• 한국기계가공학회지
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• 제7권2호
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• pp.8-15
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• 2008

Current trend of design technologies shows engineers to objectify or automate the given decision-making process. The numerical optimization is an example of such technologies. However, in numerical optimization, the uncertainties are uncontrollable to efficiently objectify or automate the process. To better manage these uncertainties, Taguchi method, reliability-based optimization and robust optimization are being used. Based on the independence axiom of axiomatic design theory that illustrates the relationship between desired specifications and design parameters, the designs can be classified into three types: uncoupled, decoupled and coupled. To best approach the target performance with the maximum robustness is one of the main functional requirements of a mechanical system. Most engineering designs are pertaining to either coupled or decoupled ones, but these designs cannot currently accomplish a real robustness thus a trade-off between performance and robustness has to be made. In this research, the game theory will be applied to optimize the trade-off.

• 소음진동
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• 제10권4호
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• pp.692-701
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• 2000

Escalators are widely used for mass transportation in public places. In recent years, strict requirements on the comfort and reliability for the public transportation have drawn a great attention to vibration in escalators. This paper presents a dynamic model for escalators to be used for the analysis and design of low vibration escalators. The dynamic model is developed so as to reflect the physical observation on peculiar characteristics in escalators such as the difference between up-moving and down-moving, and the abnormal vibration affected by the load applied. For validation of the dynamic model developed, experimental results are compared with numerical results from the model. The numerical study shows that the developed model may be useful for the analysis and design of escalator systems.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.686-691
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• 2007

The ride comfort is more important according to train speedup. Generally it is defined as the vehicle vibration. There are many studies on evaluation method of ride comfort for railway. In the case of Korean high speed train(HSR 350x), the ride comfort has been assessed by statistical method according to UIC 513R. To verify the design requirements for the performance of HSR 350x, the qualification tests had been conducted from August 19, 2002 to December 2004 and the stabilization and reliability tests are carried out nowadays. Up to December 2006, total test runs and the accumulated milage of the train were 357 times and 164,000km, respectively. A total of 352 ride indices had been acquired through the on-line test from Aug. 2002 to Dec. 2006. In this paper, we have reviewed the characteristics of ride comfort for HSR 350x according to the operational conditions, such as load and track conditions, season and used time, by using the tests data.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.601-611
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• 2007

Onboard ATC performs the train speed ristriction function by receiving the speed limit on sections of track from wayside ATC. Onboard ATC can protect passenger from collision and derailment, and so on. So, the high level of safety and reliability for Onboard ATC is required, and by this reason, it is also required to improve the safety of Onboard ATC by applying the result of safety analysis on the Onboard ATC into its design and developing from the concept definition to the detailed desing phase. The paper introduces, when developing Onboard ATC, the safety improvement of Onboard ATC can be accomplished by applying system requirements from Risk Analysis into software and hardware.

• 산업기술연구
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• 제15권
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• pp.113-122
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• 1995

By integrating WDM to OPS unit which plays an important role for the reliability of CPN, we made it possible to provide CATV, VOD, and high-speed data services simultaneously and to meet the requirements for new services in the future. For the design of optimal system, the link analysis of power budget has been performed. Also, the prototyped system has been tested with STM-1 level signals to confirm functions such as transmission, distribution, and protection. The results proved that when occurred out-of-order or recovery of ONU, the system did the pertinent switching with minimum loss for high-speed data services. Also for video distribution services, the system has distributed STM-1 level signals successfully.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.423-425
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• 2007

In this paper, Medium Access Control(MAC) protocol designed for Wireless Body area Sensor Network(Bio-MAC) is proposed, Because in WBSN, the number of node is limited and each node has different characteristics. Also, reliability in transmitting vital data sensed at each node and periodic transmission should be considered so that general MAC protocol cannot satisfy such requirements of biomedical sensors in WBSN. Bio-MAC aims at optimal MAC protocol in WBSN. For this, Bio-MAC used Pattern -SuperFrame, which modified IEE E 802.15.4-based SuperFrame structurely. Bio-MAC based on TDMA uses Medium Access-priority and Pattern eXchange -Beacon method for dynamic slot allocation by considering critical sensing data or power consumption level of sensor no de etc. Also, because of the least delay time. Bio-MAC is suitable in the periodic transmission of vital signal data. The simulation results demonstrate that a efficient performance in WBSN can be achieved through the proposed Bio-MAC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.383-384
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• 2015

DC system is still unexploited in public distribution systems. As the weight of cost efficiency and reliability requirements of distribution networks are expected to increase in the future, with the utilization of distributed generation, there will be demand for novel distribution techniques. The utilization of the Low Voltage DC (LVDC) distribution system opens new possibilities for network development. This paper presents analysis of steady state and transient state according to the number of pole in LVDC distribution system.

• 정보통신설비학회논문지
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• 제9권3호
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• pp.102-106
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• 2010

Recently process industries from oil and gas procedures and mining companies to manufactures of chemicals, foods, and beverages has been exploring the USN (Ubiquitous Sensor Networks) technology to improve safety of production processes. However, to apply the USN technology in the large-scale plant industry, reliability and security issues are not fully addressed yet, and the absence of the industrial sensor networking standard causes a compatibility problem with legacy equipment and systems. Although this situation, process industry such as energy plants are looking for the secure wireless plant solution to provide detailed, accurate safety monitoring from previously hard-reach, unaccordable area. In this paper, SPSF (Smart Plant Safety Framework based on Reliable-Secure USN) is suggested to fulfill the requirements of high-risk industrial environments for highly secure, reliable data collection and plant monitoring that is resistant to interference. The SPSF consists of three main layers: 1) Smart Safety Sensing Layer, 2) Smart Safety Network Layers, 3) Plant Network System Layer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1063-1068
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• 2008

A lens system of a camera module for mobile phones is comprised of the composition and design of various shapes of lens. To improve responses such as the modular transfer function (MTF), a lens system should always be constructed by considering uncertainty that can be caused by manufacturing and assembly error. In this study, tolerance optimization using the Latin Hypercube Sampling (LHS) technique is performed. In order to reduce the computational burden of the tolerance optimization process and decrease the influence from numerical noise effectively, we use the Progressive Quadratic Response Surface Modeling (PQRSM), which is one of Sequential Approximate Optimization (SAO) techniques. Using this method, we achieved optimal tolerance for each lens and obtained reliability for satisfying user‘s requirements. In addition, through the design process the manufacturing and assembly cost of a lens system was reduced.

• 한국CDE학회논문집
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• 제20권4호
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• pp.328-336
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• 2015

We proposed a methodology to automatically extract the requirements from the documents and check the consistency and traceability among them. The documents include not only text but also PDF or image files. We also suggest a method to visualize the result with maps, numbers, and graphs. By comparing the results with those of manual reviews from experts, we show that it is necessary to use knowledge-based method in future instead of the wordbased method for improving the reliability. The results can be applied effectively for already existing documents.