This paper compares the operation characteristics of PV(Photovoltaic) system by computer simulation with those of real PV system and the operation characteristics of PV system by computer simulation are evaluated and analyzed considering system parameters of specifications, installation and surrounding conditions etc. From the basis of these results, this study will intend to develop an evaluation, analysis tool and construct database for optimal design of PV system.

Absorption potential of desiccant solution significantly decreases after absorbing moisture from humid air, and a regeneration process requires a great amount of energy to recover absorption potential of desiccant solution. In an effort to develop an energy efficient regenerator, this study examines a regeneration process using hot air heated by solar radiation to recover absorption potential by evaporating moisture in liquid desiccant. More specifically, this study is aimed at finding the optimum operating condition of the regenerator by utilizing a well-established statistical tool, so-called response surface methodology(RSM), which may provide a functional relationship between independent and dependent variables. It is demonstrated that an optimization model to find the optimum operating condition can be obtained using the functional relationship between regeneration rate and affecting factors which is approximated on the basis experimental results.

This study deals with the collection of solar energy and its storage in evacuated tubular collector systems for different types of header design, flow passage and heat transfer devices. In order to elicit the most efficient combination of header design, flow passage, heat transfer hardware and operating conditions, a series of tests were done for the four different types of solar collectors utilizing vacuum tubes. The systems studied here either has the evacuated collector tubes with a metal cap on one end or the all-glass evacuated solar collector tubes These evacuated tubular collectors are known to be more efficient than the flat-plate ones in both direct and diffuse solar radiation. Test results show that the system comprised of the all-glass evacuated tubes with U-shaped copper pipes inside outperforms the other configurations. Especially, a rolled copper sheet tightly placed along the inner surface of each inner tube enhances heat transfer between the heated collector surface and the water contained in the U-shaped copper pipe.

The purpose of this study is to procure basic data to be used for solar power plant and concentrating collector designs. Site elevation is one of the major factors which influences the incoming insolation to the earth surface. Because the nonpermanent gases such as ozone, water vapor are unmixed components of the atmosphere and their concentrations are the function of height, the site elevation effects the relative proportion of the atmospheric constituents. We have measured solar radiation on Jiri Mt. (1,400m) and in Gurye area(115m) at the near same latitude. These values were then compared to obtain their characteristics and to investigate the potential for the solar utilization for both high and low elevated areas. From the experimental results, we concluded that 1) Daily mean horizontal global radiation and normal beam radiation on Mt. Jiri are 9.5%, and 35.3% higher than Gurye area respectively for a clear day. 2) A significant difference in atmospheric clearness index is observed between Mt. Jiri and Gurye areas.

Generator for wind power can be either synchronous or asynchronous (induction) types. Induction and synchronous generators behave in a different way when subjected to severe faults. Induction generators does not have an angle stability limit and short circuit in the neighborhood of an Induction generator causes the demagnetization of the machine when the fault is cleared, the voltage raises slowly, while the grid contributes with reactive power to the generator and the magnetic flux recovers. On the other hand in the synchronous generators the recovery of the voltage is immediate, since the excitation of the rotor angle comes from an independent circuit. This paper shows the result of the transient state analysis in the network connected to wind generation system Several case studies have been conducted to determine the effect of the clearing time of a fault on the network stability. It has been found that the critical clearing time can be as low as 61ms in the case of induction generator compared to 370ms in the case of synchronous generator.

This paper presents the modeling and analysis of V47-660 kW wind turbine generation system(WTGS) in Jeju wind farm using Psim program. Generally, WTGS is composed of complicated machinery. So it is very difficult to present the mathematic model. This means that WTGS has a nonlinear system. Using the real output data from V47 WTGS for one year, it is simply possible to express the rotor and gear coupling system as a torque generator according to wind speed. Also, the modeling of electrical system can be able to present using the data sheet from the company. To analyze the proposed method, results of computer simulation using Psim program are presented to support the discussion.

This paper presents a study on the power factor improvement of V47- 660 [kW] Wind Turbine Generation System (WTGS) in Jeju wind farm, as a model system in this paper. In this system, the power factor correction is controlled by the conventional method with power condensor banks. Also, this system has only four bank steps, and each one capacitor bank step is cut in every one second when the generator has been cut in. This means that it is difficult to compensate the reactive power exactly according to the variation of them. Actually, model system has very low power factor in the area of low wind speed, which is almost from 4 to 6 [m/s]. This is caused by the power factor correction using power condenser bank. To improve the power factor in the area of low wind speed, we used the static var compensator(SVC) using current controlled PWM power converter using IGBT switching device. Finally, to verify the proposed method, the results of computer simulation using Psim program are presented to support the discussions.

This paper represents the effect of rotor geometry on the performance of a small-scale Wells turbine for wave energy conversion. In this study, four kinds of blade profile were selected from previous studies with regard to the blade profile of the Wells turbine. The experimental investigations have been performed for two solidities by model testing under steady flow conditions, and then the effect of blade profile on the running and starting characteristics under sinusoidal flow conditions have been investigated by a numerical simulation using a quasi-steady analysis. In addition, the effect of sweep on the turbine characteristics has been investigated for the cases of CA9 and HSIM 15-262123-1576. As a result, a suitable choice of these design factors has been suggested.

According to the recent report, the lighting energy consumption of commercial buildings reaches to $30%\sim40%$ of the total energy consumption. It is more than that of cooling & heating energy consumption and it is the major target of energy-saving policy. It is obvious that they are interested in natural lighting device such as Light-shelf for the purpose of raising the lighting energy-saving efficiency. In most of highly developed countries, a thorough study on Light-shelf makes it possible to propose a practical plan while at home there leaves much to be desired to study a guiding principle of optimum plan in spite of its efficiency based on experiments using scale4 model and analysis of simulation. Aiming at making an optimum plan of Light-shelf suitable for the domestic situation, this study is worked by experiments using light-shelf and analysis of variables using illumination program. The experiments is to analyse the efficiency of Light-shelf on condition of the sky and the analysis is to make the simulation using illumination program. This study is composed of 1) the analysis of light with some variables such as presence of light-shelf and degree of angle using 1/2 scaled model 2) making the simulation using Lightscape, illumination program, In brief, concerning presence of light-shelf, it causes little difference in its efficiency in the overcast sky, whereas it decreases an illuminance of window side and provides inner side with the light, which decreases the ratio of the maximum to the minimum inner illuminance and makes the inner of illuminance to range evenly in the clear sky. On degree of angle, as the daylight increases in proportion of degree of angle, the ratio of the maximum to the minimum inner illuminance decreases, which makes it possible to increase the proportion of inner daylight.

The purpose of this study was to analyze daylighting performance in a semi-infinite size office space for lighting energy conservation. DOE2.1E was used for simulations for the model space of $12\times12\times2.6m$. Nomographs were developed which could simulate work plane illuminance, glare index, energy consumption rate and energy reduction rate for daylighting design. Major results of simulations are as follows ; 1) When blinds facing south were installed, 43% of workplane illuminance diminished, but the flare index didn't exceed the recommended max-glare value. 2) In a semi-infinite office space facing south. energy consumption rate in the case space of 500 lux workplane illuminance is larger then case space of 300 lux workplane illuminance. Therefore, energy reduction rate is increased when the semi-infinite office faces south and naintains 300 lux workplane illuminance level.

본 연구에서는 복층으로 구성된 $WSio_2Al$ 금속절연체의 상세를 보여주고 있는데, 금속과 절연체의 합성물질은 태양 흡수율의 설계와 열적인 현상을 보여주기 위해 종종 사용된다. 금속의 접착기면 위에 얇은 복층 코팅으로 구성되는 디자인은 태양 스펙트럼의 파장권역에서 선택적 흡수를 위함이다. 본 연구는 태양 복사의 열성능 평가를 위해 금속과 절연체 필름의 방사율, 태양흡수율, 코팅순서, 미 반사층(AR)의 두께, 코팅 두께와 코팅 면수, 전체 코팅 두께 등에 대해 시뮬레이션 하였다. 그 결과 네 겹의 코팅설계에서 $Sio_2AR$ 75 nm 두께와 각각의 층에서 $0.5\sim0.7$의 가변 금속부분 구성이 가장 우수한 성능을 갖는 것으로 나타났다. 또한 시뮬레이션으로 금속과 절연체 합성물의 최적의 구성과 각각의 코팅 두께에 대한 예측이 가능했으며, 최대 태양흡수율은 0.94, 방사율은 0.115의 금속과 절연체의 합성물을 구성할 수 있었다.

One of the promising optical daylighting systems is light shelf type daylighting system, Two types of lighting performance analysis methods are 1) Ray-Tracing method and 2) Radiosity method. The purpose of this paper is to compare two methods in terms of advantages and disadvantages by further looking at the detail algorithm. Also. model verification with Lightscape simulations has been conducted. Effectiveness of light penetration factor in terms of daylighting factor has been investigated and quantified. In summer time. the performance of the light shelf was twice better than the case without it.