• 대한소아치과학회지
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• 제24권2호
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• pp.383-404
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• 1997

In this study, we tried to compare the effect of glass inserts on marginal leakage of composite resin restoration by comparing with that of several filling methods. The results obtained from this experiment were as follows ; 1. The degree of microleakage measured in glass inserts group was generally lower than that of the other groups. Statistical analysis showed significant intergroup difference between glass inserts and one complete unit, pre-polymerized composite resin ball(P<.05), but no significant difference between groups of glass inserts and increments(P>.05). 2. Scanning electron microscopic observation showed relatively large gap around resin-tooth interface in specimens restored the method of using the one complete unit and pre-polymerized composite resin ball whereas a denser and tighter was observed in increments and glass inserts group. Generally the gingival margin was shown to have better bonds than the occlusal margin in specimen of all groups. 3. In the present experiment, methods using the techniques of glass inserts and increments were evaluated to be superior to those of one complete unit, pre-polymerized composite resin ball in the aspect of microleakage. However, the result of this study could not determine the superiority of the use of glass inserts over incremental method. Besides the physical properties observed in this study, the practical aspect of clinical convenience should be considered in determining the selection of material.

• 지질공학
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• 제13권4호
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• pp.445-456
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• 2003

배면그라우팅과 압밀그라우팅 보강기슬은 터널의 안정성 향상을 위해 터널현장에서 활발히 사용되고있다. 그러나 이에 대한 시공 및 관리 기술 연구는 상대적으로 대단히 미흡한 실정이다. 본 연구에서는 심부에 위치한 도수로 터널 시험 구간에 대하여 그라우팅 전후의 각종 현장 시험과 라이닝 계측을 실시하여 압밀그라우팅 및 배면그라우팅 보강이 콘크리트 라이닝의 응력 및 변형 특성에 미치는 영향을 분석하였다. 터널 그라우팅 보강 효과를 연구한 결과, 그라우팅 보강으로 인해 암반의 탄성계수는 최대 5배까지 증가하였으며 전체적으로 그라우팅의 고결효과는 주목할 만 하였다. 또한, 라이닝 배면에 작용하는 그라우팅 압력은 주입압의 약 10%에 불과하였다. 본 연구 결과는 콘크리트 라이닝 설계시 활용될 수 있을 것으로 기대된다.

• 자원리싸이클링
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• 제5권3호
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• pp.9-16
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• 1996

철강슬래그를 이용하여 아스팔트 콘크리트 충전제로서 적용가능성을 확인하고 사용하기 위해 시행되었다. 고로 수재슬래그, 고로 괴재슬래그와 전로슬래그를 아스콘 충전제로 재활용하기 위하여 슬래그를 분해하여 물리적, 화학적 성질을 조사하여 아스콘 충전제로의 사용가능성을 확인하였다. 아스팔트 콘크리트 제조시 200mesh 이하의 슬래그 분말을 충전후에 측정한 여러 가지 기계적 성질은 KS규격을 충족시켰다. 아스팔트와의 혼합온도는 140~16$0^{\circ}C$이었고, 밀도, 안정도, 공극률과 포화도는 각각 2.37g/㎤, 810kg, 3.4%와 80.4%이었다.

• 소성∙가공
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• 제13권6호
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• pp.503-508
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• 2004

Preform design techniques have been investigated to reduce die wear and forming load and to improve material flow, filling ratio, etc. In hot forging processes, a thin deformed part of a workpiece, known as a flash, is formed in the narrow gap between the upper and lower tools. Although designers make tools that generate a flash intentionally in order to improve flow properties, excessive flash increases die wear and forming load. Therefore, it is necessary to make a preform shape that can reduce the excessive flash without changing flow properties. In this paper, a new preform design technique is proposed to reduce the excessive flash in a metal forging process. After a finite element simulation of the process is carried out with an initial billet, the flow of material in the flash region is traced from the final shape to the initial billet. The region belonging to the flash is then easily found in the initial billet. The finite element simulation is then carried out again with the modified billet from which the selected region has been removed. In several iterations of this technique, the optimal preform shape that minimizes the amount of flash without changing the forgeability can be obtained.

• 박물관보존과학
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• 제3권
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• pp.15-19
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• 2001

이번 가네코 카즈시게 선생이 기증한 여러 유물 중 금자(金子)124 수호는 약 60여개 정도의 파편을 접합하고, 자체 하중을 견딜 수 있는 접착제를 적절하게 사용하여 결손부분을 복원하였다. 또한 보존처리를 하는 동안에도 항상 가역성을 염두에 두면서 처리하였고, 색맞춤도 미관상 어색함이 없는 범위 내에서 처리하였다. 그 결과, 기형이 둥근 점토질의 박형(珀形) 항아리로 새롭게 탄생하였다.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3359-3366
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• 2021

An engineered barrier system (EBS) for the deep geological disposal of high-level radioactive waste (HLW) is composed of a disposal canister, buffer material, gap-filling material, and backfill material. As the buffer fills the empty space between the disposal canisters and the near-field rock mass, heat energy from the canisters is released to the surrounding buffer material. It is vital that this heat energy is rapidly dissipated to the near-field rock mass, and thus the thermal conductivity of the buffer is a key parameter to consider when evaluating the safety of the overall disposal system. Therefore, to take into consideration the sizeable amount of heat being released from such canisters, this study investigated the thermal conductivity of Korean compacted bentonites and its variation within a temperature range of 25 ℃ to 80-90 ℃. As a result, thermal conductivity increased by 5-20% as the temperature increased. Furthermore, temperature had a greater effect under higher degrees of saturation and a lower impact under higher dry densities. This study also conducted a regression analysis with 147 sets of data to estimate the thermal conductivity of the compacted bentonite considering the initial dry density, water content, and variations in temperature. Furthermore, the Kriging method was adopted to establish an uncertainty metamodel of thermal conductivity to verify the regression model. The R² value of the regression model was 0.925, and the regression model and metamodel showed similar results.

• Journal of Plant Biotechnology
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• 제45권4호
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• pp.299-305
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• 2018

Although new plant breeding technologies facilitate efficient plant breeding without introducing a transgene, they are creating indistinct boundaries in the regulation of genetically modified organisms (GMOs). The rapid advancement in plant breeding by genome-editing requires the establishment of a new global policy for the new biotechnology, while filling the gap between process-based and product-based GMO in terms of regulations. In this study recent developments in producing major crops using new plant breeding technologies were reviewed, and a regulatory model that takes into account the various methodologies to achieve genetic modifications as well as the resulting types of mutation were proposed. Moreover, the communication process were discussed in order to understand consumers' current situation and problems of new plant breeding technology, establish social acceptance well, and understand consumers' disputes such as GMO crops.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.191-191
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• 2018

최근 기후 변화로 인한 기상이변으로 인해 가뭄의 심도와 지속시간이 길어져 이로 인한 피해가 가중되고 있다. 본 연구는 국가 물 관리에 필요한 증발산량 자료 생산과 특성을 분석할 목적으로 수행되었으며, 본 연구 결과는 국가 물 관리 및 가뭄 분석 등에 활용될 수 있을 것으로 판단된다. 2010년 국토교통부에서는 "국가수문관측망"에 증발산량 관측소를 포함하여 증발산량 자료가 정기적으로 생산될 수 있게 하였다. 계획수립 이후 일정기간 동안은 관측 방법과 품질관리 방법 등의 체계화되지 않아 전국적으로 확대되지 못하다가 최근에 와서 확대 설치되고 있다. 현재에는 증발산량 관측소가 한강수계 4개소, 금강수계 2개소, 영산강수계 3개소에서 운영되고 있다. 국토교통부 증발산량 관측소는 에디공분산 방식으로 구축되어 있으며, 자료는 30분 간격으로 생산되고 있다. 본 연구에서는 설마천 관측소의 3개년(2015년~2017년) 자료로 산지 증발산량의 경년 변화를 분석하였다. KoFlux 표준화 프로그램(spike 제거, 밀도 보정 등)으로 자료를 처리하였으며, 자료 보충(Gap-filling)은 FAO-PM, MDV, Kalman Filter 방법으로 수행하였다. 설마천 관측소에서 증발산량을 산정하여 산지 증발산량의 경년변화를 분석한 결과, 증발산량은 강수량과 순복산량의 규모에 따라 상이하였다. 또한 비교적 강수량이 적은 해에 증발산 비율이 커지는 특성을 나타내었다. 이는 가뭄 시 증발산을 왕성하게 하는 환경이 조성되어 발생되는 것으로 분석되었다.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.339-352
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• 2021

This study aims to explore the relationship between entrepreneurial role models (ERM) and entrepreneurship education (EE) on individual entrepreneurial orientation (EO) and its consequences for entrepreneurial intention (EI). Data is obtained through a survey method on 255 management and business university students who had completed the entrepreneurship education program. To evaluate the research model, the data is processed using PLS-SEM. The results of this study indicate that the existence of entrepreneurial role models and entrepreneurial education programs for students affects the components of individual entrepreneurial orientation, namely individual innovativeness, individual proactiveness, and individual risk-taker. However, ERMs do not have a direct effect on EI. The main finding of this research appears on the influence of individual EO on EI, which indicates that only individual innovativeness impacts entrepreneurial intention. Meanwhile, personal proactiveness and risk-takers are proven to have no impact on EI. This study succeeded in filling the research gap, namely, examining the influence of ERMs on each of the components forming an individual entrepreneurial orientation (IEO) and its EI. This research model also provides a comprehensive research model on the influence of pre-entrepreneurial exposure on IEO and its consequences on EI.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.881-891
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• 2020

In recent years robotics has become an important resource in engineering. Adoption of Robotics and Autonomous Systems (RAS) in activities related to ship inspections has obvious potential advantages, but also arises particular challenges, both from technical and legal viewpoints. The ROBINS project (ROBotics technology for INspection of Ships) is a collaborative project co-funded within the H2020 EU Research and Innovation programme call, aimed at filling the gap between current ship inspections approach and available robotic technology, both from technological and regulatory point of view. Main goal of the present work is to highlight how ship inspections are currently carried out by humans, how they could be improved using RAS, even if not completely autonomous for the time being, at least in selected operational scenarios and how the performances of RAS platforms can be tested to assess their effectiveness in carrying out surveys onboard. In such a framework, a testing facility aimed at assessing RAS' capabilities as well as providing suitable environment for their development has been built and it is still under development along with dedicated testing protocols, able to assess the equivalence between human and RAS inspection of ship and marine structures. The features of a testing facility where RAS can be tested and the testing protocols are presented, showing how technological and regulatory gaps are filled.