• 한국기계가공학회지
• /
• 제4권2호
• /
• pp.37-42
• /
• 2005

Recently $6{\sigma}$ quality control is an most important strategy to many enterprises in order to be a top company in the world, because it is an excellent scientific method to achieve the best quality control for their management and products. SY company is a small and medium one that has the quality problem for a long time such as occurring cracks on the surface of commutator at his assembly line while being assembled a rotor shaft and commutator of DC motor. This research was started to improve this problem by $6{\sigma}$ process, and as the results of this study, first, to find three vital fews, second, to get an achievement of about 21% improvement for the fracture strength of commutator, and third, to be recognized to change into $6{\sigma}$ quality control in SY company.

• Journal of Semiconductor Engineering
• /
• 제2권1호
• /
• pp.109-118
• /
• 2021

This review paper describes the overall operating principle of a discrete-time delta-sigma modulator (DTDSM) and a continuous-time delta-sigma modulator (CTDSM) using a switched-capacitor (SC). In addition, research that has solved the problems related to each delta-sigma modulator (DSM) is introduced, and the latest developments are explained. This paper describes the chopper-stabilization technique that mitigates flicker noise, which is crucial for the DSM. In the case of DTDSM, this paper addresses the problems that arise when using SC circuits and explains the importance of the operational transconductance amplifier performance of the first integrator of the DSM. In the case of CTDSM, research that has reduced power consumption, and addresses the problems of clock jitter and excess loop delay is described. The recent developments of the analog front end, which have become important due to the increasing use of wireless sensors, is also described. In addition, this paper presents the advantages and disadvantages of the three-opamp instrumentation amplifier (IA), current feedback IA (CFIA), resistive feedback IA, and capacitively coupled IA (CCIA) methods for implementing instrumentation amplifiers in AFEs.

• 감성과학
• /
• 제20권1호
• /
• pp.31-40
• /
• 2017

이 연구는 뉴로 마케팅의 여러 연구 기법들 중 시선추적 기술(Eye-tracking)을 이용하여 농구 경기 장면 중 남성의 동공이 전체 데이터의 3시그마 범위를 벗어난 상위 0.135 % 비율로 동공이 확장 되었을 때의 시선 관찰 및 관심도를 측정하였다. 특히 동공 크기 확장과 관련해서 시선추적 기술의 데이터 중 어느 정도의 범위일 때의 크기가 유의미하다고 밝히기는 힘들기 때문에 이 연구에서는 전체 데이터 중 상위 3시그마 범위를 동공이 확장되어지는 범위로 설정하였다. 실험에 사용된 장면은 농구 경기 중 한 상황으로 설정하였으며, 총 7,200개의 데이터 중 유효율 90 %가 넘는 유효데이터가 산출되었고 이를 통해 34명의 데이터 중 유효데이터에 해당하지 않아 사용할 수 없는 데이터를 제외한 29명의 데이터를 사용하였다. 동공의 크기를 구하기 위해 동공의 너비(Pupil Width)와 높이(Pupil Height) 값을 [동공의 크기 = 동공의 너비/2${\times}$동공의 높이/$2{\times}{\pi}$] 공식에 대입하였다. 분석한 결과 농구경기장 내 마케팅으로 활용되기 위해 사용된 광고판들은 크게 영향력을 끼치지 않았다. 관중으로서의 피험자들의 동공의 크기가 커졌을 때, 경기장내에 광고판 보다는 선수들 혹은 주변 배경에 주시빈도가 높았다. 이 연구를 통하여 무분별하게 광고판을 사용하기보다는 뉴로마케팅을 이용하여 경기장내 마케팅 및 광고판 효용성을 높이는 방안의 필요성이 요구된다.

• Bulletin of the Korean Chemical Society
• /
• 제33권7호
• /
• pp.2168-2176
• /
• 2012

Relations between fitted parameters for photoionization spectra both below and above the thresholds in the systems involving 3 channels are obtained using phase-shifted version of the multichannel quantum-defect theory. Analytical continuation of the photoionization cross sections in the form of ${\langle}{\sigma}_{below}{\rangle}_{v_{below}}={\sigma}_{above}$ examined using several representations.

• 전기학회논문지
• /
• 제57권6호
• /
• pp.1081-1086
• /
• 2008

This paper presents the $3^{rd}$ 4bit sigma delta modulator with the block and timing diagrams of DWA(Data Weighted Averaging) to optimize a operating time. In the modulator, the proposed DWA structure has a stable operation and timing margin so as to remove three latches and another clock. Because the modulator with proposed DWA structure improve timing margin about 23%. It can increase sampling frequency up to 244MHz. Through the MATLAB modeling, the optimized coefficients are obtained to design the modulator. The fully differential SC integrators, DAC, switch, quantizer, and DWA are designed by considering the nonideal characteristics. The designed $3^{rd}$ order 4bit modulator has a power consumption of 40mW and SNR(signal to noise ratio) of 77.2dB under 1.2V supply and 64MHz sampling frequency.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
• /
• pp.125-130
• /
• 2002

The most important material parameters are fracture energy and the stress-crack opening displacement($\sigma$-w) curve to determine the behavior of concrete. Especially, the relationship between the $\sigma$-w curve is strongly important to determine the load-displacement curve of concrete that has a major influence on the fracture behavior of a concrete. In this paper, notched plain concrete beams with different strength level were tested under three-point bending and fracture energy, the load-deflection curve, and the load-crack mouth opening displacement(CMOD) curve were obtained from the experimental data. Also, the fictitious crack model(FCM) was applied to determine the load-deflection curve of notched plain concrete beams using various types of $\sigma$-w curve model proposed by Petersson and we compared experimental results with numerical ones carried out by Finite Element Method(FEM).

• 한국농공학회논문집
• /
• 제51권6호
• /
• pp.83-90
• /
• 2009

This study was carried out to evaluate the vertical stress properties in sandy soil according to changes of loading type in soil bin compacted three layers. The following conclusions and comparisons have been made based on careful analysis from theoretical and experimental methods. : When sandy soil subjected to cycle-loading, compression of foundation and diffusion of vertical stress increment(${\Delta}{\sigma}_2$) were influenced by magnitude of loading plate. When sandy soil subjected to reloading after removing of pre-loading, the distribution of ${\Delta}{\sigma}_2$ depth at one time of loading plate width was different from its distribution at more deep point cause of load hysteresis, so in case of design of structure, the effect of ${\Delta}{\sigma}_2$ as depth must be considered. The increment of vertical stress will be different as loading condition and foundation depth, the loading condition must be considered in case of structure design.

• International Journal of Internet, Broadcasting and Communication
• /
• 제5권2호
• /
• pp.11-14
• /
• 2013

This paper describes the sigma-delta ADC/DAC digital block with two channels. The ADC block has comb filter and three half band filters. And the DAC block has 5th Cascaded-of-Integrators Feedback DSM. The ADC and DAC support I2S, RJ, LJ and selectable input data modes of 24bit, 20bit, and 16bit. It is fabricated with 0.35um Hynix standard CMOS cell library. The chip size is 3700*3700um. It has been verified using NC Verilog Simulator and Matlab Tool.

• Bulletin of the Korean Chemical Society
• /
• 제32권12호
• /
• pp.4195-4198
• /
• 2011

Intramolecular ${\pi}-{\pi}$ and ${\sigma}-{\pi}$ interactions are omnipresent for numerous energetic and structural phenomena in nature, and the exact description of these nonbonding interactions plays an important role in the accurate prediction of the three-dimensional structures for numerous interesting molecular systems such as protein folding and polymer shaping. We have selected two prototype molecular systems for benchmarking calculations of intramolecular ${\pi}-{\pi}$ and ${\sigma}-{\pi}$ interactions. Accurately describing conformational energy of such systems requires highly elaborate but very expensive ab initio methods such as coupled cluster singles, doubles, and (triples) (CCSD(T)). Our calculations reveal a double hybrid density functional incorporating dispersion correction (B2PLYP-D) that agrees excellently with the CCSD(T) results, indicating that B2PLYP-D can serve as a practical method of choice.

• Structural Engineering and Mechanics
• /
• 제42권5호
• /
• pp.701-713
• /
• 2012

Results pertaining to 3D investigations on the effect of the thickness on the stress fields at the crack front are presented. A 3D finite element analysis is performed using a modified single edge-notched tension specimen configuration, with an inclined crack to include mixed mode I-II. A technique to mesh the crack front (3D) with singular finite elements in ANSYS without using third party software is introduced and used in this study. The effect of the specimen thickness is explicitly investigated for six thicknesses ranging from 1 to 32 mm. In addition, three crack inclination angles, including pure Mode-I, are used to study the effect of mixed-mode I-II fracture. An attempt is made to correlate the extent of a particular stress state along the crack front to thickness. In addition, ${\sigma}_{zz}/{\nu}({\sigma}_{xx}+{\sigma}_{yy})$ contours at the crack front are presented as a useful means to analyze the stress state.