• Journal of the Korean Data and Information Science Society
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• 제17권4호
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• pp.1375-1386
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• 2006

In life testing, the lifetimes of test units under the usual conditions are so long that life testing at usual conditions is impractical. Testing units are subjected to conditions of high stress to yield informations quickly. In this paper, the inferences of parameters on the three step-stress accelerated life testing are studied. The two-parameter exponential distribution with a failure rate function that a log-quadratic function of stress and the tempered failure rate model are considered. We obtain the maximum likelihood estimators of the model parameters and their confidence regions. A numerical example will be given to illustrate the proposed inferential procedures.

• 한국국방경영분석학회지
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• 제29권1호
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• pp.88-111
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• 2003

This paper is to suggest strategic options for improving the export performance of the plant and construction industry. The overall objective of this study is to explore the feasibility of a sustained export performance in the plant and overseas construction industry by an analysis of its international competitiveness and technological competence. The empirical work of this study relates to a chosen sample of Korean and non-Korean firms in the plant and construction industry sector. Primary data was collected through a comprehensive questionnaire survey administered to plant and construction firms in twelve countries, including Korea. The actual number of firms for which full information at a sufficient level of disaggregation was obtained was 62, a response rate of 44.6％. Of these, 42 firms were drawn from Korean plant and construction firms and the remaining 20 firms from 11 other countries. The structure of responding firms by industry shows a total of 29 plant exporters and 33 construction firms. Data analysis was carried out using SPSS statistical technique such as Multiple Regression in order to examine the linear relationship among variables. The findings of the study indicate that export success and failure in plant and construction export markets is determined by firm size and by various qualitative variables. The high export volume (export success) of Plant and construction exporters is more strongly influenced by mutual economic cooperation and number of employees than by sales volume and competent knowledge of the plant and construction markets. It was also found that weak political and diplomatic relation between countries, low sales volume and lack of bid experience have an adverse effect and represent serious barriers to exports.

• 한국멀티미디어학회논문지
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• 제20권7호
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• pp.1073-1089
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• 2017

Changes in the business environment and increased competitiveness have led many companies to consider Business Process Reengineering(BPR) as a means to improve performance. However, while some BPR projects have been successful among the many companies that have performed BPR, most of the reengineering efforts have been deemed unsuccessful as the project failed. There are many answers to this, but the most important point is that the effective linkage between process innovation and information system construction is insufficient. Even if the reform of consciousness is carried out through the promotion of management innovation activities such as BPR, and the process is improved, management infrastructure can not be continuously maintained if infrastructure, especially information system, is not built up to support it. In this paper, we propose BPR and information system combining methodology for successful BPR execution and information system construction, and describe the result of BPR consulting performance when constructing information system and compare the improvement of failure risk factor. In addition, we present the case through the case of K company, and finally present customer satisfaction through post evaluation after completion of K company information system construction project implementation.

• 한국지반환경공학회 논문집
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• 제19권12호
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• pp.65-72
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• 2018

최근 무인항공시스템의 활용으로 농작물 작황조사, 접근위험지역의 시설물 현황조사, 재해재난 모니터링 및 3차원 모델링 등 그 활용 분야가 확대되고 있는 실정이며, 건설, 인프라, 영상, 측량, 농업, 감시, 수송 등 실제로 여러 분야로 활용사례가 계속 늘어나고 있다. 특히, 산사태와 같은 사면 붕괴 발생 시 무인항공시스템 적용에 대한 시도가 많아지고 있으며, 무인항공시스템은 3차원 비행이 가능하기 때문에 접근하기 어려운 공간 정보를 확인할 수 있다. 하지만, 이러한 장점에도 불구하고 사면 붕괴 발생시 무인항공시스템 활용은 아직도 제한적인 실정이다. 본 연구에서는 이러한 한계성 극복을 위하여 사면 붕괴로 인한 토사량을 무인항공시스템의 영상정보로 산정하는 기법을 고찰하였다. 본 연구를 통해 산악지역 등 접근이 어려운 지역에서 사면 붕괴 발생시 복구공사에 필요한 토사량의 정보를 취득하는데 무인항공시스템 영상정보를 활용할 수 있을 것으로 판단된다.

• 한국지반신소재학회논문집
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• 제15권4호
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• pp.105-115
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• 2016

본 연구에서는 강우에 의해 붕괴가 발생한 식생옹벽의 현장사례를 바탕으로 붕괴원인을 분석하였으며, 분석결과를 이용하여 복구방안을 제시하였다. 또한 복구방안으로 제시된 대책공법에 대한 안정성을 평가함으로써, 그 타당성을 검증하였다. 사례현장의 붕괴원인 분석결과, 지반조사 및 옹벽구조물에 대한 안정성 검토를 수행하지 않은 채 구조물 계획을 수립하였고, 배수계획 누락과 재료 및 다짐관리 기준이 현행 국가기준에서 요구하는 수준을 만족하지 못하는 등 현장조건에 부합하는 설계가 이루어지지 않았다. 또한, 가시설 공법 검토 및 시공관리의 미흡 등도 붕괴의 주요 원인으로 판단하였다. 이를 바탕으로 흙막이 구조물, 지반보강 및 블록식 보강토옹벽을 이용하여 현장조건이 고려된 복구 대책공법을 제시하였다. 그리고 각 공법의 안정성을 평가한 결과, 소요안전율을 확보함으로써 제시된 대책공법으로써의 타당성을 검증하였다. 따라서 옹벽구조물의 시공 시에는 적합한 설계법의 적용과 함께 시공관리를 통하여 구조물의 안정성을 확보할 필요가 있음을 확인하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.168-169
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• 2014

Construction Technology Service is currently hardly managed due to failure to offer standard management system of service performance, company performance, and business evaluation in every Ordering Agencies. After Construction Technology Promotion Act is enforced in May 2014, Ordering Agency obligates them to report to Minister of Land and Transportation within 10 days upon contract/ amendment/ completion. In 2013, in advance to enforcement of this law, performance management system for construction technology service was developed for a test run. However this system only applies to main contractors while management and operation of subcontractors are unavailable that causes problems on connection and integration with Experience Management Trustee. Therefore, this research will establish systematic foundation that enables real-time information of service performance and evaluation of subcontractors to result standardization of performance and evaluation for public ordered services.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.322-329
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• 2006

On the way of construction in harbor area, scourin problems took place slowly failure of embankment in the beginning of construction in sites. For studying on the scouring properties during revetment construction in silty sand soil layers, this paper is carried out on lessons of case studies of numerical seepage analysis, scouring countermeasures in dredged landfill area.

• Coupled systems mechanics
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• 제12권2호
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• pp.183-197
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• 2023

Scarce research has been published on crack propagation fracture of flywheels manufactured with carbon fiber-reinforced polymers. The present work deals with a calculation method to determine the conditions for which a crack propagates in the axial direction of the flywheel. The assumptions are: flywheels made with just a single thick ply or ply clustering laminates, oriented following the hoop direction; a single crack is analyzed in the plane defined by the hoop and axial directions; the crack starts close to one of the free edges; its axial length is initially large enough so that its tip is far away from that free edge, and the crack expands the entire circumferential perimeter and keeps its concentric position. The developed method provides information for a good design of flywheels. It is concluded that a fracture-based crack propagation criterion generally occurs at a lower speed than a stress-based criterion. Also, that the evolution of failure with thickness using the fracture criterion is exponential, demonstrating that thin flywheels are relatively not sensitive to crack propagation, whereas thick ones are very prone.

• 한국통신학회논문지
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• 제32권8B호
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• pp.539-546
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• 2007

개인 방송 서비스를 다수의 사용자들에게 제공하기 위해서 본 논문에서는 오버레이 멀티캐스트 기반의 알고리즘을 적용한 효율적이고 향상된 성능을 제공하는 miniOverlay Broadcasting Control Protocol(mOBCP)을 제안하였다. mOBCP는 서비스를 받고자 대기하는 자식 노드들에게 대기시간을 최소한으로 줄이면서 가능한 빠르게 부모 노드를 찾을 수 있는 알고리즘과 서비스를 받던 기존 부모 노드의 경로에 Failure가 발생 되었을 경우 새로운 부모를 찾아서 빠르게 다시 서비스를 가능하게 할 수 있는 성능 효율적인 Mechanism을 본 논문에서는 제안한다. 성능비교는 제한된 트리 구성 시간 변화에 대한 지연(Latency)을 시뮬레이션을 통하여 결과를 얻어내었으며 결과를 통해 제안된 기법의 효율성을 보여주고 있다.

• 한국지진공학회논문집
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• 제27권3호
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• pp.147-155
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• 2023

This study aims to present a method to evaluate the relative risk of failure due to liquefaction of domestic small to medium-sized earthfill dams with a height of less than 15 m, which has little information on geotechnical properties. Based on the results of previous researches, a series of methods and procedures for estimating the probability of dam failure due to liquefaction, which calculates the probability of liquefaction occurrence of the dam body, the amount of settlement at the dam crest according to the estimation of the residual strength of the dam after liquefaction, the overtopping depth determined from the amount of settlement at the dam crest, and the probability of failure of the dam due to overtopping was explicitly presented. To this end, representative properties essential for estimating the probability of failure due to the liquefaction of small to medium-sized earthfill dams were presented. Since it is almost impossible to directly determine these representative properties for each of the target dams because it is almost impossible to obtain geotechnical property information, they were estimated and determined from the results of field and laboratory tests conducted on existing small to medium-sized earthfill dams in previous researches. The method and procedure presented in this study were applied to 12 earthfill dams on a trial basis, and the liquefaction failure probability was calculated. The analysis of the calculation results confirmed that the representative properties were reasonable and that the overall evaluation procedure and method were effective.