• Geophysics and Geophysical Exploration
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• v.12 no.4
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• pp.289-298
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• 2009

Optimal data processing parameters were designed to attenuate multiples in seismic data acquired in the south-eastern area of the East Sea, in 2008. Bunch of multiples caused by shallow sea water depth were perceived periodically up to two way travel time of 1,750 ms at every 250 ms over seismic traces. We abbreviated sea bottom multiple as SBM, Peg-leg multiple as PLM, and free-surface multiple as FSM. To attenuate these multiples, seismic data processing flow was constructed including NMO, stack, minimum phase predictive deconvolution filter and wave equation multiple rejections (WEMR). Prevalent multiples were suppressed by predictive deconvolution and remaining multiples were attenuated by WEMR. We concluded that combining deconvolution with WEMR was effective to a seismic data of study area. Derived parameter can be applied to the seismic data processing on adjacent survey area.

• Korean Journal of Environment and Ecology
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• v.27 no.5
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• pp.571-578
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• 2013

This study generated regression models through a direct harvesting method to estimate carbon storage and uptake by Pinus densiflora and Pinus koraiensis, the major evergreen tree species in urban landscape, and established essential information to quantify carbon reduction by urban trees. Open-grown landscape tree individuals for each species were sampled reflecting various diameter sizes at a given interval. The study measured biomass for each part including the roots of sample trees to compute the total carbon storage per tree. Annual carbon uptake per tree was quantified by analyzing radial growth rates of stem samples at breast height. The study then derived a regression model easily applicable in estimating carbon storage and uptake per tree for the two species by using diameter at breast height (DBH) as an independent variable. All the regression models showed high fitness with $r^2$ values of higher than 0.98. While carbon storage and uptake by young trees tended to be greater for P. densiflora than for P. koraiensis in the same diameter sizes, those by mature trees with DBH sizes of larger than 20 cm showed results to the contrary due to a difference in growth rates. A tree of P. densiflora and P. koraiensis with DBH of 25 cm stored 115.6 kg and 130.0 kg of carbon, respectively, and annually sequestered 9.4 kg and 14.6 kg. The study has broken new grounds to overcome limitations of the past studies which quantified carbon reduction of the study species by substituting, due to a difficulty in direct cutting and root digging of landscape trees, coefficients from forest trees such as biomass expansion factors, ratios of below ground/above ground biomass, and diameter growth rates.

• Journal of the Korea Concrete Institute
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• v.13 no.3
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• pp.261-267
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• 2001

The objective of this experimental study is to find the allowable level of axial load to give the proper flexural ductility according to the yield strength of lateral ties, and the distribution and amount of longitudinal bars used in confined high-strength concrete columns. Twelve concrete columns with a 20 cm square section and 80 cm high were tested under hi-axial loads. It was observed that the ductility tends to be improved at the axial loads not less than 0.4f$\_$ck/A$\_$g/. The utilization of high-strength ties in accordance with the ACI 318-99 can cause the brittle failure due to the wide tie spacing. Under the high level of axial loads not less than 0.4f$\_$ck/A$\_$g/. it is necessary for the buckling prevention of the longitudinal bars and the proper ductility improvement to use the high-strength ties with the consideration of the volumetric ratio and confinement type of the lateral ties, and the distribution of the longitudinal bars.

• Journal of the Korea Concrete Institute
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• v.23 no.1
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• pp.13-22
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• 2011

In this study, ultimate strengths of 51 continuous reinforced concrete deep beams were evaluated by the ACI 318M-08's strut-tie model approach implemented with the presented indeterminate strut-tie model and load distribution ratio of the companion paper. The ultimate strengths of the continuous deep beams were also estimated by the shear equations derived based on experimental results, conventional design codes based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the presented strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables of shear span-to-effective depth ratio, flexural reinforcement ratio, and concrete compressive strength. The present study results of ultimate strengths obtained using the indeterminate strut-tie model and load distribution ratio of the continuous deep beams agree fairly well with those obtained using other approaches. In addition, the present approach reflected the effect of the primary design variables on the ultimate strengths of the continuous deep beams consistently and accurately. Therefore, the present study will help structural designers to conduct rational and practical strut-tie model designs of continuous deep beams.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.503-511
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• 2008

This paper presents the results of an analytical and experimental study on the performance of reinforced concrete beams subjected to pure torsion. The main parameters of the experimental tests were amount of torsional reinforcement and the ratio of the transverse torsional reinforcement to the longitudinal torsional reinforcement. The test results indicated that the maximum amount of torsional reinforcement required in ACI 318-05 code underestimated almost twice as much as the observed maximum amount of torsional reinforcement. Comparisons between the tested and calculated torsional behaviors of the 102 beams showed that the torsional failure modes of ACI 318-05 code disagreed with the observed failure modes. In addition, the torsion provisions in ACI 318-05 code overestimate the torsional strength of the RC beams in which relatively large amount of torsional reinforcement were reinforced, while underestimate for the beams with small amount of torsional reinforcement. This discrepancy between the theoretical ultimate torsional strength as given by the ACI 318-05 code and the experimental one can be due to neglecting the tension stiffening effect and the contribution of the torsional strength by concrete.

• Journal of the Korean Data and Information Science Society
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• v.27 no.4
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• pp.935-946
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• 2016

In this paper, we analyzed wage determinants of the vocational high school graduates utilizing both individual-level and work region-level variables. We formulate the models in the way wage determination has multi-level structure in the sense that individual wage is influenced by individual-level variables (level-1) and work region-level (level-2) variables. To incorporate dependency between individual wages into the model, we utilize hierarchical linear model (HLM). The major results are as follows. First, it is shown that the HLM model is better than the OLS regression models which do not take level-1 and level-2 variables simultaneously into account. Second, random effects on sex, maester dummy and engineering dummy variables are statistically significant. Third, the fixed effects on business hours and mean wage of regular job for level-2 variables are statistically significant effect individual-level wages. Finally, parental education level, parental income, number of licenses and high school grade are statistically significant for higher individual-level wages.

• Journal of the Korean Data and Information Science Society
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• v.27 no.5
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• pp.1375-1387
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• 2016

The purpose of this study was to evaluate the effect of exercise on cognitive function in the elderly through a systematic literature review and meta-analysis. For the study purpose, 14 studies were selected through a systematic process of using several databases and 11 studies were used to estimate the effect size of exercise on cognitive function. Meta-analysis was performed using a random effects model, and the effect size on cognitive function was calculated. The effect size for cognitive function of exercise intervention was Hedges' g=1.05 (95% CI: 0.61~1.50), indicating a large effect size. For heterogeneity, moderator analysis was performed using intervention, number of times per week, intervention duration, and cognitive function measurement. Cognitive function measurement was statistically significant, the other moderators did not significant difference. Results support that exercise has significant positive effects on cognitive function in elderly in korea. It also provided a basis that can be applied to exercise intervention design for cognitive function.

• Journal of the Economic Geographical Society of Korea
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• v.13 no.4
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• pp.548-560
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• 2010

This study aims to estimate the payment of farmland reverse mortgage(FRM) and to explore policy considerations about the restructuring of rural area after the initiation of farmland reverse mortgage. Farmland reverse mortgage provides stable monthly income basement for the welfare of rural elderly by liquidating fixed asset such as farmlands which the elderly in rural area owns. The main results of this study can be summarized as follows. First, FRM model based on Housing Equity Conversion Model, which is suggested by Rodda et al (2003), was built. Then, critical factors like farmland value rising rates and interest rates were elaborated, and affordable and proper monthly payment were estimated. 246,982 won, 419,374 won and 757,379 won is given to the borrower at age 65, 75 and 85 respectively with 100,000,000 won value farmland. Second, policy considerations which are necessary for the successful launch of FRM, and restructuring of rural area after launching FRM were discussed. Three policy considerations were proposed. First is about the integrated asset management system for rural elderly people. Second is about the reasonable settlement of corporate farmers system. And third is about the preparations for rural land use planning.

• Korean Journal of Social Welfare
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• v.56 no.1
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• pp.155-179
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• 2004

This study is about the effectiveness and activation strategies of vacational training programme for the disabled guided by the Ministry of Labour and the Korea Employment Promotion Agency for the Disabled(KEPAD). This research employed quantitative approach. The quantitative research used the samples of 853 disabled people who had finished vocational training programme during recent 3 years. In this research the effectiveness is categorized into two ; product effectiveness and employment effectiveness. Product effectiveness is influenced by the kind of train-center, train-area, train-length. The KEPAD, non-IT job area and train-period over 6 month are more effective. Employment effectiveness is significantly influenced by demo-sociological factor rather than disability factor. Especially the kind of train-center is very important to be employed for the disabled. This implicates that choice of train-center by the disabled and effective management of it by the public sector is very important in developing employment. Effective management, stated above, includes reengineering programmes and functions accountable to the need form the trainee, bridging the gap among train-centers in terms of performance, differentiation of financial support according to the product to save the public fund, encouraging one special programme in one train-center.

• Korean Journal of Social Welfare
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• v.52
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• pp.5-32
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• 2003

This paper examines the labor entry of conditional welfare recipients. This paper focuses on two questions. First, what is the percentage of conditional welfare recipients who have labor entry? Second, what are the predictors in the labor entry and the duration to the entry? Using Data about 917 welfare recipients who participated in the self-sufficiency programs of the Offices for Secure Employment in Seoul, this paper attempts to answer the above questions. Logistic regression analysis and survival analysis are adopted to identify variables predicting labor entry of conditional welfare recipients. This paper also utilizes a multiple imputation method to deal with the limitation of data by the missing values in some variables. The major findings are as follows: about 43.8% of the conditional welfare recipients have successful labor entry; and in the labor entry and the duration to the entry, gender, household, information and referral services for employment, health and willingness for self-sufficiency are the predictors that are statistically significant. Among these variables, health and willingness for self-sufficiency are more noticeable; it is recognized that programs to care for health of welfare recipients who want to have the labor entry and counseling programs to strengthen welfare recipients' willingness for labor entry are very important for them to be successful in the labor entry. This paper provides a basic knowledge about realities of the conditional welfare recipients' labor entry, identifies research areas for further research, and develops policy implications for their self-sufficiency.