• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.11-12
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• 2006

Actuator arm of HDD were machined with the slitting saw of tungsten carbide to clarify the cutting characteristics in terms of the roughness of machined surface, the burr size and the tool wear. An improved performance in all view of the surface machined, the tool life and the cutting efficiency was obtained at the cutting speed of 4,000rpm with the feed of 300m/min. The tool life increases with increasing the t/T value, whereas surface roughness decreases. The tool with alternate type of B and C edges has an effect to decrease the burr size.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.424-425
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• 2018

In the introduction, this paper introduces LS Industrial Systems' medium-voltage drive installed at Hyundai Green Power, an 800MW gas power plant. In the body, it explains the synchronous transfer technology and new speed search technology applied to Forced Draft(FD) Fan and Boiler Feed-water(BF) Pump, which are power generation facilities. Lastly, it shows the annual energy saving amount and operation status which are applied to each facility and proves that it is a successful application case.

• 한국정밀공학회지
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• 제19권4호
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• pp.93-100
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• 2002

The current from the feed motor of a machine tool contains substantial information about the machining state. There have been many researches that investigated the current as a measure for the cutting farces. However it has been reported that this indirect measurement of the cutting farces from the feed motor current is only feasible in low frequency. In this research, it was presented that the bandwidth of the current monitoring can be expanded to 130 Hz. And the unusual behavior of the current was examined in this bandwidth. The cross-feed directional cutting force influences the machined surface of the workpiece, which makes it necessary to estimate this force to control the roughness of the machined sulfate. The current exists in the stationary feed motor, and it can give the useful information on the quality of the machined surface. But the unpredictable behavior of the current prevents applying the current to prediction of the cutting state. Empirical approach was conducted to resolve the problem. As a result, the current was shown to be related to the accumulation of the accumulation of the infinitesimal rotation of the motor. rotation of the motor. Subsequently the relationship between the current and the cutting force was identified.

• 전자공학회논문지SC
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• 제44권5호
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• pp.62-70
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• 2007

본 논문에서는 일정 토크영역에서 승압형 PFC 컨버터와 직접토크제어(DTC) 방법을 사용하여 BLDC 모터의 구동 시스템을 DSP(TMS320F2812)로 구현하였다. 기존의 6단계 PWM 전류제어와 달리 미리 정한 샘플시간 마다 간단한 look-up 표로부터 2상 도통 모드에 대한 인버터의 전압 상태 벡터를 설정함으로써 원하는 전류파형을 만들었으며 이로부터 기존의 전류제어기보다 훨씬 빠른 토크 응답특성을 얻을 수 있었다. 또한 BLDC 모터의 비 이상적인 사다리형 역기전력에 의해 발생되는 저주파 토크변동을 저감하기 위하여 위치 loop-up 표를 사용하였다. 아울러 역률을 보정하기 위해 승압형 PFC 컨버터를 구성하였고 이 때 전파 정류된 입력전압과 출력전압, 인덕터의 전류에 의해 평균전류모드 제어 방식으로 80 kHz마다 PWM 듀티(duty)가 조절 되도록 하였다. 이와 같이 복잡한 제어 알고리즘은 초고속 DSP의 출현으로 PFC와 DTC 알고리즘이 동시에 제어가 가능하며, 본 논문에서는 DTC 알고리즘을 구현할 때 DSP의 일반 범용의 출력포트를 사용하여 구현하였고 단지 PFC에서만 1개의 PWM을 사용하여 디지털 제어기를 구현하였다. 실험을 통해 DTC 알고리즘과 PFC 컨버터를 이용한 BLDC 모터 구동 시스템의 타당성과 효용성을 보였고, 실험결과로부터 PFC 컨버터를 사용하지 않았을 때는 역률이 약 0.77이었으나 PFC 컨버터를 사용하였을 때는 부하변동에 관계없이 약 0.9997로 크게 향상됨을 확인하였다.

• ETRI Journal
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• 제27권3호
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• pp.250-256
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• 2005

A novel planar polarization-agile microstrip subarray is proposed and its performance assessed by a thorough numerical investigation. The subarray consists of five square patches with a central element, directly coupled to a pair of microstrip feed lines by a cross-shaped aperture, which spreads the power outwards to the other patches through a network of suitable connections. By properly exciting the antenna at its input ports, any kind of polarization of the radiated field can be accomplished with fairly low cross-polarization levels. Moreover, since only two feed lines are required to drive the whole subarray, polarization agility is simply and attractively achieved by a single phase-shift circuit. The design concept is described and the results of the analyses and simulations performed by two completely independent full-wave approaches are presented and discussed.

• 한국정밀공학회지
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• 제32권4호
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• pp.329-337
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• 2015

In this paper, a simulation based estimation method of energy consumption of the spindle and feed drives for the NC machine tool during the cutting process is proposed. To predict energy consumption of the feed drive system, position, velocity, acceleration and jerk of the table are analyzed based on NC data and then the power and energy are calculated considering friction force and mass of the stages. Energy consumption of the spindle is estimated based on models from acceleration motion of rotating parts, friction torque and power loss of motors. Moreover, simulation models of cutting power and energy for the material removal along the NC tool paths are proposed.

• Journal of Advanced Marine Engineering and Technology
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• 제21권2호
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• pp.186-194
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• 1997

In this thesis, a new speed control algorithm based on the load torque observer theory is pro¬posed for the high performance speed control of a voltage source inverter to drive a 3 - phase induction motor. The proposed system becomes robust against disturbances using a feed -- for¬ward control of the load torque estimated at load torque observer. Computer simulation and experimental works using the proposed control confirm that transient response for the varia¬tion ofload torque becomes improved, compared with the conventional PI control method.

• 한국기계가공학회지
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• 제19권8호
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• pp.22-27
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• 2020

Ring rolling is a type of forging for manufacturing large-diameter rings. Products manufactured by ring rolling are useful in the aerospace industry because of their excellent mechanical properties and high dimensional accuracy. The major components of the ring rolling process are a mandrel and main roll that shape the inside and outside of the ring, an axial roll that shapes the top and bottom of the ring, and a side rolls to position the ring. In this study, a simulation of ring rolling using finite element method (FEM) was performed. DEFORM, a commercial machining analysis program, was used. Based on the simulations, the mandrel feed force required for machining and the drive torque of the main roll were predicted. It was also possible to identify the metal flow caused by machining.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 추계학술대회 논문
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• pp.34-39
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• 1996

In many industrial applicatiosns such as machine tools and automation equipments the control performance of the feed-drive systems as positioning devices of the tools and workpieces have great influences on the quality of related machines. For many electrically driven mechanical feed systems resilient couplings between motors and mechanical elements which mostly consist of elasttic shafts and gears often are unavoidable. Commonly these systems can be regarded as an elastic multi-mass systems can be regarded as an elastic multi-mass system which is dealt with this contribution. S high performance speed or position control can only be achieved with the considering of the mechanical elastic characteristics of the system. n this paper some practic characteristics of the system In this paper some practical information is given about experience in modeling design simulation and experiments for linear elastic multi-mass system,

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권6호
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• pp.287-290
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• 2006

A class-E CMOS RF(Radio frequency) power amplifier with a 1.8 Volt power supply is designed using $0.25{\mu}m$ standard CMOS technology. To drive the class-E power amplifier, a Class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. After one year of operating the power amplifier with an RF choke, the PAE(Power Added Efficiency) decreases from 60% to 47% and the output power decreases 29%. However, when a finite DC-feed inductor is used with the load, the PAE decreases from 60% to 53% and the output power decreases only 19%. The simulated results demonstrate that the class-E power amplifier with a finite DC-feed inductor exhibits superior reliability characteristics.