• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.653-661
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• 2006

Metallic sandwich plates with various inner cores have important new features with not only ultra-light material characteristics and load bearing function but also multifunctional characteristics. Because of production possibility on the large scale and a good geometric precision, sandwich plates with inner dimpled shell structure from a single material have advantages as compared with other solid sandwich plates. Inner dimpled shell structures can be fabricated with press or roll forming process, and then bonded with two face sheets by multi-point resistance welding or adhesive bonding. Elasto-plastic bending behavior of sandwich plates have been predicted analytically and measured. The measurements have shown that elastic perfectly plastic approximation can be conveniently employed with less than 10% error in elastic stiffness, collapse load, and energy absorption. The dominant collapse modes are face buckling and bonding failure after yielding. Sandwich plates with inner dimpled shell structure can absorb more energy than other types of sandwich plates during the bending behavior.

• Kyungpook Mathematical Journal
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• v.32 no.3_spc
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• pp.509-515
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• 1992

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.4
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• pp.467-474
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• 2004

A large-eddy simulation is performed for turbulent flow in a concentric annulus with the inner wall rotation at Re$\sub$Dh/=8900 for three rotation rates N=0.2145, 0.429 and 0.858. Main emphasis is placed on the inner wall rotation effect on near-wall turbulent structures. Near-wall turbulent structures close to the inner wall are scrutinized by computing the lower-order statistics. The anisotropy invariant map for the Reynolds stress tensor and the invariant function are illustrated to reveal the altered anisotropy in turbulent structure. Probability density functions of the splat/anti-splat process are explored to develop a sufficiently complete picture of the contributions of the flow events to turbulent production. The present numerical results show that the altered turbulent structures may be attributed to the centrifugal instability, which leads to the augmentation of sweep and ejection events.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.24-31
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• 2011

Performance of the asymmetric trapezoidal fin with various upper lateral surface slopes is investigated by using the two-dimensional analytic method. For a fin base boundary condition, convection from the inner fluid to the inner wall, conduction from the inner wall to the fin base and conduction through the fin base are considered. Heat loss and fin efficiency are represented as a function of the fin base thickness, base height, inner fluid convection characteristic number, fin tip length and fin shape factor. One of the results shows that heat loss increases while fin efficiency decreases as the fin shape factor increases.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.50-56
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• 2011

Injection molding process is one of the popular manufacturing methods to produce plastic parts with high efficiency and low cost. Ball seat for automobile suspension is made by an injection molding process as a part to support pivot function of ball joint consisted of ball stud and housing. It is necessary for a ball seat to have a dimensional stability in the three dimensional inner area to be contacted with ball stud. In this paper, the dimensional stability of inner surface is indirectly analyzed by checking the difference of inner diameter around the circumferential direction and the thickness variation at the top part of ball seat. Measurement was performed by using the coordinate measuring machine and the fixture to hold ball seat. Optimization of injection molding processes such as injection time, cooling time and temperatures of cylinder barrel was derived to reduce the difference of inner diameter and the thickness variation at the top part of ball seat based on the Taguchi method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.740-748
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• 1999

This research was concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes were a bare inner surface, groove inner surface, corrugated inner surface and spring inserted inner surface tubes. The additive concentration was about 0.08 mass%. The heat transfer coefficient was measured as a function of film Reynolds number in the range of 20~200. Experiments were tarried out at higher cooling water temperature of $35^{\circ}C$ to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results were compared with cases without surfactant. The enhancement of heat transfer by Marangoni convection effect which was generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an inserted spring has the highest enhancement effect.

• Bulletin of the Korean Mathematical Society
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• v.35 no.2
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• pp.293-299
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• 1998

In this note we consider some characterizations of analytic functions of bounded and vanishing mean oscillation on the unit disk in $\mathbb{C}$ and answer a question about them in the negative.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.175-180
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• 2010

In this paper, we have investigated ultrahigh frequency nano-mechanical resonators, made of DWCNTs with various wall lengths, via classical molecular dynamics simulations. We have aimed our analysis on the frequency variations of these resonators with the DWCNT wall lengths. The results show that the variations can be well fitted by either the Pearson VII function when the resonant frequency of normalized by its maximum frequency is plotted as a function of the inner/outer wall length ratio L5/L10 for different values of the outer wall length L10, and the Gauss distribution function when the resonant frequency of normalized by its maximum frequency is plotted as a function of the outer/inner wall length ratio for different values of the inner wall length.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.341-346
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• 2019

The study aims to provide a study on the mixing ratios and manufacturing methods of biodegradable PLA sheets for mid - term introduction, A 3-layer process was introduced to produce a multifunctional multi-layer structure sheet having improved heat resistance, impact resistance and transparency while having anti-fogging functionality as a biodegradable PLA sheet used for the purpose of anti-fogging function. Inner layer, core layer and outer layer were mixed and extruded. The inner layer and core layer were studied for a biodegradable PLA multi-layer sheet structure having inner hardness and high heat resistance and outer layer for imparting antifogging function. By applying the results of this study, plastic PLA properties and heat-resistant temperature can be improved to replace and expand plastics.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.89-94
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• 1989

In this paper, we propose a hybrid optical/digital version of the associative memory which improve hardware efficiency and increase convergence rates. Multifocus hololens are used as space-varient optical element for performing inner product and summation function. The real-time input and the stored states of memory matrix is formated using LCTV. One method of adaptively changing the weights of stored vectors during each iteration is implemented electronically. A design for a optical implementation scheme is discussed and the proposed architecture is demonstrated the ability of retrieving with computer simmulation.