Chang-Sik Son

Dr. Chang-Sik Son

Daegu Gyeongbuk Institute of Science and Technology (DGIST)
orcid

Research Focus & Metrics

Academic Career Length

23Years (2004-Present)

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

Representative Publications

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1 October 2012 in Journal of Biomedical Informatics
Verified
Journal Article
Closed access
Chang-Sik SonChang-Sik Son
Chang-Sik Son
YKYoon-Nyun Kim
Yoon-Nyun Kim
HKHyung-Seop Kim
Hyung-Seop Kim
HPHyoung-Seob Park
Hyoung-Seob Park
MKMin-Soo Kim
Min-Soo Kim

13 March 2012 in BMC Medical Informatics and Decision Making
Verified
Journal Article
Open access
PDF file
Chang-Sik SonChang-Sik Son
Chang-Sik Son
Byoung Kuk JangByoung Kuk Jang
Byoung Kuk Jang
SSSuk Tae Seo
Suk Tae Seo
MKMin Soo Kim
Min Soo Kim
YKYoon Nyun Kim
Yoon Nyun Kim
Background: The aim of this study is to develop a simple and reliable hybrid decision support model by combining statistical analysis and decision tree algorithms to ensure high accuracy of early diagnosis in patients with suspected acute appendicitis and to identify useful decision rules. Methods: We enrolled 326 patients who attended an emergency medical center complaining mainly of acute abdominal pain. Statistical analysis approaches were used as a feature selection process in the design of decision support models, including the Chi-square test, Fisher's exact test, the Mann-Whitney U-test (p < 0.01), and Wald forward logistic regression (entry and removal criteria of 0.01 and 0.05, or 0.05 and 0.10, respectively). The final decision support models were constructed using the C5.0 decision tree algorithm of Clementine 12.0 after pre-processing. Results: Of 55 variables, two subsets were found to be indispensable for early diagnostic knowledge discovery in acute appendicitis. The two subsets were as follows: (1) lymphocytes, urine glucose, total bilirubin, total amylase, chloride, red blood cell, neutrophils, eosinophils, white blood cell, complaints, basophils, glucose, monocytes, activated partial thromboplastin time, urine ketone, and direct bilirubin in the univariate analysis-based model; and (2) neutrophils, complaints, total bilirubin, urine glucose, and lipase in the multivariate analysis-based model. The experimental results showed that the model with univariate analysis (80.2%, 82.4%, 78.3%, 76.8%, 83.5%, and 80.3%) outperformed models using multivariate analysis (71.6%, 69.3%, 73.7%, 69.7%, 73.3%, and 71.5% with entry and removal criteria of 0.01 and 0.05; 73.5%, 66.0%, 80.0%, 74.3%, 72.9%, and 73.0% with entry and removal criteria of 0.05 and 0.10) in terms of accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and area under ROC curve, during a 10-fold cross validation. A statistically significant difference was detected in the pairwise comparison of ROC curves (p < 0.01, 95% CI, 3.13-14.5; p < 0.05, 95% CI, 1.54-13.1). The larger induced decision model was more effective for identifying acute appendicitis in patients with acute abdominal pain, whereas the smaller induced decision tree was less accurate with the test data. Conclusions: The decision model developed in this study can be applied as an aid in the initial decision making of clinicians to increase vigilance in cases of suspected acute appendicitis.

1 October 2021 in IEEE Journal of Biomedical and Health Informatics
Verified
Journal Article
Open access
Chang-Sik SonChang-Sik Son
Chang-Sik Son
WKWon-Seok Kang
Won-Seok Kang
Jong-Ha LeeJong-Ha Lee
Jong-Ha Lee
KMKyoung Ja Moon
Kyoung Ja Moon
This study aimed to develop accurate and explainable machine learning models for three psychomotor behaviors of delirium for hospitalized adult patients. A prospective pilot study was conducted with 33 participants admitted to a long-term care facility between August 10 and 25, 2020. During the pilot study, we collected 560 cases that included 33 clinical variables and the survey items from the short confusion assessment method (S-CAM), and developed a mobile-based application. Multiple machine learning algorithms, including four rule-mining algorithms (C4.5, CBA, MCAR, and LEM2) and four other statistical learning algorithms (LR, ANNs, SVMs with three kernel functions, and random forest), were validated by paired Wilcoxon signed-rank tests on both macro-averaged F1 and weighted average F1-measures during the 10-times stratified 2-fold cross-validation. The LEM2 algorithm achieved the best prediction performance (macro-averaged F1-measure of 49.35%; weighted average F1-measure of 96.55%), correctly identifying adult patients at delirium risk. In the pairwise comparison between predictive powers observed from independent models, the LEM2 model showed a medium or large effect size between 0.4925 and 0.8766 when compared with LR, ANN, SVM with RBF, and MCAR models. We have confirmed that acute consciousness in S-CAM assessment is closely associated with different predictors for screening three psychomotor behaviors of delirium: 1) education level, dementia type or its level, sleep disorder, dehydration, and infection in mixed-type delirium; 2) gender, education level, dementia type, dehydration, bedsores, and foley catheter in hyperactive delirium; and 3) pain, sleep disorder, and haloperidol use in hypoactive delirium.

1 June 2012 in Measurement
Verified
Journal Article
Closed access
MKMin Soo Kim
Min Soo Kim
YCYoung Chang Cho
Young Chang Cho
SSSuk-Tae Seo
Suk-Tae Seo
Chang-Sik SonChang-Sik Son
Chang-Sik Son
YKYoon-Nyun Kim
Yoon-Nyun Kim

1 January 2016 in Journal of Korean Academy of Nursing
Verified
Journal Article
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PDF file
MCMoon Jong Choi
Moon Jong Choi
Chang-Sik SonChang-Sik Son
Chang-Sik Son
JKJinsu Kim
Jinsu Kim
YHYeongmi Ha
Yeongmi Ha
Choi MJ, et al. J Korean Acad Nurs. 2016 Feb;46(1):69-78. https://doi.org/10.4040/jkan.2016.46.1.69

13 September 2023 in Bioengineering
Verified
Journal Article
Open access
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Chang-Sik SonChang-Sik Son
Chang-Sik Son
WKWon-Seok Kang
Won-Seok Kang
This study introduces a novel convolutional neural network (CNN) architecture, encompassing both single and multi-head designs, developed to identify a user’s locomotion activity while using a wearable lower limb robot. Our research involved 500 healthy adult participants in an activities of daily living (ADL) space, conducted from 1 September to 30 November 2022. We collected prospective data to identify five locomotion activities (level ground walking, stair ascent/descent, and ramp ascent/descent) across three terrains: flat ground, staircase, and ramp. To evaluate the predictive capabilities of the proposed CNN architectures, we compared its performance with three other models: one CNN and two hybrid models (CNN-LSTM and LSTM-CNN). Experiments were conducted using multivariate signals of various types obtained from electromyograms (EMGs) and the wearable robot. Our results reveal that the deeper CNN architecture significantly surpasses the performance of the three competing models. The proposed model, leveraging encoder data such as hip angles and velocities, along with postural signals such as roll, pitch, and yaw from the wearable lower limb robot, achieved superior performance with an inference speed of 1.14 s. Specifically, the F-measure performance of the proposed model reached 96.17%, compared to 90.68% for DDLMI, 94.41% for DeepConvLSTM, and 95.57% for LSTM-CNN, respectively.