• 수산해양기술연구
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• 제30권3호
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• pp.220-226
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• 1994

In this paper the failure mechanisms of polypropylene resin composites filled with calcium carbonate particulates have been studied in the temperature range $-50^{\circ}C$ to $-50^{\circ}C$ The fillers used are both untreated and surface treated with stearic acid. The impact fracture toughness is evaluated from the impact energy absorbed divided by the uncut ligament area of the specimen. Impact fracture toughness increases as temperature is raised whether the fillers are coated or not. The static fracture toughness of these particular composites is evaluated based on the linear clastic fracture toughness of these particular composites is evaluated based on the linear clastic fracture mechanics. Static fracture toughess decreases with increasing temperature whether the fillers are coated or not. An extended stress whitened zone are observed through a large number of availabel sites for cavitation/debonding along particle matrix interface and matrix deformation.

• 공업화학
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• 제27권1호
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• pp.39-44
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• 2016

이 연구에서는 피로인산/암모늄이온, 메틸렌피페라지노메틸-비스-포스폰산, 메틸렌피페라지노메틸-비스-포스폰산/암모늄이온의 화학 첨가제로 처리된 리기다 소나무의 연소 특성을 고찰하였다. 15 wt%의 화학 첨가제 수용액으로 각각 리기다 소나무에 3회 붓칠하여 실온에서 건조시킨 후, 콘칼로리미터(ISO 5660-1)를 이용하여 연소성을 시험하였다. 그 결과, 화학 첨가제로 처리한 시험편의 최대질량감소율도달시간(PMLR time)은 무처리 시험편에 비교하여 10.5~47.4% 지연되었다. 그리고 최대일산화탄소발생률($CO\;_{peak}$)은 무처리 시험편에 비교하여 32.1~71.4% 증가하였다. 또한 총연기방출률(TSRR)은 화학 첨가제로 처리한 시험편이 무처리한 시험편보다 15.6~43.6% 증가하였다. 특히, 단위면적당 연기방출속도(RSR)에 대하여 $PP/4NH_4{^+}$로 처리한 시험편을 제외하고, 무처리 시험편보다 29.4~41.5% 높게 나타났다. 이와 같이 유기성 화학 첨가제로 처리한 시험편은 연소억제 작용에 의하여 연소시간이 길어짐에 따라 연기방출률이 높았다. 그러나 $PP/4NH_4{^+}$은 무기물 첨가제로서 일부 감연 작용을 하는 것으로 보인다. 따라서 화학 첨가제로 처리한 시험편은 무처리 시험편과 비교하여 연소가스 및 연기발생을 부분적으로 증가시켰다.

• 한국의류산업학회지
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• 제17권3호
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• pp.462-475
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• 2015

This paper investigated the characteristics of the physical properties of woven fabrics according to the yarn structure and fibre property. It was found that wicking property of woven fabrics made of sheath/core hybrid yarn were better than those of siro spun and siro-fil hybrid yarns, which was caused by platform for transport of moisture vapor by filaments on the core part of sheath core hybrid yarns. In drying property, the fabric specimen woven by PP/Tencel sheath core hybrid yarns as a warp and Coolmax/Tencel spun yarn as a weft showed quick drying property, which was caused by the sheath core hybrid yarn structure as drainage of water moisture and coolmax fibre characteristics as quick dry material. Concerning to breathability and thermal conductivity as heat transport phenomena, it was observed that breathability of fabrics woven with hybrid yarns such as sheath core and siro-fil in the warp and hi-multi filaments in the weft showed the lowest water vapor resistance, which was explained as due to for air gap in the fibres of the spun yarns to restrict the wet heat transport from perspiration vapor. Thermal conductivities of the fabrics woven with PET/Tencel siro-fil yarns in the weft and hybrid yarns such as sheath core and siro-fil in the warp revealed the highest values, which was observed as due to higher thermal conductivity of PET than PP and more contact point between fibres in the siro-fil and sheath core hybrid yarns.

• 대한토목학회논문집
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• 제29권5A호
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• pp.543-550
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• 2009

본 연구에서는 재활용된 폴리에틸렌 테레프탈레이트(polyethylene terephthalate; PET)로 만든 플라스틱 단섬유의 구조재료로서의 사용 가능성을 조사하였다. 성능을 검증하기 위해서 가장 널리 상용되는 합성섬유인 폴리프로필렌(polypropylene; PP) 섬유와 비교하였으며, 섬유의 혼입률을 0%, 0.5%, 0.75%, 1.0%로 변화시켜 혼입률에 따른 영향을 함께 검토하였다. 실험으로는 압축강도, 쪼갬인장강도 등의 재료 특성과 재생 PET(recycled PET fibers; RPET) 섬유가 혼입된 RC 부재에서의 극한성능과 연성을 평가하기 위해 RC보의 휨 실험을 수행하였다. 실험결과, 압축강도는 섬유의 혼입량이 증가함에 따라 감소하였으나, 기존 PP섬유와 유사하였다. 반면 쪼갬인장강도는 약간 증가하는 경향을 보였다. 구조 부재에 적용하였을 경우에는 RPET을 혼입한 RC 보의 극한강도, 상대 연성비, 에너지 흡수능력이 OPC 시편에 비해 확연히 증가되는 것을 알 수 있었다. 극한 휨강도와 연성비가 증가하는 현상은 PP 섬유를 혼입한 콘크리트에서도 유사하게 나타났다. 따라서 RPET 섬유는 콘크리트 부재의 보강섬유로 유용하게 사용될 수 있을 것이다.

• 한국가축번식학회지
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• 제3권1호
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• pp.36-40
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• 1979

This experiment was conducted to separate X-and Y-bearing spermatozoa of boar semen. The ratio of X-and Y-bearing spermatozoa to total spermatozoa included in ejaculated semen obtained from 4 boars raising at the College of Agriculture, Seoul National University and treated by the sedimentory or electrophoretic technique was estimated. For the electrophoresis, the semen specimen was placed into the co, pp.r loop electrodes in 30cc of glass tube at room temperature for 30 minutes and in order to sedimentary separation, the semen was sedimented in 5$^{\circ}C$ water for 50 minutes. The sperm fluorescent stainning technique was performed by the method of Bhattacharya etal (1976). The results obtained were as follows; 1. Average rate of B-body bearing spermatozoa in normal boar semen was 45.15${\pm}$4.20%, and no significant difference was observed between 1st (44.88${\pm}$6.41%) and 2nd (42.75${\pm}$4.17%) fraction of fractionally collected semen. 2. Spermatozoa were separated into several different fractions by sedimentation. B-body a, pp.arances from the top and bottom fraction were 53.70% and 33.43%, respectively. There were highly significant difference between the top and bottom fractions. 3. The swine spermatozoa were separated into X-and Y-bearing spermatozos by electrophoresis without interferring the sperm motility. The rates of B-body bearing spermatozoa attracted on the anode and cathode were 60.4% and 21.8%, respectively. Highly significant difference betwee two fractions was also observed.

• 콘크리트학회논문집
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• 제20권6호
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• pp.827-832
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• 2008

본 연구에서는 고강도콘크리트의 내화성능 향상을 위해 사용하고 있는 폴리프로필렌섬유와 강섬유 혼입에 따른 설계 강도 60 MPa급 고강도콘크리트 기둥의 내화특성을 평가하였다. 고강도 기둥 콘크리트 공시체의 내화특성 평가를 위하여 ISO-834 가열 곡선을 적용하여 내화실험을 실시하였다. 실험결과 섬유보강재를 혼입하지 않은 경우 폭렬이 심하게 발생하였으며 내부온도도 높게 나타났다. 폴리프로필렌 섬유를 혼입한 고강도콘크리트 기둥 부재의 경우 폭렬이 발생하지 않았으며 내부온도도 섬유보강재를 혼입하지 않은 경우보다 낮게 나타났으나 내부온도 증가에 있어서는 편차가 심해 내부온도 저하에는 큰 효과가 없는 것으로 나타났다. 폴리프로필렌섬유와 강섬유를 혼입한 기둥 공시체의 경우 폭렬이 발생하지 않았으며 가장 낮은 내부온도를 나타내 우수한 내화성능을 나타냈다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.465-468
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• 2008

SHCCs는 섬유와 시멘트 메트릭스 계면의 부착작용으로 인해 높은 에너지 흡수능력을 보여준다. 서로 다른 종류의 섬유로 보강된 SHCCs는 혼입되는 섬유자체가 가지는 재료적 특성 및 물시멘트비에 따라 서로 다른 특성을 나타내기 때문에 SHCCs의 압축, 휨, 직접인장 등의 역학적 특성에 관한 평가가 필요할 것으로 판단된다. 이러한 목적으로 본 연구에서는 PP2.0%, PVA2.0%, PE2.0%의 세종류의 단독섬유를 혼입하여 물시멘트비 0.45, 0.60으로 실험을 실시하였다. 실험결과, PP섬유를 혼입한 시험체에 비해 PVA 및 PE섬유를 혼입한 시험체에서 휨 및 직접인장특성에서 전반적으로 뛰어난 성능을 나타내었다. 또한 동일한 섬유 및 혼입율에서 물시멘트비 0.45인 시험체에서 물시멘트비 0.60인 시험체에 비해 약 2배정도의 높은 압축강도를 나타내었으며, 휨 및 직접인장거동시 시험체 전반에 걸쳐 미세균열이 진전되는 특성을 나타내었다. 따라서 물시멘트비 0.60에서 SHCCs의 시공성능 및 분산성능 향상을 위한 지속적인 연구가 필요할 것으로 사료된다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.217-220
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• 2007

The quality of product depends on a lots of injection molding conditions at each operation stage and mainly was effected by pressure and temperature. The objective of this study was to investigate the relationship between the product quality and the distribution of pressure in a cavity with operation condition change. Specimen having some ribs was designed and the mold was prepared and temperature and pressure sensors were installed in the mold. PP was used and pressure distribution was measured with operation condition change. The relationship between the sink mark and the pressure in a cavity was investigated by measurement of the level of sink mark. The level of sink mark was decreased at the cross of plane and rib by increasing of pressure in a cavity, so the pressure should be controlled properly in order to get the required quality.

• 한국포장학회지
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• 제26권1호
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• pp.25-31
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• 2020

Recently, applications of biomass-based plastics have increased according to the eco-friendly policy of the reduction of carbon dioxide emissions in domestic and foreign government. In this study, a paper plastic composite was produced by compounding polypropylene and micronized paper powder that was prepared using dry pulverization technology. Subsequently, the specimen of paper plastic was verified with mechanical properties, formability and product safety test to confirm the suitable packaging materials for food packaging. Paper plastics showed slightly lower mechanical properties than currently commercialized PP composites. However, paper plastics are valuable materials as environmentally friendly carbon-reducing material because of high biocarbon content, light weight features and applicability of existing manufacturing machines or system.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.26-28
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• 2007

This research is concerned with a study of failure strength evaluation on heat element gap at resistance welding. The failure strength of resistance welded joint is changed by welding factor like as current(power level), welding time(total energy), pressure etc. and another heat element factor like as number of element line, element gap etc. Tensile-shear tests were carried out with the single-lap specimen using polypropylene(PP). The failure mechanism and optimization of gap was discussed in order to explain the tensile-shear strength evaluation on heat element gap at resistance welding. Orthogonal array was used by fractional factorial design for efficient experiments.