• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.760-765
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• 2013

Eco-friendly material applied to building would be one of the materials which is must developed for global environmental conservation and reduction of carbon dioxide. For development of eco-friendly material, a cellulose sound-absorbing material has been developed with waste paper through adjustment of various mix proportions. The developed cellulose sound-absorbing material has been tested for its acoustic properties such as acoustic absorptivity and dynamic elastic modulus. The absorptivity was evaluated by developing six samples and using impedance tube and reverberation chamber. As a result of the evaluation, 0.64(NRC) was secured in absorptivity and $4.7MN/m^3$ was indicated in dynamic elastic modulus. Also, for practical use of developed sound-absorbing material as inner heartwood in drywall, comparison test of sound reduction index was performed with existing glass wool sound-absorbing material and constructed drywall of gybsum board. The results have shown 55dB(Rw) of sound reduction index in glass-wool wall and 46dB(Rw) in cellulose.

• 감성과학
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• 제23권4호
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• pp.21-32
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• 2020

패션 제품의 이미지는 소재의 재질감과 컬러에 따라 다르게 나타날 수 있으며, 실물과 디지털 화면에서의 이미지 또한 다르게 나타날 수 있다. 따라서 본 연구에서는 베이직 컬러 패션 소재의 실물과 디지털 화면에서 느껴지는 시각적 감각 차이에 대해 알아보고자한다. 본 연구에서는 60개의 패션소재로 시각적 감각 형용사 3쌍에 대해 실험을 진행하였으며, 색채, 요철과 같은 물리적 특성과 시각적 특성으로 나누어 각 요소별로 실물과 디지털 화면에서의 평가 차이가 있는지 알아보았다. 색채에 따른 시각적 감각은 실물과 디지털 화면에서의 평가가 동일한 감각을 느끼는 것으로 나타났다. 요철에 따른 시각적 감각에서 '요철이 있는' 소재는 실물과 디지털 화면에서 동일한 감각을 느끼는 것으로 나타났으며, '요철이 없는' 소재는 실물과 디지털 화면에서 서로 반대되는 감각을 느끼는 것으로 나타났다. 시각적 분류에 따른 결과는 실물과 디지털 화면에서의 평가가 모두 같은 감각을 느끼는 것으로 나타났다. 따라서, 패션 소재의 시각적 감각을 평가할 때는 소재 표면의 특성이 영향을 미치며, 실제 소재와 디지털 화면에서의 소재는 느껴지는 감각의 정도가 다름을 알 수 있었다. 본 연구는 패션 소재의 시각적 감각은 평가 방법에 따른 결과의 차이 있음을 제시함으로써 앞으로 패션 소재의 시각적 감각을 평가하는데 있어 다양한 연구 방법이 고려되어야 함을 시사하는데 의의가 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.689-692
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• 2002

Composite materials, when damaged under thermal or mechanical loadings, show property changes. Among many mechanical properties of composite materials. the stiffness tend to be reduced due to micro-cracking, debonding, or delamination caused by external loadings. This research presents results regarding the detecting technique of internal damages within composite that experienced low-velocity impacts. Post-damage evaluations were made experimentally using flexural and compression loadings. Preliminary finite element analysis was made and compared with analytical solutions. The experimental results to determine the degree of damage will be compared with finite element results.

• 센서학회지
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• 제25권4호
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• pp.264-270
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• 2016

Self-powered neutron detector (SPND) is a sensor to monitor a neutron flux proportional to a reactor power of the nuclear power plants. Since an SPND is usually installed in the reactor core and does not require additional outside power, it generates electrons itself from interaction between neutrons and a neutron-sensitive material called an emitter, such as rhodium and vanadium. This paper presents the simulations of the depletion sensitivity evaluations based on MCNP models of rhodium and vanadium SPNDs and light water reactor fuel assembly. The evaluations include the detail geometries of the detectors and fuel assembly, and the modeling of rhodium and vanadium emitter depletion using MCNP and ORIGEN-S codes, and the realistic energy spectrum of beta rays using BETA-S code. The results of the simulations show that the lifetime of an SPND can be prolonged by using vanadium SPND than rhodium SPND. Also, the methods presented here can be used to analyze a life-time of those SPNDs using various emitter materials.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.1988-1997
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• 2005

This study is concerned with structural integrity evaluations for the interference-fit flywheels in reactor coolant pumps (RCPs) of nuclear power plants. Stresses in the flywheel due to the shrinkage loads and centrifugal loads at the RCP normal operation speed, design overspeed and joint-release speed are obtained using the finite element method (FEM), where release of the deformation-controlled stresses as a result of structural interactions during rotation is considered. Fracture mechanics evaluations for a series of cracks assumed to exist in the flywheel are conducted, considering ductile (fatigue) and non-ductile fracture, and stress intensity factors are obtained for the cracks using the finite element alternating method (FEAM). From analysis results, it is found that fatigue crack growth rates calculated are negligible for smaller cracks. Meanwhile, the material resistance to non-ductile fracture in terms of the critical stress intensity factor (K$_{IC}$) and the nil-ductility transition reference temperature (RT$_{NDT}$) are governing factors for larger cracks.

• 동아시아식생활학회지
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• 제18권1호
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• pp.58-63
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• 2008

This study was conducted to present fundamental data on the physicochemical properties and sensory qualities of salad dressings made with chicken foot gelatin. Preliminary experiments were performed to confirm the gelatin powder concentrations in preparing gelatin solutions. A 2% gelatin solution, including 0.5% agar, was prepared for use in the experiments that followed. Sensory evaluations were conducted to compare the organoleptic acceptance of dressings manufactured with differing concentrations of the additive in seasoning soybean sauce, mayonnaise, and sesame powder. The viscosities of the dressings significantly increased with increasing gelatin powder concentration. A decrease in turbidity was observed in the mayonnaise and sesame dressings. The color difference values of all dressings indicated no changes. In sensory evaluations of dressings prepared with gelatin solutions at different concentrations of 2 g (1%), 4 g (2%), and 8 g (4%) of gelatin powder, the 4 g (2%) sample received the highest score for overall acceptance. From this study, which was conducted to find an efficient use for chicken house wast product, it is anticipated that chicken feet will be utilized as a new raw material for producing collagen and gelatin, protein sources widely increasing in use with in the food and bio-industries.

• 한국의류산업학회지
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• 제26권2호
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• pp.190-197
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• 2024

With increasing global interest in environmentally friendly materials and the consequent rise in demand, there is a growing need for alternatives to synthetic fibers, which can cause skin diseases and other side effects. The fashion industry is emphasizing material sustainability owing to concerns about increasing carbon emissions. Moreover, consumers express a strong desire for ecofriendly and sustainable materials. Therefore, clothing brand companies are developing eco-friendly products to enhance their corporate image. Hemp fibers are recognized for their functionality and are utilized as crucial materials in the development of eco-friendly products by global fashion companies. In this study, we produced socks that effectively improve foot health using hemp stem bark extract fibers and demonstrated the positive efficacy of natural fibers through functional and wearability evaluations. Hemp stem bark extract fibers showed 99.9% antimicrobial effectiveness against bacteria responsible for sweat-induced bacterial proliferation and odor, when blended with lyocell fibers and woven into fabric to manufacture socks. Wearability evaluations of these terry cloth socks confirmed a reduction in foot odor and fatigue among the participants with a consumer satisfaction of 4.63/5. These findings confirm the effectiveness and positive impact of the natural antimicrobial properties of hemp fibers and terry cloth structure in improving foot health.

• Advances in aircraft and spacecraft science
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• 제7권4호
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• pp.353-369
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• 2020

This paper presents the flutter analysis and optimum design of axially functionally graded box beam cantilever wing section by considering various geometric and material parameters. The coupled dynamic equations of the continuous model of wing system in terms of material and cross-sectional properties are formulated based on extended Hamilton's principle. By expressing the lift and pitching moment in terms of plunge and pitch displacements, the resultant two continuous equations are simplified using Galerkin's reduced order model. The flutter velocity is predicted from the solution of resultant damped eigenvalue problem. Parametric studies are conducted to know the effects of geometric factors such as taper ratio, thickness, sweep angle as well as material volume fractions and functional grading index on the flutter velocity. A generalized surrogate model is constructed by training the radial basis function network with the parametric data. The optimized material and geometric parameters of the section are predicted by solving the constrained optimal problem using firefly metaheuristics algorithm that employs the developed surrogate model for the function evaluations. The trapezoidal hollow box beam section design with axial functional grading concept is illustrated with combination of aluminium alloy and aluminium with silicon carbide particulates. A good improvement in flutter velocity is noticed by the optimization.

• 대한기계학회논문집A
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• 제25권3호
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• pp.369-380
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• 2001

Although extensive efforts have been devoted to the optimal design of composite laminated plates in recent years, some practical issues still need further research. Two of them are: the handling of the ply angle as either continuous or discrete; and that of the uncertainties in material properties, which were treated as continuous and ignored respectively in most researches in the past. In this paper, an algorithm for stacking sequence optimization which deals with discrete ply angles and that for thickness optimization which considers uncertainties in material properties are used for a two step optimization of composite laminated plates. In the stacking sequence optimization, the branch and bound method is modified to handle discrete variables; and in the thickness optimization, the convex modeling is used in calculating the failure criterion, given as constraint, to consider the uncertain material properties. Numerical results show that the optimal stacking sequence is found with fewer evaluations of objective function than expected with the size of feasible region taken into consideration; and the optimal thickness increases when the uncertainties of elastic moduli considered, which shows such uncertainties should not be ignored for safe and reliable designs.

• 한국공간구조학회논문집
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• 제19권2호
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• pp.73-81
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• 2019

The high-temperature properties of mild steels were studied by comparing the test results of Kwon and the yield strength, tangent modulus predicted by the design provisions of ASCE and Eurocode(EC3). The column strengths for steel members at high temperatures were determined by the elastic and inelastic buckling strengths according to elevated temperatures. The material properties at high temperatures should be used in the strength evaluations of high temperature members. The buckling strengths obtained from the AISC, EC3 and approximate formula proposed by Takagi et al. were compared with ones calculated by the material nonlinear analysis using the EC3 material model. The newly simplified formulas for yield stress, tangent modulus, proportional limit and buckling strength which were proposed through a comparative study of the material properties and buckling strengths. The buckling strengths of proposed formulas were approximately equivalent to ones obtained from the formulas of Takagi et al. within 4%. They were corresponded to the lower bound values among the buckling strengths calculated by the design formulas and inelastic buckling analysis.