• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.74-80
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• 2005

It becomes necessary for engine manufactures to verify whether lots of engines on test bed during shop test are in compliance with NOx Technical Code for marine diesel engines more efficiently on the basis of engine group test concept which contains parent engine and member engines since all the engines are not needed to take NOx measurement. In addition, it becomes more obliged to consider parameters which affect NOx emission level and describe these parameters in NOx technical file as engine information and settings to define engine operation range with tolerance to make sure the engines are still in compliance with NOx emission limit on board after shop test. During preparation of engine group test for 4-stroke marine diesel engines, we evaluated NOx emission value under different engine operating conditions and found that there are certain parameters, for example, Charge air temperature and Max. cylinder pressure which have influence on NOx emission level. The NOx emission shall be satisfied with NOx technical code by means of controlling such parameters.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.37-41
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• 1997

Hot-water soluble extracts were prepared from medium-sized barks of Siberian larch (Larix gmelineii). The extracts were fractionated by ultrafiltration method for producing uniform quality of adhesives. Molecular weight distribution of the extracts was ranged of 100 to 300.000. pH of the extracts affected amounts of flux, and the range of pH 6~pH 8 was proper for wood adhesives, because of easy concentration and fast gelation time. Removal of particles greater than $0.45{\mu}m$ from the extracts increased both filtration speed (flux) and yields of solids in the filtrates. In ultrafiltration process. operating pressure, filtrate temperature, and flow rate significantly increased with the increase of individual condition. Ultrafiltration using PM10 membrane was very effective to fractionate and concentrate the extracts. Removal of large particles greater than 0.45 m from the extracts increased filtration speed(flux) and yields of solids in the filtrates. A gelation time was accelerated with the increasing pH of the extracts and its concentration. The Stiasny precipitate(26%) from the filtrate obtained by PM 10 membrane was very lower than that(78%) of the retentates. This ultrafiltration method was efficient for obtaining high yield purified phenolic compounds.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.78-84
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• 1992

Streptomyces sp. No.8, which produced glucose isomerase was isolated from soil samples. The isolated strain, No.8, was identified as belonging to the Genus Streptomyces. A mutant strain, SM 805, showed the greatest ability to produce glucose isomerase. It was developed from the strain, No.8, by mutagenesis induced by NTG and UV treatment. The mutant strain, SM 805, produced about 7 times more glucose isomerase than the parental strain, No.8. This enzyme catalyzed the isomerization of D-xylose, D-glucose and D-ribose. It was inactive in the absence of metal ions, but was activated by the addition of $Mg^{2+}$ or $Co^{2+}$. The optimum temperature and pH for enzyme activity were $80^\circ{C}$ and pH 8.5, respectively. The enzyme was stable in a pH range of 6.0 to 10.0, and it was highly thermostable. There was no activity loss below $80^\circ{C}$, and even above $90^\circ{C}$ about 45% of its activity was retained. The reaction equilibrium was reached when about 53% fructose was present in the reaction mixture. Whole cells containing glucose isomerase from Streptomyces sp. SM 805 were immobilized by glutaraldehyde treatment. The resultant immobilized enzyme pellets showed a relatively long stability during the isomerizing reaction. The half-life of the immobilized enzyme during the operating was 45 days in the presence of 10mM $Mg^{2+}$.

• KIEAE Journal
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• 제14권3호
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• pp.71-77
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• 2014

This study aimed at developing and evaluating performance of the two logics for respectively operating two-position- and variable-heating systems. Both logics control the heating system and openings of the double skin facade buildings in an integrated manner. Artificial neural network models were applied for the predictive and adaptive controls in order to optimally condition the indoor thermal environment. Numerical computer simulation methods using the MATLAB (Matrix Laboratory) and TRNSYS (Transient Systems Simulation) were employed for the performance tests of the logics in the test module. Analysis on the test results revealed that the variable control logic provided more comfortable and stable temperature conditions with the increased comfortable period and the decreased standard deviation from the center of the comfortable range. In addition, the amount of heat supply to the indoor space was significantly reduced by the variable control logic. Thus, it can be concluded that the optimal control method using the artificial neural network model can work more effectively when it is applied to the variable heating systems.

• 대한전기학회논문지:전력기술부문A
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• 제55권10호
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• pp.399-409
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• 2006

This paper presents a novel method for satisfying the thermal comfort of indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. Korea Electric Power Corporation (KEPCO) use the fixed duty cycle control method regardless of the indoor thermal environment. However, this method has disadvantages that energy saving depends on the set-point value of the Air-Conditioner and direct load control (DLC) has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. In this paper, the variable duty cycle control method is proposed in order to compensate the weakness of conventional fixed duty cycle control method and improve the satisfaction of residents and the reduction of peak demand. The proposed method estimates the predict mean vote (PMV) at the next step with predicted temperature and humidity using the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. To verify the effectiveness of the proposed variable duty cycle control method, the case study is performed using the historical data on Sep. 7th, 2001 acquired at a classroom in Seoul and the obtained results are compared with the fixed duty cycle control method.

• Nuclear Engineering and Technology
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• 제47권3호
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• pp.227-239
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• 2015

The thermal, mechanical, and neutronic performance of the metal alloy fast reactor fuel design complements the safety advantages of the liquid metal cooling and the pool-type primary system. Together, these features provide large safety margins in both normal operating modes and for a wide range of postulated accidents. In particular, they maximize the measures of safety associated with inherent reactor response to unprotected, doublefault accidents, and to minimize risk to the public and plant investment. High thermal conductivity and high gap conductance play the most significant role in safety advantages of the metallic fuel, resulting in a flatter radial temperature profile within the pin and much lower normal operation and transient temperatures in comparison to oxide fuel. Despite the big difference in melting point, both oxide and metal fuels have a relatively similar margin to melting during postulated accidents. When the metal fuel cladding fails, it typically occurs below the coolant boiling point and the damaged fuel pins remain coolable. Metal fuel is compatible with sodium coolant, eliminating the potential of energetic fuel-coolant reactions and flow blockages. All these, and the low retained heat leading to a longer grace period for operator action, are significant contributing factors to the inherently benign response of metallic fuel to postulated accidents. This paper summarizes the past analytical and experimental results obtained in past sodium-cooled fast reactor safety programs in the United States, and presents an overview of fuel safety performance as observed in laboratory and in-pile tests.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.27-33
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• 2007

In this research, to develop the practical application system of fresh water generation system with plate-type fresh water generator using low pressure evaporation method is the main object, and to do that, this study used the evacuated solar collector with operating range of about $50-85^{\circ}C$ as thermal energy source and solar photovoltaic as electric energy source. To achieve that object, this study set up the demo-plant, then estimated and analyzed the usefulness, the safety, and the reliability through pre-tests during short time ahead of the long-time operation. This study showed that the pumps, which are including sea water supply, ejector, hot water supply, and fresh water pumps, were operated one after another. And, the fresh water yield was closely related with the solar irradiance and lower supply temperature of hot water was revealed more reasonable for the solar energy desalination system. That is due to the insufficient area than the solar collector area being required that was estimated through the performance tests of the fresh water generator.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.427-432
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• 2005

This study developed a program for detecting charged refrigerant amount in system air-conditioner. System air-conditioner is an air-conditioning system with multiple indoor units. Due to the complexity of the system, it is more difficult to detect the refrigerant amount charged in system air-conditioner than in a general single air-conditioner. Experiments were performed for 6 HP outdoor units with 3 indoor units in a psychrometric calorimeter. The experimental amount of charged refrigerant were ranged from 60% to 140% with 10% increasement. Fuzzy algorithm were emploeed for detecting the charged refrigerant amount in a system air-conditioner. The experimental data were used for curve fitting for general ranges for indoor and outdoor temperature conditions. membership function were determined for whole ranges of experimentally measured data and rulebase were defined for each amount of refrigerant charge. Developed program successfully predicted the measured data within 10% resolution range.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.480-487
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• 2007

The experimental implementation for different heating systems, district heating and separate heating and power, is discussed in the analysis of the characteristics of energy-usage in apartment complex. Total 20 families are chosen for the experiment, 10 for the district heating and the others for separate heating and power. Among the 10 families, the operating temperature was forced to be controled within certain range of temperatures for 5 ones, and it was left as usual for the other ones. The configuration and general features of each facilities and data acquisition systems are mentioned in brief and the technical specifications for it are also described. The analysis for the experiment results of this investigation is going to be carried out and published in a subsequent paper.

• Elastomers and Composites
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• 제45권3호
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• pp.152-155
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• 2010

기존의 올레핀계 열가소성 탄성체와 스티렌계 열가소성 탄성체는 넓은 경도 범위, 양호한 내굴곡성, 낮은 밀도, 용이한 리사이클성 등으로 열가소성 탄성체 시장에서 가장 많이 사용되고 있으나, 기존 고무 대비 낮은 탄성과 낮은 사용 온도 등으로 그 사용에 제약을 받고 있다. 이를 극복하기 위하여 올레핀/스티렌 또는 올레핀/$\alpha$-올레핀 공중합체를 이용한 열가소성 탄성체의 개발이 이루어지고 있다. 본 보문에서는 해당 탄성체들의 개발 예와 특성들에 대해 소개하였다. 올레핀/스티렌과 올레핀/$\alpha$-올레핀 공중합체는 현재까지 여러 가지 단점을 안고 있지만, 향후 큰 가능성을 지닌 재료라 할 수 있다.