• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1308-1313
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• 2004

Proton irradiation technology was used for the improvement of power diode switching characteristics. Proton irradiation was carried out at the energies of 2.32 MeV, 2.55 MeV, 2.97 MeV so that the projection range of irradiated proton would be at the metallurgical junction, depletion region and neutral region of pn diode, respectively. Dose conditions were varied into three conditions of 1${\times}$10$^{11}$ cm$^{-2}$ , 1${\times}$10$^{12}$ cm$^{-2}$ , 1${\times}$10$^{13}$ cm$^{-2}$ at each condition of energies. Characterization of the device was performed by I-V(current-voltage), C-V(capacitance-voltage) and trr(reverse recovery time) measurement. At the optimum condition of irradiation, the reverse recovery time of device has been reduced about 1/5 compared to that of original un-irradiated device.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1421-1423
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• 2001

$Ba(Mg_{1-x}Co_x)TaO_3$[BMCT] ceramics were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of 1525 $\sim$ 1625$^{\circ}C$ for 5hr. in air. The crystal structure of BMCT ceramics was investigated by the XRD. The microstructure of the specimens were observed by SEM. The structural properties of BMCT specimens were investigated as a function of composition and sintering temperature. All BMCT ceramics sintered over 1575$^{\circ}C$ were showed a polycrystalline complex perovskite structure without second phases and any unreacted materials. The density of BMCT (90/10) specimen sintered at 1575$^{\circ}C$ was 7.75g/$cm^2$. As the Co contents decreased, the ordering parameter of B-site in BMCT increased. The ordering parameter of BMCT(90/10) specimen sintered at 1575$^{\circ}C$ was 0.98.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2631-2633
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• 2004

This paper describes the construction of a half sphere screen driving tilting simulator that can perform six degree-of-freedom( DOF) motions simmulator to a tilting train. The mathematical equations of Tilting Train dynamics are first derived from the 6-DOF bicycle model and incorporated with the bogie. carbody, and suspension subsystems. The equations of motion are then programmed by visual C++ code. To achieve the simulator functions. a motion platform that is constructed by six electric-driven actuators is designed. and its kinetics/inverse kinetics analysis is also conducted. Driver operation signals such as carbady angle, accelerator. and tilting positions are measured to trigger the Tilting dynamics calculation and further actuate the cylinders by the motion platform control program. In addition. a digital PID controller is added to achieve the stable and accurate displacements of the motion platform. The experiments prove that the designed simulator is adequate in performing some special rail mad driving situations discussed in this paper.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.107-108
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• 2010

This paper provides test results on the tension stiffening behavior of high strength concrete (HSC) members used silica fume free binder (SFFB) instead of silica fume. The objective of this study is to evaluate the capability of replacing expensive silica fume to SFFB in HSCs with compressive strength of 60 and 80MPa. Test results indicated that for two mixes of 60 and 80 MPa HSC, cracking and strength behavior of tension members, which are replaced silica fume to SFFB, showed equivalent performance to those of tension members used silica fume.

• Journal of Broadcast Engineering
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• v.20 no.5
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• pp.770-773
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• 2015

The contrast of the intensity components of color images usually needs to be improved in order to enhance the visual quality of color images. However, pure color regions can be saturated due to the excessive enhancement of that color. In this paper, a new method for enhancing the visual quality of color images using saturation components in the HSI color space is proposed, and the same enhancement technique in the YCbCr color space is proposed. Computer simulations show that the proposed method provides improved visual quality compared to the conventional methods.

• Biomolecules & Therapeutics
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• v.24 no.5
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• pp.523-528
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• 2016

Urotensin II (UII) is a potent vasoactive peptide and mitogenic agent to induce proliferation of various cells including vascular smooth muscle cells (VSMCs). In this study, we examined the effects of a novel UII receptor (UT) antagonist, KR-36676, on vasoconstriction of aorta and proliferation of aortic SMCs. In rat aorta, UII-induced vasoconstriction was significantly inhibited by KR-36676 in a concentration-dependent manner. In primary human aortic SMCs (hAoSMCs), UII-induced cell proliferation was significantly inhibited by KR-36676 in a concentration-dependent manner. In addition, KR-36676 decreased UII-induced phosphorylation of ERK, and UII-induced cell proliferation was also significantly inhibited by a known ERK inhibitor U0126. In mouse carotid ligation model, intimal thickening of carotid artery was dramatically suppressed by oral treatment with KR-36676 (30 mg/kg/day) for 4 weeks compared to vehicle-treated group. From these results, it is indicated that KR-36676 suppress UII-induced proliferation of VSMCs at least partially through inhibition of ERK activation, and that it also attenuates UII-induced vasoconstriction and vascular neointima formation. Our study suggest that KR-36676 may be an attractive candidate for the pharmacological management of vascular dysfunction.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.318-323
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• 2001

Characteristics of the pulsatile flow in a 3-dimensional elastic blood vessel are investigated to understand the blood flow phenomena in the human body arteries. In this study, a model for the elastic blood vessel is proposed. The finite volume prediction is used to analyse the pulsatile flow in the elastic blood vessel. Variations of the pressure, velocity and wall shear stress of the pulsatile flow in the elastic blood vessel are obtained. The magnitudes of the velocity waveforms in the elastic blood vessel model are larger than those in the rigid blood vessel model. The wall shear stresses on the elastic vessel vary with the blood vessel motions. Amplitude indices of the wall shear stress for blood in the elastic blood vessel are $4\sim5$ times larger than those of the Newtonian fluid. As the phase angle increased, point of the phase angle is are moved forward and the wall shear stresses are increased for blood and the Newtonian fluid.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.709-715
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• 2006

The effects of thermal cycle condition and applied stress on the intergranular corrosion in austenitic 316 type stainless steels were investigated. Specimens were solution-treated at 1100$^{\circ}C$ for one hour and then sensitized in the temperature range of $500{\sim}800^{\circ}C$ by holding $2{\sim}300s$ with a various applied stresses of $0{\sim}8kg/mm^2$. Degree of sensitization. DOS %, was measured through polarization curve by electrochemical DL-EPR test. Microstructural observations were also conducted DOS % increased with an increase of sensitization temperature and/or holding time. Increase of applied stress resulted in increase of DOS % and more corroded surface because of acceleration of intergranular corrosion and fine grain size due to the stress. Cr depleted zone near grain boundary was observed. The amount of depletion was profounded with an increase of sensitization temperature, holding time and applied stress. $M_{23}C_6$ carbides were precipitated discontinuously at grain boundary. However, its amount was relatively small in the thermal cycle condition of 800$^{\circ}C$, 300sec and 4kg/mm$^2$.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1056-1063
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• 2007

Recently, there has been a growing consumer interest in the amount of noise produced by household electrical appliances. The designer of the product must identify the source of the noise, in order to reduce the noise. In the case of a household electric appliance such as the washing machine, there is consumer's complaint about the noise that is generated during the dehydrating condition. Because of several noise sources combined each other. It is difficult to identify the noise sources that contribute to the noise output. Multi-Dimensional Spectral Analysis (MDSA) is a method that can remove the correlation between different noise sources, and it expresses the key contributing factor as a unique output. This study utilized MDSA to analyze the contribution of each input in the noise output during the dehydrating condition.

• Food Science and Biotechnology
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• v.14 no.2
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• pp.190-195
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• 2005

The conditions for the extraction of effective substances from the stem of Opuntia ficus-indica were optimized by a response surface methodology. The total extract yield was maximized under the temperature of $97.77^{\circ}C$, at a time duration of 145.82 min and a water to sample ratio 16.59 mL/g. Moreover, the optimum conditions for the extraction of effective substances were as follows: $84.95^{\circ}C$, 156.50 min and a water/sample ratio of 7.46 mL/g for the phenolics content; and $97.11^{\circ}C$, 139.03 min and a water/sample ratio of 10.91 mL/g for the pectin content. The range of optimum extraction conditions in consideration of the physicochemical properties of the extracts were shown to be as $95-100^{\circ}C$ as the extraction temperature, 120-180 min as extraction time and a water to sample ratio of 5-18 mL/g.