• 한국진공학회지
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• 제21권2호
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• pp.69-77
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• 2012

전자기장을 포함한 대부분의 물리학적 시스템이 벡터 미분 연산자들로 기술되며 또한 벡터연산을 통하여 계산된다. 그러므로 이들 벡터장들이 유전 및 자성물질 시스템들과 상호작용할 때 물리적 체계를 기술하고 계산하려면 정확한 전자기 벡터장의 지식체계를 이해할 필요가 있다. 그런데 이들 대부분 추상적 개념들을 직관적으로 이해하기에는 쉽지 않기 때문에 이들 추상적 개념의 시각화 표현 작업은 오늘날 지식정보화 수행과정에서 매우 중요한 과제의 하나다. 우리는 전자기학 체계를 구성하는 가장 기본적인 벡터장: $\vec{E}=-\vec{\nabla}_{\varphi}$, $\vec{D}={\epsilon}\vec{E}$, $\vec{\nabla}{\times}\vec{A}$, $\vec{B}={\mu}\vec{H}$, $\vec{B}={\mu}_0(\vec{\nabla}_{\varphi}{^*}+\vec{M})$들의 가시화 시뮬레이션을 Mathematica 프로그램으로 작성하여 추상적인 전자기벡터장의 시각화 모델을 제시하였다. 이 시뮬레이션을 전자기 벡터장의 물리학적 지식체계를 탐구해 가는 기본 플랫폼으로 활용할 수 있다.

• Journal of Power Electronics
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• 제17권4호
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• pp.972-982
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• 2017

The Park's vector of stator current is a popular technique for the detection of induction motor faults. While the detection of the faulty condition using the Park's vector technique is easy, the classification of different types of faults is intricate. This problem is overcome by the Multiple Park's Vector (MPV) approach proposed in this paper. In this technique, the characteristic fault frequency component (CFFC) of stator winding faults, rotor winding faults, unbalanced voltage and bearing faults are extracted from three phase stator currents. Due to constructional asymmetry, under the healthy condition these characteristic fault frequency components are unbalanced. In order to balanced them, a correction factor is added to the characteristic fault frequency components of three phase stator currents. Therefore, the Park's vector pattern under the healthy condition is circular in shape. This pattern is considered as a reference pattern under the healthy condition. According to the fault condition, the amplitude and phase of characteristic faults frequency components changes. Thus, the pattern of the Park's vector changes. By monitoring the variation in multiple Park's vector patterns, the type of fault and its severity level is identified. In the proposed technique, the diagnosis of faults is immune to the effects of unbalanced voltage and multiple faults. This technique is verified on a 7.5 hp three phase wound rotor induction motor (WRIM). The experimental analysis is verified by simulation results.

• 생명과학회지
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• 제23권2호
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• pp.290-298
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• 2013

Mycobacterium 속은 Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium bovis와 같은 동물과 인체에 병원성을 나타내는 세균 종을 다수 포함하고 있다. 이들의 숙주에서의 생존과 병원성에 관한 유전학적 정보를 확보하는 것은 매우 중요하지만, 효과적인 유전학적 도구가 부족하였기 때문에 이들에 관한 연구가 미비하였다. 따라서 mycobacteria의 연구를 위한 분자생물학적 실험 도구로서 다양한 기능성 vector들이 고안되었고, 이러한 기능성 vector의 개발은 실질적으로 mycobacteria에서의 연구 효과를 증진시켰다. 본 연구에서는 Mycobacterium smegmatis에 적용 가능하고 기존에 제시되었던 mycobacteria 연구에 있어서의 한계점을 극복하기 위한 노력의 일환으로, 기능성 vector인 temperature-sensitive replication origin (TSRO)과 counterselectable marker로 levansucrase를 암호화하는 sacB 유전자를 포함하는 suicide vector pKOTs, chromosomal DNA로 site-specific recombination을 통해 삽입되는 lacZ transcriptional fusion vector pMV306lacZ, 그리고 TSRO를 가지는 minitransposon vector pTnMod-OKmTs를 개발하였다. 이 vector들은 실질적으로 M. smegmatis에서 효과적으로 작동하는 것이 확인되었으며 목적으로 하는 실험 결과 도출 가능성 또한 보여주었다. 따라서 이들 vector는 앞으로의 mycobacteria에 대한 효과적인 연구 기반이 될 것으로 기대된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2594-2599
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• 2003

We consider some problems of the Modified SPRT(Sequential Probability Ratio Test) method for fault detection and isolation of inertial redundant sensor systems and propose an Advanced SPRT method to solve the problems of the Modified SPRT method. One problem of the Modified SPRT method to apply to inertial sensor system comes from the effect of inertial sensor errors such as misalignment, scale factor error and sensor bias in the parity vector, which make the Modified SPRT method hard to be applicable. The other problem is due to the correlation of parity vector components which may induce false alarm. We use a two-stage Kalman filter to remove effects of the inertial sensor errors and propose the modified parity vector and the controlled parity vector which removes the effect of correlation of parity vector components. The Advanced SPRT method is derived form the modified parity vector and the controlled parity vector. Some simulation results are presented to show the usefulness of the Advanced SPRT method to redundant inertial sensor systems.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.236-248
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• 2017

A direct stator flux vector control scheme in discrete-time domain is proposed in this paper for the interior permanent magnet synchronous motor (IPMSM) drive to remove the proportional-integral (PI) controller from the direct torque control (DTC) scheme applied to IPMSM and to obtain faster dynamic response and lower torque ripple output. The output of speed outer loop is used as the desired torque angle instead of the desired torque in the proposed scheme. The desired stator flux vector in dq coordinate is calculated with a given amplitude. The state-space equations in discrete-time for IPMSM are established, the actual stator flux vector is estimated in deadbeat manner by a full-order state observer, and then the closed-loop control is achieved by the pole placement. The stator flux error vector is utilized to calculate the reference stator voltage vector. Extracting the angle position and amplitude from the estimated stator flux vector and estimating the output torque are eliminated for the direct feedback control of the stator flux vector. The proposed scheme is comparatively investigated with a PI-SVM DTC scheme by experiment results. Experimental results show the feasibility and advantages of the proposed control scheme.

• 대한수학회보
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• 제52권5호
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• pp.1535-1547
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• 2015

A vector field on a Riemannian manifold (M, g) is called concircular if it satisfies ${\nabla}X^v={\mu}X$ for any vector X tangent to M, where ${\nabla}$ is the Levi-Civita connection and ${\mu}$ is a non-trivial function on M. A smooth vector field ${\xi}$ on a Riemannian manifold (M, g) is said to define a Ricci soliton if it satisfies the following Ricci soliton equation: $$\frac{1}{2}L_{\xi}g+Ric={\lambda}g$$, where $L_{\xi}g$ is the Lie-derivative of the metric tensor g with respect to ${\xi}$, Ric is the Ricci tensor of (M, g) and ${\lambda}$ is a constant. A Ricci soliton (M, g, ${\xi}$, ${\lambda}$) on a Riemannian manifold (M, g) is said to have concircular potential field if its potential field is a concircular vector field. In the first part of this paper we determine Riemannian manifolds which admit a concircular vector field. In the second part we classify Ricci solitons with concircular potential field. In the last part we prove some important properties of Ricci solitons on submanifolds of a Riemannian manifold equipped with a concircular vector field.

• Journal of Power Electronics
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• 제18권2호
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• pp.445-455
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• 2018

A novel algorithm is proposed to regulate the neutral point potential in neutral point clamped three-level inverters. Oscillations of the neutral point potential and an unbalanced dc-link voltage cause distortions of the output voltage. Large capacitors, which make the application costly and bulky, are needed to eliminate oscillations. Thus, the algorithm proposed in this paper utilizes the finite-control-set model predictive control and the multistage medium vector to solve these issues. The proposed strategy consists of a two-step prediction and a cost function to evaluate the selected multistage medium vector. Unlike the virtual vector method, the multistage medium vector is a mixture of the virtual vector and the original vector. In addition, its amplitude is variable. The neutral point current generated by it can be used to adjust the neutral point potential. When compared with the virtual vector method, the multistage medium vector contributes to decreasing the regulation time when the modulation index is high. The vectors are rearranged to cope with the variable switching frequency of the model predictive control. Simulation and experimental results verify the validity of the proposed strategy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.110-113
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• 2000

In general, speed control method of the elevator system has used motor pole change type or motor primary voltage control type. But it will change to vector control type in order to increase it's reliability, riding comfort and decrease material cost. It is the conception of vector control type in order to increase it's reliability, riding comfort and decrease material cost. It is the conception of vector control that primary current of the induction motor be controlled independently with magnetizing current(field current of DC motor) and torque current(armature current of DC motor). In this paper, by analyzing the effect of the time constant variation of rotor of the induction motor on the slip frequency type indirect vector control, a drive system for the motor will be constructed using a fuzzy slip frequency type indirect vector controller with fuzzy control method for estimating the vector time constant in the slip frequency type indirect vector control. The goal of this study is to enabling even more efficient speed control by constructing on elevator driver based on the newly developed drive system.

• Structural Engineering and Mechanics
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• 제4권2호
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• pp.139-148
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• 1996

Vector algorithms and the relative importance of the four basic modules (computation of element stiffness matrices, assembly of the global stiffness matrix, solution of the system of linear simultaneous equations, and calculation of stresses and strains) of a finite element computer program for inelastic analysis of reinforced concrete shells are presented. Performance of the vector program is compared with a scalar program. For a cooling tower problem, the speedup factor from the scalar to the vector program is 34 for the element stiffness matrices calculation, 25.3 for the assembly of global stiffness matrix, 27.5 for the equation solver, and 37.8 for stresses, strains and nodal forces computations on a Gray Y-MP. The overall speedup factor is 30.9. When the equation solver alone is vectorized, which is computationally the most intensive part of a finite element program, a speedup factor of only 1.9 is achieved. When the rest of the program is also vectorized, a large additional speedup factor of 15.9 is attained. Therefore, it is very important that all the modules in a nonlinear program are vectorized to gain the full potential of the supercomputers. The vector finite element computer program for inelastic analysis of RC shells with layered elements developed in the present study enabled us to perform mesh convergence studies. The vector program can be used for studying the ultimate behavior of RC shells and used as a design tool.

• 융합신호처리학회논문지
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• 제8권4호
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• pp.293-296
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• 2007

본 논문에서는 벡터 미디언 값을 계산하기 위한 시스톨릭 어레이 구조의 벡터 미디언 필터 구조를 제안하였다. 컬러영상처리에서 벡터 신호는 빨강, 녹색 파랑의 3개의 요소로 이루어져 있다. 벡터 미디어 필터는 빨강, 녹색 파랑 요소로 이루어진 벡터 신호들 중에서 벡터 신호를 크기 순서대로 나열하였을 때 가운데 값을 갖는 벡터 신호를 구하는 필터로, 컬러 영상처리에서 기본적으로 많이 사용되는 필터이다. 벡터 신호가 N 개가 있을 때, 지금 까지 제안된 구조에서는(3N+1) 클럭이 필요하나, 제안된 구조에서는 (N+2) 클럭이 소요된다. 그리고 기존의 구조에서는 N 개의 입력 벡터 신호는 미디언 필터에 병렬로 입력되어야 하나 제안된 구조에서는 입력 신호는 직렬로 인가된다. FPGA를 사용하여 구현하였다.