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Passively Q-switched ytterbium-doped fiber laser using the evanescent field interaction with bulk-like WTe_2 particles

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Chinese Optics Letters 2018年第2期16卷 108-112页

作者： Seunghwan Ko Jinho lee ju han lee School of Electrical and Computer Engineering University of Seoul Seoul 02504 Republic of Kore

The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method together with Scotch tape. By attaching bulk-like WTe2 particles, which remained on the top of the sticky surface of a small segment of the Scotch tape, to the flat side of a side-polished fiber, a saturable absorber（SA） was readily implemented. A strong saturable absorption was then readily obtained through an evanescent field interaction with the WTe2 particles. The modulation depth of the prepared SA was measured as ~2.18% at 1.03 μm. By incorporating the proposed SA into an all-fiberized ytterbium-doped fiber ring cavity, stable Qswitched pulses were readily achieved.

关键词： length Passively Q-switched ytterbium-doped fiber laser using the evanescent field interaction with bulk-like WTe2 particles SA

All-fiber acousto-optic modulator based on a cladding-etched optical fiber for active mode-locking

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Photonics Research 2017年第5期5卷 391-395页

作者： JIHWAN KIM JOONHOI KOO ju han lee School of Electrical and Computer Engineering University of Seoul

An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer was overlaid. A chemical wet-etching technique, which is based on a mixed solution of NH_4F and (NH_4)2SO_4, is used to reduce the fiber diameter down to ～25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10% at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 *** using the prepared AOM within an erbium-doped-fiber ring cavity, the mode-locked pulses with a temporalwidth of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.

关键词： All-fiber acousto-optic modulator based on a cladding-etched optical fiber for active mode-locking

Investigation of nonlinear optical properties of rhenium diselenide and its application as a femtosecond mode-locker

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Photonics Research 2019年第9期7卷 984-993页

作者： JINHO lee KYUNGTAEK lee SUHYOUNG KWON BUMSOO SHIN ju han lee School of Electrical and Computer Engineering University of Seoul

We investigated the nonlinear optical properties of ReSe2. First, we measured the nonlinear absorption coefficient and the nonlinear refractive index of a ReSe2 thin film using open-aperture(OA) and closed-aperture(CA) Z-scan techniques. ReSe2 was shown to possess both saturable absorption and self-defocusing properties. The nonlinear absorption coefficient of ReSe2 was measured to be-5.67-0.35×103 cm^2∕GW, and its nonlinear refractive index was-2.81-0.13×10-2 cm^2∕GW at 1560 nm. Next, a fiberized saturable absorber(SA) based on ReSe2 was fabricated with a side-polished fiber platform and was tested as an ultrafast mode-locker capable of producing femtosecond pulses operating at a wavelength of 1560 nm. The estimated modulation depth and saturation power are 3.9% and 42 W, respectively, for the transverse electric mode, while they are 2.4% and 53 W for the transverse magnetic mode. Using the prepared SA, stable soliton pulses with a temporal width of 862 fs were produced from an erbium-doped fiber ring cavity. To the best of the authors’ knowledge, this is the first demonstration of using a ReSe2-based SA for femtosecond mode-locked pulse generation.

关键词： Se Investigation of nonlinear optical properties of rhenium diselenide and its application as a femtosecond mode-locker

Femtosecond mode-locking of a fiber laser using a CoSb_3-skutterudite-based saturable absorber

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Photonics Research 2018年第10期6卷 I0038-I0045页

作者： JINHO lee YOONTAEK KIM KYUNGTAEK lee ju han lee School of Electrical and Computer Engineering University of Seoul

We experimentally demonstrate an ultrafast mode-locker based on a CoSb_3 skutterudite topological insulator for femtosecond mode-locking of a fiber laser. The mode-locker was implemented on a side-polished fiber platform by depositing a CoSb_3∕PVA composite. The measured modulation depth and saturation power for the transverse-electric mode input were ～5% and ～8.7 W, respectively, and ～2.8% and ～10.6 W for the transverse-magnetic mode input. By incorporating this mode-locker into an erbium-doped fiber-based ring cavity, we were able to readily generate mode-locked, soliton pulses having a pulse width of ～833 fs at 1557.9 nm. The 3-dB bandwidth of the output pulses and time-bandwidth product were ～3.44 and 0.353 nm, respectively. To the best of the authors' knowledge, this is the first demonstration of the use of a skutterudite-based saturable absorber for femtosecond mode-locked pulse generation.

关键词：晶格光纤激光器通讯技术发展现状

Exophytic inflammatory myofibroblastic tumor of the stomach in an adult woman:A rare cause of hemoperitoneum

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World Journal of Gastroenterology 2008年第1期14卷 136-139页

作者： Seong-Heum Park Jong-han Kim Byung Wook Min Tae Jin Song Gil Soo Son Seung Joo Kim Sang Woo lee Hwan-Hoon Chung ju han lee jun Won Um Department of Surgery Korea University College of Medicine 126-1 5-Ga Anam-Dong Sungbuk-Gu Seoul 136-705 Korea Department of Internal Medicine Korea University College of Medicine 126-1 5-Ga Anam-Dong Sungbuk-Gu Seoul 136-705 Korea Department of Radiology Korea University College of Medicine 126-1 5-Ga Anam-Dong Sungbuk-Gu Seoul 136-705 Korea Department of Pathology Korea University College of Medicine 126-1 5-Ga Anam-Dong Sungbuk-Gu Seoul 136-705 Korea

Inflammatory myofibroblastic tumor （INT） of the stomach in adults is extremely rare, with unpredictable prognosis. We present a 55-year-old woman with a gastric IMT. She experienced sudden abdominal pain 4 d previously. Physical examination showed mild abdominal tenderness in the hypogastrium, but no palpable abnormal abdominal mass. Abdominal CT showed a mass of approximately 8 cm in the gastrocolic ligament. On laparoscopic exploration, unexpected hemoperitoneum of approximately 1.5 L of blood was found, and an exophytic gastric mass of approximately 10 cm, appeared from the anterior wall of the gastric body along the greater curvature. Laparoscopy further showed that non- clotting blood in the abdominal cavity seemed to be from the gastric tumor. After conversion to open surgery for more precise evaluation of the cause of hemoperitoneum and the large friable tumor, gastric wedge resection, including the tumor, was conducted. The final diagnosis was consistent with IMT that originated from the gastric wall.

关键词： Stomach disease Stomach neoplasms Hemoperitoneum Myofibroma Granuloma Plasma cell Stomach surgery

Catalytic Performance of Carbon Smoke over Ag-LSCF Composite Catalysts

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 30-34页

作者： GUO Guanlun han Ming LU Shaomin YU Jing ju Hongling 无 Hubei Key Laboratory of Advanced Technology for Automotive Components&Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of TechnologyWuhan 430070China College of Mechanical and Transportation Southwest Forestry UniversityKunming 650000China

To improve the catalytic performance of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3)(LSCF)towards carbon soot,we utilized the impregnation method to incorporate Ag into the prepared LSCF *** conducted a series of characterization tests and evaluated the soot catalytic activity of the composite catalyst by comparing it with the LaCoO_(3) group,LaFeO_(3) group,and catalyst-free *** results indicate that the Ag-LSCF composite catalyst exhibits the highest soot catalytic activity,with the characteristic temperature values of 376.3,431.1,and 473.9℃at 10%,50%,and 90%carbon soot conversion,*** values are 24.8,20.2,and 23.1℃lower than those of the LSCF *** also shows that LSCF can improve the catalytic activity of soot after compounding with Ag,and reflects the necessity of using catalysts in soot combustion *** characterization and BET test show that Ag-LSCF has more abundant surface-adsorbed oxygen species,larger specific surface area and pore volume than LSCF,which also proves that Ag-LSCF has higher soot catalytic activity.

关键词： metallic composites carbon smoke oxidation perovskite catalyst soot

Effect of silicon carbide-based iron catalyst on reactor optimization for non-oxidative direct conversion of methane

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Journal of Energy Chemistry 2023年第6期81卷 519-532,I0012页

作者： Eun-hae Sim Sung Woo lee Jin ju lee Seung ju han jung Ho Shin Gracia lee Sungrok Ko Kwan-Young lee Yong Tae Kim C1 Gas&Carbon Convergent Research Center Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea Department of Chemical and Biological Engineering Korea University145 Anam-roSeoul 02841Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeoul 03722Republic of Korea Chemical Data-Driven Research Center Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea Prospective Tech.Exploring Section Basic Chemical R&D centerLottechemical Corp.Daejeon 34059Republic of Korea Department of Advanced Materials and Chemical Engineering University of Science and Technology(UST)Gajeong-dongYuseongDaejeon 34113Republic of Korea

The conversion of methane to olefins,aromatics,and hydrogen(MTOAH)can be used to stably obtain hydrocarbons when the effect of the catalytic surface is optimized from the reaction engineering *** this study,Fe/Si C catalysts were packed into a quartz tube *** catalytic surfaces of Si C and the impregnated Fe species decreased the apparent activation energies(E_a)of methane consumption in the blank reactor between 965 and 1020℃.Consequently,the hydrocarbon yield increased by 2.4times at 1020℃.Based on the model reactions of ethane,ethylene,and acetylene mixed with hydrogen in the range of 500-1020℃,an excess amount of Fe in the reactor favored the C-C coupling reaction over the selective hydrogenation of acetylene;consequently,coke formation was favored over the hydrogenation *** gas-phase reactions and catalyst properties were optimized to increase hydrocarbon yields while reducing coke *** 0.2Fe catalyst-packed reactor(0.26 wt%Fe)resulted in a hydrocarbon yield of 7.1%and a coke selectivity ofjusted to be≥*** on these findings,the facile approach of decoupling the reaction zone between the catalyst surface and the gas-phase reaction can provide insights into catalytic reactor design,thereby facilitating the scale-up from the laboratory to the commercial scale.

关键词： Non-oxidative methane conversion Ethylene Aromatic Methane pyrolysis Fe/SiC Coke resistance Catalytic reactor

Association of fluoride exposure with disease burden and neurodevelopment outcomes in children in South Korea

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World Journal of Pediatrics 2024年第10期20卷 1029-1042页

作者： Won Seok lee ju Hee Kim Boeun han Gi Chun lee Hye Ri jung Ye Jin Shin Eun Kyo Ha Eun lee Soonchul lee Man Yong han Department of Pediatrics CHA Ilsan Medical CenterCHA University School of MedicineGoyangRepublic of Korea Department of Pediatrics Kyung Hee University HospitalKyung Hee University College of MedicineSeoulRepublic of Korea Department of Pediatrics CHA Bundang Medical CenterCHA University School of Medicine59 Yatap-RoBundang-GuSeongnam-siGyeonggi-do13496Republic of Korea Multi-Omics Research Center CHA Future Medicine Research InstituteSeongnamRepublic of Korea Department of Computer Science and Engineering Konkuk UniversitySeoulRepublic of Korea School of Medicine CHA UniversityPocheonRepublic of Korea Department of Pediatrics Hallym University Kangnam Sacred Heart HospitalHallym University College of MedicineSeoulRepublic of Korea Department of Pediatrics Chonnam National University HospitalChonnam National University Medical SchoolGwangjuRepublic of Korea Department of Orthopaedic Surgery CHA Bundang Medical CenterCHA University School of Medicine59 Yatap-RoBundang-GuSeongnam-siGyeonggi-do13496Republic of Korea

Background Community water fluoridation is an effective public health strategy for preventing dental caries,*** exist about potential health *** study explores associations between tap water fluoride levels and pediatric disease burden,as well as neurodevelopmental outcomes at 6 years of *** This nationwide population-based cohort study included children born in Korean cities with and without tap water fluoridation projects,between 2006 and 2012,aiming for a fluoride concentration of 0.8±0.2 mg/L in treated tap *** from the National Health Insurance Service were used,spanning from birth to *** relationship between exposure to fluoridated tap water and incidence of 16 childhood diseases that were previously identified as potentially linked to fluoride exposure were ***,we evaluated the neurodevelopmental outcomes across various domains,including gross motor,fine motor,cognition,language,social skills,and self-help *** assessments were performed using data from a comprehensive national health screening program for children aged six *** A fluoride-unexposed group included 22,881 children,whereas a fluoride-exposed group comprised 29,991 children(52%males).Children in the fluoride-exposed group had a decreased risk of dental caries and bone fractures[hazard ratio(95%confidence interval,CI),0.76(0.63–0.93)and 0.89(0.82–0.93),respectively]and increased risk of hepatic failures[1.85,(1.14–2.98)]compared to those in the unexposed ***,the risk ratio of abnormal neurodevelopmental screening outcomes increased by 9%,but this was statistically uncertain(95%CI,0.95–1.26).Conclusions Fluoridated tap water was associated with an increased risk of hepatic failure but a decreased risk of bone fractures in *** association between fluoridated tap water and neurodevelopmental screening outcomes at 6 years remains unclear,highlighting the need for further studies to clarify this associ

关键词： Children-Fluoride.Hepatic failure.Neurodevelopment

A structural relationship between place attachment and intention to conserve landscapes–a case study of Harz National Park in Germany

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Journal of Mountain Science 2017年第5期14卷 998-1007页

作者： Dukjae lee ju-Hyoung lee Department of Forest Resources University of Daegu Department of Forest Resources Yeungnam University

Place attachment is an important motivation for people to spend more time outdoors and to protect *** study explores visitors' intention to conserve natural landscapes based on the relationship with their place attachment to National Park landscape. Structural equation modelling(SEM) was used to determine the relationship between landscape conservation and place attachment. A survey with a structured questionnaire was administered to visitors to the seven designated hiking courses of Harz National Park in Germany. The path coefficient of 0.77 revealed that place dependence positively and significantly affected place attachment, whereas place identity did not. Place attachment had a significant effect on both affective appraisals and visiting satisfaction. Higher place attachment led to higher emotional reaction to landscapes on site and higher satisfaction of visiting the park. Among the variables, visiting satisfaction, but not affective appraisals, played a statistically significant mediating role between place attachment and conservation intention. With a path coefficient of 0.86, conservation intention was highly affected by visiting satisfaction. These results suggest that the managers of National Parks should focus on increasing visiting satisfaction based on how visitors are emotionally bonded with their visiting places, in order to enhance the intentions to conserve the landscape of the visitors to National Parks.

关键词： Place attachment Sense of place Mountain forests Structural Equation Model Landscape preference