• 한국산림과학회지
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• 제77권2호
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• pp.252-257
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• 1988

목질(木質)플레이크 및 P.P망(網)플레이크를 톱밥보오드에 혼합하여 그 효과를 보고자 크기를 $1{\times}1cm^2$, $1.5{\times}1.5cm^2$, $1{\times}2cm^2$로 절단하고, 혼합량을 1%, 2%, 3%, 4%로하여 보오드를 제조(製造)하여 그 물리적(物理的) 및 기계적(機械的) 특성(特性)을 조사고찰(調査考察)한 바, 그 결론(結論)을 간단히 지으면 다음과 같다. 1) 플레이크를 혼합한 톱밥보오드의 두께 팽창율(膨脹率)은 혼합비가 증가함에 따라 감소(減少)하였고 P.P망(網)플레이크를 혼합한 경우에도 같은 양상을 보여주었다. 2) 휨파괴계수(破壞係數)는 플레이크 및 P.P망(網)플레이크의 혼합비가 증가할수록 증가하였다. 플레이크 크기가 $1{\times}2cm^2$인 경우 모두 대조보오드보다 높은 값을 나타내었고 P.P망(網)플레이크의 경우에는 $1.5{\times}1.5cm^2$ 크기일때 대조보오드보다 모두 높은 휨파괴계수치(破壞係數値)를 보였다. 3) 플레이크 혼합비가 증가함에 따라 휨탄성계수(彈性係數)는 증가하는 경향을 보여주었으며, 이러한 경향은 P.P망(網)플레이크를 혼합한 경우에도 동일하게 나타났다. P.P망(網)플레이크의 경우 망(網)플레이크의 면적이 커짐에 따라 휨탄성계수(彈性係數)는 증가하는 경향을 나타내었다. 4) 플레이크를 혼합한 보오드의 경우, 그 물리적(物理的), 기계적(機械的) 성질(性質)에 관여하는 주인자는 형상(形狀)으로 나타났으며, aspect ratio가 커짐에 따라 보오드의 성질(性質)이 향상되었다. P.P망(網)플레이크를 혼합한 보오드의 경우 주인자는 망(網)플레이크의 단면적으로, 단면적이 클수록 보오드의 성질(性質)을 개선(改善)시킬 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제15권3호
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• pp.44-55
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• 1987

In order to study the effect of sawdustboard combined with plastic chips, 0.5mm($T_1$), 1mm($T_2$), 1.4mm($T_3$) thick nylon fiber. polypropylene rope fiber(RP), and 0.23mm thick moth-proof polypropylene net fiber(NP) were cut into 0.5, 1, 2cm long plastic chips. Thereafter, sawdustboard combined with plastic chips prepared as the above and plastic non-combined sawdustboard(control) were manufactured into 3 types of one-, two-, and three layer with 5 or 10% combination level. By the discussions and results at this study, the significant conclusions of mechanical and physical properties were summarized as follows: 1. The MORs were shown in the order of 3 layer> 2 layer> 1 layer among plastic non-combined boards, and $T_3$ < $T_2$ < $T_1$ < RP (NP(5%) < NP(l0%) among plastic combined boards. In 2cm long plastic chip in 1 layer board, the highest strength through all the composition was recognized. 1 layer board showing the lower strength with 0.5cm plastic chip rendered to the bending strength improvement by 2 or 3 layer board composition. On the other hand, 2 or 3 layer combined with 1, 2cm long polypropylene net fiber chips incurred MOR's conspicuous decrease requiring optimum plastic chip combined level and consideration to combined type. 2. MOE in plastic non-combined 3 layer board exhibited sandwich construction effect by higher resin content application to surface layer in the order of 3layer>1layer>2layer with the highest stiffness of the board combined with polypropylene chip, while nylon chip-combined board had little difference from plastic non-combined board. In relevant to length and layer effect, 3 layer board combined with the 0.5cm long polypropylene net fiber chip in 5% and 10% combined level presented 34-43% and 44-76% stiffness increase against plastic non-combined board(control), respectively. Moreover, in 1 layer board, 30% stiffness increase with 10% against 5% combined level in the 1 and 2cm long polypropylene net fiber chip was obtained. 3. Stress at proportional limit(Spl) showing the fiber relationship (r: 0.81-0.97) between MOR presented in the order of 1 layer<2 layer<3 layer in plastic non-combined board. Correspondingly, combined effect by layer and plastic chip length was similar to MOR's. 4. Differently from previous properties(MOR, MOE, Spl). work to maximum load(Wml) of 2 layer board approached to that of 3 layer board. Conforming the above phenomenon. 2 layer combined with 0.5cm long polypropylene net fiber chip kept the greater work than 1 layer. The polypropylene combined board superior to nylon -and plastic non - combined board seemed to have greater anti - failing capacity. 5. Internal bond strength(IB), in contrast to MOR's tendency. showed in the order of T1

• 한국구조물진단유지관리공학회 논문집
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• 제6권2호
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• pp.225-231
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• 2002

Severe cracks on Reinforced Concrete (RC) structures caused by structural displacement can be often one of the main reasons for the degradation of tensile and flexural rigidities of RC structures and for the deterioration of durability and serviceability of RC structures through accelerated steel corrosion. These combined factors adversely affect the performance of RC concrete, leading to shortened life time of RC structures. In consideration of these problems, we conducted 3 point bending experiments by employing three different types of concrete specimens: fiber-net reinforced concrete (FNRC), polypropylene-fiber reinforced concrete (PFRC), and plain concrete (PC). FNRC is well known for its strong corrosion resistance, light self-weight, and excellent tensile strength, while PFRC is known to be effective in crack control. FNRC was found to have the best first and final crack resistances followed by PFRC and PC, as evidenced by the highest initial crack load and the smallest final crack width, respectively. The FNRC specimens with various tensile strength of fiber net exhibited greater ultimate strengths than those for PFRC and PC. Furthermore, the crack widths of FNRC specimens were smaller than those calculated by the crack-width estimation equation of the KCI and ACI code. Therefore, we conclude that fiber net reinforcement is effective not only on crack control, but also on loading share.

• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.55-69
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• 1995

The primary objective of this research was to investigate optimum manufacturing condition of thin composite panels composed of sawdust, polyethylene film and polypropylene net. At the study the experiment was designed to make thin board in which sawdust offers effectiveness as core composing material, polyethylene as adhesive with added urea resin, and polypropylene as stiffness and flexibility in the composition panel. 100 types of thin composite panels were manufactured according to press-lam and mat-forming process of various hot pressing conditions(pressure, temperature and time). They were tested and compared with control boards on bending properties(MOR, MOE, SPL, WML), internal bond strength, thickness swelling, linear expansion and water absorption. At the same time the visual inspections of each types of panels were accomplished. The physical and mechanical properties of composite types passed by visual inspection were analyzed by Tukey's studentized range test. From the statistical analysis, the optimum manufacturing condition of thin composite panels were selected. Compared with two manufacturing processes, mat-forming process performed better than press-lam process in all tested properties. The optimum manufacturing conditions resulted from the experiment and statistical analysis were able to determine as following: the press temperature was shown the most good result at 130$^{\circ}C$ in mat forming process and 140$^{\circ}C$ press lam process, the press time 4 min in both processes, but the press pressure was 25-10kg/$cm^2$ in mat forming and 15k/$cm^2$ press lam process.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.813-820
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• 2003

The shear friction tests using large direct shear test units were performed to evaluate the friction properties of fiber-mixed soil. The used materials and test conditions were flowing. Soils : SM and ML; mixing fibers : three types of polypropylene fibers(net type 38mm and 60mm, and line type 60mm), reinforcement : geogrid; mixing ratio：0.2% and 0.3%; degree of compaction : 85% and 95%. In the test results, the reinforcing effect of fiber mixed soil was confirmed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.391-396
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• 2001

Exposed concrete execution is utilized insufficiently due to surface honecomb and undesirable appearance by entrapped air when existing placing method is applied. Therefore, surface glossing and impact properties of cement mortar incorporating fiber glass net blast furnace slag, expansive admixture and Polypropylene fiber are investigated in order to develop precast exposed concrete pannel by dry construction method. The kinds of the forms, placing method and admixture contents are varied. According to test results, surface glossing decrease with elapse of age. Considering the form kinds, surface glossing with acryle + astage shows the best performance. Placing horizontally shows positive results in reducing surface defects such as honecomb. Impacting resistance shows the best performance when glass fiber net applied, due to the enhance in toughness and absorption of impact.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.223-236
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• 2013

In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber.

• Composites Research
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• 제23권6호
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• pp.55-60
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• 2010

본 연구에서는 열가소성 복합재료인 유리섬유/폴리프로필렌 복합재료를 이용한 복합재료 고정판의 적절한 성형조건을 찾기 위해 다양한 성형조건으로 제작된 시편의 인장실험과 굽힘실험을 수행하여 성형조건에 따른 기계적 거동을 비교하였다. 실험 결과 성형온도와 압력이 각각 $230^{\circ}C$, 3MPa일 때 가장 우수한 기계적 특성을 가짐을 확인하였다. 성형실험을 통해 결정된 성형조건을 이용한 복합재료 고정판의 성형방법으로는 고정판의 스크류 구멍을 한번에 성형하는 정형성형방법과 스크류 구멍을 후가공하는 방법을 사용하였으며, 성형실험과 굽힘실험 결과 스크류 구멍을 후가공 하는 경우 우수한 굽힘특성을 가지는 것을 확인하였다. 본 논문에서는 복합재료 고정판의 적절한 성형을 위해 유리섬유/폴리프로필렌 복합재료의 기초 성형정보와 그에 따른 고정판 성형에 대한 연구를 수행하였으며, 이 결과는 해당재료를 이용한 구조물 성형에 중요한 정보를 제공할 것으로 기대된다.

• 수산해양기술연구
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• 제16권1호
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• pp.23-26
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• 1980

The pure polypropylen rope has been used for the head rope, and the lead cored polypropylen rope for the ground rope in the anchovy boat seine. These ropes revealed the disadvantage that deforms the net shape due to their elongation. Te improve the disadvantage, authors developed the rope of new construction which is cored by wires and wrapped by polypropylene fibers, 20mm in diameter for the head rope and 40tnm for the ground rope. To compare the physical properties of the improved rope with the conventional ones, some factors are valued and the following results are found. 1. The improved ropes rev~al some disadvantages, such as the head rope is heavier, the ground rope lighter, and both of them are stiffer than the conventional ones, contrary to the required condition of ropes) However no special difficulties are found in practical use. 2. The improved ropes display much advantages, such as elongation is 30 percent less, breaking strength is 35 precent greater, and elastic recovery is 10 percent greater than the conventional ones. Thus, it is considered that the improved ropes are more suitable for the head rope and the ground rope of the anchouy boat seine net than the conventional ones.

• 한국식품영양과학회지
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• 제40권3호
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• pp.475-479
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• 2011

생배추의 저온저장에 적합한 용기 및 기간을 살펴보고자, polypropylene 재질의 상자, polypropylene 재질의 그물망, high density polyethylene 재질의 컨테이너에 생배추를 담아 2달간 보관하였다. High density polyethylene 재질의 컨테이너에 담아 보관한 생배추의 폐기율이 가장 낮아 이것이 가장 효율적인 보관 용기인 것으로 보이며, 저장기간은 배추의 폐기율 및 보관비용 등을 고려했을 때 1달 이상이 되는 것은 바람직하지 않을 것으로 보인다. 저장기간이 다른 생배추로 절임배추를 제조하여 그 품질 특성을 살펴본 결과, 생배추로의 저장기간 없이 바로 절여서 만든 절임배추는 8주차 때 pH 4.0~4.3, 총균 및 유산균 $10^7$ cfu/g 이상, 탄력성 50% 이하를 나타내고, 8주차가 지나면서 변질이 상당히 진행되어 이의 저장 한계는 약 8주 이내인 것으로 사료된다. 1달, 2달간 저장한 생배추로 제조한 절임배추는 pH, 염도, 미생물, 탄력성 모두 생배추로의 저장기간 없이 바로 절여서 만든 절임배추의 경우와 비슷한 양상으로 변화하나 저장기간이 길어질수록 품질 저하가 보다 빠른 것으로 나타나, 저장 한계는 각각 약 6주와 4주 이내인 것으로 생각된다. 따라서 절임배추의 품질 측면을 고려하였을 때도 저장기간이 긴 생배추를 사용하는 것은 바람직하지 않으며, 생배추로서의 저장기간은 약 1달, 이를 이용한 절임배추로의 저장기간은 약 6주 정도가 가능한 것으로 보인다.