• East Asian mathematical journal
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• v.39 no.3
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• pp.319-329
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• 2023

In this paper, we consider a stochastic higher-order Kirchhoff-type equation with nonlinear damping and source terms. We prove the blow-up of solution for a stochastic higher-order Kirchhoff-type equation with positive probability or explosive in energy sense.

• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.403-406
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• 1990

Two types of new silica catalysts modified with benzenesulfonic acid derivatives were prepared by esterification or phenylation followed by sulfonation. Both catalysts thus prepared were tested as acid catalysts for 2-propanol dehydration and cumene dealkylation reactions. B catalyst () were more active than A catalyst (). Highter catalytic activity for B catalyst may be accounted for by higher resistance to water, higher acid strength, more acidity, and better thermal stability as compared with A catalyst.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.2982-2994
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• 1993

Low-velocity impact responses of composite laminates are investigated using the finite element method based on various theories. In two-dimensional nonlinear analysis, a displacement field considering higher order shear deformation and large deflection of the laminate is assumed and a finite element formulation is developed using a C$^{o}$-continuous 9-node plate element. Also, three-dimensional linear analysis based on the infinitesimal strain-displacement assumptions is performed using 8-node brick elements with incompatible modes. A modified Hertzian contact law is incorporated into the finite element program to evaluate the impact force. In the time integration, the Newmark constant acceleration algorithm is used in conjuction with successive iterations within each time step. Numerical results from static analysis as well as the impact response analysis are presented including impact force histories, deflections, strains in the laminate. Impact responses according to two typical low-velocity impact conditions are compared each other.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.6
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• pp.1-9
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• 1995

The structures of inductive irises are used commonly in waveguide filter, especially at highter frequencyies, due to low loss and high temperature stability. However, the iris thickness can not be neglected, as it could be at the lower frequencies. Approximate models assuming zero thickness fail to predict the exact behavior of the filter. And current thickness correction is introduced which is valid in the case of thick irises only. Account of the effect of round is normally not taken. So the necessity of finding a relation for the two factors-iris thickness and round-arises in the design of waveguide filters. This paper describes a mutual relation that considers the combined effect of finite thickness and round from the start. In order to test the validity of the changed relation, weveral examples are given. And the measured response of each case is then compared with the predicted reponse. And it is shown that the radius is of perceptible influence on the transmission coefficient through a thick iris.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.1
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• pp.1-11
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• 1997

The purpose of this study was to describe the protein nutritional status of female collegians between nonvegetarian diet groups(14) and vegetarian diet groups(19). Daily intake, protein were calculated from food direct measurement. Urea/creatinine, muscle mass, fatique conditions and hematological parameter were calculated. Blood samples were analyzed for total protein, albumin ammonia, urea, uric acid, creatinine, BUN contents. The results obtained are summarized as following : 1) On total dietary intake, especially Fe, vitamin C, niacin intake, vegetarian groups were higher than non vegetarian groups. 2) On composition of EAA(essential amino acids), vegetarians were highter than non vegetarian of leucine contents, but were lower lysine and threonine contents. 3) On urea / creatinine excretion, vegetarians were higher than non begetarians. Muscle mass were non signicant, fatique condition, vegetarians were normal state. 4) Non vegetarians were increased serum albumin total protein, uric acid, ammonia but vegetarians were decreased BUN, ammonia after experimental diet intake. 5) In process of time after meal, non vegetarians were increased serum albumin total protein, BUN, but vegetarians were decreased ammonia.

• Journal of KSNVE
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• v.6 no.2
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• pp.147-161
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• 1996

The stress and vibration analysis of stiffened box structure is investigated by experiment and FEM analysis. The effects of stiffener number and box section shape on the structure response are presneted. The 1st natural frequency of stiffened folded byx structure with a stiffeners is 300 Hz. It is highter than that of stiffened rectangular box structure with 5 stiffeners, which is 251 Hz. Maximum deflection of folded box structure with thickness of 1 mm is lower than that of rectangular box structure with thickness of 1 or 2 mm. The natural frequencies of box structures are increeased with the number of stiffener, while the deflections are decreased with the number of box structures. When we compare between fundamental frequency (251 Hz) of stiffened (with 5 stiffeners) and one (137.64 Hz) of unstiffened rectangular box structure under clamped-clamped boundary condition, the ratio of frequency increase is 82%. The stiffened structures of 2 mm thickness can reduced to 120% of maximum deflection of 1 mm thickness rectangular box structures.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.104-108
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• 2005

The Korean high speed train runs at 300 km/h, ballast-flying phenomenon often happens by strong train-wind. It is important to consider the prevention of ballast-flying phenomenon, because the train under-body and fares or walker around a rail might be damaged. In this study, Numerical analysis of the flow field of under-body of train and study of heighter-effect were conducted to decrease the speed of under-body. The shape of under-body was simplified for convenience of meshing and analysis. According to results of Taguchi's design by orthogonal arrays, a height of tie is dominant in the flow field, so if the heighter is installed on tie, the speed of under-body might be decreased. The result of this study is useful to build a new high-speed-line.

• Transactions of Materials Processing
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• v.9 no.1
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• pp.27-34
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• 2000

Sheet metal formabilities for aluminum 1050 and 5052 were experimentally investigated in this study. Deep drawability, bendability and stretch formability were measured at each process condition and correlated with tensile properties of sheet metal. To compare the formabilities of aluminum 1050 and 5052 sheets with those of steel sheets, deep drawing quality(DDQ) steel sheets are also tested at the same test conditions. Through the experimental studies, influential process variables for each forming process were obtained and correlated with the tensile properties. The comparisons of sheet metal formabilities with those of steed sheets showed that aluminum 1050 and 5052 is inherently deficient in formability than steel sheets but Al 5052 that has highter n and r value than al 1050 showed better formabilities.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.30-34
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• 2000

The concretes cast in the sea water would be likely to be rich mix and mass concrete. Therefore it is important to check out the hydration heat of concrete and to reduce it to prevent the concrete from processing the temperature crack. Recently the antiwashout agent is used on underwater concrete for preventing from the segregation of concrete in the water. The experimental studies were done for the combined cement replaced by fly ash 30%unit weight of binder to study on the characteristics of hydration heat of antiwashout underwater concrete, and its characteristic was discussed by comparing on cast in sea water with anther one in air. The present paper showed that the hydration heat concrete replaced by 30%of fly ash was more significantly reduced than the normal concrete. The hydration heat of antiwashout underwater concrete was highter than that of normal concrete, but it was reduced lower than the normal concrete by adding fly ash.

• Journal of the Korean Home Economics Association
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• v.34 no.3
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• pp.1-8
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• 1996

These days, Home Economics in Korea is confronted with the inner argument about its identity and the outer pressure of re-organization caused by educational reformation. Fundamentally, these internal and external challenges to Home Economics arise from that Home Economics has not been fulfilling the needs of individuals and families due to weakening of integrate perspective, insufficient practice and conservative tendency of study. To get over the current problems and construct a new paradigm of Home Economics contributing to the requirements of new era, the following prerequisites might be fulfilled; \circled1 More active concern about surmounting the alienation that threatening the modern family life and self-actualization of individuals. \circled2 An endeavor to find a new family philosophy and patterns of family culture as the basis of community restoration that harmonize the traditions with changes. \circled3 An Effort to find a highter values that contribute to symbiosis and development of global community including all human beings, creatures and eco-system on the earth.