• Communications for Statistical Applications and Methods
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• v.23 no.6
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• pp.555-562
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• 2016

Interval censored data often occur in an observational study where the subject is followed periodically. Instead of observing an exact failure time, two inspection times that include it are available. There are several methods to analyze interval censored failure time data (Sun, 2006). However, in the presence of competing risks, few methods have been suggested to estimate covariate effect on interval censored competing risk data. A sub-distribution hazard model is a commonly used regression model because it has one-to-one correspondence with a cumulative incidence function. Alternatively, Klein and Andersen (2005) proposed a pseudo-value approach that directly uses the cumulative incidence function. In this paper, we consider an extension of the pseudo-value approach into the interval censored data to estimate regression coefficients. The pseudo-values generated from the estimated cumulative incidence function then become response variables in a generalized estimating equation. Simulation studies show that the suggested method performs well in several situations and an HIV-AIDS cohort study is analyzed as a real data example.

• Korea Journal of Hospital Management
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• v.6 no.2
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• pp.86-114
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• 2001

As the environment related to hospital operation has changed very competitively in recent years, a need to reform the hospital management is ever growing. For that reason, it has become more urgent and strategically important for us to diagnose the organizational culture of the hospitals and to make efforts to change them towards more performance- and customers-oriented one. So far, there have been many studies done on the hospital organizations. However, this research distinctively attempts to base itself on the competing values approach in studying the organizational culture and empirically examine how different profiles of the organizational culture may have an impact on the organizational performances in hospital organizations. The results of this study has showed several interesting findings and posed the discussions to be dealt with. First, most hospitals selected for this research are characterized by the inner-oriented culture with more focused on 'hierarchy' and 'relationship-oriented' culture rather than on 'reform' and 'work-oriented' one. And the strong 'hierarchy-oriented' culture is a very general phenomenon in the sample hospitals. From these findings, we can inference that despite the recent efforts of most Korean hospitals for organizational change and innovation they still have long distance way to go. In addition, another important implications of this research has come from the analysis of the relationships between the cultural profiles and organizational performances. For this purpose, this research has conducted a series of cluster analysis and identified four distinct cultural profiles from the sample organizations. Several major findings are as follows. First, with respect to the dependent variable of 'job satisfaction' perceived by the nurses working in the sample hospitals, we found that the balance of competing organizational values had more positive impact on the job satisfaction. This result confirms the hypothesis of competing values model on the organizational performances. However, such result was not replicated on the other dependent variable, 'patients' satisfaction'. The reasons for these results and other discussions including the limitations of this study are suggested.

• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.949-953
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• 1994

In oxides characterized by the $K_2NiF_4-type$ structure, the low-spin${\to}$high-spin transition of trivalent cobalt ion was studied in function of the nature of competing bonds in the perovskite-plane and along the c-axis. Using Slichter and Drickamer's model the calculated values of parameters characterizing such a transition are correlated with the covalency of competing bonds along the c-axis of the $K_2NiF_4$-structure and the local structural distortion of the $(CoO_6)$ octahedron.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.249-254
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• 2006

As the concept of Ubiquitous City has become an important issue, we need to have a voice in the field of privacy. The Ubiquitous Computing revolution, it is achieved a physical space and an intelligent union of cyber space in the space where an off-line space was integrated with on-line. It is combined with a life space naturally, and Ubiquitous creates a new integrated space. The space is the opportunity space that is limitless as soon as it is the unknown world that mankind was not able to experience yet. According to the recent papers and studies, Privacy or Personal Information sector is mentioned as a major problem for Ubiquitous Computing Society. Therefore, this paper checks Ubiquitous City, the present privacy concept and situation of currently proceeding Ubiquitous computing environment. Also, The main purpose of this paper is to analyze the concepts privacy, personal information. Thus this paper treated the analysis of case, technological or social issue, problem and solution, competing values of privacy and so on.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.6
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• pp.133-149
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• 2017

As cities face increasing problems such as aging, environmental pollution and growth limits, we have been trying to incorporate sustainability into urban planning and related policies. However, it is very difficult to generate a 'sustainable spatial plans' because there are trade-offs among environmental, society, and economic values. This is a kind of non-linear problem, and has limitations to be solved by existing qualitative expert knowledge. Many researches from abroad have used the meta heuristic optimization algorithms such as Genetic Algorithms(GAs), Simulated Annealing(SA), Ant Colony Optimization(ACO) and so on to synthesize competing values in spaces. GAs is the most frequently applied theory and have been known to produce 'good-enough plans' in a reasonable time. Therefore we collected the research on 'spatial optimization model based GAs' and analyzed in terms of 'study area', 'optimization objective', 'fitness function', and 'effectiveness/efficiency'. We expect the results of this study can suggest that 'what problems the spatial optimization model can be applied to' and 'linkage possibility with existing planning methodology'.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.585-593
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• 2021

The service industry has become the driving force of economic development in recent years. With the current fierce competitive situation, competing businesses have continually provided a superior quality of service, and an excellent perceived brand image to gain customer satisfaction and customer loyalty. This study's current purpose is to empirical research the linking between service quality, brand image, customer satisfaction, and customer loyalty. We collect research data from 299 consumers who bought goods at supermarkets in Ho Chi Minh City, Vietnam, using a convenient sampling technique. We proposed the conceptual model from prior studies and considered it in Vietnam's context. PLS-SEM was conducted to test the relationships in the conceptual model. We have estimated the scale's reliability by Cronbach's alpha values and composite reliability values. Moreover, we have evaluated discriminant validity by the Fornell-Larcker standard. The findings showed that service quality positively affects the brand image, customer satisfaction, and customer loyalty. Likewise, the results also confirmed brand image had a positive impact on customer satisfaction and customer loyalty. Moreover, the outcomes also disclosed that customer satisfaction had a positive relationship with customer loyalty. The research suggested implications for managers, limitations, and directions for future research from the above findings.

• The Korean Journal of Applied Statistics
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• v.37 no.2
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• pp.225-237
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• 2024

In the analysis of competing risks data, some of covariates may not be fully observed for some subjects. In such cases, excluding subjects with missing covariate values from the analysis may result in biased estimates and loss of efficiency. In this paper, we studied multiple imputation and the augmented inverse probability weighting method for regression parameter estimation in the cause-specific proportional hazards model with missing covariates. The performance of estimators obtained from multiple imputation and the augmented inverse probability weighting method is evaluated by simulation studies, which show that those methods perform well. Multiple imputation and the augmented inverse probability weighting method were applied to investigate significant risk factors for the risk of death from breast cancer and from other causes for breast cancer data with missing values for tumor size obtained from the Prostate, Lung, Colorectal, and Ovarian Cancer Screen Trial Study. Under the cause-specific proportional hazards model, the methods show that race, marital status, stage, grade, and tumor size are significant risk factors for breast cancer mortality, and stage has the greatest effect on increasing the risk of breast cancer death. Age at diagnosis and tumor size have significant effects on increasing the risk of other-cause death.

• The Korean Journal of Air & Space Law and Policy
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• v.27 no.2
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• pp.167-192
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• 2012

Aviation industry is known as the knowledge-based one and as an advanced nations' exclusive property having a large capacity for creating job and added value. Considering the current status of the aviation industry as aforesaid, it is natural for all countries to turn their attention to such promising aviation industry. At the time of rapid growth in aviation market, the importance of securing managerial experts and technicians is being under the spotlight as the aviation profession is increasingly in demand. To meet such dire needs that have already become an ever-greater part of the industry, collaboration among governmental, educational and industrial parties has formed in preparation for putting us into so-called an era of globalization. Having recognized the significance of the program, carried forward by The Ministry of Land, Transport and Maritime Affairs, fostering human resources in civil aviation, the objective of this study lies on deloping indicators for the programofficially designed to produce men of expertise in international air transport, the market of which forms nowadays a large part of national economy, and the technology of which develops so quickly. In this paper, an effort is made to develop the appraisal indicators and to set up standards thereof in order for the program to be systematically and expertly assessed on the basis of Quinn and Rohrbaugh's the competing values model. Firstly, this paper designs appraisal indicators, taking into account the peculiarity and environment of air transport industry, for developing human resources in civil aviation by utilizing advanced research on educational assessment in general due to the absence of applicable preceding studies regarding the development of human resources in civil aviation. Secondly, investigations into the necessity and validity of the appraisal are committed by analyzing answers from 100 respondents to questionaires and oral surveys in order to verify appraisal indicators designed in accordance with the competing values model. Lastly, the paper analyzes in a demographical way discrepancy in the recognitions among institutions for which the respondents work, on the basis of the outcome of the survey. As a result, the discrepancy is found not significant, which indicate that the aviation experts favour the indicators as appraisal standards. Prospective studies on the same issue may need an in-depth analysis, empowered by sufficient sampling in balance, of correlation between independent variables, then hopefully serve as a momentum for advancement of study in civil aviation.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1355-1364
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• 2019

A recently published nuclear forensics methodology for source discrimination of separated weapons-grade plutonium utilizes intra-element isotope ratios and a maximum likelihood formulation to identify the most likely source reactor-type, fuel burnup and time since irradiation of unknown material. Sensitivity studies performed here on the effects of random measurement error and the uncertainty in intra-element isotope ratio values show that different intra-element isotope ratios have disproportionate contributions to the determination of the reactor parameters. The methodology is robust to individual errors in measured intra-element isotope ratio values and even more so for uniform systematic errors due to competing effects on the predictions from the selected intra-element isotope ratios suite. For a unique sample-model pair, simulation uncertainties of up to 28% are acceptable without impeding successful source-reactor discrimination. However, for a generic sample with multiple plausible sources within the reactor library, uncertainties of 7% or less may be required. The results confirm the critical role of accurate reactor core physics, fuel burnup simulations and experimental measurements in the proposed methodology where increased simulation uncertainty is found to significantly affect the capability to discriminate between the reactors in the library.

• Membrane Journal
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• v.13 no.4
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• pp.257-267
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• 2003

For the treatment of reactive phenolic resin waste, a simulation model of pervaporative dehydration process has been developed through hollow fiber membrane module. Some of basic parameters were determined directly from dehydration of the waste liquid through a flat sheet membrane to get realistic values. The simulation model was verified by comparing the simulated values with experimental data obtained from hollow fiber membrane module. Hollow fiber membranes with active layer coated on inside fiber were used, and feed flew through inside hollow fiber. Feed flow rate affected membrane performances and reaction by providing a corresponding temperature distribution of feed along with fiber length. Feed temperature is also a crucial factor to determine dehydration and reaction behavior by two competing ways; increasing temperature increases permeation rate as well as water formation rate. Once the permeate pressure is well below the saturated vapor pressure of feed, permeate pressure had a slightly negative effect on permeation performance by slightly reducing driving force. As the pressure approached the vapor pressure of feed, dehydration performances declined considerably due to the activity ratio of feed and permeate.