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        검색결과 875

        401.
        2012.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        막 구조물은 일반적인 설계와는 달리 형상해석, 응력변형해석 및 재단도 과정을 수행하여야만 설계가 가능하다. 처음 두 과정과는 달리 재단은 3차원 곡면을 최소 오차를 가진 평면 스트립을 형성하는 과정이다. 경제적인 이유로 재단 선은 주로 측지선을 이용하여 작성된다. 그러나 일반적으로 측지선은 초기 형상탐색에서 구성된 삼각형 요소의 정보에서 추출됨으로 부드러운 곡선이 아니며, 불규칙한 직선이다. 그러므로 어떻게 불규칙한 직선을 곡선으로 표현할 것인가가 중요하다. 따라서 본 연구에서는 스플라인 함수를 이용한 보간 방법을 재단도 생성에 적용하였다. 이를 위해서 삼차 스플라인 함수, B-스플라인 함수 및 최소자승 스플라인 함수의 세 가지 경우에 대해서 고찰하고, 단순 모델 및 카테나리 모델을 대상으로 재단도 작성 결과를 검토하였다. 단순모델의 해석요소수와 추출된 불연속 절점 수에 따른 보간 곡선 비교결과는 요소수가 큰 경우 추출된 절점의 수가 적은 것이 효과적이며, 최소자승 보간이 다른 방법보다 더 부드러운 재단 경계선을 제공한다.
        4,200원
        402.
        2012.02 구독 인증기관 무료, 개인회원 유료
        From results of three components analysis about food waste, moisture content appeared high in order of school(89.1%), townhouse(64.9%), apartment(63.2%) and home(63.2%). And content of ash also appeared high in order of school(8.8%), townhouse(6.3%), apartment(5.4%) and home(4.2%). This is judged as cause of difference of moisture content according to emission-source, diversity of kind of cooked food and volume-rate disposal system which is not performed. Meanwhile, combustible content is 10.9~32.6% and it is the most highest in order of home, apartment, townhouse and school. And big difference of standard deviation of apartment and townhouse is judged as difference of homogeneity due to co-emission of food waste. In addition, Low heating value appeared high in order of home(1086.07 kcal/kg), apartment(1033.69 kcal/kg), townhouse (678.07 kcal/kg) and school(9.18 kcal/kg). And the reason that heating value of school is very low is error about simple formula which is applied when moisture content is more than 50%. And it can be confirmed that this is difficult in analysis of Low heating value of food waste.
        4,000원
        404.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        비탄성요구스펙트럼의 형상은 구조물의 내진성능평가 결과에 많은 영향을 미친다. 비탄성요구스펙트럼은 강도감소계수를 적용하여 탄성응답스펙트럼을 비례축소시킴으로써 얻어질 수 있다. 이 연구는 기존에 많은 연구자들이 제안한 강도감소계수의 공식을 조사하였다. 이 논문에는 과거에 제안된 공식에 따라 작성된 강도감소계수 곡선과 비탄성요구스펙트럼 곡선의 형상 및 특성을 비교하고 있다. 조사된 공식으로 작성된 강도감소계수 곡선의 평균곡선을 구하고, 회귀분석을 통하여 평균 곡선의 공식을 유도하였다. 비교 연구를 통하여, 새롭게 제안된 강도감소계수 공식에 따라 작성된 비탄성요구스펙트럼의 형상은 기존에 제안된 공식으로 생성한 비탄성요구스펙트럼의 평균곡선과 일치함을 확인하였다.
        4,300원
        405.
        2011.12 구독 인증기관 무료, 개인회원 유료
        The present study was conducted to examine the reactive oxygen species (ROS) generation levels and subsequent DNA damage in the bovine cultured somatic cells. Bovine ear skin cells were classified by serum starvation, confluence and cycling cells. Cells were stained in 10 μM dichlorohydrofluorescein diacetate (H2DCFDA) or 10 μM hydroxyphenyl fluorescein (HPF) dye to measure the H2O2 or ˙OH radical levels. The samples were examined with a fluorescent microscope, and fluorescence intensity was analyzed in each cell. H2O2 and ˙OH radical levels of cultured somatic cells were high in confluence group (7.1±0.7 and 8.4±0.4 pixels/cell, respectively) and significantly low in serum starvation group (4.9±0.4 and 7.0±0.4 pixels/cell, respectively, p<0.05). Comet tail lengths of serum starvation (148.3±5.7 μm) and confluence (151.1±5.0 μm) groups were found to be significantly (p<0.05) increased in comparison to that of cycling group (137.1±7.5 μm). These results suggest that the culture type of donor cells can affect the ROS generation, which leads the DNA fragmentation of the cells.
        4,000원
        406.
        2011.12 구독 인증기관 무료, 개인회원 유료
        Induced pluripotent stem (iPS) cells have been generated from mouse and human somatic cells by etopic expression of transcription factors. iPS cells are indistinguishable from ES cells in terms of morphology and stem cell marker expression. Moreover, mouse iPS cells give rise to chimeric mice that are competent for germline transmission. However, mice derived from iPS cells often develop tumors. Furthermore, the low efficiency of iPS cell generation is a big disadvantage for mechanistic studies. Nonviral plasmid‐based vectors are free of many of the drawbacks that constrain viral vectors. The histone deacetylase inhibitor valproic acid (VPA) has been shown to improve the efficiency of mouse and human iPS cell generation, and vitamin C (Vc) accelerates gene expression changes and establishment of the fully reprogrammed state. The MEK inhibitor PD0325901 (Stemgent) has been shown to increase the efficiency of the reprogramming of human primary fibroblasts into iPS cells. In this report, we described the generation of mouse iPS cells devoid of exogenous DNA by the simple transient transfection of a nonviral vector carrying 2A‐peptide‐linked reprogramming factors. We used VPA, Vc, and the MEK inhibitor PD0325901 to increase the reprogramming efficiency. The reprogrammed somatic cells expressed pluripotency markers and formed EBs.
        4,000원
        408.
        2011.11 구독 인증기관·개인회원 무료
        원자력을 이용한 황-요오드 수소생산 공정 중 황산용액을 이송하는 기존의 시스템과 달리 새로운 황산 이송장치는 벨로우즈 박스 내에서 벨로우즈 외측으로 고온 부식성 액체인 황산이 흐르고, 벨로우즈 내측으로는 냉각수가 흐르는 상태에서 주기 운동을 통해 황산용액이 펌핑 되도록 구성된다. 200 ℃ 이상의 고온 부식성 액체인 황산용액을 정량으로 이송할 수 있도록 장치의 주요부품인 벨로우즈 주변의 열해석을 통해 온도분포를 확인하여, 테프론 재질의 벨로우즈의 내식성 및 내열성을 파악하고, 장치의 안전하고 효율적인 운용을 위한 기초자료를 취득하고자 하였으며, 냉각수 입구직경 3 ㎝, 질량유량이 3.9199 ㎏/s로 고정한 경우 벨로우즈의 길이에 관계없이 테프론 변형온도 이하임을 알 수 있었다.
        409.
        2011.11 구독 인증기관·개인회원 무료
        가막만은 여수반도와 돌산도, 고돌산반도 로 둘러싸인 반폐쇄성 해역으로 남북방향 길이가 약 15km, 동서 방향 길이가 약 9km인 타원형 내만이며, 평균 수심은 약 9m인 천해로 총면적은 112km2이고, 용적은 10.2×108m3으로 알려져 있다(수산진흥원 전라 남도, 1982). 만 내부의 해저지형을 보면 북서 내만 역은 대형 웅덩이 형태로서 저층해수가 고여 있는 정 체 현상을 보이고 있다. 중앙부는 수심 6~7m 내외이 며, 북서쪽은 수심이 9~11m로 육지로부터 유입되는 생활하수 등 여러 가지 물질들이 수렴되는 지역이다. 가막만의 북쪽과 중앙해역에는 수하식 패류(진주담치 와 굴) 양식장이 많고, 만 입구에서는 해상 가두리 어 류 양식장이 많이 분포되어 있어 과도한 양식, 양식장 의 장기사용 및 생활하수의 유입증가로 인한 어장환 경 관리에 많은 문제점들이 발생하고 있다. 북서 내만 해역은 해수 정체와 하수 및 폐수의 유입으로 부영양 화가 진행되고 있으며, 수온이 높은 하계에는 저층해 수에서 빈산소층이 빈번히 형성된다(해양수산부, 2001).
        410.
        2011.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        저류층 내에 부존되어 있는 탄화수소의 매장량을 계산하기 위해서는 그 저류층의 공극률이 필요하다. 일반적으로 시추공 이외의 지역에 대한 공극률은 시추공에서 얻은 공극률 검층자료로부터 외삽하여 얻지만, 시추공을 포함한 지역에서 획득한 탄성파탐사 자료가 존재하는 경우 시추공 자료와 함께 탄성파 탐사 자료를 이용하여 시추공 이외의 지역에서 보다 정확한 유사 공극률을 추출해낼 수 있다. 이 연구에서는 다항식 신경망 기법을 이용하여 탄성파 탐사 자료와 공극률 검층 자료로부터 유사 공극률 검층 자료를 생성하는 모듈을 개발하였다. 먼저 탄성파 탐사 자료로부터 추출된 지하매질의 특성을 나타내는 탄성파 속성(seismic attribute)과 심도에 따른 시간의 자료로 변환된 공극률 검층 자료로부터 다항식 신경망 기법을 사용하여 상관계수를 추출하였고 이 계수를 이용하여 시추공이 없는 지역에서의 공극률 정보를 생성하였다. 한편, 개발된 모듈에서는 보다 정확한 공극률을 획득하기 위하여 각각의 탄성파 속성들과 공극률 검층 자료와의 상관성 분석을 통해 상관성이 높은 탄성파 속성들을 사용하였다. 개발된 다항식 신경망 모듈의 신뢰성, 활용성을 검증하기 위하여 개발된 모듈을 북해 F3 지역의 현장자료에 적용하고, 얻어진 결과를 상용 프로그램에서 사용되는 확률론적 신경망 기법을 통해 얻어진 결과와 비교하였다. 두 방법으로부터 얻은 결과들은 유사한 결과를 보였으며 이를 통해 개발된 모듈의 신뢰성을 입증할 수 있었다. 또한, 다항식 신경망 기법으로부터 얻어진 유사 공극률 검층 자료가 확률론적 신경망 기법을 통해 얻어진 결과보다 실제 값에 더 가깝다는 것을 보여주었다. 따라서 북해 F3 지역과 같이 시추공 자료가 부족한 지역에서는 다항식 신경망 기법이 효과적임을 알 수 있었다.
        4,000원
        411.
        2011.10 구독 인증기관·개인회원 무료
        Despite of the absence of hyperacute rejection and acute humoral xenograft rejection, the organ graft of the a1,3-galactosyltransferase (GalT) gene knockouted (KO) and complement regulatory protein (CRP) expressing pig into a nonhuman primate is rejected by development of a thrombotic microangiopathy and/or a consumptive coagulopathy. Thus further introduction of genes to overcome the coagulation incompatibilities between pig and primate under GalT KO/CRP genetic background has been strongly suggested. CD73 (ecto-5'-nucelotidase) is an enzyme attached via a glycosyl phosphoinositol anchor to the extracellular membrane of endothelial cells, which catalyses the hydrolysis of adenosine triphosphate to adenosine. Loss of activity of CD73 results in activation and aggregation of platelets by a reduced capacity to convert nucleotides to adenosine. In previous study, we reported generation of GalT KO fibroblasts concurrently expressing membrane cofactor protein and produced cloned pigs by nuclear transfer of the fibroblast cells (1). In this study, we constructed a vector for expression of human CD73 under control of promoter of pig Icam2 gene expressed specifically at endothelial cells. This vector was introduced into porcine fibroblasts using the nucleofection technology, by which we had forty three fibroblasts clones carrying pIcam2- CD73 vector. Somatic cell nuclear transfer resulted in generation of two transgenic piglets survived.
        412.
        2011.10 구독 인증기관·개인회원 무료
        MicroRNAs are ~22nt small noncoding RNAs that control gene expression at the posttranscriptional level through translational inhibition and destabilization of their target mRNAs. Micro RNAs are phylogenetically conserved and have been shown to be instrumental in a wide variety of key biological processes including cell cycle regulation, apoptosis, control of metabolic pathways, imprinting and differentiation. The expression of miRNAs is often regulated in tissue specific and developmental stage‐specific manners. More than 500 miRNAs have been reported in diverse eukaryotic organism so far. One of the biological functions of miRNAs seems to be the regulation of self‐renewal versus differentiation in stem cells. Recent efforts have focused on defining the miRNA expression profile in undifferentiated ESCs as compared to their differentiated progeny. Among the so‐called ES‐specific miRNAs, the 302‐367 cluster stands out due to its intracellular abundance and high cell type specificity. Levels of miRNA 302‐367 correlate with Oct4 transcripts in ESCs and early embryonic development, indicating an important role in ESC homeostasis and maintenance of pluripotency. Several months ago, a paper showed that expression of the miRNA 302‐367 cluster can directly reprogram mouse and human somatic cell to an iPS cell in absence of any of the four factors (Oct4, Sox2, c‐Myc, Klf4) efficiently. To apply this efficient method to porcine, we made an inducible vector system including miRNA 302‐367 cluster originated from porcine embryonic fibroblasts and could make porcine ips by the miRNA 302‐367 cluster.
        413.
        2011.10 구독 인증기관·개인회원 무료
        It is known that oocytes can be activated without male contribution in vitro and develop to blastocysts which are used to isolate parthenogenetic embryonic stem (ES) cells. Differentiation capacity of the parthenogentic ES cells was rather lower than that of fertilized embryos derived ES cells, which might be the result of the absence of male genome. However, parthenogenetic ES cells might be useful research tool for genetic engineering and generating SCNT embryo derived ES cells. In our previous study, we reported that establishment of several bovine ES cell lines from in vitro fertilized (IVF) embryos named JNU-ibES. Based on this data, the objective of this study is to generate parthenogenetic ES cells and to examine their stem cell characteristics. Total 107 parthenogenetic embryos produced at day 8 or 9 were classified into their developmental stages (full expanded x 40, hatched x 67). For producing ES cells, ICM and trophetoderm-rich clumps were mechanically dissociated and were cultured on mitomycin- C treated mouse embryonic fibroblast feeder cell drop and covered with mineral oil in DMEM medium containing 20% FBS, 5 ng/ml basic FGF, 1% nonessential amino acids, and 0.55 mM b-mercaptoethanol. We obtained 20 primary parthenogenetic bovine ES (pbES)-like cell colonies. And pbES colony formation was higher in hatched blastocyst (25.4%, 16/67) than expanded blastocysts (10%, 4/40). Among those colonies, 5 pbES cell lines were successfully established and they were named as a series of JNU-pbES. These pbES cells were positively expresssed pluripotency markers such as Oct4, Nanog, TRA-1-81, SSEA-1 and alkaline phosphatase. This result demonstrated that the establishment efficiency and characteristics of pbES cell line was very similar to those of ibES cell line.
        414.
        2011.09 구독 인증기관 무료, 개인회원 유료
        Immunotherapeutic approaches using agonist antibodies or fusion proteins of immunomodulatory molecules significantly inhibit tumor growth and boost cell-mediated immunity. We isolated mRNA from previously reported 1D4 hybridoma cells and amplified the variable regions of the heavy chain (VH) and light chain (VL) genes using reverse-transcriptase polymerase chain reaction. Using a linker, the amplified sequences for the heavy and light chains were each connected to the sequence for a single polypeptide chain that was designed to be expressed. VL and VH fragments were cloned into the pOptiVEC-TOPO vector containing the human CH2-CH3 fragment. Then, 293T cells were transfected with the 1D4 single-chain Fv-Fc (scFv-Fc) constructs. A549 cells were used for presentation of the 1D4 antigen. Flow cytometry was performed for analysis of the secreted 1D4 scFv-Fc constructs. The DNA sequence of 1D4 scFv-Fc was obtained. The 1D4 scFv-Fc constructs were expressed by the transfected 293T cells and secreted into the culture medium. The immunoreactivity of the secreted scFv-Fc construct was lower than that of the murine 1D4 antibody for A549 cells. A 1D4 scFv-Fc construct for immunotherapy was developed.
        4,000원
        415.
        2011.06 구독 인증기관 무료, 개인회원 유료
        The present study was conducted to examine the reactive oxygen species (ROS) generation levels in porcine parthenogenetic embryos. Porcine in vitro matured oocytes were activated by the combination of electric stimulus and 6‐ DMAP before in vitro culture. Porcine oocytes and parthenogenetic embryos were stained in 10 μM dichlorohydrofluorescein diacetate (DCF) or 10 μM hydroxyphenyl fluorescein (HPF) dye each for 30 min at 39℃. The fluorescent emissions from the samples were recoded as JPEG file and the intensity of fluorescence in oocytes and embryos were analyzed. H2O2 and ˙OH radical levels of porcine oocytes were reduced immediately after electric stimulation. However, H2O2 and ˙OH radical levels of parthenogenetic embryos were increased with time elapsed after electric stimulation from 0 h to 3 h and after DMAP culture. During in vitro culture, H2O2 and ˙OH radical levels were gradually increased from the one‐cell stage to the two‐ and four‐cell stages. The result of the present study suggests that the ROS was not increased by electric pulse in porcine embryos. Rather than it seems to be associated with the stage of development and the culture condition.
        4,000원
        416.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In general, zona pellucida (ZP) of the blastocyst has to be removed first, then either isolated the inner cell mass (ICM) or ZP-removed whole blastocyst, which is then cultured on the feeder layer to induce ICM outgrowth for the generation of embryonic stem cells (ESC). However, it is unclear whether ICM isolation before seeding on feeder layer is beneficial or not because the interaction between ICM and trophoblasts may affect cellular growth and/or pluripotency during the culture on the feeder. In the present study, two ZP removal methods (mechanically by splitting with a 28-gauge needle versus chemically by the treatment of acid-Tyrode's solution) and two ICM isolation methods (ZP-free whole blastocyst seeding versus mechanical isolation of ICM) were evaluated for the efficient isolation and culture of putative parthenogenetic bovine ESC. The number of maintained outgrown colonies was counted in each experimental group. As the result, mechanical removal of ZP with a needle and followed by whole ZP-free blastocyst seeding on feeder cells tended to attach more on the feeder layer and resulted in more outgrown colonies with its simple and less time-costing benefits. Currently we are generating ESC lines in HanWoo cattle by using this method for initial outgrowth of the parthenogenetic bovine blastocysts.
        4,000원
        417.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study focuses on the Repeated Measurements Design (RMD) which observations are periodically made for identical subjects within definite time periods. One of the purposes of this design is to monitor and keep track of replicated records within regular period over years. This paper also presents the classification models of RMD that is developed according to the number of factors in Between-Subject (BS) variates and Within-Subject (WS) variates. The types of models belong to each number of factors: One factor is 0BS 1WS. Two factors are 1BS 1WS and 0BS 2WS. Three factors are 1BS 2WS and 2BS 1WS. Lastly, the four factors include model of 2BS 2WS In addition, the study explains the generation mechanism of models for RMD using Generalizability Design (GD). GD is a useful method for practitioners to identify linear model of experimental design, since it generates a Venn diagram. Lastly, the research develops three types of 1BS 2WS RMDs with crossed factors and nested factors. Those are random models, mixed models and fixed models and they are presented by using Generalizability Design, (S:A×B)×C. Moreover, the example of applications and its implementation steps of models developed in the study are presented for better comprehension.
        4,000원