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안동근(Dong Geun Ahn),최정희(Jung Hee Choi),장중순(Joong Soon Jang) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.2
Purpose: This paper proposes the methods and procedures to effectively identify and select potential failure modes to perform a process failure modes and effects analysis (FMEA). Methods: Detailed analyses of processes are generally required to prevent possible omissions and improper utilization of potential failure modes. In this study, a process decomposition is proposed for all procedures summarized in the process-flow chart to identify potential failure modes. To provide detailed identifications of the potential failure modes, a method of decomposing the process into work units is described. In addition, the 4M+1E elements, which are required for the decomposition, are found and listed. Each of the operational performance elements determined in this step was found to interfere with the work. Further, a method of identifying potential failure modes is proposed based on the determined work obstructions. Results: The process flow for an example screw-tightening procedure was decomposed into work units based on its process FMEA. A method to predict the potential failure modes for each disassembled work unit was also established based on the obstacles to work performance. Conclusion: By applying the proposed method to a screw-fastening process, it was confirmed that a process FMEA performed without process decomposition found unexpected potential failure modes.
공정평균이 변하는 생산공정의 초기값 및 재설정 수준 결정
안동근 ( Dong-geun Ahn ) 대한설비관리학회 2020 대한설비관리학회지 Vol.25 No.2
Mean shifts may be found in tool wear in machining, drawing, stamping and moulding operations, which make the process quality level deteriorate over time. In such situations, it is necessary to reset or readjust the manufacturing process at regular time basis or by inspection to prevent defective items being produced. Although the deterioration rate may be assumed to be linear in a production cycle, there are many cases where the rate varies after resetting due to the variation of tool characteristics or by using the resharpened tools. In such cases, the deterioration rate should not be assumed to be a deterministic constant but a random variable. This paper is to find an optimal resetting level and starting level for such production processes.
PFEM을 이용한 Process FMEA 수행 방법 연구
안동근 ( Dong-geun Ahn ),차봉환 ( Bong-hwan Cha ),장중순 ( Joong-soon Jang ) 대한설비관리학회 2020 대한설비관리학회지 Vol.25 No.3
FMEA is now considered a prerequisite tool for design, control and improvement. To perform FMEA, a systematic procedure is needed in identifying failure modes, mechanisms and causes. Results prepared in accordance with the previously widely used process FMEA implementation procedure are easy to integrate potential failure modes and causes of each process. However, there are difficulties in situations in which specific failure modes need to be managed intensively. This study is to propose a procedural model for process FMEA based on process function and equipment model (PFEM) which represents the mapping between process functions and corresponding equipments. The process FMEA performance method using PFEM is a methodology that enables them to be found by systematically accessing failure modes, effects, and causes by using a combined VOC and defect history. Such a method may be useful for the equipment focused manufacturing processes like chemical plants. An actual case study is also given.
무기체계 연구개발단계에서의 체계적인 FMEA 실행 방법
안동근(Dong Geun Ahn),유재민(Jae Min Yoo),장중순(Joong Soon Jang) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.1
Purpose: This paper proposes methods and procedures to effectively identify and select potential failure modes in the performance of faliure mode and effect analysis (FMEA). Specifically, a method is proposed to perform FMEA with emphasis on deriving failure mechanisms. Methods: The failure mechanism is known for a design change or improvement preventing recurrence and proactive. Therefore, it is important in designing FMEA to derive failure mechanisms and potential failure modes. This paper presents methods and procedures to derive failure mode and failure mechanism by analyzing past failure cases, usage/environmental condition parts (material), and interaction. Results: The effective design FMEA implementation procedure in the inorganic system development phase was described through the design FMEA practice case for antenna circuit card assembly and HL motor assembly among the drives used in induction weapon systems. Conclusion: The effectiveness of new identification of failure modes can be identified that the existing FMEA had not predicted by applying the proposed effective FMEA implementation methods and procedures to the weapon system development model.
류지수 ( Ji-soo Ryu ),안동근 ( Dong-geun Ahn ),장중순 ( Joong-soon Jang ) 대한설비관리학회 2020 대한설비관리학회지 Vol.25 No.4
The purpose of this study is to find out about the 'N' shaped yield curve that occurs at the time of transition from the development stage to the mass production stage. Also, previously proposed various methodologies to improve the 'N' shaped yield curve are reviewed. This research focuses on preventing the drop of 'N' shaped yield curve when transitioning to the mass production stage by studying the necessity of management and improvement for preventing yield drop. In regards to yield in the mass production, many studies have been conducted on design activities considering mass production under the name of Design for Manufacture. However, the research of yield reduction in the early mass production stage has rarely been studied because the reduction of yield is considered to be a natural occurrence. This study aims to stabilize the supply of products by securing stable yield in the early stage of mass production through empirical analysis data in the manufacturing, as a consequence, this study introduces the methodology to reduce the risk of initial defects.
Fe-Mn 제진 금속을 적용한 신축이음장치의 피로 내구성 평가
김기익(Kim Ki-Ik),김영진(Kim Young-Jin),안동근(Ahn Dong-Geun),김철환(Kim Cheol-Hwan) 대한토목학회 2009 대한토목학회논문집 D Vol.29 No.4D
진동ㆍ소음을 저감시키는 Fe-Mn 제진 금속을 이용하여 제작된 핑거형 신축이음장치의 피로 내구성을 평가하고자 유한 요소해석과 수직하중 피로시험을 실시하였다. 피로실험은 Fe-Mn 제진금속을 이용한 신축이음장치와 유압가력기(25tonf)를 사용하여 진행되었으며, 그 결과에 따르면 핑거형 신축이음장치에 수직하중을 인가하였을 경우 핑거에서 측정된 최대 응력은 237.6㎫ 이며, 이는 제진 금속의 항복강도인 420㎫의 56.6%이였다. 제진 금속을 이용한 신축이음의 피로시험은 도로교 설계기준에 따라 재하위치(KS F 4425)와 재하판(57.7㎝×23.1㎝)의 크기가 설정되었고, 그에 따른 200만회 수직하중 피로시험에 있어서 파괴거동을 나타내지 않았으며 그 내구성과 안전성을 확인하였다. The endurance of expansion joint manufactured the Fe-Mn damping alloy reducing noise and vibration is analyzed into FEM (Finite Element Method) and fatigue test. The fatigue test have been performed using the expansion joint manufactured Fe-Mn damping alloy and the hydraulic actuator (25tonf). And the results of fatigue test show that the maximum strength is 237.6 ㎫. Also that is 56.6 percent of Fe-Mn damping alloy yield strength (420 ㎫). The loading plate size is prepared 57.7 ㎝×23.1 ㎝ and the loading plate's set position is located on expansion joint. The expansion joint manufactured the Fe-Mn damping alloy had not presented breaking behavior against 2,000,000 times fatigue test and identified the fatigue endurance.