• Journal of Chest Surgery
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• v.35 no.9
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• pp.643-652
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• 2002

As the prevalence of coronay artery disease is increasing, the surgical treatment has been universalized and operative outcome has been improved. We analyzed the short and mid-term results of 292 CABGs performed in Kangdong Sacred Heart Hospital. Material and Method: From June 1994 to December 2001, 292 patients underwent coronary artery bypass grafting. There were 173 men and 119 women and their ages ranged from 39 to 84 years with a mean of $61.8{\pm}9.1$ years. We analyzed the preoperative risk factors, operative procedures and operative outcome. In addition, we analyzed the recurrence of symptoms, long-term mortality and complications via out-patient follow-up for discharged patients. Result: Preoperative clinical diagnoses were unstable angina in 137(46.9%), stable angina in 34(11.6%), acute myocardial infarction in 40(13.7%), non-Q myocardial infarction in 25(8.6%), postinfarction angina in 22(7.5%), cardiogenic shock in 30(10.3%) and PTCA failure in 4(1.4%) patients. Preoperative angiographic diagnoses were three-vessel disease in 157(53.8%), two-vessel disease in 35 (12.0%), one-vessel disease in 11(3.8%) and left main disease in 89(30.5%) patients. We used saphenous veins in 630, internal thoracic arteries in 257, radial arteries in 50, and right gastoepiploic arteries in 2 distal anastomoses. The mean number of distal anastomoses per patient was $3.2{\pm}1.0$ There were 18 concomitant procedures ; valve replacement in 8(2.7%), left main coronary artery angioplasty in 6(2.1%), patch closure of postinfarction ventricular septal defect(PMI-VSD) in 2(0.7%), replacement of ascending aorta in 1(0.3%) and coronary endarterectomy in 1(0.3%) patient. The mean ACC time was $96.6{\pm}35.3 $ minutes and the mean CPB time was $179.2{\pm}94.6$ minutes. Total early mortality was 8.6%, but it was 3.1% in elective operations. The most common cause of early mortality was low cardiac output syndrome in 6(2.1%) patients. The stastistically significant risk factors for early mortality were hypertension, old age($\geq$ 70 years), poor LV function(EF＜40%), congestive heart failure, preoperative intraaortic balloon pump, emergency operation and chronic renal failure. The most common complication was arrhythmia in 52(17.8%) patients. The mean follow-up period was $39.0{\pm}27.0$ months. Most patients were free of symptoms during follow-up. Fourteen patients(5.8 %) had recurrent symptoms and 7 patients(2.9%) died during follow-up period. Follow-up coronary angiography was performed in 13 patients with recurrent symptoms and they were managed by surgical and medical treatment according to the coronary angiographic result. Conclusion: The operative and late results of CABG in our hospital, was acceptable. However, There should be more refinement in operative technique and postoperative management to improve the results.

• Journal of Chest Surgery
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• v.36 no.10
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• pp.741-747
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• 2003

Background: Coronary artery bypass graf t (CABG) has been settled as most safe surgery among the open heart surgeries. However, in patients with cardiogenic shock, the emergency CABG has higher mortality than elective CABG. We analyzed thirty four patients who underwent emergency CABG and report the middle and long-term results. Material and Method: From June 1994 to December 2001, 34 patients who underwent emergency CABG at Kang-dong Sacred Heart Hospital were include in this study. On the basis of hospital databases and Out Patient Department (OPD) follow up data, preoperative diagnosis, risk factor, coronary artery anatomy, operation technique, postoperative mortality, complication, recurrence of symptom, and mid and long term mortality were analyzed retrospectively. Result: Indications for emergency CABG were 29 cardiogenic shocks (85.3%), 4 intractable chest pains (11.8%), and 1 polymorphic ventricular tachycardia (2.9%). Preoperative angiographic diagnoses were triple vessel disease in 16 (47.1%) and left main disease in 8 (23.5%) patients. We used saphenous vein grafts in 81 and left internal thoracic artery grafts in 14 anastomosis. The mean number of grafts per patients was 2.8$\pm$0.8. The mean aortic cross clamp time was 91.9$\pm$34.6 minutes and the mean cardiopulmonary bypass time was 262.7$\pm$198.3 minutes. Early mortality was 50% and the most common cause of early mortality was low cardiac output in 7 (20.6%) patients. The mean follow-up period was 30.9$\pm$35.7 months. There were no recurrences of symptom and late mortality. Conclusion: In the case of emergency operation, aggressive and proper management with drugs and IABP should be done for preoperative hemodynamic stability and early surgical intervention is the most important factor for patient salvage.

• Journal of Chest Surgery
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• v.40 no.11
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• pp.727-732
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• 2007

Background: The reciptents of aortic valve replacement or a Bentall operation usually display various degrees of mitral regurgitation. When deciding whether or not to correct the mitral regurgitation, one must consider its severity, underlying causes and operative risk. Recently, the operation method for correcting the concomitant mitral regurgitation has been done through aortic root to reduce the operation time and the cardiac trauma. We report our experiences that transaortic mitral valve commissuroplasty done with aortic valve replacement or a Bentall operation has been a simple, less invasive, effective method in the operative management of mitral valve regurgitation without significant organic changes. Material and Method: Between June 2002 and June 2005, twenty patients under-went mitral valve commissuroplasty via the aortic root with aortic valve replacement (n=14) or a Bentall operation (n=7). The mitral valve regurgitation of the patients didn't exceed a moderate (grade 2) degree and there was no significant organic disease. The preoperative diagnosis of MR was established by TTE and intraoperative TEE, and the patients were followed postoperatively by TTE. The operative technique was a simple anterolateral commissuroplasty of the mitral valve with a single mattress suture via the transaortic annular approach after excision of the aortic valve leaflets. Result: The mean patient age was 56.2 years and 65% (n=13) were male. The preoperative MR was mild (grade 1) in 9 (45%), mild to moderate in 8 (40%), and moderate (grade 2) in 3 (15%) patients. There were no operative mortalities. The MR improved in all patients (p=0.002) and the left ventricular ejection fraction (LV EF) improved in 14 (70%) patients (p=0.005). The mean cross-clamp time for the patients who under- went aortic valve replacement with transaortic mitral repair was $62.1{\pm}13.9 min$ and this was $137.5{\pm}7.2 min$ for the patients who underwent a Bentall operation with transaortic mitral repair. Conclusion: For selected patients without significant mitral organic disease, transaortic mitral valve commissuroplasty combined with aortic valve replacement or a Bentall operation may be a feasible, effective method without adding significant aortic cross clamping time and more cardiotomy.

• Journal of Intelligence and Information Systems
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• v.17 no.3
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• pp.187-201
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• 2011

KOSPI200 index is the Korean stock price index consisting of actively traded 200 stocks in the Korean stock market. Its base value of 100 was set on January 3, 1990. The Korea Exchange (KRX) developed derivatives markets on the KOSPI200 index. KOSPI200 index futures market, introduced in 1996, has become one of the most actively traded indexes markets in the world. Traders can make profit by entering a long position on the KOSPI200 index futures contract if the KOSPI200 index will rise in the future. Likewise, they can make profit by entering a short position if the KOSPI200 index will decline in the future. Basically, KOSPI200 index futures trading is a short-term zero-sum game and therefore most futures traders are using technical indicators. Advanced traders make stable profits by using system trading technique, also known as algorithm trading. Algorithm trading uses computer programs for receiving real-time stock market data, analyzing stock price movements with various technical indicators and automatically entering trading orders such as timing, price or quantity of the order without any human intervention. Recent studies have shown the usefulness of artificial intelligent systems in forecasting stock prices or investment risk. KOSPI200 index data is numerical time-series data which is a sequence of data points measured at successive uniform time intervals such as minute, day, week or month. KOSPI200 index futures traders use technical analysis to find out some patterns on the time-series chart. Although there are many technical indicators, their results indicate the market states among bull, bear and flat. Most strategies based on technical analysis are divided into trend following strategy and non-trend following strategy. Both strategies decide the market states based on the patterns of the KOSPI200 index time-series data. This goes well with Markov model (MM). Everybody knows that the next price is upper or lower than the last price or similar to the last price, and knows that the next price is influenced by the last price. However, nobody knows the exact status of the next price whether it goes up or down or flat. So, hidden Markov model (HMM) is better fitted than MM. HMM is divided into discrete HMM (DHMM) and continuous HMM (CHMM). The only difference between DHMM and CHMM is in their representation of state probabilities. DHMM uses discrete probability density function and CHMM uses continuous probability density function such as Gaussian Mixture Model. KOSPI200 index values are real number and these follow a continuous probability density function, so CHMM is proper than DHMM for the KOSPI200 index. In this paper, we present an artificial intelligent trading system based on CHMM for the KOSPI200 index futures system traders. Traders have experienced on technical trading for the KOSPI200 index futures market ever since the introduction of the KOSPI200 index futures market. They have applied many strategies to make profit in trading the KOSPI200 index futures. Some strategies are based on technical indicators such as moving averages or stochastics, and others are based on candlestick patterns such as three outside up, three outside down, harami or doji star. We show a trading system of moving average cross strategy based on CHMM, and we compare it to a traditional algorithmic trading system. We set the parameter values of moving averages at common values used by market practitioners. Empirical results are presented to compare the simulation performance with the traditional algorithmic trading system using long-term daily KOSPI200 index data of more than 20 years. Our suggested trading system shows higher trading performance than naive system trading.

• Radiation Oncology Journal
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• v.22 no.4
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• pp.265-270
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• 2004

Purpose: To evaluate the effectiveness of postoperative radiation therapy in cervical cancer patients and define the prognostic factors to affect survival rates. Materials and Methods: Eighty one patients with cervical cancer who were treated with postoperative radiation therapy following surgery at our institution between May 1992 and April 2000 were retrospectivelv analyzed. Forty two patients had stage IB disease, 17 had stage IIA disease, and remaining 22 had stage IIB disease, respectively. Histological examination revealed 76 squamous cell carcinoma and 5 adenocarclnoma. Sixty one patients were noted to have stromal invasion greater than 8 mm and 20 patients were noted to have stromal invasion 7 mm or less. Sixteen patients had parametrial invasion and 65 patients did not. Positive vaginal resection margin was documented in only eight patients and positive lymphovascular invasion was in twelve patients. All of the patients were treated with external beam radiation therapy alone. Majority of the patients were treated with 4 field brick technique to encompass whole pelvis. Total of 5,500 cGy was delivered to the primary surgical tumor bed. Minimum follow up period was four years. Results: Actuarial disease free survival rates for entire group of the patients were 95% and 89% at 2 and 5 years, respectively Five year disease free survival rates for patients with stage IB, IIA, and IIB disease were 97%, 87% and 70%, respectivelv. Local recurrences were documented in 5 patients. Cumulative local failure rate at 3 years was 6% Five year disease free survival rates for patients with stromal invasion greater than 8 mm and 7 mm or less were 88% and 92%, respectively (p>0.05). Five year disease free survival rate for patients with parametrial invasion was significantly lower than those with no invasion (72% vs 92%, p<0.05). Also there was significantly lower survival in patients with positive vaginal resection margin, compared with patients with negative resection margin (64% vs 94%, p<0.05). However, lymphovascular invasion was not a statistically significant prognostic factor Parametrial invasion and positive surgical resection margins were noted to be significant prognostic factors. Conclusions: Postoperative radiation therapy appears to be beneficial in controlling local disease in cervical cancer patients with high pathologic risk factors. Parametrial invasion and positive resection margins were noted to be significant prognostic factors to affect survival and more effective treatment should be investigated in these patients.

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.261-272
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• 2023

In recent years, natural disasters such as heavy rainfall and typhoons have occurred more frequently, and their severity has increased due to climate change. The Korea Meteorological Administration (KMA) currently uses the same criteria for all regions in Korea for watch and warning based on the maximum cumulative rainfall with durations of 3-hour and 12-hour to reduce damage. However, KMA's criteria do not consider the regional characteristics of damages caused by heavy rainfall and typhoon events. In this regard, it is necessary to develop new criteria considering regional characteristics of damage and cumulative rainfalls in durations, establishing four stages: blue, yellow, orange, and red. A classification model, called DSCM (Disaster Severity Classification Model), for the four-stage disaster severity was developed using four machine learning models (Decision Tree, Support Vector Machine, Random Forest, and XGBoost). This study applied DSCM to local governments of Seoul, Incheon, and Gyeonggi Province province. To develop DSCM, we used data on rainfall, cumulative rainfall, maximum rainfalls for durations of 3-hour and 12-hour, and antecedent rainfall as independent variables, and a 4-class damage scale for heavy rain damage and typhoon damage for each local government as dependent variables. As a result, the Decision Tree model had the highest accuracy with an F1-Score of 0.56. We believe that this developed DSCM can help identify disaster risk at each stage and contribute to reducing damage through efficient disaster management for local governments based on specific events.