• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.99-104
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• 2004

Micro/meso cutting is getting more important in the fields of precision machining technology. A micro-turning lathe is one of parts to consist the Micro Factory. It accepts stepwise motion actuators that are used for feeding system instead of the conventional mechanism. It is consisted of two Piezoelectric ceramics; one is for feeding the slider, and the other is for clamping the slider in the guide way of the body. The linearity and positional accuracy of the actuators are good enough for high precision motion. The spindle unit is operated with DC motor on the top of the slider. The motion is communicated with miniaturized linear encoder attached on each side of axis. A mono crystal diamond tool is used for cutting tool. This micro-lathe has been made a machining experiment to see the characteristics of micro-machining.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.358-362
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• 2004

Higher productivity requires high-speed motion of machine tool axes. The iron core linear DC motor (LDM) is widely accepted as a viable candidate for high-speed machine tool feed unit. LDM, however, has two inherent disturbance force components, namely cogging and thrust force ripple. These disturbance forces directly affect the tracking accuracy of the feeding system and must be eliminated or reduced. In order to reduce motor ripple, this research adapted the feedforward compensation method and neural network control. Experiments carried out with the linear motor test setup show that these control methods are effective in reducing motor ripple.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.244-247
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• 1999

This paper presents a methodology of the technique for controlling DC motor drive by implementation of 2-quadrant operating mode which can ensure the torque controlling and speed with response time less than 2 seconds at all loading conditions. By implementation of BRM technique, energy is fed with definite values of BRM 256 bits, with different patterns of high accuracy, and fixing scan time at 0.667 ms, the ripple is less than 1%, thus high efficiency can be achieved, from the consequence of the accuracy of energy feeding at low current. The stability of the whole system can be determined from circle criterion by root locus method . The instant reverse direction of rotation can be done by decreasing the energy to the lowest level while motor is running with no load and variable load at the speed about 100-120 rpm and 50-60 rpm.

• 조명전기설비학회논문지
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• 제24권6호
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• pp.138-146
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• 2010

본 논문은 직류 전기철도 급전시스템에서 레일전위와 누설전류의 분석 기법을 제시하였다. 일반적으로 직류 전기철도 급전시스템에서는 운행용 레일을 귀로 전류(부극성)의 도체로 사용하고 있으므로 레일전위가 발생하고, 특히 차량 운행용 레일과 대지사이의 저항이 작은 경우에는 대지로 흐르는 누설전류가 문제가 된다. 이 레일전위 및 누설전류는 레일 주변에 설치된 지하 매설물에 영향을 미치며, 인체의 안전과도 관련이 있다. 이에 따라 직류 전기철도 급전시스템에서 레일전위와 누설전류를 억제하는 것은 전기철도 주변 환경 및 안전 측면에서 중요한 문제이다. 이상과 같은 관점에서, 직류 전기철도 급전시스템에 대하여 단독급전 및 병렬급전 상황에서 레일전위와 누설전류를 계산할 수 있는 알고리즘을 제안하였으며, 또한 열차주행시뮬레이션(TPS)과 연동하여 열차주행에 따라 부하전류가 변동되는 상황에서 레일전위와 누설전류를 정량적으로 분석할 수 있도록 하였다. 제안한 알고리즘을 이용하여 시뮬레이션 프로그램을 개발하였고, 직류전기철도 급전시스템에 대하여 사례 연구를 수행하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.333-334
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• 2016

This paper proposes a new cascoded configuration for hybrid energy storage system (HESS) which consists of batteries and supercapacitor (SC) for Electric Vehicle applications. In this configuration,a resonant LLC converter is interfacedin series with a battery module and it converts a part of the energy from the batteries and transfer it to the dc-link bus. The LLC converter is controlled by a phase-shift angle between the primary and secondary switches to maintain a constant dc-link voltage and obtain soft-switching conditions for all the primary switches. By placing the SC moduleina cascoded concept, the rated voltage of SC can be reduced significantly compared with the conventional topologies. It helps save the cost and reduce the number of SC cells. The proposed configuration can operate with four different modes: feeding load, acceleration, regenerative braking andSC charging. A scaled-down prototype converter (2 kW, 600V output) is designed and tested to verify the advantages of the proposed topology. The maximum efficiency obtained with the proposed topology is 99%.

• International Journal of Computer Science & Network Security
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• 제22권4호
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• pp.1-12
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• 2022

In order to overcome the power fluctuation issues in photovoltaic (PV) smart grid-connected systems and the inverter nonlinearity model problem, an adaptive backstepping command-filter and a double second order generalized Integrators (DSOGI) controller are designed in order to tune the AC current and the DC-link voltage from the DC side. Firstly, we propose to present the filter mathematical model throughout the PV system, at that juncture the backstepping control law is applied in order to control it, Moreover the command filter is bounded to the controller aiming to exclude the backstepping controller differential increase. Additionally, The adaptive law uses Lyapunov stability criterion. Its task is to estimate the uncertain parameters in the smart grid-connected inverter. A DSOGI is added to stabilize the grid currents and eliminate undesirable harmonics meanwhile feeding maximum power generated from PV to the point of common coupling (PCC). Then, guaranteeing a dynamic effective response even under very unbalanced loads and/or intermittent climate changes. Finally, the simulation results will be established using MATLAB/SIMULINK proving that the presented approach can control surely the smart grid-connected system.

• Journal of Power Electronics
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• 제15권3호
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• pp.806-818
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• 2015

Based on the inherent relationship between dc-bus voltage and grid feeding active power, two dc-bus voltage regulators with different references are adopted for a grid-connected PV inverter operating in both normal grid voltage mode and low grid voltage mode. In the proposed scheme, an additional dc-bus voltage regulator paralleled with maximum power point tracking controller is used to guarantee the reliability of the low voltage ride-through (LVRT) of the inverter. Unlike conventional LVRT strategies, the proposed strategy does not require detecting grid voltage sag fault in terms of realizing LVRT. Moreover, the developed method does not have switching operations. The proposed technique can also enhance the stability of a power system in case of varying environmental conditions during a low grid voltage period. The operation principle of the presented LVRT control strategy is presented in detail, together with the design guidelines for the key parameters. Finally, a 3 kW prototype is built to validate the feasibility of the proposed LVRT strategy.

• 한국응용곤충학회지
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• 제55권4호
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• pp.351-358
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• 2016

DC-EPG 시스템을 활용하여 애멸구(Laodelphax striatellus) 암컷 성충이 벼를 섭식하는 동안 발생되는 전기적 신호를 기록하고 분석하여, 벼멸구에서 보고된 것(Seo et al., 2009)과 같은 방식으로, np, L1, L2, L3, L4-a, L4-b, L5의 7 개 EPG 파형으로 구별하였다. 파형들의 모양과 발생 패턴은 벼멸구(Nilaparvata lugens)와 매우 유사하였고, L4-b의 직전에는 반드시 L3와 L4-a가 연속된 순서로 나타났다. 감로는 L4-b에서 주기적으로 분비되었다. 레이저 stylectomy 후 섭식부분의 미세절편을 관찰한 결과, 애멸구 구침의 끝이 L3와 L4-a, L4-b에서는 벼의 체관부 근처 또는 체관부에서 관찰된 반면, L5에서는 물관부에서 관찰되었다. 레이저 stylectomy로 L4-b에서 잘려진 애멸구 구침의 절단부로부터 유일하게 벼수액이 용출되었고, HPLC로 분석된 수액 안의 당 성분으로 식물의 체관부 탄수화물 이동태인 설탕(sucrose)만이 검출되었다. 이상의 관찰 결과와 애멸구의 EPG 파형 전개 과정 분석을 통해, L1과 L2는 관다발 도달 전에 발생하는 구침을 찌르고 타액 분비가 동반된 구침의 이동 행동으로, L3와 L4-a는 체관부에서 섭식을 위해 사전에 준비하는 과정으로, L4-b는 체관부 수액을 흡즙하는 행동으로, 마지막으로 L5는 물관부에서 형성되는 섭식행동으로 벼멸구와 유사하게 결론지었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.343-346
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• 2003

In order to discuss the availability of the hydrostatic guideway driven by the coreless linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156 N and a laser scale with the resulution of 10 nm are used as the feeding system. The experiments are performed on the static stiffness. motion accuracy, positioning accuracy. microstep response and variation of velocity. The guideway has the infinite axial stiffness within 50 N of applied load, and has 0.08 ${\mu}{\textrm}{m}$ of linear motion error and 0.1 arcsec of angular motion error. It also has 0.21 ${\mu}{\textrm}{m}$ of positioning error and 0.09 ${\mu}{\textrm}{m}$ of repeatability, and it shows the stable response against the 10 nm resolution step command. The velocity variation of feeding system is less than 5%. From these results, it is confirmed that the hydrostatic guideway driven by the coreless linear motor is very useful for the ultra precision machine tools.

• 한국정밀공학회지
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• 제21권6호
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• pp.139-144
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• 2004

In order to discuss the availability of hydrostatic guideways driven by the coreless linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156 N and a laser scale with the resolution of 0.01 ${\mu}{\textrm}{m}$ are used as the feeding system. The experiments are performed on the static stuffiness, motion accuracy, positioning accuracy, microstep response and variation of velocity. The guideway has the infinite axial stillness within 50 N of applied load, and by the motion error compensation method using the Active Controlled Capillary, 0.08 ${\mu}{\textrm}{m}$ of linear motion error and 0.1 arcsec of angular motion error are acquired. The guideway also has 0.21 ${\mu}{\textrm}{m}$ of positioning error and 0.09 ${\mu}{\textrm}{m}$ of repeatability, and it shows the stable response against the 0.01 ${\mu}{\textrm}{m}$ resolution step command. The velocity variation of feeding system is less than 0.6 %. From these results, it is confirmed that the hydrostatic guideway driven by the coreless linear motor is very useful fur the ultra precision machine tools.