• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.231-238
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• 2023

For boost PFC (Power Factor Correction) converters, various control methods are being studied to achieve unity power factor and low THD (Total Harmonic Distortion) of AC input current. Among them, average current mode control, which controls the average value of the inductor current to follow the current reference, is the most widely used. However, nowadays, as advanced digital control becomes possible with the development of digital processors, predictive control of boost PFC converters is receiving attention. Predictive control is classified into predictive current mode control, which generates duty in advance using a predictive algorithm, and model predictive current control, which performs switching operations by selecting a cost function based on a model. Therefore, this paper simply explains the average current mode control, predictive current mode control, and model predictive current control of the boost PFC converter. In addition, current control under entire load and disturbance conditions is compared and analyzed through simulation.

• Journal of the Korea Society of Computer and Information
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• v.29 no.6
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• pp.143-151
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• 2024

In this paper, the inductor current distortion in a boost PFC (Power Factor Correction) converter under light load is mathematically analyzed, and its reasons are defined. In the average current mode control under light load, the inductor current is discontinuous, resulting in an inaccurate inductor current average value being reflected in the current control. In predictive current mode control, the current ripple is relatively large compared to the inductor current, leading to severe current distortion. In addition, the switch is turned off near the peak of the inductor current when model predictive current control is applied. Inductor current distortion must be addressed because it leads to an increase in total harmonic distortion and a decrease in power factor. In this paper, the design procedure to mitigate the light load current distortion in boost PFC converter is selected based on the mathematical analysis. Finally, a comparative analysis of control methods under light load is performed using hardware-in-the-loop simulation.

• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.265-270
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• 2016

Extreme tropospheric anomalies such as typhoons or regional torrential rain can degrade positioning accuracy of the GPS signal. It becomes one of the main error terms affecting high-precision positioning solutions in network RTK. This paper proposed a detection algorithm to be used during atmospheric anomalies in order to detect the tropospheric irregularities that can degrade the quality of correction data due to network errors caused by inhomogeneous atmospheric conditions between multi-reference stations. It uses an atmospheric grid that consists of four meteorological stations and estimates the troposphere zenith total delay difference at a low performance point in an atmospheric grid. AWS (automatic weather station) meteorological data can be applied to the proposed tropospheric anomaly detection algorithm when there are different atmospheric conditions between the stations. The concept of probability density distribution of the delta troposphere slant delay was proposed for the threshold determination.

• Journal of Chest Surgery
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• v.17 no.2
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• pp.189-196
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• 1984

Although the conventional methods of cardiopulmonary bypass for open heart surgery have been employed, it has been usual method to repair of congenital heart disease in infancy using deep hypother-mia and circulatory arrest technique. In 1980, we reported total correction of congenital heart disease using surface induced hypothermia-total circulatory arrest and rewarming with limited cardiopulmonary bypass. in 1981, three patients below 10 kilogram, who had ASD and PDA, and two of VSD with pulmonary hypertension were operated on using simple deep hypothermia without cardiopulmonary bypass. During surface cooling, there were no ventricular fibrillation and arrhythmia. There were no difficulties to resuscitate the heart. Postoperative respiratory and neurologic complication were not occurred. Follow up examination for two to three years gave no evidence of cerebral damage due to circulatory arrest.

• Journal of Chest Surgery
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• v.18 no.2
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• pp.360-370
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• 1985

A case of complete interruption of aortic arch with aortopulmonary window, patent ductus arteriosus, and aberrantly originated right subclavian artery from proximal descending aorta, in a four year old boy is reported in detail. This is the only reported case in Korea, who has had a successful one-stage total anatomical correction of this combination of defects. Under deep hypothermia and total circulatory arrest, aortic continuity was established using patent ductus arteriosus and anterior wall of pulmonary artery, which was anastomosed obliquely to anteromedial side of ascending aorta. Aortopulmonary window was closed using Impra patch via pulmonary arteriotomy. Then pulmonary arteriotomy was reconstructed primarily except at the junction of right pulmonary artery and main pulmonary artery, where a small piece of pericardium was used to close the defect to prevent kinking and narrowing of right pulmonary artery. Postoperative cardiac catheterization demonstrated a good reconstruction.

• Journal of Chest Surgery
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• v.24 no.2
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• pp.206-211
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• 1991

Interruption of the aortic arch may be defined as discontinuity of the aortic arch in which either an aortic vessel or a patent ductus arteriosus supplies the descending aorta. This anomaly is a rare congenital malformation that usually occurs with severe associated intracardiac congenital anomalies, such as ventricular septal defect, patent foramen ovale and abnormal arrangement of the brachiocephalic arteries. Rarely, transposition of the great vessel, truncus arteriosus are coexistent. We experienced a case of the interrupted aortic arch [Type A] associated with VSD, PDA and patent foramen ovale in a 16 years old female. One stage total correction was done under profound hypothermia with total circulatory arrest. Aortic continuity was established using patent ductus arteriosus with anterior wall of main pulmonary artery, which was anastomosed obliquely to anteromedial side of the ascending aorta. Ventricular septal defect was closed using Dacron patch and patent foramen ovale was closed directly. Postoperative course was uneventful, except mild hoarseness.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.636-643
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• 1984

For the purpose of avoiding postoperative massive pulmonary insufficiency after transannular outflow tract reconstruction in patients with tetralogy of Fallot, we have used monocusp bearing outflow patch since June 1983. Right heart catheterization and pulmonary arteriography were performed in 7 patients among the total 11 patients corrected with monocusp bearing outflow patch during postoperative 14th day to 22nd day. Particular attention was paid to the evaluation of the pulmonary valve competence, and the results were; 1.One patient died of acute renal failure secondary to low cardiac output and the operative mortality was 9.1%. 2.The average PRV/FA ratio was 0.491 and the average systolic pressure gradient between right ventricle and pulmonary artery was 17.7mmHg. The average Qp/Qs was 1.13. 3.Inspite of using monocusp bearing outflow patch, the hemodynamic and pulmonary arteriographic results were unsatisfactory in respect to pulmonary valve competence.

• Journal of Chest Surgery
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• v.20 no.4
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• pp.773-779
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• 1987

MOVC is an uncommon disease which can be corrected by surgical method if early detected. A case of a 34-year-old male with MOVC is reported. Operation was done on cardiopulmonary bypass with circulatory arrest under moderate hypothermia. The incision was done both on the RA extending to level of suprahepatic IVC and on the IVC just proximal to the right renal vein. And then, thrombectomy and membranectomy under the direct visualization was done. Total circulatory arrest was used intermittently in order to get good visual field and for preventing blood loss. The Postop. course was good except one episode of hepatic encephalopathy which was persisted for 12 hours and then controlled by conservative measures.

• Journal of Chest Surgery
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• v.21 no.3
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• pp.588-593
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• 1988

We experienced a case of interrupted aortic arch[Type A] associated with PDA, VSD, mitral regurgitation and single coronary artery. The patient was 7 years old boy, who showed congestive heart failure[NYHA functional class III]. One stage total correction was performed under profound hypothermia with total circulatory arrest. Aortic continuity was established using PDA with anterior wall of main pulmonary artery flap. VSD was closed with Dacron patch and mitral regurgitation repaired by Reed`s annuloplasty method. The postoperative cardiac catheterization revealed no pressure gradient between ascending aorta and descending aorta, decreased pulmonary artery pressure and trivial residual shunt[Qp/Qs: 1.28]. The aortogram showed good continuity of the aorta without narrowing of the anastomotic site. During the period of 1 year follow up, heart failure symptoms were nearly subsided.

• Journal of Korean Foot and Ankle Society
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• v.15 no.3
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• pp.132-138
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• 2011

Although first generation total ankle replacement (TAR) had high failure rates, recent investigations have reported good results of the newer generations of TAR due to advances in implant designs and techniques. Patient selection is critical to performing TAR to obtain promising outcomes and to decrease complication rate. As the current concepts of correcting the accompanying deformity have been established, TAR in moderate to severe varus deformity of the ankle result in favorable outcomes and indications for TAR are expanding. Correction of deformity and hindfoot fusion should be performed in conjunction with TAR if needed. If radiolucency around components or osteolysis is progressive during follow-up, CT should be carried out as a confirmative diagnostic method. TAR is an effective treatment modality alternative to ankle fusion. However, we should recognize that TAR is a demanding procedure, which requires accurate techniques, enough experience, and preoperative plan for a concomitant deformity.