• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.671-679
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• 2016

Bridges, which constitute one of the key facilities in a social infrastructure, are easily accessed and used by users, so that keeping their performance above a certain level is essential. According to various cases in the U.S., Japan and Europe with a long construction history, it is expected that the maintenance cost of bridges in Korea will increase continuously in the future, so a rational decision making system based on engineering factors is necessary to optimize the performance of and maintain them by allocating the limited budget efficiently. This study is a preliminary basic study for the purpose of developing a common asset management system for managing all of the bridges and maintaining the level of service provided by them. The scope of this preliminary study is limited to bridges in urban areas. The bridge asset management system for bridges in urban areas, their level of service (LOS) and performance measure (PM) were developed by carrying out a workshop consisting of both experts and stakeholders. The analysis on the weights of the value and performance measure for each performance indicator was carried out by using the multi-attribute utility theory and the AHP method. In order to confirm the application of the weight of the performance measure and value of the performance indicator, six bridges in an example city were selected, LOS analysis was applied and its results were reviewed.

• Journal of the KSME
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• v.44 no.6
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• pp.53-58
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• 2004

일반적으로 사용단계의 구조물은 시간이 경과함에 따라 초기의 설계, 시공상 오류에 의한 초기결함, 반복하중 그리고 취약한 환경 등 외부 조건에 노출될 경우에는 구조물 본연의 성능을 점차 상실하게 되어 심지어는 인명과 재산권을 위협하는 대형 붕괴사고를 일으키기도 한다. 따라서 구조물의 사용성을 적정 수준 이상으로 유지하기 위해서는 정기적인 점검을 통해 잔존수명을 미리 예측하여야 함은 물론, 최적의 보수시기와 보수방법을 알려줄 수 있는 시설물 모니터링시스템이 요구되고 있다. (중략)

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.57-65
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• 2013

The development of the oil refining industry has resulted in an annual 120 million tons of sulphur, which is a by-product of the desulphurization process. To exploit this abundance, the applications of sulphur must be expanded. as excellent durability of reuse of leftover sulphur which has high potential for utilization in construction materials, the study is actively in progress. Meanwhile, there has been active research on semi-rigid pavements that draw on the strengths and overcome the weaknesses of asphalt and concrete pavements. Acrylate is used to prevent cracking but involves a high cost, thus, an alternative material is required. As such, this study presents methods on the reuse of leftover sulphur and examines the engineering performance of grout containing sulfur polymer emulsion (SPE) for use in semi-rigid pavements. Our analysis shows that grout in which 30% of acrylate is replaced with SPE has superior properties in terms of time of flow and strength compared to regular grout. However, performance declined when more than 50% of acrylate was replaced by SPE, indicating that the optimum replacement level is 30%. Through SEM analysis, we found that grout with utra harding cement in this study at three hours had similar hydration properties to that of Type 1 Ordinary Portland Cement (OPC) at seven days, and maintained the properties regardless of grout containing SPE. OPC and grout with a replacement level of 30% displayed similar levels of chloride invasion resistance, whereas grout without SPE was far less resistant. Within the scope of this paper, the optimum replacement level of acrylate with SPE was found to be 30% in consideration of various properties such as time of flow, strength, and chloride invasion resistance.

• Fire Science and Engineering
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• v.26 no.6
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• pp.64-71
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• 2012

The fire resistance test has been conducted under the standard fire & loading conditions to evaluate fire resistance performance, according to applying to methods of the lateral confinement reinforcement by prestressed Wire Rope and fire resistance reinforcement by Fiber-Cocktail and load ratio for high strength concrete column. The test result, for 60 MPa high-strength concrete column, It was indicated that applying to the wire rope has improved axial ductility in the fire condition, and fire resistance performance has been enhanced by more than 23 %. In addition to this, in case of applying the wire rope to 60 MPa high-strength concrete column, load can be judged that about 70 % of designed load is appropriate. If the Wire Rope and Fiber-Cocktail is applied to 100 MPa high-strength concrete column, It was shown that the fire resistance performance was enhanced by 4 times as much as applying only hoops.

• 월간 기계설비
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• s.46
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• pp.74-89
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• 1994

현재 범국가적 차원에서 지속적인 국가 경제 발전과 국제수지 개선을 위하여 추진되고 있는 정부의 에너지 절약사업에서 건물부문이 차지하는 에너지절약 효과는 막중하다. 특히 전체주택에서 공동주택이 차지하는 비율은 1990년에 32.1$\%$, 서울시의 경우 51.3$\%$로 전체 주택의 과반수를 넘어섰으며, 수도권의 대단위 아파트단지의 개발과 함께 공동주택의 증가추세는 당분간 지속될 전망이다. 본 연구는 공동주택의 최적난방 운전기법 개발을 위한 1차년도의 연구로서 현행 공동주택의 난방운전 실태를 조사, 분석하고 각 난방법에 따른 문제점 및 최적제어 알고리즘의 개발을 위한 자료 도출을 주 목적으로 진행되었다. 1차년도에 수행된 연구의 주요 내용을 살펴보면 다음과 같다. 공동주택의 난방에너지 소비현상은 단지에 따라 최대 3배이상의 열사용량에 차이가 있는 것으로 나타났다. 열사용량의 차이는 건축의 기본 열성능, 설비시설의 수준 및 노후화정도에 영향을 받으나 동일 연대의 단지들에서도 최대 80$\%$이상의 열사용량이 차이를 보이고 있었으며 이는 기계실 및 각 세대의 난방운전방법 및 제어수준에 따른 것으로 평가되었다. 세대의 층별, 위치별 열사용량 분석에 의하면 층별 열사용량차이가 큰 것으로 분석되었으며, 특히 최상층부와 최하층부의 열사용량이 뚜렷이 많이 나타나 단열성능의 강화가 요구되는 것으로 나타났다. 한편 샘플단지에 대한 측정 데이터를 통해 적정 열량공급시간대의 설정과 외기온의 변화에 따른 적정 온수공급온도의 설정조건 및 유량제어 효과등에 대한 분석 및 검토를 하였으며, 이를 통해 2차년도의 개발목표인 최적운전제어 방안의 제시를 위한 자료를 구축하였다. 또한 각 세대의 기밀성능이 공동주택의 열성능에 미치는 영향을 도출하기 위하여 샘플단지에 대해 트레스가스 측정법과 Blower Door법에 의하여 환기 및 기밀상태를 평가 하였으며 측정주호에 대한 환기를 예측할 수 있는 환기예측평가식을 제시하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.133-141
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• 2017

Traffic volume increases according to highway expansion and industrial development which causes repetitive defect and durability degradation on pavement. The research of quality assurance system used abroad has introduced Korea. Korea Expressway Corporation (KEC) has developed a Quality Performance Index (QPI) that quantitatively assesses the level of quality of the final product, and practical applications. Assessment factor on concrete pavement consisted of pavement thickness, compressive strength, IRI and spacing factor. Assessment factor on concrete pavement is determined by empirical evaluation factor from abroad. In this study, analysis of evaluation factors of concrete pavement by using pavement life prediction simulation and measured data were evaluated with consideration of feasibility of the assessment factor. Pavement life, performance and durability are affected by pavement thickness, compressive strength, IRI and spacing factor in assessment factor on concrete pavement, QPI.

• The KIPS Transactions:PartC
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• v.8C no.3
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• pp.319-326
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• 2001

본 논문에서는 다단계상호연결 네트워크에 기반한 입력버퍼 구조의 ATM 스위치에 관해서 언급한다. 제안된 방법은 HOL 블록킹으로 인해 균일 트래픽(uniform traffic) 하에서 최대 약 58.6%의 처리율을 넘지 못하는 문제를 해결 할 수 있는 방법을 제시하며, 또한 오류허용 기능을 확장시키기 위하여 베이스라인 네트워크에서 버디 연결 매핑 및 제한연결 매핑 특성을 이용한 다중경로를 제공할 수 있는 버퍼 기법에 관하여 언급한다. 시뮬레이션에 의한 성능 평가 결과, 기존 방식과 비교하여 좋은 처리율과 셀 손실율을 보였으며, 더욱이 오류 스위치의 증가에도 불구하고 처리율의 수준은 적정한 셀 지연 범위 내에서 유지될 수 있음을 보여주고 있다.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.8
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• pp.472-483
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• 2002

This paper presents the design and implementation of a cache file system, umcFS, which is specifically designed to provide an efficient caching and transmission of streaming media. The proposed file system is based on the concept of file disk and implemented as an application level on top of a general-purpose file system. The file disk favors the continuity of cached media and provides an efficient I/O mechanism for cache server. umcFS statically allocates control blocks as well as media cache blocks. These blocks are referenced by the single-level indirect management structure. As the file system is designed as an application level, it is easy to develop and port to other systems. The performance of the implemented system shows that umcFS performs about 13% better than the native file system in randomly accessing the cache blocks of 1024KB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.193-197
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• 2016

The performance of Precision Guided Missiles is estimated by using hit probability only, which is calculated by hits against total amounts of fires in current domestic live-fire tests. It has a limitation in judging the performance of all produced Precision Guided Missiles by using the calculated hit probability according to the result of live-fire test, because the overall characteristics of the produced Precision Guided Missiles are not considered. In other words, a method is needed to estimate the confidence level which is more reliable than simply calculated hit probability according to the result of live-fire test for guaranteeing the hit probability of Precision Guided Missiles by certain level, which is already being operated or produced. This paper introduces a method to estimate the confidence level of Precision Guided Missiles by minimum live-fire tests using Hypergeometric distribution and Bayes' rule suitable for the characteristics of Precision Guided Missiles, which are small production, high costs and unable to check whether the missile hits the target or not before the live-fire tests. Also, this paper suggests a reasonable confidence level for showing the performance of the Precision Guided Missiles using the results of live-fire tests and domestic and foreign literature, when the result of live-fire tests will be decided.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.4
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• pp.10-17
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• 2020

The recent earthquake in Korea caused large and small damages to many school building. School building is an important building that is used as a shelter in the event of disaster. Among the seismic retrofit methods, the internal steel braced frame type method is used for its relatively easy construction and excellent performance. In this study, the maximum shear force and displacement were compared and examined by applying the brace frame to existing concrete school buildings. As a result, we verified the adequacy of the analytical model and compared and examined the effect of brace-height ratio on the span of the existing school buildings. The adequacy of the maximum shear force and displacement relationship can be confirmed in the model with a length of 0.3. In addition, seismic frame was applied to the actual non-seismic reinforced concrete school building, and the seismic performance was evaluated by nonlinear static analysis(Push-over analysis) according to the ratio of brace-height. As a result, the increase of the brace-height according to the brace-height ratio has the effect of increasing the maximum shear force and maximum load at the performance point. But the collapse of the braced frame due to the increase in the lateral stiffness occurred, indicating that seismic retrofit according to the proper brace-height is necessary. Therefore, in the seismic retrofit design of brace frame of existing school building, it is necessary to select the proper brace-height after retrofit analysis according to the brace-height ratio.