• Tunnel and Underground Space
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• v.10 no.4
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• pp.516-525
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• 2000

Recently, the demand for pollution-free demolition work of old reinforced concrete and steel structure has rapidly increased as the redevelopment of urban area has been accelerated. This study deals with linear shape charges for explosive jet cutting on steel structure. We have tested material and shape of steel structure, characteristics of thickness and strength, shape of linear shape charges, type of shape charges, cumulative charges, type of liner, stand-off distance, detonation method. effect of sound and vibration by air blast in explosive jet cutting method. So, We developed linear shape charges in order to take advantage of optimum explosive jet cutting condition. Shape charges were made of PETN explosives. We obtained the experimental formula to decide the amount of explosive needed for thickness of steel structure plate. There are prospects for application of the explosion curving technology under the open space conditions for dismantling the steel structure and steel bridge, scrapped old boats, which are going out of service.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.132-136
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• 1996

A Study is a experiment which is figure out to aptimum discharge cutting condition of the surfaceroughness, electric discharging speed and electro wear ratio with Ton Toff and V(voltage) as an input condition according to the current(Ip) in an electric spark machine ; 1)Electrode is utilized Cu(coper) and Graphite. 2)Work piece is used the material of carbon steel. The condition of experiment is; 1)Current is varied 0.7(A) to 50(A). 2)Pulse time(Ton) is varied 3($\mu$s) to 240($\mu$s) and also Toff is varied 7($\mu$s) to 20($\mu$s). 3)The time of electric discharging to work piece in each time is 30(min) to 60(min) 4)After the upper side of work piece was measured in radius (5${\mu}{\textrm}{m}$) of syulus analyzed the surface roughness to made the table and graph of Rmax by yielding data. 5)Electro wear ratio is; \circled1Coper was measured cx-machining and post machining but the electronic baiance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume specific gravity and analyzed to made its table and graph on ground the data 6)In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V.R(Automatic Voltage Regulator). 7)The memory scope was sticked to the electric spark machine. 8)In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid, it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging According to above results, the surface roughness by the variation of electrodw and current was analyzed to compare KS(Korea Standards) It was decided the optimum condition of electric discharge cutting through analyzing the effect of electric discharge speed and electro wear ratio.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.5
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• pp.7-15
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• 2004

The purpose of this study was to present the method to choose the optimum machining condition for the wire EDM. This was completed by examining the ever-changing quality of the material and by improving the function of the wire electric discharge machine. Precision metal mold products and the unmanned wire electric discharge machining system were used and then applied in industrial fields. This experiment uses the wire electric discharge machine with brass wire electrode of 0.25mm. To measure the precision of the machining surface, average values are obtained from 3 samples of measures of center-line average roughness by using a third dimension gauge and a stylus surface roughness gauge.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.91-98
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• 2014

The purpose of this research is to investigate optimum machining conditions to improve the quality of die using the CAD/CAM system(Power Shape/Power Mill) and 3D printing. Surface roughness is widely used as an index for processing degree of accuracy. The Power Shape was used to model the shape of product. And the model shape is confirmed by 3D printing system(BFB-3000). Also, tool path and NC-codes were generated using Power Mill. Finally, the product was cut using CNC machine(NBS-2025). The cutting time and surface roughness were measured by measuring instrument. And then this process was repeated by changing the conditions to find optimal machining conditions. The surface roughness behavior with regard to specific factors were analyzed. Through this study, the optimal machining condition can be obtained.

• Food Engineering Progress
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• v.21 no.2
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• pp.110-115
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• 2017

This study aimed to identify milling characteristics depending on the number of a cutting roller's air vent and blowing velocity to remove rice bran by the cutting type milling machine which can minimize the conventional milling process. The level of whiteness was found to be $38{\pm}0.5$ in all the conditions, showing consistent whiteness levels during milling. The rice temperatures turned out to be 15.4 and $14.6^{\circ}C$ which were rather low-level under the conditions of the cutting roller with 3 vents and blowing velocities of 35 and 40 m/s respectively. Cracked rice ratio was 2.13% under the conditions of the cutting roller with 3 vents and a blowing velocity of 35 m/s. Broken rice ratio showed the range of 0.762-0.869%, reflecting a low level. Turbidity after milling was decreased, as blowing velocity became faster. Energy consumption for milled rice production was decreased, as blowing velocity became faster. The optimum milling condition for cutting type milling machine depending on air vent number of cutting roller and blowing velocity was found to be 3 vents and 35 m/s.

• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.530-536
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• 2006

Hardwood cutting propagation and early growth characteristics were investigated in order to develop the method of cutting propagation and to find out growth characteristics in the low altitude for in situ and ex situ conservation of Empetrum nigrum var. japonicum K. Koch, which is typical arctic alpine plants on Mt. Halla. The growth of roots and shoots was different depending on hormone concentrations or soil conditions. The survival rate, rooting rate, root growth, number of root and shoot growth increased with treatment of 100 mg/l or 500 mg/l NAA. Consequently, optimum condition of hardwood cutting was at treatment with 100 mg/l or 500 mg/l NAA. When plantlets from hardwood cuttings were exposed to the field condition, after 7 months survival rate was 73.3% without shading while $91.1{\sim}94.4%$ at shading conditions. In the green house, however, survival rate of plantlets were $95.6{\sim}97.8%$ without shading. The growth of plantlets was different depending on sites and shading conditions. Particularly, the best growth was obtained when the plantlets were grown in shading conditions. It indicates that relative humidity and light intensity are correlated with the growth in the low altitude area.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.79-88
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• 2002

High speed machining system have been used in industrial because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. Therefore this study proposed to decide best manufacturing cutting condition for surface roughness and rapid manufacturing tune by using computer Image processing system and 3D modelling. Until the 16,000 rpm, the surface roughness is decreased rapidly, but it is not over that. The 22,000 rpm is the spindle speed with the optimum surface in the high speed end-milling. In the case of the feed rate with 2,000 mm/mm and 8,000 mm/mm, the surface roughness is better than 4,000 mm/min and 6,000 mm/min. By using the 3D modelling, it is effectively represented shape characteristics of working surface m high speed end-milling.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.531-555
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• 2011

This study aims to derive the statistical models for the estimation of the required specifications of a rock TBM as well as for its cutterhead design suitable for a given rock mass condition. From a series of multi-variate regression analysis of 871 TBM driving data and 51 linear rock cutting test results, the optimum models were newly proposed to consider a variety of rock properties and mechanical cutting conditions. When the derived models were applied to two domestic shield tunnels, their predictions of cutter penetration depth, cutter acting forces and cutter spacing were very close to real TBM driving data, showing their high applicability.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.4
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• pp.257-267
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• 1993

Optimum pasture management during the summer season is an important factor to maintain good regrowth and persistence of pasture. The field experiment was carried out to investigate the effects of cutting management on growth and reserve carbohydrates in stubble. and on dry matter yield of orchardgrass dominated pasture during the mid-summer season. Three different cutting times(July 15, 25 and August 5) as a main plot and three cutting heights(3, 6 and 10cm) as a sub plot were disigned with three replications. The experiment was done at pasture of Changsung Agricultural High School in 1988. The results obtained were summarized as follows: 1. Temperature of soil surface and underground in the cutting of July 15 and July 25 was not showed significantly different, because of low intensity of radiation with a run of wet weather, and that of August 5 cutting tends to be lowed in high cutting height during the mid-summer season. 2. Amount of soil moisture against cutting height showed that high cutting had a low content. 3. Growth rate against regrowth of plant height, lear length and leaf area showed to be fast in high cutting. 4. Rapid recovery period of carbohydrate content after cutting and large amount of carbohydrate accumulation were showed in the cutting of July 15 and 25 compared with August 5 cutting in the reserve carbohydrate content against cutting of time and height during the mid-summer season. 5. Dry matter yield of the 4th and 5th cutting showed to be remarkable in July 15 cutting compared to those of July 25 and August 5. From the above results, it is suggested that the 10cm cutting height during the mid-summer season is the most effective for good regrowth, reserve carbohydrates and dry matter yield of orchardgrass.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.381-386
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• 2004

A flexible disk grinding system process has been introduced that utilized varying disk orientation with respect to workpiece along with the applied feed speed. A known process model methodologies has been used to fomulate processed surface profiles. Various process conditions including cutting speed, maximum feed speed and orientation angles could applied to observe process outcomes. Even though continuous and constant feed speed has been applied to the process, the results from the trapezoidal input velocity profiles would be observed and compared. Based on the control strategies including neural network methodologies, several output results were compared to find the optimum process condition.