• Water for future
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• v.26 no.1
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• pp.93-101
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• 1993

Because of the Keumkangsan-Dam and the Peace-Dam constructed in recent years, it is expected that the peak flood discharge and the peak flood stage at the Hwachun-Dam site have been changed. In this study, two methods were used to simulate and compare the effects of the upstream dam construction on the change of the discharge and the stage. One is the storage function method widely used for the hydrological routing in this country. The other is the DWOPER (Dynamic Wave Operational Model) package developed by the U.S. NWS for the hydraulic routing. Flood routing simulations have been performed on four different scenarios:1) Before the construction of the Keumkangsan-Dam and the peace-Dam, 2) The exclusion of the Keumkangsan-Dam watershed (before the construction of the Peace-Dam), 3) The exclusion of the Keumkangsan-Dam watershed (after the construction of the Peace-Dam), 4) The exclusion of the Peace-Dam watershed. The results of the four test cases from the two methods show that the peak flood discharge and the peak flood stage at the Hwachun-Dam site are reduced due to the construction of the Peace-Dam. From these findings, it is suggested that the operational criteria for the optimal dam-operation of the hwachun-Dam need to be modified.

• Computers and Concrete
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• v.10 no.2
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• pp.135-147
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• 2012

At mesoscale, concrete is considered as a three-phase composite material consisting of the aggregate particles, the cement matrix and the interfacial transition zone (ITZ). The reconstruction of the internal structures for concrete composites requires the identification of the boundary of the aggregate particles and the cement matrix using digital imaging technology followed by post-processing through MATLAB. A parameter study covers the subsection transformation, median filter, and open and close operation of the digital image sample to obtain the optimal parameter for performing the image processing technology. The subsection transformation is performed using a grey histogram of the digital image samples with a threshold value of [120, 210] followed by median filtering with a $16{\times}16$ square module based on the dimensions of the aggregate particles and their internal impurity. We then select a "disk" tectonic structure with a specific radius, which performs open and close operations on the images. The edges of the aggregate particles (similar to the original digital images) are obtained using the canny edge detection method. The finite element model at mesoscale can be established using the proposed image processing technology. The location of the crack determined through the numerical method is identical to the experimental result, and the load-displacement curve determined through the numerical method is in close agreement with the experimental results. Comparisons of the numerical and experimental results show that the proposed image processing technology is highly effective in reconstructing the internal structures of concrete composites.

• Journal of the military operations research society of Korea
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• v.32 no.2
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• pp.1-20
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• 2006

In modern marketing environment, we are more interested in logistics as industrial structure is complicated and globalized. Most companies focus on reducing the cost price. So a lot of companies study on cost estimation logistics. However, it Is very difficult to estimate the cost of logistics. Thus they mainly use linear method such as the simple distance of transportation. This study defines the cost of logistics, structure & network of military logistics and proposes the costing estimation model in the logistics. We apply to battle shoes which are the main clothing in the military. In the result, we found some differences on the rate of cost structure between military and civil companies. This study can be used directly to the decision making for optimal military logistics alternatives and contribute to the efficient operation of military budget.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.627-630
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• 2009

Ejector system can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an configuration and operating conditions for an ejector in the condition of sonic and subsonic. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Numerical simulation was adopted for an optimal geometry design and satisfying the required performance. Also, some ejectors with a various of nozzle throat and mixing chamber diameter were manufactured precisely and tested for the comparison with the calculation results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.3
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• pp.13-18
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• 2011

Sphere Decoding (SD) is a decoding technique able to achieve the Maximum Likelihood (ML) performance in fading environments; nevertheless, the main disadvantage of this technique is its high complexity, especially in poor channel conditions. In this paper, we present an adaptive hybrid algorithm which reduces the conventional Sphere Decoder's complexity and keeps the ML performance. The system called Adaptive OSIC-SD modifies its operation based on Signal to Noise Ratio (SNR) information and achieves an optimal performance in terms of Bit Error Rate (BER) and complexity. Through simulations, we probe that the proposed system maintains almost the same bit error rate performance of the conventional SD, and exhibits a lower, quasi-constant complexity.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.173-181
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• 2014

In this paper, the algorithm that can automatically segment the lung, the airway and the pulmonary vessels in a chest CT was proposed. The proposed method is progressed in three steps. In the first step, the lung and the airway are segmented by the region growing law through the optimal threshold and three-dimensional labeling. In the second, from the start point to the first carina of the airway is segmented by the deduction operation, and the next airway of the bifurcations are segmented by applying a variable threshold technique. In the third step, the left/right lungs are divided by the restoration process for the lung, and the outside of lungs for abnormal is checked by applying the advanced rolling ball algorithm, and if abnormal is found, that part is removed, and it is restored to the normal lungs by connecting the outside of the lung in the form of second-order polynomial. Finally, pulmonary vessels are segmented by applying the three-dimensional connected component labeling method and three-dimensional region growing method. As the results of simulation, it could be confirmed that the pulmonary vascular is accurately divided without loss of tissue around lung.

• Journal of IKEEE
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• v.21 no.2
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• pp.123-129
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• 2017

Proton Exchange Membrane Fuel Cell (FEMFC) is a strong candidate for future automobile and power generation because of its high power density, low emission and low operation temperature. The major concerns of the gas diffusion layer (GDL) inside a FEMFC is water management. The GDL is typically comprised of carbon for electrical conductivity and PTFE for Hydrophobicity. In this simulation, GDL flooding was investigated using a simplified approach method of an established equation models(Fick' Law, Darcy, Law, Stefan-Maxwell diffusion). The performance of GDL was shown using result of the inner heat, water density and oxygen density of the cell using model equations. The catalyst layer mode in FEMFC showed results of effectiveness factor, Butler-volmer and hydrogen flux density. These results are interesting because the influence of several factors has been shown and the information will be helpful for fuel cell design.

• Journal of Korean Foot and Ankle Society
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• v.24 no.1
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• pp.19-24
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• 2020

Purpose: Anterolateral minimally invasive plate osteosynthesis (MIPO) was performed to treat patients with distal tibial fractures associated with open fractures or extensive soft tissue injuries, which is limited medial MIPO. The treatment results of the anterolateral MIPO technique were evaluated and analyzed. Materials and Methods: Seventeen patients with distal tibial fractures associated with an open fracture or large bullae formation on the distal tibia medial side were treated with anterolateral MIPO using anterolateral locking plates. Within 24 hours of visiting the emergency room, external fixation was applied, and the medial side wound was managed. After damage control, the anterolateral locking plate was applied using an anterolateral MIPO technique. The union time, nonunion, or malunion were evaluated with regular postoperative radiographs. The ankle range of motion, operative time, blood loss, Iowa score, and wound complications were investigated. Results: Radiological evidence of bony union was obtained in all cases. The mean time to union was 16.7 weeks (12~25 weeks). The mean operation time was 44.0 minutes. Regarding the ankle range of motion, the mean dorsiflexion was 15°, and the mean plantarflexion was 35°. Satisfactory results were obtained in 15 out of 17 cases; five results were classified as excellent, four were good, and six were fair. The mean blood loss was 125.2 mL. Two complications were recorded. Conclusion: In distal tibial fractures with severe medial soft tissue damage caused by high-energy trauma, the staged anterolateral MIPO technique using anterolateral locking plates is a useful alternative treatment to achieving optimal wound care, rapid union with biological fixation, and intra-articular reduction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.632-635
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• 2015

Proposal algorithm in this thesis introduced cells, units of router group, for distributed processing of previous genetic algorithm. This thesis presented ways to reduce search delay time of overall network through cell-based genetic algorithm. As a result of performance analysis comparing with existing genetic algorithm through experiments, the proposal algorithm was found superior in terms of costs and delay time. Furthermore, time for routing an alternative path was reduced in proposal algorithm, in case that a network was damaged in existing optimal path algorithm, Dijkstra algorithm, and the proposal algorithm was designed to route an alternative path faster than Dijkstra algorithm, as it has a 2nd shortest path in cells of the damaged network. The study showed that the proposal algorithm can support routing of alternative path, if Dijkstra algorithm is damaged in a network.

• Convergence Security Journal
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• v.20 no.2
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• pp.123-135
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• 2020

Since AlphaGo's Match in 2016, there has been a growing calls for artificial intelligence applications in various industries, and research related to it has been actively conducted. The same is true in the military field, and since there has been no weapon system with artificial intelligence so far, effort to implement it are posing a challenge. Meanwhile, AlphaGo Zero, which beat AlphaGo, showed that artificial intelligence's self-training data-based approach can lead to better results than the knowledge-based approach by humans. Taking this point into consideration, this paper proposes to apply Reinforcement Learning, which is the basis of AlphaGo Zero, to the Shipboard Combat System or Combat Management System. This is how an artificial intelligence application to the Shipboard Combat System or Combat Management System that allows the optimal tactical assist with a constant win rate to be recommended to the user, that is, the commanding officer and operation personnel. To this end, the definition of the combat performance of the system, the design plan for the Shipboard Combat System, the mapping with the real system, and the training system are presented to smoothly apply the current operations.