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A 15–40 GHz CMOS True-Time Delay Circuit for UWB Multi-Antenna Systems
Sanggu Park,Sanggeun Jeon IEEE 2013 IEEE microwave and wireless components letters Vol.23 No.3
<P>A CMOS true-time delay (TTD) circuit operating from 15 to 40 GHz is presented for integrated UWB multi-antenna systems. The TTD circuit employs a distributed active switching structure in which eight cascode switches are distributed along transmission lines, leading to 3-bit variations of the group delay. The size of the switches and the characteristic impedance of the transmission lines are carefully scaled so as to minimize loss variation among the different delay states, while maintaining flat delay performance over a wide bandwidth. The circuit is implemented in a bulk 0.13-μm CMOS technology and exhibits a total variable group delay of 40 ps with an average resolution of 5 ps from 15 to 40 GHz. The insertion loss was 14 dB with a maximum RMS variation of 1.6 dB, while the input and output return loss was better than 10 dB over the operating bandwidth.</P>
박준영(JunYoung Park),박무룡(MooRyong Park),최상규(SangGu Choi),윤의수(EuiSoo Yoon),황순찬(SoonChan Hwang) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
A centrifugal compressor for geothermal heat pump system using R134a as working fluid has been developed. The centrifugal compressor consists of an impeller with splitters, two vaneless diffuser, a low solidity vaned diffuser and a volute. In this compressor, diffuser blade angles are controlled to satisfy both heating and cooling conditions. A aerodynamic design was done by applying the repeating design procedure including a meanline design, a 3D geometry generation and fluid dynamic calculation. In this paper, design and performance prediction results of the compressor are presented.
For the Positive Definite Sign Pattern Matrices
Lee, Sanggu,Park, Sewon 성균관대학교 기초과학연구소 1994 論文集 Vol.45 No.2
John S.Maybee와 J.Quirk가 행렬이론 안에서 정성적 문제를 다루기 시작하여 부호화 행렬에 관한 많은 연구가 진행되어지고 있는데, 이전에 사용하던 부호화행렬의 곱을 임의의 부호화행렬에 대해서 정의되도록 하므로써 기존의 여러 가지 부호화행렬상의 결과들을 확장 적용할 수 있게 되었으며, 양정치행렬을 정의할 수 있게 되어 실수 행렬상의 고유치 문제와 관계된 결과를 부호화행렬을 이용하여 양의 고유치만을 갖는 실수 행렬의 형태를 규명하도록 한다. A matrix whose entries consist of the symbols +, 1 and 0 is called a sign pattern matrix. In [1], a graph theoretic characterization of sign pattern matrices that allow or require various eigenvalues was given. As we define the new product on sign pattern matrices, we have a definition of a positive (semi)definite sign pattern matrix and similar results relative to the problem of eigenvalues on real matrices.
Wooryung Park,Chibum Song,Sanggu Lee,Lee Kyu-Hwan 대한예방치과학회 2012 International Journal of Clinical Preventive Denti Vol.8 No.3
Objective: The author has measured RLU by use of ART meter at such site of dental environment as dental unit chair, dental light, tray, head rest and spittoon, in order to check the sanitary environment of dental clinic and to reveal the effect of PCMX spray with FlugunTM. Methods: 3% PCMX was used with FlugunTM as an experimental group and the mixed solution of 10% NaOCl and 70% Alcohol was sed as a control group, to compare the RLU before and after sterilization or each group, measuring RLU by use of ATP luminescence at each site and analysed by paired t-test. Results: 1. RLU was the most at the spittoon, before sterilization both in control and in experimental group. 2. RLU decrease rate was more in control group than in experimental group (p<0.05), measured at the spittoon, even though it revealed decrease of RLU after sterilization than before, both in control and in experimental group. 3. RLU decrease rates were more in experimental group than in control group, measured at such site as at the dental light, at the unit tray and at the head rest of the unit chair, but there was no significant different in each group (p>0.05). Conclusion: 3% PCMX with FlugunTM spray was recommended to use for promotion of total hygiene environment of dental clinic for a limited time and not for target area, by consideration.
Wooryung Park,Chibum Song,Sanggu Lee,Lee Kyu-Hwan 대한예방치과학회 2012 International Journal of Clinical Preventive Denti Vol.8 No.3
Objective: The author has measured RLU by use of ART meter at such site of dental environment as dental unit chair, dental light, tray, head rest and spittoon, in order to check the sanitary environment of dental clinic and to reveal the effect of PCMX spray with FlugunTM. Methods: 3% PCMX was used with FlugunTM as an experimental group and the mixed solution of 10% NaOCl and 70%Alcohol was sed as a control group, to compare the RLU before and after sterilization or each group, measuring RLU by use of ATP luminescence at each site and analysed by paired t-test. Results: 1. RLU was the most at the spittoon, before sterilization both in control and in experimental group. 2. RLU decrease rate was more in control group than in experimental group (p<0.05), measured at the spittoon, even though it revealed decrease of RLU after sterilization than before, both in control and in experimental group. 3. RLU decrease rates were more in experimental group than in control group, measured at such site as at the dental light, at the unit tray and at the head rest of the unit chair, but there was no significant different in each group (p>0.05). Conclusion: 3% PCMX with FlugunTM spray was recommended to use for promotion of total hygiene environment of dental clinic for a limited time and not for target area, by consideration. Objective: The author has measured RLU by use of ART meter at such site of dental environment as dental unit chair, dental light, tray, head rest and spittoon, in order to check the sanitary environment of dental clinic and to reveal the effect of PCMX spray with FlugunTM. Methods: 3% PCMX was used with FlugunTM as an experimental group and the mixed solution of 10% NaOCl and 70%Alcohol was sed as a control group, to compare the RLU before and after sterilization or each group, measuring RLU by use of ATP luminescence at each site and analysed by paired t-test. Results: 1. RLU was the most at the spittoon, before sterilization both in control and in experimental group. 2. RLU decrease rate was more in control group than in experimental group (p<0.05), measured at the spittoon, even though it revealed decrease of RLU after sterilization than before, both in control and in experimental group. 3. RLU decrease rates were more in experimental group than in control group, measured at such site as at the dental light, at the unit tray and at the head rest of the unit chair, but there was no significant different in each group (p>0.05). Conclusion: 3% PCMX with FlugunTM spray was recommended to use for promotion of total hygiene environment of dental clinic for a limited time and not for target area, by consideration.