• 대한설비공학회지:설비저널
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• 제14권3호
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• pp.187-199
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• 1985

The low-temperatured radiant heating System like a panel heating system is recognized as nice means to make comfortable indoor environment. Perhaps, 'Ondol' would be a typical example of the Panel heating system. Nevertheless. Occupants in a radiantly heated Space which has an asymmetric radiant field may feel thermally discomfort due to the asymmetric radiation. The aim of this Study is to suggest the fundamental technical data for establishing Standards of thermally comfortable environment when designing a radiant heating System. Thermal distribution of indoor environment and the skin temperature of the occupants were measured at experimental room in KIER (Korea Institute of Energy and Resources). Whole/Regional thermal and comfort Sensation votes of the occupants were taken simultaneously in order to investigate the relationships between thermal environmental factor and the occupants' responses. The effect of an asymmetric radiation on thermal environment and the occupants' responses was analyzed by using a v.r.t.(vector radiant temperature). By this means, the thermally neutral limits for the ambient air temperature and the floor surface temperature by the occupants' responses were Obtained. And the recommended temperature limits of the indoor surface were derived from the experimental work and the theory of radiant and will provide thermal neutrality for man without any discomfort on the part of the body.

• 한국표면공학회지
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• 제56권6호
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• pp.427-436
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• 2023

In the industry, it is recognized that human activities significantly lead to a large amount of wastewater, mainly due to the increased use of water and energy. As a result, the growing field of wastewater resource technology is getting more attention. The common technology for hydrogen production, water electrolysis, requires purified water, leading to the need for desalination and reprocessing. However, producing hydrogen directly from wastewater could be a more cost-effective option compared to traditional methods. To achieve this, a series of first-principle computational simulations were conducted to assess how waste nutrient ions affect standard electrolysis catalysts. This study focused on understanding the adsorption mechanisms of byproducts related to the oxygen evolution reaction (OER) in anion exchange membrane (AEM) electrolysis, using Co₃O₄ as a typical non-precious metal catalyst. At the same time, efforts were made to develop a comprehensive free energy prediction model for more accurate predictions of OER results.

• Current Photovoltaic Research
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• 제12권2호
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• pp.41-47
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• 2024

CIGS solar cells are thin film solar cells that have excellent light absorption coefficient and can be manufactured with high efficiency through the use of low materials. In Korea, they must pass KS certification for home and commercial installation. KS C 8562 is a standard for evaluating the durability of CIGS and thin film amorphous silicon solar modules and deals with contents such as light, temperature, humidity, and mechanical durability. Unlike general crystalline silicon solar modules, the CIGS solar module has a different behavior of output change through these environmental tests, so if it shows 90% or more of the rated output suggested by the manufacturer after the final test, it is judged to be a suitable product. In this paper, the output before and after individual tests was measured through the test method of KS C 8562 to observe the output change and to discover the vulnerabilities of the CIGS solar module when exposed to various environments. Through this, it was confirmed that humidity exposure was the most vulnerable and that it had output recovery characteristics for light (visible light and ultraviolet rays). This study attempted to present the output behavior characteristics and data of the CIGS module at the time when the high efficiency thin film photovoltaic module market is expected to be created in the future.

• Current Photovoltaic Research
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• 제12권1호
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• pp.17-23
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• 2024

Photovoltaic (PV) power generation is the world's best and largest renewable energy that generates electricity with infinite sunlight. Solar cell modules are a component of photovoltaic power generation and must have a long-term durability of at least 25 years. The development of processes and equipment that can be recovered through the recycling of metals and valuable metals when the solar module's lifespan is over has been completed to the level of commercialization, but few processes have been developed that require repair due to initial defects. This is mainly due to the economic problems caused by remaking. However, if manufacturing processes such as repairing solar cell modules that have been proven to be early defects are established and the technical review of long-term reliability and durability reaches a certain level, it is considered that it will be a recommended process technology for environmental economics. In this paper, assuming that a defective solar cell module occurs artificially, a manufacturing process for replacement of solar cells was developed, and a technical verification of the manufacturing technology was conducted through long-term durability evaluation in accordance with KS C 8561. Through this, it was determined that remanufacturing technology for solar cell replacement of solar cell modules that occurred in a short period of time after installation was possible, and the research results were announced through a journal to commercialize solar modules using manufacturing technology in the solar market in the future.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.169.1-169.1
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• 2010

Geothermal heat pump(GHP)system has been extensively disseminated due to the recent increasing demand over new and renewable energy. However, the economics and system reliability has been key issues and barriers to insure a better system performance as designed originally. The building integrated designs of geothermal heat pump system are test and optimize GHP system by evaluating its performance in virtual reality. System design is an iterative process that will help optimize the cost efficiency of the system. One of the primary goals is to minimize the energy imbalance between the amount of energy extracted from the ground and the energy reject to it. This will reduce the land area required to install the GHX, reduce the cost of installing it and ensure the long-term efficiency of the system. Commissioning is the process of ensuring that are designed, installed, functionally tested, and capable of being operated and maintained to performance in conformity with design intent. In this paper, Study on introduction of Initial commissioning method of Geothermal Heat Pump(GHP) system using ISO performance data has been introduced. Also KIER GHP Simulator is used to simulate actual heat pimp operating condition and test commissioning method. Result should that the experiment data base could verify the applicability of the commissioning method, and also were able to suggest a better ways to GHP commissioning.

• Carbon letters
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• 제19권
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• pp.72-78
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• 2016

Spinnable pitches and carbon fibers were successfully prepared from petroleum or coal pyrolysis residues. After pyrolysis fuel oil (PFO), slurry oil, and coal tar were simply filtered to eliminate the solid impurities, the characteristics of the raw materials were evaluated by elemental analysis, ¹³C nuclear magnetic resonance spectrometer, matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS), and so on. Spinnable pitches were prepared for melt-spinning carbon fiber through a simple distillation under strong nitrogen flow, and further vacuum distillation to obtain a high softening point. Carbon fibers were produced from the above pitches by single-hole melt spinning and additional heat treatment, for oxidization and carbonization. Even though spinnable pitches and carbon fibers were processed under the same conditions, the melt-spinning and properties of the carbon fiber were different depending on the raw materials. A fine carbon fiber could not be prepared from slurry oil, and the different diameter carbon fibers were produced from the PFO and coal tar pitch. These results seem to be closely correlated with the initial characteristics of the raw materials, under this simple processing condition.

• 한국수소및신에너지학회논문집
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• 제17권1호
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• pp.69-74
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• 2006

Thick film $H_2$ sensors were fabricated using $SnO_2$ loaded with $Ag_2O$ and $PtO_x$. The composition that gave the highest sensitivity for $H_2$ was in the weight% ratio of $SnO_2 : PtO_x : Ag_2O$ as 93 : 1 : 6. The nano-crystalline powders of $SnO_2$ synthesized by sol-gel method were screen printed with $Ag_2O$ and $PtO_x$ on alumina substrates. The fabricated sensors were tested against gases like $H_2$, $CH_4$, $C_3H_8$, $C_2H_5OH$ and $SO_2$. The composite material was found sensitive against $H_2$ at the working temperature $130^{\circ}C$, with minor interference of other gases. The $H_2$ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on $SnO_2-Ag_2O-PtO_x$ system exhibited the high performance, high selectivity and very short response time to $H_2$ at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of $H_2$.

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.750-757
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• 2005

The objective of this study is an understanding of the effect of inlet flow angle on the output power performance of a Francis hydraulic turbine, An optimum induced angle at the inlet of the turbine is one of the most important design parameters to have the best performance of the turbine at a given operating condition, In general. rotating speed of the turbine is varied with the change of water mass flowrate in a volute, The induced angle of the inlet water should be properly adjusted to the operating condition to have maximum energy conversion efficiency of the turbine, In this study. a numerical simulation was conducted to have detail understanding of the flow phenomenon in the flow path and output power of the model Francis turbine. The indicated power produced by the model turbine at a given operating condition was found numerically and compared to the brake power of the turbine measured by experiment at KIER. From comparison of two results, turbine efficiency or energy conversion efficiency of the model turbine was estimated. From the study, it was found that the rotating power of the turbine linearly increased with the rotating speed. It means that the higher volume flow rate supplied. the bigger torque on the turbine shaft generated. The maximum brake efficiency of the turbine is around 46$\%$ at 35 degree of induced angle. The difference between numerical and experimental output of the model turbine is defined as mechanical efficiency. The maximum mechanical efficiency of the turbine is around 93$\%$ at 25$\∼$30 degree of induced angle.

• 멤브레인
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• 제21권2호
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• pp.141-147
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• 2011

바나듐 레독스-흐름 전지 (V-RFB)용 격막으로 사용하기 위해 폴리설폰(psf)에 폴리페닐렌설파이드설폰(PPSS)을 블록 공중합 시킨 폴리머와 여기에 TPA (tungstophosphoric acid)를 첨가하여 양이온교환막을 제작하였다. 제작한 막은 1M $H_2SO_4$용액을 사용하여 막 저항을 평가하였다. 제작한 Psf-PPSS와 Psf-TPA-PPSS 양이온교환막의 막 저항은 약 $0.94{\Omega}{\cdot}cm^2$를 나타냈다. 제작한 양이온교환막과 Nafion117을 격막으로 사용하여 V-RFB의 전기화학적 특성을 평가하였다. 4 A의 전류에서 측정한 V-RFB의 충 방전 셀 저항은 막의 종류에 따라 Nafion117 < Psf-TPA-PPSS < Psf-PPSS 의 순서로 값이 낮았다. 막을 5가 바나듐 수용액에 침적하여 침적시간 변화에 따른 V-RFB의 총 방전 셀 저항을 측정함으로써 내구성을 평가하였다. 내구성은 제작한 Psf-PPSS 막이 가장 우수하였으며, Nafion117막과 제작한 Psf-TPA-PPSS막이 서로 동등하였다.

• 한국가스학회지
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• 제10권2호
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• pp.14-21
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• 2006

다공성 중공사막 분리막 기액접촉기을 이용한 황산화물 제거장치를 제작하고 다양한 상용 분리막과 자체 제작한 분리막을 이용하여 황산화물 제거 성능 실험을 수행하였다. 분리막을 이용한 황산화물 제거 성능 평가 결과 대단히 우수한 제거효율을 보였다. 중공사막을 이용하여 $SO_2$를 제거할 경우에 액막 저항을 낮출 수 있는 흡수제와 첨가제의 선정, 막 재질, 막 제조조건 등이 최적의 G-L Contactor개발에 중요한 변수로 나타났다. 향후 보다 소형화되고, 경제적이며 효율이 우수한 G-L Contactor System 개발에 대한 연구를 진행할 것이다.