http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
이정석(Jungsuk Lee),윤문영(Moonyoung Yoon),양갑진(Kapjin Yang),송정훈(Jeonghoon Song),제우성(Woosung Che),부광석(Kwangsuk Boo),김흥섭(Heungseob Kim5) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5
The fundamental reason of noise in gear system is transmission error due to deflection of gear teeth. The vibration from transmission error moves to shaft and bearing. This vibration generates bearing force which exite gear box and finally radiate as noise outside. Therefore, studying transmission error is the most important to predict which is the fundamental reason of gear noise. In this paper, transmission error due to teeth deflection was predicted and shaft torsion was not considered in order to find only teeth deflection. For this reason, shaft was modeled as rigid, and only gear pair was modeled as flexible body. transmission error was predicted by Abaqus, FEA program, and this was compared for Spur and Helical type.
김범근(Beomkeun Kim),김흥섭(Heungseob Kim),김용수(Yongsu Kim),김홍철(Hongchul Kim) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Mineral/glass reinforced polypropylene compounds, as an alternative engine cover material, offers weight as well as cost reduction. The polypropylene compound’s low strength requires, however, careful consideration of structural failure in the design of the engine cover. In this study, fatigue failure of the mineral/glass reinforced polypropylene compounds engine cover is discussed. In order to predict dynamic behavior of the engine cover, natural frequencies of the system were calculated considering the damping effect of the structure. Extracted natural frequencies were compared with the measured data from experimental modal analysis (EMA). Dynamic time history of the stress distribution in the engine cover under vibration load and assembly load was calculated based on the extracted natural frequencies of the system. Experimental measurements of strains were performed to verify the results of the analysis. Based on the calculated stress data and measured S-N curve for the engine cover material, safety factors of the engine cover were predicted. In order to improve the durability of the engine cover, design modifications of the engine cover were investigated. Durability test results showed close correlation with the analysis data. Study showed that consideration of the assembly load was necessary to predict the fatigue failure of the engine cover system.
Kim, Heungseob,Kim, Pansoo Elsevier 2017 Reliability engineering & system safety Vol.159 No.-
<P><B>Abstract</B></P> <P>This research paper presents practical stochastic models for designing and analyzing the time-dependent reliability of nonrepairable systems. The models are formulated for nonrepairable systems with heterogeneous components having phase-type time-to-failure distributions by a structured continuous time Markov chain (CTMC). The versatility of the phase-type distributions enhances the flexibility and practicality of the systems. By virtue of these benefits, studies in reliability engineering can be more advanced than the previous studies. This study attempts to solve a redundancy allocation problem (RAP) by using these new models. The implications of mixing components, redundancy levels, and redundancy strategies are simultaneously considered to maximize the reliability of a system. An imperfect switching case in a standby redundant system is also considered. Furthermore, the experimental results for a well-known RAP benchmark problem are presented to demonstrate the approximating error of the previous reliability function for a standby redundant system and the usefulness of the current research.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Phase-type time-to-failure distribution is used for components. </LI> <LI> Reliability model for nonrepairable system is developed using Markov chain. </LI> <LI> System is composed of heterogeneous components. </LI> <LI> Model provides the real value of standby system reliability not an approximation. </LI> <LI> Redundancy allocation problem is used to show usefulness of this model. </LI> </UL> </P>
Kim, Heungseob,Kim, Pansoo Elsevier 2017 Reliability engineering & system safety Vol.159 No.-
<P><B>Abstract</B></P> <P>To maximize the reliability of a system, the traditional reliability–redundancy allocation problem (RRAP) determines the component reliability and level of redundancy for each subsystem. This paper proposes an advanced RRAP that also considers the optimal redundancy strategy, either active or cold standby. In addition, new examples are presented for it. Furthermore, the exact reliability function for a cold standby redundant subsystem with an imperfect detector/switch is suggested, and is expected to replace the previous approximating model that has been used in most related studies. A parallel genetic algorithm for solving the RRAP as a mixed-integer nonlinear programming model is presented, and its performance is compared with those of previous studies by using numerical examples on three benchmark problems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Optimal strategy is proposed to solve reliability redundancy allocation problem. </LI> <LI> The redundancy strategy uses parallel genetic algorithm. </LI> <LI> Improved reliability function for a cold standby subsystem is suggested. </LI> <LI> Proposed redundancy strategy enhances the system reliability. </LI> </UL> </P>
Kim, Sang-Myeong,Kim, Heungseob,Boo, Kwangsuck WILEY-INTERSCIENCE 2018 SHOCK AND VIBRATION Vol.2018 No.-
<P>A study is presented in this paper that uses a simple mechanical analogy to analytically tune the PD (proportional-derivative) controller of a linear flexible manipulator system. More specifically, the aim is to give simple closed-form solutions of the optimal P and D gains to yield the maximum bandwidth under a given damping requirement <I>or</I> conversely the maximum damping under a given bandwidth requirement. The idea of this study is based on the observation that the performance of the complete manipulator system is largely determined by the operational dynamics of the fundamental vibration mode. A lumped element method is thus applied to model this dynamics in terms of simple lumped mechanical elements. It subsequently turns out that the original servo control problem is analogous to a conventional Zener mount design problem, that is, mathematically, to optimize a third-order dynamic system consisting of the Zener model of a viscoelastic mount and an inertial object upon it. A design methodology is finally established to analytically determine the optimal elements of the mount, corresponding to the optimal control gains. Simulations and experiments were also conducted with a single-link flexible beam to support the model and the design methodology developed.</P>
구조화 마코프체인을 이용한 이종 구성품을 갖는 k-out-of-n 시스템의 수명분포 모형
김흥섭(Heungseob Kim) 한국신뢰성학회 2017 신뢰성응용연구 Vol.17 No.4
Purpose: In this study, the lifetime distribution of a k-out-of- n system with heterogeneous components is suggested as Markov model, and the time-to-failure (TTF) distribution of each component is considered as phase-type distribution (PHD). Furthermore, based on the model, a redundancy allocation problem with a mix of components (RAPMC) is proposed. Methods: The lifetime distribution model for the system is formulated by the structured Markov chain. From the model, the various information on the system lifetime can be ascertained by the matrix-analytic (or-geometric) method. Conclusion: By the generalization of TTF distribution (PHD) and the consideration of heterogeneous components, the lifetime distribution model can delineate many real systems and be exploited for developing system operation policies such as preventive maintenance, warranty. Moreover, the effectiveness of the proposed RAPMC is verified by numerical experiments. That is, under the equivalent design conditions, it presented a system with higher reliability than RAP without component mixing (RAPCM).
기어물림강성을 고려한 기어시스템 베어링진동예측에 관한 연구
김흥섭(Heungseob Kim),김병준(Byeongjun Kim),권용규(Youngkyu Kwon),부광석(Kwangsuk Boo),서창준(Changjun Seo) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The transmission error in gear causes vibration in the gear system, which is transferred to the gear shaft and transferred to the bearing connected to the shaft. Throughout this process of transmission, vibration is amplified and eventually transferred to the housing of the gear system, which is released into the air by noise from the mechanical system. In this paper, we present predictions on analytical verification for bearing vibration reduction based on contact stiffness for the most widely used pair of spurs.
Blocked force TPA기법을 이용한 압축기 가진력 예측
김흥섭(Heungseob Kim),유승민(Seungmin Ryu),윤득선(Duksun Yoon),백승환(Seunghwan Baek),김양수(Yangsoo Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The conventional transmission path analysis method has the advantage that it is possible to predict the excitation force and analyze the contribution according to the transmission path, so that the problem can be clearly identified. However, in order to avoid interference between transmission paths, it is required to separate the powertrain from the vehicle, which adds to the cost. In order to improve this, this study performed the prediction of the electric vehicle compressor excitation force using the blocked force TPA technique. This predicted blocking force can be used to predict the sound pressure inside the vehicle or design the compressor mount.