• Journal of the Korean Society for Nondestructive Testing
• /
• v.23 no.5
• /
• pp.429-438
• /
• 2003

The effects of fiber orientation on acoustic emission(AE) characteristics have been studied for the unidirectional and satin-weave, continuous glass-fiber reinforced plastic(UD-GFRP and SW-GFRP) tensile specimens. Reflection and transmission optical microscopy was used for investigation of the damage zone of specimens. AE signals were classified as different types by using short time fourier transform(STFT) : AE signals with high intensity and high frequency band were due to fiber fracture, while weak AE signals with low frequency band were due to matrix and interfacial cracking. The feature in the rate of hit-events having high amplitudes showed a process of fiber breakages, which expressed the characteristic fracture processes of individual fiber-reinforced plastics with different fiber orientations and with different notching directions. As a consequence, the fracture behavior of the continuous GFRP could be monitored as nondestructive evaluation(NDE) through the AE technique.

• Korean Journal of Child Studies
• /
• v.17 no.1
• /
• pp.189-212
• /
• 1996

The purpose of this study was to investigate how parental childrearing behavior and children's sibling relationships are related to children's self-esteem. 440 middle class families consisting of two children and their parents were the subjects of this study. The research instruments included a childrearing behavior questionnaire, the Sibling Relationships Questionnaire (Furman & Buhrmester, 1985), and the Self-Perception Profile for Children (Harter, 1985). Analyses of the data included correlation analysis, canonical correlation, regression, stepwise multiple regression, and MANOVA with stepwise discriminant analysis as the follow-up test. The most powerful predictors of children's self-esteem were the Warmth-Acceptance of childrearing behavior and the Warmth-Closeness of sibling relationships. The self-esteem dimension was best predicted by parental childrearing behavior and by children's sibling relationships was Global Self-Worth. Behavioral Conduct was best predicted by the Rejection-Restriction factor of childrearing, and by Conflict (for boys) and Rivalry (for girls) factors of sibling relationships. Children's self-esteem was related more strongly to the Warmth-Acceptance and the Rejection-Restriction of opposite-sex parents. The effects of Permissiveness-Nonintervention were stronger in same-sex parent-child dyads. Parental childrearing behaviors accounted for boy's self-esteem better than girl's with the exception of Behavioral Conduct. Sibling relationships accounted for girl's self-esteem better than boy's. The $2{\times}2$ MANOVA revealed interaction effects of parental childrearing behaviors and sibling relationships on children's self-esteem. Two factors of Rivalry and Conflict in sibling relationships and all three factors of childrearing behaviors showed significant interaction effects, The childrearing factor of Permissiveness-Nonintervention and the sibling factor of Rivalry, which were relatively weak predictors of self-esteem when acting alone, gained power in explaining children's self-esteem within the interactional context.

• Journal of the Korean Electrochemical Society
• /
• v.13 no.1
• /
• pp.34-39
• /
• 2010

This work investigated the effect of anode thickness on the anodic overpotential with $100\;cm^2$ class MCFC single cells. The hydrogen oxidation rate in the molten carbonate is sufficiently high, which may lead to weak relation of overpotential with anode geometrical area. The relation of anode surface area and overpotential was analysed in terms of anode thickness in this work. Steady state polarization, inert gas step addition (ISA), and reactant gas addition (RA) methods were employed to the two cells with 0.77 mm and 0.36 mm thickness of anode. The result represented that the anodic overpotential at the cells were identical. It implied that the anodic overpotential was independent on the electrode thickness within the tested range.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.7
• /
• pp.561-568
• /
• 2013

After we designed Bearingless rotor hub system for 7,000lb class helicopter, flexbeam fatigue analysis was conducted for validation of requirement life time 8,000 hours. sectional structural analysis method applying elastic beam model was used. Fatigue analysis for two sections of flexbeam which were expected to weak to fatigue damage from result of static analysis was conducted. Extension, bending and torsion stiffness of flexbeam section shape was calculated using VABS for structure analysis. S-N curve of two composite material which composed flexbeam was generated using wohler equation. Load analysis of bearingless rotor system was conducted using CAMRAD II and load analysis result was applied HELIX/FELIX standard load spectrum to generate bearingless rotor system load spectrum which was used flexbeam fatigue safe life analysis.

• International Journal of Concrete Structures and Materials
• /
• v.6 no.4
• /
• pp.209-220
• /
• 2012

Post-earthquake fire (PEF) can lead to a rapid collapse of buildings that have been partially damaged as a result of a prior earthquake. Almost all standards and codes for the design of structures against earthquake ignore the risk of PEF, and thus buildings designed using those codes could be too weak when subjected to a fire after an earthquake. An investigation based on sequential analysis inspired by FEMA356 is performed here on the immediate occupancy (IO), life safety (LS) and collapse prevention (CP) performance levels of two portal frames, after they are pushed to arrive at a certain level of displacement corresponding to the mentioned performance level. This investigation is followed by a fire analysis of the damaged frames, examining the time taken for the damaged frames to collapse. As a point of reference, a fire analysis is also performed for undamaged frames and before the occurrence of earthquake. The results indicate that while there is minor difference between the fire resistances of the fire-alone situation and the frames pushed to the IO level of performance, a notable difference is observed between the fire-alone analysis and the frames pushed to arrive at LS and CP levels of performance and exposed to PEF. The results also show that exposing only the beams to fire results in a higher decline of the fire resistance, compared to exposing only the columns to fire. Furthermore, the results show that the frames pushed to arrive at LS and CP levels of performance collapse in a global collapse mode laterally, whereas at the IO level of performance and fire-alone situation, the collapse mechanism is mostly local through the collapse of beams. Whilst the investigation is conducted for a certain class of portal frames, the results confirm the need for the incorporation of PEF into the process of analysis and design, and provide some quantitative measures on the level of associated effects.

• Reproductive and Developmental Biology
• /
• v.41 no.3
• /
• pp.57-63
• /
• 2017

Xenotransplantation is proposed as a solution to the problem of organ shortage. However, transplantation of xenogeneic organs induces an antigen-antibody reaction in ${\alpha}$-1,3-gal structure that are not present in humans and primates, and thus complement is also activated and organs die within minutes or hours. In this study, we used FasL gene, which is involved in the immune response of NK cell, and US11, which suppresses MHC Class I cell membrane surface expression, to inhibit cell mediated rejection in the interspecific immunity rejection, and also hDAF(CD55) was introduced to confirm the response to C3 complement. These genes were tranfeced into Korean native pig fetal fibroblasts using pCAGGS vector. And cytotoxicity of NK cell and human complement was confirmed in each cell line. The US11 inhibited the cytotoxicity of NK cell and, in addition, the simultaneous expression of US11 and Fas ligand showed excellent suppress to T-lymphocyte cytotoxicity, hDAF showed weak resistance to cytotoxicity of natural killer cell but not in CD8+ CTLs. Cytotoxicity study with human complement showed that hDAF was effective for reducing complement reaction. In this studies have demonstrated that each gene is effective in reducing immune rejection.

• Journal of Korea Technology Innovation Society
• /
• v.20 no.1
• /
• pp.205-238
• /
• 2017

Display industry in Korea has been rapidly developing over 20 years, now taking the top-class leading position in the world. Nevertheless, many previous studies have mainly focused on major panel set makers. To overcome the drawbacks, this study focuses on supplier companies in the upstream of display industry such as materials, components, and equipments sectors. The research method used in this study is an industry value chain perspective combined with architectural innovation approach. Display panel is produced through fabrication process and modular process, each having a different characteristics of process architecture. This research figured out that there are quite a different development characteristics between materials and components suppliers and equipment suppliers. The number and revenue of materials and components suppliers were quite larger than equipments suppliers. However, the former has been growing mainly in the field of modular process, having a very weak position in the field of fabrication process. On the contrary, equipments suppliers have been showing a continuously growing pattern in the field of fabrication process. The R&D expenditures between these two kinds of suppliers showed a similar pattern. The fabrication process of display panel production is characterized as a highly integral architecture characteristics, so as to be a strong barriers to local suppliers, resulting less development of materials and components suppliers in Korea.

• Journal of KIISE:Databases
• /
• v.30 no.1
• /
• pp.1-13
• /
• 2003

In this paper, we present a content-dependent authorization mechanism for object-oriented database systems. So far, several models of authorization for object-oriented databases have been proposed, but most of these models do not support the authorization based on the database content. This paper shows how the traditional content-independent authorization model can be extended to provide the content-dependent authorization using predicates on the values of attributes of a class. The proposed model makes it possible to group objects that satisfy the specified conditions on the values of the objects and to grant a single authorization on those objects. This model supports the negative authorization and provides the concept of the strong and weak authorization to resolve conflicts between positive and negative authorizations. In addition, we address and resolve some of the problems that arise when the predicates are associated with the authorization. In particular, since the authorization operations of the traditional content- independent model become inadequate for our mode, we redefine the semantics of the authorization operations.

• IMMUNE NETWORK
• /
• v.2 no.4
• /
• pp.248-255
• /
• 2002

Background: TAP1 and TAP2 are two ABC transporter genes located within the class II region of the human MHC. Their protein products form a heterodimer whose function is to transport peptides from the cytoplasm into the endoplasmic reticulum. This study was performed to examine the polymorphism of TAP genes and the distribution of HLA-TAP haplotypes in the Korean population through family analysis. Methods: The subjects used in this study were 50 healthy Korean families consisting of 233 individuals. TAP1 (codons 333 and 637) and TAP2 (codons 379, 565, 577, 651, 665, and 687) typings were carried out by the PCR-restriction fragment length polymorphism (RFLP) method. HLA-DRB1 and DQB1 genotyping results from a previous study were used for HLA-TAP haplotype analysis. Results: The number (gene frequency) of TAP1 and TAP2 alleles detected were 3 for TAP1 (A 81.5%, B 17.0%, and C 1.5%) and 8 for TAP2 (A1 32.0%, A2 12.5%, B 34.0%, Bky2 6.5%, C 7.0%, D 3.0%, E 4.5%, and G 0.5%). Eleven TAP1-TAP2 haplotypes were observed with $frequency{\geq}1%$, among which 4 haplotypes (A-B, B-A1, A-Bky2, and C-E) showed weak but significant positive linkage disequilibrium (P<0.05). When DRB1-DQB1 haplotypes were extended to TAP1 and TAP2 loci, much diversification of haplotypes was observed: 19 different DRB1-DQB1 haplotypes formed 58 different haplotypes extended to TAP1 and TAP2 loci. These results add more evidence to the view that recombination hotspot is present within and around TAP gene region. Conclusion: The allele frequencies of TAP1 and TAP2 genes and the distribution of TAP1-TAP2 and HLA-TAP haplotypes were studied in Koreans based on a family study.

• Toxicological Research
• /
• v.24 no.2
• /
• pp.151-159
• /
• 2008

Rhus verniciflua Stokes(RVS), one of traditional medicinal plants in Asia, was found to have pharmacological activities such as antioxidative and antiapoptotic effects, raising the possibility for the development of a novel class of anti-cancer drugs. Thus, potential genotoxic effects of RVS in three short-term mutagenicity assays were investigated, which included the Ames assay, in vitro Chromosomal aberration test, and the in vivo Micronucleus assay. In Ames test, the addition of RVS water extracts at doses from 313 up to 5000 mg/plate induced an increase more than 2-fold over vehicle control in the number of revertant colonies in TA98 and TA1537 strains for detecting the frame-shift mutagens. The similar increase in reversion frequency was observed after the addition of RVS ethanol extracts. To assess clastogenic effect, in vitro chromosomal aberration test and in vivo micronucleus assay were performed using Chinese hamster lung cells and male ICR mice, respectively. Both water and ethanol extracts from RVS induced significant increases in the number of metaphases with structural aberrations mostly at concentrations showing the cell survival less than 60% as assessed by in vitro CA test. Also, there was a weak but statistically significant increase in number of micronucleated polychromatic erythrocytes(MNPCEs) in mice treated with water extract at 2000 mg/kg while ethanol extracts of RVS at doses of up to 2000 mg/kg did not induce any statistically significant changes in the incidence of MNPCEs. Therefore, our results lead to conclusion that RVS acts as a genotoxic material based on the available in vitro and in vivo results.