• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.6
• /
• pp.119-126
• /
• 2014

Micro-holes of conductive ceramic are required in micro structures. Micro-electrical discharge machining (Micro-EDM) is an effective machining method since EDM is as process for shaping hard metals and complex-shaped holes by spark erosion in all kinds of electro-conductive materials. However, as the depth of micro hole increases, the machining condition becomes more unstable due to inefficient removal of debris between the electrode and the workpiece. In this paper, micro-EDM was performed to evaluate machining characteristic such as electrode wear, machining time, taper angle, radial clearance with varying voltage and ultrasonic vibration on 10 vol.% Carbon-nanotube reinforced conductive $Al_2O_3$ composite fabricated by spark plasma sintering in previous research.

• Archives of Pharmacal Research
• /
• v.25 no.6
• /
• pp.889-894
• /
• 2002

Acharan sulfate (AS) is a glycosaminoglycan (GAG) prepared from the giant African snail, Achatina fulica. In this study, some biological activities of AS were evaluated on the basis of structural similarities to heparin/heparan sulfate and the biological functions of GAGs. We demonstrated that it exhibited strong immunostimulating activities as measured by carbon clearance test in mice and in vivo phagocytosis. It also exhibited a significant hypoglycemic activity in epinephrine (EP)-induced hyperglycemia as well as antifatigue effects by weight-loaded forced swimming test. And it showed hypolipidemic activities in cholesterol-rich mixture induced hyperlipidemia in rats. The above results indicate that AS has diverse biological activities and suggest therapeutically important target molecules.

• Tribology and Lubricants
• /
• v.6 no.1
• /
• pp.82-88
• /
• 1990

In order to investigate tribological effects of coatings on different places on tool wear, commercial quality coated inserts were tested in production speed machining after the coatings on clearance or rake face of coated tools were selectively removed. The experimental results demonstrated that the primary role of coatings in tool wear was the reduction of the thermochemical adhesion between the tool material and workpiece. And the coating on rake face was observed to retard the progress of flank wear. In case of machining carbon steel, multicoated tools showed the most favorable results for considering the notch wear.

• Transactions of Materials Processing
• /
• v.7 no.5
• /
• pp.439-444
• /
• 1998

Recently many automotive parts have been made with stainless steels by deep drawing processes, But there are various problems occurred in deep drawing works of stainless steels compared with low carbon steels. For the severe deep drawing of complex cylindrical housing optimum process planning is required to eliminate intermediate annealing improve shape accuracy and maintain surface integrity without drawing defects such as tears wrinkles and scratches or galling. Therefore in this study a sample process planning of the severe of the severe deep drawing process is applied to a complex cylindrical housing needed for a 6 multi-stepped deep drawing of type STS 305 . A series of experiments are performed to investigate optimum process variables such as drawing rate radius and clearance. Through experiments the variations of the thickness strain distribution and hardness distribution in each drawing step are observed. Also the effects of other factors on formability such as drawing oil, blank holding force and die geometry are examined and discussed.

• Korean Journal of Pharmacognosy
• /
• v.25 no.3
• /
• pp.233-237
• /
• 1994

Bacillus P-92 which fermented antler was isolated from intestinal bacteria. The biological activites, carbon clearance and growth activity of lactic acid bacteria, of fermented antler was better than those of untreated antler. The enyzmes activities, ${\beta}-glucosidase,\;{\beta}-glucuronidase$ and tryptophanase, of intestinal bacteria of mice treated with fermented antler were lower than those of mice treated with untreated antler, although those of mice treated with fermented antler or untreated antler were higher than those of control. Biological activity of the antler seems to be increased by fermentation.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.2
• /
• pp.228-236
• /
• 2002

In this study, the carbon steels, SM20C were machined with the tungsten carbide tipped circular saw to clarify the cutting-off characteristics in terms of tool wear. The results show that an improved performance in view of both the tool wear and the cutting efficiency was obtained by using oil base cutting fluid at the cutting speed of 100m/min with the feed of 0.06mm/tooth. The rake angle of 10$^{\circ}$ , clearance angle of 8$^{\circ}$ , nose radius of R0.1mm, and end cutting edge champer of 0.1mm$\times$25$^{\circ}$ are believed as the best tool geometries. The tool wear decreases due to using the saw of the disk of STS5 and the tool material of P30.

• Journal of Welding and Joining
• /
• v.12 no.3
• /
• pp.48-55
• /
• 1994

In this experiment, to find optimum brazing conditions for Cu/Stainless Steel brazing using filler metals of Ag-Cu-Zn-Cd system, first of all spreading ratio was tested on 304 stainless Steel and low carbon steel. And then shear test of brazed joint was executed. As the result of that, the shear strengths of brazed joints were the range of 60-90 MPa. Through microstructure analysis for brazed interface layer, We found as follows. Firstly interface layer increased as time increased. Secondly continuous layer of Ag-Cd compound was observed along the side of stainless steel. Also by means of EDS analysis for fracture surface, ductile fracture was occurred and precipitates on the fracture surface were found to include Cr, Mn, Si in Ag-rich phase.

• Toxicological Research
• /
• v.4 no.2
• /
• pp.151-158
• /
• 1988

Experiments were undertaken to evaluate the effects of brazilin and hematoxylin on immune functions in normal young mice. Brazilin and hematoxylin decreased the circulating leucocyte counts. Brazilin and hematoxylin decreased the cirulating leucocyte counts. Both compounds did not produce a significant change of immunoorgan weights in comparison with those in the control group. Brazilin decreased significantly IgM plaque forming cells. Brazilin and hematoxylin decreased significantly Arthus reaction at 3 hours-post challenge with respect to aggregated bovine serum albumin.

• Journal of Haehwa Medicine
• /
• v.9 no.2
• /
• pp.123-134
• /
• 2001

In order to investigate the effect of Mori Folium on immunologic control function, the various immune responses were studied. The results were obtained as follows : 1. The transformation of lymphocyte was increased significantly in all concentration of Mori Folium treated group as compared with negative and positive control. 2. In FACS analysis, the population of helper T cell and T cell were increased significantly in Mori Folium treated group as compared with control. 3. IL-12(p35) and INF-${\gamma}$ were upregulated in Mori Folium treated group 4. NO and carbon clearance were significantly increased in Mori Folium treated group as compared with control. 5. The hemagglutinin titer and hemolysin titer were increased but insignificantly in Mori Folium treated group as compared with control.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.2
• /
• pp.940-946
• /
• 2015

The turning clearance angle changes the machining characteristics. In this study, three workpiece materials, machine structural carbon steel, chrome-molybdenum steel and stainless steel, were examined. The experiments revealed how the features of selected materials changed when they were processed with machining operation. To find the surface roughness of workpiece materials, the workpiece materials, which have a higher tensile strength, showed a much better surface roughness in the surface roughness tester. Moreover, the process feed rate was compared between 0.07 mm/rev and 0.10 mm/rev. When the process feed rate was 0.07 mm/rev, the surface roughness has superior results without reference to the quality of the materials. According to this research on the turning clearance angle, the best roughness value was observed when the quality of the materials were $0.9^{\circ}$, whereas the worst roughness was observed when quality of the materials was $0.3^{\circ}$.