검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 29

        1.
        2024.10 구독 인증기관·개인회원 무료
        콘크리트 포장의 평탄성과 내구성은 환경 조건에 크게 영향을 받으며, 슬래브 상하부 간의 온습도 차이는 부등건조수축 및 와핑 (Warping) 현상을 유발하여 포장의 장기 성능 저하를 초래할 수 있다. 이는 주행성 저하, 균열 발생, 유지보수 비용 증가의 원인이 되 며, 특히 터널과 같은 특수 환경에서는 상하부 간의 습도 차이가 더욱 크게 나타나 부등건조수축이 심화될 가능성이 높다. 터널 내부 는 직사광선의 영향을 받지 않지만, 통풍이 잘 이루어져 건조한 환경이 조성되며, 이러한 조건에서는 슬래브 상부에서 수분 손실이 가 속화되고 하부는 습윤 상태를 유지하여 상하부 간의 큰 습도 차이를 발생시킨다. 이는 슬래브의 비균일한 수분 이동을 유발하여 부등 건조수축을 더욱 크게 발생하게 한다. 국내에서는 터널 길이가 500m 이상인 장대 터널에서 콘크리트 포장 적용이 증가하고 있으며, 아스팔트 포장 대비 화재 시 유독가스 발생 위험이 낮다는 이유로 국토교통부에서 콘크리트 포장을 권장하고 있다. 이로 인해 터널 내 콘크리트 포장의 사용이 증가하고 있 으나, 기상환경 변화 및 습도 관리 미흡으로 인해 콘크리트 포장 줄눈부에서의 평탄성 불량 문제가 빈번하게 발생하고 있다. 이러한 문제는 주행성 저하, 도로 이용자의 민원 증가 및 유지보수 비용 상승을 초래하고 있어, 구체적인 원인 분석과 대책 마련이 필요한 실 정이다. 따라서 본 연구는 터널과 같은 특수 환경에서 습도 조건이 콘크리트 슬래브의 부등건조수축에 미치는 영향을 실험적으로 분석하고, 슬래브의 수평 변형률 및 수직 변위를 측정하여 건조 수축에 따른 변형 거동을 정량적으로 평가하고자 하였다. 다양한 습도 조건에서 슬래브의 변형 양상을 비교 분석함으로써, 터널 환경에 적합한 콘크리트 포장 설계 및 유지관리 기준을 제시하고, 콘크리트 포장의 장 기 성능을 개선하기 위한 대책을 마련하고자 한다.
        2.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, numerical analysis was performed for the purpose of analyzing the flow characteristics and performance according to the change in the inflow hydrogen temperature and differential pressure of the receptacle of the hydrogen charging system. The pressure distribution and turbulent kinetic energy in the filter area were analyzed by changing the outlet pressure condition under the inlet hydrogen temperature condition, and the flow velocity change at the outlet was compared and analyzed. As a result of the analysis, as the differential pressure decreased, the flow rate at the outlet of the receptacle decreased by up to about 70% at the 2.86 MPa condition compared to the 1.86 MPa condition, and the mass flow rate decreased by about 56.5% at the maximum. It was found that the standard CV performance was not satisfied when the differential pressure at the inlet and outlet was 1.12 MPa or less under the 363K temperature condition.
        4,000원
        5.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study developed a scenario to understand the reaction rate and operational time according to RTI value of rate of rise detector in each type in case of fire mattress. In the results of analyzing the reaction rate and operational time of detector in each scenario, in case when installing a single detector, the elevated temperature per minute was raised to 8℃/min ~ 9℃/min. In case when installing two detectors, it was raised to 9℃/min ~ 10℃/min. In case when installing three detectors, it was raised to 10℃/min. The horizontal distance between detector and mattress was 1.8m~2.5m. Whenever the number of detectors was increased, the horizontal distance was decreased. The operational time of detector was within maximum 540 seconds and minimum 420 seconds. As the research tasks in the future, there should be the researches on the effects of reaction rate of detector on the evacuation in case of fire through the result value of RSET by setting up the latency until the detector operates, and the researches on the safety by understanding if the operational time of detector is suitable for the evaluation standard of performancecentered design.
        4,000원
        7.
        2019.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study focused on challenges faced by early childhood English teachers in Korea against the backdrop of the local rise of English education for young learners. A mixed-method was used to collect data, including open-ended survey questionnaires and interviews. Six teachers from 250 early childhood English teachers were selected for this study based on the length of teaching experience. A number of challenges emerged from the analysis of the survey, including classroom management, mixed-level class, motivation, teaching methodology, parents involvement, restrained English education in the context of Korea, the teacher’s level of English, lack of assessment and materials which fit early childhood language learners, and balancing between interest and learning. Nine distinct themes were found based on calculated frequency. They were cross-tabulated by two groups of teachers depending on whether teachers had less or more than three years of teaching experience. Results showed challenges and difficulties faced by teachers with lengthy teaching experience. Findings of this study suggest a way to build teacher education programs to support the challenges identified by teachers.
        6,000원
        8.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문은 MLS(moving least squares) 차분법의 1차 미분 근사함수를 바탕으로 시간에 따른 수치해석이 가능한 해석기법을 제시한다. 오직 1차 미분 근사함수로만 지배방정식을 이산화했으며, 근사함수를 조립하는 형태로 전체 시스템 방정식을 구성하여 차분법으로 이산화된 운동방정식이 유한요소법(finite element method)과 유사한 모습을 갖게 되었다. 운동방정식을 시간적분하기 위해서 중앙차분법(central difference method)을 사용하였다. 유한요소 알고리즘을 통해서 MLS 차분법과 유한요소법의 고유진동 해석을 수행하였으며, 두 해석결과를 비교하였다. 또한, 동적해석 결과를 기존의 2차 미분 근사함수를 활용한 해석결과와 함께 도시함으로써 제안된 수치기법의 정확성을 검증하였다. 1차 미분 근사함수를 조립하는 과정에서 해석결과의 떨림현상이 억제되었으며 상대적으로 균일한 응력분포를 구할 수 있었다.
        4,000원
        9.
        2017.05 구독 인증기관·개인회원 무료
        The coat color of mammals is determined by the melanogenesis pathway, which is responsible for maintaining the balance between black-brown eumelanin and yellow-reddish pheomelanin. The melanogenesis-associated genes controlling pigmentation act as a complex and interact with each other to cause phenotypic and genotypic variations in cattle. That the MC1R genotype of Korean native cattle with dark muzzle was e/e or E+/e, while the genotype of Korean native cattle with light muzzle was E+/E+, which is a variant of the MC1R genotype in the Korean native cattle. Especially, the MC1R expression type is shows how much pigmentation, important factor in deciding its status in the coat and nose colours. However, information regarding the coat or nose colours-associated gene regulation of korean cattle is not yet unknown. Therefore, in this study was to investigate the expression patterns of melanogenesis-associated genes in black dot nose(korea brindle cattle) and normal nose(korea native cattle). Using microarray clustering and real-time polymerase chain reaction techniques, we analysed that the expression of genes involved in the mitogen-activated protein kinase (MAPK) and Wnt signaling pathways is distinctively regulated in the dark and light muzzle tissues. Differential expression of tyrosinase was also noticed, although the difference was not as distinct as those of MAPK and Wnt. We hypothesize that emphasis on the MAPK pathway in the Korea brindle cattle induces eumelanin synthesis through the activation of cAMP response elementbinding protein and tyrosinase, while activation of Wnt signaling counteracts this process and raises the amount of pheomelanin in the native cattle. Regarding the increasing interest in the genetic diversity of cattle stocks, genes we identified for differential expression in the brindle cattle vs. native cattle may serve as novel markers for genetic diversity among cows based on the coat and muzzle color phenotype.
        10.
        2016.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Appropriate thermo-mechanical properties of nickel-based superalloys are achieved by heat treatment, which induces precipitation and solid solution hardening; thus, information on the temperature ranges of precipitation and dissolution of the precipitates is essential for the determination of the heat treatment condition. In this study, thermal analyses of nickelbased superalloys were performed by differential scanning calorimetry method under conditions of various heating rates of 5, 10, 20, or 40K/min in a temperature range of 298~1573K. Precipitation and dissolution temperatures were determined by measuring peak temperatures, constructing trend lines, and extrapolating those lines to the zero heating rate to find the exact temperature under isothermal condition. Determined temperatures for the precipitation reactions were 813, 952, and 1062K. Determined onset, peak, and offset temperatures of the first dissolution reaction were 1302, 1388, and 1406K, respectively, and those values of the second dissolution reaction were 1405, 1414, and 1462K. Determined solvus temperature was 1462K. The study showed that it was possible to use a simple method to obtain accurate phase transition temperatures under isothermal condition.
        4,000원
        11.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fire detectors are designed to minimize loss of life from a fire alarm system as an alarm to help evacuate more quickly until the completion of the evacuation alarm should be continued. the purpose of such alarms in order to achieve the characteristic fire heat release rate reaches a certain level, or when a certain time has elapsed, when the heat detector is to be alarms to answer. Requires a quick response, it is desirable to install the sensor as much as possible, but taking into account the cost of installation problems by engineering approach to minimize the quantity and rapidity of detection capability should be increased. In order to increase the rapidity of fire detectors in a room according to the height of the sensing period is to be maintained the optimum distance of the fire detector detects characteristics should be considered. Differential spot-type heat detectors installed domestic basis, depending on the type of sensor that can detect one sensor area is limited and less than 4m ceiling height regulations and simply double the number in excess of 4m and intended to be installed
        4,200원
        12.
        2013.12 구독 인증기관 무료, 개인회원 유료
        This experiment was conducted to investigate the genetic effects of candidate genes on the growth of spleen and liver tissues using dietary Curcuma longa (C. longa) supplementation. Expression analyses of candidate genes regarding animal growth was performed in order to determine the factors affecting the growth related to immune components of Curucumin, Turmerone, and Zingiberene as the bile secretion Paratolyl methyl carbinol (PTMC). The animals were divided into four groups of five chicks supplied with experimental diets of C. longa at 0.25, 0.5 and 1% and controls. The 19 growth-related genes were known to cell maturation, differentiation significant expression patterns in this analysis. Expression of growth response-related genes in chicks supplemented with 1% of C. longa showed better growth performance than chicks with 0.25 and 0.5% in spleen (p<0.05). The IGF1, MSTN, POU1F1, ADCYAP1 gene were known to central roles in mediating gonadotropin function, regulating steroidogenesis and promoting oocyte growth and maturation. Sex steroids, androgen and estrogen can affect sex differentiation and also can affect muscle development. On the other hand, GHSR and FABP3 gene showed significant expression patterns in this analysis. The results would be used as basic information for the variation of growth-related genes expression on the cell growth, sex cell growth, and sex hormones according to dietary supplementation with C. longa in chickens.
        4,000원
        14.
        2011.05 구독 인증기관·개인회원 무료
        In this study, we compared global proteome profiles and the expression pattern of defense-related genes in Chinese cabbage when infested by Myzus persicae and Plutella xylostella. Four-week-old Chinese cabbage was exposed to each insect for 24 h, and then proteins and total RNA were extracted from leaves. To elucidate the herbivore-induced differentially expressed proteins in Chinese cabbage, proteins were separated by two-dimensional gel electrophoresis, and visualized by staining with Coomassie G250. Approximately 1600 protein spots were separated and 249 protein spots showed reproducible changes in expression. Among them, nine proteins whose expressions were markedly up-regulated in M. persicae-infested group were identified using matrixassisted laser desorption/ionization time of flight mass spectrometry. The identified herbivore-responsive proteins (ribulose-1,5-bisphosphate carboxylase/ oxygenase, ATP synthase CF1, putative mismatch binding protein Mus3, and integrase core domain-containing protein) were involved in regulation of photosynthesis, carbohydrate metabolism and DNA repair. The expression levels of chitinase, b-1,3-glucanse, peroxidase, PR1, and PR4 in herbivore-infested Chinese cabbage were analyzed by reverse transcription-polymerase chain reaction. The results clarify the response of Chinese cabbage to two herbivore attack at the protein level.
        15.
        2010.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Differential item functioning (DIF) has been studied as a statistical method of finding item bias, and DIF studies have been conducted on tests of verbal abilities such as reading comprehension and vocabulary knowledge. Recently, researchers of language testing sought to understand the causes of DIF. The purpose of this study was to find possible sources of explaining DIF on an EFL vocabulary test, which can then benefit EFL learners and teachers as well. This study thus applied three DIF detection methods (the likelihood ratio test, SIBTEST, and the Mantel-Haenszel test), followed by a regression analysis using item categories and difficulties as predictors of explaining DIF. As a result, only the “Academic” category was statistically significant, positively contributing to DIF in favor of male examinees. Male examinees were better at academic lexical words than female learners of EFL at the same vocabulary knowledge level. This also means that female learners were relatively strong at nonacademic words in comparison to male EFL learners. This finding may lead to more effective curriculum of teaching English. The need for more evidence from replicated studies with better item categorization is also warranted.
        5,400원
        16.
        2007.04 KCI 등재 구독 인증기관·개인회원 무료
        The human ELAV(embryonic lethal abnormal vision)-like protein HuR stabilizes a certain group of cellular mRNAs that contain AU- ri ch elements in theil‘ 3’• untranslated region, Dysregulation of mRNA s tability may be relevant in tumor biology and may lead to abnormal expression of several proteins in malignant tumors, The aim of this study is to identify the differentially expressed proteins according to the functi onal activi ty of HuR Methods : We used stabl e expression of small interfering RNA(siRNA) of HuR gene to inhibit the expression of HuR in human ora l car cinoma cell lines‘ KB cell line and YD10B cell line‘ and compared the proteomic changes between s iRNA-treated and cont rol cell line using two-dimensional gel electrophoresis , Flow cytometry caliber scan(FACS) was employed to investigate the effects of HuR on cell apoptosis and proliferation , Results: Seventeen differentially expressed proteins between the two cell lines were identified by electrospray ioruzati on quadrupole time-of- fl ight mass spectrometry(ESI-Q-TOF MS) and database searching, Among them there are eleven proteins which are significant ly up- regulated in siRNA- treated cell line, which include heat shock protein 10(influencing nucl eocytoplas rnic transpo 다, cell dedifferentiation , and inhibition of apoptosis) , keratin 19(basal cell differ ent iat ion) ‘ and nucleoside diphosphate kinase B(G protein activator), etc Enolase 1 and Ml of pyruvate kinase a re the representatives of signifi cantly down-regulated proteins in siRNA-treated cell 11l1e Conclusion : Our data suggest that HuR participate in mRNAs stability of proteins that have the counter effects in the carcinogenesis of oral ca ncer , And the functiona l proteomics a re needed to elucidate the detailed interactions between HuR and t hese molec ules
        17.
        2005.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Studies to evaluate distribution of markers in normal keratinocyte and their immortalized keratinocyte are appropriate to evaluate the normal and preneoplastic lesion of oral cancers as biochemical and cytochemical changes associate with tumorigenesis being not completely understood. Complementary DNA microarray containing 6000 sequence -verified cDNA elements was used to systematically characterize the variation in gene expression patterns of NHOK cells vs. immortalized keratinocyte by HPV16 E6-E7(IHOK). Examination of gene expression that is 85 clones cDNAs exhibits greater than 2 fold overexpression in NHOK probes relative to IHOK probe, 147 cDNAs reveal greater 2 fold overexpression in IHOK relative to NHOK probe.The high similarity in gene expression (96.5%) between IHOK and NHOK cells suggests that only an additional 232/6720 (3.5%) of the genome is differentially gene activated during HPV16 immoratlized keratinocyte growth and differentiation. Examination of gene expression that differs between NHOK and IHOK cellsapprear to be related to : cell adhesion & recognition, cell cycle regulator, apoptosis, transciption factors, growth factors and therir receptors, cytoskeletal and extracellular matrix proteins, signal transduction modulators and effectors, and miscellaneous. The gene expression of cell recognition factor such as endothelin 1, collagen IV, fibronectin, and SPR1 in IHOK were upregulated. Distinct or duplicated cDNA clones representing the same gene were typically clustered in adjacent rows in the clustered gene map. Therefore the differentially expressed and identified genes should be informative in studying oral epithelial cell carcinogenesis and such studies should foster the research of molecular markers allowing to assess the phenotypeof malignant epithelial tumor.
        4,300원
        20.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        곤충병원세균이 효과적으로 병원력을 발휘하는 데 대상 곤충의 면역저하가 요구될 수 있다. 본 연구는 대상곤충의 면역저하가 병원세균의 살충능력에 직접 연관된다는 가설을 세웠다. 곤충병원세균을 5령 누에(Bombyx mori)의 혈강에 접종하였을 때, X. nematophilus는 다른 곤충병원세균인 Staphyiococcus gallinarum 보다 1,200배 높은 병원력을 보였다. 비록, 두 곤충병원세균은 누에의 혈구세포에 대해서 독성효과를 가지고 있지만, X. nematophiius는 S. gallinarum과 비교해보다 빠르고 높은 세포독성 영향을 보였다. 세포성 면역반응에서 5농도로 세균이 접종되었을 때, 누에는 약 20개 정도의 소낭을 형성하였다. 특히, 살아있는 X. nematophilus가 접종된 누에에서 소낭 형성은 크게 감소하였지만, S. gullinarum은 소낭 형성 감소에 영향을 주지 않았다. 두 세균 모두는 prophenoloxidase (proPO)의 활성화를 억제시켰다. 그러나 X. nematophilus.가 S. gallinarum보다 높게 PO 활성화를 억제시켰다. 라이소자임의 활성유도는 S. gallinarum접종 후 4시간에서 관찰되었으나, X. nematophilus를 접종하였을 때는 라이소자임의 활성이 전혀 관찰되지 않았다 이러한 결과들은 누에에서 X. nematophilus가 S. gallinarum보다 더 큰 면역저하를 유발하여 병원성을 높였다는 것을 보여준다. 따라서 본 연구는 곤충병원세균에 의해서 유발된 면역저하는 곤충병원세균의 병원성과 연관되어 있다는 것을 제시한다.다.
        4,000원
        1 2