• Radiation Oncology Journal
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• v.5 no.1
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• pp.49-58
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• 1987

Hypertermia for the treatment of cancer has been introduced for a long time and the biological effect for the use of hyperthermia to treat malignant tumors has been well established and encouraging clinical results have been obserbed. Unfortunately, however, the engineering or technical aspects of hyperthermia for the deep seated tumors has not been satisfactory. We developed the radiofrequency capactive hyperthermia device (Greenytherm-GY8) in cooperation with Yonsei Cancer Center and Green Cross Medical Corporation. It was composed with $8{\sim}10MHz$ RF generator, capacitive electrode, matching system, cooling system, temperature measuring system and control PC computer. The thermal profile was investigated in agar phantom, animals and in human tumors, heated with capactivie RF device. Deep and homogeneous heating could be achieved in a large phantom of 25cm diameter and 19cm thick when heated with a pair of 23cm diameter electrodes, coupled to both bases of the phantom, when the size of the two electrodes was not the same, the region near the smaller electrode was preferentially heated. It was, therefore, possible to control the depth of heating by choosing proper size of electrodes. Therapeutic temperature $(42^{\circ}C{\sim}43^{\circ}C)$ could be obtained in the living animal experiments. Indications are that deep heating of humn tumors might be achieved with the capacitive method, provided that subcutaenous fat layer is cooled by temperature controlled bolus and large size of electrodes.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.123-133
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• 2000

The kinetic analysis was carried out for commercial rubbers such as NR, IR, BR, SBR 1500, and SBR 1700. Kinetic analysis for the commercial rubbers was performed using the thermogravimetric method, with which the activation energies of NR obtained by Kissinger, Friedman, and Ozawa's method were 195.0, 198.3 and 186.3kJ/mol, whereas that of SBR 1500 were 246.4, 247.5 and 254.8kJ/mol, respectively. It was shown that the yield of pyrolytic oil was generally increased with final temperature increasing, yet slightly decreased or increased over $700^{\circ}C$. Considering the effect of heating rate, it was found that the yield of pyrolytic oil was not consistent for each sample. The number average molecular weight of SBR 1500 was in the range of 740~2486. The calorific value of SBR 1500 was 39~40kJ/g, which were made comparative study of the conventional fuel such as kerosene, diesel, light fuel, and heavy fuel. Therefore it was essential that the selection of the suitable kinetic model and the mathematical solution because of the difference in parameters obtained from each method. It was proposed that the range of $600~700^{\circ}C$ in final temperature and high heating rate due to short run time. It was suggested that the pyrolytic oil be available to use to the fuel.

• Fire Science and Engineering
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• v.1 no.1
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• pp.19-26
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• 1987

In this study, fire resistance of steel fiber reinforced concrete was investigated Cylindrical and prismatic specimens made of Ordinary Portland Cement plain concrete and steel fiber reinforced concrete were exposed to heating in accordance with a standard time-temperature curve as specified in KS·F22 57, method of fire resistance test for structural parts of buildings, the period of heating was 1 hour and 2 hours. After the fire resistance test, mechanical properties of specimens such as compressive and bending strength, stress-strain curve, static and dynamic modulus of elasticity and bending toughness were investigated. Also the cracks and spallings of the specimens were observed. From the test results, it was confirmed that steel fiber reinforced concrete has a excellent fire resistance than plain concrete in the view of higher residual strength of concrete and smaller crackings because of steel fibers in concrete.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.14 no.3
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• pp.175-186
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• 1985

This paper presents a method for estimating the useful output of solar space heating system and estimates their performance with variance of collector size, storage volume, collector tilt and other factors . The analysis is performed by the computer simulation and by 'running' conceptual systems against solar intensities and ambient temperature for a model year stored in a computer. System performance is analyzed on monthly and yearly basis respectively and at the same time, the economics of various systems are evaluated . And also, this paper shows how an optimized design can be selected for any locality for which solar data, economic parameters and system performance are provided. It is shown that storage volume of 75 liter per $m^2$ of solar collector lead to the best design.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.135-135
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• 2017

Greenhouse have been developed to provide the plants with good environmental conditions for cultivation crop, two major factors of which are the inside air temperature and humidity. The inside temperature are influenced by the heating systems, ventilators and for systems among others, which in turn are geverned by some type of controller. Likewise, humidity environment is the result of complex mass exchanges between the inside air and the several elements of the greenhouse and the outside boundaries. Most of the existing models are based on the energy balance method and heat balance equation for modelling the heat and mass fluxes and generating dynamic elements. However, greenhouse are classified as complex system, and need to make a sophisticated modeling. Furthermore, there is a difficulty in using classical control methods for complex process system due to the process are non linear and multi-output(MIMO) systems. In order to predict the time evolution of conditions in certain greenhouse as a function, we present here to use of recurrent neural networks(RNN) which has been used to implement the direct dynamics of the inside temperature and inside humidity of greenhouse. For the training, we used algorithm of a backpropagation Through Time (BPTT). Because the environmental parameters are shared by all time steps in the network, the gradient at each output depends not only on the calculations of the current time step, but also the previous time steps. The training data was emulated to 13 input variables during March 1 to 7, and the model was tested with database file of March 8. The RMSE of results of the temperature modeling was $0.976^{\circ}C$, and the RMSE of humidity simulation was 4.11%, which will be given to prove the performance of RNN in prediction of the greenhouse environment.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.489-494
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• 2013

Nano-sized titanium oxide powders were synthesized by a polymer matrix technique using pulp and Titanium tetraisopropoxide (TTIP) as starting materials. The synthesized powders were characterized by XRD and FE-SEM. The particle size of the powders was controlled by preparation conditions, such as heat treatment temperature and time. After investigating various drying and heat treatment conditions, 50-100 nm sized homogeneous titanium oxide particles were obtained by treating at $600^{\circ}C$ for 1 h. The crystallization and rapid growth of particles was accelerated by increasing heat treatment temperature and time. Anatase phase generated below $600^{\circ}C$ transformed to the rutile phase with increasing heat treatment temperature. Moreover, above $800^{\circ}C$, heat treatment time had a very large influence on particle growth, and changing the heating condition also had a large influence on crystal growth.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.275-281
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• 2013

This study was conducted to increase the amount of bio-hydrogen production from microalgae(Chlorella vulgaris) in batch reactors by thermal pre-treatment. The optimization of thermal pre-treatment was conducted using statistic experimental design of response surface methodology. Two experimental parameters of temperature and reaction time were considered. The optimization condition was founded at the coded variables of <0.52, -0.07> corresponding to the experimental of heating temperature of $95.6^{\circ}C$ and reaction time of 57.9 min, respectively. Under the optimal condition, the maximum hydrogen production was predicted to 25.3mL $H_2/g$ dry cell weight (dcw), which was 9.1 times higher value of control(2.8mL $H_2/g$ dcw).

• Advanced Composite Materials
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• v.16 no.4
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• pp.385-394
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• 2007

In this study, the effect of molding condition on the tensile properties for plain woven hemp fiber reinforced green composite was examined. The tensile properties of the composite were compared with those of the plain woven jute fiber composite fabricated by the same process. Emulsion type biodegradable resin or polypropylene sheet was used as matrix. The composites were processed by the compression molding where the molding temperature and its heating time were changed from 160 to $190^{\circ}C$ and from 15 to 25 min, respectively. The following results were obtained from the experiment. The tensile property of hemp fiber reinforced polypropylene is improved in comparison with polypropylene bulk. The strength of composite is about 2.6 times that of the resin bulk specimen. Hemp fiber is more effective than jute fiber as reinforcement for green composite from the viewpoint of strength. The molding temperature and time are suitable below $180^{\circ}C$ and 20 min for hemp fiber reinforced green composite. Hemp fiber green composite has a tendency to decrease its tensile strength when fiber content is over 50 wt%.

• Journal of Korea Foundry Society
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• v.2 no.1
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• pp.2-11
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• 1982

In order to investigate the relationship between the thermal characteristics of the various molds as green sand mold, dry sand mold, $CO_2$ mold and shell mold, and the solidification characteristics of molten metal, the thermal analysis of rarious molds and melt were performed. The structure of Al-Castings was a/so observed. Results obtained in this experiment were as follows : 1) The heating rate of the molds was increased in the order of green sand mold, $CO_2$ mold, dry sand mold and shell mold, On the other hand the solidification time of the melts was shortened in the order of dry sand mold castings, $CO_2$ mold castings, green sand mold castings and shell mold castings. 2) The arrest temperature period in the heating curve of the green sand mold was resulted from the eraporation of moisture contained in mold, which was transfered to the outer side of the mold. 3) The temperature fluctuation of the melt in the shell mold was considered to be resulted from the combution heat of resin contained in the mold. 4) The amounts of heat absorption of the molds were increased in the order of dry sand mold, $CO_2$ mold, green sand mold and shell mold. 5) The higher the solidification rate was, the longer was its shrinkage pipe and the finer its grain size.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.792-799
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• 2019

The present study aims to investigate the fluorination of thorium oxide ($ThO_2$) by ammonium hydrogen difluoride ($NH_4HF_2$). Fluorination was performed at room temperature by mixing $ThO_2$ and $NH_4HF_2$ at different molar ratios, which was then left to react for 20 days. Next, the mixtures were analyzed using X-ray diffraction (XRD) at the intervals of 5, 10, 15, and 20 days, followed by the heating of the mixtures at $450-750^{\circ}C$ with argon gas flow. The characterization of $ThF_4$ was established using X-ray diffraction (XRD) and scanning electron microscopy-dispersion X-ray spectroscopy (SEM-EDX). In this study, ammonium thorium fluoride was synthesized through the fluorination of $ThO_2$ at room temperature. The optimum molar ratio in synthesizing ammonium thorium fluoride was 1.0:5.5 ($ThO_2:NH_4HF_2$) with 5 days reaction time. In addition, the heating of ammonium thorium fluoride at $450^{\circ}C$ was sufficient to produce $ThF_4$. Overall, this study proved that $NH_4HF_2$ is one of the fluorination agents that is capable of synthesizing $ThF_4$.