• 한국화재소방학회논문지
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• 제17권1호
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• pp.26-32
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• 2003

Halon대체 소화제로 쓰이는 불활성 기체 중 Ar, $N_2$, $CO_2$의 단일 성분일 때의 물성(포화압력, 밀도, 점도)에 관한 실험식을 구하였다. 문헌에서 얻은 실험 값을 이용하여 다항식 등의 회귀분석에 의해서 실험식을 얻었다. 포화압력은 온도에 대하여 각각 2차와 3차의 실험식으로 표시하였다. 밀도는 Ar, $N_2$는 온도에 대한 1차 함수로 표시하였고, $CO_2$는 온도에 대하여 각각 2차와 3차의 실험식으로 표시하였다. 점도는 온도에 대한 지수함수로 표시하였다. 이들 실험식을 이용하여 단일 성분일 때의 상태를 알 수 있다.

• 한국산업정보학회논문지
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• 제20권4호
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• pp.25-37
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• 2015

The early studies indicated that the firm with monopoly power is likely to engage in X-inefficiency such as a managerial slack. The reflection of the X-inefficiency theory has led to the issue that the public sector may be more inefficient than the private sector. In Korea like other many countries the electricity gas water service which can be considered as natural monopoly have been provided mostly by the public sector. In order to provide the empirical evidence to the argument that the public sector may be more inefficient than the private sector this paper estimated the four types of Solow residual which is called the total factor productivity in the electricity gas water service industry with the associated empirical model and compared its productivity with one in the manufacturing industry. The empirical results do not support the argument that the public sector may be more inefficient or less productive than the private sector.

• Wind and Structures
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• 제16권6호
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• pp.603-616
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• 2013

This study is aimed at formulating an empirical equation for the across-wind fluctuating moment and spectral density coefficient, which are needed to estimate the across-wind dynamic responses of tall buildings, as a function of the side ratios of buildings. In order to estimate an empirical formula, wind tunnel tests were conducted on aero-elastic models of the rectangular prisms with various aspect and side ratios in turbulent boundary layer flows. In this paper, criteria for the across-wind fluctuating moment and spectral density are briefly discussed and the results are analyzed mainly as a function of the side ratios of the buildings. Finally, empirical formulas for the across-wind fluctuating moment coefficient and spectral density coefficient according to variation of the aspect ratio are proposed.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 추계학술발표회
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• pp.653-654
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• 2005

• 에너지공학
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• 제8권2호
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• pp.317-324
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• 1999

This study suggests the effectiveness of an "extended" power system evaluation methodology based on LCA and energy input-output analysis techniques. This "extended" evaluation methodology is designed to incorporate total energy system costs through fuel cycle and external costs, including CO$_2$abatement cost. As an empirical test, we applied the methodology to orimulsion-fired power generation technology and found that orimulsion could be considered as in attractive base-load power generation fuel in terms of economic and environmental aspects, compared to conventional coal-fired power plant.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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• pp.90-94
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• 2001

A Waterjet has been widely used for the propulsion of various speed range of marine vehicles due to its many advantages compared with the conventional screw propellers. In this paper, a power prediction based on momentum flux method is presented for the preliminary estimation of required power and selection of propulsion system for the waterjet driven craft. A theoretical basis of the mechanism of the waterjet is given and some of the empirical formulas are given as well. Finally the influence of intake type and nozzle exit velocity on the efficiency will be discussed.

• 한국정밀공학회지
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• 제33권2호
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• pp.157-163
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• 2016

The empirical evaluation of grid-connected tidal current generation system is presented in this paper. The Ul-dol-mok in Jin-do has been estimated to have tidal power of 1GW. In order to experiment, HAT (Horizontal Axis Turbine) 3-blade and 20kW grid-connected tidal current generation system was established at Ul-dol-mok in Jin-do. To generate power of generator, the speed reference of the PMSG is generated from the Cp curve and TSR (Tip Speed Ratio) of the designed turbine. The control of the converter connected to the grid is controlled to regulate unity power factor. The result showed that the turbine efficiency and system efficiency is 37 % and 31 %. This was achieved that target rate is 30 %, 20 %, respectively.

• 인지과학
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• 제27권4호
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• pp.541-572
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• 2016

인과 추론은 심리학에서는 물론 최근 베이스 접근법을 취하는 인지과학자들에 의해서도 활발히 연구되고 있다. 본 연구는 인과추론에 대한 대표적 심리학 이론인 힘-확률대비이론(a power probabilistic contrast theory of causality)을 중심으로 인과 추론의 최근 동향을 개관하고자 한다. 힘-확률대비이론에서는, 원인은 결과를 일으키거나 억제하는 힘(power)인데, 이 힘은 특정한 조건하에서 통계적 상관을 통해 파악될 수 있다고 가정한다. 본 논문에서는 이 이론에 대한 초기의 경험적 지지 증거를 먼저 살펴본 다음, 베이스 접근에 기반을 둔 이론과의 쟁점을 명확히 하고, 원인은 맥락에 무관하게 동일하게 작동한다는 인과적 불변성 가정(causal invariance hypothesis)을 중심으로 한 보다 최근의 연구 결과를 소개하고자 한다. 이 연구들은 종래의 통계적 접근법으로는 잘 설명되지 않는 결과를 제시함으로써, 철학, 통계학, 그리고 인공 지능 등과 같은 인접 분야에 인과성에 대한 힘 이론을 진지하게 고려할 것을 촉구하고 있다.

• Interdisciplinary Bio Central
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• 제2권2호
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• pp.4.1-4.6
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• 2010

The most common type of microarray experiment has a simple design using microarray data obtained from two different groups or conditions. A typical method to identify differentially expressed genes (DEGs) between two conditions is the conventional Student's t-test. The t-test is based on the simple estimation of the population variance for a gene using the sample variance of its expression levels. Although empirical Bayes approach improves on the t-statistic by not giving a high rank to genes only because they have a small sample variance, the basic assumption for this is same as the ordinary t-test which is the equality of variances across experimental groups. The t-test and empirical Bayes approach suffer from low statistical power because of the assumption of normal and unimodal distributions for the microarray data analysis. We propose a method to address these problems that is robust to outliers or skewed data, while maintaining the advantages of the classical t-test or modified t-statistics. The resulting data transformation to fit the normality assumption increases the statistical power for identifying DEGs using these statistics.

• 동력기계공학회지
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• 제18권5호
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• pp.22-27
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• 2014

The objectives of this paper are to obtain an empirical equations regarding the correlations between heat transfer and pressure drop of oval fin-tube heat exchanger having large diameter using wilson plot method. It was difficult to find any recommendable heat transfer and friction factor correlation available for our large diameter experimental cases. Overall heat transfer coefficients are composed of the heat transfer coefficients both inside and outside tubes. The resulting empirical correlations for the Nui and f-factor are given as $Nu_i=0.0146Re^{0.809}Pr^{0.3}$ and $f=4.366Re^{-0.64}$, respectively. The empirical correlations of the Nui and f-factors were developed for the large diameter oval finned-tube heat exchanger as a function of the Reynolds number. As the EG(Ethylene glycol) and air flow rate increases, the heat transfer rate and pressure drop is increased largely.