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IMPROVED HARMONIC INCOMPATIBILITY REMOVAL FOR SUSCEPTIBILITY MAPPING VIA REDUCTION OF BASIS MISMATCH

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Journal of Computational Mathematics 2022年第6期40卷 913-935页

作者： Chenglong Bao Jianfeng Cai jae kyu choi Bin Dong Ke Wei Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China Department of Mathematics The Hong Kong University of Science and TechnologyHongkongChina School of Mathematical Sciences Tongji UniversityShanghai 200092China Beijing International Center for Mathematical Research and Laboratory for Biomedical Image Analysis Beijing Institute of Big Data Research Peking UniversityBeijing 100871China School of Data Science Fudan UniversityShanghai 200433China

In quantitative susceptibility mapping(QSM),the background field removal is an essential data acquisition step because it has a significant effect on the restoration quality by generating a harmonic incompatibility in the measured local field *** though the sparsity based first generation harmonic incompatibility removal(1GHIRE)model has achieved the performance gain over the traditional approaches,the 1GHIRE model has to be further improved as there is a basis mismatch underlying in numerically solving Poisson’s equation for the background *** this paper,we propose the second generation harmonic incompatibility removal(2GHIRE)model to reduce a basis mismatch,inspired by the balanced approach in the tight frame based image *** results shows the superiority of the proposed 2GHIRE model both in the restoration qualities and the computational efficiency.

关键词： Quantitative susceptibility mapping Magnetic resonance imaging Deconvolution Partial differential equation Harmonic incompatibility removal (Tight)wavelet frames Sparse approximation

Smart Proactive Caching Scheme for Fast Authenticated Handoff in Wireless LAN

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Journal of Computer Science & Technology 2007年第3期22卷 476-480页

作者： Sin-kyu Kim jae-Woo choi Dae-Hun Nyang Gene-Beck Hahn Joo-Seok Song Electronics Telecommunications Research Institute Daejeon Korea Graduate School of Information Technology and Telecommunications Inha University IncheonKorea Mobile Communication Technology Research Lab LG Electronics AnyangKorea Department of Computer Science Yonsei University SeoulKorea

Handoff in IEEE 802.11 requires the repeated authentication and key exchange procedures, which will make the provision of seamless services in wireless LAN more difficult. To reduce the overhead, the proactive caching schemes have been proposed. However, they require too many control packets delivering the security context information to neighbor access points. Our contribution＇ is made in two-fold： one is a significant decrease in the number of control packets for proactive caching and the other is a superior cache replacement algorithm.

关键词： wireless local area network (LAN) security authentication simulation

Infrared-harvesting colloidal quantum dot inks for efficient photovoltaics: Impact of surface chemistry and device engineering

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Journal of Materials Science & Technology 2023年第16期147卷 224-240页

作者： Younghoon Kim Min-jae choi Jongmin choi Department of Chemistry Kookmin UniversitySeoul02707Republic of Korea Department of Chemical and Biochemical Engineering Dongguk UniversitySeoul04620Republic of Korea Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu42988Republic of Korea

Colloidal quantum dots(CQDs)are promising semiconducting materials,which can be used as a photoactive layer in various optoelectronic applications,because of their size-tunable bandgap energy,solution processability,and excellent optical and optoelectronic *** particular,these features have generated great interest in the development of CQD solar cells and led to a rapid increase in their power conversion *** improvements were enabled by many innovative approaches in terms of CQD’s surface chemistry and device architecture *** this review,a critical overview of the research progress in CQD solar cells is presented with a focus on the strategies adopted for achieving record efficiency in CQD solar *** strategies include the use of organic/inorganic surface ligands,pre-and post-treatment of CQDs,and solid-state/solution-phase ligand ***,we provide an understanding of the research history to inspire the rational design of next-generation CQD optoelectronic devices,such as solar cells,light-emitting diodes,and *** research on the development of infrared CQD solar cells as complementary platforms to other solar cell technologies is also critically discussed to provide another perspective on CQD technologies.

关键词： Quantum dot Lead sulfide Ligand exchange Colloidal ink Infrared light Solar cell

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

Expert recommendation system based on analyzing expertise and networks of human resources in National Science & Technology Information Service

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Journal of Central South University 2013年第8期20卷 2212-2218页

作者： YANG Myung-seok KANG Nam-kyu KIM Yun-jeong KIM jae-soo choi Kwang-nam KIM Young-kuk NTIS Center Korea Institute of Science and Technology Information Department Of Computer Science and Engineering Chungnam National University

This work aims to implement expert and collaborative group recommendation services through an analysis of expertise and network relations NTIS. First of all, expertise database has been constructed by extracting keywords after indexing national R＆D information in Korea （human resources, project and outcome） and applying expertise calculation algorithm. In consideration of the characteristics of national R＆D information, weight values have been selected. Then, expertise points were calculated by applying weighted values. In addition, joint research and collaborative relations were implemented in a knowledge map format through network analysis using national R＆D information.

关键词： human networks network analysis NTIS R&D information

Short-circuit Current Characteristics of Wind Generators

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电力系统自动化 2012年第8期36卷 110-114页

作者： Seung-jae LEE Myeon-Song choi Department of Electrical Engineering Myongji University

To study the effects of wind generators on distribution system protection,the short-circuit current(SCC) characteristics of wind generators is *** there are many researches on the issue,a clear agreement has not been reached so *** SCC characteristics for different wind generators are *** simulation is performed in the same system integrated with different kinds of wind generators,and their results are compared with those reported in IEEE *** detection possibility by overcurrent relay(OCR)is discussed based on the simulation results.

关键词：风力发电机组短路电流电流特性配电系统 PSCAD 过流继电器 IEEE 通过检测

Adsorption properties of polycarboxylate ether-based superplasticizer on cement particles and their resultant dispersion

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Frontiers of Structural and Civil Engineering 2022年第4期16卷 506-514页

作者： Jinyoung YOON Byoung Il choi jae Hong KIM Department of Structural Engineering Research Korea Institute of Civil Engineering and Building Technology(KICT)Goyang 10223Republic of Korea System Safety Research Department Korea Shipbuilding and Offshore EngineeringSeongnam 13591Republic of Korea Department of Civil and Environmental Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea

The cement dispersion performance of a polycarboxylate(PCE)-based superplasticizer is highly related to their adsorption behaviors as a function of *** study evaluated effects of PCEs on rheological properties of cementitious ***,characteristics of PCEs were characterized via permeation chromatography(GPC)and Fourier-transform infrared spectrometry(FT-IR).The adsorption behavior of single and blended PCEs on cementitious composites was identified using total organic carbon analyzer(TOC).Based on the measurement of PCE adsorption,the changes of rheological properties of cementitious materials as well as the number of dispersed cement particles were characterized using a rheometer and laser spectroscopy,*** experimental results support the systematic mechanism of PCE adsorption,cement dispersion,and the decrease in viscosity of cementitious materials.

关键词： adsorption polycarboxylate superplasticizer rheology dispersion

Toxocara optic neuropathy: clinical features and ocular findings

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International Journal of Ophthalmology(English edition) 2018年第3期11卷 520-523页

作者： Kwang-Dong choi jae-Hwan choi Seo-Young choi jae Ho Jung Department of Neurology Pusan National University Hospital Medical Research Institute Pusan National University Department of Neurology Pusan National University Yangsan Hospital Department of Ophthalmology Pusan National University Yangsan Hospital Research Institute for Convergence of Biomedical Science and Technology Pusan National University Yangsan Hospital

We evaluated thirteen eyes of twelve patients diagnosed clinically and serologically with Toxocara optic neuropathy. Eleven patients had unilateral involvement and one patient had bilateral optic neuropathy. Eight patients （66.7%） had a possible infection source to Toxocara. Six patients （50%） had painless acute optic neuropathy. Ten eyes had asymmetric, sectorial optic disc edema with peripapillary infiltration and three eyes had diffuse optic disc edema. Eosinophilia was noted in five patients （41.7%） and optic nerve enhancement was observed in eight of eleven eyes （72.7%） with available orbit magnetic resonance imaging （MRI）. Mean visual acuity significantly improved following treatment [mean logarithmic of the minimum angle of resolution （IogMAR） 0.94±0.56 at baseline and 0.47±0.59 at the final （P=0.02）]. Asymmetric optic disc edema with a peripapillary lesion and a history of raw meat ingestion were important clues for diagnosing Toxocara optic neuropathy. Additionally, Toxocara IgG enzymelinked immunosorbent assay （ELISA） test and evaluating eosinophil may be helpful for diagnosis.

关键词： optic neuropathy toxocariasis ocular toxocariasis Toxocara optic neuropathy

Early extrahepatic recurrence as a pivotal factor for survival after hepatocellular carcinoma resection:A 15-year observational study

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World Journal of Gastroenterology 2022年第36期28卷 5351-5363页

作者： jae Hyun Yoon Sung kyu choi Sung Bum Cho Hee Joon Kim Yang Seok Ko Chung Hwan Jun Department of Gastroenterology and Hepatology Chonnam National University Hospital and College of MedicineGwangju 61469South Korea Department of Gastroenterology and Hepatology Hwasun Chonnam National University Hospital and College of MedicineHwasun 58128South Korea Department of Surgery Chonnam National University Hospital and College of MedicineGwangju 61469South Korea Department of Surgery Hwasun Chonnam National University Hospital and College of MedicineHwasun 58128South Korea Department of Internal Medicine Mokpo Hankook HospitalMokpo 58643South Korea

BACKGROUND Surgical resection is one of the most widely used modalities for the treatment of hepatocellular carcinoma(HCC).Early extrahepatic recurrence(EHR)of HCC after surgical resection is considered to be closely associated with poor ***,data regarding risk factors and survival outcomes of early EHR after surgical resection remain *** To investigate the clinical features and risk factors of early EHR and elucidate its association with survival *** From January 2004 to December 2019,we enrolled treatment-naïve patients who were≥18 years and underwent surgical resection for HCC in two tertiary academic *** excluding patients with tumor types other than HCC and/or ineligible data,this retrospective study finally included 779 *** resection of HCC was performed according to the physicians’decisions and the EHR was diagnosed based on contrast-enhanced computed tomography or magnetic resonance imaging,and pathologic confirmation was performed in selected *** Cox regression analysis was performed to identify the variables associated with *** Early EHR within 2 years after surgery was diagnosed in 9.5%of patients during a median followup period of 4.4 *** recurrence-free survival period was 5.2 mo,and the median time to EHR was 8.8 mo in patients with early *** 52.7%of patients with early EHR,EHR occurred as the first recurrence of HCC after surgical *** multivariate analysis,serum albumin100 U/L,surgical margin involvement,venous and/or lymphatic involvement,satellite nodules,tumor necrosis detected by pathology,tumor size≥7 cm,and macrovascular invasion were determined as risk factors associated with early *** sub-categorizing the patients according to the number of risk factors,the rates of both EHR and survival showed a significant correlation with the risk of early ***,multivariate analysis revealed that early E

关键词： Early extrahepatic recurrence Hepatocellular carcinoma Prognosis Surgery Survival