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        검색결과 1,028

        201.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the heat flow characteristics of wave heat exchanger was investigated by being applied to the white smoke reduction system. Through numerical analysis, the heat transfer and flow characteristics of the wave heat exchanger with the change of inlet condition of air-side and water-side were analyzed. To investigate the temperature, the absolute humidity, heat transfer rate, pressure drop and turbulence characteristics of the wave heat exchanger, the simulation analysis was conducted by using the commercial computational fluid dynamics software (Solidworks Flow Simulation) under uniform flow conditions. As the inflow rate of air decreased and the inflow temperature of water increased, the heat transfer coefficient of the wave heat exchanger decreased. When the experimental conditions of water-side were the same, the air outlet temperature and absolute humidity of the wave heat exchanger increased with increasing inflow rate of air. To reduce the white smoke, the air outlet temperature and absolute humidity of the wave heat exchanger must be reduced. Therefore, the lower the air velocity and the water inflow temperature into the wave heat exchanger, the more effective it is.
        4,000원
        202.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES :Conductive and convective heat transfer simulations for an asphalt mixture were made by using discrete element method (DEM) and similarity principle.METHODS :In this research, virtual specimens composed of discrete element method particles were generated according to four different predetermined particle size distribution curves. Temperature variations of the four different particles for a given condition were estimated and were compared with measurements and analytical solutions.RESULTS :The virtual specimen with mixed particles and with the smallest particle show very good agreement with laboratory test results and analytical solutions. As particle size decreases, better heat transfer simulation can be performed due to smaller void ratio and more contact points and areas. In addition, by utilizing the similarity principle of thermal properties and corresponding time unit, analytical time can be drastically reduced.CONCLUSIONS :It is concluded that the DEM asphalt mixture specimens with similarity principle could be used to predict the temperature variation for a given condition. It is observed that the void ratio has critical effect on prediction of temperature variation. Comparing the prediction for a 4 mm particle specimen with a mixed particle specimen, it is also concluded that predicting the mixed particle specimen temperature is much more efficient considering the number of particles that are directly associated with computational time in DEM analysis.
        4,000원
        203.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Embryo transfer (ET) could be a relevant tool for genetic improvement programs in horses similar to those already underway in other species and produce multiple foals from the same mare in one breeding season. However, there have been no reports describing equine embryo transfer performed in Korea. In the present study, we performed an equine embryo collection and transfer procedure for the first time. We examined the embryo collection and pregnancy, size of embryo during the incubation period after collection, and progesterone (P4) and estradiol-17ß (E2) concentrations in mare’s serum at embryo collection and transfer. A total of 16 donors responded to estrus synchronization; estrus was induced in 12 donors and 4 recipients, and artificial insemination was successful in 10 donors and six blastocysts were collected from donors. Of these blastocysts, we monitored the size of blastocysts for 3 day during incubation and transferred 2 blastocysts to a recipient, with 1 successful pregnancy and foal achieved. The dimensions of equine embryo at day 7 to day 9 were 409 μm, 814 μm and 1,200 μm. The serum P4 and E2 concentrations were 7.91±0.37 ng/μL and 45.45±12.65 ng/μL in the donor mare, and 16.06±3.27 ng/μL and 49.13±10.09 ng/μL in the recipient mare.
        4,000원
        204.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As a part of the effort to improve post-transfer survival rate of embryos in Korean black goats, a technique for laparoscopic uterine transfer of blastocysts was carried out. A total of 26 transferrable embryos (morula to expanded blastocysts) were transferred to 13 recipient goats via transabdominal laparoscopic method. In consequence of our hormone protocol, 65% of the recipients (13/20) were found to have synchronized estrus. After confirmation of corpus luteum in each recipient goat, a Babcock laparoscopic forceps was inserted into the lower abdominal cavity to hold a uterine horn and fasten it near the peritoneum without causing injury. Then 7.5cm long 16G IV catheter was inserted directly into the uterine lumen through the abdominal wall. After removal of the stylet of the IV catheter, the embryo transfer tube (identical in size to the stylet and loaded with blastocysts) was inserted into the uterine lumen through the catheter to unload the embryos. Of the 13 estrus synchronized recipients, 9 were transferred blastocysts and 4 were transferred molurae (2 embryos in each recipient) in uterine ipsilateral to the ovary with corpus luteum. Four of the 9 recipients which blastocysts were transferred using this method has been confirmed pregnant (44.4% pregnancy rate).
        4,000원
        205.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a direct contact membrane module was manufactured to be used in a pilot scale membrane distillation process to treat 3 m3/day of the digestate produced from anaerobic digestion of livestock manure. In order to investigate the performance of the membrane module, permeate flux was measured with and without spacer inside the module under various condition of temperature difference and cross flow velocity (CFV) through the membrane surfaces. Flux recovery rate after chemical cleaning was also investigated by applying three different cleaning methods. Additionally, thermal energy consumption was theoretically simulated based on actual pilot plant operation conditions. As results, we observed flux of the module with spacer was almost similar to the theoretically predicted value because the installation of spacer reduced the channeling effect inside the module. Under the same operating condition, the permeate flux also increased with increasing temperature difference and CFV. As a result of chemical in-line cleaning using NaOCl and citric acid for the fouled membranes, the recovery rate was 83.7% compared to the initial flux when NaOCl was used alone, and 87% recovery rate was observed when only citric acid was used. However, in the case of using only citric acid, the permeate flux was decreased at a rapid rate. It seemed that a cleaning by NaOCl was more effective to recover the flux of membrane contaminated by the organic matter as compared to a cleaning by citric acid. The total heat energy consumption increased with increasing CFV and temperature difference across the membrane. Thus, further studies should be intensively conducted to obtain a high permeate flux while keeping the energy consumption to a minimum for a practical application of membrane distillation process to treat wastewater.
        4,000원
        206.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to review the relationship between managerial system and incremental innovation, and the mediating effect of knowledge transfer in small business. In order to verify and achieve the purposes mentioned above, questionnaire data were gathered and analysed from 255 enterprise managers in western Kangwon-do province. Empirical survey's findings are as follows; First, CEO's support and education/training appeared to be positively related with knowledge transfer. Second, managerial system and knowledge transfer appeared to be positively related with incremental innovation. Third, knowledge transfer had mediating effect on the relationships of CEO's support-incremental innovation and education/training-incremental innovation.
        4,300원
        208.
        2017.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 공공연구기관의 기술이전시 연구자가 이전기술의 사업화 과정에 참여 하여 이전된 기술의 발명 과정에서 습득한 노하우를 전수하는 것이 사업화 성공에 미치는 영향 을 분석하였다. ETRI(Electronics and Telecommunications Research Institute)의 2014년 기술 이전 계약건중 설문조사에 응답한 204건을 분석대상으로 하였으며, 종속변수가 범주형 변수일 때 특정 사건의 발생(성공 또는 미성공) 가능성을 예측하는 통계기법인 로지스틱 회귀분석을 이용하였다. 실증분석 결과, 기술이전이후 사업화 지원의 강도가 이전된 기술의 사업화 성공 여부와 양의 상관관계가 있는 것으로 나타났다. 본 연구는 공공연구기관중 최대 규모의 기술이 전 및 사업화지원 실적을 보유하고 있는 ETRI의 사례를 통한 실증분석 결과라는데 의의가 있으며, 이를 통해 정부 및 공공연구기관의 중소기업 지원 정책 방향에 대한 시사점을 제시한다.
        5,700원
        209.
        2017.05 구독 인증기관·개인회원 무료
        Somatic cell nuclear transfer (SCNT) is the technique which generates embryos by transferring diploid nucleus into an enucleated oocyte, it has produced specific animals successfully in a variety of species. However, the developmental capacity of SCNT embryos is still relatively lower than that of embryos produced in vivo. Oocyte is a kind of lipid rich cells, its quality limits the efficiency of embryo production. L-carnitine is a co-enzyme facilitating the transportation of long chain fatty acids across the inner mitochondria membrane where fatty acids are used for generating adenosine triphosphate (ATP) via beta-oxidation. It also has antioxidant actions which may protect mitochondrial membranes and DNA against damage induced by reactive oxygen species (ROS). Whether L-carnitine is functional in bovine SCNT embryos are unknown. Therefore, the objective of this study was to examine the effects of L-carnitine on oocyte maturation and developmental competence of subsequent SCNT embryos. L-carnitine was supplemented during IVM, then intracellular ROS and GSH levels, mitochondrial activity, gene expression of COCs were analyzed at the end of IVM. SCNT embryos were produced subsequently, apoptosis detection and gene expression evaluation were performed in blastocysts. In the results, treatments with 1.5 mM and 3 mM L-carnitine significantly improved maturation rates (P<0.05). Treatments with 3 mM L-carnitine effectively induced improvement in nuclear maturation, intracellular GSH levels and mitochondrial activity, as well as a reduction in intracellular ROS levels (P<0.05). mRNA levels of CPT1A, ACAA1, ACAA2, AREG, EREG, SOD1, GPX4, GLUT1 and CDC2 transcripts were effectively up-regulated by 3 mM L-carnitine treatments (P < 0.05). Similarly, 3mM L-carnitine induced an increase in blastocyst developmental rates and an improvement in blastocyst quality (P<0.05). Our study indicates that L-carnitine treatment during IVM improves oocyte nuclear maturation and subsequent SCNT embryo development.
        210.
        2017.05 구독 인증기관·개인회원 무료
        Introduction Porcine embryonic stem cells (pESCs) derived from cloned embryos might be a useful animal model in biomedical research, however, establishment of cloned pESCs is difficult by its incomplete nuclear reprogramming. Here, we report the improved development competence of porcine cloned embryos by vitamin C (VC) supplement to establish the pESCs. Materials and Methods Slaughterhouse-derived oocytes were in vitro matured for 44h and parthenogenetic and cloned embryos were produced using matured oocytes. Both of embryos were cultured for 6 days in PZM-5 media and development rates were examined. Four different concentration of VC (0, 25, 50, 100, and 200 μg/ml) was supplemented in IVM and IVC media and preimplantation developments in the 5 groups were compared in both of embryos Results and Discussion In the cleavage rates of IVM group, significantly higher rate was shown in 50 mg/ml group than other groups (84.5 ± 0.6% vs. 69.8 ± 5.5, 75.7 ± 1.8, 80.4 ± 0.2, 72.4 ± 0.1%; P<0.05), respectively. Significantly higher rates of blastocyst development also were shown in 50 mg/ml group than other groups (27.0 ± 2.0% vs. 20.4 ± 1.4, 22.1 ± 1.3, 23.7 ± 1.2, 19.6 ± 1.3%; P<0.05), respectively. In the cleavage rate of IVC group, non-significantly different with each group (84.0 ± 1.3, 86.7 ± 1.0, 88.4 ± 1.4, 76.7 ± 3.0, 64.6 ± 4.4; P<0.05). In the blastocyst rate of IVC group, significantly higher rate was shown in 25mg/ml and 50 mg/ml group than other groups (22.3 ± 1.7, 23.8 ± 1.7% vs. 19.1 ± 1.3, 15.9 ± 1.0, 5.8 ± 1.5%; P<0.05) In conclusion, supplement of 50μg/ml of VC in IVM and IVC media enhanced the development of porcine parthenogenetic embryos and these results will be a helpful information in the development of porcine cloned embryos and derivation of its embryonic stem cells.
        211.
        2017.05 구독 인증기관·개인회원 무료
        Polo-like kinase 1 (plk1) shows multiple events of somatic cell and mammalian oocyte division. In mice, Plk1 distributes to the centromeres from prophase to anaphase and compose spindle apparatus at different stages of mitosis in spindle organization. Somatic cell nuclear transfer (SCNT) has a number of advantages however it is difficult to apply to basic or translational researches due to its low cloning efficiency. The causes of this low cloning efficiency are unclear. However, they are attributed to the cumulative results of several biological and technical factors. In this study, a biological factor plk1 was investigated. B6D2F1 mice (7–8 weeks old) were superovulated with 10 IU of pregnant mare’s serum gonadotropin and 9 U of human chorionic gonadotropin (HCG) 48 hr later. The oocytes were then collected 14 hr after HCG injection and cultured on potassium simplex optimized medium (KSOM). The plk1-specific inhibitor BI2536 was used to understand the influence of plk1. The 2-cell stage embryos were assessed by fluorescence immunoassay. In consequence, all BI2536-treated embryos failed in the first mitotic division which showed plk1 have critical role in the first mitotic division of the mouse embryo. SCNT requires enucleation of oocyte and injecting a donor cell into the enucleated cytoplast. In this process, a respectable amount of plk1 that co-localize with nucleus may be removed together. Fluorescence immunoassay and qPCR were used to monitor the change of plk1 level during SCNT. There was significant difference between the control and enucleated embryos in the level of plk1. In all division-failure 2-cell embryos, incorrect positioning of plk1 was found. Taken together, this results demonstrate that plk1 is critical for successful mitotic division of mouse SCNT 1-cell embryos.
        212.
        2017.05 구독 인증기관·개인회원 무료
        The nature of molecular mechanisms governing embryo development is largely unknown, but recent reports have demonstrated that proper execution of programmed cell death is crucial for this process. The main objective of this study is to examine the mode of programmed cell death during nuclear transfer embryos development in porcine. In particular, the relative employment of two major pathways in programmed cell death; e.g. apoptosis (type I) and autophagy (type II) was compared. Oocytes use in the study was matured in vitro in the presence of 10% FBS maturation medium. After nuclear transfer embryos were cultured for each programmed cell death control factor [Cysteamine(Cyst : 0.4mM), 3-methyladenine(3MA : 2.5mM) and Rapamycin(RP : 100nM)] in TCM-199 medium supplemented with 0.1% BSA. In this study results of among the blastocysts development in 3MA; PCNA, MAP1LC3A and ATG5 RNA gene expression level increased in the order of IVF<Cyst < 3MA < RP. However Casp-3 and TNF-r RNA gene expression level decreased in the order of IVF < 3MA and RP< Cyst. The expression of mTOR showed a pattern opposite to that of MAP1LC3A. That is, its expression was the lowest in Cyst group. And next experiments analysis of MMP expression patterns. Analysed this MMPs enzyme activation to evaluate the effectiveness of high quality brastocyst culture in porcine. In this results of the enzymatic activity of MMP-2 and MMP-9 was assessed in culture, the level of active MMP-9 was higher expression in the medium of each 3MA and RP treatment group, with the level of another treatment group being relatively higher. These results suggest that the autophagy activation culture medium is more effective for stable and innovative nuclear transfer embryos development.
        214.
        2017.05 구독 인증기관 무료, 개인회원 유료
        Establishment of the Adherens junction (AJ) and Tight junction (TJ) are important steps in terms of morphological formation during preimplantation develoment. Particularly, TJ complex is crucial for cavitation in blastocyst. So far, many TJ protein/genes are revealed. However, the biological function and regulation of TJ were not elucidated during post implantation. We depleted several TJ and TJ associated genes using RNA interference, and examined preimplantation development with TJ. We tested functionality of paracellular sealing to determine integrity of TJ formation and examined TE differentiation indirectly using outgrowth assay in vitro. We observed defect of paracellular permeability in the TJ related genes knockdown(KD) blastocyst and abnormal outgrowth. Particularly, trophoblast cells were not stretched out in the KD groups. Finally, we did embryo transfer using the TJ genes KD and control blastocysts into surrogate mothers. We found lower of the implantation rates/ maintenance of pregnancy in the TJ KD groups (less than 40%) than in the controls (about 80%). In conclusion, TJ integrity is can be used as a selective marker for developmentally competent embryos and successful pregnancy.
        4,000원
        217.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ablative material in a rocket nozzle is exposed to high temperature combustion gas, thus undergoes complicated thermal/chemical change in terms of chemical destruction of surface and thermal decomposition of inner material. Therefore, method for conjugate analysis of thermal response inside carbon/phenolic material including rocket nozzle flow, surface chemical reaction and thermal decomposition is developed in this research. CFD is used to simulate flow field inside nozzle and conduction in the ablative material. A change in material density and a heat absorption caused by the thermal decomposition is considered in solid energy equation. And algebraic equation under boundary layer assumption is used to deduce reaction rate on the surface and resulting destruction of the surface. In order to test the developed method, small rocket nozzle is solved numerically. Although the ablation of nozzle throat is deduced to be higher than the experiment, shape change and temperature distribution inside material is well predicted. Error in temperature with experimental results in rapid heating region is found to be within 100 K.
        4,000원
        219.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated to the heat transfer performance of coating nano-structure with various shapes and patterns on the heat transfer surface. As a result of the measurement of the 3D nano shape, it was confirmed that the roughness generally increases when the adhesive is sprayed on the coating surface and finished durability experiment. In the case of TEOS adhesive, the roughness increased by 0.074 ㎛, 0.012 ㎛ and 0.015 ㎛, and the contact angle decreased 12.64°, 1.31°, 9.84° at the coating time of 120 seconds, 180 seconds and 240 seconds, respectively. In the case of PVA adhesive, the roughness increased by 0.069 ㎛, 0.056 ㎛ and 0.03 ㎛, and the contact angle decreased 2.85°, 4.82°, 6.96° at the coating time of 120 seconds, 180 seconds and 240 seconds, respectively. In the case of DGEBF adhesive, the roughness increased by 0.042 ㎛, 0.053 ㎛ and 0 ㎛, and the contact angle decreased 0.81° at the coating time of 120 seconds, increased 4.82°, 6.96° at the coating time of 180 seconds and 240 seconds, respectively. As a result, the durability tends to decrease as more nano-structures are deposited, and 3D nano shapes, contact angles and SEM photographs showed that the performance of the PVA adhesive was superior among the three adhesives.
        4,000원
        220.
        2017.03 KCI 등재 구독 인증기관·개인회원 무료
        현행 여신전문금융업법 제19조 제1항 및 제4항은, 신용카드가맹점으 로 하여금 ‘신용카드 결제를 거절하는 행위’, ‘신용카드회원을 불리하게 대우하는 행위’, ‘가맹점수수료를 신용카드회원에게 부담시키는 행위’를 금지하고 있다. 동 조항은, 국민의 금융편의를 도모하고, 거래의 투명화 및 이를 통한 탈세방지를 위하여 도입된 것으로 그간 충분한 효과를 보 여주었으나, 동 조항의 남용을 통한 가맹점 피해, 신용카드를 발급받지 못하는 저신용자에게 비용이 전가되는 등 경제적 정의에 반한다는 점, 사회전체의 거래비용이 증가한다는 점 등의 부작용이 발생하고 있다. 이 러한 부작용을 최소화하며 입법목적을 달성할 수 있도록 입법적 보완작 업이 필요하다. 예를 들어, 거액 결제와 같은 경우에는 동 조항의 적용을 배제하는 방안, 가맹점수수료 정도의 합리적인 범위내의 차별을 허용하 는 방안, 현금결제와의 차별만 금지하고 다른 전자지급결제수단과의 차 별은 허용하는 방안 등을 논의해 볼 필요가 있다. IT산업의 발달과 더불어, 과거 전통적 결제수단이었던, 현금, 어음, 수 표, 계좌이체, 신용카드 외에, 계좌이체지급결제대행, 신용카드지급결제대 행, 직불카드(직불전자지급수단), 선불카드(선불전자지급수단), 전자화폐 의 방법이 등장하였다. 이들 결제수단 중 최근 서민을 위한 결제방식으 로 부상하고 있는 계좌이체지급결제대행의 경우, 신용카드를 발급받을 수 없는 저신용자도 이용이 가능할 뿐 아니라, 탈세방지 목적에도 부합 하고, 간편결제 방식의 적용에 따라 그 이용도 매우 편리하게 되었다. 그 러나 계좌이체지급결제대행의 경우에도 제19조 제1항 및 제4항을 적용 하게 되면, 신용카드(혹은 신용카드지급결제대행 방식)에 비하여 회원 유치 경쟁력이 떨어지게 되어, 그 확산에 어려움이 있다. 현금결제 고객 과는 달리 지급결제대행업체에 의한 별도의 용역제공 행위가 있음을 감 안하여 현행 여신전문금융업법 하에서도 제19조 제1항 및 제4항의 형식 적 적용을 배제하는 적극적 해석이 필요하다.