• Journal of Dental Anesthesia and Pain Medicine
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• v.15 no.3
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• pp.153-156
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• 2015

A 47-year-old man was referred to the operating room to treat a dentigenous cyst of the mandibular bone. Initial assessment of the airway was considered normal. However, after the induction of anesthesia, we could not intubate the patient due to severe distortion of the glottis. Fiberoptic bronchoscopy and video laryngoscopy were not effective. Intubation using a retrograde wire technique was successful. After the conclusion of surgery, the patient recovered without any complications. Subsequent magnetic resonance imaging of the patient's neck showed a $6{\times}4{\times}8.6cm$ heterogeneous T2 hyperintense, T1 isointense well-enhancing mass in the prestyloid parapharyngeal space. The patient was scheduled for excision of the mass. We planned awake intubation with fiberoptic bronchoscopy. The procedure was successful and the patient recovered without complications. Anesthetic induction can decrease the muscle tone of the airway and increase airway distortion. Therefore, careful airway assessment is necessary.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.600-604
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• 1991

In this paper, an advanced PWM modulation strategy for driving a variable-speed induction motor is introduced. According to this method, the technique of efficiently eliminating harmonics component is achived. A switching pattern was computed making use of the near-proportionality of voltage and frequency in AC machines operating with constant flux. At low magnitudes and low frequencies of the foundamental, many more harmonics are eliminated than at high magnitudes and frequencies. In order to keep the inverter switching frequency constant over the output frequency range, chopping times diminishes as the frequency of the fundamental increases.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1097-1098
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• 2011

This paper proposes high performance control of induction motor drive using fuzzy neural network precompensation PI(FNPPI) controller. To apply industrial processes, control methods is requested technique that can be demonstrate high performance and robust about load disturbance, parameter variation and uncertainty of model, etc. The PI controller dose not show satisfactory performance due to fixed gain. Therefore, this paper proposes FNPPI which is adjusted input values of PI controller according to operating conditions of motor by FNN controller mixed neural network and fuzzy. And this paper proves validity of proposed control algorithm through result analysis.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.162-164
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• 1994

This paper presents the optimal design method of an induction motor for electric vehicle which minimizes the weight of motor and satisfies maximum power rating at the same time. Effects of motor parameters on the dimensions and weight of motor is investigated. Optimal routine which is used in this paper is simulated annealing technique.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.203-206
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• 2000

This paper presents a torque ripple reduction technique of direct torque control(DTC) for high power induction motors driven by 3-level inverters with the inverter switching frequency limited around 0.5-1kHz level. It is noted that conventional DTC algorithms to reduce torque ripple are devised for applications with relatively high switching frequency above 2-3kHz. A new DTC algorithms especially for low switching frequency inverter system illustrates relatively reduced torque ripple are devised for applications with relatively high switching frequency above 2-3kHz. Anew DTC algorithm especially for low switching frequency inverter system illustrates relatively reduced torque ripple characteristics Simulation and experimental results show the effectiveness of the proposed control algorithm

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.296-297
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• 2011

Many applications involving induction motors that are controlled using variable frequency drives require the ability to stop quickly. These applications include emergency stops, quick stopping of fans, centrifuges, presses, etc. The technique that is widely accepted in the industry for achieving quick stopping makes use of brake resistors in series with a power semiconductor switch. The switch-resistor combination (brake-unit) is applied across the dc bus. The fastest decelerating time achievable depends on the size of the resistors and the switch employed. In this paper, the authors propose a novel method of achieving quick stopping times without the use of any brake-unit. Experimental test results with and without this method on a large inertia motor-load combination show that the proposed stopping method is able to reduce the stopping time significantly compared to normal decelerated stop without the need for a braking unit.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1725_1726
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• 2009

The purpose for this paper is to obtain the ��$H_{\infty}$ LMI with fuzzy PI controller for induction motor which is nonlinear system. The controller type is PI and the control gains are obtained based on $H_{\infty}$ control problem. The PI controller is considered a part of a plant and the problem is changed to get controller with static gains. The nonlinear system is approximated as several linear systems and combined by using fuzzy technique.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.643-649
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• 2012

The diagnosis technique of stator winding faults based on Motor Current Signature Analysis(MCSA) was suggested. Park's vector pattern, the circle that is drawn by d-q transformed currents($i_d$, $i_q$), is widely used for stator winding faults detection. The current Distortion Ratio(DR), defined by the ratio of max axis and min axis of ellipse of Park's vector's pattern, was more simple and powerful method than the Park's vector pattern. In this study, a calculation method of distortion ratio of Park's vector pattern was suggested for auto diagnosis of stator winding short fault and usefulness of suggested calculation method of distortion ratio was verified through simulation using LabVIEW program.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.2
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• pp.116-125
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• 2003

The new HVAC system to lower the conveyance energy and building height using IAV (Increasing Air Volume) technique is developed. IAV units which are equipped in each zone carry out air-conditioning and supply fresh air by induction of outdoor air in main duct. The design program which decides size of OAHU and IAV unit according to air conditioning load and fresh air demand of each zone is presented. The control system is developed to operate efficiently HVAC system and IAV unit, so that individual zone operation and well-deal with partial load and IAQ problem are possible. The new system is investigated in model building and makes more profit in conveyance energy, size of air conditioning facilities room and building height than VAV system. But in construction cost it is worse by about 15 per-centage.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.821-824
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• 2005

This paper presents a technique to evaluate torque and speed characteristics of induction motor with the Dynamometer. The simple Dynamometer controlled via microcontroller and displayed by computer. The Microcontroller generates the PWM (Pulse Width Modulation) signal and control the duty cycle of signal for control braking level. The Buck converter is a braking unit which uses IGBT as switch in circuit. The output current of the Buck converter and output voltage of tacho generator are converted to digital signals and analyzed by microcontroller. The signals are then sent to computer for displaying torque and speed responds independent on the braking time. The test results of the Dynamometer in this research can coreectly predict the torque and speed response under reasonable tests. Moreover, this Dynamometer is easy and inexpensive to make.