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Replica higher-order topology of Hofstadter butterflies in twisted bilayer graphene

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npj Computational Materials 2023年第1期9卷 783-791页

作者： Sun-woo kim Sunam Jeon Moon Jip Park Youngkuk kim Department of Physics KAISTDaejeonRepublic of Korea Department of Materials Science and Metallurgy University of CambridgeCambridgeUK Department of Energy Science Sungkyunkwan UniversitySuwonRepublic of Korea Center for Theoretical Physics of Complex Systems Institute for Basic Science(IBS)DaejeonRepublic of Korea Department of Physics Hanyang UniversitySeoulRepublic of Korea Department of Physics Sungkyunkwan UniversitySuwonRepublic of Korea

The Hofstadter energy spectrum of twisted bilayer graphene(TBG)is found to have recursive higher-order topological *** demonstrate that higher-order topological insulator(HOTI)phases,characterized by localized corner states,occur as replicas of the original HOTIs to fulfill the self-similarity of the Hofstadter *** show the existence of exact flux translational symmetry in TBG at all commensurate *** on this result,we identify that the original HOTI phase at zero flux is re-entrant at a half-flux periodicity,where the effective twofold rotation is *** addition,numerous replicas of the original HOTIs are found for fluxes without protecting *** the original HOTIs,replica HOTIs feature both localized corner states and edge-localized real-space topological *** replica HOTIs originate from the different interaction scales,namely,intralayer and interlayer couplings,in *** topological aspect of Hofstadter butterflies revealed in our results highlights symmetry-protected topology in quantum fractals.

关键词： properties spectrum topological

Effect of ammonia gas etching on growth of vertically aligned carbon nanotubes/nanofibers

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Transactions of Nonferrous Metals Society of China 2011年第A01期21卷 130-134页

作者： Sang-Gook kim Sooh-Yung kim Hyung-woo LEE Department of Mechanical Engineering Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02139 USA National Core Research Center for Hybrid Materials Solution Pusan National University

The etching effect of ammonia （NH3） on the growth of vertically aligned nanotubes/nanofibers （CNTs） was investigated by direct-current plasma enhanced chemical vapor deposition （DC-PECVD）. NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etching is different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth, the single strand CNT growth requires shorter etching time （5 min） than large catalytic patterns （10 rain） since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy （HTEM） shows fishbone structure of CNTs grown by PECVD.

关键词： carbon nanotube ammonia etching nickel catalyst plasma enhanced chemical vapor deposition (PECVD)

Insect community structures along elevation gradients on ***-san, South Korea

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Journal of Forestry Research 2015年第4期26卷 1013-1018页

作者： Young-Min shin Il-Kwon kim Jong-woo Nam Da-Som kim Seung Jin Roh Jun Hyoung Jeon Jong Kyun Park Dong-Pyeo Lyu Bong-woo Lee Bong-Kyu Byun Division of Forest Biodiversity Korea National Arboretum Department of Biological Science and Biotechnology Hannam University Department of Applied Biology Kyungpook National University Department of Forest Sciences Sangji University

Insect communities along three elevation gra- dients on Mt. Seongak-san, South Korea, were investigated from May to September 2013 using traps in order to collect basic data for distributional monitoring of species in a forest ecosystem. A total of 2698 individuals of 309 moth species of 18 families were collected in bucket-light traps, along with 196 individuals of 26 ground-beetle species and 11,276 individuals of 14 ant species in pit-fall traps. The insect community at each site was analyzed using analysisof variance and non-metric multidimensional scaling （NMS）. The ground-beetle and ant abundances varied with elevation. The NMS showed distinct clusters of moths between the ground-beetle and ant distributions with ele- vation and month. The community-level responses of these insect groups to those gradients were analyzed.

关键词： Insect community Elevation ANOVA Bucket-light trap Pit-fall trap South Korea

An evaluation of the influence of impurity concentration and composition in concrete on activation and radiation dose in the reactor facility

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辐射防护 2020年第6期40卷 486-490页

作者： Jae Hyun kim Myeong Hyeon woo Chang Ho shin Jong Kyung kim Department of Nuclear Engineering Hanyang University222Wangsimni-roSeongdongSeoulKorea

The content analysis of radioactive waste and radiation dose evaluation is considered as one of the important factors in the reactor facility *** kind of buildings consists of the concrete for the most part and uses it as the structure and shield of the ***,the concrete has impurities such as cobalt,europium,nickel,and cesium with specific content depending on the production method or manufacturing *** radioactive nuclides generated from the fundamental components of concrete are considered that it is less contributed to the radiation dose because they are beta decay nuclides in ***,impurities of irradiated concrete in the reactor facilities,are considered occasionally an important evaluation factor for induced *** this study,the influence on the activation of impurities in concrete was evaluated from the radiation dose and induced activity *** calculation was evaluated at the bio-shield which is one of the areas with the highest neutron irradiation among the concrete structure in the reactor *** results show that radioactive nuclides with gamma decay were produced in these ***,the radiation dose of concrete with impurities was higher than concrete without *** increased radiation dose was quantified through the content of impurities.

关键词： radiation dose concrete impurity activation analysis

3D designed battery-free wireless origami pressure sensor

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Microsystems & Nanoengineering 2022年第6期8卷 35-46页

作者： Taeil kim Amirhossein Hassanpoor Kalhori Tae-Ho kim Chao Bao woo Soo kim Additive Manufacturing Laboratory School of Mechatronic Systems EngineeringSimon Fraser UniversitySurrey V3T 0A3 BCCanada

A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports *** pressure sensors have been studied extensively,battery-free functions working in wireless detection have not been studied ***,we report a 3D-structured origami-based architecture sensor for wireless pressure *** developed an architectured platform for wireless pressure sensing through inductorcapacitor(LC)sensors and a monopole antenna.A personalized smart insole with Miura-ori origami designs has been 3D printed together with conductive 3D printed sensors *** monitoring of resonant frequency and intensity changes of LC sensors have been demonstrated to monitor foot pressure for different *** sensitivity of the wireless pressure sensor is tunable from 15.7 to 2.1 MHz/kPa in the pressure ranges from 0 to 9 kPa and from 10 to 40 kPa,*** proposed wireless pressure-sensing platform can be utilized for various applications such as orthotics,prosthetics,and sports gear.

关键词： battery free utilized

Development and application of a multi-step porcine in vitro system to evaluate feedstuffs and feed additives for their efficacy in nutrient digestion, digesta characteristics, and intestinal immune responses

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Animal Nutrition 2024年第2期17卷 265-282页

作者： Hee Yeon kim Jun-Ok Moon Sung woo kim Application Center CJ Blossom Park Department of Animal Science North Carolina State University

In vitro model provides alternatives to the use of live animals in research. In pig nutrition, there has been a tremendous increase in in vivo research over the decades. Proper utilization of in vitro models could provide a screening tool to reduce the needs of in vivo studies, research duration, cost, and the use of animals and feeds. This study aimed to develop a multi-step porcine in vitro system to simulate nutrient digestion and intestinal epithelial immune responses affected by feedstuffs and feed additives. Seven feedstuffs(corn, corn distillers dried grains with solubles [corn DDGS], barley, wheat, soybean meal, soy protein concentrates, and Corynebacterium glutamicum cell mass [CGCM]), feed enzymes(xylanase and phytase), and supplemental amino acids(arginine, methionine, and tryptophan), were used in this in vitro evaluation for their efficacy on digestibility, digesta characteristics, and intestinal health compared with the results from previously published in vivo studies. All in vitro evaluations were triplicated. Data were analyzed using Mixed procedure of SAS9.4. Evaluations included(1) nutrient digestibility of feedstuffs,(2) the effects of feed enzymes, xylanase and phytase, on digestibility of feedstuffs and specific substrates, and(3) the effects of amino acids, arginine, tryptophan, and methionine, on anti-inflammatory, anti-oxidative, and anti-heat stress statuses showing their effects(P < 0.05) on the measured items. Differences in dry matter and crude protein digestibility among the feedstuffs as well as effects of xylanase and phytase were detected(P < 0.05), including xylo-oligosaccharide profiles and phosphorus release from phytate. Supplementation of arginine, tryptophan, and methionine modulated(P < 0.05) cellular inflammatory and oxidative stress responses. The use of this in vitro model allowed the use of 3 experimental replications providing sufficient statistical power at P < 0.05. This indicates in vitro models can have increased prec

关键词： Digestion Feed additive Feedstuff In vitro Intestine Pig

High-power and long-life supercapacitive performance of hierarchical, 3-D urchin-like W18049 nanostructure electrodes

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Nano Research 2016年第3期9卷 633-643页

作者： Sangbaek Park Hyun-woo Shim Chan woo Lee Hee Jo Song Jae-Chan kim Dong-Wan kim Department of Materials Science and Engineering Seoul National University Seoul 151-744 Republic of Korea School of Civil Environmental and Architectural Engineering Korea University Seou1136-713 Republic of Korea

We report the facile, one-pot synthesis of 3-D urchin-like W18O49 nanostructures （U-WO） via a simple solvothermal approach. An excellent supercapacitive performance was achieved by the U-WO because of its large Brunauer-Emmett- Teller （BET） specific surface area （ca. 123 m2.g-1） and unique morphological and structural features. The U-WO electrodes not only exhibit a high rate-capability with a specific capacitance （Csp） of -235 F·g-1 at a current density of 20 A.g-1, but also superior long-life performance for 1,000 cycles, and even up to 7,000 cycles, showing -176 F·g-1 at a high current density of 40 A.g-1.

关键词： hierarchical structure W18O49 high-power long cycle life supercapacitor

Transmural penetration of sigmoid colon and rectum by retained surgical sponge after hysterectomy

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World Journal of Gastroenterology 2016年第10期22卷 3052-3055页

作者： woo Young shin Chan Hyuk Im Sun Keun Choi Yun-Mee Choe Kyung Rae kim Department of Surgery Inha University HospitalInha University College of Medicine

Gossypiboma is a surgical sponge that is retained in the body after the operation. A 39-year-old female presented with vague lower abdominal pain, fever, and rectal discharge 15 mo after hysterectomy. The sponge remaining in the abdomen had no radiopaque marker. Therefore a series of radiographic evaluations was fruitless. The surgical sponge was found in the rectosigmoid colon on colonoscopy. The sponge penetrated the sigmoid colon and rectum transmurally, forming an opening on both sides. The patient underwent low anterior resection and was discharged without postoperative complications.

关键词： Gossypiboma Textiloma Retained foreign object Surgical sponge Radiopaque marker

Segregation of voiced and unvoiced components from residual of speech signal

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Journal of Central South University 2012年第2期19卷 496-503页

作者： JO Cheol-woo kim Jae-hee School of Mechatronics Changwon National University

In conventional source-filter models, voiced and unvoiced components were considered independently. However, in practice it was difficult to separate the source into two parts. An actual source consists of a mixture of two sources and the ratio varies according to the content or the intention of speaker. It had been investigated to separate the voiced and unvoiced components for different source models. Source signals were modeled based on the residual signal measured from inverse filtering. Three different source models were assumed. The parameters of each model were optimized for the original speech signal using a genetic algorithm. The resulting parameters were compared in terms of the mel-cepstral distance to the original signal, the spectrogram and the spectral envelope from the synthesized signal. The optimization method achieves an improvement of 15% for the Klatt model, but there is little improvement in the modified residual case.

关键词： voice source model synthesis optimization genetic algorithm