• Honam Mathematical Journal
• /
• v.44 no.3
• /
• pp.402-418
• /
• 2022

Noise is a fundamental factor to increased validity and regularity of spike propagation and neuronal firing in the nervous system. In this paper, we examine the stochastic version of the Izhikevich-FitzHugh neuron dynamical model. This approach is based on techniques presented by Luo and Guo, which provide a general framework for the bifurcation and stability analysis of two dimensional stochastic dynamical system as an Itô averaging diffusion system. By using largest lyapunov exponent, local and global stability of the stochastic system at the equilibrium point are investigated. We focus on the two kinds of stochastic bifurcations: the P-bifurcation and the D-bifurcations. By use of polar coordinate, Taylor expansion and stochastic averaging method, it is shown that there exists choices of diffusion and drift parameters such that these bifurcations occurs. Finally, numerical simulations in various viewpoints, including phase portrait, evolution in time and probability density, are presented to show the effects of the diffusion and drift coefficients that illustrate our theoretical results.

• Journal of Animal Reproduction and Biotechnology
• /
• v.38 no.1
• /
• pp.26-31
• /
• 2023

Chicken embryonic stem (ES) cells have great potential and provide a powerful tool to investigate embryonic development and to manipulate genetic modification in a genome. However, very limited studies are available on the functional characterization and robust expansion of chicken ES cells compared to other species. Here, we have developed a method to generate chicken embryonic stem cell-like cells under pluripotent culture conditions. The chicken embryonic stem cell-like cells were cultivated long-term over several passages of culture without loss of pluripotency in vitro and had the specific expression of key stem cell markers. Furthermore, they showed severe changes in morphology and a significant reduction in pluripotent genes after siRNA-mediated NANOG knockdown. Collectively, these results demonstrate the efficient generation of chicken embryonic stem cell-like cells from EGK stage X blastoderm-derived singularized cells and will facilitate their potential use for various purposes, such as biobanking genetic materials and understanding stemness in the fields of animal biotechnology.

• International conference on construction engineering and project management
• /
• 2007.03a
• /
• pp.810-819
• /
• 2007

Usually the status of a bridge is determined by its structural capability and material strength. Consequently a lot of researchers have studied the failure, the fatigue, and the deterioration of the structure in terms of the structural function of a bridge. However, the overall performance of a bridge may be affected simply by the damage of one of its components. Therefore this study utilized a systematic classification and statistical analysis based on the existing bridge inspection data collected in Taiwan to reach the following goals: (1) assess the performance distribution and deterioration rate for bearing and expansion joint of bridge; (2) find out the right time to do the preventive and essential maintenance for the component of bridge with an empirical method, and to decide what time and which component of a bridge will receive preventive maintenance or regular maintenance.

• Annual Conference of KIPS
• /
• 2009.11a
• /
• pp.179-180
• /
• 2009

본 논문은 웨어러블 플랫폼 구성 기술로써 e-Textile Fabric Area Network (e-FAN) 시스템을 소개하고, e-FAN 시스템에서의 브릿지 노드를 이용한 네트워크 확장 방법을 제안한다. E-FAN 은 직물 소재의 제품에 센서, 엑츄에이터, 프로세서 등의 다양한 정보 처리 유닛이 전도성사로 연결되는 구성되는 네트워크이다. 본 논문은 이러한 e-FAN 시스템에서의 e-FAN 브릿지 노드 (e-FAN Bridge Node; eFANBN)을 활용한 네트워크 확장 방법을 제시한다. E-FAN 브릿지 노드를 활용한 네트워크 확장 방법을 통하여 다양한 종류의 전도성사를 통신 매질로 하는 네트워크 세그먼트를 통합하여 내고장성을 지원하는 네트워크로 확장한다.

• Progress in Superconductivity and Cryogenics
• /
• v.12 no.4
• /
• pp.36-40
• /
• 2010

In this paper, a noble method for rapid cooldown of pulse tube refrigerator (PTR) was proposed and experimentally investigated. An orifice pulse tube refrigerator generates refrigeration effect by expansion PV work at the cold-end, and its amount is affected by the orifice valve opening. There exists the optimum valve opening for maximum cooling capacity and it varies as cold-end temperature. It is verified from simulation results using isothermal model that the optimum valve opening increases as the cold-end temperature increases. In the experiments, a single stage orifice pulse tube refrigerator is fabricated and tested. The fabricated PTR shows 97.5 K of no-load temperature and 10 W at 110 K of cooling capacity with the fixed orifice valve opening. From experiments, the initial cooldown curve with four cases of valve opening control scenario are obtained. And it is experimentally verified that the initial cooldown time can be reduced through the control of orifice valve opening.

• Journal of Korean Port Research
• /
• v.8 no.1
• /
• pp.17-22
• /
• 1994

The wave interaction with flexible membrane such as PVC and fabrics is studied to prove its applicability to portable breakwaters. To obtain the wave exciting force acting on flexible membrane, eigen-function expansion method is employed. The effect of flexible is involved in body boundary condition in which x-directional displacement of membrane is obtained by solving the linear membrane equation. Displacement of membrane is assumed to be small compared to wavelength, therefore the tensile force of membrane remains constant. As the numerical examples, transmission and reflection coefficients according to the change of tensile forces are investigated. The hydrodynamic force on membrane, the dynamic tension in the mooring lines and the vertical displacement profile of membrane are also calculated. It is suggested that the flexible membrane can be used to engineering material for the future coastal/ocean applications.

• Annual Conference of KIPS
• /
• 2011.04a
• /
• pp.979-981
• /
• 2011

In this paper, a new scheme to improve both the capacity and distortion performance for error-prediction method is proposed. For every triangle mesh, two vertices were selected to predict the rest vertex, and the prediction error distances which were vertical and paralleled to the edge between these two vertices would be used to embed two units of secret date amount. We sort the meshes before embedding according to predicted error in order to decrease the distortion. Experiment results show that our approach increase the capacity and decrease the distortion as compared to the original algorithm.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.216-217
• /
• 2022

After the financial crisis, the spread of indirect employment, which is an outsourcing method, is gradually becoming common in our society, and the risk of harm is relatively high or the proportion of simple jobs is high. Simple workers have a higher proportion of non-manufacturing industries such as the service industry, and production workers are intensively used in the manufacturing industry. In Article 63 of the Occupational Safety and Health Act, contractors must take necessary safety and health measures. In addition, due to the expansion of the scope of contracts under the Occupational Safety and Health Act, it is necessary to review the appropriateness of industrial accident prevention measures and implementation standards.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.219-220
• /
• 2021

As the area where stone is used in buildings increases, the amount of stone processing increases, and the amount of dust generated in the processing process is increasing, but interest in this is insignificant. In addition, as a result of investigating the dust generated in the dry process, the proportion of SiO2 is about 70%, so there is a concern about the risk of pneumoconiosis caused by breathing. Therefore, it is judged that it is urgent to collect it at the source to prevent damage to workers and environmental pollution.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.69-70
• /
• 2022

In this study, although the diversity of tiles in the expanding housing market is increasing, cases of defects in building interior tiles that occur due to limitations of existing tile adhesives and construction methods were collected, and among them, the relationship between the coefficient of thermal expansion and the occurrence of defects was analyzed. One-way ANOVA was used for the analysis method, and as a result of the analysis, it was analyzed that the difference between groups in temperature difference and humidity difference by defect type was significant.