• Korean Journal of Heritage: History & Science
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• v.40
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• pp.357-386
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• 2007

At present, thirteen Buddhist bells of Unified Silla are known to the world: Six in Korea, five in Japan and two other bells, and three out of them are impossible to make out its original form. Therefore, we divided the form of Unified Silla Buddhist bells based on the ten other bells, and we tried out to prove the manufacturing technology by the comparison of the research material of Uncheon-dong bell and existing research materials of other bells, in other to find their linkage based on the alloy elemental composition. We divided Unified Silla Buddhist bell into two types: Type I has symmetric apsaras and regular patterns on its face and it was made in early Silla period; type II has asymmetric apsaras and irregular pattern arrangement and made in late Silla period. In particular, Uncheon-dong Buddhist bells is very similar to Komyoji[光明寺] temple bell from ninth century in Japan. It is peculiar that the apsaras on Uncheon-dong bell play vertical music instruments that are never seen in Unified Silla Buddhist bell. Most of Unified Silla Buddhist bell are compounded with Cu-Sn or Cu-Sn-Pb system. From eighth and ninth century, bells were cast with even composition of copper, tin and lead, and the bronze alloy ratio was similar to the record in Gogonggi[考工記], Jurye[周禮], a book from ancient China. Particularly, Uncheon-dong bell is in a rare case of Cu-Sn-Pb-As system. As had been rarely used in Unified Silla Buddhist bells, so we presented the relative research materials. As has the same nature as Pb. Because As easily volatilize at high temperature, it is hard to use. But it has its merit of solidity and durability. Pb enhances fluidity and thereby expresses the patterns more distinct; As makes the bell stronger. The result of lead isotope ratio could not exactly reveal a concrete producing center. However, over the analysis of our samples, hereby we suggest Uncheon-dong bell was made of materials from just one ore deposit.

• Journal of Chest Surgery
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• v.39 no.12 s.269
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• pp.900-905
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• 2006

Background: Homografts and bioprostheses are most commonly used for Rastelli operation in congenital heart disease, but the limited durability is responsible for multiple reoperations associated with increased morbidity This study evaluated long-term results after Rastelli operation with a mechanical valved conduit. Material and Method: A total of 20 patients underwent Rastelli operation with mechanical valved conduit from January 1990 to July 1992. Operative mortality was 1 of 20 patients, and a retrospective review of 19 patients(10 males, 9 females) was done. Initial diagnosis was congenitally corrected transposition of great arteries(cc-TGA, n=4), complete TGA (n=2), ventricular septal defect with pulmonary atresia(VSD with PA, n=9), truncus arteriosus(n=2), double outlet right ventricle with pulmonary stenosis(DORV with PS, n=2). The mean age at Rastelli operation was $4.6{\pm}3.4$ years, and mean follow-up period was $12.8{\pm}2.7$ years. Patients underwent Rastelli opearation using 16 CarboMedics mechanical valve, and 3 Bjork-Shiley mechanical valve($17{\pm}2$ mm). Result: There were 15 reoperations for failed mechanical valved conduit. The freedom from reoperation at 5 and 10 years was 53% and 37%. Most patients were received oral anticoagulation with warfarin, and maintained the international normalized ratio(INR) of 1.5 to 2.0. There was no anticoagulation or thromboembolism related complication. There was a significant difference in the causes of a conduit failure between early(within 3 years) and late(after 3 years) failure groups. The six patients reported early prosthetic valve failure, mainly due to valvular dysfunction by thrombosis or pannus formation. The other nine patients reported late prosthetic valve failure, mainly due to dacron conduit stenosis at anastomosis sites, whereas their valvar motion was normal except 1 patient. Conclusion: To avoid early prosthetic valve failure, strict anticoagulation therapy would be helpful. About the late development of obstructive intimal fibrocalcific peels within the Dacron conduit, an improvement of conduit material is necessary to reduce late prosthetic valve failure. In selected patients, the long term results were satisfactory.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.627-634
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• 2010

Background: The durability of the tissue valve is important in choice between a mechanical valve and a tissue valve in cardiac surgery. We studied the mid-term results of tissue valve in the aortic position. Material and Method: The subjects were 380 patients who had undergone aortic prosthesis replacement between May 1990 and March 2009. We retrospectively analyzed hospital and outpatient records: the mean age was $69{\pm}9$ years; the male to female ratio was 227 : 162; and the mean follow-up duration was $46.7{\pm}40.8$ months (range 0~196 months). Result: 389 surgical cases in total had been taken with 380 patients. Early death occurred in 15 patients (3.9%). Overall survival rate at 1, 5 and 10 years were 92.3%, 78.1% and 54.2% respectively. Freedom from reoperation at 1, 5 and 10 years were 98.4%, 97.1% and 91.7% respectively. Freedom from structural valvular deterioration at 1, 5 and 10 years were 96.1%, 92.3% and 88.0% respectively. In the multivariate analysis of preoperative risk factors, young age (p<0.001) was significant risk factor for reoperation. High peak velocity in the postoperative period (p=0.034) and young age (p=0.029) were significant risk factors for structural valvular deterioration. Old age (p=0.001), long bypass time (p=0.035), concomitant coronary artery bypass graft surgery (p=0.003) and preoperative low left ventricular ejection fraction (p=0.003) were significant factors for early mortality. Preoperative estimated glomerular filtration rate (< 60 mL/min) (p=0.025) and persistent left ventricular hypertrophy (p=0.032) were the risk factors for late mortality. Conclusion: This study showed that the freedom from reoperation and the freedom from structural valvular deterioration in aortic tissue valve replacement were acceptable. It will be necessary to conduct further studies with long-term follow-up and more patients.

• Journal of Chest Surgery
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• v.38 no.1 s.246
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• pp.23-28
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• 2005

Ross procedure is ideal aortic valve replacement method with several merits of hemodynamic superiority and durability without the need of anticoagulation. Based upon this presumption, we studied its procedure performed in our hospital and tried to get the mid-term results Material and Method: From Jan 1999 to Oct 2001, 22 patients underwent the Ross procedure. The mean age of experimented (including 17 men and 5 women) was $30.9{\pm}8.1(17\~44)$. The diagnosis before the surgery had shown 20 as accompanied with AR and the rest 2 as with ASR. The follow-up period ranged from 0.6 to 40.6 months, mean of $38.9{\pm}1.6\;months,\;and\;follow-up\;rate\;was\;100{\%}$. Result. There was no operative death and two late deaths, one of whom was cardiac originated and the other, non-cardiac relate The survival rate was $94.1{\pm}5.7{\%}$(40.6 months). Postoperatively there were 2 exploration for bleeding, 3 low cardiac output patients. The pulmonary autograft technique was root replacement in 14 and inclusion technique in 8. Pulmonary homografts were used at the pulmonary position in all cases. There was no patient with significant aortic regurgitation. Conclusion: These showed that the mortality and morbidity of the Ross procedure were acceptable and postoperative AR was not significant. However, further long-term follow-up will be necessary for the improvement of the function of pulmonary autograft and homograft.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.317-323
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• 2017

In this study, the heating performance and the energy saving effect of the heat pump system using hot waste water(waste heat) of the thermal power plant discharged from a thermal power plant to the sea were analyzed. The greenhouse area was $5,280m^2$ and scale of the heat pump system was 120 RT(Refrigeration Ton), which was divided into 30 RT, 40 RT and 50 RT. The heat pump system consisted of the roll type heat exchangers, hot waste water transfer pipes, heat pumps(30, 40, 50 RT), a heat storage tank and fan coil units. The roll type heat exchangers was made of PE(Poly Ethylene) pipes in consideration of low cost and durability against corrosion, because hot waste water(sea water) is highly corrosive. And the heating period was 5 months from October to February. During the heating performance test(12 hours), the inlet water temperature of evaporator was changed from $32^{\circ}C$ to $26^{\circ}C$, and heat absorption of he evaporator was changed from 175 kW to 120 kW. The inlet water temperature of the condenser rose linearly from $15^{\circ}C$ to $50^{\circ}C$, and the heat release of condenser was reduced by 40 kW from 200 kW to 160 kW. And the power consumption of the heat pump system increased from 30 kW to 42 kW. When the inlet water temperature of condenser was $15^{\circ}C$, the heating COP(Coefficient Of Performance) was over 7.0. When it was $30^{\circ}C$, it dropped to 5.0, and when it was above $40^{\circ}C$, it decreased to less than 4.0. It was analyzed that the reduction of heating energy cost was 87% when compared to the duty free diesel that the carbon dioxide emission reduction effect was 62% by recycling the waste heat of the thermal power plant as a heat source of the heat pump system.

• Journal of Periodontal and Implant Science
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• v.27 no.4
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• pp.751-765
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• 1997

Periodontal disease is a bacterially causal by disease, To remove plaque and bacteria, it has been necessary to prescribe chemical drug to patient to subjugate therapeutic unvalue by mechanical scaling. As a patient on a high dosage of the antibiotics to maintain the effective concentration may produce unfavorable side effects, this decase demands the Slow-release local drug delivery system. The object of the experiment is to study on the slow-release local drug delivery effects of calcium sulfate compounded with tetracycline that mainly used in periodontal disease. Experimental groups were divided into four classes as follow: Group 1 10% tetracycline compounded modified calcium sulfate paste. Group 2 : compounded and hardened 10% tetracycline and calcium sulfate. Group 3 : compounded 10% tetracycline and calcium sulfate, used Just before hardened. Group 4 : tetracycline-ethylene vinyl acetate fiber. In the four groups, release concentration, it's durability and the period of absorption by times are observed and concluded as follow: 1. An effective concentration($4{\mu}g/ml$) remained until 5 weeks in group 1, 9 days in group 2, 7 days in group 3, 15 days in group 4. 2. It was fully fused at 11.8 days average in group 2 and 14.8 days average in group 3. . There were no statistically significant results in tetracycline concentration until a week in group 2 and 3(p<0.05) These results suggest that tetracycline loaded calcium sulfate release sufficient tetracycline and fused in $11{\sim}14$ days, so calcium sulfate is useful carrier as slow release local drug delivery system.

• Journal of Technology Innovation
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• v.26 no.3
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• pp.37-68
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• 2018

Since the 20th century, automobiles, which are the most common means of transportation, have been evolving as the use of electronic control devices and automotive semiconductors increases dramatically. Automotive semiconductors are a key component in automotive electronic control devices and are used to provide stability, efficiency of fuel use, and stability of operation to consumers. For example, automotive semiconductors include engines control, technologies for managing electric motors, transmission control units, hybrid vehicle control, start/stop systems, electronic motor control, automotive radar and LIDAR, smart head lamps, head-up displays, lane keeping systems. As such, semiconductors are being applied to almost all electronic control devices that make up an automobile, and they are creating more effects than simply combining mechanical devices. Since automotive semiconductors have a high data rate basically, a microprocessor unit is being used instead of a micro control unit. For example, semiconductors based on ARM processors are being used in telematics, audio/video multi-medias and navigation. Automotive semiconductors require characteristics such as high reliability, durability and long-term supply, considering the period of use of the automobile for more than 10 years. The reliability of automotive semiconductors is directly linked to the safety of automobiles. The semiconductor industry uses JEDEC and AEC standards to evaluate the reliability of automotive semiconductors. In addition, the life expectancy of the product is estimated at the early stage of development and at the early stage of mass production by using the reliability test method and results that are presented as standard in the automobile industry. However, there are limitations in predicting the failure rate caused by various parameters such as customer's various conditions of use and usage time. To overcome these limitations, much research has been done in academia and industry. Among them, researches using data mining techniques have been carried out in many semiconductor fields, but application and research on automotive semiconductors have not yet been studied. In this regard, this study investigates the relationship between data generated during semiconductor assembly and package test process by using data mining technique, and uses data mining technique suitable for predicting potential failure rate using customer bad data.

• Journal of Chest Surgery
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• v.30 no.7
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• pp.656-662
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• 1997

Aortic valvuloplasty has recently gained attention as an attractive alternative procedure for aortic valvular disease. Between March 1995 to August 1996, 14 patients with pure aortic regurgitation(AR) underwent aortic alvuloplasty using leaflet extension with glutaraldehydepreserved autologous pericardium. There were 11 males and 3 females, and the mean age was 34.8 $\pm$ 15.3 years. Preoperative echocardiography and cardiac catheterization revealed that the degree of AR was mean 3.4$\pm$0.65, and more than moderate degree of mitral regurgitation(MR) were detected in 4 patients. In 12 patients, 3 leaflets were extended and in another 2 patients only one deformed leaflet was extended. Concomitant mitral valvuloplasty (MVP) was performed in 4 patients. The competency of the aortic valve after completion of repair was evaluated by the transesophageal echocardiography in operating theater, and there was no aortic and mitral stenosis or regurgitation. In an early postoperative echocardiography, trivial AR was detected in 3 patients and mild MR in 1 patient. The end-systolic and end-diastolic dimensions of the left ventricle were decreased significantly(p<0.05) as compared with those of preoperative values. T ere was no mortality and no significant postoperative complication encountered. Late complication developed in 2 patients during the follow-up period(mean 7.9$\pm$ 5.9 months). One patient underwent AVR on postoperative 7th month due to endocarditis, and the another patient with Behcet's disease underwent Ross operation at postoperative 4th month. In conclusion, AVP of leaflet extension technique offers an excellent early clinical result and represents a good alterna!ivy surgical treatment for the pure AR especially in young age group, although long-term follow-up is necessary to determine the durability of glutaraldehyde-preserved autologous pericardium as a valve leaflet.

• Journal of Chest Surgery
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• v.37 no.6
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• pp.482-491
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• 2004

Background: The xenogenic or allogenic valves after in Vitro repopulation with autologous cells or in vivo repo-pulation after acellularization treatment to remove the antigenicity could used as an alternative to synthetic polymer scaffold. In the present study, we evaluated the process of repopulation by recipient cell to the acellu-larized xenograft treated with NaCl-SDS solution and grafted in the right ventricular outflow tract. Material and Method: Porcine pulmonary valved conduit were treated with. NaCl-SDS solution to make the grafts acellularized and implanted in the right ventricular outflow tract of the goats under cardiopulmonary bypass. After evaluating the functions of pulmonary valves by echocardiography, goats were sacrificed at 1 week, 1 month, 3 months, 6 months, and 12 months after implantation, respectively. After retrieving the implanted valved conduits, histopathologic examination with Hematoxylin-Eosin, Masson' trichrome staining and immunohistochemical staining was performed. Result: Among the six goats, which had been implanted with acellularized pulmonary valved conduits, five survived the expected time period. Echocardiographic examinations for pulmonary valves revealed good function except mild regurgitation and stenosis. Microscopic analysis of the leaflets showed progressive cellular in-growth, composed of fibroblasts, myofibroblasts, and endothelial cells, into the acellularized leaflets over time. Severe inflammatory respon-se was detected in early phase, though it gradually decreased afterwards. The extracellular matrices were regenerated by repopulated cells on the recellularized portion of the acellularized leaflet. Conclusion: The acellularized xenogenic pulmonary valved conuits were repopulated with fibroblasts, myofibroblasts, and endothelial cells of the recipient and extracellullar matrices were regenerated by repopulted cells 12 months after the implantation. The functional integrity of pulmonary valves was well preserved. This study showed that the acellularized porcine xenogenic valved conduits could be used as an ideal valve prosthesis with long term durability.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.156-166
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• 2000

This study was carried out to provide the information on seasonal variations of water content under highway asphalt pavements which influence on the dynamic behaviour and durability of pavements, and to assess the correlation between water content and soil or meteorological factors. Total eight sites for water content measurement which included fives sites in Kyungbu, two sites in Honam, and one site in Youngdong Highway were selected considering the variations in geology, topology and meteorology factors over all the country. Water contents under asphalt pavements were measured up to 170 cm depth every two week for total 13 months of August 1992 through September 1993 using neutron moisture meter(CPN-503DR). The range of water content ($\theta$$_{w}$) at the upper soils of above 50 cm depth was 7~12% and was not quite different regardless of sites, except for Iseo site. However, soil water contents below 60 or 70 cm depth were significantly different between the measurement sites, that is, the lowest water content was 5% at Kyungsan site and the highest water content was 20% at Iseo site. For all the sites, seasonal variations in water content during the experimental period were little, their range was within only 1 to 4%. Seasonal variations of water content in original or cutting area, which were 4% more or less, were slightly larger than in bedding areas, which were below 2%. Water contents under asphalt pavements had statistically significant positive correlations with silt and clay content in soil, but there were little correlations between water content and meteorological factors such as precipitation, relative humidity, mean air temperature, and wind velocity.