• 한국기계가공학회지
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• 제20권9호
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• pp.11-19
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• 2021

Linear variable differential transformer (LVDT) is a displacement sensor and is commonly used owing to its wide measurement range, excellent linearity, high sensitivity, and precision. To improve the output characteristics of LVDT, a few studies have been conducted to analyze the output using a theoretical method or a finite element method. However, the material properties of the core and the electromagnetic force acting on the core were not considered in the previous studies. In this study, a finite element analysis model was proposed considering the characteristics of the LVDT composed of coils, core, magnetic shell and electric circuit, and the core displacement. Using the proposed model, changes in sensitivity and linear region of LVDT according to changes in process and material parameters were analyzed. The outputs of the LVDT model were compared with those of the theoretical analysis, and then, the proposed analysis model was validated. When the electrical conductivity of the core was high and the relative magnetic permeability was low, the decrease in sensitivity was large. Additionally, an increase in the frequency of the power led to further decrease in sensitivity. The electromagnetic force applied on the core increased as the voltage increased, the frequency decreased, and the core displacement increased.

• 대한한의학회지
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• 제44권4호
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• pp.136-149
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• 2023

Objectives: Facial diagnosis is an important part of clinical diagnosis in traditional East Asian Medicine. In this paper, we proposed a model to quantitatively classify cold sensitivity using a fully automated facial image analysis system. Methods: We investigated cold sensitivity in 452 subjects. Cold sensitivity was determined using a questionnaire and the Cold Pattern Score (CPS) was used for analysis. Subjects with a CPS score below the first quartile (low CPS group) belonged to the cold non-sensitivity group, and subjects with a CPS score above the third quartile (high CPS group) belonged to the cold sensitivity group. After splitting the facial images into train/validation/test sets, the train and validation set were input into a convolutional neural network to learn the model, and then the classification accuracy was calculated for the test set. Results: The classification accuracy of the low CPS group and high CPS group using facial images in all subjects was 76.17%. The classification accuracy by sex was 69.91% for female and 62.86% for male. It is presumed that the deep learning model used facial color or facial shape to classify the low CPS group and the high CPS group, but it is difficult to specifically determine which feature was more important. Conclusions: The experimental results of this study showed that the low CPS group and the high CPS group can be classified with a modest level of accuracy using only facial images. There was a need to develop more advanced models to increase classification accuracy.

• 대한한의학회지
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• 제28권3호통권71호
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• pp.173-182
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• 2007

Objective : To develop an integrated curriculum for acupuncture treatment and pain sensitivity practice, and discuss its usefulness. Method : We established an integrated practice program incorporating acupuncture and pain on physiology perspectives, and measured pain sensitivity at Yin (PC6${\sim}$PC4) and Yang (TE5${\sim}$TE9) meridians before and after the acupuncture treatment. Results : The Yang (39.4${\pm}$23.5) and Yin (46.0${\pm}$25.5) meridians have significantly different degrees of pain sensitivity (n=118, p=0.018). Pain sensitivity was significantly decreased after acupuncture treatment at Yang (54.63${\pm}$28.02/ 40.81${\pm}$29.39) and Yin (56.13${\pm}$27.88/ 38.72${\pm}$25.17) meridians (n=16, p<0.001). Discussion and Conclusion : The difference between the Yin and Yang meridians can be materialized in this integrated practice curriculum model. The effectiveness of this integrated class and suggestions for improvement of integrated curricula were discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.796-801
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• 2002

The goal of this research is the shape design of the valve using a computer simulation. For an analysis a basic mathematical model describing compression cycle is considered as consisting of five sets of coupled equations. These are the volume equation (kinematics), valve dynamic equation (dynamics), ideal gas equation (thermodynamics), Bernoulli equation (fluid dynamics), and dynamic equation of fluid particle based on Helmholtz equation (acoustics). Valve motion is made by the superposition of free vibration modes obtained by the finite element method. That is, the eigenvalues and eigenvectors are the sufficient modeling factors fur the valve in the simulation program. Thus, to design a shape of the valve, shape design sensitivity through chain-ruled derivatives is considered from two sensitivity coefficients, one is the design sensitivity of the capability of compressor with respect to the eigenvalues of the valve, and the other is the design sensitivity of the eigenvalue with respect to the shape change of the valve. In this research, the continuum design sensitivity analysis concepts are used for the latter.

• 한국기계가공학회지
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• 제20권8호
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• pp.11-17
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• 2021

This paper describes the time rate of change of dynamic response of a cantilever beam inserted with a damping element, such as bonding, which is excited under a general force at various locations. A sensitivity analysis was performed in a finite element model to show that two types of second-order algebraic governing equations were used to predict the rate of change of dynamic displacement: one is related to the modal coordinate linked to a physical coordinate, and the other to the design parameter of the time rate of change of displacement. The sensitivity differential equation formulation includes more complicated terms compared with that of the undamped cantilever beam. The sensitivities of the dynamic response were observed by changing the location of the excitation force, displacement extraction, and cross-sectional area of the beam. The analytical results obtained by this suggested theory showed a relatively good agreement when compared with those obtained using the commercial finite element program. The suggested analysis procedure enables the prediction of the response sensitivity for any finite element model of the dynamic system.

• 지질공학
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• 제14권3호
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• pp.287-300
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• 2004

Visual Modflow를 이용하여 터널 굴착 시 터널 내 지하수 유입 량과 영항반경에 영향을 미치는 수리 인자들에 대한 민감도 분석을 수행하였다. 터널의 심도 및 수리전도도의 민감도가 가장 크게 나타났으며, 굴착 후 경과 시간에 따라 민감도의 순위가 달라지는 것으로 분석되었다. 비산출률의 경우 굴착 후 시간이 경과함에 따라 민감도가 지속적으로 증가하는 것으로 나타나 배수형 터널 설계 시 수리전도도와 함께 중요하게 고려되어야 할 변수인 것으로 밝혀졌다. 터널굴착 및 방수 처리 과정을 모사할 수 있는 부정류 모델링 기법을 제시하였으며, 실제 터널 설계 지역에 적용하여 굴착과정에서 발생하는 터널 내 지하수 유입량 주변 지역 지하수계의 변화를 예측하였다. 예측 모델의 결과는 모델 보정을 통하여 설정한 수리 전도도에 매우 민감하므로, 사후 모니터 링을 통한 모델 검증이 요구된다.

• Korean Chemical Engineering Research
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• 제51권1호
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• pp.87-92
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• 2013

미세조류는 바이오연료를 생산하기 위해 필요한 성분인 지방질의 생산성이 우수하기 때문에 바이오연료의 유망한 원료로서 최근 많은 주목을 받고 있다. 본 연구에서는, 이러한 미세조류의 성장 속도와 미세조류 내부의 지방의 함량이 최대가 되도록 하기 위한 목적으로, 미세조류의 성장과 지방의 생성을 설명하는 제일원리(first principle)에 근거한 상미분방정식(ODE) 모델에 대하여 조사하였다. 모델은 6개의 상태변수와 12개의 파라미터로 이루어져 있으며, 미세조류의 성장을 영양분의 흡수와 흡수된 영양분에 의한 성장으로 두 단계로 나누어 설명한 Droop 모델의 가정을 따른다. 본 연구에서는 민감도 분석(Sensitivity analysis)을 위한 최대의 정보를 줄 수 있는 입력 신호를 결정하기 위해 D-optimality criterion을 이용한 최적 입력 설계(Optimal input design)를 수행하였으며, 구하여진 입력 신호를 적용하여 민감도 분석을 수행하여 모델에 좀 더 중요한 파라미터를 결정하였다. 또한 미세조류의 성장속도와 지방의 함량이 최대가 되도록 하기 위하여 모델 예측 제어(MPC)를 수행하였다.

• 제어로봇시스템학회논문지
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• 제10권4호
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• pp.295-303
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• 2004

Previously it has been shown that the all pole systems resulting good time responses can be characterized by so called K-polynomial. The polynomial is defined in terms of the principal characteristic ratio $\alpha_1$ and the generalized time constant $\tau$ . In this paper, Part II presents several sensitivity analyses of such systems with respect to $\alpha_1$ and $\tau$ changes. We first deal with the root sensitivity to the perturbation of $\alpha_1$ . By way of determining the unnormalized function sensitivity, both time response sensitivity and frequency response sensitivity are derived. Finally, the root sensitivity relative to $\tau$ change is also analyzed. These results provide some useful insight and background theory when we select of and l to compose a reference model of which denominator is a K-polynomial, which is illustrated by examples.

• Communications for Statistical Applications and Methods
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• 제22권6호
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• pp.589-598
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• 2015

In longitudinal studies missing data are common and require a complicated analysis. There are two popular modeling frameworks, pattern mixture model (PMM) and selection models (SM) to analyze the missing data. We focus on the PMM and we also propose Bayesian pattern mixture models using generalized linear mixed models (GLMMs) for longitudinal binary data. Sensitivity analysis is used under the missing not at random assumption.

• Advances in nano research
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• 제1권1호
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• pp.29-34
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• 2013

The conversion of mechanical energy into electrical energy at nanoscale using piezoelectric nanowire arrays has been in detail shown by deflection of nanowires. Recently it has performed an analytical model, both at classical and at quantum level, for describing the most important quantities concerning transport phenomena; the model predicts interesting peculiarities, as high initial charge diffusion in nanodevices constituting by nanowires and permits also in particular to deduce interesting informations about the devices sensitivity, focusing on the correlation between sensitivity and high initial diffusivity of these materials at nanometric level.