• Communications for Statistical Applications and Methods
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• v.3 no.2
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• pp.227-237
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• 1996

비중심 ${\chi}^2$분포의 누적분포함수의 계산은 ${\chi}^2$검정에서 요구되고 있는 새로운 접근방법으로 신경망 이론을 적용하기 위하여 입력층의 입력노드가 세개, 출력증의 축력노드가 한개 그리고 한개의 은닉층으로 구성된 다층 퍼셉트론 네트워크부터 역전파 알고리즘을 개발하여 비중심${\chi}^2$분포의 확률계산을 시도하였다. 정확성과 계산속도를 고려하여 기존의 방법과 비교한 결과 효율적임을 알 수 있다.

• 한국IT서비스학회:학술대회논문집
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• 2007.11a
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• pp.210-215
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• 2007

본 연구는 한국증권선물거래소 유가증원시장에 상장된 정보통신제조업체를 대상으로 기술혁신 결정요인을 분석하였다. 연구모형은 Romer(1990)에서 시작되는 내생적 경제성장 모험의 지식생산함수를 이용하였으며, 기술혁신의 측정은 특허청의 기업별 특허출원수를 활용하였다. 분석결과 연구개발집약도, 기술수준, 수출비중, 자본집약도는 기술혁신에 양(+)의, 반면 관계사 매입.매출비중은 기술혁신에 음(-)의 유의한 영향을 미치는 것으로 나타났다. 특히 관계사 매출비중보다 매일비중이 자사의 기술혁신에 보다 나쁜 영향을 미침을 확인하였다. 이는 경영자에게 자사의 기술혁신을 위해 무엇보다 관계사 매입비중을 감소시킬 것을 보여준다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.483-490
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• 1997

The evalution of the cumulative distridution function of the noncentral $X^2$ distribution required in approxi-mate determination of the $X^2$ test. Many approximations to the cumulative distribution function of the noncentral $X^2$ distribution have been suggested. However, in selecting an approximations both simplicity and accuracy should be considered. In this note we compared various approximations in terms of accuracy and efficiency.

• The KIPS Transactions:PartB
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• v.9B no.3
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• pp.271-276
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• 2002

The test statistic in ANOVA tests has a single or doubly noncentral F distribution and the noncentral F distribution is applied to the calculation of the power functions of tests of general linear hypotheses. Although various approximations of noncentral F distribution are suggested, they are troublesome to compute. In this paper, the calculation of noncentral F distribution is applied to the neural network theory, to solve the computation problem. The neural network consists of the multi-layer perceptron structure and learning process has the algorithm of the backpropagation. Using fables and figs, comparisons are made between the results obtained by neural network theory and the Patnaik's values. Regarding of accuracy and calculation, the results by neural network are efficient than the Patnaik's values.

• Journal of Labour Economics
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• v.24 no.1
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• pp.253-283
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• 2001

This paper attempts to account for the recent decline in the share of 'regular employees' among total employees. It finds, among other things, that the decline which began in 1993 is not associated with the changes in the composition of the worker groups that have differing tendency to work as regular employees. Overall, the decline in the share of regular employment is mainly due to the workers' increased transition probability out of 'regular employment', with the exception of the younger workers for whom the decrease in the rate of entry into 'regular employment' has also been an important reason of such a decline.

• Journal of Digital Convergence
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• v.15 no.11
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• pp.113-120
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• 2017

The purpose of this study is to analyze how the relative proportion of retention between real estate for business and investment real estate among the real estate held by corporations has been changed after and before the Financial Crisis as well as whether there has been any difference between KOSPI and KOSDAQ listed companies in terms of their share of the real estate. The increasing pattern of real estate owned by KOSDAQ were similar to the KOSPI companies except for investment properties during the Financial Crisis. The proportion of real estate owned by KOSPI had been lower than that of KOSDAQ companies in both investment and business real estate before the Financial Crisis. However, during the period of the Financial Crisis, the proportion of real estate for business held by KOSPI firms was higher than that of KOSDAQ firms. Furthermore, the portion of investment of real estate owned by KOSPI has remained higher than that of KOSDAQ after the Financial Crisis period and the recent period. Based on the results of this analysis, how the relevance of the change of portion between real estate for business and investment real estate affects management performance will be figured out in the future studies.

• Journal of Korea Port Economic Association
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• v.24 no.4
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• pp.349-361
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• 2008

There has been abundant empirical research undertaken on the technical efficiency of Korean ports. Most studies have focused on the use of parametric and non-parametric techniques to analyse overall technical efficiency. This paper utilizes data for the period 2000-07 to offer a heterogeneous perspective on the overall efficiency of Korean ports. The framework assumes that ports use one input to produce one output; the output and input include port export(import) and regional export(import). This paper also employs panel analysis and heteroscedastic Tobit model to show the effect of the explanatory variables on the port efficiencies. The panel analysis shows that the regional export/total export has negative effect on the export efficiency while the regional import/total import has not any relations with the import efficiency. The heteroskedastic Tobit model shows that both regional export ratio and regional import ratio have negative effects on the efficiency while the gross regional domestic product has not any significant relations with the import efficiency.

• KSBB Journal
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• v.22 no.5
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• pp.366-369
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• 2007

In this study, the feasibility of reusing the eluent was confirmed by monitoring its specific gravity during the chromatographic purification of paclitaxel from plant cell cultures. The specific gravity of the eluent (methanol/water = 70/30, v/v) was measured prior to its elution through the hydrophobic resin column. The measurement showed a specific gravity of 0.853. The discharged eluent from the column outlet was first evaporated under vacuum pressure. The evaporated eluent was collected and condensed into a liquid eluent again, followed by the HPLC analysis in order to check the presence of any trace of impurity. Even if the specific gravity of the liquid eluent is varied from 0.853 as a result of the evaporation and condensation, the eluent can still be reused after it specific gravity is adjusted by the addition of methanol or water. The reuse of the eluent resulted in the paclitaxel yield of 86% with a purity of 95% which were closely similar to those of before the eluent reuse. These results indicate that the strategy of reusing the eluent on the basis of the specific gravity analysis was successfully implemented in this study.

• Resources Recycling
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• v.23 no.5
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• pp.36-43
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• 2014

It comtained various kinds of heavy metal in beneficiatian tailing and in order to eliminate the heavy metals, various technologies have been researched, But there are a limits because many problems and restrictions are accompanied. Therefore, in this study, in order to solve this problem, It was performed gravity separation using melti-gravity seperator (MGS) to remove As contained in tailing, which can sort out even the fine particle. It was attempted a study to remove As, which is a kind of heavy metals, by MGS gravity separation and verified the impact by slope, wash water, pulp density, rotational speed and feed rate. In the results of performing gravity concentration under the condition with the MGS slope of $3^{\circ}$, wash water of 5 l/mm, pulp density of 30%, rotational speed of 208 rpm, and the feed rate of 265.24 g/mm, the As removal rate of 88.21% and yield of 92.25% were obtained.

• International Area Studies Review
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• v.14 no.3
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• pp.312-338
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• 2010

This paper investigates the value relevance of advertising activity over the period from 2001 to 2009 in the listed Korean stock markets(KOSPI and KOSDAQ). In addition, this paper divide all sample firm into several subsample, based on R&D intensity and export ratio in total sales. The empirical result of this paper shows following two evidence; First, advertising intensity, which proxies for advertising activity, is significantly related to firm value at the 1% level of significance. Second, advertising activity of high R&D intensity and high export ratio sample firms has more significant value relevance than for firms with low R&D intensity and low export ratio. The empirical results suggest that moderation effect of R&D intensity and export ratio are very important factor in determining the value relevance of advertising activity.