• Journal of Korean society of Dental Hygiene
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• v.21 no.3
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• pp.245-253
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• 2021

Objectives: The objective of this paper was to estimate a South Korean's lifetime dental expenditures for periodontitis. Methods: For our study, we collected data from the Korea Health Panel Survey (KHPS), from 2010 to 2016. The outpatient dental care data of 1,919,608 samples of periodontitis were extracted using R version 3.0 and estimations of lifetime dental expenditures for them were generated using Excel. Results: Over 50% of the lifetime dental expenditure of South Koreans was spent for periodontitis, and incurred after the age of 40. The results showed that an estimate of average per capita lifetime dental expenditure for men (approximately 13 million won) was greater than that for women (approximately 8.8 million won) for periodontitis. Conclusions: Efficient methods for the prevention and management of periodontitis are necessary, and a new paradigm of health care system is required to reduce dental expenditure through its prevention.

• Journal of The Korean Digital Architecture Interior Association
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• v.3 no.2
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• pp.30-38
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• 2003

The purpose of this study was to analyze the demand estimation erection of lifetime sports facilities for making an accurate estimate of its demand on the basis of the rate of the people participating in lifetime sports activities. Participation rate was determined on the basis of the fact-finding survey [by the Ministry of Culture and Tourism(2000)] as a basis research on facilities demand, and its demand was calculated by making an estimate of facilities demand. An estimate of facilities demand was made in the equation by participation population, facilities demand for each person, sports space area for each person, time of sports, cycle of sports, possible time to use of sports space. Facilities demand for each person by sports event is the following: $swimming;0.03m^2$, $basketball;0.045m^2$, martial arts(taekwondo, judo, korean fencing);0.003 $75m^2$, $aerobics;0.0289m^2,\;health;0.00326m^2,\;badminton;0.00323m^2,\;tennis;0.01429m^2,\;soccer;0.1112m^2,\;squash;0.01323m^2$.

• Journal of Korean Society for Quality Management
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• v.38 no.4
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• pp.504-511
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• 2010

A fuze detonator comprising star shells is an important device so that its failure usually leads to failure of the shells. In this paper, accelerated degradation tests of RD1333 (lead azide) using temperature stress were performed, and then degradation data of explosive power for the detonator were analyzed to predict the storage lifetime of detonator. Degradation data analysis to estimate the storage lifetime is based on a distribution-based degradation process. Statistical distribution parameters of explosive power degradation measures at each time were estimated for each temperature level, and then reliability of the detonator for each accelerated temperature level was estimated using both time-varying distribution parameters and critical level of explosive power. Arrhenius model was applied to estimate storage lifetime of the detonator under the field temperature condition. Accelerated distribution-based degradation analysis to estimate storage lifetime is explained in detail, and estimation results are compared to field data of storage lifetime in this paper.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.57-60
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• 2000

An aluminum electrolytic capacitor is used in DC Link of ac motor drive system. In this case it usually has the shortest lifetime in the system and then determines the system lifetime. Therefore life estimation of the electrolytic capacitor is needed for maintenance of th circuit. In this paper a method for life estimation is presented with a ESR(equivalent series resistance) model and a heat transfer model of capacitor that can be used to estimate operating temperature it is investigated through a simple example using ESR and heat transfer.

• Journal of Applied Reliability
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• v.1 no.2
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• pp.139-148
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• 2001

We are concerned in the estimation of lifetime distribution of a component having a few observed failure data and we demonstrate that we can use the maximum likelihood estimation utilizing the censored data when the number of components in use is quite large. Weibull distribution is assumed for the lifetime and a simple estimation procedure is introduced. We also propose the method of determining the optimal number of spares required for a specified period without introducing cost functions. The proposed methods are applied to the photon stop and the water-cooled flange which are major components in Pohang Light Source.

• Proceedings of the Korean Reliability Society Conference
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• 2000.04a
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• pp.201-208
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• 2000

We are concerned in the estimation of lifetime distribution of a component having a few observed failure data and we demonstrate that we can use the maximum likelihood estimation utilizing the censored data when the number of components in use is quite large. Weibull distribution is assumed fur the lifetime and a simple estimation procedure is introduced. We also propose the method of determining the optimal number of spares required for a specified period without introducing cost functions. The proposed methods are applied to the photon stop and the water-cooled flange which are major components in Pohang Light Source.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.11-15
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• 2018

The application of Wireless Sensor Networks requires a wise utilization of limited energy resources. Therefore, a wide range of routing protocols with a motivation to prolong the lifetime of a network has been proposed in recent years. Hierarchical clustering based protocols have become an object of a large number of studies that aim to efficiently utilize the limited energy of network components. In this paper, the effect of mismatch in parameter estimation is discussed to evaluate the robustness of a distanced based algorithm called distributed clustering protocol in homogeneous and heterogeneous environment. For quantitative analysis, performance simulations for this protocol are carried out in terms of the network lifetime which is the main criteria of efficiency for the energy limited system.

• Communications for Statistical Applications and Methods
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• v.23 no.5
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• pp.363-383
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• 2016

The Weibull family of lifetime distributions play a fundamental role in reliability engineering and life testing problems. This paper investigates the potential usefulness of transmuted new generalized Weibull (TNGW) distribution for modeling lifetime data. This distribution is an important competitive model that contains twenty-three lifetime distributions as special cases. We can obtain the TNGW distribution using the quadratic rank transmutation map (QRTM) technique. We derive the analytical shapes of the density and hazard functions for graphical illustrations. In addition, we explore some mathematical properties of the TNGW model including expressions for the quantile function, moments, entropies, mean deviation, Bonferroni and Lorenz curves and the moments of order statistics. The method of maximum likelihood is used to estimate the model parameters. Finally the applicability of the TNGW model is presented using nicotine in cigarettes data for illustration.

• Journal of Applied Reliability
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• v.2 no.2
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• pp.113-119
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• 2002

The estimation of mean lifetimes in presence of interval censoring with replacement procedure are examined when the distributions of lifetimes are exponential. It is assumed that, due to physical restrictions and/or economic constraints, the number of failures is investigated only at several inspection times during the lifetime test. The maximum likelihood estimator is found in an implicit form. The Cramer-Rao lower bounds of the estimates are found in places of variances and by simulations the properties of the estimates are examined.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.281-285
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• 2008

Wireless sensor networks are closely related with the geometric environment in which they are deployed. We consider the probable case when a routing protocol runs on an environment with many complex obstacles like downtown surroundings. In addition, there are no unrealistic assumptions in order to increase practicality of the protocol. Our goal is to find a routing protocol for maximizing network lifetime by using only connectivity information in the complex sensor network environment. We propose a topology-based routing algorithm that accomplishes good performance in terms of network lifetime and routing complexity as measures. Our routing algorithm makes routing decision based on a weighted graph as topological abstraction of the complex network. The graph conduces to lifetime enhancement by giving alternative paths, distributing the skewed burden. An energy estimation method is used so as to maintain routing information without any additional cost. We show how our approach can be used to maximize network lifetime and by extensive simulation we prove that out approach gives good results in terms of both measures-network lifetime and routing complexity.