• Journal of Chest Surgery
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• v.36 no.8
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• pp.576-582
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• 2003

During the Off-Pump Coronary Arterial Bypass surgery (OPCAB), the manipulation of the heart can depress cardiac contractility and cause hemodynamic instability. In this study, hemodynamic parameters were measured during operation and the laboratory and clinical data were investigated to evaluate their effects on postoperative outcome. Material and Method: From March 2001 to August 2002, 50 consecutive patients who underwent OPCAB were included in this study. During the same period, total number of CABG was 71 The blood pressure, pulmonary artery pressure, mixed venous oxygen saturation, and cardiac index were measured before manipulation, after application of stabilizer, and at the end of anastomosis. Postoperatively, we measured the cardiac enzymes such as CK-MB, troponin 1 and checked the amount of inotropes required, chest tube drainage, the amount of transfusion, duration of ventilator support, and duration of ICU stay. Result: The number of mean distal anastomoses was 2.8$\pm$0.9 per patient. On elevation and stabilization of the heart, systolic blood pressure was depressed and pulmonary artery pressure was elevated significantly, but during each anastomosis no significant changes were detected. The peak level of cardiac markers was 29.2$\pm$46.7 for CK-MB, 0.69$\pm$0.86 for troponin 1 on postoperative day f. Among the intraoperative hemodynamic parameters, the ischemic change of EKG and bolus injection of inotropes significantly affected the posteroperative cardiac enzymes. But, no difference other than the level of cardiac enzymes between the two groups with or without the ischemic change of EKG and bolus injection of inotropes was noticed. Conclusion: The significant hemodynamic changes occurred when the heart was elevated and stabilized, however during anastomoses there were no significant changes. Serum cardiac enzymes rose significantly in the group that showed the ischemic charge of EKG or needed the bolus injection of inotropes for maintaining hemodynamic stability intraoperatively, but it did not affect the postoperative outcome. In conclusion, the ischemic change of EKG and the need for bolus injection of intropes during operation may be very indicative for probable ischemia.

• Journal of Chest Surgery
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• v.40 no.3 s.272
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• pp.193-199
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• 2007

Background: Reoperation is usually required for a right ventricle to pulmonary artery conduit obstruction caused by valve degeneration, conduit peel formation or somatic growth of the patient. An autologous tissue reconstruction (peel operation), where a prosthetic roof is placed over the fibrotic tissue bed of the explanted conduit, has been used to manage conduit obstructions at our institute since May 2002. Herein, the early and midterm results are evaluated. Material and Method: Between May 2002 and July 2006, 9 patients underwent obstructed extracardiac conduit replacement with an autologous tissue reconstruction, at a mean of 5.1 years after a Rastelli operation. The mean age at reoperation was $7.5{\pm}2.4$ years, ranging from 2.9 to 10.1 years. The diagnoses included 6 pulmonary atresia with VSD, 2 truncus arteriosus and 1 transposition of the great arteries. The preoperative mean systolic gradient was $88.3{\pm}22.2mmHg$, ranging from 58 to 125 mmHg. The explanted conduits were all Polystan valved pulmonary conduit (Polystan, Denmark). A bioprosthetic valve was inserted in 8 patients, and a monocusp ventricular outflow patch (MVOP) was used in 1 patient. The anterior wall was constructed with a Gore-Tex patch (n=7), MVOP (n=1) and bovine pericardium (n=1). Pulmonary artery angioplasty was required in 5 patients and anterior aortopexy in 2. The mean cardiopulmonary bypass time . was 154 minutes, ranging from 133 to 181 minutes; an aortic crossclamp was not performed in all patients. The mean follow-up duration was 20 months, ranging from 1 to 51 months. All patients were evaluated for their right ventricular outflow pathway using a 3-D CT scan. Resuit: There was no operative mortality or late death. The mean pressure gradient, assessed by echocardiography through the right ventricular outflow tract, was 20.4 mmHg, ranging from 0 to 29.6 mmMg, at discharge and 26 mmHg, ranging from 13 to 36 mmHg, at the latest follow-up (n=7, follow-up duration >1 year). There were no pseudoaneurysms, strictures or thrombotic occlusions. Conclusion: A peel operation was concluded to be a safe and effective re-operative option for an obstructed extracardiac conduit following a Rastelli operation.

• Korean Journal of Environmental Agriculture
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• v.22 no.2
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• pp.79-86
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• 2003

This research was conducted to present reference data to be used as newly reclaimed tidal land management. We investigated vegetation succession at 4 reclaimed/reclaiming project areas and discussed relationship with soil and vegetation trhrough investigation and analysis soil chemical characteristics at 2 areas. 14 families 58 kinds were investigated. Vegetation were variou at Dea-Ho conservation polt and Seok-Mun National Industrial Area which are maintaining naturally. Vegetation were simple at Hong-Bo and Dongjin and MinKyong river areas which effected sea water. Common species that were investigated at 9 sites were Suaeda asparagoides, Aster tripolium, Phragmites australis, Suaeda maritima, Suaeda japonica, Carex scabrifolis. As soil desalinization progressing, soil classified at first saline-soidc soil, the nest saline soil and then normal soil. Chenopodiaceae revealed at about 30 dS/m of soil ECe and existed to 10 dS/m of soil ECe. At about 20 dS/m of soil ECe. Aster tripolium, Calamagrostis epigeios, and Sonchus brachyotus revealed and then non-halophytes and common plants at inland revealed at low soil ECe of about 10 dS/m. However it was not to progress vegetation sucdession and soil desalinization at the same time, owing to input of seeds or plants ect from out-ecosystem. So for promotion of vegetation at newly reclaimed tidal land, we proposed that it was very effective to plant artificially halophytes or suitable species through soil test.

• Journal of Chest Surgery
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• v.30 no.11
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• pp.1077-1082
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• 1997

To assess the early results, risk factors and optimal timing for coronary artery bypass graft surgery(CABG) after an acute myocardial infarction(AMI), we reviewed our 19 patients who underwent CABG within 30 days after AMI, between June 1994 and October 1996. This study excluded 1 patient whose diagnosis was AMI with ventricular septal rupture. 14 of the patients were male and 5 were female. Their ages ranged from 41 to 77 years(mean age, 60.6$\pm$ 10.4 years), and the amount of time between AMI and CABG ranged from 8 hours to 24 days(mean time, 10.6$\pm$6.4 days). There were 11 anteroseptal infarctions and 8 inferior wall infarctions. 11 patients had trsnsmural infarctions and 8 had subendocardial infarctions. Indications of operations were p imary revascularization and postinfarction angina. Three patients required preoperative intra-aortic balloon pump(IABP) support, and 4 additional patients required IABP to be separated from cardiopulmonary bypass. An average of 3.6 $\pm$ 0.6 vessels per patient were bypassed. The early mortality rate for these 19 patients was 5.3% and late mortality rate was 5.5%, 1-year and 2-year actuarial survival rates were 89.5% Univariate analysis of mortality showed that an ejection fraction less than 30% and intraopretative IABP supports were associated with risk factors(p value=0.018 and 0.015 respectively). Age, sex, time to CABG, emergency operations, types and locations of infarctions were not significant. Although our studies have weak p.oints in that there was only a small number of patients and the lack of long-term results, we could conclude that early myocardial revascularization is relatively safe after AMI for those individuals with an ejection fraction greater than 30%.

• Journal of Bio-Environment Control
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• v.24 no.2
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• pp.128-133
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• 2015

Mushrooms can grow in nature when adequate temperature and humidity are maintained, but such condition can be satisfied for only a short period of time on an annual continuum. Therefore, it can be deemed that a majority of the distributed mushrooms in the current market are produced in an artificially manipulated environment. This study was conducted to resolve the problem of the Oyster mushroom cultivation house's internal temperature and humidity imbalance, where the Oyster mushrooms are cultivated in a multi-layered shelves. The air circulation fans were installed to improve the air uniformity of the Oyster mushroom cultivation house by using multi-layered shelves. During the experiment, the ambient temperature and the ambient relative humidity ranged from $5.2^{\circ}C$ to $20.4^{\circ}C$ and 40% to 100% respectively. Due to the change of the outdoor temperature, the internal temperature of the Oyster mushroom cultivation house also changed, ranging from $13.3^{\circ}C$ to $18.4^{\circ}C$, but the temperature gap between the different internal location of the facility during the conforming recorded time only ranged from $0.2^{\circ}C$ to $1.3^{\circ}C$, being significantly stable. The internal relative humidity, ranging from 82% to 96%, also changed due to the change of the outdoor temperature. Nevertheless, the relative humidity gap between the different internal location during the conforming recorded time only ranged from 2% to 7%. Furthermore, the research staff were able to maintain the concentration of $CO_2$ from 575ppm to 731ppm(below 1,000ppm was the goal) indicating the possibility of an even management of the internal environment by installing the air circulation fan.

• Journal of Intelligence and Information Systems
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• v.23 no.3
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• pp.139-153
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• 2017

Corporate bankruptcy can cause great losses not only to stakeholders but also to many related sectors in society. Through the economic crises, bankruptcy have increased and bankruptcy prediction models have become more and more important. Therefore, corporate bankruptcy has been regarded as one of the major topics of research in business management. Also, many studies in the industry are in progress and important. Previous studies attempted to utilize various methodologies to improve the bankruptcy prediction accuracy and to resolve the overfitting problem, such as Multivariate Discriminant Analysis (MDA), Generalized Linear Model (GLM). These methods are based on statistics. Recently, researchers have used machine learning methodologies such as Support Vector Machine (SVM), Artificial Neural Network (ANN). Furthermore, fuzzy theory and genetic algorithms were used. Because of this change, many of bankruptcy models are developed. Also, performance has been improved. In general, the company's financial and accounting information will change over time. Likewise, the market situation also changes, so there are many difficulties in predicting bankruptcy only with information at a certain point in time. However, even though traditional research has problems that don't take into account the time effect, dynamic model has not been studied much. When we ignore the time effect, we get the biased results. So the static model may not be suitable for predicting bankruptcy. Thus, using the dynamic model, there is a possibility that bankruptcy prediction model is improved. In this paper, we propose RNN (Recurrent Neural Network) which is one of the deep learning methodologies. The RNN learns time series data and the performance is known to be good. Prior to experiment, we selected non-financial firms listed on the KOSPI, KOSDAQ and KONEX markets from 2010 to 2016 for the estimation of the bankruptcy prediction model and the comparison of forecasting performance. In order to prevent a mistake of predicting bankruptcy by using the financial information already reflected in the deterioration of the financial condition of the company, the financial information was collected with a lag of two years, and the default period was defined from January to December of the year. Then we defined the bankruptcy. The bankruptcy we defined is the abolition of the listing due to sluggish earnings. We confirmed abolition of the list at KIND that is corporate stock information website. Then we selected variables at previous papers. The first set of variables are Z-score variables. These variables have become traditional variables in predicting bankruptcy. The second set of variables are dynamic variable set. Finally we selected 240 normal companies and 226 bankrupt companies at the first variable set. Likewise, we selected 229 normal companies and 226 bankrupt companies at the second variable set. We created a model that reflects dynamic changes in time-series financial data and by comparing the suggested model with the analysis of existing bankruptcy predictive models, we found that the suggested model could help to improve the accuracy of bankruptcy predictions. We used financial data in KIS Value (Financial database) and selected Multivariate Discriminant Analysis (MDA), Generalized Linear Model called logistic regression (GLM), Support Vector Machine (SVM), Artificial Neural Network (ANN) model as benchmark. The result of the experiment proved that RNN's performance was better than comparative model. The accuracy of RNN was high in both sets of variables and the Area Under the Curve (AUC) value was also high. Also when we saw the hit-ratio table, the ratio of RNNs that predicted a poor company to be bankrupt was higher than that of other comparative models. However the limitation of this paper is that an overfitting problem occurs during RNN learning. But we expect to be able to solve the overfitting problem by selecting more learning data and appropriate variables. From these result, it is expected that this research will contribute to the development of a bankruptcy prediction by proposing a new dynamic model.

• Korean Journal of Remote Sensing
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• v.38 no.3
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• pp.265-282
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• 2022

Sea surface temperature (SST) is a factor that greatly influences ocean circulation and ecosystems in the Earth system. As global warming causes changes in the SST near the Korean Peninsula, abnormal water temperature phenomena (high water temperature, low water temperature) occurs, causing continuous damage to the marine ecosystem and the fishery industry. Therefore, this study proposes a methodology to predict the SST near the Korean Peninsula and prevent damage by predicting abnormal water temperature phenomena. The study area was set near the Korean Peninsula, and ERA5 data from the European Center for Medium-Range Weather Forecasts (ECMWF) was used to utilize SST data at the same time period. As a research method, Long Short-Term Memory (LSTM) algorithm specialized for time series data prediction among deep learning models was used in consideration of the time series characteristics of SST data. The prediction model predicts the SST near the Korean Peninsula after 1- to 7-days and predicts the high water temperature or low water temperature phenomenon. To evaluate the accuracy of SST prediction, Coefficient of determination (R²), Root Mean Squared Error (RMSE), and Mean Absolute Percentage Error (MAPE) indicators were used. The summer (JAS) 1-day prediction result of the prediction model, R²=0.996, RMSE=0.119℃, MAPE=0.352% and the winter (JFM) 1-day prediction result is R²=0.999, RMSE=0.063℃, MAPE=0.646%. Using the predicted SST, the accuracy of abnormal sea surface temperature prediction was evaluated with an F1 Score (F1 Score=0.98 for high water temperature prediction in summer (2021/08/05), F1 Score=1.0 for low water temperature prediction in winter (2021/02/19)). As the prediction period increased, the prediction model showed a tendency to underestimate the SST, which also reduced the accuracy of the abnormal water temperature prediction. Therefore, it is judged that it is necessary to analyze the cause of underestimation of the predictive model in the future and study to improve the prediction accuracy.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.346-362
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• 2021

A sediment control dam is an artificial structure built to prolong sedimentation in the main dam by reducing the inflow of suspended solids. These dams can affect changes in dissolved organic matter (DOM) in the water body by changing the river flow regime. The main DOM component for Yeongju Dam sediment control of the Naeseongcheon River was analyzed through 3D excitation-emission matrix (EEM) and parallel factor (PARAFAC) analyses. As a result, four humic-like components (C1~C3, C5), and three proteins, tryptophan-like components (C2, C6~C7) were detected. Among DOM components, humic-like components (autochthonous: C1, allochthonous: C2~C3) were found to be dominant during the sampling period. The total amount of DOM components and the composition ratio of each component did not show a difference for each depth according to the amount of available light (100%, 12%, and 1%). Throughout the study period, the allochthonous organic matter was continuously decomposing and converting into autochthonous organic matter; the DOM indices (fluorescence index, humification index, and freshness index) indicated the dominance of autochthonous organic matter in the river. Considering the relative abundance of cyanobacteria and that the number of bacteria cells and rotifers increased as autochthonous organic matter increased, it was suggested that the algal bloom and consequent activation of the microbial food web was affected by the composition of DOM in the water body. Research on DOM characteristics is important not only for water quality management but also for understanding the cycling of matter through microbial food web activity.

• Journal of Korean Living Environment System
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• v.16 no.2
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• pp.89-100
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• 2009

The present study was designed to observe the thermal dynamics of core and skin temperatures during sub-maximal treadmill exercise; to investigate the effect of regional body cooling during short rest after the treadmill exercise on the thermal dynamics. Three conditions (No cooling, Head/Hand cooling, Leg cooling) were simulated in a climatic chamber at 24±1℃ and 50±5%RH. Subjects performed two bouts of treadmill exercise at a rate of 80%HR_max followed by rest. Body cooling with a hood, long gloves, and a blanket that circulated water set at 15℃ was assigned during two bouts of rest. The results showed that (1) rectal temperature (T_re) did not show significant difference between three conditions; (2) Skin temperatures had specific features, depending on body regions. In particular, the initial fall phenomena of skin temperatures at the onset of exercise were noteworthy in the chest, thigh, calf, and finger tip. Of these, the most significant initial fall was found in finger temperature (T_fing). (3) During the period of the initial fall in skin temperatures, T_re gradually increased. (4) The magnitude of the fall of T_fing at the onset of 2^nd running was on average 4.8, 5.1 and 3.4℃ for Control, HH cooling, and Leg cooling, respectively (p<0.05). The initial drop of T_fing at the onset of running was maintained for an average of 8.1, 7.9 and 6.3 minutes for Control, HH cooling, and Leg cooling, with no significant differences. In conclusion, the initial fall phenomena at the onset of treadmill exercise reflected non-thermal factors, as opposed to internal thermal status. The magnitude of the initial fall in T_fing was affected by legs cooling. Therefore, the initial fall phenomenon should be considered when interpreting the thermal status of the shell during heavy works/exercises that assigned with intermittent regional body cooling.

• Korean Journal of Remote Sensing
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• v.39 no.2
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• pp.233-246
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• 2023

In terms of understanding the water cycle and efficient water resource management, the importance of soil moisture has been highlighted. However, in Korea, the lack of qualified in-situ soil moisture data results in very limited utility. Even if satellite-based data are applied, the absence of ground reference data makes objective evaluation and correction difficult. The cosmic-ray neutron probe (CRNP) can play a key role in producing data for satellite data calibration. The installation of CRNP is non-invasive, minimizing damage to the soil and vegetation environment, and has the advantage of having a spatial representative for the intermediate scale. These characteristics are advantageous to establish an observation network in Korea which has lots of mountainous areas with dense vegetation. Therefore, this study was conducted to evaluate the applicability of the CRNP soil moisture observatory in Korea as part of the establishment of a Korean cOsmic-ray Soil Moisture Observing System (KOSMOS). The CRNP observation station was installed with the Gunup-ri observation station, considering the ease of securing power and installation sites and the efficient use of other hydro-meteorological factors. In order to evaluate the CRNP soil moisture data, 12 additional in-situ soil moisture sensors were installed, and spatial representativeness was evaluated through a temporal stability analysis. The neutrons generated by CRNP were found to be about 1,087 counts per hour on average, which was lower than that of the Solmacheon observation station, indicating that the Hongcheon observation station has a more humid environment. Soil moisture was estimated through neutron correction and early-stage calibration of the observed neutron data. The CRNP soil moisture data showed a high correlation with r=0.82 and high accuracy with root mean square error=0.02 m³/m³ in validation with in-situ data, even in a short calibration period. It is expected that higher quality soil moisture data production with greater accuracy will be possible after recalibration with the accumulation of annual data reflecting seasonal patterns. These results, together with previous studies that verified the excellence of CRNP soil moisture data, suggest that high-quality soil moisture data can be produced when constructing KOSMOS.