• Magazine of the Korea Concrete Institute
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• v.4 no.2
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• pp.83-92
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• 1992

본 연구의 목적은 현장에서 구입 가능한 저품질의 재료를 사용한 일련의 실험을 통하여 28일 압축강도와 물\ulcorner시멘트비와 관계를 유출함으로써 고강도 콘크리트의 배합설계식을 얻기 위한 것이다. 목표슬럼프는 고층건물에서의 시공성을 고려하여 15$\pm$2cm로 하였으며 혼화제로는 고성능감수제를 사용하였다. 실험결과로부터 고강도콘크리트의 응력-변형도 특성을 비롯하여 탄성계수, 포아송비, 단위중량 등 고강도 콘크리트의 일반적인 재료성질을 얻었으며 본 연구에서 제안한 고강도콘크리트의 배합설계식은 국내현장조건을 고려한 실용식으로 고강도콘크리트으 설계 및 시공을 위한 기초자료로 사용 가능하다고 판단된다.

• Journal of the Korean Data and Information Science Society
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• v.28 no.5
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• pp.1087-1097
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• 2017

This study aims to find the best model to fit the number of insurance solicitor's turnovers of life insurance companies using count data regression models such as poisson regression, negative binomial regression, zero-inflated poisson regression, or zero-inflated negative binomial regression. Out of the four models, zero-inflated negative binomial model has been selected based on AIC and SBC criteria, which is due to over-dispersion and high proportion of zero-counts. The significant factors to affect insurance solicitor's turnover found to be a work period in current company, a total work period as financial planner, an affiliated corporation, and channel management satisfaction. We also have found that as the job satisfaction or the channel management satisfaction gets lower as channel management satisfaction, the number of insurance solicitor's turnovers increases. In addition, the total work period as financial planner has positive relationship with the number of insurance solicitor's turnovers, but the work period in current company has negative relationship with it.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5585-5593
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• 2014

This study tested the hypothesis that the significance of the heterogeneous dispersion parameter in safety performance function (SPF) used to estimate the expected crashes is affected by the endogenous heterogeneous prior distributions, and analyzed the impacts of the mis-specified dispersion parameter on the evaluation results for traffic safety countermeasures. In particular, this study simulated the Poisson means based on the heterogeneous dispersion parameters and estimated the SPFs using both the negative binomial (NB) model and the heterogeneous negative binomial (HNB) model for analyzing the impacts of the model mis-specification on the mean and dispersion functions in SPF. In addition, this study analyzed the characteristics of errors in the crash reduction factors (CRFs) obtained when the two models are used to estimate the posterior means and variances, which are essentially estimated through the estimated hyper-parameters in the heterogeneous prior distributions. The simulation study results showed that a mis-estimation on the heterogeneous dispersion parameters through the NB model does not affect the coefficient of the mean functions, but the variances of the prior distribution are seriously mis-estimated when the NB model is used to develop SPFs without considering the heterogeneity in dispersion. Consequently, when the NB model is used erroneously to estimate the prior distributions with heterogeneous dispersion parameters, the mis-estimated posterior mean can produce large errors in CRFs up to 120%.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.57-67
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• 2008

Two test methods, nonrepetitive plate loading test (NPLT) and repetitive plate loading test (RPLT) are being used to control the quality of compaction through the evaluation of the stiffness of subgrade soils in the Korea railway industry. Subgrade reaction modulus ($k_{30}$) from the NPLT and strain modulus ($E_v$) from the RPLT are the index values to check them. The methods have similar aspects, but they differ in the modulus evaluation method, the numbers of loading stage, termination procedures, etc. This paper analyses the differences of the two test methods and evaluates the relationship between subgrade reaction modulus and strain modulus. In order to develop the relationship, total 22 tests were performed including the NPLT and the RPLT at the 6 original grounds, and 5 upper or lower subgrades in Kyungbu High Speed Railway II stage construction sites. According to the soil conditions, the relationship between subgrade reaction modulus and strain modulus was proposed with corrections by considering strain states, mean confining pressures, and Poisson's ratio.

• Journal of the Korean Geotechnical Society
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• v.35 no.7
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• pp.41-50
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• 2019

Gyeongju bentonite is a buffer material primarily considered in Korea and it is highly compacted as a part of an engineered barrier system (EBS) of high-level radioactive waste repository. The compacted bentonite undergoes swelling stress by groundwater penetration and thermal stress by decay heat from a canister. Therefore, the mechanical properties of the compacted bentonite buffer material is crucial for the performance assessment of EBS. This paper aims to evaluate deformation properties of Gyeongju compacted bentonite using seismic methods. Two sets of compacted bentonite specimens were prepared having dry densities of $1.59g/cm^3$ and $1.75g/cm^3$ with water contents of 10.6% and 8.7%. Free-free resonant column tests were performed to measure constrained and unconstrained compression wave velocities. With the measured wave velocities, Young's modulus ($E_{max}$) and constrained modulus ($M_{max}$), material damping ratio ($D_{min}$), and Poisson's ratio at small strain were determined. As results, this paper evaluates the deformation properties of Gyeongju compacted bentonite and compares them with the results of previous researches.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.261-270
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• 1999

In these days, construction activities have caused civil petitions associated with vibration-induced damages or nuisances. Therefore, it is strongly needed to develop a remedial technique to mitigate unfavorable effects. The objective of this experimental research is to investigate material and structural dynamic characteristics of vibration-controlled concretes which have been proportionally mixed with various vibration reducing material, such as latex, rubber powder, plastic resin, polystyrofoams and etc. Normal and high strength concrete specimens are also prepared for corresponding comparison. As part of the recycling research for obsolete rubber and plastic materials, 32 concrete cylinders and 10 concrete flexural beams have been made for material and structural dynamic properties, respectively. In accordance with the resonance test on concrete cylinders, it can be concluded that concrete with vibration-reducing material have relatively larger material damping ration than normal or high strength concrete. Styrofoam is determined to be very effective vibration-reducing mixtures. From the vibration test on 10 concrete flexural beams, meamwhile, of importance observations was that material damping ratio is very smaller than structural damping ratio of corresponding specimen. But further vibration test on more flexural beams should be strongly needed by varying support conditions.

• Convergence Security Journal
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• v.12 no.1
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• pp.9-16
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• 2012

Due to the large scale application of software systems, software reliability plays an important role in software developments. In this paper, a software reliability growth model (SRGM) is proposed for testing time. The testing time on the right is truncated in this model. The intensity function, mean-value function, reliability of the software, estimation of parameters and the special applications of Pareto NHPP model are discussed. This paper, a numerical example of applying using time between failures and parameter estimation using maximum likelihood estimation method, after the efficiency of the data through trend analysis model selection, depended on difference between predictions and actual values, were efficient using the mean square error and $R_{SQ}$.

• The Korean Journal of Applied Statistics
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• v.31 no.4
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• pp.475-484
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• 2018

Gamma generalized linear models are useful for non-negative and skewed responses. However, these models have received less attention than Poisson and binomial generalized linear models. In particular, hypothesis testing for the significance of regression coefficients has not been thoroughly studied. In this paper we assess the performance of various test statistics for gamma generalized linear models based on numerical studies. Our results show that the likelihood ratio test and F-type test are generally recommended and that the partial deviance test should be avoided in practice.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.137-141
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• 2006

To consider the practical use of a ship's Digital Compass in earth's magnetic field high accurate Deviation and 얘 nation are required to obtain ship's true bearing. Variation can be obtain with World Magnetic Model (WMM) using the Earth's spherical harmonic model of the main field and of the secular variation at any location around the earth. Deviation can be obtain with deviation analysis and synthesis method based on the Poisson equations. As results of deviation and variation corrections to the Digital Compass, high accurate true bearing is obtained. This experiments are carried out during in the navigation of training ship 'SAE-NU-RI'.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.789-794
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• 2011

We analyze the capacity of CDMA base stations in the subway environment. We investigate the characteristics of multipath fading, cell structures, and propagation environment in the subway, analyze signal to noise ratio, sectorization gain, path-loss exponent, frequency reuse factor, and obtain the link capacity of a base station in the subway. We measure the peakedness factor and reveal that base stations in the subway have peaked traffic. We use Neal-Wilkinson model to obtain the Erlang capacity instead of Erlang-B model based on Poisson traffic.