• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.113-119
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• 2009

In this study we analyzed and gauged the information security needs for the new IT service which will be proceeding. Then we designed Information Security Rank Authentication System to raise the level of information security. To achieve this study, we analyzed rank authentication system of the inside and outside of the country and developed the practical propulsive system and the evaluation model which reflects IT service's own feature differing from the general evaluation of IS information security. The result of this study can be utilized to assess the level of domestic IT service information security objectively, and it can be applied as the means of rational decisionmaking for establishing a policy to raise degree of information security of corporations providing IT service.

• ETRI Journal
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• v.38 no.4
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• pp.714-723
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• 2016

Considerable attention has been given to processing graph data in recent years. An efficient method for computing the node proximity is one of the most challenging problems for many applications such as recommendation systems and social networks. Regarding large-scale, mutable datasets and user queries, top-k query processing has gained significant interest. This paper presents a novel method to find top-k answers in a node proximity search based on the well-known measure, Personalized PageRank (PPR). First, we introduce a distribution state transition graph (DSTG) to depict iterative steps for solving the PPR equation. Second, we propose a weight distribution model of a DSTG to capture the states of intermediate PPR scores and their distribution. Using a DSTG, we can selectively follow and compare multiple random paths with different lengths to find the most promising nodes. Moreover, we prove that the results of our method are equivalent to the PPR results. Comparative performance studies using two real datasets clearly show that our method is practical and accurate.

• Communications for Statistical Applications and Methods
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• v.3 no.3
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• pp.113-123
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• 1996

Data-dependent (adaptive) choice of asymptotically efficient score functions for rank estimators and M-estimators of regression parameters in a linear regression model with left-truncated and right-censored data are developed herein. The locally adaptive smoothing techniques of Muller and Wang (1990) and Uzunogullari and Wang (1992) provide good estimates of the hazard function h and its derivative h' from left-truncated and right-censored data. However, since we need to estimate h'/h for the asymptotically optimal choice of score functions, the naive estimator, which is just a ratio of estimated h' and h, turns out to have a few drawbacks. An altermative method to overcome these shortcomings and also to speed up the algorithms is developed. In particular, we use a subroutine of the PPR (Projection Pursuit Regression) method coded by Friedman and Stuetzle (1981) to find the nonparametric derivative of log(h) for the problem of estimating h'/h.

• Journal of information and communication convergence engineering
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• v.6 no.4
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• pp.359-363
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• 2008

In this paper, the capacity of MIMO fading channel in the OFDM-based spatial multiplexing systems is analyzed when there is scattering at both transmitter and receiver. The employed MIMO channel model is spanning from the correlated low-rank case to uncorrelated high-rank case at both transmitter and receiver. The effects of spatial fading correlation on the capacity of MIMO channel is examined when the channel is known and unknown at the transmitter. We also evaluate the impacts of a channel estimation error at the transmitter on the MIMO channel capacity.

• The Korean Journal of Applied Statistics
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• v.7 no.1
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• pp.35-46
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• 1994

We propose the nonparametric rank-like test for the location parameter in the bivariate changepoint model. Empirical powers between the parametric test and nonparametric test are compared. These results show that rank-like test is better than parametric method except bivariate normal null distribution. The point estimators for the changepoint are also compared by the empirical mean squared errors.

• Journal of the Korea Safety Management & Science
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• v.6 no.4
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• pp.107-122
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• 2004

This study aims to examine the usefulness on the Evaluation Process for the Feasibility & Priority of A Certain Public Projects. and the Methodology used AHP(Analytic Hierarchy Process) which used pairwise comparisons of the alternatives and criteria for solving discrete alternative multicriteria decision problems. In this paper, we present a similar phenomenon, rank reversal problem, when we apply the AHP to group decision making process. The problem is identified by an example problem in that the previous rank order of Public Projects choices. we also present three different methods to prevent the undesirable characteristic of the original AHP in appling to Decision Making Process.

• Communications for Statistical Applications and Methods
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• v.24 no.2
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• pp.115-127
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• 2017

This paper proposes a Bayesian test for the equivalence of survival functions in multiple groups. Proposed Bayesian test use the model of Cox's regression with time-varying coefficients. B-spline expansions are used for the time-varying coefficients, and the proposed test use only the partial likelihood, which provides easier computations. Various simulations of the proposed test and typical tests such as log-rank and Fleming and Harrington tests were conducted. This result shows that the proposed test is consistent as data size increase. Specifically, the power of the proposed test is high despite the existence of crossing hazards. The proposed test is based on a Bayesian approach, which is more flexible when used in multiple tests. The proposed test can therefore perform various tests simultaneously. Real data analysis of Larynx Cancer Data was conducted to assess applicability.

• Journal of the Korean Data and Information Science Society
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• v.28 no.2
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• pp.435-442
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• 2017

Consider the problem of estimating a $p{\times}1$ mean vector ${\theta}$ (p ${\geq}$ 3) under the quadratic loss from multi-variate normal population. We find a James-Stein type estimator which shrinks towards the projection vectors when the underlying distribution is that of a variance mixture of normals. In this case, the norm ${\parallel}{\theta}-K{\theta}{\parallel}$ is known where K is a projection vector with rank(K) = q. The class of this type estimator is quite general to include the class of the estimators proposed by Merchand and Giri (1993). We can derive the class and obtain the optimal type estimator. Also, this research can be applied to the simple and multiple regression model in the case of rank(K) ${\geq}2$.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.916-918
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• 2004

90년대 이전에 정보 검색에 대한 연구는 문서의 내용을 기반으로 한 연구가 주류였으며, 90년대에는 링크를 이용한 연구가 활발하였다. 90년대 말에 Page Rank와 HITS가 링크를 이용한 연구의 대표적 사례이며, 최근에는 문서의 내용과 링크 정보를 같이 이용하는 연구가 많이 발표되고 있다. 본 논문도 문서의 정보와 링크 정보를 이용한 새로운 검색 모델을 제시하고자 한다. 본 논문에서 사용하는 링크 정보는 수집된 문서에서 추출한 Page Rank의 가중치와 한 페이지를 가리키는 링크들의 목록이며, 상용하고자 하는 문서의 정보는 본문 내용과 Anchor Text이다. 링크 정보와 문서 정보를 이용하여 Anchor 벡터와 문서 벡터를 만들고, 각각 질의어 벡터와 Cosine Measure를 하여 값을 구한 후, 더한 값을 해당 문서의 가중치로 하여 검색에 이용한다.

• ETRI Journal
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• v.43 no.4
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• pp.694-701
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• 2021

Catastrophic events cause casualties, damage property, and lead to huge social impacts. To build common standards and facilitate international communications regarding disasters, the relevant authorities in social management rank them in subjectively imposed terms such as direct economic losses and loss of life. Terrorist attacks involving uncertain human factors, which are roughly graded based on the rule of property damage, are even more difficult to interpret and assess. In this paper, we collected 114 183 open-source records of terrorist attacks and used a machine learning method to grade them synthetically in an automatic and objective way. No subjective claims or personal preferences were involved in the grading, and each derived common factor contains the comprehensive and rich information of many variables. Our work presents a new automatic ranking approach and is suitable for a broad range of gradation problems. Furthermore, we can use this model to grade all such attacks globally and visualize them to provide new insights.