• Journal of Welding and Joining
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• v.33 no.4
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• pp.30-36
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• 2015

Austenite stainless steel(SA213-TP347H) has widely been used for the superheater & reheater tube in USC(ultra-supercritica) coal boiler because of its high creep rupture strength and anti-oxidation. But recently, the short-term failures have happened frequently in heat affected zone for only 4,000~15,000hours of service. Many investigations have been conducted to understand the failure mechanism. The root cause of failure was comfirmed to "strain induce participation hardening crack" or "reheat cracking". This mechanism often occurred due to weld residual stress and precipitation of the Cr, Nb carbides in the stabilized stainless steel such as TP347H. This paper presents an analysis of failure tube and effect of the sample tubes that conducting stabilizing heat treatment in site after 11,380hours & 16,961hours of service. Visual inspection was performed. In addition, microscopic characteristics was identified by O.M, SEM, and hardness test was carried out to find out the heat treatment effects. Failures seem to happen because of being not conducted stabilizing heat treatment in site. And another cause is inadequate weld parameter such as pass, ampere, voltage, inter-pass temperature. Thus, this paper has the purpose to describe that how to prevent similar failures in those weld-joints.

• Journal of the Korean Wood Science and Technology
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• v.19 no.3
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• pp.62-71
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• 1991

An evaluation of bending test of composite I and Box beams for determining the ultimate strength limit design criteria was presented. Maxium loads of composite I beams were found in beams composed of thicker upper flanges and/or vertical LVL flanges. These loads of plywood web beams were greater than those of PB web beams. Maximum loads of unsymmetrical box beams were less than those of symmetrical box beams. Thus, it took on different phase in box type beams. Ultimate loads of composite beams were greater than those of solid. The failure of composite beams were abrupt and failure mode was classified into following categories; Edgewise shear failure in web, delamination in flange-web joint, tension failure and tearing in LVL flanges, and web delamination. These failures of composite beams were appeared at the mixed mode. The influence factor affecting the performance of tested composite beams was shear strength of PB-web composite beams and compressive strength in plywood-web composite beams. It was also assumed that the influence factors on structural performance on composite beams were flange quality, web material and geometry of cross section. As one of the design methods resisting to compressive stress that was required in the case of small span to depth ratio and deep beams. composite I-beams composed of thicker upper flanges comparing to lower flanges were very effective in structural performance.

• The Journal of the Korean bone and joint tumor society
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• v.2 no.1
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• pp.38-46
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• 1996

The traditional methodology in Ewing's sarcoma was chemotherapy and radiotherapy. Recently surgery is reemerging as an important therapeutic tool and some paper report increased survival with it. The purpose of this nonrandomized study is to evaluate our result of Ewing's sarcoma with surgery, retrospectively. We experienced 30 cases for seven years and among them 6 were extraskeletal. In location, axial was 10 cases and peripheral was 20. By Enneking's classification, state IIB was 26 cases and IIIB was 4. Eighteen patients took operation, chemotherapy and/or radiotherapy, and remaining twelve took chemotherapy and/or radiotherapy only. Type of operation was limb salvage in 16 cases and amputation 2. Average dosage of radiation was 45.1Gy. Six kinds of chemotherapeutic regimen were used, but among them main protocols were Ifosfamide-Adriamycin(17 cases) and IESS(Cytoxan, Adriamycin, Methotrexate, Vincristine:8 cases). Complications were as follows. In operation group, there were 3 local recurrence and one case of nonunion. In nonoperated group, one local recurrence and one pancytopenia resulting in death. Average follow up was 29.7 months. Kaplan-Meier's ten year actuarial survival rate for the whole 30 cases was 26.8%. Significant difference in survival exists between central and peripheral lesions(p=0.05, by log rank test). Types of chemotherapy and surgery itself showed no significance. But surgery is important in function and local control. More intensive chemotherapeutic regimen to prevent distant metastasis and combined surgery and radiotherapy may be needed in Ewing's sarcoma.

• The Journal of the Korean bone and joint tumor society
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• v.2 no.1
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• pp.72-77
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• 1996

Metastaic bone tumors are usually accompanied with severe pain. The treatment modalities for this pain are so variable that patients are sometimes afraid of using them. Salmon calcitonin has a function to increase beta-endorphines followed by increasing the blood level of prostaglandin and thromboxan A2, which results in analgesic effect. This drug also has been known to decrease bone resorption. There were a few reports that parenteral use of salmon calcitonin decrease the pain from metastatic bone tumor. We wanted to know the effectiveness and tolerability of nasal spray of salmon calcitonin in relieving bone pain with metastatic tumor. We analyzed the effectiveness in the aspects of pain, sleep, performance status, mobility, supplementary analgesic use. The biologic effect of salmon calcitonin was analysed with CBC, Ca/P, BUN/Cr, uric acid. Simple radiography, alkaline phosphatase, osteocalcin, pyrilink-K were used as parameters for bone change. Eighteen cases of metastatic bone tumors took nasal spray of salmon calcitonin($Miacalcic^{(R)}$, 200IU/day) for 4 weeks, to relieve bone pain. With Wilcoxon Matched-Pairs Signed Ranks Test, we could find pain decreased significantly at 3 week and mobility become improved at 4 week of salmon calcitonin use. Other parameters didn't show any significant changes. We think the analgesic effect is mainly due to effect not on the local bone lesion but on the central nervous system, and that increased dose of salmon calcitonin can induce earlier and stronger analgesic effect.

• The Journal of the Korean bone and joint tumor society
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• v.5 no.1
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• pp.44-50
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• 1999

Neurilemmoma is a benign encapsulated nerve sheath tumor originated from peripheral nerve. Previously its preoperative diagnosis had mainly depended on the history, physical examination, electrodiagnostic test, ultrasonography, bone scan. But only with these diagnostic modalities, exact preoperative diagnosis was nearly impossible. Therefore operation was performed under the impression of lipoma or just simple soft tissue tumor. Recently, the advent of magnetic resonance imaging(MRI) has made it easier to diagnose neurilemoma before surgery. MRI also helps to determine the extent of lesion and operative procedures. We performed marginal excision in 24 cases, evaluated those cases with respect to the sex, age, location, chief complaint, duration of illness, preoperative diagnosis, involved nerve, imaging studies, size of mass, complication, duration of follow-up and report with review of the literature.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.2
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• pp.69-77
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• 2009

The experiment was carried out to investigate lateral retrofitting effects by FRP and BRB (Buckling-Restrained Brace) for beam-column elements. These results were utilized to establish an analytical model using commercial nonlinear analysis software, PERFORM3D. Concrete and steel analytical models previously proposed by several scholars were adopted for this analytical study. A proposed analysis model showed reasonable accuracy compared with the test results on the beam-column elements strengthened FRP sheets and BRB, as well as with the non-strengthened element subjected to lateral cyclic loadings. Subsequently, the proposed modeling technique for nonlinear analysis would be helpful for preliminary analyses for retrofitting structures, by enabling engineers to estimate the improved capacity of retrofitted structural elements before performing construction.

• The Korean Journal of Applied Statistics
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• v.21 no.2
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• pp.327-340
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• 2008

This paper derives joint and conditional Lagrange multiplier tests based on information matrix for testing functional form and/or the presence of autocorrelation in a regression model. Small sample properties of these tests are assessed by Monte Carlo study and comparisons are made with LM tests based on Hessian matrix. The results show that the proposed $LM_E$ tests have the most appropriate finite sample performance.

• Journal of the Korea Convergence Society
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• v.5 no.1
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• pp.1-8
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• 2014

The purpose of this paper was to evaluate the fatigue life to apply the vibration fatigue analysis considering the stiffness change of the spot welding due to fatigue damage accumulation. For this, the mechanical and fatigue properties of base and spot welded standard specimens were obtained through the tensile and constant amplitude fatigue test. The transfer function of the spot-welded structure was obtained from the frequency response analysis and fatigue analyisis was performed under the condition of PSD=0.11. A vibration fatigue analysis that considered changes in the frequency response due to the fatigue damage that is, failure of some wleding point was conducted on spot-welded structure. The fatigue life of the spot-welded structure was determined by combining the transfer function, the S-N curve of the tensile-shear spot-welded joint and the input PSD.

• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.35-41
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• 2011

Recently, as large structures, which should support large design loads have been constructed, the study on the large diameter composite pile becomes necessary. The large diameter composite pile has the diameter over 700mm and consists of two parts of the upper steel pipe pile and the lower PHC pile by a mechanical joint. In this research, to analyze the bearing capacity and the material strength of the composite pile, three dimensional numerical analyses were performed. First, the numerical modeling method was verified by comparing the calculated load-movement curves of the pile with those of the field pile load tests. Then, a total of twelve analyses were performed by varying pile diameter and loading direction for three pile types of PHC, steel pipe and composite piles. The results showed that the vertical and the horizontal load-movement curves of the composite pile were identical with those of the steel pipe pile and the horizontal material strength of the composite pile was 60-80% larger than that of the PHC pile.

• 대한공업교육학회지
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• v.34 no.2
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• pp.363-378
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• 2009

The objective of the paper is to design and produce a walking robot such as humanoid robot under the given design requirements and constraints. An approach to design and produce walking robot with 2 legs was suggested. It is walking robot of 5 joints which have both of ankles, both of knee joint, and pelvis. It has 5 degrees of freedom and moves by only rotations. We review the key points before the design of the walking robot. The walking robot is consisted of 2 portions : motor and frame, control board. Final goal is to walk stably and if it detects and cognizes a special object, the walking robot avoids it and moves in other direction. The walking robot was made according to design procedures and tested by proposed algorithms. The running test was successful under given 4 modes. The findings of this research could think kinds of technologies concurrently and approach synthetically through process of design and production.