• BMB Reports
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• 제45권6호
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• pp.348-353
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• 2012

L-2-Oxothiazolidine-4-carboxylic acid (OTC) is a cysteine prodrug that maintains glutathione in tissues. The present study was designed to investigate anti-fibrotic and anti-oxidative effects of OTC via modulation of nuclear factor erythroid 2-related factor 2 (Nrf2) in an in vivo thioacetamide (TAA)-induced hepatic fibrosis model. Treatment with OTC (80 or 160 mg/kg) improved serum liver function parameters and significantly ameliorated liver fibrosis. The OTC treatment groups exhibited significantly lower expression of ${\alpha}$-smooth muscle actin, transforming growth factor-${\beta}1$, and collagen ${\alpha}1$ mRNA than that in the TAA model group. Furthermore, the OTC treatment groups showed a significant decrease in hepatic malondialdehyde level compared to that in the TAA model group. Nrf2 and heme oxygenase-1 expression increased significantly in the OTC treatment groups compared with that in the TAA model group. Taken together, these results suggest that OTC restores the anti-oxidative system by upregulating Nrf2; thus, ameliorating liver injury and a fibrotic reaction.

• 한국해양환경ㆍ에너지학회지
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• 제13권1호
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• pp.30-42
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• 2010

빈산소 수체 거동에 미치는 내부파의 영향을 유체정역학-생태계 결합 모델을 기반으로 하는 수치해석을 이용하여 일본 비와호에 적용하여 고찰하였다. 수치모델은 유체정역학 부 모델과 생태계 부 모델로 이루어져 있고, 3년간의 예비 수치모사를 수행한 후 2007년 4월에서 2008년 3월까지의 기간에 대해 본 수치해석이 이루어졌다. 수치해석의 결과는 계측된 수질의 수직적 구조를 재현하였고, 2007년 9월 30일에서 10월 21일까지의 기간에 나타난 주된 내부파는 켈빈파와 포앙카레파로서 그 주기는 각각 1.63 또는 1.77일이고 0.48일 이었다. 10월 중에 나타난 저층의 빈산소 수체는 상층에 수온약층이 형성된 기간 동안 유지되었다. 늦가을에서 겨울 동안은 수체의 상부와 하부간의 밀도차이가 줄어들고 내부파의 진폭은 증가된다. 빈산소 수체가 내부파의 영향으로 이동을 시작하게 되고, 이 빈산소 수체의 이동으로 깊은 수심의 수생생물 서식지가 감소하게 된다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2007년도 추계학술대회 및 정기총회
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• pp.58-63
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• 2007

Recently, as the management environments are changing rapidly and the uncertainty is becoming larger, the needs of internal control for management and IS become stronger. In order to construct a new internal control system for IS, it is necessary to evaluate the former research of the system. This study emphasizes the importance of effective internal control system, presents a conceptual framework for the preceding factors to consider, and verifies empirically the framework. This study sets the organization citizenship behavior, IS innovation resistance, and IT capability from the viewpoint of Socio-Technical system as the preceding factors for the effectiveness of internal control system. A research model, affecting the above factors on IS capability as a mediating variable of the internal control effectiveness for the use of IS, is set up. PLS-Graph 3.0 is used to verify the model. We found that the internal control effectiveness have affirmative effect on information capability, a surrogate variable of the IS effectiveness and a mediation effect is meaningful.

• 전력전자학회논문지
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• 제23권3호
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• pp.174-181
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• 2018

This study introduces a systematic approach to selecting the internal parameters applied to the equivalent electrical-circuit model (EECM) of a lithium titanium oxide ($Li_4Ti_5O_{12}$; LTO) rechargeable cell. Based on the dynamic characteristic of the cell, a simplified EECM consisting of an open-circuit voltage (OCV), an ohmic resistance, and an RC ladder is fabricated. To select the internal parameters of a simplified EECM, experiments on discharge capacity, OCV, and discharge/charge resistances are performed using hybrid pulse power characterization and direct current internal resistance (DCIR) measurements over the full state-of-charge (SOC) range. The experimental results of the LTO rechargeable cell highlight the importance of correct selection of internal parameters that can reduce EECM errors. This study clearly provides experimental procedures, internal parameters results, and EECM guidelines for adaptive control-based SOC estimation for LTO rechargeable cells.

• 한국유체기계학회 논문집
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• 제18권5호
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• pp.19-25
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• 2015

As a core component of a hydropower station, hydro turbines play a vital role in the integration of a power station. Research on the technology of hydro turbine is continuously increasing with the development of water electricity. On the basis of one-dimensional loss analysis, for three-dimension design, there are a lot of dimension of the internal flow passage shapes that are determined by experience. Therefore, the effect of the internal flow passage shapes on the performance and internal flow characteristics of a Francis hydro turbine model is investigated in this study. In this study, the small curvature of runner blade trailing edge shape is good for improving the efficiency of Francis turbine. The straight stay vane leading edge is good for suppressing the secondary flow. Moreover, suitable tongue passage shape and stay vane number improve the performance of the turbine considerably.

• Journal of Preventive Medicine and Public Health
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• 제35권3호
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• pp.236-244
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• 2002

Objective : To empirically investigate the relationship of internal and external customer satisfactions, service quality, and customer loyalty in medical services. Methods : This essay proposes an integrated model to explain the causality of internal and external customer satisfactions, service quality, and customer loyalty. To this end, a structural model was developed, consisting of the following factors: internal and external customer satisfactions, service quality, and customer loyalty. The study included 214 sets of data, with 107 sets being collected for both out-patients and in-patients. The data were analyzed using AMOS 4.0. Results : We found the greater the internal customer satisfaction, the greater the out-patient quality of service quality. Secondly, the greater the service quality, the greater the external customer satisfaction of both in- and out-patients. The service quality of doctors, compared to that of the nurses, had a greater effect on external customer satisfaction. Thirdly, the service quality of doctors and nurses affected both internal and external customer satisfactions, which ultimately affected the customer loyalty. Finally the greater the external customer satisfaction, the greater the customer loyalty. Conclusion : This Study confirms the positive relationship among the internal and external customer satisfactions, service quality, and customer loyalty, which proves the doctors quality of service is the primary factor for external satisfaction, and customer loyalty relating to medical services.

• Journal of Neurogastroenterology and Motility
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• 제24권4호
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• pp.669-675
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• 2018

Background/Aims Functional dyspepsia (FD) and irritable bowel syndrome (IBS) are common gastrointestinal (GI) disorders and these patients frequently overlap. Trimebutine has been known to be effective in controlling FD co-existing diarrhea-dominant IBS, however its effect on overlap syndrome (OS) patients has not been reported. Therefore, we investigated the effect of trimebutine on the model of OS in guinea pigs. Methods Male guinea pigs were used to evaluate the effects of trimebutine in corticotropin-releasing factor (CRF) induced OS model. Different doses (3, 10, and 30 mg/kg) of trimebutine were administered orally and incubated for 1 hour. The next treatment of $10{\mu}g/kg$ of CRF was intraperitoneally injected and stabilized for 30 minutes. Subsequently, intragastric 3 mL charcoal mix was administered, incubated for 10 minutes and the upper GI transit analyzed. Colonic transits were assessed after the same order and concentrations of trimebutine and CRF treatment by fecal pellet output assay. Results Different concentrations (1, 3, and $10{\mu}g/kg$) of rat/human CRF peptides was tested to establish the OS model in guinea pigs. CRF $10{\mu}g/kg$ was the most effective dose in the experimental OS model of guinea pigs. Trimebutine (3, 10, and 30 mg/kg) treatment significantly reversed the upper and lower GI transit of CRF induced OS model. Trimebutine significantly increased upper GI transit while it reduced fecal pellet output in the CRF induced OS model. Conclusions Trimebutine has been demonstrated to be effective on both upper and lower GI motor function in peripheral CRF induced OS model. Therefore, trimebutine might be an effective drug for the treatment of OS between FD and IBS patients.

• Wind and Structures
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• 제16권1호
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• pp.93-115
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• 2013

This paper describes a study of the influence of a dynamically flexible building structure on pressures inside and net pressures on the roof of low-rise buildings with a dominant opening. It is shown that dynamic interaction between the flexible roof and the internal pressure results in a coupled system that is similar to a two-degree-of-freedom mechanical system consisting of two mass-spring-damper systems with excitation forces acting on both the masses. Two resonant modes are present, the natural frequencies of which can readily be obtained from the model. As observed with quasi-static building flexibility, the effect of increased dynamic flexibility is to reduce the first natural frequency as well as the corresponding peak value of the admittance, the latter being the result of increased damping effects. Consequently, it is found that the internal and net roof pressure fluctuations (RMS coefficients) are also reduced with dynamic flexibility. This model has been validated from experiments conducted using a cylindrical model with a leeward end flexible diaphragm, whereby good match between predicted and measured natural frequencies, and trends in peak admittances and RMS responses with flexibility, were obtained. Furthermore, since significant differences exist between internal and net roof pressure responses obtained from the dynamic flexibility model and those obtained from the quasi-static flexibility model, it is concluded that the quasi-static flexibility assumption may not be applicable to dynamically flexible buildings. Additionally, since sensitivity analyses reveal that the responses are sensitive to both the opening loss coefficient and the roof damping ratio, careful estimates should therefore be made to these parameters first, if predictions from such models are to have significance to real buildings.

• 한국안전학회지
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• 제35권3호
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• pp.96-104
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• 2020

The numerical simulations were conducted to investigate the thermal-fluid phenomena occurred inside the experimental apparatus during a PCCS, used to remove heat released in accidents from a containment of light water nuclear power plant, operation. Numerical simulations of the flow and heat transfer caused by wall condensation inside the containment simulation vessel (CSV), which equipped with 18 vertical heat exchanger tubes, were conducted using the commercial computational fluid dynamics (CFD) software ANSYS-CFX. Shear stress transport (SST) and the wall condensation model were used for turbulence closure and wall condensation, respectively. The simulation using the actual size of the apparatus. However, rather than simulating the whole experimental apparatus in consideration of the experimental cases, calculation resources, and calculation time, the simulation model was prepared only in CSV. Selective simulation was conducted to verify the effects of non-condensable gas(NC gas) concentration, CSV internal pressure, and wall sub-cooling conditions. First, as a result of the internal flow of CSV, it was observed that downward flow due to condensation occurred surface of the vertical tube and upward flow occurred in the distant place. Natural convection occurred actively around the heat exchanger tube. Due to this rising and falling internal flow, natural circulation occurred actively around the heat exchanger tubes. Next, in order to check the performance of built-in condensation model using according to the non-condensable gas concentration, CSV internal flow and wall sub-cooling, the heat flux values were compared with the experimental results. On average, the results were underestimated with and error of about 25%. In addition, the influence of CSV internal pressure and wall sub-cooling was small, but when the condensate was highly generated due to the low non-condensable gas concentration, the error was large compared to the experimental values. This is considered to be due to the nature of the condensation model of the CFX code. However, in spite of the limitations of CFD, it is valid to use the built-in condensation model of CFD for PCCS performance prediction from a conservative perspective.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.19-26
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• 2003

The dispersion of recycled particulates in the complex coastal terrain containing Kangnung city, Korea was investigated using a three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). The results show that particulates at the surface of the city that float to the top of thermal internal boundary layer (TIBL) are then transported along the eastern slope of the mountains with the passage of sea breeze and nearly reach the top of the mountains. Those particulates then disperse eastward at this upper level over the coastal sea and finally spread out over the open sea. Total suspended particulate (TSP) concentration near the surface of Kangnung city is very low. At night, synoptic scale westerly winds intensify due to the combined effect of the synoptic scale wind and land breeze descending the eastern slope of the mountains toward the coast and further seaward. This increase in speed causes development of internal gravity waves and a hydraulic jump up to a height of about 1km above the surface over the city. Particulate matter near the top of the mountains also descends the eastern slope of the mountains during the day, reaching the central city area and merges near the surface inside the nocturnal surface inversion layer (NSIL) with a maximum ground level concentration of TSP occurring at 0300 LST. Some particulates were dispersed following the propagation area of internal gravity waves and others in the NSIL are transported eastward to the coastal sea surface, aided by the land breeze. The following morning, particulates dispersed over the coastal sea from the previous night, tend to return to the coastal city of Kangnung with the sea breeze, developing a recycling process and combine with emitted surface particulates during the morning. These processes result in much higher TSP concentration. In the late morning, those particulates float to the top of the TIBL by the intrusion of the sea breeze and the ground level TSP concentration in the city subsequently decreases.