• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.9
• /
• pp.80-89
• /
• 1997

Die sinking electrical discharge machining(EDM) was conducted for ceramic composite of 33 weight percent TiC based on AI$_{2}$O$_{3}$ ceramic matrix according to the change of current and duty factor(DF). Material removal rate(MRR) was increased as the current and the duty factor increased, but better surface mor-pholoty was obtained in the region of lower current and duty factor. From the scanning electron microscopy(SEM) photographs and the energy dispersive X-ray spectroscopy(EDX) of the EDMed surface, EDM trace formed by one discharge spark was analyzed. Although the bending strength after EDM was highly decreased, reliability obtained by weibull analysis was increased twice. The bending strength was recovered or more by barrel polishing after EDM. From the FEM analysis of temperature for one spark, the possible melting region of AI$_{2}$O$_{3}$and TiC was obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.438-441
• /
• 2001

In this study,microstructure and piezoelectric characteristics of PNW-PMN-PZT ceramics manufactured using attrition milling method were investigated. Sintering temperature of the ceramics was varied from $1180^{\circ}C$ to $1240^{\circ}C$.With increasing sintering temperature, dielectric constant was increased. In the specimen sintered at $1120^{\circ}C$,electromechanical coupling factor(Kp) and density showed the maxinum values of 0.546 and $7.78(g/cm^{3})$, respectively. In the specimen sintered at $1160^{\circ}C$,mechanical quality factor(Qm) also showed the maxinum value of 1,943.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.438-441
• /
• 2001

In this study, microstructure and piezoelectric characteristics of PNW-PMN-PZT ceramics manufactured using attrition milling method were investigated. Sintering temperature of the ceramics was varied from 1180$^{\circ}C$ to 1240$^{\circ}C$ .With increasing sintering temperature, dielectric constant was increased. In the specimen sintered at 1120$^{\circ}C$, electromechemical coupling factor(Kp) and density showed the maxinum values of 0.546 and 7.78(g/$\textrm{cm}^2$), respectively In the specimen sintered at 1160$^{\circ}C$, mechanical quality factor(Qm) also showed the maximum value of 1,943.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.834-838
• /
• 2002

In this paper, we have fabricated 4H-SiC schottky diodes utilizing a metal-oxide overlap structure for electric filed termination. The barrier height and Ideality factor were measured by current-voltage, capacitance-voltage characteristics. Schottky barrier height(SBH) were 1.41ev for Ni and 1.35eV for Pt, 1.52eV for Pt/Ti at room temperature and Pt/Ti Schottky diode exhibited Ideality factor was 1.06 to 1.4 in the range of $25^{\circ}C{\sim}200^{\circ}C$. To improve the reverse bias characteristics, an edge termination technique is employed for Pt/Ti/4H-SiC Schottky rectifiers and the device show excellent characteristics with higher blocking voltage up to 780V compared with unterminated devices.

• Biomedical Science Letters
• /
• v.7 no.1
• /
• pp.1-5
• /
• 2001

A cDNA of coagulation Factor IX gene has been screened from the $\lambda$gt11 human fetal liver cDNA library, and used to construct a 2.8-kb full length cDNA after recombining with the N-terminal fragment from pTZ-FIX. Human genomic DNA was isolated, digested with the restriction endonucleases, TaqI, EcoRI, and HindIII, and Southern hybridization was performed using the full length factor IX cDNA as a probe. The hybridized bands generated by the restriction endonucleases were the followings: TaqI, 0.3, 1.0, 1.6, 1.8, 2.7, 3.7, and 5.3 kb bands; EcoRI, 1.8, 4.8, 4.9, 5.5, 6.8, and 12.6 kb bands; HindIII, 4.1, 4.4, 5.2, 5.8, 7.6, and 12.5 kb bands. When the Southern bands were physically mapped along the genome, about 50-kb continuous region harboring almost all of the genomic region of Factor Ⅸ gene was covered. These results suggest a possibility of using an exonal cDNA probe to diagnose abnormalities including large deletions, insertions, and rearrangements along the genome, if there is any.

• Reproductive and Developmental Biology
• /
• v.40 no.2
• /
• pp.23-26
• /
• 2016

Transcription factor called activating enhancer binding protein 2C (AP2-gamma) is found in a variety of species and expressed from oocyte stage onwards, particularly restricted to the trophectoderm. Recent studies demonstrated that ablation of Tfap2c led to failure of tight junction biogenesis, particularly the knock-down embryos of Tfap2c did not form cavity from morula to blastocyst in mouse and pig. We speculated that the Tfa2pc may also be involved in desmosome biogenesis because blastocoel formation is coincident with the establishment of desmosome. To determine this, we depleted Tfap2c injecting siRNA into one-cell zygote and analysed the expression levels of genes that are required for desmosome complex such as PkP2, Pkp3, Dsc2, and Dsg2. We found only Pkp3 was up-regulated in the knockdowned morula embryos. Interestingly, upstream region of Pkp3 had putative Tfap2c binding sites. In conclusion, our results suggest that Tfap2c is not a crucial factor but somehow it might be involved in desmosome biogenesis directly or indirectly via Pkp3.

• The Korea Journal of Herbology
• /
• v.34 no.6
• /
• pp.99-107
• /
• 2019

Objective : The present study was conducted to investigate the effects of Chaenomelis Fructus (CF) on the regulation of biogenesis in C2C12 mouse skeletal muscle cells. Methods : C2C12 myoblasts were differentiated into myotubes in 2% horse serum-containing medium for 5 days, and then treated with CF extract at different concentrations for 48 hr. The expression of muscle differentiation markers, myogenin and myosin heavy chain (MHC) and mitochondrial biogenesis-regulating factors, peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC1α), sirtuin1 (Sirt1), nuclear respiratory factor1 (NRF1) and transcription factor A, mitochondrial (TFAM), and the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) were determined in C2C12 myotubes by reverse transcriptase (RT)-polymerase chain reaction (RT-PCR) and western blot, respectively. The cellular glucose levels and total ATP contents were measured by cellular glucose uptake and ATP assays, respectively. Results : Treatment with CF extract (0.01, 0.02, and 0.05 mg/㎖) significantly increased the expression of MHC protein in C2C12 myotubes compared with non-treated cells. CF extract significantly increased the expression of PGC1α and TFAM in the myotubes. Also, CF extract significantly increased glucose uptake levels and ATP contents in the myotubes. Conclusion : CF extract can stimulate C2C12 myoblasts differentiation into myotubes and increase energy production through upregulation of the expression of mitochondrial biogenetic factors in C2C12 mouse skeletal muscle cell. This suggests that CF can help to improve skeletal muscle function with stimulation of the energy metabolism.

• Biomolecules & Therapeutics
• /
• v.30 no.5
• /
• pp.447-454
• /
• 2022

Few studies have evaluated the role of autophagy in the development of oxaliplatin (OXT) resistance in colon cancer cells. In this study, we compared the role of autophagy between SNU-C5 colon cancer cells and OXT-resistant SNU-C5 (SNU-C5/OXTR) cells. At the same concentration of OXT, the cytotoxicity of OXT or apoptosis was significantly reduced in SNU-C5/OXTR cells compared with that in SNU-C5 cells. Compared with SNU-C5 cells, SNU-C5/OXTR cells exhibited low levels of autophagy. The expression level of important autophagy proteins, such as autophagy-related protein 5 (Atg5), beclin-1, Atg7, microtubule-associated proteins 1A/1B light chain 3B I (LC3-I), and LC3-II, was significantly lower in SNU-C5/OXTR cells than that in SNU-C5 cells. The expression level of the autophagy-essential protein p62 was also lower in SNU-C5/OXTR cells than in SNU-C5 cells. In SNU-C5/OXTR cells, the production of intracellular reactive oxygen species (ROS) was significantly higher than that in SNU-C5 cells, and treatment with the ROS scavenger N-acetylcysteine restored the reduced autophagy levels. Furthermore, the expression of antioxidant-related nuclear factor erythroid 2-related factor 2 transcription factor, heme oxygenase-1, and Cu/Zn superoxide dismutase were also significantly increased in SNU-C5/OXTR cells. These findings suggest that autophagy is significantly reduced in SNU-C5/OXTR cells compared with SNU-C5 cells, which may be related to the production of ROS in OXT-resistant cells.

• Child Health Nursing Research
• /
• v.1 no.1
• /
• pp.47-58
• /
• 1995

This study was performed to test the validity and reliability of the Health Self-Determinism Index for Children(HSDI-C), an instrument designed to measure dimensions and strength of motivation in health behavior, to improve the applicability of the tool through application to the various samples. The convenient sample of 148 (boys=75, girls=72 third grade=42, fourth grade=22, fifth grade=32, sixth grade=52 : Caucasian=72, Asian=30, African=19) comprised the children at a chatholic elementary school in Chicago. The children completed English version of HSDI-C from December 5th, 1994 to January l0th, 1995. The findings were as follows : 1. Four factors of HSDI-C were isolated through the principal component analysis and oblique rotation, and explained 48% of the variance in total score. Low correlations among four factors were anticipated because each factor contributed uniquely, All items of the tool loaded above .30 on one of 4 factors. But items loaded on each factor in this study were very different from those in the previous studies. 2. Cronbach's alpha coefficient for internal consistency was .81 for the total items and .57∼ .81 for 4 subscales. 3. The differences of HSDI-c mean scores between boys and girls and that of among races were not statistically signifcant, but the mean score of girls and the Caucasian were relatively high. The total mean score of the scale was highest at the 3rd grade, decreased at the 4th or 5th grade, and reincreased at the 6th grade. The trend of mean score of four subscales was similar to that of total mean score. According to the results, suggested below : 1. The items loaded on each factor in this study were very different from those in the previous studies. To clear away the problem of the conceptual confusion, HSDI-C needs to be performed to various and large samples. 2. Unexpectedly, the HSDI-C mean score decreased at middle school age. A longitudinal study will be helpful to search for the change trend of the intrinsic motivation. 3. To improve the applicabilty of the HSDI-C, various reliability and validity test methods besides factor analysis or internal consistency are recommended.

• The Journal of Korean Academy of Sensory Integration
• /
• v.14 no.2
• /
• pp.11-21
• /
• 2016

Objective : The purpose of the study is to examine the construct validity and internal consistency of the Sensory Processing Scale for Children (SPS-C). Method : 117 participants who are aged 3 to 5 years old has been evaluated by the Sensory Processing Scale for Children (SPS-C) for this study and the period is from November 2014 to June 2016. Statistics used for data analysis is factor analysis for construct validity and Cronbach's alpha for internal consistency. Results : In the factor analysis, the items in auditory, visual, and tactile showed a high factor loading, respectively. The items in vestibular and proprioceptive were overlapped. For internal consistency, Cronbach's alpha was .728 for whole scale which is high level. And Cronbach's alpha of each factor was range within .326~.636. Conclusion : The results of the psychometric test in this study evidence that the SPS-C is valid and reliable to be utilized. Further study need to examine various validities and reliabilities as well as standardization.