• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.227-231
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• 2000

Thermal cesium atomic beam was collimated by transversely cooling of atoms, for which circularly polarized ($\sigma^+$ and $\sigma^-$ polarized) laser light was illuminated to the atomic beam from two perpendicular directions. As a result, the temperature corresponding to the transverse velocity component could be decreased from 430 mK to 60 11K. In addition, the spatial atomic distribution was observed according to the power difference of the two laser beams and the magnetic field applied, and the result was qualitatively coincided with the calculation result by the Doppler cooling theory. heory.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1267-1273
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• 2009

Hot press forming can produce high-strength components by rapidly cooling between closed punch and die after hot forming using quenchable boron steel austenized in a furnace. In the hot press forming process, the cooling rate is influenced by the size, position and arrangement of the cooling channel and the file condition of cooling water in the die. Also, mechanical properties of the final components and operation time are related to cooling rate. Therefore, the design of optimized cooling channel is one of the most important works. In this paper, the effect of position and size of the cooling channel on the cooling rate was investigated by using design of experiment and FE analysis in hot press bending process. Therefore the optimum cooling channel ratio was presented in the HPB.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.4
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• pp.430-435
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• 2009

The cooling stage greatly affects the product quality in the injection molding process. The cooling system that minimizes temperature variance in the product surface will improve the quality and the productivity of products. The cooling circuit optimization problem that was once solved by a response surface method with 4 design variables. It took too much time for the optimization as an industrial design tool. It is desirable to reduce the optimization time. Therefore, we tried the back-propagation algorithm of artificial neural network(BPN) to find an optimum solution in the cooling circuit design in this research. We tried various ways to select training points for the BPN. The same optimum solution was obtained by applying the BPN with reduced number of training points by the fractional factorial design.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.26-27
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• 2001

• 전기산업
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• v.7 no.3
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• pp.76-82
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• 1996

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.124-130
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• 2012

An injection mold cooling circuit for an automotive front bumper was optimally designed in order to simultaneously minimize the average of the standard deviations of the temperature and the difference in mean temperatures of the upper and lower molds for uniform cooling. The temperature distribution for a specified design was evaluated by Moldflow Insight 2010, a commercial injection molding analysis tool. For efficient design, PIAnO (Process Integration, Automation and Optimization), a commercial PIDO tool, was used to integrate and automate injection molding analysis procedure. The weighted-sum method was used to handle the multi-objective optimization problem and PQRSM, a function-based sequential approximate optimizer equipped in PIAnO, to handle numerically noisy responses with respect to the variation of design variables. The optimal average of the standard deviations and difference in mean temperatures were found to be reduced by 9.2% and 56.52%, respectively, compared to the initial ones.

• Fire Science and Engineering
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• v.10 no.4
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• pp.3-12
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• 1996

The aim of the present study is to find out the effect of cooling rate on the electrical behavior of ZnO varistors. The microstructure, 1-V characteristics and complex impedance spectra were investigated under the change of cooling rates. It is found that at cooling rate $200^{\circ}$/h, nonlinearity and breakdown voltage reached a maximum value which may show that good intergranular layer is formed as a results of proper cooling rate. Complex Impedance spectras were measured as a function of frequency range 100Hz to 13MHz to determine grain and grainboundary resistance. The semicircles were attributed to the dependence of grain and grainboundary resistance on cooling rates.

• The Journal of Korean Physical Therapy
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• v.18 no.6
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• pp.1-11
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• 2006

Purpose: This study compared the effects of non-cold and cold conditions on the viscoelastic properties of tendon structures in vivo. Methods: Seven male subjects perfomed plantar flesion exercise with maximal isokinetic voluntary contraction, which consisted of muscle contraction for 6 see and relaxation for 60 secs, 10 times for 1 set, Totally 10 sets were repeated. Before and after each task, the elongation of the tendon and aponeurosis of the medial gastrocnemius muscle (MG) was directly measured by ultrasonography. (The relationship between the estimated tendon force and tendon elongation.) Tendon cross-sectional area and ankle joint moment arm were obtained from magnetic resonance imaging (MRI). The tendon force was calculated from the joint moments and the tendon moment arm and stress was obtained by dividing force by cross-sectional areas (CSA). The strain was measured from the displacements normalized to tendon length. Results: After cooling, the tendon force was larger in cold than non-cold. The value of the tendon stiffness of MVC were significantly higher under the cold condition than under the non-cold condition. The maximal strain and stress of $7.4{\pm}0.7%$ and $36.4{\pm}1.8$ MPa in non-cold and $7.8{\pm}8.5%,\;31.8{\pm}1.1$ MPa in cold (P<0.05). Conclusion: This study shows for the first time that the muscle endurance in cooling increases the stiffness and Young's modulus of human tendons. The improvement in muscle endurance with cooling was directly related to muscle and tendon.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.73-78
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• 2016

An increase in the transistor density of integrated circuit devices leads to a very high increase in heat dissipation density, which causes a long-term reliability and various thermal problems in microelectronics. In this study, liquid cooling method was investigated using straight microchannels with various metal bumps. Microchannels were fabricated on Si wafer using deep reactive ion etching (DRIE), and Ag, Cu, or Cr/Au/Cu metal bumps were placed on Si wafer by a screen printing method. The surface temperature of liquid cooling structures with various metal bumps was measured by infrared (IR) microscopy. For liquid cooling with Cr/Au/Cu bumps, the surface temperature difference before and after liquid cooling was $45.2^{\circ}C$ and the power density drop was $2.8W/cm^2$ at $200^{\circ}C$ heating temperature.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1313-1314
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• 2004