• The Journal of the Acoustical Society of Korea
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• v.18 no.5
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• pp.52-57
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• 1999

It is very important to design of QAM modulator of high spectral efficiency for high speed data transmission. In this paper, typical 16-QAM modulator is designed by modification design of DDFS(direct digital frequency synthesizer). DDFS generates sinusoidal waveform digitally to the frequency setting word. Phase modulation is accuratly made by control of a generated phase increment value and amplitude modulation is accomplished in the D/A converter output by control of amplitude level. For the suppression of harmonics and glitch, dual-structured DDFS is studied to improve the spurious characteristics. P-Spice is used for design and simulation in mixed mode. Also we can get the satisfactory results of designed 16-QAM modulator from the constellation output.

• Progress in Superconductivity and Cryogenics
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• v.6 no.2
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• pp.25-28
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• 2004

Three-phase inductive superconducting fault current limiter (SFCL) with DC reactor rated on 6.6 $KV_{rms}/200 A_{rms}$ has been developed in Korea. This system consists of one DC reactor, AC/DC power converter, and a three-phase transformer, which is called magnetic core reactor (MCR). This paper deals with the short-circuit analysis of the SFCL. The DC reactor was the HTS solenoid coil whose inductance was 84mH. The power converter was performed as the dual-mode operation for dividing voltage between the rectifying devices. The short-term normal operation (1 see) and short-circuit tests (2∼3 cycles) of this SFCL were performed successfully. In regular short-circuit test, the fault current was limited as 30% of rated short-circuit current at 2 cycles after the fault. The experimental results have a very similar tendency to the simulation results. Using the technique for the fault detection and SCR firing control, the fault current limiting rate of the SFCL was improved. From this research, the parameters for design and manufacture of large-scale SFCL were obtained.

• Tuberculosis and Respiratory Diseases
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• v.44 no.6
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• pp.1318-1325
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• 1997

Background : Since the late 1960s, mechanical ventilation has been accomplished primarily using volume controlled ventilation(VCV). While VCV allows a set tidal volume to be guaranteed, VCV could bring about excessive airway pressures that may be lead to barotrauma in the patients with acute lung injury. With the increment of knowledge related to ventilator-induced lung injury, pressure controlled ventilation(PCV) has been frequently applied to these patients. But, PCV has a disadvantage of variable tidal volume delivery as pulmonary impedance changes. Since the concept of combining the positive attributes of VCV and PCV(dual control ventilation, DCV) was described firstly in 1992, a few DCV modes were introduced. Pressure-regulated volume control(PRVC) mode, a kind of DCV, is pressure-limited, time-cycled ventilation that uses tidal volume as a feedback control for continuously adjusting the pressure limit However, no clinical studies were published on the efficacy of PRVC until now. 'This investigation studied the efficacy of PRVC in the patients with unstable respiratory mechanics. Methods : The subjects were 8 mechanically ventilated patients(M : F=6 : 2, $56{\pm}26$ years) who showed unstable respiratory mechanics, which was defined by the coefficients of variation of peak inspiratory pressure for 15 minutes greater than 10% under VCV, or the coefficients of variation of tidal volume greater than 10% under PCV. The study was consisited of 3 modes application with VCV, PCV and PRVC for 15 minutes by random order. To obtain same tidal volume, inspiratory pressure setting was adjusted in PCV. Respiratory parameters were measured by pulmonary monitor(CP-100 pulmonary monitor, Bicore, Irvine, CA, USA). Results : 1) Mean tidal volumes($V_T$) in each mode were not different(VCV, $431{\pm}102ml$ ; PCV, $417{\pm}99ml$ ; PRVC, $414{\pm}97ml$) 2) The coefficient of variation(CV) of $V_T$ were $5.2{\pm}3.9%$ in VCV, $15.2{\pm}7.5%$ in PCV and $19.3{\pm}10.0%$ in PRVC. The CV of $V_T$ in PCV and PRVC were significantly greater than that in VCV(p<0.01). 3) Mean peak inspiratory pressure(PIP) in VCV($31.0{\pm}6.9cm$ $H_2O$) was higher than PIP in PCV($26.0{\pm}6.5cm$ $H_2O$) or PRVC($27.0{\pm}6.4cm$ $H_2O$)(p<0.05). 4) The CV of PIP were $13.9{\pm}3.7%$ in VCV, $4.9{\pm}2.6%$ in PVC and $12.2{\pm}7.0%$ in PRVC. The CV of PIP in VCV and PRVC were greater than that in PCV(p<0.01). Conclusions : Because of wide fluctuations of VT and PIP, PRVC mode did not seem to have advantages compared to VCV or PCV in the patients with unstable respiratory mechanics.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.595-602
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• 2023

The EAST ICRF system operating space has been extended in power and phase control with a low-level RF system for the new double-strap antenna. Then the multi-step power and periodic phase scanning experiment were conducted in L-mode plasma, respectively. In the power scanning experiment, the stored energy, radiation power, plasma impedance and the antenna's temperature all have positive responses during the short ramp-ups of P_L;ICRF. The core ion temperature increased from 1 keV to 1.5 keV and the core heating area expanded from |Z| ≤ 5 cm to |Z| ≤ 10 cm during the injection of ICRF waves. In the phasing scanning experiment, in addition to the same conclusions as the previous relatively phasing scanning experiment, the superposition effect of the fluctuation of stored energy, radiation power and neutron yield caused by phasing change with dual antenna, resulting in the amplitude and phase shift, was also observed. The active control of RF output facilitates the precise control of plasma profiles and greatly benefits future experimental exploration.

• Journal of Power Electronics
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• v.11 no.4
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• Journal of Ocean Engineering and Technology
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• v.19 no.2 s.63
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• pp.67-73
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• 2005

This paper describes depth, heading and speed control of an underwater vehicle that has four stern thrusters of which forces are coupled in the diving and, steering motion, as well as the speed of the vehicle. The optimal linear quadratic controller is designed based on a linearized- state space model, developed by combining the dynamic equations of speed, steering and diving motion. The designed controller gives provides an optimal thrust distribution, minimizing the given performance index to control speed, depth and heading simultaneously. To validate the performance of the controller, a simulation and tank-test are carried out with DUSAUV (Dual Use Semi-Autonomous Underwater Vehicle), developed by KORDI as a test-bed for testing new underwater technologies. Optimal gains of the controller are tuned, using a computer simulation environment with a nonlinear 6-DOF numerical DUSAUV model, developed by PMM (Planner Motion Mechanism) test. To verify the performance of the presented controller in experiment, a tank-test with DUSAUV is carried out in the ocean engineering basin in KORDI. The experimental results are also compared with the simulation results to investigate the accordance of the numerical and the real mode.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.104.1-104
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• 2003

To screen for potential biocontrol agents against postharvest disease of garlics caused by Penicillium hirsutum, a total of 933 isolates (432 fungi and 501 bacteria) were isolated from the rhizoshere or rhizoplane of garlics. Among them, Pantoea agglomerans isolate 59-4 (Pa 59-4) was selected for a potential biocontrol agent by in vivo wounded garlic bulb assay, When the spore suspension (10$\^$5/ spores/$m\ell$) of Penicillium hirsutum was co-inoculated with spore or cell suspension of each fungal or bacterial isolate on wounded garlics, the isolate highly suppressed disease development. Soaking garlic bulbs in the suspension of Pa 59-4 significantly reduced garlic decay from p. hirsutum. However, Pa 59-4 did not inhibit the mycelial growth of P. hirsutum in dual-culture with P. hirsutum on Tryptic soy agar. In order to elucidate mode of action of Pa 59-4 nutrient competition between Pa 59-4 and P. hirsutum was investigated using tissue culture plates with cylinder inserts containing defusing membrane reported by Janisiewicz et al. The results showed that Pa 59-4 effectively suppressed spore germination and mycelial growth of blue mold in the low concentration (0.5％) of garlic juice, but did not suppress those of blue mold in the higher concentration (5％) of garlic juice. This result suggests that the mechanism in biocontrol of garlic blue mold by Pa 59-4 may involve in nutrient competition with P. hirsutum on garlic bulbs.

• The Korean Journal of Pain
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• v.29 no.3
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• pp.153-157
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• 2016

Tapentadol is a novel oral analgesic with a dual mode of action as an agonist of the ${\mu}$-opioid receptor (MOR), and as a norepinephrine reuptake inhibitor (NRI) all in a single molecule. Immediate release (IR) tapentadol shows its analgesic effect quickly, at around 30 minutes. Its MOR agonistic action produces acute nociceptive pain relief; its role as an NRI brings about chronic neuropathic pain relief. Absorption is rapid, with a mean maximal serum concentration at 1.25-1.5 h after oral intake. It is present primarily in the form of conjugated metabolites after glucuronidation, and excretes rapidly and completely via the kidneys. The most common adverse reactions are nausea, dizziness, vomiting, and somnolence. Constipation is more common in use of the ER formulation. Precautions against concomitant use of central nervous system depressants, including sedatives, hypnotics, tranquilizers, general anesthetics, phenothiazines, other opioids, and alcohol, or use of tapentadol within 14 days of the cessation of monoamine oxidase inhibitors, are advised. The safety and efficacy have not been established for use during pregnancy, labor, and delivery, or for nursing mothers, pediatric patients less than 18 years of age, and cases of severe renal impairment and severe hepatic impairment. The major concerns for tapentadol are abuse, addiction, seeking behavior, withdrawal, and physical dependence. The presumed problem for use of tapentadol is to control the ratio of MOR agonist and NRI. In conclusion, tapentadol produces both nociceptive and neuropathic pain relief, but with worries about abuse and dependence.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.56-65
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• 2007

The effect of gain dispersion on the self-pulsation (SP) characteristics due to the mode beating of two modes emitted in a multisection DFB laser composed of two complex-coupled DFB sections and a phase control section is investigated. When the peak wavelength, ${\lambda}_{p}$, of the gain spectrum of the DFB section is positioned in the center of the lasing wavelengths or the Bragg wavelengths of the two DFB sections, the maximum SP frequencies are higher and the modulation index has better characteristics compared to those cases for ${\lambda}_{p}$ fixed at the lasing wavelength or Bragg wavelength of one DFB section, when the difference between the Bragg wavelengths of the two DFB sections, ${\Dalta}{\lambda}_{B}$, is varied. When ${\lambda}_{p}$ is positioned in the renter of the Bragg wavelengths of the two DFB sections, the maximum SP frequency is higher and of the modulation index has better characteristics compared to those of the case for ${\lambda}_{p}$ positioned in the center of the lasing wavelengths of the two DFB sections.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.11
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• pp.909-917
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• 2021

In this work, a one-dimensional combustor solver was constructed for the scramjet control m odel. The governing equations for fluid flow, Arrhenius based combustion kinetics, and the inje ction model were implemented into the solver. In order to validate the solver, the zero-dimensi onal ignition delay problem and one-dimensional scramjet combustion problem were considered and showed that the solver successfully reproduced the results from the literature. Subsequentl y, a ramjet analysis algorithm under subsonic speed conditions was constructed, and a study o n the inlet Mach number of the combustor was carried out through the thermal choking locatio ns at ram conditions. In such conditions, a model for precombustion shock train analysis was i mplemented, and the algorithm for transition section analysis was introduced. In addition, in or der to determine the appropriateness of the ram mode analysis in the code, the occurrence of a n unstart was studied through the length of the pseudo-shock in the isolator. A performance a nalysis study was carried out according to the geometry of the combustor.