• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.855-860
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• 2006

In the environment where multiple AGVs(Automated Guided Vehicles) operate concurrently in limited space, collisions, deadlocks, and livelocks which have negative effect on the productivity of AGVs occure more frequently. The accelerated motion of an AGV is also one of the factors that make the AGV routing more difficult because the accelerated motion makes it difficult to estimate the vehicle's exact travel time. In this study, we propose methods of avoiding collisions, deadlocks, and livelocks using OAR(Occupancy Area Reservation) table, and selecting best route by estimating the travel time of an AGV in accelerated motion. A set of time-driven simulation works validated the effectiveness of the proposed methods.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.8
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• pp.67-78
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• 2009

Radiation characteristics of microstrip patch antennas integrated with mushroom-like EBG structures in all directions and length direction on a substrate with the relative dielectric constant of 10 are systematically analyzed. As the substrate thickness increases, the effect of the surface wave on the input impedance and radiation pattern of a patch antenna increases. The effect of EBG structures on the input impedance of a patch antenna is negligible when the distances between EBG structures and the center of a patch antenna are 0.4 ${\gamma}_0$, 0.2 ${\gamma}_0$ and 0.1 ${\gamma}_0$ for the substrate thickness of 3.2 mm, 1.6 mm and 0.8 mm, respectively. The forward radiation is improved due to the suppression of surface wave when the periods of EBG structures integrated are larger than 2, 2, 3 periods for the substrate thickness of 3.2 mm, 1.6 mm and 0.8 mm, respectively. The effects of EBG structures on the radiation characteristics of a patch antenna integrated with EBG structures in all directions and length direction are similar.

• JOURNAL OF ELECTRICAL WORLD
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• s.286
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• pp.64-69
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• 2000

20세기에 있어서의 비약하는 산업계의 주축으로서 철강시장은 급속히 확대되었고 그와 더불어 신기술의 개발과 도입에서도 선도적 역할을 다하여 왔다. 특히 이 4반세기는 반도체기술의 진보와 함께 컴퓨터, 플랜트 컨트롤러, 드라이브 시스템 등 전기제품은 비약적인 진화를 이루어 왔다. 현재는 중국$\cdot$아시아$\cdot$남미를 중심으로 철강제품의 수요가 증가하여 설비투자도 확대되고 있다. 그러나 북미$\cdot$유럽$\cdot$일본에서는 생산능력과 수요와의 사이에 수급공백이 있어 이전과 같은 시장만큼의 신장은 기대할 수 없는 실정이다. 이와 같은 상황하에서 철강유저의 투자목적을 합리화$\cdot$성력화$\cdot$제품품질의 향상에 두고 있어, 미쓰비시전기는 ''경쟁력 있는 제품을 만들기와 총투자코스트의 최소화''를 서포트하는 제철플랜트용 전기제품의 제공을 지향하여, 그림에 표시하는 것과 같은 4개의 어프로치로 이에 대응하고 있다. 고품질화와 자동화에 대하여는 종래의 품질제어를 능가하는 초안정화 시스템의 적용, 프로세스의 이상 검지와 자동복구에 의한 완전 노터치 오퍼레이션의 실현, 인텔리전트 센서에 의한 프로세스의 가시화로 오퍼레이터가 최종판단을 용이하고 정확하게 할 수 있는 환경을 제공한다. 고효율화$\cdot$에너지 사용합리화에 대하여는 고역률 전원을 추구하여 고효율 드라이브장치와 모터를 제공한다. 글로벌 스탠더드화에의 대응으로서는 네트워크의 오픈화에 의한 멀티벤더 환경, 범용 하드웨어에 의한 오픈 HMI(Human Machine Interface)을 제공하고 있다. 플랜트의 신속한 가동과 리모트 메인터넌스 환경을 실현하기 위하여 플랜트 시뮬레이션 시험의 실시로 공장출하 품질의 향상을 도모한다. 또한 연구센터로부터의 원격감시와 트러블해석 서포트를 쉽게 할 수가 있다. 나아가 최근에는 급격한 기세로 신장되어 온 멀티미디어 기술, 인터넷 기술, 인트라넷 기술, 모바일단말, 화상압축기술 등에 의하여 원격집중감시, 현장과 중앙 쌍방향 협조보수작업, 버추얼 리얼리티 응용시스템이 현실화 되고있는 실정이다. 이들 IT(Information Technology)솔류션은 금후의 제철플랜트의 시스템을 크게 바꾸어 나가는 것은 물론 사업 경쟁력 강화의 키 테크놀로지가 될 것이다. 앞으로 미쓰비시전기는 제철플랜트에 대하여 유저니즈를 IT 솔루션으로 전개, 제공해 나가고자 한다.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.20-28
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• 2012

DVC(Distributed Video Coding) technique is a new paradigm, which is based on the Slepian-Wolf and Wyner-Ziv theorems. DVC offers not only flexible partitioning of the complexity between the encoder and decoder, but also robustness to channel errors due to intrinsic joint source-channel coding. Many conventional research works have been focused on the light video encoder and its rate-distortion performance improvement. However, in this paper, we propose a new DVC codec which is effectively applicable for error-prone environment. The proposed method adopts a quantiser without dead-zone and symmetric Gray code around zero value. Through computer simulations, the proposed method is evaluated by the bit errors position as well as the number of burst bit errors. Additionally, it is shown that the maximum and minimum transmission rate for the given application can be linearly determined by the number of bit errors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1599-1608
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• 2014

This study is to suggest specialty contractors with countermeasures to construction orders falling off, one of the construction business indicators for the construction industry, by analyzing the impact of dwindling construction orders to business performance indicators of specialty contractors as well as identifying inter-relationships between those performance indicators. For specialty contractors of civil construction, it is analyzed that their current ratio is significantly affecting obtention of construction orders, which in turn greatly affecting the ratio of owner's equity. It seems that the amount of construction orders has a direct relationship with the corporate stability. Therefore, this type of specialty contractors are determined to be able to obtain more orders for construction by improving current ratio.

• Journal of the Korean Society for Library and Information Science
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• v.48 no.3
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• pp.137-168
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• 2014

This study proposed to seek the future development direction of policy information service in Korea by identifying users' needs for policy information and analyzing policy information users' behavior. For this purpose, we analyzed policy information users' needs and behavior through survey and interview methods, and the results are as follows. First, the most common purpose of policy information use was figuring out policy trends, and the Internet was the most common search method used in investigating policy information. Second, electronic resources showed a high rate of use, but the domestic material utilization ratio was higher, and the U.S. resources usage of overseas data was the highest. Third, users most often used materials produced within the last 2-5 years, and Web DB (journals, academic articles, etc.) and reports were the most used material types. Fourth, in the survey of opinion about methods for improving policy information utilization efficiency, cooperation between government agencies' libraries, cooperation between agencies producing the policy information resources, and the overall national collection of policy information were rated the highest.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3238-3246
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• 2013

The progress of Information Technology enables people can communicate each others using the Internet. As a smartphone proliferates, many free mobile VoIP(Voice over IP) application are developed and accepted by smartphone users. In this study we investigate the factors affecting the acceptance of mobile VoIP applications and the structural relationship among these factors. We review the related works and extract the related factors and build a research model describing the causal relationship among these factors. We conduct an empirical study - a survey and statistical analysis - to verify the research model. EFA(Exploratory Factor Analysis) is applied for variables in the survey and SEM(Structural Equation Model) is used to reveal the structural relationship among the factors. We can find that two factors - usefulness of mobile VoIP and social influence - positively affect usage intention and actual use. These findings imply that it is required to emphasize the benefits of mobile VoIP use and add S/W functionalities enhancing social influence.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.4975-4983
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• 2012

Commercial and Art movies have different characteristics even when they belong to the same 'movie' category. This study investigated the differential effects of reviewer professionalism and expectation about a movie on the intention to watch the movie. Based on the survey on young potential movie goers, we found that movie types indeed have significant effects. Specifically, in the case of art movie, people had high level of intention to watch when they were exposed to professional reviews. We found that utilitarian expectation mediates between reviewer professionalism and intention to watch for art movie. On the other hand, in the case of commercial movie, people had high level of intention to watch when they were exposed to amateur reviewers. We found that hedonic expectation mediates between reviewer professionalism and intention to watch for art movie. In result, this study contributes to our knowledge to movie industry through showing that reviewer professionalism have different impacts on commercial and art movies.

• Fire Science and Engineering
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• v.33 no.6
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• pp.152-158
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• 2019

This study examined the socio-economic and clinical characteristics associated with the use of ambulance services among pregnant, childbearing, and postpartum women based on data from the 2008-2016 Korea Health Panel. The analysis revealed that among the pregnant, childbearing, and postpartum women, the proportion using all ambulance services was 18.9% whereas 12.0% used private and 119 ambulances. Moreover, among those using ambulance services, delivery was the most common reason (38.7%) followed by complications of labor and delivery (20.0%) and pregnancy with abortive outcome (17.3%). There were statistically significant differences between the users and non-users of ambulance services in terms of the average annual household income, emergency arrival time, and delayed arrival at the emergency room. As childbirth becomes more complicated due to low fertility and elderly mothers, the expansion and improvement of ambulance services as a social safety net for pregnant, childbearing, and postpartum women will become increasingly important.

• Spatial Information Research
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• v.13 no.3 s.34
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• pp.239-252
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• 2005

The major reason that spatial data warehousing has attracted a great deal of attention in business GIS in recent years is due to the wide availability of huge amount of spatial data and the imminent need for fuming such data into useful geographic information. Therefore, this research has been focused on designing and implementing the pilot tested system for spatial decision making. The purpose of the system is to predict targeted marketing area by discriminating the customers by using both transaction quantity and the number of customer using credit card in department store. Moreover, the pilot tested system of this research provides OLAP tools for interactive analysis of multidimensional data of geographically various granularities, which facilitate effective spatial data mining. focused on the analysis methodology, the case study is aiming to use GIS and clustering for knowledge discovery. Especially, the importance of this study is in the use of snowflake schema model capabilities for GIS framework.