• 한국컴퓨터정보학회논문지
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• 제26권4호
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• pp.223-229
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• 2021

본 연구는 공공기관의 부채 규모를 결정하는 요인이 무엇인지 검증하는 것을 목적으로 한다. 구체적으로 본 연구는 공공기관의 내부적 요인으로써 비효율적 경영이 부채비율에 미치는 영향을 분석한다. 비효율적 경영을 대리하는 변수로는 총원가, 급여 규모, 복리후생비 규모를 고려하였다. 본 연구의 분석결과는 다음과 같다. 첫째, 총원가 변수는 공공기관의 부채비율과 통계적으로 유의한 양의 관계를 나타내었다. 이는 총원가가 큰 기업일수록 부채 규모가 증대됨을 의미한다. 둘째, 급여 규모와 복리후생비 규모는 공공기관의 부채비율과 통계적으로 유의한 관련성을 나타내지 않았다. 이들 결과는 공공기관의 방만한 경영과 비효율적 운영이 부채 규모를 증대시킨다는 일각의 우려에 대해 답변을 대신할 수 있는 실증적 결과라 하겠다.

• Wind and Structures
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• 제34권1호
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• pp.137-149
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• 2022

In this paper, the fluctuating lift and drag forces on 5:1 rectangular cylinders with two different geometric scales in three turbulent flow-fields are investigated. The study is particularly focused on understanding the influence of the ratio of turbulence integral length scale to structure characteristic dimension (the length scale ratio). The results show that both fluctuating lift and drag forces are influenced by the length scale ratio. For the model with the larger length scale ratio, the corresponding fluctuating force coefficient is larger, while the spanwise correlation is weaker. However, the degree of influence of the length scale ratio on the two fluctuating forces are different. Compared to the fluctuating drag, the fluctuating lift is more sensitive to the variation of the length scale ratio. It is also found through spectral analysis that for the fluctuating lift, the change of length scale ratio mainly leads to the variation in the low frequency part of the loading, while the fluctuating drag generally follows the quasi-steady theory in the low frequency, and the slope of the drag spectrum at high frequencies changes with the length scale ratio. Then based on the experimental data, two empirical formulas considering the influence of length scale ratio are proposed for determining the lift and drag aerodynamic admittances of a 5:1 rectangular cylinder. Furthermore, a simple relationship is established to correlate the turbulence parameter with the fluctuating force coefficient, which could be used to predict the fluctuating force on a 5:1 rectangular cylinder under different parameter conditions.

• Communications for Statistical Applications and Methods
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• 제4권2호
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• pp.427-434
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• 1997

The purpose of this paper is to discuss distribution-free tests of hypothesis that the random samples are identically distributed against the epidemic alternative. But most tests that have been considered are depended only on specific null distribution. Two nonparametric tests are considered and compared with a likelihood ratio test by the empirical powers.

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.627-633
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• 2020

The study attempts to analyze the impact of firm's risk on capital structure in the context of seasonal and non-seasonal businesses. We use two independent variables namely credit risk and systematic risk and one dependent variable to explore this connection. Sugar sector is taken as seasonal while the textile sector as non-seasonal businesses. The panel data of twenty-five firms from each sector are taken ranging for the period of 2012 to 2019 which has been retrieved from their annual reports for empirical analysis of the study. The results reveal the negative impact of credit risk on capital structure in both types of businesses. Increasing (decreasing) one point of credit risk causes a decrease (increase) leverage ratio by 0.27 points for seasonal while increasing (decreasing) one point of credit risk causes to decrease (increase) leverage by 0.15 points for non-seasonal businesses. Furthermore, the study shows positive impact of systematic risk on leverage ratio in non-seasonal business and no impact in seasonal business. Any increase (decrease) in the systematic risk causes an incline (decline) leverage ratio by 2.68 units for non-seasonal businesses. The study provides a guideline to managers for risk management in businesses. The research focusses on theoretical as well as managerial and policy implications on risk management in businesses.

• Carbon letters
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• 제28권
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• pp.72-80
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• 2018

In this study, an empirical relationship between the energy band gap of multi-walled carbon nanotubes (MWCNTs) and synthesis parameters in a chemical vapor deposition (CVD) reactor using factorial design of experiment was established. A bimetallic (Fe-Ni) catalyst supported on $CaCO_3$ was synthesized via wet impregnation technique and used for MWCNT growth. The effects of synthesis parameters such as temperature, time, acetylene flow rate, and argon carrier gas flow rate on the MWCNTs energy gap, yield, and aspect ratio were investigated. The as-prepared supported bimetallic catalyst and the MWCNTs were characterized for their morphologies, microstructures, elemental composition, thermal profiles and surface areas by high-resolution scanning electron microscope, high resolution transmission electron microscope, energy dispersive X-ray spectroscopy, thermal gravimetry analysis and Brunauer-Emmett-Teller. A regression model was developed to establish the relationship between band gap energy, MWCNTs yield and aspect ratio. The results revealed that the optimum conditions to obtain high yield and quality MWCNTs of 159.9% were: temperature ($700^{\circ}C$), time (55 min), argon flow rate ($230.37mL\;min^{-1}$) and acetylene flow rate ($150mL\;min^{-1}$) respectively. The developed regression models demonstrated that the estimated values for the three response variables; energy gap, yield and aspect ratio, were 0.246 eV, 557.64 and 0.82. The regression models showed that the energy band gap, yield, and aspect ratio of the MWCNTs were largely influenced by the synthesis parameters and can be controlled in a CVD reactor.

• 한국터널지하공간학회 논문집
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• 제15권4호
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• pp.443-453
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• 2013

본 연구에서는 주방식 지하구조물의 안정성을 좌우하는 무지보 암주의 거동을 수치해석에 의해 검토하였다. 암주의 강도를 추정하기 위해 기존 연구들에서 제시된 경험식들을 수치해석 결과와 비교 분석하였다. 분석 결과, 암주의 폭이 높이보다 커질수록 암주 강도와 암반 강도의 비율이 증가하여 안정성 확보에 유리한 것으로 나타났다. 특히, 본 연구의 해석조건에서는 암주의 폭과 높이의 비율이 약 1.5 이상이면 무지보 암주의 강도가 암반의 압축강도보다 크게 얻어졌다. 또한 암주의 형상 조건에 따라 수치해석 결과와 유사한 결과를 산출하는 경험식이 다소 상이하여, 현장자료 기반의 경험식을 활용하기 위해서는 암주의 형상 조건에 따라 적합한 경험식을 적용하는 것이 필요하다.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.20-27
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• 2003

In this paper, the fuel transport characteristics during transient condition was studied by using a Fast Response Flame Ionization Detector(FRFID). The quantitative measurement method for the inducted fuel mass into cylinder is studied. The inducted fuel mass into the cylinder was estimated by using calculated air-fuel ratio by hydrocarbon concentration of cylinder and air flow model. In order to estimate the transportation of injected fuel from the intake port into cylinder, the wall wetting fuel model was used. The two coefficient $\alpha$,$\beta$) of the wall-wetting fuel model was determined from the measured fuel mass that was inducted into the cylinder at the first cycle after injection cut-off To reduce an air/fuel ratio fluctuation during rapid throttle opening, the appropriate fuel injection rate was obtain from the wall wetting model with empirical coefficients. Result of air/fuel ratio control, air/fuel excursion was reduced.

• 통상정보연구
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• 제11권1호
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• pp.139-155
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• 2009

This study investigates empirically the export competitiveness of Korea and Japan in America by calculating 4 indexes such as market share index(MSI), export similarity index(ESI), market comparative adventage index(MCAI) and market share expansion ratio(MSER)-export similarity deepening ratio(ESDR). The empirical finding of this analysis shows that Korea is competitive in the labor-intensive products and Japan in the technology-intensive products. This result also meets the general understandings that Japan is superior to Korea in the export competitiveness such as value added of goods, etc. Therefore, in order to strengthen the export competitiveness of Korea in the US market, it's desirable for our firms and government to improve the quality of product ranges by developing technologies focused on the higher value-added products.

• 재무관리연구
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• 제24권2호
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• pp.183-206
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• 2007

The price-dividend ratio is one of the most frequently used financial variables to predict long-horizon stock return. However, the persistency of the price-dividend ratio is found to cause the spuriousness of the stock return prediction regression. The stable relationship between the stock price and the dividend, however, seems to weaken after World War II and to experience structural break. In this paper, we identify a structural change in the cointegrating relationship between the log of the stock price and the log of the dividend. Confirming a structural break in 1962, we subdivide the sample and apply the fully modified estimator to correct for the nonstationarity of the regressor. With the subdivided sample, we exercise the nonparametric bootstrap procedure to derive the empirical distribution of the test statistics and fail to find return predictability in each subsample period.

• Structural Engineering and Mechanics
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• 제52권4호
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• pp.739-753
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• 2014

There have been many packages that can be employed to analyze plane frames. However, because most structural analysis packages suffer from closeness of system, it is very difficult to integrate it with an optimization package. To overcome the difficulty, we proposed a possible alternative, DAMDO, which integrate Design, Analysis, Modeling, Definition, and Optimization phases into an integrative environment. The DAMDO methodology employs neural networks to integrate structural analysis package and optimization package so as not to need directly to integrate these two packages. The key problem of the DAMDO approach is how to generate a set of reasonable random designs in the first phase. According to the characteristics of optimized plane frames, we proposed the ratio variable approach to generate them. The empirical results show that the ratio variable approach can greatly improve the accuracy of the neural networks, and the plane frame optimization problems can be solved by the DAMDO methodology.