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        검색결과 4,101

        641.
        2020.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This present study was conducted to investigate protective effect of discontinuous Percoll gradient containing alpha-linolenic acid (ALA) before freezing process on viability, acrosome damage, mitochondrial activity, and oxidative stress of frozen-thawed boar spermatozoa. The separation of spermatozoa by discontinuous Percoll gradient was performed by different concentration of Percoll solution (45/90%) containing ALA combined with bovine serum albumin (BSA), and collected sperm in each Percoll layer was cryopreserved. To evaluate viability, acrosome damage, mitochondrial activity, and reactive oxygen species (ROS) level of frozen-thawed sperm, flow cytometry was used. Morphological abnormalities were observed under light microscope. In results, viability of sperm from 90% Percoll layer was higher than control and 45% Percoll group (p < 0.05). Separated sperm in 90% Percoll layer had lower acrosome damage and morphological abnormalities than control as well as viability, whereas 45% Percoll group was higher (p < 0.05). Similar with acrosome damage and abnormalities, mitochondrial activity was slightly enhanced and the population of live sperm with high ROS level was decreased by 90% Percoll separation, however, there was no significant difference. Supplementation of 3 ng/mL ALA into Percoll solution increased sperm viability and decreased population of live sperm with high ROS compared to control (p < 0.05). In conclusion, discontinuous Percoll gradient before freezing process could improve efficiency of cryopreservation of boar sperm through selection of sperm with high freezing resistance, and supplement of ALA during Percoll gradient might contribute suppression of ROS generation via stabilizing of plasma membrane during cryopreservation.
        4,000원
        642.
        2020.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this research work was to know ovarian dynamics and pregnancy rate of cyclic Murrah buffalo cows with induced estrus by administration of prostaglandin F2α (PGF2α) and timed artificial insemination (TAI) with frozen thawed semen. A total of 31 female buffaloes were selected for the study. The buffalos having matured CL observed by ultrasonography were given one intra muscular injection of cloprostenol 500 μg and TAI was performed using frozen thawed semen of Indian Murrah buffalo bull. Results showed that 90.32% (significantly, at p < 0.05) cows explore the sign of heat after injection of PG and 67.85% (significantly, at p < 0.05) cows were become pregnant out of 28 inseminated (TAI) cows. In the 28 inseminated (TAI) cows, average number of smaller and larger size of follicles were non-significantly (p > 0.05) higher at day 3 post PG injection, but the medium size of follicles was non-significantly (p > 0.05) higher at PG injection. At day 3 post PG injection the diameter of follicles was significantly (p < 0.05) higher, but the diameter of CL was significantly (p < 0.01) lower compared at PG injection. At PG injection the diameter of largest follicle was non-significantly differences (p > 0.05) in between pregnant and non-pregnant cows. But at day 3 post PG injection it was significantly (p < 0.01) higher in pregnant cows compared to non-pregnant cows. The number of small, medium, and large follicles at PG injection and at day 3 post PG injection were non-significantly (p > 0.05) difference in between pregnant and non-pregnant buffalo cows. Finally, it is concluded that the CL was effectively regresses and induced the sign of heat in buffalo cows and after AI the cows were become pregnant with significant rate. The study will help to the veterinarian and researcher to know the efficacy of PG injection and AI for reproductive efficiency in buffalo cows.
        4,000원
        643.
        2020.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 우라늄 폐촉매 처리 공정에서 발생하는 우라늄 함유 폐기물 대상으로 유리-세라믹 매질 구조의 대형 디스크 소결체 형태로 제작 시, 최종 제작된 소결체의 비등방향 수축 특성 및 변형율 변화를 연구하였다. 본 연구에서는 최대 직경 40 cm를 갖는 다양한 크기 원형 디스크 형태와 원형 디스크의 1/4 크기의 부채꼴 형 소결체를 제작하여 이들의 비등방성 수축 특성을 평가하였다. 60 MPa 압력하에서 만들어지는 성형체는 소결 시 성형체의 크기 및 형태에 관계없이 높은 등방성 수축하였다. 제조된 전체 소결체에 대한 비등방성율은 평균 1.6%이었고 이때 평균 부피 감용율은 37.4% 이었다. 이러한 결과 로부터 국내에서 발생한 우라늄 폐촉매를 처리하기 위한 공정에서 발생하는 우라늄 함유 폐기물은 대형 디스크 형태의 유리-세라믹 매질 형태로 고형화함으로써 높은 안정성과 부피감용 효과를 가지며 200 L 드럼에 포장될 수 있음이 확인되었다.
        4,200원
        644.
        2020.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Molten salt solutions consisting of eutectic LiCl-KCl and concentrations of samarium chloride (0.5 to 3.0 wt%) at 500℃ were analyzed using both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The CV technique gave the average diffusion coefficient for Sm3+ over the concentration range. Equipped with Sm3+ diffusion coefficient, the Randles-Sevcik equation predicted Sm3+ concentration values that agree with the given experimental values. From CV measurements; the anodic, cathodic, and half-peak potentials were identified and subsequently used as a parameter to acquire EIS spectra. A six-element Voigt model was used to model the EIS data in terms of resistance-time constant pairs. The lowest resistances were observed at the half-peak potential with the associated resistance-time constant pairs characterizing the reversible reaction between Sm3+ and Sm2+. By extrapolation, the Voigt model estimated the polarization resistance and established a polarization resistance-concentration relationship.
        5,200원
        645.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated the effects of precipitates and oxide dispersoids on the high-temperature mechanical properties of oxide dispersion-strengthened (ODS) Ni-based super alloys. Two ODS Ni-based super alloy rods with different chemical compositions were fabricated by high-energy milling and hot extrusion process at 1150℃ to investigate the effects of precipitates on high-temperature mechanical properties. Further, the MA6000N alloy is an improvement over the commercial MA6000 alloy, and the KS6000 alloy has the same chemical composition as the MA6000 alloy. The phase and microstructure of Ni-based super alloys were investigated by X-ray diffraction and scanning electron microscopy. It was found that MC carbide precipitates and oxide dispersoids in the ODS Ni-based super alloys developed in this study may effectively improve high-temperature hardness and creep resistance.
        4,000원
        647.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Geomunoreum Lava Tube System, declared as a UNESCO World Heritage Site, has a unique natural ecosystem. The information available about this ecosystem, which contains lava caves with secondary carbonate speleothems, is sparse. Hence, extensive research is warranted for establishing a conservation standard. We commenced microbial research on the system and have been studying the microorganisms coating the lava tube wall to acquire fundamental information for understanding the lava cave ecology of Jeju Island. Samples were collected from yellow-colored walls in six caves that are part of the system―the Bengdwi, Utsanjeon, Bukoreum, Manjang, Gimnyeong, and Yongcheon caves. This study focused on yellow walls as it is the most easily distinguished color. According to previous studies, the color of cave walls is attributed to microorganisms or their components. To determine whether the yellow mats from the Jeju lava tube walls are caused by microorganisms, we examined samples at the microscopic scale, by staining mats and analyzing bacterial isolates from glitter particles. As a result, we found that the yellow walls of lava tubes are comprised of microbial mats.
        4,200원
        648.
        2019.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        New triple tungstate phosphors NaPbLa(WO4)3:Yb3+/Ho3+ (x = Yb3+/Ho3+ = 7, 8, 9, 10) are successfully fabricated by microwave assisted sol-gel synthesis and their structural and frequency upconversion (UC) characteristics are investigated. The compounds crystallized in the tetragonal space group I41/a and the NaPbLa(WO4)3 host have unit cell parameters a = 5.3927(1) and c = 11.7961(3) Å, V = 343.05(2) Å3, Z = 4. Under excitation at 980 nm, the phosphors have yellowish green emissions, which are derived from the intense 5S2/ 5F4 → 5I8 transitions of Ho3+ ions in the green spectral range and strong 5F5 → 5I8 transitions in the red spectral range. The optimal Yb3+:Ho3+ ratio is revealed to be x = 9, which is attributed to the quenching effect of Ho3+ ions, as indicated by the composition dependence. The UC characteristics are evaluated in detail under consideration of the pump power dependence and Commission Internationale de L'Eclairage chromaticity. The spectroscopic features of Raman spectra are discussed in terms of the superposition of Ho3+ luminescence and vibrational lines. The possibility of controlling the spectral distribution of UC luminescence by the chemical content of tungstate hosts is demonstrated.
        4,000원
        649.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Chironomid communities are indicators of water pollution because of their ability to thrive under freshwater conditions. However, it is difficult to distinguish between chironomid larvae based on morphology. DNA barcoding, based on nucleotide sequences of marker genes, can be used to identify chironomid larvae. Samples of chironomid larvae were collected from Gwangju Stream and Pungyeongjeong Stream, tributaries of the Yeongsan River in South Korea. We identified 3 subfamilies, 13 genera, 16 species, and 1 cryptic species. There were 7 genera and 10 species from the subfamily Chironominae, 5 genera and 5 species from subfamily Orthocladiinae, 1 genus and 1 species from subfamily Tanipodinae, and the cryptic chironomid species of the family Chironomidae. There were 21 individuals from, 7 species and 1 cryptic species from the Gwangju Stream and 24 individuals, belonging to 10 species from the Pungyeongjeong Stream. The only species detected in both streams was Cricotopus bicinctus. The relationship between water quality and the species detected was difficult to explain, but the number of species showed a tendency to increase at sites where water quality was poor. Additional investigations and studies are needed to understand the relationship between water quality and the chironomid species occurring in these two streams.
        4,000원
        650.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        농촌진흥청 국립원예특작과학원에서는 2017년 빅립 형태의 분홍색계 팔레놉시스 ‘Lovely Angel’을 개발하였다. 2009년 백색 팔레놉시스 P. ‘Timonthy’와 빅립을 가지는 분홍색 P. World Class ‘Big Foot’을 모본과 부본으로 교배하였다. 2013년 생육이 우수하고 화색, 화형, 꽃대수 등 개화 특성이 우수한 ‘09056-12’를 개체선발하여 기내 화경배양을 통해 증식하였다. 2014년부터 2017년에거쳐 1차, 2차 특성검정을 통해 품종의 안정성과 균일성을 확인하여 ‘Lovely Angel’을 육성하였다. 이 품종은 밝고 선명한 보라빛 분홍색(RHS, PVG81C)을 띄며, 줄 무늬를 가지고 있고 설판이 큰 빅립 형태가 특징적이다. 안아피는 형태의 꽃은 길이와 폭이 각각 6.1, 5.6cm이며, 1개의 꽃대에 20.6개의 소화가 착생하여 꽃 수가 비교적 많이 달리고, 꽃대 길이는 31.8cm 이다. ‘Lovely Angel’는 생육시 잎은 반하수로 자라며 길이는 18.7cm, 폭은 6.8cm이다. 신품종인 ‘Lovely Angel’은 소형 분화용으로 이용 가능할 것이다.
        4,000원
        651.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Embryos produced with serum show the alterations in their ultrastructure, impaired compaction, abnormal blastulation, aberrant mRNA expression profiles and large calf syndrome with greater incidences of stillbirths and deaths after birth. The aim of the present study was to describe in vitro embryo production by analyzing embryo production, fetal production and pregnancy rate in free-serum medium. The OPU-IVP data used in this study from 2016. Approximately, sixteen cows (Hanwoo), which belonged to the Institute of Gyeongsang National University, were used. Two experimental group is used in this study. Serum groups were conducted in March to July and free-serum group was conducted in September to December. The recovered cumulus-oocyte complexes were morphologically classified to four grades based on the compaction of cumulus cells layers and homogeneity of the cytoplasm. The number of oocyte was significantly greater in serum groups than that in free-serum groups (29.61 ± 0.63 vs. 15.6 ± 0.62; p < 0.05). Between serum and free-serum groups indicate that average of 1st and 2nd grade oocytes were no difference (2.38 ± 1.67 vs. 2.38 ± 1.48; p > 0.05), but number of 3rd and 4th grade oocytes were greater in serum groups than that in free-serum groups (7.31 ± 7.64 vs. 5.60 ± 6.29; p < 0.05). Embryo cleaved competence was higher in rate in free-serum groups than that in serum groups (62.1% vs. 58.3; p < 0.05). However, blastocyst developmental rate was no difference between serum and free-serum groups (33.1% vs. 43.5%; p < 0.05). 986 recipients were used for embryo transfer. Pregnancy rate was indicated that between serum and free-serum group was no difference (54.6% vs. 56.3%; p < 0.05). In conclusion, we developed the free-serum system for production of in vitro bovine embryos in order to meet the developmental and qualitative requirements for large scale commercial use.
        4,000원
        652.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        긴바수염반날개[Atheta (Bessobia) occulta (Erichson)] (신칭)를 한반도에서 처음으로 보고한다. 이 종에 대한 재기재, 체형사진 및 식별형질에 대한 삽화를 제시한다.
        4,000원
        653.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study evaluated the repellent activity and the improvements in egg production and mortality rate on laying hens infested with poultry red mites (PRM) administered with a mixture of Korean traditional herbal methanolic extracts (CHE, Foeniculum vulgare : Sophora flavescens : Cinnamomum cassia : Glycyrrhiza glabra = 1:1:1:1, w/w/w/w). PRM numbers per laying hens in CHE-0.5 administered with CHE 0.5 kg/ton feed were significantly decreased compared to those in Non-CHE (control) during overall experimental periods (1st week post-treatment, p<0.05; 2nd week post-treatment, p<0.01; 3rd-4th week post-treatment, p<0.001). In CHE-1.0 administered with CHE 1.0 kg/ton feed, PRM numbers were significantly decreased compared to those in Non-CHE during the whole experimental periods (1st week post-treatment, p<0.01; 2nd-4th week post-treatment, p<0.001). After administration of CHE for 4 weeks, egg production and mortality rate in CHE-0.5 and CHE-1.0 were significantly improved compared to those in Non-CHE (p<0.05). In addition, hematological and blood biochemical parameters in all CHE-treated groups were insignificantly different compared to those in Non-CHE. This study showed that CHE (0.5 and 1.0 kg/ton feed) had a repellent activity on PRM in laying hens and effects on the improvement in egg production and mortality rate of laying hen. CHE could be an effective and safe candidate for the control of PRM and the improvement in egg production and mortality rate of laying hens.
        4,000원
        654.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was investigated the synergistic antibacterial effects from the combination of sulfamethazine (SMZ) and tiamulin (SMT) against Salmonella Typhimurium (S. Typhimurium) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae) isolated from pigs. Minimum inhibitory concentrations (MICs) and fractional inhibitory concentration (FIC) index were determined for 10 bacteria from 13 swine farms in Gyeongsangnam province by the National Committee for Clinical Laboratory Standards broth microdilution procedure. Antimicrobial agents tested included SMZ, tiamulin and SMT. Against S. Typhimurium and A. pleuropneumoniae, the MIC ranges of SMZ, tiamulin and SMT were 125-500, 15.625-62.5 and 15.625-62.5 μg/mL, respectively. In addition, the FIC index ranges of SMT against S. Typhimurium and A. pleuropneumoniae were 0.19-0.38 and 0.19-0.62, respectively. In conclusion, SMT has a high antibacterial activity against S. Typhimurium and A. pleuropneumoniae, then the combination may be applied for the treatment of swine diseases caused by S. Typhimurium and A. pleuropneumoniae.
        4,000원
        655.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Growth factors and cytokines play an important role in delaying skin aging. However, there has been no animal stability test reported for them yet. In the present study, we examined the plausibility of Growth factor and Cytokine Mixtures (GCM) as a cosmetic ingredient by assessing skin irritation and ocular irritation for hypersensitivity using New Zealand white rabbits. Skin safety study was performed to evaluate the potential toxicity of GCM based on the irritation test. For the irritation test, GCM was applied to the rabbit skin, and no adverse reaction, such as erythema and edema, had been observed from the exposed skin sites. In the ocular irritation test, the treatment of GCM did not cause any adverse reaction on rabbit eyes, including cornea, iris, and conjunctiva tissues. From the results, both tests proved that GCM makes no irritable reaction on skin and eye mucous membrane of rabbit. Hence, it may be suggested that GCM can be safely applied as a cosmeceutical ingredient without causing any significant hypersensitivity reaction.
        4,000원
        656.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the use of L1(English) by L2(Korean) learners’ interaction with their native-speaking conversation partners from a sociocultural perspective, using the lens of conversation analysis. The data included 64 hours of recorded interactions of 16 conversation pairs of nonnative learners of Korean and their native conversation partners as well as learners’ diary entries. Findings gleaned from qualitative analysis of learners’ use of their L1 (i.e., English) during native-nonnative pair interactions outside the classroom showed that the overall use of L1 by L2 learners found to be facilitative of their L2 learning. The results proposed a model of L2 learners interaction with their conversation partners that attempted to link learner’s use of L1 and their L2 proficiency, and concluded that learners’ interactions played a key role in improving L2 learners’ language proficiency. In addition, pedagogical recommendations based on the research findings were proposed.
        6,400원
        657.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study examines the extent to which key competence and learning competence in particular are promoted in the high school English classes attended by Chinese students. Eight hundred and thirty five college freshmen at a comprehensive four-year university in Jilin Province were surveyed on their experiences in high school English classes. In part 1 of the survey, we found that high school English instruction in China tends to be exam-focused rather than emphasizing the development of key competences. In part 2 of the survey, we found that three aspects of learning competence – attitudes toward learning English, meta-cognitive awareness concerning one’s own English learning, and knowledge about English language instruction – are not consistently instilled in high school English classes. Virtually no differences between ethnic majority and minority students were observed in survey. We believe that because English instruction in Chinese high schools is exam-oriented so that instructors do not have enough time to enhance learning competences. Our conclusion is that reform of instructional methods needs to include greater attention to the aspects of learning competence.
        5,800원
        658.
        2019.12 구독 인증기관 무료, 개인회원 유료
        The shipping revolution was introduced due to development and improvement that occurred in the shipping industry. Until now, changes in the shipping industry are still ongoing to improve their services, especially by introducing mega ships to transport cargoes. Thence, the shipping revolution stimulates seaport to comply with the requirements for a new mega ship. Therefore, this study was conducted to determine the external environment factors that contribute to the challenge of Malaysia Port towards the shipping revolution. Firstly, the external environmental factors that challenge Malaysia Port towards shipping revolution are identified by using the PESTEL analysis; which are political, economic, social, technological, environmental, and legal factors. Then, these identified factors are ranked by using Analytic Hierarchy Process (AHP) to determine the priority external environment factors that contribute to the challenge of Malaysia Port towards shipping revolution. Data were collected by using pair wise comparison questionnaire which is qualitative method. The questionnaire consists two sections; there are demographic information and PESTEL factors. Thereafter, the data were analysed by AHP analysis. The results shown that the top three priority external environmental main factors that contribute to the challenge of Malaysia Port towards shipping revolution which are economic, technology and environment. Then, the top three sub factors are economic growth, digitalization and reduce emission. As a conclusion, these factors can influence the Malaysia Port towards shipping revolution and need priorities attention. Whereas the economic growth will monetary support shipping and port revolution, digitalization can reduce cost and increase efficiency, and reduce emission towards environmental friendly. Consequently, the findings will raising awareness and as a blueprint to government and port operators during development and expansion of harbour towards shipping revolution.
        4,000원
        659.
        2019.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Whole body-electromyostimulation (WB-EMS) is widely used for the rehabilitation and recovery of patients with various neuromusculoskeletal disorders. Objects: To objectively measure changes in lower extremity and abdominal muscles after sit-to-stand dynamic movement training using WB-EMS. Methods: A total of 46 healthy adults (23 experimental and 23 control subjects) performed sit-to-stand exercise; the experimental group with WB-EMS, and the control group without WB-EMS. The muscle activity of the lower extremity, and the muscle thickness of the lower extremity and abdominal muscles were measured before and after the intervention. Results: In terms of electromyographic activity, there was a significant interaction effect for the rectus femoris (RF) muscle (F=30.212, p=.000). With regards to ultrasonographic imaging, the muscle thickness of the RF muscle had a significant interaction effect at the muscle contraction ratio (F=8.071, p=.007). The deep abdominal muscles, such as the transverse abdominal (TrA) and internal oblique (IO) muscles, also showed significant interaction effects at the muscle contraction ratio (F=5.474, p=.024, F=24.151, p=.000, respectively) Conclusion: These findings suggest that WB-EMS may help to improve the muscular activity of the RF muscle, and the muscle thickness of the RF muscle and deep muscles such as the TrA and IO muscles.
        4,200원