• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.425-429
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• 1990

In order to spread the practical utilization of solar energy, it depends upon how we can increase the efficiency of solar energy conversion system. This paper describes the method for calculating of optimal passive elements values in Maximum Solar Energy Tracking System. And experimental results with those calculated values are presented.

• 한국수소및신에너지학회논문집
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• 제23권5호
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• pp.503-512
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• 2012

There is a new power generation system such as direct coal fuel cell (DCFC) with a solid oxide electrolyte operated at relatively high temperature. In the system, it is of great importance to feed coal continuously into anodic electrode surface for its better contact, otherwise it would reduce electrochemical conversion of coal. For that purpose, it is required to improve the electrochemical conversion efficiency by using either rigorous mixing condition such as fluidized bed condition or just by recirculating coal particle itself successively into the reaction zone of the system. In this preliminary study, we followed the second approach to investigate how significantly particle recycle would affect the coal conversion efficiency. As a first phase, coal conversion was analyzed and evaluated from the thermochemical reaction of carbon with air under particle recirculating condition. The coal conversion efficiency was obtained from raw data measured by two different techniques. Effects of temperature and fuel properties on the coal conversion are specifically examined from the thermochemical reaction.

• 조명전기설비학회논문지
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• 제18권2호
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• pp.142-149
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• 2004

본 논문은 바람으로부터 최대출력을 추출하기 위해 계통연계 풍력발전시스템의 신경회로망 제어기와 추출된 최대출력을 계통에 전달하기 위한 전력제어기를 제안한다. 유도발전기, 변압기, 정류기 및 인버터 등으로 구성된 제어기를 갖춘 풍력발전시스템의 모델링과 시뮬레이션에 대해 검토하고자 한다. 본 논문에서는 동특성해석을 위해 드라이브 트레인 모델, 유도발전기 모델과 계통접속 모델을 제시한다. 신경회로망 제어기는 풍차날개의 피치각을 제어하여 바람으로부터 최대출력을 추출한다. 피치제어방법은 기계적으로 복잡하지만 제어성능은 스톨제어보다 우수하게 된다. MATLAB으로 수행한 시뮬레이션 결과는 발전기 토오크, 발전기 회전속도, 피치각, 계통으로 주입되는 유효/무효전력 등을 예시하고 있으며 그 결과를 보면 제안된 제어기의 효용성을 입증할 수 있다.

• 한국수소및신에너지학회논문집
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• 제26권5호
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• pp.469-476
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• 2015

The purpose of this work is to investigate main factors to design a solid-state hydrogen stroage system with magnesium hydride with 10 wt% graphite using numerical simulation tools. The heat transfer characteristic of this material was measured in order to perform the highly reliable simulation for this system. Based on the measured effective thermal conductivity, a transient heat and mass transfer simulation revealed that the total performance of hydrogen storage system is prone to depend on heat and mass transfer behaviors of hydrogen storage medium instead of its inherent kinetic rate for hydrogen adsorption. Furthermore, we demonstrate that the thermodynamic aspect between equlibrium presssure and temperature is one of key factor to design the hydrogen storage system with high performance using magnesium hydride.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.535-542
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• 2013

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor using bed inserts, effect of bed insert geometry on CO conversion of WGS catalyst was measured and investigated. Small scale fluidized bed reactor was used as experimental apparatus and tablet shaped WGS catalyst and sand particle were used as bed materials. The cylinder type and the spring type bed inserts were used to hold the WGS catalysts. The CO conversion of WGS catalyst with the change of steam/CO ratio was determined based on the exit gas analysis. Moreover, gas flow direction was confirmed by bed pressure drop measurement for each case. The measured CO conversion using the bed inserts showed high value comparable to previous results even though at low catalyst content. Most of input gas flowed through the bed center side when we charged tablet type catalyst into the cylinder type bed insert and this can cause low $CO_2$ capture efficiency because the possibility of contact between input gas and $CO_2$ absorbent is low in this case. However, the spring type bed insert showed good reactivity and good distribution of gas, and therefore, the spring type bed insert was selected as the best bed insert for SEWGS process.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2743-2750
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• 2011

Lanthanide(III)-cored complex as a wavelength conversion material has been successfully designed and synthesized for highly efficient dye-sensitized solar cells, for the first time, since light with a short wavelength has not been effectively used for generating electric power owing to the limited absorption of these DSSCs in the UV region. A black dye (BD) was chosen and used as a sensitizer, because BD has a relatively weak light absorption at shorter wavelengths. The overall conversion efficiency of the BD/WCM device was remarkably increased, even with the relatively small amount of WCM added to the device. The enhancement in $V_{oc}$ by WCM, like DCA, could be correlated with the suppression of electron recombination between the injected electrons and $I_3{^-}$ ions. Furthermore, the short-circuit current density was significantly increased by WCM with a strong UV light-harvesting effect. The energy transfer from the Eu(III)-cored complex to the $TiO_2$ film occurred via the dye, so the number of electrons injected into the $TiO_2$ surface increased, i.e., the short-circuit current density was increased. As a result, BD/WCM-sensitized solar cells exhibit superior device performance with the enhanced conversion efficiency by a factor of 1.22 under AM 1.5 sunlight: The photovoltaic performance of the BD/WCM-based DSSC exhibited remarkably high values, $J_{sc}$ of 17.72 mA/$cm^2$, $V_{oc}$ of 720 mV, and a conversion efficiency of 9.28% at 100 mW $cm^{-2}$, compared to a standard DSSC with $J_{sc}$ of 15.53 mA/$cm^2$, $V_{oc}$ of 689 mV, and a conversion efficiency of 7.58% at 100 mW $cm^{-2}$. Therefore, the Eu(III)-cored complex is a promising candidate as a new wavelength conversion coadsorbent for highly efficient dye-sensitized solar cells to improve UV light harvesting through energy transfer processes. The abstract should be a single paragraph which summaries the content of the article.

• 신재생에너지
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• 제7권2호
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• pp.10-17
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• 2011

Korea is the 11th largest energy consumption country and 96% of its total energy consumption depends on imports from overseas. Therefore it is a very important task to secure renewable energy sources which can reduce both the carbon-dioxide emission and dependency on overseas energy imports. Among the various renewable energy sources, organic wastes are important sources. In Korea, 113 million toe of methane is generated from organic wastes annually, but only 3.7% is effectively used for energy conversion. Thus, it is very important to make better use of organic wastes, especially for power generation. The goals of this project are to develope the fuel supplying system of Bio Gasturbine (GT) for 5MW-class co-generation system. The fuel supplying system mainly consists of $H_2S$ removal system, Bio Gas compression system, Siloxane removal system and moisture separating systems. The fuel requirement of 5MW-class GT is at around 60% of $CH_4$, $H_2S$ (<30 ppm), Siloxane(<10 mg/$nm^3$) and supply pressure (> 25 bar) from biogas compressor. Main mechnical charateristics of Bio Gasturbine system have the specific performance; 1) high speed turbine speed (12,840 rpm) 2) very clean emmission NOx (<50 ppm) 3) high efficiency of energy conversion rate. This paper focuses on the development of design technology for food waste biogas pretreatment system for 5MW-class biogas turbine. The study also has the plan to replace the fuel of gas turbine and other distributed power systems. As the increase of bioenergy, this system help to contribute to spread more New & Renewable Energy and the establishment of Renewable Portfolio Standards (RPS) for Korea.

• 설비공학논문집
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• 제23권8호
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• pp.543-548
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• 2011

New concept of wind energy conversion system is proposed to increase the energy density at a given working space. The quality of wind for wind power generation is depend on its direction and speed. However, the quality is not good on land because wind direction is changeable all the time and the speed as well. The most popularly operated wind turbine system is an axial-flow free turbine. But its conversion efficiency is less than 30% and even less than 20% considering the operating time. In this research, a cross-flow type wind turbine system is proposed with a convergent-divergent duct system to accelerate the low speed wind at the inlet of the wind turbine. Inlet guide vane is also introduced to the wind turbine system to have continuous power generation under the change of wind direction. In here, the availability of wind energy generation is evaluated with the change of the size of the inlet guide vane and the optimum geometry of the turbine impeller blade was found for the innovative wind power generation system.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
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• pp.79-79
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• 2011

The oceans are an untapped resource, capable of making a major contribution to our future energy needs. In the search for a non polluting renewable energy source, there is a push to find an economical way to harness energy from the ocean. Tidal stream is one of ocean energy form that is being investigated as potential source for power generation. Tidal current turbines are therefore designed as conversion machinery to generate power from tidal currents. A study on energy extraction from tidal currents is presented in this paper.

• 한국수소및신에너지학회논문집
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• 제17권3호
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• pp.293-300
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• 2006

KIER has been developing a Ru-based preferential oxidation catalysts and a novel fuel processing system to provide hydrogen rich gas to residential PEMFCs system. The catalytic activity of Ru-based catalysts was investigated at different Ru loading amount and different support structure. The obtained result indicated that 2 wt% loaded Ru-based catalyst supported on ${\alpha}-Al_2O_3$ showed high activity in low temperature range and suppressed the methanation reaction. The developed prototype fuel processor showed thermal efficiency of 78% as a HHV basis with methane conversion of 92%. CO concentration below 10 ppm in the produced gas is achieved with separate preferential oxidation unit under the condition of $[O_2]/[CO]=2.0$. The partial load operation have been carried out to test the performance of fuel processor from 40% to 80% load, showing stable methane conversion and CO concentration below 10 ppm. The durability test for the daily start-stop and 8 h operation procedure is under investigation and shows no deterioration of its performance after 50 start-stop cycles. In addition to the system design and development.