• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.340-341
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• 2012

In this work, we investigated the effects of temperature stress on flatband voltage (VFB) shifts of HfO2-SiO2 double gate dielectrics devices. Fig. 1 shows a high frequency C-V of the device when a positive bias for 10 min and a subsequent negative bias for 10 min were applied at room temperature (300 K). Fig. 2 shows the corresponding plot when the same positive and negative biases were applied at a higher temperature (473.15 K). These measurements are based on the BTS (bias temperature stress) about mobile charge in the gate oxides. These results indicate that the positive bias stress makes no difference, whereas the negative bias stress produces a significant difference; that is, the VFB value increased from ${\Delta}0.51$ V (300 K, Fig. 1) to ${\Delta}14.45$ V (473.15 K, Fig. 2). To explain these differences, we propose a mechanism on the basis of oxygen vacancy in HfO2. It is well-known that the oxygen vacancy in the p-type MOS-Cap is located within 1 eV below the bottom of the HfO2 conduction band (Fig. 3). In addition, this oxygen vacancy can easily trap the electron. When heated at 473.15 K, the electron is excited to a higher energy level from the original level (Fig. 4). As a result, the electron has sufficient energy to readily cross over the oxide barrier. The probability of trap about oxygen vacancy becomes very higher at 473.15 K, and therefore the VFB shift value becomes considerably larger.

• Korean Journal of Materials Research
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• v.22 no.9
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• pp.459-464
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• 2012

We investigated cleaning effects using $NH_4OH$ solution on the surface of Cu film. A 20 nm Cu film was deposited on Ti / p-Si (100) by sputter deposition and was exposed to air for growth of the native Cu oxide. In order to remove the Cu native oxide, an $NH_4OH$ cleaning process with and without TS-40A pre-treatment was carried out. After the $NH_4OH$ cleaning without TS-40A pretreatment, the sheet resistance Rs of the Cu film and the surface morphology changed slightly(${\Delta}Rs:{\sim}10m{\Omega}/sq.$). On the other hand, after $NH_4OH$ cleaning with TS-40A pretreatment, the Rs of the Cu film changed abruptly (${\Delta}Rs:till{\sim}700m{\Omega}/sq.$); in addition, cracks showed on the surface of the Cu film. According to XPS results, Si ingredient was detected on the surface of all Cu films pretreated with TS-40A. This Si ingredient(a kind of silicate) may result from the TS-40A solution, because sodium metasilicate is included in TS-40A as an alkaline degreasing agent. Finally, we found that the $NH_4OH$ cleaning process without pretreatment using an alkaline cleanser containing a silicate ingredient is more useful at removing Cu oxides on Cu film. In addition, we found that in the $NH_4OH$ cleaning process, an alkaline cleanser like Metex TS-40A, containing sodium metasilicate, can cause cracks on the surface of Cu film.

• Childhood Kidney Diseases
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• v.20 no.2
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• pp.45-49
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• 2016

Purpose: This study was performed to evaluate the effects of cyclosporine-A (CsA) on linear growth in pediatric patients with steroid-dependent (SDNS) or resistant nephrotic syndrome (SRNS). Methods: Thirty-five pediatric patients with SDNS or SRNS undergoing glucocorticoid (GC) and/or CsA treatment were retrospectively reviewed. Seventeen patients were treated with GC alone and 18 were treated with GC and CsA. The cumulative doses of GC and CsA were quantified (mg/kg/day). Linear growth during the follow-up period was defined as the difference in Z-score between the initial and final height according to the follow-up period (${\Delta}$ height Z score/year). The associations between linear growth and clinical parameters were analyzed. Results: The linear growth of patients in the two groups was not significantly different (P=0.262). The ${\Delta}$ height Z score/year did not show a significant correlation with the cumulative doses of CsA, but was negatively correlated with the cumulative dose of GC and positively correlated with the Z score for height at the time of diagnosis. Conclusion: In children with SDNS or SRNS undergoing GC therapy, added CsA treatment may not have harmful effects on linear growth.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.11
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• pp.5031-5035
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• 2016

Docetaxel, recognized as a stabilizing microtubule agent, is frequently administrated as a first line treatment for prostate cancers. Due to high side effects of monotherapy, however, combinations with novel adjuvants have emerged as an alternative strategy in cancer therapy protocols. Here, we investigated the combined effects of stattic and docetaxel on the DU145 prostate cancer cell line. Cytotoxicity was evaluated by MTT assay. To understand molecular mechanisms of stattic action, apoptotic related genes including Bcl-2, Mcl-1, Survivin and Bax were evaluated by real-time RT-PCR. Alteration in the expression of pro-apoptotic Bax and anti-apoptotic Bcl-2 genes and Bax/Bcl-2 ratio were investigated via the $2^{{\Delta}{\Delta}CT}$ method. The $IC_{50}$ values for docetaxel and stattic were $3.7{\pm}0.9nM$ and $4.6{\pm}0.8{\mu}M$, respectively. Evaluation of key gene expression levels revealed a noticeable decrease in antiapoptotic Bcl-2 and Mcl-1 along with an increase in pro-apoptotic Bax mRNA levels (p<0.05). Our results suggest that combination of a STAT3 inhibitor with doctaxel can be considered as a potent strategy for induction of apoptosis via increasing Bax mRNA expression.

• The Journal of the Korean dental association
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• v.55 no.2
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• pp.156-164
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• 2017

Purpose: The aim of this in vitro study was to assess changes in remineralization by stimulated human saliva over a short period of 48 hours with quantitative light-induced fluorescence (QLF) technology. Materials and Methods: Bovine incisor surfaces were demineralized for 10 days. Two types of stimulated saliva were collected from 7 healthy persons. 24 hours after tooth brushing (Stimulated saliva group) and immediately after tooth brushing with 1,000 ppm NaF dentifrice (Dentifrice saliva group). The specimens were immersed in saliva and fluorescence images were obtained by QLF-digital (QLF-D $biluminator^{TM}$,) at 2, 4, 6, 12, 24, and 48 hours fluorescence loss (${\Delta}F%$) of the lesions. A paired t-test was performed to assess fluorescence differences between before (${\Delta}F_{baseline}$) and after (${\Delta}F_{treatment\;time}$) the remineralization process. Results: Before the remineralization, the mean ${\Delta}F_{baseline}$ of the initial demineralized specimens was $-18.42{\pm}0.15$ (%). In both groups, the ${\Delta}F$ values obtained at baseline and after 2 hours were statistically significant (P < 0.001), indicating recovery of the lesions by approximately 40% after 2 hours. After 48 hours, remineralization rates were slightly higher (49%) for the stimulated saliva group than for the dentifrice saliva group (41%), but the difference was not statistically significant. Conclusions: With QLF minute degrees of remineralization by saliva can be measured in periods as short as 2 hours. Additionally no significantly higher effects of remineralization were observed in the dentifrice saliva group when compared to the stimulated saliva group.

• Journal of Life Science
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• v.19 no.12
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• pp.1829-1835
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• 2009

Hyperventilation (HV) is routinely induced in order to activate brain waves during an electroencephalogram (EEG). The aim of this study was to examine the effects of HV conditions on EEG and suggested basic data for the standardized procedure. Three degrees of HV were induced for 5 minutes with a ventilation volume of 160 ml/min (control group), 240 ml/min, and 300 ml/min in rats. Powers of delta, theta, alpha, and beta waves were examined by a quantitative EEG. The results showed that there was no significant difference in the powers of all EEG waves between the control and 240 ml/min groups. However, a notable change in EEG powers during HV induced by a ventilation volume of 300 ml/min was observed in the frontal cerebral region as follows: power of the delta was increased by 12.8% (p<0.01), powers of the theta, alpha and beta were decreased by 41.3% (p<0.01), 48.6% (p<0.05), and 41.9% (p<0.05), respectively. Therefore, it is concluded that an increase of about 90% of the normal ventilation volume might be adequate for the hyperventilation, and a useful parameter for evaluation of the qualified hyperventilation might be an alteration of the frontal EEG powers.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.387-394
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• 2019

The purpose of this study was to identify the moderated effects of emotional intelligence on the relationship between transition shock and adaptation on clinical practice among nursing students. Subjects were 185 associate nursing students associate nursing students(3rd). The data were collected using self -report questionnaire from May 1 to June 14, 2019. Data were analyzed by descriptive statistics, t-test, ANOVA, Pearson correlation and hierarchical multiple regression with SPSS/WIN 23.0. Mean point of transition shock(4 point scale) was 2.32. Mean point of emotional intelligence(5 point scale) was 3.61, and adaptation on clinical practice(5 point scale) was 3.40. Transition shock were significantly negative correlation with emotional intelligence(r=-.26. p <.001) and adaptation on clinical practice(r=-.43. p <.001) in nursing students. Emotional intelligence were significantly positive correlation with adaptation on clinical practice(r=.36. p <.001). Emotional intelligence has been shown to modulate the relationship between transition shock shock and adaptation on clinical practice(${\Delta}R^2=0.21$, p <.001). Therefore, to decrease the transition shock and to increase the adaptation on clinical practice of nursing students, It is necessary to develop the program for increase emotional intelligence of nursing students.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.527-535
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• 2000

Accurate determination of the relative restraint of beam-to-column connections is important for both the strength and the serviceability of structural frames. But steel frame analysis is carried out under the assumption that the connections are either fixed or pinned. Overestimating the connection restraint can result in underestimating lateral sway and underestimating the connection restraint can lead to underestimating forces developed in the beams and columns. This implies that the exact stiffness of connections as well as the geometric effects should be considered in the frame analysis and the overall behavior of connections could be described adequately. Therefore, the stiffness matrix which is able to consider the moment-rotation of connection was derived previously and the modified exponential model, power model and the proposed log model are adopted for modeling the semi-rigid connections. The main purpose of this study is to examine the feasibility of the derived stiffness matrix and to show the validity of log model proposed.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.2
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• pp.79-89
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• 1997

The objective of this paper is to investigate the mechanical characteristics of the laminated rubber bearings (LRBs) for the seismic isolation. The evaluations of the proposed equations of the LRB horizontal stiffness are carried out and these equations are extended to the visco-elastic problems to investigate the damping amplifications of LRBs. The stability evaluation of LRBs is also performed. For investigation of the dynamic characteristics of LRBs, the horizontal stiffness equations of the LRBs considering the P-delta effects are applied to the modeling of a seismically isolated structure and the earthquake response time history analyses are carried out. From this research, the proposed simple equation of the horizontal stiffness of LRB is so useful for the design loads and easily extended to the visco-elastic problems. Through the stability evaluation of LRB, the increasing ratio of the total rubber thickness of the LRB severely decrecises the bucking load than the increasing ratio of unit rubber thickness. From the comparison of the dynamic shear deflection of LRB, the analysis results are in good agreement with those of the experiments.

• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.749-758
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• 2017

In structural mechanics, traditional analyses methods usually employ matrix operations for obtaining displacement and internal forces of the structure under the external effects, such as distributed loads, earthquake or wind excitations, and temperature changing inter alia. These matrices are derived from the well-known principle of mechanics called minimum potential energy. According to this principle, a system can be in the equilibrium state only in case when the total potential energy of system is minimum. A close examination of the expression of the well-known equilibrium condition for linear problems, $P=K{\Delta}$, where P is the load vector, K is the stiffness matrix and ${\Delta}$ is the displacement vector, it is seen that, basically this principle searches the displacement set (or deformed shape) for a system that minimizes the total potential energy of it. Instead of using mathematical operations used in the conventional methods, with a different formulation, meta-heuristic algorithms can also be used for solving this minimization problem by defining total potential energy as objective function and displacements as design variables. Based on this idea the technique called Total Potential Optimization using Meta-heuristic Algorithms (TPO/MA) is proposed. The method has been successfully applied for linear and non-linear analyses of trusses and truss-like structures, and the results have shown that the approach is much more successful than conventional methods, especially for analyses of non-linear systems. In this study, the application of TPO/MA, with Harmony Search as the selected meta-heuristic algorithm, to cables net system is presented. The results have shown that the method is robust, powerful and accurate.