• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1596-1597
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• 1998

This study is an experiment using the non-thermal plasma for removal of NOx, SOx. This experimental setup is made up the superposing discharge electrode in order to increase the removal. Both electrode are plate and niddle electrode, back of plate installed the lower electrode making pure silver. The result of the superposing discharge is thought that the rate of removal increase by means of rising effect. This is studied the property to the U.V irradiation and temperature dependence of the flue gas.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.93-98
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• 1998

Magnetic fluids have been used in the commercial area, e. g damping, sealing and hydrodynamic bearing. In this study, magnetic fluid was made for damping in loudspeaker. The magnetic fluids were snthesized by dispersing the magnetite powder which was obtained by precipitation method in Yubase oil. When the magnetic fluid was applied to a 6 cm tweeter, improvements of damping, centering and heat transger in a loudspeaker were noted. Also we compared the performance of the magnetic fluid with 20 % magnetite in the oil and the one of APG-815 (Niphon Ferrofluidic Co.)

• Korean Journal of Optics and Photonics
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• v.30 no.2
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• pp.37-47
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• 2019

A reflecting omnidirectional optical system with four spherical and aspherical mirrors, for use with long-wavelength infrared light (LWIR) for night surveillance, is proposed. It is designed to include a collecting pseudo-Cassegrain reflector and an imaging inverse pseudo-Cassegrain reflector, and the design process and performance analysis is reported in detail. The half-field of view (HFOV) and F-number of this optical system are $40-110^{\circ}$ and 1.56, respectively. To use the LWIR imaging, the size of the image must be similar to that of the microbolometer sensor for LWIR. As a result, the size of the image must be $5.9mm{\times}5.9mm$ if possible. The image size ratio for an HFOV range of $40^{\circ}$ to $110^{\circ}$ after optimizing the design is 48.86%. At a spatial frequency of 20 lp/mm when the HFOV is $110^{\circ}$, the modulation transfer function (MTF) for LWIR is 0.381. Additionally, the cumulative probability of tolerance for the LWIR at a spatial frequency of 20 lp/mm is 99.75%. As a result of athermalization analysis in the temperature range of $-32^{\circ}C$ to $+55^{\circ}C$, we find that the secondary mirror of the inverse pseudo-Cassegrain reflector can function as a compensator, to alleviate MTF degradation with rising temperature.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.186-193
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• 2017

Microwave (MW) is an effective method for solubilizing organic solids because it has thermal, non-thermal and ionic conduction effects by dielectric heating and high energy efficiency. In this study, we evaluated the application of MW to the solubilization of cattle manure and investigated the solubilization ratio of cattle manure by solid concentration, MW power and target temperature. And $H_2SO_4$ and NaCl were added to investigated the effects on the MW-assisted solubilization. Also, we evaluated the solubilization efficiency by biochemical methane potential(BMP) test according to the solubilization conditions. Maximum SCOD increment per energy supply was 70.5 mg $SCOD_{increased}/kJ$ at 12% of the solid concentration, MW power of 800 W and the target temperature of $40^{\circ}C$. And SCOD concentration went up 153.2% compared to the initial concentration. In the MW-assisted solubilization with $H_2SO_4$ and NaCl as chemical catalysts, SCOD concentration was increased by 36% and 22.7%, respectively, compared to the result of MW. The methane production was increased by 13.3% and 11.3% with the addition of $H_2SO_4$ and NaCl. Therefore, MW is an effective method for solubilization of cattle manure, and it is necessary to use chemical catalysts to increase the solubilzation efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.75.2-75.2
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• 2011

고온고압에서 운전되는 IGCC용 분류층 석탄가스화기는 석탄에 포함된 회 성분을 대부분 용융 슬래그 형태로 가스화기 벽을 타고 흘러내리게 하여 가스화기 하부로 배출시킨다. 이러한 용융 슬래그를 원활하게 배출시키는 것은 가스화기의 안정적인 운전에 있어서 매우 중요하다. 본 연구에서는 슬래그 층 내의 물질수지, 운동량 및 에너지 보존을 고려하여 석탄가스화기내의 슬래그 거동을 해석할 수 있는 모델 식을 유도하였다. 유도된 슬래그 거동 모델 식들을 적용하고 가스화기의 형상을 고려하여 가스화기 내부에서의 슬래그 거동을 해석하였다. 또한 슬래그 물성치들인 슬래그 점도, 슬래그 비열, 슬래그 밀도, 슬래그 열전달 계수 등을 슬래그의 조성 변화에 따라 별도로 산정하여 슬래그 해석의 입력 데이터로 사용하였다. 슬래그에 첨가되는 석회석의 비율을 해석의 주요 변수로 사용하여 가스화기 하부에서 용융 슬래그 및 고체 슬래그 두께, 용융 슬래그 층 내부에서의 슬래그 점도분포 및 슬래그 속도분포 등 슬래그 거동의 주요 특성들을 예측하였다. 해석결과로 석탄에 석회석의 첨가량을 증가시키면 슬래그의 임계점도온도(temperature of critical viscosity)와 점도가 낮아지므로 가스화기 벽면에서의 용융 슬래그의 유동속도는 빨라지며, 고체 슬래그와 용융 슬래그의 두께가 감소하는 것을 정량적으로 확인할 수 있었다.

• Fire Science and Engineering
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• v.24 no.2
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• pp.106-113
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• 2010

Fire characteristics can be analyzed more realistically by using more accurate material properties related to the fire dynamics and one way to acquire these fire properties is to use one of the inverse property analyses. In this study the genetic algorithm which is frequently applied for the inverse heat transfer problems is selected to demonstrate the procedure of obtaining fire properties of the solid charring material with relatively simple chemical structure. The thermal decomposition on the surface of the test plate is occurred by receiving the radiative energy from external heat sources, and in this process the heat transfer through the test plate can be simplified by an unsteady 1-D problem. The inverse property analysis based on the genetic algorithm is then applied for the estimation of the properties related to the reaction pyrolysis. The input parameters for the analysis are the surface temperature and mass loss rate of the char plate which are determined from the unsteady 1-D analysis with a givenset of 8 properties. The estimated properties using the inverse analysis based on the genetic algorithm show acceptable agreements with the input properties used to obtain the surface temperature and mass loss rate with errors between 1.8% for the specific heat of the virgin material and 151% for the specific heat of the charred material.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.209-216
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• 2005

A new second generation advanced thermal imager, which can be used for battle tank sight has been developed by ADD. This system uses a $480\times6$ TDI HgCdTe detector, operating in the $7.7-10.3{\mu}m$ wavelength made by Sofradir. The IR optics has dual field of views such as $2.67\times2^{\circ}$ in NFOV and $10\times7.5^{\circ}$ in WFOV. And also, this optics is used for athermalization of the system. It is certain that our sensor can be used in wide temperature range without any degradation of the system performance. The scanning system to be able to display 470,000 pixels is developed so that the pixel number is greatly increased comparing with the first generation thermal imaging system. In order to correct non-uniformity of detector arrays, the two point correction method has been developed by using the thermo electric cooler. Additionally, to enhance the image of low contrast and improve the detection capability, we have proposed the new technique of histogram processing being suitable for the characteristics of contrast distribution of thermal imagery. Through these image processing techniques, we obtained the highest quality thermal image. The MRTD of the LWIR thermal sight shows good results below 0.05K at spatial frequency 2 cycles/mrad at the narrow field of view.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.1-8
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• 1985

인류에 필수불가경한 에너지는, 석유, 석탄과 같은 화석연료에 의한 염에너지와 수력, 조력, 파력, 풍력 등의 비열에너지가 있으나, 에너지이용량중 열에너지가 절대적 우위를 점하고 있다. 열에너 지는 전기한 화석연료 뿐만 아니라, 태양집, 태양열발전소와 같은 태양열에너지의 직접이용, 핵에 너지의 열에너지전환, 지열, 해수의 온도차이용등, 열에너지는 다량하면서 막대한 에너지량을 보 유하고 있는 실정이지만, ㅈ로 석유자원에 의존하여 온 것이 현상이다. 그러나, 1970년대 초기에 엄습한 석유파동이래, 세계적으로 에너지위기감에 사로잡혀, 세계각국은 탈석유화에 따른 에너지 의 다양화와 에너지절약이 감소되게 되었다. 연료절약에 관하여 말하면, 에너지이요의 효율화를 적극적으로 도모함에 있어서 열에너지이용에 관한 평가방법에 새로운 검토가 가해져서, 더 합 리적인 평가방법의 확립이 필요하게 되었다. 이를 위해서는 종래의 열역학 제1법칙에 의한 열 에너지의 양적평가 뿐만 아니라, 열역학 제2법칙에 의한 질적평가의 중요성이 인식되어, 유효에 너지(available energy) 또는 엑세르기(Exergie)의 개념이 위상되고 있다. 물론 이 개념을 적용 하여 열역학 제2법칙에 의한 해석에 따른 일정산(heat balance)에 있어서 전혀 새로운 결과가 얻어지는 것은 아니지만, 지금까지는 열정산에 있어서 열역학 제1법칙에 의한 평가방법만이 강 조되어, 열역학 제2법칙에 의한 평가방법은 거의 도외시되어온 것이 실정이며, 우리나라에서 발 간되는 열역학에 관한 도서에서도 이에 관한 검토 내용이 거의 찾아볼수 없거나, 가령 언급된 것이 있다 하더라도 그 내용이 간략하여 그 중요성이 경시되어온 것이 사실이다. 그러나 열역학 제2법칙에 의한 에너지정산에 의하여, 제1법칙에 의한 것보다 열에너지의 합리적이고 또한 유 효한 과학적평가가 가능하게 되어, 장치나 기기의 개선에 구체적이면서 합리적인 지침이 주어 지게 된다. 그리하여 이들 개념과 방법의 소개가 필요하다고 생각되어, 지금부터 우리들이 잘 아는 용어를 사용하여 해설을 서로 하기로 한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.5
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• pp.210-215
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• 2006

Mechanical alloying (MA) by high energy ball mill of pure copper and niobium powders was carried out under the Ar gas atmosphere. The supersaturated solid solution can be produced in the range up to $Cu_xNb_{100-x}$(x=5-30) by MA for 120 hrs, as demonstrated by X-ray diffraction, DSC analysis and the electronic studies through a change in the superconducting transition in the low-temperature specific heat. The $Cu_{30}Nb_{70}$ samples ball-milled for 120 hrs exhibit only a broad exothermic heat release. The total energy, ${\Delta}H_t$ accumulated during MA far the mixture of $Cu_{30}Nb_{70}$ powders increased with milling time and approached the saturation value of 7.5 kJ/mol after 120 h of milling. It can be seen that the free energy difference between the supersaturated solid solution and the mixture of $Cu_{30}Nb_{70}$ powders is estimated to be 7 kJ/mol by Miedema et al. Hence it is thermodynamically possible to assume the formation of a supersaturated solid solution phase in this system.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.991-996
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• 1995

Effects of high hydrostatic pressure on microorganisms and browning enzymes in Angelica keiskei juice were investigated using response surface methodology. The optimum process condition for maximum reduction of total aerobes was $5700\;kg_f/cm^2$ (558.6 MPa) pressure and 7.16 min process time, and 3.44 log cycle reduction of total aerobes was predicted at the optimum condition. E. coli, initially $8.8{\times}10^3\;CFU/ml$, was completely inactivated by high hydrostatic pressure at all process conditions ($3800{\sim}6700\;kg_f/cm^2\;pressure;\;3{\sim}17\;min\;process\;time$). Polyphenol oxidase and peroxidase were partly inactivated by the high hydrostatic pressure. It was also indicated that inactivation of microorganisms and browning enzymes by hydrostatic pressure is dependent on pressure rather than process time.