• 폴리머
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• 제39권1호
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• pp.107-113
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• 2015

클로로부틸(CIIR) 방진고무 복합소재 내에서 실리카-실란이 기계적 물성과 점탄성에 미치는 영향을 평가하였다. 실리카-실란이 첨가된 경우, 방진고무의 핵심물성 중 하나인 인열강도는 13%, 파단 신장률은 14%씩 각각 증가하였다. 그 외 인장강도 및 경도 등은 비슷한 값을 보였다. 점탄성 관찰로부터 인열강도 및 파단 신장률의 증가는 실리카-실란의 첨가에 의한 복합소재 내 실리카와 클로로부틸간 3차원 사슬구조의 형성에 따른 것으로 판단되었다. 인열강도 및 파단 신장률의 향상에 관한 메커니즘을 논의하였다.

• 한국공작기계학회논문집
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• 제15권4호
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• pp.98-104
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• 2006

In this paper, for the purpose of investigation the acoustic emission(AE) behaviors during resistance spot welding process and tension test of spec steels. As the results present the resistance spot welding method that can get suitable welding qualities or structural integrity estimating method. The resistance spot welding process consists of several stages: set-down of the electrodes; squeeze; current flow; forging; hold time; and lift-off. Various types of AE signals are produced during each of these stages. For tensile-shear test and cross tensile test in resistance spot welded specimens, fracture pa 야 ems are produced: tear fracture; shear fracture; and plug fracture. Tensile-shear specimens strength appeared higher than cross tensile specimens one. In case of tensile-shear specimen happened tear fracture that crack happens in most lower plate. Also, in case of cross tensile specimens, upper plate and lower plate are detached perfect fracture was exposed increases a little as acting force is lower than ordinary welding condition. Therefore, the structure which is combined by resistance spot welding confirmed that welding design must attain so that shear stress may can interact mainly.

• 펄프종이기술
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• 제35권1호
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• pp.13-18
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• 2003

This study was done in an effort to evaluate the possibility of recyclability of moisture-proof paper. Because it is difficult to recycle laminated moisture-proof paper, a mixture of styrene-butadiene latex(SB latex) and wax emulsion was used as moisture-proof paper chemicals. A bar coater was applied to make moisture-proof paper and the coated weight was 17 g/$m^2$. The mixing ratios of SB latex to wax emulsion were 85 : 15, 87 : 13, and 90 : 10, respectively. It was observed that the moisture-proof paper treated with SB latex and wax emulsion at the appropriate ratio could be recycled effectively. The moisture-proof paper was similar to base paper in degree of pulping, and there was no significant difference in dispersion between moisture-proof paper and base paper. Most of wax particle which caused the spots during drying process could be removed by flotation process. Tensile strength and tear strength of handsheets made of both moisture-proof paper and base paper after pulping was measured to examine the fiber bonding and no significant difference in mechanical properties was observed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.931-934
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• 2008

폴리우레탄은 방수재로 널리 사용되며 구조물에 발생되는 균열 및 거동에 의해 항상 외력을 받고있을 뿐만 아니라 사용 환경에 따라 각종 환경열화 인자에 노출되어 있다. 환경 열화인자로서는 자외선, 오존, 열, 수분 등이 잘 알려져 있다. 그 중에서 모든 열화의 기본이 되는 열의 영향, 특히 고온에서의 영향이 중요하다. 따라서, 노출형인 우레탄 고무계 1류 도막 방수재의 경우는 80$^{\circ}C$에서, 비노출형의 경우는 70$^{\circ}$C에서 촉진 열열화 시험을 3주간 실시하였다. 결과는 방수재의 기본물성과 인장 강도 및 신장율 모두 저하되는 경향을 보였으며, 특히 온도 60$^{\circ}$C에서 측정할 경우 급격히 물성 저하가 발생되었다.

• Archives of Plastic Surgery
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• 제35권6호
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• pp.659-662
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• 2008

Purpose: Silicone gel sheet(SGS) is used for preventing and treating keloid or hypertrophic scars. Because the product is weak in tear strength and adherence, it requires several replacements, which requires high cost. As a solution for this problem, we developed a new silicone gel sheet, named as Scar Clinic, and confirmed its physical properties. Methods: Tensile strength, elongation rate, adhesiveness, and water vapor transmission rate were experimentally compared between the most commonly used SGS product and the Scar Clinic. Results: The newly developed SGS showed better results compared to the existed SGS in regards to tensile strength, elongation rate, adhesiveness, and water vapor transmission rate. Conclusion: The Scar Clinic showed higher durability and flexibility. It will be a useful product for treating scars clinically.

• 펄프종이기술
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• 제29권1호
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• pp.7-12
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• 1997

This study was intended to investigate the proper shape and size of calcium carbonate for the improvement of paper properties and its end use performance. We loaded calcium carbonate of various shapes and size in the handsheet and measured their physical and optical properties. Results obtained from the study are summarized as follows : 1. Due to different particle shapes and sizes, precipitated calcium carbonate (PCC) contributed greater to bulk improvement than ground calcium carbonate (GCC). Scalenohedral form of PCC produced the bulkiest sheet, GCC made the sheet bulkier as average particle size increases. 2. Tensile strength increased as average particle size was increasing. GCC kept tensile strength more effectively than PCC. The effect of particle size on tensile strength was much more pronounced as filler addition level was increasing. 3. Over the average particle size of 6.99$\mu$m, GCC gave much higher burst strength and internal bond than PCC did. In the filler levels of 20% and 30%, GCC by using bigger size fillers showed 50~100% improvement in some cases than PCC at the same filler content. 4. Tear strength increased as average particle size was increasing. At the filler level of 30%, PCC decreased tear greatly. 5. Over the average particle size of 13.56$\mu$m, GCC kept bending stiffness greater than PCC. Due to its shape, Scalenohedral form of PCC showed higher stiffness than others at the same particle size. 6. Cubic and acicular form of PCC improved light scattering coefficient very effectively. Light scattering coefficient of GCC decreased as average particle size increased. 7. Both of particle shape and size of filler were important factor in developing optical properties and bending stiffness. Particle size was the only important factor in developing other strength properties

• 펄프종이기술
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• 제40권4호
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• pp.43-50
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• 2008

Adsorption of xylans extracted from birchwood and oat spelt on Hw-BKP were analyzed using HPLC. The effect of xylan adsorption on paper properties such as tensile, tear index and brightness was also investigated. The constituents of xylan was analyzed with HPLC after hydrolysis with dilute sulfuric acid. It was shown that xylose was the major constituent and small amounts of glucose and galactose were contained in the xylan samples. Adsorption of xylan on hardwood fibers was evaluated using acid hydrolysis and HPLC techniques. Results showed that the adsorption of negatively charged xylan on the fiber surface was negligible probably because electrostatic repulsion between these two materials. Pretreatment of the fiber with alum increased xylan adsorption. The amount of adsorption increased up to 30 mg/g. With the increase of xylan adsorption both tensile and tear strength of the handsheet increased suggesting xylan can be a very effective strength agents for papermaking. Brightness of the handsheets decreased, however, with the use of xylan.

• Advances in materials Research
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• 제8권2호
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• pp.103-115
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• 2019

Polypropylene (PP) fibers for making fabric which is used for packing cement have a high strength and high tear resistance. Due to these excellent properties the present study investigates the effect of PP fibers on the mechanical strength of concrete. Mechanical strength parameters such as compressive strength, splitting tensile strength and flexural strength are evaluated. Structural integrity of concrete using Ultrasonic Pulse Velocity (UPV) was also studied. Concrete containing PP fibers in percentage of 0%, 0.15%, 0.25%, 0.5% and 0.75% was developed with a characteristic compressive strength of 25 MPa. Concrete cubes, cylinder and prismatic specimens were cast and tested. It was found that the UPV values recorded for all specimens were of the similar order. Test results indicated the used of PP fibers can significantly improve the flexural and splitting tensile strengths of concrete materials whereas it resulted a decreased in compressive strength. The relative increase in split tensile and flexural strength was optimum at a fiber dosage of 0.5% and a mild decreased were observed in 28 days compressive strength. The findings in this paper suggested that PP fibers deriving from these waste cement bags are a feasible fiber option for fiber-reinforced concrete productions.

• Journal of the Korean Wood Science and Technology
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• 제27권1호
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• pp.88-104
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• 1999

본 시험은 외발 뜨기 한지와 쌍발 뜨기 한지를 구분하고 각각의 물성 차이 중 특히 4가지 강도에 대해 상대적 우위와 가로 세로 강도의 차이를 파악했다. 그 결과, 섬유 배향성을 특별히 고려하지 않은 외발 뜨기는 쌍발 뜨기와 비교해 가로, 세로 강도 차이가 다소 적다는 것 외에 특별히 뛰어난 점이 없다는 것을 알 수 있었다. 외발 뜨기 한지가 질기다고 느껴지는 것은 좋은 원료와 토착식 제법으로 여러 장(2~8장) 겹쳐서 절대적인 강도를 향상시켰기 때문이며 상대적인 강도인 지수비교에서는 큰 차이가 없었다. 또한 부가적으로 도침의 효과를 파악할 수 있었다. 도침은 내절도를 두드러지게 향상시켰으며 인열지수(인열강도)를 뺀 열단장과 파열지수(파열강도)를 높이는 역학을 했다. 특히 열단장(인장강도)의 향상을 가져왔다. 그리고 토착식 제법의 외발 뜨기는 여러 겹을 겹칠수록 인열지수가 증가(다른 강도에 비교해 상대적인 증가임)하는 경향을 보였다. 그러므로 도침과 토착식 한지는 서로 부족한 강도를 훌륭히 보완하는 역할을 했음을 알 수 있었다. 따라서 섬유 배향성을 고려하여 초지하고 도침을 실시해야 외발 뜨기 고유의 강도적 특징을 살릴 수가 있음을 알 수 있었다. 그리고 오늘날에 토착 외발 뜨기 방식으로 제조된 전통 한지들은 전체적인 강도면에서 토착 한지류와 비슷했으며 2겹지의 경우엔 가로 세로 강도차이도 토착한지 수준이었다. 그러나 강도들간의 우열 특성에서는 인열강도가 특히 낮았던 쌍발 뜨기 한지와 전체적으로 고른 강도를 보인 토착 외발 뜨기 한지의 중간에 위치하여 개선의 여지를 찾을 수 있었다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.433-440
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• 2006

A fiber processing method, which might be an alternative for conventional refining process, was introduced. The method consists of repetitive, gentle, mechanical impacts on fiber, and ensued fiber uncurling process. This method was very effective for OCC and BCTMP for increasing WRVs (water retention value) while keeping fiber lengths from shortening. For OCC and BCTMP, gentle mechanical impacts on fibers using Hobart mixer increased breaking lengths and tear strengths simultaneously at fast drainage level, and straightening fibers using kady mill increased those strength properties further. For SwBKP and HwBKP, only mechanical impacts using the mixer were effective on increasing tensile and tear strength at fast drainage, but not kady mill treatment. The strength increases of BCTMP by this alternative fiber processing method were exceptionally high. An extensive engineering development should be followed to actualize this fiber processing mechanism in an energy-effect way.