누설자속기반 가설기자재 손상 탐지를 위한 센서헤드 설계 및 이미지화 기법

김한선(Kim, Hansun),김태헌(Kim, Taeheon),문세범(Mun, Sebum),박승희(Park, Seunghee) 대한토목학회 2022 대한토목학회 학술대회 Vol.2022 No.10

유한요소 해석을 이용한 PS 텐던 외부 자화용 센서 설계 및 검증

김한선 ( Kim Hansun ),문세범 ( Sebum Mun ),박승희 ( Park Seunghee ) 한국구조물진단유지관리공학회 2021 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.25 No.2

현재 공용중인 PSC I형 거더 교량의 경우 공용연수에 따라 노후화되어 안전등급이 지속적으로 낮아지고 있지만, 안전도의 핵심인 PSC 교량의 내부 PS 텐던의 긴장 응력은 거더 성능 관리에 있어 매우 중요한 요소이나 현재 시행하고 있는 정밀안전진단방법의 경우 정확한 정보를 파악하기 어려워 관리가 이루어지지 않는 실정이다. 따라서 본 연구에서는 유한요소 해석을 이용하여 외부 비접촉형 EM 센서를 검증하고, PS 텐던의 외부 자화를 위한 원거리 자기장 및 긴장 응력 계측용 센서를 설계하였다. 그 결과를 바탕으로 센서를 제작하였고, 양측 자화 코일의 거리는 I형 거더의 하부 두께를 고려하여 양측 자화 코일의 거리를 약 1.5[m]로 설정하였으며 유한요소 해석 결과를 토대로 외부자화 시스템을 설치하여 이를 검증하였다.

위성 간 통신을 이용한 한국형 위성항법시스템의 궤도 및 시각 바이어스 추정

김기민(Gimin Kim),최진행(Jin Haeng Choi),박찬덕(Chandeok Park),천세범(Sebum Chun) 한국항공우주학회 2019 한국항공우주학회 학술발표회 논문집 Vol.2019 No.11

Estimation of Angular Acceleration By a Monocular Vision Sensor

Lim, Joonhoo,Kim, Hee Sung,Lee, Je Young,Choi, Kwang Ho,Kang, Sung Jin,Chun, Sebum,Lee, Hyung Keun The Institute of Positioning 2014 Journal of Positioning, Navigation, and Timing Vol.3 No.1

Recently, monitoring of two-body ground vehicles carrying extremely hazardous materials has been considered as one of the most important national issues. This issue induces large cost in terms of national economy and social benefit. To monitor and counteract accidents promptly, an efficient methodology is required. For accident monitoring, GPS can be utilized in most cases. However, it is widely known that GPS cannot provide sufficient continuity in urban cannons and tunnels. To complement the weakness of GPS, this paper proposes an accident monitoring method based on a monocular vision sensor. The proposed method estimates angular acceleration from a sequence of image frames captured by a monocular vision sensor. The possibility of using angular acceleration is investigated to determine the occurrence of accidents such as jackknifing and rollover. By an experiment based on actual measurements, the feasibility of the proposed method is evaluated.

캠리스엔진의 가변 밸브 타이밍에 따른 성능특성에 관한 연구

김성수(Seongsoo Kim),최세범(Sebum Choi) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

Variable intake and exhaust valve timing control in an Internal Combustion engine affects the fuel efficiency, power output, and emission. The typical examples are VVT system. However, the VVT system has a limitation for fully control the variable intake and exhaust valve timing. Recently, A Camless Engine which can control the intake and exhaust valve with a hydraulic actuator excluding camshaft, and enables fully variable valve control has been studied. Because the Camless Engine can fully control the intake and exhaust valve timing, valve duration, valve lift, and valve deactivation, it overcomes the limitations of the existing VVT engine, and improves extremely engine performance and emission characteristics. In this study, Camless system was applied to motorcycle engine using numerical analysis program "Ricardo WAVE" and it was analyzed the Idle stability, engine performance, and emission according to variable intake valve close timing on Idle condition.

AIP를 지원할 수 있는 아파트단지 주민공동 외부공간 리디자인에 관한 연구

모세범 ( Mo¸ Sebum ),김주연 ( Kim¸ Jooyun ),이현성 ( Lee¸ Hyunseung ) 한국공간디자인학회 2020 한국공간디자인학회논문집 Vol.15 No.6

(Background and Purpose) The purpose of this study was to suggest ways to support Aging in Place (AIP) in response to the rapidly aging Korean society. AIP allows for continuation and maintenance of living for the elderlies in their familiar environments. Currently, the only solution to changing the outdoor space in old apartment complexes is creation of a new environment through reconstruction of the whole complex. However, reconstruction results in changes in residents and creates a real gap in the environment for various generations. Despite of the high proportion of elderlies who want to continue to live in the same space, it is inevitable that the outdoor space faces a realistic issues of institutional and practical problems. This study has its purpose on providing direction for the outdoor space of the apartment complex through redesigning of the original space rather than creating a new one to meet the needs of the elderly population. (Research Scope and Methods) This study examined the concept of AIP and the theoretical consideration of the facilities for the elderly in the outdoor space of the apartment complex. Based on the analysis, five complexes with a high ratio of elderly residents and built more than 20 year ago were selected. Analysis of the current status data and on-site empirical surveys were performed, and improvement strategies to solve the problem and actualize the solutions were provided. (Result) The plan was to exclude the creation of new outdoor spaces through reconstruction and to change the outdoor spaces for the elderly during their residence. Conclusions were drawn from literature review, analysis of current status, field survey, and redesign planning. The need for changes in outdoor space due to aging and the preference for walking were derived, and this indicates that the outdoor space may be utilized more when located in the complex than in other available spaces such as a park. Additionally, due to the aging population and the decrease in the youth population, some of the lowly utilized and neglected outdoor space is proposed to be changed to meet the purposes of improving the activities of all generations including the elderly. Lastly, the study proposes improvement in laws and systems to support the reconstruction of outdoor spaces in residential complexes of more than 20 years old. (Conclusion) To respect the ‘right to grow old where one lives’, institutional support and change of perception are needed to differentiate the external spaces of the apartment complex. It is expected that if an opportunity to change the space that cannot necessarily be reconstructed is given, this will provide an environment in which the elderly residents can still live in their same spaces without having to move somewhere else.

Parameter Estimation for Multipath Error in GPS Dual Frequency Carrier Phase Measurements Using Unscented Kalman Filters

Eunsung Lee,Sebum Chun,Young Jae Lee,Teasam Kang,Gyu-In Jee,Jeongrae Kim 대한전기학회 2007 International Journal of Control, Automation, and Vol.5 No.4

This paper describes a multipath estimation method for Global Positioning System (GPS) dual frequency carrier phase measurements. Multipath is a major error source in high precision GPS applications, i.e., carrier phase measurements for precise positioning and attitude determinations. In order to estimate and remove multi path at carrier phase measurements, an array GPS antenna system has been used. The known geometry between the antennas is used to estimate multi path parameters. Dual frequency carrier phase measurements increase the redundancy of measurements, so it can reduce the number of antennas. The unscented Kalman filter (UKF) is recently applied to many areas to overcome some of the limitations of the extended Kalman filter (EKF) such as weakness to severe nonlinearity. This paper uses the UKF for estimating multi path parameters. A series of simulations were performed with GPS antenna arrays located on a straight line with one reflector. The geometry information of the antenna array reduces the number of estimated multipath parameters from four to three. Both the EKF and the UKF are used as estimation algorithms and the results of the EKF and the UKF are compared. When the initial parameters are far from true parameters, the UKF shows better performance than the EKF.

A Study on the Joint Effect of Country Image & Brand Image on Brand Preference

Weiwei Jia,Sebum Kim 한국서비스경영학회 2008 한국서비스경영학회 학술대회 Vol.2008 No.8

저고도 전리권 관측을 위한 사운딩 로켓 실험용 IAMMAP(Ionospheric Anomaly Monitoring by Magnetometer And Plasma-Probe)의 과학적 목표와 임무 설계

Jimin Hong,Yoon Shin,Sebum Chun,Sangwoo Youk,Jinkyu Kim,Wonho Cha,Seongog Park,Seunguk Lee1,Suhwan Park,Jeong-Heon Kim,KWANG-SUN RYU 한국우주과학회 2024 우주기술과 응용 Vol.4 No.2

Sounding rockets are cost-effective and rapidly deployable tools for directly exploring the ionosphere and microgravity environments. These rockets achieve their target altitudes quickly and are equipped with various scientific instruments to collect real-time data. Perigee Aerospace plans its inaugural test launch in the first half of 2024, followed by a second performance test launch in January 2025. The second launch, scheduled off the coast of Jeju Island, aims to reach an altitude of approximately 150 km with a payload of 30 kg, conducting various experiments in the suborbital region. Particularly in mid-latitude regions, the ionosphere sporadically exhibits increased electron densities in the sporadic E layers and magnetic fluctuations caused by the equatorial electrojet. To measure these phenomena, the sounding rocket version of ionospheric anomaly monitoring by magnetometer and plasma-probe (IAMMAP), currently under development at the KAIST Satellite Research Center, will be onboard. This study focuses on enhancing our understanding of the mid-latitude ionosphere and designing observable missions for the forthcoming performance tests. 사운딩 로켓은 저렴한 비용과 빠른 개발 기간을 통해 전리권이나 무중력 환경을 직접 탐사하는 유용한 도구이다. 이러한 로켓은 목표 고도에 신속하게 도달하며, 다양한 과학적 장비를 탑재하여 데이터를 실시간으로 수집할 수 있다. 페리지에어로스페이스㈜는 2024년 상반기에 첫 시험 발사를 진행한 뒤, 2025년 1월경에는 2차 성능시험 사운딩 로켓을 발사할 예정이다. 이 로켓은 제주 해상에서 발사될 예정이며, 약 150 km의 목표 고도에 총 30 kg의 탑재체를 싣고, 준궤도 영역에서 다양한 실험을 수행할 것이다. 특히, 중위도 지역의 전리권에서는 간헐적으로 전자 밀도가 증가하는 스포라딕 E층과 적도 전기제트에 의한 자기장의 미세변화를 관측할 수 있을 것으로 예상된다. 이러한 관측을 위해 KAIST 인공위성연구소에서 개발 중인 탑재체 IAMMAP(ionospheric anomaly monitoring by magnetometer and plasma-probe)의 사운딩로켓 버전이 발사체에 실릴 예정이다. 본 연구는 중위도 지역의 전리권에 대해서 이해하고, 2차 성능시험에서의 관측 가능한 임무 설계에 중점을 두고자 한다.

Performance Improvement of the Wald Test for GPS RTK with the Assistance of INS

Mamoun F. Abdel-Hafez,Dae Je Kim,Eunsung Lee,Sebum Chun,Young Jae Lee,Taesam Kang,Sangkyung Sung 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.4

To use the Global Positioning System (GPS) carrier phase measurement for precise positioning, the integer ambiguities at the early stage of most algorithms must be determined. Furthermore, if a precise positioning is to be applied to real time navigation, fast determination and validation methods for integer ambiguity are essential. In this paper, the Wald test that simultaneously determines and validates integer ambiguities is used with assistance of the Inertial Navigation System (INS) to improve its performance. As the Wald test proceeds, it assigns a higher probability to the candidate that is considered to be true at each time step. The INS information is added during the Wald test process. Large performance improvements were achieved in convergence time as well as in requiring fewer observable GPS satellites. To test the performance improvement of the Wald test with the INS information, experimental tests were conducted using a ground vehicle. The vehicle moved in a prescribed trajectory and observed seven GPS satellites. To verify the effect of the INS information on the Wald test, the convergence times were compared with cases that considered the INS information and cases that did not consider the INS information. The results show that the benefits of using the INS were emphasized as fewer GPS satellites were observable. The performance improvement obtained by the proposed algorithm was shown through the fast convergence to the true hypothesis when using the INS measurements.