• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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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

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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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.

• 농업생명과학연구
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• 제50권5호
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• pp.217-224
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• 2016

본 연구에서 개발된 자동천공기는 콩의 재식밀도를 고려한 비닐 천공능력이 작업주행속도 0.18-0.28m/s 조건에서 콩의 주간거리 0.20m, 0.25m, 0.30m에 대해 각각 320-500㎡/h, 260-400㎡/h, 210-330㎡/h의 범위로 나타났다. 천공율은 칼날과 지면간 30mm 거리에서 비닐이 100% 천공되었으며, 50mm 거리에서 원형칼날 16.7-25.2%, 사각칼날 33.0-42.3%, 육각칼날 54.5-100.0% 범위에서 천공되었다. 또한, 육각칼날 60°에서 비닐 절단면이 매끄럽고 부드러워 절단품질이 가장 우수하였다.

• Elastomers and Composites
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• 제57권4호
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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.

• 전기학회논문지
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• 제60권12호
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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.

• 한국전기전자재료학회논문지
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• 제19권12호
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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%.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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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.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.2212-2218
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• 2015

세 종류의 얕은기초를 지지하는 기초지반의 하중지지거동을 살펴보고자 모래지반과 점토지반을 가정하여 유한요소 해석을 수행하였다. 띠기초를 지지하는 모래지반의 파괴영역의 형상 및 크기는 상대밀도에 따라 달랐으나 점토지반의 경우 강도에 따라 파괴영역에 차이가 거의 없으며 이론에서 고려되는 파괴영역과 유사한 결과를 보였다. 모래지반에 대한 수치해석을 통해 얻은 하중-침하곡선의 형상을 고려해 볼 때 느슨한 모래에 놓인 기초의 경우 거의 관입전단파괴양상을 보였으며 조밀한 모래에 놓인 기초의 경우 극한하중이 뚜렷하지는 않았다. 점토지반에 놓인 기초에 대하여 수치해석을 통해 얻은 하중-침하량곡선의 경우 침하가 급격하게 증가하는 항복점이 존재함을 알 수 있었다. 모래지반에 의해 지지되는 기초에 대해 이론식에 의해 예측된 극한하중은 수치해석에 의한 극한하중보다 큰 값을 보였으며 점토지반에 대해 이론식에 의해 예측된 극한하중은 수치해석에 의한 극한하중과 유사한 값을 보였다. 1 인치 침하기준법에 의해 결정된 극한하중은 수치해석을 통해 얻은 극한하중보다 약간 작은 값을 보여 안전측의 결과를 보였다.

• 한국레이저가공학회지
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• 제11권4호
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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.

• 한국버섯학회지
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• 제6권3_4호
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• pp.131-137
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• 2008

표고버섯(J NM3022) 의 톱밥재배시 적절한 배지크기 및 배지조성을 구명하기 위하여 '05년부터 2년동안 시험결과 다음과 같은 결과를 얻었다. 표고버섯 톱밥재배를 위하여 배지길이와 직경이 다른 12가지 크기의 배지를 이용하여 배양기간, 배양완성률을 시험한 결과 가장 적절한 배지크기는 길이 25 cm ${\times}$ 직경 14cm, 무게 2.5 kg 배지였다. 소나무톱밥의 포화수분함량은 495 $m{\ell}/100g$으로 침 나무동밥 251 $m{\ell}/100g$보다 약 2배 많았다. 참나무톱밥 100% 등 10조합의 배지조성 중 균사생장속도와 균사일도가 가장 좋았던 배지조성은 참나무톱밥 80%+밀기울 20%와 참나무톱밥 80%+미강 20% 처리였으며, 가장 적합한 배지수분함량은 55%였다. 배양기간을 단축하기 위하여 배지중앙에 유공관을 설치하였을 때 무처리에 비하여 길이 20 cm 배지는 11일, 30 cm 배지는 32일을 단축할 수 있었다. 배지표면 갈변화에 가장 좋았던 처리는 $10^{\circ}C$ 정도의 변온과 봉지천공으로 갈변 소요기간은 35일로 동일조건의 무천공처리에 비하여 54일을 단축시킬 수 있었다.