• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.239-246
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• 1999

A highly sensitive photovoltaic infrared photodiode was fabricated for detecting infrared light in $3{\sim}5\;{\mu}m$ wavelength range on InSb wafer with p-i-n structure grown by MOCVD. Silicon dioxide($SiO_2$) insulating films for the junction interface and surface of photodiode were prepared using RPCVD because InSb has low melting point and evaporation temperature. After formation of In ohmic contacts by thermal evaporation, the electrical properties of the photodiode were characterized in dark state at 77K. A product of zero-bias resistance and area($R_0A$) showed $1.56{\times}10^6\;{\Omega}{\cdot}cm^2$ that satisfied BLIP(background limited infrared photodetector) condition. When the photodiode was tested under infrared light, the normalized detectivity of about $10^{11}\;cm{\cdot}Hz^{1/2}{\cdot}W^{-1}$ was obtained. we successfully fabricated a unit cell with InSb IR array with good quantum efficiency and high detectivity.

• Resources Recycling
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• v.18 no.1
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• pp.22-29
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• 2009

To design and construct a moving bed stoker incinerator for incineration treatment of the domestic oil fly ash, operating condition and moving bed area of incinerator were determined by performing incinerate experiment of the oil fly ash in the muffle furnace which simulates moving bed stoker incinerator in all conditions. Incineration process of the oil fly ash could be divided into 3 stages, every stage needs the appropriate operating condition for effective incineration. The optimum content of water in the heavy oil fly ash was found to be 20 wt% to prevent the ash from flying and reduce the volume. Science combustion rate of oil fly ash depends on the oxygen content, the incinerator must have a equipment to control the oxygen content in the combustion air. The optimum temperature was $750{\sim}800^{\circ}C$ in order to prevent adhesion to the stocker and evaporation of metal compounds of low melting point. Uniform combustion reaction and acceleration of combustion rate required agitation during the combustion of oil fly ash. The incineration rate was $12.53kg/m^2hr$ and the working area of moving bed incinerator was found to be $60m^2$ to incinerate 18 tons of oil fly ash per day.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.363-364
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• 2005

LTCC(low temperature co-fired ceramics)용 glass/ceramic 복합체를 제조하기 위해 3종류 의 glass를 선정하고 filler로 $Al_2O_3$ 와 $TiO_2$를 사용하여 glass frit에 따른 소결 및 유전 특성에 대하여 조사하였다. Glass frit은 lead-borosilicate(PBS), zinc-borosilicate(ZBS), bismuth-borosilicate(BBS) glass 조성을 사용하였고 1100~$1400^{\circ}C$에서 melting시킨 후 quenching하여 frit화하였다. $Al_2O_3$와 $TiO_2$ filler에 10~50 vol%로 glass frit을 각각 혼합한 후 600~$950^{\circ}C$에서 2시간 동안 소결한 결과 50 vol% glass frit 일 때 $900^{\circ}C$ 이하에서 소성이 가능하였다. 유전특성은 $900^{\circ}C$에서 $Al_2O_3$-50vol%PBS($\varepsilon_{r}$=8.8, $Q{\times}f_o$=4,900, $\tau_f$=-24), $Al_2O_3$-50vol% ZBS($\varepsilon_{r}$=5.7, $Q{\times}f_o$=17,800, $\tau_f$=-21), $Al_2O_3$-50vol%BBS($\varepsilon_{r}$=11.1, $Q{\times}f_o$= 2,080, $\tau_f$=-48), $TiO_2$-50vol%PBS($\varepsilon_{r}$=18.6, $Q{\times}f_o$=3,800, $\tau_f$=+135), $TiO_2$-50vol%ZBS($\varepsilon_{r}$=36.4, $Q{\times}f_o$= 7,500, $\tau_f$=+159), $TiO_2$-50vol%BBS($\varepsilon_{r}$=56.4, $Q{\times}f_o$=520, $\tau_f$=+119)을 나타내었다. 따라서 LTCC용 기판재료 및 마이크로파 유전체로 응용이 가능한 것으로 확인되었다.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.90-95
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• 2014

Nylon66 extrudates as a function of the extrusion number were prepared by a twin screw extruder. Chemical structures, thermal properties, melt index, crystal structures, mechanical properties such as the tensile strength, elongation at break and impact strength, and rheological property were measured by FT-IR, $^1H$-NMR, melt indexer, DSC, TGA, XRD, universal tensile tester, Izod impact tester, and rheometer. FT-IR and $^1H$-NMR characterizations indicated that the number of extrusions did not affect the chemical structure. The decrease in the molecular weight was checked by the melt index of extrudates. There were no effects of the thermal history on the melting and degradation temperature. The tensile and impact strength and modulus were found to be similar, regardless of the number of extrusions, but the elongation decreased significantly. The complex viscosity of extrudates at low frequencies decreased with the extrusion number. No structural changes after extrusion were confirmed from the fact that there was no change in the slope and shape of G'-G" plot.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.688-696
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• 2020

Petroleum coke (petcoke) is widely used, next to coal, as a gasification feedstock. In gasification processes, the viscosity of the ash and the formation of crystalline phases must be understood to ensure the continuous removal of slag. This study investigates the effect of CaO and V2O3 on petcoke slag viscosity. The viscosity of the molten slag was measured in the temperature range of 1100~1600 ℃ while varying the concentration of each component. The crystalline phases formed in a cooled slag were examined. The most slag samples tested in this study exhibited crystalline slag behavior. The increased CaO concentration resulted in a lower viscosity and a lower Tcv. The viscosity behavior changed from the glassy to crystalline slag and also showed a higher Tcv as the concentration of V2O3 increases. Most slag samples showed different crystalline phases from top to bottom. Anorthites and Ca-V phases were observed in the top and middle section, while the bottom section mainly showed V2O3 and anorthite. The vanadium in the ash forms Ca-V and V-Fe phases and also remains in molten slag. A low melting Ca-V phase can contribute to lowering the viscosity.

• The Journal of the Petrological Society of Korea
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• v.12 no.3
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• pp.119-134
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• 2003

Yuksipryeong two-mica granite presents strongly peraluminous characteristics in both mineralogy and geochemistry. It has high aluminum saturation index with 1.15∼l.20 and high corundum with 2.20∼2.98 wt% CIPW norm. As the color index is <16% and FeO$\^$T/+ MgO + TiO$_2$is average 1.9 wt％, it corresponds to leucogranite. Yuksipryeong two-mica leucogranite shows negative linear trend for TiO$_2$, Al$_2$O$_3$, FeO, Fe$_2$O$_3$, MgO, CaO, K$_2$O, P$_2$O$\_$5/, Rb, Ba, and Sr as SiO$_2$increases, and the positive relation of Zr and Th, which result from feldspar, biotite, apatite and zircon fractionation. Pegmatitic dike has higher SiO$_2$and P$_2$O$\_$5/, but lower another major elements. Yuksipryeong two-mica leucogranite has lower Rb, but higher Ba and Sr than Manaslu, Hercynian two-mica leucogranites, and S-type granites in Lachlan Fold Belt. Pegmatitic dike has higher Rb and Nb but lower Ba, Sr, Zr, Th, and Pb contents than Yuksipryeong two-mica leucogranite, resulting in removing or mobilizing for some trace elements from the granitic melt. Yuksipryeong two-mica leucogranite has total REEs with 95.7∼l23.3 ppm, and chondrite-normalized REE pattern is very steep ((La/Yb)$\_$N/ = 6.9∼24.8), light REEs (LREEs)-enriched End heavy REEs (HREEs)- depleted pattern with low to moderate Eu anomalies (Eu/Eu＊= 0.7∼0.9). While pegmatitic dike has low total REEs with 7.0 ppm, and chondrite-normalized REE pattern is flat-pattern ((La/Yb)$\_$N/ = 2.1) with strong negative Eu anomalies (Eu/Eu＊= 0.2). The melt compositions having formed two-mica leucogranites depend on not only the source rock but also the amounts of the residual remaining after melting of source rocks. The CaO/Na$_2$O and Rb/Sr-Rb/Ba ratios depend mainly on the composition of source rocks in the strongly peraluminous granite, that is, plagioclase/clay ratio of the source rocks. Yuksipryeong two-mica leucogranite has higher CaO/Na$_2$O and lower Rb/Sr-Rb/Ba ratios than Manaslu and Hercynian two-mica leucogranites (Millevaches and Gueret) derived from clay-rich, plagioclase-poor (polite), which suggest that the probable source rocks for Yuksipryeong two-mica leucogranite is clay-poor, plagioclase-rich quartzofeldspathic rocks. As the concentrations of Al$_2$O$_3$remain nearly constant but those of TiO$_2$increases as increasing temperature in the strong peraluminous melt, the Al$_2$O$_3$/TiO$_2$ratio may reflect relative temperature at which the melts have formed. Comparing the polite-derived Manaslu and Hercynian two- mica leucogranites, Manaslu two-mica leucogranite has higher Al$_2$O$_3$/TiO$_2$ratio than latter, and its melt have formed at relatively lower temperature ($\leq$ 875$^{\circ}C$) than Hercynian two-mica leucogranites. Likewise, comparing the quartzofeldspathic rock-derived granites, Yuksipryeong two-mica granite has higher Al$_2$O$_3$/TiO$_2$, ratio than S-type granites in Lachlan Fold Belt (>875$^{\circ}C$). The melt formed Yuksipryeong two-mica leucogranite are considered to have been formed at temperature at below the maximum 875$^{\circ}C$C$.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.405-411
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• 2005

Chitosan, second largest biomass after cellulose on earth, has potential for use as functional food package due to its antibacterial activity. However, due to high melting temperature of chitosan, chitosan films have been made by casting method. Because gelatin has relatively low molting temperature depending upon amount of plasticizer added, it was added to chitosan to produce commercially feasible film. The objective of the current study was to determine optimum blend ratio and amount of chitosan/gelatin blend solutions against antibacterial activities for extruder resin. Gram-positive bacteria (Bacillus cereus ATCC 14579 and Listeria monocytogenes ATCC 15313) and -negative bacteria (Escherichia coli ATCC 25922 and Salmonella enteritidis IFO 3313) were used. Paper (8 mm) diffusion and optical density methods were used to evaluate effect of different blending ratio solutions on the inhibition of bacterial growth. Measured clear none size ranged from 8 mm to 18.07 mm in paper diffusion test. For B. cereus, E. coli, and S. enteritidis, addition of $50\;{\mu}L$ blend solution (chitosan/gelatin = 2/8: 0.3 mg) resulted in clear zone on paper disc. In L. monocytogenes, inhibition effect was observed with 0.6 mg chitosan (chitosan/gelatin=4/6). Minimum inhibitory concentration (MIC) values of B. cerues, L. monocytogenes, E. coli, and S. enteritidis with addition of chitosan were 0.1461, 0.2419, 0.0980, and 0.0490 mg/mL, respectively, These results indicate possibility of producing commercially feasible film with addition of optimum chitosan/gelatin amount.

• Korean Journal of Remote Sensing
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• v.34 no.2_1
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• pp.237-248
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• 2018

The vertical distribution of hydrometeor before precipitation near the cloud base has been analyzed using a scanning lidar, rawinsonde data, and Cloud-Resolving Storm Simulator (CReSS). This study mostly focuses on 13 Desember 2016 only. The typical synoptic pattern of lake-effect snowstorm induced easterly in the Yeongdong region. Clouds generated due to high temperature difference between 850 hPa and sea surface (SST) penentrated in the Yeongdong region along with northerly and northeasterly, which eventually resulted precipitation. The cloud base height before the precipitation changed from 750 m to 1,280 m, which was in agreement with that from ceilometer at Sokcho. However, ceilometer tended to detect the cloud base 50 m ~ 100 m below strong signal of lidar backscattering coefficient. As a result, the depolarization ratio increased vertically while the backscattering coefficient decreased about 1,010 m~1,200 m above the ground. Lidar signal might be interpreted to be attenuated with the penetration depth of the cloud layer with of nonspherical hydrometeor (snow, ice cloud). An increase in backscattering signal and a decrease in depolarization ratio occured in the layer of 800 to 1,010 m, probably being associated with an increase in non-spherical particles. There seemed to be a shallow liquid layer with a low depolarization ratio (<0.1) in the layer of 850~900 m. As the altitude increases in the 680 m~850 m, the backscattering coefficient and depolarization ratio increase at the same time. In this range of height, the maximum value (0.6) is displayed. Such a result can be inferred that the nonspherical hydrometeor are distributed by a low density. At this time, the depolarization ratio and the backscattering coefficient did not increase under observed melting layer of 680 m. The lidar has a disadvantage that it is difficult for its beam to penetrate deep into clouds due to attenuation problem. However it is promising to distinguish hydrometeor morphology by utilizing the depolarization ratio and the backscattering coefficient, since its vertical high resolution (2.5 m) enable us to analyze detailed cloud microphysics. It would contribute to understanding cloud microphysics of cold clouds and snowfall when remote sensings including lidar, radar, and in-situ measurements could be timely utilized altogether.

• The Journal of the Petrological Society of Korea
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• v.28 no.3
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• pp.157-169
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• 2019

Pseudotachylytes, produced by frictional heating during seismic slip, provide information that is critical to understanding the physics of earthquakes. We report the results of occurrence, structural characteristics, scanning electron microscopic observation and geochemical analysis of pseudotachylytes, which is presumed to have formed after the Late Cretaceous in outcrops of the Paleoproterozoic granitic gneiss on the Bulil waterfall of the Jirisan area, Yeongnam massif, Korea. Fault rocks, which are the products of brittle deformation under the same shear stress regime in the study area, are classified as pseudotachylyte and foliated cataclasite. The occurrences of pseudotachylyte identified on the basis of thickness and morphology are fault vein-type and injection vein-type pseudotachylyte. A number of fault vein-type pseudotachylytes occur as thin (as thick as 2 cm) layers generated on the fault plane, and are cutting general foliation and sheared foliation developed in granitic gneiss. Smaller injection vein-type pseudotachylytes are found along the fault vein-type pseudotachylytes, and appear in a variety of shapes based on field occurrence and vein geometry. At a first glance fault vein-type seudotachylyte looks like a mafic vein, but it has a chemical composition almost identical to the wall rock of granitic gneiss. Also, it has many subrounded clasts which consist predominantly of quartz, feldspar, biotite and secondary minerals including clay minerals, calcite and glassy materials. Embayed clasts, phenocryst with reaction rim, oxide droplets, amygdules, and flow structures are also observed. All of these evidences indicate the pseudotachylyte formed due to frictional melting of the wall rock minerals during fault slip related to strong seismic faulting events in the shallow depth of low temperature-low pressure. Further studies will be conducted to determine the age and mechanical aspect of the pseudotachylyte formation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.5
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• pp.208-214
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• 2019

The glass of $BaO-GeO_2-La_2O_3-ZnO$ system with a transmittance of more than 75 % at mid-wave infrared (MWIR) region in the range of $3{\mu}m$ to $5{\mu}m$ is manufactured and its property is evaluated. After selecting construction that can melt glass through flow button test, $BaO-GeO_2-La_2O_3$ system where 10 mol%, 20 mol% of ZnO were added respectively were melted at $1350^{\circ}C$ for 1 hour and $BaO-GeO_2-La_2O_3$ system of glass was manufactured. Among them, with 20 mol% of ZnO, 16 mol% BaO-56 mol% $GeO_2-8mol%$ $La_2O_3-16mol%$ ZnO system of glass was found to has less than $660^{\circ}C$ of glass transition temperature, more than 1.70 of refractive index, and more than 530 of knoop hardness. Therefore, it is concluded that glass of $BaO-GeO_2-La_2O_3-ZnO$ system of glass with 20 mol% ZnO has good melting conditions at low temperatures and excellent optical properties, thus, can be utilized for special optical materials field.