• Journal of Korea Port Economic Association
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• v.36 no.3
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• pp.137-154
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• 2020

In this study, we analyze the performance of five major port distriparks and present a development plan. The analysis groups the performance into three categories: revitalization of companies in port distriparks, contribution to the port volume, and contribution to the national economy. The key parameters examined in detail include the ratio of hinterland volume to port volume (container and total cargo), port volume growth contribution rate, and job creation. Our results indicate that Gwangyang and Ulsan Ports showed steady growth for all the indicators analyzed, while Gwangyang Port was the only one among the five ports to display consistent steady growth. The results suggest that to achieve consistent growth, high value-added and specialized port distriparks based on the local economy should be established.

• Explosives and Blasting
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• v.35 no.3
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• pp.1-8
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• 2017

In this paper, parametric studies are conducted to evaluate the contribute effect of multi layered room and pillar mine structures by underground accidental explosions. Influence of PPV(Peak Particle Velocity) obtained from large explosion at a multi layered room and pillar mine was numerically simulated by using AUTODYN. Parameters for contribution rate Analysis was analyzed by the robust design method. Orthogonal array is $L_9(3^4)$, which was adopted in this study, the parameters were pillar height, pillar width, mine span and sill pillar of 3 levels. Results of analysis showed that bottom mine of vertical direction from explosion point are most affected by pillar height, followed by sill pillar thickness, mine span and pillar width. Parameters affecting adjacent mine of horizontal direction from explosion are in the order of pillar width, mine span, pillar height and sill pillar thickness.

• Journal of Gifted/Talented Education
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• v.27 no.1
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• pp.59-80
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• 2017

In this study, we investigate social preference of gifted students by analyzing their behaviors in social dilemma situations. We conducted an experimental study using ultimatum games and public goods games with 132 academically gifted middle school students who attended the Ewha-Seodaemun Center for gifted education from 2012 to 2016. We also experimented the same games with 87 regular students for comparative analysis. The result of ultimatum game experiment shows that there is no statistical difference in the proposed share of both groups. Their proposed share ranges from 37% to 38% as expected in other similar studies. However, the rejection rate of the respondents to the proposals with small share are significantly higher among gifted students than among their regular counterparts. This result implies that the gifted students show stronger negative reciprocity, meaning that they tend to punish selfish behaviors even when it takes some costs. In finitely repeated public goods game experiments, the results show that both groups' contribution rates decrease toward the end of the experiments. However, the gifted students show strategic cooperation by attempting to increase the other members' contribution rate within an experimental group. This implies that gifted students tend to care more about how to increase their own expected rewards by reciprocating other students' behaviors.

• The Korean Journal of Applied Statistics
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• v.28 no.4
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• pp.603-620
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• 2015

The National Pension of Korea is a public social security system designed to alleviate social risks and poverty that has had a major impact on the quality of life for the aging population. However, a rapidly aging population and low fertility threaten the sustainability of national pension in Korea. The National Pension Research Institute publishes a nancial projection every ve years; consequently, the government has lowered the entitlements for the sustainability of national pension based on the projection results. The current reform of the pension system that arbitrarily reduces the entitlements might detract from the income security role of the national pension for pensioners without accounting for the highest elderly poverty rate in the OECD countries. We first discuss methods for the financial projection of the national pension in terms of population, subscribers, and pensioner projections in order to estimate the pension reserve fund and the financial depletion year. We also conduct a sensitivity analysis for population variables, institutional variables, and economic variables based on pension reserves and the financial depletion year. We evaluate intergenerational fairness between the income hierarchy by conducting a money's worth analysis. Finally, we investigate the possibility of the sustainability of national pension by adjusting pension contributions and entitlements (income replacement rate). A new dependency ratio shows that a simple reform of the national pension does not secure the sustainability of the national pension without adapting a pay-as-you-go system.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.419-430
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• 2007

Physiochemical factors, phytoplankton biomass (Chl ${\alpha}$) and primary productivity were investigated seasonally in the three lakes of Dongbok, Juam, and Yeongsan during April 2004${\sim}$March 2006. Microphytoplankton dominated (>60%) in Dongbok lake, and phytoplankton biomass was high in the upper area, especially during April 2004, whereas they were high in the lower area during June 2004. In Juam lake, the high phytoplankton biomass in April 2004 was contributed by nanophytoplankton. In Yeongsan lake, chlorophyll a was high in August with high contribution of nanophytoplankton. Primary production was highest in Dongbok lake, and then followed by Yeongsan and Juam lakes. Regression analysis in Dongbok take showed that Chl ${\alpha}$ and primary production had close relations with secchi depth. In Juam lake, phosphate were correlated with the Chl ${\alpha}$, while temperature and TN was correlated with primary production in the lower area. In Yeongsan lake, Chl ${\alpha}$ have positively correlation with TN/TP. Primary production in the upper have high relationship with secchi depth, however, in the lower have high relationship with turbidity. Linear regression analysis showed that nutrients of nitrogen and phosphorus should be reduced for the protections in Juam and Dongbok lakes. We suggested that suspended solids and phytoplankton growth related to turbidity are needed to manage in Yeongsan lake.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.445-445
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• 2015

비점오염의 특성에 대해 지속적으로 연구 중이지만 수문특성과 연관성이 크다 보니 그 일관성에 대해 확실한 기법이 개발되지 않았다. 기법 개발과 효과적인 오염원 관리를 위해 SWMM 등의 모형을 활용하고 있지만 투입된 노력과 시간에 비해 그 효율성이 매우 적은 편이다. 이런 부분을 보완하고자 본 논문에서는 기존의 비점오염량 산정방법이 아니라 낙동강유역의 도시화 특성 및 수문/기상자료와 처리장 운영자료를 활용한 차별화된 원단위법을 통해 비점 배출 부하량 산정방법을 제시하려고 한다. 배수구역 내 관거 시스템을 합류식으로 가정하였고 배수구역별 비점 발생형태는 하수처리장의 강우 유입량, 하수처리장의 우회유량(Bypass 유량), 하수처리구역의 CSO 유량 3가지로 구분 지었다. 유입 방류자료와 강우자료를 활용하여 임계강우량을 3mm로 설정하여 3mm이상일 경우에 우회유량이 발생한다고 가정하였고 우회유량 발생시 오염부하량 산정은 건기평균유량에 유량변동부하율을 곱하여 시간최대유량으로 전환한 후 강우 지속기간 동안만 우회유량이 발생하는 것으로 가정하였다. CSO 유량은 처리구역/배수구역 면적비에 따라 3개의 그룹으로 구분한 뒤 검증된 SWMM-온천천 모형의 각 소유역별 불투수면적비와 비교하여 유사한 소유역을 각 그룹의 대표유역으로 선정하였다. 선정된 소유역의 CSO 유량과 수문현상의 비선형적인 관계를 고려할 수 있는 신경망 기법을 적용하여 강우특성에 따른 CSO 오염부하량 산정을 실시하였다. 산정결과를 바탕으로 각 하수처리장별 비점저감 기여율을 산정한 결과 대구북부 처리장에서 21.56%로 가장 높은 효율을 보여줬으며 거창가조 지점에서 0.11%로 가장 낮은 효율을 보여주는 것을 확인 할 수 있었다. 이러한 결과를 바탕으로 낙동강유역 내 위치한 하수처리장의 효율성에 대해 알 수 있으며 개선되어야 할 처리장들을 알 수 있었다. 또한 획일화된 방법이 아닌 차별화된 원단위법을 통한 오염부하량 산정은 앞으로의 연구방향에 있어서 좋은 사례가 될 것으로 사료된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.589-592
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• 2006

상수도는 도시의 일상생활 및 제반 활동을 유지시키는 중요한 사회기반 시설임에도 불구하고 시설 확대 이외의 종합적 관리 대책이 제시되지 않아 시설 노후화 및 불량으로 인한 낭비 요소가 매우 높다. 이와 같은 문제를 해결하기 위해 이 논문에서는 상수도의 생산에서 각 수용가에서 사용되는 부분에 대한 다양한 성격의 데이터들을 데이터베이스화 하고 이에 대한 분석 및 평가를 통해 무효수량 발생 원인을 쉽게 찾아 신속하게 대응함으로써 적은 노력으로 유수율을 향상시킬 수 있는 소프트웨어 시스템의 개발을 목표로 한다. 이 논문에서 개발한 유수율 제고 시스템은 상수도 시설에 대한 직접 탐사 이전에 누수 및 무효수량 발생 원인을 정량적으로 분석 평가함으로써 적은 비용으로 유수율 향상에 크게 기여할 것으로 기대된다.

• Economic Analysis
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• v.26 no.3
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• pp.1-47
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• 2020

This paper surveys research since the 1990s on the ability of the yield spread and its components (i.e., expectation spread and term premium components) for future economic activity, and also conducts an empirical analysis of their forecasting ability using the yield data of Korean government bonds. This paper's survey, particularly for the US, shows that the yield spread has significant predictive power for some macroeconomic variables, but since the mid-1980s, its predictive power seems to have declined, possibly due to stronger inflation targeting. Next, this paper's empirical analysis using Korean data indicates that the yield spread, and the term premium component in particular, has significant predictive power for industrial production (IP) growth, consumer price index growth, and the IP gap. An out-of-sample analysis shows that the prediction equations are unstable over time, and that in predicting IP growth, the yield spread decomposition makes a significant contribution to the prediction of IP growth.

• Proceedings of the Korea Technology Innovation Society Conference
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• 1998.05a
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• pp.19-19
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• 1998

본 연구에서는 정보통신산업의 연구개발 투자의 경제적 파급효과를 타 산업의 투자효과와 비교해 보았다. 연구개발자본단위당 평균적인 부가가치 증가액은 정보통신산업이 8.3억원으로 다른 산업(화학제품산업 5.6억원, 수송기계 4.8억원, 일반기계 3.4억원)에 비해 크게 나타났다. 연구개발자본 증가단위당 부가가치 파생율(부가가치 기여율을 연구개발자본량 증가로 나눈 값)도 정보통신부문 0.00041 %, 화학제품 0.00037 %, 수송기계 0.00027 %, 일반기계 0.00021 %의 순으로 평가되었다. 한편 ETRI에 대한 투자효과는 부가가치 창출액면에서 일반 기계산업보다 컸으며, 연구개발자본당 부가가치 파생액은 가장 큰 것으로 나타났다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.985-988
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• 2002

The Spindle-]fearing System is very important unit for geometrical accuracy in machine tools. To improve effectively the weak point of spindle system, it is necessary that the contribution ratio of spindle core parts to static and dynamic stiffness is clarified. In this paper, static contribution ratio of core parts is calculated by overlapping static deformation of basic spindle design with one flexible parts. The dynamic contribution ratio for natural frequency and dynamic deformation at spindle end is obtained by calculating correlation between original and basic spindle deformation, by curve fitting with regressive method. It is proved the validity of estimation result is correct.