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Frequency comb-to-comb stabilization over a 1.3-km free-space atmospheric optical link

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Light(Science & Applications) 2022年第9期11卷 2207-2216页

作者： JAEWON YANG DONG il LEE DONG-CHEL SHIN JAEHYUN LEE BYUNG SOO kim HYUN JAY KANG YOUNG-jin kim SEUNG-WOO kim Department of Mechanical Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak-roYuseong-guDaejeon 34141Republic of Korea Presently with Korea Research Institute of Standards and Science(KRISS) 267 Gajeong-roYuseong-guDaejeon 34113Republic of Korea

Stabilizing a frequency comb to an ultra-stable optical frequency reference requires a multitude of optoelectronic peripherals that have to operate under strict ambient ***,the frequency comb-to-comb stabilization aims to synchronize a slave comb to a well-established master comb with a substantial saving in required equipment and ***,we report an utmost case of frequency comb-to-comb stabilization made through a 1.3 km free-space optical(FSO)link by coherent transfer of two separate comb lines along with a feedback suppression control of atmospheric phase *** FSO link offers a transfer stability of 1.7×10-15 at 0.1 s averaging,while transporting the master comb,s stability of 1.2×10-15 at 1.0 s over the entire spectrum of the slave *** remote comb-to-comb stabilization is intended to expedite diverse long-distance ground-to-ground or ground-to-satellite applications;as demonstrated here for broadband molecular spectroscopy over a 6THz bandwidth as well as ultra-stable microwaves generation with phase noise of-80dBc Hz-1 at 1 Hz.

关键词： optical stabilization microwave

First Record of the Blue-banded Sea Krait(Laticauda laticaudata,Reptilia:Squamata:Elapidae:Laticaudinae)on Jeju Island,South Korea

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Asian Herpetological Research 2017年第2期18卷 131-136页

作者： Jaejin PARK Kyo-Soung KOO il-Hun kim Woo-jin CHOI Daesik PARK Department of Biology Kangwon National UniversityChuncheonKangwon 24341South Korea National Marine Biodiversity Institute of Korea SeocheonChungnam 33662South Korea Division of Science Education Kangwon National UniversityChuncheonKangwon 24341South Korea

We report the first recorded capture of a blue-banded sea snake（Laticauda laticaudata Linnaeus, 1758, Jobeuntti Kun Badabam in Korean） in South Korea based on one male specimen collected from Marado-ri, Seogwiposi, Jeju-do on 20 October 2016. The morphological features of the lateral nostrils, the much wider ventrals than adjacent dorsals, the horizontally undivided rostral, the two prefrontals, and the uniform black bands on the body indicate that the specimen is L. laticaudata. An analysis of the partial mitochondrial cytochrome b gene sequence indicated that the specimen fits well into the known L. laticaudata phylogenetic group, which confirms that the sea krait is L. laticaudata. Including this report, five species of sea snakes（L. laticaudata, L. semifasciata, Hydrophis platurus, H. cyanocinctus, and H. melanocephalus） have now been reported in Korean waters.

关键词： sea snake Hydrophiinae Laticaudinae blue-banded sea snake Laticauda laticaudata

Shear deformable finite beam elements for composite box beams

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Acta Mechanica Sinica 2014年第2期30卷 223-240页

作者： Nam-il kim Dong-Ho Choi Department of Architectural Engineering Sejong University Department of Civil and Environmental Engineering Hanyang University

The shear deformable thin-walled composite beams with closed cross-sections have been developed for coupled flexural, torsional, and buckling analyses. A theoretical model applicable to the thin-walled laminated composite box beams is presented by taking into account all the structural couplings coming from the material anisotropy and the shear deformation effects. The current composite beam includes the transverse shear and the restrained warping induced shear deformation by using the first-order shear deformation beam theory. Seven governing equations are derived for the coupled axial-flexural-torsional-shearing buckling based on the principle of minimum total potential energy. Based on the present analytical model, three different types of finite composite beam elements, namely, linear, quadratic and cubic elements are developed to analyze the flexural, torsional, and buckling problems. In order to demonstrate the accuracy and superiority of the beam theory and the finite beam elements developed by this study,numerical solutions are presented and compared with the results obtained by other researchers and the detailed threedimensional analysis results using the shell elements of ABAQUS. Especially, the influences of the modulus ratio and the simplified assumptions in stress-strain relations on the deflection, twisting angle, and critical buckling loads of composite box beams are investigated.

关键词： Thin-walled Composite box beam Deflection Twisting angle Buckling load Shear deformation

Electrochemical Characteristics in Seawater for Cold Thermal Spray-Coated Al-Mg Alloy Layer

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 727-734页

作者： il-Cho Park Seong-Jong kim Division of Marine Engineering Mokpo National Maritime University

For corrosion protection of carbon steel in a marine environment,cold arc thermal spray coating was applied to the surface with Al and Al-Mg alloy *** surface hardness of Al and Al-Mg thermal spray coatings increased with Mg *** the various electrochemical experiments were carried out to evaluate corrosion damage characteristics of the thermal spray coating *** Al and Al-Mg thermal spray coating layers presented negative potentials compared to carbon steel in corrosion potential *** an anodic polarization experiment revealed a tendency of activation polarization with no ***,the corrosion damage of the thermal spray coating layer in galvanostatic experiment was observed mainly at the defect area,and the Al-3Mg thermal spray coating layer presented less surface damages than *** addition,the Al-3Mg thermal spray coating layer showed the lowest corrosion rate while having a sufficient driving voltage for cathodic corrosion ***,it is an optimal thermal spray material for sacrificial anode.

关键词： Corrosion protection Carbon steel Arc thermal spray coating Al-Mg alloy Marine environment

k-Nearest Neighbor Query Processing Algorithms for a Query Region in Road Networks

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Journal of Computer Science & Technology 2013年第4期28卷 585-596页

作者： Hyeong-il kim Jae-Woo Chang Department of Computer Engineering Chonbuk National University Cloud Open R&D Center Chonbuk National University

Recent development of wireless communication technologies and the popularity of smart phones .are making location-based services （LBS） popular. However, requesting queries to LBS servers with users＇ exact locations may threat the privacy of users. Therefore, there have been many researches on generating a cloaked query region for user privacy protection. Consequently, an efficient query processing algorithm for a query region is required. So, in this paper, we propose k-nearest neighbor query （k-NN） processing algorithms for a query region in road networks. To efficiently retrieve k-NN points of interest （POIs）, we make use of the Island index. We also propose a method that generates an adaptive Island index to improve the query processing performance and storage usage. Finally, we show by our performance analysis that our k-NN query processing algorithms outperform the existing k-Range Nearest Neighbor （kRNN） algorithm in terms of network expansion cost and query processing time.

关键词： island index k-nearest neighbor query processing scheme locatiombased service road network

Chemopreventive drugs:Mechanisms via inhibition of cancer stem cells in colorectal cancer

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World Journal of Gastroenterology 2014年第14期20卷 3835-3846页

作者： Tae il kim Department of Internal Medicine and Institute of Gastroenterology Yonsei University College of Medicine

Recent epidemiological studies,basic research and clinical trials on colorectal cancer(CRC)prevention have helped identify candidates for effective chemopreventive ***,because of the conflicting results of clinical trials or side effects,the effective use of chemopreventive drugs has not been generalized,except for patients with a high-risk for developing hereditary *** in genetic and molecular technologies have highlighted the greater complexity of carcinogenesis,especially the heterogeneity of *** need to target cells and processes that are critical to carcinogenesis for chemoprevention and treatment of advanced *** research has shown that intestinal stem cells may serve an important role in tumor initiation and formation of cancer stem ***,studies have shown that the tumor microenvironment may play additional roles in dedifferentiation,to enable tumor cells to take on stem cell features and promote the formation of tumorigenic stem ***,early tumorigenic changes of stem cells and signals for dedifferentiation may be good targets for *** this review,I focus on cancer stem cells in colorectal carcinogenesis and the effect of major chemopreventive drugs on stem cell-related pathways.

关键词： Colorectal cancer Chemoprevention Cancer stem cell Carcinogenesis Microenvironment

Bacterial infection after liver transplantation

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World Journal of Gastroenterology 2014年第20期20卷 6211-6220页

作者： Sang il kim Division of Infectious Disease Seoul St. Mary’s Hospital The Catholic University of Korea Seoul 137-701 South Korea

Infectious complications are major causes of morbidity and mortality after liver transplantation,despite recent advances in the transplant ***,fungi,viruses and parasites can cause infection before and after *** them,bacterial infections are predominant during the first two months posttransplantation and affect patient and graft *** might cause surgical site infections,including deep intra-abdominal infections,bacteremia,pneumonia,catheter-related infections and urinary tract *** risk factors for bacterial infections differ between the periods after transplant,and between ***,the emergence of multi-drug resistant bacteria is great concern in liver transplant(LT)*** instructive data about effects of infections with extended-spectrum beta lactamase producing bacteria,carbapenem-resistant gram-negative bacteria,and glycopeptide-resistant gram-positive bacteria were reported on a center-by-center *** prevent posttransplant bacterial infections,proper strategies need to be established based upon center-specific data and evidence from well-controlled *** article reviewed the recent epidemiological data,risk factors for each type of infections and important clinical issues in bacterial infection after LT.

关键词： Liver transplantation Bacterial infection Intraabdominal infections Resistant bacteria

Effect of tellurium on the microstructure and mechanical properties of Fe-14Cr oxide-dispersion-strengthened steels produced by additive manufacturing

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Journal of Materials Science & Technology 2021年第36期95卷 114-126页

作者： Barton Mensah Arkhurst Jee Hwan Bae Min Young Na Hye Jung Chang Hyun Gil kim il Hyun kim Ho jin Ryu Jeoung Han kim School of Materials Science and Engineering University of New South Wales SydneyNSW 2052Australia Advanced Analysis Center Korea Institute of Science and Technology SeoulSeongbuk-guRepublic of Korea LWR Fuel Technology Division Korea Atomic Energy Research InstituteDaejeonYuseong-guRepublic of Korea Department of Nuclear and Quantum Engineering KAISTDaejeonYuseong-guRepublic of Korea Department of Materials Science&Engineering Hanbat National UniversityRepublic of Korea

Conventionally,Te has primarily been used to improve the machinability of steel and its *** this work,Te was used to refine the grains of an oxide-dispersion-strengthened(ODS)steel produced by additive manufacturing(AM)with fixed processing *** of Te to the raw powder produced an ODS steel with a fine-grained microstructure,in contrast to the ODS steel manufactured without ***,the addition of Te resulted in superior yield strength and ultimate tensile strength,which was attributed to the combined effects of grain refinement and the finer nanoparticles(NPs)composed of Terich composite NPs and Cr-rich *** the first time,the AM technique was used to obtain grain and nanoparticle sizes of~3.4μm and 6 nm,respectively,from the Te-added ODS steel.

关键词： Additive manufacturing Directed energy deposition Oxide-dispersion-strengthened steel Nanoparticle Tellurium

Fabrication of 3D Printed PCL/PEG Polyblend Scaffold Using Rapid Prototyping System for Bone Tissue Engineering Application

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Journal of Bionic Engineering 2018年第3期15卷 435-442页

作者： Su A Park Sang jin Lee Ji Min Seok Jun Hee Lee Wan Doo kim il Keun Kwon Department of Nature-Inspired Nanoconvergence Systems Korea Institute of Machinery and Materials 156 Gajeongbuk-ro Yuseong-gu Daejeon 34103 Republic of Korea Department of Dental Materials School of Dentistry Kyung Hee University 26 Kyungheedae-ro Dongdaemun-gu Seou102447 Republic of Korea

Three-dimensional （3D） printing is a novel process used to manufacture bone tissue engineered scaffolds. This process allows for easy control of the architecture at the micro structure. However, the scaffold properties are typically limited in terms of cellular activity at the scaffold surface due to the printed materials properties. In this study, we developed a polycaprolactone （PCL） blended with polyethylene glycol （PEG） 3D printed scaffold using a rapid prototyping system. The manufactured scaffolds were then washed out to form small pores on the surface in order to improve the scaffolds hydrophilicity. We analyzed the resultant material by using Scanning Electron Microscopy （SEM）, water absorption, water contact angle, in vitro WST-1, and the Bradford assay. Additionally, cells incubated on the fabricated scaffolds were visualized by Confocal Laser Scanning Microscopy （CLSM）. The developed scaffolds exhibited small pores on the strand surface which served to increase hydrophilicity as well as improve cellular proliferation and increase total protein content. Our findings suggest that the presence of small pores on the scaffolds can be used as an effective tool for improving implant cellular interaction. This research indicates that these modified scaffolds can be considered useful for bone tissue engineering applications to improve human health.

关键词： polycaprolactone polyethylene glycol polyblend 3D printing porosity bone tissue engineering