• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1998년도 추계 학술발표회 논문집
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• pp.180-192
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• 1998

One of the conventional gas burners has nowadays been used for ladle preheating. As a ladle is one of the open-type furnaces, however, it causes to consume much fuel because of high temperature of exhaust gas from the ladle and the exhaust gas passing through ladle cover makes it worsen a working environment nearby. Therefore, the objective of this study is to develop the recuperative burner system applying for an existing teeming ladle , which is integrated with burner, recuperator and eductor as one of the new type combustion equipments and has many advantages of simple installation, compactness and easy control, especially a great deal of energy saving through the waste heat recovery from exhaust gas. The contents of the study is to design, manufacture of recuperative burner system and to perform its tests experimentally after applying to the teeming ladle in the capacity of 100 ton. Its heat release rate is 1,700,000 kcal/h with COG(Cokes Oven Gas) as fuel gas. The test items are the temperature distribution inside the ladle and the preheated air temperature change depending upon the exhaust gas. Nox, exhaust gas analysis and noise.

• 설비공학논문집
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• 제29권1호
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• pp.38-42
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• 2017

This study proposes an idea for energy saving in apartment machine rooms. A conventional district heating system is equipped with constant-flow pumps and bypass valves to regulate pump differential pressure. Each family unit is equipped with a constant-flow on/off valve. This leads to excessive hot water circulation and a high return temperature. To reduce energy loss, this study assumes that each family unit is renovated with a heating valve which regulates the return temperature at $35^{\circ}C$. The hot water supply pump is also replaced with a pump with an inverter to vary flow rate. Expected energy savings is then estimated from field test data. According to the results, pump electricity consumption was reduced by 6,100 kWh for a family unit building over about half a year. The supply temperature can also be lowered by $5^{\circ}C$, which can contribute to a production of electricity of 10.3 kWh/ton of hot water.

• 설비공학논문집
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• 제1권2호
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• pp.116-127
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• 1989

Research on reheating cooling cycle and its practical application have been made to prevent unequalized distribution of temperature and humidity of room due to lack of supply air volume and dewdrops on supply diffusers to be taken place as a result of lower temperature of supply air than that of dew point of room air in cooling cycle of constant air volume, single duct, single zone and draw-through fan type. In view of the fact that human body is insensitive to humidity, it is possible not only to construct the complete non-reheating cooling cycle by increasing the humidity point allowable with the deduction of occupant's sense of pleasantness minimizing, but also to get cooling cycle decreasing the reheating quantity if the humidity exceeds the point allowable. In addition, it is possible to save maximum 8% in electric energy for cooling in cooling system by constructing non-reheating cooling cycle instead of reheating cooling cycle and by increasing the relative humidity of room from 50% to 65% in case efficiency and air pressure of cooling system are low. It is also possible to get an optimum cooling cycle by determining the room humidity in consideration of pleasantness of occupants and conservation rate of electric energy if the cooling capacity, efficiency and total pressure of cooling equipment are fixed.

• 한국통신학회논문지
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• 제39C권11호
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• pp.1151-1158
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• 2014

본 논문에서는 WiMedia 프로토콜에서, 전송 효율을 높이기 위한 연쇄된 프레임 기법을 분석한다. 그리고 연쇄된 프레임에 포함되는 미니-프레임들중 일부 미니-프레임의 손실로 인해 발생하는 성능 저하를 감소시키기 위한 효율적인 전송기법을 제안한다. 본 논문에서 제안하는 전송 기법은 연쇄된 프레임에 포함되는 미니-프레임의 손실이 발생할 경우, 에러가 발생한 미니-프레임만을 재전송하여 전체적인 에너지 소모를 줄이고, 전송효율을 높일 수 있다. 이를 증명하기 위해, 본 논문에서는 제안된 기법을 시뮬레이터에 적용시켜서 성능 분석을 수행하였다.

• 신재생에너지
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• 제5권4호
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• pp.60-65
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• 2009

The present study was conducted for a comparative evaluation of wet and dry floor heating systems using geothermal heat pump. We circulated hot water from geothermal heat pump which is $10{\sim}15^{\circ}C$ lower than that from boiler. In order to access indoor temperature ($25^{\circ}C$) it took 74 minutes for dry type and 247 minutes for wet type. Average floor temperature was $23.9^{\circ}C$ for wet type and $32.7^{\circ}C$ for dry type. Energy saving rate gradually increased by 66% after 138 minutes. As a result, in case of floor heating system using low temperature circulation water, dry type was more practicable for stable floor heating than wet type in terms of floor temperature and access time to indoor set temperature.

• 청정기술
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• 제6권1호
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• pp.71-78
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• 2000

본 연구는 광합성 균주인 C. thiosulfatophium을 이용한 황화수소의 생물학적 탈황공정시 광에너지를 저감시키기 위해 광원의 종류와 광조사 유형에 따른 탈황효율을 조사하였다. 광에너지를 저감시키기 위해서는 반응기내 광분산 효율을 극대화시켜야 한다. 광이용효율을 높이기 위해, 세균농도와 생성부산물의 증가에 의한 빛의 산란과 흡수가 세균성장에 미치는 영향에 관한 연구와 미생물이 필요로 하는 파장의 빛을 최대로 공급하기 위해 LED, 백열등, 태양광 등을 이용한 광원의 최적화 연구, 그리고 외부조사형 광반응기의 광투과 효율의 한계를 극복하기 위한 광섬유를 이용한 내부조사형 광반응기에 대한 연구를 수행하였다.

• 전기학회논문지
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• 제64권9호
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• pp.1391-1397
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• 2015

Recently, various researches are conducted in the application of regenerative energy produced during the operation of an electric locomotive. Regenerative energy is produced by a generator in the brake procedure. The generator is operated by kinetic energy of an electric railroad using an electric motor. The process of producing regenerative energy varies with the current type of a railroad and its running condition. The quality of electric power can be improved and electric energy can be utilized effectively, especially in the use of an energy storage system (ESS). Thus, it is necessary to apply ESS into AC section and high speed railway. This study analyses the composition of the regenerative ESS equipment installed in Yong-Jeong sectioning post, operational principle, charge and discharge algorithm and energy efficiency. The analysis shows that CO2 emissions can be reduced about 0.5 ton per a day. In addition, ESS helps saving the energy and the compensation of the voltage drop caused by the operation of high speed train when it is installed at the end of the feeder section. The number of high speed train will be increased continuously related to the electrification rate. Therefore, applying the ESS to high speed railway is expected to solve the instability of the feeder voltage and the equipment capacity problem caused by the high speed trains.

• Journal of Biosystems Engineering
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• 제9권2호
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• pp.65-73
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• 1984

While most of researches on the performance of high temperature grain dryer have dealt mainly with improving dryer capacity and drying speed during the last twenty years, energy efficiency, in fact, has not been emphasized. Current fuel supplies and energy cost have shifted the emphasis to reducing the energy consumption for grain drying while maintaining dryer capacity and grain quality. Since the energy input for drying is relatively large, the recovery and reuse of at least part of the exhaust energy can significantly reduce the total energy consumption in existing drying systems. Unilization of exhaust heat in grain dryer either through direct recycling or by a thermal coupling in heat exchanger have been subject of a number of investigators. However, very seldom research in Korea has been done in this area. Three drying tests(non-recycling, 0.22 recycle ratio, and 0.76 recycle ratio)were performed to investigate the thermal efficiency and heat loss factors of continuous flow type dryer, and to analyze the effect of recycle ratio (weight of exhaust air recycled/total weight of input air) on the energy requriements for rough rice drying. The test results showed that when the exhaust air was not recycled, the energy lost from furnace was 15.3 percent of input fuel energy, and latent and sensible heat of exhaust air were 61.4 percent and 11.2 percent respectively. The heat which was required in raising grain temperature and stored in dryer was relatively small. As the recycle ratio of exhaust air was increased, the drying rate was suddenly decreased, and thermal efficiency of the kerosene burner was also decreased. Drying test with 0.76 recycle ratio resulted in 12.4% increase in fuel consumption, and 38.4% increase in electric power consumption as compared to the non-recycled drying test. Drying test of 0.22 recycle ratio resulted in 6.8% saving in total energy consumption, 8.0% reduction in fuel consumption, and 2.5% increase in electric power consumption as compared to the non-recycled drying test.

• 대한기계학회논문집B
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• 제33권4호
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• pp.255-263
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• 2009

The most concerning issue of these days is the energy crisis caused by increasing threat of dependence on imported oil and volatile market trend. Under these circumstances, the PHEV(plug-in hybrid electric vehicle) is drawing attention for the next generation's car which could give a chance to decrease the dependence on imported oil and reduce the environmental impact of vehicle. The fueling cost of PHEV, one of the core factor of decision about buying car, should be calculated in the circumstances of Korea to make sure that PHEV has competitive power in real market. The fuel cost saving of PHEV versus CV(conventional vehicle) is simulated and discussed in the condition of increasing gasoline cost, electricity rate, and city-gas rate. In conclusion, the PHEV60-FS shows the best economic feasibility when gasoline price goes up. The PHEV20 has the most stable economic feasibility as electricity rate increases. The fuel cell cogeneration system for RPG could be an alternative for charger of PHEV in the near future.

• Journal of Biosystems Engineering
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• 제21권1호
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• pp.52-59
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• 1996

In this study, the combined forces of electro-osmosis and compression were applied to cabbage dewatering and their effects were discussed. Nine treatments of combined forces consisting of three levels of voltage and compression were applied to chopped and macerated chinese cabbage placed in the experimental set-up consisted of cylinder-piston. The results showed that as both voltage and pressure increased the dewatering rates increased and the combined force of voltage and compression was a very effective means in the dewatering of chinese cabbage in which the largest dewatering rate difference, 72%, was found between the combined force of 30V with 68.2kPa and no voltage(0V) with 68.2kPa. However, no significant difference was found between the voltage of 0 and 10volts in 9.75kPa and the pressure of 68.2kP and 126.7kPa in 30volts. The maximum and minimum dewatering rate were 82% in the combined force of 30 volts of 126.7kPa and 8% in 0 volt of 9.75kPa, respectively. Within the experimental trials, it appeared that the best treatment combination would be pressure of 68.2kPa and voltage of 30V producing dewatering rate of 80ft in which the produced liquid contained about 1% solid. Employing this dewatering method as a pretreatment before drying process can contribute in considerable energy saving in agricultural wastes treatment.