• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.45-51
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• 2006

The purpose of this study is to investigate experimentally the heat transfer characteristics of combustion gas or a mixture fuel of LFG and LNG as compared LFG, LNG A Pilot combustion system is constructed. Tube bundle type heat exchangers with vertical and horizontal baffles are used, and the experiment is carried out for different operating conditions, the heating value, the concentration of methane (44.5%, 54.5%). The results show that the Nusselt number of LNG is higher than that of LFG at the same Reynolds number, and in case LFG, the Nusselt number of the mixture of LFG and LNG is larger than that of LFG alone. Therefore, heat transfer is improved by using LFG that is added to LNG pertinently, if and instability of LFG supply will be relaxed.

• Journal of the Korean Institute of Gas
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• v.9 no.3 s.28
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• pp.9-14
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• 2005

To estimate the explosion characteristics of converted gas, the study was examined into effects of altering oxygen concentration and adding hydrogen. From the result of the experiment, as the concentration of converted gas and hydrogen were increased at $21\%$ oxygen concentration, the lower explosion limit was low. Minimum explosion oxygen concentration was $6\%$. Maximum explosion pressure of converted gas was $4.61 kg_f/cm^2$, now Maximum explosion pressure rising velocity was $130.75 kg_f/cm^2/s$ at converted gas concentration $40\%$. Also, minimum ignition energy was 0.13 mJ at converted gas concentration $50\%$.

• Journal of Biomedical Engineering Research
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• v.30 no.5
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• pp.418-427
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• 2009

As many people are westernizing their life style and food consumption habits, a number of patients who have malignant tumors which grow very rapidly and hazardously destroy the human body are increasing. Ultrasonic hyperthermia is not only one of the tumor treatment methods which employs the non-radioactive ultrasonic waves to increase the temperature at the tumor region up to $40\sim45^{\circ}C$ to destroy and suppress tumor cells but also has been proved by many studies. Due to the rapid development of High Intensity Focused Ultrasound(HIFU), the ultrasound hyperthemia extensively boosts its applications in clinical field. For those reasons, Computed simulation factor should be needed before inspection to patients. To prove efficiency of ultrasonic hyperthermia, precise acoustic field measurement considering tissue characteristics and a heating experiment with tissue mimicking material phantom were conducted for effectiveness of simulation program. Finally, in this study, the computer simulation program verified the anticipated temperature effects induced by ultrasound hyperthermia. In the near future, it is hoped that this simulation program could be utilized to improve the efficiency of ultrasound hyperthermia.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1163-1168
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• 2011

Most transformers use insulating and cooling fluids derived from petroleum crude oil, but mineral oil has some possibility of environmental pollution and fire with explosion. vegetable oil fluids extracted from seed has superior biodegradation and fire-resistant properties including an exceptionally high fire point enhancing fire safety. In this study, it is aimed at the practicality of substituting natural ester dielectric fluid for mineral oil in liquid insulation system of transformers. As a rise in coil winding temperature has a direct influence on transformer life time, it is important to evaluate the temperature rise of coil winding in vegetable oil in comparison with mineral oil. Four transformers for the test are designed with 10KVA, 13.2KV, one phase unit. The temperature are directly measured in insulating oil of these transformers with the two sorts of natural ester and mineral oil dielectric fluid respectively. Experiment for aging carry out two means. First means remained $120^{\circ}C$ that transformer of mineral oil were operated at 185% load. Second means is that insulating oils of two natural ester and mineral oil were aged by thermal cycles repeating from $30^{\circ}C$ to $120^{\circ}C$. For the heating, Transformers were operated at 185% load. For the cooling, cooling system was operated in the chamber. Samples were analyzed at 42, 63, 93, 143, 190, 240 300cycles. Analysis contents are dielectric strength, total acid value. Mineral oils compared results of first means with results of second means. And compared two sort natural esters respectively with mineral oil in second means.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.169-175
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• 2009

In this experiment molybdeum oxide($MoO_3$) films were prepared by a magnetic null discharge(MND) sputtering system and fundamental properties by XRD, XPS and SEM analysis were investigated. The initial and mean insulation resistance of the same with $MoO_3$ film were about 1.4[$M{\Omega}$] and 800[$k{\Omega}$] under the condition of applied voltage of 400[V]. The preferred orientation in the films changed from(100) to (210) with substrate temperature. Two XPS peaks of the $MoO_3$ photoelectron were detected at the binding energies of 228.9[eV] and 232.4[eV], while the binding energy of the O1s peak was 532.6[eV]. The substrate temperature and reactivity gives large effects to the structure and growth of the film and system is also very useful for performing the uniform reactive deposition. It can be found from the result of a $MoO_3$ film deposition that the system is very useful for performing the uniform reactive sputtering.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.1
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• pp.76-84
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• 2013

In this study, thermal weight loss, non-isothermally experiment, chemical composition analysis, calorific value, activation energy (E) were investigated to analysis the kinetic study of RDF, wood pellets, waste wood, waste textile and waste vinyl. When the chemical composition of solidification fuel was compared, the moisture content of RDF was less than the wood pellet and when the kinetic study was compared, the combustion reaction rate of the waste vinyl was higher than any other solidification fuels. However when the combustion efficiency was compared by the activation energy, the RDF had the higher efficiency than other wastes. RDF can be found that the reaction takes place between $320{\sim}720^{\circ}C$ depending on the heating rate.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.2
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• pp.141-150
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• 2000

In order to genralize the vertical dispersion of plume at long distances on mesoscale over complex terrain dispersion coefficients data have been obtained systematically according to lapsed time after release by using a composite turbulence water tank that simulates convective boundary layer. Dispersion experiments have been carried out for various combined conditions of thermal turbulence intensity mechanical turbulence intensity and plume release height at slightly to moderately unstable conditions. Results of tracer dispersion experiments conducted using water tank camera and image processing system have been converted into atmospheric dispersion data through the application of similarity law. The equation $\sigma$z/Zi=aX/(b+c X2)0.5 where $\sigma$2; vertical dispersion coefficient zi : mixing height X : dimen-sionaless downwind distance was confirmed to be an appropriate and general equation for expressing $\sigma$2 variation with turbulence intensity and plume release height, The value of "a" was found to be principally affected by mechanical turbulence intensity and that of "b" by mechanical turbulence intensity and release height. It was confirmed that the magnitude of "c" varies with release height. Results of water tank experiments on the relationship of $\sigma$2 vs downwind distance x have been compared with actual atmospheric dispersion data such as CONDORS data and Bowne's nomogram Operating conditions of a composite turbulence water tank for simulating the field turbulence situations of CONDORS experiments and Bowne's $\sigma$2(x) nomogram for suburban area have also been investigated in terms of water temperature difference between convection water tank and bottom plate heating tank grid plate stroke mixing water depth length scale and velocity scale. Moreover the effect of mechanical turbulence intensity on vertical dispersion has been discussed in the light of release height and downwind distance. height and downwind distance.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.7-12
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• 2013

Tin oxide thin-films have been widely applied in various fields of high-technology industries due to their excellent physical and electric properties. Those applications are found in various sensors, heating elements of windshield windows, solar cells, flat panel displays as tranparent electrodes. In this study, we conducted an experiment for the deposition of $SnO_2$ on glass of 2nd Gen. size for the effective development of large-scale backplanes. As deposition temperatures or flow rates of the $SnCl_4$ as a precursor changed, the thickness of tin oxide thin-films, their sheet resistances, transmittances, and hazes varied considerably.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.498-498
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• 2013

Atmospheric Pressure Plasmas have pioneered a new field of plasma for biomedical application bridging plasma physics and biology. Biological and medical applications of plasmas have attracted considerable attention due to promising applications in medicine such as electro-surgery, dentistry, skin care and sterilization of heat-sensitive medical instruments [1]. Traditional approaches using electronic devices have limits in heating, high voltage shock, and high current shock for patients. It is a great demand for plasma medical industrial acceptance that the plasma generation device should be compact, inexpensive, and safe for patients. Microwave-excited micro-plasma has the highest feasibility compared with other types of plasma sources since it has the advantages of low power, low voltage, safety from high-voltage shock, electromagnetic compatibility, and long lifetime due to the low energy of striking ions [2]. Recent experiment [2] shows three-log reduction within 180-s treatment of S. mutans with a low-power palm-size microwave power module for biomedical application. Experiments using microwave plasma are discussed. This low-power palm-size microwave power module board includes a power amplifier (PA) chip, a phase locked loop (PLL) chip, and an impedance matching network. As it has been a success, more compact-size module is needed for the portability of microwave devices and for the various medical applications of microwave plasma source. For the plasma generator, a 1.35-GHz coaxial transmission line resonator (CTLR) [3] is used. The way of reducing the size and enhancing the performances of the module is examined.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.956-960
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• 2007

The objective of this study is to remove BTEX(Benzene, Toluene, Ethylene, Xylene) and TPH(Total Petroleum Hydrocarbon) effectively by using method low thermal desorption. The thermal desorption is frequently selected because it can treat various contaminants effectively. The temperature and heating time are determined by TGA(Thermogravimetric analysis) curve. The experiment result from this research, removal rate of BTEX was up to 100% within 5 minutes and removal rates of TPH were more than 65% at $300^{\circ}C$ and 70% at $500^{\circ}C$ respectively. It was observed that there was a little change of removal rates of TPH.