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Microstructure and Tensile Behavior of a Nano-Structured Al-Fe Based Alloy

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Journal of Rare Earths 2004年第z2期22卷 65-68页

作者： Won-Yong Kim jae-sung park Mok-Soon Kim Tae-Yeub Ra Advanced Materials R&D Center Korea Institute of Industrial Technology # 472Kajwa-dongSuh-guIncheon 404-254Korea School of Materials Science and EngineeringInha University # 253Yonghyun-dongNam-guIncheon 402-751Korea School of Materials Science and EngineeringInha University # 253Yonghyun-dongNam-guIncheon 402-751Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology # 472Kajwa-dongSuh-guIncheon 404-254Korea

Room temperature deformation behavior of A1-8Fe-2Mo-2V-1Zr alloy produced by spray forming and subsequent warm-extrusion at 693 K and/or rolling at 423 K was investigated in terms of tensile test and microstructural *** the specimen processed by spray forming and warm extrusion, the microstructure consisting of equiaxed grains with the average grain size of 500 nm in the matrix phase and uniformly dispersed fine intermetallic A13(Fe, Mo, V, Zr) and A16(Fe, Mo, V, Zr) phases less than 100 nm was characterized. It was revealed that subsequent warm rolling after warm extrusion promotes precipitation of a fine dispersoid from the supersaturated matrix phase. Warm rolling was found to be effective to increase the yield and tensile strength in the high strain rate regime. Elongation of the warm rolled specimen showed highe r value than extruded specimen over the whole strain rate region studied.

关键词： microstructure tensile deformation A1-Fe based alloy spray forming extrusion warm rolling precipitation strain rate sensitivity

Detection of the Pine Wilt Disease Tree Candidates for Drone Remote Sensing Using Artificial Intelligence Techniques

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Engineering 2020年第8期6卷 919-926页

作者： Mutiara Syifa sung-jae park Chang-Wook Lee Division of Science Education Kangwon National UniversityGangwon-do 24341Republic of Korea

Pine wilt disease(PWD)has recently caused substantial pine tree losses in Republic of *** is considered a severe problem due to the importance of pine trees to Korean people,so this problem must be handled ***,we examined the history of PWD and found that it had already spread to some regions of Republic of Korea;these became our study *** detection of PWD is *** used drone remote sensing techniques to detect trees with similar symptoms to trees infected with *** remote sensing was employed because it yields high-quality images and can easily reach the locations of pine *** differentiate healthy pine trees from those with PWD,we produced a land cover(LC)map from drone images collected from the villages of Anbi and Wonchang by classifying them using two classifier methods,i.e.,artificial neural network(ANN)and support vector machine(SVM).Furthermore,compared the accuracy of two types of Global Positioning System(GPS)data,collected using drone and hand-held devices,for identifying the locations of trees with *** then divided the drone images into six LC classes for each study area and found that the SVM was more accurate than the ANN at classifying trees with *** Anbi,the SVM had an overall accuracy of 94.13%,which is 6.7%higher than the overall accuracy of the ANN,which was 87.43%.We obtained similar results in Wonchang,for which the accuracy of the SVM and ANN was 86.59%and 79.33%,*** terms of the GPS data,we used two type of hand-held GPS *** device 1 is corrected by referring to the benchmarks sited on both locations,while the GPS device 2 is uncorrected device which used the default setting of the GPS *** data collected from hand-held GPS device 1 was better than those collected using hand-held GPS device 2 in ***,in Anbi,we obtained better results from GPS device 2 than from GPS device *** Anbi,the error in the data from GPS device 1 was 7.08 m,while that of the GPS

关键词： Pine wilt disease Drone remote sensing Artificial neural network Support vector machine Global positioning system

A Survey of Sediment Fineness and Moisture Content in the Soyang Lake Floodplain Using GPS Data

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Engineering 2021年第2期7卷 252-259页

作者： Mutiara Syifa Prima Riza Kadavi sung jae park Chang-Wook Lee Division of Science Education Kangwon National UniversityGangwon-do 24341Republic of Korea

Soyang Lake is the largest lake in Republic of Korea bordering Chuncheon,Yanggu,and Inje in Gangwon *** is widely used as an environmental resource for hydropower,flood control,and water ***,we conducted a survey of the floodplain of Soyang Lake to analyze the sediments in the *** used global positioning system(GPS)data and aerial photography to monitor sediment deposits in the Soyang Lake *** from three GPS units were compared to determine the accuracy of sampling location *** samples were collected at three sites:two in the eastern region of the floodplain and one in the western region.A total of eight samples were collected:Three samples were collected at 10 cm intervals to a depth of 30 cm from each site of the eastern sampling point,and two samples were collected at depths of 10 and 30 cm at the western sampling *** were collected and analyzed for vertical and horizontal trends in particle size and moisture *** sizes of the sediment samples ranged from coarse to very coarse sediments with a negative slope,which indicate eastward movement from the *** probability of a breach was indicated by the high water content at the eastern side of the floodplain,with the eastern sites showing a higher probability than the western *** results of this study indicate that analyses of grain fineness,moisture content,sediment deposits,and sediment removal rates can be used to understand and predict the direction of breach movement and sediment distribution in Soyang Lake.

关键词： Soyang Lake Grain fineness number Moisture content GPS data Digital surface model

Prevalence of clonorchiasis in patients with gastrointestinal disease: A Korean nationwide multicenter survey

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World Journal of Gastroenterology 2009年第1期15卷 86-94页

作者： Ho Gak Kim Jimin Han Myung-Hwan Kim Kyu Hyun Cho Im Hee Shin Gwang Ha Kim jae Seon Kim Jin Bong Kim Tae Nyeun Kim Tae Hyeon Kim Tae Hyo Kim jae Woo Kim Ji Kon Ryu Young-Soo Moon Jong Ho Moon sung jae park Chan Guk park sung-Jo Bang Chang Heon Yang Kyo-Sang Yoo Byung Moo Yoo Kyu Taek Lee Dong Ki Lee Byung Seok Lee Sang Soo Lee Seung Ok Lee Woo Jin Lee Chang Min Cho Young-Eun Joo Gab Jin Cheon Young Woo Choi jae Bok Chung Yong Bum Yoon Department of Internal Medicine Catholic University of Daegu School of Medicine Daegu 705-718 South Korea Department of Internal Medicine Asan Medical Center University of Ulsan College of Medicine Seoul 138-736 South Korea Department of Medical Statistics Catholic University of Daegu School of Medicine Daegu 705-718 South Korea Department of Internal Medicine Pusan National University School of Medicine Busan 602-739 South Korea Department of Internal Medicine Korea University College of Medicine Seoul 136-705 South Korea Department of Internal Medicine Hallym University College of Medicine Chuncheon 200-704 South Korea Department of Internal Medicine Yeungnam University College of Medicine Daegu 705-717 South Korea Department of Internal Medicine Wonkwang University College of Medicine Iksan Jeonbuk 570-711 South Korea Department of Internal Medicine Gyeongsang National University School of Medicine Jinju Gyeongnam 660-702 South Korea Department of Internal Medicine Yonsei University Wonju College of Medicine Wonju Gangwon 220-701 South Korea Department of Internal Medicine Seoul National University College of Medicine Seoul 110-799 South Korea Department of Internal Medicine lnje University College of Medicine Seoul 139-713 South Korea Department of Internal Medicine Soonchunhyang University College of Medicine Bucheon Gyunggi 420-767 South Korea Department of Internal Medicine Inje University College of Medicine Busan 614-735 South Korea Department of Internal Medicine Chosun University College of Medicine Gwangju Jeonbuk 501-717 South Korea Department of Internal Medicine Ulsan University Hospital University of Ulsan College of Medicine Ulsan 681-714 South Korea Department of Internal Medicine Dongguk University College of Medicine Gyeongju Gyeongbuk 791-707 South Korea Department of Internal Medicine Hallym University College of Medicine Anyang Gyeonggi 431-070 South Korea Department of Internal Medicine Ajou University School of Medicine Suwon

AIM： To investigate prevalence of C/onorchis sinensis in patients with gastrointestinal symptoms, and the relation of the infection to hepatobiliary diseases in 26 hospitals in Korea. METHODS： Consecutive patients who had been admitted to the Division of Gastroenterology with gastrointestinal symptoms were enrolled from March to April 2005. Of those who had been diagnosed with clonorchiasis, epidemiology and correlation between infection and hepatobiliary diseases were surveyed by questionnaire. RESULTS： Of 3080 patients with gastrointestinal diseases, 396 （12.9%） had clonorchiasis and 1140 patients （37.2%） had a history of eating raw freshwater fish. Of those with a history of raw freshwater fish ingestion, 238 （20.9%） patients had clonorchiasis. Cholangiocarcinoma was more prevalent in C. sinensis-infected patients than nonnfected patients [34/396 （8.6%） vs 145/2684 （5.4%）, P = 0.015]. Cholangiocarcinoma and clonorchiasis showed statistically significant positive cross-relation （P = 0.008）. Choledocholithiasis, cholecystolithiasis, cholangitis, hepatocellular carcinoma, and biliary pancreatitis did not correlate with clonorchiasis. CONCLUSION： Infection rate of clonorchiasis was still high in patients with gastrointestinal diseases in Korea, and has not decreased very much during the last two decades. Cholangiocarcinoma was related to clonorchiasis, which suggested an etiological role for the parasite.

关键词： Clonorchis sinensis Epidemiology Cholangiocarcinoma Korea Multicenter study Clonorchiasis

Regulation of sleep by astrocytes in the hypothalamic ventrolateral preoptic nucleus

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Neural Regeneration Research 2025年第4期20卷 1098-1100页

作者： jae-Hong Kim Ruqayya Afridi Il-sung Jang Maan Gee Lee Kyoungho Suk Brain Korea 21 four KNU Convergence Educational Program of Biomedical Sciences for Creative Future Talents School of MedicineKyungpook National UniversityDaeguRepublic of Korea Department of Pharmacology School of MedicineKyungpook National UniversityDaeguRepublic of Korea Department of Pharmacology School of DentistryKyungpook National UniversityDaeguRepublic of Korea Brain Science&Engineering Institute Kyungpook National UniversityDaeguRepublic of Korea

Astrocytes are functionally dynamic cells that support neurons in multiple ways throughout an organism’s *** astrocytic regulation of neuronal activity has been increasingly recognized in recent *** are now recognized as playing a more complex role than mere bystanders in the central nervous ***,their role in regulating the sleep neurocircuitry is not well *** this perspective,we highlight the role of astrocytes in sleep modulation,with a particular focus on regulatory mechanisms related to the ventrolateral preoptic nucleus(VLPO)of the *** briefly discuss recent literature reporting the role of VLPO astrocytes in regulating sleep-associated behaviors.

关键词： sleep ventrolateral astrocytes

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采用化学镀铜的高性能3D打印电子产品

磁性元件与电源 2018年第10期 148-151页

作者： Jin Rong Jian Taei I Kim jae sung park Jiacheng Wang Woo Soo Kim 加拿大西蒙弗雷泽大学机电系统工程学院可伸缩设备实验室

本文介绍了3D打印电子元件3D环形空芯电感器的设计和性能验证，它采用了多材料基熔融沉积成型（FDM）3D打印技术和化学镀铜制作。本文研究了不同磁芯形状和绕组数的环形电感器的设计；带有10和13匝绕组的网形和半圆形磁芯。化学镀铜薄... 详细信息

本文介绍了3D打印电子元件3D环形空芯电感器的设计和性能验证，它采用了多材料基熔融沉积成型（FDM）3D打印技术和化学镀铜制作。本文研究了不同磁芯形状和绕组数的环形电感器的设计；带有10和13匝绕组的网形和半圆形磁芯。化学镀铜薄膜确保3D打印的环形塑料结构具有传导行为。当设计变化时，电感可靠地得到证明，应用的源频率为100kHz到2MHz。采用了RL电路来测试所制造的电感器的相位超前特性以及相应的相位角变化。

关键词：打印技术化学镀铜性能验证 3D 电子产品熔融沉积成型磁芯形状电感器

Variations in dynamic recrystallization behavior and mechanical properties of AZ31 alloy with extrusion temperature

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Journal of Magnesium and Alloys 2023年第7期11卷 2351-2365页

作者： jae Won Cha sung Hyuk park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigates the effects of extrusion temperature on the dynamic recrystallization(DRX)behavior of a Mg-3Al-1Zn-0.3Mn(AZ31,wt%)alloy during hot extrusion and on the microstructural characteristics and mechanical properties of materials extruded at 350 and 450℃.An increase in the extrusion temperature causes a decrease in the amount of strain energy accumulated in the material during extrusion,because of promoted activation of pyramidalslip and dynamic *** reduced strain energy weakens the DRX behavior during extrusion,which eventually results in a decrease in the area fraction of recrystallized grains of the extruded *** material extruded at 450℃has coarser grains and a stronger basal fiber texture than that extruded at 350℃.As the extrusion temperature increases from 350 to 450℃,the tensile yield strength(TYS)of the extruded material increases from 191.8 to 201.5 MPa,whereas its compressive yield strength(CYS)decreases from 122.5 to 111.0 MPa;consequently,its tension-compression yield stress ratio(CYS/TYS)decreases from 0.64 to *** increase in the TYS is attributed mainly to the stronger texture hardening and strain hardening effects of the extruded material,and the decrease in the CYS is attributed to the reduced twinning stress resulting from grain coarsening and texture *** microstructural and textural evolutions of the materials during extrusion and the deformation and hardening mechanisms of the extruded materials are discussed in detail.

关键词： Mg-Al-Zn alloy Extrusion Dynamic recrystallization Microstructure Yield asymmetry

Sensitivity analysis for axis rotation diagrid structural systems according to brace angle changes

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Earthquake Engineering and Engineering Vibration 2017年第4期16卷 783-791页

作者： jae-Kwang Yang Long-Yang Li sung-Soo park Department of Architectural Engineering Pusan National UniversityKorea Department of Architectural Engineering Pusan National UniversityDoctor of EngineeringKorea

General regular shaped diagrid structures can express diverse shapes because braces are installed along the exterior faces of the structures and the structures have no columns. However, since irregular shaped structures have diverse variables, studies to assess behaviors resulting from various variables are continuously required to supplement the imperfections related to such variables. In the present study, materials elastic modulus and yield strength were selected as variables for strength that would be applied to diagrid structural systems in the form of Twisters among the irregular shaped buildings classified by Vollers and that affect the structural design of these structural systems. The purpose of this study is to conduct sensitivity analysis for axial rotation diagrid structural systems according to changes in brace angles in order to identify the design variables that have relatively larger effects and the tendencies of the sensitivity of the structures according to changes in brace angles and axial rotation angles.

关键词： sensitivity analysis axial rotation-diagrid structure lateral behaviors

Effects of homogenization temperature on microstructure and mechanical properties of high-speed-extruded Mg–5Bi–3Al alloy

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Journal of Magnesium and Alloys 2022年第10期10卷 2833-2846页

作者： jae Won Cha Sang-Cheol Jin jae-Gil Jung sung Hyuk park School of Materials Science and Engineering Kyungpook National University80 DaehakroDaegu 41566Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effects of billet homogenization temperature on the dynamic recrystallization behavior during high-speed extrusion and resultant microstructure and tensile properties of the Mg–5Bi–3Al(BA53,wt%)*** billets homogenized at 350 and450℃(350H and 450H billets)are extruded at a high speed of 69 m/*** 350H billet has a relatively smaller grain size and a higher abundance of fine Mg3Bi2particles compared to the 450H *** extrusion of the 350H billet,enhanced dynamic recrystallization occurs as a result of its finer grains and abundance of particles,while the growth of recrystallized grains is suppressed by the grain-boundary pinning effect of ***,the extruded 350H material is characterized by smaller grains,relatively greater number of Mg3Bi2particles,and a higher internal strain energy than the extruded 450H *** tensile strength of the extruded 350H material is higher than that of the extruded 450H material owing to stronger grain-boundary hardening,particle hardening,and strain hardening *** extruded 350H material also exhibits a higher tensile elongation as its smaller grains inhibit the formation of crack-inducing undesirable twins during *** results from this study demonstrate that a decrease in the homogenization temperature from 450 to 350℃leads to improved strength and ductility in the high-speed-extruded BA53 material.

关键词： Mg–Bi–Al alloy High-speed extrusion Homogenization Dynamic recrystallization Tensile properties