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인공위성 탑재품 수준 열진공 시험에 대한 열해석 모델의 개발과 환경시험 결과를 이용한 검증
김상호(Sang-Ho Kim),서현석(Hyun-Suk Seo),유재호(Jae-Ho You),한은수(Eun-Soo Han),김태경(Tai-Kyung Kim),김형동(Hyeong-Dong Kim),허환일(Hwanil Huh) 한국항공우주학회 2010 韓國航空宇宙學會誌 Vol.38 No.8
본 연구는 인공위성 탑재품 열진공 시험시 적용된 열환경 조건, 탑재품 시험용 열진공 챔버의 형상, 위성체 내부의 열환경들을 고려하여 열진공 시험 과정을 모사하는 수치해석 모델을 설계하여 열해석을 수행하였다. 피시험체인 탑재품과 열진공 챔버 구성요소의 시간에 따른 온도 변화를 보여주는 과도적(Transient) 해석 결과를 구할 수 있다. 열해석에 의한 성능향상 설계를 반영하여 업그레이드한 열진공 챔버를 이용한 탑재품 환정시험을 수행하였으며, 시험 결과와 열해석 결과에 대한 비교/검증을 수행하였다. Thermal analysis for the simulation of satellite component level thermal vacuum test processes was carried out by considering thermal vacuum test environment condition, thermal vacuum chamber configuration, and satellite's inner thermal environment. The transient analysis results can be obtained for the temperatures of component and thermal vacuum chamber assemblies. The thermal analysis model was verified with the component thermal environmental test results by using enhanced thermal vacuum chamber.
세라믹-세라믹 관절면을 이용한 시멘트형과 무시멘트형 인공고관절 전치환술의 결과 비교
임수재 ( Soo Jae Yim ),유재호 ( Jae Ho Yoo ),서유석 ( Yu Seok Seo ),김병민 ( Byoung Min Kim ),정기진 ( Ki Jin Jung ),서유성 ( You Sung Suh ),( Seng Chamroeun ) 대한고관절학회 2008 Hip and Pelvis Vol.20 No.3
목적: 세라믹-세라믹 관절면으로 시멘트형 인공 고관절 전치환술을 시행한 군과 무시멘트형 인공 고관절 전치환술을 시행한 군에서 임상적 및 방사선학적 결과를 조사하였다. 대상 및 방법: 2004년 1월부터 2005년 2월까지 시멘트형 인공 고관절 전치환술을 시행하고 3년 이상 추시가 가능하였던 53명 59예와, 같은 기간 무시멘트형 인공 고관절 전치환술을 시행하고 3년 이상 추시가 가능하였던 58명 64예를 대상으로 하였다. 임상적 평가로는 Harris 고관절 점수, WOMAC 점수를 사용하였고, 최종 추시상 고관절부 불편감, 대퇴부 동통 여부를 조사하였다. 방사선학적으로 방사선 투과음영, 대퇴 스템의 침강, 시멘트 맨틀의 등급, 고정의 안정성 등을 관찰하였다. 결과: Harris 점수는 시멘트형 군에서 수술 전 평균 62.7점에서 최종 추시상 평균 92.4점으로 향상 되었으며, 무시멘트형 군에서는 수술 전 평균 61.5점에서 최종 추시상 평균 91.8점으로 향상 되었다(p>0.05). WOMAC 점수는 시멘트형 군에서 수술 전 평균 37.9점에서 최종 추시상 평균 7.0점으로 향상 되었고, 무시멘트형 군에서는 수술 전 평균 38.5점에서 최종 추시상 평균 12점으로 향상 되었다(p<0.05). 시멘트형 군에서는 고관절부 불편감과 대퇴부 동통은 없었으며, 무시멘트형 군에서는 고관절부 불편감 5예, 대퇴부 동통 9예가 있었다. 양 군에서 비구 컵의 골성 고정을 얻었고, 삽입물의 이동 소견은 보이지 않았다. 시멘트형 군에서 대퇴 스템의 침강은 57예에서 1 mm 이내, 2예에서 2 mm 이내였으며, 무시멘트형 군의 모든 예에서 대퇴 스템의 골성 고정을 얻었다. 결론: 세라믹-세라믹 관절면을 이용한 시멘트형 인공 고관절 전치환술은 무시멘트형 인공 고관절 전치환술에 비해 유의하게 임상적으로 양호한 결과를 얻었으며, 세라믹-세라믹 관절면의 높은 강성으로 인한 문제점을 보완하기에 좋은 방법이라고 생각된다. Purpose: The purpose of this study was to evaluate the results of ceramic-on-ceramic bearing primary total hip arthroplasty (THA) using cemented femoral stems and cementless femoral stems. Materials and Methods: We studied 59 cases (52 patients) of THAs using ceramic-on-ceramic bearing cemented femoral stems and 64 cases (58 patients) of THAs using ceramic-on-ceramic bearing cementless femoral stems. All THAs were performed between January 2004 and February 2005 and were followed up for more than 3 years. The clinical results were evaluated using the Harris hip score (HHS), WOMAC score, sense of discomfort, and thigh pain. Radiographic results were assessed with serial radiographs. Results: The mean HHS improved from 62.7 points preoperatively to 92.4 points at the last follow-up in the cemented stem group and improved from 61.5 points to 91.8 points in the cementless stem group (p>0.05). And mean WOMAC score improved from 37.9 points to 7.0 points in the cemented stem group and from 38.5 points to 12 points in the cementless stem group (p<0.05). There were 5 patients with a sense of discomfort and 9 patients with thigh pain in the cementless stem group and no cases in the cemented stem group. There were no instances of acetabular loosening in either group. Subsidence of the cemented femoral stem was less than 1 mm in 57 cases and less than 2 mm in 2 cases. All cementless femoral stems acquired firm bony union. Conclusion: Ceramic-on-ceramic bearing THA using a cemented stem showed clinical results superior to those achieved using a cementless stem. Cemented THA is thought to be good for complementing the problems caused by the hardness of ceramic-on-ceramic bearings.
조동재(Dong Jae Jo),박진한(Jin Han Park),유재호(Jae Ho You),박상섭(Sang Sup Park),김정수(Jeong Soo Kim) 한국추진공학회 2023 한국추진공학회지 Vol.27 No.3
Chemical propulsion system possesses superior thrust performance compared to other propulsion systems, making it suitable for the missions that require high thrust and agile maneuverability, such as orbit transition and attitude control. However, when it is applied to micro-satellites, the size and weight of the system manifest itself as limiting factors. Therefore, simplification of the system for microsat is inevitable, and possible approaches include component miniaturization, introduction of additive manufacturing techniques, and improvement of pressurization methods. Additive manufacturing techniques enhance the design flexibility and significantly reduce the number of parts, while using solid pressurization system or incorporating propellant management devices are also considered as the miniaturization approaches.
저속 후방 추돌 자원자 실험을 통한 두부와 경부의 동작분석
홍성우,박원필,박성지,유재호,공세진,김한성,Hong, Seong Woo,Park, Won-Pil,Park, Sung-Ji,You, Jae-Ho,Kong, Sejin,Kim, Hansung 한국자동차안전학회 2012 자동차안전학회지 Vol.4 No.2
The purpose of this research is to obtain and analyze dynamic responses from human volunteers for the development of the human-like mechanical or mathematical model for Korean males in automotive rear collisions. This paper focused on the introduction to a low-speed rear impact sled test involving Korean male subjects, and the accumulation of the motion of head and neck. A total of 50 dynamic rear impact sled tests were performed with 50 human volunteers, who are 30-50 year-old males. Each subject can be involved in only one case to prevent any injury in which he was exposed to the impulse that was equivalent to a low-speed rear-end collision of cars at 5-8 km/h for change of velocity, so called, ${\Delta}V$. All subjects were examined by an orthopedist to qualify for the test through the medical check-up of their necks and low backs prior to the test. The impact device is the pendulum type, tuned to simulate the crash pulse of a real vehicle. All motions and impulses were captured and measured by motion capture systems and pressure sensors on the seat. Dynamic responses of head and T1 were analyzed in two cases(5 km/h, 8 km/h) to compare with the results in the previous studies. After the experiments, human subjects were examined to check up any change in the post medical analysis. As a result, there was no change in MRI and no injury reported. Six subjects experienced a minor stiffness on their back for no more than 2 days and got back to normal without any medical treatment.
이온 샤우어 도핑을 이용한 자기정렬방식의 APCVD 비정질 실리콘 박막 트랜지스터의 제작
문병연,이경하,정유찬,유재호,이승민,장진,Moon, Byeong-Yeon,Lee, Kyung-Ha,Jung, You-Chan,Yoo, Jae-Ho,Lee, Seung-Min,Jang, Jin 대한전자공학회 1995 전자공학회논문지-A Vol.32 No.1
We have studied the fabrication self aligned atmospheric pressure(AP) CVD a-Si thin film transistor with source-drain ohmic contact by using ion shower doping method. The conductivity is 6*10$^{-2}$S/cm when the acceleration voltage, doping time and doping temperature are 6kV, 90s and 350.deg. C, respectively. We obtained the field effect mobility of 1.3cm$^{2}$/Vs and the threshold voltage of 7V.
최원(Won Choi),유재호(Jae Ho You),이일우(Il Woo Lee) 한국추진공학회 2010 한국추진공학회지 Vol.14 No.6
This paper dealt with the performance modeling of a low bypass turbofan engine for supersonic aircraft. The Pratt and Whitney F100-PW-229 engine has been employed for low bypass turbofan engine performance modeling. Generally, the complete commercially-classified informations concerning the engine are unknown. The components’ generic characteristics and assumptions made in order to build the F100-PW-229 engine performance model using by the published data from the open literature as basic data are described. Through the comparison of engine performance model’s analysis data using Gasturb11 with engine deck data showed that the engine performance model was evaluated to be properly constructed.