• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.12
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• pp.965-971
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• 2003

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. For this system. we have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce milliactuator and controller design method, PQ method. PQ method reduces the controller design problem for DISO (dual-input/single-output) systems to two standard controller design problems for SISO ( single-input/single-output) problems. The first part of PQ method directly addresses the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.174-185
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• 2005

This paper presents the design, fabrication, and testing results of a dual stage actuator system for a fine positioning of magnetic heads in magnetic disk drives. A novel rotary microactuator which is electrostatically driven and utilized as a secondary actuator was designed. The stator and rotor electrodes in the microactuator was revised to have the optimal shapes and hence produces much higher rotational torque compared with the conventional comb-shape electrodes. The microactuators were successfully fabricated using SoG(silicon on glass) processing technology, which is known as being cost-effective. The fabricated microactuator has the structural thickness of $45{\mu}m$ with the gap width of approximately $3{\mu}m$. The dynamic characteristic of microactuator/slider assembly was investigated, and its natural frequency and DC gain were measured to be 3.4kHz and 32nm/V, respectively. The microactuator/slider assembly was integrated into a HDD model V10 of Samsung Electronics Co. and a dual servo algorithm was tested to explore the tracking performance of dual stage actuator system where the LDV signals instead of magnetic head signals were used. Experimental results indicate that this system achieves the tracking accuracy of 30nm. This value corresponds to a track density of 85,000 track per inch(TPI), which is about 3 times greater than that of current hard disk drives.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.2
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• pp.165-170
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• 2002

In order to solve the problem of system efficiency reduced on account of two stage power conversion, we propose a series resonant full bridge Inverter circuit for battery-fed microwave oven. This circuit has both a compact size and a light weight comparing with the conventional HVT(High Voltage Transformer) method. Also, it may be adjusted power levels of the microwave oven by a frequency control. In this paper, operational principles are explained in detail in order to understand the circuit operation. Also, a proto-type Inverter circuit with 1[kW] Power consumption is built and tested for verifying the operation.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1651-1654
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• 2004

파이프라인과 슈퍼스칼라 방식이 일반화된 시스템 구조 하에서, 분기 명령어는 시스템 전체적인 성능에 중요한 영향을 미친다. 특히 분기 예측이 실패했을 경우, 잘못된 분기 예측으로 인한 페널티가 발생한다는 점에서 분기 예측의 정확도에 대한 중요성은 크다고 할 수 있다. 본 논문에서는 분기 예측의 정확도를 높이기 위해서, 분기 예측과 관련된 신경망을 구축하여 이를 통해 분기 예측에 필요한 각 요소별 가중치의 변화를 분석하고, 이를 분기 예측에 새롭게 반영하고자 한다. 본 논문에서는 이를 위해 실행 구동 방식의 시뮬레이터인 SimpleScalar를 통하여 모의 실험을 수행하였으며, 실험 결과 본 논문에서 제시한 새로운 기법이 기존의 일반적인 이단계 적응형 분기 예측 기법이나 gshare 기법에 비하여 더 우수한 결과를 보였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.72-75
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• 2012

In this paper, high-efficiency DC-AC converter is implemented for the wireless power transmission. The DC-AC converter is implemented by combining the oscillator and power amplifier. Because the conversion efficiency of wireless power transmitter is strongly affected by the efficiency of power amplifier, the high-efficiency power amplifier is implemented by using the Class-E amplifier structure. Also, because the output power of oscillator connected to the input stage of power amplifier is low, high-gain two-stages power amplifier using the drive amplifier is implemented to realize the high-output power DC-AC converter. The dual band harmonic suppression filter is implemented to suppress 2nd, 3rd harmonics of 13.56 MHz. The output power and conversion efficiency of DC-AC converter are 40 dBm and 80.2 % at the operation frequency of 13.56 MHz.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.1
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• pp.9-26
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• 2005

In the pursuit of ever higher levels of performance, recent computer systems have made use of deep pipeline, dynamic scheduling and multi-issue superscalar processor technologies. In this situations, branch prediction schemes are an essential part of modem microarchitectures because the penalty for a branch misprediction increases as pipelines deepen and the number of instructions issued per cycle increases. In this paper, we propose a novel branch prediction scheme, direction-gshare(d-gshare), to improve the prediction accuracy. At first, we model a neural network with the components that possibly affect the branch prediction accuracy, and analyze the variation of their weights based on the neural network information. Then, we newly add the component that has a high weight value to an original gshare scheme. We simulate our branch prediction scheme using Simple Scalar, a powerful event-driven simulator, and analyze the simulation results. Our results show that, compared to bimodal, two-level adaptive and gshare predictor, direction-gshare predictor(d-gshare. 3) outperforms, without additional hardware costs, by up to 4.1% and 1.5% in average for the default mont of embedded direction, and 11.8% in maximum and 3.7% in average for the optimal one.