• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.677-686
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• 2004

This study deals with literature review, developing a predicting equation for the ultimate stress of internal and external prestressing steel, and an experimental test with the parameters affecting the ultimate stress of prestressing steel in prestressed concrete beams strengthened by external prestressing tendons. The proposed predicting equation takes rationally the effect of internal and external prestressing steels into consideration as a function of prestressing steel depth to neutral depth ratio. In the experimental study, prestressed concrete beams strengthened using external steel tendons are tested with the test parameters having a large effect on the ultimate stress of internal and external prestressing steel. The test parameters include internal and external prestressing steel reinforcement ratio and span to depth ratio. The test results are analyzed to confirm the rationality and applicability of the proposed equation for predicting the ultimate stress of internal and external prestressing steel. This research shows that the results obtained by the proposed equation for predicting the ultimate stress agreed very well with the test results.

• KDI Journal of Economic Policy
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• v.30 no.2
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• pp.27-59
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• 2008

This paper empirically investigates the finance-growth linkage in Korea by utilizing firm-level data of manufacturing industries before and after the 1997 financial crisis. We find that, first, an increase in external finance is associated with a faster subsequent capital accumulation of firms. However, this capital accumulation channel became relatively attenuated after the crisis. Second, the total factor productivity growth effect of external finance has been considerably weak both before and after the crisis. Third, the information production and industry restructuring effects of external finance have also remained weak after the crisis. The limited role of external finance in post-crisis Korea partially reflects sluggish corporate investment and weakening dependence of good credit firms on external finance. The evidence suggests that, in order to effectively sustain economic growth, further reform efforts may be required to strengthen resource allocation and corporate restructuring roles of financial markets and institutions.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.823-826
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• 2008

This paper shows linkage management for external services. There are many services for specific entities such as DBLP and OntoWorld. OntoFrame, as a Semantic Web-based research information service portal, aims at one-stop service in ways that it connects external services with hyperlinks. For managing the linkage, linkage rules are manually edited by human administrators and automatically verified and tested by linkage management system. It consists of linkage rule management, linkage rule verification, linkage test, and dynamic link generation. Linkage rule management creates and edits linkage rules to connect external services on the Web. After finished rule editing and verification step, linkage management invokes linkage test with entity list. Only valid links are visible to enable users to click on our system, and thus it increases user's reliability on the system.

• The Journal of the Acoustical Society of Korea
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• v.42 no.3
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• pp.181-188
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• 2023

In a typical living space, windows are directly exposed to the external noise environment. The best way to reduce outside noise is to block it from the outside, not the inside. Exterior blinds for blocking sunlight are commercialized in various ways. However, it has not yet been actively utilized in Korea. In the previous study, an experiment was conducted in an accredited laboratory to verify the sound insulation performance of an external motorized blind manufactured for shading. And it was verified that there is a sound insulation performance of 6 dBA compared to the reduction performance of a general window. In this study, we tried to confirm the reduction performance by applying the sound insulation performance of external electric blinds to windows in actual living spaces. In addition, an improvement plan was sought to increase the effective noise reduction performance. As a result of the measurement, the reduction performance of the external motorized blind itself was insufficient at the level of 1 dBA to 3 dBA. However, additional reduction performance of the 2 dBA level was confirmed by filling the gap between the blind slits.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.387-387
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• 2020

본 연구에서는 LIP에 의한 극한강우로부터 발생되는 극한홍수량을 산정한다. Huff 형 강우시간 분포를 기후변화 시나리오별로 적용하고, 원전주변지역에서의 상세한 토지이용조건의 변화를 고려하여 빈도별 홍수량을 산정한다. 외부침수해석의 정교화를 위한 상세 지형자료를 구축하고, 원자력발전소 부지의 상세 DEM 자료를 생성한다. 이를 위해서 원자력발전소 부지에서 건물, 연석, 도로 등의 영향을 분석하고 토지이용상황에 따른 조도계수를 산정한다. 또한 원전지역에서의 외부침수재해도 분석을 위해서 국립해양조사원에서 검토한 기후변화를 고려한 조위분석 자료를 외부경계조건으로 설정한 후 부지에 대한 2차원 수리분석을 실시한다. 침수심, 침수유속, 침수시간, 침수동압력 분석 등 2차원 침수해석결과를 바탕으로 발생빈도별 침수심, 침수강도 등의 정량적인 분석을 통해서 빈도별 재해도 곡선을 개발한다. 그리고 원전지역에서의 외부 침수에 대한 대표적인 재해도 곡선을 산정하기 위하여 재현기간별 지속시간에 따른 침수심을 분석하고 정리한다. 재현기간별 침수심에 대해 확률 분포형을 적용하기 위해서 AIC검증을 통한 분포형의 적합성을 분석을 실시한다. 또한 재현기간별 지속시간에 따른 침수심들 간의 상관관계를 분석하여 분포형에 적용한다. 적용된 분포형을 몬테칼로 시뮬레이션을 통한 대표적인 확률론적 외부 침수 재해도 곡선을 산정한다. 본 연구를 바탕으로 원전 부지 및 그 부속 시설물(SSC)의 홍수방지 기능과 홍수 대비 시설물에 대한 적용 절차의 신뢰성, 홍수 저감 및 대응 전략에 대한 정량화가 가능하여 원전 홍수 위험에 대한 정량적인 평가 지원이 가능하겠다. 고려할 외부 홍수와 관련된 원전 내부시설 및 장비에 대한 상세한 모델링 절차, 특정 시나리오에 대한 홍수 방지 및 예방과 관련한 SSC의 정량화, 홍수저감 활동과 관련된 통제실 외부 시설물에 대한 수동 조작에 대한 평가가 이루어질 수 있겠다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.809-817
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• 2008

Recently, the external prestressing method is being much frequently used in strengthening reinforced concrete structures because of it's excellent load resistance and serviceability increases comparing to other strengthening methods. However, it is true that the research on fatigue performance of concrete structures strengthened by the external prestressing using FRP tendons is rare. Therefore, the purpose of this study is to evaluate the safety and feasibility of the external prestressing method by analyzing the characteristics of the reinforced concrete beam strengthening using FRP tendons under repeated loads. Test variables adopted in this experimental study are the types of external prestressing material (steel or FRP tendon) and the repeated load ranges. The repeated load range have the minimum 50% of yield load of reinforced concrete beam and the maximum 70-85%. The test beams are loaded by 4 point loadings with 3 Hz sine wave. From this experimental study, it is confirmed that the reinforced concrete beams strengthened using FRP tendons have sufficient safety against fatigue, especially in FRP tendon itself, tendon at deviators and tendon at anchorages.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.54-62
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• 2003

The satellite in space has a tiny size but is subject to the disturbance torques caused by various sources. The presence of environmental disturbance torques significantly affects the orient as well as the orbital motion of satellite. The sources of environmental effects on LEO Satellite attitude dynamics are various. Four of these, gravity gradient, Earth's magnetic field, solar radiation pressure and aerodynamic are dominant and deterministic. In this study, we describe the model of environmental disturbance torques acting on LEO Satellite and the effects of environmental disturbance torques on LEO Satellite attitude dynamics in detail.

• Journal of Korean Library and Information Science Society
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• v.41 no.4
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• pp.269-293
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• 2010

Opening university library doors to the community is essential to meeting their demands and it is also the duty of university libraries. Since opening doors of university libraries have become more and more significant, this study analysed the conditions of the university libraries that have the open-door policy to external users and carried out an analysis of problems caused by the open-door policy. The following alternatives were suggested : the introduction of the membership system about the external users, the role division of university library and local public libraries, reinforcement of external library user education, and access management about external users.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.703-705
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• 2013

외부 데이터베이스를 사용해서 서비스하는 스마트폰 어플리케이션은 네이티브 앱과 모바일 웹을 병행하여 서비스 한다. 일반적인 어플리케이션 환경에서는 외부 데이터베이스에 리소스 및 연산 결과 등의 모든 정보를 담아 두고 접근하여 활용하는 방식을 사용하였다. 반면에 스마트폰 어플리케이션 환경에서 네이티브 앱을 활용하면 디바이스 내부에 외부 데이터베이스의 정보 및 리소스를 저장하여 활용한다. 이 경우 네이티브 앱에서 연산을 수행하고 변경되는 데이터가 발생하면 외부 데이터베이스에 접근하여 업데이트를 수행한다. 그 이유는 병행 접근이 가능한 서비스의 경우 차후에 현재 접근한 네이티브 앱이 아닌 모바일 웹으로 접근하였을 때를 대비해서 최근의 데이터를 항상 유지해야 하기 때문이다. 많은 사용자를 보유한 서비스의 경우 빈번히 발생하는 데이터 업데이트 문제로 많은 자원 소모가 발생된다. 본 논문에서는 앞서 언급한 문제를 해결하고 네이티브 앱과 모바일 웹간의 데이터 연동을 위하여 외부 데이터베이스의 접근을 최소화 하는 기법을 제안한다. 실시간으로 사용자들끼리 정보를 주고받아 상호작용하는 서비스의 빈도가 상당히 낮거나 없는 스마트폰 어플리케이션 환경에서는 서버 접근을 최소화 하는 것이 좋은 방법이다. 제안의 핵심은 네이티브 앱과 모바일 웹의 기본적인 접속 정보만 외부 데이터베이스에 업데이트하여 차후 접속하는 타입이 현재와 다른 경우에만 최근에 변경된 데이터를 외부 데이터베이스에 업데이트하여 서버의 부하를 최소화 하는 것이다. 이 기술을 활용하면 서비스 업체의 경우 서버 유지비용을 낮출 수 있으며 사용자는 빈번히 일어나는 서버와의 통신에 소요되는 비용 및 끊김 현상으로 인한 불편함을 최소화할 수 있을 것으로 사료된다.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.4
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• pp.627-644
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• 2009

In the knowledge-based economy highlighting the importance of human capital, there has been a growing interest in human capital externalities as a fundamental engine of growth and development of a region. The purpose of this study is to analyze human capital externalities using 3-level hierarchical linear model(3-HLM), decomposing determinants of wages into three levels involving workers(level-1) nested within firms(level-2) nested within regions(level-3). This study separately estimates the effect of the average education level on the wages by three different schooling groups on the assumption that the intensity of knowledge spillovers varies with each group's schooling level. The main results are as follows; First, the coefficient of the average education level of a region shows 0.044, indicating that one-year increase in the average level of schooling could increase average individual earnings by 4.4%. Secondly, the external effects of human capital on three different schooling groups are considerably different, raising less than high school graduates' wages by 3.0%, college graduates' wages by 4.7%, and graduate schools' wages by 11.8%, respectively. Thirdly, well educated workers are much more sensitive to the variation of the regional education level than less educated ones when we apply the shares of each schooling group as alternative measures for the average level of education. Such findings of this study draw an implication that local governments could speed up regional economic growth in the knowledge-based economy by not only raising total human capital stock in a region but building the close networks that promote productivity-enhancing human capital external effects.