• 신재생에너지
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• 제10권3호
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• pp.39-46
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• 2014

The performances of three different types of photovoltaic (PV) module technologies namely, copper-indium-diselenide (CIGS), mono-crystalline silicon (mo-Si) and amorphous silicon (a-Si) have been comparatively studied in the grid-connected system for more than a year under the tropical monsoon climate of Thailand. The yields, performance ratios and system efficiencies for the respective PV module technologies have been calculated and a comparison is presented here. The performance ratios of the initial operation year for CIGS showed highest among the compared technologies under Thailand climate conditions by marking 97.0% while 89.6% for a-Si and 81.5% for mo-Si. Although mo-Si has shown highest efficiencies all over the period, under the testing conditions, the operating efficiency of mo-Si was down-graded from its reference value mainly due to high operating temperature and the efficiency of the tested CIGS module was also found as high as that of mo-Si in the study. Accordingly, outdoor assessment shows that CIGS modules have demonstrated high performance in terms of yields and performance ratios in Thailand climate conditions.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.396-401
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• 1995

Epoxy coated reinforcing steels (ECRs) were acquired from ten sources and coatings from each source were initially characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in three aqueous solutions at elevated temperature (8$0^{\circ}C$) and in chloride-contaminated concrete slabs under outdoor exposure, It was found that the density and size of coating defects was the promary factor affecting ECR performance. The equivalent circuit analysis using electrochemical impedance spectroscopy (EIS) data indicated that the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here. Experimental results also indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment

• 한국환경과학회지
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• 제25권7호
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• pp.951-961
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• 2016

To prevent increasing instances of heat-related illnesses due to heat waves generated by climate change, a customized thermal environment index should be developed for outdoor workers. In this study, we conducted sensitivity analysis of the Masan harbor during a heat wave period (August 9th to 15th, 2013) using the MENEX model with metabolic rate and clothing-insulation data, in order to obtain realistic information about the thermal environment. This study shows that accurate input data are essential to gather information for thermophysiological indices (PST, DhR, and OhR). PST is sensitive to clothing insulation as a function of clothing. OhR is more sensitive to clothing insulation during the day and to the metabolic rate at night. From these results, it appears that when exposed to high-temperature thermal environments in summer, wearing highly insulated clothing and getting enough rest (to lower the metabolic rate) can aid in preventing heat-related illnesses. Moreover, in the case of high-intensity harbor work, quantification of allowed working time (OhR) during heat waves is significant for human health sciences.

• 한국농촌건축학회논문집
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• 제19권1호
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• pp.23-34
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• 2017

The purpose of this paper is to suggest the preliminary data for the improvement of the senior centers' indoor environment and the upcoming progress located in rural areas. In wanju county, 81.8% of seniors were enrolled in senior centers, and used the facility everyday. Also, most of the users tended to use the facilities between 12 a.m. and 6 p.m. The majority of users had lunch at the senior centers. The facilities of most senior centers were in poor condition, and some had their restroom outdoor. Also, most senior centers are exposed to high concentrations of carbon dioxide during winter. During this season, the thermal environment in the restroom was bad. However, the users' level of the facilities' satisfaction was positive. Senior centers have been operating the facilities with difficulties, due to the low financial support from the local autonomous organization. The indoor temperature in most centers, especially, was above $30^{\circ}C$ during summer on account of lack of funding for airconditioning. Therefore, it could be recommended that the local autonomous entity start regular check-ups and repairs for the poor indoor environment and facilities, with more financial support and active supervision of the management.

• 한국멀티미디어학회논문지
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• 제23권11호
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• pp.1383-1387
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• 2020

Recently, a 4-col 7-row LED Screen that provides various information of major roads and local governments has been installed and operated. However, due to deterioration due to changes in temperature and humidity, deterioration due to static electricity, and mechanical stress, partial module failure of the display may occur, which is a major cause of missing information of vitally given to citizens. However, there have been frequent cases where the 4-col and 7-row LED Screen that have failed due to reasons such as installed location where the signboards are installed on the road and outdoor, the lack of monitoring means at all times, and the lack of manpower is often neglected for a long time. Following this flow, this paper proposes a method to detect defective modules by analyzing the images collected through the camera fixed to the front part of the LED display.

• Architectural research
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• 제19권3호
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• pp.71-77
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• 2017

Dynamic pricing refers to a system in which a tariff varies, according to a level of charging and applied time depending on time change. The power billing system used in the Korean Electric Power Corporation (KEPCO) is based on time of use (TOU) pricing, which is one of the dynamic pricing systems. This paper aimed to determine the operational results of a variable refrigerant flow system, to which a new control algorithm was applied, in order to respond to dynamic pricing, in summer and the utility of the new control. To do this, real measured data was acquired from a VRF system installed in a building for educational purposes, where dynamic pricing was applied for about 100 days during summer time. At the maximum load operation time period in TOU, the new control minimized operation within the indoor comfort range, an increase in refrigerant evaporation temperature in the indoor unit and the number of revolutions in a compressor in the outdoor unit was limited. As a result, power usage was decreased by 11%, and the operational cost by 14.6%. Furthermore, measurement results using the Predicted Mean Vote (PMV) model, that represented satisfaction of thermal environment, showed that 82.8% to 90.4% of the occupants of the building were satisfied during operation when the new control was applied.

• 한국농공학회논문집
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• 제54권2호
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• pp.55-65
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• 2012

In the winter season, when the ventilation system is operating, the fresh cold air from the slot-type openings of broiler house which directly reached the animal zone can cause various problems such as thermal stress, decreasing of feed and water consumption, occurrence of respiratory disease, and etc. Therefore it is very important to control the trajectory of aero-flow from the slot openings to induce an efficient thermal heat change. Jet-drop distance model was proposed to predict and control the jet-trajectory. However their study was restricted due to the small scaled model and difficulties of measuring the Jet-drop distance. In this study, CFD was applied to analyze qualitatively and quantitatively the jet-drop distance in a real broiler house. The various variables were considered such as installed slot-angle, designed ventilation rate, and the outdoor ambient temperature. From the present study, two linear-regression models using the Jet-drop factor and corrected Archimedes number, and their R-squared values 0.744 and 0.736, respectively, were used. From this study, the applicability of CFD on the analysis of Jet-drop distance model was confirmed.

• KIEAE Journal
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• 제16권1호
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• pp.11-19
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• 2016

Purpose: PMV, PET, and similar thermal comfort indices and microclimate modeling have recently become actively used to evaluate thermal comfort. This study will look at pedestrian roads with diverse spatial characteristics on university campus using the ENVI-met model as the base for onsite measurement. Method: The PET was used as the thermal comfort index. The first microclimate measures were collected on September 20, 2014, and the second microclimate measures were collected on June 1, 2015. The ENVI-met model was used at the same time. Result: As a results, Onsite measurement results differed depending on the PET spatial characteristics. The location associated with the most discomfort had a PET of $47.8^{\circ}C$. The spatial characteristics of this place included a with no shade. The most comfortable location had shade, and the PET was $24.6^{\circ}C$. When the ENVI-met model and onsite measurements were compared, similar patterns were found, but with a few differences at specific points; this was due to the limitation of using input materials such as trees, buildings, and covering materials with the ENVI-met model. This factor must be thoroughly considered when analyzing modeling results.

• 한국태양에너지학회 논문집
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• 제30권4호
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• pp.22-28
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• 2010

This study analyzed the performance of passive solar system for office building. A unit model of the passive solar system was proposed in order to predict its performance under varying parameters and Seoul weather date. Steady state heat transfer equations were set up using a energy balanced equations and solved using a inverse matrix method. Numerical simulation program to analyze system was developed by using MATLAB. As the results, the passive solar system performance of office building was determined by the insolation and the outdoor air temperature. Also the passive solar system indicate 6.7~16.2% of annual average efficiency. In the comparison with other systems of the conventional wall, mass wall could reduce the heating loads of 7.1% and trombe wall could reduce heating loads of 11.5%. Through this study, performance of passive solar system for office building was verified by numerical method. Consequently, the passive solar system could operate an important role as the alternative for saving energy consumption of office building, and the additional studies should be made through the experimental method for the commercialization.

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.147-152
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• 2008

This paper has been fabricated the two different type of variable attenuators using a characteristics of a 3 dB directional coupler and pin diodes. One was not analyzed using the conventional even-odd modes but used simple two-port techniques. The resulting scattering parameters described operation characteristics for the general case where the terminating impedances are equal and unequal. After analyzing resistor role of the ${\pi}$ type fixed attenuator. this paper used a pin diode instead of a resistor. The variable attenuators were fabricated using pin diodes for current-controlled attenuation on the coupled ports of a 3 dB branch-line coupler and ${\pi}$ type fixed attenuator. The realized variable attenuators have more than 33 dB attenuation ranges at 2.1 GHz. and the input and output reflection coefficients are less than -13 dB. These results could be applied to mobile communication systems. It can be varied gain of the power amplifier according to change a outdoor environmental temperature and improved linearity.