• Journal of KIISE:Computer Systems and Theory
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• v.30 no.10
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• pp.523-532
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• 2003

Video on Demand(VOD) services cause high resource consumption in a video seuer, because multimedia are characterized by continuous playback, a high bandwidth requirement, and long playback duration. Patching has been proposed to save the network I/O bandwidth of a video server. To achieve true VOD, patching uses multicasting to share video streams, thereby providing immediate VOD services to users without any service latency. A communication channel is used to either multicast the entire video as a regular channel or multicast only the leading portion of a video as a Patching channel. This paper Proposes a buffering patching technique that divides regular channels, as used in patching, into sub-regular channels and regular channels to shorten the holding time of the channels. In the proposed technique, the last portion of video data, corresponding to the size of the buffering window, is not transferred by sub-regular channels, but rather downloaded and buffered in the user buffer from the latest regular channel. When simulations were performed to compare the performance of the proposed technique with that of conventional patching, the results indicated that the proposed technique was superior in terms of the defection rate, average service latency, and fairness, although the amount of video data buffered at each user station was higher than that with patching.

• Clinics in Shoulder and Elbow
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• v.17 no.2
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• pp.68-76
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• 2014

Background: Recently, reverse total shoulder arthroplasty (RTSA) has been accepted as a main treatment option in irreparable massive rotator cuff tear with cuff arthropathy. The purpose of this study was to evaluate the early complication incidence and the preliminary clinical results of RTSAs performed in single institute. Methods: Fifty-seven RTSAs (56 patients) were performed between April 2011 and March 2013. The indications for RTSA were cuff tear arthropathy and irreparable massive rotator cuff tear with or without pseudoparalysis. Exclusion criteria were revision, preoperative infections and fractures. At final follow-up, 45 shoulders were enrolled. Mean follow-up duration was 12.5 months (range, 6-27 months). The mean age at the time of surgery was 73.6 years (range, 58-87 years). All the patients were functionally accessed via Constant score, American Shoulder and Elbow Surgeons (ASES) score, pain and functional visual analogue scale (VAS) scores and active range of motion. Complications were documented as major and minor. Major complications include fractures, infections, dislocations, nerve palsies, aseptic loosening of humeral or glenoid components, or glenoid screw problems. Minor complications include radiographic scapular notching, hematomas, heterotopic ossification, algodystrophy, intraoperative dislocations, intraoperative cement extravasation, or radiographic lucent lines of the glenoid. Results: The mean Constant score increased from 31.4 to 53.8 (p < 0.001). The pain and functional VAS scores improved (5.2 to 2.7, p < 0.001, 4.0 to 6.7, p < 0.001) and active forward flexion improved from $96.9^{\circ}$ to $125.6^{\circ}$ (p = 0.011). One or more complications occurred in 16 (35.6%) of 45 shoulders, with one failure (2.2%) resulting in the removal of implants by late infection. The single most common complication was scapular notching (9 [20%]). There were 4 (8.9%) axillary nerve palsies postoperatively (n=3: transient n. palsy, n=1: Symptom existed at 11 months postoperatively but improving). Conclusions: In a sort term follow-up, RTSA provided substantial gain in overall function. Most common early complications were scapular notching and postoperative neuropathy. Although overall early complication rate was as high as reported by several authors, most of the complications can be observable without compromise to patients' clinical outcome. Long term follow-up is required to clarify the clinical result and overall complication rate.

• Journal of Chest Surgery
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• v.18 no.4
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• pp.679-691
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• 1985

Ninety patients underwent mitral valvular heart surgery associated with or without aortic valve surgery and subjected to a clinical study in relation to their control of postoperative atrial fibrillation. There were 26 males and 64 females ranged in age from 16 to 56 years with a mean of 35.2 years. Systemic arterial embolizations were observed in 11 patients [12.2%]. Four patients of them were in normal sinus rhythm and 7 in atrial fibrillation. Out of these, left atrial thrombi were found only in 2 at the operation. Intraoperatively confirmed left atrial thrombi were in 16 patients [17.7%] of all 90 patients: Eleven patients occurred at the age of more than 40 years, 14 were in atrial fibrillation and 2 only had previous episodes of systemic arterial embolization. Sixty three patients underwent isolated mitral valve surgery [OMC 28, MVR 35] and 27 patients associated with aortic valve surgery along with mitral valve [OMC+AVR 13, MVR+AVR 14]. Preoperatively, 44 patients [48.9%] were in normal sinus rhythm. Of them, 35 patients [79.5%] revealed normal sinus rhythm thoroughly after operation without any aid of digitalis or quinidine and 5 patients [11.4%] restored normal sinus rhythm with digitalization alone. Other 3 patients converted to normal sinus rhythm with the addition of quinidine, however, in 1 patient who was resistant to quinidine therapy, electrocardioversion was carried out on the postoperative third week showing normal sinus rhythm. Thus, the most atrial fibrillations that occurred for the first time in the postoperative period, were able to reverted to normal sinus rhythm responding well to antiarrhythmic therapy. Preoperatively, 46 patients [51.1%] were in atrial fibrillation. Of them, only 5 patients returned to sinus rhythm after operation without any aid of digitalis or quinidine and other 5 restored normal sinus rhythm with digitalization: namely 2 restored within early postoperative period and 3 after more than 3 months. Eight patients well responded to quinidine therapy showing normal Sinus rhythm. So far, 25 patients have remained in persistent atrial fibrillation on 6 to 36 months follow-up. In view of these, 17 patients [68%] were over 40 years of age, 22[80%] had long duration of symptom over 5 years and 10[40%] have had atrial thrombi before operation. Left atrial dimension were still more than 40mm in 21 patients on follow up M-mode echocardiogram. One month after operation, 87 hospital survivors were improved by at least one functional NYHA class. There were 3 operative deaths [3.3%, bleeding 1, LCOS 2] and 4 late deaths [LCOS 1, valve thrombosis 1, late bleeding 1, fulminant hepatitis 1] during follow-up period. According to our limited experience, we may conclude that better results will be expected with the addition of quinidine therapy judiciously in the cases of postoperative persistent atrial fibrillation who were aged or had longer history of symptom and left atrial thrombi.

• Journal of Chest Surgery
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• v.47 no.3
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• pp.225-232
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• 2014

Background: Redo coronary artery bypass grafting (CABG) is still associated with increased morbidity and mortality as compared to the first-time operation. Further, the application of the off-pump technique to redo CABG is limited due to technical difficulties. The aim of this retrospective study was to analyze early and midterm results after redo CABG and compare the outcome of redo on-pump and off-pump CABG. Methods: From June 1996 to October 2011, elective redo CABG was performed in 32 patients. Mean age was 64.8 years (on pump 64.3 years vs. off pump 65.5 years; p=0.658), and 21 patients were male. Among these patients, 14 (43.8%) underwent on-pump CABG, and 18 (56.2%) underwent off-pump CABG. Results: Internal thoracic artery was used in 22 patients (68.8%), and total arterial revascularization was achieved in 17 patients (53.1%). The average number of distal anastomoses was 2.13, and the rate of incomplete revascularization was 43.8%. The rate of total arterial revascularization was higher in the off-pump group (14.3% vs. 83.3%, p<0.001), and the use of saphenous vein graft was more in the on-pump group (78.6% vs. 16.7%, p<0.001). Overall hospital mortality was 3.1% (n=1) and was comparable in both groups (on pump 7.1% vs. off pump 0%; p=0.249). Postoperative complications occurred in 9 patients (64.2%), and the rate of complications was high in the on-pump group without statistical significance (64.2% vs. 33.3%, p=0.082). The mean follow-up duration was 5.4 years, and overall survival at 10 years was $86.0%{\pm}10.5%$. There was no significant difference in the 10-year survival rate between the two groups (79.6% vs. 100%, p=0.225). Conclusion: Redo CABG can be safely performed with acceptable mortality. Redo off-pump coronary artery bypass is feasible with low mortality and morbidity, comparable target vessel bypass grafting, and long-term survival. The off-pump technique might be considered a safe option for redo CABG in high-risk patients.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.155-164
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• 2014

Carbon-fiber-reinforced plastic (CFRP) composites are increasingly being used in a variety of industry applications, such as aircraft, automobiles, and ships because of their high specific stiffness and high specific strength. Aircraft are exposed to high temperatures and high humidity for a long duration during flights. CFRP materials of the aircraft can absorb water, which could decrease the adhesion strength of these materials and cause their volumes to change with variation in internal stress. Therefore, it is necessary to estimate the characteristics of CFRP composites under actual conditions from the viewpoint of aircraft safety. In this study air-coupled ultrasonic testing (ACUT) was applied to the evaluation of water absorption properties of CFRP composites. CFRP specimens were fabricated and immersed in distilled water at $75^{\circ}C$ for 30, 60, and 120 days, after which their ultrasonic images were obtained by ACUT. The water absorption properties were determined by quantitatively analyzing the changes in ultrasonic signals. Further, shear strength was applied to the specimens to verify the changes in their mechanical properties for water absorption.

• Journal of the Korean Child Neurology Society
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• v.26 no.4
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• pp.221-226
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• 2018

Purpose: Febrile seizures (FSs) are the most common type of seizure in the first 5 years of life and are frequently associated with viral infections. Influenza infection is associated with a variety of neurological conditions, including FSs. The purpose of this study was to evaluate the clinical implications of influenza infection in FSs. Methods: In total, 388 children with FS were divided into two groups: FS with influenza infection (n=75) and FSs without influenza infection (n=313). Their medical records, including seizure type, frequency, duration, and familial history of FSs or epilepsy, were retrospectively reviewed and the clinical characteristics of the two groups were compared. Results: In total, 75 of the 388 children (19.3%) had FSs associated with influenza infection; such children were significantly older than those with FSs without influenza infection ($34.9{\pm}22.3$ months vs. $24.4{\pm}14.2$ months; P<0.001). The children who had more than two febrile seizures episodes were more prevalent in children with FS with influenza infection [40/75 (53.3%) vs. 92/313 (29.4%); P<0.01]. Children older than 60 months were more likely to have influenza infection compared to those aged less than 60 months [11/22 (50%) vs. 64/366 (17.5%); P=0.001]. Conclusion: Influenza infection may be associated with FSs in older children, and with recurrence of FSs. Its role in the development of afebrile seizures or subsequent epilepsy requires further investigation with long-term follow-up.

• Journal of the Korean Society of Child Welfare
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• no.58
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• pp.231-262
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• 2017

South Korea has long been a culturally homogenous society, yet the increasing number of immigrants has turned the country into a multicultural society. Therefore, many empirical studies have investigated the way immigrants adapt to the Korean society and its associated factors. However, examining the overall process of migration (from family separation to reunification and cultural adaptation to the host society) that immigrant youth usually experience has been understudied. Previous empirical research and theoretical work have identified prominent factors that predict immigrant youth's mental health: experiences of family separation, living with others rather than primary caretakers during the separation, the length of residency in the host society, and family and peer support. In this respect, this exploratory and preliminary study that examined whether the experience of migration process and post-migration are related to Korean immigrant youth's mental health problems (depression, anxiety, and suicidal ideation). The result indicated that longer duration of family separation; living with relatives, siblings; and friends rather than primary caretakers during the separation; receiving less support from family and peer after migration; and a lower degree of cultural adaptation to Korean culture were associated with depression, anxiety, and suicidal ideation. Drawing upon the results, this study discussed implications for policy and practice.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.109-121
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• 2012

Rock-surface temperatures were observed at a trachytic lava dome, called as Baeknokdam Northwest Face, in the summit area of Mt. Halla, Jeju Island, to examine the frequency and occurrence season of freeze-thaw cycles and the rate of temperature changes during a freezing period. Long-term measurements were recorded over 18 months from November 2006 to April 2008, at a 1-hour logging interval and rock depth of 1.5 cm. Both diurnal freeze-thaw cycles and effective freeze-thaw cycles appear in larger numbers on a south-facing rock face than a north-facing rock face. The diurnal cycles were dominantly observed on February and March for the south face and on November and April for the north face, respectively. The annual freeze-thaw cycles were confirmed in terms of the presence of seasonal freezing periods lasting from mid-November to mid-April for the south face and from early-November to late-April for the north face, respectively. The rate of decreasing temperatures during the seasonal freezing periods is larger on the north face than the south face. Notwithstanding the lower numbers of freeze-thaw events, the north face experiences a higher frost intensity since the number of hours below $-3^{\circ}C$ is larger on the north face than the south face. The number of freeze-thaw events and the duration of days with continuous sub-zero rock temperatures largely depend on the solar radiation controlled by the aspect of the monitored rock surfaces, and thus the high-frequency short-term frost cycle dominantly appears on the south face and the annual frost cycle on the north face, respectively.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.2
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• pp.233-239
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• 1997

Embryos of most mammalian species grown in vitro would undergo developmental arrest at the approximate time of genomic activation. Stage-specific cell block and the resulting rapid loss of embryo viability in conventional culture media have limited the duration for which embryos may be cultured prior to transfer. As a result, embryos are usually transferred to the uterus at the 4-to 8-cell stage to avoid the loss of viability associated with long-term in vitro culture. Early transfer has led to asynchrony of the endometrium-trophectoderm interaction at the time of implantation and a resultant reduction in the rate of implantation. To overcome these problems, a variety of co-culture systems has been devised in which embryos can develop for a longer period prior to embryo transfer. Vero cells, derived from African green monkey kidney, share a common embryologic origin with cells from the genital tract. In addition, they are potentially safe to use, since they are highly controlled for viruses and other contaminants. Therefore, co-culture using Vero cells has been widely utilized to enhance embryo viability and development, although not without controversies. We thus designed a series of experiments to demonstrate whether Vero cells do indeed enhance mouse embryo development as well as to compare the efficacy of co-culturing mouse 1-cell embryos on Vero cell monolayer in both Ham's F-10 and human tubal fluid (HTF) culture media. 1-cell stage ICR mouse embryos were cultured either in the presence of Vero cells (Group A) or in conventional culture medium alone (Group B). In Ham's F-10 significantly more 3-to-8cell embryos developed in group A than group B (59.8 versus 10.0%; p<0.01). In contrast, there was no significant difference in embryonic development both group A and group B in HTF. However, significant differences were noted only in later embryonic stage (13 and 0%; p<0.05 of group A and B respectively, hatching or hatched). In Ham's F-10, we also could observe the beneficial effect of Vero cell on hatching process (70.7 and 42.1%; p<0.05 of group A and group B respectively).

• The Journal of the Petrological Society of Korea
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• v.25 no.3
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• pp.261-281
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• 2016

Our knowledge of the lithosphere beneath the Korean Peninsula has been improved through petrologic and geochemical studies of upper mantle xenoliths hosted by Quaternary intraplate alkali basalts from Jeju Island. The xenoliths are mostly spinel lherzolites, accompanied by subordinate harzburgite and pyroxenites. The mantle xenoliths represent residual mantle material showing textural and geochemical evidence for at least a three-stage evolution, fractional partial melting, recrystallization, and metasomatism. Their composition primarily controlled by early fractional melt extraction and porphyroclastic and mylonitic fabrics formed in a shear-dominated environment, which was subsequently modified by residual slab-derived fluids (or melts). Modal metasomatic products occur as both anhydrous phase(orthopyroxene) and hydrous phase (phlogopite). Late-stage orthopyroxene is more common than phlogopite. However, chemical equilibrium is evident between the primary and secondary orthopyroxene, implying that the duration of post-metasomatic high temperatures enabled complete resetting/reequilibration of the mineral compositions. The metasomatic enrichment pre-dates the host Jeju Quaternary magmatism, and a genetic relationship with the host magmas is considered unlikely. Following enrichment in the peridotite protolith in the mantle wedge, the upper mantle beneath proto-Jeju Island was transformed from a subarc environment to an intraplate environment. The Jeju peridotites, representing old subarc fragments, were subsequently transported to the surface, incorporated into ascending Quaternary intraplate alkali basalt. The result of this study implies that long term material transfer in the transformation of geotectonic setting from a subarc to intraplate may have played a significant role in the evolution of lithospheric mantle, resulting in the enriched mantle domains, such as EM I or EM II in the lithospheric mantle beneath East Asia.