RISS 학술연구정보서비스

검색
다국어 입력

http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.

변환된 중국어를 복사하여 사용하시면 됩니다.

예시)
  • 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
  • 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
닫기
    인기검색어 순위 펼치기

    RISS 인기검색어

      검색결과 좁혀 보기

      • 좁혀본 항목

      • 좁혀본 항목 보기순서

        • 원문유무
        • 음성지원유무
          • 원문제공처
          • 등재정보
            • 학술지명
            • 주제분류
            • 발행연도
            • 작성언어
            • 저자

          오늘 본 자료

          • 오늘 본 자료가 없습니다.
          더보기
          • 무료
          • 기관 내 무료
          • 유료
          • 과학기술위성 2호 탑재 진공자외선 태양카메라 개발

            장민환 경희대학교 자연과학종합연구원 2003 자연과학논문집 Vol.9 No.1

            국내 최초로 국산 로켓에 의해 2005년 12월 발사 예정인 과학기술위성 2호(Science and Technology Satellite-2 STSAT-2)의 주탑재체로 진공자외선 태양카메라(Lyman-α Imaging Solar Telescope LIST)의 개발이 진행 중이다. 개발은 2002년 10월부터 국내 여러 대학의 연구진이 참여하는 경희대학교 우주탑재체 연구센터에서 주관하고 있으며 현재 Preliminary Design Review(PDR)를 준비하는 단계에 있다. 본 논문에서는 LIST의 개요와 현재까지의 개발 상황을 소개한다. The Lyman-a Imaging Solar Telescope(L1ST) is a project funded by the Korean government to fly on the second Korean Science and Technology Research Satellite (STSat-2) scheduled to launch in December 2005. The LIST is developed at the Space Payload Research Center (SPARC), a consortium of Korean universities and institutions formed to develop scientific research projects in space. The goal of the LIST is to design, build, and operate an instrument which will image the full disk of the Sun from Earth orbit at the wavelength of the Hydrogen Lyman-a emission line at 121.6 ㎚. The LIST, currently on the stage of preparing for a Preliminary Design Review(PDR), is consists of a Cassegrain type telescope, 3 filters to isolate the 1216 nm wavelength. a CCD camera, electronic boards.

          • Electronic voltage tuning of all-fiber Mach-Zehnder interferometer

            Feng,,Dejun,Choi,,Dong,Hoon,Choi,Suk-Ho 경희대학교 자연과학종합연구원 2002 자연과학논문집 Vol.8 No.-

            The electric voltage tuning performance of an all-fiber Mach-Zehnder interferometer which has unequal arm-length is studied in this paper. This interferometer consists of two 3dB fiber directional couplers, with one arm is affixed to a Piezoelectric Translators (PZT). When the voltage applied on PZT changes, the output interferometric pattern will shift accordingly. The transmission period of the interferometer is 2.24nm. When the direct current electric voltage changes from 28.7volt to 28.7volt, the pattern will shift for nearly one of its own period. The tuning sensitivity is about 0.038nm/volt, and the linearity is 0.9991. Also, the relationship between the physical path length difference of the two arms and the interval of adjacent interferometric peaks is discussed. This component has potential important applications in electric sensing measurement and optical fiber communication field.

          • π-수소결합에 대한 DFT 계산

            박채용,한혜리,김용호 경희대학교 자연과학종합연구원 2003 자연과학논문집 Vol.9 No.2

            π-수소결합을 하고 있는 복합체들(acetylene-HCl, acetylene-HCN, acetylene-acetylene, propyne-HF, cyclopropane-HCl, benzene-HCl)의 구조와 결합에너지를 DFT 방법으로 계산하여 실험결과와 비교하였다. DFT calculation for complexes of n-hydrogen bonds(acety1ene-HCl, acetylene-HCN, acetylene-acetylene, propyne-HF, cyclopropane-HC1, benzene-HC1) has been performed and the results were compared with experiments.

          • 소나무-굴참나무 천연 혼효임분 구조에 관한 연구

            이종락,정동준 경희대학교 자연과학종합연구원 1998 자연과학논문집 Vol.4 No.-

            본 연구는 한국 중부지방의 소나무-참나무 천연 혼효임분을 대상으로 입지조건에 따른 생장 및 임분구조를 파악하여 합리적인 경영방안을 제시하기 위하여 수행되었다. 사면별(북, 서 남) 위치종속조사에 의하여 수종별 생장량, 흉고직경변이지수, 혼효지수를 추정하여 혼효 임분구조를 파악하였다. 소나무의 생장은 북사면, 서사면, 남사면의 순서로 점차 감소하였으나, 굴참나무는 이와 반대의 경향을 나타냈다. 모든 방위의 혼효림에서 전체 및 각각 수종별, 개체목의 첫 번째 주변목만을 고려한 흉고직경변이지수 평균값은 23∼27%로 적은 직경변이 (little differentiation)를 나타내고 있었으며 , 이것은 소경급의 입목들이 큰 직경급을 갖고 있는 주변목의 직경에 75%의 크기를 갖고 있는 것으로서 , 즉 각 개체목들이 대부분 비슷한 직경급을 갖고 있었다. 특히 남향의 혼효림에서 굴참나무의 주변목은 모두 비슷한 직경급으로서 흉고직경변이지수값이 89∼96%으로 나타났다. 수종을 고려하지 않은 각 입목별 평균 혼효지수는 67∼77%로 1∼3개의 주변목이 중심목과 다른 수종으로 나타났으며 , 소나무를 중심목으로 보았을 때 모든 방위에서 주변목이 굴참나무로 구성된 43∼64%의 높은 값을 나타냈으며 ,굴참나무는 단지 33∼40% 만을 나타났다. 따라서 이 혼효림에서는 두 수종간에 강한 경쟁을 내포하고 있음을 판단할 수 있다. This study is to rationalize the forest management practice based upon the growth and structure of pine-oak mixed natural forest standards in central part of South Korea. The mingling index and DBH-differentiation index estimated by a distance-dependency survey conducted for each slope (north, west and south) is compared with the growth and 3 dimensional stock map. Pine trees revealed a slower growth as the slopes changed from north to west and from west to south, whereas oak trees showed the opposite results. The dbh-differentiation index for first neighbor tree (DD1) showed 23∼27% by stand mean values. These results were little differentiation, i.e., nearly 75% of neighbor trees belong to the same dbh-class of center-tree. Specially the DD1 values of oak showed 89∼96% by nearly same dbh-class with neighbor trees. Based upon the mean mingling index value (MI) for all trees result that the MI3 values showed 67∼77% as 1∼3 neighbor trees by other species from center-tree. The MI3 value of pine showed highly 43∼46% in all exposition as neighbor trees of oak, but the MI3 value of oak showed only 33∼40%. Based upon the study result that the competition pressure between pine and oak is intensified within a mixed forest stand.

          • 강설 중 분진 및 금속원소의 침착

            김성천,김동술 경희대학교 자연과학종합연구원 1995 자연과학논문집 Vol.1 No.-

            The 21 snow samples were collected from 9 different sites in Korea. Then we analysed chemical compositions, deposition fluxes and velocities of dustfall, and metallic elements in snow in Korea. The results were as follows; The concentration difference of upper and lower layer of snow showed wide range. As for dry deposition, K was highest in Suwon, Ca and Zn were highest in Kwangju. As for wet deposition, Zn, and Ca were highest in Sunchang and Namwon. The range of pH in snow was 4.95-5.85 in the upper layer and 5.00-5.58 in the lower layer. The correlation coefficient of pH and conductivity was r^(2)=0.55 in the upper layer and r^(2)=0.86 in the lower layer. The correlation coefficient of total dissolved solid and conductivity was r^(2)=0.85 in the upper layer and r^(2)=0.86 in the lower layer. Deposited dustfall in snow was 470.0 ton/km^(2)/yr in Seoul, 387.7 ton/km^(2)/yr in Suwon, and 115.4 ton/km^(2)/yr in Kwangju. Zn flux was highest in Ansung; on the other hand, Cd and Cr fluxes were highest in Seoul. Dry deposition velocity of upper layer in January were Zn 0.13 ㎝/s, Pb 0.01 ㎝/s, Ca 0.21 ㎝/s, Fe 0. 02 ㎝/s, Mn 2.13 ㎝/s, Cu 0.19 ㎝/s, and in Feburary Ca was 0.055 ㎝/s.

          • 18年生 잣나무 次代檢定林의 樹高·直徑生長의 遺傳力 및 改良效果

            전상근,정동준,장용석 경희대학교 자연과학종합연구원 1998 자연과학논문집 Vol.4 No.-

            The objectives of this study were to analyzed to variation and to estimate heritabilities and genetic gains for height and diameter growth of 18-year-old open-pollinated progenies of Korean White Pine in three different sites. The results were summarized as follows; 1. Family, site, block, and interactions among these factors were significant source of variance for tree height and diameter growth. The effects of family × site interaction were relatively large as compared with other source of variance. 2. Average values were 6.5m in height and 10.5cm in diameter at Kapyung site, 6.2 m and 9.8cm at Kwangju site, 4.9m and 6.5cm at Youngdong site, and 6.0 m and 9.1cm overall these three sites, respectively. 3. Family of No. 20 showed excellent growth of 6.8m in mean height, 10.5cm in mean diameter overall sites. 4. Individual-tree and family heritabilities were estimated 0.12-0.22 and 0.65-0.80 for height growth, and 0.05-0.15 and 0.59-0.78 for diameter growth, respectively. For overall the sites, estimates of individual-tree heritabdity was 0.38 for height and 0.25 for diameter, and those of family were 0.89 for height and 0.82 for diameter. 5. Heritability estimates varied with testing site, and that for height were higher than for diameter. 6. Given equal intensity of selection (l0%), combined selection showed the most efficient genetic gains for height and diameter.

          • On Semiprime Rings Whose Simple Singular Right Modules Are GP-injective

            Kim,,J.Y.,Kim,,N.K.,Nam,,S.B. 경희대학교 자연과학종합연구원 1996 자연과학논문집 Vol.2 No.-

            We investigate in this paper von Neumann regularity of rings whose simple singular right R-modules are GP-injective. It is proved that if R is a reduced ring whose simple singular right R-modules are GP-injective, then R is a weakly regular ring. And it is also proved that a ring R is strongly regular iff R is a semiprime right quasi-duo ring whose simple singular right R-modules are GP-injective.

          • Some Properties of Rings Whose Simple Singular Modules Are GP-injective

            Hong,,Chan,Yong,Kim,,Nam,Kyun,Kwak,,Tai,Keun 경희대학교 자연과학종합연구원 1997 자연과학논문집 Vol.3 No.-

            We investigate in this paper the connection between the p-injectivity (or GP-injectivity) of simple singular left modules of rings and the maximality of prime ideals.

          • OMACON형 MHD시스템에서의 기액이상유동에 관한 수치해석

            송기백,김창녕 경희대학교 자연과학종합연구원 1997 자연과학논문집 Vol.3 No.-

            The purpose of this study is to numerically predict the performance of an OMACON type LMMHD system which converts heat into electricity. In this system working fluid (gas) is injected through the mixer located at the bottom of the riser, and is mixed with hot liquid metal. Therefore in riser two-phase flow is developed under the influence of the gravity. As bubbles rise upward, the density of the gas becomes smaller and the velocity of the gas becomes faster. At the gravity separator located at the top of the system, the gas is separated from the liquid metal. Therefore only the liquid metal (single phase) can flow down through the down-commer. In this study, instead of getting the full characteristics of electricity generation, emphasis was put on investigating the magnitude of the mechanical loss occurring at the nozzle in the loop in association with the fact that if the MHD generator were installed in the liquid metal loop, electricity would be obtained. For the numerical calculation, finite volume method has been used with the power-law scheme for the treatment of convective and diffusive effects. For the pressure calculation, SIMPLE algorithm has been employed. And the discretized equations are solved by line-by-line method. In the OMACON system, the characteristic of two-phase flow play a major role in determining the conversion efficiency and other performance parameters. More specifically, two-phase flow friction and gas-to-liquid velocity ratio are most critical for the optimizied design. In order to achieve maximum cycle performance, void fraction in the riser should be well adjusted.

          • Solvent Effect on the Double Proton Transfer in the Formic Acid Dimer and the Formamidine Dimer Complexes : Theoretical Study 이온적 연구

            Kim,,Yongho,Lim,,Jae-Hyun 경희대학교 자연과학종합연구원 1995 자연과학논문집 Vol.1 No.-

            Proton transfer is very important in many oxidation and reduction reactions, and it is one of the simplest reaction in chemistry. Multiple proton transfer is also very important in many chemical and biological system, but it has not been very well understood yet. The double proton transfers in the formic acid dimer and the formamidine dimer complexes are a prototype of multiple proton transfer. The potential energy surfaces (PES) for the double proton transfer in the formic acid dimer and the formamidine dimer complexes has been studied using ab initio quantum mechanical methods. The solvent effect on the PES is also studied by the Onsager dielectric continuum model. In the gas phase, the transition state for the double proton transfer in the formic acid dimer complex has a D_(2h) symmetry, but in water the transition state is changed to a C_(2v) structure, when the Hartree-Fock (HF) level of theory is used. When the density functional theory is used to consider correlation effect, the transition state does not vary with the solvent effect. However the barrier height depends very much with the correlation effect. For the formamidine dimer complex, the transition state shows a C_(2v) symmetry in the gas phase, and it moves to C_(8) symmetry in water at the HF level of theory. The C_(2v) structure becomes an intermediate in water solvent. With the density functional theory, the transition state has a D_(2h) symmetry, and it does not vary with the solvent effect. These suggest the correlation effect is very important to the PES for the double proton transfer.

          맨 위로 스크롤 이동