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Fabrication of ultrafine Nd-Fe-B powder by a modified reduction-diffusion process

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Rare Metals 2006年第Z2期25卷 223-226页

作者： jang T.S. LEE D.H. cHOI c.J. SEO W.S. LEE y.H. Department of Electronic Materials Engineering Sunmoon University Korea Powder Materials Research center Korea Institute of Machinery and Materials Korea Advanced Materials Analysis & Evaluation center Korea Institute of Ceramic Engineering and Technology Korea

In order to obtain ultrafine Nd-Fe-B powder, a spray-dried precursor was treated by reduction-diffusion (R/D) process. And, unlike the conventional R/D process, calcium reduction that is a crucial step for the formation of Nd2Fe14B was performed without conglomerating the precursor with ca powder. By adopting this modified process, it is possible to synthesize the hard magnetic Nd2Fe14B at the reaction temperature as low as 850 ℃. The average size of Nd2Fe14B particles that are uniformly distributed in the optimally treated powder was cles were enclosed with thin layers of Nd-rich phase. Typical magnetic properties of such powder without eliminating impurity caO were iHc=～5.9 kOe, Br=～5.5 kG, and (BH)max=～6 MGOe.

关键词： NdFeB powder spray drying reduction-diffusion process Nd2Fe14B magnetic powder

Directly Modulated 10 Gb/s Signal Transmission over 320 km of Negative Dispersion Fiber for Regional Metro Network

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光学学报 2003年第S1期23卷 533-534页

作者： H. S. chung y. G. jang y. c. chung 1 Korea Advanced Institute of Science and Technology 373-1 Gusong-dong Yusong-gu Daejon 305-701 Korea2 Samsung Electronics 94-1 Imsudong Gumi KyungBuk 730-350 KoreaKorea Advanced Institute of Science and Technology 373-1 Gusong-dong Yusong-gu Daejon 305-701 Korea

We demonstrate the transmission of directly modulated 10-Gb/s WDM signals over 320 km of negative dispersion fiber (dispersion: -2.5 ps/km/nm @1550 nm) without dispersion compensation. The results indicate that a regional metro WDM network could be implemented cost-effectively by using the proposed negative dispersion fiber and direct modulated lasers.

关键词： of in et over Directly Modulated 10 Gb/s Signal Transmission over 320 km of Negative Dispersion Fiber for Regional Metro Network WDM for

Schottky barrier modulation of bottom contact SnO_(2) thin-film transistors via chloride-based combustion synthesis

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Journal of Materials Science & Technology 2023年第17期148卷 199-208页

作者： Bongho jang Junhee Lee Hongki Kang Jaewon jang Hyuk-Jun Kwon Department of Electrical Engineering and computer Science DGISTDaegu 42988South Korea School of Electronic and Electrical Engineering Kyungpook National UniversityDaegu 41566South Korea School of Electronics Engineering Kyungpook National UniversityDaegu 41566South Korea convergence Research Advanced centre for Olfaction DGISTDaegu 42988South Korea

The enhanced carrier flow at the interface between Au and SnO_(2)semiconductors,which initially form Schottky contacts,is realized using chloride-based combustion ***-based combustion sys-tems can achieve chlorine(cl)doping effects as well as conversion to crystalline SnO_(2)films at clearly lower temperatures(∼250℃)than conventional *** to the cl doping effect,the high carrier concentration can induce thin potential barriers at the metal/semiconductor(MS)junctions,resulting in carrier injection by *** a result,compared to conventional SnO_(2)thin-film transistors,the de-vices fabricated by combustion synthesis exhibit significantly improved electrical performance with field-effect mobility of 6.52 cm 2/Vs(∼13 times),subthreshold swing of 0.74 V/dec,and on/offratio of∼10^(7)below 300℃.Furthermore,because of the enhanced tunneling carriers induced by the narrowed barrier width,the Schottky barriers are significantly reduced from 0.83 to 0.29 eV(65%decrease)at 250℃and from 0.42 to 0.17 eV(60%decrease)at 400℃.Therefore,chloride-based combustion synthesis can con-tribute to developing SnO_(2)-based electronics and flexible devices by achieving both high-quality oxide films and improved current flow at the MS interface with low-temperature annealing.

关键词： SnO_(2) combustion Sol-gel Schottky contact Thin-film transistors

A Structural Topic Model for Exploring User Satisfaction with Mobile Payments

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computers, Materials & continua 2022年第11期73卷 3815-3826页

作者： jang Hyun Kim Jisung jang yonghwan Kim Dongyan Nan Department of Human-Artificial Intelligence Interaction Sungkyunkwan UniversitySeoul03063Korea Department of Interaction Science Sungkyunkwan UniversitySeoul03063Korea Department of Applied Artificial Intelligence Sungkyunkwan UniversitySeoul03063Korea NAVER Green Factory Seongnam13561Korea

This study explored user satisfaction with mobile payments by applying a novel structural topic ***,we collected 17,927 online reviews of a specific mobile payment(i.e.,PayPal).Then,we employed a structural topic model to investigate the relationship between the attributes extracted from online reviews and user satisfaction with mobile ***,we discovered that“lack of reliability”and“poor customer service”tend to appear in negative ***,the terms“convenience,”“user-friendly interface,”“simple process,”and“secure system”tend to appear in positive *** the basis of information system success theory,we categorized the topics“convenience,”“user-friendly interface,”and“simple process,”as system *** addition,“poor customer service”was categorized as service ***,based on the previous studies of trust and security,“lack of reliability”and“secure system”were categorized as trust and security,*** outcomes indicate that users are satisfied when they perceive that system quality and security of specific mobile payments are *** the contrary,users are dissatisfied when they feel that service quality and reliability of specific mobile payments is ***,our research implies that a novel structural topic model is an effective method to explore mobile payment user experience.

关键词： Mobile payment user satisfaction online review structural topic model

Molecular mechanisms and cellular process in signal transduction pathway related to air pollutants in obstructive lung diseases:A mini-review

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BIOcELL 2023年第8期47卷 1703-1708页

作者： AN-SOO jang Division of Allergy and Respiratory Medicine Department of Internal MedicineSoonchunhyang University Bucheon Hospital170 Jomaru-roBucheon-siGyeonggi-do14584Korea

Exposure to air pollutants such as PM_(10),PM_(2.5),PM_(0.1),O_(3),cO,NO2,and SO_(2),and biological pollutants are important factors causing the evolution and furtherance of obstructive lung diseases(OLD),including asthma and chronic obstructive pulmonary disease(cOPD).Asthma is the most frequent chronic inflammatory airway disease,characterized by breathlessness,wheezing,chest tightness,and cough,together with the presence of exaggerated expiratory airflow fluctuation that varies over *** is a heterogeneous lung condition characterized by chronic respiratory symptoms such as dyspnea,cough,expectoration,and/or exacerbations due to abnormalities of the airways and/or alveoli that cause persistent,often progressive,airflow *** the molecular mechanisms and cellular processes based on the development of OLD on exposure to air pollutants will provide insights into the solution of pathogenesis,prevention,and treatment of these *** molecular mechanisms and cellular process involved in signal transduction pathway plays a role in the binding of extracellular signaling molecules and ligands to receptors placed on the cell surface or on the inner side cell that trigger inflammation that occurs,especially when something important enters the cell to bring into a cascade *** binding then alters the cell metabolism,shape,and gene expression in the *** review aimed to reveal the effect of air pollutants on the molecular mechanisms and cellular processes involved in the signal transduction pathways in OLD.

关键词： Air pollutants Obstructive lung diseases Signal pathway

A Note on the Universal Factorization Property of Groups

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Algebra colloquium 2021年第4期28卷 635-644页

作者： Injo Hur jang Hyun Jo Department of Mathematics Education Chonnam National University Gwangju 61186Korea Department of Mathematics Sogang UniversitySeoul 04107Korea

We give criteria when a full subcategory D of the category of groups has c-universal factorization property(c-UFP)or c-strong universal factorization property(c-SUFP)for a certain category of groups *** a byproduct,we give affirmative answers to three unsettled questions in[***,***,Universal factorization property of certain polycyclic groups,*** *** 204(2006)555-567].

关键词： hereditary productive universal factorization property

FATIGUE LIVES FOR INDUcTION HARDENED SHAFTS MATERIALS AccORDING TO THE ENVIRONMENTAL TEMPERATURES

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Acta Metallurgica Sinica(English Letters) 2005年第5期18卷 585-593页

作者： D.G. Lee K.c. jang J.M. Kuk I.S. Kim Korea Institute of Industrial Technology Gwangju 506-824 Korea Dept. of Mechanical Engineering Mokpo National University Mokpo 534-729 Korea

Rotary bending fatigue tests were carried out with two kinds of materials, S43c and S50c, using the front engine and front drive shaft （FF shaft） of vehicle. The specimens were induction hardened about 1.0mm depth from the specimen surface, and the hardness value on the surface was about HRc56-60. The tested environment temperatures were -30, 25 and 80℃ in order to look over effect of the induction hardening and the environmental temperatures on the fatigue characteristics. The fatigue limit of induction hardened specimens increased more about 45% than non-hardened specimens showing that the endurances of S43c and S50c were 98.1 and 107.9MPa in non-hardened samples, 147.1 and 156.9MPa in hardened samplesrespectably. The maximum tensile and compressive stress on the small circular defect was about ＋250 and -450MPa respectively when circular defect is situated on top and bottom. The fatigue life increased 80, 25 and -30℃ in order regardless of hardening. In comparison of the fatigue lives on the basis of tested result at 25℃, the fatigue lives of non-hardened specimens decreased about 35%, but that of hardened specimens decreased about only 5% at 80℃ more than at 25℃. And fatigue life of non-hardened and hardened specimens were about 110% and 120% higher at -30℃ than that of 25℃. Based on the result of stress distribution near the defect, the tensile and compressive stress repeatedly generated by load direction were the largest on the small circular defect due to the stress concentration.

关键词： induction hardening fatigue test front engine and front drive shaft,fatigue crack fatigue life fatigue life ratio

PHySIcAL PROPERTIES AND ENVIRONMENTAL PERFORMANcE OF STEAM-cURED cONcRETE cONTAINING FLUE-GAS DESULFURIZATION GyPSUM

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Journal of Green Building 2021年第1期16卷 3-15页

作者： Hongseok jang Seungyoung So Joenbuk National University Department of Architectural EngineeringKorea. Joenbuk National University Department of Architectural EngineeringResearch Center of Industrial TechnologyKorea

Flue-gas desulfurization(FGD)gypsum has occasionally been used as an additive to ***,appropriate facilities are required to ensure the environmen-tally safe processing of FGD gypsum and the resulting cement material *** facilities are yet to be developed because the amount of FGD gypsum used is still small when compared with the vast amounts of FGD gypsum *** this study,we analyze the effect of FGD gypsum addition on the physical properties,stabilization,and radon count of steam-cured mortar and compare its performance with air-cured *** results show that the steam-cured pozzolanic hydration products of ettringite and c-S-H promote the densification of the mortar structure,thereby resulting in nanopore size reduction and increased strength of FGD gypsum mortar subsequent to the steam-cured hydration ***,our environmental test results indicate that steam-cured pozzolanic materials composed of FGD gypsum are environmentally safer than air-cured cementitious materials.

关键词： FGD gypsum nanopores leaching toxicity recycled material

Impacts of Wettability on Immiscible Fluid Flow Pattern-Microfluidic chip Experiment

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china Petroleum Processing & Petrochemical Technology 2019年第1期21卷 80-89页

作者： Zheng Xianglei jang Jaewon Municipal Testing Laboratory New York USA Department of civil and Environmental Engineering Hanyang University

Immiscible fluid flow is frequently found in resource recovery or soil remediation. The flow pattern in the porous media is affected by the wettability of pore surface. In this study, quartz substrates and microfluidic chips are treated by silica nanoparticles(SNP) and triethoxy(octyl)silane(TES) to fabricate the water-wet and oil-wet surfaces. The wettability of the treated-surface is measured in term of contact angle for several combinations of surrounding fluid and a liquid droplet. The effect of the wettability on the fluid flow pattern is explored by injecting oil and water alternately into the surface-treated microfluidic chips. The results reveal that the SNP-coated quartz substrate shows strong water-wet property and the TES coating makes water-repellent/oil-wet surfaces. In addition, it is found that the maximum and minimum oil and water saturation during alternate injection of oil and water depends on the surface wettability of the microfluidic chips. The characteristics of the pore-scale fluid flow pattern are also described.

关键词： wettability contact angle nanoparticle coating hydrophilic hydrophobic microfluidic chip