• Journal of Intelligence and Information Systems
• /
• v.7 no.1
• /
• pp.63-79
• /
• 2001

Data Envelopment Analysis(DEA), a non-parametric productivity analysis tool, has become an accepted approach for assessing efficiency in a wide range of fields. Despite of its extensive applications and merits, some features of DEA remain bothersome. DEA offers no guideline about to which direction relatively inefficient DMUs improve since a reference set of an inefficient DMU, several efficient DMUs, hardly provides a stepwise path for improving the efficiency of the inefficient DMU. In this paper, we aim to show that DEA can be used to evaluate the efficiency of life insurance companies while overcoming its limitation with the aids of machine learning methods.

• Journal of KIISE:Software and Applications
• /
• v.41 no.8
• /
• pp.598-604
• /
• 2014

In this paper, we develop stepwise regression data envelopment model to select important variables. We formulate null hypothesis to understand the importance of each variable and use Kruskal-Wallis test for this purpose. If the Kruskal-Wallis test does reject the null hypothesis this will imply there is significant fluctuation in the efficiency score relative to base model. And therefore we have to further check the pair of variables that causes the fluctuation in order to determine its importance using Conover-Inman test. The proposed models helps understand the extent of misclassification decision making units as efficient/inefficient when variables are retained or discarded alongside provides useful managerial prescription to make improvement strategies.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.46 no.2
• /
• pp.139-146
• /
• 2019

This study aimed to analyze the association of midpalatal suture (MPS) maturation stages with skeletal maturation and age and to obtain references for establishing a treatment plan for rapid maxillary expansion (RME). Cone-Beam Computed Tomography (CBCT) images from 480 children (240 boys, 240 girls) aged 7 - 15 years were obtained. MPS maturation stages and cervical vertebral maturation indicator (CVMI) were evaluated, and the correlations between MPS maturation stages, CVMI, and age were determined using the Spearman's correlation test. The positive likelihood ratio (LHR) of CVMI for MPS maturation stages was calculated. MPS maturation stages and CVMI showed a strong correlation. Especially, CVMI 1 - 3 showed positive LHR greater than 10 for the diagnosis of stages A - C. MPS maturation stages and age were correlated strongly in girls and moderately in boys. Conventional RME produces the most favorable skeletal effect at CVMI 1 - 3 or those up to 12 years of age and fewer skeletal effects at CVMI 4 or at 13 years of age in girls and 13 - 15 years in boys. It is recommended to evaluate MPS maturation stages using CBCT before RME application at CVMI 5, 6 or at 14, 15 years of age in girls.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.48 no.1
• /
• pp.31-41
• /
• 2021

The aim of this retrospective study was to evaluate the correlation between the midpalatal suture maturation and skeletal maturation in growing children aged 7 - 15 years and predict the maturational stages of the midpalatal suture corresponding to skeletal maturity assessed by the skeletal maturation indicators (SMI) and middle phalanx of the third finger (MP3) stages. The group of this retrospective study was consisted of randomly selected 132 male and 135 female in age from 7 - 15 years. The maturation of the midpalatal suture was evaluated by using images from cone-beam computed tomography (CBCT) while the skeletal age was assessed by hand-wrist radiography. CBCT images and hand-wrist radiographs used in this study were obtained from all subjects for orthodontic diagnosis before orthodontic treatment. The maturational stages of the midpalatal suture showed strong correlations with both SMI and MP3 stages. The correlation between the midpalatal suture maturation and SMI (Spearman's correlation coefficient, ϒ_S = 0.905, p < 0.05) was slightly greater than that of MP3 stages (ϒ_S = 0.830, p < 0.05). There was a positive significant correlation between the midpalatal suture maturation and chronological age (ϒ_S = 0.868,p < 0.05). CBCT for evaluation of the midpalatal suture maturational stages may be unnecessary in every pediatric patients because SMI and MP3 stages were both replaceable useful methods for assessing maturation of the midpalatal suture before orthopedic treatment. In this retrospective study, the diagnostic reliability of the SMI method for estimating midpalatal suture maturation showed better reliability than the MP3 method.

• Journal of Digital Convergence
• /
• v.11 no.8
• /
• pp.219-225
• /
• 2013

The purpose of this study was to retrospectively investigate the contributing factors in facial soft tissue injuries among children. A record-based analysis was carried out on 126 patients with facial lacerations who visited I hospital in the dept of plastic surgery from April 2010 to May 2011. Through all age group showed a significant difference in incidence rate for male and female.(p<.05). Overall, 49% of injuries occurred outdoors and the most frequent cause of injury was slip-down (42%), followed by being struck (40%). In general, the frequency of injuries peaked summer(30.2%) and increased between 12pm and 4pm. 105 patients (83.3%) arrived at the emergency room within an hour. The forehead(26%) was the most commonly injured area. The depth of soft tissue injuries was mostly subcutaneous(54%), and 1~2cm was the length of injury with the highest incidence(46%). Most children (40%) needed local anesthesia and only 4 children (1.53%) suffered associated fractures. Facial injuries require special attention because of their potential threat in inducing permanent scar or disfigurement. For the safety of children, the preventive measures to reduce facial soft tissue injuries must be improved.

• Journal of Gastric Cancer
• /
• v.9 no.2
• /
• pp.57-62
• /
• 2009

Purpose: The use of automatic circular staplers for gastroduodenostomy after distal gastrectomy is now widely accepted. We compared the clinical outcomes of two different methods. Materials and Methods: Between March 2005 and February 2008, 134 patients with gastric cancer underwent distal gastrectomies. Seventy-six consecutive patients received end-to-side gastroduodenostomies (ES) between March 2005 and September 2006. The remaining 58 consecutive patients received end-to-end gastroduodenostomies (EE) between November 2006 and February 2008. We analyzed the surgical outcomes between the two groups (ES versus EE) on the basis of prospectively collected data. Results: Among the clinical factors, there were no differences between the two groups. The overall complication rates were 19.7% in the ES group and 13.8% in the EE group (P=0.489). With respect to anastomosis-related complications, 2 cases had bleeding and 2 cases had stenoses in the ES group, while 2 cases in the EE group had bleeding. Re-operation was needed in the case of intraluminal bleeding in the ES group. There were no mortalities in our study. Conclusion: The two methods for gastroduodenostomy were safe and technically feasible. Although there was no statistical difference in the overall complications, including anastomosis-related complications, we demonstrated better outcomes with respect to anastomotic stenosis in the EE group.

• Journal of the Korean earth science society
• /
• v.25 no.7
• /
• pp.615-628
• /
• 2004

In order to elucidate seasonal sedimentary characteristics and depositional environment after construction of seawall on macrotidal flat, a seasonal observations of surface sediments (total 450) and sedimentation rates on 4 transects have been investigated for 2 years. The eastern area of Iwon tidal flat, has been changed from semi-closed coast to open coast by construction of seawall, shows general seasonal changes similar to characteristics of open coast type, which represented both fining and bad sorted distribution due to deposition of fine sediments under low energy condition in the summer, and relatively coarser and better sorted distribution because of erosion of fine sediments in the winter. In considering angles of transects, distribution patterns of surface sediments, the northern and southern parts of eastern tidal flat are dominantly influenced by wave and tidal effects, respectively. As time goes by, the eastern tidal flat shows coarsening-trend of surface sediments caused by direct effect of tidal current, were and typhoon. Meanwhile the western area of seawall, which has been re-formed by construction seawall, is sheltered from northwesterly seasonal wind. The seasonal change pattern of western area of seawall is slightly different from that of eastern tidal flat. Mean grain size and sorting of surface sediments during spring is finer and worse than those during summer. This seasonal change pattern maybe influenced by topographic effects caused from the construction of seawall. In consideration of all result, the transport of fine sediments in the study area, which is supplied to limited sediments, shows clockwise circulation pattern that fine sediments are transported from the eastern tidal flat to the western area of seawall because of blocking of seawall in the winter and are transported reversed direction the summer. As a result, many changes have been observed in the study area after construction of seawall; however, this change is still in progress and is expected to need continuous monitoring.

• The korean journal of orthodontics
• /
• v.29 no.3 s.74
• /
• pp.361-374
• /
• 1999

Intraoral filled type of orthodontic appliance can cause reversible or irreversible damages such as gingivitis, periodontitis, enamel decalcification, dental caries, root resorption, and pulpal changes. Such adverse effects are brought by increase in dental plaque as well as oral flora. Such an increase causes gingival inflammation and enamel decalcification. The purpose of this study is to get klowledge on initial changes in dental plaque, gingivitis, and enamel decalcification after bonding fixed orthodontic appliances according to time flow, gender, and sides(right/left) of premolar region. For control group, 48 students of dental college, Yonsei university(26 males, 22 females) were chosen; for experimental group, 73 orthodontic patients(36 males, 37 females) who will be treated with fixed appliances were chosen. All the subjects had no systemic disease, juvenile periodontitis and all the females had passed their ,menarche. Tooth brushing instruction was given to all the subjects prior to the experiment. For control group, plaque index, gingival index, and decalcification index were measured twice at 3 weeks interval ; for experimental group, the same was done prior to, 3, 6, 9 weeks after bonding fixed appliances. The following results were obtained: 1. In plaque index 3 weeks after placement of appliances, and it showed gradual increase afterwards. 2. In gingival index3 weeks after placement of appliances, and afterwards it showed increase at a faster rate than plaque index. 3. Enamel decalcification began to show between 3 and 6 weeks after bonding fixed appliances. Decalcification index began to increase 6 weeks after appliance placement, but there was no statistical significance. 4. When the comparison was made between two sides of premolar region, the right side showed greater index in plaque and gingival index of experimental group.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.42 no.1
• /
• pp.38-44
• /
• 2015

Children commonly experience orofacial injuries and often need emergency treatment. Due to fear and anxiety, children tend to be uncooperative in emergency rooms. Ketamine hydrochloride is a well-known sedative agent at medical-based emergency rooms which has been used for procedural sedation. In this paper, we will discuss the sedation of uncooperative young patients, who needed dental treatments in the emergency room at Wonju Severance Christian Hospital, using ketamine. We collected the records of patients under 18-years-old who visited the emergency room for dental treatment from January 2010 to May 2014. The data was categorized by age, sex, required dental treatments and application of ketamine sedation. Among 659 pediatric patients who visited for emergency dental treatments, 118 patients were treated under sedation using ketamine. Majority of patients were under the age of 6 (110 patients), and the most frequent cause of sedation was suture of oral laceration (105 patients). Though ketamine should not be used by dentists alone, dentists in emergency rooms can easily meet the patients under deep sedation using ketamine. Hence, dentists in emergency rooms need to be aware of the clinical effects, considerations, and potential adverse effects of ketamine.

• Journal of Chest Surgery
• /
• v.34 no.12
• /
• pp.901-908
• /
• 2001

Background : Coronary artery bypass graft(CABG) in patients with advanced left ventricular dysfunction has often been regarded as having high mortality rate, despite the great improvement in operative result of CABG. With recent advances in surgical technique and myocardial protection, surgical revascularization improved the symptom and long-term survival of these high risk patients more than the medical conservative treatment. Material and Methold : Clinical data of 31(4.1％) patients with preoperative ejection fraction less than 30% among 864 CABGs performed between January 1995 and March 1999 were retrospectively analyzed and pre- and postoperative changes of the ejection fraction on echocardiography were analyzed. There were 26 men and 5 women. The mean age was 60.7 years(range 41 to 72 years). History of myocardial infarction(30 cases, 98％) was the most common preoperative risk factor. There were seven irreversible myocardial infarction on thallium scan. Most patients had triple vessel diseases(26 cases, 84％) and first degree of Rentrop classification(16 cases, 52％) on coronary angiography. The mean number of distal anastomosis during CABG was per patient was 4.9${\pm}$0.8 sites in each patient. In addition to long saphenous veins, the internal mammary artery was used in 20 patients. Total bypass time was 244.7${\pm}$3.7 minutes(range, 117 to 567 minutes), and mean aortic cross-clamp time was 77.9 ${\pm}$ 1.6 minutes(range, 30 to 178 minutes). There were five other reparative procedures such as two left ventricular aneurysrmectomy, two mitral repair, and one aortic valve replacement. There were twelve postoperative complications such as three cardiac arrhythmia, two bleeding(re-operation), one delayed sternal closure, eleven usage of intra-aortic balloon counterpulsation for low cardiac output. Two patients died, postoperative mortality was 6.5% . Twenty-nine patients were relieved of chest pain and left ventricular ejection fraction after operation was significantly higher(38.5${\pm}$11.6%, p 0.001) as compared with preoperative left ventricular ejection fraction(25.3${\pm}$2.3%). The follow up period of out patient was 25. 3 months. Conclusion: In patients with coronary artery disease and advanced left ventricular dysfunction, coronary artery bypass grafting can be performed relatively safely with improvement in left ventricular function, but it will be necessary to study long term results.