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서정원,허현무,최재붕,김영진,Seo Jung-Won,Hur Hun-Mu,Choi Jae-Boong,Kim Young-Jin 대한기계학회 2005 大韓機械學會論文集A Vol.29 No.10
Damage often occurs on the surface of railway wheels due to wheel-rail contact fatigue. It should be removed before reaching wheel failure, because wheel failure can cause derailment with loss of life and property. The increase or decrease of the contact fatigue lift by the metal removal of the contact surface were investigated by many researchers, but they have not considered initial residual stress and traction force. The railway wheel has the initial residual stress formed during the manufacturing process, and the residual stress is changed by thermal stress induced by braking. The traction force and residual stress are operated on wheels of locomotive and electric motor vehicle. In this study, the effect of metal removal depth on the contact fatigue life for a railway wheel has been evaluated by applying lolling contact fatigue test. The effect of the traction force and metal removal on the contact fatigue life has been estimated by finite element analysis. It has been found that the initial residual stress determines the amount of metal removal depth if the traction coefficient is less than 0.15. If the traction coefficient is greater than 0.2, however, the amount of metal removal depth is independent on the intial residual stress.
서정원(Seo Jung-won),권성태(Kwon Sung-tae),김정국(Kim Jeong-Guk) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-
Bogie frame of the electric car is an important structural member for the support of vehicle loading. In general, more than 25 years" durability is necessary. A lot of study has been carried out for the prediction of the structural integrity of the bogie frame in experimental and theoretical domains. The objective of this paper is to estimate the structural integrity of the bogie frame of an electric car, which is under the running test. F.E. analysis of bogie frame was performed to find locations for attaching strain gage and to estimate static stress. Dynamic stress were measured by using strain gage in order to evaluate the structural integrity of the bogie frame.
서정원(Jung-Won Seo),권석진(Suck-Jin Kwon),함영삼(Young-Sam Ham),권성태(Sung-Tae Kwon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Bogie frame of the locomotive is an important structural member for the support of vehicle loading. A lot of study has been carried out for the prediction of the structural integrity of the bogie frame in experimental and theoretical domains. The objective of this paper is to estimate the structural integrity of the bogie frame. Strength analysis has been performed by finite element analysis. From these analysis, stress concentration areas were investigated. For evaluation of the loading conditions, dynamic stress were measured by using strain gage. It has been found that the stress and strain due to the applied loads were multi-axial condition according to the location of strain gage. The fatigue strength evaluations of the bogie frame are performed to investigate the effect of the multi-axial load through the employment of the critical plane approach.
서정원(Jung-Won Seo),정병구(Byoung-Koo Jung),윤창배(Chang-Bae Yoon),신영준(Young-Jun Shin) 한국전자파학회 2015 한국전자파학회논문지 Vol.26 No.11
육군 항공기류의 UHF 대역 송수신기는 규격인 MIL-STD-461F Figure CE101-4를 만족해야 한다. 항공기에 장착되는 장비이므로, 소모전력 최소화 및 주파수 간섭 최소화에 중점을 두고 장비를 설계하였다. 장비 설계 후 CE101 시험을 진행하면서 문제가 발생되었던 부분은 30 Hz에서 1 kHz에서 100 dBuA 규격 이상의 신호가 발생하였고, 발생된 신호는 송수신기에서 방사되는 10 W, 20 ms 단위의 TDD 50 Hz 신호로 분석되었다. 규격 만족을 위해 전류변화량을 줄여야 한다는 시험 결과를 토대로 출력증폭기의 Idq와 Id 값을 유사하게 수정하였고, 기존 설계의 소모 전력과 주파수 간섭과 크게 차이가 없게 설계 및 제작하였다. In case of UHF Band Transceiver for Army Aircraft, it shall follow MIL-STD-461F Figure CE101-4 most key design points for this equipment were to minize the current consumption and frequency interference since it will be integrated on aircraft. However, after design, abnomal signal(over 100 dBuA) was occured from 30 Hz to 1 kHz on CE101 test. Occured abnomal signal was measured as 50 Hz signal which was tansceiver TDD signal with the output power of 10 W and 20 ms periods. To meet the specification, current variation needed to be minized. Thus, Idq and Id of power amplifier were modified almost equally through test result and finally, the equipment was designed and developed with no difference of current consumption and frequency interference from the previous design goal.
유도낙뢰를 고려한 항공기용 제어기 및 송수신기 개발 및 검증
서정원(Jung-Won Seo),박재수(Jae-Soo Park),윤창배(Chang-Bae Yoon),홍수운(Su-Woon Hong),정병구(Byoung-Koo Jung),신영준(Young-Jun Shin),하정완(Jung-Whan Ha) 한국전자파학회 2018 한국전자파학회논문지 Vol.29 No.8
자연 대기에서 발생하는 낙뢰는 항공기에 용융, 소손 및 아크 등의 물리적인 손상을 발생시킬 뿐만 아니라, 낙뢰의 관통 과정에서 발생하는 기체 외부의 자기장은 기체 내부의 전자장비 및 배선에 전압 및 전류 과도현상을 발생시킨다. 이러한 효과는 항공기 내부의 항공전자시스템에 유도낙뢰를 발생시켜 안전한 비행을 불가능하게 한다. 본 논문에서는 표준감항인증 요구도를 만족하는 보호회로 설계 기법과 공인인증된 시험 결과를 소개하였다. Lightning causes physical damage to aircraft, such as melting, burning and arcing, and magnetic field that occurs on the aircraft’s outer body during the penetration of a lightning stroke causes voltage and current transients in the electronics and wiring within the aircraft. This effect will cause induced lightning strikes in the aircraft’s internal airborne electronic systems , preventing safe flight. This paper introduces protection circuit design techniques, and the test results that meet the requirements for certification of criteria.
폐질환 치료제의 효율적인 신약개발을 위한 생체표지자 및 대리결과 변수
서정원(Jeong-Won Seo),이병요(Byung-Yo Lee),채정우(Jung-Woo Chae),손추영(Chu-Young Son),강원구(Wonku Kang),채한정(Han-Jung Chae),권광일(Kwang-il Kwon) 대한약학회 2010 약학회지 Vol.54 No.2
Biomarkers are likely to be important in the study of various pulmonary diseases for many reasons. Research efforts in developing biomarkers and surrogate endpoints of lung diseases have resulted in the identification of new risk factors and novel drug targets, as well as the establishment of treatment guidelines. Government agencies, academic research institutions, diagnostic industries, and pharmaceutical companies all recognize the importance of biomarkers in new drug development and advancing therapies to improve public health. In drug development, biomarkers are used to evaluate early signals of efficacy and safety, to select dose, and to identify the target population. Identification of suitable end points not only would help investigators design appropriate clinical trials but would assist clinicians in caring for this patient population. Though the area of pulmonology has received much attention in the past decades, it still lags behind with regard to the development of biomarkers, particularly those of health effects and susceptibility. This review critically summarized several biomarker researches such as Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE) study with objectives of identifying the parameters that predict disease progression of COPD, as well as biomarkers that may serve as surrogate end-points.
서정원(Jung-Won Seo),나성훈(Sung-Hun Na),권성태(Sung-Tae Kwon),권석진(Seok-Jin Kwon) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Railway wheels and axles belong to the most critical components in railway vehicles. The service conditions of railway vehicles became more severe in recent years due to the increase of speed. Therefore, a more precise evaluation of wheelset life and safety has been requested. The residual stress on wheel is formed during the manufacturing process which includes a heat treatment, and then is changed by contact stress developed by wheel/rail contact and thermal stress induced by braking. Since the wheel is designed to maintain a constant thickness up to a certain limit for the reprofilling process which requires contact surface removal, wheel surface thickness is reduced by surface removal and wear over the life of a wheel. The residual stress of contact surface is redistributed due to surface removal and thickness variation. The objective of this paper is to estimate the variation and magnitude of the residual stress of railway wheel according to surface removal.
서정원(Jung-Won Seo),권성태(Seong-Tae Kwon),이동형(Dong-Heong Lee),권석진(Seok-Jin Kwon) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
Rails are subjected to damage from rolling contact fatigue which leads to defects such as cracks. Rolling contact fatigue damages on the surface of rail such as head check squats are one of growing problems. Another form of rail surface damage known as "Ballast imprint" has become apparent. This form of damage is associated with ballast particles becoming trapped between the wheel and the surface of rail. These defects are still one of the key reasons for rail maintenance and replacement. In this study we have investigated whether the ballast imprint is an initiator of head check type cracks and effect of defect size using Finite element analysis. The FE analysis were used to investigate stresses and strains in subsurface of defects according to variation of defect size. Based on loading cycles obtained from FE analysis fatigue analysis for each point was carried out.