• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.1-7
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• 2004

Abrasive water-jet(AWJ) machining can cut various materials such as metal, glass and plastics. However, the AWJ machining has some troubles including kerf, rounding and side taper. In this study, we experimently investigated the correlation between the traverse speed of the abrasive water-jet and the dimensional error of the workpiece according to the thickness and the types of the material. The specimen was the stainless steel and the mild steel and the predetermined contour cutting was conducted. A comer radius error, an uncut width and a kerf were measured and evaluated.

• Geomechanics and Engineering
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• v.8 no.4
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• pp.495-510
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• 2015

The applications of water jet cutting (WJC) in coal mine have progressed slowly. In this paper, we analyzed the possibility and reasonableness of WJC application to pressure relief in hard coal seam, simulated the distributive characteristics of stress and energy fields suffered by hard coal roadway wallrock and the internal relationships of the fields to the instability due to WJC (including horizontal radial slot and vertical annular slot) on roadway wallrock. The results showed that: (1) WJC can unload hard coal seam effectively by inducing stress release and energy dissipation in coal mass near its slots; its annular slots also can block or weaken stress and energy transfer in coal mass; (2) the two slots may cause "the beam structure" and "the small pillar skeleton", and "the layered energy reservoir structure", respectively, which lead to the increase in stress concentration and energy accumulation in coal element mass near the slots; (3) the reasonable design and optimization of slots' positions and their combination not only can significantly reduce the scope of stress concentration and energy accumulation, but also destroy coal mass structure on a larger scale to force stress to transfer deeper coal mass.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.176-176
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• 2003

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.524-528
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• 2000

Effect of food additives on the heat sensitivity of listeria monocytogenes H-12 inoculated into Pollack surimi was investigated and also confirmed the effectiveness of various decontamination method such as tap water washing, chlorination, ultraviolet irradiation and heat treatment haying been applied on cooking utensils. Food additives such as polyphosphate, chitosan, and potassium sorbate increased heat sensitivity of t monocytogenes H-12 and polyphosphate showed the strongest synergistic effect. The tested strain was not detected from stainless steel and plastic cutting board contaminated with $10^4{\~}10^5/cm^2$ of L monocytogenes H-12 after tap water washing for 10 seconds or 1 minute, but washing effect was not found in wooden cutting board. The chlorination of stainless steel and plastic cutting board for 10 seconds with $5{\~}50 ppm$ solution eliminated all cells of the contaminated strain, however any change of the viable cell count was not observed in the chlorination of wooden cutting board, W irradiation on stainless steel and plastic cutting board for 5 minutes with 15 W above 30 cm eliminated the contaminated strain, but the tested strain was still found after 60 seconds of irradiation on wooden cutting board. The treatment of hot water on all used cutting boards for 10 seconds at $70^{\circ}C$ resulted in complete loss of viability of the contaminated strain.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.1-9
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• 2012

It has been known that Golf course could impose negative impacts on water-ecosystem if pollutant-laden runoff is not treated well. It is important to control non-point source and re-use treated wastewater from the golf course to secure water quality of receiving waterbodies. At golf courses, the rainfall-runoff is affected by various practices to manage grasses. In many hydrological modelings, especially in simple rainfall-runoff modeling, effects on runoff of plant growth and cutting are not considered. In the study, the water erosion prediction project (WEPP), capable of simulating plant growth and various management, was evaluated for its runoff prediction from golf course under grass cutting and irrigation. The %Difference, $R^2$ and the NSE for runoff comparisons were 1.15%, 0.93 and 0.92 for calibration, and 18.12%, 0.82 and 0.88 for validation period, respectively. In grass cutting scenario, grass height was managed to be 18~25 mm. The estimated runoff was decreased by 27%. The difference in estimated total runoff was 11.8% depending on irrigation. As shown in this study, if grass management and irrigation are well-controlled, water quality of downstream areas could be obtained.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.5
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• pp.533-551
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• 2015

The rock fracturing during waterjet cutting is very complicated because rock is inhomogeneous and anisotropic, compared with artificial materials (e.g., metal or glass). Thus, it is very important to verify the effects of rock properties on waterjet rock cutting performance. Properties affecting the rock cutting efficiency have been variously described in the literature, depending on the experimental conditions (e.g., water pressure, abrasive feed rate, or standoff distance) and rock-types studied. In this study, a rock-property-related literature review was performed to determine the key properties important for waterjet rock cutting. Porosity, uniaxial compressive strength, and hardness of the rock were determined to be the key properties affecting waterjet rock cutting. The results of this analysis can provide the basic knowledge to determine the cutting efficiency of waterjet rock cutting technology for rock excavation-related construction.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.71-76
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• 2006

Treatment performance and microbial community structure were investigated in water-soluble cutting oil treatment process using biological activated carbon. DOC removal in BACI column at $15^{\circ}C$ was higher than at $25^{\circ}C$, but those of BAC3 column after 60days was high at$25^{\circ}C$. Also, quinone content of first-step reactors at $25^{\circ}C$ and $15^{\circ}C$ was much the same, but those of the third-step reactor at $25^{\circ}C$ was higher than at $15^{\circ}C$. The dominant type of two apparatus was ubquinone (UQ)-l 0 followed by UQ-8. Menaquinones were detected from $25^{\circ}C$ apparatus and effluent. This suggested that DOC removal at $25^{\circ}C$ was advanced degradation by attached microorganisms on the activated carbon surface. The DOC removal in long-term activated carbon apparatus increased with going in BAC3 column. This indicated the influent of POC was a result of DOC removal efficiency decrease. Integrated DOC removal from start point in experiment to break point and quinone content were showed a tendency of increasing with going last-step activated carbon apparatus. Therefore, the biological activated carbon apparatus used by this study was effective treatment process in contaminated groundwater by water-soluble cutting oil.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.1
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• pp.27-33
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• 2003

Excessive heat generation at the implant-bone interface may cause irreversible bone damage and loss of osseointegration. The effect of heat generation in vitro at the implant surface caused by abutment reduction with high-speed dental turbine was examined. Titanium-alloy abutments connected to a titanium alloy screw-implant embedded in an acrylic-resin block in a $37^{\circ}C$ water bath were prepared. Temperature changes were recorded via embedded thermocouples at the cervix and apex of the implant surface. Analysis of variance for repeated measures was used to compare seven treatment groups. Fifty seconds of continuous cutting with air and water coolant caused a mean temperature increase of $1.24^{\circ}C$ at apex and $5.77^{\circ}C$ at cervix. Similar intermittent cutting caused increase of $2.50^{\circ}C$ at apex and $1.64^{\circ}C$ at cervix. But, continuous cutting with air coolant caused a mean temperature increase of $6.47^{\circ}C$ at apex and $5.77^{\circ}C$ at cervix. Similar intermittent cutting caused increase of $6.47^{\circ}C$ at apex and $5.77^{\circ}C$ at cervix. Preparation of implant abutment does not lead to detrimental effect on peri-implant tissues provided that adequate cooling. However, without water cooling, extreme overheating could be provoked, reaching the critical temperature that would lead to irreversible bone damage within only a few seconds.

• Journal of Korea Foundry Society
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• v.9 no.4
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• pp.294-300
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• 1989

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.609-615
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• 2008

In this study, the design of UV-free reflecting reactor was studied to enhance the cutting fluid life for cutting machine. And also, the stability of cutting fluid with addition of biocide in cutting fluid and without biocide was compared with respect to the cutting fluid concentration, pH changes and microorganisms. Low number of microorganism was observed in the cutting fluid after UV-free reflecting treatment as compare to the cutting fluid which was added biocide and just cutting fluid alone. PH of the cutting fluid after UV-free reflecting treatment was about 9$\sim$8.5 while others were observed considerably low. The oil contents of cutting fluid which was added biocied and pure cutting fluid were almost degraded with the passage of time. However, in case of UV-free reflecting reactor, 4$\sim$3.5 Brix oil contents were observed in the cutting fluid.