• Journal of Chest Surgery
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• v.21 no.6
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• pp.996-1002
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• 1988

A clinical analysis was performed on 115 cases of -patent ductus arteriosus treated surgically during the period of 11 years from Aug. 1977 to Jul. 1988. at the Department of Thoracic and Cardiovascular Surgery, Chungnam National University Hospital. Among 115 cases, male was 38 and female was 77 and ages ranged 12 days to 27 years old with the average of 8 7/12 years. The major clinical symptoms on admission were frequent URI attack[77.4%], dyspnea on exertion[32.2%] and palpitation[13%]. On auscultation, continuous machinery murmurs were detected in 97 cases[84.3%] and loud systolic murmurs were detected in 18 cases[15.7%]. Preoperative electrocardiographic findings were as follows: LVH 59[51.3%], RVH 12[10.4%], BVH 16[13.9%] and WNL 28[24.3%]. Radiologically, there were increased pulmonary vascularity in 104[90.4%] and cardiomegaly 62[53.9%]. Cardiac catheterization were performed in 101 cases and mean systolic pulmonary arterial pressure was 49.84*29.7mmHg and mean Qp/Qs was 2.95k1.8. Methods of operation were multiple ligation in 96, division in 11 and transpulmonary arterial repair using cardiopulmonary bypass in 8. Complication were recannalization in 2, temporary hoarseness due to left recurrent laryngeal nerve paralysis in 3 and respiratory distress in 1 and overall mortality rate was 1.7%[2 cases].

• Journal of Chest Surgery
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• v.23 no.2
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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.

• Journal of Chest Surgery
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• v.20 no.3
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• pp.528-535
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• 1987

A clinical study was performed on 164 cases of PDA experienced at the Dept. of Thoracic and Cardiovascular Surgery of Pusan National University Hospital during 6 years from Jan. 1981 to Dec. 1986. It was shown that the PDA was a female-dominant heart disease [male to female ratio, 1:2.8] and two most common symptoms were frequent URI [45.6%] and exertional dyspnea [36.7%]. Continuous machinery murmurs were detected in 143 cases [87.2%], increased pulmonary vascularities [89.0%] and cardiomegalies [63.4%] by chest X-ray. The signs of LVH [43.9%], RVH [3.7%] and BVH [4.9%] were noted on the EKG. Cardiac catheterizations were performed on 67 out of 164 patients and the mean systolic pulmonary artery pressure was 48mmHg [range: 18-131mmHg] and the mean Qp/Qs was 3.1 [range:1.2-8.5] and Rp/Rs below 0.25 was 83.6%. Associated cardiac anomalies were VSD [7.9%], ASD [3.0%], pulmonary valvular stenosis [2.4%] and left persistent SVC [2.4%]. Operative methods were as follows; ligations [145; 88.4%] and divisions [6;3.7%] were performed through the left posterolateral thoracotomies without mortality and the remained cases [13;8.0%] were managed under the cardiopulmonary bypass because of the associated cardiac anomalies. Atelectasis [4.9%] and pneumonia [4.3%] were most frequent postoperative complications and the overall mortality rate was 2.4% [4 out of 164 cases].

• Journal of Chest Surgery
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• v.19 no.4
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• pp.627-632
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• 1986

This report describes our 17-years experience with intracardiac repair in 123 patients older than 15 years with tetralogy of Fallot. Major clinical manifestation was cyanosis and clubbing [102 Pts], but other minor associated manifestation were infective endocarditis, pulmonary tuberculosis, brain abscess, congestive heart failure, nephrotic syndrome, and tuberculous spondylitis. Prior palliative shunts had been performed in 10 patients. Preoperative hemoglobin ranged from 9.7 gm/dl to 25 gm/dl [mean 19 gm/dl]. The type of ventricular septal defect were typical perimembranous type, and total canal defect [13%]. The right ventricular outflow tract obstruction was due to combined [58.5%], infundibular [35%], and valvular stenosis [6.5%]. Transannular patch was used in 17% of patients. Hospital mortality was 9.8% in overall, but decreased to 1.7% since 1982. There was two late death [12 year actuarial survival [97%] due to fulminant hepatitis, residual abnormalities [PS, VSD]. Ninety two percent of survivors at follow-up are asymptomatic and leading an active normal life. Residual ventricular septal defect was detected with radionuclide single pass study in 15.3% of patients but almost cases were Qp/Qs less than 1.5, and only two patients had been candidates for reoperation.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.127.1-127.1
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• 2012

The 40.8-MHz VHF coherent scatter ionospheric radar, located in South Korea (Gyeryong, $36.18^{\circ}N$, $127.14^{\circ}E$), has been operating since December 2009 to investigate ionosphere E- and F-region field-aligned irregularities (FAIs) of mid-latitude. During the observation, we found E- and F-region FAIs appeared frequently: continuous echoes during the post-sunrise period and Quasi-Periodic (QP) echoes at nighttime for E region ; strong post-sunset and pre-sunrise FAIs for F region. The characteristics of E- and F-region FAIs are presented in terms of seasonal and local time variations of occurrence during December 2009 to August 2012. In addition, to investigate the correlation with geomagnetic activity to FAIs occurrence, we compared K-index variations to local time occurrence. It is worth to note our occurrence result since long term observation over several years in the mid-latitude has not yet been carried out.

• Journal of Chest Surgery
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• v.19 no.1
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• pp.25-34
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• 1986

Recently, radionuclide angiocardiogram is one of the most common procedure for assessment of ventricular performance due to its distinctive advantages such as safety, accuracy, and ease of repeated studies. Also, measurement and comparison between pre and postoperative left ventricular ejection fraction [LVEF] are meaningful for assessing the severity of myocardial damage which occurred during open heart surgery and the status of myocardial recovery. We obtained pre and post operative LVEF using radionuclide angiocardiogram on 30 patients composed of atrial septal defect, ventricular septal defect, cyanotic congenital heart disease, and valvular heart disease who undergone the open heart surgery from March to august 1984. The study revealed that ventricular septal defect and mitral valvular heart disease showed 8.1% and 6.2% decreases of postoperative LVEF, respectively. But, there are little increases of postoperative LVEF in the atrial septal defect and cyanotic congenital heart disease. In ventricular septal defect, each group of Qp/Qs over 2.0 and systolic pulmonary artery pressure over 50mmHg showed significant 17% and 14.7% decreases of postoperative LVEF, respectively. Considering the duration of the aortic cross clamping times and closing methods of VSD, each group of duration over 30 min. and of patch closure showed 13.9% and 14.2% decreases of LVEF between pre and postoperative status respectively which was significant finding statistically.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1523-1528
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• 2014

Silicon quantum dots (Si QDs) were synthesized by etching silicon nanopowder with aqueous hydrofluoric acid (HF) and nitric acid ($HNO_3$). Then, the hydride-terminated Si QDs (H-Si QDs) were functionalized by 1- octadecene (ODE). By only controlling the etching time, the maximum luminescence peak of octadecylterminated Si QDs (ODE-Si QDs) was tuned from 404 nm to 507 nm. The average optical gap was increased from 2.60 eV (ODE-Si QDs-5 min) for 5 min of etching to 3.20 eV (ODE-Si QDs-15 min) for 15 min of etching, and to 3.40 eV (ODE-Si QDs-30 min) for 30 min of etching. The electron affinities (EA), ionization potentials (IP), and quasi-particle gap (${\varepsilon}^{qp}_{gap}$) of the Si QDs were determined by cyclic voltammetry (CV). The quasi-particle gaps obtained from the CV were in good agreement with the average optical gap values from UV-vis absorption. In the case of the ODE-Si QDs-30 min sample, the difference between the quasi-particle gap and the average optical gap gives the electron-hole Coulombic interaction energy. The additional electronic levels of the ODE-Si QDs-30 min and ODE-Si QDs-15 min samples determined by the CV results are interpreted to have originated from the Si=O bond terminating Si QD.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.155-158
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• 2000

In this paper, the quantization noise in block-based video coding is analyzed, and a post-processing method based on the analysis is presented for reducing the quantization noise by using a wavelet transform(WT). In the proposed method, the quantization noise is considered as the sum of a blocking noise expressed as a deterministic profile and the random remainder noise. Each noise is removed in a viewpoint of image restoration using a 1-D WT, which yields a regularized differentiation. The blocking noise first is reduced by weakening the strength of each blocking noise component that appears as an impulse in the first scale wavelet domain. The impulse strength estimation is performed using median filter, quantization parameter(QP), and local activity. The remainder noise, which is considered as a white noise at non-edge pixels, then is reduced by soft-thresholding. The experimental results show that the proposed method yields better performance in terms if subjective quality as well as PSNR performance over VM post-filter in MPEG-4 for all test sequences of various compression ratios. We also present a fast post-processing in spatial domain equivalent to that in wavelet domain for real-time application.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.458-465
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• 2018

This study reports the fabrication of anion exchange membranes (AEMs) containing two kinds of functional groups: i) trimethylphosphite (TMP) and ii) trimethylamine (TMA). We carried out the synthesis of polymers to enhance thermal stability and ion conductivity. The alternative polymer was prepared using 2,2-bis(4-hydroxy-3-methylphenyl)propane and decafluorobiphenyl. The membrane was fabricated by solution casting method. The thermal stability of membranes was examined by TGA. The physiochemical properties of membranes were also investigated in terms of water uptake, swelling ratio, ion exchange capacity, and ion conductivity. The hydroxide ion conductivity of the membranes reached about 20.2 mS/cm for quaternary ammonium poly(arylene ether) (QA-PAE) containing TMA moiety and 5.1 mS/cm for quaternary phosphonium PAE (QP-PAE) containing TMP moiety at $90^{\circ}C$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.63-71
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• 2009

In this paper, a new low-complexity distortion estimation method for H.264 rate-distortion optimized mode decision is proposed. The coding processes, such as DCT, quantization, inverse quantization, inverse DCT, and reconstruction are needed to compute the distortion in an H.264 encoder. To reduce these processes, we estimate distortion using integer operations with coefficients obtained in the quantization process. Inverse quantization, inverse DCT, and reconstruction processes are not needed by the proposed method. For quantization parameters 24 to 36, experimental results show that the time saving of rate-distortion optimized mode decision is on average 29 % and as high as 42 % with negligible degradation in coding performance.