http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Wedge energy bands of monolayer black phosphorus: a first-principles study
Park, Minwoo,Bae, Hyeonhu,Lee, Seunghan,Yang, Li,Lee, Hoonkyung IOP 2016 Journal of physics, an Institute of Physics journa Vol.28 No.30
<P>On the basis of first-principles calculations, we present intriguing electronic properties of halogen-striped functionalized monolayer black phosphorus. The halogen-striped monolayer black phosphorus is found to have a wedge energy band with the energy-momentum relation of <img ALIGN='MIDDLE' ALT='$E\propto {{p}_{y}}$ ' SRC='http://ej.iop.org/images/0953-8984/28/30/305301/cmaa2802ieqn001.gif'/> when the stripe–stripe distance is smaller than ~40 Å. Our tight-binding study shows that the wedge energy band occurs when 2-atom basis 1D lattices are periodically repeated aligned with each other in a 2D lattice. We also discuss the possible applications of this wedge energy band in electron supercollimation with high mobility or severely anisotropic electronic transport, which can be used for the development of optics-like nano-electronics.</P>
Kim, Byung Hyo,Bae, Hyeonhu,Park, Hyesung,Lee, Hoonkyung,Ercius, Peter,Park, Jungwon The Royal Society of Chemistry 2019 Physical chemistry chemical physics Vol.21 No.1
<P>Heterostructures constructed of graphene and colloidal nanocrystals provide a unique way to exploit the coupled physical properties of the two functional building blocks. Studying the interface structure between the two constituent materials is important to understand the formation mechanism and the resulting physical and chemical properties. Along with <I>ab initio</I> calculations, we elucidate that the bending rigidity and the strong van der Waals interaction of graphene to the metal surface guide the formation of a tight and conformal interface. Using theoretical foundations, we construct colloidal nanocrystal-graphene heterostructures with controlled interfacial structures and directly investigate the cross-sectional structures of them at high resolution by using aberration-corrected transmission electron microscopy. The experimental method and observations we present here will link the empirical methods for the formation of nanocrystal-graphene heterostructures to the mechanistic understanding of their properties.</P>
Fe–Porphyrin-like Nanostructures for Selective Ammonia Capture under Humid Conditions
Yang, Hyungmo,Bae, Hyeonhu,Park, Minwoo,Lee, Seunghan,Kim, Ki Chul,Lee, Hoonkyung American Chemical Society 2018 The Journal of Physical Chemistry Part C Vol.122 No.4
<P>We performed a computational search for selective NH<SUB>3</SUB> capture of metal–porphyrin-like graphenes using first-principles density functional theory calculations. Using equilibrium thermodynamics parametrized by the first-principles calculations, we found that NH<SUB>3</SUB> molecules can be selectively adsorbed on a metal atom at room temperature and low pressure while immersed in gas mixtures of NH<SUB>3</SUB> and H<SUB>2</SUB>O even. In addition, they could be released at a temperature increase of 150 K. We identified that the optimal candidate for selective NH<SUB>3</SUB> capture under humid conditions was Fe–porphyrin-like graphene, reaching a working capacity of ∼4 mmol/g at ambient conditions. We also found that Fe–porphyrin-like carbon nanotubes selectively captured NH<SUB>3</SUB> under humidity conditions. This study allows us to discover novel promising Fe-anchored carbon materials for the selective capture of ammonia from humid air at ambient temperature and pressure conditions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2018/jpccck.2018.122.issue-4/acs.jpcc.7b11991/production/images/medium/jp-2017-11991u_0005.gif'></P>
조혜정,진호,박현후,김관혁,장윤호,조우현,Jo, Hye Jeong,Jin, Ho,Park, Hyeonhu,Kim, Khan-Hyuk,Jang, Yunho,Jo, Woohyun 한국우주과학회 2022 우주기술과 응용 Vol.2 No.1
CubeSat is a satellite platform that is widely used not only for earth observation but also for space exploration. CubeSat is also used in magnetic field investigation missions to observe space physics phenomena with various shape configurations of magnetometer instrument unit. In case of magnetic field measurement, the magnetometer instrument should be far away from the satellite body to minimize the magnetic disturbances from satellites. But the accommodation setting of the magnetometer instrument is limited due to the volume constraint of small satellites like a CubeSat. In this paper, we investigated that the magnetic field interference generated by the cube satellite was analyzed how much it can affect the reliability of magnetic field measurement. For this analysis, we used a reaction wheel and Torque rods which have relatively high-power consumption as major noise sources. The magnetic dipole moment of these parts was derived by the data sheet of the manufacturer. We have been confirmed that the effect of the residual moment of the magnetic torque located in the middle of the 3U cube satellite can reach 36,000 nT from the outermost end of the body of the CubeSat in a space without an external magnetic field. In the case of accurate magnetic field measurements of less than 1 nT, we found that the magnetometer should be at least 0.6 m away from the CubeSat body. We expect that this analysis method will be an important role of a magnetic cleanliness analysis when designing a CubeSat to carry out a magnetic field measurement.
Woo, Yesol,Kim, Byeong-Soo,Lee, Jong-Won,Park, Jeasung,Cha, Minjun,Takeya, Satoshi,Im, Junhyuck,Lee, Yongjae,Jeon, Tae-In,Bae, Hyeonhu,Lee, Hoonkyung,Han, Sang Soo,Yeo, Byung Chul,Kim, Dongseon,Yoon, American Chemical Society 2018 Chemistry of materials Vol.30 No.9
<P>An effective combination of host and guest molecules in a framework type of architecture can enhance the structural stability and physical properties of clathrate compounds. We report here that an organic clathrate compound consisting of a fullerene (C<SUB>60</SUB>) guest and a hydroquinone (HQ) host framework shows enhanced hydrogen-storage capacity and good structural stability under pressures and temperatures up to 10 GPa and 438 K, respectively. This combined structure is formed in the extended β-type HQ clathrate and admits 16 hydrogen molecules per cage, leading to a volumetric hydrogen uptake of 49.5 g L<SUP>-1</SUP> at 77 K and 8 MPa, a value enhanced by 130% compared to that associated with the β-type HQ clathrate. A close examination according to density functional theory calculations and grand canonical Monte Carlo simulations confirms the synergistic combination effect of the guest-host molecules tailored for enhanced hydrogen storage. Moreover, the model simulations demonstrate that the lithium-doped HQ clathrates with C<SUB>60</SUB> guests reveal exceptionally high hydrogen-storage capacities. These results provide a new playground for additional fundamental studies of the structure-property relationships and migration characteristics of small molecules in nanostructured materials.</P> [FIG OMISSION]</BR>