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        검색결과 5

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Estrus in cows can be detected through vaginal electrical resistance or conductivity. However, there are no studies measuring vaginal electrical resistance in Hanwoo cows. This study aims to measure the vaginal electrical resistance value in Hanwoo cows and compare it with estrus and ovulation. Methods: Vaginal electrical resistance values of 73 Hanwoo cows were measured before and after estrus at the Gyeongsangbuk-do Livestock Research Institute. Measurements were taken on days -6, -3, -2, -1, 0, 1, 2, 3, and 6 of artificial insemination. Large follicles and ovulation were confirmed using transvaginal ultrasonography. Results: The vaginal electrical resistance averaged 225.6 ± 6.3 Ω days before the artificial insemination date, decreasing until the day of artificial insemination. The average vaginal electrical resistance was 163.7 ± 4.6 Ω on the date of artificial insemination, and 188.8 ± 4.3 Ω one day after artificial insemination, when large follicles were observed. In addition, on the 6th day after artificial insemination, the vaginal electrical resistance averaged 231.4 ± 5.5, which was similar to the 6th day before artificial insemination (222.5 ± 6.3). Transvaginal ultrasonography showed that most of the cows ovulated one day after artificial insemination. Conclusions: The accuracy of estrus is high if the vaginal electrical resistance is measured for cows with confirmed estrus, making is a potentially useful for determining the timing of artificial insemination.
        4,000원
        2.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mercury and its compounds are globally managed chemicals as risks to the human body and ecosystem. It mainly enters the human body through ingestion of seafood, especially, methylmercury causes serious diseases such as central nervous system (CNS) disorder and renal dysfunction. In this study, total mercury (Hg) and methyl mercury (MeHg) were determined in seafood (16 species, n = 97) commonly consumed in Daejeon, using a gold amalgamation method. The average concentration (Hg/MeHg mean ± S.D. (minimum–maximun) mg/kg) of total Hg and MeHg in the samples was as follows; Fish 0.038 ± 0.058 (0.004 – 0.272) / 0.028 ± 0.047 (N.D. – 0.236), Crustacea 0.023 ± 0.021 (0.003 – 0.078) / 0.016 ± 0.018 (N.D. – 0.055), Mollusks 0.015 ± 0.015 (0.002 – 0.056) / 0.008 ± 0.013 (N.D. – 0.040). The concentration of MeHg in seafood were significantly correlated with total Hg concentration (p<0.001). The species with the highest average concentration of Hg was the Korean rockfish, but there was no sample that exceeded the maximum residual limit. The total %provisional tolerable weekly intake (%PTWI) value of MeHg for all of the samples was 3.76%, compared with the JECFA’s reference value, which indicates that there is almost no health risk from heavy MeHg intake through the consumption of seafood distributed in Daejeon.
        4,000원
        3.
        2021.03 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        The content of harmful materials was investigated for coffee beans sold in Daejeon. Total 79 samples were analysed and 213 residual pesticides and 2 heavy metals were analysed simultaneously by GC-MS/MS, GC-NPD, GC-ECD, LC-MS/MS and ICP-MS. The instrumental method was validated with limit of detection (LOD), limit of quantification (LOQ), the linearity of standard curves. LOD of the residual pesticides was between 0.0003 to 0.0021 mg/kg, LOQ of the residual pesticides was between 0.0008 to 0.0064 mg/kg. LOD of the heavy metals was between 0.0077 to 0.0079 μg/kg, LOQ of the heavy metals was between 0.0233 to 0.0239 μg/kg. The linearity correlation coefficient for the calibration curve was between 0.9929 to 0.9999 and the recovery rate was between 95.4% to 106.1%. According to the monitoring of residual pesticides and heavy metals, no pesticide was detected in all coffee bean samples. 88.6% (70 samples) of analysed total 79 coffee beans contained at least 1 heavy metal but there was no sample which exceeded the maximum residual limit. Risk assessment was also carried out based on the content of heavy metals detected in coffee beans. The carcinogenic risk assessment to heavy metals showed that all cancer-risk (CR) values were below 10–6 and it meant that the CR due to heavy metals intake was evaluated as safe. The non-carcinogenic risk assessment to heavy metals showed that all hazard index (HI) were below 1, which was considered acceptable at the current level of exposure. The %PTWI values of lead and cadmium for 55 roasted coffee bean samples were 0.09% and 0.04% respectively, compared with the reference values. This results indicate that there is almost no health risk from heavy metal intake through the consumption of coffee beans in circulation in Daejeon.
        4,600원
        4.
        2018.12 KCI 등재 서비스 종료(열람 제한)
        아세틸 헥사펩타이드 8 (AH8)은 보톡스 메커니즘을 응용한 주름 개선 펩타이드 소재로, 보톡스의 타겟인 synatosomal-associated protein 25 (SNAP25) N말단 서열을 모방하여 개발되었다. 주름 개선 효과가 보고되고 있지만 큰 분자량과 친수성 성질에 의하여 피부 흡수는 잘 되지 않는다는 문제가 있다. 따라서 피부 보습 성분 중에서 AH8의 피부 흡수를 증가시켜 줄 수 있는 물질을 탐색하였는데, 히알루론산(HA)이 AH8의 피부 흡수를 증가시켰다. 형광물질로 표지한 AH8만 MicropigⓇ skin 에 발라주면 대부분 각질을 투과하지 못하고 각질층에 존재하였다. 반면, HA를 함께 도포한 경우에는 각질층을 투과하여 표피, 진피로 흡수된 AH8가 증가하는 것을 형광 이미지 분석을 통해 확인했다. 특히 5 kDa 저분자량 HA가 500 kDa, 2000 kDa HA보다 피부 흡수를 더 많이 증가시켰다. HA가 피부 각질층에 미치는 영향을 푸리에변환 적외 분광법(Fourier-transform infrared spectroscopy, FTIR)으로 분석해보니, 고분자량 HA는 각질 수분 함량을 증가시키고, 저분자량 HA는 지질층의 유동성을 증가시키는 경향성이 있었다. 따라서 HA는 AH8의 피부 흡수를 증가시켜 주름 개선 효과를 향상시켜 줄 수 있을 것으로 기대된다.
        5.
        2012.11 KCI 등재 서비스 종료(열람 제한)
        Recently, development of underwater robot has actively been in progress in the world as ROV(Remotely Operator Vehicle) and AUV(Autonomous Unmmanded Vehicle) style. But KIOST(Korea Institute of Ocean Science and Technology), beginning in 2010, launched the R&D project to develop the robot, dubbed CRABSTER(Crab + (Lob)ster) in a bid to enhance the safety and efficiency of resource exploration. CRABSTER has been designed to be able to walk and swim with its own legs without screws. Among many research subjects regarding CRABSTER, optimal swimming patterns are handled in this paper. In previous studies, drag forces during one period with different values for angle of each joint were derived. However kinematics of real-robot and fluid-dynamics are not considered. We conducted simulations with an optimization algorithm for swimming by considering simplified fluid dynamics in this paper. Drag-coefficients applied to the simulation were approximated values calculated by CFD(Computational Fluid Dynamics : Tecplot 360, ANSYS). In addition, optimized swimming patterns were applied to a real robot. The experiments with the real robot were conducted in circumstances in the water. As a result, when the experiments were carried out in the water, a regular pattern of drag force output came out depending on the movement of the robot. We confirmed the fact that the drag forces from the simulation and the experiment has a high similarity.