• Nuclear Engineering and Technology
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• 제45권3호
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• pp.385-392
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• 2013

Zirconium and zirconium alloys are widely used as nuclear reactor core materials such as fuel cladding and guide tubes because they have excellent corrosion- and radiation-resistant properties. In the reactor core, zirconium alloys are subjected to high-energy neutron fluence, causing radiation-induced dislocation and growth. To discern a possible correlation between radiation-induced dislocation and growth, characteristics of dislocation and growth in zirconium and its alloys are examined. The radiation-induced dislocation including and dislocation loops is reviewed in various temperature and fluence ranges, and their growth behavior is examined in the same way. To further a fundamental understanding, radiation-induced growth prediction models are briefly reviewed. This research will assist in the design of zirconium based components as well as the safety analysis of various reactor conditions, in both research and commercial reactors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권6호
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• pp.2979-2995
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• 2017

In recent years, there has been an increasing number of studies focused on identifying a set of spreaders to maximize the influence of spreading in complex networks. Although the k-core decomposition can effectively identify the single most influential spreader, selecting a group of nodes that has the largest k-core value as the seeds cannot increase the performance of the influence maximization because the propagation sphere of this group of nodes is overlapped. To overcome this limitation, we propose a neighborhood coreness cover and discount heuristic algorithm named "NCCDH" to identify a set of influential and decentralized seeds. Using this method, a node in the high-order shell with the largest neighborhood coreness and an uncovered status will be selected as the seed in each turn. In addition, the neighbors within the same shell layer of this seed will be covered, and the neighborhood coreness of the neighbors outside the shell layer will be discounted in the subsequent round. The experimental results show that with increases in the spreading probability, the NCCDH outperforms other algorithms in terms of the affected scale and spreading speed under the Susceptible-Infected-Recovered (SIR) and Susceptible-Infected (SI) models. Furthermore, this approach has a superior running time.

• 한국작물학회지
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• 제49권6호
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• pp.546-551
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• 2004

사전에 수행된 델파이 조사의 기초자료를 이용하여 경종작물분야 미래유망기술들을 AHP방법을 사용하여 우선순위를 설정하였다. 8명의 전문가가 응답한 설문조사에서는 평가대항목중 공공성이 0.390으로 가장 중요하게 나타났으며, 그 다음으로는 기술성이 0.388,시장성은 0.223으로 나타났다 각 평가소항목의 세부적 중요도는 기술성 측면에서는 기술실현성, 기술파급성, 기술독창성 순으로, 시장성 측면에서는 시장성장성, 투자수익성, 시장규모성 순으로,공공성 측면에서는 국가전략과의 부합성, 산업파급성. 사회영향성 순으로 중요하게 나타났다. 각 기술군 중 중요도가 가장 높은 기술은 I군의 기술 중에서는 '친환경 저투입, 생산비절감 작물 재배기술이 개발된다'의 기술이 중요도가 0.836으로 가장 높게 나타났다. II군의 기술 중에서는 '생명공학기술을 이용한 작물의 유전자 탐색, 형질전환 및 상업화기술이 개발된다'의 기술이 중요도가 0.772로 가장 높게 나타났다.

• 한국분말재료학회지
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• 제20권5호
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• pp.376-381
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• 2013

Spherical Ti-6Al-4V powders in the size range of 250 and 300 ${\mu}m$ were uniformly doped with nano-sized hydroxyapatite (HAp) powders by Spex milling process. A single pulse of 0.75-2.0 kJ/0.7 g of the Ti-6Al-4V powders doped with HAp from 300 mF capacitor was applied to produce fully porous and porous-surfaced Ti-6Al-4V implant compact by electro-discharge-sintering (EDS). The solid core was automatically formed in the center of the compact after discharge and porous layer consisted of particles connected in three dimensions by necks. The solid core increased with an increase in input energy. The compressive yield strength was in a range of 41 to 215 MPa and significantly depended on input energy. X-ray photoelectron spectroscopy and energy dispersive x-ray spectrometer were used to investigate the surface characteristics of the Ti-6Al-4V compact. Ti and O were the main constituents, with smaller amount of Ca and P. It was thus concluded that the porous-surfaced Ti-6Al-4V implant compacts doped with HAp can be efficiently produced by manipulating the milling and electro-discharge-sintering processes.

• 한국과학교육학회지
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• 제34권6호
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• pp.535-547
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• 2014

이 연구의 목적은 영국, 호주, 뉴질랜드, 캐나다 온타리오주, 싱가포르 및 우리나라의 과학교과 핵심역량에 대한 동향을 조사하여 과학교육을 통해 기를 수 있는 핵심역량이 무엇인가을 알아보는 것이었다. 또한, 현장 과학교사들이 핵심역량 기반의 과학수업에 대해 어떻게 인식하고 있는지를 탐색하고, 특히 최근 핵심역량 기반의 과학교육과정을 접한 경기도 지역 교사들이 어떻게 인식하고 있는지를 알아보는것이었다. 외국의 역량 기반 과학과 교육과정을 탐색하기 위해 각종 문헌연구를 실시하였으며, 현장 과학교사들의 인식 조사를 위해, 135명의 초 중 고등학교 교사들에게 설문을 실시하였다. 외국의 역량기반 과학과 교육과정 탐색 결과, 각 국가들의 공통적인 특징으로 '범교과 역량과의 연계', '과학 내용과 과학 활동의 결합', '의사소통 능력중시', '역량별 성취 수준 제시' 등이 나타났다. 또한, 각국에서 강조하는 과학과 핵심역량으로는, '비판적 사고력', '창의적 사고력', '문제해결력', '탐구능력', '의사소통능력', '문화적 이해력', '학문간 통합능력', '적용능력', '개인적 역량과 사회적 역량'이 있었다. 현장 과학교사들은 현재 핵심역량에 대한 인지정도 및 과학수업에서의 실행 정도는 보통으로 생각하고 있었으나, 가르쳐야 한다는 움직임과 가르칠 의사에는 긍정적인 인식을 보임으로써, 필요성에 대해서는 공감하고 있었다. 중요한 핵심역량으로는, 초 중 고 세 학교급 모두에서 '창의적 사고력', '문제 해결력', '탐구 능력'을 꼽았으며, 교육 요구도가 가장 높은 역량은 '창의적 사고력'이었다. 경기도 지역의 교사들이 다른 일반지역의 교사들보다 핵심역량에 대한 인지정도가 높은 것으로 나타났으며, 핵심역량 기반의 과학 수업이 과학적 태도와 의사소통능력 형성에 큰 도움이 된다고 보았다. 그러나 수업 운영 방법에 익숙하지 않은 점, 많은 수업 준비시간 등을 어려운 점으로 꼽았다.

• Structural Engineering and Mechanics
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• 제74권3호
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• pp.395-406
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• 2020

Many prefabricated concrete frame joints have been proposed, and most of them showed good seismic performance. However, there are still some limitations in the proposed fabricated joints. For example, for prefabricated prestressed concrete joints, prefabricated beams and prefabricated columns are assembled as a whole by the pre-stressed steel bar and steel strand in the beams, which brings some troubles to the construction, and the reinforcement in the core area of the joints is complex, and the mechanical mechanism is not clear. Based on the current research results, a new type of fabricated joint of prestressed concrete beams and confined concrete columns is proposed. To study the seismic performance of the joint, the quasi-static test is carried out. The test results show that the nodes exhibit good ductility and energy dissipation. According to the experimental fitting method and the "fixed point pointing" law, the resilience model of this kind of nodes is established, and compared with the experimental results, the two agree well, which can provides a certain reference for elasto-plastic seismic response analysis of this type of structure. Besides, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

• 한국과학교육학회지
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• 제8권1호
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• pp.73-79
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• 1988

According to the previous studies, the science education departments in the college of education should develop better curricula to teach future secondary school teachers in a more professional way As one example of such curricula developments. one important topics of modem physics was integrated to teach the future high school physics teachers In the physics education departments. The title is "The Physics of Solar Constant Measurement The surrounding core physics for this measurements were pulled together with these important points in minds(1) clear goal of learning In the teachers college physics(2) Clear explanation of physics and visualization of important technologies for the high school students(3) these teachings should encourage for the students to use the knowledge and technologies learned through the class toward the industrial applications Korea will move toward one of the heavily industrialized countries in the world where the physics education can become key player to manufacture physics based products. Therefore developments of physics curricula which relates teachers college, high school, and industry will become more and more Important.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.217-217
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• 2011

Recently, demand for thermally stable metal nanoparticles suitable for chemical reactions at high temperatures has increased to the point to require a solution to nanoparticle coalescence. Thermal stability of metal nanoparticles can be achieved by adopting core-shell models and encapsulating supported metal nanoparticles with mesoporous oxides [1,2]. However, to understand the role of metal-support interactions on catalytic activity and for surface analysis of complex structures, we developed a novel catalyst design by coating an ultra-thin layer of titania on Pt supported silica ($SiO_2/Pt@TiO_2$). This structure provides higher metal dispersion (~52% Pt/silica), high thermal stability (~600$^{\circ}C$) and maximization of the interaction between Pt and titania. The high thermal stability of $SiO_2/Pt@TiO_2$ enabled the investigation of CO oxidation studies at high temperatures, including ignition behavior, which is otherwise not possible on bare Pt nanoparticles due to sintering [3]. It was found that this hybrid catalyst exhibited a lower activation energy for CO oxidation because of the metal-support interaction. The concept of an ultra-thin active metal oxide coating on supported nanoparticles opens-up new avenues for synthesis of various hybrid nanocatalysts with combinations of different metals and oxides to investigate important model reactions at high-temperatures and in industrial reactions.

• Journal of Korean Neurosurgical Society
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• 제50권3호
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• pp.157-165
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• 2011

Objective : We have introduced a method of characterization of invading glioma cells by using molecular analysis of marginal invading tumor cells and molecular profiles of glioma tumor margin. Methods : Each of tumor core and marginal tissues was obtained in 22 glioma patients. Tumor core cells and marginal cells from each glial tumor were collected by laser capture microdissection or intraoperative microdissection under the operating microscope. Expression of MMP-2, MMP-9, CD44 and RHAMM mRNA by invading glioma cells compared with tumor core was confirmed by realtime-PCR of twenty-four glioma specimens. Clinical data also were reviewed for invasion and recurrence pattern of the gliomas radiologically and invasive rim pattern microscopically. Results : Overall results of the molecular analysis showed that relative overexpression of MMP-2, MMP-9 and RHAMM were noted at the invasive edge of human glioma specimens comparing to the tumor core but CD44 was highly expressed in the tumor core comparing to the margin. High marginal expression of MMP-2 and MMP-9 were noted in poorly ill-defined margin on the pathological finding. High marginal expression of CD44 and MMP-2 were demonstrated in the midline cross group on the radiological review, and that of RHAMM and MMP-2 were showed in the aggressive recurrence group. High expression of MMP-2 seems to be involved in the various invasion-related phenomenons. Conclusion : Up-regulation of MMP-2, MMP-9, CD44 and RHAMM was noted in invasive edge of gliomas according to the various clinical situations.

• 한국과학교육학회지
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• 제36권6호
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• pp.835-849
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• 2016

이 연구의 목적은 과학중점고등학교 학생들의 이공계 진로동기 변화의 양상을 확인하고, 학생들의 이공계 진로동기의 변화양상과 그들의 계열(인문계열, 자연계열, 과학중점계열)간의 관계를 확인하는 것이다. 이를 위해 과학중점고등학교에 다니는 고등학생 256명으로부터 7개의 구인으로 구성된 이공계 진로동기를 5학기 동안 주기적으로 측정하여 종단자료를 얻었으며, 이 자료들을 바탕으로 집단중심추세모형(Group-based trajectory modeling)분석을 수행하였다. 또한 각 구인들의 추세 집단과 계열 사이의 관계를 이해하고자 카이스퀘어 검증을 실시하였다. 분석 결과 우선 이공계 진로 교육 경험과 이공계 진로에 대한 가치 인식 구인은 학생 모두가 유사한 추세 양상을 보이는 것으로 나타났다. 부모의 사회적 지지, 이공계 진로 관련 교과에 대한 자아효능감, 이공계 진로동기 구인의 추세는 '상위집단'과 '하위집단'의 두 추세집단으로 구별됨을 확인하였다. 또한 이공계 진로 자아효능감과 이공계 진로 흥미 구인의 추세는 '다소 감소 집단', '대폭 감소 집단', '증가집단'의 세 추세집단으로 구별되어 나타났다. 각 추세집단의 추세양상을 확인한 결과, 대부분의 이공계 진로동기 구인의 수준이 고등학교 2학년 1학기 말 증가했다가 학년이 올라갈수록 감소하는 양상을 나타내었다. 또한 각 구인들의 추세 집단은 계열과 모두 유의미한 관계가 있음을 확인하였다. 반면 인문계열 학생들의 경우 이공계 진로 동기 변화 양상이 서로 다르게 나타나는 집단으로 구별되는 것으로 나타났다. 이러한 연구 결과를 바탕으로 이 연구에서는 이공계 진로교육 환경이 학생들의 다양한 진로변화 양상을 고려하여 이루어져야 함을 제언하였다.