검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 554

        308.
        1993.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 다공성 니켈재료의 원료분말로 활용될 수 있는 hollw 니켈금속분말 계조를 위한 니켈-흑연복합분말의 흑연코어 기화과정에 관하여 실험을 행하였다. 수증개-수소 혼합가스에 의한 복합분말중 흑연코어의 기화온도는 800˚C~900˚C였으며, 약 1시간의 기화반응에 의해 내부가 텅 빈 hollw니켈금속분말을 얻을 수 있었다. 흑연코어의 평균입도가 21μm인 82.2tw,% 니켈-17.87tw.5 흑연 복합분말로부터 제조된 hollw니켈금속분말을 100Kg/c m2의 압력으로 압축, 성형한 성형체의 겉보기 기공도는 45%이었으며, 이성형체를 진공로에서 1150˚C 의 온도로 1시간 소결하여 30%의 기공도와 소재내에 균질한 기공분포를 갖즌 소결체를 얻음으로써 다공성재료 제조시 hollow분말을 원료로 사용하여 재료 내의 기공에 관한 제반사항을 쉽게 조절할 수 있다는 가능성을 확인하였다.
        4,000원
        309.
        1993.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 탄소/탄소복합재료의 마모특성에 대한 탄소섬유 길이의 영향을 고찰하였다. 매트릭스 precursor로 레졸형의 페놀수지와 강화재로 표면처리를 하지않은 PAN계 단섬유형 탄소섬유를 사용하여 액상함침법으로 1회의 고온열처리 공정과 4회의 탄화공정을 통하여 탄소/탄소복합재료를 제조하였다. Disk-on-disk형의 마모시험기를 통하여 상대 마찰재로 AISI 304 stainliss steel을 사용하여 0.6MPa(61 ×103Kg/m2)의 압력과 0.71m/sec의 미끄러짐 속도하에서 측정된 탄소/탄소복합재료의 마찰계수는 0.2-0.3이었다. 마찰계수에 대한 섬유의 길이의 영향은 크게 나타나지 않았지만, 마모 속도는 섬유의 길이가 증가함에 따라 증가하는 경향이 나타났다. 본 실헙 결과를 섬유 강화 플라스틱의 마모 모델을 적용하여 고찰하여 본 결과, 섬유의 길이가 증가함에 따라 탄소/탄소복합재료의 마모 속도가 증가되는 경향은 생성된느 마모조각의 크기가 커기기 때문에 나타난 현상으로 판단되었다.
        4,000원
        310.
        1992.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        여러 연구자들의 연구결과를 토대로 하여 침채류의 염장 발효과정중 나타나는 여러가지 화학적 성분과 조직감의 변화를 살펴본 결과, 식물조직의 변화는 펙틴질의 성질에 크게 영향을 받고 있었으며, 이러한 조직의 변화에 관여하는 요인들은 소금의 종류 및 농도, 절임시간, 온도, 예열처리, 염혼합물, 효소, 젓갈, 마늘첨가량 등이 복합적으로 작용하고 있었다.
        4,000원
        311.
        1992.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The needles and pollen of Pinus densiflora and Pinus koraiensis were studied for their lipid contents and fatty acid composition. The total lipid contents in needles of Pinus densiflora and Pinus koraiensis were 5.0 and 4.5%, whereas in pollen of Pinus densiflora and Pinus koraiensis 3.5 and 5.6%, respectively. Twenty-four fatty acids ranged from lauric acid to docosahexaenoic acid(22:6Ω3) were identified in the needle lipids. In needles, linolenic acid and palmitic acid were the major fatty acids. The needles of Pinus densiflora showed higher proportions of docosahexaenoic acid and 5-olefinic nonmethylene-interrupted polyenoic acids than those in the Pinus koraiensis. Twenty fatty acids ranged from myristic acid to lignoceric acid were identified in the pollen lipids. Linoleic acid was the major fatty acid in the pollen followed by oleic and palmitic acid. The fatty acid profile of pollen of Pinus densiflora was similar to those of the Pinus koraiensis pollen lipids.
        4,000원
        313.
        1991.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The seeds of wild and cultivated Camellia japonica were studied for their lipid contents and fatty acid composition. The seeds of wild and cultivated Camellia japonica contained 70.2% and 73.4% lipids, respectively. Fifteen fatty acids were identified in the lipids from the Camellia japonica seeds. In addition to confirming the 5 previously reported (16 : 0, 18 : 0, 18 : 1, 18 : 2 and 18 : 3), 10 more acids were characterized. The newly identified acids were 14 : 0, 16 : 1, 17 : 0, 20 : 0, 20 : 1, 20 : 2, 22 : 0, 22 : 1, 24 : 0 and 24 : 1. Both seeds lipids contained 18 : 1 in high levels (81. 6~82. 2%). Little difference in fatty acid composition was noted between the wild and cultivated Camellia japonica seed lipids. The fatty acid composition of commercial Camellia japonica oil was similar to those of the Camellia japonica seed lipids.
        3,000원
        314.
        1991.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Based on a precise analysis of the long-term(1971-1984) hydrographic and wintertime air temperature data gathered in the middle and southern yellow Sea, and together with other supplimentary data from Gteratures, water characteristics of the Yellow Sea Bottom Cold Water(YSBCW) and its southward extension are reexamined ; the influence of the wintertime air temperature on the YSBCW temperature and on its spatial distribution also discussed. It was found that the hitherto defined water characteristics (T, S) of the YSBCW restrict especially the upper limit of salinity to too lower values compared to the real situation, so they are not adequate to describe the spatial distribution of the water and its southward extension phenomenon. From the present study, the southward extention of the YSBCW through the cold water through west off Chejudo from spring to summer is found highly possible ; it is strongest is April and it can be detected until August. In consequence of such a southward advection of the bottom cold water, the water temperature at 50m depth in the cold water through west off Chejudo shows its lowest values in April, with a mean temperature increase by 0.4℃ only from April to August(compared to 4℃ increase near the axis of the Yellow Sea embayment). The frequently observed cold water mass from the west to the southwest(near 32°N, 126°E)off the island during spring and summer is connected with and influenced profoundly by the bottom cold water from the southern Yellow Sea, showing almost same water. characteristics as those of the latter ; it preserves quite well its wintertime water characteristics until summer. Therefore it seems to be quite reasonable to include this cold water mass(found west to southwest off Chejudo) in the definition of the YSBCW. Here, we have suggested a new definition of the YSBCW : T$lt;12℃, 32.2$lt;S$lt;33.5‰ With this new definition, the spatial distribution of the YSBCW from the offshore of the Shandong peninsula to the southwestern area off Chejudo as well as its southward extension from spring to summer can be adequately described. The wintertime air temperature is one of the most important meteorological factors, controlling the summertime water temperature of the YSBCW and its spatial distribution. In other words, the bottom cold water formed during a severe cold winter exhibits in summer lower temperatures and also wider spatial distribution toward the coasts and to the south than that formed during a mild winter.
        4,500원
        318.
        1989.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study area located in Chongpung-myon and Kumsong-Myon, Chewon-Kun, Chungbuk Province consists of the Chosun Group (Great Limestone Series) in eastern part and the Okchon Group in Western part. In order to clarify the structural relationship between the two groups, structural patterns and geologic features have systematically been investigated. The dominant structural features of the area are NW~E trending thrust faults, which are interpreted to have formed by progressive northward thrust movement during the Late CretaceousrEarly Tertiary orgeny. The predominant ocurrence of cataclastic rocks such as fault breccia, fault clay and micro-breccia suggests that the thrust faults were formed at relatively high level. The folds in limestone area consist of the primary fold (axial plane of NNW direction)and the secondary fold (axial plane of NE direction). F1 fold looks like a recumbent fold and F2 fold looks like up-right fold. The interference patterns of the area are applicable type 3. According to the interlimb angle F1 fold is included to the closed fold and F2 fold the open fold. The micro fabric study reveals that the ductile deformation is dominant in this area. According to the strain measurements using the deformed quartz grains, Lode'value(ν) is-0.24∼1.00 and the strain ellipsoids are oblate and prolate strain type.
        4,600원
        319.
        1987.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of procedures for preparation of fatty acid methyl esters for gas chromatography were investigated. A quantitative comparison of four procedures for the preparation of the fatty acid methyl esters from Korean sesame seed lipids which can be representative of fatty acid ranges of Korean vegetable oils has been made. The procedures employed were BF3-methanol, HCI-methanol, sodium methoxide-methanol, and tetramethylammonium hydroxide-methanol. Twelve fatty acids ranged from 14:0 to 24:0 were identified in the lipids from Korean white and black sesame seeds. All four procedures gave similar results for the fatty acids, 16:0, 18:0, 18:1, 18:2, and 18:3 present in the range of 1~44% but only in the HCI-methanol procedure, the fatty acids, 16:1, 20:0, 22:0, 24:0 present in the range of 0.02~1% showed the lowest values. When using tetramethylammonium hydroxide-methanol procedure for determination of total fatty acid composition from white and black sesame seed lipids, unsaponifiable matters including sesamol, sesamolin and sesamin present in the seed lipids are not removed from the resulting reaction mixture. Thus the transesterification mixture is used without further treatment for injection into the gas chromatography. However, the gas chromatographic analysis of the transesterification mixture showed that the unsaponifiable matters had no effect on the fatty acid composition of the seed lipids. From the results, it appears that the BF3-methanol, sodium methoxide-methanol and tetramethylammonium hydroxide-methanol procedures can be used to prepare fatty acid methyl esters from Korean vegetable oils. Among the methods, the tetramethylammonium hydroxide-methanol procedure, which give total fatty acid composition, glyceride fatty acid composition and composition of free fatty acids present, appears to be a simple, convenient and quantitative procedure and applicable to samples containing broad ranges of fatty acids.
        4,000원