• Journal of Industrial Technology
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• v.21 no.B
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• pp.59-66
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• 2001

In this paper, a novel overmodulation strategy for PWM inverters to extend linearity region is presented. The proposed strategy uses the concept of space-vector PWM(SVPWM) based on the zero sequence signal(offset voltage) injection principle. So, by modifying the pole voltage simply, the linear control of inverter output voltage over the whole overmodulation range can be achieved easily. The proposed strategy is so simple that its practical implementation is easy. The validity of the proposed strategy is confirmed by the experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1259-1265
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• 2013

In wireless environment such as wireless LAN, proper location of wireless LAN AP allows us to take an effective coverage to provide good wireless communication service. To simulate wireless environment, FDTD formulation is introduced and Gaussian pulse injection in grid space is considered to be replaced wireless LAN AP. So structural effect corresponding to location of arbitrary obstacle must be considered, and its received gain is estimated. An obstacle in scattering field should be modeled to be conductor and concrete wall and its diffraction effect for some cross wall is evaluated between transmitter and receiver point.

• Journal of the Korean Vacuum Society
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• v.8 no.4B
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• pp.548-555
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• 1999

The NBI (Neutral BGeam Injection) System for the Korea Superconducting Tokamak Advanced Research (KSTAR) is composed of ion sources, neutralizers, bending magnets, ion dumps, and calorimeter. The vacuum chamber, in which all of the beam line components are enclosed, is composed of differential pumping system for the effective transfer of the neutral beams. The needed pumping speeds of each of the divided vacuum chamber and the optimized gas flow rate ot the neutralizer were calculated with the help of the particle balance equations. The minimum gas flow rate to the ion sources for producing needed beam current (120kV, 65A, 78MW), the pressure distributions in the vacuum chamber for minimizing re-ionization loss, and the beam loss rate on the beam line components were used as the input in the calculation. Also the scenario for short pulse operation was determined by analysing the time dependent equations. It showed that beam extraction during less than 0.5 sec could be made only with TMP.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.35-38
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• 2003

The purpose of this work is to introduce the 1-N grade thruster development program for attitude control of satellites and lunch vehicle systems. Characteristics of the thruster and its performance have been evaluated through hot-firing test of small liquid engine inside a vacuum test cell. Performance evaluation of thruster were made with a variation of propellant injection pressure at steady state and pulse firing mode, respectively. Also hot-fire test system and test procedure are briefly described, too.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.924-927
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• 2003

Aluminium-doped ZnO (ZnO:Al) films were grown by atomic layer-controlled deposition on glass substrates at temperature of 200 $^{\circ}C$ using diethylzinc($Zn(C_{2}H_{2})_{2}$; DEtZn), water($H_{2}O$) and trimethylaluminium ($Al(CH_{3})_{3}$; TMA) as precursors. As the cycle ratio of TMA to DEZn(TMA/DEZn) increased, the resistivity of the films decreased and the roughness increased. In the case of TMA/DEZn pulse ratio of 1 to 10, the film had a resistivity of $9.7{\times}l0^{-4}{\Omega}{\cdot}cm$ and a roughness of 2.25nm(rms), while in the case of only DEZ injection the film had a resistivity of $3.5{\times}10^{-3}{\Omega}{\cdot}cm$ and a roughness of 1.07nm(rms)

• The Journal of the Korean dental association
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• v.11 no.1
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• pp.45-52
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• 1973

Ketamine HC1(Phencyclidine derivative) is a white, crystalline substance with melting point 259℃. It is soluble in water to a 20% clear, colorless solution. a 10% aqueous solution has a pH 3.5. The chemical structure is 2-(O-chlorophenyl)-2-(methylamino) cyclohexanone hydrochloride. It is a rapid acting, nonhypnotic, nonbarbiturate drug with a wide safety margin. The author used the anesthetic ketamine hydrochloride for oral surgery procedure in 16 patients(2 to 33 years). Anesthesia was achieved with a single intramuscular injection by introduction of manufacture. Result obtained as follows : 1. It was easily administered. 2. Onset time was rapid and duration was short. 3. The mild cardiac stimulation resulted in moderate increase in the blood pressure and pulse. 4. There was no significant respiratory depression. 5. The airway can be maintained without artificial support or endotracheal intubation. 6. All protective reflex maintained, which was important in oral surgery. 7. The best results were achieved in pediatric patients than adults.

• Laser Solutions
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• v.6 no.2
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• pp.35-41
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• 2003

In this study, manufacturing of polymer master and mold insert for micro injection molding was investigated. Ablation by excimer laser radiation could be used successfully to make 3-D microstructure of PET. The mechanism for ablative decomposition of PET with KrF excimer laser(λ: 248nm, pulse duration: 5ns) was explained by photochemical process. And this process showed PET to be adopted in polymer master for nickel mold insert. Nickel electroforming by using laser ablated PET master was preferable for replication method. Finally, it was shown that excimer laser ablation can substitute for X-ray lithography of LIGA process in microstructuring.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.51-57
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• 2001

In this paper, a novel overmodulation strategy for space-rector PWM(SYPWM) inverters to utilize dc link voltage fully is presented. The proposed strategy uses the concept of SVPWM based on the zero sequence signal(offset voltage) injection principle. So, by modifying the pole voltage simply, the linear control of inverter output voltage over the whole overmodulation range can be achieved easily. The proposed strategy is so simple that its practical implementation is easy. The validity of the proposed strategy is confirmed by the experimental results.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.148-150
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• 2006

In this paper, the applicability of an UET(ultrasound excited thermography) for a defect detection of the welded receptacle is described. An UET(ultrasound excited thermography) is a defect-selective and fast imaging tool for damage detection. A high power ultrasound-excited vibration energy with pulse durations of 280ms is injected into the outer surface of the welded receptacle made of Al material. An ultrasound vibration energy sent into the welded receptacle propagate inside the sample until they are converted into the heat in the vicinity of the defect. The injection of the ultrasound excited vibration energy results in heat generation so that the defect is turned into a local thermal wave transmitter. Its local heat emission is monitored by the thermal infrared camera. And they are processed by the image recording system. Measurement was performed on aluminum receptacle welded by using Nd:YAG laser. The observed thermal image revealed two area of defects along the welded seam.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.35-41
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• 2009

This paper proposes a stand alone type single-phase fuel cells micro-source with a voltage sag compensator for compensating the ac output voltage variations (sag or swell) of micro-source. The proposed micro-source is consist of a PEM(polymer electrolyte membrane) fuel cells simulator, a full bridge de converter, a 60Hz PWM(pulse width modulation) VSI(voltage source inverter), and a voltage sag compensator. Voltage sag compensator is similar to the configuration of hybrid series active power filter, and it is directly connected to micro-source through the injection transformer. Compensation algorithm of a voltage sag compensator adopts a single phase p-q theory. Effectiveness of the proposed the system is verified by the PSIM(power electronics simulation tool) simulation in the steady state and transient state which the proposed system is able to simultaneously compensate the harmonic current and source voltage sag or swell.