• 호남수학학술지
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• 제27권2호
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• pp.267-271
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• 2005

We study hypersurfaces in the Euclidean space with the following property: the tangential part of the position vector has constant length. As a result, we prove that among the connected and complete hypersurfaces in the Euclidean space, only the hypersphere centered at the origin satisfies the property.

• 대한수학회지
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• 제39권3호
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• pp.397-410
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• 2002

In this paper, some inequalities for vector-valued maximal functions over locally compact Vienkin groups are obtained.

• 대한수학회논문집
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• 제13권2호
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• pp.317-336
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• 1998

We study real hypersurfaces of a complex space form such that the Jacobi operator with respect to the structure vector field and the structure tensor $\phi$ on the real hypersurface commute.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 추계학술대회 논문집
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• pp.230-231
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• 2016

본 논문은 공간벡터 변조 방법에서부터 Six-step 동작까지의 새로운 과변조 방법을 제시하였다. 극전압을 푸리에 시리즈를 이용하여 분석하였고 지령 상전압에서부터 펄스 폭 변조 스위칭 신호까지의 알고리즘을 제안하였다. Matlab 시뮬레이션을 통해 검증하였다.

• 대한수학회보
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• 제46권4호
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• pp.713-720
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• 2009

We find all left-invariant minimal unit vector fields and strongly normal unit vector fields on a Lie group which is isometric to the hyperbolic space.

• 대한수학회지
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• 제33권3호
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• pp.609-624
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• 1996

Recently, Giannessi [9] firstly introduced the vector-valued variational inequalities in a real Euclidean space. Later Chen et al. [5] intensively discussed vector-valued variational inequalities and vector-valued quasi variationl inequalities in Banach spaces. They [4-8] proved some existence theorems for the solutions of vector-valued variational inequalities and vector-valued quasi-variational inequalities. Lee et al. [14] established the existence theorem for the solutions of vector-valued variational inequalities for multifunctions in reflexive Banach spaces.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1664-1670
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• 1991

For kinematically redundant manipulators, conventional dynamic control methods of local torque optimization showed the instability which resulted in physically unachievable torque requirements. In order to guarantee stability of the null space vector method which resolves redundancy at the acceleration level, Maciejewski[1] analyzed the kinetic behavior of homogeneous solution component and proposed the condition to identify regions of stability and instability for this method. 'In this paper, a modified null space vector method is first presented based on the Maciejewski's condition which is a function of a manipulator's configuration. Secondly, a new control method which is based on the concept of aspects is proposed. It was shown by computer simulations that the modified null space vector method and the proposed method have a common property that a preferred aspect is preserved during the execution of a task. It was also illustrated that both methods demonstrate a drastic reduction of torque loadings at the joints in the tracking motion of a long trajectory when compared with the null space vector method, and thus guarantee the stability of joint torque.

• 전력전자학회논문지
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• 제9권4호
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• pp.303-310
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• 2004

본 연구에서는 순시전압 sag 및 고조파 전류 보상을 위한 공간벡터 검출법을 기반으로 한 3상 하이브리드 직렬형 능동전력필터 시스템을 제안하고 있다. 순시전안 sag 및 고조파 전류를 검출하기 위한 공간벡터 검출법은 종전의 이론에 비해 곱셈 연산 과정을 감소할 수 있고 좌표 변환이 필요치 않기 때문에 간략화한 보상 알고리즘 구현이 가능하다. 본 연구의 타당성은 전력전자전용 시뮬레이터 PSIM에 의해 정상상태와 과도상태에서 입증하였다. 그 결과 3상 교류 전원 모두에 순간적인 전압 sag가 발생되거나, 임의의 상에 왜형 및 sag가 있는 경우, 전압 보상 및 고조파 전류 보상이 모두 가능함을 입증하였다.

• Journal of Power Electronics
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• 제4권2호
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• pp.77-86
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• 2004

This paper presents a novel three-phase power module bridge type auxiliary resonant AC link snubber for the three-phase voltage-fed sinwave soft switching PWM inverter operating under specific instantaneous space voltage vector modulation. The operating principle of this resonant snubber is described for current source load model during one switching period, along with its design approach based on the simulation data. The performance evaluations of space vector modulation three-phase sinewave soft switching inverter with a new three-phase active auxiliary resonant AC link snubber are discussed as compared with those of three-phase voltage source-fed sinewave hard switching PWM inverter with a standard space voltage vector modulation strategy. The power loss analysis and conventional efficiency estimation of three-phase soft switching PWM inverter using ICBT modules are carried out including all the conduction power losses based upon the measured v-i characteristics of IGBT and its antiparallel diode as well as their switching losses.

• 전력전자학회논문지
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• 제12권4호
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• pp.332-338
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• 2007

본 논문은 ZSI에서 shoot-through 시간을 효율적으로 제어하기 위한 변형 공간전압 변조방식으로 3종류를 제시하였다. 3개의 변형 공간전압 변조방식에 대한 스위칭 패턴과 shoot-through 시간변화에 대한 변조신호의 변화를 분석한다. Shoot-through 시간 제어 범위와 함께 스위칭 패턴 및 변조신호의 평형성 등을 고려하여 최적의 변형 공간전압 변조방식을 선정하였으며, 32비트 DSP를 사용한 실험을 통하여 그 타당성을 확인한다.