• Journal of radiological science and technology
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• v.41 no.4
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• pp.289-295
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• 2018

When using a mobile X-ray unit, primary radiation creates medical images and secondary radiation scatters in many directions, which reduces image quality and causes exposure to patients, care givers and medical personnel. The purpose of this study was to develop a radiation shielding system for effectively shielding secondary radiation and evaluate its effectiveness. Using a mobile X-ray unit, spatial dose according to presence of human equivalent phantom and spatial dose using the developed shielding device were measured, and the phantom at 80 cm equidistance from center of X-ray was compared with spatial dose according to use of a shield. Measurements were taken at intervals of 10 cm every $30^{\circ}$ from the head direction($-90^{\circ}$) to the body direction($+90^{\circ}$). In the spatial dose measurement with and without the phantom, when the human equivalent Phantom was used, the spatial dose was increased by 40% in all directions from 40 cm to 100 cm from the central X-ray, and about 88% of the space dose was reduced when using the developed shields with the phantom. The equidistance dose at 80 cm from the central X-ray was increased by 39% from $5.1{\pm}0.26{\mu}Gy$ to $7.1{\pm}0.15{\mu}Gy$ when the human equivalent phantom was used, and when phantom was used and shielding was used, the spatial dose was reduced by about 90% from $7.1{\pm}0.15{\mu}Gy$ to $0.7{\pm}0.07{\mu}Gy$. The spatial dose of natural radiation was measured to be about $0.2{\pm}0.04{\mu}Gy$ when using the developed shielding with Phantom at a distance of 1 m or more. It is expected that by using the developed shielding system, it will be possible to effectively reduce secondary radiation dose received in all directions and to ensure safe imaging.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.765-771
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• 2012

$SF_6$ gas has been used as arc quenching and insulating medium for high and extra high voltage switching devices due to its high dielectric strength, its excellent arc-quenching capabilities, its high chemical stability and non toxicity. Despite of its significant contributions, the gas was classified as one of the greenhouse gas in the Kyoto Protocol. Thus, many researches are conducted to find out the replacement materials and to develop the $SF_6$ gas useless electrical equipment. This paper describes experiments on the temperature change-related breakdown characteristics of $SF_6$ gas ($SF_6$) and $SF_6$ liquid ($LSF_6$) in a model GIS(Gas-Insulated Switchgear) chamber in order to show the possibility of more stable and safe usages of $SF_6$ gas. The breakdown characteristics are classified into three stages, namely the gas stage of $SF_6$ according to Paschen's law, the coexisting stage of $SF_6$ gas with liquid in considerable deviation at lower temperature, and the stage of $LSF_6$ and remaining air. The result shows that the ability of the $LSF_6$ insulation is higher than the high-pressurized $SF_6$. Moreover, it reveals that the breakdown characteristics of $LSF_6$ are produced by bubble-formed $LSF_6$ evaporation and bubbles caused by high electric emission and the corona. In addition, the property of dielectric breakdown of $LSF_6$ is determined by electrode form, electrode arrangement, bubble formation and movement, arc extinguishing capacity of the media, difficulty in corona formation, and the distance between electrodes. The bubble formation and flow separation phenomena were identified for $LSF_6$. It provides fundamental data not only for $SF_6$ gas useless equipment but also for electric insulation design of high-temperature superconductor and cryogenic equipment machinery, which will be developed in future studies.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.444-451
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• 2013

The purpose of this study was to investigate the changes in temporospatial variables in healthy elderly and healthy adults during usual walking, narrow base walking and centerline-guided walking. Twenty healthy elderly and nineteen healthy adults were participated in this study. In each conditions, the subjects were walked on a 6m walkway at comfortable self-selected speeds under three conditions : (1) usual walking, (2) walking within a 50% of the distance between the subject's ASIS (3) walking along a centerline. GAITRite system was used for kinematic analysis to assess the temporospatial variables. There were no significant changes in healthy adults(p>.05), but walking speed, cadence, H-H base support, functional ambulation performance were significantly decreased progressively as pathway narrowed in elderly adults(p<.05). The results show that elderly people had more difficulty with walking on narrow pathway for fear of falling. This study provides data for use in basic research into safe walking and preventing falling for elderly.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.1
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• pp.51-59
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• 2004

The effectiveness of one dimensional critical velocity method for evacuation environment at 10MW fire size in a railroad tunnel have been investigated in this paper by three dimensional CFD method. It was performed to evaluate the evacuation environment in terms of temperature distribution, visible distance distribution and CO concentration at some tunnel inlet velocity, 1m/s, 2m/s (near critical velocity), and 3m/s. At all inlet velocity, passenger should give away downward the flow direction because the inlet velocity can not afford to sufficient evacuation environment for passengers. In case of 3m/s inlet velocity, however, the evacuation environment for passengers is better than the other cases. To provide more safe evacuation environment on fire situation, tunnel inlet velocity should be larger than critical velocity.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.2
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• pp.115-128
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• 2006

The structural anisotropy and heterogeneity of rock mass, caused by discontinuities and weak zones, have a great influence on the deformation behavior of a tunnel. A tunnel construction in these complex ground conditions is very difficult. No matter how excellent a geological investigation is, local uncertainties of rock mass conditions still remain. Under these uncertain circumstances, an accurate forecast of the ground conditions ahead of the advancing tunnel face is indispensable to a safe and economic tunnel construction. This paper presents the effect of anisotropy and heterogeneity of the rock masses to be excavated by numerical analysis. The influences of distance from weak zone, the size or dimension, the different stiffness and the orientation of weak zones are analysed by 3-D finite element analysis. By analysing these numerical results, the tunnel behavior due to excavation can be well understood and the prediction of rock mass condition ahead of the tunnel face can be possible.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6733-6736
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• 2014

Background: Despite the growing acceptance of laparoscopic colon surgery, an abdominal incision is needed to remove the specimen and perform an anastomosis. Recently, natural orifice specimen extraction (NOSE) and intracorporeal anastomosis have been proposed to minimize abdominal wall trauma and improve the quality of laparoscopic colon resections Objective: To evaluate the feasibility and safety of a new approach combining intracorporeal delta-shaped anastomosis and transvaginal specimen extraction for totally laparoscopic sigmoid colectomy. Materials and Methods: Mobilization of bowel and dissection of lymph nodes were performed laparoscopically. After both proximal and distal incisal edges about 10.0 cm distance from sigmoid neoplasm were transected with an Endoscopic Linear Cutter-Straight, a small incision about 1.0 cm was created on the each colon wall of the contralateral side of the mesentery. Then anvils of an Endoscopic Linear Cutter-Straight were inserted into each colon through the small incisions, and incision and anastomosis between the walls of each colon were performed with a linear stapler. A V-shaped anastomosis was made on the wall and the remnant openings was reclosed with the Endoscopic Linear Cutter-Straight. The culdotomy was enlarged with laparoscopic ultrasound dissector. Transvaginal extraction of specimens was accomplished through a wound protector. Results: Surgery was performed for 11 patients with sigmoid cancer. No intraoperative complications or conversions occurred. The mean operating time was 132 min. All the patients were treated laparoscopically without any postoperative complications. Conclusions: The procedures of intracorporeal delta-shaped anastomosis and transvaginal specimen extraction are safe and oncologically acceptable for selected colon cancer cases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.4006-4011
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• 2013

Reverse parking guidance system help driver's safe reverse parking with display of the expected reverse path of the car on portable navigation device or rear-view camera display. In this paper, we suggest a reverse path prediction method of vehicle which reflect the differences in steering angle according to various types of vehicles and calibrate easily the distance error according to the property and the installation position of rear-view camera and we developed reverse parking guidance system with the our reverse path prediction method. This system can be applied to various types of vehicles, a variety of characteristics and installation of rear-view camera and navigation support systems, or portable devices are compatible and easily detachable, can be configured easily.

• Journal of Labour Economics
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• v.23 no.1
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• pp.103-135
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• 2000

After scrutinizing the actual conditions of labor participation in management decision makings through analysing the collective agreements and the regulations of labor-management committee at the affiliated companies of Korea's top-five Chaebols, we could get some conclusions as follows. First, because the labor participation in management decision makings is in very inactive situations at the long-term management strategy level and the workplace practice level of industrial relations, both parties of the industrial relations in those companies surveyed show the serious lack of abilities to tackle the new and rapidly changing business environments as nowadays actively and cooperatively. Second, we could find the fact that in the surveyed companies the device of collective bargaining was used more commonly at the collective bargaining level of industrial relations and the device of labor-management committee was often used relatively at the long-term management strategy level and the workplace practice level. Third, we could conclude that the separating type of the labor-management committee which was able to keep a safe distance from the more antagonistic device, the collective bargaining, was much more efficient device of the labor participation in management decision makings.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.56-67
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• 1999

This study was performed to suggest the basic data and plans for the establishment of safe water supply plans in simple water supply piped system in the rural areas. In 4 different places, 24 points of water sources 36 points of taps from water sources were sampled. Of the whole 60 points, 55 points were ground water and 5 points were surface water. 14 items were measured for the analysis of water quality on each samples. The measured items were analyzed again by statistical method ; cluster analysis and principle components analysis. The results of this study are as followed. 1) In water quality analysis on water sources, 4 items, bacteria, E.coli, NH3-N and Fe exceed the standard. Of 24 points, 20 points(83%) on bacteria, 1 point(4%) on NH3-N and Fe exceed the standard. 2) In water quality analysis on near and remote taps, 4 items, bacteria, E.coli, NH3-N and Fe , exceed the standard. Of 36 points, 20 points (81%) on bactria, 1 pint(3%) on NH3-N and Fe exceed the standard. 3)Cluster analysis on water quality shows the differences by the kinds of water sources, geographical characteristics and distance from water sources. 4) Principle components analysis on ground water shows that Factor 1 and Factor 3 are natural fluctuation by the content of soil. Also, Factor 2 and Factor 4 are penetration of pollutants to underground. Therefore, it is needed to take deeper ground water in order to prevent from pollution in the areas which have ground water as water source . 5) Principle components analysis on surface water shows that Factor 1 is penetration of vacteria from surface to water source when rainfalls. Also, Factor 2 is fluctuation of water quality by the geographical characteristics. Therefore, the counterplans against non-point pollution source must be taken. Filtration and disinfection facilities are needed in the areas which have surface water as water source.

• Korean Security Journal
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• no.62
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• pp.277-293
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• 2020

The purpose of this study is to select the talented and competent personal caregiver personnel through a professional and rational inspection system, and to provide safer personal care services to the public so that the people who are eligible for service can lead a safe life. The purpose of this study is to cultivate qualified and competent personal guardian personnel and provide professional and stable services to the people so that the people who can use the service can lead a safer life. In order to grow into a system that meets the objectives of the personal guardian qualification screening system, it must be revised and supplemented from various evaluation methods. The improvement measures related to the practical test of the system for qualifying personal guardians are as follows. First, the fitness evaluation items should be added. Second, it is necessary to reestablish the test technology. (Remove technology that causes the second threat) (Adds skills that can be used as civilian status) Third, the fallout and application action must be added. Fourth, evaluation in various starting positions is necessary. Fifth, evaluation should be made by diversifying the distance and direction with the opponent.