• Analytical Science and Technology
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• v.21 no.2
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• pp.148-157
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• 2008

To describe the lifetime prediction of gas turbine core parts serviced in some ten thousands rpms at over $1,000^{\circ}C$, the Larson-Miller Creep Curves, which are formed by creep rupture tests as the destructive experiment with parameters of stress and temperature, are used often, but not exact and reliable with errors of over some tens. On the other hand, this study shows a non-destructive method with increased accuracy and reliability. The SEM and TEM specimens were extracted by replica after polishing the local airfoil and root surfaces of the first stage scraped blade (bucket), serviced for 18,000 hours at $1,280^{\circ}C$ in Gas Turbines of Boryong. The observed TEM and SEM precipitates were digitalized for calculation of the average size. Here we could find the precipitate size grown from $0.45{\mu}m$ to $0.6{\mu}m$ during service and the grown precipitates to be still sound. From these results we could conclude that the scraped balde can be used for ten thous and hours additionally and for twenty thousand hours by additional heat treatments on the scraped blade.

• Journal of Sensor Science and Technology
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• v.11 no.5
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• pp.309-318
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• 2002

A stoichiometric mixture of evaporating materials for $CdIn_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CdIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CdIn_2S_4$ single crystal thin films measured with Hall effect by van der Pauw method are $9.01{\times}10^{16}\;cm^{-3}$ and $219\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CdIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=2.7116\;eV-(7.74{\times}10^{-4}\;eV)T^2/(T+434)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CdIn_2S_4$ have been estimated to be 0.1291 eV and 0.0248 eV, respectively, by means of the photocurrent spectra and the Hopfield quasi cubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}5$ states of the valence band of the $AgInS_2$/GaAs epilayer. The three photocurrent peaks observed at 10K areascribed to the $A_1$-, $B_1$-, and C1-exciton peaks for n = 1.

• Economic and Environmental Geology
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• v.45 no.4
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• pp.385-396
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• 2012

The geochemical high-grade uranium anormal zone has been reported in the Shinbo mine and its eastern areas, Jinan-gun, Jeollabuk-do located in the southwestern part of Ogcheon metamorphic zone, Korea. In this paper is reported the time-relationship between deformation and growth of metamorphic minerals in the eastern area of Shinbo mine, which consists of the Precambrian metasedimentary rocks (quartzite, metapelite, metapsammite) and the age-unknown pegmatite and Cretaceous porphyry which intrude them, and is considered the relative mineralization time on the basis of the previous research's result. The D1 deformation formed the straight-type Si internal foliation which is defined mainly as the arrangement of elongate quartz, biotite, opaque mineral in andalusite porphyroblast. The D2 deformation, which is defined by the microfolding of Si foliation, formed S2 crenulation cleavage. It can be divided into two sub-phases, early crenulation and late crenulation. The former occurs as the curvetype Si foliation in the mantle part of andalusite. The latter occurs as S1-2 composite foliation which warps around the andalusite. The andalusite porphyroblast began to grow under non-deformation condition after the formation of S1 foliation which corresponds to the straight-type Si foliation. It continued to grow before the late crenulation phase. The age-unknown pegmatite intruded after the D2 deformation and grew the fibrous sillimanite which random masks the S1-2 composite foliation. The D3 deformation formed F3 fold which folded the S1-2 composite foliation, D2 crenulation, fibrous sillimanite. It means that the intrusion of pegmatite related to the growth of the fibrous sillimanite took place during the inter-tectonic phase of D2 and D3 deformations. The retrograde metamorphism is recognized by the chloritization of biotite and two-way cleavage lamellae which is parallel to the S1-2 composite foliation and the F3 fold axial surface in the andalusite porphyroblast. It occurred during the D2 late crenulation phase and D3 deformation. In considering of the previous research's result inferring the most likely candidate for the uranium source rock as pegamatite, it indicates that the age-unknown pegmatite intruded during the inter-tectonic phase of D2 and D3 deformations, i.e. during the retrograde metamorphism related to the uplifting of crust, and formed the uranium ore zone around the Shinbo mine.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.122-126
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• 2003

In this study, $Zn_{0.86}Mn_{0.14}$Te epilayer of 0.7 $\mu\textrm{m}$-thickness was grown on GaAs(100) substrate by using hot wallepitaxy. GaAs(100) substrate was removed from $Zn_{0.86}Mn_{0.14}$Teepilayer by the selective etching solution. The crystal structure and the lattice constant of only Z $n_{0.86}$ M $n_{0.14}$Te epilayer were investigated to be zincblende and 6.140 $\AA$ from X-ray diffraction pattern, respectively. Mn composition x of $Zn_{1-x}Mn_x$Te epilayer was found to be 0.14 using this lattice constant and Vegard's law. The crystal quality of the epilayer was confirmed to be very good due to 256 arcsec-full-width at half-maximum of the double crystal rocking curve. The absorption spectra from the transmission ones were obtained to measure the band gap energy of $Zn_{0.86}Mn_{0.14}$Te epilayer from 300 K to 10 K. With the decreasing temperature,. strong absorption regions in the absorption spectra were shifted to higher energy side and the absorption peak meaning the free exciton formation appeared near the absorption edge. The band gap energy values of $Zn_{0.86}Mn_{0.14}$Te epilayer at 0 K and 300 K were found to be almost 2.4947 eV and 2.330 eV from the temperature dependence of the free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer, respectively. The free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer without GaAs substrate was larger 15.4 meV than photoluminescence peak position energy at 10 K. This energy difference between two peaks was analysed to be Stokes shift.

• Korean Journal of Food Science and Technology
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• v.49 no.3
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• pp.274-278
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• 2017

In this study, predictive mathematical models were developed to estimate the kinetics of Staphylococcus aureus growth in processed meat product galbitang. Processed meat product galbitang was inoculated with 0.1 mL of S. aureus culture and stored at 4, 10, 20, $37^{\circ}C$. The ${\mu}_{max}$ (maximum specific growth rate) and LPD (lag phase duration) values were calculated. The primary model was used to develop a response surface secondary model. The growth parameters were analyzed using the square root model as a function of storage temperature. The developed model was confirmed by calculating RMSE (Root Mean Square Error) values as statistic parameters. The LPD decreased, but ${\mu}_{max}$ increased with an increase in the storage temperature. At 4, 10, 20 and $37^{\circ}C$, $R^2$ was 0.99, 0.98, 0.99 and 0.99, respectively; RMSE was 0.39. The developed predictive growth model can be used to predict the risk of S. aureus contamination in processed meat product galbitang; hence, it has potential as an input model for the risk assessment.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.342-348
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• 2016

The objective of this study was to compare the change of S. Enteritidis with S. Typhimurium populations in liquid egg products. S. Enteritidis or S. Typhimurium was inoculated into egg white and egg yolk and stored at 8, 10, 15, 25, and $35^{\circ}C$, respectively. In egg white, no growth of S. Enteritidis and S. Typhimurium was observed at 8, 10, 15, and $35^{\circ}C$, while both S. Enteritidis and S. Typhimurium in egg white stored grew more than 1 log CFU/ml after 50 hours storage at $25^{\circ}C$. In egg yolk, there was no growth of S. Enteritidis and S. Typhimurium at $8^{\circ}C$ but growth of both strains was observed at 10, 15, 25, and $35^{\circ}C$. Since growth of S. Enteritidis and S. Typhimurium was only observed in egg yolk, primary growth models for both strains were developed using modified Gompertz equation and then secondary models for lag time (LT), specific growth rate (SGR), and maximum population density (MPD) were developed as a function of temperature. At all temperatures, more rapid growth of S. Enteritidis than S. Typhimurium was observed in egg yolk, indicating the greater risk of S. Enteritidis than S. Typhimurium in egg products. In conclusion, the results indicate that temperature control less than $8^{\circ}C$ is very important to ensure safety of liquid egg products, especially liquid egg yolk.

• Journal of Mushroom
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• v.13 no.2
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• pp.114-118
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• 2015

Mycoleptodonoides aitchisonii has been used a culinary material and traditional medicine for a long time in worldwide and recently the researches to find biological effects have been increased such as dopamine activation, preventive effect against phytopathogens, inhibitive effect against erythrocyte coagulation, anti-oxidative effect, anti-tumorigenic effect, etc. However it is hard to cultivate Mycoleptodonoides aitchisonii it is impossible to be mass-produced and in order to solve the problem in this study we found the appropriate cultivation period and the harvest point for it. For life cycle (from primordium formation to harvest) the morphology, weight, and quantity of polysaccharide of Mycoleptodonoides aitchisonii were measured using with 5 bodies per a day and it could be divided for 4 stages; primordium formation, growth, needle maturation, and aging. And then from the results the Zeide nonlinear growth curve could be gotten. At 13th day after cultivation there is the relation between the change of media weight and body weight and at 14th day after cultivation the rate of polysaccharide in the body was 11 %. However in the case of O2 insufficient supply the malformation of them was observed.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.4
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• pp.549-563
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• 2008

The purpose of this research is to identify the urban structure in Korea. Though there is research regarding urbanization, there is little regarding the urban structure of the Korean economy. In this paper, two issues will be discussed: the measurements of inter-city and intra-city structure in Korean Metropolitan Statistical Areas (MSAs), which is newly defined. First, the city size rank rule, widely known as Zipf’s Law, will illustrate Korean the inter-city structure. The city size rank rule gives an idea whether Korean MSAs are balanced or not. In general, Korea has a heavy concentration in the Seoul MSA in terms of population. It could be either that the Seoul MSA is too big or that the Busan MSA is too small or both. If this is the primacy problem, a decentralization policy is necessary. On the other hand, if it is a second city problem, development policies for the Busan MSA and Daegu MSA are more important. Next, the Korean intra-city structure will be discussed. The evolutions of the MSAs explain intra-city structure by analyzing population density function and the housing price function. Some large MSAs such as Seoul and Busan have experienced urban sprawl, while other MSAs have experienced urban concentration. The population density gradient by the distance from the ARC GIS shows the growth rate of a city. According to the Spatial Mismatch Index between population and employment, the Ulsan MSA, Gwangju MSA, and Suwon-Hwaseong-Osan MSA are more mismatched, while the Daejeon MSA and Incheon MSA are less mismatched. Therefore, these analyses of Korean urban structure are meaningful in developing regional policy.

• Fire Science and Engineering
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• v.34 no.1
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• pp.11-17
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• 2020

As performance-based design (PBD) has a direct impact on evacuation safety assessments, designing fire scenarios based on real fire tests is essential. To improve the reliability of the PBD for fire safety in multiplexes, information on fire behavior, such as heat release rate (HRR) and fire spread rate, are provided in this study by conducting a standard fabric flammability test. To this end, several chairs were arranged in a pattern that resembled a theater-style seating. The peak HRR and heating value per unit mass for each chair ranged from 415 kW to 988 kW and 15.2 MJ/kg to 23.8 MJ/kg, respectively. The heating values per unit mass of the new and old chairs were 23.6 MJ/kg and 16.7 MJ/kg, respectively. As the quantity of plastic and cushioning materials in the new chairs was more than that of the old ones, the new chairs were more vulnerable to fire hazards. Furthermore, when the chairs were arranged in a line, the fire spread rate was observed to be 0.39-0.42 m/min, regardless of the ignition location. Finally, a fire growth curve showing the peak HRR and fire spread rate was also demonstrated.

• Journal of the Korean Magnetics Society
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• v.12 no.2
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• pp.41-45
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• 2002

The low-field tunnel-type magnetoresistance (MR) properties of sol-gel derived $La_{0.7}Pb_{0.3}MnO_3(LPMO)$ thin film deposited on different substrate have been investigated. Polycrystalline thin films were fabricated by spin-coating on $SiO_2/Si(100)$ substrate and that with yttria-stabilized zirconia (YSZ) buffer layer, while c-axis-oriented thim film was grown on $LaAlO_3(001)$ (LAO) single crystal substrate. The full width half maximum (FWHM) of the rocking curve scan of LPMO/LAO film is $0.32^{\circ}$. Tunnel-type MR ratio is 0.52 % in $LPMO/SiO_2/Si$(100) film and that of $LPMO/YSZ/SiO_2/Si$(100) film is as high as 0.68 %, whereas that of LPMO/LAO(001) film is less than 0.4 % under the applied field of 500 Oe at 300 K. Well-pronounced MR hysteresis was registered with an MR peak in the vicinity of the coercive field. The low-field tunnel-type MR characteristics of thin films deposited on different substrates originates from the behavior of grain boundary properties.