• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.4
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• pp.285-291
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• 2001

An 8-b$\times$8-b adiabatic pipelined multiplier is designed. Simplified four phase clock generator is also designed to provide supply clocks for adiabatic circuits. All the clock line charge on the capacitive interconnections is recovered to save energy. Adiabatic circuits are designed based on ECRL(efficient charge recovery logic) and are integrated using 0.6${\mu}{\textrm}{m}$ CMOS technology. The efficiency of proposed supply clock generator is better than the previous one by 4~11%. Simulation results show that the power consumption of adiabatic pipelined multiplier is reduced by a factor of 2.6~3.5 compared to a conventional pipelined CMOS multiplier.

• Journal of the Korean Institute of Gas
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• v.25 no.1
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• pp.7-13
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• 2021

The re-liquefaction drum is a product that installed spray nozzles at the top to directly spray overcooled LNG into evaporative gas and installed demistors to facilitate gas separation, which was developed to increase the re-liquidity efficiency of small scale re-liquefaction facilities. In the hydrostatic test of the drum, no leakage occurred even at a pressure of 1.5 times the design pressure, but during the BOR(Boil Off Rate) test, the bolt loosening occurred due to contraction and expansion by temperature change. For the continued use of the product, insulation construction on flange connections was developed to enable detachment and attachment, and the comparison of heat load with existing insulation confirmed that it was very small compared to the inlet flow rate in the drum.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1264-1269
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• 2004

This research describes the application of hydrocarbon refrigerants for heat pump system which is needed for fish farm. Tested refrigerants are HCFC-22 and hydrocarbon refrigerants(CARE 50 and ASR-20). CARE 50 is mixture of R-290 and R-170, and ASR-20 is mixture of R-152a, R-290 and other additives. Heat pump consist of shell and tube heat exchanger, scroll compressor, expansion valve and accumulator. Manual expansion valve is used for testing of wide range evaporating temperature. Hydrocarbon refrigerants show a good performance as an alternative for HCFC-22 in the range of evaporating temperature from $-6^{\circ}C$ to $6^{\circ}C$.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.511-513
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• 2011

인구증가와 지속적인 산업발전으로 인하여 에너지 소비가 급증하게 되면서 효율적인 에너지 사용의 필요성이 크게 대두되었다. 특히 건물의 창문을 통해 많을 에너지 손실이 일어나 이를 해결하고자 현재 로우이(low-emissivity)유리를 사용하고 있으나 이는 태양광의 유입을 줄이는 단순한 방법으로 여전히 상대적으로 높은 열관류율을 갖고 있다. 이를 해결하고자 현재 단열성능이 좋은 고효율 진공유리가 개발 중이나 아직 가격 및 성능 등의 문제로 본격적인 보급은 이루어지지 않고 있다. 본 논문에서는 내부압력, 지지기둥(spacer)의 길이 및 지름 등이 진공유리 성능에 미치는 영향을 3차원 수치해석을 통하여 알아보았다.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.706-711
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• 2009

Energy shortage and environmental pollution caused by fossil fuels are very serious problem. Especially buildings have consumed more and more energy, and buildings are spend up to 25% of total energy consumption. So we should prepare alternatives to save energy in buildings. In apartment houses, The efficiency of thermal insulators and window glasses is very important to curtail heating energy. In this study, the energy rating of Apartment building is evaluated by applying various thermal insulators and window glasses.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.181-186
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• 1999

The objective of present work is to investigate the performance characteristics of three-lobe Roots type supercharger for the applications of low-compression and high-expansion ration gasoline engine. A performance test was conducted to obtain the drive power, volumetric efficiency, adiabatic efficiency and the influence of performance factors of supercharger . In order to analyze the supercharging characteristics, the experiments are made on operating parameters such as the supercharger speed, pressure ration and inlet temperature on the supercharging performance of the Roots type supercharger . Based on experimental results, the drive power and flow rate of supercharger increased with supercharger speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.195-201
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• 1998

This study aims at the optimal design of rotors and the development of screw type Supercharger of CNG-fueled engine for commercial vehicle. Based on the new rotor profile, an advanced oil free type Supercharger has been developed, which can achieve higher adiabatic efficiency and lower manufacturing cost. The performance test of screw type Supercharger has achieved high volumetric efficiency and the durability on the bench of performance test has also been established in the compact body.

• Journal of the KSME
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• v.50 no.7
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• pp.47-50
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• 2010

이 글에서는 건물에너지 효율을 향상시키기 위한 단열 외피 중의 하나인 창호 부위에서 발생하는 열손실 획득으로 인한 실내 냉난방 부하를 저감하기 위한 국내 창호 기술 현황에 대해 설명한다.

• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.27-32
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• 2004

The oceanic tides have an effect on groundwater levels in coastal fractured rock aquifers. The observed groundwater table fluctuations caused by the effective stress through an aquifer are shown as sine curves similar with tidal fluctuation. To estimate a hydrogeologic parameter, tidal method is utilized with groundwater level fluctuations of two monitoring wells. Cross correlation function is used to calculate time lags between observed groundwater levels and tide, and the deeper well shows longer time lag. The storage coefficients calculated by using tidal efficiency and time lag show large differences. The storage coefficients obtained by using time lags are close to the result of slug test, and that of the deeper well shows closer value by slug test. The tidal efficiency is unsatisfied to apply in the tidal method because of an effect of phreatic aquifer and the vertical flow of groundwater through fractured confining bed. This tidal method can be an economical and effective way to define the parameter by considering the location of observation well and hydrogeologic characteristics of a coastal aquifer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.227-233
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• 2001

최근 비약적인 경제발전에 힘입어 장대교량, 항만, 댐, 도로, 원자력 발전소 등과 같은 대규모 기간구조물의 건설이 증가하고 있으며, 구조물은 대형화 혹은 고강도화되는 추세에 있다. 특히, 전술한 구조물을 매스콘크리트로 가설하게 되면 초기재령시에 수화열로 인한 균열이 발생할 가능성이 매우 높기 때문에 효율적인 매스콘크리트의 개발과 매스콘크리트 구조물의 설계기술 및 시공방법이 중요한 연구대상으로 등장하게 된다. 본 논문에서는 가로 52.6m, 세로 14.4m, 높이 8.5m의 기계기초 매스콘크리트의 시공에 적합한 온도관리기법을 다음과 같은 단계로 제안하고자 한다. 먼저 온도상승요인을 최소화하는 콘크리트의 배합비를 산정한다. 산정된 콘크리트의 열특성을 측정하기 위해 단열온도실험을 수행하여 각종 열특성상수와 단열온도 상승곡선식을 도출한다. 이와 같은 열특성치를 콘크리트 구조체에 적용하여 열응력해석을 수행한다. 이와 같은 열응력해석을 통하여 구조물의 분할타설높이에 따라 온도균열이 발생하지 않는 콘크리트 내외부의 온도차를 결정한다. 이때 열응력해석에 범용 유한요소 프로그램인 Diana을 사용한다. 콘크리트의 타설은 현장조건과 타설시점을 최대로 고려하고 양생방법으로 콘크리트 내외부의 온도차를 최소화하기 위해 이중단열효과가 있는 거푸집과 가열장비을 사용한다. 또한 콘크리트의 온도관리를 위하여 구조물 내외부에 온도게이지를 매립하고 30분마다 계측을 수행하면서 콘크리트 내외부 온도차가 허용 해석범위를 유지하도록 한다. 양생기간은 7-10일 정도를 유지한다. 전술한 온도관리기법을 통하여 완공후 수평정밀도가 기초의 허용침하량으로 환산하여 $1{\mu}m$ 인 고정밀도의 기계기초는 완벽하게 시공되었다. 따라서 매스콘크리트의 온도균열을 제어할 수 있는 시공방법으로 제안한다. 또한 매스콘크리트의 내외부 온도차를 단열온도실험과 온도해석으로부터 정한 값이내로 제어하고 충분한 양생관리를 병행하면 수화열에 의한 콘크리트의 온도균열을 최소화할 수 있을 것으로 기대한다.