• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.432-432
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• 2021

우리나라는 대부분의 에너지 공급을 해외에 의존하고 있는 실정이다. 산업통상자원부와 에너지경제연구원에서 발간하는 2018년 에너지통계연보(에너지경제연구원과 산업통상자원부, 2018)에 실린 2010년부터 2017년까지의 에너지수급 균형을 보면 원유, 천연가스, 석탄, 우라늄 등 평균 95.4%의 에너지를 수입하고 있는 실정이다. 수력 및 신재생에너지의 경우 기후변화에 대응하는 수단 그리고 정부의 저탄소에너지 전환 정책으로 인정받아 상대적으로 낮은 에너지 경제성에도 불구하고 꾸준히 보급되고 있다. 우리나라뿐만 아니라 독일, 프랑스, 영국, 중국 그리고 인도와 같은 세계 주요 국가들이 친환경 에너지 정책을 주도함에 따라 향후 신재생에너지의 공급 규모는 크게 확대될 것으로 전망된다. 중력 물 보텍스 마이크로 수력 발전 시스템은 시스템의 상하류부의 수두(hydraulic head) 차에 의해 저류조(basin)에서 발생되는 물의 보텍스 즉 소용돌이(whirlpool)를 이용하여 임펠러(impeller)를 회전시켜 전기에너지를 생산하는 친환경적 재생에너지의 일종이다. 또한, 시스템으로 유입되는 물은 전기에너지 생산을 위한 임펠러를 통과한 후 다시 하천으로 방류되므로 하천 수의 손실 그리고 하천의 물길도 거의 교란 시키지 않는다. 4가구 정도의 연간 가정용 전기 요구량인 12와 15kW 사이의 전기에너지를 생산하기 위해서는 발전시스템의 상류와 하류의 수두차가 단지 1.5에서 1.7m 이하이면 충분한 것으로 알려져 있다. 본 연구에서는 중력 물 보텍스 친환경 마이크로 발전 시스템을 구성하는 저류조(basin)에 대해 최대 발전효율을 발생시키기에 최적인 기하학적 형태를 도출하는 것이며, 이를 위해 저류조의 cone angle에 따른 다양한 저류조 직경 및 물 보텍스 생성을 위한 저류조 형태의 변화, 유입수로와 저류조와의 각도인 notch angle의 변화, 유입부 폭과 유출부 직경, 유입수로의 길이 그리고 유입수로에서의 초기수심과 같은 기하학적 매개변수를 변화시켜 모의를 수행하였다.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.477-484
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• 2013

In order to recover gold from iron-hydroxide in acid mine drainage, a lead-fire assay has been used. Acid mine drainage is generated from mining waste rocks, and iron-hydroxide precipitates from acid mine drainage, which severely contaminates the area surrounding the mine. Iron-hydroxide samples contain on average 520.29 mg/kg of Fe, 4,414.62 mg/kg sulfur, and 16.19 mg/kg Au. In an XRD analysis, quartz and goethite were observed along with the iron-hydroxide. Using a lead-fire assay, the recovery of pure gold was on average 0.174 g/ton from the iron-hydroxide, whereas the gold not recovered in the process was on average 1.37 mg/kg. This unrecovered gold was lost to the glass slag due to the galena and lead formation. The galena and lead in the glass slag was identified through XRD.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.83-97
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• 2018

Tunnels are widely used for special purposes including roads, railways and culvert for power transmission, etc. Its cross-section shape is determined by uses, ground condition, environmental or economic factor. Many papers with respect to behaviours of adjacent ground and existing structure tunnelling-induced have been published by many researchers, but tunnel cross-section have rarely been considered. A collapse of tunnel causes vaster human and property damage than structures on the ground. Thus, it is very important to understand and analyse the relationship between behavoiurs of ground and cross-section type of tunnel. In this study, the behaviour of ground due to tunnel excavation for underground station below the grouped pile supported existing structure was analysed through laboratory model test using a trap-door device. Not only two cross-section types, 2-arch and box, as station for tunnel, but also, offset between tunnel and grouped pile centre (0.1B, 0.25B, 0.4B) are considered as variable of this study. In order to measure underground deformation tunnelling-induced, Close Range Photogrammetry technique was applied with laboratory model test, and results are compared to numerical analysis.

• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.226-238
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• 2007

In this paper, we present a novel fully distributed topology control protocol that can construct the multiple-ring topology of Minimal Connected Dominating Set (MCDS) as the transport backbone for mobile ad hoc networks. It makes a topology from the minimal nodes that are chosen from all the nodes, and the constructed topology is comprised of the minimal physical links while preserving connectivity. This topology reduces the interference. The all nodes work as the nodes of the distributed parallel Boltzmann machine, of which the objective function is consisted of two Boltzmann factors: the link degree and the connection domination degree. To define these Boltzmann factors, we extend the Connected Dominating Set into a fuzzy set, and also define the fuzzy set of nodes by which the multiple-ring topology can be constructed. To construct the transport backbone of the mobile ad hoc network, the proposed protocol chooses the nodes that are the strong members of these two fuzzy sets as the clusterheads. We also ran simulations to provide the quantitative comparison against the related works in terms of the packet loss rate and the energy consumption rate. As a result, we show that the network that is constructed by the proposed protocol has far better than the other ones with respect to the packet loss rate and the energy consumption rate.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.503-507
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• 2007

In this paper, the ultra-widebend, microstrip patch antenna with the bandwidth of 3 GHz was implemented for ultra-wideband(UWB) wireless communication applications. In order to cover the very wide bandwidth of 3 GHz, a multi-resonance antenna was designed, each resonance frequency was separated into five frequency bend, 7.5, 8.1, 8.7, 9.3, and 9.9GHz with the interval of 600MHz BW. And for wideband characteristics of each antenna, U-slot antennas were designed at each center frequency. Designed five U-slot antennas were connected in series for multi-resonance of 3GHz BW and wideband matching was also designed for impedance matching transmission line calculated. The relative dielectric constant, the height, the loss tangent of the PCB substrate were ${\epsilon}_r=4.8,\;h=0.6$ and loss tangent=0.0009 respectively. The implemented antenna's radiation patterns and gain were directivity characteristics and $1.46{\sim}4.08dBi$ at the five separated center frequency.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.466-474
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• 2007

Asymmetric networks that the downlink bandwidth is larger than the uplink bandwidth may cause the degradation of the TCP performance due to the uplink congestion. In order to solve this problem, this paper designs and implements the Dynamic Segment Size Control mechanism which offers a suitable segment size for current networks. The proposed mechanism does not require any changes in customer premises but suppress the number of ACKs using segment reassembly technique to avoid the uplink congestion. The gateway which adapted the Dynamic Segment Size Control mechanism, detects the uplink congestion condition and dynamically measures the bandwidth asymmetric ratio and the packet loss ratio. The gateway reassembles some of segments received from the server into a large segment and transmits it to the client. This reduces the number of corresponding ACKs. In this mechanism, the SACK option is used when occurs the bit error during the transmission. Based on the simulation in the GEO satellite network environment, we analyzed the performance of the Dynamic Segment Size Control mechanism.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.3
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• pp.98-107
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• 2007

For high-dimensional pattern recognition, such as face classification, the small number of training samples leads to the Small Sample Size problem when the number of pattern samples is smaller than the number of dimensionality. Recently, various LDA-extensions have been developed, including LDA, PCA+LDA, and Direct-LDA, to address the problem. This paper proposes a method of improving the classification efficiency by increasing the number of (sub)-classes through pre-clustering a training set prior to the execution of Direct-LDA. In LDA (or Direct-LDA), since the number of classes of the training set puts a limit to the dimensionality to be reduced, it is increased to the number of sub-classes that is obtained through clustering so that the classification performance of LDA-extensions can be improved. In other words, the eigen space of the training set consists of the range space and the null space, and the dimensionality of the range space increases as the number of classes increases. Therefore, when constructing the transformation matrix, through minimizing the null space, the loss of discriminatve information resulted from this space can be minimized. Experimental results for the artificial data of X-OR samples as well as the bench mark face databases of AT&T and Yale demonstrate that the classification efficiency of the proposed method could be improved.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1A
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• pp.26-34
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• 2002

Mobile telecommunication systems such as IS-95 and IMT-2000 employ frame based communication using frames up to 20 msec in length and the receiving end has to store the whole frome before it is being processed. The size of the frame buffer ofter dominates those of the processing unit such as soft decision Viterbi decoder. The frame buffer for IMT-2000, for example, has to be increased 80 times as large as that of IS-95. One of the parameters deciding the number of bits in a frame will be obviously the number of bits in soft quantization. Start after striking space key 2 times. This paper has studied a new aspect of offset and quantization step size on BER performance and proposes a new 3-bit soft quantization algorithm which shows similar performance as that of 4-bit soft decision Viterbi receiver. The optimal offset values and step sizes for the other practical quantization levels ---16, 8, 4, 2--- have also been found. In addition, a new optimal symbol metric table has been devised which takes the accumulation value of various repeated signals and produces a rescaled 3-bit valu.tart after striking space key 2 times.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.4
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• pp.61-70
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• 2008

This paper designed the antenna for collecting and servicing the traffic information that apply to freeway Traffic Management System, as using DSRC (Dedicated Short Range Communication). Active DSRC is the technology that is using 5.8GHz Radio Frequency to a mean Sequency and there are a lot of the case occurring a physical electric wave shadowing because of the traveling straight of a electric wave. In such inferior communication environment, it constructed the stabilized communication link that can do collecting and servicing the correct traffic information and designed the beam pattern considering the establishment position of the antenna that can apply to various road environments and a communication area. By considering the communication link environment, this paper designed and manufacture the mean frequency of 5.8GHz, the input loss of -17dB in 75MHz bandwidth, the Axial ratio of 1.5:1, and $2{\times}4$ array microstrip antenna which beam pattern have the characteristic of $55^{\circ}$ horizontal half power beam width and $26^{\circ}$elevation half power beam width and the minimum establishment height of the antenna was designed as 14m for avoiding electric wave shadowing on a physical condition between vehicles

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.375-375
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• 2015

최근 도시화에 따른 도로구역의 증가는 도심지의 불투수면적의 확대 및 도로의 수로화를 야기하여 집중호우 발생 시 노면 및 저지대의 침수를 가중시키고 있으며, 이로 인한 인명피해 및 재산 피해는 점차 증가하는 추세이다. 이에 기후변화에 따른 강우량의 변화 및 국지성 집중호우 등을 고려하고 도심지 침수 방지 및 방재성능 강화를 위하여 과거에 간선 10년, 지선 5년에서 간선 30년, 지선 10년으로 관거의 설계빈도가 상향조정 되었다. 도심지의 도로 및 유역 유출량의 배수에 상당한 영향을 미치는 빗물받이 및 빗물받이 유입구는 도심지의 방재성능강화 목적에 맞는 설계가 이루어져야 하나 현재 국내의 빗물받이 설치기준은 하수도시설기준(2009, 환경부)에서 '빗물받이 크기별, 도로 차선별 적정 빗물받이 설치간격' 으로 설계빈도 5년을 반영하여 제시된 설치기준이므로 이에 대한 수정 및 개정이 필요한 실정이다. 이에 본 연구에서는 관거시설의 설계빈도 상향을 고려한 도로 빗물받이의 유입량 산정을 위해 빗물받이 유입구 크기별 유입량을 도로의 차선, 종경사, 측구 횡경사 및 설계빈도의 변화를 고려하여 도로에서의 유출량을 산정하였으며, Froude 상사법칙을 이용하여 수리실험모형을 제작하여 실험을 실시하였다. 빗물받이 제원은 현재 대부분의 국도에 설치되는 크기인 $40{\times}50cm$, $40{\times}100cm$ 및 $40{\times}150cm$를 축소 제작하였다. 측구의 유량은 도로의 차선(2~4차선), 경사(도로 종경사 2~10%, 측구 횡경사 2~10%) 및 설계빈도(최대 30년)을 고려하였다. 실험 결과 측구의 횡경사가 커질수록 빗물받이로 유입되는 유량은 증가하였으며, 빗물받이 유입부의 길이가 증가함에 따라 유입부 측면부를 통한 횡유입량을 증가시켜 빗물받이 유입부의 차집율을 증가시켰다. 또한, 도로의 조건 변화 및 유입량의 변화에 따라서 흐름폭이 감소할수록 차집율이 증가하였다. 수리실험결과를 토대로 도로의 조건변화(차선, 도로 종경사, 측구 횡경사) 및 설계빈도 변화를 고려한 빗물받이의 차집율을 제시하였고 이를 회귀분석 하여 빗물받이 유입구 크기별 유입량 산정식을 도출하였다. 이는 설계빈도 상향에 따른 국내 빗물받이 유입부의 설계 기준 제시에 기초자료로 활용이 가능할 것으로 판단된다.