• Korean Journal of Computational Design and Engineering
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• v.17 no.2
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• pp.97-110
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• 2012

High performance sensors and modern data logging technology with real-time telemetry facilitate system fault diagnosis in a very precise manner. Fault detection, isolation and identification in fault diagnosis systems are typical steps to analyze the root cause of failures. This systematic failure analysis provides not only useful clues to rectify the abnormal behaviors of a system, but also key information to redesign the current system for retrofit. The main barriers to effective failure analysis are: (i) the gathered data (event) logs are too large in general, and further (ii) they usually contain noise and redundant data that make precise analysis difficult. This paper therefore applies suitable pre-processing techniques to data reduction and feature extraction, and then converts the reduced data log into a new format of event sequence information. Finally the event sequence information is decoded to investigate the correlation between specific event patterns and various system faults. The efficiency of the developed pre-filtering procedure is examined with a terminal box data log of a marine diesel engine.

• Geotechnical Engineering
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• v.4 no.3
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• pp.43-52
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• 1988

The behavior of clays subjected to Repeated loading has been shown to be very different from the behavior under a single load application. Especially the behavior of pore water pressure is Qf considerable importance. The objective of this work is to experimentally study the stress-strain characteristics of clays, and this study includes the pore water pressure which is built up during the load repetition. For this study, the samples were consolidated isotropically in the triaxial cell during 24 hours, .and monotonic strain controlled triaxial test is carried out by uslng the tests of Compression failure, Cycled at failure, and Nonfailure equilibrium on remoulded samples under undrained .condition . Consequently there exists a critical level of repeated loading which seperates the behavior of a particular sample into two distinctly different patterns.

• Journal of Applied Reliability
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• v.12 no.2
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• pp.67-78
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• 2012

An electric double-layer capacitor(EDLC) is an electrochemical capacitor with relatively high energy density, typically hundreds of times greater than conventional electrolytic capacitors. EDLCs are widely used for energy storage rather than as general-purpose circuit components. They have a variety of commercial applications, notably in energy smoothing and momentary-load devices, and energy-storage and kinetic energy recovery system devices used in vehicles, etc. This paper presents an accelerated degradation test of an EDLC with rated voltage 2.7V, capacitance 100F, and usage temperature $-40^{\circ}C{\sim}65^{\circ}C$. The EDLCs are tested at $50^{\circ}C$, $60^{\circ}C$, and $70^{\circ}C$, respectively for 1,750hours, and their capacitances are measured at predetermined times by constant current discharge method. The failure times are predicted from their capacitance deterioration patterns, where the failure is defined as 30% capacitance decrease from the initial one. It is assumed that the lifetime distribution of EDLC follows Weibull and Arrhenius life-stress relationship holds. The life-stress relationship, acceleration factor, and $B_{10}$ life at design condition are estimated by analyzing the accelerated life test data.

• Smart Structures and Systems
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• v.1 no.4
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• pp.369-384
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• 2005

The main objectives of this paper are to demonstrate the feasibility of using newly developed smart GFRP reinforcements to effectively monitor reinforced concrete beams subjected to flexural and creep loads, and to develop non-linear numerical models to predict the behavior of these beams. The smart glass fiber-reinforced polymer (GFRP) rebars are fabricated using a modified pultrusion process, which allows the simultaneous embeddement of Fabry-Perot fiber-optic sensors within them. Two beams are subjected to static and repeated loads (until failure), and a third one is under long-term investigation for assessment of its creep behavior. The accuracy and reliability of the strain readings from the embedded sensors are verified by comparison with corresponding readings from surface attached electrical strain gages. Nonlinear finite element modeling of the smart concrete beams is subsequently performed. These models are shown to be effective in predicting various parameters of interest such as crack patterns, failure loads, strains and stresses. The strain values computed by these numerical models agree well with corresponding readings from the embedded fiber-optic sensors.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.79-86
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• 2010

This study was performed to evaluate the flexural behavior of Hybrid fiber sheet (HFC) and Hybrid fiber bar (HFB) strengthened reinforced concrete (RC) beams. According to test results, Hybrid fiber reinforcement strengthened RC beams showed approximately 60 to 200% higher reinforcing effects than that of un-reinforced specimens. In addition, the reinforced beams showed the ideal failure pattern, which is failed presenting the ductile behavior after yielding of the reinforcing bar. More specifically, in the case of HFB reinforced RC beams, the difference with puttying method was not apparent since HFB beams reinforced using the injection of epoxy and bonding of putty showed the similar failure patterns.

• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.291-298
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• 2016

Purpose: This study was to evaluate the effect of coloring liquids on the shear bond strength between zirconia and veneering ceramic. Methods: Zirconia(15 mm in diameter, 2.5 mm in thickness; n=40) used in the experiment were divided into 5 groups depending on the coloring liquid. Each specimen were polished using a polishing machine(LaboPol-2, Struers, UK). A cylinder of veneering porcelain(6 mm in diameter, 3 mm in thickness) was fabricated and fired on zirconia surfaces. The shear bond strength was measured using a universal testing machine(Model 4302, Instron, USA). All data were analyzed statistically using a one-way ANOVA and Tukey's multiple comparisons test. After the shear bond test, fracture surfaces were examined by SEM. Results: Colored zirconia showed a higher shear bonding strength than that of uncolored zirconia except for colored zirconia immersed in Zirkonzahn coloring liquid. In particular, colored zirconia immersed in Kuwotech coloring liquid showed the highest shear bond strength. After the shear bond test, mixed failure patterns were mainly observed in the failure between zirconia and veneering ceramic. Conclusion: Coloring liquid enhanced the shear bond strength zirconia and veneering ceramic than uncolored zirconia.

• Composites Research
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• v.13 no.2
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• pp.51-60
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• 2000

Filament wound pressure vessels have been studied for the efficient design tool to consider the variation of fiber angles through-the thickness direction. Filament winding patterns were simulated from semi-geodesic fiber path equation to calculate fiber path on arbitrary surface. Finite element analyses were performed considering fiber angle variation in longitudinal and thickness directions by ABAQUS. For the finite element modeling of the pressure tank, the 3-dimensional layered solid element was utilized. From the stress results of pressure tanks, maximum stress criterion in transverse direction was applied to modify material properties for failed region. In the end of each load increment, resultant layer stresses were compared with a failure criterion and properties were reduced to 1/10 for a failed layer. Results of progressive failure analysis were compared with two experimental data.

• Radiation Oncology Journal
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• v.29 no.4
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• pp.228-235
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• 2011

Purpose: To evaluate the impact of postoperative radiotherapy (PORT) on patterns of failure and survivals in uterine carcinosarcoma patients treated with radical surgery. Materials and Methods: Between October 1998 and August 2010, 19 patients with stage I-III uterine carcinosarcoma received curative hysterectomy and bilateral salpingo-oophorectomy with or without PORT at Seoul National University Hospital. Their hospital medical records were retrospectively reviewed. PORT and non-PORT groups included 11 and 8 patients, respectively. They were followed for a mean of 22.7 months (range, 7.8 to 126.6 months). Results: At 5 years, the overall survival rates were 51.9% for entire, 61.4% for PORT, and 41.7% for non-PORT groups, respectively. There was no statistical difference between PORT and non-PORT groups with regard to overall survival (p = 0.682). Seven out of 19 (36.8%) patients showed treatment failures, which all happened within 12 months. Although the predominant failures were distant metastasis in PORT group and loco-regional recurrence in non-PORT group, there was no statistically significant difference in locoregional recurrence-free survival (LRRFS) (p = 0.362) or distant metastasis-free survival (DMFS) (p = 0.548). Lymph node metastasis was found to be a significant prognostic factor in predicting poor LRRFS (p = 0.013) and DMFS (p = 0.021), while the International Federation Gynecology and Obstetrics (FIGO) stage (p = 0.043) was associated with LRRFS. Conclusion: Considering that adjuvant radiotherapy after surgical resection was effective to decrease loco-regional recurrence and most treatment failures were distant metastasis, multimodal therapy including surgery, radiotherapy, and chemotherapy might be an optimal treatment for uterine carcinosarcoma patients.

• Korean Journal of Head & Neck Oncology
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• v.15 no.1
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• pp.22-28
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• 1999

Purpose: We performed this study retrospectively to evaluate local control, survival, prognostic factors, and failure patterns in patients with non-Hodgkin's lymphoma of Waldeyer's ring. Materials and Methods: From April 1984 to November 1996,41 patients with non-Hodgkin's lymphoma of Waldeyer's ring were treated with combined chemotherapy and radiation therapy. Age was ranged from 19 to 73 years old with a median age of 55 years, and there were 26 male and 15 female patients. Primary site was tonsil in 26 and base of the tongue in 7 and nasopharynx in 8, and stage distribution showed stage I in 12 and stage II in 29 patients. Pathologic classification was done according to Working Formulation. There were 1 with follicular mixed small cleaved and large cell, 8 with diffuse small cleaved cell, 7 with diffuse mixed small and large cell, and 25 cases with diffuse large cell. All patients were treated with combination of chemotherapy and radiation therapy. Chemotherapy regimen consisted of either CHOP-Bleo(cyclophosphamide, adriamycin, vincristine, prednisolone, bleomycin) or COP-BLAM III(cyclophosphamide, vincristine, prednisolone, bleomycin, adriamycin, procarbazine). Radiation dose ranged from 3600cGy to 6620cGy with a median dose of 5040cGy. Follow-up time was ranged from 15 months to 159 months(median 55 months). Results: The complete response was achieved in 98%(40/41) and partial response in 2%(1/41). The complete response rate were the followings: 66.7% for stage I and 51.7% for stage II after chemotherapy, 100% for stage I and 96.6% for stage II after overall treatment respectively. The overall survival rate and disease-tree survival rates at 5 years were 82.6% and 79.5%, respectively. Prognostic factors for overall survival were age(p=0.007), stage(p=0.03), nodal status(p=0.006) and radiation dose(p=0.003). The factors associated with disease-tree survival were stage(p=0.04), nodal status(p=0.004) and radiation dose(p=0.009). The failure patterns were analized in evaluable 35 patients with complete response. Locoregional failure was noted in 2 patients and distant metastasis in 5 patients. Conclusion: Our results suggest that combined modality therapy is the appropriate treatment for stage I-II intermediate grade non-hodgkin's lymphoma of the Waldeyer's ring. However, our material is small and the analysis is retrospective. Randomized prospective studies for combined therapy, radiation therapy alone and chemotherapy alone are needed.

• Radiation Oncology Journal
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• v.13 no.1
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• pp.19-26
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• 1995

Purpose : Surgery is the treatment of choice for resectable non-small cell lung cancer. For patients who are medically unable to tolerate a surgical resection or who refuse surgery, radiation therapy is an acceptable alternative. A retrospective analysis of Patients with stage I non-samll cell lung cancer treated with curative radiation therapy was performed to determine the results of curative radiation therapy and patterns of failure, and to identify factors that may influence survival. Materials and Methods : From 1986 through 1993, 39 Patients with T2N0M0 non-small cell lung cancer were treated with curative radiation therapy at department of radiation oncology, Kyungpook national university hospital. All Patients were not candidates for surgical resection because of either Patient refusal (16 patients), poor pulmonary function (12 patients), old age (7 patients), Poor Performance (2 patients) or coexisting medical disease (2 patients). Median age of patients was 67 years. Histologic cell type was squamous cell carcinoma in 36, adenocarcinoma in 1, large cell carcinoma in 1 and mucoepidermoid carcinoma in 1. All patients were treated with megavoltage irradiation and radiation dose ranged from 5000cgy to 6150cGy with a median dose of 6000cGy. The median follow-up was 17 months with a range of 4 to 82 months, Survival was measured from the date therapy initiated. Results : The overall survival rate for entire Patients was $40.6\%$ at 2 years and $27.7\%$ at 3 years, with a median survival time of 21 months. The disease-free survival at 2 and 3 years was $51.7\%$ and $25.8\%$, respectively. Of evaluable 20 patients with complete response, 15 patients were considered to have failed. Of these, 13 patients showed local failure and 2 patients failed distantly. Response to treatment (p=0.0001), tumor size (p=0.0019) and age (p=0.0247) were favorably associated with overall survival. Only age was predictive for disease-free survival (p = 0.0452). Conclusion : Radiation therapy is an effective treatment for small (less than 3cm) tumors, and should be offered as an alternative to surgery in elderly or infirm patients. Since local failure is the prominent Patterns of relapse, potential methods to improve local control with radiation therapy are discussed.