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이지형,오종윤,박익수,Lee Ji-Hyung,Oh Jong-Yun,Park Ik-Soo 한국군사과학기술학회 2004 한국군사과학기술학회지 Vol.7 No.4
A simplified test rig to simulate high-altitude environments was designed by analyzing the AEDC (Arnolds Engineering Development Center) report regarding simulated altitude testing. The test rig consists of a vacuum chamber, a supersonic nozzle connected to a cold-gas supplier and a diffuser. The preliminary tests were conducted to validate the AEDC design concepts. The test results showed that sub-atmospheric pressure(1.0psia) environments were realized inside the vacuum chamber and the design concepts were confirmed.
소형 초음속 디퓨저를 이용한 고고도환경 모사에 대한 시험적 연구
이지형,오종윤,변종렬,Lee Ji-Hyung,Oh Jong-Yun,Byun Jong-Ryul 한국군사과학기술학회 2004 한국군사과학기술학회지 Vol.7 No.4
Experimental study was conducted on cylindrical supersonic diffuser in order to investigate the effects of the ratios of diffuser area to nozzle throat area (Ad/At), diffuser area to nozzle exit area (Ad/Ae), nozzle exit area to its throat area (Ae/At), and diffuser length to its diameter (L/D), the free volume of vacuum chamber, and the relative distance between nozzle exit and diffuser inlet on the diffuser performance. The study showed that the minimum diffuser starting pressure (Po/Pa)st increased monotonically with increase in (Ad/At) as predicted by the normal shock and momentum theory models and the volume of vacuum chamber affected vacuum pressure level during diffuser operation at lower value of (Ad/Ae). The results of this investigation will be utilized in the design of real-scale high-altitude simulation test facility.
이지형,홍성걸,Lee, Ji-Hyung,Hong, Sung-Gul 한국공간구조학회 2015 한국공간구조학회지 Vol.15 No.2
Ultra High Performance Fiber Reinforced Concrete (UHPFRC) has a outstanding tensile hardening behaviour after a crack develops, which gives ductility to structures. Existing shear strength model for fiber reinforced concrete is entirely based on crack opening behavior(mode I) which comes from flexural-shear failure, not considering shear-slip behavior(mode II). To find out the mode I and mode II behavior on a crack in UHPFRC simultaneously, maximum shear strength of cracked UHPFRC is investigated from twenty-four push-off test results. The shear stress on a crack is derived as variable of initial crack width and fiber volume ratio. Test results show that shear slippage is proportional to crack opening, which leads to relationship between shear transfer strength and crack width. Based on the test results a hypothesis is proposed for the physical mechanics of shear transfer in UHPFRC by tensile hardening behavior in stead of aggregate interlocking in reinforced concrete. Shear transfer strength based on tensile hardening behavior in UHPFRC is suggested and this suggestion was verified by comparing direct tensile test results and push-off test results.
이지형 ( Ji Hyung Lee ),김상원 ( Sang Won Ghyme ),박찬종 ( Chan Jong Park ) 한국감성과학회 1999 추계학술대회 Vol.1999 No.-
컴퓨터 그래픽스에서 인간의 얼굴 표정을 생성하는 것은 고전적인 주제중의 하나이다. 따라서 관련된 많은 연구가 이루어져 왔지만 대부분의 연구들은 특정 모델을 이용한 얼굴 표정 애니메이션을 제공하였다. 이는 얼굴 표정에는 얼굴 근육 정보 및 부수적인 정보가 필요하고 이러한 정보는 3D 얼굴 모델에 종속되기 때문이다. 본 논문에서는 일반적인 3D 얼굴 모델에 근육을 설정하고 기타 정보를 편집하여, 다양한 3D 얼굴모델에서 표정 애니메이션이 가능한 도구를 제안한다.
문제 중심 학습의 물 환경교육 프로그램이 초등학생의 환경 친화적 행동에 미치는 영향
이지형(Ji Hyung Lee),이상원(Sang Won Lee) 한국환경교육학회 2009 環境 敎育 Vol.22 No.2
The purpose of this study is to investigate the influences of water environmental program using PBL on pro-environmental behavior for 4th graders in elementary school. The results of this study are as follows. First, the experimental group is more effective in promoting the pro-environmental attitude compared with the control group. Second, the experimental group is more effective in promoting the pro-environmental behavior compared with the control group. Third, the experimental group is not more effective in promoting the pro-environmental knowledge compared with the control group. Fourth, students are concerned and interested in the environment and environmental problems of the daily-life. And, they presented positive attitude and active participation toward environmental preservation. So, the process of PBL using water environmental program showed that it promotes active learning participation and various action. In conclusion, the environmental education program through PBL program has a positive effect on pro-environmental attitudes and behavior of elementary school students. It is demanded that more intensive research on this study should be done, linking with teaching and learning method, as a follow-up activity.