• The Korean Journal of Applied Statistics
• /
• v.17 no.2
• /
• pp.253-267
• /
• 2004

In some clinical trials, one may see that a significant fraction of patients are cured and their original disease does not recur even after termination of treatment and pro-longed follow-up. This situation occurs frequently in pediatric cancer trials where there are excellent therapeutic results. In such cases, interest concentrated on the difference of cure rates rather than other types of differences in failure distributions. Various authors have investigated the parametric and nonparametric methods for testing the difference of cure rates. In this study, we compare by simulation the power and size of a parametric test and five nonparametric tests in a various range of the alternatives, censoring rates and cure rates. Our objectives are to determine if any test was preferable on the basis of size and power in various situation, and to investigate the effect of the model misspecification.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.6 s.44
• /
• pp.107-111
• /
• 2006

According to IT(information technology) industry progress. our life is gradually convenient. The proliferation of environmental pollution and the threat of diseases proportional to the progress comes to be high gradually. We must prevent dangerous diseases which threatens the life of the human. Or we are bumped against irrevocable serious situation. In spite of the situation. managing one's own health against modern busy lifestyle is very difficult. Therefore, we need to manage our health situation by using sensors based on ubiquitous IT environment. In this paper. we propose a diagnostic model which is able to diagnose and prevent a cerebrovascular disease based on ubiquitous technology. Also. as a step of implementing the u-health care diagnosis system, the diagnosis model of cerebrovascular disease plays an important role to decide a clinic result. In the future, by using this model. we may improve our welfare and health.

• Journal of the Korea Society for Simulation
• /
• v.27 no.1
• /
• pp.33-38
• /
• 2018

This paper introduces the simulation concepts and technical approach of wire-guided torpedo performance analysis simulator, as a consequence, provide a framework for understanding overall attack procedures and effectiveness of tactics to torpedo operator. It described the mathematical models of simulation components and weapon engagement principle, especially it derived the closed-form solution of time consumption and leading angle problem of torpedo attack situation based on geographical assumption. In addition, it adopted the proportional navigation guidance at final stage of torpedo attack and also consider the tradeoff relation between target ship speed(propeller noise level) and detection probability, so that it improves the fidelity of physical realism. Simulator is developed with high degree of freedom in the perspective of tactical situation, and it helps user to understand the overall situation and tactical effectiveness.

• Korean small business review
• /
• v.41 no.3
• /
• pp.129-150
• /
• 2019

It is very meaningful to research on how people's perception on equality and psychology on class movement can have effect on the entrepreneurial intention at the present time when the Korean Government persuades people to create new businesses and the polarization between the rich and the poor gets severe. Accordingly, in this study, an empirical analysis was conducted to find out how the proportional equality acceptance level can affect the entrepreneurial intention via the upward mobility expectation by considering the proportionate equality acceptance level as independent variable, upward mobility expectation as a medium variable and the entrepreneurial intention as a dependent variable and then the hypothesis was tested through regression analysis. The results are as follows. First, it was found that the proportional equality acceptance level over the results makes a positive (+) effect on the entrepreneurial intention and the upward mobility expectation. On the other hand, it was found that proportional equality acceptance level over opportunity does not make any significant effect on each of entrepreneurial intention and upward mobility expectation. Second, it was found that the upward mobility expectation makes the positive (+) effect on the entrepreneurial intention. Third, it was found that the proportional equality acceptance level over opportunity and equality acceptance level over the results makes a positive (+) effect on the entrepreneurial intention through upward mobility expectation as a medium, thus showing the partial effect. This study has critical implications as it is an empirical analysis for finding out how the individual's level of perceiving equality makes an effect on entrepreneurial intention and testing the upward mobility expectation's mediating effect, thus reflecting the current society's situation.

• Journal of the Korean earth science society
• /
• v.22 no.5
• /
• pp.423-426
• /
• 2001

The accretion disk with viscosity including collisions is examined. The diffusion process are also considered for a given mass distribution in the disk. Under such a circumstance the diffusion coefficient is simply proportional to 1/${\sqrt{r}}$ The disk rapidly transfers the turbulent angular momentum and the wave front toward the outer cold regions. Then an instability situation occurs in the disk.

• Journal of Korean Institute of Industrial Engineers
• /
• v.24 no.1
• /
• pp.127-136
• /
• 1998

This paper presents a stochastic partial backorder inventory model for the situation in which demand follows normal distribution and back order ratio during that stockout period decreases exponentially according to the length of backorder period. In the paper, an objective function is formulated to minimize the average annual cost, which is the sum of the ordering, carrying, time-proportional backordering, and lost sales cost. And then sensitivity analysis for various exponential backorder ratios and standard deviations of leadtime demand are presented. The inventory model in the paper is reduced to a backorder model and lost sales model, when backorder ratio is 1 and 0, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.10
• /
• pp.996-1002
• /
• 2008

This paper presents the development of a real-time algorithm for collision detection, collision avoidance and guidance to way-point. Three-dimensional point-mass aircraft models are used. For collision detection, time of closest point of approach(CPA) and distance at CPA are compared to threshold values. For collision avoidance, optimal acceleration input which maximizes the terminal relative distance is calculated based on optimal control theory. For guidance to way-point, proportional navigation guidance, the well-known method, is used. Two scenarios of encounter situation are illustrated to validate performance of proposed algorithm.

• Korean Management Science Review
• /
• v.19 no.2
• /
• pp.169-178
• /
• 2002

The growth of Internet usage even accelerated by the spread of high-speed Internet access network such as ADSI is affecting our socioeconomic activities and culture in a great way. Korea is recently reported to be the number one high-speed Internet network subscription per 100 people in the world. In a way to reflect this situation, we collect a moderate size of sample proportional to the population of each region across country and investigate what factors might explain the level of user's dissatisfaction with respect to Internet service they have been receiving. The results indicate that the set of gender, age, Internet usage, service kinds, incoming e-mails, and e-shopping is significantly influencing user's dissatisfaction, in that dissatisfaction is measured in 11 perspectives. In particular, user's age, gender, and e-shopping experiences are considered to be mostly explainable.

• Communications for Statistical Applications and Methods
• /
• v.16 no.4
• /
• pp.697-705
• /
• 2009

The Pearson chi-squared statistic or the deviance statistic is widely used in assessing the goodness-of-fit of the generalized linear models. But these statistics are not proper in the situation of continuous explanatory variables which results in the sparseness of cell frequencies. We propose a goodness-of-fit test statistic for the cumulative logit models with ordinal responses. We consider the grouping of a dataset based on the ordinal scores obtained by fitting the assumed model. We propose the Pearson chi-squared type test statistic, which is obtained from the cross-classified table formed by the subgroups of ordinal scores and the response categories. Because the limiting distribution of the chi-squared type statistic is intractable we suggest the parametric bootstrap testing procedure to approximate the distribution of the proposed test statistic.

• International Journal of Aeronautical and Space Sciences
• /
• v.9 no.2
• /
• pp.1-8
• /
• 2008

This paper presents a real-time algorithm for collision detection, collision avoidance and guidance. Three-dimensional point-mass aircraft models are used. For collision detection, conflict probability is calculated by using the Monte-Carlo Simulation. Time at the closest point of approach(CPA) and distance at CPA are needed to determine the collision probability, being compared to certain threshold values. For collision avoidance, one of possible maneuver options is chosen to minimize the collision probability. For guidance to a designated way-point, proportional navigation guidance law is used. Two scenarios on encounter situation are studied to demonstrate the performance of proposed algorithm.