• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.82-87
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• 2011

Heat transfer oils are used in applications such as heating systems of chemical plant, refinery heat exchange systems, gas plant process, injection molding systems, and pulp and paper processing. These oils are extremely stable and resistance to thermal and oxidative degradation. In the event of a spill or accidental release of heat transfer oils, it can be ignite easily when there is an ignition source. This paper discusses the flammability and thermal stabilities of new and used oils. The flammability of the oils are assessed by measuring changes in flash point and auto ignition temperature. The thermal stability of oils are evaluated by the thermal screening unit ($TS^u$) and the differential scanning calorimeter (DSC). From the experimental results, it is suggested to give fire hazard characteristics to safe precautions for the proper use and treatment of heat transfer oils.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.63-68
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• 2011

As an effective utilization of biomass, organic wastes and coal, attention has been made to use syngas to a reciprocating engine to generate power. However, significant component variation of syngas depending upon origin and gasification conditions, and its lower heating value than that of LPG and CNG can create difficulties in stable engine operation. Thus it is necessary to address these issues in order to successfully develop power generation engines. As a primary step to resolve these problems, effects of H2 content variation in syngas on engine performance and emission characteristics were discussed in this study. The results show that as H2 % in syngas increases, more stable combustion was achieved with retarded MBT spark timing and engine efficiency becomes maximum with syngas of 10% H2. In addition, NOx emission increased while THC emission decreased as H2 % rises in the syngas.

• Solar Energy
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• v.15 no.1
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• pp.29-38
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• 1995

This paper concerns the study of a two-stage binary absorption cycle employing the refrigerant/absorbent combinations of $LiBr/H_2O$ and $NH_3/H_2O$. This cycle consists of coupling two single-effect absorption cycles so that the first stage absorber and condenser produces heating water to evaporate refrigerant in the evaporator of the second stage. The effect of operating variables such as evaporator temperature, condenser and absorber temperature, and generator temperature on the coefficient of performance and temperature lift have been studied for two-stage binary absorption heat pump systems. It is found that this cycle has a large temperature lift at $105^{\circ}C$ of optimum generator temperature to obtain $50^{\circ}C$ of condenser temperature.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.6
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• pp.517-530
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• 2016

This research was conducted on Seoul region elementary, middle, and high school nutritionists to analyze execution conditions of HACCP control standards, focusing on PHF and CCP 3~CCP 7, in order to determine more efficient methods for school meals' sanitation system settlement. All surveys were distributed and collected via email. A total of 305 survey papers were collected, and 300 school results were analyzed. The following percentage of nutritionists perceived the following foods as potentially hazardous foods(PHF): raw or cooked animal foods (94.7%), blossomed seed products (93.7%), packed pickled radish (36.7%), unopened mayonnaise (30.2%), and unopened snails & corn cans 54.8%. Exactly 51.2% of nutritionists believed that foods were properly supplied via CCP 3's food quality standard. Exactly 33.9% of nutritionists answered that they had never corrected the digital thermometer since there were no issues with the CCP 4's digital thermometer correction frequency level. As for CCP 5's chroline disinfection of green vegetables, 57.1% of nutritionists answered that vegetables were slightly softened while 36.2% said there were no changes at all. According to the nutritionists, the most difficult execution level of CCP levels (excluding CCP 3, CCP 4) was CCP 7 (37.1%), CCP 6 (16.4%), and CCP 2 (16.4%). For the above results, proper training/education must be enforced so that nutritionists can have a clear notion of the PHF. A solution must be developed enhancing the execution of CCP 4's digital thermometer correction frequency level. For CP 5's chroline disinfection of green vegetables, food characteristics must be considered to suggest an appropriate number and method of cleansing. Furthermore, cooking employees are needed that properly use and manage cooling & heating equipments to maintain heated foods above $57^{\circ}C$ under the CCP 7 standard.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.2
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• pp.6-10
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• 2002

Al films (1000~4000${\AA}$)were deposited on glass and polymer(polyethersulfine) plastic substrates by DC-magnetron sputtering for plastic-based flat-panel displays. A stepped heating process was used both to improve the electrical characteristics and to diminish the thermal expansion of the polymer substrates. Following this procedure, we could succeed in sputtering Al films without any cracking or shrinkage of the polymer substrates. The treatment temperatures and deposited process of Al films were under 200$^{\circ}C$. Also, this low temperature fabrication process allows the application of plastic substrates. Scanning Electrom Microscopy, Atomic Force Microscopy, X-ray Dffractometry, and electrical measurements such as resistivity measurements were performed to investigate the properties of deposited the Al films and their reliability. 

• Journal of the Korean Chemical Society
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• v.54 no.2
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• pp.228-233
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• 2010

Recently, nanoparticles of gold and silver has been applied to various fields due to antimicrobial property. This study added Ag and Au nanoparticles in HEMA (2-hydroxyethylmethacrylate), NVP (N-vinyl pyrrolidone) and MMA (methylmethacrylate) and copolymerized the solution by heating at $70^{\circ}C$ for 40 minutes, $80^{\circ}C$ for 40 minutes, and finally, $100^{\circ}C$ for 40 minutes. Using the polymer produced through the copolymerization process, and measured the physical characteristics which showed water content of 28.43% ~ 35.27%, refractive index of 1.429 ~ 1.440, visible transmittance of 79.2% ~ 86.5% and tensile strength of 0.125 kgf ~ 0.201 kgf. We judged that we made the copolymer with antimicrobial and physical properties which is suitable for conventional contact lens.

• Journal of the Korean Chemical Society
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• v.54 no.2
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• pp.222-227
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• 2010

This study added Au colloid in martial of conventional contact lens in various concentrations and copolymerized by heating at $70^{\circ}C$ for 40 minutes, $80^{\circ}C$ for 40 minutes, and finally, $100^{\circ}C$ for 40 minutes. Using the polymer produced through the copolymerization process, we have produced a contact lens and measured the physical characteristics which showed oxygen transmissibility of $9{\sim}12{\times}10^{-9}$ cm/s mL $O_2$/mL ${\times}$ mmHg, water content of 27.84% ~ 32.17%, refractive index of 1.432 ~ 1.443, visible transmittance of 83.2% ~ 89.5% and tensile strength of 0.141 kgf ~ 0.152 kgf. The polymer satisfied the physical properties required to produce contact lenses. Also, we judged that the polymer is suitable to be applied as a functional material for ophthalmological purposes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.2
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• pp.101-108
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• 2013

This paper is presented an experimental study of flow boiling heat transfer characteristics of ammonia, and is focused on pressure gradient and heat transfer coefficient of the refrigerant flow inside horizontal small tube with inner diameter of 3.0 mm and length of 2000 mm. The direct heating method is applied for supplying heat to the refrigerant, where the test tube is uniformly heated by electric current. The local heat transfer coefficients were obtained over a heat flux range of 20 to $80kW/m^2$, a mass flux range of 50 to $500kg/m^2s$, a saturation temperature range of 0 to $10^{\circ}C$, and quality up to 1.0. The pressure drops increase with increasing mass flux and heat flux, and with decreasing saturation temperature. The heat transfer coefficients increase with increasing mass flux and saturation temperature in middle and high quality region. And the local heat transfer coefficient increase with increasing heat flux in low quality region. The heat transfer coefficient of the experimental result was compared with six existing heat transfer coefficient correlation. A new boiling heat transfer coefficient correlation based on the superposition model for ammonia in small tubes is developed average deviation of -0.17% and mean deviation of 10.85%.

• Fire Science and Engineering
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• v.27 no.4
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• pp.41-46
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• 2013

The present study has been conducted to investigate the reaction kinetics and pyrolysis parameters for flame propagation analysis of furniture material components. TGA measurement for component materials such as MDF (medium density fiberboad) panel including coating material, synthetic leather and foam cushion are performed under maximum temperature of $600^{\circ}C$ and heating rate of $10^{\circ}C/min$. The results of TGA have shown that the peak temperature of MDF panel was $324^{\circ}C$ and the initial peak temperature of coating material decreased by $270{\sim}280^{\circ}C$. In the case of synthetic leather and foam materials, the reference temperature and reference rate depend on the type of polymer consisting the sample, the initial kinetic characteristics was classified into 2 categories of about $270^{\circ}C$ and $420^{\circ}C$ of reference temperature for the tested synthetic materials. The present study showed the pyrolysis parameters of reference temperature and reference rate proposed by Lyon to evaluate the pre-exponential factor and activation energy. The present study can contribute to improve the reliability of computational fire analysis and enhance the understanding of fire propagation phenomena based on the thermal properties study of material.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.153-158
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• 1984

The traditional methods of testing the meltability of cheese, the Schreiber and the Arnott test, were reviewed and compared. The limitations of such methods were examined. Different sensitivities were observed for these two tests. In the Schreiber test, sharp Cheddar showed highest meltability, followed by process American, mild Cheddar, and Mozzarella. In the Arnott test, however, the rank changed to Mozzarella, mild Cheddar, sharp Cheddar, and process American. Process cheese products showed very dispersed values. Meltability increased quickly until about 4 min and held constant after 5 min in the Schreiber test. In the Arnott test, it started to increase after 5 min and held constant after 15 min. The constant meltabilities shown after certain times were caused by scorching or case hardening which prevented further flow. The DSC-thermogram showed endothermal peaks at about 14 and $30^{\circ}C$. These peaks can be accounted for by the fusion of butter fat during heating.