• Proceedings of the Korea Information Processing Society Conference
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• 2018.05a
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• pp.474-475
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• 2018

전 세계적으로 9.11로 대표되는 자살테러, 비행기테러, 화학가스 테러 등에 의한 인명피해가 늘고 있다. 1986년 김포공항 폭발사고, 1995년 음진리교 지하철 사린가스 사건, 2001년 9.11 사건, 2003년 필리핀 공항 폭탄테러 사건 등의 큰 테러 외에도 작은 사건은 무수히 많다. 이러한 테러 사태를 미연에 방지하기 위한 지능형 영상 보안 감시 시스템이 사회적으로 연구되어왔고 도입되어 왔다. 기존의 지능형 영상 보안 시스템은 모션 디렉션 기반으로 금지구역의 침입자로 판단되는 사람을 찾는 기능 중심으로 발전해왔다. 또한 보안요원의 관찰 모니터를 통해 화면을 계속 주시하는 한계 시간의 존재와 모니터 증가에 따른 한계 시간은 더 급감하게 되는 것으로 판단되었다. 이에 본 연구를 통해 유기물 탐지의 자동화를 추구하고, 보안 요원의 감시 업무를 도와 국가 주요 시설물의 유기물 자동 탐지를 통해 테러로부터 안전하게 보호하고자 한다.

• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1311-1327
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• 2016

We propose a multi-state model for analyzing semi-competing risks data with interval-censored or missing intermediate events. This model is an extension of the 'illness-death model', which composes three states, such as 'healthy', 'diseased', and 'dead'. The state of 'diseased' can be considered as an intermediate event. Two more states are added into the illness-death model to describe missing events caused by a loss of follow-up before the end of the study. One of them is a state of 'LTF', representing a lost-to-follow-up, and the other is an unobservable state that represents the intermediate event experienced after LTF occurred. Given covariates, we employ the Cox proportional hazards model with a normal frailty and construct a full likelihood to estimate transition intensities between states in the multi-state model. Marginalization of the full likelihood is completed using the adaptive Gaussian quadrature, and the optimal solution of the regression parameters is achieved through the iterative Newton-Raphson algorithm. Simulation studies are carried out to investigate the finite-sample performance of the proposed estimation procedure in terms of the empirical coverage probability of the true regression parameter. Our proposed method is also illustrated with the dataset adapted from Helmer et al. (2001).

• Journal of Science Education
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• v.35 no.2
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• pp.283-294
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• 2011

The purpose of this study were to develop a tutorial for secondary students to understand of basic concepts of special relativity, which is appropriate for the cognition level of secondary student. We developed the concept evaluation tool and the tutorial material. Result from pretest and post-test are presented to verify the effect of the tutorial for helping student understanding of the concept such as time, event, reference frame, relativity of simultaneity. Secondary student had intense cognitive conflict about the complex concepts such as simultaneity, length contraction and time expansion. This tutorial could be proposed methodology to overcome cognitive difficulty for understanding these concepts.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.337-348
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• 2020

The purpose of this study is to determine whether impact of event and health beliefs affect adherence to self-care guidelines in the general public. The participants were 331 adults living in the Daegu/Gyeongbuk region. Data were collected using an online survey. The collected data were analyzed using hierarchical regression analysis and Process Procedure (Model 4). The results reported impact of event had a significant direct effect on health beliefs, and health beliefs had a significant direct effect on adherence to self-care guidelines. Also, the mediating effect of health beliefs on the relationship between impact of event and adherence to self-care guidelines was significant. To facilitate health education among the general public, it is necessary to include educational content to establish health beliefs regarding novel diseases such as COVID-19.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.159-166
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• 2020

In this paper, we propose a heterogenous mission allocation technique for multi-UAV system based on discrete event modeling. We model a series of heterogenous mission creation, mission allocation, UAV departure, mission completion, and UAV maintenance and repair process as a mathematical discrete event model. Based on the proposed model, we then optimize the number of UAVs required to operate in a given scenario. To validate the optimized number of UAVs, the simulations are executed repeatedly, and their results are analyzed. The proposed mission allocation technique can be used to efficiently utilize limited UAV resources, and allow the human operator to establish an optimal mission plan.

• Journal of the Korea Society for Simulation
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• v.21 no.2
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• pp.19-30
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• 2012

In recent decades, it has been known that the Discrete Event System Specification, or DEVS, formalism provides sound semantics to design a modular and hierarchical model of a discrete event system. In spite of this benefit, practitioners have difficulties in applying the semantics to real-world systems modeling because DEVS needs to specify a large size of sets of events and/or states in an unstructured form. To resolve the difficulties, this paper proposes an extension of the DEVS formalism, called the Structured DEVS formalism, with an associated graphical representation, called the DEVS diagram, by means of structural representation of such sets based on closure property of set theory. The proposed formalism is proved to be equivalent to the original DEVS formalism in their model specification, yet the new formalism specifies sets in a structured form with a concept of phases, variables and ports. A simplified example of the structured DEVS with the DEVS diagram shows the effectiveness of the proposed formalism which can be easily implemented in an objected-oriented simulation environment.

• Nuclear Engineering and Technology
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• v.23 no.3
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• pp.285-298
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• 1991

An example application of the fuzzy set theory is first made to a simple portion of a given accident progression event tree with typical qualitative fuzzy input data, and thereby computational algorithms suitable for application of the fuzzy set theory to the accident progression event tree analysis are identified and illustrated with example applications. Then the procedure used in the simple example is extended to extremely complex accident progression event trees with a number of phenomenological uncertainty issues, i.e., a typical plant damage state‘SEC’of the Zion Nuclear Power Plant risk assessment. The results show that the fuzzy averages of the fuzzy outcomes are very close to the mean values obtained by current methods. The main purpose of this paper is to provide a formal procedure for application of the fuzzy set theory to accident progression event trees with imprecise and qualitative branch probabilities and/or with a number of phenomenological uncertainty issues.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.606-615
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• 2015

This study aims to provide suggestions for the development of educational contents on historical events that can solve the existing curriculum's problems, such as the disproportionate weight given to Western historical events. The study focuses on content ranging from the start of the Agricultural Revolution (7000 BC.) to the start of the Industrial Revolution (AD. 1760). The results are as follows. We used the Delphi technique for deriving global historical events. Among them, 56 historical events were selected as the data for Social Network Analysis (SNA). The results of SNA showed that topics related to Civilization has a high priority. In addition, the results of a coagulation analysis showed the events can be divided into seven groups. The classification criteria is different from the criteria used for the current period. We expect that the suggested framework developed for historical contents will constitute a new approach to historical interpretation through network visualization and linkage analysis.

• School Mathematics
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• v.11 no.3
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• pp.513-526
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• 2009

The purpose of this paper intuitively shows the exact and logical explanation of Independent Event and Dependent Event. In actual classrooms, teachers have difficulty in describing the connection between those events and real life. Some teachers have wrong perceptions on the definition of those events. For example, they may not realize exactly what P(B A)=P(B) means and may not explain intuitively the original meaning of why it is independent event. Also they believe that Independent Event and Dependent Event do not always match with real life. This paper, therefore, tries to prove intuitively the exact meanings of those events in the Verbal Form with some examples and it proves that those events exactly match with real life. It is expected that this paper will greatly contribute to the improvement of probability education.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.61-69
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• 2008

In order to evaluate the performance of priority queues for future event list in discrete-event simulations, models representing patterns of enqueue and dequeue processes are required. The time complexities of diverse priority queue implementations can be compared using the performance models. This study aims at developing such performance models especially under the environment that a developed simulation model is used repeatedly for a long period. The developed performance model is based on multi-stage Markov process models; probabilistic patterns of enqueue and dequeue are considered by incorporating non-homogeneous transition probability. All necessary parameters in this performance model would be estimated by analyzing a results obtained by executing the simulation model. A case study with a war game simulation model shows how the parameters defined in muti-stage Markov process models are estimated.