• Journal of Physiology & Pathology in Korean Medicine
• /
• v.16 no.2
• /
• pp.257-261
• /
• 2002

This experimental study was designed to investigate the effect of water extracts of Chukchunwhan on the urine metabolism in rat. The results are summarized as follows ; 1. Treatment with Chukchunwhan-extracts increased excreted-urine volume of rat at the first week, however markedly decreased the excreted-urine volume at 2nd week. 2. Chukchunwhan-extracts inhibited the high level of excreted-urinary protein from rat for two weeks. 3. Chukchunwhan-extracts did not affect on the excreted-urine components of rat except for urinary protein. The results suggest that water-extracts of Chukchunwhan can be applicable to the abnormal volume of urine without medical poisoning, which have been used in the all sort of urinary diseases.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.87-92
• /
• 2002

At present, the polymer-modified mortars are used as high-performance as well as multi-functional materials in the construction industry. The purpose of this study is to synthesize polymer to modify in cement mortars and make test samples to understand pore size distribution. This paper deals with the effect of monomer ratio on the typical properties of polymer-modified mortars using Methylmethacrylate-Butyl Acrylate(MMA/BA) latexes synthesized through emulsion polymerization. From the results, we knew that the pore volume of polymer-modified mortars using Methylmethacrylate-Butyl Acrylate latexes at bound MMA contents of 70 and 60 percent is 7.5-75cm$^3$/g and the fine pore volume is increased with an increase in the polymer-cement ratio. The total pore volume of polymer-modified mortars using MMA/BA latexes is linearly reduced with an increase in the bound MMA content and increased in the polymer-cement ratio.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.3
• /
• pp.10-18
• /
• 2004

It is well known that the stratified charge combustion has many kind of advantages to combustion characteristics, such as higher thermal efficiency and less CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can be caused low fuel consumption, it is produced the high unburned hydrocarbon and soot levels because of different equivalence ratio in the combustion chamber. Moreover it has a lot of possibility of low output and misfire if the mixture gas would not be in existence around the spark plug. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The effect of locally mixture gas distribution according to control the direct injection and premixed injection in the chamber were examined experimentally. In addition, the effects of turbulence on stratified charge combustion process were observed by schlieren photography.

• International Journal of Aeronautical and Space Sciences
• /
• v.11 no.2
• /
• pp.59-68
• /
• 2010

The aim of this work is to analyze high temperature flows around an axisymmetric blunt body taking into account chemical and vibrational non-equilibrium state for air mixture species. For this purpose, a finite volume methodology is employed to determine the supersonic flow parameters around the axisymmetric blunt body. This allows the capture of a shock wave before a blunt body placed in supersonic free stream. The numerical technique uses the flux vector splitting method of Van Leer. Here, adequate time stepping parameters, along with Courant, Friedrich, Lewis coefficient and mesh size level are selected to ensure numerical convergence, sought with an order of $10^{-8}$.

• Journal of Korea Foundry Society
• /
• v.22 no.4
• /
• pp.155-159
• /
• 2002

Magnesium alloys have high strength to weight ratio and are extremely attractive for applications in transport industry. Most of structural magnesium alloys are manufactured by die casting process. The tensile properties of AZ91HP magnesium alloy were investigated after die casting under various die casting conditions. After die casting by using cold chamber machine, the volume porosity of specimens was examined with density method. With the increase of the volume porosity of specimens, both the tensile strength and elongation were significantly decreased, however the 0.2% offset strength was almost independent of the amount of porosity. With the increase of crystal pressure from 500 to 900 bar during die casting, the volume porosity was decreased, which resulted in the increase of the tensile strength. The mould temperature within the range of $150{\sim}250^{\circ}C$ has not influenced the microstructure with the eutectic phase and tensile properties of specimens. The tensile strength was the highest at 90m/sec of gate speed.

• Current Optics and Photonics
• /
• v.2 no.1
• /
• pp.85-89
• /
• 2018

This paper presents a new, efficient hybrid photonic-plasmonic structure. The proposed structure efficiently and with very high accuracy combines the resonant mode of a low-mode-volume photonic-crystal nanocavity with a bowtie nanoantenna's plasmonic resonance. The resulting enormous enhancement of light intensity of about $1.1{\times}10^7$ in the gap region of the bowtie nanoantenna, due to the effective optical-resonance combination, is realized by subtle optimization of the nanocavity's optical characteristics. This coupled structure holds great promise for many applications relying on strong confinement and enhancement of optical field in nanoscale volumes, including antennas (communication and information), optical trapping and manipulation, sensors, data storage, nonlinear optics, and lasers.

• Journal of the Mineralogical Society of Korea
• /
• v.9 no.1
• /
• pp.35-42
• /
• 1996

Polycrystalline ZrH2 in tetragonal crystal system has been compressed in a modified Bassett-type diamond anvil cell up to 36.0 GPa at room temperature. X-ray diffraction data did not indicate any phase transitions at the present pressure range. The pressure dependence of the a-axis, c-axis, c/a and molar volume of ZrH2 was determined at pressures up to 36.0 GPa. Assuming the pressure derivative of the bulk modulus (K0') to be 4.11 from an ultrasonic value on Zr, bulk modulus (K0) was determined to be 160Gpa by fitting the pressure-volume data to the Birch-Murnaghan equation of state. Same sample was heated at $500^{\circ}C$ at the pressure of 9.8 GPa in a modified Sung-type diamond anvil cell. Unloaded and quenched sample revealed that the original tetragonal structure transforms into a hexagonal structured phase with a zero-pressure molar volume change of ~115.5%.

• Journal of Hydrogen and New Energy
• /
• v.19 no.1
• /
• pp.26-34
• /
• 2008

This study presents an aerodynamic design and an experimental performance test of a turbo air compressor consisted of mixed-flow impeller and curved diffuser for the PEM fuel cell vehicle application. Many studies compare the efficiency, cost or noise level of high-pressure and low-pressure operation of PEM fuel cell systems. Pressure ratio 2.2:1 is considered as design target The goal of compressor design is to enlarge the flow margin of compressor from surge to choke mass flow rate to cover the operational envelope of FCV. Large-scale rig test is performed to evaluate the compressor performance and to compare the effects of compressor exit pipe volume to stall or surge characteristics. The results show that the mixed-flow compressor designed has large flow margin, and the flow margin of compressor configuration with small exit volume is larger than that with large exit volume.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.585-588
• /
• 2008

This study investigated fundamental properties of the colored concrete Corresponding to the various temperatures for plasticity and additive volume of the redmud. the results were summarized as following. There was no difference on the air contents and slumpflow at each temperatures for plasticity. The color tone was high in accordance with increase of temperatures for plasticity, but the drying shrinkage length change was shown in the opposite tendency. The slumpflow was gradually declined, but the air content, compressive strength, color ton and drying shrinkage length change were overall increased when the additive volume of the redmud was increased.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.04a
• /
• pp.15-21
• /
• 2001

An accumulator in hydraulic systems stores kinetic energy during braking action, and then that controls hasty surge pressure. An energy recovery system using accumulator seems to be advantageous for ERBS due to its high energy density. This study suggests a method to decide suitable accumulator volume for ERBS. The method is based upon energy conservation between kinetic energy of moving inertia and elastic energy of accumulator. The energy conversion was analyzed and a simple formula was derived. A series of computer simulation was done to verify effectiveness of the formula. The results of the simulation work were compared with those of experiments and these results show that the proposed design is effective for decision accumulator volume in ERBS.