• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
• /
• pp.501-508
• /
• 2001

Free vibration analysis of multi-delaminated composite beam-columns subjected to axial compression load is performed in the present study. In order to investigate the effects of multi-delaminations on the natural frequency and elastic buckling load of multi-delaminated beam-columns, the general kinematic continuity conditions are derived from the assumption of constant slope and curvature at the multi-delamination tip. Characteristic equation of multi-delaminated beam-column is obtained by dividing the global multi-delaminated beam-columns into segments and by imposing recurrence relation from the continuity conditions on each sub-beam-column. The natural frequency and elastic buckling load of multi-delaminated beam-columns according to the incremental load of axial compression, which is limited to the maximum elastic buckling load of sound laminated beam-column, are obtained. It is found that the sizes, locations and numbers of multi-delaminations have significant effect on natural frequency and elastic buckling load, especially the latter ones.

• 대한수학회논문집
• /
• 제38권2호
• /
• pp.341-354
• /
• 2023

In this article, an alternating Fibonacci sequence is defined from a second-order linear homogeneous recurrence relation with constant coefficients. Then, the determinant, inverse, and eigenvalues of the circulant matrices with entries in the first row having the formation of the sequence are formulated explicitly in a simple way. In this study, the method for deriving the formulation of the determinant and inverse is simply using traditional elementary row or column operations. For the eigenvalues, the known formulation from the case of general circulant matrices is simplified by considering the specialty of the sequence and using cyclic group properties. We also propose algorithms for the formulation to show how efficient the computations are.

• Journal of Advanced Research in Ocean Engineering
• /
• 제1권3호
• /
• pp.157-167
• /
• 2015

In order to provide simple and accurate wave theory in design of offshore structure, an analytical approximation is introduced in this paper. The solution is limited to flat bottom having a constant water depth. Water is considered as inviscid, incompressible and irrotational. The solution satisfies the continuity equation, bottom boundary condition and non-linear kinematic free surface boundary condition exactly. Error for dynamic condition is quite small. The solution is suitable in description of breaking waves. The solution is presented with closed form and dispersion relation is also presented with closed form. In the last century, there have been two main approaches to the nonlinear problems. One of these is perturbation method. Stokes wave and Cnoidal wave are based on the method. The other is numerical method. Dean's stream function theory is based on the method. In this paper, power series method was considered. The power series method can be applied to certain nonlinear differential equations (initial value problems). The series coefficients are specified by a nonlinear recurrence inherited from the differential equation. Because the non-linear wave problem is a boundary value problem, the power series method cannot be applied to the problem in general. But finite number of coefficients is necessary to describe the wave profile, truncated power series is enough. Therefore the power series method can be applied to the problem. In this case, the series coefficients are specified by a set of equations instead of recurrence. By using the set of equations, the nonlinear wave problem has been solved in this paper.

• 대한두경부종양학회지
• /
• 제16권2호
• /
• pp.161-166
• /
• 2000

Objective: The nm23 gene has been identified as a potential metastasis suppressor gene in various human neoplasms. Both Bcl-2, which promotes cell survival, and Bax, which promotes cell death, have been considered as major factors in controlling the apoptotic pathway. This study was carried out to determine whether these markers are useful in distinguishing potential intrinsic differences in tumor virulence of papillary thyroid cancers. Material and Method: The expressions of nm23, Bcl-2 and Bax have been evaluated using immunohistochemical techniques in 100 pure papillary thyroid cancers and 20 metastatic lymphnodes. The intensity of immnunoreactivity was graded on arbitrary four point scale(grade 0 or 1 : negative reactivity, grade 2 or 3 positive reactivity). The immunoreactivities were analyzed in relation to TNM atage, AMES score, local recurrence and distant metastasis, and that of metastatic LNs was compared with the tumors. Results: The expression of Bcl-2 and bax did not show any statistical differences by TNM stage, AMES score, recurrence, distant metastasis and also between the tumor and metastatic LN. However, the nm23 showed higher expression of Ki67 in distant metastasis than in control group and in metastatic LNs than in the tumors(p<0.05). Conclusion: Although the expression of Bcl-2 and Bax protein showed no correlation with clinical parameters representing tumor virulence, the nm23 expression could be an useful prognostic factor, especially in predicting nodal or distant metastasis in papillary thyroid cancer.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제17권4호
• /
• pp.415-428
• /
• 1995

The author studied on the 115 cases of the ameloblastoma which had been diagnosed with biopsy during the period of 1962 to 1994 at the Kyungpook National University Hospital, Pusan National University Hospital, Youngnam University Hospital, Keimyung University Hospital, Catholic Medical School Hospital, and Maryknol Hospital. This study contains the statistical analysis of the clinico-pathological findings such as sex, age, location, chief complaint, duration,treatment method, size, recurrence and impacted teeth in relation to radiographic findings. The results were as follows : 1. The incidence rate was 60% in male and 40% in female. 2. At the time of diagnosis, the age of the patients ranged from 9 to 69 years old (average 31.4 years old). The cases of 73% were in the 2nd, 3rd and 4th decades of life. 3. The majority of cases, 88.7% occurred in the mandible, especially 59% in the mandibular angle area. 4. The most prevalent chief complaint of swelling was 56.5%. 5. As regards duration, the cases less than 12 months appeared 49.5%, and average duration is 30.45months. 6. Unilocular radiographic findings showed 43.5%, Multilocular radiographic findings appeared 56.5%. 7. Conservative treatment was performed 40.0%, and radical treatment was employed 60.0%. 8. There was the variation of lesional sizes between 2.0cm and 15cm, average size 6.19cm. 9. Recurrent cases were 28.7%, and impacted teeth were shown 30.43%. 10. The radiographic finding has no relationship with the factors of age, location, chief complaint, recurrence and impacted teeth, however there is slight indication that the below 30-year-old patient tend to be related to the multilocular type. 11. The multilocular radiographic findings were shown more frequently in the groups of females, over average of 30.45 months, over average size of 6.19cm and radical treatment.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제33권2호
• /
• pp.94-102
• /
• 2007

The ameloblastoma is a common odontogenic tumor of the jaw bone and represents approximately 1% of tumor in the jaw. However, it might be able to infiltrate into the adjacent tissue, causing bony destruction and high recurrent rate. In this study, expression of RANKL and OPG in ameloblastoma in relation to age and gender of patient and recurrence, location of the lesion were examined through immunohistochemisry study. The RANKL and OPG antibody staining were used. The obtained result were as follow. 1. Positive immunoreactivity to RANKL/OPG in all specimens was found. 2. 1n recurrenc, location of ameloblastoma and age, gender of patients using immunohistochemical expression of RANKL. There was not significant difference. 3. 1n recurrence, location of ameloblastoma and age, gender of patients using immunohistochemical expression of OPG. There was not significant difference. In summary, it is suggested that activation of osteoclasts by RANKL is an important mechanism by which ameloblastomas cause bone destruction.

• 대한두경부종양학회지
• /
• 제13권2호
• /
• pp.187-199
• /
• 1997

Thyroid carcinoma ranks low in incidence and as a cause of death when compared to carcinomas arising in the other site. With adequate surgical treatment, the prognosis of operable thyroid carcinoma is good. However, the extent of surgical resection in treatment of thyroid cancer remains still controversy. The aim of this study was to assess the results of thyroid cancer patients treated surgically and to analyze the prognostic factors affecting survival and to improve the survival rate. We retrospectively analyzed the outcome of a total of 278 thyroid cancer patients treated surgically at Inje University Paik Hospital from 1980 to 1995 and followed for 1 to 16 years. There were man in 47 and woman in 231 patients with age range of 14 to 79 years(mean 42 years). Histopathologic findings were papillary carcinoma in 233, follicular carcinoma in 33, mixed carcinoma in 7, medullary carcinoma in 2, and undifferentiated carcinoma in 3 patients, respectively. Operative procedures were unilateral lobectomy in 111, subtotal thyroidectomy in 100, and total thyroidectomy in 67 patients. Central node dissection was performed in 92, modified neck disseciton in 62, radical neck dissection in 28, and no node dissection in 96 patients. Thyroid hormone was administered for the period of 3 to 5 years to suppress endogenous TSH production. Overall 5-year survival rate according to Kaplan-Meier method was 91.1%. Independently, significant factors affecting the prognosis were age at diagnosis, tumor size, pathologic type, tumor stage, lymph node metastasis, angioinvasion, extrathyroidal extension, and 'risk' group category. but, the prognosis were not influenced by sex and capsular invasion. Patients at low risk or with small size carcinomas had long survival over 5 years with only lobectomy. Lymph node dissection was carried out with a limited type in no jugular metastasis, radical neck dissection was performed only therapeutically in proved jugular node metastasis. Fifteen patients were dead of tumor recurrence after surviving for three months to two and half years, and the cause of death was local recurrence in nine, bone metastasis in four and lung metastasis in two patients. In conclusion, more extensive surgery including total thyroidecotmy and systematic compartment-oriented dissection of the lymph node metastases in patient at high-risk group will results in better survival and lower recurrence rate.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제29권1호
• /
• pp.26-34
• /
• 2003

Intraoral Vertical Ramus Osteotomy,along with Sagittal Split Ramus Osteotomy,is an popular surgical technique performed on mandibular prognathism. However Intraoral Vertical Ramus Osteotomy has been suspected for an initial mobilization at the healing phase of segment because it does not employ the rigid fixation between segments. To execute a study on the healing phase of segment after Intraoral Vertical Ramus Osteotomy on the horizontal plane, 102 patients (204 parts) who were diagnosed mandibular prognathism and took Intraoral Vertical Ramus Osteotomy at the Yonsei University dental hospital were observed during the period of before operation, immediately postoperation, 1 month, 3 months, 6 months, and 12 months. The change in the width of segment and horizontal angle of proximal segment and condylar head on the Submentovertex Cephalogram taken from those patients represented following results. 1. The width of proximal and distal segment decreased with the lapse of time. It decreased into 84.5% between immediate postoperative and 6M and even continued to decrease till 12M. 2. The horizontal angle of the proximal segment did medial rotation according as the lapse of time and rigorously continued till 3M. The rotation angle of condylar head indicated its tendency of recurrence to the original position but the entire recurrence was not allowed. The bigger an initial angle was, the higher was the tendency of recurrence after the operation while the rotation angle remained still bigger. 3. After grouping into group 1, group 2,and group 3 based on the extent of the variation of rotation angle of condylar head at immediate postoperative, the variation of rotation angle was measures in each group. The result presented that the initial rotation angle of condylar head had correlation with that of proximal segment but had no relation with the extent of setback of the mandible. However a quantitative analysis alone is not a sufficient method for analyzing the healing phase of segment on the horizontal plane.Therefore a multilateral analysis using 3 dimensional data such as CT is recommendable for the future study.

• 한국안전학회지
• /
• 제34권6호
• /
• pp.76-87
• /
• 2019

This study was conducted to check the cabin crew's safety perception in relation to the airline's safety climate and cabin crew's safety action and to verify that the safety perception's mediation effects. The results of the study confirmed that all three factors of the safety climate have a significant impact on safety perception, and among them, safety practice is the most significant. Accordingly, Airlines need to establish a community that enables real-time information exchange for air accidents so that the cabin crew can present real-time examples of safety-related accidents. In addition, it will be necessary to work with external safety agencies to form an active attitude for the establishment of safety procedures in order to prevent recurrence of safety problems while considering the causes of such incidents internally in the event of an airline safety accident. In addition, it was confirmed that safety training was the most significant factor to safety action, among which all three elements of the safety climate had a significant effect on safety action. Therefore, airlines need to expand practical training on aircraft to full-scale safety training to build an immediate resolution for cabin crews in the event of an air accident. In addition, safety training should be established to encourage collaboration among aviation safety-related personnel to participate in safety training together to address aviation safety from a diverse point of view. Safety perception was has a significant effect on safe action. Therefore, airlines should reinforce the airline's safety management system by checking the status of the cabin crew's safety perception extending the level of punishment to the scope of retirement or disqualification to establish a firm awareness of safety. Finally, the safety perception has demonstrated partial mediation effects in relation to the safety climate and safety action. Therefore, the airline needs to improve the duties of the cabin crew that interferes with cabin safety duties. In addition, airlines should utilize advertisements emphasizing that safety is first.

• 한국치위생학회지
• /
• 제6권4호
• /
• pp.387-402
• /
• 2006

This research carried out a survey for 569 students in a junior college of jeollanamdo to provide a needful basic data in developing suitable health promotion program and creating a direction of the oral hygiene education process to intial adult population after holding the oral cavity health action and a affecting factors to it. A collected data obtained the following conclusion. According to school grade, a difference of action factor is Chi-square and Pearson's correlation coeficient in actionfactor and acknowledgement-perception factor and a step-by-step recurrence analysis processed a related factor of the oral health action. 1. A related action factor of the oral health appeared meaningful difference of the oral cavity medical examination, the oral cavity clean device use or not, dental surgery prevention cure or not among the third grade who had the most experience of the oral hygiene education within one year recently. 2. A significant of the oral cavity health acknowledged and perceived and a concern of the oral cavity health, acknowledged the oral cavity health state distribution are the highest in the third grade. 3. According to monthly income, a large income is higher than a small income about self-effects in a relation between the oral cavity health action and acknowledgement-perception factor. the average of a large income is 30.59(${\pm}5.79$). The obstacle of the oral cavity health action is 12.51(${\pm}3.19$). a large income is highest. according to school career, under middle school layer obtained the highest average 16.33(${\pm}3.53$). according to a school year, acknowledge-perception factor of the oral cavity health control of the third grade is the highest(38.81(${\pm}6.25$). 4. In mutual relation between acknowledge-perception factor and the oral cavity health action, a variable constants of meaningful mutual relation are the oral cavity health perception, self-effects, the oral cavity health action obstacle, the oral cavity health action benefit, the oral health action control, aggressive. and they are self-effects, the oral cavity health action in the oral cavity health perception. A significant of the oral cavity health and the oral cavity health action obstacle are the oral cavity health action benefit and the oral cavity health action control. 5. The affecting factors to the oral health action are self-effects, action factor, acknowledged the oral health control.