• Journal of Biosystems Engineering
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• 제31권1호
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• pp.33-38
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• 2006

This work was conducted to find the operating characteristics of an efficient wet grinding system designed to obtain fine rice husk ash powder. Once the rice husk was combusted and the thermal energy was recovered from the furnace, the ash was fed and pulverized in the grinding system resulting a fine powder to be used as a supplementary adding material to the portland cement. Grinding time (15, 30, 45 min), impeller speed (250, 500, 750 rpm), and mixed ratio (6.7, 8.4, 11.l, 20.9) were three operating factors examined for the performance of a wet-type stirred ball mill grinding system. For the operating conditions employed, mean diameter of fine ash powder, specific energy input, and grinding energy efficiency were in the range of $2.83{\sim}9.58{\mu}m,\;0.5{\sim}6.73kWh/kg,\;and\;0.51{\sim}3.27m^2/Wh$, respectively. With the wet-type stirred ball mill grinding system used in this study, the grinding energy efficiency decreased with the increase in total grinding time, impeller speed, and mixed ratio. The difference in specific surface area of powder linearly increased with logarithm in total number of impeller revolution and the grinding energy efficiency linearly decreased. Grinding time of 45 min, impeller speed of 500 rpm, and mixed ratio of 6.7 were chosen as the best operating condition. At this condition, mean particle diameter of the fine ash, grinding energy efficiency, grinding throughput, and specific energy input were $2.84{\mu}m,\;2.28m^2/Wh,\;0.17kg/h$, and 2.03kWh/kg, respectively. Wet fine grinding which generates no fly dust causing pollution and makes continuous operation easy, is appeared to be a promising solution to the automatization of rice husk ash grinding process.

• Journal of Biosystems Engineering
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• 제25권1호
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• pp.39-46
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• 2000

This work was conducted to study the operating characteristics of a grinding system designed to obtain fine rice husk ash powder. To find better utilizing of rice husk, a valuable by-product from rice production, once the rice husk was incinerated and the thermal energy was recovered from the furnace, the ash was fed and pulverized in the grinding system resulting a fine powder to be used as a supplementary adding material to the portland cement manufacturing . The rice husk ash grinding system consisted of a high speed centrifugal fan for the preliminary coarse milling and a dry-type stirred ball mill for the subsequent fine grinding . Total grinding time 9 5, 15, 30, 45 min), impeller speed (250, 500, 750 rpm) , and mixed ratio (4.8, 7.9, 14.9) were three operating factors examined for the performance of a stirred ball mill used for the fine grinding of ash. With the stirred ball mill used in this study, the minimum attianable mean diameter of rice husk ash powder appeared to be 2 ${\mu}{\textrm}{m}$. During the find grinding, the difference in specific surface area of powder showed an increase and the grinding energy efficiency decreased with the increase in total grinding time, impeller speed ,and mixed ratio. For the operating conditions employed , the resulting mean diameter of fine ash powder, specific energy input, and grinding energy efficiency were in the range of 1.79 --16.04${\mu}{\textrm}{m}$, 0.072-5.226kWh/kg, an d1.11-12.15$m^2$/Wh, respectively. Grinding time of 30 min , impeller speed of 750 rpm, and mixed ratio of 4.8 were chosen as the best operating conditions of the stirred ball mill for fine grinding . At these conditions, mean particle diameter of the fine ash, grinding energy efficiency, grinding throughtput, and specific energy input were 2.73${\mu}{\textrm}{m}$, 3.95$m^2$/Wh, 0.25kg/h, and 1.22kWh/kg, respectively.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.364-369
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• 2012

The development of solar thermal energy used adsorption desalination technology have been examined as a viable option for supplying clean energy. In this study, the modelling of the main devices for solar thermal energy used and adsorption desalination system was introduced. Silica gel type adsorption desalination system is considered to be a promising low-temperature heat utilization system. The design is divided into three parts. First, the evaporator for the vaporization of the tap water is designed, and then the reactor for the adsorption and release of the steam is designed, followed by the condenser for the condensation of the fresh water is designed. In addition, new features based on the energy balance are also included to design absorption desalination system. In this basic research, One-bed(reactor) adsorption desalination plant that employ a low-temperature solar thermal energy was proposed and experimentally studied. The specific water yield is measured experimentally with respect to the time controlling parameters such as heat source temperatures, coolant temperatures, system switching and half-cycle operational times. Desalination is processes that permeate our daily lives, but It requires substantial energy input, powered either from electricity or from thermal input. From the environmental and sustainability perspecives, innovative thermodynamic cycles are needed to produce the above-mentioned useful effects at a lower specific energy input. This article describes the development of adsorption cycles for the production of desalting effects. We want that this adsorption system can be driven by low temperature heat sources at 60 to $80^{\circ}C$, such as renewable, solar thermal energy.

• 한국대기환경학회지
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• 제24권3호
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• pp.329-335
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• 2008

Volatile organic compounds emitted to the atmosphere can cause adverse effects on human health and participate in photochemical smog formation reactions. The destruction of a series of VOCs has been carried out by non-thermal plasma in other researches. And the characteristic of non-thermal plasma was operated at atmospheric pressure and low temperature. A new type non-thermal plasma reactor was investigated combined Glidarc plasma with water jet in this research. Also, it was found that the water-jet had an significant effect on the toluene removal efficiency. But too much water content does not favor toluene decomposition by decreasing of reaction temperature. The input toluene concentration, gas flow rate, water flow rate and specific energy input were used as experiment variables. The toluene removal efficiency, energy efficiency and specific energy input were 75.3%, 146.6 g/kWh and $1.12kWh/m^3$ at a water flow rate of 100 mL/min.

• 공업화학
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• 제34권4호
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• pp.404-411
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• 2023

바이오가스 직접 개질을 위해 플라즈마 방전영역을 확장할 수 있는 3상 글라이딩 아크 플라즈마 수소 추출기를 설계하고 스팀과 메탄의 부피 비율, 가스 유량, 플라즈마 입력 전력에 대해 개질 특성을 평가하여 운전 조건을 최적화했다. 수소생산효율은 플라즈마 에너지 밀도가 작을수록 증가하는 것으로 확인되었지만 C_XH_Y 혹은 carbon soot와 같은 촉매 내구성에 영향을 줄 수 있는 부산물들이 발생했다. 부산물 생성을 억제하기 위해 스팀과 메탄의 비율 혹은 플라즈마 에너지 밀도를 높여야 했고 플라즈마 개질기 최적 조건으로 스팀과 메탄의 비율을 3, 플라즈마 에너지 밀도를 5.5 ~ 6.0 kJ/L로 선정했다. 또한 플라즈마 개질기에서 발생하는 열이 반응가스를 500 ℃ 이상까지 올려줄 수 있어 바이오가스 버너의 연료사용량을 줄여 수소생산효율을 높일 수 있을 것으로 기대할 수 있다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권2호
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• pp.101-107
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• 2012

This study describes a proposed method of converting an input sound signal into a color image by emulating human synesthetic skills which make it possible to associate an sound source with a specific color image. As a first step of sound-to-image conversion, features such as fundamental frequency(F0) and energy are extracted from an input sound source. Then, a musical scale and an octave can be calculated from F0 signals, so that scale, energy and octave can be converted into three elements of HSI model such hue, saturation and intensity, respectively. Finally, a color image with the BMP file format is created as an output of the process of the HSI-to-RGB conversion. We built a basic system on the basis of the proposed method using a standard C-programming. The simulation results revealed that output color images with the BMP file format created from input sound sources have diverse hues corresponding to the change of the F0 signals, where the hue elements have different intensities depending on octaves with the minimum frequency of 20Hz. Furthermore, output images also have various levels of chroma(or saturation) which is directly converted from the energy.

• 한국대기환경학회지
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• 제27권4호
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• pp.379-386
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• 2011

Catalyst-assisted plasma system with a DBD (Dielectric Barrier Discharge) reactor was used to remove hydrogen sulfide, which is one of the odorous species in this study. The ${\gamma}-Al_2O_3$ and ${\beta}$-Zeolite catalysts impregnated by Ag, Cu and Mn species were employed as catalysts and their $H_2S$ removal characteristics under plasma irradiation were investigated. From the experimental study, we found that the $H_2S$ removal efficiency increases with decreasing space velocity in the system and increasing specific input energy. Furthermore, ${\beta}$-Zeolite catalysts are efficient to remove $H_2S$ than ${\gamma}-Al_2O_3$ catalysts. Especially, the catalysts impregnated by Ag have higher removal efficiency than other catalysts (Cu, Mn).

• 한국콘텐츠학회논문지
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• 제20권2호
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• pp.472-477
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• 2020

본 연구는 자기공명영상 검사 시 전자파흡수율을 감소시키는 대안으로 환자정보의 체중을 낮게 입력하는 방법의 오류를 바로잡고자 하였다. 연구방법은 환자정보에 입력하는 체중에 따라 전자파흡수율이 변화되지 않는다는 사실을 증명하기 위해 50kg 팬텀을 코일 안에 위치시킨 후 입력 체중을 10kg에서부터 100kg 까지 10kg 단위로 변화시켜 기기에서 산출되는 전자파흡수율을 비교평가 하였다. 연구결과, T1 강조영상은 전자파 흡수율이 평균 0.2W/kg이었고 T2 강조영상은 평균 0.4W/kg이었으나, T1, T2 강조영상 모두 체중의 변화에 따른 전자파흡수율의 변화는 없었다. 결론적으로 검사 전 검사자가 입력하는 체중에 따라 전자파흡수율은 변화되지 않으므로, 환자정보 입력 시 체중을 낮게 입력하는 것은 전자파흡수율을 감소시키는 대안이 될 수 없다.

• Environmental Engineering Research
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• 제17권2호
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• pp.89-94
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• 2012

Pyrolysis/gasification technology utilizes an energy conversion technique from various waste resources, such as biomass, solid waste, sewage sludge, and etc. to generating a syngas (synthesis gas). However, one of the major problems for the pyrolysis gasification is the presence of tar in the product gas. The tar produced might cause damages and operating problems on the facility. In this study, a gliding arc plasma reformer was developed to solve the previously acknowledged issues. An experiment was conducted using surrogate benzene and naphthalene, which are generated during the pyrolysis and/or gasification, as the representative tar substance. To identify the characteristics of the influential parameters of tar decomposition, tests were performed on the steam feed amount (steam/carbon ratio), input discharge power (specific energy input, SEI), total feed gas amount and the input tar concentration. In benzene, the optimal operating conditions of the gliding arc plasma 2 in steam to carbon (S/C) ratio, 0.98 $kWh/m^3$ in SEI, 14 L/min in total gas feed rate and 3.6% in benzene concentration. In naphthalene, 2.5 in S/C ratio, 1 $kWh/m^3$ in SEI, 18.4 L/min in total gas feed rate and 1% in naphthalene concentration. The benzene decomposition efficiency was 95%, and the energy efficiency was 120 g/kWh. The naphthalene decomposition efficiency was 79%, and the energy yield was 68 g/kWh.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권2호
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• pp.131-136
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• 2012

If one can find a control Lyapunov function (CLF) for a given nonlinear system, the control input stabilizing the system can be easily obtained. To find a CLF, the time derivative of an energy function should be negative definite. This procedure frequently requires a control input which is a rational function or includes an inverse function. The control input is not defined on the specific state-space where the denominator of the rational function is equal to 0 or the inverse function does not exist. In this region with singularities, the trajectory of the control system cannot be generated, which is one of the most important reasons why it is hard to make the origin of a nonlinear system be globally asymptotically stable. In this paper, we propose a smooth control law ensuring the globally asymptotic stability by means of cancelling the singularity in the control input.