• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.51-56
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• 2008

Since the direct normal insolation is a main factor for designing any solar thermal power system, it is necessary to evaluate its characteristics all over the country. We have begun collecting direct normal insolation data since December 1992 at 16 different locations and considerable effort has been made for constructing a standard value from measured data at each station. KIER(Korea Institute of Energy Research)'s new data will be extensively used by solar thermal concentrating system users or designers as well as by research institutes. From the results, we can conclude that 1) Yearly mean $2.67\;kWh/m^2/day$ of the direct normal insolation was evaluated for all days all over the 16 areas in Korea. 2) All day's direct normal insolation of spring and summer were $2.91\;kWh/m^2/day$ and $2.23\;kWHm^2/day$, and for fall and winter their values were $2.78\;kWh/m^2/day$ and $2.77\;kWh/m^2/day$ respectively. So, spring, fall and winter were higher, and summer was lower than the yearly mean value.

• Journal of the Korean Solar Energy Society
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• v.39 no.4
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• pp.11-24
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• 2019

The total solar irradiation on horizontal surfaces is separated into the beam and diffuses components. Although horizontal global irradiance is a commonly measured parameter for many sites, horizontal diffuse irradiance is not so readily obtainable. For such sites that measure global irradiation alone, a simple but reasonably accurate method is required to estimate diffuse irradiance from its global counterpart. This study investigates the applicability of correlation coefficients models correlating hourly diffuse and beam fraction and hourly clearness index in Daejeon. The three diffuse to global correlation coefficients models (Orgill and Holland model, CIBSE Guide J model, and Erbs et al. model) are selected and the three modified beam to global correlation coefficients models are generated. MBE, RMSE, r-squared of Daejeon and Daejeon boundary site-fitted models are compared with the case of original coefficients. The comparison result shows that the beam and diffuse to global solar irradiation correlation coefficients models with boundary site-fitted coefficients are best suitable for Daejeon. Further researches will be conducted to find the boundary site-fitting method using measured data of other cities and correlation coefficients models using solar altitude, cloud cover, and sunshine duration.

• Korean Journal of Remote Sensing
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• v.36 no.3
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• pp.411-423
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• 2020

Localized solar irradiance is normally derived from atmospheric transmission influenced by atmospheric composition and conditions of the target area. Specially, for the area with complex coastal lines such as Taean gun, the accurate estimation of solar irradiance requires for in depth analysis of atmospheric transmission characteristics based on the localized vertical profiles of the key atmospheric parameters. Using MODTRAN (MODerate resolution atmospheric TRANsmission) 6, we report a computational study on clear day atmospheric transmission and direct solar irradiance estimation of Taean gun using the data collected from 3 ground stations and radiosonde measurement over 93 clear days in 2018. The MODTRAN estimated direct solar irradiance is compared with the measurement. The results show that the normalized residual mean (NRM) is 0.28 for the temperature based MODTRAN atmospheric model and 0.32 for the pressure based MODTRAN atmospheric model. These values are larger than 0.1~0.2 of the other study and we understand that such difference represents the local atmospheric characteristics of Taean gun. The results also show that NRM tends to increase noticeably in summer as the temperature increases. Such findings from this study can be very useful for estimation and prediction of the atmospheric condition of the local area with complex coastal lines.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1998.10a
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• pp.55-62
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• 1998

온실내에서 직달 및 산란일사의 투과율은 온실이 설치된 지역의 위도, 온실의 동방위 및 형상, 피복재의 광학적 특성, 년중일수, 기상 조건, 지붕면의 경사각 뿐만 아니라 온실의 길이, 구조물의 크기 등에 따라 달라질 수 있다. 현재 국내의 기상 조건에 적합한 표준형 유리온실의 설계 기준이 부분적으로 제시되고 있으나, 온실내의 광환경과 관련된 설계 기준은 제시되지 않고 있는 실정이다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.400-401
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• 2000

황사는 대개 봄철 중국 대륙이 건조해지면서 중국 북부 사막 등의 흙먼지가 강한 상승기류를 타고 편서풍을 따라 우리 나라까지 날아오는 현상이다. 황사가 발생하면 시정이 떨어질 뿐 아니라 대기의 오염원으로 작용하여 질병을 유발시키기도 한다. 특히 황사로 인한 대기 중의 에어로졸 농도 증가는 지표에 도달하는 직달 일사량을 감소시켜 에어로졸의 광학적 두께에 영향을 준다. (중략)

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1998.05a
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• pp.27-32
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• 1998

국내에 보급되어 있는 유리온실은 네덜란드에서 수입된 벤로형(Venlo type or Dutchlite)과 벤로형에 비해서 동고가 높으며 온실 한 동의 폭이 상대적으로 큰 광폭형(widespan type)이 대부분을 차지하고 있다. 벤로형 은실의 측고는 3.5~4.0m로서 다소 차이가 있으나, 한 동의 폭과 지붕경사면의 길이가 일정하기 때문에 온실의 지붕경사각은 대부분 22$^{\circ}$를 나타낸다. (중략)

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.595-598
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• 2005

The thermal performance of glass evacuated tube solar collectors are numerically and experimentally investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are compared. Dealing with a single collector tube, the effects of not only the shapes of the absorber tube but also the incidence angle of solar irradiation (beam radiation) on thermal performance of the collector are studied. However the solar irradiation consists of the beam radiation as well as the diffuse radiation. Also, the interference of solar irradiation and heat transfer interaction between the tubes exist in an actual solar collector. These effects are considered in this study experimentally and numerically the accuracy of the numerical model is verified by the experimental results. The result shows that the thermal performance of the absorber used a plate fin and U-tube is the best.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.208-213
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• 2008

Since The measured solar radiation incident on tilted surfaces by all directions has been widely used as important solar radiation data in installing solar flat-plate collectors. To maximize the incident beam radiation, the slope, which is the angle between the plane of the surface in question and the horizontal, and the solar azimuth angles are needed for these solar thermal systems. This is because the performance of the solar thermal system is much affected by angle and direction of incident rays. Recognizing those factors mentioned above are of importance, actual experiment has been performed in this research to obtain the angle of inclination with which the maximum incident rays can be absorbed. The results obtained in this research could be used in installing optimal solar flat-plate collectors.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.161-166
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• 2008

The major purpose of this paper is to develop an uncertainty estimate for the calibration of thermopile instruments used to measure solar radiation parameters. We briefly describe the solar radiation parameters most often measured, instrumentation, reference standards, and calibration techniques. The bulk of the paper describes elemental sources of error and their magnitude. We then apply a standard error analysis methodology to combine these elemental error estimates into a statement of total uncertainty for the instrument calibration factor. Our results allow one to evaluate the accuracy of a radiometric measurement using thermopile instrumentation in the light of the application, such as engineering test evaluation or for validation of theoretical models.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.91-98
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• 1999

In order to reject the steady-state tracking error, it is common to introduce integral compensators in servosystems for constant reference signals. However, if the mathematical model of the plant is exact and no disturbance input exists, the integral compensation is not necessary. From this point of view, a two-degree-of-freedom(2DOF) servosystem has been proposed, in which the integral compensation is effective only when there is a modeling error or a disturbance input. The present paper considers a synthesis problems of this 32DOF servosystem with direct transfer term in the system representation. And, a method how we may obtain a gain such that desirable transient response is achieved, is proposed in the presence of the modelling error and disturbance input.