• 상하수도학회지
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• 제29권3호
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• pp.395-406
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• 2015

This research carried out an analysis on input cost and leakage reduction effect by leakage reduction method, focusing on the project for establishing an optimal water pipe network management system in the Taebaek region, which has been executed annually since 2009. Based on the result, optimal cost-benefit analysis models for water distribution network rehabilitation project were developed using DEA(data envelopment analysis) and multiple regression analysis, which have been widely utilized for efficiency analysis in public and other projects. DEA and multiple regression analysis were carried out by applying 4 analytical methods involving different ratios and costs. The result showed that the models involving the analytical methods 2 and 4 were of low significance (which therefore were excluded), and only the models involving the analytical methods 1 and 3 were suitable. From the result it was judged that the leakage management method to be executed with the highest priority for the improvement of revenue water ratio was installation of pressure reduction valve, followed by replacement of water distribution pipe, replacement of water supply pipe, and then leakage detection and repair; and that the execution of leakage management methods in this order would be most economical. In addition, replacement of water meter was also shown to be necessary in case there were a large number of defective water meters.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2125-2128
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• 2011

The continuous welded rail(CWR) track without the rail expansion joint has many advantages over the conventional track in a variety of fields including the speed-up and the ride comport. However, due to the excessive axial force in the CWR and the track-bridge interactive behavior, inevitably, the rail expansion joint must be installed at the vulnerable zone such as the bridge end zone, etc. In this rail expansion joint zone, the frequency of the maintenance work to repair the track irregularity is on the rise. This is because that the creep of the sleeper is occurred in the moveable zone of the rail expansion joint. In this study, among the several options for reducing the track irregularity on the rail expansion joint zone, the application and efficiency of the tied sleeper is investigated. Field test construction has been conducted, then the progress of the track irregularity and the frequency of the maintenance work are analyzed before and after the filed test construction.

• 한국구조물진단유지관리공학회 논문집
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• 제10권1호
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• pp.183-189
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• 2006

RC 구조물에 대하여 FRP로 보수 보강 작업시, 주변 온도에 따른 일정기간의 양생을 필요로 하며 또한 양생과정 중 외부의 진동원으로부터 유해한 작용을 받는 것을 피하는 것이 바람직하다. 따라서 본 연구에서는 탄소섬유쉬트(CFS)로 보강되는 RC구조물에 대하여, CFS양생과정 중 작용하는 반복하중이 보강성능에 미치는 영향을 일련의 보 실험을 통하여 분석하였다. 실험결과 CFS 1겹 보강의 경우에는 CFS부착 후 24시간, 2겹 보강의 경우에는 12시간동안 외부로부터의 반복하중을 차단하는 것이 필요한 것으로 판단되었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.250-253
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• 2001

Recently, based on the smart structure concept, optical fiber sensors have been increasingly applied to monitor the various engineering and civil structural components. Repairs based on adhesively bonded fiber reinforce composite patches are more structurally efficient and much less damaging to the parent structure than standard repairs based on mechanically fastened metallic patches. As a result of the high reinforcing efficiency of bonded patches fatigue cracks can be successfully repaired. However, when such repairs are applied to primary structures, it is needed to demonstrate that its loss can be immediately detected. This approach is based on the "smart patch" concept in which the patch system monitors its own health. The objective of this study is to evaluate the potentiality of application of transmission-type extrinsic Fabry-Perot optical fiber sensor (TEFPI) to the monitoring of crack growth behavior of composite patch repaired structures. The sensing system of TEFPI and the data reduction principle for the detection of crack detection are presented. Finally, experimental results from the tests of center-cracked-tension aluminum specimens repaired with bonded composite patch is presented and discussed.

• 한국유체기계학회 논문집
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• 제3권2호
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• pp.7-14
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• 2000

For a given axial turbine blade, reverse design method is developed to improve blade efficiency, optimize blade profile, or repair parts etc. In this process, design parameters for designing axial turbine blade are induced. The induced design parameters are as follows; ellipse at leading edge, radios of trailing edge, axial chord, tangential chord, wedge angle at the inlet, and unguided turning angle. Suction and pressure surfaces of turbine blade are described by cubic polynomials. Two sample blades we chosen and their blade profiles are measured at the mean radius. Values of design parameters for sample blades are obtained by the reverse design method. Re-designed blade profiles using calculated design parameters are compared with the measured data, and they show good agreement. So, the developed design method could be applied to design general turbine blades. Various blade shapes are designed, and they show that designed blade profiles can be adjusted by controlling design parameters.

• Tribology and Lubricants
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• 제16권6호
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• pp.440-447
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• 2000

It's a tendency to strengthen related international laws as the importance on marine oil pollution recently becomes the issue. According to the regulation of IMO, oil discharge from ships is allowed under 15 ppm only and oil filtering equipment is essential. However, for large ships using heavy fuel oil of over S.G 0.98 and viscosity 380 cSt and system oil, it has been in difficulty to process with existing filtering type of oily water separator. Oily water pre-separator of laminated plate type which is one of gravity type separator has very simple structure and it also makes easier to maintain and repair. In another words, it fits well to process large amount of rich oil with high specific gravity. In this paper, oily water pre-separator of laminated plate type has been studied. The function of emulsified oil and 4 different types of oil have been analyzed and each character has been investigated and proved by experiments. As the result of it, the efficiency of separating oil water has been advanced by 10% in case equipped with pre-separator. In addition, the higher temperature is and the more laminated plate has, it turns out to be getting more effect.

• 한국산학기술학회논문지
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• 제11권10호
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• pp.3950-3957
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• 2010

무선 센서 네트워크는 한정된 자원의 센서 노드들로 구성되어 있고, 한번 구성된 후에는 유지 보수가 어렵다는 단점을 갖고 있다. 따라서 무선 센서 네트워크에서는 에너지 소비를 최소화하고, 한정된 자원을 효율적으로 사용하여 네트워크 수명을 최대화하는 것이 중요한 문제이다. 본 논문에서는 클러스터링 방식에서 클러스터 수를 효율적으로 지정하여 에너지 소모량을 최적화하는 기법을 제안한다. 이 기법은 무선 전송에 소비되는 에너지양은 거리(임계값)에 따라 많은 차이가 있으므로 이러한 임계값을 고려하여 클러스터 수를 지정함으로써 에너지 소비를 줄이는 방식이다. 실험을 통하여 제안된 클러스터링 기법은 LEACH(Low-Energy Adaptive Clustering Hierarchy)에 비해 전체 에너지 소모량 측면에서 높은 성능을 나타냄을 확인하였다.

• 한국정보통신학회논문지
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• 제14권9호
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• pp.2040-2048
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• 2010

현대 사회에서는 정보 시스템을 이용한 업무의 편의성과 효율성은 높아지고 있지만, 네트워크의 발달로 인한 악성코드, 시스템 해킹, 내부자 정보유출 등의 역기능이 날로 대두되고 있다. 이로 인하여 시스템의 복구와 관리에 막대한 인력과 비용이 소요되고 있다. 기존의 시스템은 두 가지 측면에서 바이러스, 악성코드를 감시하고 치료하는 보안 솔루션과 컴퓨터의 시스템감시, 관리, 복구, 백업 등 유지보수를 하는 네트워크 관리 솔루션으로 나눌 수 있다. 본 논문에서는 Active Write Filter 메커니즘, NFS기반의 기술을 응용하여 기존 시스템의 사용자 데이터 등의 보전문제점을 보완하여 정보보호 및 불법 저작물 등 지적재산권의 문제 해결이 가능한 시스템을 설계하였다.

• 한국통신학회논문지
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• 제22권10호
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• pp.2123-2135
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• 1997

고집적 SRAM을 구성하고 있는 일반적인 메모리 셀을 이용하여 저항성 단락을 MOSFET의 게이트-소오스, 게이트-드레인, 소오스-드레인에 적용시키고, 각 단자에서 발생 가능한 개방 결함을 고려하여 그 영향에 따른 메모리의 자장노드의 전압과 VDD에서의 정전류를 PSPICE 프로그램으로 분석하였다. 해석 결과를 고려하여 메모리의 기능성과 신뢰성을 향상시키기 위해 기능 테스트와 IDDQ 테스트에 동시에 적용할 수 있는 O(N)의 복잡도를 갖는 테스트 알고리즘을 제안하였다. 테스트의 질과 효율을 좀 더 향상시키기 위해 메모리에서 발생되는 고장을 검출하는 BIST 회로와 정전류의 비정상적인 전류의 흐름을 발생시키는 결함을 검출하는 BICS를 설계하였다. 또한 구현한 BIST/BICS 회로는 고장 메모리의 수리를 위해 고장 및 결함의 위치를 검출할 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1166-1169
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• 2003

The issue with the drainpipe now a day is that they are laid underground Causing us to perform additional work to repair, such as digging up the ground and peeling off the insulator that surrounds the pipe. And such series works are difficult that concession appears from government and municipal office. However, if we can save time and money. Performance of piping robot that we are studied in existing session through fixing unit and improvement of cutting byte shorten and wished to heighten work efficiency. This is why we aye trying to develop a unit that can cut up the projecting parts which connects with the interior part of the drainpipes.