• 한국환경과학회지
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• 제20권7호
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• pp.881-890
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• 2011

In this study, thermal environment changes for a marathon course of IAAF World Championship, Daegu 2011 were modeled to provide improvements of thermal environment, so that runners could have the maximum condition and citizens pleasant streets. The three biggest size of intersections were selected for the study. Envi-met, 3G microclimate model, were used for a thermal environment analysis and three different cases - present status, planting roadside tree scenario, and roof-garden scenario - were compared. The followings are the results of the study. 1. The highest thermal distribution were shown at 1 p.m., but there was no significant difference between a thermal distribution at 1 p.m. and that at 5 p.m. since a heat flux from buildings affects thermal distributions rather than insolation does. 2. Tree planting or adding environmental friendly factors might lead a temperature drop effect, but the effect was not significant for areas covered with impermeability packing materials such as concrete or asphalt (especally, for Site case 2) 3. The combination of tree planting and adding environmental friendly factors also brought a temperature drop effect (Site 1 and 2) and this case showed even better result if green spaces (especially, parks) were closed.

• 한국음향학회지
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• 제12권1호
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• pp.47-54
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• 1993

Performance analysis is very important to transmit the high quality information and to construct the optimal system for the minimze the noise from the channel of spread spectrum system. In this paper the error rate performance is analyzed with computer simulation in noncoherent frequency hopping M-qry frequency shift keying(FH/MFSk) systems with regard to thermal noise under the partial band jamming environments. AS a result, in case the thermal noise is disregarded, bit error probability of system in jamming fraction ρ and Eb/Nj(bit energy to jamming power density) is reduced with the increase of K and in worst case 32FSK system is better than 2FSK system by 3.23dB with the variatio of Eb/Nj. In case thermal noise is considered, bit error probability of system by 3.23dB with the variation of Eb/Nj. In case thermal noise is considered, bit error probability of system are reduced with the increase of K and Eb/No(bit energy to thermal noise density). Bit error probability in connection with worst case ρ is not largely influenced form over the 14dB to K=1 and 8dB to K=5 accordingly thermal noise disregarding. These results may be useful for avoiding the common vulnerabilities when the spread spectrum system is designed.

• Journal of the Korean Wood Science and Technology
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• 제34권5호
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• pp.59-66
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• 2006

The thermal properties of wood flour, Hwangto, and maleated polyethylene (MAPE) reinforced HDPE composites were investigated in this study. The thermal behavior of reinforced wood polymer composites was characterized by means of thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses. Hwangto and MAPE were used as an inorganic filler and a coupling agent, respectively. According to TGA analysis, the increase of wood flour level increased the thermal degradation of composites in the early stage, but decreased in the late stage. On the other hand, Hwangto reinforced composites showed the higher thermal stability than virgin HDPE, from the determination of differential peak temperature ($DT_p$). Decomposition temperature of wood flour and/or Hwangto reinforced composites increased with increase of heating rate. From DSC analysis, melting temperature of reinforced composites little bit increased with the addition of wood flour or Hwangto. As the loading of wood flour or Hwangto to HDPE increased, overall enthalpy decreased. It showed that wood flour and Hwangto absorbed more heat energy for melting the reinforced composites. Hwangto reinforced composites required more heat energy than wood flour reinforced composites and virgin HDPE. Coupling agent gave no significant effect on the thermal properties of composites. Thermal analyses indicate that composites with Hwangto are more thermally stable than those without Hwangto.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.288-291
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• 2002

Application of metal silicides such as TiSi$_2$ and CoSi$_2$ as contacts and gate electrodes are being studied. However, TiSi$_2$ due to the linewidth-dependance, and CoSi$_2$ due to the excessive Si consumption during silicidation cannot be applied to the deep-submicron MOSFET device. NiSi shows no such problems and can be formed at the low temperature. But, NiSi shows thermal instability. In this investigation, NiSi was formed with a Ti-capping layer to improve the thermal stability. Ni and Ti films were deposited by the thermal evaporator. The samples were then annealed in the N$_2$ ambient at 300-800$^{\circ}C$ in a RTA (rapid thermal annealing) system. Four point probe, FESEM, and AES were used to study the thermal properties of Ti-capped NiSi layers. The Ti-capped NiSi was stable up to 700$^{\circ}C$ for 100 sec. RTA, while the uncapped NiSi layers showed high sheet resistance after 600$^{\circ}C$. The AES results revealed that the Ni diffusion further into the Si substrate was retarded by the capping layer, resulting in the suppression of agglomeration of NiSi films.

• 한국미생물·생명공학회지
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• 제5권1호
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• pp.5-12
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• 1977

As a basic study for the application of the spore-tearing lactic acid bacteria to foods, the effects of the sporulating conditions on the growth and sporogenesis were studied were observed. The results obtained are as follow. 1. All carbohydrates added to sporulation media except dextrin decreased the sporulation rate and the thermal resistance of spores. Dextrin stimulated the growth, however, there in no effect on the thermal resistance. 2. As nitrogen source, the protein hydrolysates such as peptone, casamino acid were effective to obtain were spores of the increased thermal resistance. 3. Ca$\^$＋＋/, Mn$\^$＋＋/ of the metal ions added to casamino acid containing medium validly increased the total growth, sporulation rate and thermal resistance. Its optimum concentration was 40 ppm each. 4. Biotin of vitamines had an effect on the total growth, sporulation and thermal resistance of spores. Its optimum concentration was 30${\gamma}$/ml. 5. The resistant spores required the adequate maturation period, more than 36 hours, sufficient aeration. and optimum temperature, 37∼45$^{\circ}C$.

• Journal of Plant Biology
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• 제5권1호
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• pp.1-6
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• 1962

1) Germination rate was rather irregular than decreasing as increasing dose of radiation and there were no differences between Kyong-Sam and Chuong-Bang of Chinese cabbage. 2) In R1 generation, abnormal leaves from seedling of irradiated seeds were observed. These were more apparent in X-ray irradiation than in thermal neutron. 3) Seedling height was inhibited with increasing dose of X-ray and thermal neutrons. Growth inhibition was more remarkable in X-ray than in thermal neutron. Kyong-Sam demonstrated more sensitivity than Chyong-Bang in both X-ray and thermal neutron. 4) Seedling height produced from seeds subjected to thermal neutrons showed small variation around its mean value, while in X-irradiation there was a greater deviaton from the mean value. 5) Fertility was decreased as increasing with dose, while the frequency of abortive pollen was increased. There were variability of the fertility and frequency of abortive pollen among plants or branches of a plant. 6) The mutants were obtained more in thermal neutron irradiation than in X-ray. The types of mutations obtained in Chinese radish of R2 generation were abnormal leaf, densely glowing leaf, degeneration in growing point and dwarf. The maximum frequency of phenotypic mutations was abnormal leaf mutation.

• 한국세라믹학회지
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• 제35권10호
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• pp.1061-1069
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• 1998

The thermal instability of Al2TiO5 Ceramics was contrlled by solid solution with MgO SiO2 and ZrO2 through electrofusion in an arc furnace. The thermal expansion properties of Al2TiO5 composites show the hysteresis due to the strong anisotropy of The crystal axes of these material. These phenomena are ex-plained by the opening and closing of microcracks. The difference in microcracking temperatures e.g 587.6(ATG2), 405.9(ATG3) and 519.7$^{\circ}C$(ATG4) is caused by the difference in grain size and stabilizer type. The thermal shock behaviour under cyclic conditions between 750-1400-75$0^{\circ}C$ show no change in mi-crostructure and phase assemblage for all three stabilized specimens. After the thermal loading test at 110$0^{\circ}C$ for 100hrs. ATG1 and ATG2 materials decomposes completely to its components corundum and ru-tile in both cases. However with approximatelly 20% retention of the Al2TiO5 Thus in order to prevent decomposition of the stabilized material in the critical temperature range 800-130$0^{\circ}C$ it must be traversed within a short period of time.

• 한국안전학회지
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• 제11권1호
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• pp.53-59
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• 1996

To protect the damages or the disasters caused by overheating of industrial electric equipments or electric home appliances, a temperature sensitive thermal fuse is generally used in those equipments. Thermal fuses cutoff the current flow when the temperature of the electric equipments are abnormally overheated and over the certain temperature. Therefore thermal fuse is one of the most important elements in the sense of safety. Thermal fuses are classified into two types according to thermally sensitive materials, a low temperature melting alloy and an organic chemical compound. Domestic products of thermal fuses are now only with an organic chemical compound. Domestic products tested by using cutoff test and aging test etc. are satisfied UL specification. It's shown that the accuracy and the precision of the domestic products are as good as those of the overseas products obtained UL mark. However, some of domestic products show the reclosing problem which is mainly related the safety. This problem should be solved to make the reliable thermal fuses. In this paper, our Interest is to find out the causes of reclosing. In the comparison between thermally sensitive materials occurred reclosing and those occurred no reclosing, the test effects show that the characteristics of emitting heat and absorbing heat are different.

• The Journal of Advanced Prosthodontics
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• 제16권1호
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• pp.48-56
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• 2024

PURPOSE. To evaluate the metameric disparities among monolithic zirconia materials with differing yttrium compositions across various lighting conditions. MATERIALS AND METHODS. Thirty-six square-shaped zirconia samples measuring 10 × 10 × 0.5 mm were prepared from monolithic zirconia materials with three different yttrium contents. A 0.2 mm thick layer of polymerized dual-polymerizable self-adhesive resin cement was created using a silicone mold with the same dimensions as the prepared zirconia specimens. To evaluate metamerism, color measurements were conducted using a spectrophotometer device on a neutral gray background in a color measurement cabinet that offers four different illumination environments. All samples underwent aging by subjecting them to 10000 thermal cycles using a thermal cycle tester. Following thermal aging, color measurements were taken once more, and the data were recorded using the CIE L^*, a^*, b^* color system. Two-way ANOVA and Post-hoc Bonferroni tests were employed to analyze the data. RESULTS. It was observed that there was no statistical difference among the color measurements made in different illumination environments of the monolithic zirconia ceramics used to evaluate metamerism (P > .05). This observation remained consistent both before and after thermal aging. After thermal aging, the color of monolithic zirconia materials exhibited a tendency towards red and yellow hues, accompanied by a decrease in brightness levels. CONCLUSION. It can be stated that different illumination conditions did not affect the metamerism of monolithic zirconia materials, but there was a color change in monolithic zirconia materials after a thermal aging period equivalent to one year.

• 한국분무공학회지
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• 제20권2호
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• pp.65-69
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• 2015

In this study, the thermal performance of vehicle's cooling system is experimentally investigated using the water/coolant-based $Al_2O_3$ nanofluids as working fluids. For the purpose, the water/coolant-based $Al_2O_3$ nanofluids are prepared by twostep method with gum arabic. In order to obtain the well-suspended nanofluids, the agglomerated $Al_2O_3$ nanoparticles are precipitated using centrifugal force and the experiments are performed with supernatant of them. The thermal conductivity is measured by transient hot wire method and the thermal conductivity of nanofluids is enhanced up to 4.8% as compared to that of base fluids. Moreover, the cooling performance of water/coolant-based $Al_2O_3$ nanofluids is evaluated using vehicle's engine simulator under the constant RPM condition. The results show that the cooling performance of automobile engine increases up to 5.9% using prepared nanofluids. To investigate the effect of nanofluids on exhaust gas, the $NO_x$ emission is measured during the operation with respect to time and 10.3% of $NO_x$ emission is decreased. The experimental results imply that the water/coolant-based $Al_2O_3$ nanofluids might be used as a next-generation vehicles' coolant