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Retraction control of motorized seat belt system with linear state observer

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Journal of Central South University 2013年第2期20卷 385-392页

作者： LEE Kang-seok choi Chin-chul LEE woo-taik Department of Control and Instrumentation Engineering Changwon National University

A design and verification of linear state observers which estimate state information such as angular velocity and load torque for retraction control of the motorized seat belt (MSB) system were described. The motorized seat belt system provides functions to protect passengers and improve passenger's convenience. Each MSB function has its own required belt tension which is determined by the function's purpose. To realize the MSB functions, state information, such as seat belt winding velocity and seat belt tension are required. Using a linear state observer, the state information for MSB operations can be estimated without sensors. To design the linear state observer, the motorized seat belt system is analyzed and represented as a state space model which contains load torque as an augmented state. Based on the state space model, a linear state observer was designed and verified by experiments. Also, the retraction control of the MSB algorithm using linear state observer was designed and verified on the test bench. With the designed retraction control algorithm using the linear state observer, it is possible to realize various types of MSB functions.

关键词： motorized seat belt system motorized seat belt (MSB) system linear state observer state space model augmented state retraction control

Potential risk factors for nonalcoholic steatohepatitis related to pancreatic secretions following pancreaticoduodenectomy

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World Journal of Gastroenterology 2011年第32期17卷 3716-3723页

作者： Sun Choon Song Seong Ho choi Dong wook choi Jin seok Heo woo seok Kim Min Jung Kim Department of Surgery Samsung Medical Center Sungkyunkwan University School of Medicine

AIM: To identify risk factors for nonalcoholic steatohepatitis following pancreaticoduodenectomy, with a focus on factors related to pancreatic secretions. METHODS: The medical records of 228 patients who had a pancreaticoduodenectomy over a 16-mo period were reviewed retrospectively. The 193 patients who did not have fatty liver disease preoperatively were included in the final analysis. Hepatic steatosis was diagnosed using the differences between splenic and hepatic attenuation and liver-to-spleen attenuation as measured by non-enhanced computed tomography. RESULTS: Fifteen patients (7.8%) who showed postoperative hepatic fatty changes were assigned to Group A, and the remaining patients were assigned to Group B. Patient demographics, preoperative laboratory findings (including levels of C-peptide, glucagon, insulin and glucose tolerance test results), operation types, and final pathological findings did not differ significantly between the two groups; however, the frequency of pancreatic fistula (P = 0.020) and the method of pancreatic duct stenting (P = 0.005) showed significant differences between the groups. A multivari- ate analysis identified pancreatic fistula (HR = 3.332, P = 0.037) and external pancreatic duct stenting (HR = 4.530, P = 0.017) as independent risk factors for the development of postoperative steatohepatitis. CONCLUSION: Pancreatic fistula and external pancreatic duct stenting were identified as independent risk factors for the development of steatohepatitis following pancreaticoduodenectomy.

关键词： Nonalcoholic fatty liver diseases Nonalcoholic steatohepatitis Pancreatic duct stenting Pancreatic fistula Pancreatic surgery

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

Highly efficient and stable solid-state fiber dye-sensitized solar cells with Ag-decorated SiO_(2) nanoparticles

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Nano Research 2021年第8期14卷 2728-2734页

作者： Jae Ho Kim seok-Ju Yoo Daseul Lee Jin woo choi Sang-Cheol Han Tae In Ryu Hyung woo Lee Myunghun Shin Myungkwan Song Materials Center for Energy Convergence Korea Institute of Materials Science(KIMS)797Changwon-daeroSungsan-guChangwonGyeongsangnam-do51508Republic of Korea CEN Nano.Co.Ltd. Nano Convergence CenterMuan-roBuduk-myeonMiryang-siGyeongsangnam-do50404Republic of Korea Accident Coordination and Training Division National Institute of Chemical Safety(NICS)90Gajeongbuk-roYuseong-guDaejeon34114Republic of Korea Department of Nanoenergy Engineering and Research Center of Energy Convergence Technology Pusan National UniversityBusandaehak-ro 63-2Geumjeong-guBusan 46241Republic of Korea School of Electronics and Information Engineering Korea Aerospace University Goyang-cityGyeonggi-do10540Republic of Korea

Fiber-shaped dye-sensitized solar cells(FDSSCs)represent promising futuristic flexible or wearable power sources,owing to their simple fabrication process,light weight,weavability,and *** with strategies on changing the properties of semiconductor materials,the effects of incorporating silver-embedded SiO_(2) nanoparticles(Ag@SiO_(2)NPs)on the photoanodes of solid-state FDSSCs(SS-FDSSCs)are *** power conversion efficiency(PCE)of SS-FDSSCs with Ag@SiO_(2) NPs reaches 5.38%,which is comparable to the reference(3.98%).The PCEs remain at 95%between-16.9 and 91.7℃,indicating the operational stability of SS-FDSSCs within this temperature *** fabricated SS-FDSSCs,whose radii were 2 mm,maintains more than 90%of their efficiency over 500 bending cycles and 10 washing cycles.

关键词： dye-sensitized solar cells fiber-shaped solar cells SiO_(2)nanoparticles plasmonic effect solid-state electrolyte

Paradoxical vocal fold motion masquerading as post-anesthetic respiratory distress:A case report

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World Journal of Clinical Cases 2023年第10期11卷 2349-2354页

作者： Jongyoon Baek Dae-Lim Jee Yoon seok choi Sang woo Kim Eun Kyung choi Department of Anesthesiology and Pain Medicine Yeungnam University College of MedicineDaegu 42415South Korea Department of Otorhinolaryngology-Head and Neck Surgery Yeungnam University College of MedicineDaegu 42415South Korea Department of Neurosurgery Yeungnam University College of MedicineDaegu 42415South Korea

BACKGROUND Functional vocal cord disorders can be a differential diagnosis for postoperative upper airway obstruction requiring urgent ***,this may be unfamiliar to anesthesiologists who would favor inappropriate airway intervention and increased *** SUMMARY A 61-year-old woman underwent cervical laminectomy,followed by laparoscopic cholecystectomy 10 mo *** adequate reversal of neuromuscular blockade,the patient experienced repetitive respiratory difficulty with inspiratory stridor after *** the second operation,the patient was diagnosed with paradoxical vocal fold motion(PVFM)by an otolaryngologist based on the clinical features and fiberoptic bronchoscopy results,and the patient was successfully *** PVFM should be considered a differential diagnosis if a patient presents with stridor after general anesthesia.

关键词： Anesthesiology Vocal fold Paradoxical motion Postoperative respiratory distress Case report

Effect of change of sand properties on travel distance of ricocheted debris

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Defence Technology（防务技术） 2021年第4期17卷 1486-1495页

作者： Yoon Keon Kim woo Chun choi Department of Mechanical Engineering Korea University145 Anam-roSeongbuk-guSeoul02841Republic of Korea

The debris from exploded buildings can ricochet after colliding with the ground,thus increasing the debris travel distance and danger from any associated impacts or *** reduce this danger,the travel distance of ricocheted debris must be accurately *** study analyzed the change in the travel distance of ricocheted concrete debris relative to changes in the properties of a sand *** shear tests were conducted to measure the change in internal friction angle as a function of temperature and water content of the *** element analysis(FEA)was then applied to these variables to predict the speed and angle of the debris after *** FEA results were compared with results of low-speed ricochet experiments,which employed variable temperature and water *** travel distance of the debris was calculated using MATLAB,via trajectory equations considering the drag *** the internal friction angle decreased,the shear stress decreased,leading to deeper penetration of the debris into the *** the loss of kinetic energy increased,the velocity and travel distance of the ricocheted debris *** in the ricochet velocity and travel distance of the debris,according to changes in the internal friction angle,indicated that the debris was affected by the environment.

关键词： Ricochet Exploded debirs Environmental change Sand Temperature Water content Internal friction angle Travel distance

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

Characteristics of machined surface controlled by cutting tools and conditions in machining of brittle material

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中国有色金属学会会刊：英文版 2009年第B9期19卷 194-201页

作者： Yong-woo KIM Soo-Chang choi Jeung-woo PARK Deug-woo LEE Department of Nano Fusion Technology Pusan National University Department of Mechanical Design Engineering Chosun University Department of Nanosystem and Nanoprocess Engineering Pusan National University

One of the ultra-precision machining methods was adapted for brittle material as well as soft material by using multi-arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because the particles of grinding tools are irregular size and material can be fragile. Therefore, we were able to design tool paths and machine controlled pattern on surface by multi-arrayed diamond tips with uniform size made in MEMS fabrication and high speed spindle, and the maximum speed was about 3×105 r/min. We defined several parameters that can affect the machining surface. Those were multi-array of diamond tips (n×n), speed of air spindle and feeding rate. The surface roughness and surface texture can be controlled by those parameters for micro machining.

关键词：加工表面脆性材料条件控制刀具路径表面粗糙度特征高速主轴加工方法

Effect of expanding nanocellulose sponge on nasal mucosal defects in an animal model

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Regenerative Biomaterials 2020年第1期7卷 47-52页

作者： JiWon Kim Kyungbae woo Jeong Mi Kim Mi Eun choi Young-Mo Kim Su-Geun Yang Bong Sup Shim Jeong-seok choi Department of Otorhinolaryngology Inha UniversityCollege of Medicine27 Inhang-roJung-guIncheon 22332Republic of Korea Department of Chemical Engineering Inha University100 InharoMichuholguIncheon 22212Republic of Korea Department of New Drug Development Inha UniversityCollege of MedicineB-308Chungsuk Bldg.366Seohae-DaeroJung-GuIncheon 22332Republic of Korea

Nanocellulose has emerged for a wide range of applications in biomedical engineering because of its water absorption capacity,appropriate *** investigated the hemostatic and regenerative abilities of an expanding polyvinyl alcohol(PVA)-nanocellulose sponge on nasal mucosal defects.A 3 mm-diameter nasal defect was made in experimental *** were divided into four groups with control,vaseline,PVA and PVA-nanocellulose packing *** the defect was created,bleeding times and amounts were *** materials were removed on experimental day(ED)*** ED 3,7 and 14,histological analysis and immunohistochemical study for neutrophils were *** cells were counted and epithelial thicknesses were *** amounts and times in the vaseline packing group were smaller than in the PVA ***-nanocellulose group showed less neutrophils than in the other groups on ED *** epithelium thickness in the PVA-nanocellulose group was significantly smaller than in the control group at ED 7,but at ED 14,there was no significant intergroup *** group had a significant lower inflammatory cell count than the control group on ED ***-nanocellulose sponge applied to nasal mucosal defects can significantly enhance mucosal regeneration during early wound healing.

关键词： polyvinyl alcohol nasal mucosa nanocellulose