• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.178-179
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• 2008

최근 들어 VSAT 시스템은 수요자의 필요에 의해 많은 기술발전을 가져왔다. 과거에는 저속의 데이터 통신 및 전화위주로 많이 사용되었으나 최근에는 통신량의 증가와 인터넷의 발달로 고속의 데이터통신 시스템으로 발전하고 있다.[1] 따라서 Application Service에 따라 기존의 TDMA 방식의 VSAT 시스템과 고속통신용의 DVB-RCS 시스템으로 양분되어 사용하고 있다. 기존의 TDMA 방식은 주로 SCADA, POS, VOICE 통신 등의 저속 데이터 통신 위주로 많이 사용하고 DVB-RCS 방식은 Multi Media 및 인터넷 서비스로 고속의 데이터 통신 용으로 많이 사용되고 있다. 이에 본 논문에서는 원격 무인 사이트가 Solar-Cell Battery를 이용하는 측면에서 소비전력 최소화 및 유지보수 편리성을 증대하기 위한 측면을 고려하여 무선 원격 자료 전송을 위한 VSAT 시스템 설계, 알고리즘 및 H/W제작을 소개하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.708-717
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• 2009

Recently, Korea government decided to introduce RPS (Renewable Portfolio Standard) mechanism which requires electricity providers to gradually increase the amount of renewable energy sources such as wind, solar, bioenergy, and geothermal. As a consequence, it is expected that the long-term fuel mix would be changed to result in more expensive production and the increased production costs would be distributed to the rate payers via electricity tariffs. This paper presents the change in long-term fuel mix in year 2020 with the four RPS scenarios of 3%, 5%, 10% and 20%, and the methodologies for collecting the increased production costs through new tariff schedule. The studies on long-term fuel mix have been carried out with the GATE-PRO (Generation And Transmission Expansion Program) optimization package, a mixed-integer program developed by the Korea Energy Economics Institute and Hongik university. Three methodologies for distributing the production costs to the rate payers have also been demonstrated.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.147-149
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• 2009

가수분해 및 응축반응을 사용하여 다공성의 TiO2입자를 합성하였다. 다공성 구조의 열적 영향을 살펴보기위해 annealing 시간을 조절하였고 태양전지에 적용하기 위해 paste로 만들었다. 그 구조적 특성을TEM(Transmission electron microscopy)과 XRD(X-ray diffraction) 통하여 분석하였고 광 전기화학적 활성을 측정해 보았다. 결과적으로 3시간 열처리한 시료의 효율이 최적화된 조건이였음을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.105.1-105.1
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• 2011

To enhance the performance of photovoltaic a-Si:H solar cells with a hybrid-type light absorbing structure of single crystal silicon nanoparticles (Si NPs) in a-Si:H matrix, single crystal Si NPs were produced by laser pyrolysis. The Si NPs were synthesized by $SiH_4$ gas decomposition using a $CO_2$ laser. The properties of Si NPs were controlled by process parameters such as $CO_2$ laser power, reactive gas pressure, and $H_2/SiH_4$ gas flows. The crystalline properties and sizes of Si NPs were analyzed by High Resolution Transmission Electron Microscopy (HRTEM). The sizes of Si NPs were controllable in the range of 5-15 nm in diameter and the effects of process parameters of laser pyrolysis were systematically investigated.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.3
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• pp.120-125
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• 2002

The aim of the present work is to optimized the annealing parameter in both front and back screen printed contacts realization on p-type multicrystalline silicon and with phosphorus diffused. The RTA treatments were carried out at various temperatures from 600 to 850$\^{C}$ and annealing time ranging from 3 min to 5 min in air, O$_2$and N$_2$ ambiance. The contacts parameters are obtained according to Transmission Line Model measurements. A good RTA cycle is obtained with a temperature plateau of 700$\^{C}$-750$\^{C}$ and annealing ambiance of air. Several processing parameters required for good cell efficiency are discussed with an emphasis placed on the critical role of the glass frit in the aluminum paste. A anamolus behaviour of Aluminum n-doping on p-type Si wafer, contact at high temperature have also been studied.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.247-250
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• 2008

The paper presents the advanced radiometric calibration method, called the lRCM (Iterative Radiometric Calibration Method), in order to avoid an operational constraint (solar source) for calibration. The IRCM assumes that an optical instrument is equipped with a filter assembly which consists of same band filters with different transmission ratios. Given all the noise sources (including the artificial one caused by the filters) of an image sensor, the noncentral ${\chi}^2$ distribution of the output result is induced by the approach of a noise PDF (Power Density Function). Finally, the radiometric calibration problem is transformed into equating two independent relations for the image sensor gains through the specified distribution.

• KIEAE Journal
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• v.12 no.1
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• pp.127-132
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• 2012

The energy consumption in the world is growing rapidly. And the environmental issues of climate become a important task. The interest in renewable energy like wind and solar is increasing now. Especially, by reducing power transmission loss, a small wind power is getting attention at the residential areas and campus of university. In this study, we attempted to estimate and compare the wind energy density using wind data of AWS (Automatic Weather Station) of H University. In this case of a campus, the weibull distribution parameter C is 2.27, and K is 0.88. According to the data, the energy density of the small wind power is 12.7 W/m2. We did CFD(Computational Fluid Dynamics) simulations at H University campus by 7 wind directions(ENE, ESE, SE, NW, WNW, W, WSW). In the results, we suggest 4 small wind powers. The small wind power generating system can produce 4,514kWh annually.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.643-649
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• 2008

The purpose of this study is to establish a standard for unit cooling load in central control type apartment applied district cooling. The model of unit household was selected. And the standard of coefficient of overall heat transmission, location of unit household, indoor air temperature, solar radiation & thermal conduction at window and interior load was selected, and region, expansion or non-expansion of balcony, pyeong type, azimuth, rate of window area was applied as parameter. And then cooling load simulation was performed. Based on the result of simulation, the synthetic district cooling load was presented for selecting heat source of apartment applied district cooling, and unit cooling load was analyzed according to design parameter.

• Journal of Astronomy and Space Sciences
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• v.9 no.1
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• pp.52-68
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• 1992

The ionosphere in accordance with solar activity can affect the transmission of radio waves. The effect of the ionosphere on the radio wave propagation are scattering of radio waves, attenuation, angle error, ranging error, and time delay. The present study is based on the Korean ionospheirc data obtained at the AnYang Radio Research Laboratory from January 1985 through October 1989. The data are analyzed to show the daily and the annual variations of the ionosphere. The data are also used to simulate the density distribution of the Korean ionosphere following the Chapman law.

• ETRI Journal
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• v.24 no.2
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• pp.153-160
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• 2002

High Altitude Platforms-craft maintaining stations in the stratosphere at altitudes of around 20 km-have been proposed as a means of supporting wireless telecommunications. They could exploit the best aspects of both terrestrial and satellite systems and support efficient frequency re-use plans. For solar powered platforms the power available for the downlink amplifiers may be minimal, particularly at night and/or higher latitudes. This paper discusses a novel type of link based on a modulated retro-directive transponder carried by the HAP. Relying chiefly on the ground station infrastructure, this would substantially reduce power consumption on the platform. We investigate the efficiency of the transponder aperture as a function of its area by developing general models for losses in the transmission lines which interconnect antenna pairs in the retro-directive array.