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Chinese Physics B 2011年第7期20卷 367-372页

作者： chang Woo lee A.John Peter Department of Chemical Engineering and Green Energy Center College of EngineeringKyung Hee University1 SeochunGihungYonginGyeonggi 446-701Republic of Korea Department of Physics Government Arts and Science CollegeMelur-625106India

The binding energy of an exciton in a wurtzite GaN/GaAlN strained cylindrical quantum dot is investigated theoretically. The strong built-in electric field due to the spontaneous and piezoelectric polarizations of a GaN/GaAlN quantum dot is included. Numerical calculations are performed using a variational procedure within the single band effective mass approximation. Valence-band anisotropy is included in our theoretical model by using different hole masses in different spatial directions. The exciton oscillator strength and the exciton lifetime for radiative recombination each as a function of dot radius have been computed. The result elucidates that the strong built-in electric field influences the oscillator strength and the recombination life time of the exciton. It is observed that the ground state exciton binding energy and the interband emission energy increase when the cylindrical quantum dot height or radius is decreased, and that the exciton binding energy, the oscillator strength and the radiative lifetime each as a function of structural parameters （height and radius） sensitively depend on the strong built-in electric field. The obtained results are useful for the design of some opto-photoelectronic devices.

关键词： quantum dot donor bound excitons oscillator strength

Bioinspired Segment Robot with Earthworm-like Plane Locomotion

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Journal of Bionic Engineering 2016年第2期13卷 292-302页

作者： chang-Woo Song Dong-Jun lee Seung-Yop lee Department of Mechanical Engineering Sogang University 1 Shinsu-dong Mapo-gu Seoul 121-742 Republic of Korea

In this paper, a miniaturized segment robot using solenoids is developed to mimic the plane locomotion of earthworms. The bioinspired robot is composed of five segmented bodies, and one segment has two solenoid actuators. This robot can move linearly and it can also turn due to the pair of solenoid actuators that facilitate the earthworm-like peristaltic locomotion. We have designed a miniaturized solenoid with a permanent magnet plunger in order to increase the total electromagnetic force. A theoretical analysis is performed to predict the linear and turning motions of each segment, and the optimal profiles of input signals are obtained for fast locomotion. Experiments are then conducted to determine the linear and turning motions of the segment robot. It takes about 0.5 s for the five segments to complete one cycle of the peristaltic locomotion. In experiments, the segment robot is shown to have the linear and angular velocities of 27.2 mm·s^-1 （0.13 body-length per second） and 2 degrees per second, respectively.

关键词： bioinspired robot earthworm peristaltic locomotion solenoid segmented robot

Electronic and optical properties of CdS/CdZnS nanocrystals

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Chinese Physics B 2012年第8期21卷 441-448页

作者： A.John Peter chang Woo lee epartment of Chemical Engineering and Green Energy Center College of EngineeringKyung Hee University1 SeochunGihungYonginGyeonggi 446-701S.Korea Department of Physics Govt.Arts CollegeMelurMadurai-62510India Department of Chemical Engineering and Green Energy Center College of EngineeringKyung Hee University1 SeochunGihungYonginGyeonggi 446-701S.Korea

Cd1-xZnxS nanocrystals are prepared by a co-precipitation method with different atomic fractions of Zn. The texture, structural transformation and optical properties with increasing x value in Cd1-xZnxS are studied with scanning electron microscopy, electron diffraction patterning, and absorption spectra respectively. Quantum confinement in a strained CdS/Cd1-xZnxS related nanodot with various Zn content values is investigated theoretically. Binding energies on exciton bound CdS/CdxZn1-xS quantum dot are computed, with consideration of the internal electric field induced by the spontaneous and piezoelectric polarizations, and thereby the interband emission energy is calculated as a function of the dot radius. The optical band gap from the UV absorption spectrum is compared with the interband emission energy computed theoretically. Our results show that the average diameter of composite nanoparticles ranges from 3 nm to 6 nm. The X-ray diffraction pattern shows that all the peaks shift towards the higher diffracting angles with an increase in Zn content. The lattice constant gradually decreases as the Zn content increases. The strong absorption edge shifts towards the lower wavelength region and hence the band gap of the films increases as the Zn content increases. The values of the absorption edge are found to shift towards the shorter wave length region and hence the direct band gap energy varies from 2.5 eV for the CdS film and 3.5 eV for the ZnS film. Our numerical results are in good agreement with the experimental results.

关键词： quantum dots quasicrystals semiconductor

Synthesis of crosslinked polystyrene particles by seeded batch polymerization with monomer absorption

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 153-159页

作者： Ki-chang lee Han-Ah WI Department of Polymer Science and Engineering Engineering Research Institute Gyeongsang National University

A highly crosslinked, monodispersed polystyrene（PS） particle was prepared by a seeded batch dispersion polymerization with a monomer absorption method. Prior to polymerization, 1,9 lam monodispersed PS seed particles were treated under an optimum condition of monomer absorption. The effects of divinylbenzebe（DVB） concentration and polymerization temperature were examined for styrene（in PS seed）/styrene（in the second stage） mass ratio of 1：1 in the medium range of EtOH/water mass ratio of 100/0-80/20 and 2.3 μm uniform crosslinked PS particles containing 15%-20% （mass fraction） DVB were prepared at 60-70 ℃. The results show that monomer absorption before the second stage of polymerization is more effective to prepare highly crosslinked monodispersed PS particles.

关键词： crosslinked polystyrene particle seeded batch dispersion polymerization monomer absorption divinylbenzene (DVB)

Half-Covered 'Glitter-Cake' AM@SE Composite:A Novel Electrode Design for High Energy Density All-Solid-State Batteries

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Nano-Micro Letters 2025年第05期 471-486页

作者： Min Ji Kim Jin-Sung Park Jin Woong lee Sung Eun Wang Dowoong Yoon Jong Deok lee Jung Hyun Kim Taeseup Song Ju Li Yun Chan Kang Dae soo Jung Energy and Environmental Division Korea Institute of Ceramic Engineering and Technology Department of Materials Science and Engineering Korea University Department of Nuclear Science and Engineering Massachusetts Institute of Technology Department of Materials Science and Engineering Ajou University Department of Energy Systems Research Ajou University Department of Energy Engineering Hanyang University Department of Materials Science and Engineering Massachusetts Institute of Technology

All-solid-state batteries（ASSBs） are pursued due to their potential for better safety and high energy density. However, the energy density of the cathode for ASSBs does not seem to be satisfactory due to the low utilization of active materials（AMs） at high loading. With small amount of solid electrolyte（SE） powder in the cathode, poor electrochemical performance is often observed due to contact loss and non-homogeneous distribution of AMs and SEs, leading to high tortuosity and limitation of lithium and electron transport pathways. Here, we propose a novel cathode design that can achieve high volumetric energy density of 1258 Wh L-1at high AM content of 85 wt% by synergizing the merits of AM@SE core–shell composite particles with conformally coated thin SE shell prepared from mechanofusion process and small SE particles. The core–shell structure with an intimate and thin SE shell guarantees high ionic conduction pathway while unharming the electronic conduction. In addition, small SE particles play the role of a filler that reduces the packing porosity in the cathode composite electrode as well as between the cathode and the SE separator layer. The systematic demonstration of the optimization process may provide understanding and guidance on the design of electrodes for ASSBs with high electrode density, capacity, and ultimately energy density.

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UBVVI Surface Photometry of the Spiral Galaxy NGC 300 in the Sculptor Group

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Chinese Journal of Astronomy and Astrophysics 2004年第4期4卷 299-310页

作者： Sang Chul Kim Hwankyung Sung Hong soo Park Eon-chang Sung Korea Astronomy Observatory Taejon 305-348Republic of KoreaDepartment of Astronomy and Space ScienceSejong University98 Gunja-dongGwangjin-guSeoul 143-747Republic of KoreaAstronomy ProgramSEESSeoul National UniversitySeoul 151-742Republic of KoreaKorea Astronomy ObservatoryTaejon 305-348Republic of Korea

We present UBVI surface photometry over a 20.5' × 20.5' area of the late-type spiral galaxy NGC 300. We have derived isophotal maps, surface brightness profiles, ellipticity profiles, position angle profiles, and color profiles. By merging our I-band measurements with those of Boker et al. based on Hubble Space Telescope observations, we have obtained combined I-band surface brightness profiles for the region 0.02' < r < 500' and have decomposed the profiles into three components: a nucleus, a bulge, and an exponential disk.

关键词： galaxies: spiral - galaxies: photometry - galaxies: individual(NGC 300) - galaxies: nuclei

“One stone,two birds”solvent system to fabricate microcrystalline cellulose–Ti_(3)C_(2)T_(x)nanocomposite film as a flexible dielectric and thermally conductive material

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Nano Research 2023年第2期16卷 3240-3253页

作者： Yong-Zhu Yan Shuwei Li Sung soo Park Wei-Jin Zhang Jun Seok lee Jung Rae Kim Dong Gi Seong chang-Sik Ha Department of Polymer Science and Engineering School of Chemical EngineeringPusan National UniversityBusan 46241Republic of Korea School of Chemical and Biomolecular Engineering Pusan National UniversityBusan 46241Republic of Korea Division of Advanced Materials Engineering Dong-Eui UniversityBusan 47340Republic of Korea

A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was *** MCC–MXene nanocomposite film was fabricated by casting a solution containing N,N-dimethylacetamide/lithium chloride(DMAc/LiCl)-soluble MCC and DMAcdispersible MXene nanosheets,followed by humidity control *** MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial ***,the nanocomposite film with 20 wt.%MXene content achieved a desirable permittivity of 71.4 at 102 Hz(a 770%improvement against that of neat cellulose),while the dielectric loss only increased by 1.8 times(from 0.39 to 0.70).The obtained nanocomposite films with 20 wt.%and 30 wt.%MXene exhibited remarkable in-plane thermal conductivities of 8.523 and 9.668 W∙m^(−1)∙K^(−1),respectively,owing to the uniform dispersion and selfalignment of the MXene layered ***,the uniformly dispersed MXene nanosheets in the MCC network with interfacial interaction(hydrogen bonding)and mechanical entanglement endowed the nanocomposite films with excellent mechanical properties and ***,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of ***,using DMAc/LiCl as the solvent system not only improves the compatibility between MCC and MXene but also avoids the problem of easy oxidation of MXene in aqueous *** the high stability of the MCC–MXene solution and enhanced properties of the MCC–MXene films,the proposed strategy manifests great potential for fabricating natural biomass-based dielectric materials.

关键词： Ti_(3)C_(2)T_(x) microcrystalline cellulose flexible dielectric thermally conductive N,N-dimethylacetamide/lithium chloride(DMAc/LiCl) compatibility

Microstructure and corrosion resistance of a Mg2Sn-dispersed Mg alloy subjected to pulsed electron beam treatment

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Journal of Magnesium and Alloys 2020年第2期8卷 345-351页

作者： Daseul lee Beomcheol Kim soo-Min Baek Jisoo Kim Hyung Wook Park Jung Gu lee Sung soo Park School of Materials Science and Engineering Ulsan National Institute of Science and TechnologyUlsan 44919Republic of Korea School of Mechanical Aerospace and Nuclear EngineeringUlsan National Institute of Science and TechnologyUlsan 44919Republic of Korea School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea

We report that the corrosion resistance of a Mg-Sn-based alloy with MgzSn precipitates can be considerably improved by surface modification using pulsed electron beam *** alloy subjected to a pulse electron beam treatment showed a modified surface layer with a thickness of〜12 μm,appearing more resistant to corrosion attack than the bare surface of the *** 0.6 M NaCl solution,the alloys with and without the surface modification exhibited average corrosion rates of 4.3 and 8.1 mm y^-1,*** improved corrosion resistance was attributed to reduced cathodic activation,resulting from the surficial reduction of relatively noble Mg2Sn precipitates.

关键词： Magnesium alloy Mg2Sn Intermetallic compound Pulsed electron beam treatment Corrosion

Characterization of hidden rules linking symptoms and selection of acupoint using an artificial neural network model

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Frontiers of Medicine 2019年第1期13卷 112-120页

作者： Won-Mo Jung In-soo Park Ye-Seul lee chang-Eop Kim Hyangsook lee Dae-Hyun Hahm Hi-Joon Park Bo-Hyoung Jang Younbyoung Chae Department of Science in Korean Medicine Graduate SchoolKyung Hee UniversitySeoul 130-701Republic of Korea Acupuncture & Meridian Science Research Center College of Korean MedicineKyung Hee UniversitySeoul 130-701Republic of Korea Department of Physiology College of Korean MedicineGachon UniversitySeoul 131-120Republic of Korea Department of Physiology School of MedicineKyung Hee UniversitySeoul 130-701Republic of Korea Department of Preventive Medicine College of Korean MedicineKyung Hee UniversitySeoul 130-701Republic of Korea

Comprehension of the medical diagnoses of doctors and treatment of diseases is important to understand the underlying principle in selecting appropriate *** pattern recognition process that pertains to symptoms and diseases and informs acupuncture treatment in a clinical setting was explored. A total of 232 clinical records were collected using a Charting Language program. The relationship between symptom information and selected acupoints was trained using an artificial neural network (ANN). A total of 11 hidden nodes with the highest average precision score were selected through a tenfold cross-validation. Our ANN model could predict the selected acupoints based on symptom and disease information with an average precision score of 0.865 (precision, 0.911;recall, 0.811). This model is a useful tool for diagnostic classification or pattern recognition and for the prediction and modeling of acupuncture treatment based on clinical data obtained in a real-world setting. The relationship between symptoms and selected acupoints could be systematically characterized through knowledge discovery processes, such as pattern identification.

关键词： acupuncture indication neural network pattern identification prediction

Helicobacter pylori in gastric carcinogenesis

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World Journal of Gastrointestinal Oncology 2015年第12期7卷 455-465页

作者： Hyo Jun Ahn Dong soo lee Division of Gastroenterology Department of Internal Medicine College of Medicine Daejeon St. Mary’s Hospital the Catholic University of Korea

Gastric cancer still is a major concern as the third most common cancer worldwide, despite declining rates of incidence in many Western countries. Helicobacter pylori(H. pylori) is the major cause of gastric carcinogenesis, and its infection insults gastric mucosa leading to theoccurrence of atrophic gastritis which progress to intestinal metaplasia, dysplasia, early gastric cancer, and advanced gastric cancer consequently. This review focuses on multiple factors including microbial virulence factors, host genetic factors, and environmental factors, which can heighten the chance of occurrence of gastric adenocarcinoma due to H. pylori infection. Bacterial virulence factors are key components in controlling the immune response associated with the induction of carcinogenesis, and cag A and vac A are the most well-known pathogenic factors. Host genetic polymorphisms contribute to regulating the inflammatory response to H. pylori and will become increasingly important with advancing techniques. Environmental factors such as high salt and smoking may also play a role in gastric carcinogenesis. It is important to understand the virulence factors, host genetic factors, and environmental factors interacting in the multistep process of gastric carcinogenesis. To conclude, prevention via H. pylori eradication and controlling environmental factors such as diet, smoking, and alcohol is an important strategy to avoid H. pylori-associated gastric carcinogenesis.

关键词： Helicobacter pylori Gastric cancer