• International Journal of Reliability and Applications
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• v.17 no.1
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• pp.85-105
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• 2016

In this paper accelerated life testing is incorporated in quality control technique of acceptance sampling plan to induce early failures in high reliability products.Stress under accelerated condition can be applied in constant-stress, step-stress and progressive-stress or combination of such loadings. A ramp-stress results when stress is increased linearly (from zero) with time. In this paper optimum failure-censored ramp-stress accelerated life test sampling plan for log-logistic distribution has been formulated with cost considerations. The log-logistic distribution has been found appropriate for insulating materials. The optimal plans consist in finding optimum sample size, sample proportion allocated to each stress, and stress rate factor such that producer's and consumer's interests are safeguarded. Variance optimality criterion is used when expected cost per lot is not taken into consideration, and bilevel programming approach is used in cost optimization problems. The methods developed have been illustrated using some numerical examples, and sensitivity analyses carried out in the context of ramp-stress ALTSP based on variable SSP for proportion nonconforming.

• International Journal of Reliability and Applications
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• v.13 no.1
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• pp.19-35
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• 2012

This paper presents an optimum design of step-stress partially accelerated life test (PALT) plan which allows the test condition to be changed from use to accelerated condition on the occurrence of fixed number of failures. Various life distribution models such as exponential, Weibull, log-logistic, Burr type-Xii, etc have been used in the literature to analyze the PALT data. The need of different life distribution models is necessitated as in the presence of a limited source of data as typically occurs with modern devices having high reliability, the use of correct life distribution model helps in preventing the choice of unnecessary and expensive planned replacements. Truncated distributions arise when sample selection is not possible in some sub-region of sample space. In this paper it is assumed that the lifetimes of the items follow Truncated Logistic distribution truncated at point zero since time to failure of an item cannot be negative. Optimum step-stress PALT plan that finds the optimal proportion of units failed at normal use condition is determined by using the D-optimality criterion. The method developed has been explained using a numerical example. Sensitivity analysis and comparative study have also been carried out.

• Industrial Engineering and Management Systems
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• v.12 no.2
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• pp.74-84
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• 2013

Modern companies have been facing devastating impacts from unexpected events such as demand uncertainties, natural disasters, and terrorist attacks due to the increasing global supply chain complexity. This paper proposes a multi stage logistic network model under disruption risk. To formulate the problem practically, we consider the effect of continuity rate, which is defined as a percentage of ability of the facility to provide backup allocation to customers in the abnormal situation and affect the investments and operational costs. Then we vary the fixed charge for opening facilities and the operational cost according to the continuity rate. The operational level of the company decreases below the normal condition when disruption occurs. The backup source after the disrup-tion is recovered not only as soon as possible, but also as much as possible. This is a concept of the business continuity plan to reduce the recovery time objective such a continuity rate will affect the investments and op-erational costs. Through numerical experiments, we have shown the proposed idea is capable of designing a resilient logistic network available for business continuity management/plan.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.253-268
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• 2020

This study examined the effectiveness of policy measures in a growth management plan by analyzing empirically the influence of regulations and incentives in a non-urban growth management plan of Sejong City using the binomial logistic model. The parcel unit data related development location of Sejong City from 2012 to 2017 was used in the model. The analysis showed that time regulation in the growth management plan has a negative (-) impact on the spread of development, which means it is effective in slowing urban sprawl by lowering the profits of developers. The time regulation applied in Sejong City needs to be used actively in other cities in Korea to prevent urban sprawl. Nevertheless, floor ratio incentives had no influence in inducing development within the growth management area, which means a new incentive policy to meet the local characteristics is needed to strengthen the effectiveness of the growth management plan. This study is meaningful because it attempted an empirical analysis of the effects of the growth management plan at The National Territory Act, and this study could encourage further studies.

• The Korean Journal of Franchise Management
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• v.7 no.2
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• pp.27-35
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• 2016

Purpose - The primary objective of this study is to investigate the impact of employee characteristics on employees' preference towards corporate pension products. This study can provide a guidance for maximization of benefits for employees and their affiliated corporation. Employee characteristics include average length of labour, wage system of annual salary, age, types of interest rates and size of corporation. Existing research generally concentrate on vitalizations of corporate pension product raising an imperfection, improvements, tax benefit analysis and legal consideration. Thus, this study intensively analyses the effect of employee attributes on firms' decision for corporate pension products, such as DB(defined benefit) and DC(defined contribution) type. Research design, data, and methodology - The data were collected using self-administrated questionnaire survey on corporate pension products from CEOs or HR directors 250 foreign-invested companies', purchasing pension plans in practice with domestic financial trustees (insurance companies, banks and security companies). Hypotheses testing was conducted using Logistic Regression analysis with SPSS/PC+ 21.0. Results - The findings of the study are as follows. Employees with the long length of labour are more likely to have DB plan; more likely to prefer DC plan with the dividend distribution product regarding the types of interest rate. SMEs(less than 100 employees) are more likely to select DC plan whereas high fluctuation in wage with annual salary has no impacts. In addition, the ages has no significant effect on the preference. Conclusions - This study has examined with the empirical testing that employees' variable attributes and qualities are one of the vital factors for corporation pension plan selection. Currently, majority employees are highly likely to join DB plan and Defined interest types. Corporation with less than 10 employees prefer IRP scheme while most of corporation are intended to join DC plan. In a very near future, corporation more than 300 employees will be required to purchase mandatory plan under national regulation. For maximization of employees' contentment to corporation pension insurance and for complementing the flaws of existing plans, the future studies shall also research in a perspective of employee benefit.

• Communications for Statistical Applications and Methods
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• v.28 no.4
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• pp.339-350
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• 2021

In medical research, the risk factors associated with human diseases need to be identified to predict the incidence rate and determine the treatment plan. Logistic regression analysis is primarily used in order to select risk factors. However, individuals who are unfamiliar with statistics outcomes have trouble using these methods. In this study, we develop a nomogram that graphically represents the numerical association between the disease and risk factors in order to identify the risk factors for delirium and to interpret and use the results more effectively. By using the logistic regression model, we identify risk factors related to delirium, construct a nomogram and predict incidence rates. Additionally, we verify the developed nomogram using a receiver operation characteristics (ROC) curve and calibration plot. Nursing home, stroke/epilepsy, metabolic abnormality, hemodynamic instability, and analgesics were selected as risk factors. The validation results of the nomogram, built with the factors of training set and the test set of the AUC showed a statistically significant determination of 0.893 and 0.717, respectively. As a result of drawing the calibration plot, the coefficient of determination was 0.820. By using the nomogram developed in this paper, health professionals can easily predict the incidence rate of delirium for individual patients. Based on this information, the nomogram could be used as a useful tool to establish an individual's treatment plan.

• Journal of Information Technology Applications and Management
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• v.14 no.4
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• pp.221-233
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• 2007

Which factors should influence consumer consideration to subscribe to Voice over Internet Protocol (VoIP)? Policy issues, managerial concerns, and demographic variables are possible factors. This paper discusses policy and managerial issues regarding VoIP adoption. A model that explains VoIP adoption is proposed and tested. This study analyzes a survey of 750 prospective VoIP users in Korea. The testing is accompanied by logistic regression and discriminant analysis. The results show that trust in VoIP, relative comparison of Quality to fixed service, numbering plan, satisfactions of call Quality and customer services on both fixed and mobile services have impacts on the adoption of VoIP. Implications for VoIP providers and policy makers are presented.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.77-78
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• 2023

As large logistics buildings have high floor heights and long spans, these buildings are designed as PC structures, and large cranes are used to lift PC members. PC erection planning can generally cause errors depending on the field engineer's experience. To solve this problem, a basic analysis method is needed to establish a systematic PC member erection plan. Crane work can be minimized if the trajectory is easily and quickly calculated according to the location of the crane and applied to the site. Therefore, the objective of this study is a basic study of crane trajectory distance calculation for sustainable PC members erection of large logistic building. In this study, a crawler crane commonly used for lifting PC members is limited. The trajectory distance for the PC erection plan was automatically calculated using the algorithm.

• Journal of Korean Public Health Nursing
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• v.35 no.1
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• pp.60-71
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• 2021

Purpose: This study examined the socio-demographic and health factors affecting the quit-smoking plan in smoking seniors. Methods: Data were obtained from the Seventh Korean National Health and Nutrition Examination Survey (VII-1, VII-2, VII-3). The sample consisted of 369 smoking seniors. The complex sample was analyzed thought an independent t-test, Chi-square test, and multiple logistic regression. Results: The influential factors on the quit-smoking plan were daily smoking (OR=0.30, CI=0.11-0.78), age of start smoking (OR=1.06, CI=1.01-1.11), daily smoking amount (OR=0.95, CI=0.90-1.00), quit-smoking trial (OR=2.63, CI=1.32-5.23), and cognitive stress (OR=2.13, CI=1.01-4.54). Conclusion: This study revealed the variables that should be considered when setting up a smoking cessation plan for smoking seniors. Based on this, an elderly cessation intervention program can be developed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.78-84
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• 2021

In addition to physical risks such as electrical, chemical, and mechanic ones in the workplace, psychosocial risks are also raising as an important issue in recent years in connection with human rights and work-life balance policies. The purpose of this study is to confirm the degree of effect of the psychosocial risk management plan at the workplace on workers through logistic regression analysis. Input data for logistic regression analysis is the results of a survey of 4,558 people conducted by the Institute for Occupational Safety and Health were used. There are 9 independent variables, including the change a workplace and confidential counseling, and the dependent variable is whether the worker feels the effect on the psychosocial risk management plan. As a result of this study, changes in work organization, dispute resolution procedures, provision of education program, notification of the impact of psychosocial risks on safety and health, and the persons in charge of solving psychosocial problems are shown effective in reducing worker's psychosocial risks. This study drives which of the management plans implemented to reduce the psychosocial risk of workers in the workplace are effective, so it can contribute to the development of psychosocial risk management plans in the future.