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A new dimmer for alternating-current directly driven light-emitting-diode lamp

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Journal of Central South University 2012年第2期19卷 374-379页

作者： KIM Jong-hyun ryu Myung-hyo YOON Hyok-min SONG Eui-ho School of Mechatronics Changwon National University

A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.

关键词：发光二极管调光器直接驱动交流电流灯泡半导体场效应晶体管 MOSFET 脉宽控制

无碱CO_(2)加氢高效制甲酸Pd/g-C_(3)N_(4)催化剂的单原子和纳米簇的协同作用

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Chinese Journal of Catalysis 2023年第4期47卷 214-221页

作者： Eun Hyup Kim min hee Lee Jeehye Kim Eun Cheol Ra Ju Hyeong Lee Jae Sung Lee 蔚山国家科学技术研究所能源与化学工程学院(UNIST) 韩国

气候变化威胁人类的生存.化石燃料的过度使用导致CO_(2)持续排放是引起全球变暖和气候变化的主要因素,须尽快减少CO_(2)排放.捕获CO_(2)并将其转化为高附加值的燃料和化学品从而循环利用是减少CO_(2)净排放的有效措施.其中,CO_(2)催化... 详细信息

气候变化威胁人类的生存.化石燃料的过度使用导致CO_(2)持续排放是引起全球变暖和气候变化的主要因素,须尽快减少CO_(2)排放.捕获CO_(2)并将其转化为高附加值的燃料和化学品从而循环利用是减少CO_(2)净排放的有效措施.其中,CO_(2)催化加氢制甲酸(HCOOH)是碳捕获与利用(CCU)的有效途径之一,其产物HCOOH可用于防腐剂、牲畜饲料抗菌剂和食品添加剂,也可作为氢载体和直接甲酸燃料电池的燃料.目前,工业上生产HCOOH的工艺包括两个步骤:甲醇和CO在强碱条件下反应生成甲酸甲酯(HCO_(2)CH_(3)),随后水解为HCOOH.该工艺利用来自化石燃料的两种原料,排放出大量CO_(2),同时在水解步骤中使用了过量的酸性水,因此对生态环境产生一定的危害.近年来,以CO_(2)为可再生原料合成HCOOH被广泛研究,人们探索了电化学、光化学、生物和热化学反应等多种途径将CO_(2)还原为HCOOH,以期实现CO_(2)循环利用.上述方法距实际应用尚有一定距离,其中,CO_(2)催化加氢制HCOOH过程最先进,它与当前许多化学工业过程相似.由于CO_(2)分子的化学稳定性,CO_(2)加氢生成HCOOH在热力学上不利,可通过有机碱和无机碱形成甲酸-碱配合物,推动反应向生成HCOOH方向移动.然而,从甲酸基配合物中提取HCOOH需要额外的分离步骤,因此在无碱条件下直接将CO_(2)加氢生成HCOOH非常重要.本课题组致力于研究无碱条件下g-C_(3)N_(4)负载的Pd(记为Pd/CN)催化剂催化CO_(2)加氢合成HCOOH,前期研究(***.,2016,52,14302-14305和***.,2021,396,395-401)发现,通过控制Pd负载量可改变催化剂中Pd单原子/Pd纳米团簇的比例,且当两种状态Pd达到最佳比例时,催化剂催化活性最高.这表明在无碱CO_(2)加氢过程中,Pd单原子与纳米团簇间存在协同作用.此外,最近有关于单原子和纳米团簇在负载金属催化剂中不同作用的报道,如NixMg1-xO催化逆水气变换反应,Ir1/In_(2)O_(3)和Pd/Fe_(3)O_(4)催化CO_(2)加氢制乙醇反应等,这些工作得出相似的结论:单原子金属对CO_(2)活化有效,而纳米团簇对H_(2)活化有效.这对于设计以CO_(2)和H_(2)为反应物的金属催化剂很重要.本工作旨在考察类似的机理是否适用于Pd/CN催化剂在无碱条件下催化CO_(2)加氢制HCOOH过程.通过控制Pd负载量,合成了含有不同比例Pd单原子和Pd纳米团簇的Pd/CN催化剂,Pd与g-C_(3)N_(4)表面碱性位间的强静电相互作用使合成含有大量Pd单原子的Pd/CN催化剂成为可能.在Pd/CN催化剂催化无碱CO_(2)加氢制HCOOH过程中,当两种状态Pd达到最佳比例时,Pd单原子和Pd纳米簇之间存在协同作用,此时催化剂活性最高.实验表明,Pd纳米簇主要通过解离吸附参与H_(2)活化,Pd单原子对CO_(2)活化更有效.在最佳单原子比(单原子数/(单原子数+纳米簇)为41%)时,该催化剂表现出最高的活性,优于文献报道的相似反应条件下Pd催化剂活性.这些发现将为以CO_(2)和H_(2)分子为反应物的反应的催化剂设计提供一定的参考.

关键词：无碱CO_(2)加氢制甲酸 Pd/g-C_(3)N_(4) 单原子催化剂纳米簇催化剂协同效应

Development of a Concentration Measurement Technique for Steady State Solid-liquid Mixing using a Neural Network

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Journal of Thermal Science 2013年第5期22卷 478-483页

作者： Deog hee Doh Joo Ho Yum Gyeong Rae Cho Myung Ho Kim Gyong Won ryu Masahiro Takei Division of Mechanical and Energy Systems Engineering Korea Maritime UniversityYeongdo-gu Busan Korea Graduate School Korea Maritime UniversityYeongdo-gu Busan Korea R&D Institute-5 Agency for Defense DevelopmentJochiwongil 462Yuseong Daejeon 305-152 Korea Graduate School of Mechanical Engineering Artificial Science Division Chiba UniversityJapan

A measurement technique that can measure the concentration of the solid particles in liquid flow was *** measurement system consists of a color camera and three LCD *** solid particles were put at the bottom of a cylindrical mixing tank in which JetA1 oil was *** mixing of the solid particles was performed by rotating a propeller type agitator with three different rotation speed(500,600,700 r/min).Mixing state was visualized by the LCD displays and a color *** color intensity of the glass particles changes with their *** color information was decoded into three principle colors R,G,and B so that,the calibration curve of color-to-concentration was performed using these information.A neural network was used for this *** transient concentration field of the solid particles was quantitatively visualized.

关键词：测量技术固液混合神经网络浓度场液晶显示器彩色摄像机固体颗粒颜色信息

Enhanced thermoelectric properties of NbCoSn half-Heuslers through in-situ nanocrystallization of amorphous precursors during the consolidation process

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Journal of Materials Science & Technology 2023年第34期165卷 39-48页

作者： Chanwon Jung Kyuseon Jang Hail Park Jeongin Jang Hanhwi Jang Byungchul Kang Kitae Park Siyuan Zhang Ruben Bueno Villoro SuDong Park Ho Jin ryu Yeon Sik Jung min-Wook Oh Christina Scheu Seong-Hoon Yi Pyuck-Pa Choi Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak-roYuseong-guDaejeon 34141Republic of Korea Max-Planck-Institut für Eisenforschung GmbH Düsseldorf 40237Germany Electrical Materials Research Division Energy Conversion Research CenterKorea Electrotechnology Research Institute(KERI)Changwon 51543Republic of Korea Department of Materials Science and Metallurgical Engineering Kyungpook National University80 DaehakroDaegu 41566Republic of Korea Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak-roYuseong-guDaejeon 34141Republic of Korea Department of Materials Science and Engineering Hanbat National University125 Dongseodae-roYuseong-guDaejeon 34158Republic of Korea

Tailoring nanostructures is a general approach used to obtain enhanced thermoelectric properties for halfHeusler compounds because the wide areas of grain and phase boundaries could be scattering centers that lower lattice thermal ***,a common fabrication method based on the sintering of crystalline precursors crushed from as-cast alloy ingots has limitations in obtaining a homogeneous microstructure without microsized impurity phases,owing to residual elemental segregation from *** this study,we used amorphous NbCoSn alloys as a precursor for the sintered specimen to obtain a homogeneous NbCoSn bulk specimen without microsized impurity phases and segregation,which led to the enhanced Seebeck coefficient due to the high purity of the half-Heusler phase after ***,superplasticity originating from amorphous features enabled the powders to be largely deformed during the sintering process,even at a low sintering temperature(953 K).This resulted in less oxidation at both,the grain boundary and the interior,as the O diffusion pathway was blocked during the sintering *** a result,the NbCoSn0.95Sb0.05 specimen using an amorphous precursor exhibited an enhanced zT of 0.7,due to the increase in the power factor and a decrease in lattice thermal conductivity compared to the specimen using a crystalline precursor.

关键词： Half-Heusler compounds Amorphous Superplasticity Segregation Atom probe tomography

Zn-doped nickel iron(oxy)hydroxide nanocubes passivated by polyanions with high catalytic activity and corrosion resistance for seawater oxidation

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Journal of Energy Chemistry 2023年第6期81卷 82-92,I0004页

作者： So Jung Kim heechae Choi Jeong Ho ryu Kang min Kim Sungwook Mhin Arpan Kumar Nayak Junghwan Bang minyeong Je Ghulam Ali Kyung Yoon Chung Kyeong-Han Na Won-Youl Choi Sunghwan Yeo Jin Uk Jang HyukSu Han Department of Energy Engineering Konkuk University120 Neungdong-roGwangjin-guSeoul 05029Republic of Korea Theoretical Materials&Chemistry Group Institute of Inorganic ChemistryUniversity of CologneGreinst.650939CologneGermany Materials Lab Geobuk-ro 25-50Incheon 22793Republic of Korea Department of Materials Science and Engineering Korea National University of Transportation50 Daehak-roChungjuChungbuk 27469Republic of Korea Korea Institute of Industrial Technology 137-41 Gwahakdanji-roGangneung-siGangwon 25440Republic of Korea Department of Advanced Materials Engineering Kyonggi UniversitySuwon 16227Republic of Korea Korea Institute of Industrial Technology 156 Gaetbeol-roYeonsu-guIncheon 406-840Republic of Korea U.S.-Pakistan Center for Advanced Studies in Energy(USPCASE) National University of Sciences and Technology(NUST)H-12IslamabadPakistan Energy Storage Research Center Korea Institute of Science and TechnologyHwarang-ro 14-gil 5Seongbuk-guSeoul 02792Republic of Korea Division of Energy and Environment Technology KIST SchoolKorea University of Science and TechnologySeoul 02792Republic of Korea Department of Metal and Materials Engineering Gangneung-Wonju National University 7 JukheongilGangneungGangwon 25457Republic of Korea Smart Hydrogen Energy Center Gangneung-Wonju National University7 JukheongilGangneungGangwon 25457Republic of Korea Innovative Fuel Development Division Korea Atomic Energy Research InstituteDaedeok-daero 989-111Yuseong-guDaejeon 305-353Republic of Korea

Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion ***-scale electrolysis of freshwater may deplete water resources and cause water scarcity ***,seawater electrolysis is a potential solution to the future energy and water *** seawater electrolysis,it is critical to develop cost-effective electrocatalysts to split seawater without chloride ***,we present zinc-doped nickel iron(oxy)hydroxide nanocubes passivated by negatively charged polyanions(NFZ-PBA-S)that exhibits outstanding catalytic activity,stability,and selectivity for seawater *** dopants and polyanion-rich passivated surface layers in NFZ-PBA-S could effectively repel chlorine ions and enhance corrosion resistance,enabling its excellent catalytic activity and stability for seawater oxidation.

关键词： Seawater splitting Oxygen evolution reaction Electrocatalyst Layered double hydroxide Sulfidation

Wave-Tide-Surge Coupled Simulation for Typhoon Maemi

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China Ocean Engineering 2013年第2期27卷 141-158页

作者： Byung Ho Choi Byung Il min Kyeong Ok Kim Jin hee Yuk Department of Civil and Environmental Engineering Sungkyunkwan University Marine Environments & Conservation Research Division Korea Institute of Ocean Science & Technology Supercomputing Center Korea Institute of Science and Technology Information

The main task of this study focuses on studying the effect of wave-current interaction on currents, storm surge and wind wave as well as effects of current induced wave refraction and current on waves by using numerical models which consider the bottom boundary layer and sea surface roughness parameter for shallow and smooth bed area around Korean Peninsula. The coupled system （unstructured-mesh SWAN wave and ADCIRC） run on the same unstructured mesh. This identical and homogeneous mesh allows the physics of wave-circulation interactions to be correctly resolved in both models. The unstructured mesh can be applied to a large domain allowing all energy from deep to shallow waters to be seamlessly followed. There is no nesting or overlapping of structured wave meshes, and no interpolation is required. In response to typhoon Maemi （2003）, all model components were validated independently, and shown to provide a faithful representation of the system＇s response to this storm. The waves and storm surge were allowed to develop on the continental shelf and interact with the complex nearshore environment. The resulting modeling system can be used extensively for prediction of the typhoon surge. The result show that it is important to incorporate the wave-current interaction effect into coastal area in the wave-tide-surge coupled model. At the same time, it should consider effects of depth-induced wave breaking, wind field, currents and sea surface elevation in prediction of waves. Specially, we found that：（1） wave radiation stress enhanced the current and surge elevation otherwise wave enhanced nonlinear bottom boundary layer decreased that, （2） wind wave was significantly controlled by sea surface roughness thus we cautiously took the experimental expression. The resulting modeling system can be used for hindcasting （prediction） the wave-tide-surge coupled environments at complex coastline, shallow water and fine sediment area like areas around Korean Peninsula.

关键词： typhoon Maemi finite element model tide-surge-wave coupling

Optimization of thermoelectric properties of n-type Bi_2(Te,Se)_3 with optimizing ball milling time

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Rare Metals 2018年第4期37卷 351-359页

作者： Ji-hee Son min-Wook Oh Bong-Seo Kim Su-Dong Park Thermoelectric Conversion Research Center Korea Electrotechnology Research Institute Department of Materials Science and Engineering Hanbat National University

The thermoelectric properties at elevated temperature were investigated for n-type Bi2（Te,Se）3 which is obtained from ball milling processed powder with various milling times. Electrical properties such as electrical resistivity and Seebeck coefficient are clearly dependent on milling time, in which the carrier concentration is attributed to the change of the electrical properties. The concentrations of the defects are also varied with the ball milling time, which is the origin of the carrier concentration variation. Even though finer grain sizes are obtained after the long ball milling time, the temperature dependence of the thermal conductivity is not solely understood with the grain size, whereas the electrical contribution to the thermal conductivity should be also considered. The highest figure of merit value of ZT = 0.83 is achieved at 373 K for the optimized samples, in which ball milling time is 10 h. The obtained ZT value is 48% improvement over that of the 0.5-h sample at 373 K.

关键词： Thermoelectric properties Ball milling Bi2Te3 Seebeck coefficient Grain size Thermalconductivity

Weave-pattern-dependent fabric piezoelectric pressure sensors based on polyvinylidene fluoride nanofibers electrospun with 50 nozzles

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npj Flexible Electronics 2022年第1期6卷 699-707页

作者： Da Bin Kim Ju Han Sun min Sung min Seong Kim Bo Kyoung Choi Sung Jun Park Hyae Rim Hong Hong Je Choi Byeong Kon Kim Chung hee Park Jong Hoo Paik Joon-Seok Lee Yong Soo Cho Department of Materials Science and Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Textile Engineering and Technology Yeungnam UniversityGyeongsan 38541Republic of Korea Deparment of Textile Merchandising and Fashion DesignSeoul National UniversitySeoul 08826Republic of Korea Samsung Electro-Mechanics Co.Ltd. Suwon 16674Republic of Korea Ceratorq Inc. Seoul 08511Republic of Korea Electronic Materials and Component Center Korea Institute of Ceramic Engineering and TechnologyJinju 52851Republic of Korea

Wearable pressure sensors having versatile device structures have been extensively investigated to achieve high sensitivity under mechanical ***,we introduce piezoelectric pressure sensors based on fabrics woven using polyvinylidene fluoride(PVDF)weft and polyethylene terephthalate(PET)warp yarns with different weave structures:1/1(plain),2/2,and 3/3 weft rib *** dependence of the pressure-sensing performance on the weave pattern is demonstrated with an actual large-scale fabric up to the~2 m *** optimized pressure sensor with a 2/2 weft rib pattern produced a high sensitivity of 83 mV N−1,which was 245%higher than that of the 1/1 *** detection performance of the optimal fabric was extensively evaluated with a variety of ambient input sources,such as pressing,bending,twisting,and crumpling,as well as various human ***,a large allfabric pressure sensor with arrayed touch pixel units demonstrated highly sensitive and stable sensing performance.

关键词： pattern fluoride piezoelectric

Epstein-Barr virus-positive diffuse large B-cell lymphoma with human immunodeficiency virus mimicking complicated frontal sinusitis:A case report

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World Journal of Clinical Cases 2021年第7期9卷 1654-1660页

作者： Seokho Yoon Kyeong Hwa ryu Hye Jin Baek Hyo Jung An Yeon-hee Joo Department of Nuclear Medicine and Molecular Imaging Gyeongsang National University School of Medicine and Gyeongsang National University Changwon HospitalChangwon 51472South Korea Department of Radiology Gyeongsang National University School of Medicine and Gyeongsang National University Changwon HospitalChangwon 51472South Korea Department of Radiology Institute of Health SciencesGyeongsang National University School of MedicineJinju 52727South Korea Department of Pathology Gyeongsang National University School of Medicine and Gyeongsang National University Changwon HospitalChangwon 51472South Korea Department of Otorhinolaryngology Gyeongsang National University School of Medicine and Gyeongsang National University Changwon HospitalChangwon 51472South Korea

BACKGROUND Primary non-Hodgkin’s lymphoma of the frontal sinus is extremely *** addition,Epstein-Barr virus(EBV)has been reported to play a role in the development of human immunodeficiency virus(HIV)-related malignant *** the best of our knowledge,there is no report for the HIVassociated,EBV-positive primary diffuse large B-cell lymphoma(DLBCL)in the frontal *** SUMMARY We present a unique case of HIV-associated,EBV-positive DLBCL in the frontal sinus in a 46-year-old *** tomography of paranasal sinuses revealed dense opacification of the right frontal sinus with combined soft tissue *** on the clinical and radiological findings,the initial diagnosis was complicated frontal sinusitis,presenting Pott’s puffy ***,HIV testing was positive on preoperative laboratory test,and the frontal sinus lesion was confirmed as EBV-positive DLBCL on *** Through this article,we suggest that EBV-positive DLBCL should be considered as possible diagnosis for patients with nonspecific space-occupying lesion of the paranasal *** also highlight an importance of clinical suspicion in diagnosing HIV infection because HIV serology is not routinely tested in patients with paranasal sinus problem.

关键词： Lymphoma Paranasal sinus Human immunodeficiency virus Epstein-Barr virus Computed tomography Case report