• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.50-55
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• 2008

CNC wire bending machines are used in industries to make a type variety of wire products such as long links. The machines have a long arm device to rotate in order to remove forming errors by flexibility of wire. Generally, the machines which constructed servo motors in the arm have the rotating range of the arm under 360 degree because the servo motors connect with fixed control devices on frame by many cables. The rotating angle under 360 degree limits working speed and forming geometry. Therefore this study developed a gear train to drive a parts in arm and to be independent on arm rotation movement. The developed gear train can transfer four movements to four components in arm and is consists parallel of four pairs of satellite gear trains. This study constructed the CNC wire bending machine with the developed gear train and verified that the gear train could drive internal components independently on arm rotation.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.3
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• pp.50-55
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• 1999

Brushless DC Motor(BLDCM) has high efficiency. But this type of motor needs a rotor sensor which complicates the motor configuration. Rotor position sensor degrades system reliability in the severe environmental condition. In this paper, we study a controller which permits the determination of the rotor position by the back EMF to eliminate the rotor position sensor Also, since the back EMF is zero at standstill, a starting technique which permits the starting of an asynchronous motor without a sensor is described. The controller is implemented using microcontroller for minimal external component.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1453-1459
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• 2011

A roller pinion gear (RPG) system composed of either a pin or a roller and its conjugated cam gear can improve the gear endurance from that of a conventional gear system by reducing the sliding contact while increasing the rolling motion. In this paper, we first proposed the exact cam gear profile and the self-intersection condition obtained when the profile shift coefficient is introduced. Then, we investigated the Hertzian contact stresses and the load stress factors while the varying the shape design parameters to predict the gear surface fatigue life, which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.269-274
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• 2016

This paper proposes the development of a low frequency electronic hammer drive system that is used to prevent scaling or clogging in the hopper process. The electro-mechanical hammering driving method involves the generation of vibration and impact energy. The operation principles of the electromagnetic hammer were considered by parallel/series spring coefficient analysis and the amount of kinetic energy generated was calculated from the product of the equivalent spring constant, which is coupled with the E core and the gap of between the E core and I core. In addition, the Pulsation Driving algorithm was applied to the proposed electromagnetic hammer to obtain the maximizing kinetic energy. This algorithm was then implemented by a logical AND operation process and micro-controller (atmega128) built in functions with a timer interrupt and PWM generation function. The driving circuit of the electromagnetic hammer was designed using the H-bridge type IGBT circuit. The experimental test was performed by usefulness of the developed electromagnetic hammer systems with the acceleration measurement method. The experimental result showed that the proposed system has good kinetic energy generation performance and can be applied to the hopper process.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.49-55
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• 2016

This paper analyzed a root cause of abnormality in the temperature and vibration at generator-side bearing of motor generator set (MG Set), which is a power supply system to control element drive mechanism (CEDM) of nuclear power plants (NPPs), and modified the design of roller-type and sealing method to improve the abnormalities. From the inspection of MG Set and analysis of temperature variation during service, it was found that the abnormal temperature transition was basically associated with original design of generator-side bearing, whose roller was axially restrained by inner race, and that the abnormal vibration level was caused by inserting small chips of cage and V-ring, which were generated due to the abnormal temperature transition at roller bearing. Type of bearing and sealing method were modified based on these analyses. The temperature and vibration level measured at roller bearing showed that the modifications clearly improved the operational stability of MG Set.

• Journal of the Korea Society of Computer and Information
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• v.18 no.6
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• pp.1-8
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• 2013

In this paper, we design and implement a firmware for low-cost small PCR devices. To minimize machine code size, the proposed firmware controls real-time tasks simultaneously only with support of the hardware interrupt, but without support of the operating system program. The proposed firmware has the host-local structure in which the firmware receives operation commands from PC and sends operation results to PC through usb communication. We implement a low-cost small PCR device with the proposed firmware loaded on microchip PIC18F4550 chip, and verify that the implemented PCR device significantly reduces cost and volume size of existing commercial PCR devices with a similar performance.

• Journal of the KSME
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• v.33 no.10
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• pp.892-901
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• 1993

환경오염과 차량 성능향상에 따라서 날로 강화되는 연비규제는 차량용 변속기로서 CVT 양상 보급에 대한 필요를 앞당기고 있다. CVT는 소형차를 중심으로 일부 자동차 에이커에 의해 이미 실용화되어 있으며 일본 및 구미 자동차 각 사는 CVT에 대한 자체기술을 보유하고 경쟁성 있 는 완성품 개발을 위하여 총력을 기울이고 있는 실정이다. CVT에 대한 연구개발의 추세는 동 력전달 구동요소의 특성에 따라 벨트식과 토로이달 (Torodial)식으로 구분할 수 있으며 대부분의 경우 현재 일부 실용화 개발된 벨트식 CVT가 기술완성도가 높은 반면 토로이달롤러의 각도를 연속적으로 변환시킴으로써 무단변속을 이루는 토로이달 방식은 2000년대 이후에 양산을 목표로 일본 및 영국 등에서 개발 진행주이나 새로운 재질과 제어기술개발 등의 숙제를 안고 있다. 벨 트식의 경우 금속벨트는 지난 십 수년이상 시행착오를 겪으며 CVT용으로 개발된 전문업체의 제품이 이미 특허화되어 있기 때문에 자동차 각사는 벨트와 같은 구동요소보다는 CVT 메카니즘 설계 및 제어시스템 개발에 기술력을 투입하고 있다. 따라서 국내 CVT 개발도 이와 같은 추세를 따를 것으로 기대되고 있으나 AT와 같은 완성품으로서의 상품가치를 갖기 위하여는 CVT에 대한 보다 많은 연구개발이 필요하다고 생각된다.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.134-138
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• 2004

본 연구에서는 카오스 랜덤 PWM(Chaotic Random PWM) 기법에 의한 3상 유도모터의 스위칭 소음 저감에 대하여 다루고 있다. 일반적으로 사용되고 있는 랜덤 발생기로서 선형일치발생기(Linear Congruential Generator : LCG)대신에 로지스트 사상(Logistic Map)의 분기도(Bifurcation Diagram)를 랜덤 발생기로 사용하였다. 카오스 랜덤수 발생기는 80C196 마이크로 콘트롤러가 전담하고 있으며, 80C196으로부터 발생된 카오스랜덤 수와 MAX038에 의하여 삼각파 랜덤 캐리어가 발생되고 있다. 1.5kw급 3상 유도모터 구동 시스템에 카오스 RPWM기법을 적용하여 모터전압 및 전류 그리고 스위칭 소음의 스펙트럼을 고찰하였다. 카오스 RPWM과 LCG에 의한 RPWM의 결과를 각각 비교하였으며 본 연구의 타당성을 입증하였다.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.35-40
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• 1997

The traction drive has advantages of having high efficiency and transmitting the power without blacklash. However, when high ratio of speed reduction is desired, excessively large size is required. In this study, a new type of traction drive is invented, designed and manufactured so that stable speed reduction mech- anisms are available by adopting a cross roller type drive. It has a simple structure, but produces high speed reduction ratio. Power loss is observed, and also, driving torque and torque transfer efficiency are calculated. Pre-loads are needed in order that the traction drive transfers power without slipping, and the spacer is enlarged due to the pre-loading. After all, the key point of pre-load mechanism is that the spacer's diameter becomes larger as pre-loads are applied.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.166-174
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• 2002

Power steering systems far automobile are becoming ever more popular because they reduce steering efforts of the drivers, especially during parking lot maneuver. In this paper, the controller of the motor driven hydraulic power steering(MDHPS) has been designed and developed. This system uses a power source of DC motor instead of engine power source for power steering drive oil pump. The developed MDHPS system is accomplished a highly sensitive power steering resulted from electronic control under variable driving condition. Furthermore, this system is more improvement than type of engine driving far fuel economy.