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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.
Delay 정보를 이용한 LTE 기지국의 Power Saving 메커니즘
이승환(Seunghwan Lee),이승형(Seunghyong Rhee),최용훈(Yonghoon Choi),박수원(Suwon Park) 한국정보과학회 2010 정보과학회논문지 : 정보통신 Vol.37 No.3
시스템에서 UE의 QoS를 보장하면서 효율적인 power saving을 위해 본 논문에서는 delay 정보를 이용하여 3GPP(Third Generation Partnership Project) 규격에서 제시한 DRX/DTX(Discontinuous. Reception/Transmission)의 차등적 적용 MAC 프로토콜을 제안한다. 제안한 MAC 프로토콜은 LTE 기지국에서 각 UE의 QoS를 고려하여 적응적으로 DRX/DTX 주기를 제어한다. UE의 패킷 delay가 적은 경우에 DRX/DTX 주기를 늘려 에너지를 절약하고 패킷 delay가 커지면 기지국의 DRX/DTX 주기를 줄여 delay를 줄이고 UE의 QoS를 보장한다. DRX/DTX의 차등적용에 따른 모의실험 결과 제안된 power saving 방식은 DRX/DTX를 상황에 따라 변화시키지 않는 방식에 비해 개선된 power saving 성능을 제공하며 특히 상황에 맞게 DRX/DTX를 설정하여 UE의 요구사항을 충족시킬 수 있다. 본 논문에서는 LTE 기지국과 UE가 통신하는 환경에서 기지국의 에너지를 절약할 수 있는 MAC protocol을 제안하고 시뮬레이션을 통하여 성능이 향상되었음을 확인한다. This thesis proposes a power saving MAC protocol for LTE base station which utilizes different graded DRX/DTX(Discontinuous. Reception/Transmission) that specified by 3GPP(Third Generation Partnership Project). Considering QoS in UE, proposed MAC protocol controls adaptive DRX/DTX cycle. When Packet delay of UE is less than normal time, LTE base station economize power by increasing DRX/DTX. When Packet delay of UE is more than normal time, delay of UE is decreased by guaranteed QoS. It depends on the traffic which is sent by UE. The proposed method is more improve power saving performance than another method which is unchanged DRX/DTX by conditions. Especially when set DRX/DTX up in conditions, it will meet the requirements of UE. In this thesis, I propose an power saving MAC protocol in an environment where LTE base station are communicated with UE and prove improvement in performance through simulations.
스포츠 팀과 스폰서 기업의 ESG 활동이 자신 및 스폰서십 파트너의 이미지에 미치는 영향 : 쌍방향의 이미지 전이를 통한 시너지 효과를 중심으로
이승환(Lee, Seunghwan) 한국체육과학회 2022 한국체육과학회지 Vol.31 No.5
This study aimed to examine the effect of sport teams’ ESG on their own and their sponsors’ image and the effect of sponsors’ ESG on their own and their teams’ image. In addition, this study tried to explore the relative effectiveness of concurrent ESG of both sport teams and sponsors over sport teams’ and sponsors’ ESG on their own and their sponsorship partners’ image. For this purpose, t-tests and ANOVAs with multiple comparisons tests were conducted with scenarios that represent 5 experimental conditions(n=510). The results of this study are as follows. First, sport teams’ ESG had a positive effect on their own and their sponsors’ image through traditional, unidirectional image transfer. Second, sponsors’ ESG had a positive effect on their own and their teams’ image through reverse image transfer. Third, concurrent ESG of both sport teams and sponsors led to higher sport teams’ and sponsors’ image through bilateral image transfer than sport teams’ and sponsors’ ESG. These findings provide both sport marketers and sponsor marketers with insight into how they develop ESG strategies that enhance sport teams’ and sponsors’ image in sport sponsorship.
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.