3성분 섬유 혼용에 의한 Wet-laid 부직포의 구조 및 공학적 성능 평가

차주희,김북성,복진선,전한용,Cha, Ju Hee,Kim, Book Sung,Bok, Jin Seon,Jeon, Han-Yong 한국섬유공학회 2016 한국섬유공학회지 Vol.53 No.2

In this study, polyarylate nonwoven fabrics were manufactured by a wet-laid process by using viscose rayon and amorphous PET fiber as binding fibers. The engineering performance was evaluated after calendering to obtain a compact structure. From the polyarylate wet-laid nonwoven fabrics, it was confirmed that polyarylate fiber and binding fibers were mixed evenly. Through calendering, the permeability and pore size of the wet-laid nonwoven fabrics were significantly reduced owing to the compact structure. The bending strength and tensile strength increased through calendering, but the tensile elongation decreased. From an analysis of the tensile properties, monolayer wet-laid nonwoven fabrics showed better evenness than multilayer wet-laid nonwoven fabrics. In addition, multilayer wet-laid nonwoven fabrics showed a higher anisotropy than monolayer wet-laid nonwoven fabrics.

시공 사면을 고려한 토목합성섬유의 계면 마찰특성 평가

차주희,안승재,박상훈,전한용,Cha, Ju Hee,Ahn, Seung Jae,Park, Sang Hun,Jeon, Han Yong 한국섬유공학회 2017 한국섬유공학회지 Vol.54 No.1

Securing the stability of waste landfill is very important of environmental and economic side. In order to secure the stability of waste landfill, slope stabilization is essential. In addition, slope stability is strongly influenced by the contact shear strength of geosynthetics used as barrier wall, so accurate contact shear strength between two interfacial materials can be an important factor for designing with landfills. Therefore, in this study, the friction characteristics on the fixed slope angle were analyzed by considering the actual application environmental condition between geomembrane and geotextile used in waste landfill. The friction characteristics between nonwoven geotextile and smooth type geomembrane increased as the slope angle increased. On the other hand, the frictional characteristics between nonwoven geotextile and textured type geomembrane tended to decrease with slope angle. Also, textured type geomembrane showed about 3 times higher frictional stresses than those of smooth type geomembrane, and textured type geomembrane was more affected by the slope angle.

몬테카를로 시뮬레이션을 통한 복합재의 방사선 차폐능 고찰

차주희(Ju-Hee Cha),전한용(Han-Yong Jeon) 한국고분자학회 2019 폴리머 Vol.43 No.5

본 연구에서는 MCNP(Monte Carlo n-patricle transport code) 시뮬레이션을 통해 다양한 재료 및 조건에 대한 차폐율을 계산해보고 이를 이용해 모든 재료에 적용해 차폐능을 계산할 수 있는 차폐 식을 도출하고자 하였다. 복합재의 구조를 생각하지 않은 선형감쇠계수항은 잘 알려진 식으로 쉽게 구할 수 있었으며 보다 실제와 비슷하게 계산하기 위해 시뮬레이션을 이용하였다. 시뮬레이션을 통해 계산된 선형감쇠계수는 감마선의 에너지 크기에 상관없이 모든 재료에서 같은 경향을 보였다. 이 경향으로 복합재의 선형감쇠계수를 계산할 수 있는 식을 도출해낼 수 있었다. 도출해낸 식으로 계산된 값은 두 재료로 이루어진 복합재가 가질 수 있는 선형감쇠계수의 최댓값으로 생각된다. In this study, Monte Carlo n-patricle transport code (MCNP) simulation was used to derive equations that can be applied to all materials to calculate radiation shielding ability. The linear attenuation coefficient term, which ignores the interface in the composite material, was easily obtained by a well-known equation and was used in the simulation for more accurate calculation. The linear attenuation coefficients calculated by simulation show the same tendency in all materials regardless of γ-ray energy. The value calculated by this tendency is considered to be the maximum value of the linear attenuation coefficient of composite material made of two materials.

PLA 블렌드의 조성비에 따른 동역학적 및 크리프 거동 해석

차주희(Ju-Hee Cha),안승재(Seung-Jae Ahn),전한용(Han-Yong Jeon) 한국고분자학회 2015 폴리머 Vol.39 No.4

Poly(lactic acid)/poly(butylene adipate-co-terephthalate)(PLA/PBAT) 블렌드의 경우 PLA에 블렌딩된 PBAT의 함량이 커질수록 열안정성이 증가하였으며 CaCO3 첨가에 의한 storage modulus 값의 증가로 PLA/PBAT 블렌드의 강성이 향상되었음을 확인하였다. PLA/PBAT/CaCO3 블렌드의 크리프 변형 결과로부터 CaCO3가 증가할수록 더 낮은 온도에서 시편의 변형 저항성이 급격하게 감소하는 것을 확인하였다. 이로부터 60℃ 이상인 경우 PLA의 단독 사용보다 PLA/PBAT 블렌드를 사용하는 것이 변형에 대한 저항성이 클 것으로 생각된다. In the case of poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blend, thermal stability increased as higher PBAT content was blended and it is confirmed that stiffness of PLA/PBAT blend has been improved by increasing the value of storage modulus as addition of CaCO3. From the creep test of PLA/PBAT/CaCO3 blends, the deformation resistance decreased rapidly at lower temperatures as CaCO3 increased. Thus, in the case of application at more than 60℃, it was considered that PLA/PBAT blend has a high resistance to deformation than pure PLA.

내진보강용 탄소섬유 복합사 하이브리드 그리드 직물 제조 및 공학적 성능 평가. I. 탄소섬유 복합사 제조 및 최적 직물 설계

연우,차주희,채철수,이형호,전한용,Yan, Yu,Cha, Ju Hee,Chai, Charles,Lee, Hyeong Ho,Jeon, Han Yong 한국섬유공학회 2018 한국섬유공학회지 Vol.55 No.4

In this study, a carbon fiber composite yarn with the desired stiffness and ductility was fabricated for use in hybrid grid fabrics for seismic reinforcement, and the optimum structures of the grid fabrics were evaluated. Carbon fiber composite yarn was prepared by a double-covering process with carbon fiber/aramid fiber/high-strength PET fiber. It was confirmed that the strength of the carbon fiber composite yarn was greatly increased compared to that of carbon fiber, and the elongation increased by about 0.5%. The TPU (thermoplastic polyurethane) extrusion coating method was more suitable for the carbon fiber composite yarn than urethane impregnation for the coating process. Meanwhile, in the evaluation of yarn fineness and grid structure, thick fibers had greater strengths. When comparing the strength and elongation, the bi-directional grid showed no advantages over the unidirectional grid.

PLA/PMMA/PBAT 블렌드의 상용성 및 조성에 의한 특성 연구

한지연,차주희,안승재,전한용,Han, Ji-Yeon,Cha, Ju-Hee,Ahn, Seung-Jae,Jeon, Han-Yong 한국섬유공학회 2015 한국섬유공학회지 Vol.52 No.4

The viscoelastic behavior and tensile properties of PLA blends and PLA/PMMA/PBAT blends were measured, and an image analysis was performed, to examine the compatibility of PLA, PBAT, and PMMA. PLA/PMMA blends were found to exhibit a high level of compatibility for all compositions. The thermal stability, modulus, and tensile strength of these blends increased with PMMA content. Also, the glass transition temperature and tensile strength of PLA/PMMA blends varied between the values for neat PLA and PMMA, indicating a high degree of compatibility. On the other hand, ternary blends of PLA, PMMA, and PBAT exhibited a low modulus than PLA/PMMA blends; their compatibility improved with PMMA content because of PMMA acting as a compatibilizer for PLA/PBAT blends.

모형실험 및 수치해석에 의한 지오그리드 보강효과 분석

안승재,차주희,유세은,전한용,Ahn, Seung Jae,Cha, Ju Hee,Yoo, Se Eun,Jeon, Han Yong 한국섬유공학회 2016 한국섬유공학회지 Vol.53 No.5

In order to minimize settlement of a shallow foundation, a model test is performed using geogrids for reinforcement. The optimal reinforcement is found by varying reinforcement length and changing reinforcement layer. From the test results, it is inferred that 2 layers and 4 times the foundation length is the most effective reinforcement condition obtained using geogrids. As a result of this tendency, 2 layers-4 times and 2 layers-5 times conditions are used to determine the reinforcement effect of two types of geogrids with the same tensile strength and of a single type of geogrid but with two tensile strengths. The reinforcement effect of the welded type is less than that of warp-knitted type. It can be seen that frictional resistance is developed at the soil-geogrid rib interface; therefore, the reinforcement capacity is reduced. It is inefficient to use reinforcement of high tensile strength under conditions of allowable bearing capacity, but it is necessary to choose reinforcement of suitable tensile strength under conditions of ultimate bearing capacity.

플라즈마 처리한 지오텍스타일의 공학적 성능 평가

이용준(Yong Joon Lee),차주희(Ju-Hee Cha),전한용(Han-Yong Jeon) 한국토목섬유학회 2012 한국토목섬유학회 학술발표회 Vol.2012 No.4

8 kinds of woven and nonwoven geotextiles with design strength were used for plasma treatment. In case of hydrophobic treatment of woven and nonwoven geotextiles was used gas of C2F6, parameter of plasma did electric power of 500 watt, plasma treated time of 10 and 20 min, and gas flow rate of 1500 sccm on treatment condition. In case of hydrophilic treatment of geotextile composites was used gas of O2, parameter of plasma did electric power of 2500 watt, plasma treated time of 10 and 20 min, and gas flow rate of 2000 sccm on treatment condition. Result of the engineering performance test, tensile strength of geotextiles increased after plasma treatment, but chemical resistance had not altered. Finally, long-term performance of plasma treated geotextiles was reviewed through application of Arrhenius equation analysis.

Evaluation of Waste Landfill Applicable Performance of Geomembrane by Accelerated Index Tests

Seung-Jae Ahn(안승재),Yong-Seok Choi(최용석),Ju-Hee Cha(차주희),Hong-Gwan Kim(김홍관),Han-Yong Jeon(전한용) 한국지반신소재학회 2013 한국토목섬유학회 학술발표회 Vol.2013 No.11

The result of the test is reported and it has been found that number of loading cycle has irregular influence on installation damage. It is known that the service life of a GM depends on the exposure conditions, which in a landfill may involve adverse chemical exposure, elevated operating temperatures, and potentially large physical stresses. New equipment was developed and the installation damaged GM samples were exposed to pH solutions under different stress at elevated temperature for hours. It has been noticed that as the applied stress on GM samples increases, residual tensile strength decreases and they showed higher tolerance to acidic condition than alkali condition.

Evaluation of Time-Temperature Dependence of Nonwoven Geotextiles by Salt Water Spray Test

Seung Jae Ahn(안승재),A Ram Lee(이아람),Ju Hee Cha(차주희),Han-Yong Jeon(전한용) 한국지반신소재학회 2013 한국토목섬유학회 학술발표회 Vol.2013 No.4

Four types of nonwoven geotextiles to be used in this study were adopted as test materials. A laboratory exposure program was conducted to assess the 10% NaCl solution of nonwoven geotextiles to examine the applicability for the coastal engineering field. Nonwoven geotextiles specimens were cut into machine direction (MD) and cross machine direction (CMD) which were immersed in the 10% NaCl solution. The immersion conditions were 96, 192, 500 hours at 35, 45, 55, 65, 75, 85℃ respectively. Chemical resistance of these nonwoven geotextiles was estimated by the average retention of tensile properties after exposure in the above chemical solutions.