• Tunnel and Underground Space
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• v.19 no.2
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• pp.158-166
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• 2009

As a basic study for investigating the development of the stress-induced crack in Hoek-Brown rock, a homogenization technique of elastic cracks is proposed. The onset of crack is monitored by Hoek-Brown empirical criterion, while the orientation of the crack is determined by the critical plane approach. The concept of volume averaging in stress and strain component was invoked to homogenize the representative rock volume which consists of intact rock and cracks. The formulation results in the constitutive relations for the homogenized equivalent anisotropic material. The homogenization model was implemented in the standard FEM code COSMOSM. The numerical uniaxial tests were performed under plane strain condition to check the validity of the propose numerical model. The effect of friction between the loading plate and the rock sample on the mode of deformation and fracturing was examined by assuming two different contact conditions. The numerical simulation revealed that the homogenized model is able to capture the salient features of deformation and fracturing which are observed commonly in the uniaxial compression test.

• Journal of Powder Materials
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• v.24 no.2
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• pp.115-121
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• 2017

In this work, p-type Bi-Sb-Te alloys powders are prepared using gas atomization, a mass production powder preparation method involving rapid solidification. To study the effect of the sintering temperature on the microstructure and thermoelectric properties, gas-atomized powders are consolidated at different temperatures (623, 703, and 743 K) using spark plasma sintering. The crystal structures of the gas-atomized powders and sintered bulks are identified using an X-ray diffraction technique. Texture analysis by electron backscatter diffraction reveals that the grains are randomly oriented in the entire matrix, and no preferred orientation in any unique direction is observed. The hardness values decrease with increasing sintering temperature owing to a decrease in grain size. The conductivity increases gradually with increasing sintering temperature, whereas the Seebeck coefficient decreases owing to increases in the carrier mobility with grain size. The lowest thermal conductivity is obtained for the bulk sintered at a low temperature (603 K), mainly because of its fine-grained microstructure. A peak ZT of 1.06 is achieved for the sample sintered at 703 K owing to its moderate electrical conductivity and sustainable thermal conductivity.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.6
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• pp.85-94
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• 2017

In this study, we argue from the Resource-Based View and Signaling Theory that Independent and Corporate VC firms have Different Impacts on time to IPO due to their Different Interests, Motivations, and Resources. Independent VC firms are primarily Financial Oriented, but Corporate VC firms generally are Strategic in Orientation. The results of this study indicate that the time to IPO is differentiated between Corporate VC firms and Independent VC firms. The results show that Independent VC firms have shorter the time to IPO compared to the time to IPO of Corporate VC firms. In addition, this study suggests that it is necessary for firms to select a venture capital that suits their situation and secure a competitive advantage. Using a sample of 300 IPOs from 2010 to 2016, we found Support for the Hypotheses that Independent VC and Corporate VC Ownership are Positively Associated with Time to IPO, whereas Time to IPO of Corporate VC Ownership is Longer than that of Independent VC Ownership.

• Journal of the Korean Home Economics Association
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• v.24 no.3
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• pp.31-42
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• 1986

It is generallybelieved that the values of female students are different depending on the cultural enviromment of society. The purpose of this paper is to discern the value orientation of female students in Korea and America, and how they are related to the clothing behavior. 300 female students were selected as sample from the Univ. of Minnesota and 158 students filled out the questionnair. 420 female students were selected from five unversities in Jinju, Taegy and Pusan. RESULTS : 1) Korean students had highly evaluated theaethetic, political, religious and social values, and American students had higher evaluation on the economic and American students had higher evaluation on the economic and theoretical values. 2) Korean students tended to regard modesty, conformity and management as important factors when they chose new clothes, and for American students, appearance and tool were important. 3) The impact of values on clothing vehavior was as follows. a) Korean students who emphasized theoretical values did not use clothes as an instrument of status symbol and modesty. b) American students who emphasized the economic values tended to have an interest in purchase and wearing of clothes on purpose. c) Korean students who had positive attitudes on the aethetic values tended to be conservative, but they wanted to use the clothes as a demonstration of self exaggeraton. d) Korean students who regarded social values important tended to have a higher interest in the management of clothes. e) Korean students who had highly evaluated the religious values tended to be conservative when the selected new clothes. American students did not want to conform to the group norm when they chose new clothes. On the whole, American students did not put on clothes to achieve a specific goal. In short, it can be concluded that Korean students and American students have different values and they have a great impact on their clothing behavior.

• Journal of the Korean Magnetics Society
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• v.6 no.5
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• pp.298-304
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• 1996

We have manufactured FMR spectrometer over wide range(2-35 GHz). In order to test FMR spectrometer, res¬onance absorption has been measured of the standard sample DPPH. The Q vaules of absorption line are 189-1096. As a result, We noticed that FMR spectrometer has been manufactured well. FMR studies of MgFez04 single crystal have been performed at S, J, K-band. The resonance lines have been observed for the each orientation of (100) plane at 300 K. The values of the magnetic anisotropy constant $K_{1}$ and the spectroscopic spli tting g valule have been calculated from the ferromagnetic resonance curve, $-2.9{\times}10^{4}erg/cm^{3}$, 2.02 at 23.89 GHz, $-2.2{\times}10^{4}erg/cm^{3}$, 1.89 at 5.3 GHz and $-2.8{\times}10^{4}erg/cm^{3}$, 2.01 at 3.6 GHz.

• Elastomers and Composites
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• v.15 no.1
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• pp.3-9
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• 1980

The oxygen permeability and it's proofness of te various commercial polymer films have been investigated at the constant pressure and temperature. Oxygen proofness, the reciprocals of the oxygen permeability for the various samples, were determined by means of a coulometric oxygen permeability tester. The testing of sample films was performed at constant temperature $(23{\pm}1^{\circ}C)$ under 1 atm. for 24 hours. The order of the relative proofness observed are as follows; oriented Nylon (O. Nylon)> oriented Polyester (O. PET)>nonoriented Nylon (N. Nylon)>nonoriented Polyester (N.PET)> rigid Polyvinyl chloride (Rigid PVC)>semirigid Polyvinyl chloride (Semirigid PVC)> oriented Polypropylene (O. PP)>plasticized Polyvinyl chloride (P. PVC)> casted Polypropylene (C. PP)> low density Polyethylene (LDPE)>high density Polyethylene (HDPE, Inflation)> high density-polyethylene (HDPE, T-die) The oxygen proofness of the films was increased with the polarity cf polymer, the film thickness and mechanical orientation and decreased with the addition of plasticizer in PVC. For the use of wrapping materials, one film with the polar property in the main chain of the polymer molecule and the others with nonpolar property in it are laminated for the protection from oxygen and moisture.

• Journal of the Optical Society of Korea
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• v.12 no.2
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• pp.98-102
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• 2008

Optical Coherence Tomography (OCT) is an important noninvasive medical imaging technique that can reveal subsurface structures of biological tissue. OCT has demonstrated a good correlation with histology in sufficient resolution to identify morphological changes in articular cartilage to differentiate normal through progressive stages of degenerative joint disease. Current OCT systems provide individual cross-sectional images that are representative of the tissue directly under the scanning beam, but they may not fully demonstrate the degree of degeneration occurring within a region of a joint surface. For a full understanding of the nature and degree of cartilage degeneration within a joint, multiple OCT images must be obtained and an overall assessment of the joint surmised from multiple individual images. This study presents frequency domain three-dimensional (3-D) OCT imaging of degenerative joint cartilage extracted from bovine knees. The 3-D OCT imaging of articular cartilage enables the assembly of 126 individual, adjacent, rapid scanned OCT images into a full 3-D image representation of the tissue scanned, or these may be viewed in a progression of successive individual two-dimensional (2-D) OCT images arranged in 3-D orientation. A fiber-based frequency domain OCT system that provides cross-sectional images was used to acquire 126 successive adjacent images for a sample volume of $6{\times}3.2{\times}2.5\;mm^3$. The axial resolution was $8\;{\mu}m$ in air. The 3-D OCT was able to demonstrate surface topography and subsurface disruption of articular cartilage consistent with the gross image as well as with histological cross-sections of the specimen. The 3-D OCT volumetric imaging of articular cartilage provides an enhanced appreciation and better understanding of regional degenerative joint disease than may be realized by individual 2-D OCT sectional images.

• Corrosion Science and Technology
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• v.7 no.3
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• pp.139-144
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• 2008

The results of microstructure observations of the $Al_2O_3$ scale formed on a Fe-Cr-Al steel during high temperature oxidation in the $SO_2$ atmosphere are presented. Morphology of the scale has been studied by SEM and TEM techniques. Phase and chemical compositions have been studied by EDX and XRD techniques. The alumina oxide is a primary component of the scale. TEM observations showed that the scale was multilayer. The entire surface of the scale is covered with "whiskers", which look like very thin platelets and have random orientation. The cross section of a sample shows, that the "whiskers" are approximately $2{\mu}m$ high, however the compact scale layer on which they reside is $0.2{\mu}m$ thick. The scale layer was composed mainly of small equiaxial grains and a residual amount of small columnar grains. EDX analysis of the scale surface showed that the any sulfides were found in the formed outer and thin inner scale layer. A phase analysis of the scale formed revealed that it is composed mainly of the $\theta-Al_2O_3$ phase and a residual amount of $\alpha-Al_2O_3$.

• Journal of Korean Academy of Nursing
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• v.46 no.3
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• pp.454-462
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• 2016

Purpose: Posttraumatic growth (PTG) is defined as 'positive psychological change experienced as a result of a struggle with highly challenging life circumstances'. The purpose of this study was to identify the level of PTG and its correlates in Korean patients with breast cancer. Methods: A sample of 120 participants was recruited from outpatients, who had successfully completed primary treatment of breast cancer at a university hospital., Data were collected from June to December, 2014 using Posttraumatic Growth Inventory, Illness Intrusiveness Rating Scale, Cancer Coping Questionnaire, Revised Life Orientation Test and The Multidimensional Scale of Perceived Social Support. Results: Total score for the PTG was $79.18{\pm}17.54$ in patients surviving breast cancer. Bivariate analyses indicated that PTG was positively associated with having a religion, perceived social support, greater optimism, cancer coping, and illness intrusiveness. Results of the regression analysis showed that cancer coping (${\beta}=.29$, p=.001), optimism (${\beta}=0.28$, p=.001) and illness intrusiveness (${\beta}=0.17$, p=.037) were statistically significant in patients' PTG. Conclusion: The research findings show that the variables of cancer coping, optimism and illness intrusiveness significantly explain PTG and these psychological variables can be used to provide improvement in PTG for patients with breast cancer.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.66.2-66.2
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• 2014

We carried out photometric observations of Maria family asteroids during 134 nights spanning from July 2008 to May 2013, and derived synodic rotational periods for 51 objects including obtained periods of 34 asteroids for the first time. In this study, we found that there is a significant excess of fast and slow rotators. The one-sample Kolmogorov-Smirnov test confirms that the spin rate distribution is not consistent with the Maxwellian at a 92% confidence level. From the correlations between rotational period, amplitude of lightcurve, and size, we conclude that rotational properties of Maria family have been changed considerably by the non-gravitational force such as the Yarkovsky and the YORP effect. Using the lightcurve inversion method, we successfully determined the pole orientation for the 13 Maria members, and found the excess of prograde objects versus retrograde with a ratio ($N_p/N_r$) of 3. This implies that retrograde rotators could have been ejected by the 3:1 resonance to the inner Solar System since the generation of Maria family. We estimate that approximately 37 - 75 kilometer-sized Maria asteroids have entered to near-Earth space every 100 Myr.