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        검색결과 52

        24.
        2018.11 구독 인증기관·개인회원 무료
        In general, the shape of cumulus-oocyte-complexes (COCs) at germinal vesicle (GV) stage is important roles on meiotic maturation of porcine oocyte during in vitro maturation (IVM). Then, mitochondria produce reactive oxygen species (ROS) such as superoxide from electron transport system during oocyte maturation. ROS levels on oocytes are regulated by various antioxidant enzymes in cumulus cells (CCs). However, the effect of mitochondria derived superoxide production from CCs during IVM of porcine oocyte has not been reported. Firstly, we divided groups according to large number of CCs (Grade 1: G1) and small number of CCs (Grade 2: G2). Then, we counted cumulus cells of G1 and G2 oocyte by using haemocytometer. The oocyte maturation rate was significant decreased (p < 0.05) in G2 oocytes than that of G1 oocytes. We measured mitochondria derived superoxide in G1 and G2 COCs by using Mito-SOX staining. Mitochondrial superoxide was higher in G2 COCs than G1 COCs. Then, the mRNA expression levels of antioxidant enzymes (SOD1, SOD2 and PRDX3) in G2 COCs were decreased compared to G1 COCs. To reduce mitochondria derived superoxide, we used Mito-TEMPO as mitochondrial superoxide scavenger. Oocyte maturation rates in both G1 and G2 groups treated with Mito-TEMPO were increased than that of non-treated groups. Mitochondrial superoxide was lower in G1 and G2 groups treated with Mito-TEMPO than that of non-treatment groups. The mRNA expression levels of antioxidant enzymes in G1 and G2 COCs treated with Mito-TEMPO were increased compared to non-treated groups. Based on these findings, we suggest that reduction of mitochondria derived superoxide by Mito-TEMPO assists maturation competence in porcine oocytes.
        25.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to identify the effect of upper thoracic mobilization on cervical alignment in stroke patients with forward head posture. The subject's of this study were two stroke patients with forward head posture and a cervical curve angle (four-line Cobb's method; FLCM) less than 40°. The intervention, central posterior-anterior (PA) mobilization, was applied to the T1-T4 vertebrae (upper thoracic spine) following the Maitland concept. This mobilization was applied three times per week for four weeks. In the results, the cervical curve angle (FLCM) increased for both subject 1 and 2. However, Jochumsen method score was decreased in subject 1, while it was increased in subject 2. These results demonstrate that upper thoracic mobilization had the positive effect on the cervical curve angle but not on Jochumsen method score. These findings suggest that PA mobilization on the upper thoracic spine could correct cervical curve angle measured by FLMC in stroke patients with FHP.
        3,000원
        26.
        2018.05 구독 인증기관·개인회원 무료
        In Sri Lanka, the shoulder in asphalt pavements has been constructed using the materials transported from borrow pit in the iRoad Project due to the low quality of in-situ soils. After excavating 150~200mm thick and 500mm wide shoulder area, the borrow pit materials are placed and compacted according to specifications. The excavated in-situ soils are dumped in designated location. It is estimated that this process of shoulder construction is not economical due to high material transportation cost and can also induce the environmental issues by disposal of in-situ soils. It can also cause distresses such as surface rutting and edge drop-off in soft shoulder section due to bearing capacity failure and off-tracking of vehicle. The heavy rainfall in Sri Lanka can induce severe erosion problem when using the soft shoulder. To improve the strength and durability of pavement shoulders in the iRoad Project, the soil stabilization will be a good alternative to solve the above mentioned problems. The use of in-situ soils with addition of soil stabilizer enables to reduce the construction cost of shoulder section and mitigate the environment issues. The objective of this task is to review the application of soil stabilization method for soft shoulder construction in the iRoad Project. Firstly, the quantitative analysis of soil strength improvement due to soil stabilization was done for soil samples collected from iRoad construction sites. Two types of soils were selected from iRoad Project sites and prepared for soil stabilization testing by the Road Development Authority. Secondly, the appropriate stabilizer was selected at given soil type based on test results. Three different stabilizers, ST-1, ST-2, and ST-3, produced in Korea were used for estimating soil strength improvements. Finally, the optimum stabilizer content was determined for improving shoulder performance. The uniaxial compressive strength (UCS) test was conducted to evaluate the strength of stabilized soil samples in accordance with ASTM D 1633. The use of bottom ash as a stabilizer produced from power plant in Sri Lanka was also reviewed in this task.
        27.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This experiment was carried out to investigate the effect of harvesting time of Italian ryegrass (Lolium multiflorum Lam; IRG) in spring on dry matter (DM) yield. IRG cultivars ‘Kowinearly’ and ‘Greenfarm’ were seeded at 50 kg/ha and grown on rice paddy fields. There was no difference in growth characteristics between both varieties before winter. However, cold tolerance of Kowinearly was higher than that of Greenfarm, as demonstrated by post-wintering growth characteristics. The heading date of both varieties was affected by the spring weather. The IRG was harvested three times at 5-day intervals beginning from 9 May. The DM yield of Greenfarm was 6,306; 7,335; and 8,109 kg/ha, and that of Kowinearly was 7,498; 9,196; and 10,449 kg/ha at the three consecutive harvests. The delay of the harvesting time for 5 and 10 days increased the DM yield of Greenfarm by 16% and 29% and that of Kowinearly by 23% and 39%, respectively, compared to the yield at first harvest (p < 0.05). Therefore, IRG harvest later than early to mid-May is expected to increase productivity. The feed values of Greenfarm were: 12.2% of crude protein (CP), 34.5% of acid detergent fiber (ADF), 57.7% of neutral detergent fiber (NDF), 61.6% of total digestible nutrients (TDN), and 72.3% of in vitro DM digestibility (IVDMD). For Kowinearly, these values were 16.4% of CP, 30.4% of ADF, 52.7% of NDF, 64.9% of TDN and 79.0% of IVDMD.
        4,000원
        28.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study investigated the effects of different seeding rates on growth characteristics and seed productivity of the “Kowinearly” cultivar of Italian ryegrass (Lolium multiflorum Lam.) in paddy fields. Sowing Kowinearly in paddy fields under growing rice at the rates of 20, 30, 40, and 50 kg/ha resulted in seed yields of 1.57, 1.92, 2.06, and 2.09 ton/ha, respectively. Seed yield of Kowinearly was the highest at a seeding rate of 50 kg/ha (p<0.05), at which the cultivar was able to survive in winter and the weed ratio was low. Under these conditions, most growth characteristics such as winter survival (85%), weed ratio (10%), stems per square meter (1,006) were superior than those sown at other seeding rates (p<0.05). In addition, it has been reported that the economic efficiency of the 50 kg/ha seeding rate was higher than that of the other seeding rates.
        2,000원
        29.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The sintering mechanisms of nanoscale copper powders have been investigated. A molecular dynamics (MD) simulation with the embedded-atom method (EAM) was employed for these simulations. The dimensional changes for initial-stage sintering such as characteristic lengths, neck growth, and neck angle were calculated to understand the densification behavior of copper nano-powders. Factors affecting sintering such as the temperature, powder size, and crystalline misalignment between adjacent powders have also been studied. These results could provide information of setting the processing cycles and material designs applicable to nano-powders. In addition, it is expected that MD simulation will be a foundation for the multi-scale modeling in sintering process.
        4,000원
        30.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the densification behavior of rhenium alloys including W-25 wt.%Re and Re-2W-1Ta (pure Re) during sintering. The dilatometry experiments were carried out to obtain the in-situ shrinkage in H2 atmo-sphere. The measured data was analyzed through shrinkage, strain rate and relative density, and then symmetricallytreated to construct the linearized form of master sintering curve (MSC) and MSC as a well-known and straightforwardapproach to describe the densification behavior during sintering. The densification behaviors for each material were ana-lyzed in many respects including apparent activation energy, densification parameter, and densification ratio. MSC witha minimal set of preliminary experiments can make the densification behavior to be characterized and predicted as wellas provide guideline to sinter cycle design. Considering the results of linearized form and MSC, it was confirmed thatthe W-25 wt.%Re compared to Pure Re is more easily densified at the relatively low temperature.
        4,000원
        31.
        2013.04 구독 인증기관·개인회원 무료
        The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is one of the major insect pests of cucumber, Cucumis sativus L. The spatial distribution and occurrence of Aphis gossypii Glover on greenhouse cucumber, Cucumis sativus L., were studied to provide an efficient and reliable sampling plan for its control. A highly clumped pattern was observed among plants (TPL b = 1.63) within a greenhouse. To develop a sampling plan for visual enumeration, leaves within plants were selected by different percentages of leaves (eg., 3rd and 6th, 6th and 9th leaf,…from the bottom of the plant) and then compared the accuracies and efficiencies by relative net precision (RNP). The results indicated that selecting leaves from the bottom of the plant by systemic sampling methods were relatively high as other sampling methods.
        38.
        2018.02 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        In this study, we evaluated the antioxidant activity and anti-inflammatory effects of Abeliophyllum distichum (A. distichum) leaves that were prepared via air-drying. Fresh and air-dried A. distichum leaves were examined via 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assay and measurements of the reducing power. The suppression effects on inflammation of the leaves were analyzed by a western blot and RT-PCR on LPS-induced RAW 264.7 cells. As a result, the antioxidant activity of the fresh leaves was found to be more effective than that of the air-dried leaves. Also, the fresh leaves were more effective in suppressing the protein and mRNA levels of iNOS and COX-2 than the air-dried leaves, thereby indicating the better anti-inflammatory effects. In addition, the contents of phenolic compounds and acteoside were analyzed by high-performance liquid chromatography (HPLC). The results showed that the acteoside content decreased with the use of the air-drying method, while there was no change in the content of phenolic compounds. Therefore, this study indicated that fresh A. distichum leaves potential antioxidant and suppression activities of various factors that are involved in the production of NO, which were found to be better than those of air-dried A. distichum leaves. These biological activities were also found to be independent of the content of phonolic compounds and were assumed to be directly or indirectly related to the content of acteoside.
        39.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        This study was conducted to investigate egg development and larvae morphological development of catfish and to provide basic data to clarify the genetic relationship with Siluriformes fish. The mother fish that was used in this study was caught in the stream of Nakdong River in Uiseong-gun, Gyeongbuk. The temperature range of the breeding was 23.0- 25.0℃ (mean 24.0±1.0℃) and egg size was 1.62-1.70 mm (mean 1.66±0.05, n=30). Eggs of catfish began hatching at 54 hours and 40 minutes after fertilization. Immediately after hatching, the total length of larvae was 3.60-3.65 mm (mean 3.62±0.03, n=5) and had an egg yolk without swimming ability. On the third day after hatching, the larvae at the medium stage was 8.00-8.65 mm (mean 8.32±0.45) in total length, and two pairs of whiskers formed around the mouth were elongated. On the 12th day after hatching, the larvae at the juvenile stage was 16.5-17.0 mm (mean 16.7±0.35) in total length, and the stem of each fin was in the range, and the juvenile at this period was morphologically similar to the mother fish.
        40.
        2014.02 서비스 종료(열람 제한)
        Weir is installed across a river with the general purpose of controlling water level and water intake. Most weirs installed on rivers are fixed weirs and hinder water flow to bring about sedimentation of earth and sand and deterioration of water quality causing destruction of the river environment. Due to such reason, movable weir which can control reservoir capacity has been developed recently and increasingly installed instead of existing fixed weir and various studies have been carried out to develop methods for self-purification effect and reducing sedimentation of earth and sand.<br>From movable weir, rubber dams have been used in many construction sites due to ease of maintenance administration but if the rubber sheet is damaged artificially or by natural disaster, harm is done to the river and high maintenance and repair costs are incurred if neglected for a long time. Also, the life expectancy of a rubber dam is over 30 years so appropriate management and maintenance administration are required to secure safety of the river and proper water procurement.<br>This study developed rubber sheet for improvement of maintenance and repair for rubber dam which is repaired most often for purpose of irrigation and water intake in rivers and such results are as follows.<br>As a result of investigating repair cases when operating rubber dams, repair cases for poor assembly of rubber panel was only about 3.5% of all cases while there were no reported cases of self-defect of rubber dams. From a total of 19 cases of rubber dam repairs, 12 cases (63.2%) were due to external conditions so it is determined that rubber sheet development is needed for improving the durability and safety of rubber dams. Regarding such finding, this study developed a rubber dam enabling bullet resistance/cut resistance by adding aramid sheet when producing rubber sheet and enabled abrasion check by coating the outer layer with colored synthetic rubber.<br>As a result of developing rubber sheet for improving maintenance and repair of rubber dams, durability and safety were found to be better than existing rubber dam while there were effects of ease of maintenance administration and greater economic efficiency as well. For continuous and permanent use of rubber dams, it is determined that systematic research and continuous development are necessary.
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