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Graphite Nanosheets/PVDF 복합체의 열전 성질
윤호동(Ho Dong Yoon),남승웅(Seung Woong Nam),응우옌두(Nguyen D K Tu),김대흠(Dae Heum Kim),김희숙(Hee Suk Kim) 한국고분자학회 2013 폴리머 Vol.37 No.5
유연 열전소자를 제조하기 위한 열전재료로서, graphite nanosheet(GNS)와 poly(vinylidene fluoride) (PVDF)를 복합화하여 GNS/PVDF 복합체를 제조하였다. GNS의 함량에 따른 전기전도도, 열전도도, 지벡상수를 측정하여열전성능을 확인하였다. GNS의 함량이 10에서 70 wt%로 증가하면서 전기전도도는 389에서 1512 S/m로 향상되는결과를 보였다. 복합체의 전기전도도가 크게 증가하는 반면에 지벡 상수는 26.7에서 31.2 μV/K로 큰 변화를 보이지않았으며, 열전도도 역시 0.24 W/m·K를 유지하면서 변화를 보이지 않았다. 고분자와의 복합화를 통하여 GNS 자체의 높은 열전도도를 낮춤으로써 향상된 열전성능을 갖는 열전재료를 제조할 수 있었다. GNS/PVDF composites were prepared using graphite nanosheets (GNS) and poly(vinylidene fluoride) (PVDF)for flexible thermoelectric application. We measured the electrical conductivity, thermal conductivity and Seebeck coefficient of GNS/PVDF composites with different contents of GNS and then evaluated the thermoelectric properties of GNS/PVDF composites. The electrical conductivity of GNS/PVDF composites increased from 389 to 1512 S/m with increasing the content of GNS from 10 to 70 wt%. While the electrical conductivity dramatically increased, Seebeck coefficient and thermal conductivity did not show any big difference as the content of GNS increases. In this study, we demonstrated that GNS/PVDF composites improved the thermoelectric properties by decreasing the thermal conductivity due to the phonon scattering at the interfaces between polymer and GNS nanoplatelets.
수산물 가공부산물의 이용에 관한 연구 1 - 가다랭이 내장 발효 silage 제조를 위한 유산균주의 배양특성
윤호동(Ho Dong Yoon),이두석(Doo Seog Lee),지청일(Cheong Il Ji),서상복(Sang Bok Suh) 한국수산과학회 1997 한국수산과학회지 Vol.30 No.1
In order to utilize fish by-products from the skipjack tuna (Katsuwonus pelamis) canning manufactures, Lactobacillus bulgaricus KCTC 3188 and L. plantarum KCTC 1048 were used as a starter culture for the preparation of fermented fish silage with skipjack tuna viscera. The optimum temperature and pH on bacterial growth and lactic acid production of L. bulgaricus and L. plantarum in MRS broth were 35℃ and around pH 6.0, respectively. And the optimum concentrations of the carbohydrate sources added to the broths were 7% far dextrose and 10% for molasses on the basis of total weights of skipjack tuna viscera. The pH of acid treated skipjack tuna viscera silage (ASS) slightly increased from 4.0 to 4.5, while that of fermented skipjack tuna viscera silages by the use of lactic acid bacterias (FSS) was significantly declined from 5.9 to about 4.0 after 42 days of storage at 35℃. Though the content of volatile basic nitrogen (VBN) in ASS was lower than those of FSS after 42 days of storage at 35℃, VBN content in silages slightly increased from an initial value of 62∼65 ㎎/100 g to final value of 113∼155 ㎎/100 g over 42 days. The fermented silage by L. plantarum reached a maximum concentration of amino nitrogen and showed 81% of hydrolysis degree after 4 days of storage at 35℃.
수산물 가공부산물의 이용에 관한 연구 2 - 가공방법에 따른 가디랭이 내장 silage 의 저장 중 성분변화
윤호동(Ho Dong Yoon),이두석(Doo Seog Lee),서상복(Sang Bok Suh) 한국수산과학회 1997 한국수산과학회지 Vol.30 No.1
For an effective use of fish by-products from the skipjack tuna (Katsuwonus pelamis) canning manufactures, the changes of chemical properties of skipjack tuna viscera silage by the processing method during storage were investigated. The acid treated skipjack tuna viscera silage (ASS) were higher in the contents of moisture, lipid, protein and mineral but lower in the contents of carbohydrate and polyunsaturated fatty acids than those of fermented skipjack tuna viscera silage (FSS) by L. bulgaricus, KCTC 3188 and L. plantarum, KCTC 1048. Especially, the contents of total n-3 fatty acids in FSS increased remarkably during storage. The dominant amino acids in ASS and FSS were glutamic acid (Glu), aspartic acid (Asp), leucine (Leu), glycine (Gly), and alanine (Ala). And the contents of tryptophan (Trp) decreased by 30% in ASS and 5% in FSS in comparision with that of raw skipjack tuna viscera after 42 days of storage. The concentration of vitamin B₁and B₂in FSS increased gradually during storage but the concentration of vitamin B₂in ASS decreased. In the organoleptic evaluation, ASS gave a grayish brown color and a fishy odor. On the other hand, FSS had reddish brown color and sour taste by the production of lactic acid during storage.
노무라 입깃 해파리(Nemopilema nomurai)로부터 항균활성물질의 분리 및 정제
문호성 ( Ho Sung Moon ),김연계 ( Yeon Kye Kim ),이문희 ( Moon Hee Lee ),윤나영 ( Na Young Yoon ),이두석 ( Doo Seog Lee ),윤호동 ( Ho Dong Yoon ),서정길 ( Jung Kil Seo ),박남규 ( Nam Gyu Park ) 한국수산과학회(구 한국수산학회) 2011 한국수산과학회지 Vol.44 No.5
An antimicrobial material was purified from the acidified whole body extract of the jellyfish Nemopilema nomurai by using C18 reversed phase and cation-exchange high performance liquid chromatography (HPLC). Whole body extract and the purified compound (JAP-1) showed potent antimicrobial activities against a wide range of microorganisms including Escherichia coli D31, Bacillus subtilis, Streptococcus iniae and Candida albicans, without significant hemolytic activity. Treatment of JAP-1 with trypsin completely abolished all antibacterial activity against Bacillus subtilis, suggesting that JAP-1 is likely to be a proteinaceous antibiotic. The molecular weight of JAP-1 was determined to be 680.10 Da by MALDI-TOF mass spectroscopy.
메기(Silurus asotus )에 투여한 멜라민의 체내함량 변화
김풍호 ( Poong Ho Kim ),조미라 ( Mi Ra Jo ),이희정 ( Hee Jung Lee ),김경덕 ( Kyoung Duck Kim ),하광수 ( Kwang Soo Ha ),유현덕 ( Hyun Duk Yoo ),유홍식 ( Hong Sik Lee ),이두석 ( Doo Seog Lee ),윤호동 ( Ho Dong Yoon ) 한국수산과학회(구 한국수산학회) 2011 한국수산과학회지 Vol.44 No.6
In 2007, pet food contaminated with melamine caused hundreds of dogs and cats to develop renal failure all over the world. In 2008, over 294,000 infants consumed infant formula and developed kidney stones in China. Further investigation revealed that fish feed also contained melamine; this raised concerns about melamine residues in edible fish tissues, which could have caused the urinary tract stone epidemic. In Korea, catfish fed with assorted feed that included cuttlefish organs that contained melamine developed whitening syndrome and fell dead in some populations in 2008. This event raised suspicions about the toxicity of melamine and all feeds containing melamine were immediately recalled. In this study, we investigated the rates of melamine accumulation and depletion in muscle and viscera of catfish to propose proper withdrawal periods. One group of catfish was fed a commercially available diet that contained 30, 100 and 300 mg melamine per kg diet for 14 days. To investigate residual melamine contents in muscle and viscera, other experimental groups were fed a melamine free diet after being fed melamine for 7 days. The residual amount of melamine was analyzed by LC-MS/MS. The melamine concentration in muscle was estimated to be 3.7 mg/kg after 6 days of feeding with a diet containing 300 mg melamine/kg. After 2 days of culture with a melamine free diet, the residual melamine was depleted and the concentration had decreased from 1.15 mg/kg to 0.19 mg/kg in the muscle of catfish fed a diet containing 300 mg melamine/kg for 7 days. The residual amount of melamine was reduced to 0.03 mg/kg in muscle after 7 days of culture with a melamine free diet and was undetectable after a prolonged culture period of 14 days. Catfish tend to excrete melamine rapidly after oral administration and changes in body color were not observed during the short dosing period.