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Nano Research 2019年第10期12卷 2559-2567页

作者： Jong-hyun kim Sang Hyo Kweon Sahn Nahm KU-KIST Graduate School of Converging Science and Technology Korea University145 Anam-roSeongbuk-guSeoul 02841Republic of Korea Department of Material Science and Engineering Korea University145 Anam-roSeongbuk-guSeoul 02841Republic of Korea Department of Mechanical Engineering Kobe University1-1 Rokkodai-choNadaKobe 657-8501Japan

A monolayer of Sr2Nb3Oio(SNO)is deposited on the Pt/Ti/SiCWSi(Pt?Si)or Pt/Ti/polyimide(Pt-Pl)substrate by using the Langmuir-Blodgett method and employed as a seed-layer for the growth of a crystalline(Nai_xKx)NbO3(NKN)film at 350℃.The crystalline NKN film is grown along the[001]direction on the SNO/Pt-Si(or SNO/Pt-PI)*** to the presence of oxygen vacancies in the SNO seed-layer,the NKN film exhibits low ferroelectric properties and large leakage *** ameliorate these properties,the SNO/Pt-Si substrate is annealed in a 50 Torr oxygen atmosphere at 300℃,which removes the oxygen ***,the NKN film deposited on this substrate exhibits promising electrical properties,namely a dielectric constant of 278,dissipation factor of 1.7%,a piezoelectric 8nstant of 175 pm`V^-1,and a leakage current density of 6.47 x 10^-7 A cm^-2 at-0.2 MV *** electrical properties are obtained from the NKN film grown on the flexible SNO/Pt-PI substrate at 350°***,the NKN films grown on the SNO seed-layer at 350°C can be applied to electronic devices with flexible polymer substrates.

关键词： lead-free piezoelectric thin films low-temperature-deposition process two-dimensional(2D)nanosheet seed-layers polymer substrates

Airborne bioaerosols and their impact on human health

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Journal of Environmental Sciences 2018年第5期30卷 23-35页

作者： Ki-hyun kim Ehsanul Kabir Shamin Ara Jahan Department of Civil and Environmental Engineering Hanyang UniversitySeoul 04763Republic of Korea Department of Farm Power&MachineryBangladesh Agricultural UniversityMymensinghBangladesh BRAC Clinic DhakaBangladesh

Bioaerosols consist of aerosols originated biologically such as metabolites, toxins, or fragments of microorganisms that are present ubiquitously in the environment. International interests in bioaerosols have increased rapidly to broaden the pool of knowledge on their identification,quantification, distribution, and health impacts（e.g., infectious and respiratory diseases,allergies, and cancer）. However, risk assessment of bioaerosols based on conventional culture methods has been hampered further by several factors such as：（1） the complexity of microorganisms or derivatives to be investigated;（2） the purpose, techniques, and locations of sampling; and（3） the lack of valid quantitative criteria（e.g., exposure standards and dose/effect relationships）. Although exposure to some microbes is considered to be beneficial for health,more research is needed to properly assess their potential health hazards including inter-individual susceptibility, interactions with non-biological agents, and many proven/unproven health effects（e.g., atopy and atopic diseases）.

关键词： Health effect Exposure Infectious diseases Respiratory diseases Cancer Guideline

Effects of oxygen concentration and flow rate on cognitive ability and physiological responses in the elderly

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Neural Regeneration Research 2013年第3期8卷 264-269页

作者： hyun-Jun kim hyun-Kyung Park Dae-Woon Lim Mi-hyun Choi hyun-Joo kim In-Hwa Lee hyung-Sik kim Jin-Seung Choi Gye-Rae Tack Soon-Cheol Chung Department of Obstetrics & Gynecology Konkuk University Department of Laboratory Medicine Seoul Clinical Laboratories Department of Information & Communication Engineering Dongguk University Department of Biomedical Engineering Research Institute of Biomedical EngineeringCollege of Biomedical & Health ScienceKonkuk University

The supply of highly concentrated oxygen positively affects cognitive processing in normal young adults. However, there have been few reports on changes in cognitive ability in elderly subjects following highly concentrated oxygen administration. This study investigated changes in cognitive ability, blood oxygen saturation （%）, and heart rate （beats/min） in normal elderly subjects at three different levels of oxygen [21% （1 L/min）, 93% （1 L/min）, and 93% （5 L/min）] administered during a 1-back task. Eight elderly male （75.3 ＋ 4.3 years old） and 10 female （71.1 ＋ 3.9 years old） subjects, who were normal in cognitive ability as shown by a score of more than 24 points in the Mini-Mental State Examination-Korea, participated in the experiment. The experiment consisted of an adaptation phase after the start of oxygen administration （3 minutes）, a control phase to obtain stable baseline measurements of heart rate and blood oxygen saturation before the task （2 minutes） and a task phase during which the 1-back task was performed （2 minutes）. Three levels of oxygen were administered throughout the three phases （7 minutes）. Blood oxygen saturation and heart rate were measured during each phase. Our results show that blood oxygen saturation increased, heart rate decreased, and response time in the 1-back task decreased as the concentration and amount of administered oxygen increased. This shows that administration of sufficient oxygen for optimal cognitive functioning increases blood oxygen saturation and decreases heart rate.

关键词： neural regeneration clinical practice highly concentrated oxygen cognitive task 1-back task cognitive ability blood oxygen saturation heart rate physiological responses elderly grant-supported paper neuroregeneration

Improved continuous precipitation kinetics and tensile properties of extruded AZ80 alloy through {10-12} twin formation

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Journal of Magnesium and Alloys 2023年第9期11卷 3323-3337页

作者： hyun Ji kim Sumi Jo Sung Hyuk Park Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566the Republic of Korea

This study investigates the effect of{10-12}deformation twins on the continuous precipitation behavior of an extruded Mg-8.0Al-0.5Zn-0.2Mn(AZ80)alloy during *** extruded AZ80 alloy is compressed along the transverse direction to introduce{10-12}twins,followed by an aging treatment at 300℃.The extruded material exhibits a twin-free microstructure with low internal strain energy,whereas the pre-twinned material possesses abundant{10-12}twins and has high internal strain *** aging results reveal that the peak-aging time of the pre-twinned material(1 h)is one-eighth of that of the extruded material(8 h).Although Mg_(17)Al_(12)continuous precipitates(CPs)are observed in both the peak-aged materials,these CPs are much smaller and more densely distributed in the pre-twinned material despite the significantly shorter aging *** CPs size in the peak-aged materials increases in the following order:twinned region in the pre-twinned material(0.47μm)

关键词： AZ80 alloy {10-12}twin Aging Continuous precipitation Tensile properties

High-throughput discovery of plastid genes causing albino phenotypes in ornamental chimeric plants

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Horticulture Research 2023年第1期10卷 249-259页

作者： hyun-Seung Park Jae-Hyeon Jeon Woohyeon Cho Yeonjeong Lee jee Young Park Jiseok kim Young Sang Park hyun Jo Koo Jung Hwa Kang Taek Joo Lee Sang Hoon kim Jin-Baek kim Hae-Yun Kwon Suk-Hwan kim Nam-Chon Paek Geupil Jang Jeong-Yong Suh Tae-Jin Yang Department of Agriculture Forestry and BioresourcesResearch Institute of Agriculture and Life Sciencesand Plant Genomics and Breeding InstituteCollege of Agriculture and Life SciencesSeoul National UniversitySeoul08826Republic of Korea Department of Integrative Biological Sciences and Industry Sejong UniversitySeoul 05006Korea Hantaek Botanical Garden YonginGyeonggi-do17183Republic of Korea Radiation Breeding Research Team Advanced Radiation Technology InstituteKorea Atomic Energy Research InstituteJeongeup 56212Korea Special Forest Resources Division National Institute of Forest ScienceSuwon 16631Korea School of Biological Sciences and Technology Chonnam National UniversityGwangjuSouth Korea Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences Seoul National UniversitySeoul 08826Korea

Chimeric plants composed of green and albino tissues have great ornamental *** unveil the functional genes responsible for albino phenotypes in chimeric plants,we inspected the complete plastid genomes(plastomes)in green and albino leaf tissues from 23 ornamental chimeric plants belonging to 20 species,including monocots,dicots,and *** nine chimeric plants,plastomes were identical between green and albino ***,another 14 chimeric plants were heteroplasmic,showing a mutation between green and albino *** identified 14 different point mutations in eight functional plastid genes related to plastid-encoded RNA polymerase(rpo)or photosystems which caused albinism in the chimeric *** them,12 were deleterious mutations in the target genes,in which early termination appeared due to small deletion-mediated frameshift or single nucleotide *** was single nucleotide substitution in an intron of the ycf3 and the other was a missense mutation in coding region of the rpoC2 *** inspected chlorophyll structure,protein functional model of the rpoC2,and expression levels of the related genes in green and albino tissues of Reynoutria japonica.A single amino acid change,histidine-to-proline substitution,in the rpoC2 protein may destabilize the peripheral helix of plastid-encoded RNA polymerase,impairing the biosynthesis of the photosynthesis system in the albino tissue of *** chimera plant.

关键词： plast substitution ornamental

Characteristics of Atmospheric Circulation Associated with Cold Surge Occurrences in East Asia:A Case Study During 2005/06 Winter

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Advances in Atmospheric Sciences 2008年第5期25卷 791-804页

作者： Tae-Won PARK jee-Hoon JEONG Chang-Hoi HO Seong-Joong kim School of Earth and Environmental Sciences Seoul National University Seoul Korea Department of Earth Sciences University of Gothenburg Gothenburg Sweden Korea Polar Research Institute Incheon Korea

The characteristics of the upper-level circulation and thermodynamical properties for the period when two distinct cold surges broke out over East Asia during the 2005/06 winter are investigated. From early December 2005 to early January 2006, exceptionally cold weather lasted for approximately one month due to two successive cold surges that took place on 2 December 2005 and 2 January 2006, respectively. This study reveals that both involve the upper-tropospheric circulation, which induces the amplification and expansion of the surface Siberian high toward East Asia, but arose from different causes： the former is caused by the upper-level blocking originated from the North Pacific and the latter is caused by the upper-level wave train across the Eurasian Continent. In particular, it is suggested that the lower-tropospheric anomalous wind caused by upper-level circulation anomalies and a steep meridional temperature gradient amplified by phase-locked annual cycle combined to induce very strong cold advection in East Asia, which resulted in exceptionally cold weather that lasted for several weeks. The present results emphasize that the characteristics of the upper-tropospheric circulation can be considered as important precursors to cold surge occurrences in East Asia.

关键词： cold surge Siberian high East Asia East Asian winter monsoon upper-tropospheric circulation

Complications and management of forgotten long-term biliary stents

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World Journal of Gastroenterology 2017年第4期23卷 622-628页

作者： Se Hoon Sohn Jae hyun Park Kook hyun kim Tae Nyeun kim Division of Gastroenterology and Hepatology Department of Internal MedicineYeungnam University College of MedicineDaegu 42415South Korea

AIMTo evaluate complications and management outcomes of retained long-term plastic biliary *** plastic biliary stent placement was performed in 802 patients at Yeungnam University Hospital between January 2000 and December 2014. Follow-up loss with a subsequently forgotten stent for more than 12 mo occurred in 38 patients. We retrospectively examined the cause of biliary stent insertion, status of stents, complications associated with biliary stents and management outcomes of long-term plastic biliary stents. Continuous variables were analyzed using the t test. Observed frequencies in subsets of the study population were compared using Fisher’s exact test and χ2 tests. Statistical significance was defined as P < 0.05 (two-tailed).RESULTSMean age of patients was 73.7 ± 12 years and male-to-female ratio was 2.2:1. Indications of plastic biliary stent insertion were bile duct stones (63.2%, 24/38) and benign bile duct stricture (52.6%, 20/38). Mean duration of retained plastic stent was 22.6 ± 12.2 mo, and in 10 cases (26.3%), stents were retained for more than 24 mo. Common bile duct (CBD) stones or sludge were found in most cases (92.1%, 35/38). The most common complication was acute cholangitis (94.7%, 36/38). Stent removal by endoscopic approach was successfully performed in 92.1% (35/38) of the cases. In 3 cases, an additional plastic stent was inserted alongside the previous stent due to failure of the stent removal. Endoscopic removal of bile duct stones was successful in 73.7% (28/38) of the cases. When patients were divided into two groups by duration of stent placement (12 to 24 mo vs over 24 mo), there were no differences in the development of cholangitis, presence of biliary stones, and success rate of endoscopic removal of stones and biliary *** most common complication of retained long-term plastic biliary stents was acute cholangitis associated with CBD stones. Endos

关键词： Biliary stent Long-term complications Forgotten stents Acute cholangitis Biliary stone

Triboelectric nanogenerators with gold-thin-film-coated conductive textile as floating electrode for scavenging wind energy

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Nano Research 2018年第1期11卷 101-113页

作者： Bhaskar Dudem Dong hyun kim Jae Su Yu Department of Electronic Engineering Kyung Hee University 1732 Deogyeong-daero Giheung-gu Yongin-si Gyeonggi-do 446-701Republic of Korea

We report triboelectric nanogenerators （TENGs） composed of a flexible and cost-effective gold-coated conductive textile （CT） to convert wind energy into electricity. The Au-coated CT is employed because of its high surface roughness resulting from Au nanodots distributed on microsized fibers. Thus, the Au-coated CT with nano/microarchitecture plays an important role in enhancing the effective contact area as well as the output performance of the TENG. Moreover, the surface roughness of the Au-coated CT is controlled by adjusting the Au thermal deposition time or tailoring the diameter of the Au nanodots. At an applied wind speed of 10 m.s-1, a wind-based TENG （W-TENG） with dimensions of 75 mm × 12 mm ×25 mm produces an open-circuit voltage （Voc） of - 39 V and a short-circuit current （Isc） of - 3 A by using the airflow-induced vibrations of an optimized Au-coated CT between two flat polydimethylsiloxane （PDMS） layers. To further specify the device performance, the electric output of the W-TENG is analyzed by varying several parameters such as the distance between the PDMS layer and Au-coated CT, applied wind speed, external load resistance, and surface roughness of the PDMS layers. Introducing an inverse micropyramid architecture on the PDMS layers further improves the output performance of the W-TENG, which exhibits the highest Voc （- 49 V） and Isc （- 5μA） values at an applied wind speed of 6.8 m.s-1. Additionally, the reliability of the W-TENG is also tested by measuring its output current during long-term cyclic operation. Furthermore, the rectified output signals observed by the W-TENG device are used as a direct power source to light 45 green commercial light-emitting diodes connected in series and also to charge capacitors （100 and 4.7μF）. Finally, the output performance of the W-TENG device in an actual windy situation is also investigated.

关键词： triboelectric nanogenerators Au-coated conductivetextile polydimethylsiloxanelayer wind energy

Numerical Computation of Motions and Structural Loads for Large Containership using 3D Rankine Panel Method

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Journal of Marine Science and Application 2017年第4期16卷 417-426页

作者： Jung-hyun kim Yonghwan kim Department of Naval Architecture & Ocean Engineering Seoul National University Seoul 08826 Korea

In this paper, we present the results of our numerical seakeeping analyses of a 6750-TEU containership, which were subjected to the benchmark test of the 2 nd ITTC–ISSC Joint Workshop held in 2014. We performed the seakeeping analyses using three different methods based on a 3D Rankine panel method, including 1) a rigid-body solver, 2) a flexible-body solver using a beam model, and 3) a flexible-body solver using the eigenvectors of a 3D Finite Element Model(FEM). The flexible-body solvers adopt a fully coupled approach between the fluid and structure. We consider the nonlinear Froude–Krylov and restoring forces using a weakly nonlinear approach. In addition, we calculate the slamming loads on the bow flare and stern using a 2D generalized Wagner model. We compare the numerical and experimental results in terms of the linear response, the time series of the nonlinear response, and the longitudinal distribution of the sagging and hogging moments. The flexible-body solvers show good agreement with the experimental model with respect to both the linear and nonlinear results, including the high-frequency oscillations due to springing and whipping vibrations. The rigid-body solver gives similar results except for the springing and whipping.

关键词： Rankine panel method fluid-structure interaction benchmark test containership springing, whipping

Contrast-enhanced ultrasound in the diagnosis of nodules in liver cirrhosis

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World Journal of Gastroenterology 2014年第13期20卷 3590-3596页

作者： Tae Kyoung kim hyun-Jung Department of Medical Imaging Toronto General HospitalUniversity of TorontoToronto ON M5G 2N2Canada

Contrast-enhanced ultrasound(CEUS)using microbubble contrast agents are useful for the diagnosis of the nodules in liver *** can be used as a problem-solving method for indeterminate nodules on computed tomography(CT)or magnetic resonance imaging(MRI)or as an initial diagnostic test for small newly detected liver *** has unique advantages over CT and MRI including no renal excretion of contrast,real-time imaging capability,and purely intravascular *** carcinoma(HCC)is characterized by arterial-phase hypervascularity and later washout(negative enhancement).Benign nodules such as regenerative nodules or dysplastic nodules are usually isoechoic or slightly hypoechoic in the arterial phase and isoechoic in the late ***,there are occasional HCC lesions with atypical enhancement including hypovascular HCC and hypervascular HCC without *** are infrequently detected during HCC surveillance and mostly show rimlike or diffuse hypervascularity followed by rapid *** are often found at HCC surveillance and are easily diagnosed by *** can be effectively used in the diagnostic work-up of small nodules detected at HCC *** is also useful to differentiate malignant and benign venous thrombosis and to guide and monitor the local ablation therapy for HCC.

关键词： Hepatocellular carcinoma Liver cirrhosis Dysplastic nodule Contrast ultrasound Imaging