• Journal of the Korean Data and Information Science Society
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• 제28권1호
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• pp.153-161
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• 2017

전염병 확산에 대한 확률과정모형으로 활용되는 분기과정은 실제 데이터를 통해 모수를 추정할 수 있다는 장점이 있다. 음이항 분포를 분기과정의 생산 분포 모형으로 적용할 수 있는데 음이항 분포를 적용하기 위해서는 평균과 산포 모수를 추정하여야한다. 기존의 생물학 연구와 역학 연구 분야에서는 이를 최대우도법을 이용하여 추정하고 있다. 그러나 대부분의 역학 자료의 특성상 분기과정에서 이용되는 음이항 분포는 소표본이어서 최대우도 추정량의 정도를 충족시킬 수 없다. 본 논문에서는 소표본 자료에서 좋은 통계량의 성질을 만족한다고 알려져 있는 베이지안을 이용하여 모수를 추정하는 방법을 제안한다. 2015년 국내 메르스 사례에 베이지안 방법을 적용하여 모수를 추정하고 사후 분포를 적합하였다. 그 결과 어떠한 사전 분포를 가정하더라도 안정적으로 모수를 추정하는 것을 알 수 있었다. 추정된 산포 모수를 이용하여 분기과정에서의 전염병 소멸 확률을 유도하였다.

• 융합보안논문지
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• 제8권4호
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• pp.173-181
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• 2008

최근 웜에 의한 사이버 위협이 증가함에 따라 웜의 확산 특성을 분석하기 위한 전파 모델이 연구되고 있다. 대표적인 예로 수학적 모델링 기법인 Epidemic(SI), KM(Kermack-MeKendrick), Two-Factor, AAWP(Analytical Active Worm Propagation)등의 모델 기법들이 제시되었다. 하지만, 기존 모델 방법들은 대부분 코드레드와 같은 네트워크를 대상으로 하는 랜덤 스캐닝 기법에 대해서만 모델링이 가능하다. 또한 거시적인 분석만 가능하고 특정 위협에 대해 예측하는데 한계점을 가지고 있다. 따라서 본 논문에서는 과거의 위협 발생 데이터를 근거로 하여 Mass SQL Injection 같은 사이버위협에 적용 가능한 마코브 체인(markov chain) 기반 예측 방법을 제시한다. 이를 통하여 각 위협별 발생 확률 및 발생빈도를 예측할 수 있다.

• Journal of the Korean Data and Information Science Society
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• 제20권1호
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• pp.149-158
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• 2009

쯔쯔가무시증은 가을철 유행성 출혈열 중 80%이상을 차지하는 질병으로 1주에서 2주의 잠복기를 가지는 것으로 알려져 있다. 우리는 그 잠복기간의 확률분포가 감마분포라 가정하고 후향연산식을 이용하여, ${\hat{\mu}}=309.92$$, ${\hat{\sigma}}=14.154$인 정규분포를 따르는 감염자 분포를 추정하였다. 감염자는 10월에 집중적으로 분포하는 것으로 나타났다. 이러한 감염자 분포형태는 발병자 수가 11월동안 급격하게 증가하는 것에 기인한다. 본 연구에서 추정한 감염확률에 의해 미래의 유병자수를 계산한 결과 최대 1200명이었고 이는 매년 증가하는 발병자 수의 경향을 반영하지 못한 한계가 있다. 또한 우리는 전염병 모형으로 잘 알려져 있고 전염발전 단계간의 상호작용을 고려하는 SIRS 모형을 적용해 보았다. 모수는 초기값으로부터 잘 근사되어 수렴하는 값으로 추정하였다.

• 전기의세계
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• 제26권2호
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• pp.66-71
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• 1977

A mathematical model, which can be used for the study of an influenza epidemic, was derived. The model of influenza takes into full consideration the incubation period and inapparent infection. That was analysed by means of digital computer under the conditions of changing the infection rate, .betha., from 4 to 5, for three types of communities (First type: the initial distribution of population, x$_{1}$(0)=89% susceptibles, x$_{2}$(0)=3% incubatives, x$_{3}$(0)=0.5% carriers, x$_{4}$(0)=7.5% immunes; Second type: x$_{1}$(0)=79%, x$_{2}$(0)=3%, x$_{3}$(0)=0.5%, x$_{4}$(0)=17.5%; Third type: x$_{1}$(0)=69%, x$_{2}$(0)=3%, x$_{3}$(0)=0.5%, x$_{4}$(0)=27.5%, considering the rate of population increase, in Seoul. In conclusion, the outcomes of this study are summarized as follow. 1) The new model is quite reasonable in representing many phenomena connected with influenza spread. 2) The more influenza does prevail, the smaller the valve of attack rate becomes, while the contagious period becomes slightly longer. 3) The average infection rate, .betha., of influenza is approximately 5 per week time and X$_{4}$(0) is about 27.5 percent of the total population in Seoul spring 1961. 4) The number of carriers of influenza in Seoul spring 1961 becomes maximum within approximately 2.4 weeks after the attack of diseases. 5) About 68 percent of all cases in the contagious period is infected with influenza from 5 to 15 days after the attack of diseases. The auther believes that the method to study the influenza models in this paper will be helpful to study the characteristics of other epidemics. It will also contribute to public healthe management and the preventive policy decision against epidemics.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권12호
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• pp.597-603
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• 2001

In the mathematical model for the transmission dynamics of HIV infection described in previous papers, the population under consideration is assumed to be homogeneous community of homosexual males for which the parameter x represents the constant rate at which individual members of the population acquire new sexual partners. This is a gross oversimplification since it is well known that individuals vary widely in their levels of sexual activity and in this papers the heterogeneous model is modified to allow for this variation. The pattern on the epidemic character of HIV, the causative agent of AIDS, was analysed by heterogeneous-mixing model. The computer simulation was performed using real date.

• 한국멀티미디어학회논문지
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• 제22권5호
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• pp.588-600
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• 2019

Each year Malaria affects over 200 million people worldwide. Particularly, African continent is highly hit by this disease. According to many researches, this continent is ideal for Anopheles mosquitoes which transmit Malaria parasites to thrive. Rainfall volume is one of the major factor favoring the development of these Anopheles in the tropical Sub-Sahara Africa (SSA). However, the surveillance, monitoring and reporting of this epidemic is still poor and bureaucratic only. In our paper, we proposed a method to fast monitor and report Malaria instances by using Social Network Systems (SNS) and precipitation volume in Nigeria. We used Twitter search Application Programming Interface (API) to live-stream Twitter messages mentioning Malaria, preprocessed those Tweets and classified them into Malaria cases in Nigeria by using Support Vector Machine (SVM) classification algorithm and compared those Malaria cases with average precipitation volume. The comparison yielded a correlation of 0.75 between Malaria cases recorded by using Twitter and average precipitations in Nigeria. To ensure the certainty of our classification algorithm, we used an oversampling technique and eliminated the imbalance in our training Tweets.

• 유통과학연구
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• 제21권8호
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• pp.47-55
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• 2023

Purpose: Online meeting is chosen instead of face-to-face conferences as a solution that ensures both effectiveness and legality during times of strong epidemic outbreaks. In the current period, managers can have different types of meeting options for information distribution. This study has examined the effect of past behavior on the managers' intention of organizing online meetings. Research design, data and methodology: Data were collected from a survey with 475 managers and put into SmartPLS 4.0 for analysis. Partial least squares structural equation modeling (PLS-SEM) was employed to test relationships in the research model. Results: The findings indicated that past behavior plays the most critical role in explaining the organizing online meeting intention of managers, followed by attitude and subjective norms. Meanwhile, the perceived behavioral control factor has absolutely no effect on intention in the context of this study. Notably, attitude and subjective norms also remarkably mediated the impact of past behavior on managers' intention. Conclusions: This study has added to the understanding of the meeting organization behavior of managers. Even if the epidemic is under control, the administrators should still organize some meetings in the form of online because it will affect the social perceptions of future behavior and behavioral intention.

• ETRI Journal
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• 제30권1호
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• pp.81-88
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• 2008

The security threat posed by worms has steadily increased in recent years. This paper discusses the application of the optimal and sub-optimal Internet worm control via Pontryagin's maximum principle. To this end, a control variable representing the optimal treatment strategy for infectious hosts is introduced into the two-factor worm model. The numerical optimal control laws are implemented by the multiple shooting method and the sub-optimal solution is computed using genetic algorithms. Simulation results demonstrate the effectiveness of the proposed optimal and sub-optimal strategies. It also provides a theoretical interpretation of the practical experience that the maximum implementation of treatment in the early stage is critically important in controlling outbreaks of Internet worms. Furthermore, our results show that the proposed sub-optimal control can lead to performance close to the optimal control, but with much simpler strategies for long periods of time in practical use.

• 대한의용생체공학회:의공학회지
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• 제14권4호
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• pp.365-370
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• 1993

Of the assumptions commonly used in continuous infection model, the least likely to be even approximately true in large population, is that of homogeneous mixing. In this paper, We investigate a model for the spread of infection amongst a population which is divided into classes, such that the individuals of each class mix homogeneously amongst themselves, but mix to a lesser degree with individuals of other class. The stochastic model in this form is intractable and approximations are made, yielding results in reasonable agreement with simulation trials.

• ETRI Journal
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• 제28권5호
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• pp.692-695
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• 2006

Recently, there has been a constant barrage of worms over the Internet. Besides threatening network security, these worms create an enormous economic burden in terms of loss of productivity not only for the victim hosts, but also for other hosts, as these worms create unnecessary network traffic. Further, measures taken to filter these worms at the router level incur additional network delays because of the extra burden placed on the routers. To develop appropriate tools for thwarting the quick spread of worms, researchers are trying to understand the behavior of worm propagation with the aid of epidemiological models. In this study, we present an optimization model that takes into account infection and treatment costs. Using this model we can determine the level of treatment to be applied for a given rate of infection spread.