• 터널과지하공간
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• 제2권1호
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• pp.123-151
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• 1992

“Norwegian Tunnelling in General" will cover the following subjects : - Short introduction to the geology of Norway - Major considerations in rock installations - Hydropower plants, roads, tunnels, oil and gas storage in rock, drinking water storage, sewage plants, frozen food storage, defence and civil defence projects, including sports arenas and swimming pools, etc.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2003년도 춘계 학술발표회 논문집
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• pp.445-455
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• 2003

Relatively high carbon-14 emissions, which occurred at PHWR Plant during 1998 and 1999, made the site staff to implement several operational improvements: 1) the frequency and volume of the moderator cover gas purging were reduced through increased $O_2$ additions to the cover gas, 2) the 'old' resin columns were not used during re-start of the reactor from outage, 3) efforts were made to minimize air ingress, 4) the maximum service time of moderator ion-exchange columns were restricted to about 80 days. Through the improvements, the carbon-14 emission from each PHWR reactor returned to the normal levels during the remainder of 1999 and during 2000. We carried out a special surveillance at W-1 and W-3 from September 2001 to August 2002 to properly evaluate ways to optimize the use of moderator ion exchange resins from a C-14 perspective. The surveillance showed that only data that provided an operational marker for deciding when to remove the IX-resin column is an observed increase in the C-14 stack emissions themselves. Also, it is shown that any increase over the rate of 0.4 Ci $month^{-1}$ for two consecutive weeks may be the indication for an ion-exchange resin column change, especially if the IX-resin column has been in service for more than 80 days.

• Design & Manufacturing
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• 제15권1호
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• pp.32-40
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• 2021

Mold design for in-mold coating was carried out to achieve simultaneous injection molding and two-color coating for car gas cap cover. The developed mold includes one core and three cavities which are composed of a substrate cavity and two coating cavities. To provide a sealing edge for complete seal during the second coating, the first coated material was used at the boundary between the first coating and the second one, and injection molded substrate was used at the parting line. The materials used were PC/ABS for substrate and 2-component Polyurea for coating. Through experiments, it was found that the suggested sealing edges were effective for complete seal during the second coating. In cavity pressure traces, there were three peaks caused by mold closing, coating-material injection and cleaning-piston advancement inside the mixing head. The cavity pressure increased with decreasing coating thickness.

• 한국기후변화학회지
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• 제8권4호
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• pp.329-337
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• 2017

In this study, land-use changes from 1990 to 2010 in Jeju Island by different approaches were produced and compared to suggest a more efficient approach. In a sample-based method, land-use changes were analyzed with different sampling intensities of 2 km and 4 km grids, which were distributed by the fifth National Forest Inventory (NFI5), and their uncertainty was assessed. When comparing the uncertainty for different sampling intensities, the one with the grid of 2 km provided more precise information; ranged from 6.6 to 31.3% of the relative standard error for remaining land-use categories for 20 years. On the other hand, land-cover maps by a wall-to-wall approach were produced by using time-series Landsat imageries. Forest land increased from 34,194 ha to 44,154 ha for 20 years, where about 69% of total forest land were remained as forest land and 19% and 8% within forest lands were converted to grassland and cropland, respectively. In the case of grassland, only about 40% of which were remained as grassland and most of the area were converted to forest land and cropland. When comparing land-cover area by land-use categories with land-use statistics, forest areas were underestimated while areas of cropland and grassland were overestimated. In order to analyze land use change, it is necessary to establish a clear and consistent definition on the six land use classification.

• 한국가스학회지
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• 제22권6호
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• pp.123-128
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• 2018

MDF목재에 처리제 즉, 방화락카, 수용성방염코트, 수용성우드커버 등을 MDF표면에 처리하여 연소시 열분해특성과 대기 유해가스 발생 특성을 대용량열분석기를 활용하여 실험한 결과 순수 MDF목재에 방화락카를 질량비로 0.11/11.55g을 처리한 후 열분해 및 연소가스 발생 특성을 살펴본 결과 방화락카를 처리한 경우 순수 MDF보다 연소시작시간이 다소 길어지고 연소온도가 약$340^{\circ}C$에서 $450^{\circ}C$로 올라가는 현상을 알 수 있었다. 그리고 수성방염코트를 처리한 MDF목재(PA2)의 열분해 및 연소가스발생 특성은 시료의 질량 비 0.13/11g에서 연소시작 시간과 온도가 약 26분 $260^{\circ}C$에서 약54분 $612^{\circ}C$로 변화를 보였다. 또한 상업적으로 판매되고 있는 수용성우드커버를 MDF에 0.13/11.55g을 처리하여 연소하였을 경우 급격한 중량변화는 $300^{\circ}C$에서 $370^{\circ}C$로 높아지는 경향을 보였고 약$500^{\circ}C$에서 2차 변화가 나타났다.

• 동력기계공학회지
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• 제15권3호
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• pp.65-69
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• 2011

This paper introduces the multi-coil eddy current sensor and its characteristic in magnetic material gas turbine rotor. In the past, magnetic particle inspection method was used for qualitative defect evaluation in magnetic material gas turbine rotor. And the ultrasonic inspection method was used for quantitative defect evaluation. Nowadays, eddy current method is used in magnetic gas turbine rotor inspection due to advanced sensor design technology. We developed multi-coil eddy current sensor for the rotor dovetail inspection. At first, rotor stress is analyzed for the determination of sensor position and number. The sensor coils are designed to cover the stress concentration area of rotor dovetail. We select optimum frequency according to material standard penetration data and experiment results. The rotor mock-up and artificial defects were made for the signal detection and resolution analysis of multi-coil eddy current sensor. The results show that signal detection and resolution capabilities are enhanced in comparison to the commercialized sensor enough for the gas turbine rotor inspection. So, this developed multi-coil eddy current sensor substituted for commercialized one and it applied in real gas turbine rotor inspection.

• Journal of Microbiology and Biotechnology
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• 제23권7호
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• pp.993-1003
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• 2013

Methanotrophs are the most important sink of $CH_4$, which is a more highly potent greenhouse gas than $CO_2$. Methanotrophic abundance and community diversity in cover soils from two typical semi-aerobic landfills (SALs) in China were detected using real-time polymerase chain reaction (real-time-PCR) and denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA genes, respectively. Real time-PCR showed that Type I methanotrophs ranged from $1.07{\times}10^6$ to $2.34{\times}10^7$ copies/g soil and that of Type II methanotrophs from $1.51{\times}10^7$ to $1.83{\times}10^8$ copies/g soil. The ratio of Type II to Type I methanotrophic copy numbers ranged from 5.61 to 21.89, indicating that Type II methanotrophs dominated in SAL. DGGE revealed that Type I methanotrophs responded more sensitively to the environment, changing as the community structure varied with different soil types and locations. Methylobacter, Methylosarcina, and Methylomicrobium for Type I, and Methylocystis for Type II were most prevalent in the SAL cover layer. Abundant interflow $O_2$ with high $CH_4$ concentration in SALs is the reason for the higher population density of methanotrophs and the higher enrichment of Type II methanotrophs compared with anaerobic landfills and other ecosystems, which proved a conclusion that increasing the oxygen supply in a landfill cover layer would greatly improve $CH_4$ mitigation.

• 한국전산유체공학회지
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• 제7권3호
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• pp.44-52
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• 2002

An analytic methodology was developed for free surface motions between liquid metal coolant and cover gas in order to calculate the phenomena of gas entrainment in hot pool surface through IHX EMP and reactor core. The methodology was setup by applying the first order VOF convection model to CFX4 general purpose fluid dynamics analysis code. The methodology was validated by applying it to an experimental apparatus designed for free surface motions of KALIMER reactor. The distributions of free surface calculated by the present methodology were almost coincident with the experimental data. The developed methodology was applied to the KALIMER reactor of full power operating condition. The shapes of the free surface were nearly uniform. From the results, it was found that the altitude of the free surface from the IHX inlet nozzle of KALIMER reactor is high enough not to affect to free surface motions of generating gas bubbles from the turbulent shear flows such as hydraulic jump and water falls.

• 한국산업융합학회 논문집
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• 제11권2호
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• pp.65-70
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• 2008

This study presents gas turbine cooling blade by using experimental and numerical works. The review cover researches related to cooling channels using finite element method in rotating blade. Also, the film cooling device and the heat transfer of the external surface of the blade are included. In addition, several methods to be used for the design of the blade, numerical method and experimental techniques are introduced. This work will contribute to improving the manufacturing of engine and the efficiency of gas turbine engines.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.107-110
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• 2008

엔진의 비행, 구성품 성능 오차, 엔진 시스템 인증 기준에 따라 결정된 시스템 시험영역을 기준으로 하는 터보펌프 가스발생기 연계시험 영역 설정을 하였다. 연계시험 작동점에 해당하는 연소기 압력 모사를 위한 배관 손실계수와 터빈 출력 조정을 위한 스로틀 밸브의 손실계수를 결정하였다.