• 환경위생공학
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• 제9권2호
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• pp.88-100
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• 1994

A study on the recovery of useful components from waste tire. This study was carried out investigate the recovery of fuel oil condensed from gases formed in the pyrolysis of waste tire. Energy to require the pyrolysis of waste tire was used the heat that was produced by the combustion of the gases from the pyrolysis of waste tire itself. The results are as follows; 1. Energy to require forming the fuel oil by the pyrolysis of waste tire was used only 1/6 quantities of waste tire for forming fuel oil. 2. The formed fuel oil were light oil, Kerosene and gasoline 3. The pollutants of combustion gas of patronizable gases was lower than standard Value.

• 설비공학논문집
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• 제14권10호
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• pp.817-824
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• 2002

A diffusion absorption refrigerator is a heat-generated refrigeration system. It uses a three-component working fluid consisting of the refrigerant (ammonia), the absorbent (water) and the auxiliary gas (typically hydrogen). This system has no moving parts and the associated noise and vibration. In this study, the operating characteristics of diffusion absorption refrigerator are investigated through cycle modeling and simulation. System parameters considered in this study are the charged concentration of ammonia aqueous solution, the concentration difference between absorber inlet and outlet and the system pressure determined by the amount of auxiliary gas charged. It was found that there exists a critical value of concentration difference that maximizes the refrigerating capacity. And the lower the system pressure, the higher the refrigerating capacity.

• 한국식품영양과학회지
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• 제24권6호
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• pp.984-989
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• 1995

The concentration-efficiencyh of blue dextran solution in the progressive freeze-concentration was related to the freezing conditions such as the freezing speed and the stirring speed in the solution phase. From the theoreticla balance equation of heat and mass transfer at freezing front, the relationship between the freezing conditions and the ice structure at freezing front was drived. A high freeze-concentration efficiency was obtained under the operating conditions represented by a low speed of freezing and a high speed of stirring. The operating conditions were related to a smooth solid-liquid interface and these results were well explained by the theoretical equation. Effect of the solute component size on the concentration efficiency in the progressive freezeconcentration was also tested. The concentration efficiency of latex particles showed a lower value than that of blue dextran, however, its difference was insignificant.

• 한국수자원학회논문집
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• 제54권12호
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• pp.1215-1222
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• 2021

본 연구에서는 상수관망 수리해석을 통한 폭염 저감 시설로써의 소화전 활용방안연구를 수행하였다. 소화전 설치 지점을 폭염저감을 위해 개방한다고 가정하고, 지점별 수압에 따른 살수반경을 도출하고 전체 대상구역의 살수면적에 따른 도심지 온도의 저감비율을 살수차운영에 따른 살수면적과 비교하였다. 소화전 개방에 따른 살수면적은, 상수관망 수리해석을 통해 소화전이 설치된 절점에서의 압력값을 도출한후, 압력값에 따른 살수반경 관계식을 통해 산정하였다. 제안된 방법론을 2개의 지역에 적용한 결과, 소화전에 의한 살수방법의 온도저감 효과는 절대적인 살수면적의 차이에 따라, 살수차에 의한 살수방법 대비 낮게 도출될 수 있다는 한계점을 보였다. 그러나, 소화전은 살수차와 달리 물공급양에 대한 상대적 제한이 없고 동일한 지역에 대한 지속적인 분할살수가 가능하므로 일정 구역의 살수면적이 확보될 경우 살수차 대비 상대적으로 효과성 있는 폭염저감 효과를 도출할 수 있을것으로 기대된다.

• 한국가스학회지
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• 제14권1호
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• pp.8-14
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• 2010

본 연구에서는 LPG/바이오디젤 혼합연료의 직접분사식 디젤엔진 적용성에 관한 실험을 수행하였다. 특히, 혼합연료를 엔진에 적용하는 경우 엔진성능, 배출가스 (미연탄화수소, 일산화탄소, 질소산화물, 이산화탄소), 연소안정성에 대한 실험을 1,500 rpm의 엔진회전수 조건에서 수행하였다. 바이오디젤은 질량대비 20-60% 범위로 LPG에 혼합하였다. 바이오디젤을 40% 이상 혼합하는 경우 엔진은 모든 부하영역에서 매우 안정적으로 연소되었다. 바이오디젤의 혼합율이 증가할수록 혼합연료의 세탄가가 향상되어 연소시작 시점이 진각되었다. 혼합연료를 사용하면 저부하에서는 과혼합에 의한 부분연소로 인하여 THC와 CO의 배출량이 급증하였으며, NOx의 경우 저부하에서는 배출량이 디젤연료에 비해서 낮았으며 고부하에서는 더 많이 배출되었다.

• 한국식품저장유통학회지
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• 제3권2호
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• pp.137-143
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• 1996

In order to produce the high-quality of dried red pepper with respect to a color and a taste we developed a automatic drier equipped with combined several heat energies(ADCHE). and compared the quality of ADCHE-treated red pepper with that of the pepper treated with conventional dryings such as natural, hot-air, and far-infrared ray dryings. The results obtained were as follows : (1) The contents of capsanthin varied significantly with drying methods within the range of 1.7 to 6. 4mg/g dry weight. The capsanthin level of red pepper treated with far-infrared ray drying was higher than that of the pepper treated with ADCHE showed the highest at 51.46mg/g dry weight of three drying methods. (2) As a result of determination of color intensity of-red-pepper using-a colorimeter, the red color intensity of the peppers was affected by drying methods irrespective of drying temperature, and especially a value of red pepper treated with ADCHE was appeared to be 19. 1, indicated that this pepper have the most bright color intensity. (3) The contents of soluble browing subatances increased with a increase in drying temperature, but L* value of red pepper treated with ADCHE was appeared to be 0.187, indicated that this red pepper have the most clear red color (4) The changes of capsanthin level of red pepper according to drying methodes did not show significantly, but generally a decreasing rate of capsanthin levels were lower in that order ADCHE

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.351-357
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• 2009

This study was conducted to verify the simulation model through the drying test, and investigate effect of factors, such as temperature of drying air, airflow rate, and velocity of the airflow, on the drying. The low temperature drying simulation model was developed based on the circulation dry simulation model presented by Keum et al. (1987), and by modifying low temperature thin layer drying model, equilibrium moisture content model, latent heat of vaporization model, and crack ratio prediction model. The heat pump and experimental dryer with a capacity of 150kg were used for the test. The RMSE between the predicted and measured value was 0.27% (drying temperature), 0.15% (crack ratio), and 2.08% (relative humidity), so the relevance of the model was verified. In addition, the effect of drying temperature, airflow rate, and velocity of the airflow on the drying was examined. The experimental results showed that the crack ratio at drying temperature of $25{\sim}40^{\circ}C$ was allowable. Moreover, at below $30^{\circ}C$, variation of the crack ratio was slight, but drying time was delayed. Given these results, the drying temperature of over $30^{\circ}C$ was effective. As the airflow rate increased, required energy dramatically increased. Whereas drying rate slowly increased, so loss of drying efficiency was caused. Considering these results, the dryer needed to be designed and adjusted to lower than $30\;m^3/min{\cdot}ton$. As velocity of the airflow increased, required drying energy increased when the velocity of the airflow was over $5\;m^3$/hr, while crack ratio and drying rate showed little variation.

• 한국추진공학회지
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• 제14권2호
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• pp.46-53
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• 2010

본 연구에서는 하이브리드 추진 연소에서 산화제의 상(Phase)에 따른 연소특성 변화를 연구하였다. 산화제는 $GN_2O$와 $LN_2O$를 사용하고 고체연료는 HDPE(High Density PolyEthlene)를 적용하여 연소실험을 수행하였고, 상에 따른 고체연료의 후퇴율과 압력선도, 연소효율의 변화 등을 조사하였다. $LN_2O$를 적용할 경우 액체 산화제의 기화에 필요한 잠열이 화염에서 발생되는 연소에너지에 비해 무시할 정도로 작아 $GN_2O$를 산화제로 사용했을 때의 고체연료 후퇴율과는 큰 차이가 없었지만, 추진 성능효율이 낮아짐을 확인하였고, 액체 산화제의 유량이 증가할수록 산화제의 기화에 필요한 열전달 증가로 인 해 연소 불안정성이 커짐을 확인하였다.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1433-1438
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• 2009

본 논문의 목적은 점화시기의 변화가 LPG/가솔린 겸용차량에 미치는 영향을 살펴보기 위한 것으로 가솔린 전용연료 모드를 LPG 전용연료 모드로 진각시킨 제어시스템을 제안하여 엔진회전수(1500rpm, 2000rpm) 및 점화시기 ($5^{\circ}$,$10^{\circ}$,$15^{\circ}$,$20^{\circ}$)의 변화에 따른 실린더내의 가스압력, 압력상승률 및 열발생률을 측정하였다. 그 결과 실런더내의 가스압력 및 압력상승률은 기관의 회전속도가 1500rpm 및 2000rpm 모두 점화시기가 진각될수록 증가하였으나, $20^{\circ}$부근에서의 압력상승률값만 약간 낮게 나타났다. 또한, 열발생률은 1500rpm에서 점화시기가 진각될수록 증가하였으며 2000rpm의 $20^{\circ}$부근에서 감소하는 경향을 볼 수 있었다.

• 열처리공학회지
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• 제3권3호
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• pp.13-20
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• 1990

SCM 21 and D.P steel were carburized in vacuum using prophane at a temperature ranging from 1228k to 1308k under a gas pressure ranging from 21.3kpa to 61.8kpa, and the following results were obrained. 1) D.P. steel has considerable efficiency in depressing the grain growth during the high temperature carburizing and it has fine structure even at 1268k for 14.4ks when carburizied. Therefore this steel is expected to be suitable for vacuum carburizing at a high temperature. 2) Case depth was increased as the carburizing temperature increases and it was 3.2mm at max, temperature of 1308k, for max, time of 14.4ks and under max, pressure of 61.8kpa. Thus vacuum-carburizing was considered effective for the materials which need case depth, which is necessary for machine structure use. 3) The rate of case depth of SCM 21 was faster than D.P. steel under same carburizing conditions and the increasing rate of the case depth was constant. 4) Case depth was increased as the gas pressure becomes high under same carburizing temperature. 5) Case carbon concentration, $C_s$, of SCM 21 obeys to a formula, $$C_s=kt^{1/2}+C_0$$ Where k is $2.15{\times}10^{-2}$($wt%.S^{-1/2}$) and this value is a little bit lower than that of SNCM 815.