• Journal of computational fluids engineering
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• v.20 no.1
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• pp.10-15
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• 2015

In this study, the characteristics of water treatment mixer with various propeller profiles are numerically invesitgated. The computation was conducted by solving the incompressible Navier-Stokes equations on unstructured tetrahedral elements with k-${\varepsilon}$ turbulence model. It was found that the spreading angle and swirl magnitude of the jet are important factors for the mixer efficiency, since they clearly characterize the propeller and the frontal surface area of the propeller but not so much affected by the skew angle if it exceeds 30 degrees. The case1 and case2 models are found to show the best propeller efficiency. The case2 with low blade angle, however, requires the lowest power input for the same discharge capacity as the case1.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.111-111
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• 2003

Green tea have been widely reported as functional foods because of their various bioactivities. In the present study, we used 3T3-Ll cells model of white adipocytes to clarify whether green tea and its main pharmaceutically effective compounds (EGCG, caffeine and theanine) prevent obesity. Cellular viability, glycerol-3-phosphate dehydrogenase activity, glycerol release and HSL mRNA levels were checked. Glycerol release into the medium was significantly increased by the cells treated with green tea extract. Glycerol release into the medium was significantly increased by the cells treated with green tea extract. Caffeine and theanine from green tea showed some level of lipolytic activity, and glycerol-3-phosphate dehydrogenase activity was remarkably decreased by EGCG. These results suggest that green tea has anti-obesity effect through inhibition of adipogenesis and stimulation of lipolysis. Catechins and theanine of green tea might be the factors responsible for the modulation of lipid metabolism and adipocyte differentiation.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.155-158
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• 2002

In general, TVC(Thermal Vapor Compressor) is used to boost/compress a low pressure vapor to a higher pressure for further utilization. The one-dimensional method is simple and reasonably accurate, but cannot realize the detail as like the back flow and recirculation in the mixing chamber, viscous shear effect, and etc. In this study, the axisymmetric How simulations have been performed to reveal the detailed flow characteristics for the various ejector shapes. The Navier-Stokes and energy equations are solved together with the continuity equation In the compressible flow fields. The standard $k-{\epsilon}$ model is selected for the turbulence modeling. The commercial computational fluid dynamic code FLUENT software is used for the simulation. The results contain the entrainment ratio under the various motive, suction and discharge pressure conditions. The numerical results are compared with the experimental data, and the comparison shows the good agreement. The three different flow regimes (double chocking, single chocking and back flow) have been clearly distinguished according to each boundary pressure values. Also the effects of the various shape variables (nozzle position, nozzle outlet diameter, mixing tube diameter, mixing tube converging angle, and etc.) are quantitatively discussed.

• Coupled systems mechanics
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• v.9 no.5
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• pp.433-454
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• 2020

In-place analysis for offshore platforms is essentially required to make proper design for new structures and true assessment for existing structures. The structural integrity of platform components under the maximum and minimum operating loads of environmental conditions is required for risk assessment and inspection plan development. In-place analyses have been executed to check that the structural member with all appurtenances robustness and capability to support the applied loads in either storm condition or operating condition. A nonlinear finite element analysis is adopted for the platform structure above the seabed and the pile-soil interaction to estimate the in-place behavior of a typical fixed offshore platform. The analysis includes interpretation of dynamic design parameters based on the available site-specific data, together with foundation design recommendations for in-place loading conditions. The SACS software is utilized to calculate the natural frequencies of the model and to obtain the response of platform joints according to in-place analysis then the stresses at selected members, as well as their nodal displacements. The directions of environmental loads and water depth variations have important effects on the results of the in-place analysis behavior. The result shows that the in-place analysis is quite crucial for safe design and operation of offshore platform and assessment for existing offshore structures.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.3
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• pp.166-173
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• 2009

The reliability of hafnium oxide gate dielectrics incorporating lanthanum (La) is investigated. nMOSFETs with metal/La-doped high-k dielectric stack show lower $V_{th}$ and $I_{gate}$, which is attributed to the dipole formation at the high-k/$SiO_2$ interface. The reliability results well correlate with the dipole model. Due to lower trapping efficiency, the La-doping of the high-k gate stacks can provide better PBTI immunity, as well as lower charge trapping compared to the control HfSiO stacks. While the devices with La show better immunity to positive bias temperature instability (PBTI) under normal operating conditions, the threshold voltage shift (${\Delta}V_{th}$) at high field PBTI is significant. The results of a transconductance shift (${\Delta}G_m$) that traps are easily generated during high field stress because the La weakens atomic bonding in the interface layer.

• Journal of the Ergonomics Society of Korea
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• v.28 no.2
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• pp.57-67
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• 2009

This study proposed a practical metaphor development process that consisted of three steps: 1) identifying major functions, 2) developing metaphor candidates, and 3) evaluating appropriateness of the candidates. In the first step, a total of 27 functions might be implemented in a driver information system (DIS) in the near future. Then, three metaphor candidates were selected from existing metaphors, which were reported to be more practical than others by previous studies. Finally, the candidates were evaluated on their appropriateness for driver information systems by using a quick and simple survey. As a result, two metaphors (a PC and a secretary) were identified as the most appropriate ones. The two metaphors can be used to design a variety of interfaces and interactions for driver information systems. In addition, the development process proposed in this study could be applied to developing metaphors for emerging devices with a variety of functions (e.g. PMPs, MP3s, and electronic dictionaries) as well as driver information systems.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.11
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• pp.38-45
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• 1996

In recent years, ultrasonic has been widely applied in measurement and industrial fields and its application range has been expanded as a result of continuous research and development. Wire Bonding Machine, an instrument fabricating semi-conductor, makes use of ultrasonic bonding method. Specially, the method utilizes the longitudinal vibration of ultrasonic transducer composed of piezoelectric vibrator and horn. This work investigates the design conditions affecting the dynamic characteristics through the theretical and experimental analysis. It conducts separately the system identification of piezoelectric vibrator in time domain and the modal analysis of horn in frequency domain. The integrated modeling is conducted via a combbination of dynamic identification of piezoelectric vibrator and theroretical analysis of horn. Then comparison is made for theroretical and experimental results of the dynamic characteristics of the ultrasonic transducer comprised of piezoelectric vibrator and horn. Form the results of the comparison we develop the design technique of ultrasonic transducer using dynamic characteristics analysis and propose the possibility of ultrasonic bonding considering the optimal conditions for the longitudinal vibration of ultrasonic transducer and other conditions.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.1
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• pp.21-25
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• 1988

The rumen degradability of rice straw (untreated, urea-sprayed, urea-treated), grasses (Panicum maximum, Pennisetum clandestinum) and rice bran was compared. The mean in vivo organic matter digestibility of the untreated (US), urea-supplemented (SS) and urea-ammonia treated (TS) rice straw were 50.9, 53.9 and 57.4%, respectively. Rice bran contained extremely high levels of acid-insoluble ash (25.2% DM), and its OMD was 36.1%. Grasses had OMD values around 66%. Degradability measurements were performed with buffaloes using the nylon bag technique. The organic matter (OM) disappearance data were fitted to an model which was used to describe degradation pattern. The mean potentially degradable fraction for US, SS and TS was 61.5, 61.9 and 69.4%, respectively. Urea-ammonia treatment increased both the amount of OM degraded and the rate at which it was degraded in the rumen. Both grasses had similar values for degradable fraction (around 65%) and for rate constant for degradation (0.04). Rice bran contained high proportions of readily soluble material (23.9%), but the degradable OM fraction was only 13.2%. The low quality of rice bran is attributed to the contamination of rice hulls during processing.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1700-1709
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• 1993

The stepped specimen which is subjected to step loading is modeled to study the initiation and growth of adiabatic shear band using explicit time integration finite element method. Three different clearance sizes are tested. The material model for the stepped specimen includes effects of strain hardening, strain rate hardening and thermal softening. It is found that the material inside the fully grown adiabatic shear band experiences three phase of deformation, (1) homogeneous deformation phase, (2) initiation/incubation phase, and (3) fast growth phase. The second phase of deformation is initiated after sudden shear stress drop which occurs at the same time regardless of the clearance size. The incubation time prior to fast growth phase increases, as the clearance size of the stepped specimen increases. Whereas, after incubation period, the growth rate of the adiabatic shear band decreases, as the clearance size decreases. It is also found that two adiabatic shear band may develop instead of one for the smaller clearance size.

• THE JOURNAL OF KOREAN ORIENTAL ONCOLOGY
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• v.7 no.1
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• pp.109-116
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• 2001

By applying in vitro invasion assay model, we examined the anti-metatstastic effect of ChunghjagamTang(CLJGT). In 3H-thymidine incorporation assay, CLJGT treated groups showed the decreased DNA synthesis rate compared with control group. Gelatin zymogram assay showed that CLJGT decreases the gelatinolytic activity of MMP-9 from A-549, at the concentration of $800{\mu}g/ml$. We examined whether CLJGT inhibits the invasion of A-549 cells through the matrigel precoated transwell chamber. The results showed that CLJGT effectively inhibited the invasion of A-549 as compared with the control (+PMA) groups. From our research, part of mechanism underlying anti-metastastic effect of CLJGT was proven in vitro.