• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1228-1230
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• 1992

The permanent magnet synchronous motor(PMSM) is receiving Increased attention for servo drive applications in recent years because of its high torque to inertia ratio, superior power density and high efficiency. By vector-controll method, PMSM has the same operating characterics as seperately excited dc motor. The drive system of servo motor is requested to have an accurate response for the reference input and a quick recovery for the disturbance such as load torque. However, when the unknown disturbances and parameter variations are imposed on the permanent magnet synchronous motor(PMSM), the drive system is significantly effected by them. As a result, the drive system with both a fast compensation and a robustness to a parameter variations is requested. This paper investigates the possibility of applying the fuzzy logic controller(FLC) using Multi-Rule Base In a servo motor control system. In this paper, The five Rule Bases(1 to 5) are selected to recover the state error caused by the disturbance in steady state. In the initial operating mode. Rule Base 0 is used. To show the validity of the proposed fuzzy logic controll system, the computer simulation results are provided.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4A
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• pp.214-218
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• 2012

In this paper, we reported on a high performance waveguide VCO(voltage controlled oscillator) for FMCW applications. The waveguide VCO consists of a GaAs Gunn diode, a varactor diode, and two bias posts with low pass filter(LPF). The cavity is designed for fundamental mode at 47 GHz and operated at second harmonic of 94 GHz center frequency. The developed waveguide VCO has 1.095 GHz bandwidth, 590 MHz linearity with 1.69% and output power from 14.86 to 15.93 dBm. The phase noise is under -95 dBc/Hz at 1 MHz offset.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.3
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• pp.99-104
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• 2002

lateral insulated gate bipolar transistors(LIGBTs) are extensively used in high voltage power IC application due to their low forward voltage drops. One of the main disadvantages of the LIGBT is its scow switching speed when compared to the LDMOSFET. And the LIGBT with reverse channel structure is lower current capability than the conventional LIGBT at the forward conduction mode. In this paper, the LIGBT which included p+ ring and p-channel gate is presented at the reverie channel structure. The presented LIGBT structure is proposed to suppress the latch up, efficiently and to improve the turn off time. It is shown to improve the current capability too. It is verified 2-D simulator, MEDICI. It is shown that the latch up current of new LIGBT is 10 times than that of the conventional LIGBT Additionally, it is shown that the turn off characteristics of the proposed LIGBT is i times than that of the conventional LIGBT. It is net presented the tail current of turn off characteristics at the proposed structure. And the presented LIGBT is not n+ buffer layer because it includes p channel gate and p+ ring.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.88-90
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• 2012

A study on an integrated single stage AC/DC converter is presented in this paper. The input current can be controlled by the auxiliary winding($L_{aux}$), auxiliary primary winding($N_3$), and the boost inductor($L_B$) which are designed to operate in discontinuous conduction mode(DCM) to reduced the total harmonic distortion(THD) of input current. The auxiliary primary winding($N_3$) is critically selected in order to compress the input capacitor voltage($V_{in}$) as well as to reduce the current stress of the switch(Q). Low total harmonic distortion(THD), low input voltage($V_{in}$) in universal input voltage($V_{AC}$), low current stress at the switching device and high efficiency are the main consideration keys in this design to achieve high performance system with low cost of single stage AC/DC converter. A 30W single stage AC/DC prototype converter is under study.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1199-1205
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• 1993

It has been well known that the assumption of full state availability is one of the most important restrictions to the practical realization of VSCS. And several attempts to alleviate the assumption had been made. However, it is not easy to find a positive scheme among them. Recently, an output feedback variable structure control system(OFVSCS) was proposed and the effectiveness of the scheme was validated for the disturbance free systems. The purpose of this study is to propose a robust OFVSCS that have the robust properties against process parameter variations and external distrubances by extending the basic OFVSCS and to evaluate its control performances through power system stabilizer design example. The ROFVSCS is composed of dynamic switching function and output feedback switching control inputs that are constructed by the use of the unknown vector modeling technique. With the proposed scheme, existence of sliding mode is guaranteed and any nonzero bias can be suppressed in the face of disturbances and process parameter variations as far as well-known matching condition is satisfied. Due to the fact that the ROFVSCS is driven by small number of measured informations, the practical application of VSCS for the systems with unmeasurable states and for high order systems that conventional schemes cannot be applied, is possible with the proposed scheme. It is noticeable that the implementation cost of VSCS can be considerably reduced without sacrifice of control performances by adopting ROFVSCS since there is no need measure the states with high measurement cost.

• Laser Solutions
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• v.17 no.4
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• pp.14-19
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• 2014

Laser beam was applied on the boundary of the polyurethane and biodegradable polyacetate polymers. The distributed laser passed through the polyurethane layer and heated the polyacetate layer, then the soften acetate was squeezed thorough the 1mm square slots of polyurethane for the mechanical joining. The surface roughness ranging between $0.28{\mu}m$ and $3.06{\mu}m$ had almost no effect on joining strength, but the optical properties of HD (High Definition) and UHD (Ultra High Definition) mode affected laser beam transmittance. The optimum laser power was found to be between 8watt and 10watt with 500mm/min of scanning speed. The joining boundary was characterized by optical and SEM analysis. Based on the experiment and characterization results, the laser energy was effective for the polymer joining and efficiency of joining.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.09a
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• pp.121-145
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• 2001

Chip Size Packages (CSP) are now widely used in high speed DRAM. The major driving farce of CSP development is its superior electrical performance than that of conventional package. However, the power dissipation of high speed DRAM like DDR or RAMBUS DRAM chip reaches up to near 2W. This fact makes the thermal management methods in DRAM package be more carefully considered. In this study, the thermal performances of 3 type CSPs named $\mu-BGA$^{TM}$$ $UltraCSP^{TM}$ and OmegaCSP$^{TM}$ were measured under the JEDEC specifications and their thermal characteristics were of a simulation model utilizing CFD and FEM code. The results show that there is a good agreement between the simulation and measurement within Max. 10% of $\circledM_{ja}$. And they show the wafer level CSPs have a superior thermal performance than that of $\mu-BGA.$ Especially the analysis results show that the thermal performance of wafer level CSPs are excellent fur modulo level in real operational mode without any heat sink.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1011-1016
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• 2015

Gas piping systems in power plants and factories are always influenced by the mechanical vibrations of rotational machines such as pumps, blowers, and compressors. Unusual vibrations in a gas piping system influence possible leakages of liquids or gases, which can lead to large explosive accidents. Real-time measurements of unusual vibrations in piping systems in situ prohibit them from being possible leakages owing to the repeated fatigue of vibrations. In this paper, a non-contact 3-dimensional measurement system that can detect the vibrations of a solid body and monitor its vibrational modes is introduced. To detect the displacements of a body, a stereoscopic camera system is used, through which the major vibration types of solid bodies (such as X-axis-major, Y-axis-major, and Z-axis-major vibrations) can be monitored. In order to judge the vibration types, an artificial neural network is used. The measurement system consists of a host computer, stereoscopic camera system (two-camera system, high-speed high-resolution camera), and a measurement target. Through practical application on a flat plate, the measured data from the non-contact measurement system showed good agreement with those from the original vibration mode produced by an accelerator.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.774-779
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• 1998

For the speed control of motors, the position or speed sensors are necessary to obtain the position information of the rotor. Specially, SRM(Switched Reluctance Motor) needs an accurate rotor position data because both the rotor and the stator have a salient pole structure. High functional sensors like resolver or encoder are expensive and have complex connecting lines to the controller so the pure signals are apt to be mixed with noised. In the sight of SRM drives, the high temperature, heavy dust, and the EMI surroundings reduce the reliability of speed and position sensors. Therefore, the speed and position sensorless control algorithms using observer have been accepted widely. In this paper An adaptive sliding observer is described to control the SRM without speed or position sensors. The adaptive sliding observer is set on the basis of variable structure control theory. The sliding surface is constructed by current error terms and this surface guarantees the errors converge to "zero". The stability of observer is affirmed by Lyapunov stability analysis and popov's hyper stability theory.ty theory.

• Journal of the Korean Professional Engineers Association
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• v.27 no.2
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• pp.42-54
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• 1994

Nowadays communication network is steadily changing from a main body of telephone to a network which is creating new services such as multimedia etc. Jhis article introduces a bud of new service and new network which are able to sustain the above service. Including Korea, world advanced countries have been digitatizing their network with N-ISDN (narrowband ISDN) by e.g. 64K b/s and 1.5M b/s. New service by N-ISDN are extraordinary, though it can not solve all kinds of services. To solve these problems, a solving platform should be constituted. B-ISDN(broadband ISDN), as a platform has to be built to deal with almost all uinds of services, whatever the communication speed, communication mode or communication quality may be. Korea Telecommunication Authority(KTA) opened the narrowband ISDN(N-ISDN) at the end of 1993. This was one step previous opening of the broadband ISDN(B-ISDN) service scheduled to be rendered in 2001. B-ISDN, receiving and transmitting by far more information with high speed than the N-NSDN does, is one of G-7 Progects which the Korean government is driving foreward to raise the national scientific power to seven advan ced countries. This is also linked with an extremely high speed information network scheduled to be built by the Ministry of Communications in 2015.