• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.451-462
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• 2009

Recently, there are many active studies to enhance low I/O performance of hard disk device. The studies on the hardware make good progress whereas those of the system software to enhance I/O performance may not support the hardware performance due to its poor progress. In this paper, we propose a new method of prefetching n-blocks into the flash memory. The proposed method consists of three steps: (1)analyzing the pattern of read requests in block units; (2)determining the number of blocks prefetched to flash memory; (3)replacing blocks according to block replacement policy. The proposed method can reduce the latency time of hard disk and optimize the power consumption of the computer system. Experimental results show that the proposed dynamic n-block method provides better average response time than that of the existing AMP(Adaptive multi stream prefetching) method by 9.05% and reduces the average power consumption than that of the existing AMP method by 11.11%.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.299-307
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• 2014

N-Data Center which provide of cloud computing service for the Government departments, will be prepared transforming to cloud data center and transformed into an 'IT service' provided as a service to the information resources required by each department. N-Data center already provide a cloud service to the departments as maintains a high level of security, and plan to connecting with the private sector as a precondition of security. Therefore, in order to promote them effectively, it is necessary to determine the level of security in the cloud data center, and we have proposed appropriate measures. In this paper, we analyze security requirements of cloud data centers in developed countries and identify the leading private cloud data center security. In addition, we identify the N-data center security level, and analyzes the data center and private cloud gap and provide a transition strategy in terms of security finally.

• Smart Media Journal
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• v.9 no.4
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• pp.126-133
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• 2020

The treatment policy and prognosis are determined based on the final stage of lung cancer patients. The final stage of lung cancer patients is determined based on the T, N, and M stage classification table provided by the American Cancer Society (AJCC). However, the final stage of AJCC has limitations in its use for various fields such as patient treatment, prognosis and survival days prediction. In this paper, clustering algorithm which is one of non-supervised learning algorithms was assessed in order to check whether using only T, N, M stages with a data science method is effective for classifying the group of patients in the aspect of survival days. The final stage groups and T, N, M stage clustering groups of lung cancer patients were compared by using the cox proportional hazard model. It is confirmed that the accuracy of prediction of survival days with only T, N, M stages becomes higher than the accuracy with the final stages of patients. Especially, the accuracy of prediction of survival days with clustering of T, N, M stages improves when more or less clusters are analyzed than the seven clusters which is same to the number of final stage of AJCC.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.1-10
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• 2004

Quite many papers about moving objects database (MOD) have been Published. Most of them are concerning of improving efficiency of updating policy, but none of them talks about verification of system's requirements. No matter how efficient updating policy is employed, a system designer still has to verify if the MOD satisfies user's requirement at the beginning of system lifestyle. For example, if a MOD serves n moving objects, then the designer must verity if it can update information for n moving objects and provide new information to moving objects within specified time limit. For the purpose of requirement analysis of MODs, we build a Petri net model for MOD using Design/CPN, and then we show how to verify whether the MOD satisfies user's requirements by simulation. The contribution of this paper is providing a simulation model for requirement analysis of MOD for the first time. The model is expansion of our previous fuzzy-timing Petri net model. The distance-based updating policy, and distributed database management system are reflected in this model and system analysis for moving objects is considered. It is built in Design/CPN so that the simulation can be automatically performed. The application of our model is not limited to requirement analysis, it is useful to study other MOD design issues, such as the trade-offs between update cost and information accuracy, and between the tim interval needed for updating database and MOD system resources, etc.

• Journal of Preventive Medicine and Public Health
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• v.34 no.3
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• pp.219-227
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• 2001

Objectives : To understand the current status of the opening, closing and relocation of primary medical institutes in Korea and identify the underlying decision factors. Methods : Sources of analyzed data included the medical institutional master file at the National Health Insurance Corporation(1998, 2000) and Regional Statistic Annual Bulletins. To investigate changes including the opening, closing and relocation, a total of primary medicalinstitutions(16,757 in 1998, 19,267 in 2000) were analysed. Results : Between 1998 and 2000, there was a 15.0%(2,510) increase in the number of primary medical institutions and the rate of increase in the rural area was higher than the urban area, and higher for specialty clinics than primary practice. However, these findings did not suggestany improvement in the maldistribution of primary medical institutions. During the time period studied, newly opened and closed primary medical institutions numbered 4,085 and 1,573, respectively. Additionally, institutions thatrelocated numbered 2,729, or 16.3% of all primary medical institutions in operation in 1998. These openings and closings were more frequent among young doctors. As a result of our analysis on the underlying regional factors forrelocation, the factors that were statistically significant were local per capita tax burden and the number of schools per ten thousand persons. !n, the case of institutional factors, movements were significantly associated with gender and the location of primary medical institutions. Conclusions : In order to establish effective long-term intervention for primary medical institutions, further study and monitoring of primary medical institutions and the identification of factors influencing opening location and relocation is necessary.

• Korea Journal of Hospital Management
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• v.19 no.4
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• pp.57-68
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• 2014

Since the introduction of National Health Insurance(NHI) in 1977, it has grown rapidly and contributed to extend patient's access to the health care services. However, limited coverage for health care services of NHI has been ongoing challenge and private health insurance(PHI) has been rising as an alternative source of enhancing coverage and saving out-of-pocket(OOP) expenditure for patients. In this study, after controlling for socio-demographic, economic, health related variables, we identified the patients' healthcare utilization and subsequent OOP expenditure depending on their PHI enrollment and their enrollment types(fixed benefit, indemnity, fixed benefit plus indemnity). Data were collected from the 2010 Korean Health Panel. The unit of analysis was a member of household(n=13,324). Of the 13,324 cases, 70.7% of patients held PHI, in detail, fixed benefit(47.0%), indemnity(3.6%), fixed benefit plus indemnity(20.1%). Major findings showd that patients who enrolled in PHI used more outpatient services(outpatient visit, number of physician visit, number of examination) and spent more OOP expenditure than non-PHI patients. There were also differences of healthcare utilization and OOP expenditure among the types of PHI. In addition, PHI patients used more inpatient services(inpatient use, number of hospitalization, LOS), but there was no significant difference between PHI and non-PHI patients with regard to the OOP expenditure. Thus, we could not find any distinct relationship between the types of PHI and patients' tertiary hospital use. Policy-makers should need careful political deliberation for monitoring the effect of PHI on health care utilization and subsequent expenditure not only to improve patients' coverage but also to save their OOP expenditures.

• Health Policy and Management
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• v.27 no.4
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• pp.324-335
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• 2017

Background: The aim of this study is to analyze determinants of welfare attitudes toward healthcare services in South Korea, using three main theories: self-interest (positive welfare attitudes if the policy fulfills people's personal interests), symbolic attitudes (positive welfare attitudes if the person is politically progressive or egalitarian), and sociotropic perception (positive welfare attitudes if the person experienced positive aggregated collective experiences of societal events and trends regarding the policy). Although the definition of the welfare attitude is rather ambiguous in literatures, in this investigation, we operationalize the concept as the 'willingness to pay higher taxes to improve the level of health care services for all people in Korea' which shows individuals' actional propensity. Methods: We used the health module from the International Social Survey Program 2011 for the analysis (N= 1,391). Five logistic regression models were built successively using two variables for each theory to measure key concepts of self-interest, symbolic attitudes, and sociotropic perceptions as independent variables. Results: The result showed self-interest and symbolic attitudes factors to be strong determinants of welfare attitudes towards healthcare services in South Korea, whereas sociotropic perception factors have inconsistent effects. Conclusion: For a more politically elaborated healthcare reform in South Korea and elsewhere, there needs to be further research on various dimensions and determinants of welfare attitudes to understand popular basis of welfare expansion, especially in the era of inequality.

• Journal of KIISE:Software and Applications
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• v.26 no.12
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• pp.1404-1417
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• 1999

웹과 같은 분산 환경에서는, 웹 브라우저 상에서 SQL 형식의 공간 질의를 수행시키는 것과 또한 서버로부터 그 질의 결과를 보는 것이 가능하다. 그러나, 격자 이미지(raster image)와 같은 대용량 공간 데이타를 포함하는 질의 결과를 웹 브라우징할 때 발생하는 많은 문제점들 중에서, 사용자 응답 시간의 지연은 매우 중요한 문제이다. 본 논문에서는 사용자의 재요청(callback) 접근 패턴이 공간적 근접성(spatial locality)을 따른다는 가정하에서의, 사용자 응답 시간을 최소화하기 위한 새로운 프리페치(prefetch) 전략에 대해서 서술한다. 본 논문의 프리페치 전략은 다음과 같이 요약될 수 있다. 첫째, 프리페치 알고리즘은 사용자의 접근 패턴을 잘 반영하는 힐버트 곡선(Hilbert-curve) 모델을 바탕으로 한다. 둘째, 프리페치 전송 비용을 줄이기 위해서 사용자의 재요청 시간 간격(think time)을 이용한다. 본 논문에서는, 힐버트 곡선을 이용한 프리페치 전략의 성능 평가를 위해서 다양한 실험을 하였으며, 그 결과로 프리페치를 하지 않는 방식보다 높은 성능 향상이 있음을 보인다.Abstract In distributed environment(e.g., WWW), it would be possible for the users to submit SQL-like spatial queries and to see their query results from the server on the Web browser. However, of many obstacles which result from browsing query results including large spatial data such as raster image, the delay of user response time is very critical. In this paper we present a new prefetch policy which can alleviate user response time on the assumption that user's callback access pattern has spatial locality. Our prefetch policy can be summerized as follows: 1) our prefetch algorithm is based on the Hibert-curve model which well replects user's access pattern, and 2) it utilizes user's callback interval to reduce prefetch network transmission cost. In this paper we conducted diverse experiments to show that our prefetch policy achieves higher performance improvement compared to other non-prefetch methods.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.9
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• pp.1073-1082
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• 1999

본 논문에서는 시스템 내의 프로세서들을 효과적으로 사용하기 위한 적응적 프로세서 할당 정책을 제안한다. 프로그램의 병렬성을 향상시키기 위하여 일반적으로 병렬 처리에 사용될 프로세서 개수를 증가시킨다. 그러나 증가된 프로세서들은 그레인 크기에 변화를 일으키며 이는 캐쉬 성능에 영향을 미친다. 특히 대역이 제한된 공유 버스를 사용하는 시스템에서는 프로세서 개수의 증가는 공유 버스에 대한 접근 경쟁을 크게 증가하므로 버스에서 대기하는 시간이 프로세서 증가에 의한 계산 능력 이득을 상쇄시키는 주요한 원인이 되고 있다. 본 논문에서 제안한 적응적 프로세서 할당 정책은 프로그램이 수행되는 도중에 임의의 기간동안 공유버스에 대기중인 프로세서 분포에 관한 정보를 얻는다. 그리고 이 정보를 바탕으로 프로세서 개수를 변경하는 방법이다. 모의 시험에서 적응적 프로세서 할당 정책은 프로그램들의 버스 트래픽 특성에 따른 최적의 적합한 프로세서 개수를 발견함을 보인다. 그리고 적응적 프로세서 할당 정책은 고정된 프로세서 개수를 사용한 가장 좋은 성능보다는 다소 떨어진 성능을 나타내었으나 시스템의 프로세서 활용성을 높여 효과적 시스템 사용에 기여함을 보인다. Abstract In this paper, the adaptive processor allocation policy is suggested to make effective use of processors in system. To enhance the parallelism, the number of processors used in the parallel computing may be increased. However, increasing the number of processors affects the grain size of the parallel program. Therefore, it affects the cache performance. In particular, when the shared bus is employed, since increasing the number of processors can result in a significant amount of contention to achieve the shared-bus, the increased computing power is offset by the bus waiting time due to these contentions. The adaptive processor allocation policy acquires the information about the distribution of waiting processors on shared bus for any execution period of programs. And it changes the number of processors working in parallel processing during the program's run. Our simulation results show that the adaptive processor allocation policy finds the optimum feasible number of processors based on the bus traffic characteristic of programs. Thus, it contributes to effective system utilization, even though it performs slightly less efficiently than using a fixed number of processors with the best performance.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.53-63
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• 2016

This study aims to discuss what is needed for meaningful development of social service, focusing on Community Service Investment Project(CSIP). The contents of CSIP were analyzed on applying the Analytic Framework by N. Gilbert and H. Specht and the values that were the basis of social choice. Based on the analysis of output and policy value of this Project, this study draws three social service policy issues. First, 'localization' is needed to be emphasized more in CSIP because there are few programs that take into account the regional peculiarities. Second, as the social services focused on the individuality of the citizen is more important, it is necessary to examine 'sustainability' of CSIP. Third, in relation to the community building, it is necessary to discuss the modification of the CSIP's goals. As process for improving community, it is needed to review for local residents not participating in decision-making process, income-based user selection and appropriateness of the term 'investment' in the project name.