• 센서학회지
• /
• 제22권1호
• /
• pp.28-37
• /
• 2013

This paper presents a fault-tolerant control technique for wind turbine systems with sensor and actuator faults. The control objective is to maximize power production and minimize turbine loads by calculating a desired pitch angle within their limits. Any fault with a sensor and actuator can cause significant error in the pitch position of the corresponding blade. This problem may result in insufficient torque such that the power reference cannot be achieved. In this paper, a fault-tolerant control technique using a robust dynamic inversion observer and control allocation is employed to achieve successful pitch control despite these faults in the sensor and actuator. The observer based detection method is used to detect and isolate sensor faults by checking whether errors are larger than threshold values. In addition, the control allocation technique is adopted to tolerate actuator fault. Control allocation is one of the most commonly used fault-tolerant control techniques, especially for over-actuated systems. Further, the control allocation method can be used to achieve the power reference even in the event of blade actuator fault by redistributing the lost torque due to erroneous pitch position into non-faulty blade actuators. The effectiveness of the proposed method is demonstrated through simulations with a benchmark model of the wind turbine.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
• /
• pp.309-313
• /
• 2009

In this paper, the network performance of a turbo coded optical code division multiple access (CDMA) system with cross-layer, which is between physical and network layers, concept is analyzed and simulated. We consider physical and MAC layers in a cross-layer concept. An intensity-modulated/direct-detection (IM/DD) optical system employing pulse position modulation (PPM) for satellite broadcasting communications is considered. In order to increase the system performance, turbo codes composed of parallel concatenated convolutional codes (PCCCs) is utilized. The network performance is evaluated in terms of bit error probability (BEP). From the simulation results, it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is confirmed that the performance of such an optical CDMA network can be substantially improved by increasing the interleaver length and the number of iterations in the decoding process. The results of this paper can be applied to implement the satellite broadcasting communications.

• 한국컴퓨터정보학회논문지
• /
• 제23권11호
• /
• pp.51-57
• /
• 2018

In this paper, we studied about the extraction of the parameter and implementation of speechreading system to recognize the Korean 8 vowel. Face features are detected by amplifying, reducing the image value and making a comparison between the image value which is represented for various value in various color space. The eyes position, the nose position, the inner boundary of lip, the outer boundary of upper lip and the outer line of the tooth is found to the feature and using the analysis the area of inner lip, the hight and width of inner lip, the outer line length of the tooth rate about a inner mouth area and the distance between the nose and outer boundary of upper lip are used for the parameter. 2400 data are gathered and analyzed. Based on this analysis, the neural net is constructed and the recognition experiments are performed. In the experiment, 5 normal persons were sampled. The observational error between samples was corrected using normalization method. The experiment show very encouraging result about the usefulness of the parameter.

• 디지털융복합연구
• /
• 제14권5호
• /
• pp.301-307
• /
• 2016

탄광, 지하실, 지하창고 등 위험한 지역에서 일하는 일군들의 움직임을 비롯한 위치 측정은 안전을 위해 반드시 필요한 기술이다. 위험하고 제한된 환경에서의 USN의 위치 측정 기법들은 다양하게 존재한다. 위치 측정 기법 중에 삼각측량법은 간단하기 때문에 여러 분야에서 많이 적용되고 있다. 하지만 측정기구와 전파 장애 및 물리적 장애로 인해 오차가 발생하여 정확한 위치를 파악하기 어렵다. 본 논문에서는 4개의 Anchor와 움직이는 노드 사이의 거리 정보를 다양하게 활용하여 재계산하여 기존 삼각측량법으로 얻은 위치보다 오차범위를 줄일 수 있는 방법을 제안한다. 또한 제안 기법을 통해 거리 측정하여 움직이는 노드의 위치 즉, 예측점을 계산하였을 때는 기존 삼각측량법보다 계산의 오버로드가 발생하지만 수학적으로 위치측정 오차 범위 계산 시 41%가 향상되었다.

• Journal of Positioning, Navigation, and Timing
• /
• 제7권3호
• /
• pp.127-138
• /
• 2018

Spoofing attacks including meaconing can provide a bogus position to a victim GPS receiver, and those attacks are notably difficult to detect at the point of view on the receiver. Several countermeasure techniques have been studied to detect, classify, and cancel the spoofing signals. Based on the countermeasure techniques, we have developed an anti-spoofing equipment that detects and mitigates or eliminates the spoofing signal based on raw measurements. Although many anti-spoofing techniques have been studied in the literatures, the evaluation test system is not deeply studied to evaluate the anti-spoofing equipment, which includes detection, mitigation, and elimination of spoofing signals. Each study only has a specific test method to verify its anti-spoofing technique. In this paper, we propose the performance evaluation test system that includes both spoofing signal injection system and its injection scenario with the constraints of stand-alone anti-spoofing techniques. The spoofing signal injection scenario is designed to drive a victim GPS receiver that moves to a designed position, where the mitigation and elimination based anti-spoofing algorithms can be successively evaluated. We evaluate the developed anti-spoofing equipment and a commercial GPS receiver using our proposed performance evaluation test system. Although the commercial one is affected by the test system and moves to the designed position, the anti-spoofing equipment mitigates and eliminates the injected spoofing signals as planned. We evaluate the performance of anti-spoofing equipment on the position error of the circular error probability, while injecting spoofing signals.

• 한국소음진동공학회논문집
• /
• 제19권4호
• /
• pp.355-362
• /
• 2009

Sound source localization method based on the time delay of arrival(TDOA) is applied to many research fields such as a robot auditory system, teleconferencing and so on. When multi-microphones are utilized to localize the source in 3 dimensional space, the conventional localization methods based on TDOA decide the actual source position using the TDOAs from all microphone arrays and the detection measure, which represents the errors between the actual source position and the estimated ones. Performance of these methods usually depends on the number of microphones because it determines the resolution of an estimated position. In this paper, we proposed the localization method using spatially mapped GCC functions. The proposed method does not use just TDOA for localization such as previous ones but it uses spatially mapped GCC functions which is the cross correlation function mapped by an appropriate mapping function over the spatial coordinate. A number of the spatially mapped GCC functions are summed to a single function over the global coordinate and then the actual source position is determined based on the summed GCC function. Performance of the proposed method for the noise effect and estimation resolution is verified with the real environmental experiment. The mean value of estimation error of the proposed method is much smaller than the one based on the conventional ones and the percentage of correct estimation is improved by 30% when the error bound is ${\pm}20^{\circ}$.

• 전기학회논문지
• /
• 제64권9호
• /
• pp.1374-1379
• /
• 2015

Time Domain Reflectometry(TDR) using microwave bands, including broadband spectrum that occurs at the range of rates that start between partial discharge position it easier to make the techniques that could be measured. Partial discharge in the Gas Insulated Switchgear(GIS), the dielectric constant in the band more than GHz different the insulating material if you want to organize, and the insulating material regardless of how partial discharge position in the SF6 gas Partial Discharge by applying the heritability estimated its position, but the position error occurred about 23 percent of the existing way, correct in not suitable location tracking the outbreak PD. This technique the rate of other dielectric that make up the power apparatus heterology is measured at the function to slow the progression of the electromagnetic waves apart by calculating the partial discharge as the location, A simple way to track. Dielectric using other methods proposed new structure can calculate the speed of heritability PD is occurring can measure.

• International Journal of Internet, Broadcasting and Communication
• /
• 제10권4호
• /
• pp.70-74
• /
• 2018

In order to ensure the flow of goods available and more flexible, reduce labor costs, many factories and industrial zones around the world are gradually moving to use automated solutions. One of them is to use Automated guided vehicles (AGV). Currently, there are a line tracing method as an AGV operating method, and a method of estimating the current position of the AGV and matching with a factory map and knowing the moving direction of the AGV. In this paper, we propose ceiling Light and guided line based moving direction estimation algorithm using multi-camera on the AGV in smart factory that can operate stable AGV by compensating the disadvantages of existing AGV operation method. The proposed algorithm is able to estimate its position and direction using a general - purpose camera instead of a sensor. Based on this, it can correct its movement error and estimate its own movement path.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2001년도 Proceedings of 2001 Korea-Japan Joint Seminar on Particle Image Velocimetry
• /
• pp.100-107
• /
• 2001

A simple new technique of particle depth position measurement, which can be applied for three-dimensional velocity measurement of fluid flows, is proposed. Two color illumination system that intensity is encoded as a function of z-coordinate is introduced. A calibration procedure is described and a profile of small sphere is detected by using the present method as preliminary test. Then, this method is applied to three-dimensional velocity field measurement of simple flow fields seeded with tracer particles. The motion of the particles is recorded by color 3CCD camera. The particle position in the image plane is read directly from the recorded image and the depth of each particle is measured by calculation of the intensity ratio of encoded two color illumination. Therefore three-dimensional velocity components are reconstructed. Although the result includes to some extent error, the feasibility of the present technique for three-dimensional velocity measurement was confirmed.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
• /
• pp.83-86
• /
• 2003

This paper suggests user's interface with computer by means of detecting gaze under HMD, head mounted display, environment. System is derived as follows; firstly, calibrate a camera in HMD, which determines geometrical relationship between monitor and captured image. Second, detect the center of pupil using algorithm of the center of mass and represent a gazing position on the computer screen. If user blinks or stares at a certain position for a while, message is sent to computer. Experimental results show the center of mass is robust against glint effects, and detecting error was 7.1%. and 4.85% in vertical and horizontal direction, respectively. To adjust detailed movement of a mouse takes 0.8 sec more. The 98% of blinking is detected successfully and 94% of clicking detection is resulted.