• Tribology and Lubricants
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• 제8권2호
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• pp.7-13
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• 1992

Wear experiments were conducted using the SRV machine on the lubricated conditions of the several temperature and load. Oil samples were prepared by adding several friction modifiers into both paraffinic base oil and engine oil. Friction and wear characteristics of the oils were determined and are discussed in connection with the friction modifiers contained, the testing temperature and the load applied. From the study, it was found the MoDTC and the MoDTP, added into the engine oil, caused drastic increase in wear and had a tendendy to lose the friction-reducing property on some specific conditions of temperature and/or load, though they had the good property on other conditions. Ashless friction modifiers and dispersed $MoS_2$ investigated showed the good friction-reducing property, but the loads, where they became active, were different.

• KSTLE International Journal
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• 제1권1호
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• pp.63-68
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• 2000

Angular contact ball bearings are mainly used in the spindle, which requires high speed and stiffness. The heat generation is studied by experiments and simulations using a pair of angular contact ball bearings. The temperature variation of inner and outer races and the temperature increment distribution are measured by using thermocouples for the rotational speed, preload, viscosity of lubricant. The measured values from experiments are used to estimate the heat conduction rate. The method of oil-air lubrication is used for the experiment. The amount of conduction heat transfer to the test spindle and the convection heat transfer coefficients long the spindle are computed by using inverse method with temperature increment distribution. Total heat generation rate is estimated with the heat partition rate which is calculated from temperatures of inner and outer races. In addition, the empirical factor of oil-air lubrication method for Palmgren's heat generation model is suggested. The empirical friction coefficients, which are obtained from the experiments, depend on the preload condition, and can give us more accurate estimation of the heat generation in ball bearings.

• 한국분무공학회지
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• 제2권3호
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• pp.25-31
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• 1997

This experiment was undertaken to investigate the spray characteristics of the conventional injection system and the ultrasonic energy added injection system. Test fuels include light oil and mixed light-BC oil. The mixed light-BC oil was injected at the normal temperature$(20^{\circ}C)$ and the high temperature$(95{\pm}2^{\circ}C)$ and injection pressure was $120kg/cm^2$. Sauter mean diameter was measured under the variation of the spray distance. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. It is also found that the condition of the ultrasonic energy added injection and high temperature injection generates the smaller droplets than that of the conventional injection.

• 대한방사선기술학회지:방사선기술과학
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• 제11권1호
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• pp.33-41
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• 1988

This study was measured the radiation-induced current - X-ray dose, dose rate, X-ray quality, time, temperature, electric field characteristics and the dependence of gap length in insulating oil under of D.C. Voltage before, during and after X-ray irradiation. The obtained results can be summarized as following. 1. The radiation - induced current is more the dependence of X-ray quality (tube voltage) than quantity (tube current), the dependence of quantity is appeared at the high than low X-.ay tube voltage. 2. The dependence of dose rate is appeared at the more dose rate, and ${\triangle}\;=\;0.64{\sim}0.74$. 3. The higher temperature of insulating oil and X-ray tube voltage (X-ray quality) is increased, at the low electric field, the more radiation-induced current. 4. $G_{eq}-G_{o}(={\triangle}G)$ is increased at the low than high temperature, high than low X-ray quality. 5. The dependence of temperature is appeared before than during X-ray irradiation. 6. The RIC saturation region is appeared at the high than low insulating oil temperature during (1000 V/cm above) than before (4000 V/cm above) X-ray irradiation.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.961-966
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• 2009

This paper presents precise temperature control of oil outlet in an oil cooler with hot-gas bypass control as an industrial refrigerator. The control system was designed for obtaining precise temperature control performance even though abrupt disturbances based on flow rate control of hot-gas bypass. PID controller was adopted in feedback control system. We showed that the gain of PID could be easily determined by using gain-tuning methods without any numerical model. Through some experiments, excellent control performances such as overshoot within 1.7%, steady state temperature error within ${\pm}0.1^{\circ}C$ were established by a simple PI controller. We expect that the system can control the target temperature within error of $0.33^{\circ}C$ under abrupt disturbances.

• 공업화학
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• 제8권6호
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• pp.973-978
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• 1997

Diglycidyl ether of bisphenol A(DGEBA)수지에 castor oil(CO)로 혼합한 후 경화촉매인 tris(dimethylaminomethyl) phenol (DMP-30)로 반응시킨 에폭시의 강인성과 모폴로지를 관찰하였다. 개질제인 CO와 에폭시수지의 혼합물은 기존의 에폭시 개질제인 carboxyl terminated butadiene acrylonitrile(CTBN)보다 상용성이 좋았다. 경화온도와 CO의 양이 증가할수록 유리전이온도가 감소하였는데, CO/에폭시 경화물은 경화온도가 증가할수록 가교밀도가 감소하면서 연성구조를 갖게 되는 것으로 해석되었다. CO/에폭시 경화물은 경화온도 $40^{\circ}C$에서 CO의 양이 증가함에 따라 강인성이 약간 증가하였다. 경화온도가 증가와 CO의 양이 증가함에 따라 강인성이 증가하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권1호
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• pp.8-12
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• 2012

This study is maintains the condition of high temperature (above $600^{\circ}C$) within a short time using on microwave and high temperature heating elements. And removal characteristics according to changes in soil moisture, microwave power and temperature through the decomposition of the contaminated soil by oil. The difficulty resolvability material was sort of lubricating oil having long carbocyclic (C18-C50) and TPH removal rate reached 85.2% at 6 kW and $700^{\circ}C$ and thus the contaminant was removed 1,788 mg/kg within a process time of 40 minutes. In the case of light oil, gasoline contaminated soil, the removal amount showed 567 mg/kg and the treatment rate reached 98.4% at 6 kW, $500^{\circ}C$ and 20 minute. In the case of non-resolvability reached TPH concentrations on 2,000 mg/kg of worrisome level of soil contamination in the 3 zones at 6 kW, $700^{\circ}C$ and 30 minute. At the time, showed up processing costs 8,173 won per ton.

• 한국식품조리과학회지
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• 제13권1호
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• pp.40-46
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• 1997

약과의 제조조건에 따른 탈수량 및 유지 흡수량의 변화와 그때의 품질특성을 알아보고자 반죽을 냉장.냉동했을 경우 및 반죽의 크기, 튀김온도와 반죽횟수, 원료배합량을 달리하였을 경우의 탈수량 및 유지 흡수량의 변화, 관능적 특성 등을 조사하였다. 반죽을 냉장.냉동 했을 경우 control군과 탈수량, 유지 흡수량, 관능적 특성에 차이가 없었다. 반죽의 크기를 중, 대, 소로 하였을 경우 크기가 작을수록 탈수량과 유지 흡수량이 증가하였고, 크기가 중인 것이 전반적인 기호도에서 기호도가 가장 높았다. 튀김온도(12$0^{\circ}C$ 36분, 14$0^{\circ}C$ 16분, 16$0^{\circ}C$ 11분, 18$0^{\circ}C$ 7분)의 영향은 탈수량은 거의 차이가 없으나 유지 흡수량은 온도가 높을수록 감소하였다. 반죽횟수(30회, 200회)의 영향은 탈수량은 거의 차이가 없으나 유지 흡수량은 반죽횟수가 많을 때 감소하였다. 원료배합량에 따른 영향은 참기름, 꿀, 소주의 배합량이 증가하면 탈수량이 증가하였는데 소주의 경우 탈수 정도가 컸다. 유지 흡수량은 참기름의 경우는 첨가량의 증가에 따른 유의차가 없었고, 꿀의 경우는 첨가량이 증가하면 유지 흡수량이 유의적으로 증가하였으며, 소주의 경우는 첨가량이 증가하면 유지 흡수량이 유의적으로 감소하였다. 튀김온도, 반죽횟수, 원료배합비를 달리한 약과의 관능평가에서는 유지 흡수량이 많은 약과의 경우 광택, 연한 정도, 부서지는 정도, 기름 맛 등의 특성이 강하다고 평가하여 위의 제조조건이 약과의 유지 흡수량과 그에 따른 관능적 성상에 큰 영향을 미친다는 것을 알 수 있었다.

• 공업화학
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• 제24권2호
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• pp.144-147
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• 2013

Sweating은 오일 중에 수종의 안료를 분산시키고 이들을 왁스로 고화시킨 계의 표면에 출현하는 특이한 현상으로 립스틱이나 커버메이크업 같은 고형 제품에 흔히 나타나며 원인은 불균형한 처방에 기인한다. 그동안 화장품 분야에서 Sweating 현상을 개선하기 위하여 많은 연구가 진행되어 왔다. DSC는 주로 일정 조건 하에서 온도에 따른 시료의 열적 특성의 변화를 측정하는 분석 방법으로 이 변화를 온도 또는 시간의 함수로 기록하는 기기를 말한다. 오일/왁스구조의 열적 특성(thermal property)을 파악하기 위하여 DSC를 이용하였으며, 이러한 열적 특성과 Sweating 현상이 어떠한 상관관계가 있는지 파악하였다. 오일/왁스 제형 중 온도 변화에 따른 구조 변화가 적은 열적 특성을 나타내고 사용감과 제형 안정성을 갖는 최적융점의 오일/왁스 제형을 연구하였다. 또한, 다양한 온도 범위에서 오일/왁스 제형의 Sweating 현상을 관찰하였으며 그 결과 온도 변화에 따른 구조 변화가 적은 오일/왁스 제형이 Sweating 현상도 최소화하는 조합임을 관찰하였다.

• Tribology and Lubricants
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• 제22권5호
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• pp.260-268
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• 2006

The dielectric constants of used gasoline engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$ Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz,,and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 4% for gasoline engine oil.