• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.13-19
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• 2012

In order to provide the basis for developing practical mouse embryonic stem cells (mESCs) culture method, how the endogenous level of self-renewal-stimulating factor genes was altered in the mESCs by different extracellular signaling was investigated in this study. For different extracellular signaling, mESCs were cultured in 2 dimension (D), 3D and integrin-stimulating 3D culture system in the presence or absence of leukemia inhibitory factor (LIF) and transcriptional level of $Lif$, $Bmp4$ and $Wnt3a$ was evaluated in the mESCs cultured in each system. The expression of three genes was significantly increased in 3D system relative to 2D system under LIF-containing condition, while only $Wnt3a$ expression was increased by 3D culture under LIF-free condition. Stimulation of integrin signaling in mESCs within 3D system with exogenous LIF significantly up-regulated transcriptional level of $Bmp4$, but did not induce transcriptional regulation of $Lif$ and $Wnt3a$. In the absence of LIF inside 3D system, the expression of $Lif$ and $Bmp4$ was significantly increased by integrin signaling, while it significantly decreased $Wnt3a$ expression. Finally, the signal from exogenous LIF significantly caused increased expression of $Lif$ in 2D system, decreased expression of $Bmp4$ in both 2D and 3D system, and decreased expression of $Wnt3a$ in integrin-stimulating 3D system. From these results, we identified that endogenous expression level of self-renewal-stimulating factor genes in mESCs could be effectively regulated through artificial and proper manipulation of extracellular signaling. Moreover, synthetic 3D niche stimulating endogenous secretion of self-renewal-stimulating factors will be able to help develop growth factor-free maintenance system of mESCs.

• Journal of Welding and Joining
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• v.31 no.5
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• pp.1-6
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• 2013

In carrying out the elastic-plastic analysis, four conditions (equilibrium equation, constitutive equation, condition of compatibility and yield condition) should be satisfied. In welding, the temperature largely changed from a melting temperature to a room temperature. So, yield stress of materials largely changed, too. In particular, yield stress becomes about zero over $700^{\circ}C$. The analysis should be carried out under the condition that equivalent stress generated in temperature increment ${\Delta}T$ did not exceed yield stress of materials at high temperature over $700^{\circ}C$. It should be sufficiently recognized that the obtained results were not reliable if this condition was not satisfied.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.382-387
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• 2016

This paper deals with the assessment of voltage sags regarding the variation of system operating conditions. In general, voltage sag assessment is performed by assuming the constant operating condition throughout the year. However, the assumption can lead to assessment errors in case of considerable changes of system operation condition. This paper presents a method to estimate ESF(expected sag frequency) considering the operating conditions according to the changes of power demand throughout the year.

• Journal of Power Electronics
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• v.3 no.4
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• pp.215-223
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• 2003

In this paper, a new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in the main switch and the main diode, respectively. The auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition. The resonant current required to obtain the ZCT condition is relatively small and regenerated to the input voltage source. The operational principles of a boost converter integrated with the proposed ZCT circuit cell are analyzed and verified by the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2105-2107
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• 2004

In this study, Spiral inductors on the $SiO_2$/Si(100) substrate were fabricated by the magnetron sputtering method. Cu thin film with the thickness of 2 ${\mu}m$ was deposited on the substrate. Also we fabricated square inductors through the wet chemical etching technique. The inductors are completely specified by the turn width and the spacing between spirals. Both the width and spacing between spirals were varied from 10 to 60 ${\mu}m$ and from 20 to 70 ${\mu}m$, respectively. Inductance and Q factor dependent on the RF frequency were investigated to analyze performance of inductor arrays. Also, We recommend that the reasonable Q-factors, spec's turns and thickness of the coil for inductors cab be set to be ideal condition.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.227-230
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• 2001

This paper deals with a bidirectional ac-dc converter used in ups system application. We propose a Voltage-Source-Charge-Pump-Power-Factor-Correction(VS-CPPFC) ac-dc converters. First of all, we propose a charge pump power-factor-correction converter. Secondly, we derive and analyse a unity power factor condition. The proposed topology is based on a half-bridge for the primary and a current-fed push pull for the secondary side of a high frequency isolation transformer. The advantage of bidirectional flow of power achieved by using the same power components is that the circuit is simple and efficient. And the galvanically isolated topology is specially attractive in battery charge/discharge circuits in ups system. We design equivalent model for the steady-state circuit and analyse operation waveforms for each mode. We show that the proposed model can be applied to ups system by simulation processes.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.369-378
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• 2010

The creation of the hydraulic turbine flow factor map will undoubtedly benefit its design by decreasing both the design cycle time and product cost. In this paper, the geometry and flow variables, which effectively affect the flow factor, are proposed, analyzed and determined. These flow variables are further used to create the operating condition maps by using different model approaches categorized into Response Surface Method (RSM) and Artificial Neural Network (ANN). The accuracies of models created by different approaches are compared and the performances of model approaches are analyzed. The influences of chosen variables and the combination of Principle Component Analysis (PCA) and model approaches are also studied. The comparison results between predicted and actual flow factors suggest that two-hidden-layer Feed-forward Neural Network (FFNN), and one.hidden-layer FFNN with PCA has the best performance on forming this mapping, and are accurate sufficiently for hydraulic turbine design.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2090-2092
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• 2004

In this paper, the new measurement methodology of characteristics of the vibratory micro gyroscope using Quality factor and the resonant displacement was proposed. Because the Quality factor has a large error under the high Quality factor condition, it is difficult to analyze the characteristics of the vacuum packaged vibratory micro gyroscopes with the Quality factor. We analyzed mechanical characteristics of gyroscope with the value of Quality factor. We described measurement errors of mechanical characteristics of micro gyroscopes. The measured value of Quality factor is 47532 and error range of Quality factor is from -29.8 % to 73.9 %. The value of resonant displacement is 3.4${\mu}m$ and the measurement error is 2.9 %. From the result of Quality factor degradation and resonant displacement degradation, 1698 days and 1503 days were estimated as Time To Failure (TTF), respectively. The range of estimation error of Quality factor degradation and resonant displacement degradation is calculated from 1246 days to 1832 days and from 1456 days to 1537 days, respectively. We can analyze the characteristics of the vibratory gyroscope using the quality factor when the Quality factor is smaller than 10,000. Also we can analyze that using the resonant displacement when the Quality factor is larger than 10,000.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.172-176
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• 2001

In this paper, a new detection algorithm of faulted voltages under the unbalanced condition and a control algorithm of the instantaneous voltage sag corrector (IVSC) are proposed. To quantify the unbalance under fault conditions, the voltages are decomposed into two balanced three-phase systems using the symmetrical components of positive and negative sequence voltages, which is defined by magnitude factor (MF) and unbalance factor (UF). New control algorithm based on MF and UF values for instantaneous voltage compensation are proposed and verified through the PSCAD/EMTDC simulation and experimental results.

• Journal of Dental Anesthesia and Pain Medicine
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• v.15 no.1
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• pp.25-29
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• 2015

Factor XI deficiency (Hemophilia C) is a very rare autosomal recessive bleeding disorder. Patients with factor XI deficiency do not typically show any spontaneous bleeding or specific symptoms. Sometimes those who have this disorder are identified during special situations such as trauma or surgery. Orthognathic surgery is particularly associated with a high bleeding risk. Therefore, great care must be taken when treating patients with bleeding disorders such as factor XI deficiency. There are a few reports that address the management of patients with bleeding disorders during orthognathic surgery. The current report describes a patient with factor XI deficiency who underwent Le Fort I osteotomy together with bilateral sagittal split osteotomy. The patient's condition was assessed using both rotation thromboelastometry ($ROTEM^{TM}$) and noninvasive measurements of total hemoglobin (SpHb) using Masimo Radical 7 (Masimo Co. CA, USA).