• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.777-783
• /
• 2006

The coarse grained materials are used in various construction field such as express way back fill, Dam etc. Especially, for dam construction, a huge mount of rock fill materials are needed, so around domestic stony mountains are generally developed to produce materials. Not an accurate theory, but design criteria is based on empirical factors that were constructed in advance for design of dam especially Concrete Face Rockfill Dam(CFRD). Considering the post facts, the modified design criteria are essential in the future with more theoretical and experimental ways. In this study, large scale direct shear tests are performed with various relative density conditions on coarse grained material of Yecheon area to compare test results and general CFRD design factors.

• Nuclear Engineering and Technology
• /
• 제29권4호
• /
• pp.310-319
• /
• 1997

A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized into the average (membrane) stress, the linearly varying (bending) stress and the peak stress through the thickness. The resulting stresses are interpreted per Section III of the ASME Boiler and Pressure Vessel Code from which the Primary(B$_1$), Secondary(C$_1$) and Peak(K$_1$) stress indices for pressure, the Primary (B$_2$), Secondary(C$_2$) and Peak(K$_2$) stress indices for moment are developed. Based on the comparison between stress value by stress indices derived in this paper and stress value represented by the ASME Code Case N-391-1, the empirical equations for stress indices are effectively used in the piping stress analysis. Therefore, the use of empirical equations can simplify the procedure of evaluating the local stress in the piping design stage.

• 한국군사과학기술학회지
• /
• 제15권5호
• /
• pp.705-711
• /
• 2012

The purpose of this study is to develop the model to estimate the penetration rate of metal under a high power continuous wave laser irradiation. To estimate it, an empirical modeling is more practical when the penetration phenomena of metal by laser irradiation is too complex to be analyzed by the numerical simulation. When several methods published earlier were applied to our results, we found out that their methods were not appropriate as the model. Therefore, we suggested the new empirical method considering effective intensity as a key variable. As a result, we confirmed that the new method was effective to model the penetration rate of SUS304 metal and expected that it could be available to other metals.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.554-558
• /
• 2004

In this paper, we introduce noise prediction program of HVAC system to assist low-noisy design of ship's cabin. The developed program calculates sound power levels at HVAC components considering primary and secondary noise generated by fan and duct element, duct element noise attenuation, and duct break-in noise based on the authentic empirical method suggested by NEBB and acoustic power balancing method. Sound pressure level at cabin with or without ceiling system is evaluated by the diffuse-field theory considering diffuser and duct break-out sound powers. Moreover, the program provides intuitive pre- and post-processors using modem GUI functions to help efficient modeling and evaluation of cabin and HVAC component noise. To validate the accuracy and convenience of the program, noise prediction for a HVAC system is demonstrated.

• 한국화재소방학회논문지
• /
• 제16권2호
• /
• pp.51-58
• /
• 2002

몬트리올 의정서에 의해서 규제받는 Halon-1301과 대체 물질중의 하나인 $CO_2$의 물성(밀도, 점도, 엔탈피)의 실험식을 구하였다. 문헌에서 얻은 실험값을 이용하여 온도에 대한 회귀분석에 의해서 실험식을 얻었다. 압축인자를 이용하여 온도에 대한 2차 함수로서 밀도에 관한 실험식을 제안하였다. 점도는 온도에 대한 지수함수로 표시되며, 보정인자를 사용하여 사용 온도범위를 확장하였다. 엔탈피는 열용량과 마찬가지로 온도에 대한 2차 함수로 정의하여 나타내었다. 본 연구에서 제안된 위의 실험식의 상관계수는 0.99 이상이었다.

• 한국화재소방학회논문지
• /
• 제16권3호
• /
• pp.16-25
• /
• 2002

소화제인 Freon-23과 몬트리올 의정서에 의해서 규제받는 CFC의 대체 물질인 HFC-227ea의 물성(포화압력, 밀도, 점도, 엔탈피, 표면장력)에 관한 실험식을 구하였다. 문헌에서 얻은 실험값을 이용하여 다항식등의 회귀분석에 의해서 실험식을 얻었다. 포화압력은 온도에 대하여 각각 3차와 2차의 실험식으로 표시하였다. 압축인자와 포화압력을 이용하여 온도에 대한 밀도에 관한 실험식을 제시하였다. 점도는 온도에 대한 지수함수로 표시하였고, 엔탈피는 열용량과 마찬가지로 온도에 대한 2차 함수로 정의하여 나타내었다. 표면장력에 대해서는 간단한 1차 온도에 대한 선형적인 관계가 있었다.

• 한국분무공학회지
• /
• 제16권4호
• /
• pp.176-185
• /
• 2011

The empirical correlations for the prediction of penetration height of liquid jet in crossflow are reviewed and classified in this study. Around thirty different correlations had been proposed by many investigators. It has generally known that the penetration height of a liquid jet in a cross-flow is a function of the liquid to air momentum flux ratio and the normalized downstream distance from the injector. However, several researchers incorporated the Weber number, liquid-to-water or air viscosity ratio, pressure ratio or Reynolds number, temperature ratio in the empirical correlations. The existing correlations can be grouped as correlations in a power-law, logarithmic, and exponential forms, respectively. Correlations in a power-law form can be further classified as three groups such as basic form, Weber number form and other parameters form. It should be pointed out that correlations in a logarithmic form in terms of Weber number or any other parameters could not be found. Universal correlation has still not been established due to the significant discrepancies between various correlations suggested to date. Several of the studies reported the significant discrepancies of predicted values by the existing correlations. The possible reasons for discrepancies will be summarized as measurement technique, assumptions made in defining terms in the liquid to air momentum flux ratio, difficulties in defining the boundaries of the liquid jets, and nozzle/injector geometry. Evaluation of validity for the correlations proposed recently by several investigators is essentially required. Those include eight power-law forms, two logarithmic forms, and one exponential form.

• 전기학회논문지
• /
• 제65권5호
• /
• pp.836-842
• /
• 2016

When an accident occurs in the nuclear power plant, the faulted information might mislead to the high possibility of aggravating the accident. At the Fukushima accident, the operators misunderstood that there was no core exposure despite in the processing of core damage, because the instrument information of the reactor water level was provided to the operators optimistically other than the actual situation. Thus, this misunderstanding actually caused to much confusions on the rapid countermeasure on the accident, and then resulted in multiplying the accident propagation. It is necessary to be equipped with the function that informs operators the status of instrument integrity in real time. If plant operators verify that the instruments are working properly during accident conditions, they are able to make a decision more safely. In this study, we have performed various tests for the fault detection sensitivity of an data-driven empirical model to review the usability of the model in the accident conditions. The test was performed by using simulation data from the compact nuclear simulator that is numerically simulated to PWR type nuclear power plant. As a result of the test, the proposed model has shown good performance for detecting the specified instrument faults during normal plant conditions. Although the instrument fault detection sensitivity during plant accident conditions is lower than that during normal condition, the data-drive empirical model can be detected an instrument fault during early stage of plant accidents.

• Journal of Korea Trade
• /
• 제23권6호
• /
• pp.131-144
• /
• 2019

Purpose - The purpose of this study was to investigate market power of soybeans exported by the United States to Korea. Particularly, this paper considered dichotomous characteristics of genetically modified (GM) soybeans and non-GM soybeans and conducted empirical analysis of these two segregated soybean markets to understand key tenets of market power in international soybean trade. Design/methodology - The difference in market power between GM and non-GM soybeans was analyzed using Residual Demand Elasticity (RDE) and Residual Supply Elasticity (RSE) models over the period of 2008~2018. RDE and RSE models under an imperfect competition condition were used to estimate market margins and determine whether GM and non-GM exporters or importers exercised market power in the destination market. Findings - Empirical results suggested that the U.S. had a market power on both GM and non-GM soybean exports. GM exports had greater market power than non-GM exports (14% vs. 9%). By contrast, Korea showed an inability to grab market margin or exert market power in soybean imports. Both export supply by the U.S. and import demand by Korea were found to be more responsive to price changes of GM soybeans than to prices changes of non-GM soybeans. This might be due to a self-interested, profit-seeking strategy by the exporter and many concerned consumers regarding potential adverse effects of GMOs in the importing country. Originality/value - This paper fills the literature gap by exploiting market power in both GM and non-GM markets with explicit consideration of price correlations between GM and non-GM soybeans in Korea. A number of existing studies have provided evidence for market power broadly embedded in international commodity trade. However, studies focusing on Korean markets are limited. No study has explored the country's soybean trade. Furthermore, the majority of prior studies have almost exclusively focused on the market power from a standpoint of exporting countries without discussing importers' market structure. This paper also sought to understand potentially distinguished patterns of market power between GM and non-GM markets.

• 한국화재소방학회논문지
• /
• 제17권2호
• /
• pp.43-49
• /
• 2003

대체 소화제로 사용되는 불활성 기체 중 Ar, $N_2$, $CO_2$에 대한 혼합물에서의 물성(포화압력, 밀도, 점도)에 관한 실험식을 구하였다. Mixing rule에 의해 계산한 값을 이용하여 다항식 등의 회귀분석에 의해서 실험식을 얻었다. 포화압력은 온도에 대하여 1차 실험식으로 표시하였다. 압축인자와 포화압력을 이용하여 온도에 대한 밀도에 관한 실험식을 제시하였다. 점도는 온도에 대한 지수함수로 표시하였다. Ar, $N_2$, $CO_2$혼합물의 조성이 40/50/10(mol. %)에서 열역학적 실험식을 구하였다.