• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1782-1788
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• 2007

This study analyzed ground settlement and ground stress depending on tunnel excavation and the ground reinforcing grouting methods for double line road tunnel through deep weathered zone. Diameter of double line road tunnel was approximately 12m and umbrella arch method and side wall reinforcing grouting were applied. The ring-cut split excavation method and CD-cut excavation method for excavation method were applied. Analysis of failure rate and vertical stress ratio show that the tunnel for which the height of the cover(H) was higher than four times the diameter, it can be considered a deep tunnel. Comparisons of various excavation and ground reinforcement methods were showed that CD-cut method results in lower surface and crown settlement, and lower failure rate than where using Ring-cut split method. In addition the side wall reinforcing grouting resulted in reduction of tunnel displacement and settlement.

• 한국구조물진단유지관리공학회 논문집
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• 제7권2호
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• pp.209-218
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• 2003

The analytical studies included nonlinear finite element analysis of split-tee connection details subjected to axial load and lateral load. A three-dimensional model of the connections between CFT columns and H-beams has been developed. Both initial geometrical imperfections and residual stresses are taken into consideration. A geometrically nonlinear load-displacement analysis of the structure containing the imperfection is then performed, using the Riks method. Analytical results are compared with existing experimental results. Extensive parametric analyses are carried out to investigate the relation of the connections between CFT columns and H-beam to various parameters such as the axial load, column width-thickness ratio, and split-tee thickness.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.518-521
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• 2007

To retrieve Sea Surface Temperature(SST) from NOAA-AVHRR imagery the spilt window atmospheric correction algorithm is generally used. Recently, there have been various new algorithms developed to process these data, namely the variable-coefficient split-window, the R54 transmittance-ratio method, fixed-coefficient nonlinear algorithm, dynamic water vapour (DWV) correction method, Dynamic Water Vapour and Temperature algorithm (DWVT). We used MCSST (Multi-Channel Sea surface temperature) and NLSST(Non linear sea surface temperature) algorithms in this study. The study area is around the Korea sea area (Yellow Sea). We compared and analyzed with various methods by applying each Ocean in-situ data and satellite data. The primary aim of study is to verify and optimize algorithms. Finally, this study proposes an optimized algorithm for SST retrieval.

• Structural Engineering and Mechanics
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• 제70권3호
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• pp.257-267
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• 2019

Expressions for the calculation of ductility index for concrete girders with different ratios of prestressed and classical reinforcement were proposed using load-displacement, load-strain and load-curvature relation. The results of previous experimental static tests of several large-scale concrete girders with different ratio of prestressed and classical reinforcement are briefly presented. Using the proposed expressions, various ductility index of tested girders were calculated and discussed. It was concluded that the ductility of girders decreases approximately linearly by increasing the degree of prestressing. The study presents an expression for the calculation of the average ductility index of classical and prestressed reinforced concrete girders, which are similar to the analysed experimental test girders.

• 수산해양기술연구
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• 제59권2호
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• pp.99-109
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• 2023

In this study, a comparative test operation was conducted through the alternate haul method to examine the selectivity of the four mesh sizes (60 mm, 90 mm, 110 mm, and 130 mm) of the trawl codend. The selectivity was analyzed using the SELECT model considering the fishing efficiency (split parameter) of each fishing gear in the comparative test fishing operation in the trawl and the maximum likelihood method for parameter estimation. A selectivity master curve was estimated for several mesh sizes using the extended-SELECT model. As a result of analyzing the selectivity for silver croaker based on the results of three times hauls for each experimental gear, it was found that the size of the fish caught increased as the size of the mesh size increased. When the selectivity for each mesh size analyzed by the SELECT model considering the split ratio was evaluated based on the size of the AIC value, the estimated split model was superior to the equal split model. Based on the master curve, the 50% selection length value was 2.893, which was estimated to be 136 mm based on the mesh size of 60 mm. In some selectivity models, there was a large deviance between observed and theoretical values due to the non-uniformity of the distribution of fished length classes. As a result, it is considered that appropriate sea trials and selectivity evaluation methods with high reliability should be applied to present trawl fishery resource management methods.

• 한국분무공학회지
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• 제19권3호
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• pp.123-129
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• 2014

A diesel spray overall SMD (Sauter mean diameter) in a spray chamber was simulated with CFD by varying the compression ratio in the spray chamber from 18:1 to 100:1. The gas densities of the spray chambers for the compression ratios of 18:1 and 100:1 were 17.97 and $74.8kg/m^3$, respectively. Standard KIVA-3V code was used for the CFD simulation. Various fuel injection patterns such as single injection, pilot injection and split injection were used for the CFD simulation. Fuel injection pressures for the simulated diesel sprays are 90 and 120 MPa. As the compression ratio increases, the CFD simulated SMD was decreased, which was generally in agreement with previous experimental studies.

• 정보처리학회논문지C
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• 제11C권3호
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• pp.379-386
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• 2004

WAP 2.0 시스템은 인터넷 환경과의 호환성을 고려하여 WAP 포럼에서 새롭게 제안된 무선통신 시스템으로서, WAhP 단말기와 기존 Origin 웹서버 간의 통신을 담당한다. 본 연구의 목적은 1) WAP 포럼에서 제안된 WAP 2.0 프록시를 구축하고 2) 이를 개선하여 유무선 통신 간의 전송 효율을 향상시키는데 있다. 본 연구에서 구축한 개선된 WAP 프록시는 split-TCP 개념을 사용하여 유무선 통신환경을 연결하고 있지만, split-TCP 연결과는 달리, TCP의 end-to-end 의미(semantics)를 유지시키고 상위 프로토클 계층에서의 처리를 되도록 줄여서 오버헤드를 감소시킨다. 또한, SACK(Selective Acknowledgement) 옵션 및 Timestamp 옵션을 지원하여 빠른 재전송을 가능하게 함으로써, 무선통신 경로에서의 TCP의 성능 저하를 줄인다. 본 논문에서 구축한 개선된 WAP 프록시를 Linux 환경에서 구현한 후 성능을 측정한 결과, WAP 포럼에서 제안된 WAP 프록시에 비하여 데이터 전송지연시간과 데이터 전송량이 모두 줄어드는 전송 효율의 향상을 얻었다 특히, 패킷 유실율(packet missing ratio)이 클수록, 데이터 전송량의 감소 효과가 점점 커짐을 알 수 있으며, 이것은 개선된 WAP 프록시로 인한 무선통신 환경에서의 성능 항상 효과가 뚜렷함을 입증한다고 생각된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.443-461
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• 2014

Overlay routing has emerged as a promising approach to improve reliability and efficiency of the Internet. For one-hop overlay source routing, when a given primary path suffers from the link failure or performance degradation, the source can reroute the traffic to the destination via a strategically placed relay node. However, the over-heavy traffic passing through the same relay node may cause frequent package loss and delay jitter, which can degrade the throughput and utilization of the network. To overcome this problem, we propose a Load-Balanced One-hop Overlay Multipath Routing algorithm (LB-OOMR), in which the traffic is first split at the source edge nodes and then transmitted along multiple one-hop overlay paths. In order to determine an optimal split ratio for the traffic, we formulate the problem as a linear programming (LP) formulation, whose goal is to minimize the worse-case network congestion ratio. Since it is difficult to solve this LP problem in practical time, a heuristic algorithm is introduced to select the relay nodes for constructing the disjoint one-hop overlay paths, which greatly reduces the computational complexity of the LP algorithm. Simulations based on a real ISP network and a synthetic Internet topology show that our proposed algorithm can reduce the network congestion ratio dramatically, and achieve high-quality overlay routing service.

• International Journal of Concrete Structures and Materials
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• 제7권3호
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• pp.239-249
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• 2013

In the present scenario to fulfill the demands of sustainable construction, concrete made with multi-blended cement system of OPC and different mineral admixtures, is the judicious choice for the construction industry. Silica fume (SF) and fly ash (FA) are the most commonly used mineral admixtures in ternary blend cement systems. Synergy between the contributions of both on the mechanical properties of the concrete is an important factor. This study reports the effect of replacement of OPC by fly ash (20, 30, 40 and 50 % replacement of OPC) and/or silica fume (7 and 10 %) on the mechanical properties of concrete like compressive strength and split tensile strength, with three different w/b ratio of 0.3, 0.4 and 0.45. The results indicate that, as the total replacement level of OPC in concrete using ternary blend of OPC + FA + SF increases, the strength with respect to control mix increases up to certain replacement level and thereafter decreases. If the cement content of control mixes at each w/b ratio is kept constant, then as w/b ratio decreases, higher percentage of OPC can be replaced with FA + SF to get 28 days strength comparable to the control mix. A new method was proposed to find the efficiency factor of SF and FA individually in ternary blend cement system, based on principle of modified Bolomey's equation for predicting compressive strength of concrete using binary blend cement system. Efficiency factor for SF and FA were always higher in ternary blend cement system than their respective binary blend cement system. Split tensile strength of concrete using binary and ternary cement system were higher than OPC for a given compressive strength level.

• 한국통신학회논문지
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• 제31권1A호
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• pp.23-29
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• 2006

무선 센서네트워크(Sensor Network)에서는 많은 수의 센서 노드를 영구적으로 사용하기 보다는 일회성의 목적으로 사용하기 때문에 센서 네트워크를 구성하는 노드들의 수명을 장시간 유지시키는 것이 매우 중요하다. 이를 위해서 본 논문에서는 무선 센서네트워크의 연결 유지 시간(network lifetime)을 연장시키기 위한 EASR(Energy Aware Source Routing) 프로토콜을 제안한다. 제안하는 EASR 기법은 기존의 EAR(Energy Aware Routing)처럼 다중 경로 중에 확률에 의해 결정되는 단일 경로로만 데이터 트래픽을 전송하여 에너지 소비를 분산시키는 방법을 사용한다. 하지만 제안하는 EASR 기법에서는 기존의 SMR(Split Multipath Routing)에서 사용되는 다중 경로 선정 기법을 개선한 방법으로서 센서 노드들의 에너지 소비를 최소화 하기 위하여 다중 경로간의 overhearing 지수를 정의하고 이를 근거로 overhearing 현상에 의한 에너지 소비를 최소로 하는 다중 경로를 설정하는 기법이다. 제안하는 EASR기법이 무선 센서네트워크 환경에서 노드의 수명을 장시간 유지시키고 합리적인 데이터 전송 지연시간을 갖는다는 것을 시뮬레이션 분석을 통해 확인하였다.