• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.9
• /
• pp.2297-2311
• /
• 1994

This paper presents the study on the development of a DNC, system IPIS(Interactive Plant Information System)/DNC, which can manage NC machines and robots as a distributed control method in the machine. processing factory. The IPIS/DNC system is composed of a host computer, satellites and NC machines. A set of software modules are developed on the host computer and the satellites separately. By modularizing each functions of the IPIS/DNC system and using multi-taking method, the functions such as NC program management, NC program distribution, and shop monitoring can be performed on the host computer, and the functions such as NC program transfer to the NC machines, and NC program editing can be performed on the satellites. A Relational database which is linked with job scheduling system is used for IPIS/DNC system.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.496-501
• /
• 2003

Computational study is performed to understand the fluidic thrust vectoring control of an axisymmetric nozzle, in which secondary gas injection is made in the divergent section of the nozzle. The nozzle has a design Mach number of 2.0, and the operation pressure ratio is varied to obtain the different flow features in the nozzle flow. The injection flow rate is varied by means of the injection port pressure. Test conditions are in the range of the nozzle pressure ratio from 3.0 to 8.26 and the injection pressure ratio from 0 to 1.0. The present computational results show that, for a given nozzle pressure ratio, an increase of the injection pressure ratio produces increased thrust vector angle, but decreases the thrust efficiency.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1637-1642
• /
• 2004

Experimental and computational studies were performed to investigate the effectiveness of a thrust vectoring method using a counterflow concept. A shadowgraph method was used to visualize the supersonic jet expanded from a two-dimensional convergent-divergent nozzle and deflected by a now suction. The primary nozzle pressure and suction nozzle pressure ratios are varied between 3.0 and 5.0, and between 0.2 and 1.0 respectively. The present experimental and computational results showed that, for a given primary nozzle pressure ratio, a decrease in the suction nozzle pressure ratio produced an increased thrust vector angle, and during the change processes of the suction pressure, a hysteresis effect of the thrust vectoring was found through the wall pressure distributions.

• Journal of Korea Water Resources Association
• /
• v.30 no.6
• /
• pp.769-776
• /
• 1997

The behavior of surge induced in the discharge system of the thermal power plants by the sudden stop of cooling water pump is analyzed using the numerical model developed by Yoon and Lee (1997). Various effects, which are ignored earlier, such as discharge from internal system, air chamber and air inlet of seal well, monholes, open channel and sea are included. These effects of the surge behavior are systematically analyzed. Especially, the surge control effect and air pressure change in the air chamber associated with the area of air inlet are presented for easy application in practice.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.1
• /
• pp.38-45
• /
• 1993

The feature based modeling approach is useful for post-CAD related works such as process planning and NC part programming. This paper describes the development of 'FeaTURN' system which is feature based NC part programming system for turning operation. The programming task in 'FeaTURN' system becomes easy and effective with the assistance of feature icons. The manufacturing attributes can be handled toghther with the features during input procedure. The cutter location data (CLD) is determined by the processor module. The post process module converts the CL data to machine control data (MCD). Also, the system graphically displays the tool path.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.11
• /
• pp.1423-1428
• /
• 2011

This paper proposes a learning input shaper with nonlinear actuator dynamics to reduce the residual vibration of flexible systems. The controller is composed of an estimator of the time constant of the nonlinear actuator dynamics, a recursive least squares method, and an iterative updating algorithm. The updating mechanism is modified by introducing a vibration measurement function to cope with the dynamics of nonlinear actuators. The controller is numerically evaluated with respect to parameter convergence and control performance by using a benchmark pendulum system. The feasibility and applicability of the controller are demonstrated by comparing its control performance to that of an existing controller algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.12
• /
• pp.1885-1891
• /
• 2010

Torque control of wind turbines is important when the wind speed is below the rated speed. The main objective of torque control is to extract the maximum power from the potential aerodynamic power of the wind. Torque control methods for wind turbines are classified as torque-mode control and speed-mode control. In torque-mode control, which is well known and traditionally used in many wind turbines, the torque demand of the generator is proportional to the square of the generator speed. In speed-mode control, a PI controller is used to generate the appropriate torque demand of the generator. In this study, the two torque control methods mentioned above are applied to a 2.75-MW wind turbine; simulation results for real turbulence wind speeds are presented, and the response properties are compared.

• Journal of Energy Engineering
• /
• v.27 no.4
• /
• pp.92-97
• /
• 2018

This study deals with the numerical analysis for hood development to improve the cooling effect of the engine related components in engine room. Reducing the component temperature in engine room caused by a sudden temperature deviation can minimize the durability degradation of components. Therefore, in this study, numerical analysis for the development of the hood in engine room was carried out in four parts such as generator, battery, ECU and power steel oil which are relatively easy to control temperature among the main components in engine room. In order to verify the numerical analysis, experiments were conducted under the same conditions as those assumed in the numerical analysis.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.9
• /
• pp.863-871
• /
• 2013

Flow characteristics of velocity-control trim in a valve is investigated numerically with high pressure drop. A basic trim widely used for a valve in domestic powerplants is selected and designed for a baseline of velocity-control trim. The numerical analysis is focused on flow rate and cavitation with the basic trim. For a condition of high-pressure drop, pressure drop between inlet and outlet and fluid temperature are selected to be 18.1 MPa and $160^{\circ}C$, respectively, which are typical ones considering operating conditions adopted in powerplants. With this baseline model and condition, design changes are made for improvement of flow rate and cavitation phenomenon. For re-design, trim is divided into three zones in radial direction and design parameters of flow area, stage, and flow direction are considered in each zone. With these combined parameters applied to each zone, 4 models with design changes are proposed and their flow rates and cavitation areas are investigated. From comparison with those in the baseline model of a basic trim, proposed models show better performance in both flow rate and cavitation.

• Journal of the KSME
• /
• v.23 no.5
• /
• pp.326-334
• /
• 1983

1980년대에서는 생산성이 세계 제조업자들에게 특히 중요하게 된다. 이 기간 중에, 보호관세가 낮아져서 외국사람의 접근이 증가하게 되고, 국내 및 국외시장에서 경쟁 역시 증가될 것이다. 동 시에 전세계적인 산업자동화의 물결이, 급속히 증가하고 있는 컴퓨터와 산업용 로봇들을 근거로 제조업에 거세게 일 것이며, 이 기술변환의 지표로서, CAD/CAM에 관한 약 1,000개의 논문 및 서적과 기사가 매년 출판 발표되고 있다. 이러한 변화의 물결 중에서, 가장 급속히 진보하고 있는 2개의 첨단기술은, 컴퓨터응용설계를 위한 그래픽시스템의 사용이며, 생산기계류와 수치로 제어 되는 기계공구 사용과 더불어 부품과 공구취급을 위한 산업용 로봇의 사용이다. CAD/CAM이, 기업이나 산업국가에게 위협을 줄런지 또는 행운을 가져다 줄런지 결정하는 CAD/CAM 그 자 체가 아니라, CAD/CAM에 대한 기업이나 산업국가의 반응 및 그 활용에 있겠다.