• 한국염색가공학회지
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• 제18권3호
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• pp.42-48
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• 2006

The aim of this work is to develop Thick-Thin polyester yarn(T-T yarn) with finer than 1 denier mono filament. The manufacture of T-T yarns were carried out in a draw-winder using 85d/72f PET filament with various spinning speed of 2700, 2900, and 3100 m/min, respectively. The structure and physical properties of T-T yarns with spinning speed and over feed ratio were examined by draw-winder processing the sample in $100^{\circ}C$ water for 20 min and drying in 120, 140, 160, and $180^{\circ}C$ of dry air for 20 min. The crystallinity, the birefringence and the initial elasticity modulus of T-T yarns increased with increased spinning speed of filament and the heat treatment temperature but at the temperatures higher than $140^{\circ}C$ the increased rates show a tendency to decrease. Moreover, the initial modulus and the tenacity of T-T yarns increased with decreasing the over feed ratio of filament and the those of T-T yarns decreases with increasing the heat treatment temperature. The shrinkage of T-T yarns decreased with decreasing spinning speed and increased over feed ratio of filaments. Consequently, the results indicate that the best T-T yarn under 1 denier was optimized from PET filament with spinning speed of 2700 m/min and over feed ratio of 0.67

• 감성과학
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• 제10권2호
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• pp.169-175
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• 2007

본 연구에서는 국내 7개회사와 중국과 대만의 각각 2개회사에서 만든 PET POY 사(絲)의 섬도, 인장역학특성 그리고 열 수축특성 등의 물성편차에 대해 연구하였다. 이를 위해 준비된 시료로서는 239d/96f 중국사와 255d/48f의 국내사를 시료로 사용하였으며 120d 굵기의 중국사와 대만사 두 가지를 국내 6개 기업에서 만들어진 사(絲)와 또한 각각 비교하였다. 그리고 섬도, 인장역학특성 그리고 습열과 건열 수축률 등과 같은 물성 실험은 원사 케이크 내의 사(絲), 50,000m를 1개 층으로 각각 나누어 각각의 층별로 측정하였으며 이들 원사 케이크 내외층의 물성의 편차를 국내 외 원사별로 측정 분석하였다. 이들 결과들은 국내 중소 제직, 사가공 기업에게 고부가가치 고감성 소재를 개발하는데 필요한 기초물성 데이터를 제공해주는 데 큰 의의를 가진다.

• 대한치과보철학회지
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• 제44권6호
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• pp.712-721
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• 2006

Statement of problem. Acrylic resin is most commonly used for denture bases. However, acrylic resin has week points of volumetric shrinkage during polymerization that reduces denture fit. The expandability of POSS (Polyhedral Oligomeric Silsesquioxane) containing polymer could be expected to reduce the polymerization shrinkage of denture bases and would increase the adaptability of the denture to the tissue. Purpose. The purpose of this study was to compare the dimensional stability in the conventional acrylic resin base, POSS-containing acrylic resin base, and metal bases. Materials and methods. Thirty six maxillary edentulous casts and dentures of different base were fabricated. Tooth movement and tissue contour change of denture after processing (resin curing, deflasking, decasting and finishing without polishing) and immersion in artificial saliva at $37^{\circ}C$ for 1 week and 4 weeks were measured using digital measuring microscope and threedimensional laser scanner. Results. The results were as follows: 1. The conventional resin group showed significant (p<0.01) dimensional change throughout the procedure (processing and immersion in artificial saliva). 2. After processing, the metal group and POSS resin group showed lower linear and 3-dimensional change than conventional resin group (p<0.01). 3. There was no statistically significant linear and 3-dimensional change after immersion for 1 week and 4 weeks in metal and POSS resin group. 4. In all groups, the midline and alveolar ridge crest area presented smaller 3-dimensional change compared with vestibule and posterior palatal seal area after processing and soaking in artificial saliva for 1 week and 4 weeks (p<0.01). Conclusion. In this study, a reinforced acrylic-based resin with POSS showed good dimensional stability.

• 콘크리트학회논문집
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• 제13권3호
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• pp.206-212
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• 2001

본 연구는 콘크리트 면처리재 (Concrete Surface Preparator)와 기존의 견출공법에서 사용한 플라스터의 재료적 특성을 비교검토함으로써 콘크리트 면처리재의 사용가능성 및 품질특성을 규명하고자 하였다. 이를 위하여 실험은 콘크리트 면처리재와 기존의 견출공법에 사용되는 시멘트에 혼화제를 첨가한 플라스터를 사용하여 KS F 4716에 규정하고 있는 시험방법에 의하여 실험을 실시하여 콘크리트 면처리재와 플라스터의 성능비교 및 KS에서 제시하고 있는 성능기준의 만족여부를 고찰하여 그 활용가능성을 검토하였다. 그 결과 다음과 같은 결과를 얻었다. 콘크리트 면처리재는 초기 건조수축에 의한 잔갈림과 균열의 발생이 없어, 기존 견출공사에 비해 우수한 것으로 나타났다. 콘크리트 면처리재는 기존 시멘트 페이스트를 사용한 경우보다 1.6배 높은 부착강도를 나타냈다. 콘크리트 면처리재는 표면의 평활도 및 마무리 정도가 기존 견출공사에 비해 우수하였으며 콘크리트 바탕바름제의 규정 모두를 만족하는 것으로 나타났다. 이와 같이 콘크리트 면처리재는 기존의 견출공사에서 사용되는 혼화제를 혼입한 시멘트 페이스트보다 재료적 특성면에서 우수한 재료로 판단된다.

• Journal of the Korean Wood Science and Technology
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• 제2권1호
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• pp.3-18
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• 1974

The exports of plywood are increasing annually and it has ranked first in the world market because of the high quality product and manufactured using mordern techniques. However, it is known that the exports of the other wood products, except plywood, is inactive because of their low quality. Accordingly, to increase the exports of various wood products investigations were carried out on kiln drying techniques to improve the quality of the wood. Wet wood should be kiln dried before use to prevent various drying defects such as distortion, shrinkage etc., which would develop after processing,:and also wet wood is not suitable for cutting, gluing and finishing. Therefore, the kiln drying properties of lumber from such species as oak, ramin and meranti which are used in large quantity for manufacturing exporting wood products have been studied. The results of the research are summarized as follows. (1) The end checks and the time for drying from initial moisture content of about 40 percent to 5 percent moisture content in ovendry were investigated as follows: (2) The kiln dried results, for 30mm stock, which are presented by using kiln schedule table 3 are as follows: (3) The kiln schedules for ramin, meranti and oak are given respectively as follows: Ramin kiln schedule: Table 17 and Table 18. Meranti schedule : Table 12. Oak schedule : Table 15.

• 한국염색가공학회지
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• 제6권2호
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• pp.47-54
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• 1994

Cotton fiber, NaOH-mercerized cotton fiber, cotton fabric, and NaOH-mercerized cotton fabric have been treated by liquid ammonia at -33.4$^{\circ}C$. The fine structures, bending properties, tensile strengthes, shrinkages for laundering, and wrinkle recoveries were studied. The treatment of cottons with liquid ammonia brought about the transition of crystal lattice ; transforming cellulose I crystal of original cotton to cellulose I and III crystal, and cellulose II crystal of mercerized cotton to cellulose II and III crystals. The degree of crystallinities were decreased in the order of liquid ammonia>NaOH/liquid ammonia>NaOH-treated cotton. However moisture regain and water absorbency for liquid ammonia-treated cotton were lower than that of NaOH-treated cotton because of a difference in swelling actions of the agents. It seems caused by intermicrofibrillar pores produced in swelling processes. The bending rigidity and bending hysteresis were decreased remarkly by liquid ammonia treatment. Therefore softness and dimensional stability were improved. The liquid amminia and NaOH/liquid ammonia-treated cottons moreover show excellent properties in tensile strength, anti-shrinkage for laundering, and wrinkle recovery.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1067-1070
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• 2008

DuPont Teijin FilmsTM have developed engineered substrates for flexible electronics. Teonex(R) Q65 and Melinex(R) ST506/5004 are biaxially oriented semi-crystalline polyesters. Smooth planarised Teonex(R) Q65 and Melinex(R) ST506/504 emerge as suitable substrate materials for display backplanes and frontplanes. This contribution discusses the impact of applying a planariser coating to these films. Also, the effect of a more controlled finishing process treatment upon film shrinkage and CLTE is presented.

• 한국염색가공학회지
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• 제15권2호
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• pp.59-67
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• 2003

PTT[poly(trimethylene terephthalate)] fiber was annealed by passing on the plate heater to illuminate the effects of annealing on the mechanical properties and dyeability with varying the treatment temperature for 0.5 second. The apparent crystal sizes and crystallinity were increased with increases in temperature. With the increases of the temperature, the dynamic viscoelastic behaviors were analyzed to be reduction in $T_{max} (tan{\delta})$. The initial modulus were observed to be a small enhanced. The shrinkage in hot water were reduced. The dyeability for disperse dye enhanced dramatically, for example, a satisfactory degree of exhaustion was obtained by dyeing at $95^\circ{C}$ for 30 min with the PTT fibers heat treated at $180^\circ{C}$.

• 한국염색가공학회지
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• 제11권1호
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• pp.34-41
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• 1999

To examine the increase of paper strength by solvent-bonding using N-methylmorpholine N-oxide (NMMO), a paper was treated with aqueous solutions of NMMO, concentrated at $90^\circ{C}$ for selected periods of time, and pressed for 5 seconds followed by washing and drying. The effect of the increasing NMMO concentration on bonding state and some important properties of samples were mainly investigated. With increasing concentration of NMMO, the degree of bonding between fibers was increased, the fiber cross-sectional shape was changed from 'thin ribbonlike' to 'round rodlike' by swelling with solvent, and the longitudinal waves (crimp) were introduced to fibers, hence the shrinkage, weight per unit area, and thickness of paper were increased. Consequently, the tensile strength and elongation, under standard and wet conditions, and the stiffness were increased, and the water absorption was decreased generally with increasing concentration of NMMO. The moisture regain of treated samples was lower than that of the untreated sample, because of the reduction of space between fibers. But the moisture regain was increased a little with increasing concentration of NMMO due to the fiber swelling with NMMO followed by structural relaxation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.274-278
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• 2002

Surface finishing is still indispensable for most rapid prototyping (RP) processes because of the inherent stair-stepped surface and shrinkage of the parts. These problems can be minimized in the $VLM-_ST$ Process, because it uses expandable polystyrene foam sheets, each of which has a thickness of3.9 mm and a linear-interpolated side slope. The use of thick layers, however, limits the process capability of constructing fine details. This study focuses on the design of post-processing tool for fine details of $VLM-_ST$ parts and investigation of thermal characteristics during EPS foam cutting using the post-processing tool. To calculate the heat flux from the tool into the foam sheet, the tool was modeled as a heat source of radiation for finite element analysis. Results of the analysis agreed well with those of the experiment.