• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.395-398
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• 1997

In the modem manufacturing system, to achieve the unmanned automation, the stability of accuracy is required through a long working period. The thermal deformation of precision machine is predominant in this long time stability. While grinding slender and long workpiece at cylindrical grinding machine, we support workpiece using steadies to prevent the vibration of workpiece. The thermal deformation of the machine by grinding and internal heat source cause processing errors, so the steadies for compensating the thermal deformation in real time are strongly needed. In order to compensate these thermal deformation and grinding processing errors, the device to determine the precise positioning having the stroke of 10.mu.m is necessary. This paper suggests design and make the device to determine the precise positioning using thermoelectric device, to investigate the control characteristics and presents the heat actuator will be very useful in machine tool.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.36-42
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• 2000

An experimental study was carried out to investigate the effects of inclined angles of channel on thermal stability of electronic components. In this study, it is focused on the natural convection heat transfer from an inclined parallel channel with discrete protruding heat sources. The material used for the inclined parallel channel was epoxy-resin, while air as the cooling fluid. Heat transfer phenomena for inclined angles of $\psi$=$15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$ and for the range of $9.52{\times}10^5/ were analyzed. The thermal fields in the channel were visualized by Mach-Zehnder interferometer. Also, local temperatures were measured by thermocouples along the channel wall and heat sources surface. As a result, for the range of $4.29{\times} 10^5/, a useful correlation of mean Nusselt number was proposed as a function of modified channel Rayleigh number.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1047-1054
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• 2018

This paper proposed the strategies for controlling both the heater temperature and the output voltage of a single-phase inverter for the heat treatment. The single-phase inverter system for the heat treatment controls the heater temperature to its reference one, and also it limits the inverter output voltage to 60 V for safety. The stability may be deteriorated due to the large time constant difference between the heater temperature and inverter output voltage. In order to ensure the stability, a hysteresis on/off control approach for the heater temperature control is adapted, and both the open-loop and the closed-loop control strategies of the output voltage are suggested. The performances for the proposed strategies are demonstrated with the experiments.

• Bulletin of the Korean Mathematical Society
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• v.46 no.1
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• pp.87-97
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• 2009

We prove the Hyers-Ulam stability of the sine and cosine functional equations in the spaces of generalized functions such as Schwartz distributions, Fourier hyperfunctions, and Gelfand generalized functions.

• Korean journal of food and cookery science
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• v.9 no.1
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• pp.43-51
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• 1993

Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.897-898
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• 2012

• Progress in Superconductivity and Cryogenics
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• v.1 no.2
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• pp.43-48
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• 1999

The normal zone propagation (NZP) velocity and V-I characteristics of two Bi-2223 pancake coils with different Ag/SC ratio were investigated based on the experimental results and broad resistive transition were obesved in two coils. The measured NZP velocity of coil was found to be faster due to increase of Ag/SC ratio, and agree well with calculated data from two dimensional heat balance equation.

• Food Science and Preservation
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• v.4 no.1
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• pp.27-32
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• 1997

Natural convection in agricultural-products storage system was analysed theoretically, The storage system was modelled by Internally heated fluid saturated porous layer. Darcy's law was used to explain characteristics of fluid motion. Stability equations were obtained under the linear stability theory and transfer characteristics were modelled by the shape assumption. Based on the modelling of transfer characteristics, heat trasnfer correlations were derived theoretically.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.315-325
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• 2020

Boron compound had many advantages as wood preservative, but it was prone to leaching. Improving boron preservation was required to extend the service life of fast growing and low durability red jabon (Antochephalus macrophyllus) hardwood. This study aimed to evaluate the dimensional stability, color change and durability of modified red jabon wood by double impregnation with boron and methyl methacrylate (MMA) and heat treatment. Impregnation I used boric acid or borax, and impregnation II used MMA, while heat treatment used temperatures of 90 ℃ or 180 ℃ for 4 hours. The dimensional stability, leachability, water absorption, color change and decay resistance of modified red jabon wood were tested. The results showed that MMA impregnation increased the dimensional stability of red jabon wood, while the leaching and water absorption in the wood significantly reduced. Heating at 180 ℃ caused less water absorption and higher dimensional stability of the wood than that of heating at 90 ℃. Impregnation with boric acid and MMA followed by heating at 90 ℃ resulted in the highest wood ASE, 89.9%. The color change (∆E^*) of wood increased significantly after MMA impregnation and heating at 180 ℃. Boric acid impregnation caused more resistant wood than borax impregnation against decay fungi and termites. Impregnation with boric acid and MMA followed with heating at 180 ℃ increased significantly the wood resistance against decay fungi and termites.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.6
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• pp.743-752
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• 1993

To elucidate the effects of natural gums, i.e. carrageenan, locust bean gum and xanthan gum and synthetic gums, i.e. carboxymethyl cellulose(CMC) and methyl cellulose(MC) on the foaming properties of sodium caseinate, surface tension, absolute viscosity, turbidity, foaming ability, foam stability, and heat stability of the foams of the caseinate solutions with added gums were examined. The surface tension of sodium caseinate solution(5%) adding to gums at pH 4.0 and 5.0 were higher than those at pH 7.0 and 8.0. The viscosities of the solutions adding to gums(0.1, 0.2, 0.3 and 0.5%) ap pH 4.0, 5.0, 7.0 and 8.0 were 2.4~170.0, 2.5~190.0, 5.3~180.0 and 6.3~99.0 cps, respectively. Especially xanthan gums predominantly increased the viscosity. Turbidities were 97.3~98.2 at pH 4.0 and 5.0 and 93.0~95.8 at pH 7.0 and 8.0. Foaming abilities of the solution adding to xanthan gum, carrageenan and locust bean gum were increased, while those of CMC and MC were decreased. Additions of xantham gum, CMC and MC increased the foam stability, especially xanthan gum did predominantly. Xanthan gum, MC and locust bean gum were more effective than CMC and carrageenan for heat stability. For improving the foaming properties of sodium caseinate xanthan gum were best of five kinds of gums. Surface tensions and turbidities of the solution were related to foaming ability, and the viscosities were related to foam stability and heat stability.