• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.173-177
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• 2010

The electronic structure of charge-density-wave (CDW) system $CeTe_2$ has been investigated by using angle-resolved photoemission spectroscopy (ARPES). The clearly dispersive band structures are observed in the measured ARPES spectra, indicating the good quality of the single-crystalline sample employed in this study. The four-fold symmetric patterns are observed in the constant energy (CE) mappings, indicating the $2{\times}2$ lattice deformation in the Te(1) sheets. The observed CE images are similar to those of $LaTe_2$, suggesting that Ce 4f states have the minor contribution to the CDW formation in $CeTe_2$. This study reveals that the carriers near the Fermi level should have mainly the Te(1) 5p and Ce 5d character, that the Te(1) 5p bands contribute to the CDW formation, and that the Ce 5d bands cross the Fermi level even in the CDW state.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.127-132
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• 2001

By the use of a similar numerical method as the forming limit strain by coating method of coated sheet metals is investigated, in which the FEM is applied and J2G(J2-Gotohs Corner Theory) is utilized as the plasticity constitutive equa-tion. Circular bonded sheet metals with dissimilar sheets on both surface planes are stretched in a plane -strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such com-posite sheets are clearly illustrated. It is concluded that, it the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighed according thickness.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.296-296
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• 2011

동시 증발법(co-evaporation)에 의해 성장된 $CuIn_xGa_{1-x}Se_2$ (CIGS) 박막의 광학적 특성을 photoreflectance (PR) 분광법으로 연구하였다. 조성비 x는 0~1까지 변화시켰다. 시료의 두께는 약 2.2 ${\mu}m$였다. PR 측정은 변조빔 세기, 변조빔 주파수 및 온도의 함수로 조사하였다. PR 스펙트럼으로부터 조성비 x가 증가함에따라 시료의 띠간격 에너지가 증가하는 것을 관측하였다. 상온 PR 스펙트럼으로부터 시료내에 형성된 내부 전기장을 구하였다. 그리고 변조빔 세기의 증가에 따른 PR 신호의 세기는 점차 증가하는 반면에, 변조 주파수를 증가시킴에 따라 신호의 세기가 점차 감소함을 보였다. PR 신호의 온도 의존성 실험으로부터 띠간격 에너지의 변화 및 Varshni 계수 등을 구하여 CIGS 시료의 특성을 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.391-392
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• 2013

반도체 집적회로의 고집적화 및 고성능화를 위한 기본 소자(MOSFET)의 미세화 및 단위공정의 물리적 한계를 극복하기 위해 기존의 Top-down 방식에서 buttom-up 방식의 공정에 대한 연구가 진행되고 있다. 그 중 nanoparticles를 이용한 나노소자 제작 연구가 이루어지고 있다. 하지만 이러한 nanoparticles를 이용한 나노소자의 제작에 있어서 원하는 위치에 nanoparticles를 배열하고 정렬하는데 어려움을 겪고 있다. 이 문제를 해결하기 위해서 자기조립 특성을 가지고 있는 DNA분자와 기능화를 통하여 표면에 positive charge를 띄고있는 Gold nanoparticles를 상호결합 시키는 실험을 하였다. Au-DNA nanowire는 backbone에 있는 phosphate부분에서 negative charge를 띠고 있는 DNA와 positive charge를 띠고 있는 Gold nanoparticles가 결합하는 원리로 형성된다. 그렇지만 Gold particles를 표면이 아닌 DNA에만 붙이는 것은 아직 해결해야 할 부분으로 남아있다. 본 연구에서는 이 문제를 해결하기 위하여 pH 조절을 통하여 기능화된 Gold particles의 charge의 변화를 주고 이를 Zeta potential 측정기로 측정한 후에 이 particles와 DNA를 결합시켜서 FE-SEM과 AFM 으로 확인하는 실험을 하였다.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.1
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• pp.133-148
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• 2014

In order to investigate community formation ability, herbaceous perennials such as Miscanthus sacchariflorus Bentham, Miscanthus sinensis var. purpurascens Rendle, Imperata cylindrica Linne, Pennisetum alopecuroides (L.) Spreng. and Arundinella hirta Tanaka were planted in April 2009 at the levee slope of Gwangju Stream in South Korea. Miscanthus sacchariflorus Bentham, Miscanthus sinensis var. purpurascens Rendle, Imperata cylindrica Linne and Pennisetum alopecuroides (L.) Spreng. which grew in pots for two years and divided rhizomes of Arundinella hirta Tanaka gathered from fields were employed. Weeds growing on the experiment sites were removed twice a year until 2011 when the plant species were formed into community. Weeds were not eradicated during 2012 and 2013 to observe community sustainability of the species. T-tests on stem numbers and heights in May, July and September were conducted between 2011 and 2012, and between 2012 and 2013. Stem numbers of the five species in 2012 were significantly reduced(p<0.001) compared with those in 2011, which were attributed to weed growth in 2012. Heights of Miscanthus sinensis var. purpurascens Rendle, Imperata cylindrica Linne, Pennisetum alopecuroides (L.) Spreng. and Arundinella hirta Tanaka in 2012 were significantly lower than those in 2011(p<0.001), which resulted from weed invasion. Heights of Miscanthus sacchariflorus Bentham in May and July 2012 were significantly decreased compared with those in 2011(p<0.001), however, heights of Miscanthus sacchariflorus Bentham in September 2012 were almost the same as those in 2011(p>0.05). Miscanthus sacchariflorus Bentham was able to compete against weeds in September 2012. Stem numbers and heights of Miscanthus sacchariflorus Bentham, Miscanthus sinensis var. purpurascens Rendle, Imperata cylindrica Linne and Pennisetum alopecuroides (L.) Spreng. in 2013 were similar to those in 2012(p>0.05). However, stem numbers and heights of Arundinella hirta Tanaka in 2013 were significantly decreased compared with those in 2012(p<0.001). After community formation, Miscanthus sacchariflorus Bentham, Miscanthus sinensis var. purpurascens Rendle, Imperata cylindrica Linne and Pennisetum alopecuroides (L.) Spreng. were able to maintain its community without weed removal. However, Arundinella hirta Tanaka was unable to establish its community due to the weed growth. Miscanthus sacchariflorus Bentham, Miscanthus sinensis var. purpurascens Rendle, Imperata cylindrica Linne are more suitable to stream levee slope environment in terms of community formation and maintenance, stream landscape enhancement and slope erosion control.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.96-104
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• 2008

In this study, the observation of test pieces with an optical microscope was carried out after fabricating 4 groups of standard lacquer, in order to inquire into the ancient lacquering techniques. Group I had transparent reddish brown color, and the part of layer was indefinite, and the layer polished was easily distinguished. Group II had mostly transparent yellowish brown color, and it was possibility distinguished the layers when they were varnished with mixed lacquer after prime coating, and when they were varnished with lacquer as the prime coating. Group III set up membrane in the hardening process of the lacquer, and the lacquer and the unsaturated fatty acid of internal part was dried, so the top layer and the lacquer layer were separated and observed. Group IV: When the lacquer coat film of Group IV test pieces were observed in polarized light, the ferrous components were seen as the black and red color were mixed, and the silica crystals of silty soil were distinguished by reflection of lights. And the colors were distinguished as the lacquer layer of ruddle had red color, and the mixed lacquer of reddish lacquer and ruddle had the deep red color at the top and the bottom, but the middle part had the bright red color.

• Development and Reproduction
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• v.9 no.1
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• pp.23-31
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• 2005

Vitellogenesis during oogenesis, reproductive cycle and first sexual maturity of the female Neptunea (Barbitonia) arthritica cumingii was investigated by light and electron microscope observations. In the early vitellogenic oocyte, the Golgi complex and mitochondria were involved in the formation of lipid droplets and yolk granules. In late vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of proteid yolk granules in the cytoplasm. A mature yolk granule was composed of three components: main body(central core), superficial layer, and the limiting membrane. The spawning season was between May and August and the main spawning occurred between June and July when the seawater temperature rose to approximately $18{\sim}23^{\circ}C$. The female reproductive cycle can be classified into five successive stages: early active stage(September to October), late active stage(November to February), ripe stage(February to June), partially spawned stage(May to August), and recovery stage(June to August). The rate of individuals reaching the first sexual maturity was 53.1% in females of 51.0 to 60.9mm in shell height, and 100% in those over 61.0mm.

• The Korean Journal of Mycology
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• v.32 no.1
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• pp.45-49
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• 2004

Verticillium tenerum was detected from the samples of potato (Solanum tuberosum L.) and pumpkin (Cucurbita maxima Duch.) in Korea. The samples on which this species was detected were potato tubers collected from Pyungchang and Gimjae, and fruits and seeds of pumpkin from Yeonchon in 2003. The conidiophores of the fungus produced mainly three to five phialides in verticil. The phialides were narrow, flask-shaped, only very slightly swollen at the base, and taper subulately to a narrow neck. They were hyaline, $10{\sim}26{\times}2{\sim}5\;{\mu}m$. The conidia were formed in slimy heads, and were oval to ellipsoidal, pale reddish-brown, $2.5{\sim}7.5{\times}2{\sim}4\;{\mu}m$. The colony on the substrata was unique, showing brick-red color. This is the first report on the distribution of Verticillium tenerum in Korea.

• The Korean Journal of Ecology
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• v.22 no.3
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• pp.163-167
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• 1999

In order to investigate territorial behaviour, Pungitius sinensis kaibarae were collected from Sacheon-river, Kangwon-do, Korea. They are reared in aquarium with designed experimental region from March to May 1996. In this study, territorial behaviour was divided into 1) pre-territorial movements of a shoal under varying water-weeds position 2) individual ranking patterns in connection with total length of fish 3) the change in size of territorial maps during the parental stage. The movements of a shoal tend to prefer regions with water-weeds and the lower half of the aquarium. Competition for territory was fierce, and fish that are longer in total length dominate smaller one in occupying territory. Both males and females developed territorial behaviour as they grew. However, male's territory was enlarged according to the hatching and dispersion of fry. At this time, aggressive tendencies reached their peak.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.1
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• pp.57-61
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• 2002

Ternary $SrO-B_2O_3-SiO_2$ glasses were fabricated as a function of R(${\equiv}SrO\;mole%/B_2O_3\;mole%$) and K(${\equiv}SiO_2\;mole%/B_2O_3\;mole%$). The structures of these glasses were investigated through Infrared transmittance, vicker's hardness, and refractive index. The results indicated : First, in the infrared transmittance spectra, when R increased, the intensities of the absorption bands around $1200{\sim}1600cm^{-1}$ resulting from the B-O stretching vibration bond in the symmetrical trigonal $BO_3$ units decreased, and these of the absorption bands around $800{\sim}1200cm^{-1}$ caused by the B-O stretching vibration bond of the tetrahedral $BO_4$ units varied. Also, the intensities of the absorption bands for the B-O stretching vibration bond in trigonal $BO_3$ units increased and these of the bands for B-O stretching vibration bond in tetrahedral $BO_4$ units decreased as K increased. Second, the increase and the decrease of vicker's hardness values for these glasses depended on the fraction of $BO_4$ units and it of $BO_3$ units, respectively. The refractive index of these glasses mostly depended on the SrO contents and only slightly depended on the fraction of $BO_4$ and $BO_3{^-}$ units.