• Annual Conference of KIPS
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• 2005.05a
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• pp.1257-1260
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• 2005

인증서 상태 확인은 해당 거래에 사용되는 인증서에 대해 유효한 인증서임을 판별하기 위한 과정으로 인증서 표준이 제정된 이후로 계속적으로 연구되고 있는 분야이다. 현재 가장 보편적으로 이용되는 인증서 상태 확인 기법은 인증서폐지목록(CRL : Certificate Revocation List)을 이용하는 기법이다. 이 기법은 방법 자체가 가지고 있는 시간격차 문제와 물리적 파일 처리의 과부하로 인하여 사용에 많은 제약이 따른다. 이를 해결하기 위해 온라인 인증서 상태 프로토콜(OCSP : OnLine Certificate Status Protocol) 기법이 제시되었다. 이 기법은 CRL 기법의 비 실시간성 문제를 해결한다. 하지만 서비스 요청 서버의 과부하 문제와 구조적 집중화 문제로 인하여 인증서 상태를 확인 하는데 소요되는 시간이 다소 오래 걸린다는 문제가 있다. 본 논문에서는 검증 요청자의 신원정보에 대한 해쉬값을 이용하여 인증서 상태 확인 요청을 하고 이를 통해 인증서 상태 확인 과정을 진행함으로써 통신 부하를 감소시키고 실시간으로 인증서 상태를 확인 할 수 있는 검증 요청자 신원 정보를 이용한 인증서 상태 확인 메커니즘을 제안한다.

• Fire Science and Engineering
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• v.25 no.3
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• pp.28-41
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• 2011

Regulation of Escape and fire-prevention of Building of South Korea were enacted as a part of building codes in 1962. Since it was enacted, the law has gone through many changes. In this study, evaluated the fire safety of the law about the case of a hotel that the fire risk are expected to be higher whenever it was changed. As a result, the current law has gotten better in tire safety since it was enacted. However, especially it could be confirmed that the evacuation safety is insufficient in the lower level of hotel building. In the case of accommodation, because the occupants become aware of fire lately, they have not enough time to escape. Therefore, this study suggests that it is needed to come up with an effective counterplan about the interior finish materials, fire door and fire compartments that the smoke layer descending time is longer.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.70-78
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• 2004

Although set accelerating agents are used generally in New Austrian Tunneling Method, the standards for test methods and quality of set accelerating agents are not prescribed domestically. In this study, the proprieties of the various standards and the characteristics of set accelerating agents for shotcrete were evaluated. The alkali contents of set accelerating agents based on silicate, aluminate and cement were higher than those of alkali-free ones. From the result, it is thought that the quality control of aggregate should be enhanced and that the number of test cycle of alkali-aggregate reaction should be increased. The setting times of cement paste with set accelerating agents based on silicate and alkali-free ones were different largely with mixing methods. Compressive strength of mortar with set accelerating agents based on silicate, aluminate and cement at one day satisfied the specifications of Korea Concrete Institute. However, the strength ratio compared to control mix at 28 days showed as $50{\~}65\%$ except for the alkali-free set accelerating agents. As a results of setting time and strength test, the establishment of domestic standards that can reflect the characteristics of materials and construction methods of tunnels and that can increase quality of set accelerating agents is required immediately.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.838-845
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• 2009

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models are reviewed. Three earthquake records of El-centre, Santa-Monica, Taft and three artificial earthquake records in accordance with Korea standard are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with various hysteresis models. As results, story shear force is increased by maximum 60% according to hysteresis model. And Story drift ratio is increased by maximum 42% according to hysteresis model. And The result with clough model shows the maximum hinge distribution state.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.4
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• pp.280-283
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• 2009

To improve coding performance of scalable video coding which is an emerging video coding standard as an extension of H.264/AVC, SVC uses not only intra prediction and inter prediction but inter-layer prediction. This causes a problem that computational complexity is increased. In this paper, we propose an efficient intra prediction mode decision method in spatial enhancement layer to reduce the computational complexity. The proposed method selects Inra_BL mode using RD cost of Intra_BL in advance. After that, intra mode is decided by only comparing DC modes. Experimental results show that the proposed method reduces 59% of the computation complexity of intra prediction coding, while the degradation in video quality is negligible.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.1-9
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• 2002

본 논문은 현재 무선 LAN 환경에서 적용되고 있는 매체접근제어 프로토콜인 IEEE 802.11 CSMA/CA를 이용함으로써, 음성 위주의 항공이동통신에서 음성과 데이터 채널을 통합하여 사용하도록 하고 있다. 또한, 표준으로 제정되어 있는 기존의 CSMA/CA 매체접근제어 프로토콜에 대한 이해를 바탕으로 성능 개선 방안을 제안하였으며, 이를 바탕으로 채널 효율을 향상시켰다. IEEE 802.11 매체접근제어(MAC, Medium Access Control) 프로토콜은 데이터 유형에 따라 채널을 두 개의 구간(PCF와 DCF 구간)으로 나누어 전송하도록 하고 있다. 본 논문에서는, 데이터 유형별로 적용되는 구간 중, DCF 구간에서의 패킷간의 충돌 가능성을 줄임으로써 데이터 전송 효율을 높이는데 주안점을 두고 있다. 제안 방안으로는 경쟁 구간에서의 전송에서 충돌에 따른 손실을 보완할 수 있도록 Wireless Window Protocol(이하, WWP)을 적용한 후 전송 과정을 제어하였다. Hidden 터미널의 영향이 적으므로 가시권내 통신에 적합한 기존의 2-Way CSMA/CA 프로토콜을 항공통신에 적용하여 상태 천이 과정을 5개에서 6개로 세분화하였고, 주어진 확률에 의하여 나누어진 두 개의 그룹별로 상태 천이 과정을 다르게 적용하였다. 따라서, 채널이 한 항공기에 의해 점유되는 PCF를 제외한, DCF 구간에서의 데이터 전송 효율을 높일 수 있었다. 시뮬레이션은 채널 대역폭과 패킷 크기 등을 파라미터 값으로 하여 수행하였으며, 시뮬레이션 결과 CSMA/CA에 비해 새로 제안한 알고리즘이 데이터 전송 과정에서 발생하는 충돌 가능성을 감소시킴으로써 성능이 향상됨을 알 수 있었다.

• Journal of Broadcast Engineering
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• v.18 no.1
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• pp.43-58
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• 2013

Richmedia Service means that interactive media service can provide view with various multimedia elements(such as Video, Audio, Text) at same time. Various Multimedia elements can be serviced by Scene Description technology standards like BIFS(Binary Format for Scenes) and LASeR(Light Application Scene Representation). By providing Scene Component information, richmedia service is available to various multimedia services. so users is available to personalized services fitting temporal and spatial options. In conventional technology, when the scene is changed by user or service, mobile deletes the scene of configuration information and makes new scene of configuration information. this is a very inefficient way. In this paper, Propoesed that by using DOM(Document Object Model) method, to pass only the dynamic configuration part, changes scene method.

• Journal of Korea Multimedia Society
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• v.11 no.7
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• pp.956-965
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• 2008

H.264/AVC is the newest video coding standard of ITU-T VCEG and the ISO/IEC MPEG, offering a significant performance improvement over previous video coding standards. However, the computational complexity of H.264/AVC is drastically increased because of new technologies such as intra prediction, variable block size, quarter-pels motion estimation/compensation, etc. In this paper, we propose a fast intra prediction scheme which has two step processing. The first step is a fast block size decision which can be calculated only in one block without considering all cases of $4{\times}4$ block and $16{\times}16$ block. The complexity of the intra prediction can be reduced by using boundary difference values of macroblock. After selecting the block size, we can make mode decision using the neighbouring reference pixels and representative pixels of the block in the second step. The experimental results show that the proposed algorithm saved on the average 41.5% encoding time without any significant PSNR losses.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.4
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• pp.555-565
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• 2024

The government has enacted legislation to enforce selective dismantling in order to increase the recycling of construction waste. Therefore, this study aims to propose a standard quantity per unit estimation method, crucial for determining the expenses associated with large-scale demolition projects necessary for public development, particularly in the context of extensive land development ventures. Four individual houses were thoroughly examined and tested. We surveyed the house to create a floor plan and conducted a detailed investigation of interior materials in order to propose a Standard Quantity per Unit for cost estimation of the selective dismantling work. The process encompassed precise measurement of the houses, creation of schematics, thorough scrutiny of interior materials, and division of the dismantling process into components such as ceilings, walls, and floors. The duration of each dismantling task was meticulously documented. Particular emphasis was placed on refining the methodology to accommodate factors such as window openings, thereby ensuring a heightened level of precision compared to preceding studies. The outcomes of this study are anticipated to serve as practical benchmarks for estimating costs in demolition projects, thereby fostering sustainable development within the construction industry.

• Korean Security Journal
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• no.16
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• pp.357-371
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• 2008

Currently, the security operations in nation's key foundations in Korea are performed by private police and special security guard in accordance with the Private Police Act and Security Business Act, respectively. In 1960s, The Korean Government introduced the private police system in terms of the national security issues, but it was just a hurriedly-set plan on the basis of Japanese Sunsa system as by that time there was no such system revitalized. However, the special security guards could offer wider range of security services including those of the private police with the enactment and revision of the Security Business Act 1976 and April 2001, respectively. Moreover, the expectations and interests rose over the special security guards in nation's key foundations after 9.11Terror Event in the U. S. 2001. However, as we investigated the current education/training system for the special security guard, we found that such education/training which is not activating the specialty of special security guard will not respond to the social demands. Special security guard owns its own characteristics other than those of general security guard as they are in service in nation's key foundations. Thus, the effcient management and training for the special security guard is the most important matter for the safety and security of nation's key foundations. Therefore, the well-educated special security guard through the reorganized and specialized education/training for the protection of nation's key foundations is expected to offer qualitatively improved security services.