• Journal of Chest Surgery
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• v.31 no.12
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• pp.1165-1171
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• 1998

Background: All currently available mechanical and bioprosthetic valves are associated with various types of deterioration leading to dysfunction and/or valvular complications. Reoperation on prosthetic heart valves is increasingly under consideration for both clinical and prophylactic indications. This review was conducted to determine the factors affecting the risk of reoperation for prosthetic valve replacement. Material and method: From January 1985 to July 1996, 124 patients underwent reoperation on prosthetic heart valves, and 3 patients had a second valve reoperation. The causes of reoperation were prosthetic valve failure(96 cases, 77.4%), prosthetic valve thrombosis(16 cases, 12.9%), prosthetic valve endocarditis(7 cases, 5.6%) and paravalvular leak(5 cases, 4.1%). This article is based on the analysis of the experience with particular emphasis on the preoperative risks affecting the outcome of the reoperation. Result: Overall hospital mortality rate was 8.9%(11/124). Low cardiac output was the most common cause of death(70.6%). Left ventricular systolic dimension(p=0.001), New York Heart Association functional class IV(p=0.003) and serum creatinine level(p=0.007) were the independent risk factors, but age, sex and cardiothoracic ratio did not have any influence on the operative mortality. Follow-up period was ranged from 3 to 141 months (mean, 50.6 months). A late mortality rate was 1.8%. Conclusion: The surgical risk of reoperation on heart valve prostheses in the advanced NYHA class patients is higher, therefore reoperation is recommended before the hemodynamic impairment become severe.

• Korean Journal of Environment and Ecology
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• v.18 no.4
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• pp.359-368
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• 2004

The purpose of this study is to examine distribution and damages of the trails of inquiry of urban natural parks. Those parks were located at south-north green corridor at Incheon being mountainous type of urban natural parks that were core area of urban ecosystem preservation to of urban natural parks that citizens recently made use of them as nature experience type of leisure and recreation place from time to time, and to supply basic material deciding on the ways to improve the trails of nature preservation type. The survey sites included Geyang Park, Baekma Park, Yaksa Park, Munhak Park and Cheongryang Park. The number of main trails was 42 at Geyang Park, 43 at Baekma Park, 9 at Yaksa Park, 28 at Munhak Park, and 22 at Cheongryang Park, and it was excessively more than optimum needed: The number of branch trails of the parks seemed to increase. The bared trail width in average of the roads was 3.5m, while maximum depth in average was 21.3cm. The trails were thought to be deteriorated rapidly without systematic maintenance. The 5th and 6th grade of the impact rating class that required restoration because of serious deterioration occupied 19.6∼78.0%. Based on the findings, the study suggested ways to improve and manage the trails of inquiry of urban natural parks that were placed at south-north green corridor at Incheon.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.4
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• pp.24-35
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• 2006

The vascular plants of the studied area was listed 384 taxa of 90 families, 234 genera, 331 species, 1 subspecies, 45 varieties and 7 forms. The flora of each reservoir, 285 taxa of 83 families, 190 genera, 247 species, 1 subspecies, 30 varieties, 7 forms in Osongjae, 117 taxa of 39 families, 87 genera, 100 species, 17 varieties in Ogongjae, 83 taxa of 30 families, 67 genera, 73 species, 8 varieties, 2 forms in Shinyongjae and 86 taxa of 33families, 70 genera, 75 species, 1 subspecies, 10 varieties in Eodujae. Based on the list of the rare plants by the Forest Research Institute, 3 taxa were recorded in the studied areas; Magnolia kobus (Preservation priority order : No. 187), Penthorum chinense (No. 144), Prunus yedoensis (No. 110) and based on the list of Korean endemic plants, 4 taxa were recorded; Populus tomentiglandulosa, Clematis trichotoma, Prunus yedoensis, Paulownia coreana. Specific plant species by floral region were total 15 taxa; Prunus yedoensis in class V, 2 taxa (Carex idzuroei, Magnolia kobus) in class IV, 2 taxa (Monochoria korsakowi, Poncirus trifoliata ) in class III, 10 taxa (Sagittaria aginashi, Salix glandulosa, Clematis brachyura, Nymphoides peltata, etc.) in class I. The naturalized plants in this site were 13 families, 29 genera, 43 species, 1 varieties, 44 taxa and naturalization rate was 11.5% and based on the list of an ecosystem disturbance plants, 3 taxa were recorded in the studied areas : Paspalum distichum, Solanum carolinense, Ambrosia artemisiifolia var. elatior. The hydrophytes was listed 31 taxa of 15 families, 20 genera, 29 species, 2 varieties and Eleocharis mamillata var. cyclocarpa, Penthorum chinense, Soirodela polyrhiza were recorded in Osongjae, Sagittaria aginashi, Eleocharis kuroguwai, Scirpus juncoides, Scirpus triqueter, Monochoria korsakowi, Monochoria vaginalis var. plantaginea were recorded in Ogongjae. Besides, Scirpus fluviatilis, Trapa pseudoincisa were recorded in Shinyongjae and Scirpus triangulatus, Nymphoides peltata, Myriophyllum verticillatum were recorded in Eodujae. This site is located in the urban area and ecosystem-disturbing wild animal and plant has been imported here, therefore ecosystem has been disturbed more and more. The wetland here rapidly has changed into upland, so it needs conservation measures through long-term monitoring.

• Journal of Chest Surgery
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• v.28 no.1
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• pp.23-30
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• 1995

From January 1985 to December 1992, of 1257 patients who underwent a heart valve replacement 210 [16.8% underwent reoperation on prosthetic heart valves, and 6 of them had a second valve reoperation. The indications for reoperation were structural deterioration [176 cases, 81.5% , prosthetic valve endocarditis [25 cases, 11.6% , paravalvular leak [12 cases, 5.6% , valve thrombosis [2 cases, 0.9% and ascending aortic aneurysm [1 case, 0.4% . Prosthetic valve failure developed most frequently in mitral position [57.9% and prosthetic valve endocarditis and paravalvular leak developed significantly in the aortic valve [40%, 75% [P<0.02 . Mean intervals between the primary valve operation and reoperation were 105.3$\pm$28.4 months in the case of prosthetic valve failure, 61.5$\pm$38.5 months in prosthetic valve endocarditis, 26.8$\pm$31.2 months in paravalvualr leak, and 25.0$\pm$7.0 months in valve thrombosis. In bioprostheses, the intervals were in 102.0$\pm$23.9 months in the aortic valve, and 103.6$\pm$30.8 months in the mitral valve. The overall hospital mortality rate was 7.9% [17/26 : 15% in aortic valve reoperation [6/40 , 6.5% in reoperation on the mitral prostheses [9/135 and 5.7% in multiple valve replacement [2.35 . Low cardiac output syndrome was the most common cause of death [70.6% . Advanced New York Heart Association class [P=0.00298 , explant period [P=0.0031 , aortic cross-clamp time [P=0.0070 , prosthetic valve endocarditis [P=0.0101 , paravalvularr leak [P=0.0096 , and second reoperation [P=0.00036 were the independent risk factors, but age, sex, valve position and multiple valve replacement did not have any influence on operative mortality. Mean follow up period was 38.6$\pm$24.5 months and total patient follow up period was 633.3 patient year. Actuarial survival at 8 year was 97.3$\pm$3.0% and 5 year event-free survival was 80.0$\pm$13.7%. The surgical risk of reoperation on heart valve prostheses in the advanced NYHA class patients is higher, so reoperation before severe hemodynamic impairment occurs is recommended.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.646-650
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• 2014

In this paper, in order to avoid the deterioration of the pattern classification performance which results from the curse of dimensionality, we propose a new feature selection method. The newly proposed feature selection method is based on Fuzzy C-Means clustering algorithm which analyzes the data points to divide them into several clusters and the concept of a function with fuzzy numbers. When it comes to the concept of a function where independent variables are fuzzy numbers and a dependent variable is a label of class, a fuzzy number should be related to the only one class label. Therefore, a good feature is a independent variable of a function with fuzzy numbers. Under this assumption, we calculate the goodness of each feature to pattern classification problem. Finally, in order to evaluate the classification ability of the proposed pattern classifier, the machine learning data sets are used.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.1
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• pp.57-62
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• 2004

We have proposed an efficient method of word separation in a handwritten legal amount on bank check based on the spatial gaps between the connected components. The previous gap measures all suffer from the inherent problem of underestimation or overestimation that causes a deterioration in separation performance. In order to alleviate such burden, we have developed a modified version of each distance measure. Also, 4 class clustering based method of integrating three different types of distance measures has been proposed to compensate effectively the errors in each measure, whereby further improvement in performance of word separation is expected. Through a series of word separation experiments, we found that the modified distance measures show a better performance with over 2 - 3% of the word separation rate than their corresponding original distance measures. In addition, the proposed combining method based on 4-class clustering achieved further improvement by effectively reducing the errors common to two of three distance measures as well as the individual errors.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.56-61
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• 2008

Because the harmonic disturbance characteristic which makes voltage drop and the deterioration of instantaneous power quality in electrical power system overheats the NGR and the customer capacitor and malfunctions the OCGR and AMR, it is necessary for electric power company to take active measures to reduce this disturbance. International Electrotechnical Commission(IEC) 61000-3-2 specifies limits for harmonic current emissions generated by low voltage(LV) electrical equipment whose input current $\leq$ 16(A) per phase. Analysis shows that limits for Class A equipment in IEC are calculated using the reference impedance of LV system and maximum permissible voltage and limits for other Classes are also calculated based on limits for Class A. Therefore we have calculated four(4) internal limits for LV electrical equipment using the korea reference impedance and maximum permissible voltage in this paper.

• Atmosphere
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• v.30 no.4
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• pp.421-437
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• 2020

The effects of the terminal fall velocity-diameter relationship for raindrops, which is prescribed based on the measurement, on the simulated surface precipitation over Korea during summer season were investigated in our study. Two rainfall cases, 1-month summer precipitation and mesoscale rainfall, have been simulated using the Weather Research and Forecasting (WRF) model. The selected cloud microphysics parameterizations are WRF Single-Moment 5-class (WSM5) and WRF Single-Moment 6-class (WSM6) in the WRF model. The measured terminal fall-diameter relationship for raindrops by Gunn and Kinzer (1949) was applied in both WSM5 and WSM6. The sensitivity experiments with WSM5 and WSM6, applying the measured fall-diameter relationship, presents the different responses in simulated precipitation amount for the 1-month summer precipitation case. Precipitation increases with WSM5, thus enhancing the precipitation statistical skills. However, precipitation decreases with WSM6 leading to the deterioration of precipitation statistical skills. For the mesoscale rainfall case, precipitation increases with both WSM5 and WSM6, which further enhances the positive bias in precipitation amount.

• The Journal of Internal Korean Medicine
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• v.43 no.2
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• pp.244-253
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• 2022

Objective: This study reports on the management of a patient with myasthenia gravis (MG) following myasthenic crisis (MC) using Korean medicine. Methods: A 77-year-old Class V MG patient was treated with acupuncture, moxibustion, and Korean herbal medicine. A manual muscle test was used to derive a Medical Research Council (MRC) score and the patient's subjective view of his dyspnea was measured to assess MG symptoms. Results: The MRC grade indicated significant deterioration after 65 days of treatment, although there was no change in the patient's subjective dyspnea assessment. But no other MG or MC complications occurred. Conclusion: This study suggests that Korean medicine could be used for the management of Class V MG patients.

• Korean Journal of Remote Sensing
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• v.8 no.1
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• pp.27-43
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• 1992

The purpose of this study is to detect and evaluate the change of urban vegetation of Seoul during 1980s. Large areas covered with agricultural crops or forests were converted to residential and commercial areas, roads, schools, sports complexes, etc. There were also widespreas concerns on the deterioration of the quality of urban vegetation due to severe air pollution, overcrowding of nature parks, and idling of farm lands by land speculators. The image used for this study were MSS(Oct. 4, 1979) and TM(Apr. 26, 1990). The Green Vegetation Index of Kauth & Thomas(1976) was for the analysis. The GVI were resampled with 75$\times$75m grids and overlaid with the jurisdictional boundaries of 22 districts of Seoul. The results were reclassified to 6 classes, class 6 representing grids with the most vigorous vegetation or the best vegetation improvement in 1980s. The finding of this study can be summarized as follows : First, the most vigorous vigorous vegetation, in terms of GVI, of the 1979 image can be found at paddy fields located on alluvial near Han River. Broad-leaf forests located on hilly terrains have higher GVI than conifers located on the upper-parts of mountains. The average GVI of the northern part and southern part of Han River are 3.56 and 3.74, respectively. The main reason why the southern part has higher GVI is that there are more prime agricultural lands. Districts of Kangseo, Yangcheon, and Songpa have the highest percentage of grids of GVI class 6, and the percentages are 3.55 %, 3.47 %, and 2.69 %, respectively. Second, the most vigorous vegetation of the 1990 image can be found at the grass lands of the Yongsan golf club and the Sungsu horse racing track. The GVI of farm lands is lower than forest because most agricultural crops are at the early stage of growing season when the TM image was taken. The size of built-up area is much larger than of 1979. On the other hand, vegetation patches surrounded by developed area become smaller and have stronger contrast to surrounding area. The average GVI of the northern part and southern part of Han River are 3.57 and 3.51, respectively. The main reason why the southern part has lower GVI is the at more large-scale urban development projects were carried out in there during 1980s. Districts of Tobong, Nowon, and Seocho have the highest percentage of class 6, and the perecentages are 16.58 %, 10.14 %, and 8.50% respectively. Third, the change of urban vegetation in Seoul during 1980s are significant. Grids of GVI change classes 1 and 2, which represent severe vegetation loss, occupy 15.97% of Seoul. Three districts which lost the most vegetation are Yangcheon, Kangseo, and Songpa, where the percentages of GVI class 1 are 13.42%, 13.39% and 9.06%, respectively. The worst deterioration was mainly caused by residential developments. On the other hand, the vegetation of some part of Seoul improved in this period. Grids of GVI change classes 5 and 6 occupy 9.83 % of Seoul. Distircts of Jung, Yongsan, and Kangnam have the highest percentage of grids with GVI change classes 5 and 6, and their percentages are 22.31%, 19.17%, and 13.66%, respectively. The improvement of vegetation occurred in two areas. Forest vegetation is generally improving despite of concerns based on air pollution and heavy use by recreationists. Vegetation in open spaces established in riverside parks, large residential areas, and major public facilities are also improving.