• Korean Journal of Bronchoesophagology
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• v.4 no.2
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• pp.219-224
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• 1998

Bilateral vocal cord paralysis can result in severe airway compromise. Over the years a variety of arytenoidectomy procedures have bee described, and one or more of these have been the gold standard for many years. A widely accepted treatment is endoscopic laser total arytenoidectomy. However, vocal results are usually poor. Objective : To evaluate the effect of treatment of endoscopic laser medial partial arytenoidectorny for bilateral vocal cord paralysis Material and Methods : We performed endoscopic medial partial arytenoidceomy with $CO_2$laser for 3 patients with bilateral vocal cord paralysis. The $CO_2$laser is operated with a continuous 7-watt beam in superpulse mode. We compared degree of dyspnea and glottic area of pre-operation with those of post-operation for 3 patients. We analysed aerodynamic study pre-operatively and post-operatively for 1 patient. Results The symptom of dyspnea was improved markedly and the glottic area was widened from 34% to 50% compared with that of pre-operation. The voice quality was slightly decreased. Tracheotomy was not necessary for not-tracheotomized patient and decanulation was possible for tracheotomized patient post-operatively. Cunclusion： The endoscopic laser medial partial arytenoidectomy is a convient and effective method for opening the posterior glottic airway.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.753-759
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• 2016

Power automation system to operate power distribution systems can be distinguished by distribution SCADA with remote monitoring and control; and distribution automation system with basic functions such as service restoration to the distribution SCADA; and distribution management system which is operated by various applications in order to enhance distribution system operation performance based on the distribution automation system. In the technological change, a technical boundary of information technology (IT) and operation technology (OT) is being blurred by that new concepts such as interoperability. In addtion, IT/OT convergence has been proposed by the improvement of ICT and power system technology. At the viewpoint, advanced distribution management system (ADMS) to have the new concepts and to increase distribution system operation efficiency through global information and functions from the other systems has been proposed. In order to implement the ADMS, IT and OT have to be employed together on the ADMS; and the concept-based IT/OT convergence concept has been presented. Therefore, this paper introduces ADMS and IT/OT convergence and proposes a design of IT/OT convergence based ADMS system design with configurations and functions.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.53-58
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• 2021

Operation of the interleaved Boost PFC converter in Critical Conduction Mode (CrM) shows the advantages of high efficiency and good EMI characteristics owing to the valley switching of FET. However, when it is designed for a highly pulsating load, operation at a relatively high frequency is inevitable at non-pulsating typical load condition, resulting in efficiency degradation. Moreover, the physical size of the inductor becomes problematic because of the nature of the CrM operation, where the inductor peak current is about two times the inductor average current, thereby requiring high DC-bias characteristics, which is worse when the output power is high. In this study, a new parallel driving method of two sets of interleaved boost PFC converters for highly pulsating high-power application is proposed. The proposed method does not require any additional load-sharing controller, resulting in high efficiency and smaller inductor size.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.445-452
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• 2015

A tubular packed bed reactor for the steam-$CO_2$ combined reforming of natural gas to produce the synthesis gas of a target $H_2/CO$ ratio 2.0 was simulated. The effects of the reactor dimension, the feed gas composition, and the gas feeding temperature upon the possibility of coke formation across the catalyst bed were investigated. For this purpose, 2-dimensional heterogeneous reactor model was used to determine the local gas concentrations and temperatures over the catalyst bed. The thermodynamic potential distribution of coke formation was determined by comparing the extent of reaction with the equilibrium constant given by the reaction, $CH_4+2CO{\Leftrightarrow}3C+2H_2O$. The simulation showed that catalysts packed in the central region nearer the entrance of the reactor were more prone to coking because of the regional characteristics of lower temperature, lower concentration of $H_2O$, and higher concentration of CO. With the higher feeding temperature, the feed gas composition of the increased $H_2O$ and correspondingly decreased $CO_2$, or the decrease in the reactor diameter, the volume fraction of the catalyst bed subsequent to coking could be diminished. Throughout the simulation, reactor dimension and reaction condition for coking-free operation were suggested.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.67-72
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• 2015

The purpose of this study is to achieve energy saving effect of inverter driving multistage centrifugal pump. For determining the operation points in the pump system, the system curves should be obtained experimentally. To get the system curves, three pumps combined in parallel and one pump operated with different rotational speeds. But for variable speed pump system, energy saving rates can not be evaluated from operation efficiencies. That is why operation efficiencies, system curves, duty cycles, and input powers of the pump system were measured by the constructed experimental apparatus. The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time. The system was operated with two different periods. The mean duty cycles were collected from apartment and found that the system operated at 40% and at 50% or below capacity. Measured energy saving rate was 58.16%. Estimating method of energy saving rate could be more effective operation index than that of operation efficiency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.3
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• pp.264-268
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• 2005

A 2.2-inch QCIF+(176${\times}$RGB${\times}$220) TFT-LCD with integrated row driver was developed using a standard amorphous silicon TFT technology. At low temperature, the integrated row driver operation is dramatically effected by the electron drift mobility reduction(■50 %) and the threshold voltage shift (■1V) of the a-Si TFT. We studied the dependency of circuit design and found that higher on-current circuit is important to guarantee good operation in wide temperature range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.559-562
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• 2004

A 2.2-inch QCIF+ $(176{\times}RGB{\times}220)$ TFT-LCD with integrated row driver was developed using a standard amorphous silicon TFT technology. At low temperature $({\sim}-20^{\circ}C)$, the integrated row driver operation is dramatically effected by the electron drift mobility variation $({\sim}50%)$ and the threshold voltage shift $({\sim}1V)$ of the a-Si TFT. We studied the temperature dependency of the circuit design and found that higher on-current circuit is important to guarantee good operation in wide temperature range.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.47-48
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• 2012

In this study, the CO₂ emission and economic efficiency of high-rise apartment houses were evaluated, and were analyzed as a way to establish database on the evaluation of environment-friendliness of high-rise buildings. To that end, standard of buildings to be evaluated were proposed through analysis of the designing guideline for high-rise apartment houses proposed by Seoul city, and CO₂ emission of the subject buildings were evaluated based on the characteristics of materials admitted into each building and the amounts of energy consumed during lifecycle period. In addition, the initial costs in construction stage and annual costs in operation stage were set as analysis parameters, and along with calculation of direct cost by the consumption of construction materials and energy, the costs of CO₂ emission were evaluated and analyzed. As a result, the CO₂ emission and economic efficiencies of high-rise apartment houses by construction stage and operation stage could be analyzed quantitatively.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.102-107
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• 2014

SCR(Thyristor) type $CO_2$ welders have widely used for the welding process of heavy industries such as shipbuilding and plant. Since the industrial fields of shipbuilding and plant are usually exposed to severe welding condition with lots of dust, extreme temperature, high humidity and vibration, it is not recommended to use inverter type welder despite its state-of-the-art technology. Many sophisticated functions in the inverter welder may not work due to malfunction of its sensitive components. Hence this study focused on digitalization of SCR $CO_2$ welder by making use of microprocessor for SCR phase control. By this application, fine control of output of the $CO_2$ welding systems is achieved. Also pulse output mode of operation is realized and its verification is carried out with aluminum sample welding. The experimental results showed sound weld bead. The front operation panel provide user with numerical parameter settings and monitors. It will help precise weld process monitoring and control with digital value.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.118-119
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• 2017

This paper proposes the operation mode and control method of the PV ESS for building lighting. The PV ESS is consisted of 3.3kW single phase grid connected PV inverter, Bi-direction DC/DC converter for Charging/Discharging for battery and DC48V Buck DC/DC converter for LED lighting.