• Proceedings of the KSR Conference
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• 2005.11a
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• pp.318-325
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• 2005

In present, KTX's wheel is worn inevitably according to the interaction with rail in service. It was analyzed by wearing type, damage type and wheel reprofiling cycle on the running surface. As a result, damage on the running surface is main cause to reprofile the wheel. Wearing type of wheel is normal and it hasn't reprofiled according to normal wheel wear. As a follow-up result of the whee] defects on the running surface, if the defects size is well managed by periodical inspection, it would be efficient to increase the wheel life.

• Journal of Chest Surgery
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• v.38 no.10 s.255
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• pp.693-698
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• 2005

Background: Sinus valsalva aneurysm (SVA) is a rare disease, and it is frequently accompanied by ventricular septal defect and aortic valve regurgitaion. For treatment of SVA, several surgical mordalities were applied, but there was no report on the long-term result after surgical repair in Korea. We reviewed our 28 years of experiences and analyzed the long-term results after treatment of sinus valsalva aneurysm with or without rupture. Material and Method: Between March 1974 and February 2002, 81 patients were operated under the impression of sinus valvsalva aneurysm or sinus valsalva aneurym rupture. Retrospectively we reviewed the patients' record. Mean age of patients was $29.2\pm11.5$ and there were 49 males. Accompanyng diseases were as follows: VSD in 50, PDA in 2, Behcet's disease in 2, TOF in 1, RVOTO in 1, AAE in 1. Seventy-seven $(95\%)$ patients had sinus valsalva rupture and in 14 patients, subacute bacterial endocarditis was accompanied. Degree of aortic valve regurgitation was as follows: grade I: 8, II: 10, III: 9, IV: 4. Most common rupture site was right coronary sinus (66 patients, $81\%$) and most common communication site was right ventricle (53 patients). In repair of sinus valsalva rupture, patch was used in 37 patients, and direct suture was done in 38 patients. Result: There was one surgical death $(1.2\%)$. Follow up was done in 78 patients $(97.5\%)$, mean follow up period was $123.3\pm80.9(3\~330\;months)$. During the follow up period, 3 patients died $(3.8\%)$. One patient died of heart failure, another patient died of arrhythmia and the other one died of unknown cause. In two patients, complete atrio-ventricular block was developed during follow up period, and there was no operation related event or complication. Kaplan-Meier survival analysis revealed $92.5\pm3.5\%$ survival at 15 and 27 years and it seems to be satisfactory. Conclusion: Long-term surgical results and survival is satisfactory after repair of sinus valsalva aneurysm with or without rupture.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.6
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• pp.201-214
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• 2023

This study attempted to analyze the impact of individual entrepreneurial capabilities on entrepreneurial intention targeting small and medium-sized business employees, and sought to confirm the mediating effect of entrepreneurial efficacy and entrepreneurial mentoring between entrepreneurial capabilities and entrepreneurial intention. The sub-variables of entrepreneurship competency were analyzed separately into creativity, problem solving, communication, and marketing. 368 questionnaires collected from employees at small and medium-sized manufacturing companies located across the country were used for empirical analysis. A parallel dual mediation model with no causal relationship between parameters was used for empirical analysis using SPSS v26.0 and PROCESS macro v4.2. As a result of the analysis, first, among the start-up competencies, creativity, communication, and marketing were confirmed to have a significant positive (+) effect on start-up efficacy. Second, among the start-up competencies, creativity, communication, and marketing were tested to have a significant positive influence on start-up mentoring. Third, both startup efficacy and startup mentoring were found to have a significant positive influence on startup intention. Fourth, among start-up capabilities, creativity and marketing were confirmed to have a significant positive (+) effect on start-up intention. Fifth, startup efficacy and startup mentoring were found to have a mediating effect on startup intention except for problem solving among startup competencies. As a result, it was confirmed that in order to strengthen the intention to start a business among small and medium-sized business employees, start-up efficacy and start-up mentoring are important factors, and that marketing and creativity have an important influence among individual start-up capabilities, so education and prior preparation for these are necessary. As follow-up research, it will be necessary to apply multivariate models, analyze time series data, research considering external environmental factors, and test the difference between start-up capabilities and performance considering detailed population characteristics.

• Journal of Chest Surgery
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• v.42 no.3
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• pp.317-323
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• 2009

Background: Although high efficiency of conversion into sinus rhythm has been demonstrated after performing the Cox-Maze procedure in patients with atrial fibrillation associated with mitral valve disease, the changes in the mechanical function and size of the left atrium have not been determined. The aim of the study was to evaluate the effect of the Maze procedure on the left atrial size and contractile transport function. Material and Method: From July 1997 to July 2008, 647 consecutive patients were operated on for chronic atrial fibrillation associated with mitral valve disease. Among these, 211 patients that (1) were able to be followed up for 2 years after surgery, (2) had sustained normal sinus rhythm, regardless of whether they were taking anti-arrhythmic medications and (3) did not have valvular regurgitation greater than grade III or they did not have moderate grade valvular stenosis were selected for evaluation. The left atrial size and contractile transport function were assessed by transthoracic echocardiography at the postoperative base line (1 year) and at regular follow-up periods (2 years, 3 years, 4 years and 6 year). Result: The left atrial dimension was increased and the contractile transport function was decreased during the follow-up period. The longer the follow-up period, the greater was the statistical significance of the left atrial size increase and contractile transport function decrease. Conclusion: In patients who sustain normal sinus rhythm conversion after a Maze III procedure with a mitral valve operation, there is a gradual increase of the left atrial dimensions and a decrease of contractile transport function during the follow-up period. Therefore, scrupulous follow-up is needed for these patients.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.156-165
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• 1997

In the practical control systems, the dynamic range of actuatiors is limited(or saturated) when actuators are driven by sufficiently large signals. This gives rise to a nonlinearity as a result of actuator saturation. For example, the upper limit is imposed on productive capability by available factory space and capital equipment. Other examples of those kinds of actuator saturations are a maximum torque of the actua- ting motors and a throttle position in an aircraft speed control A saturating actuator may lead not only to a large overshoot during start-up and shut-down, but also to deterioration of the performance due to the uncertainties. That is, the speed of response is decreased and, possibly, the system output may not follow the lalrge reference inputs. The large-overshoot may be accompanied by rest wind-up(or called by integra- tor wind-up) which comes from controllers with integral action in saturation operation regions. Eventually, as the overshoot increases, the system has a limit cycle or becomes oscillatorily unstable. Due to these cir- cumstances, many studies are focused on the stability and robustness of the nonlinear systems with satu- rating actuator in the time-domain as well as in the frequency-domain.

• Korean Journal of Human Ecology
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• v.18 no.2
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• pp.419-429
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• 2009

The purpose of this study was to research the preference for the entertainers image and imitation behavior. The research was a survey and the subjects were 1,034 middle and high school students. The collected data was analyzed using frequency, statistics analysis, t-test, crosstab, ANOVA, factor analysis and multiple regression analysis. Result were as follows; The preference for the entertainment, most of the adolescents loved the singer and the TV talent. The feminine and urban image was their favorite image for the entertainer. The favorite image was significantly different according to the gender and age. Star entertainer imitation behaviors showed the differences according as adolescent's gender and age. The unique marketing strategy is required as the job in the entertainment business, so the tend to follow up and imitate all attractive factors and favorite image of the entertainer. This study was for helping the adolescent who are very sensitive and going to set up their identification to get the role model as the fair way to be the social member, helping the one to set up the image-making way for each entertainment's job, and helping the enterprise who want to use the image of the star in their promotion.

• Journal of Educational Research in Mathematics
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• v.8 no.2
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• pp.709-722
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• 1998

This thesis is to see if the classes using problem posing is effective to improve the students' grades in math. So I set up research subjects as follow. 1. Do the classes focused on problem posing have any influence on the students' achievement\ulcorner 2. Do the classes focused on problem posing have any different influence on the students' achievement according to their levels\ulcorner 3. Do the classes focused on problem posing have any different influence on the students' achievement according to the categories in math\ulcorner I close four classes in the first grade of K middle school in Kangnung, Kangwon province for this thesis. First I divided them into two groups. Each group consisted of two classes. One is the experimental group. The other is the comparative group. The experimental group was taken classes using problem posing. The comparative group was taken classes by the traditional teaching method. And then I analyzed the difference of the achievement between two groups. As a result of this research, I came to the conclusion as follow. First, the classes focused on problem posing is more effective than traditional teaching method for the improvement of the students` achievement Second, both the classes using problem posing and the traditional teaching method doesn`t affect to the advanced students. Third, the classes using problem posing is more effective to the intermediate students and lower level students than the traditional teaching method. Especially it is very effective in teaching the students the linear equation.

• Journal of Korean Foot and Ankle Society
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• v.12 no.1
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• pp.74-79
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• 2008

Purpose: In this study, we introduced an newly developed technique of operation for fracture of lateral malleolus of the ankle. We treated the fracture by close reduction and internal fixation using arthroscopy. Materials and Methods: From July 2006 to June 2007, we had treated 23 cases of lateral malleolar fracture (SER type) by closed reduction and internal fixation with arthroscopy and followed them up more six month. Operation time, union time, clinical and functional result were evaluated. Results: After the final follow-up, all the fractures were healed with satisfactory bony union. The subjective result was excellent in 15 cases (65%), good in 8 cases (35%), the objective result was excellent in 13 cases (57%), good in 10 cases (43%), and the roentgenographic result was excellent in 17 cases (74%), good in 6 cases (26%). Conclusion: Closed reduction and internal fixation with arthroscopy technique is an effective treatment method in treating lateral malleolar fracture of the ankle since it offers advantages including corrective anatomical reduction and minimizing complication associated with injury of soft tissue.

• Journal of Chest Surgery
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• v.41 no.3
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• pp.305-312
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• 2008

Background: Anatomic and functional abnormalities of the systemic atrioventricular (AV) valve are common in single ventricle. pathologies and continue to be associated with poor early and late outcomes in surgically palliated single. ventricle patients. We aggressively performed valvuloplasty for atrioventricular valve regurgitation (AVVR) during the course toward a Fontan operation. Material and Method: Between January 1995 and December 2004, 209 patients underwent a Fontan operation in our institution. We retrospectively evaluated the prevalence of AVVR and the influence of AV valve repair on outcome, and we analyzed the progression of AVVR after the Fontan operation for 168 patients where echocardiographic follow up results for more than 6 months after the Fontan operation were available. During the course toward a Fontan operation, 25 patients underwent 30 procedures for AVVR. These procedures. were. carried out during placement of a bidirectional cavopulmonary shunt (BCPS) for nine patients, between the time of placement of a BCPS and the Fontan operation for four patients, and during the Fontan operation for 17 patients. Five patients underwent procedures for AVVR twice. Result: The late mortality rate after the Fontan operation was 4.2% (n=7), with a median follow-up duration of 52 months (range, $6{\sim}123$ months). Seven patients (4%) had unfavorable outcomes such as significant (moderate or severe) AVVR in six patients, and significant AV valve stenosis in one patient was determined at the last follow up after the Fontan operation. Among the seven patients, four patients underwent AV valve repair after the Fontan operation, and one patient underwent subsequent AV valve replacement. Progression to AVVR of equal to or greater than grade 2 was noted in 30 patients (18%) at the last follow up after the Fontan operation, including 12 patients that underwent previous AV valve procedures. Initial grading of AVVR, a previous AV valve operation, and specific AV valve morphology such as a common AV valve or mitral atresia were significant risk factors for the progression of AVVR after the Fontan operation. Conclusion: In our surgical series, a small percentage of patients showed unfavorable outcomes. related to AVVR during the course toward a Fontan operation. However, a closer follow-up is required to evaluate the progression of the AVVR after a Fontan operation, especially for patients showing poor AV valve function at the first presentation and specific AV valve morphology.

• Journal of the Korean Arthroscopy Society
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• v.12 no.2
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• pp.107-111
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• 2008

Purpose: To evaluate the clinical and radiographical results of arthroscopic meniscectomy in patients aged over 50 with minimum 3-year follow-up. Materials and Methods: Of the patients who had undergone arthroscopic meniscectomies between Dec. 1997 and Dec. 2003, 36 patients(36 knees) were available for retrospective evaluation. The average age at the time of surgery was 56.4 years and the mean follow-up period was 63 months. According to the Kellgren-Lawrence classification, grade I change were noted in 16 patients, II in 12, III in 6 and IV in 2. According to Outerbridge classification, grade I articular lesions were noted in 16 patients, II in 10, III in 7 and IV in 3. Postoperative Lysholm score, patient s subjective satisfaction and radiographic changes were evaluated retrospectively. Results: Twenty-four patients(66.7%) were good or excellent for the Lysholm score and 26 patients(72.2%) were satisfied at final follow-up. Tibiofemoral angle was changes from mean valgus 3.9 degrees to mean valgus 2.6 degrees and 22 patients(61.1%) showed the progression of osteoarthritic changes. Conclusion: The satisfactory results could be obtained in 72.2% of patients aged over 50 with a minimal follow-up of 3 years after arthroscopic meniscectomy. The results tended to be worse in patients with moderate or severe tibiofemoral osteoarthritic changes or with articular cartilage lesions.