• Korea journal of population studies
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• v.33 no.1
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• pp.1-25
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• 2010

This study looks into travel behavior differences by sex, gender role and economic status. Source for analysis in this study is from Time Use Survey conducted by Korea National Statistical Office in 2004. The sample considered of 3,122 women's time diaries and 2,678 men's, whose age range from 20-59. The results of the study show that married women, women with child under age 6 and unemployed women have less travel time quantity, travel during the daytime and use mass transportation than men and single women. However single women and working women, especially working women having high income level, show more similar patterns of travel behavior with men's which are quite unvarying regardless of marital, parental and economic status.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1182-1189
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• 2007

Frequency reuse in a cellular wireless communication environment gives rise to a phenomenon of cochannel interference. This paper introduces a power control strategy for OFDM based communication systems operating in such an environment. Among the existing power control schemes, IWF(iterative waterfilling) is known to exhibit relatively good performance. However, it requires feedback of power level and bit allocation information for each subcarrier from a receiver to its associated transmitter, which can lead to a considerable overhead, especially for the case of employing large number of subcarriers. Motivated by this, we present a simplified power control scheme with reduced overhead feedback, which allocates some nonzero identical power to the subcarriers of which channel conditions are above a certain threshold and zero power to the other ones. Computer simulations show that the proposed strategy produces a good approximation to the performance of the IWF in terms of the transmission power level while it requires less overhead feedback.

• Journal of the Korea Society of Computer and Information
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• v.15 no.11
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• pp.47-56
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• 2010

In navigation, officers receive data about inside and outside of ship from several devices(ex, GPS / AIS / ECDIS / ARPA Radar / etc) in bridge, and use it to recognize and predict safety situations. However, observation work of a officer is still hard for a torrent of data from several devices, and the problem of inconsistent data among the devices. In previous research, we presented the conceptual model of Intelligent Navigation Safety Information System based on information fusion, and showed the example of the conceptual model using CF (Certainty Factor) expert system to solve this problem. The information fusion technology needs various reasoning skills, and CF expert system is not enough to express ambiguous or indefinite factors. In this paper, we propose the concept of an intelligent navigation information fusion using fuzzy expert system to describe the ambiguous factors, and show the validity of applying fuzzy expert system to the Navigation Safety Information System through the design and implementation of the proposed concept.

• Korean Journal of Cognitive Science
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• v.11 no.3_4
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• pp.1-11
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• 2000

This study investigated information acquisition from hypertext and the difference of searching behavior between adults and children. In experiment 1. we compared the amount of information acquisition from the hypertext to that of the printed text. The result showed that the performance in printed text was better than in hypertext. However. the performance of experienced (in the internet) participant showed no difference between the hypertext and the printed text. Experiment 2 compared the information-searching behavior of the adults and children in the hypertext environment. The results showed that adults performed the information-searching faster than children, yet there was no difference in the proportion of correct responses of the two groups. However. children who were more experienced in the internet and produced right answers to the 7th level questions in depth performed better and faster than the adults who were not. These results suggest that the experience in the internet is the most important factor in the searching of the wanted information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.1042-1049
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• 2007

Frequency reuse in a cellular wireless communication environment gives rise to a phenomenon of cochannel interference. This paper introduces a power control strategy for OFDM based communication systems operating in such an environment. Among the existing power control schemes, IWF(iterative waterfilling) is known to exhibit relatively good performance. However, it requires feedback of power level and bit allocation information for each subcarrier from a receiver to its associated transmitter, which can lead to a considerable overhead, especially for the case of employing large number of subcarriers. Motivated by this, we present a simplified power control scheme with reduced overhead feedback, which allocates some nonzero identical power to the subcarriers of which channel conditions are above a certain threshold and zero power to the other ones. Computer simulations show that the proposed strategy produces a good approximation to the performance of the IWF in terms of the transmission power level while it requires less overhead feedback.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.635-642
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• 2008

We propose the Optimum Power Allocation (OPA) scheme for Distributed Antenna Systems(DAS) in the time-varying Rayleigh fading channel. Recently, the OPA schemes which uses the Channel State Information (CSI) including a small scale (fast) fading have been proposed. However, the channel is changing vary fast over time due to small scale fading, therefore Bit Error Rate (BER) increases. Because of this reason, we derive the OPA for minimizing BER in DAS, which only uses a large scale fading to CSI and excepts a small scale fading. The simulation results show that the proposed OPA achieves better BER performance than conventional OPA considering a small scale fading in time-varying Rayleigh fading channel, and also has similar performance in Rayleigh flat-fading environment. The BER performance of proposed OPA which derived in Rayleigh fading channel is similar to minimum BER of Ricean fading channel which has small Line-of-Sight (LOS).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.4
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• pp.36-53
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• 2017

The global intelligent transport systems (ITS) market is experiencing rapid growth, and domestic ITS companies' efforts to extend its business abroad are steadily increasing. However, due to the burden of costs associated with the overseas expansion and the lack of strategy for local market, domestic companies' contracts for global businesses are far short of the technology. Although the government is actively promoting Korean enterprises' participation to overseas business, it has obvious limits due to the lack of its specialized strategy. This study established a customized export model for the countries in which Korean companies want to enter, and developed a strategy to advance into the local market.

• Journal of Korea Water Resources Association
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• v.49 no.12
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• pp.971-980
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• 2016

In general, efficient operation of sediment sluicing is important in economical aspect. In this study, the efficiency of sediment sluicing by various operation at water surface elevation on multi-functional weirs were analyzed using Nays2DH, and we focused on the Dalsung weir at Nakdong river. The results of this study shows that, the same number of flushing channels and water gates were developed due to sediment sluicing, and sediment deposition occurred in upstream region of flushing channels. Also, the sediment sluicing efficiency increased by approximately 4.6% and sedimentation decreased by approximately 4.5% at EL. 14.5 m for operations on water surface elevation exceeding EL. 14.0 m. The mitigation of reservoir sedimentation and extension of maintenance dredging period are possible if the variation of sediment sluicing efficiency in various operation at water surface elevation during flood season are considered.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.4
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• pp.407-413
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• 1999

Maxillary duplication is a kind of proliferative neurocristopathy and considered to arise from bifurcation of neural crest elements soon after migration into mandibular arch. Sometimes this malformation is accompanied with oblique facial cleft. Usually this type of maxillofacial malformation requires multiple surgical intervention and the results are far from ideal. It became more troublesome if it had not been properly corrected on time, because secondary deformities could be developed from growth and development of abnormal tissues. This is a case of a 25-year-old-female patient who showed severe facial asymmetry thought to secondary deformity of maxillary duplication and masticatory disturbance due to multiple supernumerary teeth on posterior part right maxilla. We successully treated these deformities through four times of surgery of bone resection, orthodontic treatment, zygomatic and orbital reconstruction, orthognathic surgery and scar revision... ect. So we reported this rare case with review of literatures.

• Monthly Duck's Village
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• s.92
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• pp.50-59
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• 2011

2008년 급등하였던 국제곡물 가격은 209년 들어 하락하여 2010년 상반기까지 안정세를 보였으나, 기상악화로 인한 구소련 지역의 밀 생산 감소로 러시아가 수출 금지 조치를 취하면서 2010년 7월부터 밀 가격 급등을 시작으로 현재까지 강세를 보이고 있다. 옥수수 국제 가격 상승은 사료비 상승의 주된 요인으로 작용하여 축산 농가의 수익성을 악화시키고, 밀과 대두 국제 가격 상승은 이를 원료로 하는 가공품 가격 상승으로 이어져 소비자들의 부담으로 연계된다. 따라서 본고에서는 2008년의 애그플레이션 경험을 토대로 최근의 국제곡물 가격상승 원인과 2011년 상반기 국내 물가에 미치는 영향을 분석하고, 시사점을 제시하였다. 최근의 국제곡물 가격 상승은 생산 감소, 수요 증가, 곡물 선물 투기 증가에서 기인하고 있다. 2010/11년도 세계 곡물 생산량은 전 세계적인 이상기후로 전년보다 2% 감소하고, 소비량은 2.4% 증가하여 곡물 기말재고율은 전년대비 3.1%p 하락할 것으로 예상된다. 향후 바이오연료 소비는 지속적으로 증가할 전망이며, 이에 따른 세계 곡물 수요 증가는 불가피해 보인다. 곡물 수급이 전년보다 좋지 않은 상황에서 곡물 선물에 대한 투기가 증가하고, 중국과 인도의 육류 소비 증가에 따른 곡물 소비 증가도 국제곡물 가격 상승의 주된 원인으로 작용하고 잇다. 2010년 하반기 국제곡물 가격을 적용하면, 2011년 상반기 국내 물가 상승은 불가피한 것으로 나타났다. 2011년 상반기 국제곡물 가격을 적용하면, 2011년 상반기 국내 물가 상승은 불가피한 것으로 나타났다. 2011년 상반기 배합사료는 2010년 6월 시세보다 11.5%, 제분 부문은 31.3%, 유지 및 식용유는 6.6%, 제당 부문은 30.0%의 물가 상승요인이 있는 것으로 나타났다. 한편 전분 및 당류는 전년 6월대비 10.9%의 물가 상승요인이 있을 것으로 예상된다. 이와 같이 밀, 옥수수, 대두의 대부분을 수입에 의존하는 우리나라는 국제곡물 가격이 상승할 경우 국내물가 상승이 불가피한 실정이며, 국내 생산을 늘린다 하더라도 수요량을 충족하기에는 한계가 있다. 따라서 국제곡물 수급 및 가격을 상시 모니터링하여 향후 국제곡물 가격을 전망하는 관측시스템 개발을 통해 조기경보를 주고, 이에 따른 매뉴얼을 만들어 대응해야 할 것이다. 한편, 정부 차원에서는 세계 곡물 생산량 감소와 수요 증가로 곡물 공급에 차질이 생길 경우 수입선 다변화 등의 빠른 정책적 대응을 위해 주요 곡물 생산국과의 네트워킹을 강화시킬 필요가 있다.