• 한국수정란이식학회지
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• 제29권2호
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• pp.133-139
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• 2014

$K^+$ channels are involved in the regulation of a variety of physiological functions, including proliferation, apoptosis and differentiation, in mammalian cells. Our previous study demonstrated that the blockage of $K^+$ channels inhibits mouse early embryonic development. This study was designed to identify the effect of $K^+$ channels during bovine embryonic development. $K^+$ channel blockers (tetraethylammonium (TEA), $BaCl_2$, quinine, ruthenium red and fluoxetine) were added to the culture medium during in vitro fertilization (IVF) for 6 h to first identify the short-term effect of these chemicals. Among $K^+$ channel blockers, fluoxetine, which is used as a selective serotonin reuptake inhibitor, significantly increased the blastocyst formation rate by approximately 6% when compared to control. During the in vitro maturation (IVM) of immature oocytes and the in vitro culture (IVC) of embryos, the oocytes and embryos were exposed to fluoxetine for either a short-term (6 h) or a long-term (24 h) to compare the embryonic development in response to exposure time. The 6 h exposure to fluoxetine during IVM did not affect the blastocyst formation rate, but the rate of blastocyst formation was reduced after the 24 h exposure. On the other hand, embryonic development increased approximately 10% in both groups of embryos exposed to fluoxetine for 6 and 24 h during IVC. Taken together, fluoxetine treatment during IVF and IVC, but not IVM, enhances bovine embryonic development. These results suggest that fluoxetine-modulated signals in oocytes and embryos could be an important factor towards enhancing bovine embryonic development.

• 한국추진공학회지
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• 제19권1호
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• pp.9-17
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• 2015

기본 유동 형상은 상대적으로 얇은 중간층이 연료와 공기 사이에 끼어있는 평행 2단 혼합층으로 구성되어 있다. 본 연구는 중간층의 두께 변화에 따른 연소 향상을 수치해석을 통해 조사하였다. 이 경우에, 난류 혼합층에서 열 방출에 의한 효과가 중요하다. 수치해석을 수행하기 위해 완전 보존적인 비정상 2차 시간 정확도의 하부 반복 기법과 2차 총 변화 억제 기법을 k-${\omega}$ 전단응력이동 모델이 결합된 유한체적법과 함께 사용하였다. 다음과 같이 3개의 경우에 대해 해석을 수행하였다. 연료와 공기로 구성된 단일 혼합층, 연료와 공기 사이에 불활성 기체층이 끼어있는 2단 혼합층, 그리고 연료와 공기 사이에 차가운 연료층이 끼어있는 2단 혼합층. 수치해석은 중간 기체층이 1, 2, 4 mm 인 경우에 대하여 수행되었다. 기체층의 총 두께는 4 cm이다. 불활성기체층이 2, 4 mm인 경우와 저온의 연료층이 4 mm인 경우에 단일 혼합층의 경우보다 연소영역이 확대된다.

• 한국유체기계학회 논문집
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• 제8권4호
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• pp.39-47
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• 2005

The present study has been performed to investigate the influences of rectangular fins on heat transfer in an impingement/effusion cooling system with crossflow. To simulate the impingement/effusion cooling system with initial crossflow, two perforated plates are placed in parallel and staggered arrangements with a gap distance of 2 times of the hole diameter. The crossflow passes between the plates, and various rectangular fins are installed on the plates. Reynolds number based on the hole diameter is fixed to 10,000 and the flow rate of crossflow is changed from 0.5 to 1.5 times of that of the impinging jet. A naphthalene sublimation method is used to obtain the heat/mass transfer coefficients on the effusion plate. Also to analyze the flow characteristics, a numerical calculation is performed. When rectangular fins are installed, the flow and heat transfer pattern is changed greatly from the case without fins. In the injection hole region, the jet impinges on effusion plate without deflection and wall jet spreads symmetrically. In the effusion region, the crossflow accelerates due to the decrease of cross-sectional area in the channel. Local heat/mass transfer coefficients are enhanced significantly compared to the case without fins. As the blowing ratio increases, the effect of rectangular fins against the crossflow becomes more significant and then the higher average heat/mass transfer coefficients are obtained than the case without fins. However, the increase of blockage effect gives more pressure loss in the channel.

• 동의생리병리학회지
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• 제24권4호
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• pp.592-597
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• 2010

Cinnamomi Ramulus is one of the medicinal plants that have been used to improve various diseases caused by insufficient blood circulation. This study was performed for the investigation of vasodilation efficacy ethanol extract of Cinnamomi Ramulus (CR). CR exhibited vascular relaxation against phenylephrine (PE, $10^{-6}M$)-, KCl- and NaF-induced contraction in rat thoracic aorta. In addition, its relaxation was endothelium-independent. Treatment of potassium channel blockers such as gilbenclamide (Gli, $10^{-5}M$), tetraethylammonium (TEA, 1 mM) and 4-aminopyridine (4-AP, 0.2 mM) did not effect on the relaxation of CR. The relaxant effects were also not inhibited by pre-treatment of rat aorta with L-NAME ($10^{-4}M$), methylene blue ($10^{-5}M$), indomethacin ($10^{-5}M$), and atropine ($10^{-6}M$). However, nifedipine ($10^{-5}M$), L-type $Ca^{2+}$ channel blocker, in part attenuated the relaxation of CR ($0.2\;mg/m{\ell}$), but SK&F96365 ($3{\times}10^{-5}M$), receptor activated $Ca^{2+}$ channel blocker and 2-APB ($10^{-4}M$), store operated $Ca^{2+}$ channel blocker did not affact dilation of CR. These findings suggest that the endothelium-independent relaxation effect of CR is partly related with inhibition of $Ca^{2+}$ influx via voltage dependent $Ca^{2+}$ channel.

• 대한조선학회논문집
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• 제52권3호
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• pp.236-247
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• 2015

In this paper, the experimental equipments for ventilated supercavitation in cavitation tunnel is constructed and the basic data of ventilated supercavitation regard to the entrainment coefficient and Froude number is fulfilled. The experiments are conducted for the disk cavitator with injecting air and the pressure inside cavity and the shape of cavity are measured. As the entrainment coefficient increases while the Froude number is kept constant, the ventilated cavitation number decreases to a minimum value which decreases no more even with increasing the air entrainment. The minimum value of ventilated cavitation number, caused by the blockage effect, decreases according to increasing the diameter ratio of test section to cavitator. The cavity length is rapidly enlarged near the minimum cavitation number. In low Froude numbers, the cavity tail is floating up due to buoyancy and the air inside the cavity is evacuated from its rear end with twin-vortex hollow tubes. However, in high Froude numbers, the buoyancy effect is almost negligible and there is no more twin-vortex tubes so that the cavity shape becomes close to axisymmetric. In order to measure the cavity length and width, the two methods, which are to be based on the cavity shapes and the maximum width of cavity, are applied. As the entrainment coefficient increases after the ventilated cavitation number gets down to the minimum cavitation number, the cavity length still increases gradually. These phenomenon can be confirmed by the measurement using the method based on the cavity shapes. On the other hand, when the method based on the maximum width of cavity is used, the length and width of the cavity agree well with a semi-empirical formular of natural cavity. So the method based on the maximum width of cavity can be a valid method for cavitator design.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.944-951
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• 2011

본 논문은 ADCP 계측기기 부근에서 음향학적인 그리고 ADCP 계기로 인해 발생하는 흐름의 교란에 기인한 속도 오차에 대한 원인들을 실험 및 수치모의를 통해 고찰한다. 실험실에서의 연구는 선박에 탑재되지 않은 독립된 ADCP에 대해 수행하였고, 수평 및 수직면에서 ADCP에 의해 유발되는 흐름 교란은 ADV를 이용하여 관측하였다. 그리고 ADCP와 ADV의 동시적 측정이 ADCP계측에 있어 추가적인 계측기기 부근의 영향들을 고려하기 위해 수행되었다. 수치모의는 ADCP가 선박에 탑재되었을 때 ADCP 계기 부근에 발생하는 잠재적인 오차에 대해 연구하기 위해 설계되었다. 수치해석 기법 사용된 LES (Large Eddy Simulation)는 선박에 탑재된 ADCP에 작용하는 항력과 계기와 선박의 막음효과에 의해 발생하는 흐름의 교란의 크기와 범위를 모의하였다. 결과로 ADCP에 의해 관측된 속도는 계측기기 하단의 제한된 범위 내에서 일정 정도 오차를 보였고 교란되지 않은 하천의 흐름 조건에 따라 오차가 실질적으로 다르게 나타났다.

• Archives of Pharmacal Research
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• 제18권2호
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• pp.121-128
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• 1995

The role of nitric oxide (NO) in non-adrenegic non-cholinergic (NANC) neurotransmission was studied on circular muscle strips of the dorsal part of the fuinea-pig gastric fundus. In the presence of atropine and guanethidine, a low frequency-dependent relaxsations which were not affected by adrenergic and cholinergic blockage but abolished by tetrodotoxin. $N^G$-nitro-L-arginine (L-NNA), a stereospecific inhibitor of NO-biosynthesis, inhibited the relaxations induced by electrical stiumulations but not the relaxations to exogenous nitric oxide. The effect of L-NNA was prevented by L-arginine, the precursor of the NO biosynthesis but not by its enantiomer, D-arginine. Exgenous administration of No caused concentration -dependent relaxations which showed a similarity to those obtained with electrical simultaion. Hemoglobin, a NOscavenger, abolished the NO-induced relaxations and also markedly reduced those induced by electrical simultaion. The inhibitory effect os hemoglobin was similar to that of L-NNA. Application of ATP caused weak relaxations compared with those to electrical stimultaion, which were unaffected by L-NNA. Exogenously applied vasoactive intestinal polypeptide (VIP) induced concentration-dependent relaxation which was not affected by L-NNA. These results suggest that NO is produced and released mainly as a neurotransmitter from enteric neurons during NANC relaxation induced by low frequencies and short trains of electrical simulation and has a main role in NANC neurotransmission at relaxation induced by these electrical simultaions in the guinea-pig gastric fundus.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제2권1호
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• pp.62-69
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• 2021

This study aimed to verify the suitability of an air quality regulating service for wetland ecosystem service evaluation by investigating the effect of reducing particulate matter (PM) on vegetation in wetlands. We installed tunnel-type experimental plots at Yonghwasil Pond in the National Institute of Ecology and set up the input and output of PM by applying the natural vegetation of the relevant wetlands. We took measurements by replicating four different conditions four times each. The air quality regulating service in each experimental plot was measured based on PM10 concentration; further, the difference between the input and the output concentration of PM passing through the Phragmites australis community tunnel was measured using a light scattering method. For the Phragmites australis community in the outdoor conditions and bare land, the PM concentration was measured with the same specifications as tunnel-type experimental plots without setting up the input and output. For the tunnel-type experimental plots, PM10 concentration was significantly lower in the output than in the input. Furthermore, in the outdoor conditions, a comparison between the Phragmites australis community and bare land showed that the concentration was relatively low in the former than in the latter. This confirmed the PM reducing effect due to the blockage and absorption of PM depending on the growth of Phragmites australis. Based on the results of this study, we assessed the air quality regulating service in wetlands as an evaluation indicator.

• Advances in concrete construction
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• 제14권2호
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• pp.93-102
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• 2022

In this study, limestone powder (LS) and fly ash (FA) were used as powder materials in self-compacting concrete (SCC) in increasing quantities in addition to cement, so that the two powders commonly used in the production of SCC could be compared in the same study. Considering the reduction of the maximum aggregate size in SCC, 10 mm or 16 mm was selected as the coarse aggregate size. The properties of fresh concrete were determined by slump flow (including T₅₀₀ time), V-funnel and J-ring experiments. The experimental results showed that as the amount of both LS and FA increased, the slump flow also increased. The increase in powder material had a negative effect on V-funnel flow times, causing it to increase; however, the increase in FA concretes was smaller compared to LS ones. The increase in the powder content reduced the amount of blockage in the J-ring test for both aggregate sizes. As the hardened concrete properties, the compressive and splitting strengths as well as the modulus of elasticity were determined. Longitudinal and transverse deformations were measured by attaching a special frame to the cylindrical specimens and the values of Poisson's ratio, initiation and critical stresses were obtained. Despite having a similar W/C ratio, all SCC exhibited higher compressive strength than NVC. Compressive strength increased with increasing powder content for both LS and FA; however, the increase of the FA was higher than the LS due to the pozzolanic effect. SCC with a coarse aggregate size of 16 mm showed higher strength than 10 mm for both powders. Similarly, the modulus of elasticity increased with the amount of powder material. Inelastic properties, which are rarely found in the literature for SCC, were determined by measuring the initial and critical stresses. Crack formation in SCC begins under lower stresses (corresponding to lower initial stresses) than in normal concretes, while critical stresses indicate a more brittle behavior by taking higher values.

• 대한임상검사과학회지
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• 제47권4호
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• pp.175-181
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• 2015

알러지성 접촉피부염 유발제인 수은의 독성에 대한 청미래덩굴(Smilax china L.) 추출물의 영향을 조사하기 위하여 배양 NIH3T3 섬유모세포에 여러 농도의 메틸수은(methylmercuric chloride, MMC)을 72시간 동안 처리한 후 이들의 세포독성을 조사하였다. 또한, MMC의 독성에 대한 청미래덩굴 추출물의 보호효과를 항산화 측면에서 조사하여 다음과 같은 결론을 얻었다. MMC는 농도 의존적으로 배양 NIH3T3 섬유모세포의 세포생존율을 유의하게 감소하였으며 $XTT_{50}$값이 100 uM 이하로서 고독성(highly-toxic)인 것으로 나타났다. 또한, MMC의 독성이 항산화제인 vit. E에 의하여 방어됨으로서 MMC의 독성에 산화적 손상이 관여하고 있는 것으로 나타났다. 한편, MMC의 세포독성에 대한 청미래덩굴 추출물의 방어효과에 있어서 청미래덩굴 추출물은 MMC에 의하여 감소된 세포생존율을 유의하게 증가시킴으로서 MMC의 독성을 방어하였다. 또한, 청미래덩굴 추출물은 전자공여능(EDA)을 비롯한 SOD-유사 활성(SLA) 및 지질과산화능(LPA)와 같은 항산화 효과를 나타냈다. 이상의 결과로부터 청미래덩굴과 같은 천연 성분은 산화적 손상과 관련된 염증성 피부질환의 치료를 위한 항산화제로서의 미래 가능한 천연소재라고 생각된다.