• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.294-299
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• 2003

The efficiency of complex slurry preparation route for the development of high performance RS-SiCf/SiC composites has been investigated. The green bodies for RS-SiC and RS-SiCf/SiC composite materials prior to the infiltration of molten silicon were prepared with various C/SiC complex matrix slurries, which associated with both different sizes of starting SiC particles and blending ratios of starting SiC and carbon particles. The reinforcing materials in the composite system were uncoated and C coated Tyranno SA SiC fiber. The characterization of RS-SiC and RS-SiCf/SiC composite materials was examined by means of SEM, EDS and three point bending test. Based on the mechanical property-microstructure correlation, process optimization methodology is discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.689-695
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• 2002

Film compositions are needed in semiconductor manufacturing for such diverse application as production tool qualifications and process development. Surface and interface information is generally provided with Auger electron spectroscopy(AES). In this paper, WSix films were analyzed for structural, electrical, and compositional properties of tungsten silicide thin films produced by low pressure chemical vapor deposition as a function of temperature, DCS post flow, shower head life time, and the silicon to tungsten ratios have been investigated. We find that Si/W composition ratio is increased in the surface and interface of WSix thin films by the DCS post flow process and increasing deposition temperature, respectively. The results obtained in this study are also applicable to process control of WSix deposition for memory device fabrication.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1716-1724
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• 2018

Single crystal of organic lead halide ($CH_3NH_3PbX_3$; $CH_3NH^+_3$ = methylammonium (MA), $X=Cl^-$, $Br^-$, $I^-$) is the best candidate for material intrinsic property studies due to no grain boundary and high crystal quality than the film having a lot of grain boundary and surface defects. The representative crystallization methods are inverse temperature crystallization (ITC) and anti-solvent vapor assisted crystallization (AVC). Herein, we report bandgap modulated organic lead halide single crystals having a bandgap ranging from ~ 2.1 eV to ~ 3 eV with ITC and AVC methods. The bandgap modulation was achieved by controlling the solvents and chloride-to-bromide ratio. Structural, optical and compositional properties of prepared crystals were characterized. The results show that the crystals synthesized by the two crystallization methods have similar properties, but the halide ratios in the crystals synthesized by the AVC method are controlled more quantitatively than the crystals synthesized by ITC.

• Computers and Concrete
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• v.29 no.6
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• pp.433-444
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• 2022

Concrete's compressive strength is widely studied in order to understand many qualities and the grade of the concrete mixture. Conventional civil engineering tests involve time and resources consuming laboratory operations which results in the deterioration of concrete samples. Proposing efficient non-destructive models for the prediction of concrete compressive strength will certainly yield advancements in concrete studies. In this study, the efficiency of using radial basis function neural network (RBFNN) which is not common in this field, is studied for the concrete compressive strength prediction. Complementary studies with back propagation neural network (BPNN), which is commonly used in this field, have also been carried out in order to verify the efficiency of RBFNN for compressive strength prediction. A total of 13 input parameters, including novel ones such as cement's and fly ash's compositional information, have been employed in the prediction models with RBFNN and BPNN since all these parameters are known to influence concrete strength. Three different train: test ratios were tested with both models, while different hidden neurons, epochs, and spread values were introduced to determine the optimum parameters for yielding the best prediction results. Prediction results obtained by RBFNN are observed to yield satisfactory high correlation coefficients and satisfactory low mean square error values when compared to the results in the previous studies, indicating the efficiency of the proposed model.

• The Korean Journal of Food And Nutrition
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• v.27 no.4
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• pp.539-550
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• 2014

The purpose of this study was to determine the optimal mixing ratios of three different ingredients of Polygonum multiflorum Radix powder, butter, and sugar for the development of recipe for cookies with Polygonum multiflorum Radix powder. Response surface methodology based on a five level and three variables by central composite design was employed to obtain the best possible combination for the ratios of Polygonum multiflorum Radix powder ($X_1$), butter ($X_2$), and sugar ($X_3$). The analytical results of the physical and mechanical properties for each sample including color L (P<0.01), color a (P<0.01), color b (P<0.01), spread ratio (P<0.001), and hardness (P<0.001) showed significant differences. The sensory measurements were significantly different in color (P<0.05), appearance (P<0.05), texture (P<0.001), flavor (P<0.01), taste (P<0.01), and overall quality (P<0.001). The optimal compositional ratios were determined to be 4.00 g for the Polygonum multiflorum Radix powder, 75.42 g for the butter, and 45.67 g for the sugar.

• The Journal of the Petrological Society of Korea
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• v.5 no.1
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• pp.66-83
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• 1996

We report petrography, mineral chemistry, and major and trace element chemistry for rare tholeiites in Cheju island where alkalic rocks predominate. Available age data indicate that the tholeiitic magmatism was younger than 0.49Ma, possibly younger than 0.17 Ma. The tholeiites are generally fine-grained, porphyritic rock and show intergranular texture with lath-shaped plagioclase ($An_{61-46}$), orthopyroxene (bronzite) and olivine ($Fo_{78-67}$). Characteristically, two kinds of clinopyroxene (pigeonite and augite) occur only in groundmass. The tholeiites have normative quartz and show limited compositional variations ($SiO_2$=51.0-52.5 wt%; Mg＃=54-60). Major and transitional metal element variations of tholeiites are distinct from those of alkaline rocks in MgO diagram, suggestingthat the two rock types cannot be simply related to differentiation process from the same magma. The ratios among $K_2O$, Rb, Ba, Nb and La are similar for both tholeiites and alkali basalts, however the ratios between the elements (P, Y and Yb) having an affinity with garnet and the above elements are higher for tholeiites than for alkali basalts. These trace element ratios suggest that the tholeiites and alkali basalts were produced by different degrees of partial melting from a similar sources material (garnet lherzolite mantle).

• Economic and Environmental Geology
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• v.56 no.4
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• pp.475-499
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• 2023

To infer the provenance of raw iron materials utilized in iron production at the archaeological sites in Gyeongsang province, petrographic and geochemical analyses were conducted for smelting samples and major iron ores sourced from ore deposits. The smelting samples excavated from various iron archaeological sites were classified into different types according to their refining processes, such as iron bloom, iron bloom slag, pig iron, pig iron slag, forging iron flake, smithery iron, iron flake, and arrowhead. These samples exhibited discernable differences in their mineralogical components and texture. The enrichments of major elements such as aluminum and calcium in silicate minerals of the residual slags and the high contents of trace elements such as nickel and copper in some iron-making relics reflect the characteristics of raw iron ores, and thus can be regarded as potential indicators for inferring the provenance of source materials. In particular, the compositional ranges of Pb-Sr isotope ratios for the iron smelting samples were classified into three categories: 1) those exhibiting similar ratios to those of the raw iron ores, 2) those enriched in strontium isotope ratio, and 3) those enriched in both lead and strontium isotope ratios. The observed distinct Pb-Sr isotope characteristics in the iron smelting samples suggest the potential contribution of specific additives being introduced during the high-temperature refining process. These results provide a new perspective on the interpretation of the provenance study of the iron archaeological samples in Gyeongsang province, particularly in terms of the potential contribution of additives on the refining process.

• Journal of Ginseng Research
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• v.22 no.4
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• pp.274-283
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• 1998

It has generally been accepted that quality of ginseng should be determined not by the content of a single component but by composition and balance of total active principles. However, there still can be an exception with a product in which a given ginsenoside is used for the treatment of a specific disease. Although ginsenosides have been regarded to be major active components of ginseng and employed as index components for the quality control, it does not consistent with the traditional concept on ginseng quality creterion; main root has been more highly appreciated than the lateral or fine root. Content of ginsenosides in the lateral or fine root is much higher than that in main root. However, the ratio of protopanaxadiol (PD) and protopanaxatriol (PT) saponins existing in various part of ginseng root is greatly different. The ratio of PD/PT saponins in main root is well balanced but the thinner the root is the higher the ratio. Thus far, a total of 34 different kinds of ginsenosides have been isolated from Korean (red) ginseng, and their pharmacological activities were elucidated partly. Interestingly, different ginsenoside shows similar or contrary effects to each other in biological systems, thus indicating the significance of absolute content of single ginsenoside as well as compositional patterns of each ginsenoside. Therefore, pharmacological activities of ginseng should be determined as a wholly concept. In these regards, standardization of ginseng material (fresh ginseng root) should be preceded to the standardization of ginseng products because ginsenoside content and non-saponin active principles such as polysaccharides and nitrogen (N)-containing compound including proteins are significantly different from part to part of the root. In other words, the main root contains less ginsenosides than other lateral or fine roots. Contents of polysaccharides and N-containing compound in main root is higher. However, the quality control of ginseng products focused on non-saponin compounds has limitation in applying to the analytical method, because of the difficult chemical analysis of these compounds. Content of ginsenosides, and ratios of PD/PT and ginsenoside Rb,/Rg, are inversely proportional to the diameter of ginseng root. Therefore, these can be served as the chemical parameters for the indirect method of evaluating from what part of the root does the material originate. Furthermore, contents of polysaccharides and N-containing compounds show inverse relationship to saponin content. Therefore, it seems that index for analytical chemistry of saponin can be applied to the indirect method of evaluating not only saponin but also non-saponin compounds of ginseng. From these viewpoints, it is strongly recommended that quality of ginseng or ginseng products be judged not only by the absolute content of given ginsenoside but also by varieties and compositional balance of ginsenosides, including contents of non-saponin active principles.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.776-784
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• 1993

A pentasil zeolite, ZSM-5 was synthesized in the absence of organic template, $TPA^+$ ion at $210^{\circ}C$. It was realized that a conventional method can not be applied to the synthesis system where organic templates are not used. The results indicated that the compositional range for the crystallization of ZSM-5 is very narrow, requiring very careful controls in the $Na_2O/SiO_2$and $SiO_2/Al_2O_3$ratios. In addition, the results showed that the effects of mixing method, aging and reaction time on the crystallization of ZSM-5 were extraordinarily significant.

• Journal of the Korean Vacuum Society
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• v.10 no.3
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• pp.321-327
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• 2001

Ti-Si-N films obtained by using RF reactive sputtering of targets with various Ti/Si ratios in a $N_2(Ar+N_2)$ gas mixture have been investigated in terms of films resistivity and diffusion barrier performance. The chemical bonding state of Si in the Ti-Si-N film which contained a higher Si content was in the form of amorphous $Si_3N_4$, producing increased film resistivity with increased $N_2$flow rate. Lowering the Si content in the deposited Ti-Si-N film favored the formation of crystalline TiN even at low $N_2$flow rates, and leads to low film resistivity. In addition increasing the N content led to Ti-Si-N films having a higher density and compressive stress, suggesting that the N content in the films appear to be one of the most important factors affecting the diffusion barrier characteristics. Consequently, we proposed the optimum composition in the range of 29~49 at.% of Ti, 6~20 at.% of Si, and 45~55 at.% of N for the Ti-Si-N films having both low resistivity and excellent diffusion barrier performance.