• 한국식생활문화학회지
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• 제12권1호
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• pp.35-40
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• 1997

약과의 튀김 온도와 반죽 횟수가 약과의 품질 특성에 미치는 영향과 혼합 계획(mixture experiment)에 따라 3가지 성된(참기름, 시럽, 소주)의 수준을 변경하여 재료 배합비가 약과의 품질 특성에 미치는 영향을 조사하였다. 튀김 온도와 반죽 횟수에 따른 영향은 색도에서 L(명도)값은 $120^{\circ}C$에서 유의적으로 높았으며, 반죽 횟수가 많을 때 증가하였다. a(적색도)값은 온도가 높을 때 증가하였으나 반죽 횟수의 영향은 별로 없었다. b(황색도)값은 유의차가 없었다. 경도는 온도가 높을수록 유의적으로 커졌으며 반죽 횟수가 많을 때 경도가 약간 커졌다. 지방 흡수율은 온도가 높아짐에 따라 유의적으로 감소하였고, 반죽 횟수가 많을 때 약간 감소하였다. 집청 흡수율은 온도가 낮을수록 유의적으로 증가하였으며, 반죽 횟수에 따른 차이는 없었다. 재료 배합 비율에 따른 영향은 색도는 재료 배합 비율과의 사이에 뚜렷한 관계를 나타내지 않았으며, 경도는 참기름, 소주의 양이 많아지면 단단해지고 시럽이 많아지면 연해졌다. 지방 흡수율은 참기름, 시럽의 함량이 증가할 때 증가하였으며, 집청흡수율은 참기름과 소주의 함량이 감소하고, 시럽의 함량이 증가할 때 증가하였다.

• Tribology and Lubricants
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• 제12권4호
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• pp.28-34
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• 1996

The lubrication characteristics of high-speed ball bearings have been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flow rates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 2969 N axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.275-280
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• 2018

Methyl ester derived from coconut oil is very interesting to study since it contains free-fatty acid with chemical structure of medium carbon chain ($C_{12}-C_{14}$), so the methyl ester obtained from its part can be a biodiesel and another partially into biokerosene. The use of heterogeneous catalysts in the production of methyl ester requires severe conditions (high pressure and high temperature), while at low temperature and atmospheric conditions, yield of methyl ester is relatively very low. By using microwave irradiation trans-esterification reaction with heterogeneous catalysts, it is expected to be much faster and can give higher yields. Therefore, we studied the production of methyl ester from coconut oil using CaO catalyst assisted by microwave. Our aim was to find a kinetic model of methyl ester production through a transesterification process from coconut oil assisted by microwave using heterogeneous CaO catalyst. The experimental apparatus consisted of a batch reactor placed in a microwave oven equipped with a condenser, stirrer and temperature controllers. Batch process was conducted at atmospheric pressure with a variation of CaO catalyst concentration (0.5; 1.0; 1.5; 2.0, 2.5%) and microwave power (100, 264 and 400 W). In general, the production process of methyl esters by heterogeneous catalyst will obtain three layers, wherein the first layer is the product of methyl ester, the second layer is glycerol and the third layer is the catalyst. The experimental results show that the yield of methyl ester increases along with the increase of microwave power, catalyst concentration and reaction time. Kinetic model of methyl ester production can be represented by the following equation: $-r_{TG}=1.7{\cdot}10^6{_e}{\frac{-43.86}{RT}}C_{TG}$.

• 멤브레인
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• 제10권4호
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• pp.220-229
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• 2000

본 연구는 한외여과 중공사형 모듈과 역삼투 나권형 모듈로 구성된 모듈 set 1∼7을 이용하여 모듈 set에 따른 순수 및 2차 처리수의 투과 flux를 고찰하고, 적용압력과 온도변화에 의한 한외여과 막과 역삼투 막의 분리 특성을 고찰하였다. 탁도와 SS는 한외여과 막에서 효율적으로 제거되며 COD, T-N, TDS 등은 역삼투 막에서 우수한 제거효율을 나타내었다. 적용압력과 온도의 증가에 따른 투과 flux는 선형적으로 증가하는 경향을 보였다. 이로부터 한외여과 및 역삼투 막은 정유공장 방류수의 고도처리 및 재활용을 위해 적합한 것으로 나타났다.

• 설비공학논문집
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• 제5권4호
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• pp.265-277
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• 1993

Recently, underground transmission system is growing continuously according to the electric power demand increase in the downtown area. Even if domestic cable makers are manufacturing 154kV oil filled cable and joint, the design technology of cable-joint has not been fully self-reliance. This study is aimed at the detail heat transfer analysis of 154kV cable-joint. So, that is cut into the five sections in order to analyze a conjugate natural convection in two dimensional $r-{\theta}$ coordinate. The streamline and temperature distributions are obtained for each sections. Also the changes of those are analyzed with respect to the variation of transmission currents and cable-joint surface heat transfer coefficients. The same analyses are also shown in view point of the maximum temperature of conductor and local equivalent conductivity.

• 한국생산제조학회지
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• 제7권4호
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• pp.73-78
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• 1998

In this paper, we have studied about the thermal expansion of the ball screw used for the CNC machine tools. The hollow ball type is used for the ball screw. We have compared the conventional cooling system and function with the improved cooling system and function which is developed the path providing cooling oil in hollow ball screw. That is the temperature variation and positioning accuracy are analyzed of the ball screw. We have obtained the following results through this experiment. 1) The improved cooling system of the hollow ball screw for CNC machine tools was developed 2) The improved cooling system of the hollow ball screw has a large effectiveness on restraining the thermal expansion of the ball screw. 3) The positioning accuracy of the ball screw was improved about 2~4$\mu$m using temperature -controlled cooling oil.

• 전기의세계
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• 제22권4호
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• pp.30-34
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• 1973

The main purporse of this paper is to study on the influence of temperature effect on electrical-properties, i.e., dielectric breakdown voltage, dielectric constant and resitivity of homemade insulating oil containing antioxidant. Transformer oil manufactured in Korea is taken for a sample, and this sample is classified into seven samples in which antioxidant is contained and not contained, and antioxidant is divided into three kinds of amount: 0.3%, 0.5%, 0.8%. Changing the tempe5rature of the samples by oil bath, the electric properties measured from the samples are as follows: (1) the variation of either the dielectric breakdown voltage or the resistivity are considerably large, but the dielectric constants are almost unchanging. (2) In view of electrical characteristic, the deterioration rate of the samples containing antioxidant is somewhat lower than that of other samples. (3) Nearly the same value is shown in the dielectric-breakdown voltage of the samples, in which contained the different amount of antioxidant: 0.3%, 0.5%, 0.8%, but the decrease rate of resitivity is lowest, 0.3%, of all. As the result of the experiment, This study can suggest that 0.3% be the optimum amount of antioxidant which will be added transformer oil manufactured in Korea and is useful for the understanding about the electrical properties of transformer oil containing antioxidant.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제24회 춘계학술대회
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• pp.86-93
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• 1996

The lubrication characteristics of high-speed ball bearings has been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flowrates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 303 kgf axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

• 한국자원식물학회지
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• 제10권2호
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• pp.151-158
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• 1997

본 연구는 콩계통들의 지방함량이 서로 다른 가상요인에 어떻게 영향을 받는 지를 규명하기 위해 미국 노스캐롤라이나지방의 5개 지역에서 3년에 걸쳐 수행하였다. 각 계통의 지방함량 및 지방수량들이 기상요인에 대한 Linear response가 조사되었고, 또한 최저기상 반응모델을 결정하기 위해 Stepwise Selection Program이 사용되었다. 콩지방함량, 지방수량은 기상 요인인 온도와 강우량에 의해 크게 영향을 받았으며 성숙시기에 온도가 가장 높고, 최고최저 온도범위가 가장 작은 환경에서 지방함량이 가장 낮게 나타났고, 최저온도 변이가 가장 작고 강우량변이가 가장 큰 환경에서 지방수량이 가장 높게 나타났다. 계통들의 대부준으 지방함량이 MxDT, HTD, ADT, ADTRg에 반비례하는 경향을 나타내었으며 이는 성숙시기에 온도가 높아질수록 지방함량이 감소한다는 것을 의미한다. 그러나 NC107은 MxDT, ADT에 비례하는 경향을 보였다. 모든 계통들이 VMnDT, VADTRg, ADRa에 비례하는 경향을 나타내었고 이는 최저온도와 최고최저 온도범위의 변이가 클수록, 평균강우량이 많을수록 지방함량은 증가한다는 것을 의미한다. 11계통이 1개 내지 3개의 기상변수를 가지는 최적기상모델을 형성하였다. 그러나 NC109와 NC105는 모든 기상변수에 유의한 Linear 반응을 나타내지는 않았으나 전자는 2개의 기상변수를 가지는 최적기상모델을 형성하였고 후자는 가지지 않았다. 이는 NC109는 지방 함량이 아마도 기상변수 하나에 의한 영향보다도 2개 변수의 상호작용에 의한 영향이 큰 것으로 추측 할 수 있고, NC105는 지방함량이 기상환경에 상대적으로 더 안정하기 때문인 것으로 생각된다. 위와 같은 사실은 콩지방함량의 기상반응에 대한 품종적 차이가 상당히 크다는 것을 의미한다. 지방수량은 ADTRg와 VADRa에 반비례하는 경향을 나타내었으며 이는 최고최저 온도차이와 평균강수량 변이가 클수록 지방수량은 감소한다는 것을 의미한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.79-79
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• 2010

In this paper, we present results of the dielectric breakdown test in various 6.9kV power cables used in power plants. The dielectric strength of the different conditioned cables was measured by placing the sliced cable sections in silicone oil bath with needle electrode. The results were analyzed by the Weibull distribution. The shape and scale parameters of the Weibull distribution for each cable sections under test were calculated and evaluated. Collected data base was applied to deterioration trend analysis and lifetime guide was also proposed.