• Biomolecules & Therapeutics
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• 제26권4호
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• pp.380-388
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• 2018

Neural stem cells (NSCs) have the ability to self-renew and differentiate into multiple nervous system cell types. During embryonic development, the concentrations of soluble biological molecules have a critical role in controlling cell proliferation, migration, differentiation and apoptosis. In an effort to find optimal culture conditions for the generation of desired cell types in vitro, we used a microfluidic chip-generated growth factor gradient system. In the current study, NSCs in the microfluidic device remained healthy during the entire period of cell culture, and proliferated and differentiated in response to the concentration gradient of growth factors (epithermal growth factor and basic fibroblast growth factor). We also showed that overexpression of ASCL1 in NSCs increased neuronal differentiation depending on the concentration gradient of growth factors generated in the microfluidic gradient chip. The microfluidic system allowed us to study concentration-dependent effects of growth factors within a single device, while a traditional system requires multiple independent cultures using fixed growth factor concentrations. Our study suggests that the microfluidic gradient-generating chip is a powerful tool for determining the optimal culture conditions.

• Structural Engineering and Mechanics
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• 제19권2호
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• pp.231-236
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• 2005

This study considers the buckling of orthotropic cylindrical thin shells with material nonhomogeneity in the thickness direction, under torsion, which is a power function of time. The dynamic stability and compatibility equations are obtained first. Applying Galerkin's method then applying Ritz type variational method to these equations and taking the large values of loading parameters into consideration, analytic solutions are obtained for critical parameter values. Using those results, the effects of the periodic and power variations of Young's moduli and density, ratio of Young's moduli variations, loading parameters variations and the power of time in the torsional load expression variations are studied via pertinent computations. It is concluded that all these factors contribute to appreciable effects on the critical parameters of the problem in question.

• 한국문헌정보학회지
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• 제50권2호
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• pp.271-287
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• 2016

본 연구는 이용자 중심의 도서관장애인서비스 품질요인을 실증적으로 고찰하고자 하였다. 품질요인의 실증적인 고찰을 위해 기존 도서관서비스의 품질 측정도구와 장애인서비스 기준 및 지침을 분석하여 총 9개의 품질요인을 도출하였으며, 이 요인을 활용하여 설문조사와 사례의 질적 평가가 이루어졌다. 조사 결과, 공공도서관 장애인서비스에서 가장 핵심적이며, 또한 상대적으로 취약한 품질요인은 시설, 장서, 직원 등 기본적인 도서관 자원의 영역으로 나타났다. 또한 도서관장애인서비스 우수사례를 분석한 결과 독서문화프로그램과 정보서비스 품질요인에 강조를 두고 있음이 조사되었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.121-124
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• 2004

The purpose of this study is to define the optimized layer pattern of composite wind turbine blade by using a commercial FEM program and to perform the fatigue test of T-Bolt. FEM analysis is done by using a PATRAN and ABAQUS to get a information about stress distribution ,critical deformation shape and get a critical load factor in local buckling analysis. As a result of the linear and nonlinear structural analysis, layer pattern of blade was optimized. T-Bolt is a connecting part of wind turbine blade and rotor hub, therefore T-bolt is cirtical part of wind turbine blade. T-bolt fatigue test is conducted to get a information of life cycle of T-bolt. The test is done by using a hydraulic actuator system

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2001년도 춘계학술대회 논문집
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• pp.109-113
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• 2001

The purpose of this paper is to propose an analytical method for evaluating user satisfaction of Internet websites using the structural equation model(SEM). This paper is intended to identify critical evaluation factors of user satisfaction for websites to determine criteria for evaluating the websites, and use the criteria to develop a SEM model for quantitatively evaluation of each factors' effects of user satisfaction. The SEM model used 2 variables of usability and good-looks for the evaluation factors of websites user satisfaction and each factors have 4 sub evaluation criteria, 3 portal sites were evaluated to construct the SEM model, and 155 subjects participated the website evaluation using the walk-through and face-to-face survey method. Analysis results showed that the SEM model was statistically significant for all the 3 websites evaluated. Both the usability and good-looks two factors also showed significant effects to user satisfaction of websites and have positive correlation. The user satisfaction was more effected by the usability factor than good-looks, and the simplification and harmonization were the most critical sub-factors of the usability and good-looks.

• 한국소음진동공학회논문집
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• 제12권5호
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• pp.380-388
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• 2002

This paper describes the optimum design for low-pressure steam turbine rotor of 1,000 MW nuclear power plant by using a combined genetic algorithm, which uses both a genetic algorithm and a local concentrate search algorithm (e.g. simplex method). This algorithm is not only faster than the standard genetic algorithm but also supplies a more accurate solution. In addition, this algorithm can find the global and local optimum solutions. The objective is to minimize the resonance response (Q factor) and total weight of the shaft, and to separate the critical speeds as far from the operating speed as possible. These factors play very important roles in designing a rotor-bearing system under the dynamic behavior constraint. In the present work, the shaft diameter, the bearing length, and clearance are used as the design variables. The results show that the proposed algorithm can improve the Q factor and reduce the weight of the shaft and the 1st critical speed.

• Journal of Welding and Joining
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• 제20권2호
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• pp.116-124
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• 2002

The fatigue life is predicted on tensile-shear spot weldment made from Al-Mg alloy sheet with thickness of 0.8mm using Mitchell's method and uniform material law by $B{\ddot{a}}umel$ and Seeger based on local strain approach. The fatigue properties of critical HAZ region are estimated from the tensile property using simple hardness method. To predict the fatigue life of spot weldment, the local stresses and strains at the potential critical region are estimated by Neuber's rule. The predicted fatigue life based on uniform material law using HAZ's material properties provides good results within a factor of 3, conservatively.

• Structural Engineering and Mechanics
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• 제62권1호
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• pp.65-77
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• 2017

The free vibration analysis of fluid conveying Timoshenko pipeline with different boundary conditions using Differential Transform Method (DTM) and Adomian Decomposition Method (ADM) has not been investigated by any of the studies in open literature so far. Natural frequencies, modes and critical fluid velocity of the pipelines on different supports are analyzed based on Timoshenko model by using DTM and ADM in this study. At first, the governing differential equations of motion of fluid conveying Timoshenko pipeline in free vibration are derived. Parameter for the nondimensionalized multiplication factor for the fluid velocity is incorporated into the equations of motion in order to investigate its effects on the natural frequencies. For solution, the terms are found directly from the analytical solution of the differential equation that describes the deformations of the cross-section according to Timoshenko beam theory. After the analytical solution, the efficient and easy mathematical techniques called DTM and ADM are used to solve the governing differential equations of the motion, respectively. The calculated natural frequencies of fluid conveying Timoshenko pipelines with various combinations of boundary conditions using DTM and ADM are tabulated in several tables and figures and are compared with the results of Analytical Method (ANM) where a very good agreement is observed. Finally, the critical fluid velocities are calculated for different boundary conditions and the first five mode shapes are presented in graphs.

• 중환자간호학회지
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• 제13권2호
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• pp.36-44
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• 2020

Purpose : The person-centered care is essential for better patient outcome. This study was conducted to identify the factors affecting to the person-centered care among intensive care unit (ICU) nurses. Method : This study was cross sectional survey, and the participants included 107 ICU nurses who provided a written consent to participate in the study. Using a structured survey, nurse's compassion fatigue, compassion satisfaction, and person-centered care among ICU nurses were assessed. The collected data were analyzed using t-test, ANOVA, and Pearson correlation test with SPSS 23.0 program. The factors affecting patient-centered care were analyzed using multiple regression. Results : According to the multiple regression analysis, education level, perceived caregivers need priority and compassion satisfaction were positive affecting factors to the person-centeredness of ICU nurses. Conclusion : In conclusion, the compassion satisfaction was an affecting factor to the person-centered care, however compassion fatigue didn't affect to the person-centered care among ICU nurses. Therefore, the strategy enhancing compassion satisfaction among ICU nurses will be needed to increase person centeredness.

• 산업경영시스템학회지
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• 제39권2호
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• pp.119-128
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• 2016

Use of ICT in Government has ability to improve service delivery to its citizens, and yet many developing countries have lagged behind in the implementation of e-Government. Many e-Government initiatives also failed to achieve their objectives in developing countries. This paper therefore aims to identify critical failure or success factors in Kenya, using Heeks' Factor Model. A survey questionnaire was developed and data were collected and analyzed from officials and interested citizens. The analysis results enabled to highlight seven specific success and failure factors, and their constituent elements in Kenya. The Kenyan overall e-Government implementation score belongs to the Zone of Improvement (3.52 of total 5.0), which means partial success or failure. The enablers of e-Government projects are good strategy formulation, and internal and external drive, whereas main failures of e-Government are weak ICT infrastructure. The areas for improvement are project management, design, competencies and funding. Data analysis highlights both strengths and weaknesses for each factor or variable. In particular, Kenyan government excels at the drive for change by top to bottom government officers as well as external stakeholders, while the government officers who are using e-Government are satisfied with the availability of vision, strategy and plan of e-Government implementation. Both technologies and e-transactions laws were the worst of all the variables in e-Government implementation. Two areas should be improved using immediate corrective action. In-depth study reveals that government officers and citizens can't fully use their laptop and mobile devices due to the lack of both ICT network and its operating technology, and legal system associated with the transaction of business information. Finally, the study ends up with recommendations for policy makers to shape the future of e-Government system in both developing and developed countries.