• Advanced Composite Materials
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• v.18 no.4
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• pp.351-364
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• 2009

The thermal stability and elevated temperature mechanical properties of $SiC_P$/Al-11.7Fe-1.3V-1.7Si (Al-11.7Fe-1.3V-1.7Si reinforced with SiC particulates) composites sheets prepared by spray deposition (SD) $\rightarrow$ hot pressing $\rightarrow$ rolling process were investigated. The experimental results showed that the composite possessed high ${\sigma}_b$ (elevated temperature tensile strength), for instance, ${\sigma}_b$ was 315.8 MPa, which was tested at $315^{\circ}C$, meanwhile the figure was 232.6 MPa tested at $400^{\circ}C$, and the elongations were 2.5% and 1.4%, respectively. Furthermore, the composite sheets exhibited excellent thermal stability: the hardness showed no significant decline after annealing at $550^{\circ}C$ for 200 h or at $600^{\circ}C$ for 10 h. The good elevated temperature mechanical properties and excellent thermal stability should mainly be attributed to the formation of spherical ${\alpha}-Al_{12}(Fe,\;V)_3Si$ dispersed phase particulates in the aluminum matrix. Furthermore, the addition of SiC particles into the alloy is another important factor, which the following properties are responsible for. The resultant Si of the reaction between Al matrix and SiC particles diffused into Al matrix can stabilize ${\alpha}-Al_{12}(Fe,\;V)_3Si$ dispersed phase; in addition, the interface (Si layer) improved the wettability of Al/$SiC_P$, hence, elevated the bonding between them. Furthermore, the fine $Al_4C_3$ phase also strengthened the matrix as a dispersion-strengthened phase. Meanwhile, load is transferred from Al matrix to SiC particles, which increased the cooling rate of the melt droplets and improved the solution strengthening and dispersion strengthening.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.144-151
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• 2014

Increasing the gene copy number has been commonly used to enhance the protein expression level in the yeast Pichia pastoris. However, this method has been shown to be effective up to a certain gene copy number, and a further increase of gene dosage can result in a decrease of expression level. Evidences indicate the gene dosage effect is product-dependent, which needs to be determined when expressing a new protein. Here, we describe a direct detection of the gene dosage effect on protein secretion through expressing the enhanced green fluorescent protein (EGFP) gene under the direction of the ${\alpha}$-factor preprosequence in a panel of yeast clones carrying increasing copies of the EGFP gene (from one to six copies). Directly examined under fluorescence microscopy, we found relatively lower levels of EGFP were secreted into the culture medium at one copy and two copies, substantial improvement of secretion appeared at three copies, plateau happened at four and five copies, and an apparent decrease of secretion happened at six copies. The secretion of EGFP being limiting at four and five copies was due to abundant intracellular accumulation of proteins, observed from the fluorescence image of yeast and confirmed by western blotting, which significantly activated the unfolded protein response indicated by the up-regulation of the BiP (the KAR2 gene product) and the protein disulfide isomerase. This study implies that tagging a reporter like GFP to a specific protein would facilitate a direct and rapid determination of the optimal gene copy number for high-yield expression.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.77-82
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• 2015

The effect of the electrode type on the dielectric and piezoelectric properties of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbZrO_3-PbTiO_3$ (PMN-PZT) single crystals was investigated in an effort to improve their properties for various piezoelectric applications. First, three different types of PMN-PZT single crystals [PMN-PZT-A (piezoelectrically soft type; dielectric constant ~ 10,000), PMN-PZT-B (piezoelectrically soft type; phase-transition temperature between the rhombohedral and tetragonal phases ($T_{RT}$) ~ $145^{\circ}C$), PMN-PZT-C (piezoelectrically hard type; high mechanical quality factor ($Q_m$) ~ 1,000)] were fabricated using the solid-state single crystal growth (SSCG) method. Then, four different types of electrodes [sputtered Au, sputtered Cr/Au, sputtered Ti/Au, and fired Ag] were formed on the single crystals, and their dielectric and piezoelectric properties were measured. The single crystals with a sputtered Ti/Au electrode showed the highest dielectric and piezoelectric constants but the lowest coercive electric field ($E_C$). The single crystals with a fired Ag electrode showed the lowest dielectric and piezoelectric constants but the highest coercive electric field ($E_C$). This dependence on the type of electrode was most significant in the piezoelectrically hard PMN-PZT-C single crystals. However, the effects of the electrode type on the phase transition temperatures ($T_C$, $T_{RT}$) and dielectric loss were negligible. These results clearly demonstrate that it is important to select an appropriate electrode so as to maximize the dielectric and piezoelectric properties of single crystals in each type of piezoelectric application.

• Journal of Korean Academy of Nursing
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• v.30 no.1
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• pp.137-147
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• 2000

The purpose of this study was to investigate characteristics of teenagers' perceptions to bullies according to the classification types of Q-methodology. The results of the analysis were classified in 5 types. Type 1, which was the type geared foward solution, showed that they expressed a strong attitude of sympathy and protection towards the victim. However, they had harbored rage and hostile feelings against the assaulter. For example, when they witnessed the bully in action, they positively intervened in the situation. Type 2, which was the observer type, showed that they thought the victims were to blame for their misfortune. Also, when a friend who was left out in the cold by his classmates, they were just watched without showing any special interest. Type 3, which was the type of conflict, indicated that they believed that the both the victim and the assaulter should have responsibility. In contrast to the previous type, they had sympathy for the friend who was left out in the cold by his classmates, they had the dual feeling that intended to use the bully under the situation with his friend. Type 4, which was the type of assenting, indicated that they assumed an indifferent attitude to the situation, while they implied assenting to the situation of the friend who had a bad relationship with them. Type 5, which was the negative type, showed that they had the negative view to the situation of bully itself so that they did not recognize the bully as the method of revenge for whatever reason. The results of the study showed that the bully increased the factor of stress to school life of the victim or assaulter, even in the subjective position. The perception of the bully should change according to the characteristics of the types of people and it is necessary to study how to cope with the situations.

• Korean Journal of Child Studies
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• v.13 no.2
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• pp.217-228
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• 1992

The purpose of this study is to examine the effects of early full-time nonparental care during infancy/toddlerhood on children's socioemotional behaviors during the preschool period. Subjects for this study were 105 three- to five-year-olds from middle-class families in the U. S. A. Children were assigned to one of three groups according to their early care history. Children's social interactions with peers and caregivers during indoor free-play sessions in day care centers were observed for 20 minutes. The head teachers rated the children's social and emotional behaviors on two questionnaires. Mothers completed the Attachment Q-sort for attachment assessment for the preschoolers. In addition, mothers were asked to fill out a questionnaire on their parenting practices. Children who had received full-time nonparental care during infancy and/or toddlerhood were rated by their teachers as being more intellectually competent than children who did not receive full-time nonparental care during first three years of life. They were, however, rated by teachers and were observed by the researcher as being more aggressive than children with no full-time nonparental care. These children were observed to engage in less wandering/onlooking behaviors than children who had not had any full-time nonparental care. Children's attachment security scores and dependency scores did not differ as a function of early nonparental care histories. When the effects of early care patterns, sex of child, and current attachment security to mothers on aggressive behaviors of the preschoolers were examined by a hierarchical regression model, then any "pure" effects of nonparental care and of attachment security on child aggression were minimal after controlling for family background, child care center quality, and maternal childrearing practices. Strong buffering factors for the preschool children (family characteristics, parenting styles, and high quality nonparental care) mediated a possible risk factor of early nonparental care and promoted optimal outcomes for the children.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.6
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• pp.546-554
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• 2012

This paper suggests a design method of an improved phase control loop for tracking resonant frequency of solid type precision resonant gyroscope. In general, a low cost MEMS gyroscope adapts the automatic gain control loops by taking a velocity feedback configuration. This control technique for controlling the resonance amplitude shows a stable performance. But in terms of resonant frequency tracking, this technique shows an unreliable performance due to phase errors because the AGC method cannot provide an active phase control capability. For the resonance control loop design of a solid type precision resonant gyroscope, this paper presents a phase domain control loop based on linear PLL (Phase Locked Loop). In particular, phase control loop is exploited using a higher order PLL loop filter by extending the first order active PI (Proportion-Integral) filter. For the verification of the proposed loop design, a hemispherical resonant gyroscope is considered. Numerical simulation result demonstrates that the control loop shows a robust performance against initial resonant frequency gap between resonator and voltage control oscillator. Also it is verified that the designed loop achieves a stable oscillation even under the initial frequency gap condition of about 25 Hz, which amounts to about 1% of the natural frequency of a conventional resonant gyroscope.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.23 no.1
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• pp.14-22
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• 2012

Objectives : The purpose of present study is to identify the differences between temperament and character traits among adolescents classified by ego resilience and ego control level. Methods : A Junior Temperament and Character Inventory (TCI) was performed on participants, and a California Child Q-Test (CCQ) was tested for by the parents of the adolescent participants. Results : The result of the factor analysis and discriminant analysis show that the participants are classified into three different groups based on CCQ score and item response patterns. The three groups are named the ego resilience group, the undercontrolled group, and the overcontrolled group. The ego resilience group indicates that they have a high level of interest and curiosity but yet they are not easily tempered. Moreover, they behave proactively with a reasonable level of responsibility in order to improve themselves. In contrast, among the undercontrolled group, it is observed that, although the group shows even higher level of interest, curiosity and honesty, they are careless, more impulsive, and have a lack of delayed gratification and shame. Conclusions : The overcontrolled group shows that they are the most cautious and reflective group among the three but also show emotional instability such as strong criticism and passive-aggressiveness. In this study, implications and limitations are discussed.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1244-1245
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• 2008

Recently, piezoelectric transformer is applied to wide fields. Multi layer piezoelectric transformer has the advantage of high step up ratio, electromechanical coupling coefficient(Kp) and mechanical quality factor(Qm), but is indicated of peeling-phenomenon of electrode, rising sintering temperature made price of costly electrode. So in this study, it discuss on method for fabrication of rosen type piezoelectric transformers. For the fabrication as rosen type piezoelectric transformers, synthesized the powder using 0.01Pb$(ni_{1/3}Nb_{2/3})O_3$ - 0.08Pb$(Mn_{1/3}Nb_{2/3})O_3$ - 0.91Pb$(Zr_{0506}Ti_{0496})O_3$ (abbreviated as PNN-PMN-PZT) ceramics. The density, microstructure, dielectric and piezoelectric properties as a function of sintering temperature were investigated. The results indicated that the optimized properties of ceramics were obtained at sintering temperature of 1200$^{\circ}C$, showed the value of $d_{33}$=273pC/N, $K_p$=0.60 $Q_m$=1585, ${\varepsilon}_r$=1454, density=7.917$g/cm^3$ and $tan{\delta}$=0.0064.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.30-37
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• 2005

The microwave dielectric properties and their related structural characteristics in solid solutions of (1-$\chi$) Ba($Mg_{1/3}$Nb$_{2/3}$) $O_3$-$\chi$La(Mg$_{2/3}$Nb$_{1}$3) $O_3$(BLMN) have been investigated by measuring the dielectric constant($\varepsilon$r), Q value and temperature coefficient of resonant frequency($\tau$f) and by observing the crystal structure using high resolution transmission electron microscopy (HRTEM). Microwave dielectric properties showed characteristic features for specific composition. Dielectric constant($\varepsilon$$_{r}$) showed maximum value at the composition which corresponds to the phase boundary between 1 : 2 ordered and 1 : 1 ordered structure. The increase in $\varepsilon$$_{r}$ may be caused by the rattling of ions by incorporating smaller ions and the disordered structure. The variation of temperature coefficient of resonant frequency($\tau$$_{f}$) was investigated in terms of oxygen octahedra tilting.dra tilting.

• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.19-24
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• 2016

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality worldwide. The exploration of new biomarkers with high sensitivity and specificity for early diagnosis of AMI therefore becomes one of the primary task. In the current study, we aim to detect whether there is any heart specific long noncoding RNA (lncRNA) releasing into the circulation during AMI, and explore its function in the neonatal rat cardiac myocytes injury induced by $H_2O_2$. Our results revealed that the cardiac-specific lncRNA MHRT (Myosin Heavy Chain Associated RNA Transcripts) was significantly elevated in the blood from AMI patients compared with the healthy control ($^*p<0.05$). Using an in vitro neonatal rat cardiac myocytes injury model, we demonstrated that lncRNA MHRT was upregulated in the cardiac myocytes after treatment with hydrogen peroxide ($H_2O_2$) via real-time RT-PCR (qRT-PCR). Furthermore, we knockdowned the MHRT gene by siRNA to confirm its roles in the $H_2O_2$-induced cardiac cell apoptosis, and found that knockdown of MHRT led to significant more apoptotic cells than the non-target control ($^{**}p<0.01$), indicating that the lncRNA MHRT is a protective factor for cardiomyocyte and the plasma concentration of MHRT may serve as a biomarker for myocardial infarction diagnosis in humans AMI.