• Title/Summary/Keyword: 수평면

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A Study on the Reliability Evaluation and Rehabitation of Solar Insolation Data by Field Measurement in Korea (국내 태양에너지 측정데이터의 신뢰성 평가 및 보정에 관한 연구)

  • Jo, Dok-Ki;Kang, Young-Heack
    • Journal of the Korean Solar Energy Society
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    • v.25 no.3
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    • pp.11-18
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    • 2005
  • The Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 at different locations. Because of a poor reliability of existing data, KIER's new data will be extensively used by the solar system users as well as by research institutes. But the quality of solar insolation data is not always good. This reports on an attempt to identify systematic error in such data using clear-day analysis for data rehabilitation. Clear-day analysis is successful in uncovering solar insolation data of questionable quality. It is not proven that rehabilitation process can improve the quality of data for daily or monthly means, but it is suggested that the method can be used to improve the quality of data for monthly means of several years for use in many applications of solar energy planning. Earlier studies finding a maximum ETR of about 0.80 are confirmed.

A Study on the Solar Radiation Estimation of 16 Areas in Korea Using Cloud Cover (운량을 고려한 국내 16개 지역의 일사량 예측방법)

  • Jo, Dok-Ki;Kang, Young-Heack
    • Journal of the Korean Solar Energy Society
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    • v.30 no.4
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    • pp.15-21
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    • 2010
  • Radiation data are the best source of information for estimating average incident radiation. Lacking this or data from nearby locations of similar climate, it is possible to use empirical relation ships to estimate radiation from days of cloudiness. It is necessary to estimate the regression coefficients in order to predict the daily global radiation on a horizontal surface. There fore many different equations have proposed to evaluate them for certain areas. In this work a new correlation has been made to predict the solar radiation for 16 different areas over Korea by estimating the regression coefficients taking into account cloud cover. Particularly, the straight line regression model proposed shows reliable results for estimating the global radiation on a horizontal surface with monthly average deviation of -0.26 to +0.53% and each station annual average deviation of -1.61 to +1.7% from measured values.

Behavior and Lateral Force of H-piles under lateral Soil Movement in Sand (측방변형을 일으키는 모래지반속의 H형 말뚝에 작용하는 수평력)

  • 김영인
    • Journal of Ocean Engineering and Technology
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    • v.16 no.6
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    • pp.44-48
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    • 2002
  • In lateral ground flow, slope stability, and land slide problems, H-piles have often been used, on a horizontally deforming ground, to prevent the failure of mass of soil in a downward and outward movement of a slope. Here, theoretical equations are derived to estimate the lateral force, assuming that the Mohr-Coulomb's plastic states occur in the ground, just around H-piles. In this study, some model experiments were performed to check the lateral forces determined from theoretical equations, using several pile widths, heights and various interval ratios between H-piles for sand specimens. The solution of the theoretical equation, derived from previous studies, showed reasonable characteristics for constants of soil, as well as for the interval, widths, and heights of H-Pile.

Solar Radiation Estimation Using Cloud Cover and Hours of Bright Sunshine (운량과 일조시간에 의한 태양자원 예측)

  • Jo, Dok-Ki;Yun, Chang-Yeol;Kim, Kwang-Deuk;Kang, Young-Heack
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.126-129
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    • 2012
  • In this work a new correlation has been made to predict the solar radiation for 16 different areas over Korea by estimating the regression coefficients taking into account cloud hours of bright sunshine. Particularly, the multiple linear regression model proposed shows reliable results for estimating the global radiation on a horizontal surface with monthly average deviation of -0.26 to +0.53% and each station annual average deviation of -1.61 to +1.7% from measured values.

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A Characteristic Analysis of Solar Radiation Resources in Korea (국내 일사량 자원 특성분석)

  • Jo, Dok-Ki;Yun, Chang-Yeol;Kim, Kwang-Deuk;Kang, Young-Heak
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.413-416
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    • 2009
  • Since the solar radiation is main input for sizing any solar photovoltaic system and solar thermal power system, it will be necessary to understand and evaluate the insolation data. The Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 and direct normal insolation data since December 1992 at 16 different locations. Because of a poor reliability of existing data, KIER's new data will be extensively used by solar energy system users as well as by research institutes. Among some significant results, the yearly averaged horizontal global insolation was turned out 3.61 kWh/$m^2$/day and the yearly mean 5.38 kWh/$m^2$/day of the direct normal insolation was evaluated for clear days.

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A Estimation Technique of Typical Day for Solar Energy System Design (태양에너지 시스템 설계를 위한 Typical Day 예측기법)

  • Jo, Dok-Ki;Yun, Chang-Yeol;Kim, Kwang-Deuk;Kang, Young-Heak
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.409-412
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    • 2009
  • In this research, the intensity of solar energy, which was injected to the different angle plane every hour day by day, was technically documented and quantitatively analyzed through actual observations. In order to group every days into days with similar intensity, graph was drawn with respect to time for every day and each area value under the curve was calculated. Then, the search for grouped days having similar intensity curve patterns was carried out and the optimum incident angle of absorber plate was derived to maximize the efficiency of solar energy systems.

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On the Estimates of Radiation on Horizontal Surface During Winter in Korea (동계 한국의 수평면 일사량 추정에 관하여)

  • 한영호
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.13 no.1
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    • pp.7-10
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    • 1977
  • In estimates of horizontal radiation, its values are determined by correlations among the length of day, noon altitude of the sun, and cloud amount. During winter from 1971 to 1974 in Korea, its correlations are calculated by empirical method are $$Q_o=0.0124 H_cT_d at clear day and$$ $$ Q_s=0.0124 H_cT_d (1-0.0C4^1.3) at cloudy day.$$ here$ Q_o, Q_s, H_c, T_d, C $ are horizontal radiation at clear day, horizontal radiation at cloudy day, noon altitude of the sun, length of day, and cloud amount. In applications of this equation at 10 stations in Korea, errors are less than 10% when cloud amount are less than 7, and 1O~20% when cloud amount are more than 7. But, according to Laevastu equation in same case, errors are 50% closely.

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이온빔 증착법으로 제작한 수직자기이방성[Co/Pt]${\times}$5 다층박막의 열적안정성

  • 김미선;이진용;최종구;황도근;이상석
    • Proceedings of the Korean Magnestics Society Conference
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    • 2004.06a
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    • pp.206-207
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    • 2004
  • 수직자기이방성을 갖는 [Co/Pt]$\times$5 다층박막을 상온에서 이온빔 증착(ion beam deposition)법으로 제작하여 자기적 및 열적 특성을 연구하였다. 수직자기이방성 특성은 비정상 홀(Hall)-전압법으로 측정하였으며, 표면광 Kerr 효과로 확인하였다. $[Co(10{\AA}/Pt(12.5{\AA})]{\times}5$) 다층박막에서 수직자성 보자력은 400 Oe이었고 수평자성은 매우 큰 곤란축(hard-axis) 특성을 유지하였다. 진공 열처리 시 1 kOe의 균일한 자기장이 박막면 수평(시료 A)과 수직(시료 B)이 되도록 각각 인가함에 따라 열적안정성을 관찰하였다. 시료 A의 수직자성의 보자력이이 $300^{\circ}C$에서 1 KOe로 유지되어 시료 B의 열적안정성 보다 훨씬 우수하였다.

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A Study on the Feasibility Evaluation for the Use of Solar Photovoltaic Energy in Korean Peninsula Using a Satellite Image Forecasting Method (인공위성영상 예측기법을 적용한 태양광에너지 이용가능성 평가에 관한 연구)

  • Jo, Dok-Ki;Kang, Young-Heack;Auh, Chung-Moo
    • Journal of the Korean Solar Energy Society
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    • v.25 no.2
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    • pp.9-17
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    • 2005
  • Images taken by geostationary satellite may be used to estimate solar irradiance fluxes at earth's surface. It is based on the empirical correlation between a satellite derived cloud index and the irradiance at the ground. For the validation, estimated solar radiation fluxes are compared with observed solar radiation fluxes at 16 sites over the Korean peninsular from January 1982 to December 2004. Estimated solar radiation fluxes show reliable results for estimating the global radiation with average deviation of -7.8 to +7.0% from the measured values and the yearly averaged horizontal global insolation of Korean peninsula was turned out to be $3.56kW/m^{2}/day$.

A Study on Estimating Solar Radiation in Relation to Meteorological Parameters (기상매개변수와의 상관관계에 의한 일사예측에 관한 연구)

  • Jo, Dok-Ki;Kang, Young-Heack
    • Journal of the Korean Solar Energy Society
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    • v.28 no.3
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    • pp.1-6
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    • 2008
  • It is necessary to estimate empirical constants in order to predict the monthly mean daily global radiation on a horizontal surface in the developing areas for alternative energy. Therefore many different equations have proposed to evaluate them for certain areas. In this work a new correlation has been made to predict the solar radiation for any areas over Korea by calculating the regression models taking into account latitude, percentage of possible sunshine, and cloud cover. Results clearly demonstrates the reliability of the single linear equation for the estimation of global radiation, which is proposed by using percentage of possible sunshine method. When compared with the measured values, the average annual deviation falls between -3.1 to +0.6%.