• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.8
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• pp.307-317
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• 2003

We analyze the performance of MC-CDMA and MC-DS/CDMA system on quasi-synchronized moble satellite return link. Quasi-synchronization is considered that chip offset between terminals is within a few chips. In 10-3 BER, performance of MC-DS/CDMA system with walsh code is 0.3dB better than that of MC-CDMA system when the number of user is 5 from -0.5 $T_{c}$ to 0.5 $T_{c}$ quasi-synchronization of MC-DS/CDMA system and from -5/64 $T_{c}$ $^{MC}$ to 5/64 $T_{c}$ $^{MC}$ quasi-synchronization of MC-CDMA system. MC-DS/CDMA system with walsh code is over 0.2dB better than that of MC-DS/CDMA system with extended m code and gold code. MC-CDMA system with walsh code is over 1.2dB better than that of MC-CDMA system with gold code when the number of user is 5 and lower than from -5/32 $T_{c}$ $^{MC}$ to 5/32 $T_{c}$ $^{MC}$ quasi-synchronization.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.4
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• pp.136-141
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• 2011

In this paper, we propose an approach to improve the data detection performance of the acoustic data transmission system based on the modulated complex lapped transform (MCLT). We first present an effective analysis of the features and the detection method of data in the acoustic data transmission system. And then feature vectors which are applied to the Gaussian mixture model (GMM) are selected from relevant parameters of the previous system for the efficient data detection. For the purpose of evaluating the performance of the proposed algorithm, Bit error rate (BER) of the received data was measured at different environments (music genres (rock, pop, classic, jazz) and different distances (1m∼5m) from the loudspeaker to the microphone in a office room) and yields better results compared with the conventional scheme of the acoustic data transmission system based on the MCLT.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.69-75
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• 2004

In the paper, system is combined multiband system with DS-UWB techniques with properties including low peak-to-average power ratio, robustness to multiuser interference and excellent security. Because each sub-band is not satisfied with coherence bandwidth, rake receiver in each sub-band is applied to the Proposed system receiver. Output of rake receiver is combined by using Maximal Ratio combining technology. In this paper we mathematically analyse the BER of the DS-UWB system with singleband and multiband systems in the narrow interference channel condition and multi user interference channel condition, the simulation results show that proposed scheme is getting robuster with increasing of the number of subbands.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.340-344
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• 2008

최근의 급속한 도시화로 인한 불투수면적의 증가는 첨두유량의 증가, 홍수도달시간의 단축을 야기해 도시유역의 홍수 피해를 증가시키고 있다. 특히 하천 홍수위 상승에 의한 외수피해와 순간적인 집중호우에 의해 도로 노면수의 배수불량에서 기인하는 내수피해가 겹치는 경우 도시유역의 홍수피해는 더욱 가중된다. 이러한 도시홍수의 피해를 방지하기 위해서는 구조적 또는 비구조적인 대책수립이 필요하다. 구조적 대책의 경우 효과적이나 예산과 공기 등의 문제가 있으며, 중추적인 해결책이 되지 않으므로 도시홍수예보 시스템의 개발이 필요하다. 일반적으로 홍수예보에는 유출해석모형이 활용되고 있다. 유출해석모형 중 SWMM 모형은 맨홀 및 우수관망의 고려가 가능하여 하천과 우수관로가 연계된 도시 유출특성의 모의가 가능하여 도시홍수예보에 적합한 모형이다. 그러나 SWMM은 소배수유역의 분할 및 계산시간의 제약으로 대체적으로 유역면적이 $100km^2$ 내에 적용되는 한계를 가지고 있다. 따라서 본류 및 지류하천과 우수관로가 연계되는 $100km^2$ 이상인 도시유역의 홍수예보를 위해서는 우수관망 해석 및 하천흐름해석의 연계가 필요하다. 본 연구에서는 중규모 유역의 도시홍수예보를 위해 SWMM과 HEC-RAS 모형을 연계하는 방안을 제시하였다. 중랑천 유역을 대상으로 SWMM 모형을 이용하여 소유역의 지표 및 관망유출과 지류하천의 유출 분석을 수행하였고, 중랑천 본 류구간에 대해서는 HEC-RAS 모형을 구축하여 하천의 부정류 해석을 수행하였다. 또한, SWMM으로 계산된 배수구역별 유출해석 결과를 HEC-RAS의 지류유입량으로 활용하여 본류의 지류유입 영향을 고려하도록 하였으며, 원할한 연계를 위해 SWMM과 HEC-RAS를 연계한 시스템을 구축하였다. 결과적으로 SWMM과 HEC-RAS를 연계시스템 통한 모의유량이 관측유량과 유사한 결과를 보였으며, 도시홍수예보를 위한 SWMM과 HEC-RAS의 연계는 복잡한 도시유역의 홍수관리에 활용성이 클 것으로 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.617-623
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• 2020

Urban railroad vehicles carry many passengers and are the core of an urban railroad transportation system. Therefore, the dynamic performance of the vehicle must be ensured. Dynamic behaviors such as the vibration and ride comfort of railway vehicles are affected by the structure of the suspension system. We analyzed the dynamic behavior of a railway vehicle according to the suspension system of an urban railway vehicle, which is mainly operated in Korea. For two types of vehicles with different suspension structures, the vibration of the vehicles on railway tracks was measured, and dynamic behavior characteristics such as vibration, ride, and vibration reduction rate were analyzed. The result of the test shows that the vibration performance of the body is superior to that of B-bogie in the lateral direction and that of A-bogie in the vertical direction. Overall, the ride quality of the A-bogie car is superior to that of B-bogie. When analyzing the vibration attenuation rate of primary suspension system, the vibration attenuation performance of B-bogie with coil spring was superior to that of A-bogie with a conical rubber spring. The secondary suspension system has better vibration attenuation performance for A-bogie with air springs compared to coil springs.

• Korean Journal of Cognitive Science
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• v.4 no.1
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• pp.213-242
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• 1993

During the past decades,several automatic indexing systems have been developed such as single term indexing.phrase indexing and thesaurus basedidndexing systems.Among these systems,single term indexing has been known as superior to others despte its simpicity of extracting meaningful terms.On the other hand,thesaurus based one has been conceived as producing low retrival rate ,mainly because thesauri do not usually have enough index terms.so that much of text data fail to be indexed if they do not match with any of index terms in thesauri.This paper develops a thesaurus based indexing system THINS that yields higher retrieval rate than other systems.by doing syntactic analysis of text data and matching them with index terms in thesauri partially.First,the system analyzes the input text syntactically by using the machine translation suystem MATES/EK and extracts noun phrases.After deleting stop words from noun phrases and stemming the remaining ones.it tries to index these with similar index terms in the thesaurus as much as possible. We conduct an experiment with CACM data set that measures the retrieval effectiveness with CACM data set that measures the retrieval effectuvenss of THINS with single term based one under HYKIS-a thesaurus based information retrieval system.It turns out that THINS yields about 10 percent higher precision than single term based one.while shows 8to9 percent lower recall.This retrieval rate shows that THINS improves much better than privious ones that only yields 25 or 30 percent lower precision than single term based one.We also argue that the relatively lower recall is cause by that CRCS-the thesaurus included in CACM datea set is very incomplete one,having only more than one thousand terms,thus THINS is expected to produce much higher rate if it is associated with currently available large thesaurus.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.722-728
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• 2012

Urban sewer systems has a limitation of capacity of rainwater storage and problem of occurrence of untreated sewage, so adopting a storage facility for sewer flooding prevention and urban non-point pollution reduction has a big attention. The Korea Ministry of Environment has recently introduced a new concept of "multi-functional storage facility", which is crucial not only in preventive stormwater management but also in dealing with combined sewer overflow and sanitary sewer discharge, and also has been promoting its adoption. However, reserving a space for a single large-scale storage facility might be difficult especially in urban areas. Thus, decentralized construction of small- and midium-sized storage facilities and its operation have been introduced as an alternative way. In this paper, we propose a model predictive control scheme for an optimized operation of distributed storage facilities and sewer networks. To this aim, we first describe the mathematical model of each component of networks system which enables us to analyze its detailed dynamic behavior. Second, overflow locations and volumes will be predicted based on the developed network model with data on the external inflow occurred at specific locations of the network. MPC scheme based on the introduced particle swarm optimization technique then produces the optimized the gate setting for sewer network flow control, which minimizes sewer flooding and maximizes the potential storage capacity. Finally, the operational efficacy of the proposed control scheme is demonstrated by simulation study with virtual rainstorm event.

• Pallet News
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• s.51
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• pp.3-10
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• 2008

아시아 물류선진화를 위해서는 현대물류에 있어 가장 효율적 시스템인 유닛로드 시스템(Unit Load System ULS)의 구축과 보급 확산이 시급한 과제다. ULS는 일관파렛트화와 컨테이너화가 그 핵심이며, 일관파렛트화와 컨테이너화는 파렛트와 컨테이너의 표준화로 가능하다. 본 협회는 아시아 유닛로드시스템의 중요성과 구축방안에 대한 한 중 일 아시아 유닛로드시스템 컨퍼런스를 개최하였으며 또한 제5회 한국파렛트컨테이너산업대상 시상식을 갖고 개최하여 산업물류 혁신을 위해 표준파렛트와 컨테이너 생산 및 사용에 있어 가장 모범이 되는 우수한 업체와 이러한 활동에 헌신한 개인 또는 단체를 발굴, 시상하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.187-190
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• 2003

본 논문에서는 다차원 멀티미디어 데이터의 효율적인 스트리밍과, 다차원 입체 시스템 정보의 효율적인 전송을 위한 (역)다중화기를 제안하였다. 제안한 (역)다중화기는 MPEG-2를 TransMux Layer Tool로 이용하였으며 HPEG-4 시스템을 기반으로 설계되었다 다차원 입체 시스템의 구동을 위한 부가 정보는 본 논문에서 제안한 설러 가지 descriptor를 통해, 다차원 멀티미디어 데이터인 다시점 비디오, 스테레오 오디오, 합성 영상과 함께 수신부로 전송된다. 제안한 (역)다중화기는 다차원 입체 시스템에 매우 적합하며, 다른 시스템과의 호환성도 매우 우수하다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.287-289
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• 2006

이 논문은 사용자의 쿼리와 사용자의 행동양식을 바탕으로 상대네트워크를 구축함으로써 개인화된 논문검색 시스템을 모델링한 것이다. 제안하는 시스템은 사용자가 검색한 논문에서 키워드의 빈도수를 분석하여 개인적 상대네트워크를 구축하게 되는데, 이 네트워크는 다운로드, 열기, 삭제 등과 같은 사용자의 행동으로부터 키워드간 가중치를 조정을 함으로써 구축된다. 시스템의 성능평가를 위해 100명의 사용자들을 대상으로 실험한 결과, 기존의 검색엔진을 사용했을 때보다 성능이 우수하여 사용자 만족도가 높게 나타남을 알 수 있었다