• The Journal of the Korea institute of electronic communication sciences
• /
• v.4 no.1
• /
• pp.33-36
• /
• 2009

Incremental converters provide a solution for such measurement applications, as they retain most of the advantages of conventional ${\Delta}{\Sigma}$ converters, and yet they are capable of offset-free and accurate conversion. Most of the previous research on incremental converters was for single-channel and dc signal applications, where they can perform extremely accurate data conversion with more than 20-bit resolution. In this paper, a design technique for implementing multi-channel incremental data converters to convert narrow bandwidth ac signals is discussed. It incorporates the operation principle, topology, and digital decimation filter design. The theoretical results are verified by simulation results.

• Journal of the Korean Society of Safety
• /
• v.14 no.1
• /
• pp.25-32
• /
• 1999

The objective of this paper is to evaluate the fracture resistance characteristics of SA508 CL.1a carbon steel, TP347 stainless steel and their associated welds manufactured for primary coolant system of Ulchin 3,4 nuclear power plants. The effect of various parameters such as pipe size, welding method, chemical composition, crack plane orientation, metallography and fractography on the material properties were discussed. Test results showed that the effect of pipe size on fracture toughness is negligible while the effect of welding method on fracture toughness is significant. In addition, the drop of fracture toughness in the field fabrication weld of TP347 stainless steel is probably due to the large amount of $\sigma$-phase precipitated on the $\delta$-ferrite boundary and the large size dimples.

• Proceedings of the KIEE Conference
• /
• 1998.07g
• /
• pp.2411-2413
• /
• 1998

In this paper, using tile concept of block digital filtering, and the design procedure of time-interleaved oversampling converter are presented. it is shown that arbitrary sigma-delta A/D converter can be converted into corresponding time-interleaved structure. The TIM structure of this paper is designed by the bilinear transform. To verify the simulation results, a second-order TIM structure A/D converter has been implemented and the design process as well as experimented results are presented.

• ETRI Journal
• /
• v.33 no.2
• /
• pp.169-175
• /
• 2011

This paper presents a double-sharpened decimation filter based on the application of a Kaiser and Hamming sharpening technique for multistandard wireless systems. The proposed double-sharpened decimation filter uses a pre-droop compensator which improves the passband response of a conventional cascaded integrator-comb filter so that it provides an efficient sharpening performance at half-speed with comparison to conventional sharpened filters. In this paper, the passband droop characteristics with compensation provides -1.6 dB for 1.25 MHz, -1.4 dB for 2.5 MHz, -1.3 dB for 5 MHz, and -1.0 dB for 10 MHz bandwidths, respectively. These results demonstrate that the proposed double-sharpened decimation filter is suitable for multistandard wireless applications.

• Proceedings of the IEEK Conference
• /
• 2000.07b
• /
• pp.1041-1044
• /
• 2000

The enhancement to the back-propagation algorithm presented in this paper has resulted from the need to extract sparsely connected networks from networks employing product terms. The enhancement works in conjunction with the back-propagation weight update process, so that the actions of weight zeroing and weight stimulation enhance each other. It is shown that the error measure, can also be interpreted as rate of weight change (as opposed to ${\Delta}W_{ij}$), and consequently used to determine when weights have reached a stable state. Weights judged to be stable are then compared to a zero weight threshold. Should they fall below this threshold, then the weight in question is zeroed. Simulation of such a system is shown to return improved learning rates and reduce network connection requirements, with respect to the optimal network solution, trained using the normal back-propagation algorithm for Multi-Layer Perceptron (MLP), Higher Order Neural Network (HONN) and Sigma-Pi networks.

• Journal of Industrial Technology
• /
• v.18
• /
• pp.203-208
• /
• 1998

Fatigue tests were performed to examine the 4 parameter method for specimens prepared by various heat treatment which resulted in different mechanical properties. Obtained main results are as follows. (1) Samples treated by austempering did not show the expected improvement of fatigue limit although hardness and strength increased. This is attributed to the fact that defect sensitivities of materials increase as increasing of hardness and tensile strength, it is also shown that the graphites acting as stress concentration place become larger by austempering heat treatment than by normal annealing. (2) It is very reasonable to predict the fatigue limit of ductile irons with 4 parameter method based on ${\sigma}_{TS}$, $H_v$, ${\Delta}K_{th}$ and ${\sqrt{area}}_{max}$. (3) The half-austempering treatment appeared to be more useful than the full-austempering method to improve the fatigue limit in the spheroidal graphite cast iron with multi defective material.

• Kyungpook Mathematical Journal
• /
• v.57 no.3
• /
• pp.401-417
• /
• 2017

Ever since their introduction, skew PBW ($Poincar{\acute{e}}$-Birkhoff-Witt) extensions of rings have kept growing in importance, as researchers characterized their properties (such as primeness, Krull and Goldie dimension, homological properties, etc.) in terms of intrinsic properties of the base ring, and studied their relations with other fields of mathematics, as for example quantum mechanics theory. Many rings and algebras arising in quantum mechanics can be interpreted as skew PBW extensions. Our aim in this paper is to study skew PBW extensions of Baer, quasi-Baer, principally projective and principally quasi-Baer rings, in the case when the base ring R is not assumed to be reduced. We just impose some mild compatibleness over the base ring R, and prove that these properties are stable over this kind of extensions.

• Journal of Power Electronics
• /
• v.14 no.4
• /
• pp.796-805
• /
• 2014

A digital controller with a low-power approach for point-of-load synchronous buck converters is discussed and compared with its analog counterpart to confirm its feasibility for system integration. The tri-mode digital controller IC in $0.35{\mu}m$ CMOS process is presented to demonstrate solutions that include a PID, quarter PID, and robust RST compensators. These compensators address the steady-state, stand-by, and transient modes according to the system operating point. An idle-tone free condition for ${\Sigma}-{\Delta}$ DPWM reduces the inherent tone noise under DC-excitation. Compared with that of the traditional approach, this condition generates a quasi-pure modulation signal. Experimental results verify the closed-loop performances and confirm the power-saving mechanism of the proposed controller.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.818-821
• /
• 2010

본 논문에서는 차량 레이더 시스템용 시그마-델타 변조기를 제안한다. 개발된 변조기는 차량 레이더 시스템에서 고주파 대역 신호의 고해상도 데이터 변환, 즉 아날로그-디지털변환을 수행하는데 사용되며 저전압 및 저 왜곡 특성을 가진 몸체효과 보상형 스위치 구조로 구현되어 있다. 제안된 변조기는 0.25 마이크론 이중 폴리 3-금속 표준 CMOS 공정으로 제작되었고, $1.9{\times}1.5mm^2$의 다이 면적을 점유한다. 제안된 회로는 2.7V의 동작 전압에서 기존의 부트스트랩형 회로보다 약 20dB 향상된 우수한 총 고조파 왜곡 특성을 보였다.

• The KIPS Transactions:PartC
• /
• v.10C no.4
• /
• pp.455-462
• /
• 2003

Techniques for the reduction of SRTS jitter and pointer adjustment jitter are studied. To reduce the stuffing jitter several methods have been proposed, such as bit leaking, stuff threshold modulation and sigma delta modulation. The characteristics of jitter generated in SRTS and pointer adjustment systen implementing these reduction techniques is analyzed with computer simulation. The results show that ms jitter value decreases to less than 50% as compared to a conventional pointer adjustment system. The amplitude of SRTS jitter using new techniques decreases or Increases dependent on system parameter.