• The Journal of Korean Institute of Communications and Information Sciences
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• 제19권5호
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• pp.822-832
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• 1994

DSC-HDTV image compression algorithm removes spatial, temporal, and amplitude redundancies of an image by using transform coding, motion-compensated predictive coding, and adaptive quantization, respectively. In this paper, leak processing method which is used to recover image quality quickly from scene change and transmission error and adaptive quantization using perceptual weighting factor obtained by HVS are proposed. Perceptual weighting factor is calculated by contrast sensitivity, spatio-temporal masking and frequency sensitivity. Adaptive quantization uses the perceptual weighting factor and global distortion level from buffer history state. Redundant bits according to adaptation of HVS are used for the next image coding. In the case of scene change, DFD using motion compensated predictive coding has high value, large bit rate and unstabilized buffer states since reconstructed image has large quantization noise. Thus, leak factor is set to 0 for scene change frame and leak factor to 15/16 for next frame, and global distortion level is calculated by using standard deviation. Experimental results show that image quality of the proposed method is recovered after several frames and then buffer status is stabilized.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• 제26권2호
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• pp.184-189
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• 2022

Backgrounds/Aims: The soft texture of the pancreas parenchyma may influence the incidence of pancreatic leakage after pancreaticcoduodenectomy (PD). One possible method to assess pancreatic texture and atrophy, is via computed tomography (CT) scan of the abdomen. The purpose of our study was to evaluate the relation between the preoperative CT scan and the incidence of pancreatic fistula after PD. Methods: A retrospective single-center study including patients who underwent PD for a benign and malignant tumor of the periampullary region between the years 2000 and 2016. Demographic and imaging data were analysed and a correlation with the post-operative leak was evaluated. Results: Pancreatic leak was documented in 34 out of 154 (22.1%) patients. All the leakage cases occurred in the preserved pancreas group (33.1% of the total preserved pancreas group alone). No leak was documented in the atrophic pancreas group. This difference between the two groups was found to be statistically significant (p ≤ 0.00001). Conclusions: Atrophic pancreas in the preoperative CT scan may be protective against leakage after PD. These findings may help the surgeon to risk stratify patients accordingly. In addition, the findings suggest that patients with a preserved pancreas may require more protective methods to prevent leakage.

• Proceedings of the Korean Nuclear Society Conference
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.663-664
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.355-356
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• 2005

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2001년도 제21회 학술발표회 초록집
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• pp.115-115
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• 2001

• Transactions of the Korean Society of Pressure Vessels and Piping
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• 제9권1호
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• pp.62-69
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• 2013

A probabilistic assessment code, PRO-LOCA ver. 3.7 which was developed in an international co-operative research program, PARTRIDGE was evaluated by conducting sensitivity analysis. The effect of some variables such as simulation methods (adaptive sampling, iteration numbers, weld residual stress model), crack features(Poisson's arrival rate, maximum numbers of cracks, initial flaw size, fabrication flaws), operating and loading conditions(temperature, primary bending stress, earthquake strength and frequency), and inspection model(inspection intervals, detectable leak rate) on the failure probabilities of a surge line nozzle was investigated. The results of sensitivity analysis shows the remaining problems of the PRO-LOCA code such as the instability of adaptive sampling and unexpected trend of failure probabilities at an early stage.

• Journal of the Korean Society of Safety
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• 제30권5호
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• pp.123-130
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• 2015

Wolsong Unit 2,3&4 has been performing a containment integrity test during power operation. This test could impact to the safe operation during test. If an accident occurs during pressure dropping phase, reactor trip can be delayed because of the increased pressure difference which causes a time delay to reach the trip set-point. On the contrary, if an accident occurs during pressure increasing phase, reactor trip could be accelerated because the pressure difference to the trip set-point decrease. Point Lepreau nuclear power plant, which installed GCLMS (Gross Containment Leakage Monitoring System) in 1990, has discontinued the test since 1992 due to these adverse effects. Therefore, we evaluated the risk to obviate the GCLMS test based on PWR's ILRT (Integrated Leak Rate Test) extension methodologies. The results demonstrate that risk increase rate is not high in case of performing only ILRT test at every 5 years instead of doing GCLMS test at every 1.5 years. In addition, the result shows that GCLMS test can be removed on a risk-informed perspective since risk increasement is in acceptable area of regulatory acceptance criteria.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제21권2호
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• pp.297-304
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• 2012

Recently RFID (Radio Frequency Identification) technology advances in wireless communication technologies are bringing new challenges. But RFID tag packaging technology has been lagging compared to the demand, so this technology is being required to improve reliability. In this paper, reliability comparison among 11 types of most commonly used epoxy molding in electrical/electronic components packaging has been made through analysis of confidentiality using a humidity sensor. Consequently, the variation of moisture penetration time causes has been verified by the changes in molding thickness for 3 types of epoxy, and from the result, the best experimental results were observed in terms of confidentiality. Moreover we have been confirmed the relationship between confidentiality, the molding thickness, and thermal property of epoxy through thermal analysis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제16권1호
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• pp.9-16
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• 2017

This study describes the development of a 1-inch cryogenic glove valve for an LNG pumping system and localization development achieved through the performance test. The cryogenic valve used in the LNG pumping system plays an important role in maintaining a flow rate by LNG transportation. This trial manufactured goods, which was achieved through reverse engineering and developing the assembly process. The result of the leak test satisfied the internal pressure condition using the 78-bar normal temperature test and maintained the anti-leakage condition. Also, the result of the cryogenic leak test (BS 6364: low temperature test procedure) maintained anti-leakage at -196 and 52 bar, which satisfied the test standards.

• Proceedings of the SAREK Conference
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.36-41
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• 2008

Fault detection and diagnosis(FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. An experimental study has been performed on fault detection and diagnosis method for a water chiller. Bayes classifier, which is one of classical pattern classifiers, is adopted in deciding whether fault occurred or not. FDD algorithm can detect refrigerant leak failure, when 20% amount of charged refrigerant for normal operation leaks from the water chiller. The refrigerant leak failure caused COP reduction by 6.7% compared with normal operation performance. When two kinds of faults, such as a decrease in the mass flow rate of cooling water and temperature sensor fault of cooling water inlet, are detected, COP is a little decreased by these faults.