• International Journal of Automotive Technology
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• 제6권6호
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• pp.671-676
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• 2005

Spring is one of major suspension part of the light commercial vehicle (LCV). In the manufacturing process it is shot-peened to improve its fatigue strength. In this paper, residual stresses by shot peening were calculated through finite element analysis, and the effects of these residual stresses on fatigue strength of leaf spring were evaluated. Fatigue tests were performed with two kinds of specimens; one is actual leaf spring assembly, and the other is simulated 3-point bending specimen. Fatigue tests were performed under the loading condition that was measured on the proving ground. From the results, the maximum load-fatigue life relation of leaf spring was defined, and test results of 3 point bending specimen are in good agreement with those of leaf spring assembly. The effects of residual stresses by shot peening on fatigue strength of leaf spring is not large in the high load range, however, in the low load range, its effects were not negligible.

• 한국정밀공학회지
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• 제15권12호
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• pp.28-36
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• 1998

This investigation is the result of a structural analysis by the finite element method and static loading test for the optimal structural design of an electric railway vehicle made of stainless 301L materials. We analyzed the stress and displacement of the existing electric car-body structure for predicting the position of concentrated stress, the flow of stress, rigidity to be occurred in the car-body structure when it is subjected to the vertical load. It was exposed that the side sills and window corners around the bolsters are the weak parts of the electric car-body structure because the bolsters of the electric car-body structure were subjected to the vertical load and dynamic load to be occurred during running. The flow of stress and the cause of stress concentration in the weak zone were studied in order to prevent the concentration of stress and buckling. The rearrangement of the structure and the selection of the beam elements were also carried out for optimum design of the structure.

• 산업공학
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• 제17권2호
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• pp.233-241
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• 2004

The main subject to become a hub port is automation. The automated container terminal has already operated in advanced ports and it has been planned for the basic planning and operation design in domestic case. The key of automated container terminal is effective operation of both ATC(automated transfer crane) and AGV(automated guided vehicle) which is automated handling equipments. This is essential to productivity of automated container terminal. This study suggests the most optimal method of equipment operation in order to minimize loading time using each three types of effective ATC operation methods and AGV dispatching rules in automated container terminals. As the automated equipment operation causes unexpected deadlocks or interferences, it should be proceeded on event-based real time. Therefore we propose the most effective ATC operation methods and AGV dispatching rules in this paper. The various states occurred in real automated container terminals are simulated to evaluate these methods. This experiment will show the most robust automated equipment operation method on various parameters(the degree of yard re-marshaling, the number of containers and AGV)

• 터널과지하공간
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• 제16권4호
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• pp.288-295
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• 2006

본 연구에서는 발파 및 지진발생으로 인한 횡방향 지반진동에 대하여 KTX 차량 및 부산지하철을 대상으로 주행안전성을 평가하였다. 이를 위하여 휠/레일 상호작용 해석 WERIA프로그램인 프로그램을 이용하여 철도차량의 동적거동을 시뮬레이션 하였다. 또한 횡방향 지반진동이 철도차량에 유발할 수 있는 차륜/레일간의 큰 상대변위를 고려하기 위하여 차륜/레일간 접촉면의 기하학적 형상과 크리프힘을 반영하였다. 입력하중은 국내의 내진규정 특성에 부합하는 인공지진과 공사중 발생하는 발파진동을 사용하였다. 해석 결과 차륜/레일간의 상대변위와 탈선계수를 산정하여 철도 차량의 주행안전성을 평가한 결과 탈선가능성은 없는 것으로 나타났다.

• 한국항공우주학회지
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• 제36권9호
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• pp.923-928
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• 2008

파이로 충격은 고주파 영역까지 큰 가속도가 유발되는 천이 진동 현상으로 발사체에서는 주로 화약에 의한 분리 장치의 작동에 의해 발생하게 된다. 일반적인 발사체의 경우 단 분리, 페어링 분리, 위성 분리 이벤트에서 파이로 충격이 발생하게 되는데 이에 의해 위성 또는 발사체의 전자 장비가 비정상적인 기능을 보이거나 작동 불능 상태가 될 수 있다. 본 논문에서는 이러한 파이로 충격의 절연을 위해 와이어메쉬 절연계를 소개하였고 동일 단면을 기준으로 밀도와 높이를 다르게 9 종류를 제작하였다. 와이어메쉬 절연계의 전형적인 특성을 살펴보기 위해 기본적인 압축 시험을 수행하였고 더미 질량을 이용하여 파이로 충격 시험을 수행, 충격 절연 효과가 뛰어남을 검증하였다.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.145-154
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• 2003

Occupant simulation models have been used to study trends or specific design changes in several typical crash situations. The ATB, Articulated Total Body, was developed and used to predict gross human body responses to vehicle crashes and pilot ejections. Since the ATB source code is open to public, the user can add their own defined modules and functions. The introduction of seat belts into cars significantly decreased the injury risk of passengers in frontal impacts. In this paper, a new seat belt model was developed and implemented into the ATB. For this purpose, a subroutine of the new seat belt was constructed. A force-deflection function was added to replace an existing function to consider energy absorption. The function includes hysteresis effects of the experiment data of the loading and unloading parts of the seat belt load-extension curve. Moreover, this belt model considers a slip between ellipsoid and belt segments. This paper attempted to validate the ATB program which includes the subroutine of new belt models comparing with the real car frontal crash experiments and MADYMO frontal models. The analysis focusses on the human movement and body accelerations.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.139-145
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• 2007

Fretting is a kind of surface damage mechanism observed in mechanically jointed components and structures. The initial crack under fretting damage occurs at lower stress amplitude and lower cycles of cyclic loading than that under plain fatigue condition. This can be observed in automobile and railway vehicle, fossil and nuclear power plant, aircraft etc. In the present study, railway axle material RSA1 used for evaluation of fretting fatigue life. Plain and fretting fatigue tests were carried out using rotary bending fatigue tester with proving ring and bridge type contact pad. Through these experiments, it is found that the fretting fatigue limit decreased about 37% compared to the plain fatigue limit. In fretting fatigue, the wear debris is observed on the contact surface, and oblique cracks at an earlier stage are initiated in contact area. These results can be used as useful data in a structural integrity evaluation of railway axle.

• 무역상무연구
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• 제43권
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• pp.337-370
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• 2009

The Joint Cargo Committee of International Underwriting Association of London (IUA) and Lloyd’s Market Association (LMA) have issued the revised version of Institute Cargo Clauses A, B, C, Institute Cargo Clauses (Air) and their accompanying War and Strikes Clauses. The Institute Cargo Clauses ("ICC") were last revised in 1982. Following a two year long consultation process, the latest edition of the ICC clauses became available to the Market on 1st January 2009. The overall result of the amendments to the 1982 ICC has been to create clearer policies that are more favourable to the Assured. Exclusions have also been amended to the advantage of the assured. The Transit Clause has seen a large revision, again more favourable to the Assured. The insurance now attaches within the warehouse or place of storage when the goods are "first moved$\cdots$ for the purpose of the immediate loading into or onto the carrying vehicle or other conveyance for the commencement of transit" whereas previously the insurance would not attach until the goods left the warehouse. Furthermore, the insurance now terminates on completion of unloading from the vessel at (rather than delivery to) the final warehouse or at a warehouse prior to the destination named in the contract of insurance which the Assured or their employees elect to use either for storage or distribution.

• Smart Structures and Systems
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• 제14권5호
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• pp.869-881
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• 2014

This paper presents the materials analysis for combination of working modes of Magnetorheological (MR) damper. The materials were selected based on the optimum magnetic field strength at the effective areas in order to obtain a better design of MR damper. The design of electromagnetic circuit is one of the critical criteria in designing MR dampers besides the working mechanism and the types of MR damper. The increase in the magnetic field strength is an indication of the improvement in the damping performance of the MR damper. Eventually, the experimental test was performed under quasi-static loading to observe the performances of MR damper in shear mode, squeeze mode and mixed mode. The results showed that the increment of forces was obtained with the increased current due to higher magnetic flux density generated by electromagnetic coils. In general, it can be summarized that the combination of modes generates higher forces than single mode for the same experimental parameters throughout the study.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
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• pp.263-268
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• 2001

In this paper, we present a new heuristic algorithm fur buffer allocation in FMS (Flexible Manufacturing System). It is conducted by using a genetic algorithm and simulation. First, we model the system by using a simulation software, \"Arena\". Then, we apply a genetic algorithm to achieve an optimal solution. VBA blocks, which are kinds of add-in functions in Arena, are used to connect Arena with the genetic algorithm. The system being modeled has seven workstations, one loading/unloading station, and three AGVs (Automated Guided Vehicle). Also it contains three products, which each have their own machining order and processing times. We experimented with two kinds of buffer allocation problems with a proposed heuristic algorithm, and we will suggest a simple heuristic approach based on processing times and workloads to validate our proposed algorithm. The first experiment is to find a buffer profile to achieve the maximum throughput using a finite number of buffers. The second experiment is to find the minimum number of buffers to achieve the desired throughput. End of this paper, we compare the result of a proposed algorithm with the result of a simple buffer allocation heuristic based on processing times and workloads. We show that the proposed algorithm increase the throughput by 7.2%.t by 7.2%.