• Journal of Power Electronics
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• 제3권4호
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• pp.239-248
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• 2003

This paper presents a novel prototype of three-phase voltage source type zero voltage soft-switching inverter with the auxiliary resonant snubbers suitable for high-power applications with IGBT power module packages in order to reduce their switching power losses as well as electromagnetic conductive and radiative noises. A proposed single inductor-assisted resonant AC link snubber circuit topology as one of some auxiliary resonant commutation snubbers developed previously to achieve the zero voltage soft-switching (ZVS) for the three-phase voltage source type sinewave PWM inverter operating under the instantaneous space voltage vector modulation is originally demonstrated as compared with the other types of resonant AC link snubber circuit topologies. In addition to this, its operation principle and unique features are described in this paper. Furthermore, the practical basic operating performances of the new conceptual instantaneous space voltage vector modulation resonant AC link snubber-assisted three-phase voltage source type soft-switching PWM inverter using IGBT power module packages are evaluated and discussed on the basis of switching voltage and current waveforms, output line to line voltage quality, power loss analysis, actual power conversion efficiency and electromagnetic conductive and radiative noises from an experimental point of view, comparing with those of conventional three-phase voltage source hard-switching PWM inverter using IGBT power modules.

• 한국측량학회지
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• 제28권2호
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• pp.247-254
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• 2010

SPOT 4 위성영상의 기하 왜곡을 보정하기 위하여 새로운 접근방법을 연구하였다. 우주공간에서 위성과 지구의 관계를 정립함으로서 새로운 조건 방정식을 유도하였다. 초기 위성에 대한 정보가 어떤 일정한 변화에 의해 왜곡이 있다고 가정하고, LOS(Line-Of-Sight) 벡터를 변화시켜 위성영상의 기하를 보정하는 LOS 벡터 조정 모델을 연구하였다. 본 모델을 증명하기 위하여 관측각이 큰 SPOT 4 위성영상을 대상으로 실험하였다. 또한, 정확한 실험을 위하여 GPS로부터 측량한 10개의 지상기준점(GCPs)과 25개의 검사점(check points)을 사용하였다. SPOT 4 위성영상에 주어진 초기 위성정보(위성 위치, 속도, 자세, 관측각 등)를 그대로 이용하여 계산한 위성영상 기하는 총 35개의 지상기준점과 검사점에 대하여 거의 일정한 변화량을 지녔으며, 이를 통해 SPOT 4 위성영상에 시선벡터조정모델을 적용할 수 있음을 확인하였다. 시선벡터조정모델을 적용하여 영상에 고르게 분포하는 지상기준점을 2점에서 10점까지 변화시키면서 검사점의 오차를 계산하였고, 25개 검사점 오차는 모두 1픽셀 미만이었다. 새로운 접근 방법인 이 모델은 2점 이상의 지상기준점을 이용하여 SPOT 4 영상 기하를 효과적으로 보정하였으며, 또한 SPOT 영상과 촬영방식이 동일한 고해상 위성영상에 대해서도 좋은 결과를 얻을 것으로 기대한다.

• 전력전자학회논문지
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• 제3권2호
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• pp.118-124
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• 1998

This paper describes a relationship of a space vector PWM and a sinusoidal PWM and presents that the space vector PWM can produce linearly the output voltage to the unity MI(modulation index). At first, reference angles and holding angles are derived from expanding a Fourier series of the reference voltage waveform and then the angles are used for the inverter switching to linearize transfer characteristics of the inverter. In addition, the harmonic components of the output voltage are analyzed and on-line control is shown to be feasible by approximating in piecewise-linearization the reference and holding angles versus the MI. In V/f control of the induction motor, it is verified by the experiment that the motor current is changed smoothly for the variation of the inverter input voltage and the change of the reference voltage.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.21-24
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• 2002

The vector control system of an induction motor is the high performance drive system to achieve the instantaneous torque control. The vector control system is greatly divided into the direct control, and the indirect control that the most widely is used, The indirect vector control needs the rotor time constant, which changes widely according to the temperature, frequency, and current amplitude. The incorrect time constant leads to the saturation of magnetic flux or under-excitation phenomena. As a result, that deteriorate the control performance. Therefore, in this paper, the effect of time constant variation is investigated and its on-line tuning algorithm is proposed. The time constant using the torque angles was calculated and that of the validity of algorithm proposed was proved through the computer simulation and the experiment.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.588-591
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• 2000

Sphingoliped 대사의 율속효소인 serine palmitoyl transferase(SPT)와 acid ceramidase의 연구를 위하여 인간의 SPTII 유전자와 acid ceramidase 유전자의 5‘-upstream region을 얻었다. 사람의 대장암세포인 HT29 cell로부터 genomic DNA를 얻고 GenomeWalker kit를 이용하였으며 2690bp의 SPTII promoter와 2028bp 및 1034bp의 acid ceramidase promoter의 fragment들을 얻을 수 있었다. 이들 DNA 조각들을 T7Blue vector에 subcloning하여 sequencing하였으며 이들이 사람의 SPTII 및 acid ceramidase gene의 5’-upstream region임을 확인하였다. 동물세포에서의 promoter activity를 측정하기위하여 firefly luciferase를 reporter gene으로 하는 pGL2-enhancer vector와 pGL2-basic vector에 subcloning하였으며 pRL-TK vctor와 함께 HT29 cell 및 HepG2 cell에 cotransfection 시킨 후 luciferaseg활성을 측정한 결과 같은 양의 DNA로는 사람의 SPTII promoter와 acid ceramidase promoter는 pRL-TK에 비하여 transfection efficiency가 아주 낮았으며 promoter 연구를 위하여는 pRL-TK vector의 양을 1/100으로 줄이는 것이 적당하였으며 HT29 cell보다는 HepG2 cell에 더 높은 발현율을 보였다.

• 한국학교수학회논문집
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• 제16권4호
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• pp.841-862
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• 2013

이 연구는 2007 개정 교육과정의 '기하와 벡터' 교과에서 다루어지는 벡터와 내적 개념을 분석하여 그 특징을 기술함으로써 벡터와 내적 개념 지도의 교수학적 시사점을 얻는데 목적을 두었다. 이를 위해 '기하와 벡터' 교육과정에서 다루어지는 벡터와 내적 개념 분석을 위한 세부 관점을 Tall(2002a; Tall, 2004b)과 Watson et al.(2003; Watson, 2002)에 기초하여 5가지로 추출하고, 이렇게 추출된 세부 관점을 토대로 '기하와 벡터' 교육과정 및 교육과정해설서, '기하와 벡터' 교과서 10종 모두에서 다루어지는 벡터와 내적 개념의 특징을 분석하였다. 이로부터 벡터와 내적 개념 형성과 관련된 교육과정상의 이슈를 구체화하였으며 이에 비추어 '기하와 벡터' 교과서에서 벡터 단원의 내용을 전개하는 방식과 관련된 시사점을 논의하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2521-2524
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• 2003

Since inertial sensor errors which increase with time are caused by initial orientation error and sensor errors (accelerometer bias and gyro drift bias), the accuracy of these devices, while still improving, is not adequate for many of today's high-precision, long-duration sea, aircraft, and long-range missile missions. This paper presents a navigation error compensation scheme for Strap-Down Inertial Navigation System (SDINS) using Line-Of-Sight(LOS) vector from star sensor. To be specific, SDINS error model and measurement equation are derived, and Kalman filter is implemented. Simulation results show the bounded-ness of position and attitude errors.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.420-427
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• 2017

This paper proposes a new method using Wide Line Detector based statistical shape Feature (WLDF) to identify whether or not a tongue is cracked; a cracked tongue is one of the most frequently used visible features for diagnosis in traditional Chinese Medicine (TCM). We first detected a wide line in the tongue image, and then extracted WLDF, such as the maximum length of each detected region, and the ratio between maximum length and the area of the detected region. We trained a binary support vector machine (SVM) based on the WLDF to build a classifier for cracked tongues. We conducted an experiment based on our proposed scheme, using 196 samples of cracked tongues and 245 samples of non-cracked tongues. The results of the experiment indicate that the recognition accuracy of the proposed method is greater than 95%. In addition, we provide an analysis of the results of this experiment with different parameters, demonstrating the feasibility and effectiveness of the proposed scheme.

• 전자공학회논문지S
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• 제34S권2호
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• pp.104-111
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• 1997

In this paper, three-phase PWM AC to DC boost converter that operates with unity power factor and sinusodial input line currents is presented. The current control of this converter is based on the space vector PWM strategy with fixed switching frequency and the line currents track to reference currents within one sampling time interval. By using this control strategy low ripples in the outut current and the voltage as well as fast dynamic response are achieved with small dc link cpacitance employed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.763-766
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• 1991

The moving of each axis in the robot manipulator can be represented with the motion of cartesian space. This paper shows the robot manipulator of the straight line trajectory planning algorithms in the cartesian space. The relation formulas between cartesian space and joint space are induced to accomplish a desired trajectory in the cartesian space and the velocity vector of sampling time in the cartesian space is transformed into the velocity vector of joint by the interpolation method. The error of trajectory in moving is removed by obtaining the real position for the present joint position and the desired distance is made by comparing the real position and the next position. Through the simple tests for suggested algorithms are confirmed the validity of algorithms.