• 한국자동차공학회논문집
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• 제12권2호
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• pp.24-31
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• 2004

A cylindrical constant volume combustion bomb is used to investigate the combustion characteristics and to analyzer the heat quantity of inhomogeneous charge methane-air mixture. To analyze the heat quantity, some definitions including the CHR ratio, the UHC ratio and the HL ratio are needed and are calculated. It is shown that the effect of stratification is not significant in case of the overall excess air ratio of 1.1, mainly due to the higher heat loss and lower thermal efficiency compared to those of homogeneous condition. In the case of the overall excess air ratio of 1.4, as the initial charge pressure decreases, the CHR ratio has been decreased while the HL ratio has been increased, Generally, as the initial charge pressure increases, the amount of injection mixture has been decreased and has resulted in lower mean velocity and turbulence intensity for injection mixture. Also, the injected mixture is too rich to result in mixing deficiency in combustion chamber. From these results, it could be possible to acquire the improvement of thermal efficiency and the reduction of heat loss simultaneously through the 2-stage injection in CNG direct injection engine.

• 유통과학연구
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• 제16권11호
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• pp.21-27
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• 2018

Purpose - This study investigates the financial ratio of savings banks and the effect of the ratio having influence upon bankruptcy by quantitative empirical analysis of forecast model to give material of better management and objective evidence of management strategy and way of advancement and risk control. Research design, data, and methodology - The author added two growth indexes, three fluidity indexes, five profitability indexes, and four activity indexes CAMEL rating to not only the balance sheets but also the income statement of thirty savings banks that suspended business from 2011 to 2015 and collected fourteen financial ratio indexes. IBMSPSS VER. 21.0 was used. Results - Variables having influence upon bankruptcy forecast models included total asset increase ratio and operating income increase ratio of growth index and sales to account receivable ratio, and tangible equity ratio and liquidity ratio of liquidity ratio. The study selected total asset operating ratio, and earning and expenditure ratio from profitability index, and receivable turnover ratio of activity index. Conclusions - Financial supervising system should be improved and financial consumers should be protected to develop saving bank and to control risk, and information on financial companies should be strengthened.

• 한국해양공학회지
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• 제12권1호
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• pp.65-75
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• 1998

The fracture resistance curve is one of most important and design techniques employed in nuclear pressure vessel structures. This study is to evaluate the J-R curve characteristics for the SA508C-3 by the unloading compliance method and load rato analysis. The effect of strain aging for the exponential correlation of the J-R curve in this metal are investigated at room temperature, 20$0^{\circ}C$ and 30$0^{\circ}C$. The load ratio analysis method can evaluate the J-R curve by using the simple tension load-displacement curve only without the repeat of the unloading and loading. Therefore, the analysis by the proposed load ratio method has a merit, in comparison with the unloading compliance method, which can measure the crack length without the precision measurement equipment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.479-482
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• 1999

The tension stiffening effect, which means the maintaining a part of stiffness after cracking of concrete in tensile, exists at a reinforced concrete member because of the concrete softening and bonding stress between cracks. It is required to consider it for precise analysis and evaluation o structural behavior, due to the possibility of discrepancy between the actual behavior and the analysis without considering the tension stiffening effect. Making and adopting a tension stiffening model is the most simple and effective way for considering it at nonlinear analysis which indicated the estimation from models and experimental results were similar each others. The comparisons on RC beam were, also performed in order to analyzed the influence of concrete strength and steel ratio into the structural behavior. They indicated that the results from analysis estimated quite closely to the test results at low steel ratio, however, overestimated at high steel ratio. The overestimation increase linearly as concrete strength or steel ratio increased.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.258-261
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• 2003

In this study, finite element analysis for multi-stage deep drawing process of rectangular configuration with extreme aspect ratio is carried out especially for the blank design. The analysis of rectangular deep drawing process with extreme aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profile. In order to solve the difficulties, numerical approach using finite element method is performed in the present analysis and design. A series of experiments for multi-stage rectangular deep drawing process are conducted and the deformed configuration is investigated by comparing with the results of the finite element analysis. Additionally, to minimize amount of removal material after trimming process, finite element simulation is applied for the blank modification. The analysis incorporates brick elements for a rigid-plastic finite element method with an explicit time integration scheme using LS-DYNA3D.

• 한국초등수학교육학회지
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• 제21권1호
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• pp.135-160
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• 2017

2009 개정 교육과정에 따른 6학년 수학 교과서가 현장에 적용된 이후, 1학기 비와 비율 단원이 다소 어려워 학생들에게 학습 부담으로 작용한다는 지적이 있어왔다. 이에 본 연구에서는 국내외 수학 교과서의 비와 비율 관련 내용을 종적 횡적으로 비교 분석하여 적절한 비와 비율 지도 방안을 모색하고자 하였다. 구체적으로 국내의 5차부터 현행 2009 개정 교육과정까지의 수학 교과서를 종적 분석 대상으로, 일본, 싱가포르, 홍콩, 핀란드 수학 교과서를 횡적 분석 대상으로 선정하였다. 분석기준은 각 교과서에 제시된 비와 비율 관련 학습 요소 및 지도 순서, 용어의 정의, 관련 개념의 도입 방법이다. 분석 결과를 토대로 우리나라 교육과정별 및 각 국가별로 비와 비율 관련 내용의 구현 여부 및 방법에 있어서 특징과 차이점을 파악하였다. 각각에 대한 구체적인 결과를 제시하고, 그에 기초하여 차기 교과서 개발 시비와 비율 단원 구성에 대한 몇 가지 시사점을 도출하였다.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.17-23
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• 2004

A cylindrical constant volume combustion bomb is used to investigate the combustion characteristics and to analyze the heat quantity of homogeneous charge methane-air mixture under various initial pressures, excess air ratios and ignition times. As the overall pressure increase, the values of maximum combustion pressure, maximum heat release rate and cumulative heat release have been increased. But it is not very meaningful to compare with some values such as maximum combustion pressure, maximum heat release rate and cumulative heat release for different overall pressure due to the different heat energy of supplied fuel. So the each value is needed to be compared with normalized value, which is divided by the entered fuel energy. To analyze the heat quantity, some definitions including the CHR ratio, the UHC ratio and the HL ratio are needed and are calculated. As the overall pressure increase, the CHR ratios and the UHC ratios have been decreased, while the HL ratios have been increased. The CHR ratio of 300 ms has the higher value than that of 10000ms, and the HL ratios of 300 ms have a lower value.

• 한국농공학회논문집
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• 제57권5호
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• pp.89-99
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• 2015

In this research, 1,032 data of precise safety inspection from 2004 to 2013 are gathered and constructed for finding effective safety inspection systems. Items are extracted from constructed data and factors for typology are decided with statistical method such as principle component analysis and cluster analysis. For factor decision, we extruded independent characteristics such as morphological and geographical characteristic, and deleted items which can be expressed by combination of independent characteristics. Four factors such as total storage, watershed ratio, levee length ratio, and spillway length ratio are extracted in this process. In cluster analysis, levee length ratio is excluded because it is not separated as cluster. Finally nine types of agricultural reservoir are extruded by total storage, watershed ratio, and spillway length ratio with frequency analysis.

• 대한기계학회논문집
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• 제14권3호
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• pp.656-663
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• 1990

본 연구에서는 이러한 해석적 근사해를 이용한 스터링기관의 최적설계조건에 관하여 취급하고자 한다. 단열해석의 결과를 대응하는 등온해석과 비교, 고찰함으로 써 방법에 따른 조건의 차이를 보이고 주요 설계인자의 성능에 미치는 영향을 규명한 다. 또한, 제인자에 따른 기관성능의 변화추이가 편리하게 표시될 수 이씨는 일종의 성능선도(performance map)를 작성하고자 한다.

• 환경분석과 독성보건
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• 제21권4호
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• pp.237-242
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• 2018

Strontium (Sr) commonly exists in rock, groundwater, soil, plants, and animals. The Sr isotope ratio offers important information as a tracer on nature because the Sr isotopic composition is not fractionated by any biological process in these ecosystems. Hence, Sr isotope ratio has been used in several studies on tracing the Sr source for contaminated sites and human migration. In this study, we developed a separation method for Sr content, and then improved Sr isotope analysis using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). A powdered rock standard (NIST 2710a) was used to determine the removal of interference elements (Rb and Ca) and the recovery rate of Sr content. The results ranged from 98% to 106%. Additionally, three standard samples (NBS 987, IAPSO and NIST 1486) were analyzed to evaluate the precision and accuracy of the results. The measured $^{87}Sr/^{86}Sr$ ratio for all the samples were consistent with the reported values, within an error. These results indicate that our established Sr separation and Sr isotope measurement methods are reliable and can hence be useful in the fields of environmental and forensic sciences.