• 품질경영학회지
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• 제25권1호
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• pp.173-181
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• 1997

A modified periodic inspection policy is examined. It is troublesome to know the life distribution and burdensome to compute an optimum planned inspection time numerically as well. A nonparametric a, pp.oximation is used so that equations for the optimum inspection time are expressed as closed forms. To show that the a, pp.oximation can be used in practice, simulations are conducted in the case of Weibull failure times.

• 한국염색가공학회지
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• 제11권2호
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• pp.27-37
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• 1999

Polypropylene(PP) films were treated with plasma glow discharge to produce peroxy radicals on the surfaces. The peroxy radicals formed on the PP film surfaces were subsequently used for the graft polymerization of acrylic acid and acrylamide in an aqueous solution by heating, respectively. Introduction of acrylic acid and acrylamide on the PP film could be confirmed by the observation of carbonyl and primary amine absorptions based on carboxylic acid and amide, respectively. And introduction of functional group could be confirmed by weight analysis and ESCA. The water contact angle(90$^{\circ}$) of PP film was constant, irrespective of elapsed time, while plasma-treated and functional monomer-grafted PP films were slowly increased with elapsed time, showing the rearrangement of surface polar groups in air condition. The water contact angle$(90^\circ)$ of PP film was decreased by the plasma treatment$(56^\circ)$ and further decreased by the grafting of acrylic acid$(34^\circ)$ and acrylamide$(37^\circ)$, indicating increased hydrophilicity of the modified surfaces. The water contact angle of plasma-treated PP film increased a little as time elapsing. The half-life periods of surface voltage on acrylic acid-(31sec) and acrylamide-grafted PP(42sec) were significantly decreased when compared to those on PP(950sec) and plasma-treated PP film(241sec). In the experiments using acid, basic and disperse dyes, absorbance and $\Delta{E}$ values of functional monomer-grafted PP films were significantly increased than that of oxygen plasma-treated one.

• 한국건축시공학회지
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• 제23권2호
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• pp.133-142
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• 2023

본 연구에서는 열화 콘크리트 구조물의 보수 시 현재 범용적으로 사용하고 있는 폴리머 시멘트 모르타르의 내화성능을 확보하기 위한 최적 배합을 도출하고자 폴리머 혼입량(2, 4, 6, 8%)에 따른 PP섬유의 길이(6, 12mm) 및 PP섬유 혼입량(0.05, 0.1Vol%)에 따른 섬유혼입 폴리머 시멘트 모르타르의 내화성능을 평가하였다. 실험결과 함수율 및 폴리머 혼입률이 높을수록 폭렬발생 가능성이 증가하며, PP섬유의 길이가 길고 혼입률이 증가할수록 폭렬저감에 효과적인 것으로 나타났다.

• 한국레이저가공학회지
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• 제9권3호
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• pp.15-21
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• 2006

A Polypropylene (PP) film was ablated using a femtosecond laser with a center wavelength of 785 nm, a pulse width of 184 fs and a repetition rate of 1 kHz. Increments of both pulse energy and the shot number of pulses lead to co-occurrence of photochemical and thermal effect, demonstrated by the spatial expansion of rim on the surface of PP. The shapes of the laser-ablated PP films were imaged by a scanning electron microscope (SEM) and measured a 3D optical measurement system (NanoFocus). And, the oxygen transmission rate (ORT) of periodically laser-ablated PP film were characterized by oxygen permeability tester for modified atmosphere packaging (MAP) of fresh fruit and vegetable. Our results demonstrate that femtosecond pulsed laser is efficient tools for breathable packaging films in modifying the flow of air and gas into and out of a fresh produce container, where the micropatterns are specifically tailored in size, location and number which are easily controlled by laser pulse energy and pulse patterning system.

• Transactions on Electrical and Electronic Materials
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• 제12권3호
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• pp.110-114
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• 2011

Polymeric films of high chemical stability and mechanical strength covered with a thin metallic film have been extensively used in various fields as electric and electronic materials. In this study, we have chosen polypropylene (PP) as the polymer due to its outstanding chemical resistance and good creep resistance. We coated thin nickel film on PP films by the electroless plating process. The surfaces of PP films were pre-treated and modified to increase the adhesion strength of metal layer on PP films, prior to the plating process, by an environment-friendly process with atmospheric plasma generated using dielectric barrier discharges in air. The surface morphologies of the PP films were observed before and after the surface modification process using a scanning electron microscope (SEM). The static contact angles were measured with deionized water droplets. The cross-sectional images of the PP films coated with thin metal film were taken with SEM to see the combined state between metallic and PP films. The adhesion strength of the metallic thin films on the PP films was confirmed by the thermal shock test and the cross-cutting and peel test. In conclusion, we made a composite material of metallic and polymeric films of high adhesion strength.

• 농업생명과학연구
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• 제50권1호
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• pp.155-165
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• 2016

The study investigated the effects of adding bovine plasma protein(PP) hydrolysates on the quality properties of cooked pork patties. Pork patties were prepared as follows: manufactured with pork back-fat(control); replacement of back-fat with 40% olive oil(T1), 40% olive oil and 2% PP hydrolysates(T2), and 40% olive oil and 4% PP hydrolysates(T3). The olive oil modified the fatty acid profiles of the pork patties by lowering the saturated fatty acids(SFAs) percentage. Olive oil and 4% PP hydrolysates addition reduced the level of 2-thiobarbituric acid-reactive substance(TBARS) values in pork patties, compared to the controls. Furthermore, the pork patties with added PP hydrolysates had higher pH values than the control. All samples containing olive oil and PP hydrolysates had increased levels of DPPH radical scavenging activity. In particular, added PP hydrolysates were more effective in increasing antioxidant activity than were the other treatments. Therefore, PP hydrolysates could be used as a natural antioxidative in cooked pork patties.

• Fibers and Polymers
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• 제4권4호
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• pp.210-214
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• 2003

Siloxylated polypropylene fibers composed of polypropylene (PP) and aluminosiloxane (AS) were prepared by melt blending followed by spinning. The effects of blend compositions on the thermal behaviors, surface and tensile properties of PP/AS blend fibers were investigated by DSC, WAXD, SEM, static honestometer, etc. The heat of fusion of PP/AS blends decreased with increasing AS contents. In addition, the peak intensity of PP/AS blends in X-ray diffraction patterns decreased with increasing AS contents. It was observed that the silicone molecules exist and well distribute on the surface of siloxylated polypropylene fibers. From the results of the half-life period measurements, the anti-static properties of PP fibers siloxylated with AS was found to be significantly modified.

• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.52-60
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• 2015

The present study aims to the use of carboxymenthyl cellulose (CMC) improving the ability of fiber in the dyeing process. Cellulose was extracted from banana leaves by NaOH and then modified by reacting with chloroacetic acid to obtain the carboxymenthyl cellulose. The effect of carboxymenthyl cellulose contents on the mechanical properties and dye absorption were also investigated. Then, CMC were blend with polypropylene (grade 561R) at 1%, 3% and 5% by weight ratio. The fibers were obtained from single screw extruder. The results show that the mechanical properties of the product decreased when increased the amount of CMC in the fiber product. After dyeing, the dye however were absorbed by the CMC-PP fibers more than the original PP fibers. The absorption of dye on the CMC-PP fibers increased significantly with the CMC ratio.

• Journal of the Korean Data and Information Science Society
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• 제10권2호
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• pp.341-357
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• 1999

Greenwich and Jahr-Schaffrath(1995) considered a new process incapability index(PII) $C_{pp}$, which modified the useful index $C^{\ast}_{pm}{$ for detecting assignable causes. The new index $C_{pp}$ provides an uncontaminated separation between information concerning the process accuracy and precision while this kind of information separation is not available with the $C^{\ast}_{pm}$ index. In this paper, we will study about the index $C_{pp}$ based on the bootstrap. First, we will prove the consistency of bootstrap deriving the bootstrap asymptotic distribution for our index $C_{pp}$. Moreover, with the consistency of bootstrap, we will construct six bootstrap confidence intervals and compare their performances. Some simulation results, comparison and analysis are provided. In particular, two STUD and ABC bootstrap methods perform significantly better.

• 지능정보연구
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• 제3권1호
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• pp.47-68
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• 1997

This paper discusses a method of modified Elman network(1990) for nonlinear predictions and its a, pp.ication to forecasting daily exchange rate returns. The method consists of two stages that take advantages of both time domain filter and modified feedback networks. The first stage straightforwardly employs the filtering technique to remove extreme noise. In the second stage neural networks are designed to take the feedback from both hidden-layer units and the deviation of outputs from target values during learning. This combined feedback can be exploited to transfer unconsidered information on errors into the network system and, consequently, would improve predictions. The method a, pp.ars to dominate linear ARMA models and standard dynamic neural networks in one-step-ahead forecasting exchange rate returns.