• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.41-41
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• 2012

고급 스포츠웨어와 이너웨어 등에 많이 사용되고 있는 나일론/폴리우레탄 혼방제품은 염색에 있어서 Grin-through 현상, 인공피혁의 염료 이염 현상 등 많은 문제들이 존재한다. 본 연구의 나일론과 폴리우레탄 복합소재에서 나타나는 염색거동을 고찰하고 분석하여, 폴리우레탄 복합소재의 염색성을 개선하기 위하여 실시하였다. 폴리우레탄 복합소재는 해성분이 용출되지 않은 나일론 초극세사 소재에 폴리우레탄 수지를 함침하여 인공피혁과 같은 느낌을 주도록 직접 제조하였다. 제조된 폴리우레탄 함침 나일론 초극세사 소재의 해성분을 용출하였고, Red 색상의 밀링형 산성 염료, 함금속 염료와 반응성 염료에 따라 달라지는 염색특성 및 세탁 견뢰도 등을 고찰하였다. 본 연구를 통하여 다음과 같은 실험결과를 얻을 수 있었다. 나일론 초극세사와 폴리우레탄 수지를 준비하여 습식공정을 통해 인공피혁을 제조한 함침 소재를 알칼리 감량하였고, 감량률은 15~17% 정도로서 대부분의 해성분이 용출됨을 확인하였다. PPG와 PTMG로 구성된 폴리올을 기반으로 한 폴리우레탄 함침 피혁과 PTMG를 단독으로 사용한 함침 피혁의 염색성을 비교한 결과, PPG+PTMG 타입이 더 우수한 염색성을 나타내었다. 특히 밀링 타입과 함금속 타입 염료의 경우는 거의 2배 이상의 흡진율과 겉보기 색농도를 나타내었다. 한편, 반응성 염료의 경우는 두 종류의 폴리우레탄 필름에 거의 염착되지 않았기 때문에 앞으로의 염색실험에서 제외하였다. 견뢰도 측면에서는 각각의 피염물의 등급은 거의 유사하게 나타남을 확인하였다. 이상과 같은 결과로부터, 인공피혁 제조시 PPG+PTMG 타입의 폴리우레탄 수지를 사용하여 함침시 더 높은 색강도와 염착률을 얻을 수 있음을 알았다. 사용하는 염료의 종류를 좀 더 다양하게 하여 실험을 실시하고 폴리우레탄의 물성 및 분석 등의 추가적인 연구가 진행된다면, 인공피혁의 염색시에 발생하는 여러 가지 문제점들을 해결할 수 있을 것이다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.3
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• pp.227-235
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• 2004

Tunneling in rock mass produces two types of damages in the vicinity of a tunnel: structural and constructional damages. Structural damage represents the damage induced by the unbalance of geostatic stress caused by the tunneling, and constructional damage is the damage produced during the construction. In this study, formulations of tangential and radial stresses in the elastic and plastic zones near a tunnel, and the calculation of radius of plastic zone surrounding a tunnel are introduced by modifying the Hoek-Brown criterion of 2002 edition, which has capability of considering in situ rock mass characteristics and construction damage. From the parametric study, influences of rock mass quality, uniaxial compressive strength of intact rock, and the dimension of the tunnel on the plastic zone are investigated. The accuracy of the proposed approach is evaluated by comparing with results from the previous study.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.393-404
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• 2018

The tunnel can be planned to connect to underground roadway and surface road. The large tunnel and branch section are made when the ramp tunnel access to the main tunnel. In the branch section, stress concentration can be assigned and it can be very important for the stability of the tunnel. This study assessed the behavior of rock pillar in double deck tunnel diverging area by using a two dimensional numerical analysis. This study evaluated different safety factors according to pillar width and the ramp tunnel position in branch. By the assessment of the strength-stress ratio, tunnel pillar width is suggested in order to secure the safety factor 1.5.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.668-675
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• 2018

The continuing urbanization and industrialization around the world has required a large amount of power. Therefore, construction of major infrastructure, including nuclear power plants in coastal areas, has accelerated. In addition, the intensity of natural disasters is increasing due to global warming and abnormal climate phenomena. Natural disasters are difficult to predict in terms of occurrence, location, and scale, resulting in human casualties and property damage. For these reasons, the disaster scale and damage estimation in coastal areas have become important issues. The present study examined the predictable weather data and regional ratings and developed estimating functions for wind wave damage based on the disaster statistics in the southern areas. The results of the present study are expected to help disaster management in advance of the wind wave damage. The NRMSE was used for verification. The accuracy of the NRMSE results ranged from 1.61% to 21.73%.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.499-506
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• 2011

In this study, the performance of composite safety barriers was evaluated through computer simulation. A composite safety barrier of SB4 grade was modeled. The MAT58 material model provided by LS-DYNA software was used to model composite material. The performance of composite material varies according to fiber, resin type, and fiber direction. Polyurethane resin and glass fiber were used. The performance of three different stacking designs was evaluated by carrying out vehicle impact simulation. The performance evaluation based on the vehicle crash manual includes the structural strength performance, the passenger protection performance, the vehicle behavior after crash, scattering of the guardrail. As the result of the finite element analysis, the barrier composed of the more transverse direction fibers shows the better performance on the impact simulation.

• Korean Journal of Environment and Ecology
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• v.5 no.1
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• pp.91-103
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• 1991

Use impacts on environmental deteriorations of trail and campsite were studied in Chirisan National Park in 1991. The entire width, bare width and maximum depth of trail as the trail condition were significantly greater on the more heavily used trail. Trail conditions, especially altitude, entire width and maximum depth of deteriorated points which were surveyed at the total of 82 were significantly different from those of non-deteriorated points. On the ridge trail, the damaged are more severe than Class 4 reaches about 34,000$m^2$ and use impacts on campsite and deterioration were also accelerated. The dominant trees of the upper layer in trail edge vegetation are changed from Carpinus tschonoskii to Quercus serrata, Carpinus laxiflora and to Quercus mongolica, Carpins laxiflora at Hwaeomsa trail, and from Quercus serrata to Quercus mongolica at Piagol trail. Also Lespedoza maximowiczii, Symplocos chinensis, Deutzia prunifolia, Weigela Subsessilis appear as the dominant lower species at Hwaeomsa trail, L. maximowiczii, S. chinensis, Stephanandra incisa, Rhododendron schlippenbachii for Piagol trail.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.422-431
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• 2016

This study was evaluated in the performance of the connection according to the details of the concrete casing segment in the prestressed composite girder by fabricating and testing specimens with different segments. A total of four comparative specimens were fabricated by using the variables of general composite girders, reinforcement or non-reinforcement, and details of reinforcing bars in the segments so as to evaluate the structural behavior of steel girders. In addition, the possibility of non-cracking grade design of segmented composite girders as well as the effects of stiffness and strength according to the loop connection types after cracking were analyzed, and the appropriateness of the crack width control both the embedded steel plate and the concrete surface were evaluated.

• Polymer(Korea)
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• v.30 no.1
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• pp.10-13
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• 2006

The effects of antioxidants and thermal treatment on the radiation resistance of the gamma-ray irradiated polypropylene (PP) were studied. The PP was blended with various antioxidants and was fabricated into a sheet. The PP sheet was irradiated with gamma-ray to a dosage of 25kGy in the nitrogen atmosphere. The differences in both color and mechanical strength were investigated for the gamma-ray irradiated PP depending on the kind and the content of antioxidant. The residual amount of free radical and the variation of oxidation index were investigated for the gramma-ray irradiated PP with thermal treatment after irradiation. The PP having phosphite antioxidant showed little difference in color after gamma-ray irradiation compared with the PP having phenolic or mine antioxidant. Sufficient amount of free radical could be removed from the gamma-ray irradiated PP by the thermal treatment at $130\;^{\circ}C$ for 30 min. Thermally treated PP showed lower oxidation index than the PP without thermal treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2356-2363
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• 2015

This study deals the optimization design with the simulation based design of a coil spring inserted into the lock nut for preventing the screw thread from loosening at the bolted joint when the high-strength steel bolt with the property class of 10.9 is used and the screw torque of 640 to 800 (Nm) is applied. In this study, structural analysis of assembly composed of bolt, nut and coil spring is carried out to evaluate its safety factors on the basis of the equivalent stress with commercial finite element analysis software. And the design strategy to extract the design improvement from these simulation results is established. An iterative process performed with the proposed design strategy is also proposed for improving the performance of the existing design. At the proposed procedure, the feasible design parameters using response surface method are found, and then these parameters are verified to be optimal or not by comparing with the response values and the simulation results obtained from the feasible parameters.

• Korean Journal of Food Science and Technology
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• v.14 no.1
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• pp.63-66
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• 1982

The pectin content in tangerine peel and the characteristics of extracted pectin and its gel were determined. The pectin contents of citrus peel and citrus albedo were 11.52% and 9.3% on a dry weight basis, respectively The equivalent weight, methoxyl content and acetyl content of the extracted citrus peel pectin were 596, 13.41% and 0.125% respectively. The intrinsic viscosity and molecular weight of extracted citrus peel pectin were higher than those of commercial citrus pectin samples. The anhydrouronic acid content and jelly grade of the extracted pectins were 98.4% and 138.1, respectively. These were higher than those of commercial citrus pectin. In the textural characteristics of gels, the gel made from the extracted pectin was shown to have lower values in hardness, cohesiveness, adhesiveness and gumminess than the gels made from commercial citrus pectins.