• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.430-433
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• 2003

Air-operated valve is one of principal valves that are using to control fluid flow. A period diagnosis for safety of power plants is necessary. But there are many difficulties such as economic loss caused by intone of high cost devices and a matter hard to deal with users. In this study we developed the diagnosis system that usersofpower plants are easy to handle. The diagnosis system is composed of database module, reliability analysis module, design safety nodule and diagnosis test and evaluation module.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.24-26
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• 2004

For past decade, medium voltage circuit breakers have used the spring-driven mechanical system for interrupting of electric power. However, these mechanisms have many disadvantages of high power consumption, mechanical control components and electrical switching ones for the coil current. Recently, the vacuum interrupter operated by permanent magnet actuator gives outlook on improved characteristic, higher reliability and cost price reduction as well as the feature of simple structure and few components. This paper deals with the dynamic characteristics of permanent magnet actuator used in the medium voltage distribution systems. Coupled finite element method is used to analysis the dynamic characteristics of permanent magnetic actuator and we compared with those of conventional ones.

• 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.

• 전력전자학회논문지
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• 제19권6호
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• pp.549-556
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• 2014

This study proposes a parallel operation strategy for small wind turbine systems. A small wind turbine system consists of blade, permanent magnet synchronous generator, three-phase diode rectifier, DC/DC buck converter, and the battery load. This configuration has reliability, simple control algorithm, high efficiency, and low cost. In spite of these advantages, the system stops when unexpected failures occur. Possible failures can be divided into mechanical and electrical parts. The proposed strategy focuses on the failure of electrical parts, which is verified by numerical analysis through equivalent circuit and acquired general formula of small wind power generation systems. Simulation and experimental results prove its efficiency and usefulness.

• Tribology and Lubricants
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• 제11권5호
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• pp.15-19
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• 1995

Learning from the failure of mechanical systems is a necessity, given that it is the understanding of how and why things fail that generates effective redesign. This subsequently enables the technology that surrounds us to become more reliable, safer, and more economical by extending component life and minimizing the wasteful decisions made to replace systems that am either sound for continued operation could be easily repaired. Considerations for cost-effective decision making, so as to promote healthy machinery, equipment, and structures, are discussed in terms of learning from failure analysis, improving via reliability engineering, and achieving longevity through integrated diagnostics.

• 대한기계학회논문집A
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• 제31권5호
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• pp.625-634
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• 2007

KARI SUAV program was initiated to develop a Smart Unmanned Aerial Vehicle with innovative smart technologies. SUAV is a tilt rotor aircraft of which rotor system is 3-bladed, gimbaled hub type. Several existing concepts of gimbaled hub were analyzed and compared to investigate the applicability to SUAV rotor system design. From the result of these investigations, it was concluded that a new design concept of low cost and high reliability characteristics was necessary for the rotor hub development of SUAV. The design requirements of new gimbal hub concept and the design results were presented. Also, the analysis results to verify the satisfaction of design requirements of SUAV rotor system were presented.

• 한국생산제조학회지
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• 제25권6호
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• pp.434-439
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• 2016

Optical fiber splice closure serves to protect connection parts from external environment. Moreover, it functions as a connection, junction, and distribution in diverse surroundings such as aerial, underground, duct, and pole. In this research, first, the optical fiber splice closure, its configuration, and the design problem were briefly investigated. Second, the design and application for in-line cable closure were studied to satisfy its construction and technical features. The injection molding conditions and optimal design were conducted to save time and cost during the manufacturing process. Third, methods to minimize loss via of optical fiber cable while strongly fixing optical fiber cable with optical cable holder to prevent fracture were researched, and tests such as perfect air tightness and mechanical and environmental performance were conducted.

• 한국의류산업학회지
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• 제12권1호
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• pp.68-79
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• 2010

This study was fulfilled in the purpose of proposing construction strategies of fashion information industry through the analysis of information user's satisfaction/dissatisfaction on information quality. The research was performed through a depth interview. Data were collected from 18 fashion information users(designers and merchandisers) who were working at fashion apparel industry during October to November 2007. Results from the study showed that there were three dimensions and 18 components of satisfaction/dissatisfaction on fashion information quality: Information quality(understandability, value-added, level of detail, relevance, diversity, objectivity, completeness, accuracy, quantitativeness), Service quality(responsiveness, accessibility, cost efficiency, empathy, reliability), System quality(currency, ease of use, format, timeliness). And the information users were perceiving that there were some changes in notion of preferring information, searching for information and usage of information.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.252-259
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• 2001

Integrated condition monitoring is required to monitor effectively the machine conditions since machine failures could not be monitored accurately by any single measurement parameter. Application of various condition monitoring techniques is therefore preferred in many cases in order to diagnosis the machine condition. However it inevitably requires lots of maintenance cost and sometimes it could be proved to over-maintenance unnecessarily. This could happen especially when one measurement parameter closely correlates to another. Therefore correlation analysis of various monitoring parameters has to be performed to improve the reliability of diagnosis. In this work, Pearson correlation coefficient was used to analyze the correlation between condition monitoring parameters of an over-loaded machine system where the vibration, wear and temperature were monitored simultaneously. The result showed that Pearson correlation coefficient could be regarded as a good measure for evaluating the availability of condition monitoring technology.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.256-261
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• 2014

Endurance test procedures of multipurpose tactical vehicle is constructed by comparing the Korea defence standard and TOP-2-2-506. The plan was to make the best reflect the operational environment and the actual production purposes. Endurance test of multipurpose tactical vehicle more stringent than the existing other military vehicles validation procedures. But the test plan, it is possible to reduce the cost and schedule of long verification that occurs because of the Endurance test. Through a comparison of the dynamic characteristic analysis, change of test center was to ensure the reliability and validity.