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A unified formulation of optimal guidance-to-collision law for accelerating and decelerating targets

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Chinese Journal of Aeronautics 2022年第7期35卷 40-54页

作者： Young-Won kim Boseok kim chang-Hun LEE Shaoming HE Department of Aerospace Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

This paper provides a unified formulation of optimal guidance-to-collision law for a target with an arbitrary acceleration or *** collision course for general target acceleration or deceleration is first determined from the engagement geometry in conjunction with the nonlinear engagement kinematics in the proposed *** heading error defined in the collision course is then adopted as a variable to be nullified for accomplishing the intercept *** proposed guidance law is derived based on the heading error dynamics and the optimal error dynamics to ensure optimality and finite-time *** illustrative examples,the proposed guidance command for a constant target acceleration and a target deceleration in the form of a quadratic function of speed are ***,the time-to-go prediction method is suggested for implementing the proposed *** characteristics of the proposed guidance command are analytically investigated to provide insight into the proposed *** key benefits of the proposed method lie in not producing unnecessary guidance commands near a target compared to other methods and ensuring optimality in guidance command even in the nonlinear engagement ***,numerical simulations are performed to validate the proposed method and to show our findings.

关键词： Guidance-to-collision law Optimal guidance Optimal error dynamics Target acceleration or deceleration Unified formulation

Hepatocellular carcinoma presenting as organized liver abscess:A case report

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World Journal of Clinical Cases 2023年第33期11卷 8078-8083页

作者： Sung Hyeok Ryou Hyun deok Shin Suk Bae kim Department of Internal Medicine Dankook University College of MedicineCheonan 31116ChungnamSouth Korea

BACKGROUND Hepatocellular carcinoma(HCC)is difficult to treat and has a high mortality rate,emphasizing the importance of early diagnosis and *** characteristic radiologic findings and underlying liver disease are present,a diagnosis can be made without a ***,when HCC is accompanied by a liver abscess,diagnosis might be delayed by atypical radiologic *** case report aims to assist in the diagnosis of HCC,which can manifest in various *** SUMMARY A 75-year-old male presented to the Emergency Department with worsening fever and mental *** was diagnosed with liver cirrhosis six months *** computed tomography(CT)raised our suspicion of an organized liver abscess.A follow-up CT scan after four weeks of antibiotic treatment showed a decrease in the liver lesion ***,high fever recurred,and C-reactive protein increased to 14 mg/*** of the liver lesion was performed,but no bacteria were *** culture revealed the presence of *** patient received an additional four weeks of antibiotics and antifungal agents before being *** 10 mo later,a CT scan showed an increase in the lesion size,and biopsy was *** biopsy revealed an organized abscess with focal carcinomatous changes,for which surgery was *** histopathological examination revealed HCC,clear-cell *** nontumor liver tissue showed cirrhosis and an organized *** Even if a liver abscess is suspected in a patient with cirrhosis,the possibility of HCC should be considered.

关键词： Liver abscess Hepatocellular carcinoma Infection Diagnosis Case report

InGaAsP/InP DH Ridge Waveguide Phase Modulator with High Modulation Efficiency

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光学学报 2003年第S1期23卷 289-290页

作者： Young Tae Byun Hwa Sun Park Sung Jin kim deok Ha Woo Jong chang Yi Yoshiaki Nakano Photonics Research Center Korea Institute of Science and Technology Seoul Korea School of Electronics and Electrical Engineering Hong Ik University Seoul Korea Research Center for Advanced Science and Technology University of Tokyo Tokyo Japan

The P-p-n-N InGaAsP/InP ridge waveguide phase modulator has been fabricated and investigated at a wavelength of 1550nm. The phase modulation efficiency measured by the Fabry-Perot resonance method is as high as 34°/V... 详细信息

关键词： phase modulation ridge waveguide

Accurate Multi-Site Daily-Ahead Multi-Step PM_(2.5)Concentrations Forecasting Using Space-Shared CNN-LSTM

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Computers, Materials & Continua 2022年第3期70卷 5143-5160页

作者： Xiaorui Shao chang Soo kim Department of Information Systems Pukyong National UniversityBusan608737Korea

Accurate multi-step PM_(2.5)(particulate matter with diameters≤2.5 um)concentration prediction is critical for humankinds’health and air populationmanagement because it could provide strong evidence for ***,it is very challenging due to its randomness and *** paper proposed a novel method based on convolutional neural network(CNN)and long-short-term memory(LSTM)with a space-shared mechanism,named space-shared CNN-LSTM(SCNN-LSTM)for multi-site dailyahead multi-step PM_(2.5)forecasting with self-historical *** proposed SCNN-LSTM contains multi-channel inputs,each channel corresponding to one-site historical PM_(2.5)concentration *** which,CNN and LSTM are used to extract each site’s rich hidden feature representations in a stack ***,CNN is to extract the hidden short-time gap PM_(2.5)concentration patterns;LSTM is to mine the hidden features with long-time *** channel extracted features aremerged as the comprehensive features for future multi-step PM_(2.5)concentration ***,the space-shared mechanism is implemented by multi-loss functions to achieve space information ***,the final features are the fusion of short-time gap,long-time dependency,and space information,which enables forecasting more *** validate the proposed method’s effectiveness,the authors designed,trained,and compared it with various leading methods in terms of RMSE,MAE,MAPE,and R^(2)on four real-word PM_(2.5)data sets in Seoul,South *** massive experiments proved that the proposed method could accurately forecast multi-site multi-step PM_(2.5)concentration only using self-historical PM_(2.5)concentration time series and running ***,the proposed method obtained averaged RMSE of 8.05,MAE of 5.04,MAPE of 23.96%,and R^(2)of 0.7 for four-site daily ahead 10-hourPM_(2.5)concentration forecasting.

关键词： PM_(2.5)forecasting CNN-LSTM air quality management multi-site multi-step forecasting

Dynamic PIV Measurement of a Compressible Flow Issuing from an Airbag Inflator Nozzle

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Journal of Thermal Science 2006年第4期15卷 377-381页

作者： SangJoonLee YoungGilJang Seokkim chang Soo kim Department of Mechanical Engineering POSTECHSan 31Hyoja DongPohang790-784Korea Safety System R&D Department Hyundai MOBIS80-10Mabook-RiGuseong-EupYongin-ShiGyunggi-Do449-910Korea

Among many equipment for passenger safety, the air bag system is the most fundamental and effective device for an automobile. The inflator housing is a main part of the curtain-type air bag system, which supplies high-pressure gases in pumping up the air bag-curtain which is increasingly being adapted in deluxe cars for protecting passengers from the danger of side clash. However, flow information on the inflator housing is very limited. In this study, we measure the instantaneous velocity fields of a high-speed compressible flow issuing from the exit nozzle of an inflator housing using a dynamic PIV system. From the velocity field data measured at a high frame-rate, we evaluate the variation of the mass flow rate with time. The dynamic PIV system consists of a high-repetition Nd：YLF laser, a high-speed CMOS camera, and a delay generator. The flow images are taken at 4000 fps with synchronization of the trigger signal for inflator ignition. From the instantaneous velocity field data of flow ejecting from the airbag inflator housing at the initial stage, we can see a flow pattern of broken shock wave front and its downward propagation. The flow ejecting from the inflator housing is found to have very high velocity fluctuations, with the maximum velocity at about 700 m/s. The time duration of the high-speed flow is very short, and there is no perceptible flow after 100 ms.

关键词： Airbag inflator PIV automobile.

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自适应正则化滤波化极方法研究

地球物理学报 2024年第3期67卷 1255-1272页

作者：何涛王皓张义蜜王万银 Colin G.Farquharson J.kim Welford 长安大学地质工程与测绘学院西安710054 海洋油气勘探国家工程研究中心北京100028 中国科学院海洋地质与环境重点实验室山东青岛266071 Department of Earth Sciences Memorial University of NewfoundlandSt.John'sAlB 3X5Canada

化极是消除磁力异常斜磁化影响的关键步骤,可以在波数域(频率域)和空间域中实现.相比于空间域,在波数域(频率域)进行化极简单且高效,但在低纬度地区存在不稳定性问题,因此明确低纬度地区的范围,研究稳定、实用、精度高的低纬度地区化极... 详细信息

化极是消除磁力异常斜磁化影响的关键步骤,可以在波数域(频率域)和空间域中实现.相比于空间域,在波数域(频率域)进行化极简单且高效,但在低纬度地区存在不稳定性问题,因此明确低纬度地区的范围,研究稳定、实用、精度高的低纬度地区化极方法具有重要意义.本文通过理论研究得出化极因子振幅的最大值为2时,对应的磁化倾角的值为±45°,当磁化倾角在该范围内时,引起化极不稳定.因此采用正则化思想,提出了自适应正则化滤波化极方法(ARF-RTP),该方法利用化极因子振幅构建正则化滤波函数,并以振幅值等于2作为约束计算化极方法的参数值,从而实现自适应化极处理,提高了化极方法的稳定性及实用性.同时结合迭代算法提高了此方法的精度,有效地解决了低纬度地区化极的不稳定性问题.自适应正则化滤波这一思想不但可以解决化极的不稳定性问题,而且可以解决分量转换或者磁化方向转换的不稳定性问题以及类似数据处理中的不稳定性问题,具有广阔的推广应用前景.

关键词：化极低纬度地区振幅自适应正则化滤波迭代算法

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Grain size dependence of flow stress in ECAPed Ti with constant texture

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中国有色金属学会会刊：英文版 2012年第S3期22卷 673-677页

作者： chang-Young HYUN Ho-Kyung kim Department of Materials Science and Engineering Seoul National University of Science and Technology Department of Automotive Engineering Seoul National University of Science and Technology

The effect of grain size on the flow stress in an ECAPed Ti with a constant texture was investigated,assuming that 2,4,5 and 6 passes microstructures have a similar *** average size of recrystallized grains decreased to 0.5 μm,0.4 μm,and 0.3 μm with respect to the ECAP pass number of 2,4,and 6,*** ultimate tensile strength (UTS) and yield strength (YS) increase with an increase in the number of *** UTS and YS of the 6 passes ECAPed sample were found to be 740.2 MPa and 580.3 MPa,*** equation for the flow stress of an ECAPed Ti with a constant texture as a function of the strain and grain size was derived for the ECAPed *** following equation was finally obtained:σ(ε)=103.9+1825ε-9.6ε1/2·d-1/2+8.3d-1/2.

关键词： Ti mechanical properties grain size flow stress equal channel angular pressing

Morbidity analysis of left hepatic trisectionectomy for hepatobiliary disease and live donor

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Hepatobiliary & Pancreatic Diseases International 2022年第4期21卷 362-369页

作者： Young-In Yoon Sung-Gyu Lee deok-Bog Moon Shin Hwang Ki-Hun kim Hui-Ju kim Ki-Hoon Choi Division of Hepatobiliary Surgery and Liver Transplantation Department of SurgeryAsan Medical CenterUniversity of Ulsan College of Medicine388-1 Poongnap-dongSongpa-guSeoul 138-736Korea Department of Surgery Gold Coast University HospitalSouthportQLD 4215Australia

Background:Despite remarkable advances in surgical techniques and perioperative management,left hepatic trisectionectomy(LHT)remains a challenging procedure with a somewhat high postoperative morbidity rate compared with less-extensive *** study aimed to analyze the short-and long-term outcomes of LHT and identify factors associated with the postoperative morbidity of this technically demanding surgical ***:The medical records of 53 patients who underwent LHT between June 2005 and October 2019 at a single institution were retrospectively *** independent prognostic factor of postoperative morbidity was analyzed using the logistic regression ***:Hepatocellular carcinoma was the most common indication for surgery(n=21),followed by hilar cholangiocarcinoma(n=14),intrahepatic cholangiocarcinoma(n=10),and other pathologies(including colorectal liver metastasis,hepatolithiasis,gallbladder cancer,living donor,hemangioma,and multilocular biliary cyst;n=8).The rates of postoperative morbidities of Clavien-Dindo grade 3 or higher and 90-day mortality were 39.6% and 1.9%,*** 1-,3-,and 5-year overall survival rates were 81.1%,61.4%,and 44.6%,*** analysis revealed that preoperative jaundice[hazard ratio(HR)=6.15,95%confidence interval(CI):1.57-24.17,P=0.009]and operative time>420 min(HR=4.66,95%CI:1.27–17.17,P=0.021)were independent predictors of postoperative ***:The in-hospital mortality of LHT surgery can be minimalized by a reliable preoperative evaluation of liver function and selection of the dominant anatomic features of right posterior sector,active and appropriate preoperative management for obstructive cholangitis and compensatory hypertrophy of the future remnant posterior sector,and the experience of the surgeon.

关键词： Left hepatic trisectionectomy Major hepatectomy Liver neoplasms Survival rate Morbidity

Methodology for predicting the life of plasma-sprayed thermal barrier coating system considering oxidation-induced damage

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Journal of Materials Science & Technology 2022年第10期105卷 45-56页

作者： Keekeun kim Damhyun kim Kibum Park Junghan Yun chang-Sung Seok School of Mechanical Engineering Sungkyunkwan UniversitySuwonGyeonggi 440-746Korea

The lifespan of plasma-sprayed thermal barrier coating(TBC)systems is difficult to predict owing to the variety of microstructures and deterioration *** this study,we developed a novel TBC damage model to reflect deterioration histories;thus,it can be applied to various *** to TBCs is classifed into oxidation and mechanical damage;therefore,a detailed deterioration history can be *** addition,by introducing a virtual S–N diagram,a life prediction model that can be applied to TBCs with various microstructures was *** used the proposed damage and life prediction models in isothermal aging and thermal cycle tests with different aging *** predicted lifespan of TBCs by using the proposed models was within 95%of the results obtained by performing actual tests in the temperature range of 1150–1350℃.

关键词： Thermal barrier coatings Damage model Temperature history Thermal fatigue Life prediction model