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Microsystems & Nanoengineering 2022年第4期8卷 233-249页

作者： Yongkui Tang Eun sok kim Department of Electrical and Computer Engineering University of Southern CaliforniaLos AngelesCA90089-0271USA

Focused ultrasound(FUs)is a powerful tool widely used in biomedical therapy and imaging as well as in sensors and *** focusing techniques based on curved surfaces,metamaterial structures,and multielement phased arrays either present diffculties in massively parallel manufacturing with high precision or require complex drive electronics to *** difficulties have been addressed by microfabricated self-focusing acoustic transducers(SFATs)with Parylene air-cavity Fresnel acoustic lenses(ACFALs),which require a time-demanding step in removing the sacrificial *** paper presents three new and improved types of ACFALs based on polydimethylsiloxane(PDMS),an SU-8/PDMS bilayer,and SU-8,which are manufactured through simple sacrificiallayer-free microfabrication processes that are two to four times faster than that for the Parylene ***,by studying the effect of the lens thickness on the acoustic transmittance through the lens,the performance of the transducers has been optimized with improved thickness control techniques developed for PDMS and *** a result,the measured power transfer effciency(PTE)and peak output acoustic pressure are up to 2.0 and 1.8 times higher than those of the Parylene ACFALs,*** simple microfabrication techniques described in this paper are useful for manufacturing not only high-performance ACFALs but also other miniaturized devices with hollow or suspended structures formicrofluidicand optical applications.

关键词： Parylene Fresnel cavity

A modeling method for vibration analysis of cracked beam with arbitrary boundary condition

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Journal of Ocean Engineering and Science 2018年第4期3卷 367-381页

作者： Kwanghun kim sok kim Kyongjin sok Chanil Pak Kwangbok Han Department of Engineering Machine Pyongyang University of Mechanical EngineeringPyongyang 999093Democratic People’s Republic of Korea Department of Information Engineering Chongjin Mine&Metal UniversityChongjin 999091Democratic People’s Republic of Korea Institute of Information Technology University of SciencesPyongyang 999093Democratic People’s Republic of Korea Information Center Kim Chaek University of TechnologyPyongyang 950003Democratic People’s Republic of Korea Department of Resource Development Machinery Engineering Pyongyang University of Mechanical EngineeringPyongyang 999093Democratic People’s Republic of Korea

This paper establishes a cracked Timoshenko beams model to investigate the vibration behavior based on the ultraspherical *** beam theory is applied to model the free vibration analysis of the cracked beam and the numerical results are obtained by using ultraspherical orthogonal *** boundary conditions of both ends of the cracked beam are modeled as the elastic spring and the beam is divided into two parts by the crack section,and continuous conditions at the connecting face are modeled by the inverse of the flexibility coefficients of fracture mechanics *** the influence of boundary conditions,displacements admissible functions of cracked Timoshenko beam can be set up as ultraspherical orthogonal *** accuracy and robustness of the present method are evidenced through comparison with previous literature and the results achieved by the finite element method(FEM).In addition,the effects of flexibility coefficient on the natural frequencies are also investigated by using the proposed *** examples are given for free vibration analysis of cracked beams with various boundary conditions,which may be provided as reference data for future study.

关键词： Cracked beam Free vibration Ultraspherical polynomials Arbitrary boundary conditions

A semi-analytical method for forced vibration analysis of cracked laminated composite beam with general boundary condition

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Journal of Ocean Engineering and Science 2021年第1期6卷 40-53页

作者： sok kim Kwanghun kim Myongchol Ri Yongsong Paek Choljun kim Department of Information Engineering Chongjin Mine&Metal UniversityChongjin 999091Democratic People’s Republic of Korea Department of Engineering Machine Pyongyang University of Mechanical EngineeringPyongyang 999093Democratic People’s Republic of Korea Institute of Science Pyongyang University of Mechanical EngineeringPyongyang 999093Democratic People’s Republic of Korea Department of Resources Development Mechanical Engineering Pyongyang University of Mechanical EngineeringPyongyang 999093Democratic People’s Republic of Korea

In this paper,a semi-analytical method for the forced vibration analysis of cracked laminated composite beam(CLCB)is *** computational model is formulated by Timoshenko beam theory and its dynamic solution is solved using the Jacobi-Ritz *** boundary conditions(BCs)at both ends of the CLCB are generalized by the application of artificial elastic springs,the CLCB is separated into two elements along the crack,the flexibility coefficient of fracture theory is used to model the essential continuous condition of the connective *** the allowable displacement functions used to analyze dynamic characteristics of CLCB are expressed by classical Jacobi orthogonal polynomials in a more general *** accuracy of the proposed method is verified through the compare with results of the finite element method(software ABAQUS is used in this paper).On this basis,the parametric study for dynamic analysis characteristics of CLCB is performed to provide reference datum for engineers.

关键词： Semi-analytical method Cracked laminated composite beam(CLCB) Dynamic analysis General boundary condition Numerical analysis

Optimal Cyber Attack Strategy Using Reinforcement Learning Based onCommon Vulnerability Scoring System

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Computer Modeling in Engineering & Sciences 2024年第11期141卷 1551-1574页

作者： Bum-sok kim Hye-Won Suk Yong-Hoon Choi Dae-Sung Moon Min-Suk kim Department of Electronic Information System Engineering Sangmyung UniversityCheonan31066Republic of Korea Department of Human Intelligence&Robot Engineering Sangmyung UniversityCheonan31066Republic of Korea Intelligent Convergence Research Laboratory Electronics and Telecommunications Research InstituteDaejeon34129Republic of Korea

Currently,cybersecurity threats such as data breaches and phishing have been on the rise due to the many differentattack strategies of cyber attackers,significantly increasing risks to individuals and *** technologies such as intrusion detection have been developed to respond to these cyber ***,advanced integrated cybersecurity that incorporates Artificial Intelligence has been the *** this paper,wepropose a response strategy using a reinforcement-learning-based cyber-attack-defense simulation tool to addresscontinuously evolving cyber ***,we have implemented an effective reinforcement-learning-basedcyber-attack scenario using Cyber Battle Simulation,which is a cyber-attack-defense *** scenarioinvolves important security components such as node value,cost,firewalls,and ***,we applieda new vulnerability assessment method based on the Common Vulnerability Scoring *** approach candesign an optimal attack strategy by considering the importance of attack goals,which helps in developing moreeffective response *** attack strategies are evaluated by comparing their performance using a variety ofReinforcement Learning *** experimental results show that RL models demonstrate improved learningperformance with the proposed attack strategy compared to the original *** particular,the success rateof the Advantage Actor-Critic-based attack strategy improved by 5.04 percentage points,reaching 10.17%,whichrepresents an impressive 98.24%increase over the original ***,the proposed method canenhance security and risk management capabilities in cyber environments,improving the efficiency of securitymanagement and significantly contributing to the development of security systems.

关键词： Reinforcement learning common vulnerability scoring system cyber attack cyber battle simulation

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柬埔寨Artisans公司经营策略研究

柬埔寨Artisans公司经营策略研究

作者：金松（kim sok）北京交通大学

学位级别：硕士

Over the last few years, international tourist arrival in the Kingdom of Cambodia has increased unprecedentedly, being projected to reach 5 million international tourists by the end of 2015. The minister of tourism, in his speech to Chinese tourists in 2013, explained about the increase, having cited two main reasons, the nation-wide full piece and the prosperity of Khmer culture. Simultaneously, the needs of tourism services also increase while the souvenir industry, one of the tourism services, remarkably *** study aims to develop a business strategy for Artisans Cambodia (AC) to improve its current standing in the souvenir art industry in Cambodia. The study attempts to answer the following questions:(1) How can the operation of AC be sustained?(2) What are strategic options available for AC to sustain its operations?(3) What marketing strategies must be adopted to take advantage of the growing business opportunities in Cambodia tourism industry?The study information was gathered both from primary and secondary *** data are generated from the interviews of sellers and international tourists. Using convenience sampling technique in interviewing respondents numbering to approximate 100 foreign tourists and 20 sellers of souvenir art shops, a fact to face interview was undertaken in the capital of Phnom Penh and the town of Siem Reap, the two most wanted places to visit for both international and local tourists. An actual visit was conducted by the researchers at the manufacturing plant of AC in Phnom Penh and Siem Reap, where a case study was held. This result validates main findings of the *** result of the survey showed about the number (in percentage) of tourists from the other foreign countries who like buying the souvenirs, the kinds of souvenir products and their average costs per piece the international customers preferred, the places of the potential tourism markets all over Cambodia where the tourists preferred to visit and buy souv

关键词： Figure 经营策略 weighing ancient tourist Artisans heritage Temple tourism silver

Nanotribological properties and scratch resistance of MoS_(2)bilayerona SiO_(2)/Si substrate

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Friction 2023年第1期11卷 154-164页

作者： Si-hwan kim Hyo-sok AHN Department of Transdisciplinary Studies Seoul National UniversitySeoul 08826Republic of Korea Department of Manufacturing Systems and Design Engineering Seoul National University of Science and TechnologySeoul 08826 Republic of Korea

The tribological properties and scratch resistance of MoS_(2)bilayer deposited on SiO_(2)/Si substrates prepared via chemical vapor deposition are *** force microscopy(FFM)is employed to investigate the friction and wear properties of the MoS_(2)bilayer at the nanoscale by applying a normal load ranging from 200 to 1,000 *** resistance is measured using the scratch mode in FFM based on a linearly increasing load from 100 to 1,000 *** probe force microscopy(KPFM)is performed to locally measure the surface potential in the tested surface to qualitatively measure the wear/removal of Mos,layers and identify critical loads associated with the individual failures of the top and bottom *** analysis of the contact potential difference values as well as that of KPFM,friction,and height images show that the wear/removal of the top and bottom layers in the MoS_(2)bilayer system occurred *** FFM and KPFM results show that the top MoS_(2)layer begins to degrade at the end of the low friction stage,followed by the bottom layer,thereby resulting in a transitional friction stage owing to the direct contact between the diamond tip and SiO_(2)*** the stable third stage,the transfer of lubricious MoS_(2)debris to the tip apex results in contact between the MoS_(2)-transferred tip and SiO_(2).Nanoscratch test results show two ranges of critical loads,which correspond to the sequential removal of the top and bottom layers.

关键词： chemical vapor deposition(CVD)-grown MoS,bilayer friction force microscopy(FFM) nanoscratch test Kelvin probe force microscopy(KPFM) scratch resistance

利用CF_4等离子体制作高开口率TFT-LCD(英文)

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液晶与显示 2006年第5期21卷 409-413页

作者：金奉柱崔瑩石劉聖烈張炳鉉柳在一李禹奉李貞烈京东方科技集团股份有限公司中央研究院北京100016

为了获得高的开口率,有必要优化设计参数和工艺容差。通常的过孔刻蚀工艺采用SF6基气体进行刻蚀,但是这种方法在金属和钝化层之间的选择性太小,因此,必须增加过孔的尺寸才行。为了克服上述问题,在本研究中用CF4气体代替SF6气体进行刻蚀... 详细信息

为了获得高的开口率,有必要优化设计参数和工艺容差。通常的过孔刻蚀工艺采用SF6基气体进行刻蚀,但是这种方法在金属和钝化层之间的选择性太小,因此,必须增加过孔的尺寸才行。为了克服上述问题,在本研究中用CF4气体代替SF6气体进行刻蚀,结果在FFS 5 .16(2 .03 in)像素结构中,开口率提高了60 %。

关键词： TFT—LCD 开口率刻蚀 CF4等离子体

Evaluation of early-age strains and stresses in roller-compacted concrete pavement

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第1期9卷 93-105页

作者： Tetsya sok Young Kyu kim Jun Young Park Seung Woo Lee Public Infrastructure Department Ministry of Public Works and TransportPhnom Penh 12100Cambodia Institute for Disaster Prevention Gangneung-Wonju National UniversityGangneung-si 25457South Korea Korea Expressway Research Institute Korea Expressway CorporationHwaseong-si 18489South Korea Civil Engineering Department Gangneung-Wonju National UniversityGangneung-si 25457South Korea

In the structural design of a roller-compacted concrete pavement(RCCP), it is crucial to estimate strain and stress developments in the RCCP slab realistically. Since the RCCP mix uses less cement and lower amount of water, shrinkage strain and concrete temperature during the hardening stage are expected to be reduced as compared to those of conventional concrete mixture, resulting in a reduction of the concrete early-age deformation and stress developments in the RCCP slab. In this paper, early-age concrete strain and stress developments in RCCP slab subjected to environmental loads were evaluated. A full-scale test section of RCCP under real climatic conditions was monitored. The early-age total strains,stress-independent strains, shrinkage strains, and coefficient of thermal expansion(CTE) of the RCCP were measured and analyzed. Using the results of measured strains, in-situ CTE and shrinkage strain, and temperature, the early-age concrete stress development is computed by incorporating a viscoelastic property of the early-age concrete. The results revealed that the shrinkage strain of the RCCP is quite low as compared to that of conventional concrete. The early-age stress developments in the RCCP slab are strongly governed by the thermal-induced stresses. Shrinkage-induced stresses were quite small and might be negligible in a preliminary estimation of early-age stress developments in the RCCP slab.

关键词： Road engineering Roller-compacted concrete pavement Concrete strain Concrete stress Shrinkage strain Environmental loads

Common bile duct stones on multidetector computed tomography:Attenuation patterns and detectability

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World Journal of Gastroenterology 2013年第11期19卷 1788-1796页

作者： Chang Whan kim Jae Hyuck Chang Yeon Soo Lim Tae Ho kim In Seok Lee sok Won Han Department of Internal Medicine College of MedicineThe Catholic University of Korea505 BanpoDongSeocho-GuSeoul 137-701South Korea Department of Radiology College of MedicineThe Catholic University of Korea505 Banpo-DongSeocho-GuSeoul 137-701South Korea

AIM:To investigate the attenuation patterns and detectability of common bile duct(CBD) stones by multidetector computed tomography(MDCT).METHODS:Between March 2010 and February 2012,191 patients with suspicion of CBD stones undergoing both MDCT and endoscopic retrograde cholangiopancreatography(ERCP) were enrolled and reviewed *** attenuation patterns of CBD stones on MDCT were classified as heavily calcified,radiopaque,less radiopaque,or *** association between the attenuation patterns of CBD stones on MDCT and stone type consisting of pure cholesterol,mixed cholesterol,brown pigment,and black pigment and the factors related to the detectability of CBD stones by MDCT were ***:MDCT showed CBD stones in 111 of 130 patients in whom the CBD stones were demonstrated by ERCP with 85.4% *** attenuation patterns of CBD stones on MDCT were heavily calcified 34(26%),radiopaque 31(24%),less radiopaque 46(35%),and undetectable 19(15%).The radiopacity of CBD stones differed significantly according to stone type(P < 0.001).From the receiver operating characteristic curve,stone size was useful for the determination of CBD stone by MDCT(area under curve 0.779,P < 0.001) and appropriate cut-off stone size on MDCT was 5 *** factors related to detectability of CBD stones on MDCT were age,stone type,and stone size on multivariate analysis(P < 0.05).CONCLUSION:The radiopacity of CBD stones on MDCT differed according to stone *** type and stone size were related to the detectability by MDCT,and appropriate cut-off stone size was 5 mm.

关键词： Common bile duct gallstones Gallstones Multidetector computed tomography Endoscopic retrograde cholangiography

Undiagnosed Borrmann type Ⅱ gastric cancer due to necrosis and regenerative epithelium

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World Journal of Gastroenterology 2014年第28期20卷 9621-9625页

作者： Joon Hur Jae Hyuck Chang Byung Kee kim Hoon Young Ko Jong Hwan Lee Soo Jeong kim Mi Ae Song Tae Ho kim Chang Whan kim sok Won Han Division of Gastroenterology Department of Internal MedicineBucheon St.Mary’s HospitalThe Catholic University of KoreaCollege of Medicine Department of Clinical Pathology Bucheon St.Mary’s HospitalThe Catholic University of KoreaCollege of Medicine

Endoscopic biopsy is essential to the proper diagnosis and treatment of gastric ***,the results of endoscopic biopsy are not always the same as what is expected based on gross endoscopic *** results of endoscopic biopsy can be negative for malignancy in Borrmann typeⅣadvanced gastric cancer(AGCa)or gastric ***,in the case of typeⅡAGCa,repeated biopsies negative for malignancy have not been reported.A 49-year-old male patient underwent esophagogastroduodenoscopy three times due to large gastric ulcer suspected to be Borrmann typeⅡ***,three repeat endoscopic biopsies with multiple specimens showed necrosis and superficial regenerative epithelium without malignant *** patient underwent laparoscopic distal gastrectomy with D2 lymph node *** surgical specimen revealed that the mucosal layer was completely replaced with regenerative epithelium without cancer cells.

关键词： Endoscopy Biopsy Stomach neoplasm Stomach ulcer Regeneration