• The Korean Journal of Financial Management
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• v.25 no.4
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• pp.183-212
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• 2008

The purpose of this paper is to analyze the efficiency change and determinants of the korean non-life insurance companies. we use DEA (Data Envelopment Analysis) model to measure company efficiency change and use GLS, Tobit model, FIixed effect model, Random effect model, GMM to measure efficiency determinants. we utilize ten non-life insurance companies in korea and the panel data for five from 2001 to 2005. The empirical results show the following findings. First, technical efficiency shows that approximately 15.5% of inefficiency exists on the non-life insurance companies and it reveals that the cause for technical inefficiency is due to scale inefficiency. Second, Dea Window results show that the stable dissimilarity by standard deviation, LDP of CCR. Third, the results of efficiency determinants show that increase efficiency is depend on the premium income and real estates.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.1
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• pp.70-74
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• 1997

Data on 2,571 lactation records of Nili-Ravi buffaloes from four institutional herds and four field recording centers were analyzed under an animal model to see the effect of season definition on the error variance of the fitted model. Herd-year-season(HYS) was the main fixed effect along with permanent environment, breeding value and residuals as the random effects. All known relationships among the animals were considered. The error variance differed for various HYS combinations. It was minimum when then months were not grouped into seasons. The four or Five season scenarios were better than the two season scenarios. The average number of lactations represented in a HYS combination varied widely from 6 to 28. Very few subclasses for a given HYS combination warrants the use of fewer seasons for animal model evaluation of buffaloes.

• Journal of Information Technology Services
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• v.6 no.3
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• pp.87-110
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• 2007

Recently, researches on IT Service Management (ITSM) for improving information system operation service and information system outsourcing cost estimation model are proliferating. This study suggests a new cost model of IT operation service and optimizing method based upon the characteristics of operation service as a long-term and continuous business service for both user's and service provider's point of view. This study explains the cost optimization model of IT operation service by improving service request management process, such as adequate reception and control, proper valuation, process management using project management methodology, effective organization and time management of service personnel. Especially in this study, service ability improvement effect and fixed operation cost reduction effect are defined to prove the proposed new cost model.

• Health Policy and Management
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• v.32 no.1
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• pp.29-44
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• 2022

Background: This study was conducted to analyze the impact of having a usual source of care on health behaviors of the middle aged and the elderly, in order to investigate the potential effect of enhancing primary health care in a Korean context. Methods: This study constructed a balanced panel of middle-aged and elderly samples using the Korea Health Panel 2016-2018, and fixed-effect models were used to analyze the data. Results: Among three sets of dependent variables (physical activity, smoking, drinking), statistically significant results were found only in physical activity. Subgroup analysis showed that this effect was not observed in the late elderly (aged 75 and older) and those without chronic diseases. Conclusion: Results of the study implied that enhancing primary health care among middle age and the elderly may have an effect on improving health behaviors. Moving forward to person-centered primary health care from disease-focused primary health care should be considered in high-risk groups such as the middle aged and the elderly with chronic diseases.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.49-56
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• 2009

This paper shows the characteristic analysis of single-phase line start permanent magnet (LSPM) motors considering the overhang structure. To achieve the low-cost design of an LSPM motor, the overhang structure is adapted for the rotor with a constraint of a fixed magnet volume. To obtain the dynamic and steady performance of the motor, the circuit parameters are extracted using the 3D-static FEM(Finite Element Method) and the d-q equivalent circuit is used. The performance of the model with overhang is compared with the conventional model without overhang on the condition that both models have a fixed volume for the permanent magnet.

• Journal of applied mathematics & informatics
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• v.42 no.2
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• pp.305-320
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• 2024

We consider a mathematical model which describes the quasistatic contact of electro-viscoelastic rod with an obstacle. We use a modified Kelvin-Voigt viscoelastic constitutive law in which the elasticity operator is nonlinear and locally Lipschitz continuous, taking into account the piezoelectric effect of the material. We model the contact with a general damped response condition. We establish a local existence and uniqueness result of the solution by using arguments of time-dependent nonlinear equations and Schauder's fixed-point theorem and obtain a global existence for small enough data.

• Earthquakes and Structures
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• v.16 no.1
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• pp.69-82
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• 2019

As the residual displacement and/or drift demands are commonly used for seismic assessment of buildings, the estimation of these values play a very critical role through earthquake design philosophy. The residual displacement estimation of fixed base structures has been the topic of numerous researches up to now, but the effect of soil flexibility is almost always omitted. In this study, residual displacement demands are investigated for SDOF systems with period range of 0.1-3.0 s for near-field and far-field ground motions for both fixed and interacting cases. The elastoplastic model is used to represent non-degrading structures. Based on time history analyses, a new simple yet effective equation is proposed for residual displacement demand of any system whether fixed base or interacting as a function of structural period, lateral strength ratio and spectral displacement.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.220-227
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• 2006

In this paper, we present a novel approach to analyze the throughput of direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA system. In the unslotted system, the departure rate of interfering transmissions is proportional to the number of current interferers that can be regarded as the system state. In order to model this state-dependency, we introduce a two-dimensional state transition model that describes the state transition of the system. This model provides a more rigorous analysis tool for the DS/SSMA unslotted ALOHA systems with both fixed and variable packet lengths. Numerical results reveal that this analysis yields an accurate system performance that coincides with the simulation results. Throughout the analysis we have discovered that the state-dependency of the departure rate causes interference averaging effect in the unslotted system and that this effect yields a higher throughput for the unslotted system than for the slotted system when supported by a strong channel coding.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.6
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• pp.379-389
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• 2016

This study intends to evaluate the conservativeness of the fixed-base analysis as compared to the soil-structure interaction (SSI) analysis for the seismically isolated model of a nuclear power plant in Korea. To that goal, the boundary reaction method (BRM), combining frequency-domain and time-domain analyses in a twofold process, is adopted for the SSI analysis considering the nonlinearity of the seismic base isolation. The program KIESSI-3D is used for computing the reaction forces in the frequency domain and the program MIDAS/Civil is applied for the nonlinear time-domain analysis. The BRM numerical model is verified by comparing the results of the frequency-domain analysis and time-domain analysis for the soil-structure system with an equivalent linear base isolation model. Moreover, the displacement response of the base isolation and the horizontal response at the top of the structure obtained by the nonlinear SSI analysis using BRM are compared with those obtained by the fixed-base analysis. The comparison reveals that the fixed-base analysis provides conservative peak deformation for the base isolation but is not particularly conservative in term of the floor response spectrum of the superstructure.

• Journal of Korea Port Economic Association
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• v.30 no.2
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• pp.133-143
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• 2014

The paper uses a panel gravity model to analyse the determinants of export via Gwangyang port for the period from 2000-2012. The gravity model includes export via Gwangyang port, GDP and population of trading partners, the distances between Korea and its partners, and Korea-ASEAN FTA dummy. Hausman test shows up which one is exactly appropriate between random effect estimation and fixed effect estimation to use panel dataset. It depends on whether or not existence or nonexistence of the correlation between unobserved omitted factors and variables. Fixed effect estimation is suitable for this paper by the rejection of null hypothesis. An Empirical analysis of this paper shows GDP influences positive effects and distance influences negative effects to Gwangyang port trading partners. In addition, the results strongly supported the effects of Korea-ASEAN FTA on the growth of Gwangyang port export.