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Prof. Sangjun Im
Department of Forest Sciences and Research Institute of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea

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0 Wildfire
0 rainfall interception
0 soil hydraulic properties
0 Forest Hydrology
0 soil water repellency

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Review
Published: 12 July 2021 in Forests
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Cable yarding technology remains the most effective operation in steep terrain harvesting systems; however, it has limitations and challenges. Using cable yarders (tractor-, truck-, and excavator-based) to extract tree lengths and whole trees has been common since the late 20th century in South Korea, and cable yarding operations were developed in the late 1800s in the United States and Europe. Machine potential and limitations must be understood to ensure the widespread use of technology, strong cooperation, and optimal selection of machinery size. We reviewed the literature on tower yarder performances from 1990–2021 to determine the alteration of yarders and its productivity pattern and obtained 23 papers; <2 publications per year discussed the determination of cable yarding productivity. We selected independent variables (e.g., silvicultural treatment, harvesting method, and cycle log volume) for cable yarding that would likely affect productivity. Data were analyzed to compare productivities under silvicultural treatment, the harvesting method, and yarding direction and identify the interaction mechanical power (i.e., lifting capacity and machine power), yarding distance, and slope. Cable yarder productivity rates generally depended on the silvicultural treatment, harvesting method, and yarding direction, particularly in clear-cut, tree-length, and uphill yarding operation activities. The lifting capacity, machine power, and slope had no significant correlation with yarders’ productivity, particularly in thinning operations, whereas, in clear-cut productivity, it was influenced by these variables. The results contribute to improving operation activities for cable yarding systems and towards future research directions.

ACS Style

Eunjai Lee; Yunsung Choi; Minjae Cho; Koohyun Cho; Jaeheun Oh; Sangkyun Han; Sangjun Im. A Literature Review on Cable Extraction Practices of South Korea: 1990–2020. Forests 2021, 12, 908 .

AMA Style

Eunjai Lee, Yunsung Choi, Minjae Cho, Koohyun Cho, Jaeheun Oh, Sangkyun Han, Sangjun Im. A Literature Review on Cable Extraction Practices of South Korea: 1990–2020. Forests. 2021; 12 (7):908.

Chicago/Turabian Style

Eunjai Lee; Yunsung Choi; Minjae Cho; Koohyun Cho; Jaeheun Oh; Sangkyun Han; Sangjun Im. 2021. "A Literature Review on Cable Extraction Practices of South Korea: 1990–2020." Forests 12, no. 7: 908.

Journal article
Published: 29 May 2021 in Forests
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Forest fires can have a direct and immediate impact on soil properties, particularly soil water repellency. This study investigated the direct impacts of the Gangneung forest fire of 2019 on soil properties and the spatial variability of soil water repellency with vegetation burn severity in the Korean red pine (Pinus densiflora Siebold and Zucc) forest of South Korea. A total of 36 soil samples were collected at depth intervals of 0–5 cm, 10–15 cm, and 20–25 cm from three burned sites, representing surface-fuel consumption (SC), foliage necrosis (FN), and crown-fuel consumption (CC), respectively. An unburned site was also used as a control. Soil properties such as soil texture, pH, bulk density, electrical conductivity (EC), total organic carbon (TOC), and cation exchange capacity (CEC) were analyzed in the laboratory. The increase in the sand fraction near the soil surface after a fire was associated with changes in silt and clay fractions. Moderate to high vegetation burn severity at the FN and CC sites caused a decrease in soil pH due to the thermal destruction of kaolinite mineral structure, but organic matter combustion on the soil surface increased soil pH at the SC site. Forest fires led to increases in total organic carbon at the FN and SC sites, owing to the external input of heat damaged foliage and burnt materials. Molarity of an ethanol droplet (MED) tests were also conducted to measure the presence and intensity of soil water repellency from different locations and soil depths. MED tests showed that vegetation burn severity was important for determining the strength of water repellency, because severely burned sites tended to have stronger water repellency of soil than slightly burned sites. Unburned soils had very hydrophilic characteristics across soil depths, but a considerably thick hydrophobic layer was found in severely burned sites. The soil water repellency tended to be stronger on steep (>30°) slopes than on gentle (<15°) slopes.

ACS Style

Qiwen Li; Sujung Ahn; Taehyun Kim; Sangjun Im. Post-Fire Impacts of Vegetation Burning on Soil Properties and Water Repellency in a Pine Forest, South Korea. Forests 2021, 12, 708 .

AMA Style

Qiwen Li, Sujung Ahn, Taehyun Kim, Sangjun Im. Post-Fire Impacts of Vegetation Burning on Soil Properties and Water Repellency in a Pine Forest, South Korea. Forests. 2021; 12 (6):708.

Chicago/Turabian Style

Qiwen Li; Sujung Ahn; Taehyun Kim; Sangjun Im. 2021. "Post-Fire Impacts of Vegetation Burning on Soil Properties and Water Repellency in a Pine Forest, South Korea." Forests 12, no. 6: 708.

Journal article
Published: 10 November 2020 in Water
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Floor litter can reduce the amount of water reaching the soil layer through rainfall interception. The rainfall interception capacity of floor litter varies with the physical features of the litter and rainfall characteristics. This study aimed to define the maximum and minimum interception storages (Cmx, Cmn) of litter layers using rainfall simulation experiments, and examine the effects of litter type and rainfall characteristics on rainfall retention and drainage processes that occur in the litter layer. Different types of needle-leaf and broadleaf litters were used: Abies holophylla, Pinus strobus, Pinus rigida, Quercus acutissima, Quercus variabilis, and Sorbus alnifolia. Our results indicate a wide variation in interception storage values of needle leaf litter, regardless of the rainfall intensity and duration. The A. holophylla needle-leaf litter showed the highest Cmx and Cmn values owing to its short length and low porosity. Conversely, the lowest interception storage values were determined for the P. strobus needle leaf litter. No significant differences in interception storage were established for the broadleaf litter. Moreover, except for A. holophylla litter, the broadleaf litter retained more water than the needle leaf litter. An increase in the intensity or duration of rainfall events leads to an increase in the water retention storage of litter. However, these factors do not influence the litter’s drainage capacity, which depends primarily on the force of gravity.

ACS Style

Qiwen Li; Ye Eun Lee; Sangjun Im. Characterizing the Interception Capacity of Floor Litter with Rainfall Simulation Experiments. Water 2020, 12, 3145 .

AMA Style

Qiwen Li, Ye Eun Lee, Sangjun Im. Characterizing the Interception Capacity of Floor Litter with Rainfall Simulation Experiments. Water. 2020; 12 (11):3145.

Chicago/Turabian Style

Qiwen Li; Ye Eun Lee; Sangjun Im. 2020. "Characterizing the Interception Capacity of Floor Litter with Rainfall Simulation Experiments." Water 12, no. 11: 3145.

Original article
Published: 30 June 2020 in Journal of Forest Research
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Using the Soil Conservation Service (SCS) curve number (CN) procedure for estimating runoff volume on an ungauged forest watershed remains controversial because little guidance has been provided for defining appropriate CN values. In this study, alternative methods for assigning CN values (CNs) were assessed to determine whether these methods provide acceptable estimates of runoff on forested watersheds. The estimated CNs varied between the methods employed, showing the highest CN values when derived from a probabilistic method and lowest when derived from a graphical method. The tabulated CN values in Section 4 of the National Engineering Handbook (NEH-4) had relatively higher bias compared to those derived from measured rainfall-runoff data. The storm runoff volume was predicted using the assigned CNs and compared with the observations. The coefficients of determination and RMSE values between the measured and estimated runoff volumes varied with the methods employed. The highest watershed average RMSE value was obtained by the use of the tabulated CN values in NEH-4 (51.19 mm), while arithmetic mean approach provided the lowest average RMSE value of 24.38 mm, even though this method requires intensive data collection. Among the alternatives, probabilistic method was found to be the most reliable in determining CNs for forest cover with limited data. The estimated runoff largely agreed with the observations. Therefore, the revised CNs can be used for estimating storm runoff from ungauged, mountainous forests.

ACS Style

Sangjun Im; Jeman Lee; Koichiro Kuraji; Yen-Jen Lai; Venus Tuankrua; Nobuaki Tanaka; Mie Gomyo; Hiroki Inoue; Chun-Wei Tseng. Soil conservation service curve number determination for forest cover using rainfall and runoff data in experimental forests. Journal of Forest Research 2020, 25, 204 -213.

AMA Style

Sangjun Im, Jeman Lee, Koichiro Kuraji, Yen-Jen Lai, Venus Tuankrua, Nobuaki Tanaka, Mie Gomyo, Hiroki Inoue, Chun-Wei Tseng. Soil conservation service curve number determination for forest cover using rainfall and runoff data in experimental forests. Journal of Forest Research. 2020; 25 (4):204-213.

Chicago/Turabian Style

Sangjun Im; Jeman Lee; Koichiro Kuraji; Yen-Jen Lai; Venus Tuankrua; Nobuaki Tanaka; Mie Gomyo; Hiroki Inoue; Chun-Wei Tseng. 2020. "Soil conservation service curve number determination for forest cover using rainfall and runoff data in experimental forests." Journal of Forest Research 25, no. 4: 204-213.

Journal article
Published: 29 April 2020 in Sustainability
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Land cover change is a major environmental concern in the northwestern highlands of Ethiopia. This study detected land cover transitions over the past 30 years in the Chemoga basin (total area = 118,359 ha). Land cover maps were generated via the supervised classification of Landsat images with the help of the Google Earth (GE) images. A total of 218 unchanged land features sampled from GE images were used as the training datasets. Classification accuracy was evaluated by comparing classified images with 165 field observations during the 2017 field visit. The overall accuracy was 85.4% and the kappa statistic was 0.81, implying that the land classification was satisfactory. Agricultural land is the dominant land cover in the study basin, and increased in extent by 2,337 ha from 1987 to 2017. The second and third most dominant land cover types, grassland and woodland, decreased by 1.9% and 3.6%, respectively, over the past 30 years. The increase in agricultural lands was mostly due to the conversion of grasslands and woodlands, although some agricultural lands changed to Eucalyptus plantations and human settlements. The results revealed that the expansion of built-up space and agricultural lands was the major driver of fragmentation of the landscape, and degradation of natural resources in the Chemoga basin, Ethiopia.

ACS Style

Wubeshet Damtea; Dongyeob Kim; Sangjun Im. Spatiotemporal Analysis of Land Cover Changes in the Chemoga Basin, Ethiopia, Using Landsat and Google Earth Images. Sustainability 2020, 12, 3607 .

AMA Style

Wubeshet Damtea, Dongyeob Kim, Sangjun Im. Spatiotemporal Analysis of Land Cover Changes in the Chemoga Basin, Ethiopia, Using Landsat and Google Earth Images. Sustainability. 2020; 12 (9):3607.

Chicago/Turabian Style

Wubeshet Damtea; Dongyeob Kim; Sangjun Im. 2020. "Spatiotemporal Analysis of Land Cover Changes in the Chemoga Basin, Ethiopia, Using Landsat and Google Earth Images." Sustainability 12, no. 9: 3607.

Research article
Published: 31 December 2019 in Advances in Civil Engineering
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Soil erosion control dams are widely used as part of measures to reduce damage caused by debris flow all over the world. Engineering considerations are needed for proper design of erosion control dams, but in the Republic of Korea, the impact force of debris flow is not fully reflected in the current design criteria of the dam. Against this backdrop, this study was conducted to estimate the impact force of debris flow for the practical purpose of designing erosion control dam. Simulated flume experiments were performed to develop the relationship to estimate the flow velocity as well as the impact force of debris flow. Experimental results showed that increases both in sediment mixture volume and flume slope gradient led to an increase in flow velocity. Especially, it was found that as clay content increased gradually, the flume slope gradient had greater impact on the increase of flow velocity. Also, it was proved that the impact force of debris flow was well fitted to the hydrodynamic model as it showed linear correlation with the flow velocity. Then, the debris-flow velocity model was established based on the factor related to the debris-flow velocity. Finally, the dynamic model to estimate the impact force of debris flow was introduced utilizing correlations between the established debris-flow velocity model and Froude number. Both models which were developed with using statistically significant watershed characteristics succeeded in explaining the experiment results in a more accurate way compared to existing models. Therefore, it is highly expected that these models can be fully utilized to estimate impact force of debris flow which will be required to design erosion control dams in practical use through overcoming their identified limitations.

ACS Style

Song Eu; Sangjun Im; Dongyeob Kim. Development of Debris Flow Impact Force Models Based on Flume Experiments for Design Criteria of Soil Erosion Control Dam. Advances in Civil Engineering 2019, 2019, 1 -8.

AMA Style

Song Eu, Sangjun Im, Dongyeob Kim. Development of Debris Flow Impact Force Models Based on Flume Experiments for Design Criteria of Soil Erosion Control Dam. Advances in Civil Engineering. 2019; 2019 ():1-8.

Chicago/Turabian Style

Song Eu; Sangjun Im; Dongyeob Kim. 2019. "Development of Debris Flow Impact Force Models Based on Flume Experiments for Design Criteria of Soil Erosion Control Dam." Advances in Civil Engineering 2019, no. : 1-8.

Journal article
Published: 13 July 2019 in Forests
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In South Korea, logs for low-value products, such as pulpwood and fuelwood, are primarily extracted from harvest sites and transported to roadside or landing areas using small shovels. Previous studies on log extraction, however, have focused on cable yarding operations with the goal of improving productivity on steep slopes and inaccessible sites, leaving small-shovel operations relatively unexamined. Therefore, the main objectives were to determine small-shovel extraction productivity and costs and to evaluate the impact of related variables on productivity. In addition, we developed a model to estimate productivity under various site conditions. The study took place in 30 case study areas; each area has trees with stems at a diameter at breast height ranging from 18 to 32 cm and a steep slope (greater than 15%). The areas ranged from 241 to 1129 trees per hectare, with conifer, deciduous, and mixed stands. Small-shovel drives ranged from 36 to 72 m per extraction cycle from stump to landing. The results indicated that the mean extraction productivity of small-shovel operations ranged between 2.44 to 9.85 m3 per scheduled machine hour (including all delays). At the forest level, the estimated average stump-to-forest road log production costs were US $4.37 to 17.66/m3. Small-shovel productivity was significantly correlated with stem size (diameter at breast height and tree volume) and total travelled distance (TTD). However, a Pearson’s correlation analysis indicated that stand density and slope did not have a significant effect on productivity. Our findings provide insights into how stem size and TTD influence small shovel performance and the predictive ability of productivity. Further, this information may be a valuable asset to forest planners and managers.

ACS Style

Eunjai Lee; Sang-Kyun Han; Sangjun Im. Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea. Forests 2019, 10, 585 .

AMA Style

Eunjai Lee, Sang-Kyun Han, Sangjun Im. Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea. Forests. 2019; 10 (7):585.

Chicago/Turabian Style

Eunjai Lee; Sang-Kyun Han; Sangjun Im. 2019. "Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea." Forests 10, no. 7: 585.

Journal article
Published: 24 November 2017 in Remote Sensing
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Near-infrared spectroscopy (NIRS) was implemented to monitor the moisture content of broadleaf litters. Partial least-squares regression (PLSR) models, incorporating optimal wavelength selection techniques, have been proposed to better predict the litter moisture of forest floor. Three broadleaf litters were used to sample the reflection spectra corresponding the different degrees of litter moisture. The maximum normalization preprocessing technique was successfully applied to remove unwanted noise from the reflectance spectra of litters. Four variable selection methods were also employed to extract the optimal subset of measured spectra for establishing the best prediction model. The results showed that the PLSR model with the peak of beta coefficients method was the best predictor among all of the candidate models. The proposed NIRS procedure is thought to be a suitable technique for on-the-spot evaluation of litter moisture.

ACS Style

Ghiseok Kim; Suk-Ju Hong; Ah-Yeong Lee; Ye-Eun Lee; Sangjun Im. Moisture Content Measurement of Broadleaf Litters Using Near-Infrared Spectroscopy Technique. Remote Sensing 2017, 9, 1212 .

AMA Style

Ghiseok Kim, Suk-Ju Hong, Ah-Yeong Lee, Ye-Eun Lee, Sangjun Im. Moisture Content Measurement of Broadleaf Litters Using Near-Infrared Spectroscopy Technique. Remote Sensing. 2017; 9 (12):1212.

Chicago/Turabian Style

Ghiseok Kim; Suk-Ju Hong; Ah-Yeong Lee; Ye-Eun Lee; Sangjun Im. 2017. "Moisture Content Measurement of Broadleaf Litters Using Near-Infrared Spectroscopy Technique." Remote Sensing 9, no. 12: 1212.

Preprint
Published: 21 September 2017
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Near-infrared spectroscopy (NIRS) was implemented to monitor the moisture content of broadleaf litters. Partial least-squares regression (PLSR) models, incorporating optimal wavelength selection techniques, have been proposed to better predict the litter moisture of forest floor. Three broadleaf litters were used to sample the reflection spectra corresponding the different degrees of litter moisture. Maximum normalization preprocessing technique was successfully applied to remove unwanted noise from the reflectance spectra of litters. Four variable selection methods were also employed to extract the optimal subset of measured spectra for establishing the best prediction model. The results showed that the PLSR model with the peak of beta coefficients method was the best predictor among all candidate models. The proposed NIRS procedure is thought to be a suitable technique for on-the-spot evaluation of litter moisture.

ACS Style

Ghiseok Kim; Suk-Ju Hong; Ah-Yeong Lee; Ye-Eun Lee; Sangjun Im. Moisture Content Measurement of Broadleaf Litters using Near-Infrared Spectroscopy Technique. 2017, 1 .

AMA Style

Ghiseok Kim, Suk-Ju Hong, Ah-Yeong Lee, Ye-Eun Lee, Sangjun Im. Moisture Content Measurement of Broadleaf Litters using Near-Infrared Spectroscopy Technique. . 2017; ():1.

Chicago/Turabian Style

Ghiseok Kim; Suk-Ju Hong; Ah-Yeong Lee; Ye-Eun Lee; Sangjun Im. 2017. "Moisture Content Measurement of Broadleaf Litters using Near-Infrared Spectroscopy Technique." , no. : 1.

Original articles
Published: 30 June 2017 in Forest Science and Technology
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Forests are well known to control soil erosion and severe flooding. In the Democratic People's Republic of Korea (North Korea), deforestation was estimated at 20% between 1997 and 2014. This decline was mainly reflective of improper land use practices on steep slopes. Intensive deforestation and inappropriate land management can lead to severe soil erosion. The objective of this study was to describe the regional soil erosion severity in North Korea using the Revised Universal Soil Loss Equation (RUSLE) model coupled with a GIS technique. This model is widely being used to assess the potential mean annual soil erosion under different rainfall, soil characteristics, slope, and land use conditions. The results showed that the average annual rate of soil loss was estimated to be 15.8 tonnes ha−1 yr−1. Regionally, Nampo city is the most vulnerable region to soil erosion (55.1 tonnes ha−1 yr−1), followed by Hwanghaebuk-do (30.5 tonnes ha−1 yr−1), due to rapid land development. Denuded lands, which are estimated at around 6.5% of the total area, are predicted to have contributed 192.1 million tonnes yr−1 to the country's soil erosion. Participatory agroforestry and reforestation were found to be practical solutions to reduce soil erosion, particularly on degraded landscapes, and improve people's farm-based livelihoods.

ACS Style

Eunjai Lee; Sujung Ahn; Sangjun Im. Estimation of soil erosion rate in the Democratic People's Republic of Korea using the RUSLE model. Forest Science and Technology 2017, 13, 100 -108.

AMA Style

Eunjai Lee, Sujung Ahn, Sangjun Im. Estimation of soil erosion rate in the Democratic People's Republic of Korea using the RUSLE model. Forest Science and Technology. 2017; 13 (3):100-108.

Chicago/Turabian Style

Eunjai Lee; Sujung Ahn; Sangjun Im. 2017. "Estimation of soil erosion rate in the Democratic People's Republic of Korea using the RUSLE model." Forest Science and Technology 13, no. 3: 100-108.

Conference paper
Published: 11 June 2017 in Advancing Culture of Living with Landslides
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Open image in new windowConfined or channelized debris flow is one of the most powerful processes for transporting solid materials along the mountain torrent. It is defined as a type of mass movement that involves water-charged, predominantly coarse materials flowing rapidly down along a steep confined, pre-existed channel. Development of debris flow is broadly characterized by initiation, transportation, and deposition, depending on channel gradient, and size and gradation of solid mixture. In order to design debris flow control structure, exact measurement of velocity and corresponding impact force are required. Therefore, debris flow flume has been designed in this study to experimentally examine the flow characteristics of debris flow. A 200 mm (W) × 300 mm (H) × 2000 mm (L) flume has been used to conduct the experiments with a flume slope of 25°, 30°, 35°, 40°. Velocity of debris flow was estimated by image analysis of photographs, and runout length and width were measured using grids on deposition pan. Two types of debris mixture have defined, based on the portion of clay, sand, and gravel materials. Experiments showed that velocities of debris flow strongly related to flume slope, ranging 1.5–2.5 m/s. Runout length and width were affected by the flume slope and debris flow composition.

ACS Style

Sangjun Im; Song Eu; Dongyeob Kim; Matjaz Mikos; Binod Tiwari; Yueping Yin; Kyoji Sassa. Understanding Debris Flow Characteristics Using Flume Experiments. Advancing Culture of Living with Landslides 2017, 357 -361.

AMA Style

Sangjun Im, Song Eu, Dongyeob Kim, Matjaz Mikos, Binod Tiwari, Yueping Yin, Kyoji Sassa. Understanding Debris Flow Characteristics Using Flume Experiments. Advancing Culture of Living with Landslides. 2017; ():357-361.

Chicago/Turabian Style

Sangjun Im; Song Eu; Dongyeob Kim; Matjaz Mikos; Binod Tiwari; Yueping Yin; Kyoji Sassa. 2017. "Understanding Debris Flow Characteristics Using Flume Experiments." Advancing Culture of Living with Landslides , no. : 357-361.

Conference paper
Published: 18 May 2017 in Advancing Culture of Living with Landslides
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Open image in new windowDebris flow is recognized as a major natural hazard in torrent landscape over the world. Various types of control structures have been employed to capture debris flow in mountain torrents of Korea. In this study, flexible wire net dam was newly designed and implemented to retain debris flow on a small, steep mountain torrent. The dam consists of a flexible net panel, wire anchors and supporting rods to dissipate the energy of debris flow. A 500 mm × 500 mm wire panel was designed to endure the impacts of debris sediments, regarding the characteristics of streambed materials on upstream torrents. The plane stresses induced by debris impacts were uniformly distributed over the panel and subjected to the wire anchors installed in river banks. The anchors were specially designed to absorb the kinetic energy of sediment movement. Supporting rods were anchored into streambed and keep the wire panel against the sediment-induced force. Designed dam was implemented in average slope of 35° torrent of Mt. Gwanak in Seoul, Korea. The dam has a 15 m bottom width and 3 m height. Design load was estimated from the size and density of stony debris materials placed in upstream torrents. A 95-percentile diameter of sediment materials (D95) was 0.5 m in size. Maximum force acting on wire net was estimated to be 14.81 kN/m for design purpose. The flexible wire net dam has well-designed and installed in a site for preventing debris flow movement. The dam can be constructed without disturbing the stream environment and with ease, so it has environmental benefit and safety performance by reducing dangerous works for construction.

ACS Style

Sangjun Im; Seungyoub Yi; Song Eu. Implementation of a Flexible Wire Net Dam for Controlling Debris Flow in a Small Mountain Torrent. Advancing Culture of Living with Landslides 2017, 503 -511.

AMA Style

Sangjun Im, Seungyoub Yi, Song Eu. Implementation of a Flexible Wire Net Dam for Controlling Debris Flow in a Small Mountain Torrent. Advancing Culture of Living with Landslides. 2017; ():503-511.

Chicago/Turabian Style

Sangjun Im; Seungyoub Yi; Song Eu. 2017. "Implementation of a Flexible Wire Net Dam for Controlling Debris Flow in a Small Mountain Torrent." Advancing Culture of Living with Landslides , no. : 503-511.

Journal article
Published: 20 April 2016 in Journal of Earth System Science
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Wind erosion causes serious problems and considerable threat in most regions of the world. Vegetation on the ground has an important role in controlling wind erosion by covering soil surface and absorbing wind momentum. A set of wind tunnel experiments was performed to quantitatively examine the effect of canopy structure on wind movement. Artificial plastic vegetations with different porosity and canopy shape were introduced as the model canopy. Normalized roughness length (Z 0/H) and shear velocity ratio (R) were analyzed as a function of roughness density (λ). Experiments showed that Z 0/H increases and R decreases as λ reaches a maximum value, λ max, while the values of Z 0/H and R showed little change with λ value beyond as λ max.

ACS Style

Youngjoo Hong; Dongyeob Kim; Sangjun Im. Assessing the vegetation canopy influences on wind flow using wind tunnel experiments with artificial plants. Journal of Earth System Science 2016, 125, 499 -506.

AMA Style

Youngjoo Hong, Dongyeob Kim, Sangjun Im. Assessing the vegetation canopy influences on wind flow using wind tunnel experiments with artificial plants. Journal of Earth System Science. 2016; 125 (3):499-506.

Chicago/Turabian Style

Youngjoo Hong; Dongyeob Kim; Sangjun Im. 2016. "Assessing the vegetation canopy influences on wind flow using wind tunnel experiments with artificial plants." Journal of Earth System Science 125, no. 3: 499-506.

Journal article
Published: 18 November 2015 in Sustainability
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This study employs a diverse set of variables to explain slope stabilization on stable versus failure-prone revegetated cut-slopes in Korea. A field survey was conducted at potential unstable sites and stable sites using 23 variables. Through a non-parametric test of the field survey results, 15 variables were identified as primary determinants of slope failure. Of these variables, one described physical characteristics (elapsed year); four variables described vegetation properties (plant community, vegetation coverage rate, number of trees, and number of herbs); and 10 variables represented soil properties (porosity, soil hardness, water content, sand ratio and silt ratio of soil texture, tensile strength, permeability coefficient, soil depth, soil acidity, salt concentration, and organic matter). Slope angle, which was mainly considered in previous studies, of variables in physical characteristics was not statistically selected as one of the 15 variables because most of sites were located on steep slopes. The vegetation community, vegetation coverage, and number of trees influence slope stabilization. Vegetation coverage is highly correlated with other soil and vegetation variables, making it a major indicator of slope stabilization. All soil variables were related to slope failure such that subsequent slope failure was related to the method of slope revegetation rather than the environmental condition of the slope. Slope failure did not occur in revegetated slopes that matched the characteristics of the surrounding landscape and contained a large number of native trees. Most soil and vegetation variables showed differing values for whether a revegetated slope is potentially unstable or stable.

ACS Style

Sung-Ho Kil; Joongku Lee; Ho Gul Kim; Nam-Choon Kim; Sangjun Im; Gwan-Soo Park. Comparing Potential Unstable Sites and Stable Sites on Revegetated Cut-Slopes of Mountainous Terrain in Korea. Sustainability 2015, 7, 15319 -15341.

AMA Style

Sung-Ho Kil, Joongku Lee, Ho Gul Kim, Nam-Choon Kim, Sangjun Im, Gwan-Soo Park. Comparing Potential Unstable Sites and Stable Sites on Revegetated Cut-Slopes of Mountainous Terrain in Korea. Sustainability. 2015; 7 (11):15319-15341.

Chicago/Turabian Style

Sung-Ho Kil; Joongku Lee; Ho Gul Kim; Nam-Choon Kim; Sangjun Im; Gwan-Soo Park. 2015. "Comparing Potential Unstable Sites and Stable Sites on Revegetated Cut-Slopes of Mountainous Terrain in Korea." Sustainability 7, no. 11: 15319-15341.

Articles
Published: 10 May 2011 in Forest Science and Technology
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Changes in the forest landscape of Mt. Makiling Forest Reserve were evaluated given the three different time periods of remotely sensed datasets using ISOCLUST method. The classification explicitly figured out that the forest areas are persistent or still intact while spatially expanding the coverage from the area. The change analysis revealed that the spatial distribution of various land-cover categories was subjected to gain and loss based on the latest and previous remotely sensed data sets. High gains for forest areas and many losses on agroforestry areas were established at certain time spans. The land cover by category denotes a decrease of forest areas between 1993 and 2002, and eventually increases in line with the latest period. The increase in agroforestry areas was merely detected between 1993 and 2002 and subsequently reduced the possible expansion of its area coverage. A great deal of land cover can be perceived to the restoration efforts made in the study area. Applying NDVI in the segmentation process during the image classification demonstrated to be a constructive approach of classifying land cover types.

ACS Style

Marilyn S. Combalicer; Dongyeob Kim; Don Koo Lee; Edwin A. Combalicer; Rex Victor O. Cruz; Sangjun Im. Changes in the forest landscape of Mt. Makiling Forest Reserve, Philippines. Forest Science and Technology 2011, 7, 60 -67.

AMA Style

Marilyn S. Combalicer, Dongyeob Kim, Don Koo Lee, Edwin A. Combalicer, Rex Victor O. Cruz, Sangjun Im. Changes in the forest landscape of Mt. Makiling Forest Reserve, Philippines. Forest Science and Technology. 2011; 7 (2):60-67.

Chicago/Turabian Style

Marilyn S. Combalicer; Dongyeob Kim; Don Koo Lee; Edwin A. Combalicer; Rex Victor O. Cruz; Sangjun Im. 2011. "Changes in the forest landscape of Mt. Makiling Forest Reserve, Philippines." Forest Science and Technology 7, no. 2: 60-67.