• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.9
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• pp.1284-1291
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• 2002

Combustion instabilities are an important concern associated with lean premixed combustion. Laboratory-scale dump combustor was used to understand the underlying mechanisms causing combustion instabilities. Experiments were conducted at atmospheric pressure and sound level meter was used to track the pressure fluctuations inside the combustor. Instability maps and phase-resolved OH chemiluminescence images were obtained at several conditions to investigate the mechanism of combustion instability and relations between pressure wave and heat release rate. It showed that combustion instability was susceptible to occur at higher value of equivalence ratio (>0.6) as the mean velocity was decreased. Instabilities exhibited a longitudinal mode with a dominant frequency of ∼341.8 Hz, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instabilities occurred. Rayleigh index distribution gave a hint about the location where the strong coherence of pressure and heat release existed. These results also give an insight to the control scheme of combustion instabilities. Emission test revealed that NOx emissions were affected by not only equivalence ratio but also combustion instability.

• Polymer(Korea)
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• v.34 no.3
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• pp.261-268
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• 2010

Phase change materials based on polypropylene blended with n-eicosane were studied in this paper. In addition, this paper reviews recent studies on the preparation of shape stabilized phase change materials (SSPCM), such as SSPCM from polypropylenes and n-eicosane, their basic properties and possible applications to latent heat storage. The preparation methods used were the melting method and absorption methods. Shape stabilized PCM(SSPCM) prepared for DSC, WAXD, FTIR spectroscopy, ARES, results of the analysis of shape stability heat capacity to improve were identified.

• Korean Journal of Health Education and Promotion
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• v.31 no.4
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• pp.51-62
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• 2014

Objectives: The objective of study was to calculate the municipal level environmental burden of disease (EBD) due to heat wave. Methods: The data used were Korea National Health Insurance 2011 claim data and 2011 death registry. Heatwave related diseases included hypertensive heart diseases, ischemic heart diseases, cerebrovascular disease, and heat related illness. According to the method that WHO proposed, the study computed population-attributable fraction with relative risk which come from previous study and proportion of exposure which the study calculated with historical meteorology data. Results: The Average of 251 municipal EBD was 2.11 per thousand persons. The value of years lost due to disability was 11 times higher than that of years of life lost. On average EBD of county and southern geographical areas tended to be higher than those of District or city areas. The relationship between municipal deprivation index (composite deprivation index) and EBD showed the positive association, which means that the worse deprived municipal is, the higher EBD takes. Conclusions: Climate change is getting one of the major risk factors of cardio-cerebrovascular disease, which is the second leading cause of death. The study results suggested the urgent policy planning and reaction of climate change adaptation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.543-552
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• 2003

The effects of a directionally emitting and reflecting dielectric surface on the wall heat flux and medium temperature distribution are studied. The system is an infinite square duct enclosing an absorbing and emitting medium. The emissivity and reflectivity of opaque and gray wall vary with direction. Combined effect of conductive and radiative heat transfer is analyzed using finite difference and the direct discrete-ordinates method. The parameters under study are conduction to radiation parameter, optical depth, refractive index ratio. The results with directional and diffuse properties deviate each other when the conduction to radiation parameter is less than around 0.01. The wall heat flux differs fur optical thickness less than around 0.1. However, the medium temperature profiles differ for optical thickness greater than around 1. Deviations from diffuse property calculations are larger for hot wall with directional property than cold wall with directional property. As n increases from 1.5, the trend changes are observed fur refractive index ratio about n=6.10

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.31-41
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• 1999

Blended Low Heat type cement is ground granulated blast furnace slag and fly ash mixed ternary with ordinary portland cement. From the viewpoint of X-ray patterns of domestic LHC, the main components of cement such as $C_2$S, $C_3$A, $C_3$S are considerably reduced. Therefore the heat evolution of LHC paste is 42cal/g lower than of OPC paste. At early age, the compressive strength development of LHC concrete is delayed, but the slump loss ratio of fresh concrete is reduced more than 20% with elapsed time. The penetrability of LHC is lower than that of OPC by 1/7.8 with the penetrability of chloride ion into the concrete until the age of 120 days. And the PD Index value of LHC is 0.44$\times$10-6 $\textrm{cm}^2$/s, which indicates only 39.3% of OPC. From the Mercury Intrusion Porosimetry test of cement past, we know that the pore size of LHC is more dense than that of OPC by production of C-S-H.

• International Journal of Industrial Entomology and Biomaterials
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• v.42 no.1
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• pp.7-13
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• 2021

In the present study, the effect of heat treatment on the crystallinity of the outside of silkworm cocoon in nine different silkworm varieties was studied using ATR-FTIR spectroscopy. Additionally, the morphological structure and moisture regain of the cocoon were examined. The silkworm cocoon showed different colors and external features depending on the silkworm variety. Moreover, the thickness of the filament (15.3-27.6 ㎛) and moisture regain of the cocoon (9.0%-11.0%) were quite different depending on the silkworm variety. The crystallinity index of the cocoon outside varied from 52.1% to 56.1%, depending on the silkworm variety. J300 and MO42 showed the highest (56.1%) and the lowest (52.1%) crystallinity index, respectively, indicating that the microstructure of sericin of the outside of the cocoon was affected by the silkworm variety. Regardless of silkworm variety, their crystallinity indexes decreased from 52.1%-56.1% to 49.9%-43.6% depending on the silkworm variety by the heat treatment at 250 ℃. Interestingly, the crystallinity degree decrease was somewhat different depending on the silkworm variety, implying that the cocoon sericin microstructure is strongly influenced by the silkworm variety.

• Journal of Environmental Science International
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• v.16 no.5
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• pp.593-602
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• 2007

The frequency of tropical nights and tropical days in Busan during summer season (June-August) from 1995 to 2004 were investigated. When air temperature higher than $25^{\circ}C$ continuously maintains at night in summer, it is called the occurrence of tropical night. Tropical day is defined that maximum air temperature is higher than $30^{\circ}C$, In Jin-Gu and Daeyeon-dong shows a lot of frequency of tropical day and tropical night because there were located in downtown. Relatively, the areas where are located in seaside and riverside show very low frequency. This can be explained the cooling effects of sea and river. The main meteorological characteristics during tropical nights and tropical days is proved pattern of reverse tendency through wind rose. We analyzed heat index and discomfort index during tropical night and tropical day. This study is useful to understand the aspect of urban thermal environment but need some more observation to quantify.

• Korean journal of food and cookery science
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• v.7 no.3
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• pp.1-6
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• 1991

Potato starches are obtained from Irish Cobbler (the dry type), Shepody and superior (the intermediate type) and Dejima (the moist type). Rheological properties of heat-gelatinized potato starch paste were studied to elucidate difference of various potato starches. Heat-gelatinized 3 to 7% potato starch paste showed pseudo plasticity in yield stress. As starch paste concentration increased, the values of consistency index was increased. Relationship between logarithmic consistency index and concentration of potato starch paste was linear at 5% starch concentration. Concentration dependence of consistency index and yield stress of Shepody was highest. As measuring temperature increased, the value of consistency index was decreased. Irish Cobbler starch paste at $50^{\circ}C$, Shepody, Superior and Dejima starch paste at $60^{\circ}C$ showed linear relationships with different slopes. The activation energies of Shepody starch paste was 3.97㎉l/㏖.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.55-57
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• 2012

In this study, the field applicability on reducing the heat of hydration of mass concrete by using the hydration heat difference method is analyzed with the following summary. As a result of applying the hydration heat difference method by using low heating combination, the temperature difference between the central part and the surface part of mass material was reduced, and as a result of visual observation, there was no showing of cracks by the hydration heat on the upper surface part. Therefore, the cracking index of the field to apply this method was shown to be approximately 1.57 with very little crack occurrence probability of less than 3%.

• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.111-116
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• 2009

The cracking due to hydration heat in mass concrete must be resolved to improve the stability and durability of concrete structures. In this study, the economic efficiency was improved by replacing a copper pipe with a steel one for the heat pipe, and the heat pipe was standardized to significantly improve the operation efficiency, such as the processing, transport, assembly, and construction time. As a result of the experiment, the peak temperature of the ICSHP, ISSHP, and ISUHP specimens decreased by about $7.2{\sim}10.9^{\circ}C$ compared to the OPC specimen and the probability of a thermal crack being generated in the ICSHP, ISSHP, and ISUHP specimens decreased by up to 84~88%.