• Journal of Conservation Science
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• v.31 no.2
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• pp.87-94
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• 2015

Plastic artwork can be appeared crack, change of color and whitening event by various environment conditions. A large scale plastic artwork often exhibits in outside it will be directly degraded by physical and chemical degradation factor such as strong sunlight, high humidity and rainfall. We should know degradation characteristic of plastics to prevent these damages. In this study, we studied degradation characteristic of plastics (5 types of wide use plastics; polypropylene, polystyrene, polyethylene, polyvinyl chloride, polyurethane) depending on various artificial degradation conditions such as high temperature, ultraviolet and these complex conditions (high temperature and ultraviolet). As a result, polypropylene, polystyrene and polyethylene show the most visible change especially polypropylene, polystyrene. Polypropylene didn't show a great change degree of tensile strength and contact angle, on the other hand polystyrene did. Polypropylene and polystyrene weakened by photo degradation, polyvinyl chloride and polyurethane had relatively good light stability. Also the high temperature and complex conditions were most degradation characteristic. High temperature worked for degradation catalyst because its energy can not enough worked for cut off binding energy of plastics while ultraviolet condition effected as directly degradation condition. Though following results, we expect it can be applied to investigation of degradation factor depending on plastic artwork materials and basic result of plastic artworks conservation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.12
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• pp.1322-1329
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• 2004

End-milling has been used widely in industrial system because it is effective to a material manufacturing with various shapes. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in precision machine part and electronic part. The optimum mechanical vibration of main spindle, surface roughness and cutting temperature have an effect on end-milling condition such as, cutting direction, revolution of spindle, feed rate and depth of cut, etc. Therefore, this study carried to decide the working condition for optimum mechanical vibration of main spindle, surface roughness and cutting temperature using design of experiments, ANOVA and characteristic function. From the results of experimentation, mechanical vibration has an effect on revolution of spindle, radial depth of cut, and axial depth of cut. The surface roughness has an effect on cutting direction, revolution of spindle and depth of cut. And then the optimum condition used design of experiments is upward cutting In cutting direction, 600 rpm in revolution of spindle, 240 mm/min in feed rate, 2 mm in axial depth of cut and 0.25 mm in radial depth of cut. By design of experiments and characteristic function, it is effectively represented shape characteristics of mechanical vibration, surface roughness and cutting temperature in end-milling.

• Journal of Biosystems Engineering
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• v.30 no.4 s.111
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• pp.235-241
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• 2005

For better and large utilization of rice husk, the production and consumption status, differences in chemical composition and heating value due to region and variety, and thermogravimetric characteristic of rice husk were studied. In addition, the differences in chemical composition due to region and variety and the crystallization characteristic of rice husk ash were also studied. Approximately 800,000 M/T of rice husk was produced per year in Korea, which is about $18\%$ of the paddy production by weight. Noticeable varietal and regional difference pattern in chemical composition was not found among the domestic rice husk samples. Their average ash content and higher heating value were $16.4\%$ and 16,660 kJ/kg by dry basis, respectively. A relation seemed to exist between the carbon content and higher heating value. Noticeable difference pattern in chemical composition was not found among the domestic rice husk ash samples. The $SiO_2$ contents were a little low, the maximum being $92.9\%,$ and the contents of major components such as CaO, MgO, and $K_2O$ were also lower compared with foreign rice husk ash due to the deficiency of compost matters in domestic soils. Thermogravimetry study showed the thermal decomposition of rice husk started at about $250^{\circ}C,$ followed by relatively fast combustion of combustible gas until the temperature rose to $350^{\circ}C.$ After $350^{\circ}C,$ combustion of the carbon component proceeded relatively slowly as the temperature increased. Therefore, the ignition temperature of the rice husk could be estimated around $300^{\circ}C$. Crystallization of $SiO_2$ in the rice husk ash was found from the combustion temperature of $750^{\circ}C$ and became distinctly when the combustion temperature exceeded $900^{\circ}C$. The ash became darker with $SiO_2$ crystallization.

• Food Science of Animal Resources
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• v.32 no.3
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• pp.268-273
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• 2012

The aim of this study was to evaluate the effects of tumbling condition (time and temperature) on the quality characteristics of restructured chicken breast ham. Tumbling conditions were 10, 30, and 60 min at 3 or $-3^{\circ}C$, respectively. After tumbling, quality characteristic regarding the treatments processed by each condition were measured. There were no significant differences in pH levels among tumbling time or temperature. Treatments involving 60 min of tumbling had significantly higher water holding capacity (WHC) than that tumbled for 10 min, but WHC was not affected by the tumbling temperature. The tumbling condition at $-3^{\circ}C$ for 60 min demonstrated the most effective cooking yields for restructured chicken breast ham. Myofibrillar protein solubility of treatments tumbled for 60 min had the highest value of all, regardless of tumbling temperature. The hardness of treatments tumbled at $-3^{\circ}C$ were lower than those at $3^{\circ}C$; however, the springiness of treatments tumbled for 60 min were significantly higher than those regarding the treatments tumbled for 10 and 30 min. Therefore, tumbling technology for 30 min or more at $-3^{\circ}C$ can produce restructured chicken breast ham of excellent quality.

• The Korean Journal of Pain
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• v.22 no.2
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• pp.146-150
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• 2009

Background: A skin temperature difference is one of the variables used in the diagnosis of complex regional pain syndrome. However, there have been no reports as to whether the real (${\Delta}T$) or absolute value ($|{\Delta}T|$) of skin temperature differences should be used in the diagnosis of complex regional pain syndrome. This study was conducted to compare the diagnostic validity of ${\Delta}T$ with $|{\Delta}T|$ for complex regional pain syndrome using receiver operating characteristic curves (ROC). Methods: Infrared thermographic images were obtained from the 144 patients who were suspected to have CRPS in a unilateral limb. After ${\Delta}T$ and $|{\Delta}T|$ calculation from the thermographic image, ROCs of ${\Delta}T$ and $|{\Delta}T|$ were developed, and the areas under the curve (AUC) for the ROC curves were compared. Results: AUCs of ${\Delta}T$ and $|{\Delta}T|$ were 0.520 and 0.746 respectively, this difference was statistically significant (P < 0.001). Conclusions: Absolute skin temperature difference shows greater validity in the diagnosis of CRPS than ${\Delta}T$. Therefore, $|{\Delta}T|$ is more useful when comparing the skin temperature of CRPS patients.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.262-266
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• 2013

A new concept of periapical radiography, intra oral x-ray tube and detector system is introduced. It is new system that a miniature x-ray tube is inserted into mouse and it acquired digital image using external detector. In this study, we have investigated temperature and dose distribution of insertional x-ray tube for periapical radiography. To analyze temperature characteristic of x-ray tube, we attached the thermocouple to surface of x-ray tube and we measured the temperature according to distance. Also, we measured the dose distribution of a miniature x-ray tube according to distance. As a result, temperature was constant to $27^{\circ}C$ over 2mm without cooling system, dose distribution of x-ray tube was 3.14 and 1.84mGy in 3 and 5cm, respectively. Therefore, the proposed x-ray system works in lower dose than conventional dental x-ray system. Thus, it is considered that new concept of system will have a significant effect on medical imaging technology.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.140-145
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• 2008

The purpose of this paper is to discuss the fabrication of $\beta$-PVDF($\beta$-Polyvinylidene fluoride, ${\beta}-PVF_2$) organic thin films using the vapor deposition method. Vapor deposition was performed under the following conditions: the temperature of evaporator, the applied electric field, and the pressure of reaction chamber were $270^{\circ}C$, 142.4 kV/cm, and $2.0{\times}10^{-5}\;Torr$, respectively. The molecular structure of the evaporated organic thin films were evaluated by a FT-IR. The results showed that the characteristic absorption peaks of $\beta$-form crystal increase from 72% to 95.5% with an increase in the substrate temperature. In the analysis of the electric characteristics, the abnormal increases in the relative dielectric constant and the dielectric loss factor in the regions of low frequency and high temperature are known to be caused by inclusion of impurity carriers in the PVDF organic thin films. In order to analyze quantitatively the abnormalities in the conductivity mechanism caused by ionic impurities, the product of the ion density and the mobility that affect the electrical property in polymeric insulators is analyzed. In the case of a specimen produced by varying the substrate temperature from $30^{\circ}C$ to $105^{\circ}C$, the product of mobility and the ion density decreased from $4.626{\times}10^8$ to $8.47{\times}10^7/V{\cdot}cm{\cdot}s$. This result suggests that the higher the substrate temperature is maintained, the better excluded the impurities are, and the more electrically stable material can be obtained.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1789-1791
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• 1999

In consideration of piezoelectric characteristic and Temperature stability, 3-element system dopped with NiO, $Cr_2O_3$ well-known as Hardner and Stabilizer whose primary element is PZT was eximanated its structure, piezoelectric characteristics, dopping with Nio, $Cr_2O_3$. We think that piezoelectric Characteristic is developed, remenent polarization and $E_c$ can developed in specimens by dopping with NiO, $Cr_2O_3$ additive. also, electromechanical quality factor largely showed tendency of decrement. According to dopping NiO, $Cr_2O_3$ more.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.626-629
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• 2012

In this paper, Actual refrigeration system and the data were analyzed in order to provide basic design data of Refrigeration system using the characteristic curve of the refrigerant. On the basis of the characteristic curve of the refrigerant developed simulation program and data of refrigeration system equipment data consisting of compressor, condenser, Receiver content, expansion valve, evaporator, liquid separator, leading to changes in temperature and Moliere were analyzed.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.7
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• pp.99-104
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• 2009

Creep characteristic is an important failure mechanism when evaluating engineering materials that are soft as polymers or used as mechanical elements at high temperatures. One of the popular thermo-elastic plastics, Polyethylene(PE) which is used broadly for engineering purposes, as it has good properties and merits compared to other plastics, was studied for creep characteristic at various level of stresses and temperatures. From the experimental results, the creep limit of PE at room temperature is 75% of tensile strength. Also the creep limits decreased exponentially as the temperatures increased, up to 50% of the melting point. Also the secondary stage among the three creep stages was nonexistent nor was there any rupture failure which occurred for many metals.