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        검색결과 376

        201.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        낙동강 물금 지역에서 채집된 동물플랑크톤 중 윤충류인 Keratella 속을 대상으로 10년 전후(1995, 1997, 2005 그리고 2007)의 종조성 변화를 분석하고, 피갑형태에 다양한 변화를 보이는 K. cochlearis의 피갑 크기, 후돌기의 발현 여부 및 길이 그리고 후두돌기 길이의 연도와 계절에 따른 변화를 측정하였다. Keratella 속의 밀도는 봄에 높고 겨울에 낮은 뚜렷한 계절성을 보였다. 군집 내에서 K. cochlearis가 우점종이었으며 상대풍부도는 1995년과 1997년보다 2005년과 2007년에서 높게 나타났다. 연도별 K. cochlearis의 피갑 폭은 유사하였으나, 피갑 길이의 경우 여름에 감소하고 겨울에 증가하는 특징을 보였다. 모든 연도에서 후돌기를 발현하는 개체의 비율이 낮았고 특히 여름과 가을에 출현빈도가 낮았다. 후돌기의 평균 길이는 여름에 짧고 겨울에 길었으며 후두돌기 평균 길이는 겨울에 가장 짧은 것으로 나타났다.
        4,000원
        202.
        2009.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Changes in the surface morphology and light scattering of textured Al doped ZnO thin films on glasssubstrates prepared by rf magnetron sputtering were investigated. As-deposited ZnO:Al films show a hightransmittance of above 80% in the visible range and a low electrical resistivity of 4.5×10-4Ω·cm. The surfacemorphology of textured ZnO:Al films are closely dependent on the deposition parameters of heater temperature,working pressure, and etching time in the etching process. The optimized surface morphology with a cratershape is obtained at a heater temperature of 350oC, working pressure of 0.5 mtorr, and etching time of 45seconds. The optical properties of light transmittance, haze, and angular distribution function (ADF) aresignificantly affected by the resulting surface morphologies of textured films. The film surfaces, havinguniformly size-distributed craters, represent good light scattering properties of high haze and ADF values.Compared with commercial Asahi U (SnO2:F) substrates, the suitability of textured ZnO:Al films as frontelectrode material for amorphous silicon thin film solar cells is also estimated with respect to electrical andoptical properties.
        4,000원
        203.
        2009.05 구독 인증기관·개인회원 무료
        The Black Soldier Fly (BSF, Hermetia illucens) was widely distributed throughout Korea. This insect was mainly found in the vicinity of and in cattle sheds, manure sheds, living waste dump grounds, and food waste dump grounds. This fly is a kind of a beneficial fly because BSF adults do not go into houses, they do not regurgitate on human food, they do not bite, bother or pester humans in any way and they are not associated in any way with the transmission of disease. But their greatest attribute lies their ability to eat and digest raw waste. They can devour, for example, a large, raw, Irish potato and others in just a few hours. Unlike many other flies, since the BSF larvae have very powerful mouth parts and digestive enzymes, they can ingest raw waste far more efficiently than any other known species of fly. On this study, to investigate whether feeding strategy of the BSF larvae involves extra-oral digestion or not, and to better understand this process, the salivary glands and a few tissue from the BSF were dissected and subjected to morphological and preliminary enzyme characterization.
        204.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to determine the effects of Taxol pre-treatment to in vitro matured bovine oocytes, and sucrose and trehalose added to vitrification solution on spindle morphology and embryonic development following cryopreservation. Bovine oocytes were collected from ovaries and matured in tissue culture medium 199 (TCM 199) supplemented with 10% Fetal Bovine Serum (FBS), 0.05ng/ml epidermal growth factor, 0.01 IU/ml luteinizing hormone and estradiol for 22h in , 5% , TCM 199-HEPES containing 20% FBS was used as basic medium (BM) to prepare vitrification solution. Oocytes were pre-treated with Taxol in maturation medium for 15 min prior to vitrification. Oocytes were exposed to 1.6 M ethylene glycol (EG) and 1.3M dimethyl sulfoxide (DMSO) in BM and then were exposed to 3.2 M EG, 2.6 M DMSO and 0.5 M sucrose in BM or 3.2 M EG, 2.6 M DMSO and 0.5 M trehalose in BM. Oocytes with cumulus cells and oocytes without cumulus cells were considered as control 1 and control 2, respectively and held in TCM 199-HEPES at . Oocytes were frozen using modified solid surface vitrification and were stored in cryotubes in liquid nitrogen for more than 1 week. Frozen oocytes were thawed in TCM 199-HEPES containing 0.5 M, 0.25 M and 0.1 M sucrose in BM for 2 min, respectively or 0.5 M, 0.25 M and 0.1 M trehalose in BM for 2 min, respectively. Immunoflurorescence staining of oocytes was performed to assess spindle morphology and chromosome configuration of oocytes. The rates of cleavage and blastocyst were examined following in vitro fertilization. Normal spindle morphology rate of oocytes pre-treated with Taxol prior to vitrification was not higher than that of other vitrified groups. Taxol pre-treatment did not increase cleavage and blastocyst formation rates, although control groups showed significantly higher rates (p<0.05). Percentages of normal spindle and embryonic development were not significantly different among vitrified groups regardless of type of sugar. In conclusion, Taxol pre-treatment of oocytes before cryopreservation did not reduce the damage induced by vitrification and subsequently did not improve embryonic development following vitrification. Trehalose may be used as an alternative non-permeating cryoprotectant in vitrification solution.
        4,000원
        205.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 저광 조사 저온 저장 중 광합성유효방사(PAR)내의 각 파장이 토마토 묘의 형태와 엽색 변화에 미치는 영향을 조사하기 위하여 실시되었다. 10±0.5℃의 온도와 피크 파장이 각각 405, 450, 505, 545, 600, 645, 680, 700nm의 발광다이오드로부터 조사된 3μmol m-2s-1의 광합성유효광량 자속밀도 조건에서 토마토 접목묘를 28일간 저장하였다. 405, 450, 505nm의 파장에서 저장된 묘의 잎은 다른 파장에서 저장된 잎에 비해 직립하는 경향을 보였으며, 특히 450과 505nm 파장에서 저장된 묘의 경우 엽축 생장이 억제되면서 콤팩트한 형태를 보였다. 파장의 변화에 따른 엽색의 규칙적인 변화는 저장 전후를 비교하여 관찰되지 않았으나, 405와 700nm 파장에서 저장된 묘는 엷은 녹색을 나타내었다. 저광 조사 저온 저장 중, 450~545nm 영역의 광조사는 토마토 묘의 직립을 유도하여 외관상 건강한 묘로 인정 받는데 기여할 것으로 기대된다.
        4,000원
        206.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        친전자성 치환반응으로 제조된 술폰화 단량체, 비(非)술폰화 단량체 및 탄산칼륨을 이용하는 직접 중합법을 통하여 높은 점도의 술폰화 폴리아릴에테르술폰 공중합체를 합성하고, 이들을 원료로 N-메틸-2-피롤리돈(NMP)과 디메틸아세트아미드(DMAc)의 혼합 용매 상에서 직접 메탄을 연료전지용 고분자 전해질 막을 제조하였다. 막 제조 시의 용매 효과에 주목하여 혼합 용매의 부피 비는 0~100%로 변화시키고 공중합체의 술폰화도는 50%로 고정하였다. 이온 전도도 및 메탄올 투과도 측정을 통하여 최종 전해질 막의 기본 특성을 파악하고, 주사전자현미경 및 원자간력현미경분석을 통한 표면 분석 결과와 비교함으로써 이들의 상관관계를 고찰하였다. 막 제조 시의 용매 혼합 비율을 적절히 조절함에 따라 최종 전해질 막의 이온 전도도를 크게 향상시킬 수 있음이 확인되었는데, 25℃의 100% 가습 환경에서 측정된 수소 이온 전도도는 NMP : DMAc 50:50 부피/부피-%에서 최대 1.38×10 -1 S/cm이었다.
        4,300원
        207.
        2008.12 구독 인증기관 무료, 개인회원 유료
        Sagassum yezoense (Yamade) Yoshida et Konno is a large fucacean brown alga that occurs in Korea and Japan. The species is one of the most common and abundant marine algae on the east coast of Korea. Investigation on seasonal variation of growth and decline of thalli, reproduction, and morphological features of the species was carried out bimonthly for a target population in Homigot, Pohang, from April 2007 to February 2008. Ten quadrats (50 cm × 50 cm) per every visit were randomly put on S. yezoense beds and, after measuring its coverage, all thalli in the quadrats were collected, and examined for morphology. Surface seawater temperature was in a range of 9oC in February and 22.6oC in September. Coverage was high (74%) in April and low (15%) in October. The average length of thalli was large with 78.2 cm in June and was low 8.6 cm in September. Most of thalli were fertile in June, having male and female receptacles. S. yezoense beds gradually declined from August and small juveniles occurred from October. However, the length of leaves was shorter in June (1.7 cm) than (3.5 cm) in October, and the same was true for leaf width. S. yezoense had germination period from September, and growth period from December, and reproductive period from June. The Pearson correlation coefficient between length of thallus and surface seawater temperature was negative. As a low temperature species on the east coast, S. yezoense will be used as an indicator species for detecting warming of coastal waters in Korea.
        4,000원
        212.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        제올라이트 분리막을 형성시키기 위하여 결정핵으로 작용할 수 있는 동일한 제올라이트 입자들을 다공성 지지체 위에 균일하게 도포하는 기술을 개발하고자 하였다. 제올라이트 입자들을 수용액에 분산시킨 다음 이 수용액을 튜브형 다공성 세라믹 지지체에 일정 유속으로 공급하고, 세라믹 지지체의 반대편에 진공을 유지하여 일부 수용액이 지지체를 통과하면서 동시에 제올라이트 입자들을 지지체 표면에 도포하였다. 수용액 상에 분산된 제올라이트의 농도, 도포시간 그리고 분산 수용액의 공급속도 등이 결정핵 도포량에 미치는 영향을 고찰하였다. 공급유속이 100 mL/min, 도포시간이 4분인 경우 농도가 0.01 wt%에서 0.3 wt%로 증가할수록 도포량이 0.0019 g에서 0.0208 g으로 증가하였다. 농도가 0.01 wt%, 공급유속이 100 mL/min인 경우 도포시간이 1분에서 4분으로 증가하는 경우 도포량이 0.0004 g에서 0.0019 g으로 증가함을 알 수 있었다. 또한 농도가 0.3 wt%이고, 도포시간이 1분일 때 유속이 100 mL/min에서 300 mL/min으로 빨라진 경우 도포량이 0.002 g에서 0.01 g으로 증가함을 알 수 있었다. 그러나 도포량이 증가할수록 제올라이트 분리막을 통한 물과 에탄올의 총투과속도는 감소함을 확인할 수 있었다.
        4,000원
        213.
        2008.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The effects of the field emission property in relation to the surface morphology and adhesion force were investigated. The single-wall-nanotube-based cathode was obtained by use of an in-situ arc discharge synthesis method, a screen-printing method and a spray method. The morphologies of the formed emitter layers were very different. The emission stability and uniformity were dramatically improved by employing an in-situ arc discharge synthesis method. In this study, it was confirmed that the current stability and uniformity of the field emission of the cathode depend on the surface morphology and adhesion force of the emitters. The current stability of the field emission device was also studied through an electrical aging process by varying the current and electric field.
        4,000원
        214.
        2008.05 구독 인증기관·개인회원 무료
        Only two species of Eurydema occur in Korea and Japan: E. dominulus (Scopoli, 1763) [= E. pulchra (Westwood, 1837), syn. n.] and E. gebleri Kolenati, 1846 [= E. rugosa Motschulsky, 1861, syn. n.]. In order to prove the above taxonomical change, we focused on three major works (1)morphology, (2)molecular identification and (3)biological experiment (inter-specific copulation, confirmation of fertilization and interbreeding). All the results of these three major works support to confirm new taxonomical change amongst these four species. The inter-specific copulation occurs (E. pulchra_male X E. gebleri_female) in nature, but the eggs from inter-specific copulation are confirmed not to be fertilized as a result of the biological experiment. A new identification key to species occurring in Korea and Japan is presented for the all stages (from eggs to adult).
        215.
        2008.05 구독 인증기관·개인회원 무료
        A phylogeny of the tribe Aphidini (Hemiptera: Aphididae) was reconstructed using three molecular gene fragments: partial mitochondrial tRNA-leucine + cytochrome oxidase II (tRNA/COII), partial mitochondrial 12S + tRNA-valine + 16S (12S/16S), and nuclear elongation factor-1 alpha (EF1α) for a total of 41 species consisting of 37 representative species in Aphidini and 4 outgroup species in the tribe Macrosiphini. Also, to compare with the molecular analyses, a second phylogenetic reconstruction was performed using 41 morphological characters for equally weighted analysis. Minimum evolution, maximum parsimony, maximum likelihood, Bayesian phylogenetic analyses, and Bremer support test were performed for the phylogenetic construction. As our phylogenetic results were compared with the classical taxonomy based on morphological characteristics and biological data, we newly confirmed the following phylogenetic relationships within Aphidini: (1) each monophyletic subtribe of Aphidina and Rhopalosphina was supported by significant P values in the combined analysis, (2) contrary to the classical taxonomic position, Cryptosiphum should be moved to Macrosiphini because it is more closely related to Lipaphis and Brevicoryne in the myzine group of Macrosiphini, (3) The genus Toxoptera was possibly considered as a non-monophyletic group because three species were separately positioned in Aphidina, (4) In Rhopalosiphina, the genus Melanaphis was relatively divergent from three genera, Rhopalosiphum, Schizaphis and Hyalopterus, clustered in a strongly supported clade, (5) in the relationships among four the Aphis species-groups, which are accepted by most aphid taxonomists, most species except for some morphologically distinct species were separated to the two main lineages; the fabae-group was confirmed to be closely related with the spiraecola-group and craccivora-group, but the gossypii-group diverged as a monophyly from those three group.
        217.
        2008.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The crystal structures and morphologies of precipitates in L10-ordered TiAl intermetallics containing nitrogen were investigated by transmission electron microscopy (TEM). Under aging at an approximate temperature of 1073 K after quenching from 1423 K, TiAl hardens appreciably due to the nitride precipitation. TEM observations revealed that needle-like precipitates, which lie only in one direction parallel to the [001] axis of the L10-TiAl matrix, appear in the matrix preferentially at the dislocations. Selected area electron diffraction (SAED) pattern analyses showed that the needle-shaped precipitate is perovskite-type Ti3AlN (P-phase). The orientation relationship between the P-phase and the L10-TiAl matrix was found to be (001)p//(001)TiAl and [010]p//[010]TiAl. By aging at higher temperatures or for longer periods at 1073 K, plate-like precipitates of Ti2AlN (H-phase) with a hexagonal structure formed on the 111 planes of the L10-TiAl matrix. The orientation relationship between the Ti2AlN and the L10-TiAl matrix is (0001)H//(111)TiAl and H//TiAl.
        4,000원