• Journal of Welding and Joining
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• 제32권1호
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• pp.93-101
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• 2014

This study aims to investigate the effect of heat input of outside SAW weld on low temperature toughness($-20^{\circ}C$) of inside SAW weld for API 5L X70 with sour gas resistance. As increasing heat input of the outside weld, low temperature toughness of the inside weld was decreased. Especially, in spite of the same heat input, the value of low temperature toughness was fluctuated. On the basis of fracture and microstructure analysis, the low temperature toughness is correlated with the fracture area ratio of shear lips and four kinds of fracture sections. These sections were divided with size and shape of dimple correlated with grain boundary ferrite and cleavage correlated acicular and polygonal ferrite in grain. Therefore, it was seen that these sections were two of final solidification area in the inside weld and the outside weld, no reheated zone and reheated zone in the inside weld. In conclusion, it is thought that the difference of low temperature toughness at the same heat input is due to the fact that each of impact test specimens could have the different microstructure, even though the notch was machined under the error tolerance of 1mm. It is because the final solidification area of the inside weld is very narrow.

• Journal of Power Electronics
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• 제6권1호
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• pp.83-93
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• 2006

A new high efficiency and low profile on-board DC/DC converter for digital car audio amplifiers is proposed. The proposed converter shows low conduction loss due to the low voltage stress of the secondary diodes, a lack of DC magnetizing current for the transformer, and a lack of stored energy in the transformer. Moreover, since the primary MOSFETs are turned-on under zero-voltage-switching (ZVS) conditions and the secondary diodes are turned-off under zero-current-switching (ZCS) conditions, the proposed converter has minimized switching losses. In addition, the input filter can be minimized due to a continuous input current, and an output inductor is absent in the proposed converter. Therefore, the proposed converter has the desired features, high efficiency and low profile, for a viable power supply for digital car audio amplifiers. A 60W industrial sample of the proposed converter has been implemented for digital car audio amplifiers with a measured efficiency of $88.3\%$ at nominal input voltage.

• STI Policy Review
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• 제1권2호
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• pp.51-68
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• 2010

This paper compares OECD nations by developing a comprehensive evaluation index that examines the efforts and achievements of countries toward Low-Carbon Green Growth. The input-process-output of a Low-Carbon Society system is in dynamic competition with that of a High-Carbon Society system. The model used in this study of the comprehensive evaluation index for Low-Carbon Green Growth was comprised of Large indices such as Input, Process, and Output. The Input and Output consisted of 'Social-economic' and 'Physical-ecological' Middle indices while the Process was made up of 'Stimulation mechanisms' and 'Participation of stakeholders and Knowledge flow' Middle indices. In order to calculate the comprehensive evaluation index, our model gave a weight to each indicator/index and applied a weighted arithmetic mean. Korea ranked $15^{th}$ out of 30 OECD nations in the comprehensive evaluation that analyzed Input ($14^{th}$), Process ($18^{th}$), and Output ($17^{th}$). The top five nations were Switzerland, Sweden, Denmark, Germany, and France; while Japan was $8^{th}$ and the USA $26^{th}$.

• Journal of Welding and Joining
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• 제22권5호
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• pp.58-64
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• 2004

Although leakage at a low carbon steel pipe made by electrical resistance welding (ERW) was reported due to grooving corrosion, the cause for the corrosion has not yet been cleared. In order to clarify the main cause, failure analysis on the leaked pipe was carried out, followed by metallographic investigation and corrosion test for the various ERW pipe made with different welding heat input. The microstructure, particularly inclusion content, of the weldment is dependant on the welding heat input applied. For an improper low heat input, the amount of inclusion at the weld was high. High inclusion content accelerated grooving corrosion at the weld. It is therefore that welding heat input should be controlled based on the carbon content of the pipe in order to improve the corrosion resistance of the ERW pipe.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.161-162
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• 2008

In this paper we design an irregular low-density parity-check (LDPC) code for a multi-input multi-output (MIMO) system. The considered MIMO system is minimum mean square error soft-interference cancellation (MMSE-SIC) detector. The MMSE-SIC detector and the LDPC decoder exchange soft information and consist a turbo iterative detection and decoding receiver. Extrinsic information transfer (EXIT) charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the input-output transfer chart of the MMSE-SIC detector. It is shown that the performance of the designed LDPC code is much better than that of conventional LDPC code optimized for the AWGN channel.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.101-104
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• 2002

This paper propose that is algorithm of power dissipation reduction in the high level synthesis design for DSP(Digital Signal Processor), as the portable terminal system recently demand high power dissipation. This paper obtain effect of power dissipation reduction and switching activity that increase correlation of operands as input data of function unit. The algorithm search loop or repeatedly data to the input operands of function unit. That can be reduce the power dissipation using the new low power high level synthesis algorithm. In this Paper, scheduling operation search same nodes from input DFG(Data Flow Graph) with correlation coefficient of first input node and among nodes. Function units consist a multiplier, an adder and a register. The power estimation method is added switching activity for each bits of nodes. The power estimation have good efficient using proposed algorithm. This paper result obtain more Power reduction of fifty percents after using a new low power algorithm in a function unit as multiplier.

• 한국전자통신학회논문지
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• 제9권9호
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• pp.1027-1034
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• 2014

3G부터 4G LTE까지의 전체 대역에 적용이 가능한 저전력, 광대역 저잡음증폭기를 설계하였다. 설계한 광대역 다중입력 저잡음증폭기는 기존의 3G인 CDMA의 대역인 1.2GHz대역과 LTE대역인 2.5GHz대역까지 넓은 주파수 대역을 안정적으로 증폭이 가능하고, 다중입력방식을 통해 입력신호의 크기에 관계없이 안정적인 증폭이 가능하도록 설계하였다. 설계된 저잡음증폭기는 1.2V의 공급전압에서 약 0.6mA의 전류를 소모하고, 이는 Cadence사의 컴퓨터 시뮬레이션을 통해 검증하였다. 낮은 입력신호에 대응한 증폭은 최대 20dB이고, 신호에 따라 최저 -10dB의 이득값을 얻을 수 있었다. 잡음특성(NF : Noise Figure)은 High Gain모드에서 15dB이하, Low Gain 모드에서 3dB이하를 가진다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.114-119
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• 1991

An input estimation technique for tracking filter(CHP algorithm) suggested by Y.T. Chan et. al. has bad performance for low maneuvering targets. In this paper, two maneuver detection algorithms are applied to Singer's target model. First, an CHP input estimation technique is applied to 9 state target model. Second, we construct a maneuver detection and correction technique using pseudo acceleration measurements, which are derived directly from measurements. These two filters have good performance for even the low maneuvering targets.

• ETRI Journal
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• 제29권1호
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• pp.45-49
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• 2007

The poly-Si thin film transistor (TFT) shows large variations in its characteristics due to the grain boundary of poly-crystalline silicon. This results in unacceptably large input offset of low-voltage differential signaling (LVDS) receivers. To cancel the large input offset of poly-Si TFT LVDS receivers, a full-digital offset compensation scheme has been developed and verified to be able to keep the input offset under 15 mV which is sufficiently small for LVDS signal receiving.

• 전기학회논문지
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• 제66권12호
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• pp.1721-1724
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• 2017

This paper presents a numerical optimization technique to reduce input current and torque ripple of the low voltage BLDC motor using core, coil and switching angle optimization. The optimization technique is employed using the generalized response surface method(RSM) and sampling minimization technique with FEM. A 50W 24V BLDC motor is used to verify the proposed algorithm. As optimizing results, the input current is reduced from 2.46 to 2.11[A], and the input power is reduced from 59 [W] to 51 [W] at the speed of 1000 [rpm]. Also, applied the same optimization algorithm, the torque ripple is reduced about 7.4 %. It is confirmed that the proposed technique is a reasonably useful tool to reduce the consuming current and torque ripple of the low voltage BLDC motor for a compact and efficient design.