• 한국가스학회지
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• 제27권3호
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• pp.98-107
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• 2023

본 연구에서는 인도네시아 북부 칼리만탄 섬 임의의 광구에서 취득한 석탄시료의 메탄가스 흡착량 측정 실험 결과를 활용하여 석탄층 메탄가스 저류층의 적정 생산정 간격 설계 연구를 수행하였다. 가스 생산성 분석결과, 랭뮤어 부피가 증가할수록 누적 가스생산량도 증가하며 이는 최대 가스 흡착량이 가스생산량에 직접적인 영향을 주는 것으로 판단된다. 또한 탄리투과도가 증가할수록 최대 가스생산량이 증가하고 배출수 기간(dewatering period)이 단축되는 것을 확인하였다. 특히 생산 영향영역이 넓어짐에 따라 누적 가스생산량은 증가하지만 단위 가스정 당 생산성 비교 시, 심도 2,000 ft, 영향영역 80-160 acres 사이에서 최대 누적 가스생산량이 산출되었다. 탄층 심도와 생산 영향영역을 동시에 고려하여 적정 생산정 심도 및 간격 산출 결과, 600-2,000 ft 사이에서 가스 생산성이 가장 높게 나타나며, 이때 생산정 간격은 80-160 acres 범위 내로 설계 하는 것이 적정하다. 따라서 탐사 시추 시 회수된 코어 시료 이외의 시추 자료가 없는 미개발 CBM 저류층에서 석탄시료의 가스흡착 실험 결과를 활용함으로써 탄층심도를 고려한 생산정 간격 설계를 수행할 수 있음을 제시하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.131.2-135
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• 1999

This study focuses on part quality and cycle times under gas-assisted injection molding(GIM) of housing molded parts. The position of the gas channel was estabished near to parting line at the end of last locations to fill. Applied hot runner and valve gates the gas was introduced directly into the mold cavity via gas pin. As GIM was applied the introduced directly into the mold cavity via gas pin. As GIM was applied the conclusion reached as follows. I) The quality of appearance was improved by reducing sink marks and scratches of texture ii) The realibility was improved by preventing warpages and reinforcing rigidity through optimum gas channel layout iii)It is enable to use small size of injection molding machine step by step as GIM was accomplished low pressure and reduced clamp forces against CIM iv)The productivity were improved by reducing cycle times.

• 소성∙가공
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• 제8권3호
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• pp.276-283
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• 1999

This study focuses on part quality and cycle times under gas-assisted injection molding (GIM) of box shape molded parts. The position of the gas channel was established near to parting line at the end of last locations to fill. Applied hot runner and valve gates, the gas was introduced directly into the mold cavity via gas pin. As GIM was applied, the conclusion reached as follows. I) The quality of appearance was improved by reducing sink marks and scratches of texture. ii) The reliability was improved by preventing warpages and reinforcing rigidity through optimum gas channel layout. iii) It is enable to use small size of injection molding machine step by step as GIM was accomplished low pressure and reduced clamp forces against CIM. iv) The productivity were improved by reducing cycle times.

• 대한기계학회논문집B
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• 제35권3호
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• pp.331-336
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• 2011

가스터빈 회전익이나 고정익 에어포일이 지닌 3 차원 곡면형상의 복잡성은 제조산업뿐만 아니라 재생정비 공정조차 어렵게 만드는 요인이다. CNC 기반기술을 이용한 공작기계와 공정 관련 프로그램들은 1990 년대부터 발달하기 시작한 컴퓨터 기술 덕분에 급속히 개발되면서 가스터빈 분야로 그 응용범위를 넓혀 나가고 있다. 특히 적응형 기능을 겸비한 5 축 동기 제어형 생산장비들은 유연한 공정능력과 손실된 부위의 형상 정보를 결정하는데 탁월한 성능을 보이고 있다. 8 축 동기제어가 가능하도록 구비된 로봇형 공정시스템은 매우 강력한 공정절차 표준화를 이룰 수 있게 할 뿐만 아니라 높은 생산성도 가져다 준다. 이 논문에서는 가스터빈 산업에서 CNC 기반기술의 응용현황을 검토하고, 부품 제조산업과 재생정비 산업의 공정비교와 개발사례를 통해 향후 전망을 제시한다.

• Journal of Welding and Joining
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• 제27권3호
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• pp.38-43
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• 2009

The optimization of the welding parameters was studied to maximize the weldability and minimize the amount of spatter in the MAG welding of automotive steel sheets under different shielding gas composition ratio. JS-EFSC, JS-SPHC steel plates and Ar mixture gases were used as a substrate and shielding gas for welding respectively. The five welding parameters were selected through preliminary experiments and their effects on the weldability were analyzed. Experiments were performed using the Taguchi experimental method. As results, appropriate range for welding could be achieved. Amount of spatter in 80%Ar+20%$CO_2$ shielding gas was 20% of that of $CO_2$welding. Therefore, in terms of high productivity and welding cost, Ar mixture gas(80%Ar+20%$CO_2$) was recommended as a shielding gas for application of MAG process, indicating the low spatter and good weld quality.

• 한국미생물·생명공학회지
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• 제24권5호
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• pp.597-603
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• 1996

This study was carried out to examine degradation characteristics of microalgae Chlorella vulgaris in methane fermentation. We measured COD and VS reduction, gas and methane productivity, VFA (volatile fatty acid), respectively. Then we calculated material balance and hydrolysis rates in soluble and solid material. The substrate concentration was controlled from 14 gCOD$_{cr}$/l to 64 gCOD$_{cr}$/l in batch cultures, and HRT (hydraulic retention time) controlled from 2 days to 30 days in continuous experi- ments. The results were as follows. In batch culture, accumulated gas productivity increased with the increase of the substrate concentration. The SS and VSS was removed all about 30% increase of substrate concentration and the most of the degradable material removed during the first 10 days. The curve of gas and methane production rate straightly increased until substrate concentration is 26 gCOD$_{cr}$/l. In continuous culture experiments, the removal rates at HRT 10days were 20% for total COD and TOC, respectively. At longer HRT, there was no increase in the removal efficiency. At HRT 15 days, the removal rates were 30% for SS and VSS, respectively. Soluble organic materials were rapidly degraded, and so there was no accumulated. Soluble COD concentration was not increase regardless of HRT-increasing. That meaned the hydrolysis was one of the rate-limiting stage of methane fermentation. The first-order rate constants of hydrolysis were 0.23-0.28 day$^{-1}$ for VSS, and 0.07-0.08 day$^{-1}$ for COD.

• The Korean Journal of Ecology
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• 제24권6호
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• pp.335-339
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• 2001

The dynamic model was developed to simulate the photosynthetic rate of Phragmites communis stands in coastal ecosystem. The model was composed of the compartments of both climatic and biological variables. The former were photosynthetic photon flux density(PPFD), daily maximum- and minimum-temperature. The latter were combinations of the specific physiological responses of plant organs with the biomass of each organs. The PPFD and air temperature were calculated and using those values, gas exchange rate of each plant organ was calculated at every hour. The carbon budget was constructed using the modelled predictions. Analysis of annual productivity and fluxes showed that yearly gross population productivity, yearly population respiration and yearly net population productivity were 33.4, 21.3 and 12.1 $CO_2ton{\cdot}ha^{-2}{\cdot}yr^{-1}$, respectively. The final result was tested over two stands, produced promising predictions with regards to the levels of production attained. The model can be used to determine production potential under given climatic conditions and could even be applied to plant canopies with analogous biological characteristics.

• 한국가스학회지
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• 제21권2호
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• pp.50-57
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• 2017

셰일 저류층은 매우 미세한 입자로 구성되어 있으며, 공극의 크기가 나노미터에 불과하다. 본 연구에서는 셰일 암체에서의 크누센 확산영향, 균열대 및 암체에서 상대투과도, 셰일가스 생산에 따른 균열투과도 변화를 적용하여 그 영향을 분석하였다. 이를 위해 캐나다 혼리버 셰일 저류층 모델을 구축하였으며, 장기간 생산을 하는 셰일 저류층에서의 확산 및 선행연구에서 제안된 균열대 상대투과도를 적용하여 생산성에 미치는 영향을 분석하였다. 그리고 암체와 균열대에서 동생수가 생산성에 미치는 영향과 저류층 생산에 따른 균열투과도 변화를 적용하여 생산성을 평가하였다.

• Geomechanics and Engineering
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• 제29권2호
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• pp.145-154
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• 2022

Complex geological conditions have a great influence on the mining of coalbed methane (CBM), which affects the extraction efficiency of CBM. This investigation analyzed the complicated geological conditions in the Liujia CBM block of Fuxin. A geological model of heterogeneities CBM reservoirs was established to study the influence of strike direction of igneous rocks and fault structures on horizontal well layout. Subsequently, the dual-porosity and dual-permeability mathematical model was established, which considers the dynamic changes of porosity and permeability caused by gas adsorption, desorption, pressure change. The results show that the production curve is in good agreement with the actual by considering gas seepage in matrix pores in the model. Complicated geological structures affect the pressure expansion of horizontal wells, especially, the closer to the fault structure, the more significant the effect, the slower the pressure drop, and the smaller the desorption area. When the wellbore extends to the fault, the pressure expansion is blocked by the fault and the productivity is reduced. In the study area, the optimal distance to the fault is 70 m. When the horizontal wellbore is perpendicular to the direction of coal seam igneous rock, the productivity is higher than that of parallel igneous rock, and the horizontal well bore should be perpendicular to the cleat direction. However, the well length is limited due to the dense distribution of igneous rocks in the Liujia CBM block. Therefore, the horizontal well pumping in the study area should be arranged along the direction of igneous rock and parallel plane cleats. It is found that the larger the area surrounded by igneous rock, the more favorable the productivity. In summary, the reasonable layout of horizontal wells should make full use of the advantages of igneous rock, faults and other complex geological conditions to achieve the goal of high and stable production.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.136.2-136.2
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• 2011

A dynamic simulation study on SCR process in GTL process was carried out in order to find optimum operation conditions for pilot plant operation. Optimum operating conditions for SCR synthesis gas process were determined by changing operation variables such as feed temperature and pressure. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. The effect of temperature and pressure on synthesis gas process $H_2$/CO ratio were mainly examined. Dynamic simulation results were fed back to feed operation condition for optimizing productivity, especially for appropriate condition to FT (Fischer-Tropsch) synthesis unit.