• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.2
• /
• pp.207-211
• /
• 1999

$Si/Si_{1-x}Ge_x$ MODFET structures, incorporating linearly-graded buffer layers have been grown by GaS Source Molecular Beam Epitaxy. The growth temperature of the graded layers has not significantly changed the distribution of misfit dislocation. However, the surface undulation and surface defects were increased with increasing growth temperature. In $Si/Si_{1-x}Ge_x$ MODFET structures, the densities of misfit dislocations near the Si-active layers were considerably reduced in comparison with the region of graded layers. The electron mobility of $Si/Si_{1-x}Ge_x$ MODFET structure has increased with lowering the growth temperature.

• Journal of Korean Society for Atmospheric Environment
• /
• v.20 no.1
• /
• pp.17-31
• /
• 2004

The subway play an important part in serious traffic problems. However, because subway system is a closed environment, many serious air pollution problems occurred in subway stations and injured passenger's health. Therefor, it is a necessary to identify sources and to estimate pollutant sources in order to protect passenger's health and to keep clean subway environment. The purpose of this study was to analyze a air quality in the subway stations and to apply a new receptor methodology for quantitatively estimate of PM10 sources. In this study, the size distributions of particulate matters has been measured by using Aerosizer LD (U.S.A., API, Inc.). It's real time measurement capability of time-of-flight technique offers a significant advantage of user convenience and air pollution management. Also, the mass concentrations of PM 10 has been measured by using mini-vol portable sampler (U.S.A., Airmetrics Co.). The sampling performed in Seoul subway stations during the period of February 2000 and April 2000. The number distribution data used in this study consisted of 26 raw data sets in the Jongno-sam-ga station. Correlation Analysis can be used in subway stations for source separation and identification. Then, number contribution from each source is determined by the particle number balance (PNB). The mass concentration data used in this study consisted of 31 raw data in the 8 different stations. The mass contributions of PM10 sources in the concourse by using PMF/CMB model.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.18 no.3
• /
• pp.396-410
• /
• 1996

This study was carried out to evaluate the distribution and the degree of the asymmetry existed in normal persons and asymmetric patients, and to investigate the changes of asymmetric patients after orthognathic surgery. The analysis was performed with the posteroanterior cephalometric radiography of 60 normal persons and 31 facial asymmetric patients. The results were as follows : 1. The degree of normal asymmetry existed in normal persons was not significant except MF and Me measurements. 2. The degree of normal asymmetry according to sex difference was not significant except cranial base area. 3. When normal persons were compared to asymmetric patients, there were more measurements which presented significant asymmetry on mandible than on maxilla. 4. When postoperative state was compared to preoperative state, the degree of asymmetry were usually decreased except AGO and GA measurements, especially the Cd, MF, Me, and Cd-Me measurements decreased significantly. 5. When postoperative state was compared to normal persons, 4 measurements of mandible approached significantly the measurements of normal persons.

• Journal of the Korean institute of surface engineering
• /
• v.43 no.6
• /
• pp.304-308
• /
• 2010

Deposition temperature uniformity of GaN based MQW (multiple quantum well) layers is an important key which affects the wavelength uniformity of white LEDs. Temperature uniformity was assessed by infrared images for both cases of a static and a rotating susceptor. Rotating the susceptor at 2.5 rpm over the induction heater gave 4.3% of temperature non-uniformity. Temperature distribution of the graphite susceptor over the induction heater was numerically modelled and agreed with experimental results.

• Journal of Electrical Engineering and Technology
• /
• v.4 no.2
• /
• pp.185-193
• /
• 2009

This paper presents a methodology for photovoltaic (PV) system allocation in distribution systems using a discrete particle swarm optimization (DPSO). The PV allocation problem is in the category of mixed integer nonlinear programming and its formulation may include multi-valued dis-crete variables. Thus, the PSO requires a scheme to deal with multi-valued discrete variables. This paper introduces a novel multi-level quantization scheme using a sigmoid function for discrete particle swarm optimization. The technique is employed to a standard PSO architecture; the same velocity update equation as in continuous versions of PSO is used but the particle's positions are updated in an alternative manner. The set of multi-level quantization is defined as integer multiples of powers-of-two terms to efficiently approximate the sigmoid function in transforming a particle's position into discrete values. A comparison with a genetic algorithm (GA) is performed to verify the quality of the solutions obtained.

• Journal of the Korean Institute of Rural Architecture
• /
• v.13 no.4
• /
• pp.83-90
• /
• 2011

The purpose of this study is to grasp the color situation of buildings on Urban Street, through the color image evaluation to research primary factors have an effect on color image preferences. A scope of this study is district of Sang Mu in Gwangju Metropolitan City. A method of study put out evaluation model after BIB test by photography, spot color. And performed Factorial Design, Multiple Regression Analysis through SD questionnaire. The result of this study show that color situation exceedingly used YR predominates, support, stress color, in the second place used predominate, support color is B, stress color is R. Luminosity showed middle luminosity 4.1~7.0, low freshness distribution. Color image was evaluated modern and cold image and appeared affirmative aspect clean, order, neat image and showed negative aspect stiff, flat image. And 'comfortableness', 'unification' had an effect on color image preferences The result of this study showed that color plan need to improve comfortableness, unification bring control into line color at building color image of urban street.

• Asian Journal of Atmospheric Environment
• /
• v.4 no.3
• /
• pp.166-176
• /
• 2010

In this research, the environmental behavior of carbon dioxide ($CO_2$) was investigated in a mountainous site in the proximity of a highly industrialized megacity, Seoul, Korea. The concentration data of $CO_2$ monitored routinely at hourly intervals at Mt. Gwan-Ak (GA), Seoul, Korea throughout 2009 were analyzed in several respects. The mean $CO_2$ value was $405{\pm}12.1$ ppm (median=403 ppm) with a range of 344 to 508 ppm (N=8548). The analysis of its seasonal trend indicated that the $CO_2$ levels peaked in the winter but reached a minimum in fall. If the short-term trend is analyzed, the $CO_2$ values generally peaked during daytime along with the presence of two shoulders; this is suspected to be indicative of strong man-made effects (e.g., traffic activities). It is seen that the general patterns of $CO_2$ distribution in this study area are highly comparable to those typically found in urban areas with strong signals of anthropogenic activities.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.1
• /
• pp.1-9
• /
• 2007

This study proposes to increase the energy-saving effects by reducing excessive intensity of radiation of artificial lighting through analyzing daylight incident. A photosensor sends amounts of detected luminous flux to digital control unit(DCU) as a signal and then, it can decide dimming ratios, received a proper dimming signal from DCU. Generally it is effective to control artificial lighting with the different control ratio of each zone by setting a photosensor as same number and rows as artificial lighting. However, it is ineffective to do in initial costs of systems aspect in offices. As a result of grasping the distribution of daylight previously and analyzing daylight and dimming data, we can dim different dimming ratios to each zone of artificial lighting by a single photosensor.

• Proceedings of the KSRS Conference
• /
• v.1
• /
• pp.220-223
• /
• 2006

The COMS(Communication, Ocean and Meteorological Satellite) EPS(Electrical Power Subsystem) is derived from an enhanced Eurostar 3000 EPS which is fully autonomous operation in normal conditions or in the event of a failure and provides a high level of reconfiguration capability and flexibility. This paper introduces the COMS EPS preliminary design result. The COMS EPS consists of a battery, a solar array wing, a PSR(Power Supply Regulator), a PRU(Pyrotechnic Unit), a SADM(Solar Array Drive Mechanism) and relay and fuse brackets. This can offer a bus power capability of 3 kW. The solar array is made of a deployable wing with two panels. One type of solar cells is selected as GaAs/Ge triple junction cells. Li-ion battery is base lined with ten series cell module of five cells in parallel. PSR associated with battery and solar array generates a power bus fully regulated 50 V. Power bus is centralised protection and distribution by relay and fuse brackets. PRU provides power for firing actuators devices. The solar array wing is routed by the SADM under control of the AOCS(Attitude Orbit Control Subsystem). The control and monitoring of the EPS especially of the battery, is performed by the PSR in combination with on-board software.

• International Journal of Advanced Culture Technology
• /
• v.2 no.1
• /
• pp.20-24
• /
• 2014

As the standards organization under ISO responsible for the development of all international financial services standards, ISO/TC 68 plays a key role in the development and adoption of new technologies in the banking, brokerage and insurance industries. In this paper many of its current work projects are introduced for developing ecommerce standards. We need to discuss the recommendations on XML conversion with ISO and other international standard organizations. Each country try to adopt the international standards even though domestic technical standards and barriers. To solve this problem of interworking between these standards, harmonization activities are nedded. For development and distribution of electronic documents to be conformed to international standards, it is enough to have the role of international activities continue to supply part of the domestic industry and the trends in participation and international standard.Our principal focus is on facilitating national and international trade, through the simplification and harmonization of processes, procedures and information flows, and so contributing to the growth of global commerce.