• Journal of IKEEE
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• v.24 no.2
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• pp.385-391
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• 2020

Overcurrent and abnormal voltages in the distribution system can cause not only burden of power plant but also damage to customers. As a result, researches related to the distribution automation have been widely conducted by utilizing a real time digital simulation to improve the reliability of power supply through rapid failure handing, reduction of power failure intervals and failure recovery. However, the distribution automation systems using the real time digital simulator are expensive and limited to verify actual hardwares. Therefore, in this paper, an external hardware devices was developed based on the distribution system analysis results of the digital simulator. And real-time simulation and functional verification are implemented by the real feeder remote terminal units used in distribution automation. The effectiveness of the proposed system is verified through several experiments.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.110-116
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• 2022

Human failure event (HFE) dependency analysis is a part of human reliability analysis (HRA). For efficient HFE dependency analysis, a maximum number of minimal cut sets (MCSs) that have HFE combinations are generated from the fault trees for the probabilistic safety assessment (PSA) of nuclear power plants (NPPs). After collecting potential HFE combinations, dependency levels of subsequent HFEs on the preceding HFEs in each MCS are analyzed and assigned as conditional probabilities. Then, HFE recovery is performed to reflect these conditional probabilities in MCSs by modifying MCSs. Inappropriate HFE dependency analysis and HFE recovery might lead to an inaccurate core damage frequency (CDF). Using the above process, HFE recovery is performed on MCSs that are generated with a non-zero truncation limit, where many MCSs that have HFE combinations are truncated. As a result, the resultant CDF might be underestimated. In this paper, a new method is suggested to incorporate HFE recovery into the MCS generation stage. Compared to the current approach with a separate HFE recovery after MCS generation, this new method can (1) reduce the total time and burden for MCS generation and HFE recovery, (2) prevent the truncation of MCSs that have dependent HFEs, and (3) avoid CDF underestimation. This new method is a simple but very effective means of performing MCS generation and HFE recovery simultaneously and improving CDF accuracy. The effectiveness and strength of the new method are clearly demonstrated and discussed with fault trees and HFE combinations that have joint probabilities.

• Journal of Industrial Convergence
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• v.14 no.2
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• pp.15-23
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• 2016

Korea is aging rapidly and unprecedentedly in the world, and the social burden is prospected to be increased rapidly. New business start-up in blue ocean area is boomed in Korea, because sedulousness of people and high household saving rate which are basis of the economic development are getting lower, and propensity of the consumption and debt in household are getting higher. This article is refers that what is success factors of new business start-up in blue ocean through investigating the theoretical concept and the success cases. As a result, the success factors of new business start-up are categorized as environmental factors, strategical factors, organizational factors, personal factors, and factors of growing-up stages. In order not only to identify the success factors, but also to avoid failure, it is important that the basic principle should be followed ; Specifying the objectives, Balancing the fund, Meeting good biz-partners, Analysis of the market and Advice of the experts.

• Journal of Power Electronics
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• v.10 no.6
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• pp.660-666
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• 2010

This paper presents the approach followed to develop a course that introduces reliability into the design of power electronics converters. The course is part of the curriculum of a master of science in electrical engineering program, and it is aimed at providing reliability tools that can be used in a straightforward manner, while avoiding the mathematical intricacies. The reliability calculations are performed according to the Military Handbook 217, using the evaluation version of a commercial software package which greatly reduces the computational burden usually associated with this task. The course assessment shows that, after attending the course, students were able to improve the mean time between failures in a power-electronics converter, from a minimum of 5%, up to 100%.

• Journal of Applied Reliability
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• v.11 no.4
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• pp.371-385
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• 2011

Because consumer mostly utilizes company test standard, supplier spends burden of expenses on building test equipments and managing expert manpower to fulfill consumer's various tests. Therefore, it is urgent to standardize test assessment which has a bond of sympathy between consumer and supplier and evaluates reliability of their products. This study develops reliability assessment standard which is composed of 12 test items considering international and domestic test standards, company internal test standards of consumer companies and field conditions. Also this study introduces overall technical procedure on accelerated test with no failure which is used for the main technology of reliability assessment. To verify effectiveness of reliability assessment, the test results are herein analyzed through building the test equipments and performing the test items.

• Journal of Information Processing Systems
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• v.15 no.6
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• pp.1462-1471
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• 2019

Real-time embedded systems have become pervasive in general industry. They also began to be applied in such domains as avionics, automotive, aerospace, healthcare, and industrial Internet. However, the system failure of such domains could result in catastrophic consequences. Runtime software testing is required in such domains that demands very high accuracy. Traditional runtime software testing based on handwork is very inefficient and time consuming. Hence, test automation methodologies in runtime is demanding. In this paper, we introduce a software testing system that translates a real-time software into a monitorable real-time software. The monitorable real-time software means the software provides the monitoring information in runtime. The monitoring target are time constraints of the input real-time software. We anticipate that our system lessens the burden of runtime software testing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1311-1322
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• 1997

Performance management of ATM network is urgently required because a different quality of service should be guaranteed on each connection. A lot of performance measurement data increase the burden on agent systems and on managment stations. In this paper, an effective OAM-based performance monitoring and faulty node identification technique is proposed. A proposed VP Selection Algorithm reduces management-related traffic and when the indication of hard or soft failure state is detected, failed node is identified by Fault Identification Rule.

• Journal of Korean language education
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• v.29 no.4
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• pp.225-254
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• 2018

The purpose of this study is to contrast the patterns of realization and understanding of refusal speech acts between Korean and Thai learners. This study intends to answer the following questions: (1) Do Koreans and Thai learners perform refusal speech acts differently? (2) Do Koreans and Thai learners understand refusal speech acts differently? A DCT and a follow-up interview were conducted to collect data of two groups of 30 native Korean speakers and 30 native Thai speakers. For research question 1, we analyzed the refusal strategy and provided reasons given by Koreans and Thai learners depending on the context. For research question 2, we ran a chi-squared test on the elements of the follow-up interviews, such as the weight of burden of refusing, and whether the participant would actually refuse or not. The differences between the refusal strategies of the two groups could be categorized by the preceding inducing speech act. In refusing a request, the difference was prominent in the apologizing strategy, whereas in refusing a suggestion, the difference was mainly in the direct refusal strategy. When refusing an invitation, the most evident difference was the number of refusal strategies employed. When providing an explanation of refusal to people with high social status, Koreans gave more specific reasons for refusals, whereas Thai learners tended to use more vague reasons. Moreover, when refusing an invitation, Koreans primarily mentioned the relationship, and Thai learners showed the spirit of Greng Jai. When asked the weight of burden of refusing, Koreans felt pressured to refuse a request from people with high social status, and a suggestion or invitation from people with high level of intimacy while Thai learners found it highly difficult to make a refusal in all cases. In answering whether they would actually refuse or not, Koreans tried not to make a refusal to people with high level of intimacy, and such a trend was not evident among the Thai. This study can help us better understand the learner's pragmatic failure, and serve as a basis in establishing a curriculum for teaching speech acts.

• Korean Journal of Clinical Pharmacy
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• v.26 no.4
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• pp.341-347
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• 2016

Background: Liver cirrhosis causes substantial socio-economic burden and is one of the major severe liver diseases in Korea. Nonetheless, there is only a few studies that analyzes disease burden of liver cirrhosis in Korea. Such study must be carried out due to its increasing need from the invention of new drugs for chronic hepatitis and demand for cost-effectiveness analyses. Methods: Patient sample data with ensured representativeness was analyzed retrospectively to compare the medical costs and uses for patients with compensated cirrhosis and decompensated cirrhosis. Patient claims data that include K74 and K703 from the year of 2014 were selected. Within the selected data, decompensated cirrhosis patient was identified if complications such as ascites (R18), encephalopathy (B190), hepatic failure (K72), peritonitis (K65), or esophageal varices (I85) were included, and they were compared to compensated cirrhosis patients. Results: 6,565 patients were included in the analysis. The average cost per patient was 6,471,020 (SD 8,848,899) KRW and 2,173,203 (4,220,942) KRW for decompensated cirrhosis and compensated cirrhosis, respectively. For inpatients, the average hospitalized days was 38.0 (56.4) days and 27.2 (57.2) days for decompensated cirrhosis and compensated cirrhosis, respectively. For outpatients, the average number of visits was 8.7 (9.1) days and 5.3 (7.5) days for compensated cirrhosis and decompensated cirrhosis, respectively. Conclusion: Compared to compensated cirrhosis patients, decompensated cirrhosis patients had higher costs, especially for hospitalization, injection, examination, and drugs administrated within medical institutions.

• Korean Journal of Digital Imaging in Medicine
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• v.15 no.1
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• pp.1-7
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• 2013

Purpose : The Carotid Angio inspection including Aortic arch applied to wide area is conducted as the Contrast Enhance MR Angiography(CEA) which is using a contrast medium. However it is a burden not only for someone such as infants, pregnant women and patients suffering from kidney failure but continuous use of contrast medium also can be a burden for patients who has been taken follow up inspection since diagnose lesion already. The purpose of this study is to estimate a usefulness of the Time of Flight (TOF) by comparing with CEA. Materials and methods : 10 patients with an average age of 58 (from 45 to 75) who had MRA inspection in our hospital were studied using 3.0 Tesla Aachieva (Philips, Netherland) MRI system and Sense Neuro-Vascular 16 Channels Coil. The same patient was inspected both TOF and CEA simultaneously. The TOF inspection included from Aortic arch to Willis Circle by connecting 3 TOF stacks and so did CEA inspection. The quantitative analysis was conducted through signal to noise ratio(SNR) and contrast to noise ratio(CNR) with soft tissue by setting up an area of interest on CCA bifurcatoin, ICA, ECA, MCA and VA concerning obtained image. In case of qualitative analysis, 3 radiological technologists and 1 radiologist evaluated 4 items (1: Visibility of the blood vessel, 2: Image distortion measure, 3: Overlapping measure with vein, 4: Peripheral blood vessel description measure) into five points scale (1: Very bad, 2: Bad, 3: Normal 4: Good, 5: Very good). Results : Results for the quantitative analysis was obtained by calculating the average of 5 ROIs in case of SNR and CNR separately. Results of SNR, TOF were generally measured higher than CEA (In case of TOF were 166.1, 205.2, 154.39, 172.23, 161.95, and CEA were 92.05, 95.43, 84.76, 73.69, 88.3). But according to the result of CNR, both TOF and CEA were measured similarly as 67.62, 106.71, 55.9, 73.74, 63.46 for TOF and 67.82, 71.19, 60.52, 49.45, 64.07 for CEA. Throughout every results of each ROI, SNR showed statistically meaningful consequence (0.050.05). In case of qualitative analysis the average of each evaluated item was 4.2points and 4.28points in the item1, 2.93points and 4.55points in the item2, 4.6points and 3.13points in the item3, 2.88points and 4.6points in the item4. According to the results TOF was measured higher in the item3 while in the item2 and item4 CEA was higher and in case of the item1, both CEA and TOF were similar. To sum up statistically meaningful results (p<0.05) were shown in the item2, item3 and item4 but not in the item1 (p>0.05). Conclusions : Both TOF and CEA are complementary because each inspection has pros and cons, but when inspect wide area including Aortic arch normally CEA is conducted. But TOF inspection also can be considered as alternative in terms of patients who has difficulty in the contrast medium such as infants, pregnant women and patients suffering from kidney failure and patients during follow up.