• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.325-326
• /
• 2006

This paper proposes a new frame interpolation algorithm mainly designed for intra-mode blocks. In order to improve the accuracy of pixel interpolation, the new algorithm exploits two different interpolation modes for inter-mode blocks and intra-mode blocks, respectively. The use of the two modes reduces ghost artifacts but increases blocking artifacts between the blocks interpolated by different modes. To reduce blocking artifacts, this paper proposes an interpolation algorithm that attempts to isolate a fast moving object and interpolates such objects as the intra-mode while the remaining blocks are interpolated as the inter-mode. Simulation results show that the proposed algorithm improves subjective and objective quality of pictures by reducing ghost artifacts.

• 조명전기설비학회논문지
• /
• 제21권4호
• /
• pp.19-27
• /
• 2007

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost H-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switch mode equivalent circuits and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft-switching(ZVS) operation ranges, and the power dissipation as compared with those of the conventional type high frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation(PWM) and pulse density modulation(PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• 한국항해학회지
• /
• 제14권4호
• /
• pp.41-52
• /
• 1990

부유식 진동수주형 파력발전기는 불규칙한 해상 상태에서의 작동으로 인하여 흡수효율의 저하를 필수적으로 수반한다. 본 논문에서는 입사파의 에너지를 적절히 흡수할 수 있는 파력발전기를 초기설계하여 모델로 이용하였으며, 이 모델의 유체력추정에는 3차원 특이점 분포법을 사용하였다. 그리고, 가변구조 시스템으로 알려진 슬라이딩 모드기법을 이용하여 파의 상태 변화에 따른 파력발전기의 자세와 위치를 제어함으로써 흡수파력의 효율을 중대시킬 수 있는 시스템을 제안하고 있다.

• 전기학회논문지
• /
• 제57권6호
• /
• pp.966-971
• /
• 2008

Free-piston engine system is a new type energy converter which uses a linear motion of piston by using linear generator. In free-piston engine system, the piston is not connected to a crank-shaft. The major advantages of free-piston engine system are high efficiency and low mechanical loss from the absence of motion conversion devices. Linear generator of free-piston engine system is used as generator and starting motor. In design step, considering of back-emf and detent force characteristics for generating mode and thrust and control characteristics for starting mode is needed. In this research, generating mode of flat-type linear generator and tubular-type linear generator is analyzed by finite element analysis method and starting mode of both type linear generators is analyzed by using capability curve. Capability curve is plotted from electrical parameters of both type linear generator and motion profile is calculated from mechanical parameters.

• 비파괴검사학회지
• /
• 제29권6호
• /
• pp.586-590
• /
• 2009

Poisson's ratio, one of elastic constants of elastic solids, has not attracted attention due to its narrow range and difficult measurement. Transverse wave velocity as well as longitudinal wave velocity should be measured for nondestructive measurement of Poisson's ratio. Rigid couplants for transverse wave is one of obstacle for scanning over specimen. In the present work, a novel measurement of Poisson's ratio distribution was applied. Immersion method was employed for the scanning over the specimen. Echo signals of normal beam longitudinal wave were collected, and transverse wave modes generated by mode conversion were identified. From transit time of longitudinal and transverse waves, Poisson's ratio was determined without the information of specimen thickness. Poisson's ratio distribution of the carbon steel weldment was mapped. Heat affected zone of the weldment was clearly distinguished from base and filler metals.

• 비파괴검사학회지
• /
• 제28권6호
• /
• pp.519-523
• /
• 2008

Poisson's ratio is one of elastic constants of elastic solids. However, it has not attracted attention due to its narrow range and difficult measurement. Transverse wave velocity as well as longitudinal wave velocity should be measured for nondestructive measurement of Poisson's ratio. Hard couplant for transverse wave prevents transducer from scanning over specimen. In the present work, a novel measurement of Poisson's ratio distribution was proposed. Immersion method was employed for the scanning over the specimen. Echo signals of normal beam longitudinal wave were collected. Transverse wave modes generated by mode conversion were identified. From transit time of longitudinal and transverse waves, Poisson's ratio can be determined without information of specimen thickness. This technique was demonstrated for aluminum and steel specimens.

• 소음진동
• /
• 제8권6호
• /
• pp.1172-1180
• /
• 1998

음향학적으로 강성인 물체와 연성인 물체로부터의 탄성파의 산란과 음향파의 산란을 수치적으로 해석하고 그 특성들을 비교하였다. 부분파들과. 또한 부분파들의 합인 전체 산란파의 위상 및 크기의 거동을 수치적으로 분석하고 토의하였다. 탄성파의 산란시 발생하는 종파와 횡파 사이의 모드변환 현상이 산란파의 크기와 위상에 주는 영향을 밝혔다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
• /
• pp.37-38
• /
• 2012

Two catalyst systems with different content of precious metal coated on DOC are carefully tested in a diesel engine to investigate the emission characteristics of $NO_2$. Three types of experiment methods ($NO_2$ conversion test, ETC mode test, and BPT test) are applied to compare the performance of the two catalyst systems. All the experimental results consistently indicate that it is possible to satisfy $NO_x$ regulation by properly lowering the content of precious metal without the loss of PM removal performance.

• 한국철도학회논문집
• /
• 제2권2호
• /
• pp.39-45
• /
• 1999

This paper presents the current-fed inverter of a TGV-K traction system with thyristor switches using phase control and commutation techniques. The current-fed inverters have two modes of operation which consist of forced commutation and natural commutation. In forced commutation mode, at speed of less than 120km/h, commutation is forced by means of the commutation capacitors and the thyristors. Above 120km/h, the thyristors operate in natural commutation mode. according to the voltages between phases of the motors. In this paper. the power conversion theory of the TGV-K traction system and the control principle of the converter and current-fed inverter are discussed.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 추계종합학술대회 논문집
• /
• pp.689-692
• /
• 1999

This paper describes a 10-bit 75-MHz CMOS current-mode DAC designed for 0.8${\mu}{\textrm}{m}$ double-poly double-metal CMOS technology. This D/A converter is implemented using a current cell matrix that can drive a resistive load without output buffer. In the DAC. a current source is proposed to reduce the linearity error caused by the threshold-voltage variations over a wafer and the glitch energy caused by the time lagging, The integral and differential linearity error are founded to be within $\pm$0.35 LSB and $\pm$0.31 LSB respectively. The maximum conversion rate is about 80 MS/s. The total power dissipation is 160 ㎽ at 75 MS/s conversion rate.