• Journal of KSNVE
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• v.7 no.1
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• pp.20-29
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• 1997

내부공진은 2자유도계 이상의 다양한 비선형 시스템에 존재할 수 있으며 모드 사이의 진동에너지의 교환의 원인이 된다. 위에서 설명한 흡진기의 경우처럼 그 시스템의 동작에 필수적인 요소가 되기도 하며 직사각형 평판의 경우처럼 선형이론 으로는 예측불가능한 진폭변조된 진동을 유발하기도 한다. 이론적인 해석의 결과 다양한 분기와 여러가지 형태의 해를 가지며, 특히 주기적 정상해와 혼돈적인 해를 갖는 것이 밝혀졌다. 이러한 주기적 정상해는 구조물에 따라 여러 가지 형태로 나타 나며 평판의 경우는 진폭변조된 움직이는 파형으로, 본문에서는 언급하지 않았지만 현의 경우는 타원의 퀘적의 크기와 주축의 방향의 변화로 나타난다. 이러한 다양한 해들은 구조물의 종류와 형상에 따라 다른 형태로 나타나며 향후 연구의 대상이라 생각되어진다.

• KIPE Magazine
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• v.9 no.2
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• pp.38-41
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• 2004

서보 모터 및 드라이브는 일반산업기계, 반도체 장비, 공작기계, 산업용 로봇 등 산업 자동화 기술의 핵심요소이다. 국내에서는 1990년을 기점으로 대기업을 주축으로 서보 장치 개발이 시작되었으며, 일부 대학과 중소기업의 참여가 이루어져왔다 하지만 IMF이후 국내 서보기술 투자여건 변화와 선진제품의 꾸준한 시장잠식에 의해 외국산 서보제품이 국내시장의 대부분을 차지하고 있다. 〔그림 1〕. 이에 국내제품의 품질 및 기술력 향상을 통해 산업기반요소인 서보 시장에서 경쟁력을 갖춘 고 정밀 서보 시스템 개발이 요구되고 있다. 본고에서는 회전형 서보 모터 및 드라이브에 국한하여 국내 서보관련 제조업체 및 서보기술의 현황을 파악하여, 국내 서보 시스템의 발전 방향을 모색하는데 일조 하고자 국내 서보 제조업 체들의 홈페이지를 소개하고자 한다.(중략)

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.627-629
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• 2000

최근에 클러스터 시스템 사용이 보편화되어 가고 있지만 클러스터를 구성하고 있는 노드 사이의 통신이 여전히 전체 성능 향상의 병목요인으로 지적되어 있다. 현재 클러스터 시스템의 노드간 통신은 TCP 프로토콜을 이용하고 있는데, 동질적이고 전송에러를 무시할 수 있는 클러스터 통신망에는 적합하지 않다. TCP의 단점을 극복하기 위하여 클러스터를 위한 다양한 사용자 수준 인터페이스가 제안되고 구현되었다. 이 중 Intel, Compaq, Microsoft가 주축이 되어 정의한 VIA는 SAN 환경에 적합하도록 기존의 소프트웨어 오버헤드를 줄인 사용자 수준의 통신 프로토콜이다. 본 논문에서는 현재 리눅스 클러스터 상에서 사용 가능한 VIA 구현들에 대해 특징을 살펴보고, 동일한 환경에서 성능을 비교해 보았다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.40-42
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• 2001

ebXML[1]은 UN/CEFACT와 OASIS가 주축으로 제정한 전자상거래 국제 표준으로 모든 거래 당사자들에게 상호 운용성, 안전 및 일관성 있는 방법으로 XML 기반의 구조를 제공하여 광범위 한 e-business 정보 사용이 가능하도록 하는 것을 목적으로 한다. ebXML Registry/Repository는 ehXML을 기반으로 한 전자상거래 시스템의 핵심 부분을 구성하며 Browse & Drill Down Query Filter Query와 같은 메커니즘을 기본적으로 제공하고 SQL Query를 선택적으로 지원한다. 본 논문에서 RDBMS상에서 Registry 시스템의 필수 질의 서비스인 Filter Query를 구현하기 위해 SQL로의 변놘 방법을 제안하고 적용 예를 설명한다.

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.192-201
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• 2016

Condition Monitoring System (CMS) has been used to detect unexpected faults of wind turbine caused by the abrupt change of circumstances or the aging of its mechanical part. In fact, it is a very hard work to do regular inspection for its maintenance because wind turbine is located on the mountaintop or sea. The purpose of this study is to find out distribution patterns of vibration signals measured from the main mechanical parts of wind turbine according to its operation condition. To this end, acceleration signals of main bearing, gearbox, generator, wind speed, rotational speed, etc were measured through the long period more than 2 years and trend analyses on each signal were conducted as a function of the rotational speed. In addition, correlation analysis among the signals was done to grasp the relation between mechanical parts. As a result, the vibrations were dependent on the rotational speed of main shaft and whether power was generated or not, and their distributions at a specific rotational speed could be approximated to Weibull distribution. It was also investigated that the vibration at main bearing was correlated with vibration at gearbox each other, whereas vibration at generator should be dealt with individually because of generating mechanism. These results can be used for improving performance of CMS that early detects the mechanical abnormality of wind turbine.

• Journal of Practical Engineering Education
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• v.10 no.2
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• pp.81-87
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• 2018

During the major sections of the network, Software-defined network control technology for the network area corresponding to the transmission network is becoming a change in network-controlled environments utilizing network operation and provisioning across the network industry. Currently development is underway along with the deployment of PTN equipment and configuration for provisioning is being phased out. It is actively introducing establishment of SDN-based control system while constructing provisioning of PTN equipment from actual commercial network. Therefore, in this thesis, we are going to look at the contents and trends of SDN systems in packet-based transmission networks based on PTN and use them in research on OpenDaylight, an open source for configuring SDN. It then Network Operator will study the software defined control techniques for operational education.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.203-212
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• 2002

Active magnetic hearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting. This paper describes a design and test of an active magnetic bearing system with 16-pole radial magnets. The spindle is originally designed for a CNC lathe and driven by outer motor with 5.5 kW power and maximum speed 10,000 rpm. Considering static load condition and geometric restrictions, radial magnet is designed 16-pole type for smaller outer diameter of the spindle system. Dynamic system characteristics such as natural frequency, critical speed, stiffness, damping and system stabilities are simulated with a rigid rotor model including direct feedback controller. The designed spindle system is realized with digital PIDD controller to compensate phase lag of PWM amplifier and magnet coils. With levitation and step response experiment the control system characteristics are tested, and the spindle is rotated up to 10,000 rpm stab1y.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.213-219
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• 2002

A cone-shaped active magnetic healing spindle system for high speed internal grinding with built-in motor that has 7.5kW power and maximum rotational speed of 50,000 rpm is designed and built. Using cone-shaped AMB(Active Magnetic Bearing) system, the axial rotor dick and magnets of conventional 5-axis actuating design can be eliminated. so this concept of design provides a simple magnetic bearing system. In this paper, the cone-shaped electromagnets are designed by magnetic circuit theory, and a de-coupled direct feedback PID controller is applied to control the coupled magnetic bearings. The designed crone-shaped AMB spindle system is built and constructed with a digital control system, which has TMS320C6702 DSP, 16 bit AD/DA, switching power amplifier and gap sensors. As the AMB system provides high damping ratio eliminating overshoot and resonance speed, this spindle runs up to 40,000 rpm stably with about 5${\mu}{\textrm}{m}$ of runout.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.20-25
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• 2011

In this paper, we reviewed the spindle system's motor and bearing and its mode safety for optimal design of a high speed spindle system that exceeds DmN value of 1,500,000. We could verify that it has a separation margin during critical speed by performing critical speed analysis. Also, we have selected an optimal sensoring installation location and actually manufactured & installed the sensor by identifying the stress concentration position in the axial load through finite element analysis to install the built-in piezo electric type load sensor to the spindle housing that can measure and monitor the machining load during high speed rotation of the spindle. Reproducibility is also verified by calibrating the error through the sensor's sensitivity adjustment after comparing the output between the plate dynamoneters and the load sensor to confirm the reproducibility of the load sensor.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.5
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• pp.38-48
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• 2004

Recently the use of high-speed equipment in machine-tool industry has greatly increased, which requires the development of prognostics and prediction methods on the design stage. Conversion of the test/experiments stage from real to virtual reality will not only significantly reduce the design and manufacturing cost, but will also increase design quality. This paper shows how it is possible to develop the automated system for the design calculations of the air-bearing spindles. First, the general calculation method is introduced. It contains several steps, namely, geometry identification, pressure calculation, stiffiness calculation, dynamics characteristics calculation. For geometry identification reducing spindle shaft to rings was proposed, which helps to automate the calculation process. For pressure calculation the Peshti method was implemented. For stiffiness calculation the analysis was made, which shown the necessity of correct calculation step selection. Then the system of ordinary differential equations containing influence coefficients was evolved, which is used for trjectories calculation. The graphical representation of the calculation results shows the dynamic behavior of the spindle unit concerning various working conditions. Finally, this automated system is illustrated by an example of the air-bearing spindle calculation.