• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.63-71
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• 2004

Recently, a sheet forming process of Mg alloys is highlighted again due to increasing demand for Mg wrought alloys in the applications of casings of mobile electronics and outer-skins of light-weight transportation. Microstructure control is essential for the enhancement of workability and formability of Mg alloy sheets. In this research, AZ31 Mg alloy sheets were prepared by hot rolling process and the rolling condition dependency of the microstructure and texture evolution was studied by employing a conventional rolling mill as well as an asymmetric rolling mill. When rolled through multiple passes with a small reduction per pass, fine-grained and homogeneous microstructure evolved by repetitive dynamic and static recrystallization. With higher rolling temperature, dynamic recrystallization was initiated in lower reduction. However with increasing reduction per pass, deformation was locallized in band-like regions, which provided favorable nucleation sites f3r dynamic recrystallization. Through post annealing process, the microstructures could be transformed to more equiaxed and homogeneous grain structures. Textures of the rolled sheets were characterized by $\{0002\}$ basal plane textures and retained even after post annealing. On the other hand, asymmetrically rolled and subsequently annealed sheets exhibited unique annealing texture, where $\{0002\}$ orientation was rotated to some extent to the rolling direction and its intensity was reduced.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.665-670
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• 2016

Prevailing dissemination of machine tools and cutting technology have caused drastic developments of high speed dry machining with work materials of high hardness, and demands on the high-hardness-materials with high efficiency have become increasingly important in terms of productivity, cost reduction, as well as environment-friendly issue. Addition of Si to TiAlN has been known to form nano-composite coating with higher hardness of over 30 GPa and oxidation temperature over $1,000^{\circ}C$. However, it is not easy to add Si to TiAlN by using conventional PVD technologies. Therefore, Ti-Al-Si-N have been prepared by hybrid process of PVD with multiple target sources or PVD combined with PECVD of Si source gas. In this study, a single composite target of Ti-Al-Si was prepared by powder metallurgy of MA (mechanical alloying) and SPS (spark plasma sintering). Properties of he resulting alloying targets were examined. They revealed a microstructure with micro-sized grain of about $1{\sim}5{\mu}m$, and all the elements were distributed homogeneously in the alloying target. Hardness of the Ti-Al-Si-N target was about 1,127 Hv. Thin films of Ti-Al-Si-N were prepared by unbalanced magnetron sputtering method by using the home-made Ti-Al-Si alloying target. Composition of the resulting thin film of Ti-Al-Si-N was almost the same with that of the target. The thin film of Ti-Al-Si-N showed a hardness of 35 GPa and friction coefficient of 0.66.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.4
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• pp.357-364
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• 2010

Kjeldahl method used in many materials from various plant parts to determine protein contents, is laborious and time-consuming and utilizes hazardous chemicals. Near-infrared (NIR) reflectance spectroscopy, a rapid and environmentally benign technique, was investigated as a potential method for the prediction of protein content. Near-infrared reflectance spectra(1100-2400 nm) of coarse cereal grains(n=100 for each germplasm) were obtained using a dispersive spectrometer as both of grain itself and flour ground, and total protein contents determined according to Kjeldahl method. Using multivariate analysis, a modified partial least-squares model was developed for prediction of protein contents. The model had a multiple coefficient of determination of 0.99, 0.99, 0.99, 0.96 and 0.99 for foxtail millet, sorghum, millet, adzuki bean and mung bean germplasm, respectively. The model was tested with independent validation samples (n=10 for each germplasm). All samples were predicted with the coefficient of determination of 0.99, 0.99, 0.99, 0.91 and 0.99 for foxtail millet, sorghum, millet, adzuki bean and mung bean germplasm, respectively. The results indicate that NIR reflectance spectroscopy is an accurate and efficient tool for determining protein content of diverse coarse cereal germplasm for nutrition labeling of nutritional value. On the other hands appropriate condition of cereal material to predict protein using NIR was flour condition of grains.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.184-189
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• 2008

To assess the relationship between Cd fraction in paddy soils and Cd in polished rice, soils and rice were analyzed at the 3 Cd contaminated paddy fields near closed mines. Major Cd fractions of A field were organically bound (62.6%) and Fe-Mn oxide bound (25.3%) forms. In case of B field, major Cd fractions of B1 field were carbonate bound (46.3%) and Fe-Mn oxide bound (31.6%) form whereas B2 field were residual (54.3%) and carbonate bound (21.8%) form, respectively. It showed a huge difference of Cd fraction each other. 0.1M HCl extractable Cd in soil was positively correlated with Cd in rice. Specially, the ratios of 0.1M HCl extractable Cd against total Cd content in soils were 13.7%, 2.6%, and 0.45% in A, B1, and B2 fields, respectively. These ratio were largely affected with Cd uptake to rice grain. Also, exchangable, Fe-Mn oxide bound, and carbonate bound form, which are partially bioavailable Cd fraction to the plant, were positively correlated with Cd in rice while organically bound and residual form was not correlated. Multiple regression equation was developed with Rice Cd = -0.02861 + 0.07456 FR 1(exchangeable) + 0.00252 FR 2(carbonate bound) + 0.001075 FR 3(Fe Mn oxide bound) - 0.00095 FR 4(organically bound) - 0.00348 FR 5(residual) ($R^2=0.7893^{***}$) considering Cd fraction in soils.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.5
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• pp.232-242
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• 2005

This paper concerns automatic hardware synthesis from data flow graph (DFG) specification for fast HW/SW cosynthesis. A node in BFG represents a coarse grain block such as FIR and DCT and a port in a block may consume multiple data samples per invocation, which distinguishes our approach from behavioral synthesis and complicates the problem. In the presented design methodology, a dataflow graph with specified algorithm can be mapped to various hardware structures according to the resource allocation and schedule information. This simplifies the management of the area/performance tradeoff in hardware design and widens the design space of hardware implementation of a dataflow graph compared with the previous approaches. Through experiments with some examples, the usefulness of the proposed technique is demonstrated.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.258-261
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• 2000

Highly (h00)-oriented (Ba, Sr)TiO$_3$(BST) thin films were grown by pulsed laser deposition on the perovskite LaNiO$_3$(LNO) metallic oxide layer as a bottom electrode. The LNO films were deposited on SiO$_2$/Si substrates by rf-magnetron sputtering method. The crystalline phases of the BST film were characterized by x-ray $\theta$-2$\theta$, $\omega$-rocking curve and $\psi$-scan diffraction measurements. The surface microsturcture observed by scanning electron microscopy was very dense and smooth. The low-frequency dielectric responses of the BST films grown at various substrate temperatures were measured as a function of frequency in the frequency range from 0.1 Hz to 10 MHz. The BST films have the dielectric constant of 265 at 1 kHz and showed multiple dielectric relaxation at the low frequency region. The origin of these low-frequency dielectric relaxation are attributed to the ionized space charge carriers such as the oxygen vacancies and defects in BST film, the interfacial polarization in the grain boundary region and the electrode polarization. We studied also on the capacitance-voltage characteristics of BST films.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.112-115
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• 2010

Transparent conducting undoped and Al impurity doped ZnO films were deposited on glass substrate by spin coat technique using 24 days aged ZnO precursor solution with solution of ethanol and diethanolamine. The films were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), electrical resistivity ($\rho$), carrier concentration (n), and hall mobility ($\mu$) measurements. XRD data show that the deposited film shows polycrystalline nature with hexagonal wurtzite structure with preferential orientation along (002) crystal plane. The SEM images show that surface morphology, porosity and grain sizes are affected by doping concentration. The Al doped samples show high transmittance and better resistivity. With increasing Al concentration only mild change in optical band gap is observed. Optical properties are not affected by aging of parent solution. A lowest resistivity ($8.5 \times 10^{-2}$ ohm cm) is observed at 2 atomic percent (at.%) Al. With further increase in Al concentration, the resistivity started to increase significantly. The decrease resistivity with increasing Al concentration can be attributed to increase in both carrier concentration and hall mobility.

• Journal of Nutrition and Health
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• v.32 no.8
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• pp.935-945
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• 1999

The factors affecting bone mineral density (BMD) of 103 rural women aged 30 to 76 years were investigated. Data for food and nutrient intake was obtained by 24-hour recall method. BMD of lumbar spine(L1-L4), femoral neck, ward's triangle and trochanter was measured by XR-series x-ray bone densitometer. Serum was collected and analyzed for total Ca, P and ionized Ca (Ca++)content. Relationship between the factors and BMDs was analyzed by Pearson's correlation coefficient(r) and multiple regression analysis. The results are summarized as follows. 50% of the subjects under 50 years of age($\leq$49 yr group) and 86.4% of the subjects from 50 up($\geq$50yr group) were classified as osteopenia or osteoporosis. Mean body weight, height and BMI were 153.1cm, 59.1kg and 25.0kg/$m^2$ in $\leq$49 yr group and 151.9cm, 55.9kg, and 24.2kg/$m^2$ in $\geq$50 yr group. BMDs of lumbar spines and femurs ranged from 0.84 to 1.05g/$m^2$ and from 0.67 to 1.16g/$m^2$ in $\leq$49 yr group, and ranged from 0.67 to 0.85kg/$m^2$ and from 0.68 to 0.44g/$m^2$ in $\geq$50 yr group, respectively. On the whole, the BMDs were reduced to 83.8 to 94.2% of peck bone mass in $\leq$49 yr group and 55.2 to 78.9% of those in $\geq$50 yr group. Mean daily intake of Ca was much less than the Korean RDA, \67.2% in $\leq$49 yr group and 62.3% in $\geq$50 yr group. The average concentration of total Ca, P and Ca++ in serum were within normal range in both age group. Both age and height were significantly related with BMD in both age group but the relationship tended to be stronger in $\geq$50 yr group than in $\leq$49 yr group. Body weight was also a potent determinant of BMD only in 50 yr group. In $\leq$49 yr group, total food intake was positively related with BMDs of ward's triangle, L1 and L2 and intake of cereals and grain products, sugars and sweets, milk and dairy products was positively related with BMDs measured in this study. On the contrary, intake of eggs, oil and fats were positively related with a few BMDs in 50 yr group. The BMDs were positively affected by intake of energy, protein, carbohydrate, Ca, P and Fe in $\leq$49 yr group and those of protein, fat Ca, P, vitamin B1, vitamin B2 and vitamin C in $\geq$50 yr group. It was noteworthy that serum Ca++ concentration was positively related with BMDs of lumbar spine in boty age groups. According to multiple regression analysis, the four factors, age, body weight, height and BMI additionally accounted for 21% of the variance in BMD of trochanter in $\leq$49 yr group and only two factors, age and C a intake accounted for 38% of that of femoral neck in $\geq$50 yr group. Further investigation is necessary to make sure of the relations between BMD and serum Ca++ level.

• Economic and Environmental Geology
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• v.45 no.5
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• pp.487-502
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• 2012

This paper is focused on mineral compositions, microstructures and distributional characters of remained grains in the fault rocks collected from a fault developed in Yongdang-ri, Yangbuk-myeon, Gyeongju City, Korea, using X-ray diffraction (XRD), optical microscope, laser grain size analysis and fractal dimension analysis methods. The exposed fault core zone is about 1.5 meter thick. On the average, the breccia zone is 1.2 meter and the gouge zone is 20cm thick, respectively. XRD results show that the breccia zone consists predominantly of rock-forming minerals including quartz and feldspar, but the gouge zone consists of abundant clay minerals such as chlorite, illite and kaolinite. Mineral vein, pyrite and altered minerals commonly observed in the fault rock support evidence of fault activity associated with hydrothermal alteration. Fractal dimensions based on box counting, image analysis and laser particle analysis suggest that mineral grains in the fault rock underwent fracturing process as well as abrasion that gave rise to diminution of grains during the fault activity. Fractal dimensions(D-values) calculated by three methods gradually increase from the breccia zone to the gouge zone which has commonly high D-values. There are no noticeable changes in D-values in the gouge zone with trend being constant. It means that the bulk-crushing process of mineral grains in the breccia zone was predominant, whereas abrasion of mineral grains in the gouge zone took place by continuous fault activity. It means that the bulk-crushing process of mineral grains in the breccia zone was predominant, whereas abrasion of mineral grains in the gouge zone took place by continuous fault activity. Mineral compositions in the fault zone and peculiar trends in grain distribution indicate that multiple fault activity had a considerable influence on the evolution of fault zones, together with hydrothermal alteration. Meanwhile, fractal dimension values(D) in the fault rock should be used with caution because there is possibility that different values are unexpectedly obtained depending on the measurement methods available even in the same sample.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.7
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• pp.624-631
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• 2006

This study was conducted to make clustering analysis based on major physicochemical characteristics related to palatability of cooked rice. 89 Korea-bred japonica rice cultivars could be largely classified into two groups, that is, Dongjinbyeo and Ilpumbyeo groups. The Ilpumbyeo group was divided into two subgroups; Ilpumbyeo and Chucheongbyeo groups. The two major rice groups showed significant difference in viscogram properties of rice flour. Ilpumbyeo group revealed slightly higher estimates of viscogram traits as compared with Dongiinbyeo group in average. Early-maturing rice group showed slighly lower estimates of taste meter and higher protein content compared with medium or medium late maturing ones. Also, early and medium-maturing groups exhibited slightly higher estimates of peak, hot and breakdown viscosities but lower estimates of consistenency and setback viscosities compared with medium-late-maturing one. The rice cultivars developed in 2000's revealed slightly higher estimates of peak, hot, cool and consistency viscosities compared with those in $1980's{\sim}1990's$. The grain quality properties significantly associated with the esimates of Toyo taste meter were protein and amylose contents and hot viscosity. The lower protein content and hot viscosity and the higher amylose content, the higher estimates of the taster meter. The protein content was highly negatively correlated with amylose content of milled rice. The important quality components contributed to multiple regression formula for estimating the Toyo taster meter values were protein content, alkali digestion value, and hot viscosity. The fittness of this formula was about 49% along with the coefficients of determination.