• Current Optics and Photonics
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• 제8권2호
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• pp.183-191
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• 2024

High-resolution retinal imaging based on adaptive optics (AO) is important for early diagnosis related to retinal diseases. However, in practical applications, closed-loop AO correction takes a relatively long time, and traditional open-loop correction methods have low accuracy in correction, leading to unsatisfactory imaging results. In this paper, a SH-U-net-based open-loop AO wavefront correction method is presented for a retinal AO imaging system. The SH-U-net builds a mathematical model of the entire AO system through data training, and the Root mean square (RMS) of the distorted wavefront is 0.08λ after correction in the simulation. Furthermore, it has been validated in experiments. The method improves the accuracy of wavefront correction and shortens the correction time.

• Journal of Power Electronics
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• 제16권5호
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• pp.1833-1842
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• 2016

In grid-connected converter control, grid voltage feedforward is usually introduced to suppress the influence of grid voltage distortion on the converter's grid-side AC current. However, owing to the time-delay in control systems, the suppression effect of the grid voltage distortion is seriously affected. In this paper, the positive effects of the grid voltage feedforward control are analyzed in detail, and the time-delay caused by the low-pass filter (LPF) in the voltage filtering circuits and digital control are summarized. In order to reduce the time-delay effect on the performance of the feedforward control, a voltage feedforward control strategy with time-delay compensation is proposed, in which, a leading correction of the feedforward voltage is used. The optimal leading step used in this strategy is derived from analyzing the phase-frequency characteristics of a LPF and the implementation of digital control. By using the optimal leading step, the delay in the feedforward path can be further counteracted so that the performance of the feedforward control in terms of suppressing the influence of grid voltage distortion on the converter output current can be improved. The validity of the proposed method is verified through simulation and experiment results.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.181-185
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• 2007

A free-surface correction(FSC) method is presented to solve the 3-D shallow water equations. Using the mode splitting process, FSC method can simulate shallow water flows under the hydrostatic assumption. For the hydrostatic pressure calculation, the momentum equations are firstly discretized using a semi-implicit scheme over the vertical direction leading to the tri-diagonal matrix systems. A semi-implicit scheme has been adopted to reduce the numerical instability caused by relatively small vertical length scale compare to horizontal one. and, as the free surface correction step the final horizontal velocity fields are corrected after the final surface elevations are obtained. Finally, the vertical final velocity fields can be calculated from the continuity equation. The numerical model is applied to the calculation of the simulation of flow fields in a rectangular open channel with the tidal influence. The comparisons with the analytical solutions show overall good agreements between the numerical results and analytical solutions.

• Current Optics and Photonics
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• 제3권2호
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• pp.154-163
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• 2019

In this study, we developed an optical sighting system capable of shooting at a long-distance target by operating a digital gyro mirror composed of a gyro sensor and an FSM. The optical sighting system consists of a reticle part, a digital gyro mirror (FSM), a parallax correction lens, a reticle-ray reflection mirror, and a partial reflection window. In order to obtain the optimal volume and to calculate the leading angle range according to the driving angle of the FSM, a calculation program using Euler rotation angles and a three-dimensional reflection matrix was developed. With this program we have confirmed that the horizontal leading angle of the developed optical sighting system can be implemented under about ${\pm}8^{\circ}$ for the maximum horizontal driving angle (${\beta}={\pm}12.5^{\circ}$) of the current FSM. Also, if the ${\beta}$ horizontal driving angle of the FSM is under about ${\pm}15.5^{\circ}$, it can be confirmed that the horizontal direction leading angle can be under ${\pm}10.0^{\circ}$. If diagonal leading angles are allowed, we confirmed that we can achieve a diagonal leading angle of ${\pm}10.0^{\circ}$ with a vertical driving angle ${\alpha}$ of ${\pm}7.1^{\circ}$ and horizontal driving angle ${\beta}$ of ${\pm}12.5^{\circ}$.

• ETRI Journal
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• 제41권1호
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• pp.73-83
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• 2019

This paper describes in detail the processing path leading to successful phase images stitching in digital holographic microscope for the extension of the field of view. It applies FIJI Grid/Collection Stitching Plugin, which is a general tool for images stitching, non-specific for phase images. The FIJI plugin is extensively supported by aberration and phase offset correction. Comparative analysis of different aberration correction methods and data processing strategies is presented, together with the critical analysis of their applicability. The proposed processing path provides good background for statistical phase analysis of cell cultures and digital phase pathology.

• 풍력에너지저널
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• 제14권3호
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• pp.25-33
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• 2023

In order to secure the safety of increasing offshore activities such as offshore wind farm maintenance and fishing, IMPACT, a mid-term marine weather forecasting system, was established by predicting marine weather up to 7 days in advance. Forecast data from the Korea Hydrographic and Oceanographic Agency (KHOA), which provides the most reliable marine meteorological service in Korea, was used, but wind speed and wave height forecast errors increased as the leading forecast period increased, so improvement of the accuracy of the model results was needed. The Model Output Statistics (MOS) method, a post-correction method using statistical machine learning, was applied to improve the prediction accuracy of wave height, which is an important factor in forecasting the risk of marine activities. Compared with the observed data, the wave height prediction results by the model before correction for 6 to 7 days ahead showed an RMSE of 0.692 m and R of 0.591, and there was a tendency to underestimate high waves. After correction with the MOS technique, RMSE was 0.554 m and R was 0.732, confirming that accuracy was significantly improved.

• 셀메드
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• 제13권7호
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• pp.25.1-25.4
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• 2023

Objective: A case report on the improvement of dyshidrotic eczema using cellular correction nutritional therapy (OCNT) Methods: A female patient in her 50s from Korea diagnosed with dyshidrotic eczema, experiencing symptoms such as vesicles, burning sensation, itching, and nail involvement, leading to significantly reduced quality of life Results: Improvement of dyshidrotic eczema observed after the implementation of nutritional therapy Conclusion: Nutritional therapy can be beneficial in alleviating symptoms in patients with dyshidrotic eczema.

• Archives of Plastic Surgery
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• 제36권2호
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• pp.167-173
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• 2009

Purpose: The key points of treatment of cryptotia are the elevation of invaginated ear helix and the correction of deformed cartilage. Prevention of stabilized cartilage contouring from returning to the previous state is also important. The authors carried otoplasty by modified Onizuka's method or Ohmori's method that conchal cartilage graft or high density polyethylene implant(MEDPOR$^{(R)}$) graft served as fixation after spreading posterior aspect of adhered antihelix and a splint for prevention of recurrence of cartilage deformities. The aim of this study is to reveal the availability of the high density polyethylene implant(MEDPOR$^{(R)}$) graft for the correction of cryptotia. Methods: We have repaired 17 cryptotic deformities using cartilage graft from cavum of concha(12 cases) or high density polyethylene implant(5 cases) for correction of deformed cartilage. We investigate the operative time, complications, and satisfaction of postoperative ear shape on both autogenous cartilage graft group and high density polyethylene implant graft group. Results: There was 1 case of reinvagination on autogenous cartilage graft group. Implant exposure was occurred on high density polyethylene implant graft group, as 1 case. These were statistically no differences between autogenous cartilage graft group and high density polyethylene implant graft group to the satisfaction of ear shape. Conclusion: High density polyethylene implant(MEDPOR$^{(R)}$) present an alternative to autogenous material as they allow of fibrovascular ingrowth, leading to stability of the implant and decreased infection rates. The correction of deformed cartilage by using the high density polyethylene implant(MEDPOR$^{(R)}$) is a good option for the treatment of cryptotia.

• Journal of Chest Surgery
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• 제18권2호
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• pp.258-264
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• 1985

The experience with operative treatment for total correction of Fallot at the department of Thoracic and Cardiovascular Surgery, Keimyung University Dong San Medical Center from July 1980 to July 1984 was reviewed. There were 37 males and 12 females and their ages ranged from 3 years to 30 years, with the average age of 12.2 years. Sixty nine point four percent of patients were younger than 15 years of age. The most frequent type of right ventricular outflow stenosis was the combined type [pulmonary valvular and infundibular stenosis] containing 41 patients [83.7%] and there were 9 deaths in this group. The major associated lesions included Patent foramen ovale in 20 patients [40.8%], Atrial septal defect in 7 patients [14.3%], Left superior vena cava in 4 patients [8.2%], Right sided aortic arch in 2 patients [4.1%] and Patent ductus arteriosus in 11 patient [2.0%]. The pulmonary valvotomy was performed in 41 patients and patch graft reconstruction of the right ventricular outflow tract was performed in 23 patients. In 11 patients the monocusp patches were used. Thirty-five patients [71.4%] had the right bundle branch block postoperatively. There were 11 postoperative deaths with hospital mortality rate of 22.4% and the leading causes of death were low output syndrome, bleeding, and cerebral embolism.

• Journal of Chest Surgery
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• 제23권2호
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• pp.253-259
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• 1990

Between January, 1970 and August, 1989, a total of 81 patients whose age were more than 20 years of life, received total correction for tetralogy of Fallot. This report analyzed 70 patients among them and excluded the remaining 11 patients whose clinical data could not be found. Their mean age was 25.750.39 years[range 20 \ulcorner50]. The clinical manifestations were cyanosis and clubbing [64 pts], frequent URI[40 pts], anoxic spell [19 pts], infective endo-carditis[4 pts], brain abscess[3 pts], pulmonary tuberculosis[3 pts] and CHF, chest tightness, nephrotic syndrome, left hemiplegia, and tamponade. The types of right ventricular outflow tract obstruction were combined[46 pts], pure infundibular [21 pts] and pure valvular[3 pts]. Associated cardiovascular anomalies were PFO [27 pts], ASDi8 pts], LSVC[8 pts], aortic regurgitation [5 pts], right aortic arch, coronary artery anomalies, PDA and dextrocardia. Hospital mortality was 5.7%. The causes of death ware low cardiac output [2 pts], aggravation of CRF[1 pts] and brain damage[1 pts]. There was one late death because of residual intracardiac shunt and congestive heart failure. During the follow-up period, 16 patients were lost and the remaining 49 patients were asymptomatic and leading normal lives. Residual intracardiac shunt was detected in 5 patients with radionuclide single pass study but all of them had Qp / Qs ratio less than 1.5.