• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.267-268
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• 2012

본 논문에서는 3상 계통연계형 배터리 충전기의 전류리플 발생 원인을 분석하고 보상하는 기법을 제안한다. 배터리 전류리플의 요소로는 전류 측정 시 발생하는 오차에와 데드타임에 의해 각각 기본파, 2고조파, 6고조파 성분이 발생한다. 배터리 전류의 리플 성분은 배터리 수명을 저하시키는 요소 중 하나로 리플 성분을 보상하여 그 크기를 줄이는 알고리즘이 필요하다. 배터리 전류 리플 성분의 발생은 시뮬레이션과 실험을 통해 확인하였고, 공진형 전류제어기를 사용하여 특정 고조파에 해당하는 리플 성분을 보상하여 배터리 전류의 리플을 보상하는 알고리즘을 적용하여 배터리의 리플 성분이 감소함을 확인하였다.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.9-17
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• 2018

For Earth observation, a small satellite camera has relatively weak structural stability compared to medium-sized satellite, resulting in misalignment of optical components due to severe launching and space environments. These alignment errors can deteriorate the optical performance of satellite cameras. In this study, we proposed a 3-axis focus mechanism to compensate misalignment in a small satellite camera. This mechanism consists of three piezo-electric actuators to perform x-axis and y-axis tilt with de-space compensation. Design requirements for the focus mechanism were derived from the design of the Schmidt-Cassegrain target optical system. To compensate the misalignment of the secondary mirror (M2), the focus mechanism was installed just behind the M2 to control the 3-axis movement of M2. In this case, flexure design with Box-Behnken test plan was used to minimize optical degradation due to wave front error. The wave front error was analyzed using ANSYS. The fabricated focus mechanism demonstrated excellent servo performance in experiments with PID servo control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.221-228
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• 2020

A sonobuoy is dropped onto the surface of water to estimate the bearing of an underwater target. A Directional Frequency Analysis and Recording (DIFAR) sonobuoy has an error in the specific angular section due to the method of estimating bearing and noise, which causes an error in target localization using multiple sonobuoys. In addition, the position of the sonobuoy continues to move, but since a sonobuoy with a GPS is intermittently arranged, it is difficult to estimate the exact position of the sonobuoy. This also causes target localization performance degradation. In this paper, we propose a technique to improve the target localization performance by compensating for bearing errors using characteristics of the DIFAR sonobuoy and multiple-sonobuoy position errors based on the intermittently arranged active sonobuoy with a GPS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1685-1690
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• 2014

This paper proposes a novel method to compensate for the measurement errors in detecting phase currents for vector-controlled inverter in real-time. The output torque equations for 3-phase induction motor are derived in terms of offset error and transducing gain error in current measurement circuits, and the equations shows that motor output torque has many ripples due to current measurement errors. Especially, if the proposed method is applied to vector-controlled inverter, the torque ripple by transducing gain error can be reduced in real-time at running state of motor. To verify the proposed method, it was applied to vector-controlled inverter for 3-phase induction motor of 200[W] and computer simulation and experimentation were carried out.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.1
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• pp.1-8
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• 2011

The accuracy of MR sensor-based electronic compass is influenced by the temperature drift and DC offset of the MR sensor and the OP-amp, the magnetic distortion of nearby magnetic materials, and the compass tilt We design the 3-axis MR sensor and accelerometers-based electronic compass which is compensated by the set/reset pulse switching method on the temperature drift and DC offset, by the execution of hard-iron calibration routine on the magnetic distortion, and by the execution of the Euler rotational equation on the compass tilt. We qualitatively analyze the measured azimuth error on the execution of sensitivity calibration routine which is the normalization process on the different sensitivity of each MR sensor and the different gain of each op-amps. This compensation and analytic result make us design the one degree accuracy electronic compass.

• The Journal of the Acoustical Society of Korea
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• v.38 no.6
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• pp.630-636
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• 2019

Passive Ranging Sonar (PRS) is a type of passive sonar consisting of three sub-array on the port and starboard, and has a characteristic of detecting a target and calculating a bearing and a distance. The bearing and distance calculation requires physical sub-array position information, and the bearing and distance accuracy performance are deteriorated when the position information of the sub-array is inaccurate. In particular, it has a greater impact on distance accuracy performance using plus value of two time-delay than a bearing using average value of two time-delay. In order to improve this, a study on sub-array position error estimation and error compensation is needed. In this paper, We estimate the sub-array position error based on enetic algorithm, an optimization search technique, and propose a method to improve the performance of distance accuracy by compensating the time delay error caused by the position error. In addition, we will verify the proposed algorithm and its performance using the sea-going data.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.1
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• pp.1-8
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• 2004

The INS(Inertial Navigation System) provides high rate position, velocity and attitude data with good short-term stability while the GPS(Global Position System) provides position and velocity data with long-term stability. By integrating the INS with GPS, a navigation system can be achieved to Provide highly accurate navigation Performance. For the best performance, time synchronization of GPS and INS data is very important in GPS/INS integrated system But, it is impossible to synchronize them exactly due to the communication and computation time-delay. In this paper, to reduce the error caused by the measurement time-delay in GPS/INS integrated systems, error compensation methods using separate bias Kalman filter are suggested for both the loosely-coupled and the tightly-coupled GPS/INS integration systems. Linearized error models for the position and velocity matching GPS/INS integrated systems are Int derived by linearizing with respect to its time-delay and augmenting the delay-state into the conventional state equations for each case. And then separate bias Kalman Inter is introduced to estimate the time-delay during only initial navigation stage. The simulation results show that the present method is effective enough resulting in considerably less position error.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.547-555
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• 2008

This parer proposed the path mismatch detection and compensation algorithm with closed form for linear amplification with non-linear components(LINC) system implementation. The LINC system has a merit of using the high efficient amplifier by transferring the non-constant envelop signal which is high peak to average signal ratio into constant envelop signal. However, the performance degradation is very sensitive to the path mismatch such as an amplitude mismatch and a phase mismatch. In order to improve the path mismatch, the error detection and compensation method is introduced by the use of four test signals. Since the presented method has the closed form solution, the efficient and fast detection is available. The digital-IF structure of LINC system applied by the proposed error detection and compensation algorithm was implemented. The performance was evaluated with the IEEE 802.16 WiMAX baseband sinal which has 7 MHz channel bandwidth and 16-QAM. The Error Vector Magnitude(EVM) of -37.37 dB was obtained through performance test, which meets performance requirement of -24 dB EVM. As a result, the introduced error detection and compensation method was verified to improve the LINC system performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.283-287
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• 1997

공작기계의 가공정도는 공작기계의 운동기구가 가지고 있는 기하오차와 절작작업시 발생하는 진동, 열,절삭력에 의해서 공작기계의 구조계,주축계,이송계의 변형에 의해서 직접적인 영향을 받는다. 또 가공정도는 제품의 정밀도 및 품질에 직접적인 영향을 미치기 때문에 가공정도를 향상시키기 위한 방법으로 공작기계의 오차를 측정/해석하는 방법이 연구되고 있다. 일반적으로,공작기계의 오차는 Quasi-static 오차와 Dynamic오차로 구분할수 있다. Dynamic 오차는 기계의 진동,채터 및 스핀들의 진동에 의해서만 발생하는 오차이며,Quasi-static 오차는 공작기계 구성요소인 안내면,칼럼,볼스크류등의 기하오차와 온도변화에 의한 열변형오차에 의해서 발생한다. 특히,공작기계 및 절삭가공중에 발생하는 열원에 의한 열변형 오차는 공작기계의 기하오차에 비해서 가공정도에 큰 영향을 미치며[1,2],발생오차의 약 40~70% 정도가열변형 오차에 기인한 것으로 알려져 있다[1]. 실제 많은 실험결과를 볼 때 CNC공작기계이 경우는 열변형에 의한 오차는 기하오차에 비해서 매우 크게 나타났다. 이러한 열변형 오차는 공작기계 주위 온도와 공작기계 구성요소(칼럼,이송유니크,스핀들유니트)의 비선형적인 온도 특성에 의해서 주로 발생하고, Time-variant특성을 가지고 있기 때문에 작업중에 발생하는 온도특성에 따른 열변형 오차를 최소화 할 수 있는 방법이 필요하다. 스핀들유니트는 냉각방식을 사용하여 온도변화를 줄이고 있으나 반복적인 작업과 스핀들의 고속회전으로 인해서 복합 적인 온도변화를 발생시킨다. 또, 볼스크류의 지지방식이 양쪽 고정단 형태이기 때문에 조립시 예압(pre-load)을 주어서 열팽창을 보상하고 있으나 공작기계의 반복적인 이송으로 인해서 발생하는 온도변화에 의한 열오차를 보상하는데는 어려움이 있다.됩니다. 생리적 저항력이 없는 어린이들은 이러한 공해와 생활조건의 제일희생자가 되는 것입니다. 엄마들이 "얘는 감기, 비염, 편도선을 달고 삽니다...." "얘는 코감기, 목감기 번갈아 가면서 하도 앓고 있어서 양약율 중지하고 현재 한약을 먹고 있습니다." 이러한 역경은 극복할 수 있는가\ulcorner 질병의 메카니즘은 어떻게 작용되는가\ulcorner 등등을 육미회 센타에서 체험한 사례를 가지고 말씀드리고자 합니다..ell layer (PCL)와 glia에 SOD-1이 강하게 염색되었다. APT 병용 투여로 상당수의 경련이 일어나지 않은 흰쥐는 해마의 DG에 FRA가 경미하게 염색되었고, PCL에 SOD-1도 경미하게 나타났으나, 경련이 나타난 쥐에서는 KA만을 투여한 흰쥐와 구별되지 않았다. 이상의 APT의 항산화 효과는 KA로 인한 뇌세포 변성 개선에 중요한 인자로 작용할 것으로 사료되나, 보다 명확한 APT의 기전을 검색하고 직접 임상에 응응하기 위하여는 보다 다양한 실험 조건이 보완되어야 찰 것으로 생각된다. 항우울약들의 항혈소판작용은 PKC-기질인 41-43 kD와 20 kD의 인산화를 억제함에 기인되는 것으로 사료된다.다. 것으로 사료된다.다.바와 같이 MCl에서 작은 Dv 값을 갖는데, 이것은 CdCl$_{4}$$^{2-}$ 착이온을 형성하거나 ZnCl$_{4}$$^{2-}$ , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경우 Dv값이 제일 작았다. 바. 본 연구

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.551-557
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• 2006

The electrical frequency synchronized periodic torque ripple exits in the AC motor. There are various sources of torque ripple in AC motor such as current measurement error, dead time, etc. This paper proposes a compensation algorithm which suppresses undesired side effect known as the periodic torque ripple of AC motor. The torque ripple compensation classified as the speed ripple detector and torque ripple compensator. This paper proves a speed ripple minimization at steady state by analysis of torque ripple compensator. A new speed ripple detector improves the performance of torque ripple compensation algorithm. The simulation and experimental results show that the compensation algorithm is effective and the torque ripple compensation method improves the performance of speed ripple detector by eliminating torque ripples effectively.