• Nuclear Engineering and Technology
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• 제46권6호
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• pp.753-772
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• 2014

The paper presents functional modelling and its application for diagnosis in nuclear power plants. Functional modelling is defined and its relevance for coping with the complexity of diagnosis in large scale systems like nuclear plants is explained. The diagnosis task is analyzed and it is demonstrated that the levels of abstraction in models for diagnosis must reflect plant knowledge about goals and functions which is represented in functional modelling. Multilevel flow modelling (MFM), which is a method for functional modelling, is introduced briefly and illustrated with a cooling system example. The use of MFM for reasoning about causes and consequences is explained in detail and demonstrated using the reasoning tool, the MFMSuite. MFM applications in nuclear power systems are described by two examples: a PWR; and an FBR reactor. The PWR example show how MFM can be used to model and reason about operating modes. The FBR example illustrates how the modelling development effort can be managed by proper strategies including decomposition and reuse.

• Communications for Statistical Applications and Methods
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• 제25권2호
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• pp.173-184
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• 2018

In medical or public health research, it is common to encounter clustered or longitudinal count data that exhibit excess zeros. For example, health care utilization data often have a multi-modal distribution with excess zeroes as well as a multilevel structure where patients are nested within physicians and hospitals. To analyze this type of data, zero-inflated count models with mixed effects have been developed where a count response variable is assumed to be distributed as a mixture of a Poisson or negative binomial and a distribution with a point mass of zeros that include random effects. However, no study has considered a situation where data are also censored due to the finite nature of the observation period or follow-up. In this paper, we present a weighted version of zero-inflated Poisson model with random effects accounting for variable individual follow-up times. We suggested two different types of weight function. The performance of the proposed model is evaluated and compared to a standard zero-inflated mixed model through simulation studies. This approach is then applied to Medicaid data analysis.

• 한국정보처리학회논문지
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• 제4권9호
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• pp.2354-2365
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• 1997

본 논문은 현대의 정보 통신 응용에서 접근제어 요구 사항의 복잡한 문제를 해결하기 위한 접근제어 매커니즘의 설계 방안을 제시한다. 본 논문에서는 자원의 기밀성, 무결성 및 가용성의 공통적 목적을 달성하기 위한 통합 정보 모델을 제안 하고, 신분-기반, 규칙-기반 및 직무-기반의 관점에서 각 관련된 정책과 규칙을 정의하였으며, 필요한 접근제어 오퍼레이션들을 구현하였다. 제안된 통합 정보 모델은 보안 레이블, 무결성 등급, 직무 및 소유권 등의 다단계 보안 정책을 기반으로 하여 자원에 대한 불법적인 접근을 방어할 수 있다.

• Journal of Power Electronics
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• 제14권6호
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• pp.1178-1188
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• 2014

This study proposes a finite-state model predictive controller to regulate the load current and balance the DC-link capacitor voltages of a four-leg neutral-point-clamped converter. The discrete-time model of the converter, DC-link, inductive filter, and load is used to predict the future behavior of the load currents and the DC-link capacitor voltages for all possible switching states. The switching state that minimizes the cost function is selected and directly applied to the converter. The cost function is defined to minimize the error between the predicted load currents and their references, as well as to balance the DC-link capacitor voltages. Moreover, the current regulation performance is improved by using a two-step prediction horizon. The feasibility of the proposed predictive control scheme for different references and loads is verified through real-time implementation on the basis of dSPACEDS1103.

• 한국인구학
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• 제11권1호
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• pp.97-116
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• 1988

This study examines the socioeconomic determinants of fertility behavior in Korea by developing a model which simultaneously takes into account both individual and community-level differences. It especially focuses on the micro-macro nexus of fertility behavior depending on social contexts. This study utilizes micro data obtained from the 1974 Korean National Fertility Survey(KNFS), and macro data obtained from Korean government statistics. The framework of the model is formalized as a set of structural equations modelling the fertility process. The model is formed on a cohort-specific processual basis and is restricted to five-year birth cohorts. Three cohorts of women are studied : those aged 30-34, 35-39, and 40-44. The model includes three fertility-process components : age at first birth, early fertility, and later fertility, which are defined by reference to the age of the mother. The results of this study indicate that socioeconomic development in Korea results in increased age at first birth and reduced numbers of children per couple. In addition to the developmental change, Korea's fertility decline is found to be facilitated by family planning programs. As expected, the effect of family planning on fertility is greater among better-educated women than among poorly educated women. The inconsistent but suggestive result, however, is that the effect of socioeconomic development on fertility is greater among less-privileged women than among more-previleged women.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.83-93
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• 2021

COVID-19 poses a major risk to global health, highlighting the importance of faster and proper diagnosis. To handle the rise in the number of patients and eliminate redundant tests, healthcare information exchange and medical data are transmitted between healthcare centres. Medical data sharing helps speed up patient treatment; consequently, exchanging healthcare data is the requirement of the present era. Since healthcare professionals share data through the internet, security remains a critical challenge, which needs to be addressed. During the COVID-19 pandemic, computed tomography (CT) and X-ray images play a vital part in the diagnosis process, constituting information that needs to be shared among hospitals. Encryption and image steganography techniques can be employed to achieve secure data transmission of COVID-19 images. This study presents a new encryption with the image steganography model for secure data transmission (EIS-SDT) for COVID-19 diagnosis. The EIS-SDT model uses a multilevel discrete wavelet transform for image decomposition and Manta Ray Foraging Optimization algorithm for optimal pixel selection. The EIS-SDT method uses a double logistic chaotic map (DLCM) is employed for secret image encryption. The application of the DLCM-based encryption procedure provides an additional level of security to the image steganography technique. An extensive simulation results analysis ensures the effective performance of the EIS-SDT model and the results are investigated under several evaluation parameters. The outcome indicates that the EIS-SDT model has outperformed the existing methods considerably.

• 한국노년학
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• 제37권1호
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• pp.173-200
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• 2017

본 연구의 목적은 노인자살예방을 위해 개발된 통합적 위기개입모델을 경기도를 중심으로 적용한 후 위기개입서비스의 실제 개입효과를 검증하는 것이다. 통합적 위기개입모델은 지역사회 통합시스템 접근과 스트레스 취약성 이론을 포함하는 위기개입 이론에 기초하여 개발되었다. 효과성 검증을 위해 노인우울(GDS-K) 및 자살생각(SSI)척도를 활용하였고, 1차 사전검사 258명, 통합적 위기개입 서비스 6개월 제공 후 2차 사후검사 184명, 2-3년 후 역추적을 통해 3차 추수검사 124명의 자료를 수집하여 분석하였다. 분석은 R Statistics computing을 이용하였고, 서로 다른 시점의 다른 검사를 비교하기 위해 검사 동등화 및 측정 시점 간 수직 척도화를 수행한 후 기술통계와 일변량 분산분석을 실시하였고, 마지막으로 베이지언 추정을 이용해 다층모형 분석을 실시하였다. 연구결과 노인자살예방을 위해 개발된 통합적 위기개입모델 적용 후 사전점수에 비해 사후측정에서 통계적으로 유의하게 노인우울과 자살생각을 감소시키는 것으로 나타났는데, 노인우울 감소에 .56의 효과크기를, 자살생각의 감소에 .39의 효과크기를 나타내 모델의 전체적인 효과성이 입증되었다. 그러나 위기개입 후 2-3년 후 추수검사에서 노인우울 및 자살생각이 다시 높아져 원래 상태를 회복하는 것으로 나타나 개입의 장기적인 유지효과는 확인되지 않았다. 노인우울 및 자살생각 변화량에 영향을 주는 요인을 찾기 위해 다층분석을 통해 위기개입 서비스의 각 유형(위기개입 전문상담, 약물치료, 동료상담)과 내담자특성(성별, 연령), 상담자 특성(전문가 연령, 경력, 전공)들 및 위기개입 서비스 유형(위기개입 전문상담)과 상담자 특성(전문가 연령, 경력, 전공)의 상호작용 효과를 살펴본 결과, 유일하게 약물치료가 단독으로 자살생각을 의미있게 낮추는 것으로 나타났으며, 전문가의 전공이 상담전공일 때 전문상담과 상호작용하여 자살생각을 의미있게 감소시키는 것으로 나타났다. 본 연구는 노인자살예방을 위해 개발된 통합적 위기개입모델의 전체효과와 각 개입서비스 유형의 효과를 검증하여 현장 적용의 근거를 확보했다는 데에 의의가 있다.

• 보건행정학회지
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• 제32권4호
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• pp.347-355
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• 2022

Background: Since November 2019, long-term care hospitals have been able to provide patients with discharging programs to support the elderly in the community. This study aimed to identify both patient- and hospital-level factors that affect successful community discharge from long-term care hospitals. Methods: A multilevel logistic regression model was performed using hospitals as a clustering unit. The dependent variable was whether a patient stayed in the community for at least 30 days after discharge from a long-term care hospital. As for the patient-level independent variables, an agreement between a patient and the family about discharge, length of hospital stay, patient category, and residence at discharge were included. The number of beds and the ratio of long-stay patients were selected for the hospital-level factors. The sample size was 1,428 patients enrolled in the discharging program from November 2019 to December 2020. Results: The number of patients who were discharged to the community and stayed at least for 30 days was 532 (37.3%). The intraclass correlation coefficient was 22.9%, indicating that hospital-level factors had a significant impact on successful community discharge. The odds ratio (OR) of successful community discharge increased by 1.842 times when the patients and their families agreed on discharge. The ORs also increased by 3.020 or 2.681 times, respectively when the patients planned to discharge to their own house or their child's house compared to those who didn't have a plan for residence at discharge. The ORs increased by 1.922 or 2.250 times when the hospitals were owned by corporate or private property compared to publicly owned hospitals. The ORs decreased by 0.602 or 0.520 times when the hospital was sized over 400 beds or located in small and medium-sized cities compared to less than 200 bedded hospitals or located in metropolitan cities. Conclusion: The results of the study showed that the patients' and their family's willingness for discharge had a great impact on successful community discharge and the hospital-level factors played a significant role in it. Therefore, it is important to acknowledge and support long-term care hospitals to involve active in the patient discharge planning process.

• 한국정보시스템학회지:정보시스템연구
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• 제26권4호
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• pp.379-400
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• 2017

Purpose The purpose of this study is to investigate the effects of ICT on multilevel marketing organizations (MLMs) whose members are both salespeople and consumers. This study explores the effects of the latest ICT convergence on the direct selling, which is the oldest sales method, and suggests the direction for the development of network marketing. Therefore, we will propose the changes in direct sales brought by ICT and predict the future direction of network marketing in preparation for the 4th Industrial Revolution era. Design/methodology/approach Exploratory case study was the methodology selected for this paper. The case study enables the use of multiple methods for data collection and analysis. This study applies qualitative case-study methodology on Amway Korea, which is the top seller of MLM organizations, to better understand the impact of ICT. This study conducted an in-depth interview with four different levels of MLM members (e.g. membership, ruby, emerald, diamond) which are based on the qualification system of MLM organizations and observed their behaviors. Findings This study revealed that the ICT impact on network marketing organizations(MLMs) could be summarized as follows : new membership growth, easier communication with customers, increase in work efficiency, increase in organizational trust, change in educational environment, and increase in the use of social media. Based on the interview, we propose the changes of network marketing organizations in the fourth industrial revolution era and the future strategy of Amway Korea as follows: (1) retention of royal ABOs, (2) harmony with SMEs, (3) utilization of Big Data, (4) creation of IoT business model, and (5) construction of successful O2O business platform.

• Journal of Preventive Medicine and Public Health
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• 제50권3호
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• pp.165-176
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• 2017

Objectives: This study aimed to estimate the risk of bleeding following minor oral surgical procedures and uninterrupted aspirin therapy in high-risk patients or patients with existing chronic diseases compared to patients who did not use aspirin during minor oral surgery at a public hospital. Methods: This retrospective cohort study analyzed the data of 2912 patients, aged 20 years or older, who underwent 5251 minor oral surgical procedures at a district hospital in Thailand. The aspirin group was comprised of patients continuing aspirin therapy during oral surgery. The non-aspirin group (reference) included all those who did not use aspirin during surgery. Immediate and late-onset bleeding was evaluated in each procedure. The risk ratio of bleeding was estimated using a multilevel Poisson regression. Results: The overall cumulative incidence of immediate bleeding was 1.3% of total procedures. No late-onset bleeding was found. A significantly greater incidence of bleeding was found in the aspirin group (5.8% of procedures, p<0.001). After adjusting for covariates, a multilevel Poisson regression model estimated that the bleeding risk in the aspirin group was 4.5 times higher than that of the non-aspirin group (95% confidence interval, 2.0 to 10.0; p<0.001). However, all bleeding events were controlled by simple hemostatic measures. Conclusions: High-risk patients or patients with existing chronic diseases who continued aspirin therapy following minor oral surgery were at a higher risk of hemorrhage than general patients who had not used aspirin. Nonetheless, bleeding complications were not life-threatening and could be promptly managed by simple hemostatic measures. The procedures could therefore be provided with an awareness of increased bleeding risk, prepared hemostatic measures, and postoperative monitoring, without the need for discontinuing aspirin, which could lead to more serious complications.