• 한국해양공학회지
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• 제13권2호통권32호
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• pp.129-137
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• 1999

The time of the onset of double-diffusive convection in time-dependent, nonlinear concentration fields is investigated theoretically. The initially quiescent horizontal fluid layer with a uniform temperature gradient experiences a sudden concentration change from below, but its stable thermal stratification affects concentration effects in such way to invoke convective motion. The related stability analysis, including Soret effect, is conducted on the basis of the propagation theory. Under the linear stability theory the concentration penetration depth is used as a length scaling factor, and the similarity transform for the linearized perturbation equations. The newlly obtained stability equations are solved numerically. The resulting critical time to mark the onset of regular cells are obtained as a function of the thermal Rayleigh number, the solute Rayleigh number, and the Soret effect coefficient. For a certain value of the Soret effect coefficient, the stable thermal gradient promote double-diffusive convective motion.

• Steel and Composite Structures
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• 제32권3호
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• pp.293-304
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• 2019

In the present paper, the element free Galerkin (EFG) method is developed for geometrically nonlinear analysis of deep beams considering small scale effect. To interpret the behavior of structure at the nano scale, the higher-order gradient elasticity nonlocal theory is taken into account. The radial point interpolation method with high order of continuity is used to construct the shape functions. The nonlinear equation of motion is derived using the principle of the minimization of total potential energy based on total Lagrangian approach. The Newmark method with the small time steps is used to solve the time dependent equations. At each time step, the iterative Newton-Raphson technique is applied to minimize the residential forces caused by the nonlinearity of the equations. The effects of nonlocal parameter and aspect ratio on stiffness and dynamic parameters are discussed by numerical examples. This paper furnishes a ground to develop the EFG method for large deformation analysis of structures considering small scale effects.

• Geomechanics and Engineering
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• 제33권5호
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• pp.519-528
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• 2023

In this paper, we present the results of an experimental study on the effect of polymer support fluid on shaft resistance of offshore bored piles. A series of pullout tests were performed on bored piles installed under various boundary conditions considering different types of grounds and support fluids, and a range of support fluid exposure times. Contrary to previous studies concerning onshore bored piles, a time dependent effect of polymer fluid on shaft resistance was observed in all ground types. The adverse effect of polymer support fluid on the shaft resistance, however, was considerably less than bentonite support fluid for a given exposure time. No significant reduction in shaft resistance was evident when limiting the exposure time of the polymer support fluid to the side wall of the borehole within 2-3 hours. The degree to which the polymer fluid affects shaft resistance seemed to vary with the ground type. A proper consideration should be given to the time dependent effect of polymer fluid on shaft resistance of bored piles installed in offshore construction environment to limit its adverse effect on the pile performance. The practical implications of the findings are discussed.

• The Korean Journal of Physiology and Pharmacology
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• 제24권6호
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• pp.545-553
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• 2020

Aripiprazole is a quinolinone derivative approved as an atypical antipsychotic drug for the treatment of schizophrenia and bipolar disorder. It acts as with partial agonist activities at the dopamine D2 receptors. Although it is known to be relatively safe for patients with cardiac ailments, less is known about the effect of aripiprazole on voltage-gated ion channels such as transient A-type K⁺ channels, which are important for the repolarization of cardiac and neuronal action potentials. Here, we investigated the effects of aripiprazole on Kv1.4 currents expressed in HEK293 cells using a whole-cell patch-clamp technique. Aripiprazole blocked Kv1.4 channels in a concentration-dependent manner with an IC₅₀ value of 4.4 μM and a Hill coefficient of 2.5. Aripiprazole also accelerated the activation (time-to-peak) and inactivation kinetics. Aripiprazole induced a voltage-dependent (δ = 0.17) inhibition, which was use-dependent with successive pulses on Kv1.4 currents without altering the time course of recovery from inactivation. Dehydroaripiprazole, an active metabolite of aripiprazole, inhibited Kv1.4 with an IC₅₀ value of 6.3 μM (p < 0.05 compared with aripiprazole) with a Hill coefficient of 2.0. Furthermore, aripiprazole inhibited Kv4.3 currents to a similar extent in a concentration-dependent manner with an IC₅₀ value of 4.9 μM and a Hill coefficient of 2.3. Thus, our results indicate that aripiprazole blocked Kv1.4 by preferentially binding to the open state of the channels.

• Korean Journal of Acupuncture
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• 제33권4호
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• pp.194-203
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• 2016

Objectives : The aim of this study was to observe the dose-dependent effects of bee venom (BV) pharmacopuncture on the serious ankle sprain in rats. Methods : The grade III ankle sprain was produced by surgically damaging the lateral ligaments complex of Sprague-Dawley rats. BV pharmacopuncture with the different doses($5{\mu}g/kg$, $10{\mu}g/kg$, $50{\mu}g/kg$) were treated on the different acupoints(GB34, GB39 and GB42) of the affected hind limb, respectively. By measuring foot weight bearing force ratio(FWBFR), the pain levels by ankle sprain and the pain recovery for 7 days were observed under BV pharmacopuncture on each acupoint. Results : In the normal and ankle sprained rat, the BV single administration decreased FWBFR in a dose - dependent pattern. The higher the BV dose, the higher the pain resulted in the normal and the sprained ankles. Especially, the dose - dependent effects of BV resulted in the most pronounced decrease in FWBFR in GB34. The recovery of FWBFR was shown at the low dose($5{\mu}g/kg$) BV and the effect was most remarkable in the BV of GB34, but the others showed no recovery effect compared with the control group. Conclusions : BV pharmacopuncture does not exhibit analgesic effects in acute phase of ankle sprain. However, the recovery of ankle sprain was more effective than the natural recovery in the case of low dose of BV repeated over time. Considering this, it is presumed that it would be important to select appropriate clinic guidelines for acute phase of ankle sprain.

• Human Ecology Research
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• 제53권6호
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• pp.641-654
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• 2015

This study identifies and tracks changes gender differences in adolescent users' problematic online behavior. This study used Korea Youth Panel Survey (KYPS), which has tracked respondents over 7 years, with self-control theory and social learning theory applied as a theoretical framework. The model included individual-level variables such as self-control and respondent's experience of problematic behavior (offline), as well as socialization variables such as the number close friends who engaged in problematic offline behavior, parent-child relationships, and parental monitoring. Dependent variables included problematic online behavior, unauthorized ID use (ID theft) and cyberbullying (cursing/insulting someone in a chat room or on a bulletin board). Control variables consisted of academic performance, time spent on a computer, monthly household income, and father's educational attainment. Random and fixed effects models were performed by gender. Results supported self-control theory even for the within-level analysis (fixed effects models) regardless of gender, while social learning theory was partially supported. Only peer effects were found significant (except for unauthorized ID use) among girls. Year dummy variables showed significant negative associations; however, academic performance and time spent using computers were significant in some models. Father's educational attainment and monthly household income were found insignificant, even in the random effects models. We also discuss implications and suggestions for future research and policy makers.

• 한국수자원학회논문집
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• 제42권6호
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• pp.445-455
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• 2009

본 논문에서는 연구대상 지역의 150 mm 주철 상수관로의 첫 번째 파손으로부터 일곱 번째 파손사건에 대한 비례 위험모형을 구축하였다. 모형의 구축과정에서 공변수의 위험률에 대한 비례위험 가정을 검사하여 이를 위배할 경우 시간종속형 공변수로 모형화하였다. 그 결과 첫 번째 파손에 대해서는 관로의 제원 및 연결 방식과 급수인구가, 그리고 두 번째 파손 사건에 대해서는 급수인구의 영향이 시간에 따라 변하는 것으로 나타났다. 각 생존시간군의 기저위험률에 대한 분석으로부터 첫 번째와 두 번째 파손에 대해서는 대체적으로 파손 위험률이 시간에 따라 계속해서 증가하는 것으로 나타났으며, 세 번째 파손으로부터 일곱번째 파손사건에 대해서는 파손 위험률이 감소하다가 시간이 지나면 증가하는 욕조 모양으로 추정되었다. 또한 시간과 파손횟수에 따른 기저위험률의 변화 및 각 생존시간군의 중간생존시간으로부터 연구대상 상수관로들은 파손횟수가 증가할수록 전반적인 관로의 상태가 악화되는 것으로 판단된다. 추정된 공변수의 회귀계수와 위험비율을 이용하여 관로파손에 미치는 인자와 그 시간적 영향에 대하여 분석하였으며, 구축된 모형의 이탈잔차를 이용하여 모형의 적합도를 검증하였다.

• 동의생리병리학회지
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• 제19권1호
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• pp.124-129
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• 2005

Resveratrol, a phytoalexin found at high levels in grapes and in grape products such as red wine, has been reported to possess a wide range of biological and pharmacological activities including anti-oxident, anti-inflammatory, anti-mutagenic, and anti-carcinogenic effects, but its molecular mechanism is poorly understood. In this study, we examined the effects of resveratrol on lipopolysaccharide (LPS)-induced growth inhibitory activity and cell growth-regulatory gene products in astroglioma C6 cells to elucidate its possible mechanism for anti-cytotoxicity. It is shown that LPS induced time-dependent growth inhibition and morphological changes of C6 cells, which were recovered by pre-treatment with resveratrol. The anti-proliferative effect of LPS was associated with the induction of tumor suppressor p53 and cyclin-dependent kinase (Cdk) inhibitor p21 (WAF1/CIP1) expression assessed by RT-PCR and Western blot analysis in time-dependent manner in C6 cells. In addition, the pro-apoptotic Bax expression was also up-regulated in LPS-treated C6 cells without alteration of anti-apoptotic Bcl-2 and Bcl-XL expression. However, resveratrol significantly inhibited LPS-induced p53, p21 and Bax levels, suggesting that the modulation of p53, p21 and Bax levels could be one of the possible pathways by which resveratrol functions as anti-cytotoxic agent.

• Environmental Analysis Health and Toxicology
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• 제27권
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• pp.10.1-10.7
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• 2012

Objectives: In recent years, a number of structurally diverse Histone deacetylase (HDAC) inhibitors have been identified and these HDAC inhibitors induce growth arrest, differentiation and/or apoptosis of cancer cells in vitro and in vivo. This study aimed at investigating the antitumor activity of newly synthesized HDAC inhibitor, 3-(4-dimethylamino phenyl)-N-hydroxy-2-propenamide (IN-2001) using human breast cancer cells. Methods: We have synthesized a new HDAC inhibitor, IN-2001, and cell proliferation inhibition assay with this chemical in estrogen receptor-positive human breast cancer MCF-7 cells. Cell cycle analysis on MCF-7 cells treated with IN-2001 was carried out by flow cytometry and gene expression was measured by RT-PCR. Results: In MCF-7 cells IN-2001 showed remarkable anti-proliferative effects in a dose- and time-dependent manner. In MCF-7 cells, IN-2001 showed a more potent growth inhibitory effect than that of suberoylanilide hydroxamic acid. These growth inhibitory effects were related to the cell cycle arrest and induction of apoptosis. IN-2001 showed accumulation of cells at $G_2$/M phase and of the sub-$G_1$ population in a time-dependent manner, representing apoptotic cells. IN-2001-mediated cell cycle arrest was associated with HDAC inhibitor-mediated induction of CDK inhibitor expression. In MCF-7 cells, IN-2001 significantly increased $p21^{WAF1}$ expression. Conclusions: In summary, cyclin-dependent kinase (CDK) induced growth inhibition, possibly through modulation of cell cycle and apoptosis regulatory proteins, such as CDK inhibitors, and cyclins. Taken together, these results provide an insight into the utility of HDAC inhibitors as a novel chemotherapeutic regime for hormone-sensitive and insensitive breast cancer.

• 대한한의학회지
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• 제19권1호
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• pp.66-88
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• 1998

This study was performed from March to September 1997 on 95 healthy students to observe the effects of acupuncture at Hap-kok (LI4) according to the meridian and qi-xue(氣血) phenomenon of oriental medicine's theory. Skin temperature on the Hap-kok (LI4) and Chun-Choo (ST25) were measured by D. 1. T. I. (Digital Infrared Thermograph Imaging) before acupuncture stimulation and 1min, 10 min after acupuncture stimulation. 1. In healthy students, the left and right mean temperature of LI4 and ST25 was $29.04\;^{\circ}C,\;29.12\;^{\cir}C\;and\;30.29\;^{\circ}C,\;30.22\;^{\circ}C$ respectively. 2. In control group, the time dependent changes for 10 min of LI4 and ST25 were $-0.32\;^{\circ}C,\;-0.36\;^{\circ}C\;and\;-0.5\;^{\circ}C,\;-0.46\;^{\circ}C$ respectively, however, the thermal differences of both sides LI4 and ST25 were not changed for 10 min. 3. In acupuncture stimulation of both sides LI4, the time dependent changes of ST25 were $-0.13\;^{\circ}C,\;-0.06\;^{\circ}C$, and the thermal differences of both sides ST25 were reduced, but not changed significantly. In acupuncture stimulation of right side LI4, the time dependent changes of LI4 were $-0.1\;^{\circ}C,\;-0.32\;^{\circ}C$ respectively, and the thermal differences of both sides LI4 were increased more than control, but not significantly. Also, that of ST25 were changed by $-0.69\;^{\circ}C,\;-0.63\;^{\circ}C$ respectively, but not significantly. 4. In acupuncture stimulation group, it was classified following the thermal differences of both sides LI4 and ST25, and the effects of acupuncture were observed by changes of classification. The acupuncture of both sides LI4 results in temperature of the left side ST25 to be high after acupuncture. The acupuncture of right side LI4 results in increased ratio of the left side higher than right LI4. The above results indicates that D. I. T. I. was a useful method to observe follow-up the effects and changes by acupuncture stimulation on objective evaluation of phenomenon for the meridian system. Thus, acupuncture on LI4 affects to thermal changes of ST25 and LI4, but exact examination of thermal changes on ST25 will have to be.