• 한국환경농학회:학술대회논문집
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• 2011.07a
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• pp.177-187
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• 2011

This study was conducted to determine some physical and chemical properties of the soil and their relationship to spectroscopic-based (visible range) analytical methods while evaluating soil organic matter fractions and soil quality in degraded and non-degraded soils in a wide range of environments. Soil samples were collected from the different landscape positions of cultivated and noncultivated soils, and the latter from the same landscape positions but with different vegetation, at Songco, Lantapan, Bukidnon. The physical and chemical properties of the soils were determined at the SPAL, CMU, Musuan, Bukidnon while the metagenomic properties were determined at the Laboratory of the University of Missourri, Missourri, USA. Bulk density and air dry soil strength values of the soils from the cultivated areas were generally higher than those of the uncultivated areas. Also, soils at the summit generally had lower bulk density and soil strength values than the other landscape positions. Moreover, soils planted to camote (Ipomoea batatas) had higher bulk density and soil strength values compared to soils grown to pepper under the trees. Exchangeable calcium (Ca), magnesium (Mg), and potassium (K) and cation exchange capacity (CEC) of the soils were generally higher in uncultivated areas than those of the cultivated areas. A similar trend was observed for the potassium permanganate ($KMnO_4$)-oxidizable organic C contents determined by spectroscopic method and the total C contents determined by the Walkley-Black method. The $KMnO_4$-oxidizable organic C contents determined by spectroscopic method and the total C contents determined by the Walkley-Black method were closely related ($r=0.631^{**}$). Hence, the former method shows promise in assessing soil quality as it is a rapid test, relatively low cost and can be distributed as a field kit either with a portable spectrometer or with a color chart.

• Korean Journal of Materials Research
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• v.29 no.10
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• pp.586-591
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• 2019

This study describes the doping effect of $Yb_2O_3$ on microstructure, electrical and dielectric properties of $ZnO-V_2O_5-MnO_2-Nb_2O_5$ (ZVMN) ceramic semiconductors sintered at a temperature as low as $900^{\circ}C$. As the doping content of $Yb_2O_3$ increases, the ceramic density slightly increases from 5.50 to $5.54g/cm^3$; also, the average ZnO grain size is in the range of $5.3-5.6{\mu}m$. The switching voltage increases from 4,874 to 5,494 V/cm when the doping content of $Yb_2O_3$ is less than 0.1 mol%, whereas further doping decreases this value. The ZVMN ceramic semiconductors doped with 0.1 mol% $Yb_2O_3$ reveal an excellent nonohmic coefficient as high as 70. The donor density of ZnO gain increases in the range of $2.46-7.41{\times}10^{17}cm^{-3}$ with increasing doping content of $Yb_2O_3$ and the potential barrier height and surface state density at the grain boundaries exhibits a maximum value (1.25 eV) at 0.1 mol%. The dielectric constant (at 1 kHz) decreases from 592.7 to 501.4 until the doping content of $Yb_2O_3$ reaches 0.1 mol%, whereas further doping increases it. The value of $tan{\delta}$ increases from 0.209 to 0.268 with the doping content of $Yb_2O_3$.

• Korean Journal of Organic Agriculture
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• v.19 no.3
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• pp.343-355
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• 2011

This work was studied the effects of spore density and infection of arbuscular mycorrhizal fungi (AMF) for no-tillage organic cultivation of pepper with wintering green manure crops cultivation in greenhouse field. Spore density of arbuscular mycorrhizal fungi (AMF) in green manure crops was 189 spores/30g fresh soils in control including alive spore (82 spores). Spore density of AMF in all green manure crops was totally 196~226 spores/30g fresh soil and alive spore was 84~112 spores/30g fresh soil. Spore density of AMF in soils of Pepper crop was range of 48.0~56.7 spores/30g fresh soils after cultivation of green manure crops. Infection structure of AMF was not significantly difference in soils of green manure crops and Pepper crop after cultivation of green manure crops. Infection rate of AMF in roots of green crops was low level by 2.8% in giant chickweed, 7.4% in rye, 9.3% in hairy vetch. Infection rate of AMF in roots of barley was the highest level by 20.3%. Infection rate of AMF in roots of Pepper crop was range of 5.2~7.2% after cultivation of green manure crops Also, infection rate of AMF in roots of Pepper crop was 8.1% after the harvest of barley. Infection structure of AMF in barley very well consisted of network with internal hyphae, while hairy vetch and rye tended to no network. There was not a significant relationship between spore density in soils and infection rate of AMF in rhizosphere of Pepper.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.57-66
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• 2016

In order to develop materials with a low environmental load for restoring the destroyed forest, seven types of wood-concrete hybrid laminated materials were manufactured with four softwoods, three hardwoods and concrete, and the effect of wood density on bending creep property was investigated. The bending creep curves showed a shape to considerably increase at the upper right side, and the curves were found to show a linear behavior beyond about 30 min - 1 hour, as behaviors of solid woods and wood-based materials. The initial compliances of wood-concrete hybrid-laminated materials decreased with an increase in the wood density, and those values showed 0.9 - 1.2 times of the concrete one. The creep compliances of hybrid laminated materials showed very low values, which were 0.4 - 0.8 times of the concrete ones. The relative creep were very low with a range from 8.2% to 17.0% range, which were 0.3 - 0.7 times of the concrete ones. These results indicate that these materials can be applied for restoring the destroyed forest to reduce creep deformation of the conventional concrete materials by hybrid-laminating concrete and woods.

• Journal of the Korean Data and Information Science Society
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• v.28 no.5
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• pp.1027-1041
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• 2017

Hyperlipidemia, the status of blood with high level of low-density lipoprotein cholesterol (LDL-C), is known as a main cause of coronary artery diseases such as myocardiac infarction or brain infarct. Statin is the representative prescription to hyperlipidemia and the effects of it depend on the patient's individual conditions such as health-caring habits or adherence to medication. The main effect of statin is reducing LDL-C, which should reach the target range based on National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) guideline. In this research, the reduction of LDL-C and attainment to patient's target range are considered effects of statin. The association between factors - individual conditions and adherence to medication of patients - and the effects of statin is analyzed with National Health Insurance Service-National Sample Cohort (NHIS-NSC).

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.18-22
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• 2013

The Co-base super heat resisting alloy ECY768 is employed in gas turbine because of its high temperature strength and oxidation resistance. The prediction of fatigue life for superalloy is important for improving the efficiency. In this paper, low cycle fatigue tests are performed as variables of total strain range and temperature. The relations between strain energy density and number of cycle to failure are examined in order to predict the low cycle fatigue life of ECY768 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.609-616
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• 1992

This study has been investigated on the milling of Aluminium Distearate (ADS) powder and characteristics of the ADS-doped UO2 pellets. As-received ADS powder of the agglomerated particles has not shown any milling effect because of heat generated during planetary milling. But the use of coolant to effectively remove heat generated during milling has been found an effective way in breaking up the agglomerates of ADS powder. The green density of the UO2 pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% theoretical density, the 200 ppm ADS-doped UO2 pellet has to be pressed under higher compacting pressure of 3500~4000 kgf/$\textrm{cm}^2$ compared with the ADS-undoped UO2 pellet pressed under around 3000 kgf/$\textrm{cm}^2$. The ADS-dpoed UO2 pellet with even relatively low sintered density of 10.27 g/㎤ exhibits open porosity of 1% while open porosity of the ADS-undoped UO2 pellet is reduced to around 1% only after its sintered density increases to 10.43g/㎤. It is, therefore, concluded that doping of ADS powder significantly contributes to the decrease in open porosity of the UO2 pellet. The dilatometry of the ADS doped UO2 pellet shows the sintering rate curve with the bimodal mode, which could be attributed to a phase reaction between UO2 and ADS. The X-ray diffraction analysis indicates that there occurs not any new phase formed but the shift of the peaks. It would be expected that a phase reaction resulting in solid solution would happen in the temperature range of 130$0^{\circ}C$ to 150$0^{\circ}C$ between UO2 and ADS.

• Korean Journal of Materials Research
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• v.20 no.9
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• pp.463-466
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• 2010

We studied the initial reaction mechanism of Zn precursors, namely, di-methylzinc ($Zn(CH_3)_2$, DMZ) and diethylzinc ($Zn(C_2H_5)_2$, DEZ), for zinc oxide thin-film growth on a Si (001) surface using density functional theory. We calculated the migration and reaction energy barriers for DMZ and DEZ on a fully hydroxylized Si (001) surface. The Zn atom of DMZ or DEZ was adsorbed on an O atom of a hydroxyl (-OH) due to the lone pair electrons of the O atom on the Si (001) surface. The adsorbed DMZ or DEZ migrated to all available surface sites, and rotated on the O atom with low energy barriers in the range of 0.00-0.13 eV. We considered the DMZ or DEZ reaction at all available surface sites. The rotated and migrated DMZs reacted with the nearest -OH to produce a uni-methylzinc ($-ZnCH_3$, UMZ) group and methane ($CH_4$) with energy barriers in the range of 0.53-0.78 eV. In the case of the DEZs, smaller energy barriers in the range of 0.21-0.35 eV were needed for its reaction to produce a uni-ethylzinc ($-ZnC_2H_5$, UEZ) group and ethane ($C_2H_6$). Therefore, DEZ is preferred to DMZ due to its lower energy barrier for the surface reaction.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.5
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• pp.305-308
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• 2004

The 7-dial inductive voltage divider(IVD) for application at low frequency range which can precisely divide the in put voltage up to resolution of $10^{-7}$ was fabricated by using the toroidal cores made by super-mumetal strips of 0.025 mm thick and special decade switches. The cores have the initial permeability of 200.000 and magnetic flux density of 0.5 T. The inphase and quadrature ratio errors for a fabricated 7-dial IVD are found to be less than $\pm$4${\times}$$10^{-7}$ and $\pm$5${\times}$$10^{-6}$ rad(k=2), respectively. by calibration using the IVD calibration system of KRISS. The fabrication techniques used and uncertainty evaluation are discussed in this paper.

• Advances in environmental research
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• v.6 no.4
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• pp.255-264
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• 2017

This work investigated the use of sugarcane bagasse ash (SCBA) generated by an energy cogeneration process in sugarcane mill as an alternative raw material in soil-cement brick. The SCBA obtained from a sugarcane mill located in southeastern Brazil was characterized with respect to its chemical composition, organic matter content, X-ray diffraction, plasticity, and pozzolonic activity. Soil-cement bricks were prepared by pressing and curing. Later, they were tested to determine technical properties (e.g., volumetric shrinkage, apparent density, water absorption, and compressive strength), present crystalline phases, and microstructural evolution. It was found that the SCBA contains appreciable amounts of silica ($SiO_2$) and organic matter. The results showed that the SCBA could be used in soil-cement bricks, in the range up to 30 wt.%, as a partial replacement for Portland cement. These results suggest that the SCBA could be valorized for manufacturing low-cost soil-cement bricks.