동력차용 대차프레임의 피로강도평가

이학주,한승우,이상록,Lee, Hak-Ju,Han, Seung-U,Augagneur Sylvain,Lee, Sang-Rok 한국기계연구원 1997 硏究論文集 Vol.27 No.-

The bogie between the track and the railway vehicle body, is one of the most important component in railroad vehicle. Its effects on the safety of both passengers and vehicle itself, and on the overall performance of the vehicle such as riding quality, noise and vibration are critical. The bogie is mainly consisted of the bogie frame, suspensions, wheels and axles, braking system, and transmission system. The complex shapes of the bogie frame and the complicate loading condition (both static and dynamic) induced in real operation make it difficult to design the bogie frame fulfilling all the requirements. The complicated loads applied to the bogie frame are i) static load due to the weight of the vehicle and passengers, ii) quasi-static load due to the rolling in curves iii) dynamic load due to the relative motion between the track, bogie, and vehicle body. In designing the real bogie frame, fatigue analysis based on the above complicated loading conditions is a must. In this study, stress analysis of the bogie frame has been performed for the various loading conditions according to the UIC Code 6 15-4. Magnitudes of the stress amplitude and mean stress were estimated based on the stress analysis results to simulate the operating loads encountered in service. Fatigue strength of the bogie frame was evaluated by using the constant life diagram of the material. 3-D surface modelling, finite element meshing, and finite element analysis were performed by Pro-Engineer, MSC/PATRAN, and MSC/NASTRAN, respectively.

최대전력관리장치 보급확대를 위한 수요관리 프로그램 개발

이학주(Hak-Ju Lee),이한별(Han-Byul Lee),박재덕(Jae-Duck Park),금병선(Byung-Sun Kum) 한국조명·전기설비학회 2005 한국조명·전기설비학회 학술대회논문집 Vol.2005 No.11월

The electric demands increase, financial need for new power plant constructions and environmental problem have led to search for more efficient energy production and load management. To minimize the construction of power plants and reduce total power consumption include installation of demand controller to industrial applications. Accordingly to maximize the load control by the diffusion of demand controller, governmental economic supports as well as the analysis of energy saving effects. This paper presents the cost-effectiveness analysis for DSM program evaluation and case study to analyze demand controller DSM program.

초등 교과교육학의 성격과 내용구조 연구

유한구(Han Ku Ryu),장성모(Sung Mo Chang),송광용(Kwang Yong Song),조주연(Joo Yun Cho),이학주(Hak Ju Lee) 한국초등교육학회 1997 초등교육연구 Vol.11 No.1

이 연구는 교과교육과 교과교육학의관계, 그리고 교과교육학과 교육학의 관계등을 분석하고, 그 결과를 토대로 하여 초등학교 교과교육과 교육대학 교과교육학 교육의 실제를 정확히 이해하고 그 발전 방향을 탐색하기 위한 것이다. 일반적으로, 교과교육학은 교육학에서 제시하고 있는 교육과정의 구성및 교육방법상의 일반 원리를 교과교육이라는 특수한 사태에 적용하는 과정에 관심을 두는 이론으로 간주되고 있다. 이 관점에 의하면, 교과교육학은 교육학의 일반적 원리에 따라 교과교육이라는 특수한 맥락에 처방을 내리기 위한 것으로 파악된다. 이 관점을 교과와 그것을 가르치는 교사의 삶을 사실상 별개의 것으로 분리하는 것이며, 그와 동일한 이유에서 교과교육학과 교과교육학자의 삶 또한 별개의 것임을 전제하는 것이다. 그러나 교과교육과 교과교육학, 그리고 교과교육학과 교육학의 관계는 이론에서 실제로 나아가는 앞의 방향과는 정반대 방향에서도 이해될 수 있다. 이 관점에 의하면, 교과교육학은 교과교육 실제에 처방을 내리기 위한 것이 아니라 그 실제를 기술하고 정당화하기 위한 것으로 파악된다. 교과교육과 교과교육학의 관련이 이렇게 파악될 때, 교과 교육학은 교사나 교과교육학자에게 자신이 지금 하는 일이 자신의 삶과 결코 무관한 것이 아니라는 믿음을 심어 주게 되며, 나아가 그들 자신이 참여하고 있는 초등학교나 교육대학의 교육실제를 기술하거나 정당화하려고 할 때 반드시 필요한 개념적 도구를 제공해 줄 수 있게 된다. 바로 여기에 교과교육학에 관한 종래의 접근과는 구분되는 새로운 접근방식이 요구되는 이유가 있다. The purpose of this study is threefold: The first is to analyse the relations between subject education and subject pedagogy, and between subject pedagogy and general pedagogy. The second is, based on the analysis result, to have the precise understanding of teaching various subjects in the elementary school, and of teaching subject pedagogy in the university of education. The third is to search for the desirable direction of developing the elementary education and the teacher education. Subject pedagogy is usually defined as a theory which is interested in the process of applying pedagogical principles regarding curriculum organization and teaching methods to specific teaching situations, that is, subject education situations. However, this definition has a limitation, because it assumes that a subject and the teacher's life who teaches the subject are separated from each other, and that subject pedagogy and the scholar who studies subject pedagogy are also separated. The relationship between subject teaching and subject pedagogy, and between subject pedagogy and general pedagogy can be understood with quite different viewpoint. This new viewpoint, which is the major discussion matter of this study, assumes that subject pedagogy is never separated from the life of subject teacher/subject pedagogist. This viewpoint will reveal the theoretical features of subject pedagogy better, and give us new meaning on the life of teachers/subject pedagogists. The subject pedagogy in the correct sense should provide teachers/pedagogists with the conceptual instrument based on the new viewpoint. This conceptual instrument will make teachers/pedagogists be able to describe, explain, and validate their own educational practice-such as the content structure of each subject-in the elementary school or the university of education.

초등학교 교직문화 연구(1)

유한구(Han Ku Ryu),이학주(Hak Ju Lee),송경헌(Kyung Hun Song),김승호(Seung Ho Kim) 한국초등교육학회 1997 초등교육연구 Vol.11 No.1

이 논문은 초등교사의 삶을 '있는 그대로' 드러내는 데에 그 목적이 있다. 보다 구체적으로 말하여, 우리나라에서 초등학교 교사로서의 삶을 산다는 것, 곧 초등학교 교사의 생애가 무엇인가를 밝히려고 한다. 이를 위해서 본 연구에서는 교사의 구체적인 삶을 반영한다고 보이는 일기, 서간, 메모 등의 여러 가지 문서들을 수집·해석한 뒤에 그것을 다시 재구성하는 방법을 사용하였다. 그리하여 본 연구의 본론에서는 초등학교 교사의 생애를, '교사가 된 동기', '교사의 자화상', '교사의 삶의 보람과 애환', '교사로서의 성장과정', '교사의 생애 계획'이라는 5가지 측면으로 나누어 드러내었다. 본 연구의 결과에 비추어 볼 때, 점차 실추되어 가는 우리나라 초등교사의 위상을 바로 세우는 길은 그들의 생애를 좀더 총체적으로 드러내는 데에 있다고 하여도 과언이 아니다. 앞으로 본 연구의 결과는 예비교사를 양성하는 데에 좋은 참고가 될 것으로 기대된다. The purpose of this study is to show the life of primary school teacher as it is. More concretely speaking, we investigate what it is for a man to carry on his life as primary school teacher in Korea. For this purpose we use the life-histoy method to analyze diarys, letters, memos and so on, which seem to reflect the concrete life of primary school teacher, and to reconstruct the data analyzed. In main part of this study, therefore, we managed to show 5 aspects of the life of primay school teacher, such as 'motive to be teacher', 'teacher's self-perspectives', 'joy and sorrow of teacher', 'developmental process as teacher', and 'teacher's life-plan'. Based on the result of this study, it is not unreasonable to say that it depends on descibing the life of primacy school teacher as totality to recover the dignity of teacher. The result of this study is expected to suggest practical strategies for elementary teacher education.

탈수속도 변화에 따른 세탁기 클러치하우징의 강도해석

김완두,이학주,한승우,Kim, Wan-Du,Lee, Hak-Ju,Han, Seung-U 한국기계연구원 1996 硏究論文集 Vol.26 No.-

The transmission system of a washing machine which is called by the clutch is one of the most important components to preserve the performance. The clutch housing has a role to guard and mount the transmission system on the frame of the machine. The load which is applied on the clutch housing depends on the operating conditions. Nowadays the dehydration speed is higher and higher in order to improve the efficiency. In this study, the strains on the predicted weak positions were measured using the strain gage and its measuring equipment. The relationships between the dehydration speeds and the maximum principal strains were obtained. Finite element analysis is executed to acquire the effect of the dehydration speed on the stress of the clutch housing. The distributions of the equivalent stress and the maximum stresses under the various speeds, the various loading directions and the various thickness of the clutch housing were obtained.

압력용기용 Cr-Mo강의 균열진전거동에 관한 연구

최병익,이학주,한승우,김창욱,차정환,김정태,지병하,Choe, Byeong-Ik,Lee, Hak-Ju,Han, Seung-U,Kim, Chang-Uk,Cha, Jeong-Hwan,Kim, Jeong-Tae,Ji, Byeong-Ha 한국기계연구원 1999 硏究論文集 Vol.29 No.-

Fatigue crack growth behaviors of Cr-Mo steels developed recently for thick-wall pressure vessel were investigated. Experiments in accordance with ASTM E647 standard were performed for 1/2 inch CT specimens of $2^(1/4)$Cr-1Mo and 3Cr-IMo steels in gaseous environments, hydrogen gas of 10 atm, 1 atm and argon gas of 1 atm. Fatigue crack growth rates were observed and effects of gaseous hydrogen and argon on the crack growth behavior were discussed.

컨베이어용 풀리의 용접부위에 관한 파괴역학 설계기술 개발

한승우,이학주,우창수,이상록,Han, Seung-U,Lee, Hak-Ju,U, Chang-Su,Lee, Sang-Rok 한국기계연구원 1993 硏究論文集 Vol.23 No.-

The drive pulley, which is employed for loading and unloading raw materials in a steel mill, is usually manufactured by use of various welding processes. In this study the weldment in the pulley, in which TIG and $CO_2$ welding processes are used, has been analyzed from view point of fracture mechanics. Fracture toughness tests have been performed according to ASTM E813. A servo-hydraulic testing machine (10kN) has been employed. Also the crack propagation tests (Mode I) have been performed with compact tension specimen in compliance with ASTM E647. To predict the critical crack size in the weldment, finite element stress analysis for the drive pulley under real operating conditions have been performed. In addition, the residual stresses at the weldment and in heat-affected zone have been obtained by hole drilling method. The planar critical crack size have been predicted for the drive pulley by considering the stress analysis results and the residual stresses due to welding process. For the drive pulley considered in this study, it has been concluded that the most important factor in determining the critical crack size is the welding residual stress in the transverse direction. Also the effect of stress concentration at the root of the weldment have been noticeable. For the planar crack, the fatigue crack growth life from an initial crack size of 2mm to the critical crack size obtained as in the above have been predicted. The predicted lives were between 55, 900 and 72, 000 cycles depending on the shape of the elliptical crack. The predicted lives were in fairly good agreement for the drive pulley considered in this study.

자동차 프런트 서브프레임 모듈 설계기술에 대한 연구

최병익,김완두,이학주,강재윤,김정엽,우창수,한승우,김주성,김기주,Choe, Byeong-Ik,Kim, Wan-Du,Lee, Hak-Ju,Gang, Jae-Yun,Kim, Jeong-Yeop,U, Chang-Su,Han, Seung-U,Kim, Ju-Seong,Kim, Gi-Ju 한국기계연구원 2002 硏究論文集 Vol.32 No.-

Even in the world wide automobile companies where a few simple modules are put into practical use, the front subframe modules of which performances of durability, NVH and crash are significantly important are under planing. In this study, design technology for the automobile front subframe module, which consists of an engine, a transmission and steering parts, structural components (frame, upper arm, lower arm and brake etc.) and rubber components(engine mount, axle mount and rubber disc etc.), was developed. A FEM-based analytical approach was used to evaluate the multiaxial high cycle fatigue damage of the front subframe module. Strain-life fatigue database system and expert system for fatigue properties of welded materials were developed. Stiffness values of the various rubber bushes mounted on the front subframe were evaluated by experimental method and FEM. TWB(Tailor Welded Blank) technology was applied to forming the cross member of the front subframe. Performance evaluations in relation to NVH and crash were conducted by using CAE technologies.

Water Seal 특성의 전산 해석

한승우,김완두,이학주,Han, Seung-U,Kim, Wan-Du,Lee, Hak-Ju 한국기계연구원 1994 硏究論文集 Vol.24 No.-

Water seal is composed of metal case, garter spring, and NBR. Axisymmetric, large deformation non-linear contact problems were solved by using the finite element method for the evaluation of performance of the water seal. Effects of the interference between seal and shaft, and the garter spring on the seal characteristics were considered in this analysis. The contact force and sealing performance increased as the interference and spring stiffness increases. And middle seal is main role sealing performance. Further research efforts are required to consider the effects of the garter spring stiffness, the eccentricity by the shaft or case, and the water pressure.

나노압입시험기를 이용한 MEMS 공정조건에 따른 SU-8 감광제의 기계적 물성 측정

최현주(Hyun-ju Choi),김재현(Jae-Hyun Kim),이학주(Hak-joo Lee),현승민(Seungmin Hyun),한승우(Seung-Woo Han) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

The interest of utilizing SU-8 for the fabrication of thick micro-electro-mechanical systems(MEMS) has been growing recently. Especially SU-8 is a widespread material for soft structures in MEMS applications. However, the fabrication of thick SU-8 MEMS process has been experienced severe problems such as cracks, distortions and delaminations due to post expose bake(PEB) photolithography process. In order to design a reliable device using SU-8 , it is necessary to measure the mechanical properties of SU-8. The mechanical behavior of micro-scale structures usually is very different from that of the bulk materials. The behavior of small scale structures is dependent on their dimension and fabrication process. In this study, we used an advanced Pillar Compression Test using nanoindentation apparatus to measure the stress-strain relationship of SU-8 micro pillars fabricated by MEMS process. Stress-strain curves and mechanical properties of baked SU-8 pillar at 65℃ ~ 120 ℃ were extracted from measured load-displacement data.