• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.771-772
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.305-306
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• 2007

• Bulletin of the Society of Naval Architects of Korea
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• v.5 no.2
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• pp.51-52
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• 1968

The effect of trim on the form factor K was investigated by the towing tank test using a 4 ft. Mariner model. The effect is considerably small. The results are shown in Fig.1.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.845-846
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• 2011

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.531-537
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• 2010

This paper optimized the design parameters of the offset strip fin in a heat exchanger. To decrease the pressure drop and increase heat transfer, the performance factors such as j/f, $j/f^{1/3}$, and JF, which could be used to estimate the pressure drop and heat transfer simultaneously, were employed as the criteria for optimization. In the present study, STDQAO, PQRSM, and MGA were used for solving the constrained nonlinear optimization problem. The JF factor and heat transfer performance of the optimized offset-strip fin were greater than those of the reference offset-strip fin by 36% and 280%, respectively.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.43-48
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• 2007

Collagen-induced arthritis (CIA) is a model for some types of human autoimmune rheumatoid arthritis (RA). In this study, we examined whether ethanol extract of potato (Solanum tuberosum) is efficacious against CIA in mice. Potato extracts (100 and 200 mg/kg) were orally administered to DBA/1J mice once daily for 49 day after initial immunization with type II collagen. Clinical assessment of disease and measurement of paw edema were conducted throughout the study. The production of CIA-related rheumatoid factor, anti-type II collagen antibody, and cytokines were examined in DBA/1J mice. Serum levels of AST, ALT, creatinine, and lipids were measured, and antioxidant enzyme activity in the spleen was also determined. The arthritis score and paw edema were markedly suppressed in the groups treated with potato extract. Levels of rheumatoid factor, anti-type II collagen antibody, interleukin (IL)-1, IL-6, LDL-cholesterol, and malondialdehyde in sera were also reduced by potato extract treatment. The activities of glutathione peroxidase and glutathione reductase were increased in the spleens of CIA mice treated with potato extract. These findings suggest that potato extract has suppressive effects on type II collagen-induced arthritis, an animal model for human RA.

• 한국도로학회:학술대회논문집
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• 2008.10a
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• pp.93-102
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• 2008

An energy based crack growth model is developed in this study to simulate the propagation of top-down cracking in asphalt pavements. A viscoelastic fracture mechanics approach, generalized J integral, is employed to model the crack growth of asphalt concrete. Laboratory fatigue crack propagation tests for three different asphalt mixtures are performed at various load levels, frequencies and temperatures. Disk-shaped specimens with a proper loading fixture and crack growth monitoring system are selected for the tests. It is observed from the tests that the crack propagation model based on the generalized J integral is independent of load levels and frequencies, while the traditional Paris' law model based on stress intensity factor is dependent of loading frequencies. However, both models are unable to take care of the temperature dependence of the mixtures. The fatigue crack propagation model proposed in this study has a good agreement between experimental and predicted crack growth lives, which implies that the energy based J integral could be a better parameter to describe fatigue crack propagation of viscoelastic materials such as asphalt mixtures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.252-256
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• 1989

In the low cycle fatigue fracture testing with KS(or JIS) SS41, crack growth rate, AE count rate and J-integral range are measured to get empirical relations between crack growth rate and J-integral range, AE count rate and J-integral range as well as AE count rate and crack growth rate. All the relations are shown to be linear on the log-log graphs. It is also shown that the linear relations can be formulated by using Dunegan's assumption and elastic-plastic fracture mechanics along with the well-known relation of crack growth rate and J-integral range. It is concluded that the differences between experimental and theoretical values are due to Dunegan's assumption.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.284-286
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• 2003

The low load power factor causes various problems such as the Increase of the power loss and the voltage instability. The demand of reactive power increases continuously with the growth of active power and the restructuring of electric power companies makes the integrated management of ractive power troublesome, from which the systematic control of load power factor is required. In this paper, the load power factor sensitivity of the generation cost and integrated costs are used for determining the locations and capacities of reactive power compensation devices effectively and for enhancing the load power factor appropriately. It is shown through the application to a small-scale power system that the system power factor can be enhanced effectively and appropriately using the load power factor sensitivity and integrated costs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3051-3059
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• 2015

In this study, the effect of corrugation angle on thermal performance of corrugated plate is numerically investigated with an aim to develop humidifying element. Numerical analysis was conducted for a range of corrugation angle (from $0^{\circ}/0^{\circ}$ to $60^{\circ}/60^{\circ}$ for equal angle and from $15^{\circ}/0^{\circ}$ to $15^{\circ}/60^{\circ}$ for unequal angle). Results revealed that both j and f factor increased as corrugation angle increased. Especially, f factor increased significantly at high corrugation angles. j and f factors of unequal angle plates and those of equal angle (obtained by averaging unequal angles) plates were approximately the same. The largest $j/f^{1/3}$, which implies the largest heat transfer rate per consumed power, was obtained at $15^{\circ}/15^{\circ}$. Existing correlations under- or over-predicted the present numerical results.