• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.1 s.4
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• pp.153-159
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• 2002

Disasters are the phenomena that we have to prevent the occurrence in order to keep the safety to human lives and properties, and if occurred, we have to minimize the economic, social, and mental costs of the occurred disasters or incidents. This research analyzes the optimal location of fire stations in terms of served population maximization in Seoul. This research introduces "the maximal covering location problem(MCLP)," one of the optimization techniques, as the primary research method. This research also applies a geographic information system into spatial distribution analyses of existing fire stations and observed fire incidents. Results from the analyses show that the existing location of fire stations and branches need to be improved. The dispatch location of fire engines should be reconsidered for rapid services of fire fighting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1166-1174
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• 2015

There were the attempts to prevent the spread of harmful materials of the agri-food through the record tracking of the products with the bar code, the partial information tracking of the agri-food storage and the delivery vehicle, or the control of the temperature by intuition. However, there were many problems in the attempts because of the insufficient information, the information distortion and the independent information network of each distribution company. As a result, it is difficult to prevent the spread over the life-cycle of the agri-food using the attempts. To solve the problems, we propose the mechanism mainly to do context awareness, predict, and track the harmful materials of agri-food using big data processing.

• Journal of radiological science and technology
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• v.24 no.1
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• pp.11-15
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• 2001

Symptoms of caliceal diverticular stones are commonly associated with pain, recurrent urinary tract infection and hematuria. The aim of this study is to select the proper patient for the application of more successful extracorporeal shock wave lithotripsy(ESWL) as a treatment of caliceal diverticular stone. 16 patients with caliceal diverticular stones were treated with ESWL, and all patients had single caliceal diverticulum. The diagnosis of caliceal diverticulum with stones was made by intraveneous pyelography to all patients. On these intravenous pyelogram, we also classified diverticular type, whether the diverticular neck is connected with urinary tract patently, diverticular site and stone number and size. All patients were followed after ESWL by plain film of the kidneys, ureters and bladder and interviewed. Of all patients 44% was shown stone-free completely, also 83% was rendered symptom-free. All patients whose diverticular neck connected with urinary tract patently on the intraveneous pyelogram became stone- free. Of solitary stone 60% and multiple stones(more than 2) 17% became stone free. All patients rendered stone-free became symptom-free, and of patients with residual stones 44% became symptom-free. The patients with infection before ESWL 75% had residual stones, of these patients 33% had slightly flank pain, and 25% of patients with stones recurred become stone-free. We propose that more successful ESWL for patients with caliceal diverticular stones select satisfactory patients including that the diverticular neck is connected with urinary tract patently, solitary stone and no infection simultaneously.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.11
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• pp.974-980
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• 2014

A power supply of cathode has been developed for hall-effect thruster for small satellite. A microwave cathode has been applied to the electric propulsion system and cathode power is necessary in oder to work securely. Anode current is varied by a flow rate controlled by anode tank pressure. Then cathode current has to be controled in proportion by anode current. So cathode power supply has been designed to offer a current proportional to anode current. Also cathode power has been tuned to work securely for cathode to emit more electron than anode within 0.03A. The function test of cathode power was performed by constructing an equivalent load for anode and cathode. It has been tested in a vacuum chamber in order to ensure a stable operation of the thruster. And it was confirmed that thruster normally has been operated in the space environment after the launch.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.491-497
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• 2005

Brake system is indispensible functional part to the transportation machines such as railroad cars, and all of industrial machines. It is mechanical element to stop the movement or slow the speed, transforming kinetic energy of motion object into thermal energy through solid friction. According that recently the railroad cars have become high-speed, the technique in braking domain to secure the overall braking effort is making rapid progress. In particular, material development and manufacturing process are so important to secure friction performance, which is the core in braking performance of mechanical brake units. Wear of brake disk could mainly result in the diminishment of its life span due to thermal cracking, so the endurance against high temperature is required. On the other hand, in this case, the problem is that the side wear of pad, relative material is slightly increased because of enlargement of plastic deformation. It is necessary, therefore, to develop a disk material that will be used in the Tilting System mechanical brake units. The purpose of this paper is to make a study prior to developing brake disk of Tilting Train travelling at 200km/h and to propose the component of brake disk. Accordingly, I will conduct sufficient researches on technical documents of brake disk, that are basic documentations, analyze an impact on components, and further, considering braking degree of train, study for the basic proposal on brake disk's component of the train travelling at 200km/h, which has relatively minor influence of heat stress and maintains the friction. In this respect, I would like to investigate friction characteristics between disk and relative friction material via Test on some possible test segments, analyze and propose friction performance, temperature impact and so forth coming from the contact with pad, relative material to demonstrate the friction characteristics.

• The Journal of the Korea Contents Association
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• v.11 no.10
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• pp.1-10
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• 2011

In this paper, we proposed the skin color based hand and finger detection technology for the gesture recognition in CCTV surveillance. The aim of this paper is to present the methodology for hand detection and propose the finger detection method. The detected hand and finger can be used to implement the non-contact mouse. This technology can be used to control the home devices such as home-theater and television. Skin color is used to segment the hand region from background and contour is extracted from the segmented hand. Analysis of contour gives us the location of finger tip in the hand. After detecting the location of the fingertip, this system tracks the fingertip by using only R channel alone, and in recognition of hand motions to apply differential image, such as the removal of useless image shows a robust side. We explain about experiment which relates in fingertip tracking and finger gestures recognition, and experiment result shows the accuracy above 96%.

• Development and Reproduction
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• v.13 no.4
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• pp.271-280
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• 2009

Human placenta is abundant source of adult stem cells. Especially, amniotic epithelial cells have stem cell characteristics, expressing surface markers normally present on embryonic stem cells and germ cells. However, culturing and expanding amniotic epithelial cells in vitro without feeder cells are difficult due to endogenous characteristics of epithelial cells. In the present study, amniotic epithelial cells are isolated and proliferated in several passages by applying dithiothreitol and a Rho-associated kinase inhibitor in culture media. The cultured amniotic epithelial cells showed the epithelial and stem cell characteristics. In conclusion, human placenta-derived amniotic epithelial stem cells can be a major source of stem cells for medical treatment of various diseases without any controversial issues.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.2
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• pp.127-135
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• 2017

The computing environment has changed rapidly to enable large-scale finite element models to be analyzed at the PC or workstation level, such as multi-core CPU, optimal math kernel library implementing BLAS and LAPACK, and popularization of direct sparse solvers. In this paper, the design considerations on a parallel finite element code for shared memory based multi-core CPU system are proposed; (1) the use of optimized numerical libraries, (2) the use of latest direct sparse solvers, (3) parallelism using OpenMP for computing element stiffness matrices, and (4) assembly techniques using triplets, which is a type of sparse matrix storage. In addition, the parallelization effect is examined on the time-consuming works through a large scale finite element model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.3
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• pp.185-191
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• 2007

For the seismic performance enhancement of residential flat plate structure and for the selection of earthquake records, the possibility of base isolation is evaluated and the time history results are reviewed. By evaluating a base isolated stiffness, a target period, and an envelope curve analysis, seismic performance of structure, which has strong rotational mode, is evaluated. For the propriety evaluation of earthquake records usage and scaling method, time history analysis is done with variables such as DBE(design base earthquake) level, MCE(maximum considerable earthquake) level, and 1.4DBE level. From the analysis results, following conclusions can be made; the earthquake records, which are used in base isolation analysis, should be selected by similar soil type which the structure is considered, and should be intensity scaled in a range of mean ${\pm}$ standard deviation of code based design response spectrum.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.17-23
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• 2009

Deformational characteristics of subgrade soils are very important input parameters for pavement design. It is necessary to make an amount of effort to estimate experimentally the modulus of subgrade soils. In case of designing simple (or lower level) pavement section, the estimation of the modulus based on experiments must cause an excessive cost. It has proposed various empirical correlation models to estimate the modulus from basic properties of the materials or more simple alternative tests. Seven subgrade soils in Korea were tested in this study. It was founded that the deformational characteristics of subgrade soils in Korea has a close relation to strength characteristics, the empirical correlation model was proposed. There was a close relation between cohesion value and modulus at low confining stress ($r^2=0.93$). By comparing with the measured modulus and the modulus determined by proposed correlation model from strength characteristics, the value of the coefficient of determination ($r^2$) is 0.75.