• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권8호
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• pp.440-447
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• 1999

This paper proposes a control method for three-phase PWM rectifier with only single current sensor in DC link side. A PWM modulation strategy for reconstructing three phase currents from the DC link current is given. The states of the retifier switch are modified so that all phase currents can be reconstructed in a switching period although one or two of active vectors is applied only for a short time. Therefore, a new current control using an adjustment scheme of the modulation signal for three-phase PWM rectifier will be discussed, and verified the experimental results.

• 한국해양공학회지
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• 제20권5호
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• pp.1-8
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• 2006

Offshore structures are subjected to wave, wind, and earthquake loads. The failure of offshore structures can cause sea pollution, as well as losses of property and lives. Therefore, safety of the structure is an important issue. The reduction of the dynamic response of offshore towers, subjected wind generated random ocean waves, is a critical problem with respect to serviceability, fatigue life and safety of the structure. In this paper, a structural control method is proposed to control the vibration of offshore structures by the probabilistic neural network (PNN). The state vectors of the structure and control forces are used for training patterns of the PNN, in which control forces are prepared by linear quadratic regulator (LQR) control algorithm. The proposed algorithm is applied to a fixed offshore structure under random ocean waves. Active control of the fixed offshore structure using the PNN control algorithm shows good results.

• Journal of Power Electronics
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• 제17권1호
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• pp.161-171
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• 2017

To enhance the reliability of two-motor drive systems, this paper proposes an improved direct torque control (DTC) scheme (P-DTC) for five-leg dual-PMSM drive systems. First, the topology of a five-leg dual-PMSM drive system is illustrated. To clarify the analysis of the P-DTC, the standard DTC scheme for three-phase drive systems is presented. The operation of a five-leg dual-PMSM drive system is classified into three situations according to the definitions of the switching-vector unions. Compared with the existing DTC scheme (R-DTC), the P-DTC can minimize the replacement of active switching-vectors to zero switching-vectors. When this replacement cannot be avoided, the P-DTC uses a proposed master-slave selection principle to minimize the system error. Comparing with the R-DTC, the P-DTC has lower torque ripples, a wider speed range and a faster torque increasing response. Experiments have been carried out in the coupling and independent modes, and the effectiveness of the P-DTC is verified by the obtained results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.3820-3841
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• 2018

Most of the accidents occur due to drowsiness while driving, avoiding road signs and due to driver's distraction. Driver's distraction depends on various factors which include talking with passengers while driving, mood disorder, nervousness, anger, over-excitement, anxiety, loud music, illness, fatigue and different driver's head rotations due to change in yaw, pitch and roll angle. The contribution of this paper is two-fold. Firstly, a data set is generated for conducting different experiments on driver's distraction. Secondly, novel approaches are presented that use features based on facial points; especially the features computed using motion vectors and interpolation to detect a special type of driver's distraction, i.e., driver's head rotation due to change in yaw angle. These facial points are detected by Active Shape Model (ASM) and Boosted Regression with Markov Networks (BoRMaN). Various types of classifiers are trained and tested on different frames to decide about a driver's distraction. These approaches are also scale invariant. The results show that the approach that uses the novel ideas of motion vectors and interpolation outperforms other approaches in detection of driver's head rotation. We are able to achieve a percentage accuracy of 98.45 using Neural Network.

• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.107-113
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• 2016

In this paper, by managing the biometric data is changed with the passage of time, a systematic and scientifically propose a framework to increase the bio-vector generation efficiency of the smart health care. Increasing the development of human life as a medicine and has emerged smart health care according to this. Organic and efficient health management becomes possible to generate a vector when the biological domain to the wireless communication infrastructure based on the measurement of the health status and to take action in accordance with the change of the physical condition. In this paper, we propose a framework to create a bio-vector that contains information about the current state of health of the person. In the proposed framework, Bio vectors may be generated by collecting the biometric data such as blood pressure, pulse, body weight. Biometric data is the raw data from the bio-vector. The scope of the primary data can be set to active. As the collecting biometric data from multiple items of the bio-recognition vectors may increase. The resulting bio-vector is used as a measure to determine the current health of the person. Bio-vector generating the proposed framework, it can aid in the efficiency and systemic health of healthcare for the individual.

• Parasites, Hosts and Diseases
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• 제59권5호
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• pp.513-518
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• 2021

The incidence of vivax malaria in Korea was reduced to a low plateau. For successful elimination of vivax malaria, socio-behavioral changes in the communities are essential. This study aimed to figure out awareness of the inhabitants on the vivax malaria endemicity. The 407 participants including vivax malaria patients and uninfected inhabitants in Gimpo- and Paju-si, Gyeonggi-do, known as high-risk areas in Korea. We used a community-based study design and non-probability sampling method using primary data. Except for the perception about the public health facilities' capability to cope with anti-malaria programs, the 2 groups of participants shared the same level of awareness about public promotional and educational measures and opinions for malaria elimination from the community. Thus, our future goals for malaria prevention and elimination are to develop more active and well-organized community-based education and evaluation programs collaborating with the community healthcare authorities and local governments.

• 정보처리학회논문지B
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• 제11B권3호
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• pp.281-288
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• 2004

본 논문은 외부 자극에 대한 생물 행동의 복잡하고 다양한 특징들을 추출하고 분석하기 위한 방법을 제안한다. 이를 위해 물 속 생물인 깔따구의 행동궤적으로부터 얻어 낸 속도 벡터의 위상영상에 적응적이고 수리적인 방법인 에너지 최소화 모델을 적용한다. 즉, 다이아지논이라는 약물이 처리되기 전과 후의 깔따구의 행동궤적의 특징을 위상영상으로부터 찾아내어 행동 패턴을 분류하고 이 약물에 대한 깔따구의 적응적 행동 특징을 추출하는 것이다. 특징추출을 위해 도입한 방법은 T. Chan과 L. Vese에 의해 제안된 개선 Active Contour 모델에 근거한 것으로 Active Contour를 진화시키는 과정에서 생성되는 에너지함수 값의 변화를 이용한 것이다. Active Contour 모델이란 주어진 영상에 놓인 커브를 그 커브에 의해 분할된 부분영상들의 에너지 값들의 합을 최소화하는 방향으로 변화하게 함으로써 영상 내 객체의 경계를 찾는 영상분할 방법이다. 깔따구의 행동궤적 데이터는 CCD 카메라를 통해 0.25초 간격으로 약물을 처리하기 전과 후 4일 간을 관찰하여 획득하고, 이 행동궤적 데이터에서 행동의 특징 요소가 되는 속도벡터 성분을 15-20분 간격으로 추출하여 위상영상을 만든다. 그리고 이 위상영상에 Active Contour를 적용함으로써 시간에 따라 감소하는 에너지 함수 값의 그래프에서 구해진 기울기 변화에 대한 수리적 계산과 분석을 통해 깔따구 행동궤적의 특징을 찾고 행동 패턴을 분류한다. 또한, 에너지 최소화 모델은 약물 처리된 깔따구의 반응적인 행동이 이에 적응하고 있음을 효과적으로 보여준다.

• Journal of Power Electronics
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• 제12권2호
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• pp.344-356
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• 2012

In recent years, multilevel technology has become an effective and practical solution in the field of moderate and high voltage applications. This paper discusses an APF with a three-level NPC inverter. Obviously, the application of such converter to APFs is hindered by the problem of the voltage unbalance of DC capacitors, which leads to system instability. This paper comprehensively analyzes the theoretical limitations of the neutral-point voltage balancing problem for tracking different harmonic currents utilizing current switching functions from the space vector PWM (SVPWM) point of view. The fluctuation of the neutral point caused by the load currents of certain order harmonic frequency is reported and quantified. Furthermore, this paper presents a close-loop digital control algorithm of the DC voltage for this APF. A PI controller regulates the DC voltage in the outer-loop controller. In the current-loop controller, this paper proposes a simple neutral-point voltage control method. The neutral-point voltage imbalance is restrained by selecting small vectors that will move the neutral-point voltage in the direction opposite the direction of the unbalance. The experiment results illustrate that the performance of the proposed approach is satisfactory.

• Journal of Power Electronics
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• 제18권3호
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• pp.789-801
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• 2018

Model predictive direct power control (MPDPC) is a widely recognized high-performance control strategy for a three-phase grid-connected pulse width modulation (PWM) rectifier. Unlike those of conventional grid-connected PWM rectifiers, the active and reactive powers of permanent magnet synchronous generator (PMSG)-connected PWM rectifiers, which are used in electromagnetic transmitters, cannot be calculated as the product of voltage and current because the back electromotive force (EMF) of the generator cannot be measured directly. In this study, the predictive power model of the rectifier is obtained by analyzing the relationship among flux, back EMF, active/reactive power, converter voltage, and stator current of the generator. The concept of duty cycle control in the proposed MPDPC is introduced by allocating a fraction of the control period for a nonzero vector and rest time for a zero vector. When nonzero vectors and their duration in the predefined cost function are simultaneously evaluated, the global power ripple minimization is obtained. Simulation and experimental results prove that the proposed MPDPC strategy with duty cycle control for the PMSG-connected PWM rectifier can achieve better control performance than the conventional MPDPC-SVM with grid-connected PWM rectifier.

• 천문학논총
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• 제14권2호
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• pp.103-112
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• 1999

We have investigated the solar activity variation with period shorter than 1000 days, through Fourier transformation of solar cycle 21 and 22 data. And real time predictions of the flare maximum intensity have been made by multilinear regression method to allow the use of multivariate vectors of sunspot groups or active region characteristics. In addition, we have examined the evolution of magnetic field and current density in active regions at times before and after flare occurrence, to check short term variability of solar activity. According to our results of calculation, solar activity changes with periods of 27.1, 28.0, 52.1, 156.3, 333.3 days for solar cycle 21 and of 26.5, 27.1, 28.9, 54.1, 154, 176.7, 384.6 days for solar cycle 22. Periodic components of about 27, 28, 53, 155 days are found simultaneously at all of two solar cycles. Finally, from our intensive analysis of solar activity data for three different terms of $1977\~1982,\; 1975\~1998,\;and\;1978\~1982$, we find out that our predictions coincide with observations at hit rate of $76\%,\;63\%$, 59 respectively.