• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.50-53
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• 2000

The effect of punching density on the mechanical and thermal properties of nonwoven needle-punched carbon/phenol composite was studied. The carbonized preforms were farmed into composites with phenol resin. The interlaminar shear, tensile and flexural strengths were increased with increasing punching density. However, excessive punching density decreased interlaminar shear and tensile strengths. Erosion rate of carbon/phenol composite was decreased with increasing punching density

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.63-66
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• 2003

The effect of punching density and material composition on the tensile properties and optimum condition of manufacturing of carbon needle punched perform was studies. The interlaminar tensile strength were increased but the intralaminar tensile strength were decreased with increasing punching density. In the case of the performs composed of continuous oxi-PAN fabrics, there was a considerable improvement of the interlaminar and intralaminar tensile strength.

• Journal of agriculture & life science
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• v.50 no.5
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• pp.217-224
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• 2016

In this study, performance of a developed automatic punching machine considering the planting density of soybeans was evaluated in the case of the operation speed of 0.18-0.28 m/s. The performance demonstrated a rate of 320-500 ㎡/h, 260-400 ㎡/h, and 210-330 ㎡/h for the 0.20 m, 0.25 m, and 0.30 m soybean planting density, respectively. One hundred percent punching capacity was confirmed in 30 mm distance between the ground and the blade. Additionally, in the 50 mm distance condition, the performance of round, square, and hexagonal blades were observed in the range of 16.7-25.2%, 33.0-42.3%, and 54.5-100.0%, respectively. Above all, the hexagonal blade with a 60° edge angle had the most superior cutting quality demonstrating a smooth and soft cutting plane of the plastic.

• Elastomers and Composites
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• v.57 no.4
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• pp.157-164
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• 2022

Representative bulletproof materials, such as aramid or ultra-high molecular weight polyethylene(UHMWPE), have excellent strength and modulus in the plane direction but are very vulnerable to forces applied in the thickness direction. This paper reports a study on the effects of reinforcement in the thickness direction when bulletproof composite fabrics are prepared to improve their performance. Aramid and UHMWPE fabrics were combined using the film-bonding, needle-punching, or stitching methods and then subjected to low-velocity projectile and ball-drop impact tests. The results of the low-velocity projectile test indicated that the backface signature(BFS) decreased by up to 29.2% in fabrics obtained via the film-bonding method. However, the weight of the film-bonded fabric increased by approximately 23% compared with that obtained by simple lamination, and the fabric stiffened on account of the binder. Flexibility, light weight for wearability, and excellent bulletproof performance are very important factors in the development of bulletproof materials. When the needle-punching method was used, the BFS increased as the fibers sustained damage by the needle. When the composite fabrics were combined by stitching, no significant difference in weight and thickness was observed, and the BFS showed similar results. When a diagonal stitching pattern was employed, the BFS decreased as the stitching density increased. By contrast, when a diamond stitching pattern was used, the fabric fibers were damaged and the BFS increased as the stitching density increased.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2230-2235
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• 2011

The purpose of this paper is to provide the unbalanced magnetic force and vibration mode comparison between two large interior permanent magnet machines(IPM) with different pole-slot combination considering stator and rotor eccentricity. Due to the punching tolerance, the mixed eccentricity of air-gap is inevitable. It will generate the asymmetric magnetic flux density in air-gap, which makes the unbalanced magnetic pull and vibration. The study is focused on the unbalanced magnetic force and their harmonic components according to eccentricity conditions such as static, dynamic and mixed. When the high vibration is produced especially resonance, the obtained results provide clues what eccentricity condition occurs in the machine.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1112-1117
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• 2006

The properties of LTCC green tape with addition of binder were investigated in order to understand an effects of binder on multilayer processing. A green sheet form was fabricated through tape casting method with the MLS-22 powder. The lamination density increased with increasing amount of binder and lamination pressure. With increasing amount of binder, the elongation of ceramic sheets increased but the tensile stress and air-permeability decreased. The addition of excessive binder is caused defects in the green sheet during via hole punching. The optimum condition of the via hole without defects was observed from amount of the binder 10 wt%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.285-288
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• 2007

In the recent years the using of low-density material such as high-strength Al alloy on the various industries is becoming light-weight. High strength and hollow Al alloy is good material for stiffness and recycling. Therefore the advanced manufacturing technology with Al alloy is continuously required in many industrial fields. In this study simplified hallow rectangular section of Al alloy is analyzed by FE analysis. Bending stress is affected punching and rotating of wing-die. The analysis of press bending is preformed at first. The elastic recovery value of component and stress distribution acting from the result of the bending angle of three types were obtained. The designed precesses were analyzed by the commercial FE code, Deform-3D. Forming dies for each process were designed and prototypes were manufactured by the verified forming process. Some of the important features of design parameters in the press bending were reviewed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2212-2218
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• 2015

In order to find out the load bearing behavior of sand and clay which sustain three types of shallow footing, finite element analyses were performed. Failure zone of sand which sustain strip footing was affected by relative density of sand whereas, failure zone of clay was not affected by soil strength and it was similar to the failure zone which is considered in theory. Considering the shape of load-settlement curves obtained by numerical analyses, punching shear failure can be seen in loose sand and ultimate bearing load can not be seen in dense sand whereas, yielding point can be seen in clay. Ultimate bearing loads for sand predicted by theory were greater than those obtained by numerical analyses and ultimate bearing loads for clay predicted by theory were similar to those of numerical analyses. Ultimate bearing loads determined by 1 inch settlement criteria were slightly less than those of numerical analyses.

• Laser Solutions
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• v.11 no.4
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• pp.29-34
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• 2008

Ultraviolet laser micromachining has increasingly been applied to the electronics industry where precision machining of high-density, multi-layer, and multi material components is in a strong demand. Due to the ever-decreasing size of electronic products such as cellular phones, MP3 players, digital cameras, etc., flexible printed circuit board (FPCB), multi-layered with polymers and metals, tends to be thicker. In present, multi-layered FPCBs are being mechanically cut with a punching die. The mechanical cutting of FPCBs causes such defects as burr on layer edges, cracks in terminals, delamination and chipping of layers. In this study, the laser cutting mechanism of FPCB was examined to solve problems related to surface debris and short-circuiting that can be caused by the photo-thermal effect. The laser cutting of PI and FCCL, which are base materials of FPCB, was carried out using a pico-second laser(355nm, 532nm) and nano-second UV laser with adjusting variables such as the average/peak power, scanning speed, cycles, gas and materials. Points which special attention should be paid are that a fast scanning speed, low repetition rate and high peak power are required for precision machining.

• Journal of Mushroom
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• v.6 no.3_4
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• pp.131-137
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• 2008

These experiments were conducted to search for the optimum media size and composition for culture of Lentinula edodes (JNM3022). Considering the incubation period and the successful culturing rate, the optimum media size was length 25 $cm{\times}diameter$ 14 cm (weight 2.5 kg). The saturation moisture amount of Oak sawdust was 251 ml/100 g. It is a half of pine sawdust 495 ml/100 g. Considering the hypha growing speed and hypha density, the optimum media composition was Oak sawdust 80%+ wheat bran 20% and Oak sawdust 80%+ rice bran 20% In 10 treatments of media composition. The optimum moisture amount of media for growing Lentinula edodes (JNM3022) was 55%. Injection pipe with 20 holes in media was reduced the incubation periods to 11 days when 20cm length media and 32 days when 30cm length media compare to control. The best method for browning media surface was change temperature condition above $10^{\circ}C$ and punching the vinyl bag. This treat could shortened the browning periods to 54 days.