• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.726-733
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• 2016

In this study, a computer simulation of the three types of air distribution systems, open type system, aisle partition system and aisle containment system, to evaluate the applicability of the aisle partition system on a data center server room. The variables of the simulation were the height and location of the partition fixed on the top server rack. The energy efficiency of the air distribution systems were confirmed to be excellent in the order of the aisle containment system, aisle partition system, and open type system. In the cold aisle partition system, the height of the partition that can be effective in saving cooling energy by obstructing sufficient air recirculation was found to be more than 0.9m. In the hot aisle partition system, the height of the partition was found to be more than 0.8m.

• Journal of the Korean Geosynthetics Society
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• v.10 no.3
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• pp.43-51
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• 2011

This paper describes the results of pullout tests in the laboratory, which are conducted to assess the pullout performance of recently developed geosynthetic strip reinforcement with rounded band anchor. The geosynthetic strip can be used as reinforcements in reinforced soil wall with concrete block facing. The pullout resistance of the geosynthetic strip with rounded band anchor is mobilized by the combination of the interface friction between soil-reinforcement surface and the passive soil resistance caused by the rounded band anchor. Therefore, both the friction resistance and the passive resistance have to be considered in design. From the pullout test results, when the rounded band anchor are formed in the end part of the geosynthetic strip, pullout strength increases about from 10% to 65%. The passive resistance can be evaluated based on the pullout test results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.11C
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• pp.1124-1131
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• 2002

The banyan network is a popular and basic structure of the multi-stage ATM switches. This paper presents a novel approach to resolve the internal blocking of the banyan network by using a Non-Blocking Permutation Generator (NBPG). The NBPG performs two functions, i.e., the first is to extract the conflict cells from the incoming cells and Ole second is to re-assign new input port addresses to the conflict cells. As a result, NBPG generates non-blocking I/O permutations. To estimate the performance of the NBPG, we provide the results of several simulations.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.323-329
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• 2006

The aim of this study was to evaluate the retrievability of Resilon as a root canal filling material Twenty-seven human single-rooted extracted teeth were instrumented utilizing a crown down technique with Gates-Glidden burs and ProFile system. In group1 (n = 12) canals were obturated with gutta percha and AH-26 plus sealer using a continuous wave technique and backfilled. In group 2 (n = 15) Resilon was used as a filling material. Then teeth were sealed and kept in $37^{\circ}C$ and 100% humidity for 7 days. For retreatment, the samples were re-accessed and filling material was removed using Gates-Glidden burs and ProFiles. Teeth were sectioned longitudinally to compare the general cleanliness and amount of debris $({\times}\;75)$ using SEM. Chi-square test was used $({\alpha}\;=\;0.05)$ to analyze the data. The total time required for removal of filling materials was expressed as mean ${\pm}SD$ (min) and analyzed by the Student t-test $({\alpha}\;=\;0.05)$, Required time for retreatment was $3.25\;{\pm}\;0.32$ minutes for gutta percha/ AH 26 plus sealer and $3.05\;{\pm}\;0.34$ minutes for Resilon. There was no statistically significant difference between the two experimental groups. There was no significant difference between the groups in the cleanliness of the root canal wall. This study showed that Resilon was effectively removed by Gates-Glidden burs and ProFiles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2428-2435
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• 2014

Numerical analysis with ALE (Arbitrary Lagrangian Eulerian) Adaptive Meshing technique was performed to evaluate the pullout capacity of the embedded suction anchors (ESA) in uniform clay. The numerical method was verified by the previous study, analytical results based on limit-equilibrium theory and centrifuge tests. The pullout capacity of the ESA under horizontal, vertical, and inclined loading were evaluated, and the effect of initial rotation of the ESA on pullout capacity was also investigated. The analysis results showed that the maximum horizontal capacity was obtained at the mid-point, and the each vertical capacity gave the similar value regardless of the loading points. Furthermore, the inclined capacity was decreased as the load inclination angle increased at the mid-point of the anchor, and almost the same pullout capacity was obtained when the initial rotation angles were below 30 degrees.

• Journal of the Economic Geographical Society of Korea
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• v.19 no.3
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• pp.491-511
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• 2016

This paper attempts to understand the nature and dynamics of global value chains in the auto industry using the OECD TiVA 2015 edition on the bilateral foreign value added in exports over the period 1995-2011 and employing the techniques of social network analysis such as the computation of network measures and visualization of value added trade flows. It is shown that there has been a tendency towards increasing production fragmentation both within and across regions. The automotive value-added network is found to have small-world properties with a hierarchical, clustered and dense structure. The differences among the US, Germany and China as major suppliers of foreign value added in global automotive value chains are remarkably revealed. Although the fragmentation of production has been developed on a global scale, a dichotomous tension between center and periphery and domestic and foreign capital lies behind it.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.167-173
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• 2014

The embedded suction anchor, ESA, is one type of mooring anchor systems which utilizes the suction pile or caisson to penetrate the anchor into the sea bed and develops its capacity under pullout load. In this study, the numerical analysis using ALE (Arbitrary Lagrangian Eulerian) Adaptive Meshing technique was performed to simulate the pullout behavior of the ESA, and the results were compared to those of the previous research, centrifuge model tests and the analytical method based on limit equilibrium theory. The pullout behaviors of the ESA under horizontal, vertical, and inclined loading were evaluated. The analysis results showed that the maximum horizontal pullout load was developed when the location of loading point was at the mid-point, and the each vertical pullout load gave the similar value regardless of the locations of the loading points. The pullout load decreased as the load inclination angle increased at the mid-point of the anchor.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.81-81
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• 2003

목적 : 현재, 많은 병원이 방사선과 의료영상정보를 기존의 필름형태로 판독하고, 진료하는 방식에서 PACS 를 도입하여 디지털 형태로 영상을 전송, 저장, 검색, 판독하는 환경으로 변화하고 있다. 한편, PACS 가 가지는 가장 큰 제한점은 휴대성의 결핍이다. 본 연구는 이동형 장치가 가지는 호스트의 이동성 및 휴대성의 장점들을 살리면서, 무선 채널 용량의 한계, 무선 링크 사용이라는 제약점들을 감안하여 의료영상을 JPEG2000 영상압축 방식으로 부호화한 후 무선 환경을 고려한 전송 패킷의 크기를 결정하고자 하였으며, 무선 통신 중 발생되는 패킷 손실에 대응하기 위한 자동 오류 수정 기능도 함께 구현하고자하였다. 방법 : Window 2000 운영체계에서 의료영상을 로드하고, 데이터베이스화하며, 저장하고, 다른 네트워크와 접속, 제어가 가능한 PC급 서버를 구축하였다. 영상데이터는 무선망을 통해 전송하기 때문에 가장 높은 압축비율을 지원하면서 에너지 밀도가 높은 JPEG2000 알고리즘을 사용하여 영상을 압축하였다. 또한, 무선망 사용으로 인한 패킷 손실에 대비하여, 영상을 JPEG2000 방식으로 부호화한 후 각 블록단위로 전송하였다. 결과 : PDA에서 JPEG2000 영상을 복호화 하는데 걸리는 시간은 256$\times$256 크기의 MR 뇌영상의 경우 바로 확인할 수 있었지만, 800$\times$790 크기의 CR 흉부 영상의 경우 약 5 초 정도의 시간이 걸렸다. CDMA 1X(Code Division Multiple Access 1st Generation) 모듈을 사용하여 영상을 전송하는 경우, 256 byte/see 정도에서는 안정된 전송 결과를 보여주었고, 1 Kbyte/see 정도의 전송의 경우 중간 중간에 패킷이 손실되는 결과를 관찰할 수 있었다. 반면 무선 랜의 경우 이보다 더 큰 패킷을 전송하더라도 문제점은 발견되지 않았다. 결론 : 현재의 PACS는 유선과 무선사이의 인터페이스의 부재로 인해 유무선 연동이 되지 못하고 있다. 따라서 이동형 JPEG2000 영상 뷰어는 PACS가 가지는 문제점인 휴대성을 보완하기 위하여 개발되었다. 또한 무선망이 가지는 데이터 손실에 대하여서도 허용할 수 있는 범위에서 재전송을 가능하게 함으로서 약한 연결성을 보완하였다. 본 JPEG2000 영상 뷰어 시스템은 기존 유선상의 PACS와 이동형 장치간에 유기적인 인터페이스 역할을 하리라 기대된다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2001.11b
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• pp.91-94
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• 2001

MPEG-4 시스템은 장면 자체를 하나의 구성 요소로 여기는 기존의 시스템과는 달리, 그 장면을 구성하는 부호화 또는 복호화된 A/V 객체(Audio/visual Objects)들을 하나의 단위로 인식하여, 다양한 멀티미디어 컨텐츠의 장면을 구성(Scene Composition)하고 표현 하는 것에 그 특징이 있다. 이러한 MPEG-4 시스템의 객체 기반 특징은 다양한 사용자와의 대화성(Interactivity)을 가능하게 하며 , 또한 편리한 컨텐츠 편집 및 재사용 등이 가능하기에 차세대 디지털 방송 컨텐츠 제작에 중요하게 활용될 전망이다. 객체 기반 A/V 편집 도구는 MPEG-4를 기반으로 차세대 디지털 방송 컨텐츠 제작을 용이하게 하기 위한 제작/편집 도구로써 , 장면을 표현하기 위하여 BIFS(Binary Format for Scene description)와 XMT(eXtensible MPEG-4 Textual format) 포맷을 모두 사용하고 있다. BIFS 포맷은 저작된 결과물을 바이너리 형태로 표현하기 때문에, 저작된 결과물을 전송하는 데에는 용이하나, 중간에 저작된 결과물을 확인하기 어렵고, 또한 기존의 다른 어플리케이션과의 상호 작용(Interoperability)과 교환(Exchange)에도 어려움이 따른다. 이에 반해, XMT는 차세대 마크업 언어로 각광 받고 있는 XML 에 그 기반을 두고 있기에 저작된 결과물을 제작자가 쉽게 저작물을 이해할 수 있으며, SMIL 과 X3D 같은 다른 어플리케이션과의 상호작용과 교환 또한 용이하게 한다 XMT는 기술 방법에 따라 XMT-A 와 XMT-0 두 가지 형태가 있으며, XMT-A 포맷은 VRML에서 발전한 X3D(extensible 3D)를 바탕으로 MPEG-4 시스템의 특징들을 수용하여 구성되고 BIFS와 일대일로 대응된다. 반면에 XMT-0는 멀티미디어 문서를 웹문서로 표현하는 SMIL 2.0 을 그 기반으로 하였기에 MPEG-4 시스템의 특징보다는 컨텐츠를 저작하는 제작자의 초점에 맞추어 개발된 형태이다. XMT를 이용하여 컨텐츠를 저작하기 위해서는 사용자 인터페이스를 통해 입력되는 저작 정보들을 손쉽게 저장하고 조작할 수 있으며, 또한 XMT 파일 형태로 출력하기 위한 API 가 필요하다. 이에, 본 논문에서는 XMT 형태의 중간 자료형으로의 저장 및 조작을 위하여 XML 에서 표준 인터페이스로 사용하고 있는 DOM(Document Object Model)을 기반으로 하여 XMT 문법에 적합하게 API를 정의하였으며, 또한, XMT 파일을 생성하기 위한 API를 구현하였다. 본 논문에서 제공된 API는 객체기반 제작/편집 도구에 응용되어 다양한 멀티미디어 컨텐츠 제작에 사용되었다.

• Journal of Korean Society of Transportation
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• v.30 no.4
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• pp.33-42
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• 2012

Recent development and penetrating expansion in ICT(Information and Communication Technology) has brought considerable improvements in transportation services. However, there is a controversial debate whether transportation and communications behave as substitutes or as complements to one another. On this subject, recent studies considered those two industries as services, but transportation and communications are broadly put for intermediary goods into other industries. Hence, it is essential to examine this issue from understanding their relationships to each other with respect to manufacturing and services. In this study, input-output tables of benchmark years from 1980 to 2005 have been analysed to explore the relationships between transportation and communications using Spearman's correlation analysis. The results show that both industries had complementary roles over the period, but, to some extent, changed into substitution roles in some categories.