• Structural Engineering and Mechanics
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• 제60권6호
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• pp.1079-1092
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• 2016

In this paper, an electromechanical integrated harmonic piezodrive system is proposed. The operating principle of the drive system is introduced. The equation of the relationship between the displacements of the flexible ring and the rotating angle of the rotor is deduced. Using the equation, the displacements of the flexible ring for the drive system and their changes along with the system parameters are investigated. The results show that the displacements of the flexible ring changes periodically along with the rotation of the vibrator; there are abrupt changes in the displacements of the flexible ring at some points where there are abrupt changes in the number of the mesh teeth pair; the length of the flexible ring, the excitation voltage, and the speed ratio have obvious effects on the displacements of the flexible ring. The results are useful for the design of the drive system. ;

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.540-542
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• 1999

We develop jumping ring system with sensor and control system using dynamic neural networks. Jumping ring, sensor and control system are controlled by 586 PC using Turbo C program. Sensor system is composed of 20 optical sensors and encoder. The control circuits are consisted of thyristor, FET and phase controller. A/D converter and optical sensor acquire real time motion data of the jumping ring system. The information of acquired jumping ring Position is estimated by using dynamic neural networks. Estimated control signals are sent to control circuits and D/A converter to track desired position of the jumping ring system. Experiment results are given to verify that proposed dynamic controller is useful in real jumping ring system.

• 한국컴퓨터정보학회논문지
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• 제12권2호
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• pp.37-45
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• 2007

본 논문에서는 각 조직과 사용자의 특성에 맞는 맞춤형 e-Ring(Enterprise Portal Back Tone) 시스템을 설계하고 개발하였다. e-Ring 시스템은 고객들이 조직에 전화를 걸 때, 전화 통화를 시작하기 전까지 기다리게 되는 귀중한 시간을 최대한 낭비하지 않도록 하기 위해 고객에게 통화연결음 서비스를 비롯하여 부가 서비스를 제공하는 시스템이다. 이는 일반적인 전화 통화에서 듣게 되는 의미없는 링연결음을 대신하여 조직의 이미지에 적합한 홍보를 할 수 있으며 또한 서비스 사용자 자동 응대 및 서비스 사용자에게 필요한 서비스를 제공하여 서비스 가용성과 업무의 효율성을 극대화 할 수 있다.

• International Journal of Fluid Machinery and Systems
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• 제8권1호
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• pp.46-54
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• 2015

Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions from thrust bearing and operation conditions of hydro-generator units. Because the oil circulatory and cooling system with thrust-ring-pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump. On another hand, the head and flow rate are varying with the operation conditions of hydro-generator units and the oil circulatory and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulatory and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization is purposed in this paper. Firstly, the head and flow rate at different conditions are decided by 1D flow numerical simulation of the oil circulatory and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and flow rate from the simulation. Thirdly, the flow passage geometry matching optimization between thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulatory and cooling system are collaborative hydrodynamic optimized with predicted head-flow rate curve and the efficiency-flow rate curve of thrust-ring-pump. The presented methodology has been adopted by DFEM in design process of thrust-ring-pump and it shown can effectively improve the performance of whole system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.520-522
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• 2005

This paper presents the design and analysis of the electromagnetic system such as jumping ring system. Also, we study the characteristics of dynamics for system with initial parameter. For the propose of system control,, first, we simulate the MATLAB tool solving coupled differential equations with electric parameter, inductance and mutual inductances. Therefore, we design a jumping ring system using design results, implement, and analyze the jumping ring system real situation. For the near time, we present a control process, and compare of real system and software technique.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권1호
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• pp.17-19
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• 2006

This paper presents the design of an electromagnetic system such as jumping ring system, and also considers the characteristics of dynamics for system with initial parameter. For the propose of system analysis, the MATLAB tool is to solve coupled differential equations with inductances and mutual inductance. To apply a real electromagnetic system, this paper implements the jumping ring system using design parameters, and analyzes the jumping ring system with proposal step.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1476-1479
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• 1996

발전설비나 자동차 그리고 항공우주분야에 사용되는 각종 bearing, 원형부품들에 사용되는 ring을 생산하는 방법중, 가장 효과적이고 경제적인 방법은 ring rolling (ring 압연)이다. 이 방법은 직경 50cm에서 2m이상의 원형 ring을 연속적으로 짧은 시간내에 (한 ring당 약 1분) 생산 가능하다. 이제까지의 수학적 모델을 사용한 제어시스템은 ring의 단면적이 사각형인 제품에는 최소한의 오차로 생산 가능하였으나, plant의 생산성과 제품의 다양성을 위하여 ring의 단면적이 복잡한 것을 생산시에는 문제점이 노출되었다. 왜냐하면 기존의 수학적모델이 roll gap 또는 metal forming zone에 근거하여 modelling하였기 때문이다. 본 논문에서는, 이러한 문제점을 고전적인 수학적 모델을 기초로한 adaptive control system의 방법대신에, 축적된 control system설계와 운용 경험을 이용하여 설계한 퍼지제어기 및 그것의 실적용 그리고 그 결과를 소개한다. 실적용 결과는, 제조된 단면적이 상대적으로 복잡한 bearing의 형상이 (filling grad)이 제어기의 제어정도 판단기준이었는데, 99.5%의 형상도를 보임으로서 industry에서 요구하는 제품기준을 만족시켰다. 또한 짧은 제어기 설계 및 on-line optimization 기간 또한 이 제어기의 장점이었다.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권12호
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• pp.571-576
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• 2002

This paper is to develop jumping ring system with three sensor arrays and to control levitated ring using dynamic neural mode. Placing an aluminum ring on the core and switching on an AC source causes the ring to jump in the air due to induced currents. The educational system is composed of 40th optical sensor array, encode circuit, 89C51 microprocessor and control board. The control board consists of power IC, and phase controller. Real time process is present to obtain a height of levitated ring for three different sensor arrays. Based on the educational system and the proposed dynamic neural mode, the height of levitation of the ring is controlled by reference signals. This paper focuses on real system controls using the dynamic neural mode with on line learning algorithm.

• 한국정보과학회논문지:시스템및이론
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• 제29권2호
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• pp.105-115
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• 2002

NUMa 구조는 원격 메모리에 대한 접근이 불가피한 구조적 특성 때문에 상호 연결망이 시스템 성능을 좌우하는 큰 변수가 된다. 기존에 대중적으로 사용되던 버스는 물리적 확장성 및 대역폭에서 대규모 시스템을 구성하는데 한계를 보인다. 이를 대체하는 고속의 지점간 링크를 사용한 이중 링구조는 버스가 가지는 확장성 및 대역폭의 한계라는 단점을 개선하였으나, 많은 노드가 연결되는 경우에는 응답 지연시간이 증가하는 문제점을 가지고 있다. 본 논문에서는 스누핑 프로토콜이 적용된 이중 일 구조에서 노드개수 증가에 따른 응답지연시간 증가의 문제점을 보안하기 위해 코달 링 구조로의변화를 제안하고 이 구조에 효과적인 링크 제어기를 설계한다. 또한 확률 구동 시뮬레이터를통해 본 논문을 통해 제시한 코달 링 구조가 시스템의 성능 및 응답시간에 미치는 영향을 알아본다.

• 대한수학회보
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• 제28권2호
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• pp.175-180
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• 1991

In [3], [4] and [5], Hochster and Huneke introduced the notions of the tight closure of an ideal and of the weak F-regularity of a ring. This notion enabled us to give new proofs of many results in commutative algebra. A regular ring is known to be F-regular, and a Gorenstein local ring is proved to be F-regular provided that one ideal generated by a system of parameters (briefly s.o.p.) is tightly closed. In fact, a Gorenstein local ring is weakly F-regular if and only if there exists a system of parameters ideal which is tightly closed [3]. But we do not know whether this fact is true or not if a ring is not Gorenstein, in particular, a ring is a Cohen Macaulay (briefly C-M) local ring. In this paper, we will prove this in the case of an 1-dimensional C-M local ring. For this, we study the F-rationality and the normality of the ring. And we will also prove that a C-M local ring is to be Gorenstein under some additional condition about the tight closure.