• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.335-341
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• 2020

This study examined the shear bond strength between the zirconia core and pressed lithium disilicate veneering ceramics. The Schmitz-Schulmeyer test method was used to investigate the core-veneer shear bond strength of industrially manufactured zirconia core ceramic (Zirtooth, HASS, Gangneung, Korea) and pressed veneer ceramic (IPS e.max Zirpress, Vita PM9, GC Initial IQ, HASS Rosetta SM) (N=40). Data were statistically analyzed using one-way ANOVA and Tukey's test (a=0.05). The fractured surfaces of the specimens were examined to determine the failure pattern using a digital microscope. The mean ± SD shear bond strength in MPa were 16.69±3.11, 14.21±3.63, 11.17±2.92, and 27.90±5.71 for IPS e.max Zirpress, VITA PM9, GC Initial IQ, and HASS Rosetta SM, respectively. The average shear bond strength was largest for HASS Rosetta SM, followed by IPS e.max Zirpress, Vita PM9, and GC Initial IQ(p<0.05). The digital microscopy examination of the fracture surface showed adhesive and cohesive failure in pressed lithium disilicate veneering ceramics. The use of lithium disilicate veneer ceramic produced a significantly higher shear bond strength.

• Korean Journal of Poultry Science
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• v.50 no.4
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• pp.203-212
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• 2023

This study conducted a diallel-crossbreeding test using four Korean native chicken parent stock lines (YC, YD, CK, and CF) to develop a native commercial layer with high egg-laying performance. A total of 312 chickens in six combinations were examined for various traits, including livability, body weight, age at first egg-laying, hen-day, and hen-housed egg production, egg weight, and egg quality, from hatching to 60 weeks of age. The results showed that the average survival rate was 77.1±18.8% with the YDYC combination having the highest survival rate along with excellent specific combining ability. The YDYC combination exhibited significantly higher body weight compared to the other combinations (P<0.01). The average age at first egg-laying was 121.3±2.5 days, with no significant difference between the combinations. The average hen-day egg production was 74.0±6.4%, and the hen-housed egg production was 181.4±33.8 eggs with the YDCF and YCCK combinations demonstrating the highest laying performance, while the YDYC and CKCF combinations had the lowest (P<0.05). Laying performance was more influenced by specific combining ability than general combining ability. The eggs from the YDYC combination were significantly lighter and had the darkest shell color (P<0.01), whereas the YDCF combination exhibited the thickest eggshells. There was no difference in internal egg quality among combinations, except the YDCF combination had the darkest yolk color. Overall, we concluded that the YCCK combination, characterized by high laying performance and livability, and the YDCF combination with high laying performance and good egg quality are the most desirable combinations for Korean native commercial layers.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1098-1103
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• 2003

Soybeans released proteins when immersed in water at $50{\sim}60^{\sim}C$. We investigated the changes in the characteristics of soybean when soaked in water at different temperatures and studied the electrophoretic properties of soy proteins in recommended Korean soybean varieties after heat treatment. Soybean seeds were heated in soaking water at temperatures of 30, 40, 50, 60, $70^{\circ}C$ for 90 min, and also from 10 to 150min at $60^{\circ}C$. The pH value of the water decreased with heating time at $60^{\circ}C$, and the amount of soluble solids increased with temperature and heating time. The protein concentration of the solution increased with temperature and time. From SDS-PAGE of the proteins in soaking water, we detected two new bands of 16 kDa- and 31 kDa-proteins from the Korean soybean varieties on heat treatment.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.89-100
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• 2010

Although various methods for determination of damage threshold in rock have been suggested, clear damage thresholds were determined by some methods, but different thresholds were measured by other methods. We determined the damage thresholds in Hangdeung granite using all the methods suggested, and investigated the best methods, applicability and errors of each method. The crack initiation threshold and the crack damage threshold which are important in investigation of characteristics of crack development and failure were verified by field strength ratio method and long-term constant load test. The crack closure stress and the crack initiation stress were 57.5 MPa and 77.6 MPa, and the most exact values were yielded by crack volumetric strain. The secondary crack initiation stress was 90.6 MPa and AE event count and AE event count rate were the effective methods. The volumetric stiffness, AE event count and AE event count rate were the most effective methods for determination of crack coalescence threshold and crack coalescence stress was 110.3 MPa. The crack damage stress was 127.5 MPa and was measured correctly by volumetric stiffness and AE event count rate. The ratio between crack initiation stress and uniaxial compressive strength was 0.47 which was very similar with the FSR value of 0.46. The ratio between crack damage stress and uniaxial compressive strength was almost the same as the ratio between long-term strength and uniaxial compressive strength, indicating that the crack initiation stress and the crack damage stress measured were correct.

• Analytical Science and Technology
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• v.24 no.1
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• pp.38-44
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• 2011

The quality of decoction water would be important for the preparation of herbal medicines. Four types of decoction water, S1, S2, S3 and S4, three types of mineral water from Jeju island and one type of tap water from Seoul region were evaluated. The contents of minerals in decoction water were analysed by ICP-AES and ICP-MS. There was significant difference in the mineral contents between the types of decoction water. The bioactive components from rhubarb were extracted with four types of water and the relationship between mineral contents in water and the extracted amounts of components was evaluated. The total extraction was calculated by evaporating water and weighing the residue. The bioactive components in rhubarb were determined by HPLC method. Kruskall-Wallis rank sum tests were used. Multiple factor analysis was used to analyze the relation between the contents of mineral and total extraction or bioactive components in the decocted solutions. Not only the total extraction but also the amount of extracted bioactive components showed statistically significant relationship with the contents of minerals and anions in decoction water.

• Journal of Korean Society of Forest Science
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• v.80 no.2
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• pp.232-236
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• 1991

The efficacy of berberine sulphate, a fluorochrome having binding properties with both DNA and RNA, was investigated for the detection of mycoplasma-like organisms(MLOs) in jujube(Zizyphus jujuba), paulownia(Paulownia tomentosa), mulberry(Morus alba) trees and periwinkle (Catharanthus roseus) plant. When examined under fluorescence microscope, berberine sulphate-stained sections of diseased samples showed distinct MLO-specific fluorescent particles in the phloem area, while such fluorescence was absent in the healthy ones. This staining technique was proved to be a very accurate method for the diagnosis of MLO infections in woody and herbaceous plants. Furthermore, the cheap and easy procedure could be used to test a great number of samples on MLO infections with reliability and rapidity.

• The Korean Journal of Applied Statistics
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• v.18 no.2
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• pp.253-269
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• 2005

One of the basic assumptions of the regression models is that the parameter vector does not vary across sample observations. If the parameter vector is not constant for all observations in the sample, the statistical model is changed and the usual least squares estimators do not yield unbiased, consistent and efficient estimates. This study investigates the regression model with some or all parameters vary across partitions of the whole sample data when the model permits different response coefficients during unusual time periods. Since the usual test for overall homogeneity of regressions across partitions of the sample data does not explicitly identify the break points between the partitions, the testing the equality between subsets of coefficients in two or more linear regressions is generalized and combined with the test procedure to search the break point. The method is applied to find the possibility and the turning point of the structural change in the long-run unemployment rate in the usual static framework by using the regression model. The relationships between the variables included in the model are reexamined in the dynamic framework by using Vector Autoregression.

• Korean Journal of Weed Science
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• v.10 no.3
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• pp.207-213
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• 1990

Thirty formulations of oxyfluorfen(2-chloro-2,2,2-trifluoro-p-toyl 3-ethoxy-4-nitrophenyl ether were manufactured by adsorption and substitation. Of them 16 formulations n-ere selected because they showed rekatuvely high activity and long durability in the bioassay with (Brassica campestris V.L.) Then, the formulations selected and 4 commercial formulations were tested using Monochoria in pots. As the result, the formulations of polyer 11, elvan 7/40, coal-slag 7/40, zeolite(A), and bentonite(A) were selected because they showed almost complete inhibition of Monochoria even up the 73 days after treatment.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.2
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• pp.67-76
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• 2008

Recently, one of the most outstanding technological characteristics of aerial survey is an application of Direct Georeferencing, which is based on the integration of main sensing sensors such as aerial camera or Lidar with positioning sensors GPS and IMU. In addition, a variety of digital aerial mapping cameras is developed and supplied with the verification of their technical superiority and applicability. In accordance with this requirement, the development of a multi-looking aerial photographing system is just making 3-D information acquisition and texture mapping possible for the dead areas arising from building side and high terrain variation where the use of traditional phptogrammetry is not valid. However, the development of a multi-looking camera integrating different sensors and multi-camera array causes some problems to conduct time synchronization among sensors and their geometric and radiometric calibration. The establishment of a test field for aerial sensor calibration is absolutely necessary to solve this problem. Therefore, this paper describes investigations for photogrammetric Test Field of foreign countries and suggest an establishment scheme for domestic test field.

• Environmental and Resource Economics Review
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• v.19 no.3
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• pp.485-508
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• 2010

This paper examines the long memory property and investigates cointegration in the dynamics of crude oil markets. For these purposes, we apply the joint ARMA-FIAPARCH model with structural break and the vector error correction model (VECM) to three daily crude oil prices: Brent, Dubai and West Texas Intermediate (WTI). In all crude oil markets, the property of long memory exists in their volatility, and the ARMA-FIAPARCH model adequately captures this long memory property. In addition, the results of the cointegration test and VECM estimation indicate a bi-directional relationship between returns and the conditional variance of crude oil prices. This finding implies that the dynamics of returns affect volatility, and vice versa. These findings can be utilized for improving the understanding of the dynamics of crude oil prices and forecasting market risk for buyers and sellers in crude oil markets.