• Advances in materials Research
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• v.13 no.1
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• pp.1-18
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• 2024

The present experimental investigation focuses on finding optimal parametric data-set of laser micro-drilling operation with minimum taper and Heat-affected zone during laser micro-drilling of Carbon Nanotube/Epoxy-based composite materials. Experiments have been conducted as per Box-Behnken design (BBD) techniques considering cutting speed, lamp current, pulse frequency and air pressure as input process parameters. Then, the relationship between control parameters and output responses is developed using second-order nonlinear regression models. The analysis of variance test has also been performed to check the adequacy of the developed mathematical model. Using the Response Surface Methodology (RSM) and an Accelerated particle swarm optimization (APSO) technique, optimum process parameters are evaluated and compared. Moreover, confirmation tests are conducted with the optimal parameter settings obtained from RSM and APSO and improvement in performance parameter is noticed in each case. The optimal process parameter setting obtained from predictive RSM based APSO techniques are speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), Air pressure (1 kg/cm²) for Taper and speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), air pressure (3 kg/cm²) for HAZ. From the confirmatory experimental result, it is observed that the APSO metaheuristic algorithm performs efficiently for optimizing the responses during laser micro-drilling process of nanocomposites both in individual and multi-objective optimization.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.575-578
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• 2004

The performance of an active power filter(APF) depends on the inverter characteristic, the control method, and the accuracy of reference signal generator. The accuracy of reference generator is the most critical item to determine the performance of active power filter. This paper introduces a novel reference signal generator composed of improved adaptive predictive filter. The performance of proposed reference signal generator was first verified through a simulation with MATLAB. Furthermore, the application of feasibility was evaluated through experimenting with a single-phase APF prototype based on the proposed reference generator, which was implemented using the TMS320C31 floating-point signal processor. Both simulations and experimental results confirm that our reference signal generator can be used successfully in practical active power filters.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.719-723
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• 1998

Prevention of the islanding phenomena is one of the most important issues because it can damage electrical equipment connected to the utility system and endanger human life. It is very difficult to detect an islanding condition of a power distribution line with conventional voltage of frequency relays, while the output power and the load power of utility interactive PV inverter units are in nearly balanced state in both active power and reactive power. This paper describes the protective equipment that prevents the PV system connected to the utility grid from starting islanding. Both predictive ocntrol method and harmonic injection method are used for a current control and islanding detection for operating safety.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.410-411
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• 2010

풀 브릿지 컨버터는 1차 측과 2차 측이 트랜스포머를 통하여 절연되어 있으며, 이 트랜스포머에 교번으로 전압을 걸어주어 1주기에 2번의 전력을 전달한다. 이러한 전력 전달 과정에서 트랜스포머에 흐르는 자화 전류에 오프셋이 발생할 수 있으며, 이는 효율 감소 및 소자의 파괴를 야기할 수 있으므로 제거하는 것이 바람직하다. 디지털 개발 환경에서 트랜스포머의 자화 전류 오프셋을 줄이고 동특성의 개선을 위하여 예측 제어 방식을 사용한 최대 전류 제어 방식을 제안하고 실험을 통하여 동작을 검증한다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.757-762
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• 2000

This paper presents a digital controller for three-phase Boost Converter. Generally, the conventional Space-Vector Pulse Width Modulation (SVPWM) have complex computation. Thereby, it should be implemented with high performance processor. In order to reduce calculation burden of the conventional SVPWM, digital controller which has a simplified SVPWM algorithm is designed in this study. A proposed digital controller consists of fuzzy pwm controller and prediction controller. In simulations and experiments, the proposed digital controller is validated.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.140-143
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• 2002

위상제어 정류기 시스템에서 예측전류제어는 전류 응답속도가 매우 빠르고 오버슈트가 없는 것으로 알려져 있다. 하지만 전원과 부하의 전압 전류방정식에 의존하는 예측전류제어는 부하 파라메터 값이 틀릴 경우 전류지령 값과 피드백 사이에 정상상태 오차를 보이게 된다. 본 논문에서는 디지털 순시치 샘플링과 최소자승법을 이용하여 온라인으로 부하의 파라메터를 추정하는 알고리즘을 제안하였고, 이를 이용하여 예측전류제어를 수행함으로써 빠르고 정밀한 전류제어응답을 보였다.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.213-214
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• 2018

본 논문에서는 전기자동차 온-보드 충전기용 단상 cycloconverter-type high frequency link 컨버터의 전력 제어성능과 동적 응답특성을 개선하기 위하여 예측전류제어 기법을 적용한다. 배터리를 충전 및 방전하기 위하여 전력계통에 연결되는 V2G 충전기는 전압 변동, 고조파 왜곡 등의 외란 발생에도 강인한 동적 응답 특성을 유지하여야 한다. 예측전류제어 기법이 적용된 제어기는 계통 외란이 존재하는 경우에도 전력 레퍼런스를 빠르게 추적하고 정확한 듀티를 생성할 수 있으므로 우수한 동적 및 과도 응답특성을 갖는다. 제안하는 제어기의 성능과 파라미터 변동에 대한 민감도는 PSIM 시뮬레이션을 이용하여 평가되며, 여러 계통외란 상태에서 PI 제어기와 비교된다.

• Current Optics and Photonics
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• v.5 no.6
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• pp.641-651
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• 2021

To handle the servo delay in a real-time adaptive optics system, a linear subspace system identification algorithm was employed to model the system, and the accuracy of the system identification was verified by numerical calculation. Experimental verification was conducted in a real test bed system. Through analysis and comparison of the experimental results, the convergence can be achieved only 200 times with prediction and 300 times without prediction. After the wavefront peak-to-valley value converges, its mean values are 0.27, 4.27, and 10.14 ㎛ when the communication distances are 1.2, 4.5, and 10.2 km, respectively. The prediction algorithm can effectively improve the convergence speed of the peak-to-valley value and improve the free-space optical communication performance.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.585-588
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• 2019

Predictions of Energy Consumption for Industries gain an important place in energy management and control system, as there are dynamic and seasonal changes in the demand and supply of energy. This paper presents and discusses the predictive models for energy consumption of the steel industry. Data used includes lagging and leading current reactive power, lagging and leading current power factor, carbon dioxide (tCO2) emission and load type. In the test set, four statistical models are trained and evaluated: (a) Linear regression (LR), (b) Support Vector Machine with radial kernel (SVM RBF), (c) Gradient Boosting Machine (GBM), (d) random forest (RF). Root Mean Squared Error (RMSE), Mean Absolute Error (MAE) and Mean Absolute Percentage Error (MAPE) are used to measure the prediction efficiency of regression designs. When using all the predictors, the best model RF can provide RMSE value 7.33 in the test set.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.325-334
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• 2015

This paper deals with a control method for a hybrid energy storage system (ESS) with a battery and super capacitor for grid-connected operation. To improve the grid regulation and to minimize the depth of discharge of the battery, control algorithms for the hybrid ESS are proposed. A p-q control with predictive current control is used for the inverters for the super-capacitor and the battery. To verify the effectiveness of the proposed control method, simulation studies using the PSIM and RTDS are carried out for the actual grid model.