• 제어로봇시스템학회논문지
• /
• 제12권5호
• /
• pp.505-508
• /
• 2006

This paper presents a new analytical approach for designing multiloop PI controllers for disturbance rejection in multivariable processes with time delay. The proposed method is based on IMC-PID design approach. To overcome a sluggish load response by dominant pole in the process, the IMC filter is modified to compensate the dominant pole effect. Based on the modified IMC filter, an analytical tuning rule for multiloop PI controller is driven by extending the generalized IMC-PID method for single input/single output (SISO) systems [1] to multi input/multi output (MIMO) systems. Simulation results show that the proposed method gives a satisfactory load performance as well as servo performance in the multiloop system.

• 한국산학기술학회논문지
• /
• 제14권4호
• /
• pp.1982-1987
• /
• 2013

본 논문에서는 1.7-2.7 GHz 대역에서 동작하는 이동통신 기지국용 광대역 직렬 급전 다이폴 쌍 (SDP) 안테나에 대하여 2.4-2.484 GHz 무선랜(WLAN) 대역에서 저지 특성을 가지기 위한 설계 방법을 연구하였다. 대역 저지 특성은 SDP 안테나의 두 다이폴 소자를 연결하는 코플래너 스트립 선로 상에 U자형 슬롯을 삽입함으로써 얻을 수 있다. 슬롯의 위치와 구조에 따른 저지 대역의 특성 변화를 분석하였다. 최적화된 WLAN 대역 저지 SDP 안테나를 FR4 기판 상에 제작하고 특성을 실험한 결과 VSWR < 2 인 대역은 1.65-2.78 GHz (51.0%) 이고, 저지 대역은 2.39-2.54 GHz로 원하는 대역 저지 성능을 갖는 것을 확인하였다.

• 한국음향학회지
• /
• 제23권8호
• /
• pp.597-601
• /
• 2004

본 논문에서는 CDMA이동통신 환경에서의 음성인식을 위한 왜곡음성신호의 전처리-지부방법을 소개한다. 먼저, CDMA이동통신 채널에서의 왜곡된 음성신호를 분석하고 분석된 매커니즘을 바탕으로 채널에 의해 왜곡된 음성신호를 음성의 준주기성을 바탕으로 하여 거부하는 알고리즘을 제안한다. 실험을 통해 제안된 전처리-거부방법이 적은 계산량을 가지고 음성인식에 적용되어 효과적으로 CDMA에 환경에서 채널왜곡된 음성신호를 거부-할 수 있음을 알 수 있었다.

• 전자공학회논문지SC
• /
• 제44권2호
• /
• pp.10-17
• /
• 2007

의료용 초음파 시스템으로 혈류 속도를 측정할 때, 순수한 혈류 신호의 검출이 필요하다. 초음파 트랜스듀서를 통해 들어오는 반사 신호는 체세포 조직(tissue), 혈관 벽(blood wall), 적혈구(red blood cell), 잡음(noise) 등이 혼합된 신호이다. 혼합된 신호에서 체세포 조직과 혈관 벽 신호를 클러터(clutter)라고 한다. 본 논문에서는 ICA(independent component analysis)를 적용하여 클러터 신호와 잡음을 효과적으로 제거하는 방법을 제시하였다. Field II 초음파 시뮬레이션 프로그램을 이용하여 초음파 반사 신호를 생성하고, ICA를 사용하여 각 독립 신호들을 분리, 클러터 신호를 제거하여 혈류 신호를 추출했다. 추출전 혈류신호를 2D 자기상관(autocorrelation) 방법으로 혈류 속도를 측정했다. 그리고 PCA(principal component analysis)방법을 적용한 고유 필터(autocorrelation) 방법으로 클러터를 제거한 결과와 비교하였다. 그 결과 잡음 환경에서의 혈류 속도 측정에 ICA 방법이 우수한 적용 결과를 보였다.

• 음성과학
• /
• 제15권4호
• /
• pp.85-96
• /
• 2008

Automatic speech recognition has severe performance degradation under noisy environments. To cope with the noise problem, many methods have been proposed. Most of them focused on noise-robust features or model adaptation. However, researchers have overlooked utterance verification (UV) under noisy environments. In this paper we discuss UV problems based on the normalized confidence measure. First, we show that UV performance is also degraded in noisy environments with the experiments of an isolated word recognition. Then we observe how the degradation of UV performances is suffered. Based on the UV experiments we propose a modeling method of the statistics of phone confidences using sigmoid functions. For obtaining the parameters of the sigmoidal models, the particle swarm optimization (PSO) is adopted. The proposed method improves 20% rejection performance. Our experimental results show that the PSO-NCM can apply noise speech recognition successfully.

• 한국해양공학회지
• /
• 제38권3호
• /
• pp.115-123
• /
• 2024

USBL systems are essential for providing accurate positions of autonomous underwater vehicles (AUVs). On the other hand, the accuracy can be degraded by outliers because of the environmental conditions. A failure to address these outliers can significantly impact the reliability of underwater localization and navigation systems. This paper proposes a novel outlier rejection algorithm for AUV localization using Voronoi diagrams and query point calculation. The Voronoi diagram divides data space into Voronoi cells that center on ultra-short baseline (USBL) data, and the calculated query point determines if the corresponding USBL data is an inlier. This study conducted experiments acquiring GPS and USBL data simultaneously and optimized the algorithm empirically based on the acquired data. In addition, the proposed method was applied to a sensor fusion algorithm to verify its effectiveness, resulting in improved pose estimations. The proposed method can be applied to various sensor fusion algorithms as a preprocess and could be used for outlier rejection for other 2D-based location sensors.

• Journal of Power Electronics
• /
• 제17권6호
• /
• pp.1611-1624
• /
• 2017

With the rapid development of microgrid technology, microgrid projects are no longer limited to laboratory demonstrations and pilot platforms. It shows greater value in practical applications. Hence, the smooth interaction between a microgrid and the main grid plays a critical role. In this paper, a control method based on active disturbance rejection control (ADRC) is proposed in order to realize seamless transitions between grid-connected and islanding operation modes and stable operation with variable loads. It is verified by simulations that the proposed ADRC-based method features better performance when compared to conventional proportional-integral-differential (PID) control. Meanwhile, the stability of the third-order extended state observer (ESO) in second-order ADRC is validated by using Lyapunov stability criteria.

• 한국군사과학기술학회지
• /
• 제17권2호
• /
• pp.175-181
• /
• 2014

In this paper, we propose a robust clutter pre-thresholding method using background adaptive Threshold Map for the clutter rejection in the complex coastal environment. The proposed algorithm is composed of the use of Threshold Map's and method of its calculation. Additionally we also suggest an automatic decision method of Thresold Map's update. Experimental results on some sets of real infrared image sequence show that the proposed method could remove clutters effectively without any loss of detection rate for the aim target and reduce processing time dramatically.

• Management Science and Financial Engineering
• /
• 제20권1호
• /
• pp.27-32
• /
• 2014

This paper introduces three different simulation algorithms of the shifted Poisson distribution. The first algorithm is the inverse transform method, the second is the rejection sampling, and the third is gamma-Poisson hierarchy sampling. Three algorithms have different regions of parameters at which they are efficient. We numerically compare those algorithms with different sets of parameters. As an application, we give a simulation method of the constant elasticity of variance model.

• 조명전기설비학회논문지
• /
• 제23권7호
• /
• pp.67-74
• /
• 2009

This paper describes the speed control functions of the typical steam turbine speed controllers and the test results of generator load rejection simulations. The goal of the test is to verify the speed controller's ability to limit the steam turbine's peak speed within a predetermined level in the event of generator load loss. During normal operations, the balance between the driving force of the steam turbine and the braking force of the generator load is maintained and the speed of the turbine-generator is constant. Upon the generator's load loss, in other word, the load rejection, the turbine speed would rapidly increase up to the peak speed at a fast acceleration rate. It is required that the speed controller has the ability to limit the peak speed below the overspeed trip point, which is typically 110[%] of rated speed. If an actual load rejection occurs, a substantial amount of stresses will be applied to the turbine as well as other equipments, In order to avoid this unwanted situation, not an actual test but the other method is necessary. We are currently developing the turbine control system for another nuclear power plant and have plan to do the simulation suggested in this paper.