• Journal of Internet Computing and Services
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• v.6 no.2
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• pp.69-84
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• 2005

As the Internet users are increasing rapidly, a cluster web server system is attracted by many researchers and Internet service providers. The cluster web server has been developed to efficiently support a larger number of users as well as to provide high scalable and available system. In order to provide the high performance in the cluster web server, efficient load distribution is important, and recently many content-aware request distribution techniques have been proposed. In this paper, we propose a new content-aware load balancing technique that can evenly distribute the workload to each node in the cluster web server. The proposed technique is based on the hash histogram transformation, in which each URL entry of the web log file is hashed, and the access frequency and file size are accumulated as a histogram. Each user request is assigned into a node by mapping of (hashed value-server node) in the histogram transformation. In the proposed technique, the histogram is updated periodically and then the even distribution of user requests can be maintained continuously. In addition to the load balancing, our technique can exploit the cache effect to improve the performance. The simulation results show that the performance of our technique is quite better than that of the traditional round-robin method and we can improve the performance more than $10\%$ compared with the existing workload-aware load balancing(WARD) method.

• Journal of IKEEE
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• v.13 no.2
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• pp.232-240
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• 2009

This paper presents a robust vehicle detection and tracking algorithm for supervision of illegal parking. The proposed algorithm is composed of four parts. First, a vehicle detection algorithm is proposed using the improved codebook object detection algorithm to segment moving vehicles from the input sequence. Second, a preprocessing technique using the geometric characteristics of vehicles is employed to exclude non-vehicle objects. Then, the detected vehicles are tracked by an object tracker which incorporates histogram tracking method with Kalman filter. To make the tracking results more accurate, histogram tracking results are used as measurement data for Kalman filter. Finally, Real Stop Counter (RSC) is introduced for trustworthy and accurate performance of the stopped vehicle detection. Experimental results show that the proposed algorithm can track multiple vehicles simultaneously and detect stopped vehicles successfully in the complicated street environment.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.1
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• pp.35-41
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• 2002

It is extremely important to minimize network access time in constructing a high-performance PC cluster system For an SCI based PC cluster it is possilbe to reduce the network access time by maintaining network cache in each cluster node, This paper presents a CC-NUMA card that utilizes network cache for SCI based PC clustering The CC-NUMA card is directly plugged into the PCI solot of each node, and contains shared memory network cache, and interconnection modules. The network cache is maintained for the shared memory on the PCI bus of cluster nodes. The coherency mechanism between the network cache and the shared memory is based on the IEEE SCI standard. A CC-NUMA prototype card is developed to evaluate the performance of the system. According to the experiments. the cluster system with the CC-NUMA card showed considerable improvements compared with an SCI based clustser without network cache.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.608-614
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• 2006

The popularization of high-speed networks and the innovation of high-performance hardware/servers have enlarged the role of large-scale, highly distributed IT infrastructure. Though many criteria on the assessment of IT infrastructure can be considered, the survivability assessment is treated as the most important one due to the essential role as an infrastructure. While assessing the survivability of some given IT infrastructures, we can not only choose the best one among them but also improve their survivability by modifying their structure and security policies. In this paper, we propose a DMKB-based assessment system on the survivability of IT infrastructures, where DMKB is a kind of database which provides the known vulnerabilities and defense mechanism for many system components.

• Korean Journal of Construction Engineering and Management
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• v.10 no.2
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• pp.132-144
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• 2009

In this study, the basic data for calculating the proper construction cost as minimizing the uncertainty at the stage of forecasting construction cost with the basis of the analysis on the actual construction cost within completed domestic public apartment house. In this regard, 23 public apartment houses by each region which were ordered by the Korea National Housing Corporation and completed from 2004 to 2007 were selected as the objects of study. Four works such as common temporary installation, construction work, civil work and machine/equipment work which are the important direct cost items based on the actually inputted and settled construction costs were classified by completion year, region, architectural area, and the distribution type considering inflation rate. The sequent actual construction costs per 3.3m2 were compared and analyzed by each work, the proper construction costs were analogized and the calculating formula were presumed with the basis of average actual construction costs to be analyzed and presented.

• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.1-9
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• 2012

This study aims to propose a performance metric for the application of a horizontal air-exhausting system to be used for the reduction of vapor and/or moisture that exists in the waterproof layer, by evaluating the physical properties. For this reason, tests in accordance with current standards were carried out, and the results were examined. Finally, a proposal was established for a general performance metric that could be applied as fundamental data based on the user's judgment. This has some limitations, in that the object is existing merchandise, however it should be useful for application in the construction field. In the future, analysis of a wider area, including workability, should be added in the phase of field application.

• Korean Journal of Construction Engineering and Management
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• v.13 no.3
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• pp.143-151
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• 2012

The facility safety management in Korea does not secure efficiency as a safety management that is not constructed a maintenance manual. As such, disaster dangerous facilities are at a great danger for disaster occurrence. Accordingly, this study introduced revised requirement and revised level of requirement to field attendants to explore domestic facility safety management system, and set up and suggested a revised plan through brainstorming and attendants of central management institutions. This study is of importance that it reflects field attendants and attendants of central management institutions, suggests specific alternatives for realization to improve national level of institutional improvement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.71-84
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• 1992

Polymer-Impregnated Concrete(PIC) is a composite material of concrete and polymer. PIC has superior properties compared to conventional cement concrete, such as strength, stiffness, toughness, durability, water-proofing, chemical resistance. However, the usage of PIC has been limited to repairing materials and non-structural applications due to the lack of the design criteria and the analytical model to determine structural behavior. The objective of this study is experimentally to develop the optimum mixing proportions of polymer impregnants and the stress-strain responses, the strength characteristics, the fatigue and creep behaviors, and the durabilities of MMA(methyl methacrylate)-based PIC.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.553-554
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• 2011

자동차, 선박, 기계부품 등의 분야에서 고성능 컴퓨터를 활용한 공학 시뮬레이션 기술은 이미 널리 활용되고 있으며, 바이오, 나노뿐 아니라 금융 분야까지 확대되고 있는 추세이다. 공학 시뮬레이션을 수행하기 위해서는 CFD(Computational Fluid Dynamics), 기계구조, 병렬수치해석 등에 대한 고급 지식이 요구되는데, 이로 인해 산업체에서의 활용이 활발하지 못한 것이 현실이다. 이러한 문제를 해결하기 위한 하나의 대안으로 공학 시뮬레이션 프로세스의 자동화 기술이 등장했으며, 열유체, 피로내구, 진동, 충돌 등의 분야에서 특정제품이나 기술에 대한 시스템이 제안되었다. 국내에서는 에어포일(airfoil), 팬(fan), 기어(gear) 등의 제품이나 주조 기술에 대해 공학 시뮬레이션 자동화가 시도되었다. KISTI에서는 축류팬(axial fan) 시뮬레이션 자동화에 대해 프로토타입 시스템을 구축하였으며, 현대차에서는 자동차 부품에 대한 시뮬레이션 자동화 시스템을 구축하여 활용하고 있다. 미국 OSC(Ohio Supercomputer Center)의 경우 용접기술에 대한 시뮬레이션 자동화 시스템을 웹상에 구축하여 서비스를 오픈하였으며, 현재 전 세계 200여 기업이 이용하고 있다. 공학 시뮬레이션 자동화 기술이 보다 발전하기 위해서는 시뮬레이션 결과의 신뢰성, 적용 가능 분야 및 제품의 확대, 데이터보안 등이 확보되어야 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11c
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• pp.2347-2350
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• 2002

본 논문에서는 일반 데스크탑 PC의 디스플레이 성능에 적합하도록 작성된 유선의 웹 문서를 무선 인터넷 환경의 핸드헬드 계열 소형 단말에서도 효율적으로 표현하기 위한 변환 기법을 제시한다. 이는 기존의 단순한 텍스트 위주의 추출 및 형식의 변환과는 달리, 분석 및 변환을 위한 최소 내용 단위를 설정하고, 이들의 재배치를 통하여 원본 웹 문서의 정보를 보다 정확히 반영한다. 또한 새로운 인덱스 형식으로의 재표현을 통하여 기존의 페이지 조각과 계층적 구조의 인덱스 링크를 이용한 인터페이스보다 편리한 검색 및 페이지 이동을 제공한다. 이 기법은 보다 많은 정보를 복잡한 구조로 표현하는 현재의 웹 문서 특징을 반영하고, 이동 단말들의 고성능화 추세와 함께 화려한 무선 인터넷을 요구하는 사용자들을 고려한 것이다. 전체 변환 과정은 Layout-Forming Tag Analysis Algorithm, Component Grouping Algorithm Component Block Classification Method, Index Generation Method로 구성된다. 변환 시스템의 구성 모듈별 설계와 프로토타입의 구현을 통하여 제안하는 알고리즘 및 변환 방법을 평가하였고, 실제 웹 문서에 대한 실험 결과에서 단말의 소형 화면에 적합하게 변환된 모습을 확인하였다.