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Ionizing terahertz waves with 260 MV/cm from scalable optical rectification

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Light(Science & Applications) 2024年第6期13卷 1075-1087页

作者： Hyeongmun Kim Chul Kang Dogeun Jang Yulan Roh Sang Hwa Lee Joong Wook Lee Jae Hee Sung seong Ku Lee Ki-yong Kim Advanced Photonics Research Institute GISTGwangju61005Korea Department of Physics and Optoelectronics Convergence Research Center Chonnam National UniversityGwangju61186Korea Pohang Accelerator Laboratory POSTECHPohang37673Korea Center for Relativistic Laser Science Institute for Basic ScienceGwangju61005Korea Institute for Research in Electronics and Applied Physics Department of PhysicsUniversity of MarylandCollege ParkMaryland20742USA

Terahertz(THz)waves,known as non-ionizing radiation owing to their low photon energies,can actually ionize atoms and molecules when a sufficiently large number of THz photons are concentrated in time and ***,we demonstrate the generation of ionizing,multicycle,15-THz waves emitted from large-area lithium niobate crystals via phase-matched optical rectification of 150-terawatt laser pulses.A complete characterization of the generated THz waves in energy,pulse duration,and focal spot size shows that the field strength can reach up to 260 megavolts per *** particular,a single-shot THz interferometer is employed to measure the THz pulse duration and spectrum with complementary numerical *** intense THz pulses are irradiated onto various solid targets to demonstrate THz-induced tunneling ionization and plasma *** study also discusses the potential of nonperturbative THz-driven ionization in gases,which will open up new opportunities,including nonlinear and relativistic THz physics in plasma.

关键词： optical interferometer matched

Submicron Ag-coated Cu particles as filler in sintering paste: Suppression of Ag dewetting and improvement of sinterability by surface modification using stearic acid

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Transactions of Nonferrous Metals Society of China 2024年

作者： Yeongjung Kim yong-Sung Eom Kwang-seong Choi Jong-Hyun Lee Department of Materials Science and Engineering， Seoul National University of Science and Technology， 232 Gongneung-ro Low-Carbon Integration Tech， Creative Research Section， ETRI， 218 Gajeong-ro Materials Research Institute for Future Convergence， Seoul National University of Science and Technology， 232 Gongneung-ro

Four types of submicron Ag-coated Cu particles with different Ag contents were prepared as sintering paste fillers， and the Ag contents of the particles were measured to be 10， 20， 30， and 40 wt%. Four types of particles （in order of increasing Ag content: A10， A20， A30， and A40） were surface-modified with stearic acid， to suppress the Ag shell dewetting and improve sinterability. The surface-modified particles were mixed with a polyol-based solvent to fabricate a resin-free paste. Subsequently， the pastes were screen-printed onto a slide glass and sintered at 250 ℃ in a nitrogen atmosphere for 1–10 min to form an electrode. The electrical resistivity of the sintered film as a function of sintering time was measured using a four-point probe. All the four surface-modified Cu@Ag particles with different Ag contents exhibited decreased electrical resistivity. Particularly， the largest difference in values after and before the surface modification was observed for A40 with the highest Ag content; the electrical resistivities of the initial and surface-modified particles were 1.51×10-4and 6.67×10-5Ω·cm， respectively， after sintering for 10 min. The findings of this study confirmed that the surface modification using stearic acid effectively suppressed the dewetting of the Ag shell and improved the sinterability of the submicron Cu@Ag particles.

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Friction stir welding of 5052 aluminum alloy plates

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中国有色金属学会会刊：英文版 2009年第B9期19卷 23-27页

作者： yong-Jai kwon seong-Beom SHIM Dong-Hwan PARK School of Materials Science and Engineering University of Ulsan Institute of E-Vehicle Technology University of Ulsan

Friction stir welding between 5052 aluminum alloy plates with a thickness of 2 mm was performed. The tool for welding was rotated at speeds ranging from 500 to 3000 r/min under a constant traverse speed of 100 mm/min. The results show that at all tool rotation speeds, defect-free welds are successfully obtained. Especially at 1000, 2000 and 3000 r/min, the welds exhibit very smooth surface morphologies. At 500, 1000, and 2000 r/min, onion ring structure is clearly observed in the friction-stir-welded zone (SZ). In addition, the onion ring structure region becomes wider as the tool rotation speed is increased. The gain size in the SZ is smaller than that in the base metal, and is decreased with a decrease of the tool rotation speed. In all tool rotation speeds, the SZ exhibits higher average hardness than the base metal. Especially at 500 r/min, the average hardness of the SZ reaches a level about 33% greater than that of the base metal. At 500, 1 000 and 2 000 r/min, the tensile strength of the friction stir welded (FSWed) plates is similar to that of the base metal (about 204 MPa). The elongation of the FSWed plates is lower than that of the base metal (about 22%). However, it is noticeable that the maximum elongation of about 21% is obtained at 1 000 r/min.

关键词：搅拌摩擦焊接铝合金板旋转速度焊接工具表面形貌环形结构抗拉强度伸长率

Suggestion of advanced regression model on friction angle of fault gouge in South Korea

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第6期13卷 1368-1379页

作者： seong-Woo Moon Hyun-Seok Yun yong-Seok Seo Department of Earth and Environmental Sciences Chungbuk National University1 Chungdae-roCheongju-siChungcheongbuk-do28644South Korea

Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than those of soils or rocks due to its high heterogeneity and low ***,to improve the accuracy of analysis results,we conducted simple regression analysis and structural equation model analysis and selected major influential factors of friction characteristics among many factors,and then we deduced advanced regression model with the highest coefficient of determination(R^(2)) via multiple regression *** most coefficients of determination in simple regression analysis are below0.3-0.4,coefficient of determination in multiple regression analysis is remarkably large as 0.657.

关键词： Fault gouge Friction angle Simple regression analysis Structural equation model analysis Multiple regression analysis

Mutation of MED12 is not a frequent occurrence in prostate cancer of Korean patients

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Asian Journal of Andrology 2017年第3期19卷 346-349页

作者： Nara Yoon Sharon Lim So Young Kang Ghee Young kwon Hwang Gyun Jeon Byong Chang Jeong seong Il Seo seong Soo Jeon Hyun Moo Lee Han yong Choi Department of Pathology Samsung Medical Center Sungkyunkwan University School of Medicine Seoul 135-710 Korea Department of Urology Samsung Medical Center Sungkyunkwan University School of Medicine Seoul 135-710 Korea

Prostate cancer is one of the major health care problems, but the molecular pathogenesis has been relatively insufficiently elucidated. Recently, whole exome sequencing of prostate cancer identified recurrent mutations involving MED12 in Caucasian patients, which finding was not reproduced in one subsequent study by Sanger sequencing. Thus, we investigated mutation status of MED12 in exons 2 and 26 by Sanger sequencing in 102 radical prostatectomy cases from Korean patients. The analysis found the mutation in none of the cases. Therefore, MED12 mutation does not appear to represent a significant molecular alteration in this cohort of patients according to the analysis by the traditional ＂gold standard.＂

关键词： mediator complex subunit 12 mutation analysis prostate cancer prostate neoplasms

Prostate-specific antigen density predicts favorable pathology and biochemical recurrence in patients with intermediate-risk prostate cancer

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Asian Journal of Andrology 2016年第3期18卷 480-484,I0012页

作者： Ho Won Kang Hae Do Jung Joo yong Lee Jong Kyou kwon seong Uk Jeh Kang Su Cho Won Sik Ham Young Deuk Choi Department of Urology Chungbuk National University College of Medicine Cheongju Korea Department of Urology Severance Hospital Urological Science InstituteYonsei University College of Medicine Seoul Korea Department of Urology. Inje university Haeundae Paik Hospital Busan Korea Department of Urology Gyeongsang National University School of Medicine Jinju Korea Department of Urology Gangnam Severance Hospital Urological Science Institute Yonsei University Uollege of Medicine Seoul Korea Robot and Minimal Invasive Surgery Center Severance Hospital Yonsei University College of Medicine Seoul Korea.

This study was designed to identify clinical predictors of favorable pathology and biochemical recurrence （BCR） in patients with intermediate-risk prostate cancer （IRPCa）. Between 2006 and 2012, clinicopathological and oncological data from 203 consecutive men undergoing robot-assisted radical prostatectomy （RARP） for IRPCa were reviewed in a single-institutional retrospective study. Favorable pathology was defined as Gleason score 〈6 and organ-confined cancer as detected by surgical pathology. Logistic regression analysis was used to determine predictive variables of favorable pathology, and the Kaplan-Meier and multivariate Cox regression model were used to estimate BCR-free survival after RARP. Overall, 38 patients （18.7%） had favorable pathology after RARP. Lower quartile prostate-specific antigen density （PSAD） was associated with favorable pathology compared to the highest quartile PSAD after adjusting for preoperative PSA, clinical stage and biopsy Gleason score （odds ratio, 5.42; 95% confidence interval, 1.01-28.97; P = 0.048）. During a median 37.8 （interquartile range, 24.6-60.2） months of follow-up, 66 patients experienced BCR. There were significant differences with regard to BCR free survival by PSAD quartiles （log rank, P = 0.003）. Using a multivariable Cox proportion hazard model, PSAD was found to be an independent predictor of BCR in patients with IRPCa after RARP （hazard ratio, 4.641; 95% confidence interval, 1.109-19.417; P = 0.036）. The incorporation of the PSAD into risk assessments might provide additional prognostic information and identify some patients in whom active surveillance would be appropriate in patients with IRPCa.

关键词： biochemical recurrence prostatectomy prostate-specific antigen prostate-specific antigen density prostatic neoplasms

Direct dynamic-simulation approach to trajectory optimization

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Chinese Journal of Aeronautics 2021年第10期34卷 6-19页

作者： Sung Wook HUR seong Han LEE yong Hyeon NAM Chang-Joo KIM Department of Aerospace Information Engineering Konkuk UniversitySeoul 05029Republic of Korea

This paper proposes a new direct method for an efficient trajectory optimization using the point that the dynamics of a deterministic system are uniquely determined by initial states and controls imposed over the time horizon of *** effectively implement this concept,the Hermite spline is adopted to interpolate the continuous controls and the system dynamics are integrated with corresponding control parameters in *** a result,the optimal control problem can be transcribed into a nonlinear programming problem which has no dynamic equality constraints and no intermediate states in its design *** addition,the paper proposes an efficient recursive Jacobian estimation technique and introduces a Jacobian transformation matrix to straightforwardly handle the general state *** properties of the present method are thoroughly investigated through its applications to the trajectory optimization for a soft lunar landing from a parking orbit,including the detailed analyses for the de-orbiting *** computed results are compared with those using the pseudo-spectral method to demonstrate an extreme outperformance of the proposed method in the aerospace applications over the traditional direct method.

关键词： Trajectory optimization Direct method Hermite spline interpolation Pseudo-spectral integrator Soft lunar landing

Electrochemical characteristics of Al-Mg and Al-Mg-Si alloy in sea water

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中国有色金属学会会刊：英文版 2012年第S3期22卷 881-886页

作者： seong-jong KIM Seung-jun LEE Jae-yong JEONG Kyu-hwan KIM Division of Marine Engineering Mokpo Maritime University

Among Al alloys,particularly 5000 series Al Mg and 6000 series Al Mg Si often used as marine materials have excellent corrosion resistance,low melting point,and thereby showing recycling availability when compared to other *** experiments were conducted to select the most suitable material for marine *** electrochemical experiments were conducted in natural *** corrosion test was performed in many methods such as anodic/cathodic polarization and Tafel analysis using multi-channel potentio/galvanostat WMPG *** results,anodic and cathodic polarization behaviors indicate the characteristics of passive state and concentration polarization by reduction reaction in dissolved oxygen,which shows excellent electrochemical *** analysis results show no significant difference but 5052-O alloy of various alloy materials indicates the lowest corrosion current ***,5052-O Al alloy presents most anti-corrosion material in marine environment.

关键词： Al alloy ship electrochemical characteristics corrosion

Suppression of laser-induced choroidal neovascularization by intravitreal injection of tristetraprolin

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International Journal of Ophthalmology(English edition) 2014年第6期7卷 952-958页

作者： yong Wun Cho yong Seop Han In Young Chung seong Jae Kim seong Wook Seo Ji Myong Yoo Jong Moon Park Department of Ophthalmology Gyeongsang National University School of Medicine Gyeongsang Institute of Health Science Gyeongsang National University

AIM: To examine the effect of intravitreal adenoviral vector-mediated tristetraprolin(Ad-TTP) on VEGF m RNA expression in a rat model of laser-induced choroidal ***: Ad-TTP was prepared using a commercial kit. Retinal laser-induced photocoagulation(10 spots per eye) was performed on rats in this experimental choroidal neovascularization(CNV) model. Rats were divided into four groups: control(single intravitreal injection of balanced salt solution, n =10), laser-induced CNV(photocoagulation only, n =20), laser-induced CNV plus Ad-TTP injection(photocoagulation plus a single intravitreal Ad-TTP injection, n =20) and Ad-TTP injection only(n =10). Changes in choroidal morphology were evaluated in ten rats in the laser only and the laser plus Ad-TTP groups. Two weeks after laser injury, the size of CNV was calculated by perfusion with high-molecular-weight fluorescein isothiocyanate(FITC)-dextran. VEGF m RNA expression in retina-choroid tissue from ten rats in each group was measured by reverse transcription polymerase chain reaction(RT-PCR). RESULTS: Two weeks after treatment, the area of laser-induced CNV was reduced by approximately 60% in the rats given the Ad-TTP injection compared with that in the laser-only group. There was a tendency toward decreased VEGF m RNA expression in the Ad-TTP injection ***: A single intravitreal injection of Ad-TTP significantly suppressed CNV size in this experimental laser-induced CNV model. Ad-TTP injection also decreased VEGF m RNA expression compared with that inthe laser-induced CNV group. The present study is meaningful as the first study to investigate the effect of tristetraprolin delivered via intravitreal injection.

关键词： laser-induced choroidal neovascularization tristetraprolin adenoviral vectors