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검색결과 1,090건 처리시간 0.031초

First-principles Study of Graphene/Hexagonal Boron Nitride Stacked Layer with Intercalated Atoms

  • Sung, Dongchul;Kim, Gunn;Hong, Suklyun
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.185.2-185.2
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    • 2014
  • We have studied the atomic and electronic structure of graphene nanoribbons (GNRs) on a hexagonal boron nitride (h-BN) sheet with intercalated atoms using first-principles calculations. The h-BN sheet is an insulator with the band gap about 6 eV and then it may a good candidate as a supporting dielectric substrate for graphene-based nanodevices. Especially, the h-BN sheet has the similar bond structure as graphene with a slightly longer lattice constant. For the computation, we use the Vienna ab initio simulation package (VASP). The generalized gradient approximation (GGA) in the form of the PBE-type parameterization is employed. The ions are described via the projector augmented wave potentials, and the cutoff energy for the plane-wave basis is set to 400 eV. To include weak van der Waals (vdW) interactions, we adopt the Grimme's DFT-D2 vdW correction based on a semi-empirical GGA-type theory. Our calculations reveal that the localized states appear at the zigzag edge of the GNR on the h-BN sheet due to the flat band of the zigzag edge at the Fermi level and the localized states rapidly decay into the bulk. The open-edged graphene with a large corrugation allows some space between graphene and h-BN sheet. Therefore, atoms or molecules can be intercalated between them. We have considered various types of atoms for intercalation. The atoms are initially placed at the edge of the GNR or inserted in between GNR and h-BN sheet to find the effect of intercalated atoms on the atomic and electronic structure of graphene. We find that the impurity atoms at the edge of GNR are more stable than in between GNR and h-BN sheet for all cases considered. The nickel atom has the lowest energy difference of ~0.2 eV, which means that it is relatively easy to intercalate the Ni atom in this structure. Finally, the magnetic properties of intercalated atoms between GNR and h-BN sheet are investigated.

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밥 크로울리 무대디자인에 나타나는 시각적 은유에 관한 연구 - 뮤지컬 '아이다' 무대디자인을 중심으로 - (A Study on Visual Metaphors that appear in the Stage Design of Bob Crowley - Focused on the stage design of 'AIDA' -)

  • 황수연;윤재은
    • 한국실내디자인학회논문집
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    • 제22권1호
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    • pp.55-63
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    • 2013
  • The main purpose of (the) performing arts is to efficiently communicate the themes and meanings which performances contain under limited time and place to the audience. Stage design should visually express play writer's scripts and director's interpretations of works, amid limitations. Although it is mostly designed metaphorically, in many cases, it is used only as a tool describing the background of performances but fails to effectively convey the true message of scenes to spectators. On the other hand, Bob Crowley has been recognized for his own design presentation skills to win 'Best Scenic Design of a Musical' of Tony Awards for six times and still exerts great influence on the musical and performing arts fields as a set designer. This study analyzes his reading of scripts and visual metaphor expressions, focusing on the musical, 'Aida' where the skills are mostly notable. To that end, we studied the concept of stage arts and theory of visual metaphoric expression to derive the features of his own technique in visual metaphor. Then, the features were applied to each scene of 'Aida' to see how they are displayed on stage. The result shows that Bob Crowley not only describes the background on stage, but also visualizes characters' personality and emotions in scenes. Such method of his expression is a proof to enhanced performance level by maximizing the atmosphere. Considering that a stage design should be based on the capacity of a designer to reinterpret the space with renewed viewpoints, visual metaphoric expression can serve as an effective tool to deliver clear messages to the audience under limited time and space, which is open to various methods of expressions.

특허(特許)와 논문(論文)으로 본 폐(廢) 디스플레이 재활용(再活用) 기술(技術) 동향(動向) (Trend on Recycling Technologies for Display Wastes analysed by the Patents and Literature Review)

  • 이성규;이찬기;홍현선;조영주;조봉규
    • 자원리싸이클링
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    • 제21권3호
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    • pp.65-73
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    • 2012
  • 디스플레이는 액정 디스플레이(LCD), 음극선관(CRT), 플라즈마 디스플레이 패널(PDP), 발광 다이오드(LED), 유기 발광 다이오드(OLED) 등 여러 종류가 있다. 경제적, 효율적 관점에서 폐 디스플레이의 재활용 기술은 폭넓게 연구되어 왔다. 본 연구에서는 폐 디스플레이의 재활용 기술에 대한 특허와 논문을 분석하였다. 분석범위는 1980년~2011년까지의 미국, 유럽연합(EU), 일본, 한국의 등록/공개된 특허와 SCI 논문으로 제한하였다. 특허와 논문은 키워드를 사용하여 수집하였고, 기술의 정의에 따라 필터링하였다. 특허와 논문의 동향은 연도, 국가, 기업, 기술에 따라 분석하여 나타내었다.

분산 모바일 코어기반 5G 네트워크에서의 Service Function Chaining 적용구조 (Service Function Chaining Architecture for Distributed 5G Mobile Core Networks)

  • 선경재;김영한
    • 한국통신학회논문지
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    • 제41권12호
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    • pp.1914-1924
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    • 2016
  • 본 논문은 5G 모바일 네트워크에서 가상화 기반의 이동통신 코어망인 Virtualized Evolved Packet Core(vEPC) 환경을 고려하여, 가입자의 종류 및 트래픽 식별에 따라 동적으로 End-to-end 서비스를 제공하기 위한 기술인 Service Function Chaining(SFC)을 적용하기 위한 구조 및 메시지 절차를 제안한다. SFC 기술은 네트워크 기능들을 물리적인 연결에 상관없이 선택적으로 제공하기 위한 기술로써, 가상화 기반 네트워크 기술인 Network Function Virtualization(NFV)기반의 네트워크 환경에서 서비스 제공을 위한 주요 기술로 예상된다. 특히, 5G 모바일 코어 네트워크는 분산 코어 형태로 구축될 것으로 예상되기 때문에 본 논문에서는 이를 고려하여 계층적 SFC(hSFC: Hierarchical SFC) 구조를 적용하였다. 본 논문에서는 제안하는 구조 및 구조 내에서의 SFC를 이용한 경로 설정 메시지 절차를 정의하고 오픈소스 기반의 테스트베드 설계를 통해 이를 구현하고자 하였다.

토픽 모델과 소셜 네트워크를 이용한 개발자 추천방법 (A Developer Recommendation Technique Based on Topic Model and Social Network)

  • 양근석;장도;이병정
    • 한국정보과학회논문지:소프트웨어및응용
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    • 제41권8호
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    • pp.557-568
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    • 2014
  • 최근 소프트웨어 규모가 더욱 커지고 복잡해지고 있다. 하루에도 수많은 버그 리포트들이 버그저장소에 전송 되어 개발자들의 업무가 늘어나고 있다. 이러한 버그 리포트들을 적절한 개발자에게 전달하여 빠르고 정확하게 소프트웨어의 결함이 수정되어야 하는데, 많은 버그 리포트들이 적절하지 않는 개발자에게 배정되어 다른 개발자에게 다시 재배정 되는 경우가 빈번하게 일어나고 있다. 이것은 배정자가 전송받은 버그 리포트들을 정확히 이해하지 못했거나, 또는 모든 개발자들의 능력을 바르게 파악하지 못해 발생한다. 이것은 소프트웨어 유지보수에 개발자의 시간과 노력을 많이 필요하게 한다. 이러한 문제를 해결하기 위해 본 연구에서는 버그 리포트와 관련된 토픽을 찾아내고, 토픽 내 개발자들의 소셜 네트워크 관계를 분석해서 적절한 개발자를 추천하는 기법을 제안한다. 그리고 공개 소스 프로젝트를 이용한 개발자 추천에 대한 성능비교 실험을 통하여 본 연구에서 제안한 방법이 효과적이라는 것을 보인다.

장경각 기상 자료 수집 체계 (Meteorological Data Acquisition System for the Changkyeonggak)

  • 유병용;전채익;이강수;신교철;변종홍;김창홍
    • 보존과학회지
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    • 제5권1호
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    • pp.69-86
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    • 1996
  • More than eighty thousands of wooden printing blocks of the Tripitaka Koreans are accommodated in the Changkyeonggak which consists of two open structured wooden buildings, Peoppojeon and Sudarajang. These blocks are virtually in pristine state even after three quarters of a millennium. The excellent preservation could be attributed to the careful preparation and meticulous finish of the blocks. But the meteorological environment or microclimate should be one of the key factors for the preservation. To keep the blocks intact as it is or at least do not accelerate the deterioration, we should study the blocks and its microclimatic environment supplied by the Changgyeonggak and the topology of the site. As a Part of this effort we designed a computerized meteorological data acquisition system, which can handle up to 4,096 sensors. A partial but operative installation of 16 temperature/humidity sensors was set up in the Peoppojeon. We hope to have a chance to install a full fledged system in the near future for the compilation of the fuller environmental data base.

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Use of Near-Infrared Spectroscopy for Estimating Lignan Glucosides Contents in Intact Sesame Seeds

  • Kim, Kwan-Su;Park, Si-Hyung;Shim, Kang-Bo;Ryu, Su-Noh
    • Journal of Crop Science and Biotechnology
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    • 제10권3호
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    • pp.185-192
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    • 2007
  • Near-infrared spectroscopy(NIRS) was used to develop a rapid and efficient method to determine lignan glucosides in intact seeds of sesame(Sesamum indicum L.) germplasm accessions in Korea. A total of 93 samples(about 2 g of intact seeds) were scanned in the reflectance mode of a scanning monochromator, and the reference values for lignan glucosides contents were measured by high performance liquid chromatography. Calibration equations for sesaminol triglucoside, sesaminol($1{\rightarrow}2$) diglucoside, sesamolinol diglucoside, sesaminol($1{\rightarrow}6$) diglucoside, and total amount of lignan glucosides were developed using modified partial least square regression with internal cross validation(n=63), which exhibited lower SECV(standard errors of cross-validation), higher $R^2$(coefficient of determination in calibration), and higher 1-VR(ratio of unexplained variance divided by variance) values. Prediction of an external validation set(n=30) showed a significant correlation between reference values and NIRS estimated values based on the SEP(standard error of prediction), $r^2$(coefficient of determination in prediction), and the ratio of standard deviation(SD) of reference data to SEP, as factors used to evaluate the accuracy of equations. The models for each glucoside content had relatively higher values of SD/SEP(C) and $r^2$(more than 2.0 and 0.80, respectively), thereby characterizing those equations as having good quantitative information, while those of sesaminol($1{\rightarrow}2$) diglucoside showing a minor quantity had the lowest SD/SEP(C) and $r^2$ values(1.7 and 0.74, respectively), indicating a poor correlation between reference values and NIRS estimated values. The results indicated that NIRS could be used to rapidly determine lignan glucosides content in sesame seeds in the breeding programs for high quality sesame varieties.

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Isolation and Partial Characterization of Phytotoxic Mycotoxins Produced by Sclerotinia sp., a Potential Bioherbicide for the Control of White Clover(Trifoliorum repens)

  • Hong, Yeon-Kyu;Lee, Bong-Choon;Jung, Won-Kwon;Bae, Soon-Do;Park, Sung-Tae;Uhm, Jae-Youl
    • The Plant Pathology Journal
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    • 제20권1호
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    • pp.52-57
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    • 2004
  • Sclerotinia sp. (isolate BWC98-105) causes stem blight and root rot in Leghum sp., and is presently being evaluated as a potential mycoherbicide for the control of Trifoliorium repens. Bioassays have shown that Sclerotinia sp. produces phytotoxic substance which is biologically active against T. repens. Two biologically active compounds, designated as compoundsI and II, were produced in vitro from the culture filtrate of BWC98-105 isolate Sclerotium sp. Compounds I and II were purified by means of liquid-liquid extraction and $C_{18}$ open column chromatography (300 ${\times}$ 30 mm, i.d). To determine the purity, the purified compounds were analyzed by RP-HPLC. The analytical RP-HPLC column was a TOSOH ODS-120T (150 ${\times}$ 4.6 mm i.d, Japan), of which the flow rate was set at 0.7 mL/min using the linear gradient solvent system initiated with 15 % methanol to 85 % methanol for 50 min with monitoring at 254 nm. Under these RP-HPLC conditions, compounds I and II eluted at 3.49 and 4.13 min, respectively. Compound II was found to be most potent and host specific. However, compound I had a unique antibiotic activity against phytopathogenic bacteria like bacterial leaf blight (Xanthomonas oryzae) on rice, where it played a less important role in producing toxicity on T. repens. No toxin activity was detected in the water fraction after partitioning with several organic solvents. However, toxin activity was detected in the ethyl acetate and butanol fractions. In the leaf bioassay using compound II, the disease first appeared within 4-5 h as water soaked rot, which subsequently developed into well-defined blight affecting the whole plant.

작업환경측정 결과를 활용한 벤젠 노출 매트릭스에 대한 연구 (Benzene Exposure Matrices Using Employees's Exposure Assessment Data)

  • 백경희;박동욱;하권철
    • 한국산업보건학회지
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    • 제25권2호
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    • pp.146-155
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    • 2015
  • Objectives: The aims of this study were to set up benzene exposure matrices according to industry and process and to assess the risk of those occupational exposure to benzene. Methods: The benzene exposure matrices were assembled depending on industry and process, based on an exposure database provided by KOSHA(the Korean Occupational Safety and Health Agency), which was gathered from a workplace hazards evaluation program in Korea. These exposure matrices were assessed by Hallmark Risk Assessment tool. Results: The benzene was treated 412 industries sector(36%), 2,747 business places, and 471 industrial processes according to database. The arithmetic mean of past decade 8 hours time-weighted average of airborne benzene concentrations in the workplace was 0.10722 ppm. 1.07% of the total sample were greater than OEL, and 59.8% were showed less than the limit of detection. The highest risk values(Danger Value) were seen 36 industries including manufacture of general paints and similar product and 12 processes, such as other painting of manufacture of metal fabricated members. Exposure matrices based on employee exposure data base may provide exposure histories and can be used in epidemiological studies. Conclusions: It was found that more attentions should be paid to 36 among 412 industries and 12 of 471 processes, with a higher risk value.

영농환경 개선을 위한 인삼재배사 표준화 디자인 (A Study For the Standardization Design of Ginseng Cultivating Facility for the Improvement of Farming Environment)

  • 신택균
    • 디자인학연구
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    • 제16권1호
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    • pp.93-102
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    • 2003
  • 이 논문은 영농환경 개선을 위한 인삼재배사(일명 해가림 시설물) 디자인 표준화를 위한 연구이다. 연구배경의 핵심은 현 WTO 농산물 개방 체제하에서 한국의 세계적 농특산물인 고려인삼의 생산과 품질 가치를 더욱 확고히 하고 인삼 종주국으로서 위상에 걸맞는 현대식 인삼재배 시설을 최초로 도입하기 위한 기초연구를 제안함에 있다. 디자인 개념으로서는, 현재 목재 볏짚 비닐 등 일회성 또는 비표준화된 재료를 사용하므로서 매년 반복 재설치 작업 및 환경오염이 되고 있는 우리나라 인삼경작사의 노동 및 자원 낭비적 요소를 개선하고자 하였다. 구체적 개선 요소로서는 첫째, 양산체제에 의한 형태 및 구조의 표준화. 둘째, 반영구적 재료 표준화를 위한 수지 등 신소재 도입, 위 두 가지 내용을 한국적 이미지를 바탕으로 형상화 하고자 하였다. 디자인 결과로서, 인삼재배사의 기준 단위모델을 디자인하여 재배면적의 크기 형상에 따라 가변적으로 연결 조립하여 사용할 수 있도록 배려하였다.

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