Earticle

To maintain communication quality of a mobile satellite antenna system without disconnection, the satellite tracking technique is required. There are two major tracking methods called step tracking and monopulse tracking, which utilize satellite signals as a tracking feedback. The monopulse tracking method provides fast and accurate tracking performance, whereas it can be used only in limited small regions near the satellite's direction. In the case of step tracking method, it can be applied in relatively large regions. However, this method also has a limitation, in that it cannot provide fast and accurate tracking performance near the satellite direction. In this paper, a hybrid tracking method composed of step tracking mode and monopulse tracking mode is proposed. The proposed tracking method can present accurate tracking performance near the satellite direction as well as be applied in relatively large regions.

A magnetic levitation system requires a robustness to overcome a dynamic instability due to disturbances. In this paper a robust controller for a magnetically levitated fine manipulator is presented. The proposed controller consists of following two parts: a model reference controller and an $H_{\infty}$ controller. First, the model reference control stabilizes the motion of the manipulator. Then, the motion of the manipulator follows that of the reference model. Second, the $H_{\infty}$ control minimizes errors generated from the model reference control due to noise and disturbance since the $H_{\infty}$ control is a kind of robust control. The experiments of position control and tracking control are carried out by use of the proposed controller under the conditions of free disturbances and forced disturbances. Also, the experiments using PID controller are carried out under the same conditions. The results from above two controllers are compared to investigate the control performances. As the results, it is observed that the proposed controller has similar position accuracy but better tracking performances comparing to the PID controller as well as good disturbance rejection effect due to the robust characteristics of the controller. In conclusion. it is verified that the proposed controller has the simple control structure, the good tracking performances and good disturbance rejection effect due to the robust characteristics of the controller.

본 연구의 목적은 전자 퍼포먼스 트래킹 시스템(EPTS)의 GPS, LPS, IMU 센서, 영상추적(VID) 기기를 활용하 여 무용 동작을 정량화하여 과학적인 무용 평가 방법을 모색하며, 무용수의 부상 방지 예측 모델의 적용 가능성을 제시하는 데 있다. 연구 결과는 무용의 객관적인 평가를 위한 척도로 역동성, 연속성, 균형성의 요인을 EPTS의 LPS와 IMU 센서를 활용하여 정량적인 데이터를 측정할 수 있으며, 이를 통해 무용수의 움직임을 비교 및 평가할 수 있다. 또한, 무용수들이 훈련 및 경기에서 측정되는 가속, 감속, 방향전환, 점프 그리고 Playerload의 횟수를 주간 단위로 운동량을 계산하여, 부상 발생률(ACPR)을 확인하고 과 훈련으로 인한 상해를 방지할 수 있다.

The purpose of this study is to investigate the objective and the scientific evaluation method of dance using Electronic Performance Tracking System (EPTS) and to suggest the applicability of predictive model of injury prevention of dancers. The results of this study can be used to measure quantitative data using EPTS's LPS and IMU sensors. Dancers can also be calculated the number of high-strength accelerations, decelerations, Chang of Direction, jumps and playerload measured in training and competitions as momentum per week to check the incidence of injury (ACPR) and prevent injury from over-training.

A lunar lander demonstrator developed for the purpose of demonstrating lunar landing technologies recently in Korea. The thruster control system of the lunar lander demonstrator adopted the main thrusters for altitude control and the reaction thrusters for attitude control. In this paper, we propose a path tracking controller base on Euler angles. The control signals of the controller are of continuous type. And Pulse Width Modulator(PWM) is adopted to provide On/Off signals. We perform MATLAB simulation for evaluating the path tracking performance and the final landing velocity of the lunar lander demonstrator.

본 논문에서는 cross-eye의 두 재밍 안테나의 진폭 불일치로 인한 성능 저하를 고려한다. 진폭비의 불일치 는 기계적 결함에 따른 실제 진폭비와 명목상 진폭비의 차이가 정규분포를 갖는 랜덤변수로 모델링한다. 1차 테일러 전개와 2차 테일러 전개를 통한 해석적 성능분석이 제안된다. 실제 진폭비와 명목상 진폭비의 불일치가 발생한 Cross-eye 재밍의 성능 측정은 mean square difference (MSD)를 계산함으로서 측정된다. 해석적으로 유도된 MSD는 1차 테일러 전개 기반 시뮬레이션 기반 MSD 및 2차 테일러 전개 기반 시뮬레이션 기반 MSD와 해석 기반 MSD와 비교함으로써 검증된다. 계산비용이 높은 Monte-Carlo기반 MSD보다 해석 기반 MSD가 우수함을 보인다.

In this paper, performance degradation in the cross-eye jamming due to amplitude mismatch of two jamming antennas is considered. The mismatch of the amplitude ratio is modeled as a random variable with a normal distribution of the difference between the actual amplitude ratio and the nominal amplitude ratio due to mechanical defects. In the proposed analytic performance analysis, the first-order Taylor series expansion and the second-order Taylor series expansion is adopted. Performance measure of the cross-eye jamming is the mean square difference (MSD). The analytically derived MSD is validated by comparing the analytically derived MSD with the first-order Taylor series-based simulation-based MSD and the second-order Taylor series-based simulation-based MSD. It shows that the analysis-based MSD is superior to the Monte-Carlo-based MSD, which has a high calculation cost.

In this paper, code tracking loop was designed and the timing tracking performance of 1st order and 2nd order Delay-Locked Loop(DLL) for S-CDMA cable modem was evaluated in impulse, AWGN, and frequency offset channel environment. The designed 1st order DLL showed insufficient tracking performance in severe impulse noise or large frequency offset. On the other hand, the designed 2nd order DLL of loop gain G1=0.8, G2=0.01 showed good tracking performance with noticeable reduction of jitter.

Nowadays, the improvement and development of Multi-media and information & communication technology is rapidly processed. They need large data storage capacity. So that, many studies and researches in data storage have been carried out. According to them, the data storage capacity has been increased. But the limitation of storage capacity is happened for several problems. One of them is spot & pit size in optical and magnetic data storage and another is the resolution of actuators. The problems in spot & pit size are covered by new data storage methods-- for examples, AFM(Atomic Force Microscopy), MO(Magneto-optical) system, and NFR(Near-Field decoding) system etc. But the resolution limit of an actuator was not developed and doesn\`t follow up the development of spot & pit size. Because of them, we should improve a resolution of an actuator. Especially, in this paper an actuator if studied and designed for NFR (in using SIL(Solid Immersion Lens) system. It is a dual stage actuator, which consists of a Fine actuator and a Coarse actuator. and should desire 100nm accuracy. Its actuating force generation method is VCM(Voice Coil Motor). The Fine actuator is composed of 4-leaf springs and a bobbin wrapped by coil. The Coarse actuator has Coils and 3-Roller bearings. Also, The Characteristics of designed actuator for NFR system is estimated by Sine-Swept mode and LDV(Laser Doppler Vibro-meter).

The tracking trainer is an equipment for practicing every step of firing missile, targeting either a real target or a virtual target with the IR source in the field. The main components of the tracking trainer are the training missile round, dummy BCU, battery pack, and battery charger. The tracking practice missile is equipped with a controller instead of a warhead, and a propulsion and ejection motor. The launcher system for the tracking trainer is the same as the actual launcher system; the size, shape, electronic and mechanical interface are exactly the same as the actual equipment. This paper shows that the previously researched cooled type tracking missile has limitations in its tracking range and is inadequate for repeated practice, especially under unusual environments. This study suggests some improvements in the range of the cooled type tracking missile so that it could be used more repeatedly. The main configurations of Chiron consist of missiles in container, launcher system, tracking trainer, simulator, and mobile maintenance equipment. In this paper, we adopt an un-cooled type seeker for the tracking trainer so that it does not require nitrogen gas injection for operation. As the consequence, the system has become very cost effective. The controller which shows the status of tracking training is also designed to be integrated into the missile for more convenient operation.

The efficiency a solar cell system us mainly affected by the solar incident angle on the photovoltaic panels. The purpose of this thesis is to investigate a solar light-tracking BIPV system as the applicability on the educational facilities. Two typical types of BIPV system by operating system; fix PV panel type and rotating PV panel type, are analyzed in the performance of electric power generation and compared with solar light-tracking BIPV system. The simulation of solar irradiance is performed using ECOTECT, which has various advantage such as easy user interface and simple simulation processes. In order to evaluate the electric power generation efficiency, the electric power generation rate and global irradiation were measured on the spring/autumn equinox and the summer/winter solstice. As a result, the generation of solar power by solar light-tracking BIPV system shows 6.7% higher than fix-PV panel system. Meanwhile the generation of solar power by rotating PV system shows 1% higher than fix-PV panel system. Therefore, the solar light-tracking BIPV system will be an effective solution to develop for the zero energy building in educational facility.

일반적인 위성 항법 장치 수신기는 루프 필터 기반의 스칼라 추적 루프를 통해 신호 추적이 이루어진다. 본 논문에서는 루프 필터를 LQG 제어기로, 스칼라 추적 루프를 벡터 추적 루프로 대체한 LQG 기반 벡터 추적 루프의 성능을 정확성과 강건성 측면에서 살펴보았다. 정확성을 판단하기 위해서, 일반적인 루프 필터 기반 스칼라 추적 루프 대비 LQG 기반 스칼라 추적 루프의 측정치 추정 오차가 60% 이상 향상됨을 확인하였다. 다음으로 LQG 기반 스칼라 추적 루프 대비 LQG 기반 벡터 추적 루프의 측정치 추정 오차의 성능 향상과 위성 개수 증가에 따른 위치/속도 추정 오차 성능 향상을 확인함으로써 정확성을 확인하였다. 마지막으로 4초 동안의 30 dB-Hz의 일시적 신호 감쇄 상황에서 루프 필터 기반의 스칼라 추적 루프는 신호 추적에 실패하는 반면, LQG 기반 벡터 추적 루프는 연속적으로 위치/속도, 측정치 추정이 가능함을 확인함으로써 강건성을 확인하였다.

Generally, loop filter based scalar tracking loops (LF-STL) have been used for global positioning system (GPS) signal tracking algorithm. This paper introduces the accuracy and robustness of linear-quadratic-Gaussian based vector tracking loop (LQG-VTL) algorithm instead of LF-STL. To verify the accuracy of LQG-VTL, we confirm that the measurements estimation errors of the LQG based scalar tracking loops (LQG-STL) are improved by more than 60 % compared to LF-STL. Also, when LQG-VTL is used, measurements estimation errors decrease compared to LQG-STL, and position/velocity estimation errors also decrease as the number of satellites increases. To verify the robustness of LQG-VTL, we confirm that LQG-VTL can estimate position/velocity and measurements successively compared to LF-STL in temporal signal attenuation of 30 dB-Hz during 4 seconds.

레이다의 주요 성능 규격 중 하나인 거리 분해능은 동일한 속도 및 각도의 두 표적을 거리 상으로 분해할 수 있는 성능과 관련된 지표이다. 일반적으로 레이다 성능 규격에 정의된 분해능은 실제 두 표적 분해 관점이 아닌 송신 펄스 폭으로 정의된다. 송신 펄스 폭 수치는 설계 측면의 성능 규격일 뿐, 두 표적을 분해할 수 있는 최소 거리를 의미하는 것이 아니다. 본 논문에서는 송신 펄스폭과 레이다 알고리즘을 동시에 고려하여 동일한 속도 및 각도 정보를 가지는 두 신호가 거리 차이로 분해되어 개별 추적개시로 이어질 수 있는 최소 거리차이에 대해 분석한다. 분해능 이외의 다른 외부 간섭을 배제하기 위해 비콘(Beacon) 신호를 활용한 루프랩 (Roof-lab) 환경에서 지상시험을 수행하였고, 탐지 단계에서는 신호처리 알고리즘에 의해 개별 탐지 성능이 결정되고, 추적 형성 단계에서는 데이터 연관을 통한 중복성 검사 알고리즘에 의해 분해 성능이 결정되는 것을 확인하였다.

Range resolution is the ability to distinguish different targets placed in same angular direction but at different distances from the radar. Normally, Range resolution requirement is defined as the width of transmitting pulse. The width of transmitting pulse does not mean the ability to distinguish two different targets. Range resolution performance to detect and track targets separately depends on the signal processing and tracking algorithm not only the width of transmitting pulse. This paper analyzes the processing steps in algorithms to affect the range resolution performance and verifies the results by roof-lab ground test using beacon signal. As a result, to track targets with the same angular position separately, it is desirable to have larger range difference than plot-track association test gate.

본 연구는 야구에서 타자의 타격 성과를 예측하기 위한 배트 트래킹 지표와 기존 타격 지표 간의 상관관계를 비선형 회귀분석을 통해 분석하고 해석하는 데 중점을 두었다. MLB Statcast가 제공한 데이터를 바탕으로 평균 배트 스피드, 정타율, 블래스트, 스윙 길이와 타자의 주요 성과 지표인 안타 수, 홈런 수, 타율, 장타율, OPS 간의 관계를 분석하였다. 분석 결과, 정타율은 안타 수에 대해 양의 영향을 미쳤으며, 블래스트는 안타 수와 장타율에 큰 음의 영향을 미쳤다. 특히 홈런 수와 OPS의 경우, 블래스트와 정타율 간의 상호작용이 매우 중요했으며, 이들의 결합은 홈런 수와 OPS에 각각 긍정적인 영향을 나타냈다. 본 연구는 배트 트래킹 지표와 타격 지표 간의 복잡한 상호작용을 명확히 이해 함으로써, 타자의 타격 성과를 보다 정확하게 예측하는 데 중요한 통찰을 제공하며, 이는 야구 분석 및 선수 평가에 실질적인 기여가 가능할 것이다. 또한, 이러한 분석을 통해 배트 트래킹 데이터가 기존 타격 지표와 어떻게 상호작용하 는지를 심층적으로 이해하는 데 중요한 기초 자료를 제공하고, 야구 선수의 평가에 새로운 시각을 제시할 수 있다.

This study focuses on analyzing and interpreting the relationship between Bat Tracking metrics and traditional hitting metrics using non-linear regression analysis to predict baseball batter performance. Based on data provided by MLB Statcast, we analyzed the relationships between Average Bat Speed, Squared-up Rate, Blast, Swing Length, and key performance indicators such as Hits, Home Runs, Batting Average, Slugging Percentage, and OPS. The analysis revealed that Squared-up Rate had a significant positive impact on Hits, while Blast showed a substantial negative impact on both Hits and Slugging Percentage. In the case of Home Runs and OPS, the interaction between Blast and Squared-up Rate was crucial, showing positive effects. This study provides important insights into understanding the complex interactions between Bat Tracking metrics and hitting metrics to more accurately predict batter performance, offering practical contributions to baseball analytics and player evaluation.

In particle filter framework, there are many parameters need to be set to have the object tracking work best. On the other hand, the success of an object tracking is also determined by the characteristics of the video being used. Different videos might require different values of parameters to obtain best performance. This paper investigates thoroughly the effect of parameters in object tracking within particle filter framework for videos with different characteristics. We also propose a new method in selecting particle number and matrix value that used in propagation model. This work finds best parameters for video with particular characteristics and contributes in providing guideline of parameter setting in particle filter-based object tracking.