• Journal of the Korean Society of Systems Engineering
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• v.12 no.1
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• pp.41-58
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• 2016

Reliability Centered Maintenance (RCM) introduces a systematic method and decision logic tree for utilizing previous operating experience focused on reliability and optimization of maintenance activities. In this paper RCM methodology is applied on safety injection system for APR-1400. Functional Failure Mode Effects and Criticality Analysis (FME&CA) are applied to evaluate the failure modes and the effect on the component, system and plant. Logic Tree Analysis (LTA) is used to determine the optimum maintenance tasks. The results show that increasing the condition based maintenance will reduce component failure and improve reliability and availability of the system. Also the extension of the surveillance test interval of Safety Injection Pumps (SIPs) would lead to an improved pump's availability, eliminate the unnecessary maintenance tasks and this will optimize maintenance activities.

• Korean journal of aerospace and environmental medicine
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• v.30 no.2
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• pp.61-65
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• 2020

In the case of aviation maintenance work, several kinds of shift works are performed during day and night, and a lot of works are performed on the ramp due to the characteristics of the aircraft flight schedule. Maintenance workers are often exposed to the sun or in cold temperatures for aircraft maintenance works. The fatigue risk of the maintenance workers will be weighted. In particular, the work at night shift under normal biological rhythms can make maintenance workers feel sleepy during daytime work. It can also affect the safety of aircraft and individual workers. Accordingly, this study will consider fatigue-related previous researches in the field of aviation maintenance, review the effects of shift work, and how fatigue affects aviation mechanics during the day/night shifts. Considering these factors, we tried to present a plan that can minimize the fatigue of aviation workers through this study.

• Journal of Haehwa Medicine
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• v.12 no.2
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• pp.157-175
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• 2004

The purpose of this study was to investigate the effects of Hangamdan(抗癌丹). The clinical study was carried out 320 cases of patients with cancer treated by Hangamdan(抗癌丹) from May 1st 1998 to September 1st 1999. The results were summarized as follows; 1. The effects of improvement in the symptoms with traditional oriental cancer therapy(47.6%) were higher than combined treatment of western and oriental therapy(37.4%). 2. In the analysis of hematology, maintenance and increasing of WBC(86.2%), Hgb(87.2%), P1atelet(97.6%) RBC(81.1%) were observed. In the analyses of tumor marker, maintenance and decreasing of CEA(76%), CA19-9(88.8%), AFP(69.2%) were observed. 3. In the analysis of safety, maintenance and decreasing of AST(93.1%), ALT(95%), BUN(92.2%), Creatinine(93.6%) were observed. 4. In the analysis of QOL attached by cancer, combined treatment of western and oriental therapy(maintenance and improvement; 91.8%) was higher than traditional oriental cancer therapy(maintenance and improvement; 79.3%) 5. In the analysis of survival in patients with terminal cancer, above 6 months(46.3%), 12 months(19.2%). 6. In the analysis of antitumor effects, combined treatment of western and oriental therapy(maintenance 71.6% improvement 12.8%) was higher than traditional oriental therapy (maintenance 66.7% improvement 9.5%). 7. In the analysis of curative evaluation, combined treatment of western and oriental therapy(maintenance 40.4% improvement 41.8%) was higher than traditional oriental therapy (maintenance 23.8% improvement 46.1%). 8. In the analysis of IL-12 and IFN-$\gamma$ attached by cancer, increasing of IL-12(32.3%), IFN-$\gamma$(41.5%) were observed. From the above results, it is suggested that Hangamdan has significant effects of antitumor and immune activity, also could be usefully applied for cancer patients by combination with western therapy or alone.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.167-178
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• 2007

In general, it is known that the concrete ballast track is possible to reduce a cost of maintenance activities cause of maintenance free by restrictive maintenance in application of track ballast structures. However, if deteriorations and fracture mechanism of a material are considered, proper maintenance activities and repairing are continually required. For the problems, we evaluated an economical efficiency of the gravel ballast and the concrete ballast on a proper level of maintenance activities. As the method based on history path is difficult to obtain sufficient reliabilities cause of an absence of real data for maintenance activities, we chose the delphi survey method by professional group, and we obtained the appropriate index and profiles for maintenance activities. As a result, we founded that effects for cost reduction can be expected by preventive maintenance management, and we proposed economical restrictions and life cycle cost for track ballast structures in a life cycle.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.1-9
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• 2016

The paper aims at evaluating effects of preventive maintenance on life cycle cost(LCC) reduction of bridges. The preventive maintenance activities capable to delay bridge deteriorations can reduce overall maintenance costs and extend service life of a bridge by regularly providing maintenance activities and avoiding larger maintenance(repairs or rehabilitations) costs. Couple of prediction models were proposed in order to calculate LCC of a typical bridge: a health score model and repair rehabilitation cost model. In addition, the maintenance activities such as wash and painting were also suggested in order to consider effects of preventive maintenance in the analysis based on literature reviews. According to analysis results, new maintenance strategy(reactive maintenance + preventive maintenance) can save \0.5 billion per bridge for future life-cycle costs over 100 year analysis or \184 billion for entire HBMS(Highway Bridge Management System) inventory over 20 years. Small investments for preventive maintenance in improved bridge management can have a very significant return when considering the large bridge inventory.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.4
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• pp.1-11
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• 2011

This paper presents the effects of preventive maintenance schemes on the residual stress distributions in dissimilar metal welds. Dissimilar metal weld is known susceptible to PWSCC and thus, effective maintenance schemes to prevent PWSCC are needed. Three preventive maintenances schemes, i.e. weld overlay, MSIP and inlay weld which are widely used in nuclear power plants, are selected and their effects on welding residual stresses are investigated via finite element analyses. As results, weld overlay and MSIP were proved effective method to mitigate residual stresses and inlay weld, on the other hand, produces strong tensile residual stresses in the inner surface. Although Alloy 690 known to be resistant to PWSCC are used in inlay weld, continuous careful observation are needed since tensile welding residual stresses are key parameter for PWSCC.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2413-2419
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• 2013

Background: Use of epidermal growth factor receptor inhibitors (EGFR-TKIs ) is now standard for non-small-cell lung cancer (NSCLC). However, the effects of EGFR-TKIs in maintenance therapy for advanced NSCLC patients are still unclear. The preent meta-analysis was performed to examine pooled data of randomized control trials (RCT) where EGFR-TKIs were compared against placebo in maintenance regimens for patients with advanced NCSLC to quantify potential benefits and determine safety. Methods: Several data bases were searched, including PubMed, EMBASE and CENTRAL, and we performed an internet search of conference literature. The endpoints were objective response rates (ORR), progression-free survival (PFS) and overall survival (OS). We performed a meta-analysis of the published data, using Comprehensive Meta Analysis software (Version 2.0). with a fixed effects model and an additional random effects model, when applicable. The results of the meta-analysis are expressed as hazard ratios (HRs) or risk ratios (RRs), with their corresponding 95% confidence intervals (95%CIs). Results: The final analysis included six trials, covering 3,758 patients. Compared with placebo, EGFR-TKIs maintenance therapy improved ORR and PFS for patients with advanced NSCLC, the difference being statistically significant (P<0.05), but proved unable to prolong patients' OS. The main adverse reactions were diarrhea and rashes. Conclusion: EGFR-TKIs demonstrated encouraging efficacy, safety and survival when delivered as maintenance therapy for patients with advanced NSCLC after first-line chemotherapy, especially for the patients who had adenocarcinomas, were female, non-smokers and patients with EGFR gene mutations.

• Childhood Kidney Diseases
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• v.22 no.1
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• pp.1-6
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• 2018

Rituximab (RTX) is a chimeric monoclonal antibody that inhibits CD20-mediated B-cell proliferation and differentiation. Several studies have examined its use in intractable nephrotic syndrome (NS) with some positive results. However, those studies examined such effects for a short-term period of 1 year, and some patients continued to relapse after a lapse in RTX treatment. Our use of RTX as a maintenance therapy (RTX injection when the CD19 cell count exceeded $100-200/{\mu}L$ before relapse) showed some noticeable efficacy. We used RTX in 19 patients with steroid-dependent NS (SDNS). In 12 patients treated with RTX maintenance therapy, only one relapse occurred. The mean treatment period was $23.4{\pm}12.7months$, and the mean number of RTX administrations was $3.9{\pm}1.6$. The relapse rates were decreased (from 2.68/year to 0.04/year), and the drug-free period also increased (from 22.5 days/year to 357.1 days/year) during maintenance therapy. The other seven patients were treated with one cycle of RTX or additional cycles in case of relapse (non-maintenance therapy). Relapse rates were significantly decreased after RTX treatment (from 1.76/year to 0.96/year, P=0.017). The relapse-free period was $15.55{\pm}7.38$ (range, 5.3-30.7) months. No severe side effects of RTX were found except for a hypersensitivity reaction such as fever and chills during its infusion. In conclusion, RTX is considered an effective and safe option to reduce the relapse rate by a single- or maintenance-interval therapy in SDNS.

• Journal of Haehwa Medicine
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• v.10 no.1
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• pp.121-131
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• 2001

Clinical studies were carried out 62 cases of patients with lung cancer treated by Hangamdan(抗癌丹) from January 1th 1998 to September 30th 2000. The results were summarized as follows; 1. Distribution of those attached by lung cancer, by sex, showed that Male is more then Female, by age, showed that the number of sixties is majority. 2. Distribution of diagnostic stage, in descending order; stage IV(43.6%,top), stage III(35.5%), stage II(17.7%), stage I(3.2%). 3. The effects of maintenance and improvement in the symptoms with traditional oriental therapy(83.3%) and combined treatment of western and oriental therapy(84.0%) were observed. The effects of the symptoms were as follows; cough(50.0%), anorexia(48.4%), chest discomfort(31.0%), sputum(24.2%), general body weakness(11.3%), hemoptysis(9.7%) and etc. in orders. 4. Analysis of hematology attached by lung cancer, maintenance and increasing of WBC(98.4%), RBC(74.2%), Hgb(71.0%), Platelet(96.7%) were observed. After taken Hangamdan, the safety of the liver and kidney were as follows; maintenance and decreasing of AST(91.5%), ALT(93.2%), ${\gamma}-GTP$(95.0%), BUN(82.7%), Creatinine(93.3%) were observed. 5. Analysis of IL-12 and $IFN-{\gamma}$ attached by lung cancer, increasing of IL-12(31.3%), $IFN-{\gamma}$(72.7%) were observed. 6. Analysis of QOL attached by lung cancer, maintenance and improvement of combined treatment of western and oriental therapy(94.0%), traditional oriental therapy(91.7%) were observed. 7. Analysis of survival in patients with IV stage of lung cancer, above 7 months(22.2%), 12 months(70.4%). 8. Analysis of antitumor effects, maintenance of traditional oriental therapy(50.0%) and maintenance and improvement of combined treatment of western and oriental therapy(80.0%) were observed. 9. Analysis of curative valuation, maintenance and improvement of traditional oriental therapy(50.0%), combined treatment of western and oriental therapy(60.0%) were observed. From the above results, it is suggested that Hangamdan has significant effects of antitumor and immune activity, also could be usefully applied for lung cancer patients by combination with western therapy or alone.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.196-197
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• 2006

Preventive maintenance can avail the generation utilities to reduce cost and gain more profit in a competitive supply-side power market. So, it is necessary to perform reliability analysis on the systems in which reliability is essential. In this paper, RCM (Reliability -Centered Maintenance) analytical method is adopted using real historical failure data in Korean power plants. Therefore, the reliability -based Probability model for predicting the failures of components in the power plant is also established, and application to FMECA(Failure Mode Effects and Critical Analysis) consideration of failure probability, Based on the weighting ranking of generating equipments which status to be probability estimation by FMECA. The FMECA is an engineering analysis and a core activity performed by reliability engineers to review the effects of probable failure modes of generating equipments and assemblies of the power system on system performance. The results of this paper show that application of FMECA with stochastic approach to the preventive maintenance can efficiently avail decreasing the cost on maintenance and hence improve the total benefit.