• 한국강구조학회 논문집
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• 제20권1호
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• pp.43-53
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• 2008

현재 국내에서 현장 체결공법으로 채용하고 있는 토크관리법은 토크계수를 근거로 해서 간접적으로 도입축력을 제어하는 방법이기 때문에 현장에서의 토크계수 관리가 상당히 중요하다. 따라서 본 연구에서는 현장 시공시 볼트보관방법 및 현장관리에서 일반적으로 발생할 수 있는 주요 환경 요인 중 수분 침투, 녹 발생, 외기노출, 와셔의 오용 등 다양한 실험변수로 계획하여 토크계수의 변화에 따른 도입축력의 차이를 확인하기 위하여 실험을 수행했다. 실험에 사용된 볼트는 육각 고력볼트, TS 고력볼트, 아연피막처리 육각 고력볼트, ASTM A490 고력볼트로서 4종류로 구분하여 수행되었고, 각 볼트별로 시공환경에 따른 체결특성을 비교 분석하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권7호
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• pp.1061-1067
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• 2008

Direct Torque Control[DTC] and Vector Control are the two schemes developed for high performance induction motor drives. DTC based induction motors are being increasingly used in various industrial applications. DTC offers fast torque response and better speed control with lesser hardware and processing costs as compared to vector controlled drives. However, conventional DTC suffers from high torque ripple, current harmonics and low performance during torque transients. In this paper a new Direct Torque Control[DTC] method of induction motor is presented. In comparison with the conventional DTC method, the PWM technique is applied to proposed control method. In this method, decoupling mechanism is not required and the torque, the flux magnitude are under control using PI controllers and generating the voltage command for inverter control. Therefore torque and speed ripple could be reduced in comparison with the conventional switching table DTC.

• 전력전자학회논문지
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• 제3권1호
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• pp.23-35
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• 1998

영구자석 동기전동기의 제어에 있어서 토오크 맥동은 전동기 제어성능 결정에 큰 요인으로 작용한다. 본 논문에서는 이러한 토오크 맥동을 효과적으로 저감하기 위한 새로운 토오크 추정 및 제어기법에 대해서 다룬다. 제안된 기법에서는 모델 기준 적응시스템(Model reference adaptive system ; MRAS) 기법을 이용하여 순시 토오크를 추정하고 적본형 가변구 조제어(Integral variable structure control ; IVSC)를 이용하여 추정된 토오크를 제어한다. DSP를이용하여 고 토오크 영구자석 동기전동기 제어시스템을 구성하고 실험을 수행하였으며 그 결과 제안된 제어기법이 우수한 토오크 맥동 저감효과를 가짐을 입증하였다.

• 복합신소재구조학회 논문집
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• 제5권3호
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• pp.8-16
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• 2014

Torque control method and turn of nut method are specified as clamping method of high strength bolts in the steel construction specifications. Quality control of torque coefficient is essential activity because torque control method, which is presently adopted as clamping method in domestic construction sites, is affected by variation of torque coefficient. The clamping of torque shear bolt is based on KS B 2819. It was misunderstood that the tension force of the TS bolt was induced generally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the intended tension, as it considerably varies due to torque coefficient dependent on the environmental factors and temperature variables despite the break of the pin tail.This study was focused to evaluate the effect of environmental factors and errors of installing bolts during tightening high strength bolts. The environmental parameters were composed of 'wet' condition, 'rust' condition, 'only exposure to air' condition. And the manufacture of trial product was planned to identify the induced force into the bolts. The algorithm for a trial product was composed of the relation between electricity energy taken from torque shear wrench and tension force from hydraulic tension meter.

• 전기학회논문지P
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• 제51권2호
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• pp.68-76
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• 2002

This paper presents an implementation of high-dynamic performance control system of Reluctance Synchronous Motor (RSM) drives for an industrial servo system with direct torque control (DTC). The problems of DTC for high-dynamic performance and maximum efficiency RSM drives are the nonlinear variable flux and inductance due to a saturated stator linkage flux and nonlinear inductance curve with various load currents. The accurate estimation of the stator flux and torque are obtained using stator flux observer of which a saturated inductance Ld and Lq can be compensated by using the adapted neural network from measuring the modulus and angle of the stator current. To obtain fast torque response and maximum torque/current with varying load current, the reference command flux is ensured by imposing Ids=Iqs. This control strategy is proposed to fast response and optimal efficiency for RSM drive. In order to prove rightness of the suggested control algorithm, we have some actual experimental system using 6000 pulse/rev encoder at ${\pm}10$ and ${\pm}1500rpm$. The developed digitally high-performance control system are shown some good response characteristics of control results and high performance features using 1.0kW RSM of which has 2.57 Ld/Lq salient ratio.

• 전기전자학회논문지
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• 제22권3호
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• pp.759-766
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• 2018

This paper presents a high-speed axial-flux machine which utilizes the idea of sinusoidal shaped pole combined with a consequent iron-pole. The target of the proposed machine is the cost reduction of the relatively expensive Samarium-Cobalt (SmCo) permanent magnet (PM) material and the torque per PM volume improvement by using sinusoidal consequent-pole rotor. The effectiveness of the proposed machine is validated by comparing it with conventional consequent-pole and with conventional PM machines using 3-D finite element method (FEM) simulations. The comparison and analysis is done in terms of back electro-motive force (back-EMF) harmonic contents, torque per PM volume and torque ripple characteristics. The simulation results show that the proposed machine is suitable and cost-effective for high-speed and high torque per PM volume applications. Furthermore, due to the consequent pole, the magnetic flux saturation and the overload current torque-capability are also presented and discussed in the paper.

• Journal of Korean Dental Science
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• 제2권1호
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• pp.19-27
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• 2009

Tightening of the screws in implant restorations should be accurate and precise. If applied torque is too low, screw loosening would be occurred. With too high torque, the screw fracture might take place. Various torque generating devices are developed and employed to apply a proper torque. The purpose of this investigation was to determine and compare the accuracy of the torque controllers. In this study, 4 types of torque controllers were used; electronic torque controller, torque limiting device, torque indicating device and contra angle torque driver. Digital torque gauge was employed to measure the de-torque value. Thirty cycles of tightening and loosening were done with each torque controller. All implant torque controllers have shown slight errors and deviations. The torque liming device exhibited the most accurate data. No significant difference was found among the mean de-torque values of the electronic torque controller, torque indicating device and contra angle torque driver. In the limitation of this study, it would be recommended that the implant torque controllers should be checked whether uniformed and precise torque can be generated and a measuring error should be corrected.

• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1105-1110
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• 2011

본 논문은 신경회로망 기법을 이용하여 직접벡터제어 방식의 문제점을 개선하고자 하였다. 직접벡터제어 방식은 히스테리시스 밴드 폭의 변화로 인해 유도전동기 속도제어 시 맥동이 큰 단점을 가지고 있다. 이러한 문제점을 학습을 통해 오차를 감소시키는 신경회로망 기법을 사용하여 기존의 직접벡터제어 방식에서 발생하던 속도 맥동을 개선하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.471-474
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• 2009

Gearbox is used to converter the power with high torque and low speed into the power with low torque and high speed. Gearbox housing should be sustained to prevent rotation of gearbox itself due to the difference between input and out torque. Uneven wind causes the reaction system to have unwanted reactive loads together with predictable pure torque. These unwanted reaction loads often cause the failure of gearbox due to bad gear mesh. In this paper, pure torque reaction system is proposed to prevent the failure of gearbox. Effectiveness and functionality of the proposed reaction system are demonstrated through the numerical analysis.

• 복합신소재구조학회 논문집
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• 제6권3호
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• pp.32-40
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• 2015

The torque shear high strength bolt is clamped normally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the required tension, as it considerably fluctuates due to torque coefficient dependent on lubricant affected temperature. In this study, the clamping tests of torque shear bolts were conducted independently at indoor conditions and at construction site conditions. During last six years, temperature of candidated site conditions was recorded from $-11^{\circ}C$ to $34^{\circ}C$. The indoor temperature condition was ranged from $-10^{\circ}C$ to $50^{\circ}C$ at each $10^{\circ}C$ interval. As for site conditions, the clamping force was reached in the range from 159 to 210 kN and the torque value was from 405 to $556 N{\cdot}m$. The range of torque coefficient at indoor conditions was analyzed from 0.126 to 0.158 while tensions were indicated from 179 to 192 kN. The torque coefficient at site conditions was ranged from 0.118 to 0.152. Based on this test, the variable trends of torque coefficient, tension subjected temperature can be taken by statistic regressive analysis. The variable of torque coefficient under the indoor conditions is $0.13%/^{\circ}C$ while it reaches $2.73%/^{\circ}C$ at actual site conditions. When the indoor trends and site conditions is combined, the modified variable of torque coefficient can be expected as $0.2%/^{\circ}C$. and the modified variable of tension can be determined as $0.18%/^{\circ}C$.