• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.449-454
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• 2008

Some pretreatment methods have been proposed to enhance the biodegradability and to shorten the hydrolysis reaction time. By means of efficient pretreatment the suspended solids (SS) can be made of better accessible for the anaerobic bacteria. There are several ways how this can be accomplished, which include biological, mechanical, thermal, and chemical methods. For the sludge solubilization using the cavitation phenomenon, we have tried to develop a pretreatment process consisted of a reactor and pumps. The objectives of this study were to develop a advanced wastewater treatment consisted of IABR and the cavitation with PGA. The most effective removal for organic matter and nutrients were occured when both cavitation pretreatment and ${\gamma}$-PGA were applied at the IABR process. Only small portion of ${\gamma}$-PGA at a rate of 1.38mg/L, was enough to improve sedimentation ability, SS removal efficiencies, and sludge volume reduction. After the sludge solubilization by the cavitation, SCOD increased to 193% and SS decreased to 36%. The removal ratio of BOD was 94.5%, T-N removal ratio was 85.5% and T-P removal ratio was 84.9%. The combination process of the IABR with the cavitation and PGA addition seems to be very effective alternative wastewater treatment process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1284-1292
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• 2006

Heat treatment is a controlled heating and cooling process to improve the physical and/or mechanical properties of metal products without changing their shapes. Today finite element method is widely used to simulate lots of manufacturing processes including heat treatment and surface hardening processes, which aims to reduce the number of time- and cost-consuming experimental tryouts. In this study we tried, using this method, to simulate the full carburizing process that consists of carburizing, diffusing and quenching, and to predict the distribution of carbon contents, phase fraction and hardness, thermal deformation and other mechanical characteristics as the results. In the finite element analysis deformation, heat transfer, phase transformation and diffusion effects are taken into consideration. The carburizing process of a lock gear, a part of the car seat recliner, that is manufactured by the fine blanking process is adopted as the analysis model. The numerical results are discussed and partly compared with experimental data. And a combination of process parameters that is expected to give the highest surface hardness is proposed on the basis of this discussion.

• Journal of Acupuncture Research
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• v.25 no.1
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• pp.89-95
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• 2008

Objectives : To investigate changes in facial temperature generated by Miso Facial Rejuvenation Acupuncture treatment. Methods : One middle-aged woman with no diseases was recruited. Miso Facial Rejuvenation Acupuncture was performed on only the right side of her face. We measured her facial temperature using digital infrared thermal imaging(DOREX Inc. Spectrum 9,000MB, USA, D.I.T.I) before, immediately after, and 10 minutes after treatment. We also used the Wilcoxon signed rank test(p<0.05) to compare the differences in facial temperature from one side of the face to the other at each time. Results : Facial temperature on the right side(the area treated by acupuncture) increased immediately from $30.02{\pm}1.87^{\circ}C$ to $32.24{\pm}1.03^{\circ}C$, a statistically significant increase. Ten minutes after treatment, facial temperature on the right side decreased a little bit, but there was no statistical significance. Facial temperature on the left side increased a little, but there was no statistical significance. The difference between the right and left sides of the face increased after the Miso Facial Rejuvenation Acupuncture treatment. Conclusions : Miso Facial Rejuvenation Acupuncture could increase facial temperature.

• Journal of Oriental Medical Thermology
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• v.6 no.1
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• pp.32-38
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• 2008

Objective: To investigate the changes of facial temperature by Miso Facial Rejuvenation Acupuncture treatment. Methods: One middle-aged women who has no other disease was recruited. The Miso Facial Rejuvenation Acupuncture was performed on only right face. We measured the facial temperature using the Digital Infrared Thermal Imaging (DOREX Inc. Spectrum 9000 MB, USA, D.I.T.I.) before, immediate after and 10 minutes after treatment. And we used the Wilcoxon signed rank test (P<0.05) to compare the difference of facial temperature at each time. Results: Right facial temperature (the area treated by acpuncuture) increased immediately from $30.02{\pm}1.87^{\circ}C$ to $32.24{\pm}1.03^{\circ}C$, the change of temperature is statistically significant. At 10 minutes after treatment, right facial temperature decreased little, but there was no statistical significance. Left facial temperature increased little, but there was no statistical significance. The difference between right and left face increased after Miso facial rejuvenation acupuncture treatment. Conclusion: Miso facial rejuvenation acupuncture could make the facial temperature increase.

• Applied Science and Convergence Technology
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• v.25 no.3
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• pp.51-55
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• 2016

The surface treatment of a titanium implant is investigated with a non-thermal atmospheric pressure plasma jet. The plasma jet is generated by the injection of He and $O_2$ gas mixture with a sinusoidal driving voltage of 3 kV or more and with a driving frequency of 20 kHz. The generated plasma plume has a length up to 35 mm from the jet outlet. The wettability of 4 different titanium surfaces with plasma treatments was measured by the contact angle analysis. The water contact angles were significantly reduced especially for $O_2/He$ mixture plasma, which was explained with the optical emission spectroscopy. Consequently, plasma treatment enhances wettability of the titanium surface significantly within the operation time of tens of seconds, which is practically helpful for tooth implantation.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.3
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• pp.161-173
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• 2023

This study investigated the effects of K_N and process time on the formation of a compound layer at a nitriding temperature of 540℃ for SCR420H material. As a result of controlled nitriding from 3 h to 20 h at K_N 1.2 atm^-1/2, compound layers were formed up to about 10 ㎛, and an effective hardening depth of about 460 ㎛ was obtained. Initially, an ε+γ' complex phase was formed, and the phase fraction changed over time, and finally, the fraction of ε phase decreased to less than 1%. With higher K_N, the compound thickness increased, a pore layer was formed on the surface, and the surface hardness decreased. By applying the controlled nitriding process, it was possible to produce annulus gears with a compound thickness of 12.8 ㎛ and an ε phase of 5% or less. The annulus gears made through controlled nitriding were mounted on a 6-speed transmission and tested for durability. As a result, the durability test of 250,000 km was satisfied, and the transmission efficiency was also confirmed to be expected.

• Journal of Soil and Groundwater Environment
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• v.18 no.6
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• pp.32-37
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• 2013

The scope of this study was to develop, design, and build an ex-situ remediation system of using the heating and water sparging treatment for the highly volatile DNAPL (Dense Non-Aqueous Phase Liquid) contaminated groundwater, and to conduct pilot testing at the site contaminated with DNAPL. The TCE (Trichloroethylene) removal was at the highest rate of 94.6% with the water sparging at $70^{\circ}C$ in the lab-scale test. The pilot-scale remediation system was developed, designed, and fabricated based on the results of the lab-scale test conducted. During the pilot-scale testing, DNAPL-contaminated groundwater was detained at heat exchanger for the certain period of time for pre-heating through the heat exchanger using the thermal energy supplied from the heater. The heating system supplies thermal energy to the preheated DNAPL-contaminated groundwater directly and its highly volatile TCE, $CCl_4$ (Carbontetrachloride), Chloroform are vaporized, and its vaporized and treated water is return edback to the heat exchanger. In the pilot testing the optimum condition of the HWSRS was when the water temperature at the $40^{\circ}C$ and operated with water sparging concurrently, and its TCE removal rate was 90%. The efficiency of the optimized HWSRS has been confirmed through the long-term performance evaluation process.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.130-134
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• 2016

The influence of Au/Ni-based contact formed on a lightly-doped (7.3×1017cm−3, Zn-doped) InGaAsP layer for electrical compensation of surface plasmon polariton (SPP) propagation under various rapid thermal annealing (RTA) conditions has been studied. The active control of SPP propagation is realized by electrically pumping the InGaAsP multiple quantum wells (MQWs) beneath the metal planar waveguide. The metal planar film acts as the electric contact layer and SPP waveguide, simultaneously. The RTA process can lower the metal-semiconductor electric contact resistance. Nevertheless, it inevitably increases the contact interface morphological roughness, which is detrimental to SPP propagation. Based on this dilemma, in this work we focus on studying the influence of RTA conditions on electrical control of SPPs. The experimental results indicate that there is obvious degradation of electrical pumping compensation for SPP propagation loss in the devices annealed at 400℃ compared to those with no annealing treatment. With increasing annealing duration time, more significant degradation of the active performance is observed even under sufficient current injection. When the annealing temperature is set at 400℃ and the duration time approaches 60s, the SPP propagation is nearly no longer supported as the waveguide surface morphology is severely changed. It seems that eutectic mixture stemming from the RTA process significantly increases the metal film roughness and interferes with the SPP signal propagation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.174-180
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• 2019

In this study, we evaluated and analyzed the properties of polymeric transparent films used in military vehicle covers according to weathering test. Two types of polymer films (Film A and Film B) that are mostly used for military vehicle covers were selected. The weathering treatment condition and tester are described in KS K 0706, and the following weathering times were tested: 0hour, 40hours, 160hours and 320 hours. The tensile strength, elongation and thermal decomposition behavior and optical characteristics were analyzed. The tensile strength tended to decrease - increase - decrease with increasing weathering treatment time in both transparent films. The thermal decomposition temperature gradually decreased. Regarding the optical property, the light transmittance decreased and the haze tended to increase. However, film A showed almost similar optical characteristics after 160-hour weathering treatment.

• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.590-597
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• 2013

High voltage pulsed electric fields (PEF) treatment is a promising non-thermal processing technology that can replace or partially substitute for thermal processes. The aim of this research was to investigate the microbial inactivation mechanisms by PEF treatment in terms of physiological changes to Saccharomyces cerevisiae. PEF was applied at the electric field strength of 50 kV/cm, treatment time of 56 ${\mu}s$ and temperature of $40^{\circ}C$. The microbial cells treated with PEF showed loss of salt tolerance on the cell membrane and collapse of the relative pH gradient on in-out of cells. Cell death or injury resulted from the breakdown of homeostasis, decreased $H^+$-ATPase activity, and loss of glycolysis activity.