• Proceedings of the KSR Conference
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• 2001.10a
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• pp.147-155
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• 2001

A data acquisition and signal processing system for evaluating the current collection system is developed, and subsequently applied to the measurement and analysis of the contact force in the current collection system of the proposed Korean High Speed Railway. The measurement of the contact force is based on an algorithm that employs the relationship between the contact force, the strain due to the bending moment and the panhead inertia. For the contact forces in the frequency range of less that 50Hz, the panhead can the modeled as a rigid body in the inertia calculation. For higher frequencies however, the bending vibration modes of the panhead need to be accounted for as well.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.157-160
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• 2010

Management of indoor air quality of underground subway station is an important issue since the limited natural ventilation, limited sunshine incoming, and highly moistured atmosphere. The improvement in IAQ of platform is expected because most stations were installed with platform screen door currently, however, the poor air quality in tunnel might be affecting subway cabin indoor. In this study, we developed the air quality assessment model based on computational fluid dynamics. The geometry of air ventilation unit, seat, LCD monitors, and passengers were modeled using commercial software (Design Modeler) and fluid pattern and pollutants trajectories were analyzed by using CFX. We predicted the thermal comfort by predicted mean vote (PMV), distribution of CO2 and PM10 concentration. It is expected that this model can be used for the performance test of air cleaners which are under development.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.1
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• pp.258-265
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• 2016

This study was to describe and understand the experiences of the physical disabled adult attending in public welfare program. The interview data were collected from seven persons and analyzed by using descriptive phenomenology of Colazzi. The procedural steps were that described the phenomenon of interest, collected participants' descriptions of the phenomenon, extracted the meaning of significant statements, organized the meanings into them clusters, wrote exhaustive descriptions and then incorporated data into an exhaustive description. The finding in 129 re-statements, 63 constructed meanings, 35 themes, 13 theme clusters, and six categories were deduced. The six categories were 'Life patterns exclusive health', 'Powerlessness by physical disabilities', 'Social supports', 'Positive motivation', 'Seeking to be holistic health', and 'Sense of accomplishment'. The study identified that social welfare program for the disabled necessities for health, learning, economy and their future in success. Therefore, we suggest there may be a need for supplying professional program for their health and welfare.

• Korean Journal of Optics and Photonics
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• v.5 no.3
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• pp.418-422
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• 1994

본 연구에서는 MOVPE를 이용한 MQW활성층을 DFB-LD 구조에 도입함으로서 2.5Gbps 광전송용 광원으로 사용된 $ 1.55.\mu$m 파장의 MQW-PBH-DFB-LD를 제작하였다. 활성층으로는 MOVPE를 이용하여 8쌍의 InGaAs/InGaAsP MQW층을 성장하였으며 2차 및 3차 결정성장은 LPE를 사용하였고 발진파장을 결정하는 회절격자 주기는 238nm로 하였다. MQW-PBH-DFB-LD의 평균 임계전류는 13.81mA, Slope efficiency는 0.137mW/mA이었고 발진파장은 1548.6nm의 특성을 얻었다. 그리고 2.5Gbps 대신호 변조시의 chirping특성을 조사하여 본 결과 0.55nm임을 확인할 수가 있었다.

• Journal of Environmental Impact Assessment
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• v.5 no.1
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• pp.95-105
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• 1996

Meteorological Joint Frequency Function required indispensably in long-term air quality prediction models were discussed for practical application in Korea. The algorithm, proposed by Turner(l964), is processed with daily solar insolation and cloudiness and height basically using Pasquill's atmospheric stability classification method. In spite of its necessity and applicability, the computer program, called STAR(STability ARray), had some significant difficulties caused from the difference in meteorological data format between that of original U.S. version and Korean's. To cope with the problems, revised STAR program for Korean users were composed of followings; applicability in any site of Korea with regard to local solar angle modification; feasibility with both of data which observed by two classes of weather service centers; and examination on output format associated with prediction models which should be used.

• Journal of Power System Engineering
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• v.20 no.6
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• pp.51-57
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• 2016

Experiment is carried out to investigate the mixed convective flow in three-dimensional horizontal rectangular channels filled with high viscous fluid. The particle image velocimetry(PIV) with thermo-sensitive liquid crystal tracers is used for visualizing and analysis. Quantitative data of temperature and velocity are obtained by applying the color-image processing to a visualized image, and neural network is applied to the color-to-temperature calibration. In this study, the fluid used is silicon oil(Pr=909), the aspect ratio(channel width to heigh) is 4 and Reynolds number is $2{\times}10^{-2}$. From the present study, we can visualize the quantitative temperature and velocity of mixed convective flow in three-dimensional horizontal rectangular channels simultaneously.

• Radiation Oncology Journal
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• v.2 no.1
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• pp.123-128
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• 1984

To determine the effectiveness of radiotherapy for pain control in metastatic bone disease, we retrospectively analyzed the treatment results in 126 patients who received short-course radiotherapr(2,000 rad/1wk vs 3,000 rad/2wks) in the Department of Therapeutic Radiology, Seoul National University Hospital from Feb. 1979 to July 1983. Pain relief was obtained in $82\%$ of patients and complete Pain relief was obtained in $35.3\%$ of patients. The incidence of metastatic bone tumor was highest in spine and pelvis, $43.7\%\;and\;26.3\%$>, respectively. Primary sites of metastasia were lung, breast, unknown primary, stomach, uterine cervix, in order of frequency. There was no significant difference in the response to treatment between 2,000 rad in 1 week and 3,000 rad in 2 weeks.

• Journal of architectural history
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• v.14 no.1 s.41
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• pp.21-39
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• 2005

This study is to examine the Severe-Ornament (Vyuha :Sanskrit) of wooden pagodas in Shilla period in order to assume a detailed shape of wooden pagodas called the palace style, the multi-story style, the towered namsion style, that were built at the temples in Gyeongju during Shilla period. The Severe-Ornament had been used traditionally by installing a Buddhist image, Guardians, Sarira and by printing a color. The other hand, The roof tiles and tiles were annexed to the Severe-Ornament so as to enhance the value of the wooden pagodas. The Vyuha had been used not only to install a highly valued Buddhist image in the wooden pagodas but also to represent an important part of ritual art of Silla period. Therefore, it was possible to find out a variety of details of the wooden pagodas in Shilla period.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.119-125
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• 1995

Strained multiple quantum well(SMQW) PBH-DFB-LDs emitting at 1.55$\mu$m wavelength has been fabricated using OMVPE and LPE crystal growth tecnique. Using the SMQW active layer, a linewidty enhancement factor of 2.65 was obtained at lasing wavelength and consequnently, packaged 42 modules showed a very low average chirp of 0.44nm at 2.5Gbps NRZ direct modulation. The 77 devices showed average threshold current of 8.72mA and average slope efficiency of 0.181 mW/mA, and single longitudinal mode operation with SMSR larger than 30dB up to 5mW. Among the 77 devices, standard deviation of lasing wavelength of 3.57nm was obtained owing to a good crystal growth uniformity.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.9
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• pp.139-145
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• 1994

InGaAsP/InP PBH-DFB-LD emitting at 1.55${\mu}$m wavelength has been fabricated for 2.5Gbps optical fiber communcations. For fabrication of PBH-DFB-LD, Interference expose for grating formation 3-step LPE epitaxial growth were used. Fabricated PBH-DFB-LD operates in single longitudinal mode with larger than 35dB SMSR and wider than 3dB bandwidth of 3GHz. A 8${\mu}$m mesa structure was introduced by channel etching to reuce parasitic capacitance. To reduce pad capacitance, we designed a small electrode. 0.27mW/mA in the case of spectrum shows single logitudinal mode operation with larger thatn 30dB SMSR measured at 5mW.