• Investigative Magnetic Resonance Imaging
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• v.22 no.1
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• pp.10-17
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• 2018

Purpose: To evaluate interpretation errors involving spine MRIs by residents in their second to fourth year of training, classified as minor, intermediate and major discrepancies, as well as the types of commonly discordant lesions with or without clinical significance. Materials and Methods: A staff radiologist evaluated both preliminary and final reports of 582 spine MRIs performed in the emergency room from March 2011 to February 2013, involving (1) the incidence of report discrepancy, classified as minor if there was sufficient description of the main MR findings without ancillary or incidental lesions not influencing the main diagnosis, treatment, or patients' clinical course; intermediate if the correct diagnosis was made with insufficient or inadequate explanation, potentially influencing treatment or clinical course; and major if the discrepancy affected the main diagnosis; and (2) the common causes of discrepancy. We analyzed the differences in the incidence of discrepancy with respect to the training years of residents, age and sex of patients. Results: Interpretation discrepancy occurred in 229 of the 582 cases (229/582, 39.3%), including 146 minor (146/582, 25.1%), 40 intermediate (40/582, 6.9%), and 43 major cases (43/582, 7.4%). The common causes of major discrepancy were: over-diagnosis of fracture (n = 10), missed cord lesion (n = 9), missed signal abnormalities associated with diffuse marrow (n = 5), and failure to provide differential diagnosis of focal abnormal marrow signal intensity (n = 5). No significant difference was found in the incidence of minor, intermediate, and major discrepancies according to the levels of residency, patients' age or sex. Conclusion: A 7.4% rate of major discrepancies was found in preliminary reporting of emergency MRIs of spine interpreted by radiology residents, probably related to a relative lack of clinical experience, indicating the need for additional training, especially involving spine trauma, spinal cord and bone marrow lesions.

• Journal of Aerospace System Engineering
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• v.11 no.3
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• pp.39-46
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• 2017

Required military demands for high reliability of weapons systems throughout stages of life cycles as high technologies combined with weapons systems, research and development continue to drive costs upwards. However, for studies on reliability of national defense weapons systems, empirical research is limited because of a lack of interest or limitations relative to data collection. This study proposes a collection process relative to field operating specifications, based on data relative to experience and management collected by visiting vessels onsite, that operate weapons systems. In addition, after drawing the operating MTBF of the launching system for the Haeseong guided missile launcher, this study compared and analyzed that with values predicted during development and identifies parts with low operating values as compared to predicted values. Results of this study relative to maintenance support troops and weapon systems development companies will contribute to maintaining operational deployment of the launching system of the Haeseong guided weapons system.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.600-612
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• 2009

Special banks primarily using Internet have different properties in transactions with customers, risk management, capital strength, and branch networks with general banks. The success and failure factors of Internet banks have been explained only by the economies of scale, and learning and experience effects of Internet banks based on the perspective of organizational ecologies. In this study, the success factors of Internet banks are investigated based on strategic choice by organizations and resource-based view of the firms instead of organizational ecology perspective. To this end, 31 major Internet banks operating in overseas market have been classified by the size and profitability of banks, and three strategic groups have been derived. three representative company cases were analyzed. critical success factors of Internet banks were derived, and considerable points when operating Internet banks were discussed.

• Convergence Security Journal
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• v.6 no.1
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• pp.1-11
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• 2006

The exponential increase of malicious and criminal activities in cyber space is posing serious threat which could destabilize the foundation of modem information society. In particular, unexpected network paralysis or break-down created by the spread of malicious traffic could cause confusion and disorder in a nationwide scale, and unless effective countermeasures against such unexpected attacks are formulated in time, this could develop into a catastrophic condition. As a result, there has been vigorous effort and search to develop a functional state-level cyber-threat early-warning system however, the efforts have not yielded satisfying results or created plausible alternatives to date, due to the insufficiency of the existing system and technical difficulties. The existing cyber-threat forecasting and early-warning depend on the individual experience and ability of security manager whose decision is based on the limited security data collected from ESM (Enterprise Security Management) and TMS (Threat Management System). Consequently, this could result in a disastrous warning failure against a variety of unknown and unpredictable attacks. It is, therefore, the aim of this research to offer a conceptual design for "Knowledge-based Real-Time Cyber-Threat Early-Warning System" in order to counter increasinf threat of malicious and criminal activities in cyber suace, and promote further academic researches into developing a comprehensive real-time cyber-threat early-warning system to counter a variety of potential present and future cyber-attacks.

• Composites Research
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• v.33 no.5
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• pp.288-295
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• 2020

Fiber-reinforced composite laminates have high specific stiffness and strength and are expected to be useful for weight reduction in weight-sensitive industries, such as automotive and aerospace. However, designing composite laminates is often dependent on designer's experience and intuition because of difficulties in determining the number of plies and stacking sequence, which tends to lead to over-design. In this study, optimal design of composite laminates was performed to minimize weight, while withstanding the given load. Based on the enumeration method, all combinations of stacking sequence satisfying the design guideline for composite laminates were considered. Composite laminates were discretized into panels. Optimal number of plies and stacking sequence for each panel were determined considering local load on each panel and contiguity across adjacent panels. Failure index from Tsai-Wu criteria was optimized for strength and buckling analysis was performed for compressive load. Stacking angles of 0, ±45 and 90° were used.

• Journal of Chest Surgery
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• v.26 no.9
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• pp.677-685
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• 1993

Experience with bileaflet mechanical valve replacement at the Inha Hospital in 192 patients, operated on from June 1986 until April 1993. Two hundred fourty-one prostheses [51 Duromedics, 79 St.Jude Medical, and 111 CafboMedics]were implanted during the total 195 operations. Mitral valve replacment[MVR]was done in 113 cases, aortic valve replacement[AVR]in 34, tricuspid valve replacement[TVR]in 2, and double valve replacement[DVR]in 46 cases.Of the total patients, 63.0% were women and 37.0% were men. The mean age of the patients was 40.8 years, ranged from 14 to 67years. Overall early mortality was 9.2\ulcorner%[18 out of 195]; 9.7%[11 out of 113]for MVR, 14,7% [5 out of 34]for AVR, and 4.3%[2 out of 46]for DVR. All of the operative survors were followed over a period of one to 83 months with a mean of 37 months, for total 543 patient-years. So far, eleven patients[6.7% of the long-term survivors]were lost to follov-up after a mean postoperative follow-up of 22.8 months. There were nine late deaths; three deaths due to prostetic valve endocarditis, two due to persistent heart failure, one due to cerebral hemorrhage, one due to aortic dissection after Bentall oreration, and two sudden deaths. Actuarial survival rate at 6.9 years was 94.8%, There were seventeen valve-related complications; three prosthetic valve thromboses, three thrombembolisms, three instances of prosthetic valve endocarditis, two paravalvular leakages, and six hemorrhagic complications related to anticoagulation. The actuarial rate of freedom from all valve-related complications at 6.9years was 91.3%. There were significant decreases in the heart size postoperatively that can be demonstrated by comparison of cardio-thoracic ratios on simple chest X-ray and left ventricle dimensions on echocardiography. We conclude that this midterm follow-up shows good results in terms of hemodynamics and durability although further long-term evaluations are mandatory.

• Journal of Chest Surgery
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• v.28 no.3
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• pp.263-267
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• 1995

A total and consecutive 87 patients underwent aortic valve replacement[AVR with the St. Jude Medical prosthesis between 1984 and 1993. Age ranged from 14 to 66 years[mean:38.6$\pm$ 14.0 years .Twenty-one patients [24.1% had undergone previous valve replacement. There were 8 early deaths with an operative mortality rate of 9.2% [7.6% for primary AVR and 14.3 % for re-replacement AVR . Seventy-nine early survivors were,followed for a total of 309.1 patient-years[mean:3.9$\pm$ 2.5 years . A late mortality rate was 5.1% [4 patients or a linearized incidence of 1.294 %/patient-year. All were anticoagulated with coumadin to maintain the international normal ized ratio[INR between 1.5 and 2.5. One patient experienced thromboembolism[0.324%/patient-year , and none did bleeding. Endocarditis occurred in one[0.324%/patient-year . Paravalvular leak was the most frequent complication and was experienced by 8 patients[2.588%/patient-year , and 5 of them required re-replacement AVR[1.618 %/patient year of reoperation rate . There was no structural failure of the prosthesis. Actuarial survival including operative death was 83.9%$\pm$ 4.6% at 10 years.The actuarial estimates of freedom from thromboembolism and of freedom from late death and all complications were 95.1% $\pm$ 4.8 % and 81.4% $\pm$ 6.1%, respectively, at 10 years. These clinical results suggest that less intensive anticoagulation may be allowed for patients of AVR with the St. Jude Medical valve with low incidences of both thromboembolic and bleeding complications.

• Journal of the Korean Professional Engineers Association
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• v.13 no.4
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• pp.31-47
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• 1980

Since medium and small manufacturing enterprises have , played a very important role not only in national economy but also in political and social relationships all of the countries in the world have paid favorable policies and programmes for protecting and promoting this sector. In Korea main ingredients of promoting policy for this sector consist of (1) encouragement to modernize facilities and rationalize operation (2) special priority in bank loan (3) promotion of industrial cooperatives (4) prevention of infringement by large industries. However, substantial investigation for problems incurred in medium industries has revealed that unless medium industries improve and raise their technological and managerial skillfulness for themselves all other measures are useless to solve the problems. This realization has induced all of the countries to render extension services on both of technology and management to assist and support their own effort for rationalization. Also in Korea during past 20 years many technical and managerial research institutes have rendered free consultancy services to medium industries by the support of government subsidy. Among them the joint extension services project performed by the Medium Industry Bank and UNDP during 1967 and 1975 might he listed as model case because of its broad and integrated activities and participation of foreign experts. We think many precepts should be :learned from the study of this project. Korean economy is expected to develop rapidly throughout coming'80 in spite of many obstacles, tut there is an apprehension that gap in of every facet between medium and large enterprises might he deepened and enlarged. To prevent the actualization of so-called dual structure of national economy and to promote stabilized medium industries with high added value productivity which are shown in well developed countries, consultancy assistance ana extension services should be strengthened much more than ever. Fortunately in 1978 legislation of "Medium and small industry promotion act" has paved the way for the systematic achivement of consultancy and extension services which shall be integrated by the government overall program. Under new framework thoughtfull accomplishment should be undertaken considering precious precepts obtained from past experience and failure. Special attention should be given to the technical liaison officer scheme, exclusive participation of only professional institutes, strict qualification and training for consultants for the future succsseful implementation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1632-1638
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• 2011

Electric cables are one of the most important components in a nuclear power plant since they provide the power needed to operate electrical equipment. Despite their importance, cables typically receive little attention since they are considered passive, long-lived components that have been very reliable over the years when subjected to the environmental conditions for which they were designed. The operating experience reveals that a defect of the insulator or poor construction causes the initial failure of cable. However, the number of cable failures increase with plant aging, and these cable failures are occurring within the plants' 40-year licensed period. These cable failures have resulted in plant transients, shutdown, loss of safety functions or redundancy, entries into limiting conditions for operation, and challenges for plant operators. Therefore, diagnosis of MV cable installed in NPPs has become one of the most urgent issues in recent years. In accordance with PSR, condition maintenance for cables is also continuously required. Recently, HFPD tests have been widely performed to diagnose cable in the transmission and distribution cable system. However, on-line HFPD wasn't used in the NPPs because of the danger of plant shutdown, measurement sensitivity and application problems, etc. In this paper, HFPD measurement with portable device was performed to evaluate the integrity of the 4.16kV & 13.8kV cable lines. The test results show that HFPD is highly attractive to the diagnosis of MV cables in NPP by high detection sensitivity on-site.

• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.110-120
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• 1994

The Quantitative analysis for collapsion probability of each construcion work has not been developed, despite of that the one for safety management itself has been reported, up to now. It is concluded that showing critical check points against structure collapsion due to each work at construction site, and Quantifying those could be useful Quality-assuring tool, not to prevent Quality failure. Risk classes of each work at construction site, classified by German Builders Mutual-Aid Association (GEBMAS), and by special instruction rates of Korea Insurance Development Institute, are introduced to compare with the results of this study. As of a study method, total 2,002 sheets of questionwares are distributed directly to new city development areas, which are called, Ilsan 110 points : Pundang 79points and Chungdong 38points, including additional Changwon 125sheets and pusan 60sheets, by four(4) people, for contact with actual site engineers. Total responses of 1,056 sheets, are collected. Interrelationship diagram between experience years of Engrs., and risk rate of responses are also classified, with the criteria of four(4) years. Domestic journals with relation to construction have reported that main building Structure collapsions are mainly shown on apartment buildings and office ones. These two(2) building structures are again classified as five(5) kinds of works. This study takes use of an approach on haying the risk rates for each construction work on the above individual construction work. Additionally, site investigations have been performed to find out any possible unreasonable check items, due to construction method ; Reinforced Concret structure, Pre cast Concrete structure, and Steel structure building. Developed Quality Assurance Analysis Form with the Quantitative danger class, resulted from this study, are verified as it is able to be a good efficiency tool against collapsion of building structures.