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조준현,Jo, Jun-Hyeon 대한건축사협회 1981 建築士 Vol.1981 No.9
건축공사의 적산은 제시된 설계도나 기지 시방서에 의하여 공종별로 수량을 산출하고 그 명 수량에 소요단가를 정한 금액을 합산하여 공사비를 적출하게 된다. 공사량을 적출하고 공사비를 계산하는데 있어 기본 지침서가 되는것은 정부(건설부)제정 건축적산비율 및 건설공사 표준품셈이 있다. 공종별로 주요하다고 생각되는 1981적용 건축적산비율의 내용과 적산하는데 필요한 자재의 규격 및 1981적용 건설공사 표준품셈을 근간으로한 일위대비표를 건축사 여러분이 실용함에 있어 다소나마 도움이 되지 않을까 생각되어 본지를 통해 소개한다. 본지의 지면관계상 상세하게 또한 전공종을 다 소개하지 못하는 것을 아쉽게 여기면서 지면이 허락하는데로 또한 자료가 정리되는데로 계속해서 소개해 드리고자 한다
쿨롱 마찰 감쇠를 고려한 공기 포일 베어링의 범프 포일 동특성에 관한 연구
조준현(Jun-Hyeon Jo),이용복(Yong-Bok Lee),김창호(Chang-Ho Kim),임윤철(Yoon-Chul Rhim) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.11
Bump foils in air foil bearings are investigated using theoretic analysis, FEM (Finite element method), and experimental method. To analyze the dynamics of bump foils, the governing equation is used by bending moment equation and theory of the thin curvature beam in analytic method. All forces, reactions, and friction forces between bump foils and the housing or the top foil are considered from the geometric form of bump foil applying normal forces on the central top of bump. Plane strain-stress method considered by three components in the xy plane, and the triangle elements are used for FEM analysis. To measure stiffness and damping coefficients of bump foil, the test setup is made with exciter, accelerometer, and gap sensors. An increase in the friction coefficient between the top foil and the bump is a more effective method of achieving both Coulomb damping and higher stiffness. This paper presents the comparison between FEM analytic and experimental results.
극저온 환경용 볼베어링 시험장치 개발 및 터보펌프용 볼베어링 시제품의 성능평가
조준현(Jun Hyeon Jo),임윤철(Yoon Chul Rhim),이성철(Sungchul Lee),김충현(Choong Hyun Kim) 한국트라이볼로지학회 2012 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.28 No.4
The turbo pump of a liquid rocket engine is composed of three main parts: the oxidizer pump, fuel pump, and turbine. Liquid oxygen (LOX) is the working fluid in the cryogenic environment in the oxidizer pump, but tests are usually performed using liquid nitrogen (LN2), which has a boiling point similar to that of LOX but is comparatively safer and easier to use for the test. In this study, a bearing test rig is developed and its performance is evaluated using a cryogenic ball bearing with LN2 as the working fluid. Verifying the performance of the bearing test rig is crucial for ensuring correct working of the turbo pump unit in the liquid rocket engine. A stable test rig for the bearing in a cryogenic environment makes the bearing technology enhance its reliability. The test results show that the system operates stably and the requirement of performance time of 500 s is met. The test results of temperature, motor speed, and torque are discussed. The developed cryogenic bearing test rig is expected to help in widening knowledge and expanding research on ball bearings in the future.