• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
• /
• pp.719-720
• /
• 2006

In the mechanical system, optimization of motion control is very essential in the aspect of automation technique progress. In the servo system, the function of controller is very important but most of the controllers have played only the role of pulse generator because the controller with main function is very expensive. In this thesis, the system was composed of PC, commonly used driver AC servo motor and a produced control board. The PC transmit a gain, a locus data to a driver and controller. At the same time, it converts imformation from the controller and convert them into data and offer an output with graph. The role of a controller is to trasmit a locus data to a driver and counting the pulse on the phase of an encoder to the PC. We have performed the experiment in order to confirm with variable PID parameter capable of the optimization of gain tuning with the counting of feedback control sensor signal with regard to the external interface into the system, such as torque. Based on the experiment result, we have confirmed as follows: First, it was confirmed that we could easily input control factors P.I Gain, constant $K_P,\;K_I$ into PC. Second, not only pulse generator function was possible, but with this pulse it was also possible to count using software with PIC chip. And third, using the multi-purpose PIC micro chip, simple operation and the formation of small size AC Servo Controller was possible.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 하계학술대회 논문집 D
• /
• pp.1124-1126
• /
• 1997

The Unified Power Flow Controller(UPFC) with a series inverter and a shunt inverter ia able to control all three line Parameters(voltage, impedance and phase angle) and so UPFC technology has the potential to enhance the implementation and broad application of the FACTS concept with improved Performance. In this Paper, the UPFC is applied in order to improve the power flow oscillation damping. The modal performance measure is minimized in order to determine the optimal parameters of UPFC controller for damping Power flow oscillations. The dynamics of the injected voltage of UPFC is represented as a first order delay element. The UPFC controller used here is of the PIO type and the input signal to the controller is the active power flow through the UPFC. The effect of UPFC application to the Power system are analyzed from the stand point of power system oscillation damping.

• 디지털콘텐츠학회 논문지
• /
• 제10권1호
• /
• pp.107-113
• /
• 2009

최근에 와서 ADL(Advanced Distributed Learning) SCORM 2004를 준수하는 e-러닝 콘텐츠를 개발하여 제시함으로써 e-러닝 콘텐츠 간의 상호 호완성과 재사용성을 증대시키고자 하는 여러 노력이 있어 왔다. 진정한 의미의 효과적인 SCORM 2004 콘텐츠를 개발하기 위해서는 콘텐츠 개발자가 교수 설계 단계에서부터 콘텐츠 시퀸싱 전략을 수립해야 한다. 그러나 설계 단계에서 수립된 콘텐츠 시퀀싱 전략을 SCORM 시퀀싱으로 구현하는 단계에서는 SCORM 2004 S&N(Sequencing&Navigation) 이해의 난해함으로 인하여 진입장벽(barrier)이 존재하는 것이 현실이다. 이에 본 연구에서는 SCORM 2004의 활용 및 활성화를 더디게 하는 가장 큰 어려움 중의 하나였던 SCORM 시퀀싱을 효과적으로 적용한 응용 사례와 함께 SCORM 2004 콘텐츠 설계 및 구현 단계를 구체적으로 제시함으로써 사실상 e-러닝 기술 표준으로 인정받고 있는 SCORM 2004의 적용 효과성 및 유용성에 대한 질적 재고를 모색하고자 한다.

• Structural Engineering and Mechanics
• /
• 제37권2호
• /
• pp.197-213
• /
• 2011

Concrete is a heterogeneous material exhibiting quasi-brittle behaviour. While homogenization of concrete is commonly accepted in general engineering applications, a detailed description of the material heterogeneity using a mesoscale model becomes desirable and even necessary for problems where drastic spatial and time variation of the stress and strain is involved, for example in the analysis of local damages under impact, shock or blast load. A mesoscale model can also assist in an investigation into the underlying mechanisms affecting the bulk material behaviour under various stress conditions. Extending from existing mesoscale model studies, where use is often made of specialized codes with limited capability in the material description and numerical solutions, this paper presents a mesoscale computational model developed under a general-purpose finite element environment. The aim is to facilitate the utilization of sophisticated material descriptions (e.g., pressure and rate dependency) and advanced numerical solvers to suit a broad range of applications, including high impulsive dynamic analysis. The whole procedure encompasses a module for the generation of concrete mesoscale structure; a process for the generation of the FE mesh, considering two alternative schemes for the interface transition zone (ITZ); and the nonlinear analysis of the mesoscale FE model with an explicit time integration approach. The development of the model and various associated computational considerations are discussed in this paper (Part 1). Further numerical studies using the mesoscale model for both quasi-static and dynamic loadings will be presented in the companion paper (Part 2).

• 디지털융복합연구
• /
• 제3권2호
• /
• pp.143-157
• /
• 2005

Many papers point out that the e-Learning is one of the most important industries, and the effect on other industries can be more powerful than any other business. Therefore, we think about social, cultural, industrial and technological effect of the e-Learning in order to enlarge industry scale as well as educational performances. In many cases of developed countries, various kinds of study have been performed for the e-Learning quality assurance because quality of the e-learning should operate on effective and efficient learning and continuous market development of education industries. The e-Learning quality assurance has import function not only for learning contents reusability like a SCORM and metadata but also for learning system, solution and service operation, so activities for the quality assurance should consider of cultural and tactical approach when it is applied in the e-learning business. In this paper, we present the concept, domain and purpose of the e-Learning quality assurance. Furthermore, this paper proposes the process and methodology in order to make the quality assurance standard model which is consist of 6 phase such as Environment Research, Needs Analysis, Framework, Metrics, Development and Implementation, Evaluation and Feedback through the analysis and comparison of pre-studied worldwide quality control, management and assurance documents.

• 대한조선학회논문집
• /
• 제45권4호
• /
• pp.345-352
• /
• 2008

The motion of a projectile initiated by the release of highly pressurized air is simulated presuming the flow field as a two dimensional one. The effects of water compressibility on projectile movements are investigated, comparing results based on the Fluent VOF model where water is treated as an incompressible medium with those from the presently developed VOF scheme. The present model considers compressibility of both air and water. The Fluent results show that the body moves farther and at higher speeds than the present ones. As time proceeds, the relative difference of speed and displacement between the two results drops substantially, after acoustic waves in water traverse and return the full length of the tube several times. To estimate instantaneous accelerations, however, requires implementation of the water compressibility effect as discrepancies between them do not decrease even after several pressure wave cycles.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2010년도 제42차 하계학술발표논문집 18권2호
• /
• pp.203-207
• /
• 2010

본 논문에서는 레이더용 다중채널 수신기의 설계 및 제작 그리고 측정 결과를 소개한다. 설계된 다중채널 수신기는 주파수 X-대역에서 8개의 동일 특성을 갖는 신호를 수신 할 수 있으며, 80[dB]이상의 높은 동특성을 갖는다. 또한 직접수신처리를 위해 2개의 디지털복조처리기가 내장된 일체형이므로 수신경로의 손실을 최소화하였고, 자체점검 기능을 부여하여 시스템의 안정성을 확보하였다. 다중채널 수신기의 성능으로는 수신이득 $14{\pm}2[dB]$, 수신 잡음지수 19[dB], 수신 경로상의 크기와 위상 차이는 각각 ${\pm}2[dB]$, $10^{\circ}$이하를 갖는다.

• 한국정보처리학회논문지
• /
• 제4권5호
• /
• pp.1380-1390
• /
• 1997

본 논문에서는 정규 순환방정식으로 표현된 n차원의 문제로부터 1차원이나 2 차원의 최적 평면 시스톨릭 어레이를 체계적으로 유도하는 방법과 이를 구현한 시스톨릭 어레이 설계시스텀을 제시한다. 구현된 시스템은 주어진 정규 순환방정식을 구문분석하여 문제공간, 자료종속 벡터와 초기값의 위치를 구한다. 이들 정보로부터 공간.시간 변환을 하여 자동으로 시스톨릭 어레이를 유도한다. 이스시템은 유도된 시스톨릭 어레이를 유도한다. 이 시스템은 유도된 시스톨릭 어레이의 병렬수행이 올바르게 이루어지는 지를 시각적으로 검증할 수 있게 해 준다.

• Journal of Power Electronics
• /
• 제16권6호
• /
• pp.2350-2358
• /
• 2016

The one cycle control (OCC) scheme for active power filters (APFs) has shown excellent harmonic suppression and implementation simplicity. However, its real world application is limited because the non-ideal supply voltage for APFs can influence its performance so that the source currents are still distorted after compensation. This paper proposes a modified one cycle control (MOCC) scheme to improve the performance of three-phase shunt APFs under non-ideal supply voltage conditions. In this paper a detailed mathematical derivation has been presented and the key control law of the MOCC has been developed for adaption to the non-ideal supply voltages, following the control philosophy of simplicity. A relatively simple sequence filter is introduced to extract the harmonic components of supply voltages. The modified scheme can be easily implemented. The proposed control strategy has excellent performance and a 5kVA APF hardware platform has been implemented to validate the feasibility and performance of the proposed strategy.

• Journal of Power Electronics
• /
• 제16권6호
• /
• pp.2109-2118
• /
• 2016

Based on the space vector pulse width modulation (SVPWM) theory, this paper realizes an easier SVPWM strategy, which is equivalently implemented by CBSPWM with zero-sequence voltage injection. The traditional SVPWM strategy has no effect on controlling the neutral-point voltage balance. In order to solve the neutral-point voltage unbalance problem for neutral-point-clamped (NPC) three-level inverters, this paper proposes a neutral-point voltage balance controller. The proposed controller realizes controlling the neutral-point voltage balance by dynamically calculating the offset superimposed to the three-phase modulation waves of an equivalent SVPWM strategy. Compared with the traditional SVPWM strategy, the proposed neutral-point voltage balance controller has a strong ability to balance the neutral-point voltage, has good steady-state performance, improves the output waveforms quality and is easy for digital implementation. An experiment has been carried out on a NPC three-level inverter prototype based on a digital signal processor-complex programmable logic device (DSP-CPLD). The obtained experimental results verify the effectiveness of the proposed neutral-point voltage balance controller.