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병원종사자의 VDT증후군 자각증상과 건강영향에 관한 연구
이승환,정병곤,이규찬,이광철,배성복,Lee, SeungHwan,Jeong, Byeong Gon,Lee, Gyu Chan,Lee, Gwang Cheol,Bae, Seong Bock 대한핵의학기술학회 2012 핵의학 기술 Vol.16 No.2
Purpose : This study aims to examine hospital employees' subjective symptoms of VDT syndrome (Video display terminal syndrome) and figure out their effects on health conditions and correlations. Materials and Methods : This study used a structured self-administering questionnaire and gained data from 125 subjects. The questionnaire consists of total 62 questions, and they went through real number, percentage, ${\chi}^2$-terst, t-test, one-way ANOVA, and logistic regression analysis. Results : Regarding the difference in the types of subjective symptoms of VDT syndrome by jobs, there was statistically significant difference in ophthalmic symptoms, systemic symptoms, and musculoskeletal symptoms. About the correlation between the subjective symptom points of VDT syndrome by the types of symptoms, there was statistically significant correlation all in skin trouble, backache, upper limb muscle pain, lower limb muscle pain, fatigue in the head and eyes, and depression or anxiety disorders. There was significant correlation between the subjective symptom points of VDT syndrome and subjective health conditions. Conclusion : Hospital employees' subjective health conditions had significant correlation with subjective symptom points of VDT syndrome. This result shows that as radiologists' and also other hospital employees' working conditions change into VDT environment, VDT syndrome gradually appears more and more. This implies that it is needed to designate not only radiologists but also all the other hospital employees as jobs exposed to the working environment of VDT syndrome and provide preventive measures, education, and publicity for it afterwards.
랜섬웨어 탐지를 위한 동적 분석 자료에서의 변수 선택 및 분류에 관한 연구
이승환,황진수,Lee, Seunghwan,Hwang, Jinsoo 한국통계학회 2018 응용통계연구 Vol.31 No.4
최근 랜섬웨어는 일반 PC 사용자에 비해 상대적으로 수준 높은 보안 체계를 갖추고 있는 기업과 정부 기관에 침입하여 상당한 피해를 입히는 등 기존 보안 체계의 허점을 찾아 진화하는 모습을 보이고 있다. 이처럼 계속해서 변화하는 랜섬웨어를 탐지하기 위해 랜섬웨어의 특징을 파악하는 정적 분석과 동적 분석과 관련된 연구가 활발히 이루어지고 있다. 본 연구에서는 582개의 랜섬웨어 샘플과 942개의 정상 샘플 프로그램을 쿠쿠 샌드박스 가상환경 내에서 실행시킨 뒤, PC에서 이루어지는 30,967가지의 행동 여부를 기록한 동적 분석 자료를 활용하여 랜섬웨어 분류에 유의한 변수를 탐색하기 위한 여러 변수 선택 방법의 적용과 랜섬웨어 분류를 위한 기계학습 모형들을 구축하고자 하였다. 변수 선택법으로 LASSO와 이항변수 만으로 이루어진 고차원 자료라는 특성을 활용하기 위한 카이제곱검정을 이용한 변수 선택, 선행 연구에서 이용된 방법인 상호정보를 이용한 변수 선택법을 적용하였으며 기계 학습 모형으로는 능형 로지스틱 회귀, 서포트 벡터 머신, 랜덤 포레스트, XGBoost가 활용되었다. 연구 결과, 정상 프로그램과 구별되는 랜섬웨어 프로그램만의 특징적인 행동을 확인할 수 있었으며 여러 변수 선택법과 기계학습 분류 모형들의 조합 중, 주어진 자료에서 카이제곱검정을 이용한 변수 선택법과 랜덤 포레스트 모형의 조합이 가장 높은 탐지율과 정분류율을 보이는 것을 확인하였다. Attacking computer systems using ransomware is very common all over the world. Since antivirus and detection methods are constantly improved in order to detect and mitigate ransomware, the ransomware itself becomes equally better to avoid detection. Several new methods are implemented and tested in order to optimize the protection against ransomware. In our work, 582 of ransomware and 942 of normalware sample data along with 30,967 dynamic action sequence variables are used to detect ransomware efficiently. Several variable selection techniques combined with various machine learning based classification techniques are tried to protect systems from ransomwares. Among various combinations, chi-square variable selection and random forest gives the best detection rates and accuracy.
자동차 거주성 평가를 위한 감성공학/인간공학적 가이드라인 개발
이승환(Seunghwan Lee),김수환(Soohwan Kim),박범(Peom Park),이동하(Dhongha Lee),유재우(Jaewoo Yoo),나건(Keoun Nah),백승렬(Seungyoul Paik) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Consumers have benn interested in Roominess of car. Almost every car makers direct their efforts to enlarge vehicle interior roominess. Until now, the first method of enlarging roominess of vehicle is only enlarging interior dimensions; Legroom, Headroom, Shoulder room and so on. Many consumers do not feel so large despite of large interior physical dimensions. Therefore, we determine the definition of roominess as a perception and find the relation between roominess as a perception and physical dimension which applied in the early period of vehicle design by consumer's survey. Statistics methods have been used for analyzing survey results.
고속 자율 주행 차량의 고자유도 모델 기반 조향제어 알고리즘 개발
이승환(Seunghwan Lee),임승국(Seungkuk Lim),소민우(Minwoo Sho),권재준(Jaejoon Kwon),홍태욱(Taewook Hong),박기홍(Kihong Park) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11
This paper is study of steering control for path tracking of autonomous vehicle. One of the core technologies of autonomous vehicle is steering control technology for accurate path tracking. Conventional steering control algorithms have been applied for controlling the low-speed driving. Steering control on the low-speed driving is possible by using the 2-D.O.F. model. To prepare for a variety of driving conditions, steering control algorithms for high-speed driving should be developed. But, cornering stiffness and lateral load transfer by roll should be considered for controlling the high-speed driving. In order to reflect these factors for controlling the high-speed driving, the steering control algorithm based on nonlinear 3-D.O.F. model should be developed. For verifying the developed algorithm, developed steering control algorithm based on nonlinear 3-D.O.F. was compared with conventional steering control algorithm.