• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.270-274
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• 2006

This paper proposes a Chaos Pulse Width Modulation(CPWM) technique. For generating the chaotic numbers by chaos phenomenon, chaos area $\lambda$=0.99 in bifurcation tree of the proposed double tent mapping is used. A micro-controller is used for the generation of chaos numbers and triangular carrier with chaotic frequency is obtained through the process of frequency modulation according to the generated chaos numbers. The experiments are executed with the 1.5kw induction motor coupled with a 2.5A load. The experimental results show that the voltage / current spectra are spread to a chaotic range, and the switching noise of motor is reduced by the proposed method compared to the fixed frequency PWM method.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1682-1691
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• 2015

In this paper, a real time implementation of selective harmonic elimination pulse width modulation (SHEPWM) using Real Coded Genetic Algorithm (RGA), Particle Swarm Optimization technique (PSO) and a new technique known as Linearization Method (LM) for Single Phase Matrix Converter (SPMC) is designed and discussed. In the proposed technique, the switching frequency is fixed and the optimum switching angles are obtained using simple mathematical calculations. A MATLAB simulation was carried out, and FFT analysis of the simulated output voltage waveform confirms the effectiveness of the proposed method. An experimental setup was also developed, and the switching angles and firing pulses are generated using Field Programmable Gate Array (FPGA) processor. The proposed method proves that it is much applicable in the industrial applications by virtue of its suitability in real time applications.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.32-35
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• 2001

In sheet metal forming process, it is very important to nest blanks optimally to get a maximum utilization ratio(UR) to reduce waste of material. Optimal Blank Nesting algorithm is developed about single nesting, double nesting, fixed slitting width and free slitting width. This algorithm was applied to various practical blanks which are under production. Then new optimal nesting configuration was obtained and higher UR was achieved by this program in each cases.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권4호
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• pp.493-500
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• 2015

A flyback converter operates with either pulse width modulation (PWM) or pulse frequency modulation (PFM) control scheme depending on the load current. At light load condition, PFM control is employed to reduce the switching frequency and thereby minimize the switching power loss. For heavier load, PWM control is used to regulate the output voltage of the flyback converter. The flyback controller has been implemented in a $0.35{\mu}m$ BCDMOS process and applied to a 40-W flyback converter. The light-load power efficiency of the flyback converter is improved up to 5.7-% comparing with the one operating with a fixed switching frequency.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.747-750
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• 2003

We have studied PHEMTs optimization by means of fabrication of PHEMTs. All PHEMTs have been fixed with a gate length of 0.1 ${\mu}{\textrm}{m}$, a gate head size of 0.75${\mu}{\textrm}{m}$, and two gate fingers. We have measured the characteristics of PHEMTs with variation of source-drain spacing, pad size, and gate width. As a result, we have found the enhanced characteristics of $I_{dss}$, $S_{21}$, $h_{21}$, $f_{T}$, $f_{max}$, and $G_{ms}$ with increasing gate width. Also, $g_{m}$ has improved with decreasing source-drain spacing, and $S_{21}$ has improved with deceasing pad size.e.e.e.e.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.63-64
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• 2009

The TFTs have been fabricated with 3 different geometry SID electrodes which have the same channel W/L ratio (W/L = 5) due to constant channel resistance, The 3 samples have different channel widths (350, 150, and $25\;{\mu}m$) and channel lengths (70, 30, and $5\;{\mu}m$) by fixed channel W/L ratio simultaneously on one chip for reliable comparisons. Resultant on-current and field effect mobility are proportional to the channel width, while the subthreshold swing is inversely proportional to the channel width mainly due to the change of contact resistance. These results show that the contact resistance strongly affects the device performances and should be considered in the applications.

• 대한가정학회지
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• 제42권8호
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• pp.203-218
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• 2004

Recently, knitted materials are used more often than ever before in fashion. Therefore it is necessary to study their application into garment patterns. The purpose of this study was to develop a system by which the tensile property of knitted fabrics can be applied. In this study, 5 different distribution methods of tensile property were tested on 2 sample fabrics which have a lower and higher tensile property than moderate-stretch. The subjects were five women within an age range from 18 to 24 who showed average body figures. The major findings derived from this investigation were as follows; The 4th method was regarded as the most valid. The 4th method was fixed proportional alteration based on the reduction amount of bust girth, i.e. front (back) width and shoulder width reduced by 60％ of the bust girth reduction and neck point reduced by 28％ of the bust girth reduction. When the reduction was based on the proportion of the actual measurements, the alteration was too severe, so that the armhole curve was changed into a very uncomfortable curve.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1623-1628
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• 2008

A temperature gradient focusing (TGF) via Joule heating phenomenon was numerically studied. The governing transport equations are implemented into a quasi-1D numerical model to predict the resulting temperature, velocity, and concentration profiles along a microchannel of varying width under an applied electric field. The model is used to analyze the effects of varying certain geometrical parameters of a microchannel on the focusing performance of the device. We show the effects of varying width of the microchannel having a fixed length, and propose the optimal geometry of the device. This method can be easily implemented into lab-on-a-chip (LOC) applications where focusing is required based on its simple design.

• Restorative Dentistry and Endodontics
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• 제39권3호
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• pp.226-229
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• 2014

Orthodontic extrusion is usually performed by means of a fixed orthodontic appliance that utilizes arch wire attached to adjacent teeth and transfers the desired force by elastic from the wire to the root. However, clinicians often encounter cases where the bonding required for tooth traction is not possible because the adjacent teeth have been restored with ceramic or veneer. The purpose of this case report is to describe a modified orthodontic extrusion appliance that is useful when conventional orthodontic treatment is not possible. The modified appliance was fabricated using an artificial tooth, clear plastic sheeting, and a braided fiber-reinforced composite strip that covered adjacent teeth without bonding. It satisfied the esthetic and functional needs of the patient and established the optimal biologic width.

• 한국시뮬레이션학회논문지
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• 제11권3호
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• pp.35-48
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• 2002

In the work presented here, we describe a method to extract TrueType features for supporting letter recognition. Even if variously existing document processing techniques have been challenged, almost few methods are capable of recognize a letter associated with its TrueType features supporting OCR free, which boost up fast processing time for image text retrieval. By reviewing the mechanism generating digital fonts and birth of TrueType, we realize that each TrueType is drawn by its contour of the glyph table. Hence, we are capable of deriving the segment with density for a letter with a specific TrueType, defined by the number of occurrence over a segment width. A certain number of occurrence appears frequently often due to the fixed segment width. We utilize letter recognition by comparing TrueType feature library of a letter with that from input word images. Experiments have been carried out to justify robustness of the proposed method showing acceptable results.