스마트폰 로봇의 위치 인식을 위한 준 지도식 학습 기법

유재현(Jaehyun Yoo),김현진(H. Jin Kim) 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.6

Supervised machine learning has become popular in discovering context descriptions from sensor data. However, collecting a large amount of labeled training data in order to guarantee good performance requires a great deal of expense and time. For this reason, semi-supervised learning has recently been developed due to its superior performance despite using only a small number of labeled data. In the existing semi-supervised learning algorithms, unlabeled data are used to build a graph Laplacian in order to represent an intrinsic data geometry. In this paper, we represent the unlabeled data as the spatial-temporal dataset by considering smoothly moving objects over time and space. The developed algorithm is evaluated for position estimation of a smartphone-based robot. In comparison with other state-of-art semi-supervised learning, our algorithm performs more accurate location estimates.

Comparison between Isokinetic Peak Torque and Isotonic 1RM on the Knee Joint

유재현(Jaehyun Yoo) 물리치료재활과학회 2023 Physical therapy rehabilitation science Vol.12 No.2

Objective: Resistance exercise is a necessary element to improve quality of life, and measurement and evaluation of muscle strength provide important information for prescription and management of rehabilitation and exercise programs. This study analyzed the correlation between direct and indirect 1RM for isokinetic maximum torque of the knee joint in order to provide useful information in the field of exercise programs. In addition, the flexion-extension ratio and the difference in left-right deviation were verified. Design: A cross-sectional studyMethods: The subjects of this study were 33 healthy adult men and women without medical problems who participated in the health exercise class program at S University in Seoul. The correlation between isokinetic maximum torque and direct and indirect 1RM was analyzed, and a dependent t-test was performed to analyze the flexion-extension ratio and left-right deviation. Results: There was a high correlation between the isokinetic maximum torque and direct and indirect 1RM, and no statistically significant difference was shown between the test methods in the analysis of the flexion-extension ratio and left-right deviation. Conclusions: Isokinetic muscle function measuring equipment is expensive, so it is difficult to use it in local exercise rehabilitation and training sites. Through this study, it was found that direct and indirect 1RM isokinetic maximum torque showed a high correlation, and there was no difference in evaluating muscle function such as flexion-extension ratio and left-right deviation. Therefore, it is considered that the muscle function evaluation using 1RM in general field can be usefully utilized.

전기방사를 이용하여 제조된 산화아연 나노섬유의 직경제어 및 광촉매 특성

지명준,유재현,이영인,Ji, Myeong-Jun,Yoo, Jaehyun,Lee, Young-In 한국재료학회 2019 한국재료학회지 Vol.29 No.2

A heterogeneous photocatalytic system is attracting much interest for water and air purification because of its reusability and economical advantage. Electrospun nanofibers are also receiving immense attention for efficient photocatalysts due to their ultra-high specific surface areas and aspect ratios. In this study, ZnO nanofibers with average diameters of 71, 151 and 168 nm are successfully synthesized by facile electrospinning and a subsequent calcination process at $500^{\circ}C$ for 3 h. Their crystal structures, morphology features and optical properties are systematically characterized by X-ray diffraction, scanning electron microscopy, UV-Vis and photoluminescence spectroscopies. The photocatalytic activities of the ZnO nanofibers are evaluated by the photodegradation of a rhodamine B aqueous solution. The results reveal that the diameter of the nanofiber, controlled by changing the polymer content in the precursor solution, plays an important role in the photocatalytic activities of the synthesized ZnO nanofibers.

통합 물정보 제공을 위한 웹 GIS 기반의 SWG 시뮬레이터 설계

박용길,김계현,이성주,유재현,Park, Yonggil,Kim, Kyehyun,Lee, Sungjoo,Yoo, Jaehyun 한국공간정보학회 2015 한국공간정보학회지 Vol.23 No.1

최근 전 세계적인 기온상승과 불규칙한 이상기후로 인하여 지역간 수자원 격차 및 물부족 현상이 나타나고 있으며 미래 물 수급의 안정성 확보를 위한 수자원 관리가 점차 중요해지고 있다. 이를 해결하기 위해 수자원의 안정적인 확보와 관리가 가능한 방안으로 대두되고 있는 Smart Water Grid (SWG) 연구가 진행되고 있다. 따라서 본 연구에서는 웹 환경에서 통합 물정보 제공을 위한 GIS 기반의 SWG 시뮬레이터를 설계하고자 하였다. 시스템 개발을 위해 사용자 요구분석을 기반으로 SWG 현황 조회, 미래 예측 및 정수장 현황 조회기능을 설계하였으며 사용자의 이해를 높이기 위해 GIS 및 HTML5 기술을 이용한 정보표출 기술을 적용하였다. 또한 비상 상황이 발생했을 때 SWG를 이용한 문제 해결 과정을 확인할 수 있도록 시나리오 재현 기능을 설계하였다. 시스템 개발을 위한 설계도로 Use-case, Class, Sequence diagram을 작성하고 최종 개발 내용을 확인하기 위한 스토리보드를 작성하였다. 본 연구를 통해 설계된 SWG 시뮬레이터는 기후변화 대응을 위한 물관리를 지원하기 위한 정보의 획득을 도울 뿐 아니라 시나리오 재현을 통한 의사결정자의 결정을 도울 수 있을 것으로 판단된다. 주요 기능이 수자원 관리자 및 생산자 위주로 설계되었지만 향후 소비자를 위한 콘텐츠와 기능을 추가로 개발하여 단방향 정보 전달이 아닌 양방향 정보 교환이 가능하도록 해야 할 것이다. Due to the global warming and unstable abnormal climate changes, water resources differences between regions and water shortage are occurring. Therefore, the water resources management is becoming more important for the stable securement of future water supply and demand. Researches on Smart Water Grid (SWG), which is considered as a new method, that can stably secure and maintain the water resources, are actively being conducted but it is still in infancy. Thus, this study aimed to design SWG simulator based on GIS in order to provide integrated water information in web environment. The user's requirements were analyzed for system development and important functions such as SWG current situation checking, future prediction, filtration plant situation checking functions were designed and data expression techniques using GIS and HTML5 were applied to enhance the understanding of the users. Also, when the emergency situations occurred, the solving process of the situations are reproduced to check the solution process using scenario reproduction functions. Use-case, class, sequence diagram, which are a design for real system development and defines the system usage contents of users, were written, and the story board was written to check the final development contents. This study designed a SWG simulator in order to support the water maintenance reacting to climate changes. The development of system is expected to help securing information to deal with emergency situations such as water shortage and help the decision maker to make decision through reproduction of scenario. The major functions were designed for the convenience of water resource manager and producer but new contents for consumers must be developed to enable duplex information transmission.

딥러닝 기법을 이용한 담수역남조류 공간 모니터링

남기범(Gibeom Nam),유재현(Jaehyun Yoo),박상현(Sanghyun Park),송현오(Hyunoh Song),신현주(Hyunjoo Shin),강태구(Taegu Kang),이재관(Jaekwan Lee) 대한환경공학회 2020 대한환경공학회 학술발표논문집 Vol.2020 No.11

서울시 일부 고등학생의 과민대장증후군 유병률과 위험 요인

이경태(Kyung Tae Lee),유재현(Jaehyun Yoo),김보경(Kyoung Kim),정해관(Hae-Kwan Cheong) 한국역학회 2007 Epidemiology and Health Vol.29 No.1

  Background and Objectives: Irritable bowel syndrome (IBS) is prevalent in the general population, but there are few reports on bowel habits and IBS in high school students in Korea. This study aims to describe the prevalence of IBS in high school students in Korea and to investigate the influence of lifestyle factors including dietary habits, on the IBS. This study also investigates relationship between anxiety, depression and IBSprevalence.   Subjects and methods:This study is a cross-sectional study on 1,018 students (451 males and 567 females) form freshman to senior of a high schools in Seoul. All students were requested to fill in a self-reported questionnaire. IBS was diagnosed based on the Rome Ⅱ criteria. Those having past medical history of organic gastrointestinal disorders and any one of the "alarm factors"(e.g. continuous hematochezia, weight loss, or anemic symptom) were excluded from the IBS group. For the evaluation of risk factors on the IBS, we surveyed dietary habit, health behavior, past medical history, the Hollingshed index for the measurement of socioeconomic status, Beck"s Anxiety Inventory for the anxiety, and the Children"s Depression Inventory for the depression.   Results: The prevalence of IBS was 19.1%. Family history of abdominal discomfort (odds ratio 2.07, 95% 1.46-2.92) and having night snack (odds ratio 1.46, 95% CI 1.09-1.94) were significantly different between the IBS group and non-IBS group. There was a linear trend towards the higher prevalence of IBS with fewer hours of exercise (odds ratio 0.99, 95% CI 0.95-1.04). Menstruation, stress, and irregular eating were the significant provocation factors of IBS. Anxiety and depression was not significantly higher in in the IBS group.   Conclusions: Prevalence of the IBS in high school students from this study was higher compared with those reported in college students in Korea. This study shows that family history, dietary factors, lifestyle, and grade were significantly related to IBS. From our study, we found that there are multifaceted health aspects required to reduce symptoms, such as dietary education and encouragement to change lifestyle for controlling stress.

가우시안 프로세스를 이용한 다중 로봇 분산 시스템의 환경 모델 학습

장도현(Dohyun Jang),유재현(Jaehyun Yoo),김현진(H. Jin Kim) 한국통신학회 2020 한국통신학회 학술대회논문집 Vol.2020 No.8

대역폭 제한이 있는 네트워크 제어 시스템을 위한 이벤트 기반 예측 제어 기법 연구

장도현(Dohyun Jang),유재현(Jaehyun Yoo),김현진(H. Jin Kim) 한국통신학회 2020 한국통신학회 학술대회논문집 Vol.2020 No.2

화재 대피를 위한 배리어 프리 시스템 현황과 공간구성 연구

김소연(Soyeon Kim),유재현(Jaehyun Yoo),이상원(Sangwon Lee) 한국HCI학회 2021 한국HCI학회 학술대회 Vol.2021 No.1

재난 발생 시 노인, 장애인 등의 취약특성으로 인한 피해가 크게 나타나면서 안전취약계층의 보호에 대한 문제가 제기되고있지만 관련 법제도 등의 일부만 개정되고 있을 뿐 대부분 일반인을 대상으로 적용되고 있어 관련 법령 및 제도와 매뉴얼 등의 정비에 대한 필요성이 중요하게 대두되고 있다. 이에 따라 본 연구는 재난취약계층인 대형 병원 환자들의 재난관리 및 지원에 관한 연구가 상당부문 공백으로 남아있다는 문제의식 하에, 국내 장애인 및 노인 재난안전 관련법과 제도 및 지원체계를 분석하고 이에 따라 신촌세브란스병원의 공간을 예시로 재구성 하여 재난관리정책 방향을 설정하기 위한 기초자료를 Agent-based Modeling 시뮬레이션 을 통해 기초자료를 제공한다.

퍼지논리 기반 실시간 전류, 전압 특성을 활용한 과전류 계전기 정정 방법에 관한 연구

신동엽(Dongyob Shin),윤명석(Myungseok Yoon),유재현(Jaehyun Yoo),노주안(Juan Noh),최승연(Sungyun Choi) 한국조명·전기설비학회 2022 한국조명·전기설비학회 학술대회논문집 Vol.2022 No.11