• 동의생리병리학회지
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• 제24권3호
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• pp.476-483
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• 2010

The present study was performed to investigate the putative anxiolytic-like effects of the aqueous extract of the roots of Scrophularia buergeriana (SB-W) using elevated plus-maze (EPM) and hole-board apparatus in mice. SB-W was orally administered at doses of 50, 100, 200 or 400 mg/kg to ICR mice, 1 h before the behavioral evaluation. Control group were administered with an equal volume of saline, and positive control group with buspirone (2 mg/kg, i.p.). The administration of SB-W significantly increased the percentage of time spent in open arms and entries into the open arms of the EPM compared with saline-treated control group (P < 0.05). Futhermore, those anxiolytic-like activities of SB-W were antagonized by flumazenil (a $GABA_A$ antagonist, 10 mg/kg), but not by WAY-100635 (a 5-$HT_{1A}$ antagonist, 0.3 mg/kg). Moreover, there were no changes in the locomotor activity and myorelaxant effects in any group compared with saline-treated control group. In the hole-board test, the administration of SB-W (200 and 400 mg/kg) significantly increased the number of head-dipping compared with saline-treated control group (P < 0.05). Therefore, these findings suggest that Scrophularia buergeriana promotes the anxiolytic-like activity mediated by GABAergic nervous system in mice.

• Biomolecules & Therapeutics
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• 제15권3호
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• pp.175-181
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• 2007

Zizyphi Spinosi Semen (ZSS), a traditional Chinese folk medicine, has been used for treatment of insomnia and anxiety. This experiment was performed to investigate the anxiolytic-like effect of methanol extract of ZSS (MEZSS) in mice by using the experimental paradigms of anxiety and compared with that of a known anxiolytic, diazepam. In the elevated plus-maze test, it showed that MEZSS (100 mg/kg, p.o.) and diazepam (2.0 mg/kg, p.o.) increased the percentage of time spent on the open arms and the number of open arms entries. MEZSS (50, 100 and 200 mg/kg, p.o.) and diazepam (0.5 mg/kg, p.o.) significantly increased the number of head dips compared with that of control group in the hole-board test. However, MEZSS has no effect on decreasing the locomotor activity, while diazepam (2.0 mg/kg, p.o.) significantly inhibited locomotor activity. MEZSS did not decrease the strength force in the grip strength test, either. In addition, GABAergic involvements were also investigated to understand the possible mechanisms. $GABA_{A}$ receptors subunits and glutamic acid decarboxylase (GAD) were not over expressed, compared with that of the saline group. We also found that MEZSS did not increase chloride influx in cultured cerebellar granule cells. It is concluded that MEZSS might have anxiolytic-like effects, but these effects might not be mediated by GABAergic transmission.

• 한국수자원학회논문집
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• 제56권10호
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• pp.603-617
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• 2023

본 연구는 포말대 흐름의 난류특성에 대한 이해를 목표로 한다. 포말대 흐름을 재현하기 위해 이중 댐-붕괴 파랑생성법이 제시되었다. 기존 단일 댐-붕괴 실험과 비교하여 이중 댐-붕괴 실험은 두 개의 수문의 개방 시간을 조절하여 처오름과 처내림의 다양한 상호작용을 구현할 수 있다. 수치모형으로는 OpenFOAM의 overInterDyMFoam이 활용되었다. overInterDyMFoam은 밀도가 다른 두 유체(i.e., 공기, 물)의 경계면 추적기법과 동격자 및 중첩 격자 기법을 결합한 모형이다. 질량보존 및 운동량 방정식으로는 𝜅-𝜖 난류모형이 결합된 이차원 Reynolds-Averaged Navier-Stokes 모형이 채택되었다. 수치모형실험 결과는 수리모형실험의 수심 및 흐름 방향 유속 시계열과 비교하여 정확도가 검증되었다. 난류 운동 에너지 분포특성을 확인하여 각 흐름 단계(i.e., 처오름, 처내림, 흐름의 상호작용)의 난류 진화 특성을 고찰하였다.

• 한국안전학회지
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• 제32권6호
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• pp.40-45
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• 2017

Chemical accidents generated during maintenance, repair, and normal operation, such as dispersion, fire, and explosions, can cause massive losses like a 2012 hydro fluorine leak in Gumi, South Korea. Since this accident, many researches have studied physical mitigation systems. However, due to many difficulties including potential costs and lack time, it is really hard for many companies to install mitigation systems without prior knowledge. Thus, the efficacy of mitigation system should be evaluated. This study assesses a dike design considering the fluid velocity at an open hole when a leakage accident occurs. It is assumed that leakage materials follow a free fall motion. Throughout case studies, a current KOSHA guide for a dike design was evaluated and new guidelines handling various conditions were proposed.

• Structural Engineering and Mechanics
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• 제62권6호
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• pp.739-748
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• 2017

Notches such as slots are typical geometric features on mechanical components that promote fatigue crack initiation. Unlike for components with open hole type notches, there are no conventional treatments to enhance fatigue behavior of components with slots. In this work we evaluate the viability of applying laser shock peening (LSP) to extend the fatigue life of 6061-T6 aluminum components with slots. The feasibility of using LSP is evaluated not only on damage free notched specimens, but also on samples with previous fatigue damage. For the LSP treatment a convergent lens was used to deliver 0.85 J and 6 ns laser pulses 1.5 mm in diameter by a Q-switch Nd: YAG laser, operating at 10 Hz with 1064 nm of wavelength. Residual stress distribution was assessed by the hole drilling method. A fatigue analysis of the notched specimens was conducted using the commercial code FE-Safe and different multiaxial fatigue criteria to predict fatigue lives of samples with and without LSP. The residual stress field produced by the LSP process was estimated by a finite element simulation of the process. A good comparison of the predicted and experimental fatigue lives was observed. The beneficial effect of LSP in extending fatigue life of notched components with and without previous damage is demonstrated.

• 한국안전학회지
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• 제33권5호
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• pp.35-41
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• 2018

Chemical accidents generated during maintenance, repair, and normal operation, such as dispersion, fire, and explosions, can cause massive losses like a 2012 hydro fluorine leak in Gumi, South Korea. Since this accident, many researches have studied physical mitigation systems. However, due to the lack of potential costs and time, it is really hard for many companies to install mitigation systems without prior knowledge. Thus, the efficacy of mitigation system should be evaluated. This study assesses a dike design considering the fluid velocity at an open hole when a leakage accident occurs. It is assumed that leakage materials follow a free fall motion. Throughout case studies, a current KOSHA guide for a dike design was evaluated and new guidelines handling various conditions were proposed.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.359-365
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• 2000

Port facilities and marine structures used in marine environment were encountered to corrosion damages because of the influence of $Cl^-$. Generally, to protect these accidents, mainly applied anti-corrosion paint and epoxy coating. But it was still remained erosion-corrosion damage such as impingement erosion, cavitation erosion, deposit attack. There was needs to develope the new coating materials to protective those corrosion damages. This paper, polyester glass flake, vinylester glass flake lining and epoxy coating for SS were investigated electrochemical tests and cavitation erosion test for corrosion behaviour under sea water. The main results obtained are as follows, 1) Surface of epoxy coating appear erosion pin hole but surface of polyester glass flake and vinylester glass flake lining do not appear erosion pin hole after impingement-cavitation erosion test in sea water. 2) Weight loss of polyester glass flake and vinylester glass flake lining do not occur after impingement-cavitation erosion test in sea water. 3) Corrosion current density of polyester glass flake lining less drained than epoxy coating and substrate under corrosion potential.. 4) Corrosion current density of vinylester glass flake lining with three coating less drained than that of polyester glass flake lining with two coating.

• Advances in Traditional Medicine
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• 제6권1호
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• pp.34-38
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• 2006

The hot water extract of the seeds of Vernonia anthelmintica Kuntze (Compositae) in a dose of 10 ml/kg body weight of mice, showed significant analgesic activity on the hot plate analgesic method throughout the 4 h experimental period. The hole cross scores and the climbing out scores are of lower than the control animals. The hot water extract reduced the defecation in hole board study and significantly reduces the exploratory ambulation and head dipping behaviour. The seed also showed significant depressant activity on the exploratory ambulation of the open field scores. The drug decreased the spontaneous locomotion activity on brick-chip displacement method up to 45 min and also showed the ability to lessen the amphetamine induced hyperactivity up to 20 min. But it didn't show any effect on pentobarbital induced sleeping time test. The extract reduced gastrointestinal motility.

• 한국재료학회지
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• 제30권12호
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• pp.660-665
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• 2020

Silicon heterojunction solar cells can achieve high conversion efficiency with a simple structure. In this study, we investigate the passivation characteristics of VOx thin films as a hole-selective contact layer using ALD (atomic layer deposition). Passivation characteristics improve with iVoc (implied open-circuit voltage) of 662 mV and minority carrier lifetime of 73.9 µs after post-deposition annealing (PDA) at 100 ℃. The improved values are mainly attributed to a decrease in carbon during the VOx thin film process after PDA. However, once it is annealed at temperatures above 250 ℃ the properties are rapidly degraded. X-ray photoelectron spectroscopy is used to analyze the chemical states of the VOx thin film. As the annealing temperature increases, it shows more formation of SiOx at the interface increases. The ratio of V5+ to V4+, which is the oxidation states of vanadium oxide thin films, are 6:4 for both as-deposition and annealing at 100 ℃, and 5:5 for annealing at 300 ℃. The lower the carbon content of the ALD VOx film and the higher the V5+ ratio, the better the passivation characteristics.

• 한국정밀공학회지
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• 제12권5호
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• pp.126-135
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• 1995

An exhaust muffler is one of the simple and effective means to meet the demand for a quiet vehicle, and it deserves a close attention to effectively reduce the engine noise. The transfer function technique is one of the tools that have been used to analyze the noise characteristics of the exhaust muffler. In this paper we obtained a transfer function using the forward-going and backward-going components of sound pressure in the exhaust muffler, which is compatible wiht lattice filter algorithm. This form of transfer function is obtained for the basic elements of a muffler, such as uniform tube, open termin- ation, closed termination, anechoic termination, expansion, contraction, extended-tube resonator, hole, Helmholtz resonator, and concentric hole-cavity resonator. The results are combined to produce the transfer function of various types of mufflers. With this transfer function we calculate the transmission and insertion losses of mufflers, and examined the effects of various design parameters. Comparisons were made between the calculation and experimental results, which showed a good agreement, and we conclude that the transfer function of lattice form can be used to analyze the noise characteristics of the exhaust mufflers.