• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.170-175
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• 2001

Fire inside light railway transit(LRT) was simulated for various fire scenarios using CFD analysis in order to assess the safety of passengers. Considered in the present paper are the effects of locations of fire, a fire size, an operation of ventilation system and an opening time of door on evolution of temperature and smoke concentration inside the LRT. For fire simulation, fire cells releasing heat and smoke corresponding to fire size were positioned at the location of fire. From the results, it is seen that the ventilation system and the opening time of door were the most important factors on temperature and smoke concentration inside the LRT

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.387-393
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• 2008

This paper has dealt with the probability of oyster shell desiccant cooling system driven by renewable energy of photo-volatic effect with fundamental experiment. The test materials for desiccant are activated charcoal, silica-gel, hi-dry, and oyster shell. The experiments were mainly performed with focusing on the observation of surface features, adsorption amounts of the adsorbent species, and the effect of temperature. Oyster shell has sufficient probability for using as desiccant in a air-conditioning system. Moreover, the heat releasing device would be attached in the system, the system based with oyster shell can be operated with high efficiency.

• Textile Coloration and Finishing
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• v.10 no.4
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• pp.53-61
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• 1998

The absorptions of ultraviolet rays of benzophenone derivatives were investigated in terms of the position of substituent, especially hydroxyl group. When the derivatives were added to the aqueous solution of Rhodamin B, which has very low light-fastness, all of them delayed the photofading of Rhodamin B solution. But on the fabrics, only the derivatives with the hydroxyl group at 2-position showed the good ability of ultraviolet rays absorption. The benzophenone derivatives absorb ultraviolet rays to form a hydrogen bond between hydroxyl group and carbonyl group, and return to their original structure by releasing heat energy. In solution, the derivatives can form a intermolecular hydrogen bond, and absorb the ultraviolet rays. But on the fabric, the intermolecular hydrogen bond is impossible, only hydroxyl group of 2-position forms a intramolecular hydrogen bond, and that makes the derivatives on the fabric absorb ultraviolet rays.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.2
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• pp.207-213
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• 2009

The bundling process is the final step in vegetable manufacturing, however, the process is a little difficult to be automatized, because vegetable has the physical properties of roughness, softness, and fragility etc. In this paper, we proposed an automatic bundling mechanism for vegetable based on the heat melt sticking. The proposed mechanism consists of three modules, one module is the moving part for aligning of the vegetable shape and adjusting of the vegetable tension, second module is the arm driving part for the vegetable binding and the band roll releasing, and third module is band joining, band cutting, and band feeding part for the vegetable binding continuously. Through this research, Using the SMO(SimDesigner Motion) module, we optimize condition of mechanical movement of the bundling mechanism. This bundling system designed in order to binding 288 bundle/hour.

• Journal of Korean Elementary Science Education
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• v.19 no.2
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• pp.15-27
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• 2000

The purpose of this study was to survey the thinking of children, preliminary elementary teachers and elementary teachers in relation to the experiment of candle's combustion in a bottle on the water, to develop some supplementary experiments for the correction of the misconception on this experiment and to propose a new teaching method for this subject-matter The results of this study can be summarized as follows. 1. Most of the answers are related to the simple observation as the extinguishing of candlelight and the water rising in the bottle after a candle's combustion. And it is appeared that all the groups are similarly short of the ability of experimental design to verify the cause and effect. 2. from the results of the developed supplementary experiments, it is concluded that the main cause of the water rising is not the combustion of oxygen, but the expansion of volume and the releasing of air in the bottle in the bottle by heat of candle's combustion. 3. Based on the above results, a new direction for the teaching method of this subject is proposed.

• Journal of Hydrogen and New Energy
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• v.11 no.1
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• pp.43-49
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• 2000

The heat transportation from a complex of industry to a rural area needs more efficient method because the distance between them is usually more than 10km. Conventional heat transportation using steam or hot water via pipe line has limits in transportation distance (about 3~5 km) because of the heat loss and frictional loss in the pipe line. Metal hydride can absorb or discharge hydrogen through exothermic or endothermic reaction. After releasing hydrogen from metal hydride by means of the waste heat from industry, we can transport this hydrogen to urban area via pipe line. In urban areas, other metal alloy reacts with this hydrogen to form metal hydride and produces heat for heating. Cool heat is also obtained if it is possible to use metal hydride with low reaction temperature. Therefore, metal hydride can be used as a media for transportation and storage of heat. $MmNi_{4.5}Al_{0.5}Zr_{0.003}$, $LaNi_5$, $Zr_{0.9}Ti_{0.1}Cr_{0.6}Fe_{1.4}$, $MmNi_{4.7}Al_{0.1}Fe_{0.1}V_{0.1}$ alloys were selected for this purpose and the properties of those metal hydrides were discussed. The design and control techniques were proposed and discussed for this heat transportation system using metal hydride.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.323-323
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• 2013

High power light-emitting diodes (LEDs) are widely used in many device applications due to its ability to operate at high power and produce high luminance. However, releasing the heat accumulated in the device during operating time is a serious problem that needs to be resolved to ensure high optical efficiency. Ceramic or Aluminium base metal printed circuit boards are generally used as integral parts of communication and power devices due to its outstanding thermal dissipation capabilities as heat sink or heat spreader. We investigated the characterisation of electroless plating of Ni-B film according to plating bath temperature, ranging from $50^{\circ}C$ to $75^{\circ}C$ on Ag paste/anodised Al ($Al_2O_3$)/Al substrate to be used in metal PCB for high power LED packing systems. X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM) and X-ray Photoelectron Spectroscopy (XPS) were used in the film analysis. By XRD result, the structure of the as deposited Ni-B film was amorphous irrespective of bath temperature. The activation energy of electroless Ni-B plating was 59.78 kJ/mol at the temperature region of $50{\sim}75^{\circ}C$. In addition, the Ni-B film grew selectively on the patterned Ag paste surface.

• Biomolecules & Therapeutics
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• v.22 no.6
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• pp.563-569
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• 2014

Materials with differing surfaces have been developed for clinical implant therapy in dentistry and orthopedics. This study was designed to evaluate bone response to titanium alloy containing Ti-32Nb-5Zr with nanostructure, anodic oxidation, heat treatment, and ibandronate coating. Rats were randomly assigned to two groups for implantation of titanium alloy (untreated) as the control group and titanium alloy group coated with ibandronate as the experimental group. Then, the implants were inserted in both tibiae of the rats for four weeks. After implantation, bone implant interface, trabecular microstructure, mechanical fixation was evaluated by histology, micro-computed tomography (${\mu}CT$) and the push-out test, respectively. We found that the anodized, heat-treated and ibandronate-coated titanium alloy triggered pronounced bone implant integration and early bone formation. Ibandronate-coated implants showed elevated values for removal torque and a higher level of BV/TV, trabecular thickness and separation upon analysis with ${\mu}CT$ and mechanical testing. Similarly, higher bone contact and a larger percentage bone area were observed via histology compared to untreated alloy. Furthermore, well coating of ibandronate with alloy was observed by vitro releasing experiment. Our study provided evidences that the coating of bisphosphonate onto the anodized and heat-treated nanostructure of titanium alloy had a positive effect on implant fixation.

• Journal of Powder Materials
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• v.6 no.4
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• pp.314-319
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• 1999

The solid state reaction by mechanical alloying(MA) generally proceeds by lowering the free energy as the result of a chemical reaction at the interface between the two adjacent layers. However, Lee et $al.^{1-5)}$ reported that a mixture of Cu and Ta, the combination of which is characterized by a positive heat of mixing of +2kJ/mol, could be amorphized by mechanical alloying. This implies that there exists an up-hill process to raise the free energy of a mixture of pure Cu and la to that of an amorphous phase. It is our aim to investigate to what extent the MA is capable of producing a non-equilibrium phase with increasing the heat of mixing. The system chosen was the ternary $Cu_{30}Ta_{ 70-x}Mo_ x$ (x=35, 10). The mechanical alloying was carried out using a Fritsch P-5 planetary mill under Ar gas atmosphere. The MA powders were characterized by the X-ray diffraction with Cu-K $\alpha$ radiation, thermal analysis, electron diffraction and TEM micrographs. In the case of x=35, where pure Cu powders were mixed with equal amount of pure Ta and Mo powders, we revealed the formation of bcc solid solution after 150 h milling but its gradual decomposition by releasing fcc-Cu when milling time exceeded 200 h. However, an amorphous phase was clearly formed when the Mo content was lowered to x=10. It is believed that the amorphization of ternary $Cu_{30}Ta_{60}Mo_{10}$ powders is essentially identical to the solid state amorphization process in binary $Cu_{30}Ta_{70}$ powders.

• Tunnel and Underground Space
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• v.8 no.2
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• pp.107-117
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• 1998

In the case of a fire disaster in a uni-directional road tunnel, it is important to determine the critical ventilation velocity to prevent the backflow travelling toward the tunnel exit where vehicles are stopped. The critical ventilation velocity is horizontal velocity to prevent hot smoke from moving toward the tunnel exit. According to Froude modelling, the model tunnel whcih was 300mm in diameter and 21 m in length was made of acryl tubes. Inner section of acryl tubes was clothed with polycarbonate. 1/20 scaled model vehicles were installed to simulate the situation that vehicles are stopped in the tunnel exit. Methanol in a pool type burner was burned in the middle of tunnel to simulate a fire hazard. In this study, the basis of determining the critical ventilation velocity is the ventilation flow rate that is able to maintain the allowable CO concentration in the tunnel section. We assumed that the allowable CO concentration was backflow dispersion index. Futhermore, We intended to find out CO distribution and temperature distribution according as we changed ventilation velocity. The results of this study were that no backflow happened when ventilation velocity was 0.52 m/s in the case of 5.75 kW. If we adapt these results of a fire disaster releasing 10MW heat capacity in real tunnel which is 400m in length, no backflow happens when ventilation velocity is 2.31m/s. After we figured out dimensionless heat release rate and dimensionless ventilation velocity of model test and those of real test to verify experimental correctness, we tried to find out correlation between experimental results of model tunnel and those of real tunnel.