• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.2
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• pp.60-67
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• 2010

In the ubiquitous age, applications of wireless personal area network (WPAN) technology using LEDs are in progress. However, visible light communications (VLC) using the LEDs have weakness which deteriorate performance of communication because of multi-path fading that occurs propagation delay by interior walls or other things in indoor environments. In this paper, orthogonal frequency division multiplexing (OFDM) scheme is adapted to decrease multi-path fading and multi-path dispersion and to provide high speed data transmission. Besides, to reduce information losses caused by optical noise (incandescent lamps, fluorescent lamps, sunbeam etc.) also proposed channel coding using turbo codes. The encoding and decoding of the proposed system is described, and simulation results are analyzed. We can know that performance of proposed system is increased about 4 [dB] through the simulation results. Also, when the system take doppler effect, the system performance worsened.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1411-1418
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• 2015

Currently, the previous studies on the concept, configuration, and system regarding spacial information policies show the little progress. However, these studies only propose the basic structure system in terms of a policy theory, seeking and suggesting the basic concept to establish spacial information policies. In the shift of a new paradigm from a PC-based paradigm that began in the mid-2000s to the current smart society based on mobile devises, such as smart phones, this study thus reviewed the strategic direction of the propulsion to establish the desired future strategy for the spatial technology policy with spatial information system that can influence the future national competitiveness of Korea. The results of this study is expected to be used to analyze a variety of issues and technological changes on geospatial intelligence at the global level and to support the establishment of a road-map for policies and research & development on domestic geospatial information.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.907-914
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• 2015

Currently, the previous studies on the concept, configuration, and system regarding spacial information policies show the little progress. However, these studies only propose the basic structure system in terms of a policy theory, seeking and suggesting the basic concept to establish spacial information policies. In the shift of a new paradigm from a PC-based paradigm that began in the mid-2000s to the current smart society based on mobile devises, such as smart phones, this study thus reviewed the strategic direction of the propulsion to establish the desired future strategy for the spatial technology policy with spatial information system that can influence the future national competitiveness of Korea. The results of this study is expected to be used to analyze a variety of issues and technological changes on geospatial intelligence at the global level and to support the establishment of a road-map for policies and research & development on domestic geospatial information.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.410-416
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• 2013

In this paper, we propose a chaotic correlation delay shift keying(CDSK) using digital retrodirective array antenna (RDA) for improving security and receive performance. Chaotic signals provide improved security due to non-periodic and non-predictable performance of chaotic signals. However, the receive performance of these chaotic signals is degraded due to self-interference and interference signals. Therefore, this paper, we analyze the receive BER performance of chaos communication system which has digital RDA based on CDSK modulation schemes for improving security without receive performance degradation. Simulation results show that the proposed system can get the same receiving performance compared to BPSK modulation schemes when array elements of RDA are 5.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.222-222
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• 2021

도시 내 하천 친수공간은 레저 및 여가를 위한 공간과 더불어 자연경관 및 생태체험 등의 다목적으로 활용되어 지역사회에 있어 중요한 공간으로 활용되고 있다. 과거 4대강 사업으로 국가하천 내 휴식공간을 조성하였다. 그 후 친수지구 중에서 이용도가 저조한 곳을 해제하였으며, 현재 297개의 친수지구를 중점으로 관리하고 있다. 이러한 친수지구를 유지하는데 필요한 보수 비용들을 지자체에서 담당하고 있으나, 상당한 비용이 소요되므로 친수지구 지정 후 운영단계에서 지역 주민들의 특성 및 요구를 정확히 파악할 필요가 있다. 하천 친수공간에 대한 정보구축은 조사원 조사, 유지관리 기관 조사 등 인적 조사 방식을 통한 데이터 수집으로 많은 비용이 필요할 뿐만아니라 DB 갱신 부분에도 한계가 있다. 그러므로 본 연구에서는 RS/GIS를 기반으로 친수시설에 대한 정보맵 작성 방안 연구와 친수시설 뿐만 아니라 유역조사 시 하천공간에서 수행할 수 있는 기술에 대한 연구를 수행하였다. 연구대상지역은 대저생태공원과 삼락생태공원을 대상으로 선정하였다. 해당 지역 항공영상의 정합 및 전처리를 실시한 후 QGIS를 활용하여 LSMS(Large-Scale Mean Shift) 기법으로 시설물 분류를 실시하였다. 공원 내 친수시설 분류를 위해 공간 반경(Spatial radius)를 10 ~ 25까지 변화시키면서 최적 분류 결과를 도출하는 공간 반경을 찾았으며 친수시설 규모와 시설의 특성에 따라 공간 반경을 조절하여 친수시설 분류맵을 작성하였다. 친수지구 내 친수시설 분류맵과 친수지구 내 친수시설 현황 및 친수시설별 코드와, 위치정보(위도, 경도 및 표고), 면적 및 관리현황으로 분류하여 입력 할 수 있도록 하였다. 본 연구에서 구축한 친수시설 자동분류 알고리즘을 통해 전국 단위 통합 하천관리체계 구축 및 친수시설에 대한 정보맵을 작성할 수 있는 기반 마련이 가능할 것이다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.431-436
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• 2008

Recently, the rapid development of GIS technology has made it possible to handle a various data associated with spatially hydrological parameters with their attribute information. Therefore, there has been a shift in focus from lumped runoff models to distributed runoff models, as the latter can consider temporal and spatial variations of discharge. In this research, a distributed rainfall-runoff model based on physical kinematic wave for analysis of surface and river flow was used to simulate temporal and spatial distribution of long-term discharge. The snowfall and melting process model based on Hydro-BEAM was developed, and various hydrological parameters for input data of the model was extracted from basic GIS data such as DEM, land cover and soil map. The developed model was applied for the Shonai River basin(532) in Japan, which has sufficient meteorological and hydrological data, and displayed precise runoff results to be compared to the hydrograph.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.421-430
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• 2004

Clinically, it is almost impossible for a physician to distinguish subtle changes of frequency spectrum by using a stethoscope alone especially in the early stage of thrombus formation. Considering that reliability of mechanical valve is paramount because the failure might end up with patient death, early detection of valve thrombus using noninvasive technique is important. Thus the study was designed to provide a tool for early noninvasive detection of valve thrombus by observing shift of frequency spectrum of acoustic signals with computer aid diagnosis system. A thrombus model was constructed on commercialized mechanical valves using polyurethane or silicon. Polyurethane coating was made on the valve surface, and silicon coating on the sewing ring of the valve. To simulate pannus formation, which is fibrous tissue overgrowth obstructing the valve orifice, the degree of silicone coating on the sewing ring varied from 20％, 40％, 60％ of orifice obstruction. In experiment system, acoustic signals from the valve were measured using microphone and amplifier. The microphone was attached to a coupler to remove environmental noise. Acoustic signals were sampled by an AID converter, frequency spectrum was obtained by the algorithm of spectral analysis. To quantitatively distinguish the frequency peak of the normal valve from that of the thrombosed valves, analysis using a neural network was employed. A return map was applied to evaluate continuous monitoring of valve motion cycle. The in-vivo data also obtained from animals with mechanical valves in circulatory devices as well as patients with mechanical valve replacement for 1 year or longer before. Each spectrum wave showed a primary and secondary peak. The secondary peak showed changes according to the thrombus model. In the mock as well as the animal study, both spectral analysis and 3-layer neural network could differentiate the normal valves from thrombosed valves. In the human study, one of 10 patients showed shift of frequency spectrum, however the presence of valve thrombus was yet to be determined. Conclusively, acoustic signal measurement can be of suggestive as a noninvasive diagnostic tool in early detection of mechanical valve thrombosis.

• International Journal of Oral Biology
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• v.37 no.3
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• pp.137-145
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• 2012

Aggregatibacter actinomycetemcomitans is the most important etiologic agent of aggressive periodontitis and can interact with endothelial cells. Monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) are chemokines, playing important roles in periodontal pathogenesis. In our current study, the effects of A. actinomycetemcomitans on the production of MCP-1 and IL-8 by human umbilical vein endothelial cells (HUVEC) were investigated. A. actinomycetemcomitans strongly induced the gene expression and protein release of both MCP-1 and IL-8 in a dose- and time-dependent manner. Dead A. actinomycetemcomitans cells were as effective as live bacteria in this induction. Treatment of HUVEC with cytochalasin D, an inhibitor of endocytosis, did not affect the mRNA up-regulation of MCP-1 and IL-8 by A. actinomycetemcomitans. However, genistein, an inhibitor of protein tyrosine kinases, substantially inhibited the MCP-1 and IL-8 production by A. actinomycetemcomitans, whereas pharmacological inhibition of each of three members of mitogen-activated protein (MAP) kinase family had little effect. Furthermore, gel shift assays showed that A. actinomycetemcomitans induces a biphasic activation (early at 1-2 h and late at 8-16 h) of nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and an early brief activation (0.5-2 h) of activator protein-1 (AP-1). Activation of canonical NF-${\kappa}B$ pathway ($I{\kappa}B$ kinase activation and $I{\kappa}B-{\alpha}$ degradation) was also demonstrated in these experiments. Although lipopolysaccharide from A. actinomycetemcomitans also induced NF-${\kappa}B$ activation, this activation profile over time differed from that of live A. actinomycetemcomitans. These results suggest that the expression of MCP-1 and IL-8 is potently increased by A. actinomycetemcomitans in endothelial cells, and that the viability of A. actinomycetemcomitans and bacterial internalization are not required for this effect, whereas the activation of protein tyrosine kinase(s), NF-${\kappa}B$, and AP-1 appears to play important roles. The secretion of high levels of MCP-1 and IL-8 resulting from interactions of A. actinomycetemcomitans with endothelial cells may thus contribute to the pathogenesis of aggressive periodontitis.

• Spatial Information Research
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• v.19 no.4
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• pp.11-20
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• 2011

In accordance with low carbon and green growth paradigm, a subway is one of major public transit systems for resolving traffic congestion and decreasing traffic accidents. In addition, as subway networks expand, passengers' travel pattern in the subway network change and consequently affect the urban structure. Generally, new subway route has been planned and developed, mainly considering a travel demand forecast. However, it is desired to conduct an empirical analysis on the forecast model regarding change of travel accessibility and passenger demand pattern according to new subway line. Therefore, in this paper, an alternative method, developed based upon a spatial syntax model, is proposed for evaluating new subway route in terms of passenger's mobility and network accessibility. In a case study, we constructed subway network data, mainly targeting the no 9 subway line opened in 2009. With an axial-map analysis, we calculated spatial characteristics to describe topological movement interface. We then analyzed actual modal shift and change on demand of passengers through the number of subway passenger between subway stations and the number of passenger according to comparative bus line from Smart Card to validate suggested methods. Results show that the proposed method provides quantitative means of visualizing passenger flow in subway route planning and of analyzing the time-space characteristics of network. Also, it is expected that the proposed method can be utilized for predicting a passengers' pattern and its impact on public transportation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.4
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• pp.58-66
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• 2012

Currently many devices reproduce electronic images in the various ways. However, the color that is reproduced in any device is different from the original color due to the differences in the gamut between devices. A recent trend in gamut mapping algorithms is the use of spatial information to compute the color transformation of pixels from the input to the output gamut. However, these techniques share the problem of preserving details, and avoiding halos, and hue shift. In this paper, spatial gamut mapping for preserving the details of the input image is proposed. Our approach improves visibility of detail that is not effectively represented with conventional spatial gamut mapping. In proposed method, initially, we gamut map the input image using gamut clipping and obtain a detail layer for both the input and the gamut mapped images. Next, we calculate the difference between the two detail layers, obtaining the details of the out of gamut region. Finally, we add the details of out of gamut region to the gamut mapped image. Since the resulting image has out of gamut colors, we obtain resulting image of proposed method by using a gamut clipping method. Consequently, the printed output image was more consistent with the corresponding monitor image.