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        검색결과 384

        101.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Morphological competence plays an important role in extending one’s vocabulary in grammatical context. This study is to explore the developmental distribution of English grammatical morphemes appearing in elementary English textbooks. To this end, the study developed grammatical morpheme recognition and elicitation tests based on the bilingual syntax measurement (BSM). The tests are given to 114 fifth graders and 126 sixth graders across small, medium and metropolitan cities. The students were stratified into high, mid and low English ability groups by their English achievement scores. The result shows that English grammatical morpheme awareness was positively correlated with students’ English ability. The grammatical morphological development of Korean students was more in alignment with that of English learners as a foreign language than that of native speakers. Pedagogical implications are provided at the end of the paper.
        5,800원
        102.
        2017.05 구독 인증기관·개인회원 무료
        The present study was conducted to investigate the effect of different heights from liquid nitrogen (LN2) vapor on sperm motility and morphology after frozen-thawing. Two ejaculates were collected from 2 fertile Hanwoo bulls (A and B) by using artificial vagina at Hanwoo Research Institute. After collection, ejaculates were transferred to laboratory immediately and diluted with semen extender (Optixcell, France). Sperm dilutions were extended to a final concentration of 40 x 106 sperm/ml, and cooled at 4°C for 4 h and loaded to 0.5 ml straws. The straws were divided into 2 groups. Straws were placed in 3 or 9 cm of LN2 vapor for 14 min and then plunged into LN2 tank and cryopreserved until evaluation. Sperm motility and motility parameters (total motility, VSL with 25μm≥, VCL, VSL, VAP, LIN, STR, WOB, ALH and BCF) were evaluated by sperm class analysis (SCA, IVOS, Spain) after frozen-thawed. In bull A, 3cm group showed higher percentages of total motility, VSL with 25μm and VAP compared those with 9cm group (98.0 vs. 93.4%, 62.4 vs. 54.0% and 98.6 vs. 93.2%, 3 vs. 9 cm, irrespectively; p<0.001). In bull B, frozen-thawed sperm of 3cm group showed higher percentages of VSL with 25μm, VCL, VSL, VAP and BCF compared with those of 9cm group (43.5 vs. 26.0%, 123.8 vs. 111.6 μm, 62.9 vs. 57.3 μm and 81.5 vs. 72.5 μm; 3 vs. 9 cm, irrespectively; p<0.001). The viability and acrosomal integrity of spermatozoa were evaluated by Trypanblue/Giemsa staining method divided into 4 groups; live and intact acrosome (LIA), live and damaged acrosome (LDA), dead intact acrosome integrity (DIA), dead damaged acrosome (DDA). In bull A, frozen-thawed sperm of 3 and 9cm groups showed no significant difference in LIA, LDA, DIA and DDA. In bull B, 3 cm group showed higher LIA and lower DIA compared with those of 9 cm group (73.2 vs. 23.7% and 23.7 vs. 32.2%, 3 vs. 9 cm, irrespectively; p<0.001). We suspected that 3 cm vapor on LN2 vapor might be affected positively spermatozoa viability and acrosomal integrity compared with 9 cm group. In conclusion, semen freezing procedure in the present study will improve sperm quality after frozen thawing.
        103.
        2017.05 구독 인증기관·개인회원 무료
        현재 상용 고분자들 중 폴리벤즈이미다졸(PBI)은 슈퍼 엔지니어링 플라스틱으로 내열성과 내화학성이 우수하다고 알려져 있다. 또한, 해당 고분자는 기계적 물성 및 화학적 물성 또한 우수하여 재료공학, 나노공학, 광학 이외에도 다양한 분야에 활용되고 있다. 본 연구는 용매-비용매 상전이법을 이용하여 폴리벤즈이미다졸 분리막을 제조하였고, 제조 시 다양한 조건들을 변화시켜 나타나는 모폴로지를 관찰하여 모폴로지 조절이 가능한 폴리벤즈이미다졸 분리막을 제조하였다. 용매와 조용매는 각각 DMAc와 THF를 사용하였고 나이프캐스팅법을 통하여 분리막을 제조하였다. 모폴로지는 주사전자현미경(SEM)을 통해 표면과 단면을 관찰하여 확인하였다.
        104.
        2017.04 구독 인증기관·개인회원 무료
        Ionic liquids (ILs) are organic salts with low melting point by asymmetric ionic strength between cation and anion. They have been known as promising DNA extraction, separation and preservation agent due to their hydrophilic, hydrophobic interaction with DNA. However, few studies have been performed about how DNA-ILs complexes form and their mechanism. Herein, we present three types of ionic liquids (EMIM-Cl, BMIM-Cl, and OMIM-Cl) change the DNA structure depend on alkyl chain length of ionic liquids. Structural changes of DNA by ionic liquids are observed by Atomic force microscopy, gel electrophoresis, zeta potential and solid-state nanopore technology. The results of AFM show the different structures of DNA, including aggregate, stretching, and bundling shapes in terms of EMIM-Cl, BMIM-Cl, and OMIM-Cl respectively. In DNA translocation experiment, DNA/EMIM-Cl show rare translocation signal due to aggregated structure by neutralized surface charge. DNA/BMIM-Cl and DNA/OMIM-Cl show slowing down the translocation speed due to changes of DNA net charge and structure. Especially, OMIM-Cl make slowing down the DNA translocation speed about 102~104 times compared to translocation speed of bare DNA by unzipping the bundling shape of complex. In conclusion, the morphology of DNA could be modified by the incorporation with different alkyl chain length of ILs, providing their further application in nanopore technique for slowing DNA sequencing or understanding protein-DNA interaction.
        105.
        2017.04 구독 인증기관·개인회원 무료
        Dendrolimus superans (Lepidoptera: Lasiocampidae) has long been acknowledged to present in South Korea under the circumstance of a substantial change in species names of Dendrolimus. In the present study, we found that specimens of D. superans collected from South Korea were D. sibiricus, rather than D. superans. Comparison of Korean specimens to the D. superans from Japan and the D. sibiricus from Russia in terms of wing morphology, female and male genitalia, a partial COI gene sequence, and a partial internal spacer sequence 2 (ITS2) consistently supported the presence of D. sibiricus in South Korea. Phylogenetic analyses using concatenated sequences of COI and ITS2 from available individuals of D. sibiricus and D. superans both by Bayesian inference and maximum likelihood methods the Korea samples to be D. sibiricus.
        106.
        2017.04 구독 인증기관·개인회원 무료
        Morphology of antennal sensilla and their distribution were investigated in male and female adults of Ooencyrtus nezarae, an egg parasitoid of Riptortus pedestris, using scanning electron microscopy. Antennae of O. nezarae was composed of scape, pedicel and seven flagella in both sexes. Six types of sensilla (s. trichodea, s. basiconica, s. chaetica, s. campaniformia, s. sickle-shaped and unknown s.) were identified from both sexes. Among them, s. trichodea and s. sickle-shaped were multiporous, others are not. They distributed in varying numbers. Sexual dimorphism was clearly observed in the distribution of s. trichodea (only on male antennae) and unknown sensilla (only on female antennae). These findings would be helpful for further studies on detailed sex specific-receptive functions of each antennal sensilla.
        107.
        2016.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.
        4,300원
        108.
        2016.11 구독 인증기관·개인회원 무료
        PVDF Membrane has been used as material for the UF membrane through in-situ interfacial polymerization (IP) because of it’s outstanding properties such as high chemical resistance, thermal stability, and mechanical strength. In this study, surface morphology change of PVDF membrane was researched depending on evaporation time. 13% PVDF 6020 was used for casting and the evaporation time period was from 5s to 600s. The surface morphology of the membrane was investigated by scanning electron microscopy (SEM) and filtration was conducted in the cross flow method to evaluate the a performance of UF membrane. As a result, average pore size was increased with longer evaporation times which caused the decrease of rejection.
        109.
        2016.11 구독 인증기관·개인회원 무료
        The anion exchange membrane fuel cells (AEMFCs) have been noticed as the promising power sources. One of the most important components in AEMFC is the anion exchange membranes(AEMs). Recently various materials for AEMs have been investigated for fuel cell applications. Imidazolium-based long alkyl chain multiblock copolymers have drawn much interest due to their well-defined phase separation between hydrophilic and hydrophobic blocks. We report herein the investigation of the effect of block ratio on the phase separation as well as mechanical and electrical properties of the corresponding membranes.
        110.
        2016.11 구독 인증기관·개인회원 무료
        Since Loeb and Sourirajan has introduced phase inversion method for membrane fabrication, the phase separation technique became the mainstream of membrane fabrication methods. Phase inversion includes solvent evaporation, vapor induced phase separation, thermally induced phase separation (TIPS) and nonsolvent induced phase separation (NIPS). Among those, NIPS and TIPS process is widely studied and employed for membrane fabrication. Depending on the membrane fabrication processes such as NIPS and TIPS, corresponding morphology differs from macrovoid structure to spherulitic structure, respectively. In this presentation, comparison of NIPS and TIPS effect on the final membrane morphology and controlling the membrane morphology by tuning the NIPS and TIPS effect will be presented.
        114.
        2016.10 구독 인증기관·개인회원 무료
        Semen collection from epididymis has been used as an important alternative tool, particularly on abnormal animals including those with joint disorder, poor sex drive and poor libido. However, previous studies had been focused on only recovery of sperm derived from testes, regardless of fundamental parameters such as age, body weight, scrotal circumference, testicular size (weight, length, width and volume) and semen volume. In addition, there is no precise castrating periods to recover sperm from young Hanwoo bulls’ testis. Therefore, we investigated fundamental parameters in Hanwoo bulls at 7, 8, 14, 15, 16 and 17 months of age, which parameter can be used for sperm recovery from testis. Before castration, body weight and scrotal circumference were recorded. After castration, testes were transported to laboratory and testicular weight, length and width were recorded. About 2 cm of epididymal tail was collected and minced using blades on 100 mm petridish. Minced epididymal tail tissues were mixed with Optixcell (France, IMV technologies) and debris were removed by filteration with 100 um nylon mesh. Seven to 8 months of age in bulls showed low fundamental parameters compared to those of at 14 to 17 months of age in bulls (body weight, 218-258 vs. 330-429 kg; scrotal circumference, 23.4-24.6 vs. 28.8-32.8 cm; testicular weight, 92-104 vs. 222.3-269.9 g; testicular length, 10.9-11.6 vs. 13.4-15.6 cm; testicular width, 4.7 vs. 6.2-6.6; testicular volume, 126.4-136.4 vs. 268.9-357.6 cm3, semen volume, 3.0-4.8 vs. 60.6-68.3 ml, p<0.001). In conclusion, to recover semen derived from epididymis of testis in young Hanwoo bull, these fundamental parameters should be satisfied; 330 kg of body weight, 28.8 cm of scrotal circumference, 222.3 g of testicular weight, 13.4 cm of testicular length, 6.2 cm of testicular width, 268.9 cm3 of testicular volume. In further study, fundamental parameters of 9 to 13 months of age in bull should be investigated to determine more accurate castrating periods for sperm recovery from testis.
        115.
        2016.10 구독 인증기관·개인회원 무료
        The habitat of the cockroach varies by species. The German cockroach (Blattella germanica) lives in human dwellings, while the Japanese field roach (Blattella nipponica) lives in a mountainous region. Based on phylogenetic analysis of mtCO I, the two species are closely related to each other and B. germanica is divergent from wild species such as B. nipponica. Their habitats and walking speed differ even though the two species have similar morphology. We hypothesized that habitats might influence walking speed via changes to appendage morphology and enzyme-based physiological differences. We found that phenotype such as appendage length and esterase isozyme expression were clearly different between the two species. These differences might be responsible for the observed difference in walking speed.
        116.
        2016.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We report on an all-solution-processed hydrothermal method to control the morphology of ZnO nanostructures on Si substrates from three-dimensional hemispherical structures to two-dimensional thin film layers, by controlling the seed layer and the molar contents of surfactants during their primary growth. The size and the density of the seed layer, which is composed of ZnO nanodots, change with variation in the solute concentration. The ZnO nanodots act as heterogeneous nucleation sites for the main ZnO nanostructures. When the seed layer concentration is increased, the ZnO nanostructures change from a hemispherical shape to a thin film structure, formed by densely packed ZnO hemispheres. In addition, the morphology of the ZnO layer is systematically controlled by using trisodium citrate, which acts as a surfactant to enhance the lateral growth of ZnO crystals rather than a preferential one-dimensional growth along the c-direction. X-ray diffraction and energy dispersive X-ray spectroscopy results reveal that the ZnO structure is wurtzite and did not incorporate any impurities from the surfactants used in this study.
        4,000원
        118.
        2016.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Flower-like nickel oxide (NiO) catalysts were coated on NiCrAl alloy foam using a hydrothermal method. The structural, morphological, and chemical bonding properties of the NiO catalysts coated on the NiCrAl alloy foam were investigated by field-emission scanning electron microscopy, scanning electron microscopy-energy dispersive spectroscopy, Xray diffraction, and X-ray photoelectron spectroscopy, respectively. To obtain flower-like morphology of NiO catalysts on the NiCrAl alloy foam, we prepared three different levels of pH of the hydrothermal solution: pH-7.0, pH-10.0, and pH-11.5. The NiO morphology of the pH-7.0 and pH-10.0 samples exhibited a large size plate owing to the slow reaction of the hydroxide (OH−) and nickel ions (Ni+) in lower pH than pH-11.5. Flower-like NiO catalysts (~4.7 μm-6.6 μm) were formed owing to the fast reaction of OH− and Ni2+ by increased OH− concentration at high pH. Thus, the flower-like morphology of NiO catalysts on NiCrAl alloy foam depends strongly on the pH of the hydrothermal solution.
        4,000원
        119.
        2016.04 구독 인증기관·개인회원 무료
        The cabbage whitefly Aleyrodes proletella L. (Hemiptera: Aleyrodidae) is a specialized insect that uses its mouthparts(stylets) to feed from the phloem of its host plants, which are found among the Brassicaceae and Asteraceae. Female whiteflies lay their eggs in circular patterns embedded in wax on the underside of the leaves. These were collected from the leaf of triangular lettuce, Crepidiastrum sonchifolium throughout the whole Chungnam province, 2013. We reared the cabbage whitefly on the egg-plant. The elongate-oval eggs are laid upright in a semicircle on the underside of Brassica leaves but didn’t in lab. Initially pale and translucent, the eggs become darker. Nymphs are scale-like and covered with wax; their color is white with two yellow spots on the abdomen. On the dorsal surface of the last abdomial segment is the vasiform orifice charactersitic of the group. The fourth instar is called the “pupa”. The pupa is thicker, immobile, and pale in color with red eyes. The adults are tiny, about 1.5 mm long, and moth-like. The head and thorax are dark. The abdomen is yellow and covered by a conspicuous white waxy layer. The forewings have a faint, dark bar. If disturbed, the adults fly readily. The duration of development of immature stages of Aleyrodes proletella decreased with increase in temperature, the mortality was higher below 16 ℃ and above 28 ℃.
        120.
        2016.04 구독 인증기관·개인회원 무료
        Chitin deacetylases (CDAs) are chitin-modifying enzymes that deacetylate chitin to form chitosan. In insects, this modification may contribute to the affinity and/or cross-linking of chitin/chitosan-like polysaccharides for a variety of structural proteins that may lead to diverse mechanical properties of the cuticle. DmCDA1 (serpentine) and DmCDA2 (vermiform) from Drosophila melanogaster play roles in development and morphology of embryonic tracheal tubes. We previously reported the functional importance of TcCDA1 and TcCDA2 orthologs to DmCDA1 and DmCDA2 from Tribolium castaneum, in molting, morphology of cuticle, and movement of legs. In this study, we further analyze ultrastructural defects of the cuticles and leg joints in TcCDA1- and TcCDA2-deficient insects. Loss of function of TcCDA1 and TcCDA2 causes disorganized chitinous horizontal laminae and vertical pore canals of rigid adult cuticle (e.g. elytron). Both proteins are also required for laminal organization in soft cuticle (e.g. hindwing). Morphological analysis of TcCDA1- and TcCDA2A-deficient adult revealed that ruptured tendons between femur and tibia cause the defects in movement of the leg joint. This work was supported by NRF (NRF-2015R1A2A2A01006614).