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Search Results: 1 - 10 of 65970 matches for " Jun-Ho Lee "
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On the Dynamical Analysis in Aftershock Networks  [PDF]
Woon-Hak Baek, Kyungsik Kim, Ki-Ho Chang, Seung-Kyu Seo, Jun-Ho Lee, Dong-In Lee
Open Journal of Earthquake Research (OJER) , 2018, DOI: 10.4236/ojer.2018.71002
Abstract:
We investigate the dynamical behavior of aftershocks in earthquake networks, and the earthquake network calculated from a time series is constructed by contemplating cell resolution and temporal causality. We attempt to connect an earthquake network using relationship between one main earthquake and its aftershocks from seismic data of California. We mainly examine some topological properties of the earthquake such as the degree distribution, the characteristic path length, the clustering coefficient, and the global efficiency. Our result cannot presently determine the universal scaling exponents in statistical quantities, but the topological properties may be inferred to advance and improve by implementing the method and its technique of networks. Particularly, it may be dealt with a network issue of convenience and of importance in the case how large networks construct in time to proceed on earthquake systems.
Ferrimagnetic Slater Insulator Phase of the Sn/Ge(111) Surface
Jun-Ho Lee,Hyun-Jung Kim,Jun-Hyung Cho
Physics , 2013, DOI: 10.1103/PhysRevLett.111.106403
Abstract: We have performed the semilocal and hybrid density-functional theory (DFT) studies of the Sn/Ge(111) surface to identify the origin of the observed insulating ${\sqrt{3}}{\times}{\sqrt{3}}$ phase below ${\sim}$30 K. Contrasting with the semilocal DFT calculation predicting a metallic 3${\times}$3 ground state, the hybrid DFT calculation including van der Waals interactions shows that the insulating ferrimagnetic structure with ${\sqrt{3}}{\times}{\sqrt{3}}$ structural symmetry is energetically favored over the metallic 3${\times}$3 structure. It is revealed that the correction of self-interaction error with a hybrid exchange-correlation functional gives rise to a band-gap opening induced by a ferrimagnetic order. The results manifest that the observed insulating phase is attributed to the Slater mechanism via itinerant magnetic order rather than the hitherto accepted Mott-Hubbard mechanism via electron correlations.
Antiferromagnetic Slater Insulator Phase of Na2IrO3
Hyun-Jung Kim,Jun-Ho Lee,Jun-Hyung Cho
Physics , 2013, DOI: 10.1038/srep05253
Abstract: Using a hybrid density-functional theory (DFT) calculation including spin-orbit coupling (SOC), we predict that the zigzag antiferromagnetic (AFM) ground state of the honeycomb layered compound Na2IrO3 opens the observed insulating gap through a long-range magnetic order. We show that the effect of SOC and the correction of self-interaction error inherent in previous local or semilocal DFT calculations play crucial roles in predicting the band gap formation in Na2IrO3. It is revealed that the itinerant AFM order with a strong suppression of the Ir magnetic moment is attributed to a considerable hybridization of the Ir 5d orbitals with the O 2p orbitals. Thus, our results suggest that the insulating phase of Na2IrO3 can be represented as a Slater insulator driven by itinerant magnetism.
Antiferromagnetic ordering of dangling-bond electrons at the stepped Si(001) surface
Jun-Ho Lee,Sun-Woo Kim,Jun-Hyung Cho
Physics , 2013, DOI: 10.1063/1.4794162
Abstract: Using first-principles density-functional calculations, we explore the possibility of magnetic order at the rebonded $D_B$ step of the Si(001) surface. The rebonded $D_B$ step containing threefold coordinated Si atoms can be treated as a one-dimensional dangling-bond (DB) wire along the step edge. We find that Si atoms composing the step edge are displaced up and down alternatively due to Jahn-Teller-like distortion, but, if Si dimers on the terrace are passivated by H atoms, the antiferromagnetic (AFM) order can be stabilized at the step edge with a suppression of Jahn-Teller-like distortion. We also find that the energy preference of AFM order over Jahn-Teller-like distortion is enhanced in an oscillatory way as the length of DB wires decreases, showing the so-called quantum size effects.
LC/MS Analysis of Tetrodotoxin and Its Deoxy Analogs in the Marine Puffer Fish Fugu niphobles from the Southern Coast of Korea, and in the Brackishwater Puffer Fishes Tetraodon nigroviridis and Tetraodon biocellatus from Southeast Asia
Jun-Ho Jang,Jong-Soo Lee,Mari Yotsu-Yamashita
Marine Drugs , 2010, DOI: 10.3390/md8041049
Abstract: Tetrodotoxin (TTX) and its deoxy analogs, 5-deoxyTTX, 11-deoxyTTX, 6,11-dideoxyTTX, and 5,6,11-trideoxyTTX, were quantified in the tissues of three female and three male specimens of the marine puffer fish, Fugu niphobles, from the southern coast of Korea, and in the whole body of the brackishwater puffer fishes, Tetraodon nigroviridis (12 specimens) and Tetrodon biocellatus (three specimens) from Southeast Asia using LC/MS in single ion mode (SIM). Identification of these four deoxy analogs in the ovarian tissue of F. niphobles were further confirmed by LC/MS/MS. TTX and 5,6,11-trideoxyTTX were detected in all three puffer fish species as the major TTX analogs, similar to Japanese Fugu pardalis. While 6,11-dideoxyTTX was also found to be a major analog in almost all tissues of Korean F. niphobles, this analog was minor in the two Tetraodon species and Japanese F. pardalis. Among the tissues of F. niphobles, the concentrations of TTXs were highest in the ovaries (female) and skin (female and male).
Recent Advances in the Design of Electro-Optic Sensors for Minimally Destructive Microwave Field Probing
Dong-Joon Lee,No-Weon Kang,Jun-Ho Choi,Junyeon Kim,John F. Whitaker
Sensors , 2011, DOI: 10.3390/s110100806
Abstract: In this paper we review recent design methodologies for fully dielectric electro-optic sensors that have applications in non-destructive evaluation (NDE) of devices and materials that radiate, guide, or otherwise may be impacted by microwave fields. In many practical NDE situations, fiber-coupled-sensor configurations are preferred due to their advantages over free-space bulk sensors in terms of optical alignment, spatial resolution, and especially, a low degree of field invasiveness. We propose and review five distinct types of fiber-coupled electro-optic sensor probes. The design guidelines for each probe type and their performances in absolute electric-field measurements are compared and summarized.
The Clinical Course of Reverse-flow Anterolateral Thigh Flap: Need to Prepare for Venous Congestion and Salvage Operation
Il-Kug Kim,Tae-Gon Kim,Jun-Ho Lee,Yong-Ha Kim
Archives of Plastic Surgery , 2012, DOI: http://dx.doi.org/10.5999/aps.2012.39.3.262
Abstract:
Usefulness of Intravenous Anesthesia Using a Target-controlled Infusion System with Local Anesthesia in Submuscular Breast Augmentation Surgery
Kyu-Jin Chung,Kyu-Ho Cha,Jun-Ho Lee1,Yong-Ha Kim
Archives of Plastic Surgery , 2012, DOI: http://dx.doi.org/10.5999/aps.2012.39.5.540
Abstract: Background Patients have anxiety and fear of complications due to general anesthesia.Through new instruments and local anesthetic drugs, a variety of anesthetic methods havebeen introduced. These methods keep hospital costs down and save time for patients. Inparticular, the target-controlled infusion (TCI) system maintains a relatively accurate level ofplasma concentration, so the depth of anesthesia can be adjusted more easily. We conductedthis study to examine whether intravenous anesthesia using the TCI system with propofol andremifentanil would be an effective method of anesthesia in breast augmentation.Methods This study recruited 100 patients who underwent breast augmentation surgeryfrom February to August 2011. Intravenous anesthesia was performed with 10 mg/mLpropofol and 50 μg/mL remifentanil simultaneously administered using two separate modulesof a continuous computer-assisted TCI system. The average target concentration was set at2 μg/mL and 2 ng/mL for propofol and remifentanil, respectively, and titrated against clinicaleffect and vital signs. Oxygen saturation, electrocardiography, and respiratory status werecontinuously measured during surgery. Blood pressure was measured at 5-minute intervals.Information collected includes total duration of surgery, dose of drugs administered duringsurgery, memory about surgery, and side effects.Results Intraoperatively, there was transient hypotension in two cases and hypoxia in threecases. However, there were no serious complications due to anesthesia such as respiratorydifficulty, deep vein thrombosis, or malignant hypertension, for which an endotrachealintubation or reversal agent would have been needed. All the patients were discharged on theday of surgery and able to ambulate normally.Conclusions Our results indicate that anesthetic methods, where the TCI of propofol andremifentanil is used, might replace general anesthesia with endotracheal intubation in breastaugmentation surgery.
Physisorption of DNA nucleobases on h-BN and graphene: vdW-corrected DFT calculations
Jun-Ho Lee,Yun-Ki Choi,Hyun-Jung Kim,Ralph H. Scheicher,Jun-Hyung Cho
Physics , 2013, DOI: 10.1021/jp402403f
Abstract: We present a comparative study of DNA nucleobases [guanine (G), adenine (A), thymine (T), and cytosine (C)] adsorbed on hexagonal boron nitride (\textit{h}-BN) sheet and graphene, using local, semilocal, and van der Waals (vdW) energy-corrected density-functional theory (DFT) calculations. Intriguingly, despite the very different electronic properties of BN sheet and graphene, we find rather similar binding energies for the various nucleobase molecules when adsorbed on the two types of sheets. The calculated binding energies of the four nucleobases using the local, semilocal, and DFT+vdW schemes are in the range of 0.54 ${\sim}$ 0.75 eV, 0.06 ${\sim}$ 0.15 eV, and 0.93 ${\sim}$ 1.18 eV, respectively. In particular, the DFT+vdW scheme predicts not only a binding energy predominantly determined by vdW interactions between the base molecules and their substrates decreasing in the order of G$>$A$>$T$>$C, but also a very weak hybridization between the molecular levels of the nucleobases and the ${\pi}$-states of the BN sheet or graphene. This physisorption of G, A, T, and C on the BN sheet (graphene) induces a small interfacial dipole, giving rise to an energy shift in the work function by 0.11 (0.22), 0.09 (0.15), $-$0.05 (0.01), and 0.06 (0.13) eV, respectively.
Nature of the Insulating Ground State of the 5d PostPerovskite CaIrO3
Sun-Woo Kim,Chen Liu,Hyun-Jung Kim,Jun-Ho Lee,Yongxin Yao,Kai-Ming Ho,Jun-Hyung Cho
Physics , 2015, DOI: 10.1103/PhysRevLett.115.096401
Abstract: The insulating ground state of the 5d transition metal oxide CaIrO3 has been classified as a Mott-type insulator. Based on a systematic density functional theory (DFT) study with local, semilocal, and hybrid exchange-correlation functionals, we reveal that the Ir t2g states exhibit large splittings and one-dimensional electronic states along the c axis due to a tetragonal crystal field. Our hybrid DFT calculation adequately describes the antiferromagnetic (AFM) order along the c direction via a superexchange interaction between Ir4+ spins. Furthermore, the spin-orbit coupling (SOC) hybridizes the t2g states to open an insulating gap. These results indicate that CaIrO3 can be represented as a spin-orbit Slater insulator, driven by the interplay between a long-range AFM order and the SOC. Such a Slater mechanism for the gap formation is also demonstrated by the DFT + dynamical mean field theory calculation, where the metal-insulator transition and the paramagnetic to AFM phase transition are concomitant with each other.
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