SHEM OTOI ONYANGO

Dr. SHEM OTOI ONYANGO

Jomo Kenyatta University of Agriculture and Technology, Nairobi, Nairobi City, Kenya
orcid

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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9 November 2022 in Sensors
Verified
Journal Article
Open access
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SHEM OTOI ONYANGOSHEM OTOI ONYANGO
SHEM OTOI ONYANGO
SOSOLOMON AMOAH OWIREDU
SOLOMON AMOAH OWIREDU
KKKwang Il Kim
Kwang Il Kim
SYSanglok Yoo
Sanglok Yoo
The rapid development and adoption of automatic identification systems as surveillance tools have resulted in the widespread application of data analysis technology in maritime surveillance and route planning. Traditional, manual, experience-based route planning has been widely used owing to its simplicity. However, the method is heavily dependent on officer experience and is time-consuming. This study aims to extract shipping routes using unsupervised machine-learning algorithms. The proposed three-step approach: maneuvering point detection, waypoint discovery, and traffic network construction was used to construct a maritime traffic network from historical AIS data, which quantitatively reflects ship characteristics by ship length and ship type, and can be used for route planning. When the constructed maritime traffic network was compared to the macroscopic ship traffic flow, the Symmetrized Segment-Path Distance (SSPD) metric returned lower values, indicating that the constructed traffic network closely resembles the routes ships transit. The result indicates that the proposed approach is effective in extracting a route from the maritime traffic network.

4 February 2024 in Sustainability
Verified
Journal Article
Open access
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SOSOLOMON AMOAH OWIREDU
SOLOMON AMOAH OWIREDU
SHEM OTOI ONYANGOSHEM OTOI ONYANGO
SHEM OTOI ONYANGO
ESEun-A Song
Eun-A Song
KKKwang Il Kim
Kwang Il Kim
BKByung Yeop Kim
Byung Yeop Kim
KLKyounghoon LEE
Kyounghoon LEE
Accurate determination of fishing effort from Automatic Identification System (AIS) data improves catch per unit effort (CPUE) estimation and precise spatial management. By combining AIS data with catch information, a weighted distribution method is applied to allocate catches across various fishing trajectories, accounting for temporal dynamics. A Generalized Linear Model (GLM) and Generalized Additive Model (GAM) were used to examine the influence of spatial–temporal and environmental variables (year, month, Sea Surface Temperature (SST), Sea Surface Salinity (SSS), current velocity, depth, longitude, and latitude) and assess the quality of model fit for these effects on chub mackerel CPUE. Month, SST, and year exhibited the strongest relationship with CPUE in the GLM model, while the GAM model emphasizes the importance of month and year. CPUE peaked within specific temperature and salinity ranges and increased with longitude and specific latitudinal bands. Month emerged as the most influential variable, explaining 38% of the CPUE variance, emphasizing the impact of regulatory measures on fishery performance. The GAM model performed better, explaining 69.9% of the nominal CPUE variance. The time series of nominal and standardized indices indicated strong seasonal cycles, and the application of fine-scale fishing effort improved nominal and standardized CPUE estimates and model performance.

31 October 2016 in Journal of Navigation and Port Research
Verified
Journal Article
Closed access
SHEM OTOI ONYANGOSHEM OTOI ONYANGO
SHEM OTOI ONYANGO
Youngsoo ParkYoungsoo Park
Youngsoo Park
JPJin-Soo Park
Jin-Soo Park

Verified
Journal Article
Open access
PDF file
SYSanglok Yoo
Sanglok Yoo
SHEM OTOI ONYANGOSHEM OTOI ONYANGO
SHEM OTOI ONYANGO
Joo-Sung KimJoo-Sung Kim
Joo-Sung Kim
KKKwang Il Kim
Kwang Il Kim
Anchor dragging at anchorages poses a significant threat to marine traffic, potentially leading to collisions and damage to seabed infrastructure. This study analyzed a large dataset of ships in anchorage areas to develop a machine learning (ML) model that estimates the risk of anchor dragging using a binary classification system that differentiates between dragging and non-dragging incidents. Historical data from the automatic identification system (AIS), hydrographic, and meteorological sources were compiled for each case. Preliminary analysis revealed a significant class imbalance, with non-dragging cases far outnumbering dragging cases. This suggested that the optimal ML strategy would involve undersampling the majority class and cost-sensitive learning. A combination of data-undersampling methods and cost-sensitive algorithms was used to select the model with the best recall, area under the receiver operating characteristic curve (AUC), and geometric mean (GM) scores. The neighborhood cleaning rule undersampler paired with cost-sensitive logistic regression outperformed other models, achieving recall, GM, and AUC scores of 0.889, 0.767, and 0.810, respectively. This study also demonstrated potential applications of the model, discussed its limitations, and suggested possible improvements for the ML approach. Our method advances maritime safety by enabling the intelligent, risk-aware monitoring of anchored vessels through machine learning, enhancing the capabilities of vessel traffic service officers.