• Journal of IKEEE
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• v.22 no.4
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• pp.1158-1162
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• 2018

A fast-lock multiplying delay-locked loop (MDLL)-based digital clock frequency multiplier with an anti-harmonic lock capability is presented. The proposed digital frequency multiplier utilizes a new most-significant bit (MSB)-interval search algorithm to achieve fast-locking time without harmonic lock problems. The proposed digital MDLL frequency multiplier is designed in a 65nm CMOS process, and the operating output frequency range is from 1 GHz to 3 GHz. The digital MDLL provides a programmable fractional-ratio frequency multiplication ratios of N/M, where N = 1, 4, 5, 8, 10 and M = 1, 2, 3, respectively. The proposed MDLL consumes 3.52 mW at 1GHz and achieves a peak-to-peak (p-p) output clock jitter of 14.07 ps.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.220-229
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• 2000

In the brake systems a proportioning valve which reduces the brake pressure at each wheel cylinder for anti-locking of rear wheels is closely related with the safety of vehicles. But, it is impossible for a present proportioning valve to exactly control brake pressure because mechanically it is an open loop control system. So, in this paper we describe a electronic brake pressure distribution system using a fuzzy controller in order to exactly control brake pressure using a close loop control system. The object of electronic brake pressure distribution system is to change an cut-in pressure and an valve slop of proportioning valve in order to obtain better good performance of brake system than with mechanical system.

• Korean System Dynamics Review
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• v.15 no.4
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• pp.61-84
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• 2014

This study aims to explore the development and application of a simulated skills package designed to improve nursing students' knowledge integration and their system thinking(ST) skills about congestive heart failure(CHF) and to identify the change in students' ST levels using a ST-based learning approach. A simulated learning support package was developed by nurse educators and ST experts. The developed program was implemented with 35 third-year nursing students from S university in Seoul. The subjects improved their ST skills regarding CHF after intervention. Mean test scores for students completing the program were significantly higher than pre-intervention scores, including measures of direction of causality, polarity of causal relationship, feedback loop, polarity of feedback loop (reinforcing, balancing) and time delay (t=2.26~6.53, p=.030~p<.001). It is suggested that more educational programs be developed on various topics in order for nursing students to improve their ST skills as well as knowledge integration in clinical nursing practicum packages.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.359-360
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• 2002

A bacterial strain able to degrade terephthalic acid (TPA) was isolated and identified to belong to the Corynebacterium sp. It was named Corynebacterium sp. YT-14. When stirred loop bioreactor was used in a batch type system for removing terephthalic acid from weight loss treatment wastewater and complex dyeing process wastwater, the removal efficiency of terephthalic acid was 85.4% after 7 days of treatment of the weight loss treatment wastewater, while no residual terephthalic acid was detected after 3 days of treatment of the complex dyeing process wastewater

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.164-167
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• 1996

This paper presents an off-line P.I.D parameter estimation method during normal operation in power plant. The process parameters are estimated using the recursive least square method. The controller parameters are estimated on the basis of desired characteristics of the dynamic model of the closed-loop control.

• Journal of Power Electronics
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• v.11 no.1
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• pp.59-63
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• 2011

This paper presents the modeling of the sampling effect in the p-type average current mode control. The prediction of the high frequency components near half of the switching frequency in the current loop gain is given for the p-type average current mode control. By the proposed model, the prediction accuracy is improved when compared to that of conventional models. The proposed method is applied to a buck converter, and then the measurement results are analyzed.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.10
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• pp.771-782
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• 1991

In industrial multivariable plants, it is ofte the case that the plant outputs are measured in similar components not simultaneously but serially. In this paper, the problem of estimating the state vector of the plant based on the data obtained from such a measuring scheme is considered, and a special type of observer(referred to as a $'$multiple serial-sampling$'$ type observer) which renews its internal states whenever a new group of data is obtained is proposed. It is proved that such an observer can be constructed for almost every sampling period if the palnt is observable as a continuous-time multivariable system, and that the poles of the closed-loop system using the multiple serial-sampling type observer consist of the poles of the observer and those of the state feedback system. The behaviors of the observer and the closed-loop system are studied by simulation. The results of simulation indicate that a multiple serial-ampling type observer can estimate the state of the plant more accurately than the ordinary type observers and improve the closed-loop performance, especially, in the existence of measuring noise.ng noise.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.65-72
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• 2008

This paper proposes a new dual-loop digital PLL(DPLL) using seamless frequency tracking methods. The dual-loop construction, which is composed of the coarse and fine loop for fast locking time and a switching noise suppression, is used successive approximation register technique and TDC. The proposed DPLL in order to compensate the quality of jitter which follows long-term of input frequency is newly added cord conversion frequency tracking method. Also, this DPLL has VCO circuitry consisting of digitally controlled V-I converter and current-control oscillator (CCO) for robust jitter characteristics and wide lock range. The chip is fabricated with Dongbu HiTek $0.18-{\mu}m$ CMOS technology. Its operation range has the wide operation range of 0.4-2GHz and the area of $0.18mm^2$. It shows the peak-to-peak period jitter of 2 psec under no power noise and the power dissipation of 18mW at 2GHz through HSPICE simulation.

• Clean Technology
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• v.23 no.2
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• pp.205-212
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• 2017

We investigated the performance of a jet loop reactor (JLR) with the two-fluid venturi-type swirl nozzle (TVSN) during experiment for ammonia removal by air stripping from a synthetic wastewater, and compared it with that of a JLR with the two-fluid venturi-type conventional nozzle (TVCN), with the variation of pH, liquid circulation rate ($Q_L$), and air flow rate ($Q_G$). Their performance levels were compared based on the ammonia removal efficiency and overall mass transfer coefficient ($K_La$). Investigated parameters in a JLR were pH (10-12), air flow rate ($Q_G=5-20L\;min^{-1}$), and liquid circulation rate ($Q_L=25-35L\;min^{-1}$). Throughout the experiment, the ammonia removal efficiency and $K_La$ in a JLR with TVSN was higher than in a JLR with TVCN. This may be due to the enhanced turbulent intensity by swirling flow formed in the JLR with TVSN compared to that with TVCN. Further, we obtained higher $K_La$ when pH, $Q_L$ and $Q_G$ were increased. In particular, $K_La$ was increased more efficiently by increasing $Q_G$ than by increasing pH and $Q_L$.

• Journal of the Korean Society of Radiology
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• v.84 no.6
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• pp.1350-1360
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• 2023

Purpose To evaluate the factors that predict symptomatic dislodgement of a percutaneous transhepatic biliary drainage (PTBD) catheter in patients with malignant biliary obstruction. Materials and Methods This retrospective study included 572 patients with malignant biliary obstruction who underwent 733 PTBD catheter insertions between January 2010 and February 2015. The duration of catheter placement, approach site, location of the catheter tip, insertion angle, presence of a closed-loop pigtail, and tube diameter were evaluated. Results During the follow-up period, 224 PTBD catheter dislodgements (30.56%) were observed in 157 patients. Among them, 146 (19.92%) were symptomatic. The mean duration from catheter insertion until dislodgement was 32 days (range: 1-233 days). Male (odds ratio [OR]: 1.636, 95% confidence interval [CI]: 1.131-2.367, p = 0.009), right-sided approach (OR: 1.567, 95% CI: 1.080-2.274, p = 0.018), increased insertion angle (OR: 1.015, 95% CI: 1.005-1.026, p = 0.005), and incomplete closed-loop pigtail formation (OR: 1.672, 95% CI: 1.098-2.545, p = 0.016) were independent factors predictive of symptomatic dislodgement of a PTBD catheter. Conclusion Factors predictive of symptomatic catheter dislodgement included male sex, a right-sided approach, increased insertion angle, and incomplete closed-loop pigtail formation.