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Optimal Checkpoint Placement on Real-Time Tasks with Harmonic Periods

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Journal of Computer Science & Technology 2012年第1期27卷 105-112页

作者： seong woo Kwak Jung-Min Yang Department of Electronic Engineering Keimyung University Department of Electrical Engineering Catholic University of Daegu

This paper presents an optimal checkpoint strategy for fault-tolerance in real-time systems where transient faults occur in Poisson distribution. In our environment, multiple real-time tasks with different deadlines and harmonic periods are scheduled in the system by rate-monotonic algorithm, and checkpoints are inserted at a constant interval in each task. When a fault is detected, the system carries out rollback to the latest checkpoint and re-executes tasks. The maximum number of re-executable checkpoints and an equation to check schedulability are derived, and the optimal number of checkpoints is selected to maximize the probability of completing all the tasks within their deadlines.

关键词： checkpoint scheme real-time system fault-tolerance harmonic period rate-monotonic (RM) scheduling

Mo and Ta addition in NbTiZr medium entropy alloy to overcome tensile yield strength-ductility trade-off

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Journal of Materials Science & Technology 2022年第14期109卷 176-185页

作者： Muhammad Akmal Hyun woo seong Ho Jin Ryu Department of Materials Science and Engineering KAISTDaejeonYuseong-gu 34141South Korea Department of Nuclear and Quantum Engineering KAISTDaejeonYuseong-gu 34141South Korea

In this study,single-phase NbTiZr and NbTiZr(MoTa)_(0.1) medium-entropy alloys(MEAs)were investigated for their use in biomedical *** alloys were prepared by arc melting,and were then cold-rolled,annealed,and characterized in terms of phase analysis,mechanical properties,fractography,and wear *** alloys showed a single body-centered cubic phase with superior mechanical,and tribological properties compared to commercially available biomedical *** and Ta-containing MEAs showed higher tensile yield strength(1060±18 MPa)and higher tensile ductility(~20%),thus overcoming the strength-ductility trade-off with no signs of transformation-induced plasticity,twinning,or *** generalized stacking fault energy(GSFE)calculations on the{112}slip system by the first-principles calculations based on density functional theory showed that the addition of less than0.2 molar fraction of Mo and Ta lowers the GSFE *** behavior posits the increase in ductility of the alloy by facilitating slips although strength is also increased by solid solution *** wear resistance of both alloys against hardened steel surfaces was superior to that of commercial biomedical ***,we concluded that NbTiZr(MoTa)_(0.1)MEA with good tensile ductility is a potential candidate for biomedical implants.

关键词： Medium-entropy alloys Wear-resistant Biomedical implants Solid solution hardening Staking fault energy

Optimal treatment strategy for Helicobacter pylori:Era of antibiotic resistance

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World Journal of Gastroenterology 2014年第19期20卷 5654-5659页

作者： Jun Heo seong woo Jeon Department of Internal Medicine Kyungpook National University Hospital Medical CenterDaegu 702-911South Korea

Standard triple therapy, consisting of a proton pump inhibitor, plus amoxicillin and clarithromycin, has been the most commonly used first-line treatment regimen for Helicobacter pylori (H. pylori) eradication for many years worldwide. However, as a result of increased resistance to antibiotics, H. pylori eradication rates with use of standard triple therapy have been declining and recently reached < 80% in many countries. Several new strategies to enhance the eradication rate of H. pylori have been studied. Currently, among the alternative first-line eradication regimens, concomitant and hybrid regimens have shown excellent results and could be the optimal treatment option. Although clinical usefulness of rescue therapy for patients in whom eradication of H. pylori with non-bismuth quadruple regimen has failed is unclear, levofloxacin-based quadruple therapy has shown promise as a rescue treatment. The choice of third-line therapy depends on factors such as the local pattern of antibiotic resistance, drug availability, and previous treatment. We hope that a simple method for detection of antibiotic susceptibility using polymerase chain reaction would be a possible alternative to administration of “tailored treatment” in the era of increasing prevalence of antimicrobial resistance.

关键词： Helicobacter pylori Standard therapy Bacterial eradication Concomitant therapy Hybrid therapy

Grade-4 commercially pure titanium with ultrahigh strength achieved by twinning-induced grain refinement through cryogenic deformation

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Journal of Materials Science & Technology 2021年第7期66卷 193-201页

作者： seong-woo Choi Jae Sukjeong Jong woo Won Jae Keun Hong Yoon Suk Choi Titanium Department.Korea Institute of Materials Science Changwon51508Republic of Korea School of Materials Science and Engineering Pusan National UniversityPusan.46241Republic of Korea Materials and Manufacturing Development Team Doosan Heavy Industries and ConstructionChangwon51711Republic of Korea

The yield strength of commercially pure(CP) Ti of ASTM grade 4, the strongest among all the CP-Ti grades, is too low for structural applications that require high-strength materials. Here, we demonstrate the strengthening of grade-4 CP Ti by cryogenic-temperature rolling(CTR), which enables deformation twinning in grade-4 CP Ti to achieve twinning-induced grain refinement. CTR activated {11.22} twinning and {10.12} twinning, which are the most common twinning systems in pure Ti, whereas room-temperature rolling(RTR) did not activate any twinning system. CTR with imposing an area reduction of just 30% significantly increased the yield strength of the CP Ti to 946 MPa, which is not achievable through typical processes performed at or above room temperature and is comparable to that of commercial Ti-6 Al-4 V. The significant increase in strength was due to microstructural strengthening caused by twinning-induced grain refinement, combined with dislocation accumulation. In contrast to RTR, CTR greatly increased the stress concentration at grain boundaries(GBs), which caused the unusual activation of twinning in the grade-4 CP Ti by facilitating twin nucleation at GBs. The stress concentration increased because CTR activated the slip to a lesser extent compared to RTR, thereby reducing the strain compatibility between neighboring grains. These results will contribute to development of ultrahigh-strength CP Ti and may thereby extend its use to structural applications that require high-strength materials.

关键词： Titanium Twinning Cryogenic deformation Grain refinement Tensile properties

Checkpoint Management with Double Modular Redundancy Based on the Probability of Task Completion

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Journal of Computer Science & Technology 2012年第2期27卷 273-280页

作者： seong woo Kwak Kwan-Ho You Jung-Min Yang Department of Electronic Engineering Keimyung University School of Information & Communication Engineering Sungkyunkwan University Department of Electrical Engineering Catholic University of Daegu

This paper proposes a checkpoint rollback strategy for real-time systems with double modular *** built-in fault-detection and spare processors,our scheme is able to recover from both transient and permanent *** comparisons are conducted at each ***,the states stored in two consecutive checkpoints of one processor are compared for checking integrity of the *** states of two processors are also compared for detecting faults and the system rolls back to the previous checkpoint whenever required by logic of the proposed scheme.A Markov model is induced by the fault recovery scheme and analyzed to provide the probability of task completion within its *** optimal number of checkpoints is selected so as to maximize the probability of task completion.

关键词： checkpoint scheme double modular redundancy (DMR) real-time task fault tolerance Markov model

Duplication of the common bile duct manifesting as recurrent pyogenic cholangitis:A case report

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World Journal of Gastroenterology 2021年第4期27卷 371-376页

作者： Jun seong Hwang Sung woo Ko Internal Medicine Inje University Haeundae Paik HospitalInje College of MedicineBusan 48108South Korea Internal Medicine Eunpyeong St.Mary's HospitalCatholic University of KoreaSeoul 03312South Korea

BACKGROUND Duplication of the extrahepatic bile duct(DCBD)is an extremely rare congenital anomaly of the biliary *** are five types of DCBD according to the latest *** them,Type V is characterized by single drainage of the extrahepatic bile *** on DCBD Type V are *** SUMMARY A 77-year-old woman presented with recurrent epigastric pain but without fever or *** tomography revealed a dilated common bile duct(CBD)that harboured multiple *** retrograde cholangiopancreatography(ERCP)was performed,and the stones were extracted using a Dormia *** was discharged without any complications;however,she visited the emergency department a day after she was discharged due to epigastric pain and *** findings were suggestive of *** urgent ERCP for stone removal,magnetic resonance cholangiopancreatography was performed to evaluate remnant *** resonance cholangiopancreatography revealed a DCBD Type Va and remnant choledocholithiasis in the right *** CBDs were accessed,and the stones were cleared successfully during a subsequent *** In this article,we report an extremely rare case of DCBD manifesting as recurrent pyogenic *** case highlights the importance of recognizing DCBD because stones in the unrecognized bile duct could make the patient’s prognosis critical.

关键词： Double common bile duct Common bile duct disease Choledocholithiasis Cholangitis Endoscopic retrograde cholangiopancreatography Case report

Suggestion of advanced regression model on friction angle of fault gouge in South Korea

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第6期13卷 1368-1379页

作者： seong-woo Moon Hyun-Seok Yun Yong-Seok Seo Department of Earth and Environmental Sciences Chungbuk National University1 Chungdae-roCheongju-siChungcheongbuk-do28644South Korea

Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than those of soils or rocks due to its high heterogeneity and low ***,to improve the accuracy of analysis results,we conducted simple regression analysis and structural equation model analysis and selected major influential factors of friction characteristics among many factors,and then we deduced advanced regression model with the highest coefficient of determination(R^(2)) via multiple regression *** most coefficients of determination in simple regression analysis are below0.3-0.4,coefficient of determination in multiple regression analysis is remarkably large as 0.657.

关键词： Fault gouge Friction angle Simple regression analysis Structural equation model analysis Multiple regression analysis

Endoscopic resection of co-existing severe dysplasia and a small esophageal leiomyoma

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World Journal of Gastroenterology 2013年第1期19卷 137-140页

作者： Sun Young Ahn seong woo Jeon Division of Gastroenterology and Hepatology Department of Internal MedicineKyungpook National University HospitalDaegu 700-721South Korea

Leiomyoma is the most common benign mesenchymal tumor of the esophagus.A small leiomyoma covered with endoscopically normal mucosa has a characteristic endoscopic ultrasonographic appearance,slow growth rate,and negligible risk of malignant transformation;therefore the histology does not need to be *** tumors such as an epithelial tumor and small subepithelial tumor in the upper gastrointestinal tract are *** describe a case with a coexisting small leiomyoma and severe dysplasia in the esophagus which were completely resected by endoscopic mucosal resection.

关键词： Synchronous tumor Leiomyoma Dysplasia

Comparison of ring 1 parameters in 37-segment multifocal electroretinography between onset and offset conditions of ring 2 to 4 in normal subjects

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International Journal of Ophthalmology(English edition) 2019年第1期12卷 73-78页

作者： Jun Ho Yoo Cheolmin Yun Jaeryung Oh seong-woo Kim Department of Ophthalmology Korea University College of Medicine

AIM: To investigate whether the response of a central hexagonal element corresponding to the macular area in conventional multifocal electroretinography(mfERG) tests was the same as that of experimental mfERG using single central hexagonal element stimulation. METHODS: Prospective, observational study. Thirty healthy subjects were included in this study. mfERG recordings were performed according to two protocols: stimulus with 37 hexagonal elements(protocol 1), and stimulus with a single central element created by deactivating the other 36 hexagonal elements(protocol 2). We compared differences between ring 1 parameters in each protocol. RESULTS: In protocol 1, the first positive component(P1) implicit time and P1 amplitude were 37.8±1.8 ms and 6.3±2.7 μV. After single element stimulation(protocol 2), double positive waves appeared. The implicit time and amplitude of P1 were 40.7±2.4 ms(P<0.001) and 9.1±3.3 μV(P=0.001), respectively. The implicit time and amplitude of the second positive component(P2) were 68.0±4.5 ms(P<0.001, compared with P1 in protocol 1) and 12.3±4.7 μV(P<0.001, compared with P1 in protocol 1), respectively. The amplitude of P2 in protocol 2 was about two times higher than that of P1 in protocol 1. CONCLUSION: mfERG responses of a central hexagonal element in a single element stimulation protocol are different from those of multiple element stimulation. The positive wave is more enhanced compared to that of the conventional protocol and it elongated into two wavelets.

关键词： multifocal electroretinography focal electroretinography macular function single element stimulation stray light effect