• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집(한일합동학술편); 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.780-785
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• 1987

The measuring point data of clay model are widely used to design parts whose external features are important design factor such as automobiles and general die products. This paper presents a method for improving the process to generate smooth surfaces from the measuring point data using turnkey CAD/CAM system. The process of smooth-surface generation involves several steps: styline finding, curve fairing, surface generation and filleting. The process is improved by automatic curve fairing, local correction of surface and multi-boundary surface treatment. An automobile bumper and a telephone receiver are measured and modeled to test the new method. Significant time saving is resulted by changing interactive mode to automatic mode and eliminating inefficient loop of surface generation process.

• 전자공학회논문지D
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• 제35D권7호
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• pp.102-108
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• 1998

A new 1*4 optical waveguide power divider is proposed and fabricated. It consists of a 1*4 multi-branch structure with a beam separator and two beam expanders that can control the splitting ratios between the output ports. The proposed optical waveguide power divider is designed by employing the two dimensional finite difference beam propagation method and is fabricated by a reactive ion etching method. The splitting ratio of fabricatd device is 25.0 : 25.7 : 25.3 : 24.0 for TE mode and 25.7 : 25.2 : 24.1 : 25.0 for TM mode. Comapred with the conventional Y-branch structure, the proposed structure shortens the length of a 1*N divider by the factor 3. Thus it reduces the total propagation loss and the total radiation loss at the branch points. furthermore, the splitting ratios between the output ports may be controlled in this structure for some special applications.

• 반도체디스플레이기술학회지
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• 제3권2호
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• pp.5-9
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• 2004

Microcircuit fabrication requires precise control of impurities in tiny regions of the silicon. These regions must be interconnected to create components and VLSI circuits. The patterns to define such regions are created by lithographic processes. In order to image features smaller than 70 nm, it is necessary to employ non-optical technology (or next generation lithography: NGL). One such NGL is extreme ultra-violet lithography (EUVL). EUVL transmits the pattern on the wafer surface after reflecting ultra-violet through mask pattern. If particles exist on the blank mask, it can't transmit the accurate pattern on the wafer and decrease the reflectivity. It is important to care the blank mask. We removed the particles on the wafer using focused ion beam (FIB). During removal, FIB beam caused damage the multi layer mask and it decreased the reflectivity. The relationship between particle removal and reflectivity is examined: i) transmission electron microscope (TEM) observation after particle removal, ii) reflectivity simulation. It is found that the image mode of FIB is more effective for particle removal than spot and bar mode.

• Nuclear Engineering and Technology
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• 제35권3호
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• pp.226-233
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• 2003

The discharge characteristics of a prototype ion source was investigated, which was developed and upgraded for the NBI (Neutral Beam Injection) heating system of KSTAR (Korea Superconducting Tokamak Advanced Research). The ion source was designed for the arc discharge of magnetic bucket chamber with multi-pole cusp fields. The ion source was discharged by the emission-limited mode with the control of filament heating voltage. The maximum ion density was 4 times larger than the previous discharge controlled by a space-charge-limited mode with fully heated filament. The plasma (ion) density and arc current were proportional to the filament voltage, but the discharge efficiency was inversely proportional to the operating pressure of hydrogen gas. The maximum ion density and arc current were obtained with constant arc voltage ($80{\sim}100V$), as $8{\times}10^{11}cm^{-3}$ and 1200 A, respectively. The estimated maximum beam current was about 35 A, extracted by the accelerating voltage of 80kV.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1455-1458
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• 2002

In this paper, we propose a modified CP-AFC(Cross-Product Automatic Frequency Control) algorithm to enhance coherent signal detection for WCDMA reverse link receiver. We introduce a moving average filter at the FDD(Frequency Difference Detector) input to increase the number of cross-products, since pilot symbol in WCDMA is not transmitted continuously. We also add normalization algorithm to overcome the conventional CP-FDD's sensitivity to the variance of input signal amplitude and to increase the linear range of S- curve. For rapid frequency acquisition and tracking, we adopt a multi-stage tracking mode. We applied the proposed algorithm in the implementation of WCDMA base station modem successfully.

• 드라이브 ㆍ 컨트롤
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• 제14권2호
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• pp.30-36
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• 2017

This paper presents a sliding mode observer-based fault detection algorithm for steering inputs of an all-terrain crane. All-terrain cranes with multi-axles have several steering modes for various working purposes. Since steering angles at the other axles except the first wheel are controlled by using the information of steering angle at the first wheel, a reliable signal of the first axle's steering angle should be secured for the driving safety of cranes. For the fault detection of steering input signal, a simplified crane model-based sliding mode observer has been used. Using a sliding mode observer with an equivalent output injection signal that represents an actual fault signal, a fault signal in steering input was reconstructed. The road steering mode of the crane's steering system was used to conduct performance evaluations of a proposed algorithm, and an arbitrary fault signal was applied to the steering angle at the first wheel. Since the road steering mode has different steering strategies according to different speed intervals, performance evaluations were conducted based on the curved path scenario with various speed conditions. The design of algorithms and performance evaluations were conducted on Matlab/Simulink environment, and evaluation results reveal that the proposed algorithm is capable of detecting and reconstructing a fault signal reasonably well.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.114-123
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• 1998

The multi-resonant converter(MRC) minimizes a parasitic oscillation by using the resonant tank circuit absorbed parasitic reactances existing in a converter circuit. So it si possible that the converter operated at a high frequency has a high efficiency because the losses are reduced. Such a MHz high frequency applications provide a high power density [W/inch3] of the converter. But the resonant voltage stress across a switch of the resonant tank circuit is 4~5 times a input voltage. This h호 voltage stress increases the conduction loss because of on-resistance of a MOSFET with higher rating. Thus, in this paper we proposed the alternated multi-resonant converter (AT MRC) differ from the clamp mode multi-resonant converter and applicated it to the forward MRC. The AT forward MRC can reduce the voltage stress to 2~3 times a input voltage by using two series input capacitor. The control circuit is simple because tow resonant switches are driven directly by the output pulse of the voltage controled oscillator. This circuit type is verified through the experimental converter with 48V input voltage, 5V/50W output voltage/power and PSpice simulation. the measured maximum voltage stress is 170V of 2.9 times the input voltage and the maximum efficiency of 81.66% is measured.

• 소성∙가공
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• 제22권3호
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• pp.133-142
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• 2013

Recently, electric vehicles and hybrid cars are being promoted as alternatives to reduce automobile emissions. Generally, thin sheet materials such as aluminum alloy AA300X and cold-rolled steel sheet such as JIS-G-3141 are used for the container for the lithium-ion secondary batteries. In this study, a multi-stage deep drawing process is used to produce a rectangular cup from thin stainless steel sheet material, SUS409L, with an initial blank thickness of 0.4mm for the battery container application. Numerical simulations of the first through the fifth stages for the multi-stage deep drawing with thin SUS409L sheet were conducted using LS-Dyna3D Implicit/Explicit. Special consideration was given to the deformation characteristics due to the normal anisotropy of the sheet material. The numerical simulations were conducted with both isotropic properties and the anisotropic properties of the initial blank material. An unexpected forming failure, barreling in the bottom region of the deep drawn rectangular cup, was observed. This failure mode can be avoided by additional ironing thickness control during the process.

• 제어로봇시스템학회논문지
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• 제21권5호
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• pp.447-452
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• 2015

A hybrid power system was developed for agricultural machines with a 20kW output capacity, and it was attached to a multi-purpose cultivator to improve the performance of the cultivator. The hybrid system combined heterogeneous sources: an internal-combustion engine and an electric power motor. In addition, a power splitter was developed to simplify the power transmission structure. The cultivator using a hybrid system was designed to have increased fuel efficiency and output power and reduced exhaust gas emissions, while maintaining the functions of existing cultivators. The fuel consumption for driving the cultivator in the hybrid engine vehicle (HEV) mode was 341g/kWh, which was 36% less than the consumption in the engine (ENG) mode for the same load. The maximum power take off output of the hybrid power system was 12.7kW, which was 38% more than the output of the internal-combustion engine. In the HEV mode, harmful exhaust gas emissions were reduced; i.e., CO emissions were reduced by 36~41% and NOx emissions were reduced by 27~51% compared to the corresponding emissions in the ENG mode. The hybrid power system improved the fuel efficiency and reduced exhaust gas emissions in agricultural machinery. The hybrid system's lower exhaust gas emissions have considerable advantages in closed work environments such as crop production facilities. Therefore, agricultural machinery with less exhaust gas emissions should be commercialized.

• 전력전자학회논문지
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• 제20권2호
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• pp.105-114
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• 2015

Heated glasses are widely used to prevent surface condensation and freezing in ship and building windows. This study proposes a heated glass temperature control system composed of power and control circuits to control the temperature of heated glasses. The proposed temperature control system adopts a digital controller instead of a conventional analog controller. Thus, the proposed system has better characteristics, such as precise setup and control of glass temperature, setup and control of output power, and control mode change between ON/OFF and phase controls. The system can also implement multi-functional control algorithms. The control characteristics are not dependent upon external disturbances, such as ambient temperature and electrical noises. Furthermore, the proposed temperature control system utilizes the power line communication (PLC) method to control the number of heated glasses without any extra communication lines. The system proposes a new communication protocol with strong immunity to electrical switching noises. A new sensorless algorithm is used to detect the temperature of the heated glass. This study presents the design guidelines in detail and its effectiveness are confirmed by implementing a 4-kw prototype temperature control system.