• The Journal of Korean Academy of Prosthodontics
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• v.46 no.1
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• pp.42-52
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• 2008

Purpose: Resonance Frequency Analysis(RFA) technique can be used as an effective method in measuring the implant stability and documenting the clinical results. This technique also determines how stable the implant is before performing a prosthetic practice. Having become one the guidelines of the implant therapy whose final objective is the immediate loading, the $Osstell^{TM}$ mentor is giving a lot of information to the clinicians recently. In this communication, experiments were performed to investigate how reliable the measured ISQ values by $Osstell^{TM}$ mentor are, and to see if those are also stable even after sterilization. As five objectives: 1) How stable measured ISQ values after fixation $Smartpeg^{TM}s$ for 400 times. 2) How stable measured ISQ values after 'attach-detach'$Smartpeg^{TM}'s$ for 400 times. 3) How stable measured ISQ values after clinical sterilization methods. 4) How stable measured ISQ values after repeatedly sterilization in autoclave for 10 times. 5) What is the critical temperature which is lost the magnetism of $Smartpeg^{TM}$. Materials and Methods: Clinical sterilization methods(Autoclave sterilization, Dentistar sterilization, Ultra violet sterilization, Vacuum dry unit sterilization, Boiling water sterilization, combined $H_{2}O_{2}$ and Alcohol sterilization).$Smartpeg^{TM}s$. D3 Block bone($3{\times}9{\times}2cm$). Osstem implant(${\emptyset}4.1$-10mm).$Osstell^{TM}$ mentor. Individual experiment was used 8 number of $Smartpeg^{TM}s$ and they had measured to ISQ values of before experiment and after experiment. Results: 1. The measured ISQ values did not change after fixation $Smartpeg^{TM}s$ for 400 times. 2. There was no significant changes in the measured ISQ values of 'attach-detach $Smartpeg^{TM}s'$ for 400 times. 3. The measured ISQ values did not change after the usual clinical sterilization methods. 4. The measured ISQ values did not change after sterilization in autoclave for 10 times. 5. It was impossible to exactly measure the critical temperature which is lost the magnetism of $Smartpeg^{TM}s$. But, the results was resulted to lost its magnetism in higher temperature than $150^{\circ}C$/10 minute. Conclusion: The measured ISQ values showed insignificant differences in case of no changes in the magnetism of the $Smartpeg^{TM}s$. It seems that the $Smartpeg^{TM}s$ can be used repeatedly in every measurement if the original magnetisms of the $Smartpeg^{TM}s$ can be recognized. There seems to be no significant changes in the measured ISQ values of 'attach-detach $Smartpeg^{TM}s'$ only if the screw pitches were unimpaired. The clinical sterilization methods seems acceptable because the result was resulted to lost its magnetism in higher temperature than $150^{\circ}C$/10minute.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.175-190
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• 1994

In order to get fundamental information for prediction of landslide hazard, both forest and site factors affecting slope stability were investigated in many areas of active landslides. Twelve descriptors were identified and quantified to develop the prediction model by multivariate statistical analysis. The main results obtained could be summarized as follows : The main factors influencing a large scale of landslide were shown in order of precipitation, age group of forest trees, altitude, soil texture, slope gradient, position of slope, vegetation, stream order, vertical slope, bed rock, soil depth and aspect. According to partial correlation coefficient, it was shown in order of age group of forest trees, precipitation, soil texture, bed rock, slope gradient, position of slope, altitude, vertical slope, stream order, vegetation, soil depth and aspect. The main factors influencing a landslide occurrence were shown in order of age group of forest trees, altitude, soil texture, slope gradient, precipitation, vertical slope, stream order, bed rock and soil depth. Two prediction models were developed by magnitude and frequency of landslide. Particularly, a prediction method by magnitude of landslide was changed the score for the convenience of use. If the total store of the various factors mark over 9.1636, it is evaluated as a very dangerous area. The mean score of landslide and non-landslide group was 0.1977 and -0.1977, and variance was 0.1100 and 0.1250, respectively. The boundary value between the two groups related to slope stability was -0.02, and its predicted rate of discrimination was 73%. In the score range of the degree of landslide hazard based on the boundary value of discrimination, class A was 0.3132 over, class B was 0.3132 to -0.1050, class C was -0.1050 to -0.4196, class D was -0.4195 below. The rank of landslide hazard could be divided into classes A, B, C and D by the boundary value. In the number of slope, class A was 68, class B was 115, class C was 65, and class D was 52. The rate of landslide occurrence in class A and class B was shown at the hige prediction of 83%. Therefore, dangerous areas selected by the prediction method of landslide could be mapped for land-use planning and criterion of disaster district. And also, it could be applied to an administration index for disaster prevention.

• Journal of Internet Computing and Services
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• v.16 no.1
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• pp.67-74
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• 2015

In recent years, frequent itemset mining for considering the importance of each item has been intensively studied as one of important issues in the data mining field. According to strategies utilizing the item importance, itemset mining approaches for discovering itemsets based on the item importance are classified as follows: weighted frequent itemset mining, frequent itemset mining using transactional weights, and utility itemset mining. In this paper, we perform empirical analysis with respect to frequent itemset mining algorithms based on transactional weights. The mining algorithms compute transactional weights by utilizing the weight for each item in large databases. In addition, these algorithms discover weighted frequent itemsets on the basis of the item frequency and weight of each transaction. Consequently, we can see the importance of a certain transaction through the database analysis because the weight for the transaction has higher value if it contains many items with high values. We not only analyze the advantages and disadvantages but also compare the performance of the most famous algorithms in the frequent itemset mining field based on the transactional weights. As a representative of the frequent itemset mining using transactional weights, WIS introduces the concept and strategies of transactional weights. In addition, there are various other state-of-the-art algorithms, WIT-FWIs, WIT-FWIs-MODIFY, and WIT-FWIs-DIFF, for extracting itemsets with the weight information. To efficiently conduct processes for mining weighted frequent itemsets, three algorithms use the special Lattice-like data structure, called WIT-tree. The algorithms do not need to an additional database scanning operation after the construction of WIT-tree is finished since each node of WIT-tree has item information such as item and transaction IDs. In particular, the traditional algorithms conduct a number of database scanning operations to mine weighted itemsets, whereas the algorithms based on WIT-tree solve the overhead problem that can occur in the mining processes by reading databases only one time. Additionally, the algorithms use the technique for generating each new itemset of length N+1 on the basis of two different itemsets of length N. To discover new weighted itemsets, WIT-FWIs performs the itemset combination processes by using the information of transactions that contain all the itemsets. WIT-FWIs-MODIFY has a unique feature decreasing operations for calculating the frequency of the new itemset. WIT-FWIs-DIFF utilizes a technique using the difference of two itemsets. To compare and analyze the performance of the algorithms in various environments, we use real datasets of two types (i.e., dense and sparse) in terms of the runtime and maximum memory usage. Moreover, a scalability test is conducted to evaluate the stability for each algorithm when the size of a database is changed. As a result, WIT-FWIs and WIT-FWIs-MODIFY show the best performance in the dense dataset, and in sparse dataset, WIT-FWI-DIFF has mining efficiency better than the other algorithms. Compared to the algorithms using WIT-tree, WIS based on the Apriori technique has the worst efficiency because it requires a large number of computations more than the others on average.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.37-44
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• 2013

In study suggested clinical availability to shoulder forced traction method in term of quality of image, the patient's convenience and stability, according to whether to use of shoulder forced traction bend using computed tomography(CT) that X-ray calibration and various mathematic calibration algorithm application can be applied by AEC. To achieve this, 79 patients is complaining of cervical pain oriented that shoulder forced traction bend use the before and after acquires lateral projection scout image and transverse image. transverse image of a fixed size in concern field of pixel and figure the average HU value compare that quantitative analysis. Artifact and pixel and resolution to qualitative clinical estimation image analysis. the patient feel inconvenience degree that self-diagnosis survey that estimate. As a result, lateral projection scout image if you used shoulder forced traction bend for the depicted has been an increase in the number of a cervical vertebrae. transverse image concern field shoulder forced traction bend use the before and after for pixel and the average HU-value changes was judged to be almost irrelevant. Artifact and resolution and contrast, in qualitative analysis of the results relating the observer to the unusual result. So, the patients of 82.27% complained discomfort that use of shoulder forced traction bend in self-diagnosis survey. No merit of medical image by using of bend from result was analyzed quality of image to quantitative and qualitative method judged. Nowadays, CT is supplied possible revision of quality of radiation by reduction of slice and automatic exposure controller, etc and application of preconditioning filter process due to various mathematic revision algorithm. So, image noise by beam hardening artifact should not be a problem. shoulder forced traction bend of use no longer judged clinically availability because have not influence of image quality and give discomfort, have extra dangerousness.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.305-312
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• 2014

Purpose : The purpose of this study is to analyze the mechanical and leaf speed accuracy of the dynamic multileaf collimator (DMLC) and determine the appropriate period of quality assurance (QA). Materials and Methods : The quality assurance of the DMLC equipped with Millennium 120 leaves has been performed total 92 times from January 2012 to June 2014. The the accuracy of leaf position and isocenter coincidence for MLC were checked using the graph paper and Gafchromic EBT film, respectively. The stability of leaf speed was verified using a test file requiring the leaves to reach maximum leaf speed during the gantry rotation. At the end of every leaf speed QA, dynamic dynalog files created by MLC controller were analyzed using dynalog file viewer software. This file concludes the information about the planned versus actual position for all leaves and provides error RMS (root-mean square) for individual leaf deviations and error histogram for all leaf deviations. In this study, the data obtained from the leaf speed QA were used to screen the performance degradation of leaf speed and determine the need for motor replacement. Results : The leaf position accuracy and isocenteric coincidence of MLC was observed within a tolerance range recommanded from TG-142 reports. Total number of motor replacement were 56 motors over whole QA period. For all motors replaced from QA, gradually increased patterns of error RMS values were much more than suddenly increased patterns of error RMS values. Average error RMS values of gradually and suddenly increased patterns were 0.298 cm and 0.273 cm, respectively. However, The average error RMS values were within 0.35 cm recommended by the vendor, motors were replaced according to the criteria of no counts with misplacement > 1 cm. On average, motor replacement for gradually increased patterns of error RMS values 22 days. 28 motors were replaced regardless of the leaf speed QA. Conclusion : This study performed the periodic MLC QA for analyzing the mechanical and leaf speed accuracy of the dynamic multileaf collimator (DMLC). The leaf position accuracy and isocenteric coincidence showed whthin of MLC evaluation is observed within the tolerance value recommanded by TG-142 report. Based on the result obtained from leaf speed QA, we have concluded that QA protocol of leaf speed for DMLC was performed at least bimonthly in order to screen the performance of leaf speed. The periodic QA protocol can help to ensure for delivering accurate IMRT treatment to patients maintaining the performance of leaf speed.

• Journal of forensic and investigative science
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• v.2 no.2
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• pp.21-29
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• 2007

News from the media on sexual assaults to children committed by natural fathers doesn't attract social attention any more. The number of crimes related to Child Sexual Assault(CSA) is increasing every year in spite of the "Special Act on Prevention of Sexual Assault in Korea". The YoungNam District Sunflower Center for prevention of Child Sexual Assaults(SC-CSA) was established in Daegu, June 2005. The YoungNam District SC-CSA provides forensic evaluation of physical evidence, medical and psychological treatment for the victims less than 13 years of sexual assaults simultaneously. This study carried out 36 cases of CSA by kin reported to YoungNam District SC-CSA, among 180 cases in total until December 2006 since its opening. Most of the victims were girls (32 cases). 28 cases (78%) were indecent assaults (78%) and 8 cases (22%) were rapes. The assailants were overwhelmingly males (35 cases). The assailants of 21 cases (58.3%) were identified as the victims' natural fathers. The incident locations were victim's residence (31 cases, 86.1%) and the victims had been sexually assaulted regularly for many years (25 cases, 69.4%). Considering the above research, we can conclude that CSA committed by kin has specific characteristics. CSA is not a one-time incident, but consistently occurring crime. However, in 22 cases (61.1%), the victim's guardian didn't want to report about it or punish the assailants. As the assailants were natural fathers or relatives of the victims, the other family members probably thought it might be shameful to reveal their wrong doings and would lead to defamation of their family's reputation. The SC-CSA provides the counseling and medical treatment to the victims with the consent of the parents. Due to the guardians' misjudgment, the incident is sometimes not reported to the police. By not reporting the incident to the police, the assailant freely commits other crimes, which multiplies victims. The legal Act of supporting the management of the SC-CSA is still not regulated, so the stability of the SC-CSA is not guaranteed, yet. Even though it is obligatory to report incidents to the police, some cases are still not reported. Currently, there are three SC-CSA centers : in Seoul, in Daegu, and in Gwangju. More centers need to be established to diminish CSA cases in Korea.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.47-61
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• 2004

Although the purpose of orthodontic treatment is to increase the function and esthetics of the jaws along with increasing stability, there are many side effects during the treatment itself, such as root resorption and alveolar bone resorption. Such resorption of the apical root Is unpredictable, and may even proceed into the dentin layer. Once the process has begun, it is irreversible. By evaluating the effect of many oral habits, especially that of nail biting, in correlation with the root and the periodontal tissues, the appropriate biomechanics for orthodontic treatment can be taken into consideration, along with the possibility of root resorption and alveolar bone loss during orthodontic treatment, and any legal problems that might occur. Among the male and female patients of the ages $10\~15$ without skeletal deformity, 63 were chosen as the experiment group with known nail biting habits at time of examination, and within the same age group without nail biting habits as the control. After the orthodontic treatment, number of the experiment group was 31 and the control group was 22. The periapical radiographies of anterior teeth were taken and the assesment of the root length and alveolar bone level were taken before(T1) and after(T2) the orthodontic treatment. The results from this study were as follows : 1. Before the orthodontic treatment, average crown-to-root ratio of the experimental group showed noticeably high values in 4 maxillary incisors and mandibular right central incisor. 2. Before the orthodontic treatment, comparing the root length, maxillary and mandibular right central incisors and both mandibular incisors had a smaller value in the experimental group. 3. Before the orthodontic treatment, comparing and evaluating the alveolar bone loss measured from the cemento-enamel junction to the alveolar bone crest, some crestal bone of the experiment group showed greater loss than the control. 4. After the orthodontic treatment, there was shortening of the root length and loss of the crestal bone in both groups. 5. After the orthodontic treatment, the changes of C/R ratio and the shortening of root length were significantly high in the experimental group. 6. After the orthodontic treatment, the level of alveolar crestal bone showed greater loss in the experimental group.

• 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 Korean Public Health Nursing
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• v.3 no.2
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• pp.47-76
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• 1989

The objectives of this study was to analyze the major causes of decreasing utilization rate of health care institutios in pilot-project area of regional medical insurance, Kwang-hwa and Kun-wi country. After the implementation of medical insurance, utilization rate of health institutions turned out' to be lower than it was estimated, when the pilot-project of regional medical insurance was planned. It might be due to changes in inhabitant's behavioral attitude toward medical insurance. So this study was made to find measures for financial stability by increasing utilization rate of health care institutions and to be available for basic demand-supply program of medical care. The hypothesis of this study was as follows; First. there is difference in understanding health care institutions between Kun-wi and Kwang-hwa. Second. respondesnts of inquiry survey have exact knowledge of their past experience of treatment taken prior to enforcement of medical insurance, Questionaire survey was made as to each 700 household among total 11, 884 households in Kun-wi and 20,919 households in Kwang-hwa. In case of Kun-wi, 70% of inquired households (491) gave their answers. In Kwang-hwa, the number was 560 households (80% of inquireds). Dollected data was processed and analyzed by way of using SPSS batch system. To evaluate facto rs distribution aspects of data and to make comparison between two area, percentage and $X^2$ distribution were applied. The results were as follows; L The utilization rate of health care institutions in Kun-wi and Kwang-hwa was lower than it was estimated. when pilot-project of medical insurance was planned. 2. Prior to the implementation of medical insurance. inhabitants in two area chose the medical institutions considering such factors. First was medical care fee cheap. second in habitant's residence, Third was the institutions conveniently easy of access. 3. After the implementation of medical insurance. 26.1% of inqurieds in Kun-wi and 41.6% in Kwang-hwa, changed medical institutions. In case of Kwn-wi, from health care institution (p 0.05), and in case of Kwang-hwa, vice versa, from general medical institutions to health care institutions. 4. Evaluation by factors were made such as follows. Inquired gave high marks to following facts: In case of Kun-wi, general medical institutions were difficult of access and relation between patients: was not friendly, but burden of medical expenditure was light. Effects of treatment and facilities was good. In case of Kwang-hwa, inquired gave high evaluation marks to the follow ing facts; facilities of medical institutions was not good, but the burden of medical expenditure was light. 5. After the implementation of medical insurance, the services was evaluated as good, but inquired hopec for lessening the burden of medical expenditure. 6. In case of exact understanding of cost-sharing, the evaluation rate in Kwang-hwa was higher than that of Kun-wi (p < 0.005). And positive attitude toward necessity of medical insurance was also good in Kwang-hwa (p < 0.05). 7. In case of inquired's attitude toward medical institutions, Kwang-hwa showed positive response (p < 0.05) 8. In the case of comparison between general medical institution and health care institution, two area showed similar positive response; medical manpower, facilities of medical institutions and effest: of treatement was good. 9. In comprehensive evaluation of benefit-service; the general medical institution's positiveness was higher than that of health care institutions in Kun-wi. But in Kwang-hwa vice-versa. 10. If the medical expenditure of general medical institution and health care institutions was equal 77% of inquireds in Kun-wi and 59.1% in Kwang-hwa answered that they chose general medical insurance. Considering results above mentioned, the conclusion of this study was made as follows. 1. In Kwang-hwa county, where the understanding of health care institutions's was good, the utilization's of health care institutions was shown high. Therefore, in case of Kwang-hwa, betterment: should be made to induce increasing utilization rate for negative factors of health care institutions. 2. In case of Kun-wi, where the understanding of health care institutions was on the decrease, measures for changing such negative factors should be taken by way of strengthening public relations. And cases of Kwang-hwa should also be studied. 3. On the side of financial stabilization and establishing health care delivery system, primary health care should be available. Therefore, the major cause of inhabitant's avoiding health care institutions should be known. And measures for activating that institutions have to be taken. So, the facilities of health care institution have to be improved up to the level of clinic. And supportive measures for securing equipment and improving health care services should also be taken. It is necessary that strategy for public relations should be employed with policy considerations and supports.

• Journal of Intelligence and Information Systems
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• v.20 no.4
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• pp.121-139
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• 2014

Predicting corporate failure has been an important topic in accounting and finance. The costs associated with bankruptcy are high, so the accuracy of bankruptcy prediction is greatly important for financial institutions. Lots of researchers have dealt with the topic associated with bankruptcy prediction in the past three decades. The current research attempts to use ensemble models for improving the performance of bankruptcy prediction. Ensemble classification is to combine individually trained classifiers in order to gain more accurate prediction than individual models. Ensemble techniques are shown to be very useful for improving the generalization ability of the classifier. Bagging is the most commonly used methods for constructing ensemble classifiers. In bagging, the different training data subsets are randomly drawn with replacement from the original training dataset. Base classifiers are trained on the different bootstrap samples. Instance selection is to select critical instances while deleting and removing irrelevant and harmful instances from the original set. Instance selection and bagging are quite well known in data mining. However, few studies have dealt with the integration of instance selection and bagging. This study proposes an improved bagging ensemble based on instance selection using genetic algorithms (GA) for improving the performance of SVM. GA is an efficient optimization procedure based on the theory of natural selection and evolution. GA uses the idea of survival of the fittest by progressively accepting better solutions to the problems. GA searches by maintaining a population of solutions from which better solutions are created rather than making incremental changes to a single solution to the problem. The initial solution population is generated randomly and evolves into the next generation by genetic operators such as selection, crossover and mutation. The solutions coded by strings are evaluated by the fitness function. The proposed model consists of two phases: GA based Instance Selection and Instance based Bagging. In the first phase, GA is used to select optimal instance subset that is used as input data of bagging model. In this study, the chromosome is encoded as a form of binary string for the instance subset. In this phase, the population size was set to 100 while maximum number of generations was set to 150. We set the crossover rate and mutation rate to 0.7 and 0.1 respectively. We used the prediction accuracy of model as the fitness function of GA. SVM model is trained on training data set using the selected instance subset. The prediction accuracy of SVM model over test data set is used as fitness value in order to avoid overfitting. In the second phase, we used the optimal instance subset selected in the first phase as input data of bagging model. We used SVM model as base classifier for bagging ensemble. The majority voting scheme was used as a combining method in this study. This study applies the proposed model to the bankruptcy prediction problem using a real data set from Korean companies. The research data used in this study contains 1832 externally non-audited firms which filed for bankruptcy (916 cases) and non-bankruptcy (916 cases). Financial ratios categorized as stability, profitability, growth, activity and cash flow were investigated through literature review and basic statistical methods and we selected 8 financial ratios as the final input variables. We separated the whole data into three subsets as training, test and validation data set. In this study, we compared the proposed model with several comparative models including the simple individual SVM model, the simple bagging model and the instance selection based SVM model. The McNemar tests were used to examine whether the proposed model significantly outperforms the other models. The experimental results show that the proposed model outperforms the other models.