• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.135-142
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• 2001

The effect of tensile hold time on the creep-fatigue interaction in AISI 316 stainless steel was investigated. To study the fatigue characteristics of the material, strain controlled low cycle fatigue(LCF) tests were carried out under the continuous triangular waveshape with three different total strain ranges of 1.0%, 1.5% and 2.0%. To study the creep-fatigue interaction, 5min., 10min., and 30min. of tensile hold times were applied to the continuous triangular waveshape with the same three total strain ranges. The creep-fatigue life was found to be the longest when the 5min. tensile hold time was applied and was the shortest when the 30min. tensile hold time was applied. The cause fur the shortest creep-fatigue life under the 30min. tensile hold time is believed to be the effect of the increased creep damage per cycle as the hold time increases. The creep-fatigue life prediction using artificial neural network(ANN) showed closer prediction values to the experimental values than by the modified Coffin-Manson method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.47-53
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• 2010

The paper presents a method for decision the optimal cycle time during the vehicle traffic control in single intersection with AHP. To solve this uncertainty optimization problem, the optimization index in the form of linear addition and fuzzy measurement is assumed and fuzzy integral is used. Examples of solution for two cases of optimal cycle time in two traffic controller are presented and compared.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.1
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• pp.80-86
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• 2011

This study compared and analyzed manual tapping and automatic tapping regarding tapping process characteristics of titanium hard-to-cut-material. Tapping process characteristics of titanium hard-to-cut-material are evaluated as the quality of a screw, wear of a tap, economic analysis, and cycle time etc. The type of screw threads after manual tapping is formed as an irregular type of screw threads, and perfect screw threads are created after automatic tapping. In addition, the chip type after manual tapping process is formed as the discontinuous chip due to work hardening, and the powder type of chip after automatic tapping process is created. In terms of cycle time, an automatic tapping process is shortened by 70% compared to manual tapping process. Insert tip wear of an automatic tapping shown in the process of 5-hole tapping is not found, but hand tap wear for finish cutting is most severe.

• 한국경영정보학회:학술대회논문집
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• 2007.11a
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• pp.611-616
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• 2007

반도체 패키징 공장에서 싸이클타임(Cycle-time)을 정확히 예측하는 것은 납기일 준수를 통해 고객만족도를 향상시킬 수 있고, 보다 효율적인 스케쥴링을 가능하게 하여 공장 가동률을 높일 수 있게 한다. 그러나 반도체 패키징은 제품 종류가 다양하고 제품마다 특화된 기술을 사용할 뿐만 아니라 공정 순서나, WIP에 따라 싸이클타임이 크게 영향을 받아 그 정확한 예측이 매우 어렵기 때문에 현장 전문가의 판단에 의존하는 경우가 많았다. Fab공정의 경우 전문가를 도와 좀 더 정확한 예측에 도움을 주기 위해 그 동안 전통적 통계 기법 및 시뮬레이션에 기반한 의사결정 모형이 많이 연구되었는데, 최근에는 기계학습 및 인공지능 기법을 사용한 연구가 눈에 띄고 있으며 기존의 방법보다 우수한 성능을 보여 주는 것으로 나타났다. 하지만 아직 기계학습 및 인공지능을 이용한 충분한 연구가 진행되지 못하고 있는 실정이다. 따라서 본 연구에서는 사례기반 추론을 사용하여 패키징 공정의 싸이클타임을 예측하고자 하였으며 그 성능을 인공신경망 모형, 의사결정나무 모형, 그리고 해당 분야 전문가의 예측치와 비교하였다. 실험결과에 따르면 사례기반추론 모형이 가장 뛰어난 성능을 보이는 것으로 나타났다.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.4
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• pp.479-484
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• 2006

This paper discusses a fitness of the control on intersection using fuzzy analytic hierachy process. The validity of control of traffic signal on intersection is the fitness of phase and cycle on the intersection. The validity of the controller is cleared by the comparison of the delay time of vehicle. Fuzzy analytic hierachy process clears the grade of validity of the fixed cycle time controller and adaptive fixed cycle time and fuzzy trafic controller and proposes a new control type a traffic signal by this fuzzy analytic hierachy process.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1250-1255
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• 1990

This paper discusses an optimal cyclic scheduling problem for a FMC (Flexible Manufacturing Cell) modeled by a two-machine flowshop with two machining centers with APC's (Automated Pallet Changers), an AGV (Automated Guided Vehicle) and loading and unloading stations. Cyclic production in which similar patterns of production is repeated can significantly reduce the production lead-time and WIP (Work-In-Process) in such flexible, automated system. Thus we want to find an optimal cyclic schedule that minimizes the cycle time in each cycle. However, the existence of APC's as buffer storage for WIP makes the problem intractable (i.e., NP-complete). We propose an practical approximation algorithm that minimizes, instead of each cycle time, its upper bound. Performances of this algorithm are validated by the way of computer simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1883-1888
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• 2000

In this paper a computer aided analysis method is proposed for durability assessment in the early design stages using dynamic analysis, stress analysis and fatigue life prediction method. From dynamic analysis of a vehicle suspension system, dynamic load time histories of a suspension component are calculated. From the dynamic load time histories and the stress of the suspension component, a dynamic stress time history at the critical location is produced using the superposition principle. Using linear damage law and cycle counting method, fatigue life cycle is calculated. The predicted fatigue life cycle is verified by experimental durability tests.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1309-1313
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• 2008

This paper suggests an example of modification of the durability test specifications of electronic control unit for an automotive system in phase of design validation. The basic concept to redefine the specifications of durability test is based on the Arrhenius relationship for accelerated temperature test and the modified Coffin-Manson model for temperature cycle test. The ambient temperature of the powered-event durability test is increased to reduce the required test time of the current specification. Furthermore, the holding time between the events to cool down the temperature of the components is shortened and the resultant temperature rise affects the durability of the components. Thus, the acceleration factor due to the increased temperature range of temperature cycle is also estimated by the modified Coffin-Manson model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.23-27
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• 2005

Generally, when the injection molds are made in advanced nations, the improvement of a quality and production rate is obtained by using CAE. In this paper, the methodology which is possible to reduce the cycle time of injection molding process is studies by using the cooling analysis with CAE(Moldmax). In case of changing the cooling system design with the analysis result of CAE, the manimum reduction of the cycle time runs into 30 percent. Finally, the average reduction of the cycle time is 17.8 percent.

• Journal of Korean Port Research
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• v.14 no.4
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• pp.395-406
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• 2000

In this paper, an improved high efficiency gantry crane for container transportation is designed. The basic concept of the designed crane can be used with modification of the classical gantry crane instead of changing lots of them. This crane can reduce the cycle time more than the classical gantry carne. The high efficiency gantry crane can improve the productivity of the container transportation job because of reducing cycle time. The loading and unloading capability are compared with classical crane. The result show that show that the proposed crane has better performances than classical type.