• Title/Summary/Keyword: TDC

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Molecular Analysis of the Salmonella Typhimurium tdc Operon Regulation

  • Kim, Min-Jeong;Lim, Sang-Yong;Ryu, Sang-Ryeol
    • Journal of Microbiology and Biotechnology
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    • v.18 no.6
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    • pp.1024-1032
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    • 2008
  • Efficient expression of the Salmonella Typhimurium tdc ABCDEG operon involved in the degradation of L-serine and L-threonine requires TdcA, the transcriptional activator of the tdc operon. We found that the tdcA gene was transiently activated when the bacterial growth condition was changed from aerobic to anaerobic, but this was not observed if Salmonella was grown anaerobically from the beginning of the culture. Expression kinetics of six tdc genes after anaerobic shock demonstrated by a real-time PCR assay showed that the tdc CDEG genes were not induced in the tdcA mutant but tdcB maintained its inducibility by anaerobic shock even in the absence of tdcA, suggesting that an additional unknown transcriptional regulation may be working for the tdcB expression. We also investigated the effects of nucleoid-associated proteins by primer extension analysis and found that H-NS repressed tdcA under anaerobic shock conditions, and fis mutation delayed the peak expression time of the tdc operon. DNA microarray analysis of genes regulated by TdcA revealed that the genes involved in N-acetylmannosamine, maltose, and propanediol utilization were significantly induced in a tdcA mutant. These findings suggest that Tdc enzymes may playa pivotal role in energy metabolism under a sudden change of oxygen tension.

Comparison of tdcA Expression Between Escherichia coli and Salmonella enterica Serovar Typhimurium

  • Kim, Min-Jeong;Lim, Sang-Yong;Ryu, Sang-Ryeol
    • Journal of Microbiology and Biotechnology
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    • v.21 no.3
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    • pp.252-255
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    • 2011
  • Both Escherichia coli (E. coli) and Salmonella enterica serovar Typhimurium (S. Typhimurium) have a tdc operon that encodes enzymes involved in a metabolic pathway for the degradation of L-serine and L-threonine. However, S. Typhimurium does not have the tdcR gene, which is a positive regulator in E. coli. In the present study, transcriptional analysis revealed that tdcA expression in E. coli is higher under anaerobic than aerobic growth conditions, but the opposite is true in S. Typhimurium. Interestingly, a tdcR mutant strain of E. coli showed a similar expression pattern to that observed in S. Typhimurium and was also induced by anaerobic shock. These results suggest that the induction of tdcA expression by anaerobic conditions is observable when tdcA expression is low owing to the absence of TdcR.

A Study on the Performance Improvement of a Time-to-Digital Converter (시간-디지털 변환기의 성능 개선에 대한 연구)

  • Ahn, Tae-Won;Lee, Jong-Suk;Moon, Yong
    • 전자공학회논문지 IE
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    • v.49 no.1
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    • pp.1-6
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    • 2012
  • For the performance improvement of a time-to-digital converter(TDC), a 2-stage high resolution TDC has been designed by using a 2-stage vernier time amplifier(2-S VTA). The two stage vernier time amplifier which has a gain over 64 of the resolution can enhance the resolution of the whole two stage TDC. Because of using a vernier TDC, the structure is not limited to advanced processes for achieving high resolution. The proposed TDC has been designed in a $0.18{\mu}m$ CMOS process and simulated with a 1.8V supply voltage. The entire input range is 512ps, and the full resolution 0.125ps.

A Study on the Noise Improvement of All Digital Phase-Locked Loop Using Time-to-Digital Converter (시간-디지털 변환기를 이용한 ADPLL의 잡음 개선에 대한 연구)

  • Ahn, Tae-Won;Lee, Jongsuk;Lee, Won-Seok;Moon, Yong
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.2
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    • pp.195-200
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    • 2015
  • This paper presents SVBS-TDC (Semi-Vernier Binary-Search Time-to-Digital Converter) for the noise improvement of ADPLL (All-Digital Phase Locked Loop. We used a Semi-Vernier BS-TDC (Binary-Search TDC) architecture to improve the operation speed more then 10 times compared with the previous conventional BS-TDC and ensured a 510ps wide input range. The proposed Semi-Vernier BS-TDC was designed in a 65ns CMOS process and the simulation results showed 200MHz speed and 4ps resolution with a 1.2V supply voltage, and considerable noise improvement of ADPLL.

Study of Effective Stiffness and Effective Strength for a Pinwheel Model combined with Diamond Truss-Wall Corrugation (P-TDC) (다이아몬드 트러스 벽면으로 구성된 P-TDC 모델의 강성 및 강도 연구)

  • Choi, Jeong-Ho
    • Journal of the Korean Society of Industry Convergence
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    • v.19 no.3
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    • pp.109-124
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    • 2016
  • The objective of this paper is to find the density, stiffness, and strength of truss-wall diamond corrugation model combined with pinwheel truss inside space. The truss-wall diamond corrugation (TDC) model is defined as a unit cell coming from solid-wall diamond corrugation (SDC) model. Pinwheel truss-wall diamond corrugation (P-TDC) model is made by TDC connected with pinwheel structure inside of the space. Derived ideal solutions of P-TDC is based on truss-wall and pinwheel truss model at first. And then it is compared with Gibson-Ashby's ideal solution. To validate the ideal solutions of the P-TDC, ABAQUS software is used to predict the density, strength, and stiffness, and then each of them are compared to the ideal solution of Gibson-Ashby with a log-log scale. Applied material property is stainless steel 304 because of having cost effectiveness. Applied parameters for P-TDC are 1 thru 5 mm diameter within fixed opening width as 4mm. In conclusion, the relative Young's modulus and relative yield strength of the P-TDC unit model is reasonable matched to the ideal expectations of the Gibson-Ashby's theory. In nearby future, P-TDC model is hoped to be applied to make sandwich core structure by advanced technologies such as 3D printing skills.

Modified Time Delay Control for Servo with Friction (마찰이 있는 서보의 변형된 시지연제어)

  • Park, J.H.;Kim, Y.M.
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.6
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    • pp.106-113
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    • 1997
  • A new algorithm based upon TDC (Time Delay Control) is proposed to improve the robustness of TDC performance in systems where the stick-slip friction is strong. Experiments were performed at the different levels of friction. The reponses of the TDC and the modified TDC were compared each other, and against those of a PID controller with an anti-windup. The results show that the TDC and the modified TDC equally perform better than the PID, and that the modified TDC performs consistently well even with variations in the friction level while the TDC does not.

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Causes of Top Dead Center Error in Marine Generator Engine Power-Measuring Device (선박용 발전기 엔진 출력 측정 장치의 TDC 오차 발생 원인)

  • Lee, Ji-Woong;Jung, Gyun-Sik;Lee, Won-Ju
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.4
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    • pp.429-435
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    • 2020
  • Different methods are used for determining the output of engines to obtain the indicated horsepower by measuring the combustion pressure of cylinders, and to obtain the shaft horsepower by measuring the shaft torque. It is difficult to examine the shaft torque using the condition of the cylinder, and the most accurate method used for determining the combustion pressure involves examining the combustion state of the cylinder to evaluate the engine performance and analyze the combustion of the cylinder. During the measurement, the combustion pressure is the most important parameter used for accurately determining the cylinder angle because the cylinder pressure is indicated based on the angle of the crankshaft. In this study, an encoder was used as the crank angle sensor to measure the cylinder pressure on the generator engine of the actual operating ship. The reasons for the differences between the top dead center (TDC) recognized by the encoder (TDCencoder) and the TDC recognized by the compression pressure (TDCcomp) were considered. The dif erences between the TDCcomp and TDCencoder of the cylinders measured at idle running, 25 %, 50 %, and 60 % loads were analyzed to determine for the crankshaft production effect, the crankshaft torsion effect owing to the increased rotational resistance from the increased load, and the coupling damping effect between the engine and generator. It was confirmed that the TDC error occurred up to 3° crank angle as the load of the generator increased.

The management effect of TDC(Total Dental Care) internship program (일개 대학 치위생과 대학생들의 TDC(Total Dental Care) 인턴십 프로그램의 운영효과)

  • Cho, Min-Jung;Kim, Eun-Mi;Ha, Myung-Ok
    • Journal of Korean society of Dental Hygiene
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    • v.14 no.2
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    • pp.147-154
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    • 2014
  • Objectives : The purpose of the study is to identify the efficiency of total dental care(TDC) internship program. Methods : Dental hygiene students participated in the total dental care(TDC) internship program for 4 weeks in dental clinics practice. A self-reported questionnaire was filled out from June to July in 2012. The questionnaire consisted of oral health condition and dental care services by the students, dentists, and dental hygienists after TDC internship program. Results : Satisfaction degree of the students was $3.92{\pm}0.68$ points. The patients satisfied with TDC internship program and it was helpful to their dental health care(4.0 points). There were significant changes in tooth brushing method, frequency and O'Leary plaque index. Satisfaction degree of the dentists was 4.09 points and that of the dental hygienists was 3.80 points. Conclusions : TDC internship program is very helpful for the students not only to play an outstanding role in their dental care activities after employment but also to establish the real identity of the dental hygienist.

Correction of TDC Position for Engine Output Measuring in Marine Diesel Engines (선박용 디젤엔진의 출력산정을 위한 TDC 위치보정에 관한 연구)

  • Jung, Kyun-Sik;Choi, Jun-Young;Jeong, Eun-Seok;Choi, Jae-Sung
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.4
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    • pp.459-466
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    • 2012
  • The accurate engine output is basically one of important factors for the analysis of engine performance. Nowadays in-cylinder pressure analysis in internal combustion engine is also an indispensable tool for engine research and development, environment regulation and maintenance of engine. Here, it is essential more than anything else to find the correct TDC(Top Dead Center) position for the accuracy of engine output for diesel engine. Therefore this study is to analyze affecting factors to TDC position in 2-stroke large low speed engine and to suggest new method for determining correct TDC position. In the previous paper, it was mentioned that the accuracy of engine output is influenced by the determination of exact TDC position, and that 'Angle based sampling' method is better than 'Time based sampling' method in terms of precision. It was confirmed that there is 'Loss of angle', which is a difference between compression pressure peak and real TDC caused by heat loss and blow by of gas leakage. Consequently we invented new method, called "An improved method of time based sampling", which can obtain the correct engine output. The results by this method with compensating loss of angle was shown the same result by the 'Angle based sampling' method in encoder setting cylinder. This study is to suggest the new measuring method of exact engine output, and to examnine the reliance on the outcome.

A Design of Vernier Coarse-Fine Time-to-Digital Converter using Single Time Amplifier

  • Lee, Jongsuk;Moon, Yong
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.12 no.4
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    • pp.411-417
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    • 2012
  • A Coarse-Fine Time-to-Digital Converter (TDC) using the single time amplifier is proposed. A vernier delay line is used to overcome process dependency and the 2-stage time amplifier is designed to have high resolution by increasing the gain of the time amplifier. Single time amplifier architecture reduces the silicon area of the TDC and alleviates mismatch effect between time amplifiers. The proposed TDC is implemented in $0.18{\mu}m$ CMOS process with the supply voltage of 1.8 V. The measured results show that the resolution of the TDC is 0.73 ps with 10-bit digital output, although highend process is not applied. The single time amplifier architecture reduces 13% of chip area compared to previous work. By reducing the supply voltage, the linearity of the TDC is enhanced and the resolution is decreased to 1.45 ps.