• 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

• 대한인간공학회지
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• 제21권2호
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• pp.71-86
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• 2002

This study's purpose is to gain basic data for the factory automation of manufacturing custom-made girdles. For this study , obese women in their 30s and 40s was experimented through direct measuring and by the 3D scanner, by means of which the proportions of the subject's body was measured. Based upon the results of this experiment, individually designed girdles were made. In order to gain the basic data for the factory automation of manufacturing custom-made girdles, the patterns and the clothing pressure and the feeling of wearing such girdles were analyzed. This study can be summarized as follows: The material properties and the designs of existing functional girdles in the market were studied thoroughly, and the subject were required to wear those existing girdles. On the basis of this result, the experimental girdles were designed and produced which could serve well the subject's intension. The experimental girdles were of the basic long-type in order to apply to all sorts of girdles, and they were produced according to the style and pattern of the existing grading system. The second experiment was conducted by applying the subject's body measurements. Due to the elasticity of the material, in girdles the smaller measurements were to be used in this second experiment were: 80% of waist size, 84% of the hip and 85% of the thigh. To determine the length of the girdles, the same measurements were applied. The test results of the feeling of wearing the experimental girdles showed that the second, custom-made experimental girdles were better. According to the test results of the clothing pressure, the second experimental girdles(custom-made girdles) marked the higher pressure than the first on every part of the body, especially on the hips and thighs. Thus, it can be said that the second experimental girdles are better than the first in lifting up the hips. It is expected that the design methods developed in this study can be utilized as basic resources for the factory automation system of manufacturing custom-made girdles.

• Structural Engineering and Mechanics
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• 제74권2호
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• pp.227-241
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• 2020

The bi-axial and shear buckling behavior of laminated hypar shells having rhombic planforms are studied for various boundary conditions using the present mathematical model. In the present mathematical model, the variation of transverse shear stresses is represented by a second-order function across the thickness and the cross curvature effect in hypar shells is also included via strain relations. The transverse shear stresses free condition at the shell top and bottom surfaces are also satisfied. In this mathematical model having a realistic second-order distribution of transverse shear strains across the thickness of the shell requires unknown parameters only at the reference plane. For generality in the present analysis, nine nodes curved isoparametric element is used. So far, there exists no solution for the bi-axial and shear buckling problem of laminated composite rhombic (skew) hypar shells. As no result is available for the present problem, the present model is compared with suitable published results (experimental, FEM, analytical and 3D elasticity) and then it is extended to analyze bi-axial and shear buckling of laminated composite rhombic hypar shells. A C⁰ finite element (FE) coding in FORTRAN is developed to generate many new results for different boundary conditions, skew angles, lamination schemes, etc. It is seen that the dimensionless buckling load of rhombic hypar increases with an increase in c/a ratio (curvature). Between symmetric and anti-symmetric laminations, the symmetric laminates have a relatively higher value of dimensionless buckling load. The dimensionless buckling load of the hypar shell increases with an increase in skew angle.

• Computers and Concrete
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• 제20권4호
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• pp.391-407
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• 2017

Fiber reinforced polymer (FRP) bars have been recently used to reinforce concrete members in flexure due to their high tensile strength and especially in corrosive environments to improve the durability of concrete structures. However, FRPs have a low modulus of elasticity and a linear elastic behavior up to rupture, thus reinforced concrete (RC) components with such materials would exhibit a less ductility in comparison with steel reinforcement at the similar members. There were several studies showed the behavior of concrete beams with the hybrid combination of steel and FRP longitudinal reinforcement by adopting the experimental and numerical programs. The current study presents a numerical and analytical investigation based on the data of previous researches. Three-dimensional (3D) finite element (FE) models of beams by using ANSYS are built and investigated. In addition, this study also discusses on the design methods for hybrid FRP-steel beams in terms of ultimate moment capacity, load-deflection response, crack width, and ductility. The effects of the reinforcement ratio, concrete compressive strength, arrangement of reinforcement, and the length of FRP bars on the mechanical performance of hybrid beams are considered as a parametric study by means of FE method. The results obtained from this study are compared and verified with the experimental and numerical data of the literature. This study provides insight into the mechanical performances of hybrid FRP-steel RC beams, builds the reliable FE models which can be used to predict the structural behavior of hybrid RC beams, offers a rational design method together with an useful database to evaluate the ductility for concrete beams with the combination of FRP and steel reinforcement, and motivates the further development in the future research by applying parametric study.

• Journal of Biosystems Engineering
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• 제17권2호
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• pp.156-170
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• 1992

The force-deformation relationship gives the basic physical properties of the fruits such as the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point. These informations are very important to study the stress-strain relationships of the fruits. This study was conducted to analyze those physical properties according to the sampling position of the fruits, and to determine the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point of the fruits for two different storage conditions(low temperature and normal temperature) and the storage period, and to investigate the effect of loading rate on those physical properties, the hysteresis on the loading-unloading condition and the degree of elasticity of the fruits. The results of the study were as follows : 1. The physical properties(BS, US, BD, and RD) of the test specimen selected from the different sampling positions were quite different. The values of the physical properties were shown smallest ones at the cheek of the fruits, and the statistical test results of the physical properties between the cheek from the other two positions of the fruits showed that there were significant difference at the 1 % level between them. 2. The effect of loading rate on the physical properties of the fruits was relatively large, all the considered physical propertis of the fruits increased with the loading rate, but the hysteresis loss decreased with it. 3. The physical properties of the fruits according to the storage conditions and period showed different, and the bioyield deformation and the rupture deformation of the fruits increased with the storage period, but the bioyield strength and the ultimate strength of the fruits decreased with it. The effect of the storage conditions on the those physical properties showed that the normal temperature storage condition was a little higher than the low temperature storage condition. 4. As a whole, it was shown that the bioyield strength and the ultimate strength of the pear decreased a little faster than those of the apple, and the bioyield deformation and rupture deformation of the pear increased a little faster than those of apple at the two storage conditions.

• 자원리싸이클링
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• 제4권1호
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• pp.4-11
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• 1995

국내 각 채석장 및 석재 가공공정에서 발생되는 폐석과 석분 슬러지를 활용하여 장식재, 바닥재 및 내외장재 등에 쓰이는 인조 석판재 제조기술을 개발하고자 하였다. 인조석재는 폐석과 결합제 및 경화제 등을 혼합하여 제조하였으며 성형압력, 폐석 및 석분 슬러지의 결합비 그리고 결합제의 양 등의 변화에 따른 인조석재 각각의 특성을 비교하였다. 천연석재와 인조석재와의 물성을 비교하기 위하여 $\circled1$ 비중,$\circled2$ 흡수율, $\circled3$ 탄성파속도, $\circled4$ 압축강도, $\circled5$ 인장강도, $\circled6$ 반발경도, $\circled7$ 탄성계수 $\circled8$ 포아송비를 측정하였으며 $\circled9$ 내열성도 함께 조사하였는데 석재의 물성은 원료의 혼합정도, 성형압력 및 결합제의 양에 의해 좌우됨을 알 수 있었다. 본 인조석재의 제조에도 석분에 비해 고가인 결합제의 사용을 가능한한 최소로 하여 폐기물로 배출되는 폐석 및 석분슬러지를 최대한 활용할 수 있도록 하였으며 성형압력 $200kg/\textrm{cm}^2$, 결합제의 양 12~15wt.%의 제조조건에서 원하는 물성을 갖는 인조석재를 제조할 수 있었다.

• 폴리머
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• 제34권3호
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• pp.253-260
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• 2010

본 연구에서는 조직확장 응용을 위한 생체적합성 생분해성 하이드로젤을 제조하고, 그 기본특성을 분석하였다. 친수성 고분자인 poly(ethylene glycol)의 양 말단에 다양한 몰비의 D,L-lactide와 glycolide를 개환 중합시켜 PLGA-PEG-PLGA 삼중공중합체를 합성한 뒤 비닐기를 도입하여 하이드로젤 제조 시 swelling/degradation controllers(SDC)로 사용하였다. 합성한 SDC와 PEG diacrylate를 사용하여 라디칼 중합으로 제조한 하이드로젤은 건조된 상태에서도 유연하고 탄성을 보였으며 분해테스트에서는 SDC의 조성과 SDC/PEG의 몰비에 따라 다양한 팽윤지연시간과 분해기간을 갖는 것으로 나타났다. 그 밖에 기계적 물성과 팽윤압력을 측정하였고, 이식시험을 통해 이식용 하이드로젤을 사용목적에 맞게 이식하거나 삽입하였을 때의 생체 조직의 국소적인 병리적 양상을 육안관찰과 현미경적 관찰을 통하여 평가하였다.

• Applied Biological Chemistry
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• 제37권1호
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• pp.19-24
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• 1994

국산장려품종 중 8품종의 콩을 대상으로 콩의 일반성분, 단백질 분산도(PDI), 발아속도, 두부의 주요 품질특성을 비교하였다. 콩의 단백질 함량은 경동 3이 40.43%로 가장 높은 함량을 보였으며, 보광이 37.80%로 가장 낮은 함량을 나타내었다. 그러나, 지질의 함량은 보광이 가장 높았다. 단백질 분산도는 경동 3이 95.3%로 가장 높았고, 수원 162가 71.6%로 가장 낮았다. 콩나물 뿌리의 성장속도는 경동 3, 수원 160, 수원 162 등이 현저히 빠를 뿐만 아니라 발아율도 100%이어서, 콩나물 재배에 적당함을 보였다. 두부의 수율은 수용성단백질 함량이 가장 높았던 경동 3이 $198.8\;cm^3$로 가장 높았으며, 견고성은 수원 146이 가장 단단하였다. 두부의 주요한 관능적 특성 중 익은 콩냄새는 $L{\times}2.3$과 수원 162가, 그리고 탄력성과 견고성은 수원 146이 가장 높게 평가되었다. 따라서 경동 3은 콩나물 재배 뿐만 아니라 두부의 제조에도 우수한 품종으로 밝혀졌으나 표피의 색이 검정색이어서 두부의 색에 영향을 주었다.

• 대한토목학회논문집
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• 제31권1D호
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• pp.91-98
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• 2011

최근에 들어 보도나 산책로, 공원 등에 주로 사용되었던 보도블록 및 투수콘크리트 대신 합성고무칩(EPDM Chip)을 사용한 탄성포장이 보행시 충격흡수와 다양한 칼라와 디자인을 연출할 수 있어 사용이 증가되고 있다. 그러나, 자외선에 노출시 합성고무칩의 탄성력, 내구성 등이 저하되고, 황변현상으로 다양한 색상에 의한 경관포장의 기능이 저하되고 있다. 따라서 본 연구에서는 자외선에 노출 시 탄성포장의 주재료인 합성고무칩과 폴리우레탄수지의 색변화를 분석하기 위해 자외선 촉진 내후성 실험을 수행하였다. 그리고 색차계를 이용하여 색공간의 색 수치좌표를 이용하는 방법으로 색차를 정량적으로 분석하였다. 실험결과 기존에 주로 사용되는 BL 폴리우레탄수지의 색변화가 합성고무칩보다 큰 것으로 나타났다. 그리고 BC 폴리우레탄수지의 총색차 ${\Delta}E$가 촉진재령 14일에서 3.162로 BL 폴리우레탄수지의 20.639에 비해 6배 정도 자외선에 대한 색변화 저항성이 높은 것으로 나타났다. 따라서 합성고무칩을 사용하는 탄성포장에서 폴리머 제조시 이소시아네이트를 HMDI로 사용하여 체인형 분자구조를 갖도록 제조된 BC 폴리우레탄수지를 바인더로 사용하는 것이 자외선에 의한 색변화를 억제하는데 매우 효율적인 방법으로 나타났다.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.30-40
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• 2016

본 연구는 2단계 발효된 달팽이 추출물을 5% 사용한 시트 마스크 팩 (2F-SEM)을 개발하였다. 이에 대한 피부미용학적 연구를 수행하기 위하여 순면 100%의 시트를 사용하여 얼굴모양으로 커팅하여 사용하였다. 플라세보 마스크 팩 (placebo mask pack; PM)과 일반 용매추출에 의한 달팽이 추출물을 사용한 마스크 팩 (Gene-SEM)에 대하여 피부 개선효과를 측정한 결과를 보고한다. 첫째; 2F-SEM의 보습효과는 PM 보다 11%, Gene-SEM는 PM 보다 4.7%가 상승되었다. 둘째; 2차 발효달팽이 추출물이 함유된 마스크 팩의 탄력도는 PM 보다 13.8%, Gene-SEM PM 보다 6.7% 이상 개선하는 효과를 보였다. 셋째; 2F-SEM의 피부 거칠기는 PM 보다 6.80%, Gene-SEM는 PM 보다 2.3%가 개선되었다. 넷째; 2F-SEM의 멜라닌감소효과는 PM 보다 15.0%, Gene-SEM는 PM 보다 8.7%이상 개선되었다. 다섯째; 2F-SEM의 잔주름개선효과는 PM보다 8.0%정도 우수하였다. Gene-SEM는 PM 보다 5.1%이상 개선되었다. 여섯째; 2차 발효 물을 이용한 2F-SEM의 관능 평가는 부드러움(softness), 보습 감(moisture), 주름개선효과(fine wrinkle improvement)에서 유의 차 있는 사용감촉을 보였다.