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        검색결과 24

        1.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        경주 및 포항 지진으로 인한 수도관의 파열 및 누수로 배관 시스템용 신축이음부의 내진 안전성 확보가 강조되고 있 다. 일반적으로 금속 벨로우즈에 스테인리스강을 이용한 금속 벨로우즈가 사용되며 목적에 따라 다양한 주름 형상과 단층 및 다층 형태로 제작된다. 그러나 벨로우즈의 불규칙한 산의 형상에 대한 휨 거동 및 피로 파괴에 대한 연구는 미비하다. 본 연구 에서는 벨로우즈의 불규칙한 산의 형상을 고려한 휨 거동을 검토하기 위하여 단조시험, 준정적 반복재하시험 및 피로시험을 수 행하였다. 시험을 위해 제작된 벨로우즈는 단층(1ply)과 다층(3ply)으로 제작되었다. 다층 벨로우즈의 최대하중과 최대변형이 단 층 벨로우즈보다 크게 평가되었다. 단층 벨로우즈는 산과 산 사이에서 파괴가 되었으며, 다층 벨로우즈의 경우에는 산에서 파괴 가 발생하였다. 주름의 높이와 전체 두께가 다른 벨로우즈의 휨 파괴 거동을 평가하였으며, 단층의 초기 피로 균열은 고정 플랜 지와 첫 번째 산의 곡률에서 관찰되었다. 다층의 경우에는 첫 번째 산과 두 번째 산 사이의 곡률에서 관찰되었다.
        4,000원
        3.
        2017.05 구독 인증기관·개인회원 무료
        모든 난산 중 어미소의 원인으로 인한 난산이 24%를 차지한다. 난산으로 인한 어미소의 폐사율은 태아의 원인(13%)에 비해 어미소의 원인(32%)이 더 크다. 젖소 품종 중에서 홀스타인종의 난산 발 생율이 40%로 가장 높은데, 어미소 체중에 대한 송아지 체중의 비율이 홀스타인종의 경우 평균 7.1%(10% 이상인 경우도 있음)로 저지종의 5.6~6.3%에 비해 높기 때문이다(Holland와 Odde, 1992). 분만장애가 발생되면 분만 후에도 여러 가지 산후장애가 속발되어 도태율이 높아지는데, 유열 2 배, 난소낭종 3배, 좌측전위 2배, 후산정체 및 자궁염 2~3배의 위험성이 증가된다(Rajala와 Grohn, 1998). 따라서 본 연구는 분만 시 보조의 필요성 여부 및 보조의 시점을 판단하는 지표를 개발하 기 위하여 젖소와 한우를 대상으로 수행하였다. 송아지의 생시체중을 40kg 이하 및 41kg 이상으로 구분한 것은 40.3kg의 임계치를 넘으면 난산율이 크게 증가하고 사망률이 매우 높아진다는 Menissier와 Foulley(1979)의 보고에 근거한 것이다. 태아의 반응, 우설색깔 및 우설길이는 Hard (2008)의 방법에 따라 측정하였다. 태아의 반응은 태아의 혀를 꼬집었을 때, 태아가 반응하는 강도 를 기준으로 1(반응 없음), 2(약간 반응), 3(상당히 반응), 4(즉각 반응)로, 우설색깔은 17가지 색조 를 1∼3(어두움), 4∼9, 10∼17(밝음)로, 우설길이는 55mm 이상과 이하로 구분하였다. 분만유형은 순산(보조 없이 자연적으로 분만) 및 보조(상당한 힘이나 견인하여 보조)로 구분하여 분석하였다. 발굽둘레는 Parish 등(2009)의 방법에 따라 출생 직후 줄자로 송아지의 발굽둘레를 측정하였고, 본 연구에서 15.7cm 이하와 15.8cm이상으로 구분한 것은 조사된 24두의 평균 발굽둘레가 15.7cm였기 때문에 중앙치로 구분하여 분석하였다. 본 연구를 수행한 결과 다음과 같은 성적을 얻었다. 생시 체중에 따른 분만유형은 순산의 경우 40kg 이하 및 41kg 이상이 각각 81.8% 및 53.8%였고, 보조 (견인)의 경우 18.2% 및 46.2%였다. 생시체중에 따른 평균 발굽둘레는 40kg 이하 및 41kg 이상이 각각 14.8±0.5cm 및 16.5±0.3cm였다. 생시체중에 따른 발굽둘레 분포는 15.7cm 이하의 경우 40kg 이하 및 41kg 이상이 각각 63.6% 및 30.8%였고, 15.8cm 이상의 경우 36.4% 및 69.2%였다. 산차에 따른 분만시간 분포는 30분 이내의 경우 1산, 2산 및 3산 이상이 각각 28.6%, 37.5% 및 33.3%였 고, 31~60분의 경우 각각 57.1%, 12.5% 및 33.3%였으며, 61분 이상의 경우 각각 14.3%, 50.0% 및 33.3%였다. 산차에 따른 분만유형은 순산의 경우 1산, 2산 및 3산 이상이 각각 61.5%, 72.7% 및 70.0%였고, 보조(견인)의 경우 각각 38.5%, 27.3% 및 30.0%였다. 우설특성에 따른 분만시간 분포는 30분 이내의 경우 정상 및 비정상이 각각 27.3% 및 0%였고, 31~60분의 경우 각각 63.6% 및 0%였 으며, 61분 이상의 경우 각각 9.1% 및 100%였다. 우설특성에 따른 분만유형은 순산의 경우 정상 및 비정상이 각각 90.9% 및 0%였고, 보조(견인)의 경우 각각 9.1% 및 100%였다.
        4.
        2015.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Self-assembled monolayers(SAM) of microspheres such as silica and polystyrene(PS) beads have found widespread application in photonic crystals, sensors, and lithographic masks or templates. From a practical viewpoint, setting up a highthroughput process to form a SAM over large areas in a controllable manner is a key challenging issue. Various methods have been suggested including drop casting, spin coating, Langmuir Blodgett, and convective self-assembly(CSA) techniques. Among these, the CSA method has recently attracted attention due to its potential scalability to an automated high-throughput process. By controlling various parameters, this process can be precisely tuned to achieve well-ordered arrays of microspheres. In this study, using a restricted meniscus CSA method, we systematically investigate the effect of the processing parameters on the formation of large area self-assembled monolayers of PS beads. A way to provide hydrophilicity, a prerequisite for a CSA, to the surface of a hydrophobic photoresist layer, is presented in order to apply the SAM of the PS beads as a mask for photonic nanojet lithography.
        4,000원
        5.
        2014.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The quality characteristics of noodles made from domestic Korean wheat flour added with 0, 1, 3, 5% cactus Chounnyuncho (Opuntia humifusa) powder were investigated. The water absorption and peak time of dough, as determined by farinography, increased with higher cactus powder content. Stability and elasticity of dough decreased as fermentation proceeded. Cooking characteristics of noodles made from dough such as weight, water absorption, and volume decreased with higher cactus powder content. The turbidity of cooked water increased significantly with 5% cactus powder content. For color test, L-value decreased while a-value and b-value increased with higher cactus powder content. In texture analyses, hardness, adhesiveness, springiness, cohesiveness, and gumminess increased with higher cactus powder content. In the sensory test, noodles containing 3% cactus powder were the most preferred.
        4,000원
        6.
        2013.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was investigated the optimal time that enhanced the functional activities of mung beans for use of functional food resources. Mung beans were roasted according three levels of roasting time levels (10, 20 and 30 minutes) at 110℃ and then the physicochemical compositions were determined. The reducing sugar content was decreased with the increased roasting time. Moisture was decreased with increased roasting time, whereas, crude fat, crude ash, crude protein and carbohydrate were increased with prolonged roasting time. The highest contents of total phenol and flavonoid were shown at a roasting condition 110℃ for 30 minutes. The highest inhibitory activities of DPPH radical, ABTS radical and xanthine oxidase was the best at the condition of 110℃ for 30 min. From these results optimal roasting time of mung beans were 30 minutes for use of functional food resources.
        4,000원
        7.
        2013.03 구독 인증기관 무료, 개인회원 유료
        The objective of this work was to analyze the concentrations of progesterone (P4) and estrogen (E2) hormones changed during estrus synchronization in dairy heifers. Estrus synchronization was carried out with CIDRⓇ (Controlled Intravaginal Drug Release) devices. Corpus luteum (CL) was classified into three grades based on its size and palpable characteristics. The concentrations of P4 and E2 were measured by enzyme-amplified chemiluminescence. Serum P4 concentration was markedly low at the estrus stage (36 hrs after removal of CIDR) compared to other stages, while E2 concentration was kept high during estrus stage. The serum P4 concentration was highest in the CL classified into gradeⅠ. These results indicate that P4 concentration could be used as a criteria for determining recipients for artificial insemination or embryo transfer in dairy cattle.
        4,000원
        11.
        2012.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Bismuth antimony telluride (BiSbTe) thermoelectric materials were successfully prepared by a spark plasma sintering process. Crystalline BiSbTe ingots were crushed into small pieces and then attrition milled into fine powders of about 300 nm ~ 2μm size under argon gas. Spark plasma sintering was applied on the BiSbTe powders at 240, 320, and 380˚C, respectively, under a pressure of 40 MPa in vacuum. The heating rate was 50˚C/min and the holding time at the sintering temperature was 10 min. At all sintering temperatures, high density bulk BiSbTe was successfully obtained. The XRD patterns verify that all samples were well matched with the Bi0.5Sb1.5Te3. Seebeck coefficient (S), electric conductivity (σ) and thermal conductivity (k) were evaluated in a temperature range of 25~300˚C. The thermoelectric properties of BiSbTe were evaluated by the thermoelectric figure of merit, ZT (ZT = S2σT/k). The grain size and electric conductivity of sintered BiSbTe increased as the sintering temperature increased but the thermal conductivity was similar at all sintering temperatures. Grain growth reduced the carrier concentration, because grain growth reduced the grain boundaries, which serve as acceptors. Meanwhile, the carrier mobility was greatly increased and the electric conductivity was also improved. Consequentially, the grains grew with increasing sintering temperature and the figure of merit was improved.
        4,000원
        12.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A study was conducted to investigate the efficiency of recipient for Embryo Transfer (ET) in Holstein Heifers. A total of 193 heifers (Age 14-20 months and body weight, 250-400 Kg) was assigned in 2 groups (natural ovulation cycle group and Hormone-induced ovulation synchronization group) based on the development of corpus luteum (CL) and uterus where 28.49% (55/193) heifers were in normal estrous. The ET technique was applied in both of the groups to transfer the embryo in the recipients and evaluated their efficiency. In vivo frozen embryos were used for ET at the blastocyst stage. Results showed that according to recipient preparation method the conception rates were 22.72% (10/44) and 40.26% (60/149) in hormone-induced ovulation synchronization group and natural ovulation cycle group, respectively. The pregnancy rate of heifers was significantly higher (p<0.05) during the first time ET compared to repeat ET; however, recipient showed no significant difference in CL development in both side. The conception rate were 31.03% (9/29), 37.75% (57/151) and 15.38% (2/13) at day 6, 7 and 8, respectively after the CL development of the heifers. The conception rate was significantly higher (p<0.05) in the right side compared to left side of the CL development. In addition, during ET anesthesia group and non anesthesia group conception rate of the recipient were 27.63% (21/76) and 41.88% (49/117), respectively.
        4,000원
        13.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study was analyzed substances that high contribute to odor strength degree which emitted from the painting, the plating, the casting, the rubber manufacturing, and the used oil refining facilities in Gwangju Hanam industrial complex. In order to this, we analyzed two types of nitrogen compounds, five types of sulfur compounds, thirteen types of the aldehyde, and ten types of volatile organic compounds discharged from an outlet for antipollution facilities. The results are as following high contribution rate sustances to odor strenth was ordered butylaldehyde (73.8%) > acetaldehyde (17.7%) > propionaldehyde (4.9%) at painting facilities. At plating facilities, it was ordered Acetaldehyde (59.0%) > ammonia (19.1) > hydrogen sulfide (13.1%). At casting facilities, it was ordered Hydrogen sulfide (65.9%) > acetaldehyde (17.2%) > sulfur dioxide(5.2%). At rubber manufacturing facilities, it was ordered i-valeraldehyde (35.0%) > butylaldehyde (32.0%) > n-valeraldehyde (13.3%) and at used oil refinery facilities, it was ordered Acetaldehyde (36.8%)> butylaldehyde (33.6%) > sulfur dioxide (14.5%).
        4,000원
        14.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to determine physiological and mechanical factors effecting on the pregnancy rates following artificial insemination in dairy cattle. Estrus for artificial insemination of cows was checked whether the outflow of mucus from the elements was out flow or not. There were no significant difference of gestation rates with mucus release (31.76%) and without mucus release (24.03%). The pregnancy rates were 39.02% in 10~20mm of follicle size group and 27.08% (p<0.05) in 20~30mm diameter of the follicles. There were not different pregnancy rates between twice inseminated dairy cattle and more than 3 times inseminated cattle. The pregnancy rate was 28.57% under automatic milking system. In contrast, under artificial milking system pregnancy rate was 56.85%. Two systems significantly (p<0.05) were different. These results suggest that pregnancy rates were not effected by physiological system, but mechanical condition.
        4,000원
        16.
        2009.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, we analyzed the effect of silicon oxynitride matrix on the optical properties of Au nanoparticles dispersed on composite film and explored the effectiveness of the silicon in fine tuning the refractive index of the composite film for applications in optical waveguide devices. The atomic fraction of nitrogen in SiOxNy films was controlled by varying the relative flow ratio of nitrogen gas in reactive sputtering and was evaluated optically using an effective medium theory with Bruggeman geometry consisting of a random mixture between SiO2 and Si3N4. The Au nanoparticles were embedded in the SiOxNy matrix by employing the alternating deposition technique and clearly showed an absorption peak due to the excitation of surface plasmon. With increasing nitrogen atomic fraction in the matrix, the surface plasmon resonance wavelength shifted to a longer wavelength (a red-shift) with an enhanced resonance absorption. These characteristics were interpreted using the Maxwell-Garnett effective medium theory. The formation of a guided mode in a slab waveguide consisting of 3 μm thick Au:SiOxNy nanocomposite film was confirmed at the telecommunication wavelength of 1550 nm by prism coupler method and compared with the case of using SiO2 matrix. The use of SiOxNy matrix provides an effective way of controlling the mode confinement while maintaining or even enhancing the surface plasmon resonance properties.
        4,000원
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