• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.644-645
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• 2007

In this paper, the eigenvalue sensitivity analysis algorithm in discrete systems by the RCF method are presented and applied to the power system including TCSC. The RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of dominant oscillation modes after periodic switching operations. These simulation results are very different from those of the conventional continuous system analysis method such as the state space equation method

• Tuberculosis and Respiratory Diseases
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• 제64권2호
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• pp.80-86
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• 2008

연구배경: 폐확산능을 해석하는 데 필요한 정상예측식으로는 한국인을 대상으로 하여 박 등이 개발한 식(박 식)이 있으나 아직 외국 정상예측식을 많이 사용하고 있다. 이에 국내에서 많이 사용하는 외국 정상예측식인 Burrows 식과 박 식의 임상적 유용성과 정확성을 비교하고자 하였다. 방법: 1. 임상적 유용성 연구; 2006년 7월부터 12월까지 6개월간 폐확산능검사를 시행한 환자 중 두 식을 각각 정상예측식으로 적용하였을 때 폐확산능 해석이 다른 276명(대상군 A)을 대상으로 하였다. 대상군 A에게 두 식을 각각 적용하였을 때 폐확산능 해석과 임상적 판단과의 일치도를 비교하여 임상적 유용성을 평가하였다. 2. 간질성폐질환 진단의 정확성 비교; 2001년부터 2006년까지 폐조직검사를 시행하여 확진된 간질성폐질환군과 서울아산병원에서 모집한 정상군을 대상으로 하여 정상예측식으로 두 식을 각각 적용하였을 때 폐확산능 해석의 정확도를 비교하였고, 두 식이 차이가 나는지 맥니머의 카이스퀘어 검정을 하였다. 결과: 1. 임상적 판단과의 일치도 비교; 276명을 임상정보를 토대로 폐확산능을 예측하여 분류한 결과 정상 54명, 감소 220명, 불분명이 2명이었다. 예측식으로 박 식과 Burrows 식을 적용하였을 때 임상적 판단과 일치하는 환자는 각각 78%와 22%이었다(p<0.001). 2. 간질성폐질환 진단의 정확성 비교; 박 식은 민감도 90.1%, 특이도 100%이었고 Burrows 식은 민감도 64.2%, 특이도 100%로 민감도가 통계학적으로 유의하게 박 식이 높았다(p<0.001). 결론: 우리나라 정상예측식인 박 식이 외국 정상예측식인 Burrows 식을 정상예측식으로 적용하는 것보다 임상적 유용성이나 간질성폐질환 진단의 민감도에서 더 우월하였다. 향후 폐확산능검사의 정상예측식으로 박 식을 사용해야 할 것으로 사료된다.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2245-2252
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• 2002

Design sensitivity analysis scheme is proposed in an elasto -plastic finite element method with explicit time integration using a direct differentiation method. The direct differentiation is concerned with large deformation, the elasto-plastic constitutive relation, shell elements with reduced integration and the contact scheme. The design sensitivities with respect to the process parameter are calculated with the direct analytical differentiation of the governing equation. The sensitivity results obtained from the present theory are compared with that obtained by the finite difference method in a class of sheet metal forming problems such as hemi-spherical stretching and cylindrical cup deep-drawing. The result shows good agreement with the finite difference method and demonstrates that the preposed sensitivity calculation scheme is a pplicable in the complicated sheet metal forming analysis and design.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.746-752
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• 2001

Design sensitivity analysis for nonlinear structural problems has been emerged in the last decade as a glowing area of engineering research. As a result, theoretical formulations and computational algorithms have already developed for design sensitivity of nonlinear structural problems. There is not enough research for practical nonlinear problems using multi-element, due to difficulties of implementation into FEA. Therefore, nonlinear response analysis for stiffened shell which consists of Mindlin plate and Timoshenko beam, was considered. Specially, it presents the backward-Euler method which is adopted to describe an exact yield state in the stress computation procedure. Then, design sensitivity analysis of nonlinear structures, particularly elasto-perfectly-plastic structure, is developed using direct differentiation method. The accuracy of the developed sensitivity analysis was compared with the central finite difference method. Finally, on the basis of above results, design improvement for stiffened shell is suggested.

• 한국보육지원학회지
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• 제14권6호
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• pp.1-18
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• 2018

Objective: The purpose of this study was to investigate relationships among child care teachers' role conflict, organizational commitment and teacher's sensitivity. It also aimed to test the mediating effect of organizational commitment on the pathway from child care teachers' role conflict on teacher's sensitivity. Methods: A self-report survey was conducted on 301 child care teachers in Chungbuk. Descriptive, means, standard deviations, correlations using SPSS 18.0, and Structural Equation Modeling using AMOS 18.0 were all conducted in order to analyze the collected data. Results: The results indicated that child care teachers' role conflict and organizational commitment had significant direct effects on teacher's sensitivity. This study also confirmed the significant mediating role of organizational commitment on the pathway from child care teachers' role conflict to sensitivity. Conclusion/Implications: The significance of role conflict and organizational commitment suggests that the integration of individuals with less conflict and more dedication will contribute more qualitative child care services by improving sensitive interactions with young children.

• Geosystem Engineering
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• 제21권6호
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• pp.335-343
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• 2018

Alkali-surfactant polymer flooding has become an important technique to improve oil recovery following the development of oil fields while the function of emulsification in enhanced oil recovery is rarely considered in the existing mathematical model for numerical simulation. In this paper, the mechanism of improving the recovery of the emulsification was analyzed in ASP flooding, and a relatively perfect mathematical model with deep filtration-theory was established, in which oil-water volume equation, saturation equation, viscosity equation, and permeability reduction equation are included. The new model is used to simulate the actual block of an oil field; the simulated results of the new model and an old model without considering the emulsification are compared with the actual well history. It is found that new model which is easy to be realized in numerical simulation has a high precision fitting, and the effect of adding oil and decreasing water is obvious. The sensitivity of emulsification was analyzed, and the results show that the water reducing funnel becomes wider and the rate of water cut decreases rapidly with the increase of emulsifying capacity, and then the rate of recovery slows down. The effect of increasing oil and decreasing water is better, and the degree of recovery increases. The emulsification of the ASP flooding is maintained at a moderate level, which corresponds to ${\Phi}=0.2$ in the new model, and the emulsification is applied to realize the general mathematical quantitative description, so as to better guide the oilfield development.

• 소성∙가공
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• 제31권4호
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• pp.200-206
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• 2022

The finite element analysis is one of the representative methods for predicting the materials behavior for experiments that are difficult to perform empirically. Constitutive equations are essential for reducing computation time and sharing data because they enable finite element analysis simulations through simple formulae. However, it is difficult to derive accurate flow curves for all materials as most constitutive equations are not formulated based on their physical meaning. Also, even if the constitutive equation is a good representation of the flow curve to the experimental results, some fundamental issues remain unresolved, such as the effect of mesh size on the calculation results. In this study, a new constitutive equation was proposed to predict various materials by modifying the combined Swift-Voce model, and the calculation results with various mesh sizes were compared to better simulate the experimental results.

• 전자공학회논문지SC
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• 제48권1호
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• pp.1-8
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• 2011

MR 센서에 의해 지구자기장의 세기를 측정하여 방위각을 결정하는 전자 Compass의 정밀도는 MR센서 및 OP-Amp.의 온도 Drift, DC Offset등 소자에 의한 오차, 측정주변 자성체에 의한 자기장의 왜곡, 및 Compass Tilt에 의한 오차 등의 영향을 받는다. 본 연구에서는 Set/Reset Pulse 방법에 의해 MR 센서 및 OP-Amp의 온도 Drift 및 DC Offset에 의한 오차를 해결하였고, 주변 자성체에 의한 자기장의 왜곡에 의한 오차를 Hard-Iron Calibration 루틴 수행에 의해 보상하였으며, Compass Tilt에 의한 오차를 Euler Rotational Equation에 의해 보상할 수 있는 3축 MR 센서 및 3축 Accelerometer를 기반으로 하는 전자 Compass 를 설계하였다. 특히 이와 샅이 설계한 전자 Compass를 가지고 3측 MR 센서의 서로 다른 Sensitivity와 OP-Amp.의 서로 다른 Gain등을 규준화하기 위한 Sensitivity Calibration 루틴 수행 시 Tilt의 발생으로 야기되는 오차를 정량적으로 분석하였으며, 이를 바탕으로 $1^{\circ}$정도(精度) Compass를 설계할 수 있었다.

• 한국가족관계학회지
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• 제22권2호
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• pp.51-69
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• 2017

Objectives: The purpose of this study was to examine the associations and paths among parenting behaviors, cyber delinquency, and moral sensitivity in adolescents to reduce and prevent cyber delinquency. Method: The data was collected by a survey for 270 students from a middle school and a high school in G city. The valid 262 cases were analyzed by frequency, descriptive analysis with SPSS 18.0 and tested by structural equation model by using AMOS 18.0 program. Results: Results showed that 1) 'control' among the parenting behaviors has positive effects on the cyber delinquency in adolescents, 2) 'intimacy and rationality' among the parenting behaviors has positive impacts on the moral sensitivity, 3) it shows that moral sensitivity has negative effects on the cyber delinquency in adolescents, and 4) bootstrapping test for indirect effect of moral sensitivity was verified significantly. We founded the full mediation of moral sensitivity and the path of 'intimacy and rationality' to cyber delinquency through moral sensitivity. Conclusions: The results implied 1) provision of the parent education and program for parents and newlyweds to learn positive parenting behaviors and 2) application of moral education to develop moral sensitivity of adolescents in schools and communities.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.2114-2116
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• 2004

센서의 소형화 되는 추세에 전극 면적은 sensitivity의 중요한 요인이다. 본 연구에서는 콜레스테롤을 측정하기 위해 각각 planar 전극과 porous 전극에 효소 고정화 방법으로 covalent binding인 silanization 공정을 이용하여 전극 면적에 따른 전기화학적 감도를 비교하였다. Handles-Sevcik equation을 이용하여 전극 면적을 구한 결과 planar 전극의 경우 0.1608 $cm^2$, porous 전극의 경우 0.5054 $cm^2$로 porous 전극 면적이 planar전극에 비해 약 3.1배 증가하였다. 또, planar 센서의 sensitivity는 0.08567 ${\mu}A/mM{\cdot}cm^2$이고 porous 센서의 sensitivity는 planar sensor에 비해 약 3.1배 증가한 0.2656 ${\mu}A/mM{\cdot}cm^2$였다. 따라서 porous sensor의 sensitivity의 증가는 전극 면적의 증가에 따른 것이라고 할 수 있다.