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Search Results: 1 - 10 of 1175 matches for " Woon-Hak Baek "
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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.
Flash-based Extended Cache for Higher Throughput and Faster Recovery
Woon-Hak Kang,Sang-Won Lee,Bongki Moon
Computer Science , 2012,
Abstract: Considering the current price gap between disk and flash memory drives, for applications dealing with large scale data, it will be economically more sensible to use flash memory drives to supplement disk drives rather than to replace them. This paper presents FaCE, which is a new low-overhead caching strategy that uses flash memory as an extension to the DRAM buffer. FaCE aims at improving the transaction throughput as well as shortening the recovery time from a system failure. To achieve the goals, we propose two novel algorithms for flash cache management, namely, Multi-Version FIFO replacement and Group Second Chance. One striking result from FaCE is that using a small flash memory drive as a caching device could deliver even higher throughput than using a large flash memory drive to store the entire database tables. This was possible due to flash write optimization as well as disk access reduction obtained by the FaCE caching methods. In addition, FaCE takes advantage of the non-volatility of flash memory to fully support database recovery by extending the scope of a persistent database to include the data pages stored in the flash cache. We have implemented FaCE in the PostgreSQL open source database server and demonstrated its effectiveness for TPC-C benchmarks.
Creation of Resveratrol-Enriched Rice for the Treatment of Metabolic Syndrome and Related Diseases
So-Hyeon Baek, Woon-Chul Shin, Hak-Seung Ryu, Dae-Woo Lee, Eunjung Moon, Chun-Sun Seo, Eunson Hwang, Hyun-Seo Lee, Mi-Hyun Ahn, Youngju Jeon, Hyeon-Jung Kang, Sang-Won Lee, Sun Yeou Kim, Roshan D’Souza, Hyeon-Jin Kim, Seong-Tshool Hong, Jong-Seong Jeon
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057930
Abstract: Resveratrol has been clinically shown to possess a number of human health benefits. As a result, many attempts have been made to engineer resveratrol production in major cereal grains but have been largely unsuccessful. In this study, we report the creation of a transgenic rice plant that accumulates 1.9 μg resveratrol/g in its grain, surpassing the previously reported anti-metabolic syndrome activity of resveratrol through a synergistic interaction between the transgenic resveratrol and the endogenous properties of the rice. Consumption of our transgenic resveratrol-enriched rice significantly improved all aspects of metabolic syndrome and related diseases in animals fed a high-fat diet. Compared with the control animals, the resveratrol-enriched rice reduced body weight, blood glucose, triglycerides, total cholesterol, and LDL-cholesterol by 24.7%, 22%, 37.4%, 27%, and 59.6%, respectively. The resveratrol-enriched rice from our study may thus provide a safe and convenient means of preventing metabolic syndrome and related diseases without major lifestyle changes or the need for daily medications. These results also suggest that future transgenic plants could be improved if the synergistic interactions of the transgene with endogenous traits of the plant are considered in the experimental design.
Effects of metallic absorption and the corrugated layer on the optical extraction efficiency of organic light-emitting diodes
Baek-Woon Lee,Young-Gu Ju
Physics , 2009,
Abstract: The absorption of a metallic cathode in OLEDs is analyzed by using FDTD calculation. As the light propagates parallel to the layer, the intensity of Ez polarization decreases rapidly. The intensity at 2.0 um from the dipole is less than a quarter of that at 0.5 um. The strong absorption by a cathode can be a critical factor when considering the increase of optical extraction by means of bending the optical layers. The calculation indicates that the corrugation of layers helps the guided light escape the guiding layer, but also increases the absorption into a metallic cathode. The final optical output power of the corrugated OLED can be smaller than that of the flat OLED. On the contrary, the corrugated structure with a non-absorptive cathode increases the optical extraction by nearly two times.
Coarsening Dynamics in a Two-dimensional XY model with Hamiltonian Dynamics
Kyo-Joon Koo,Woon-Bo Baek,Bongsoo Kim,Sung Jong Lee
Physics , 2006,
Abstract: We investigate the coarsening dynamics in the two-dimensional Hamiltonian XY model on a square lattice, beginning with a random state with a specified potential energy and zero kinetic energy. Coarsening of the system proceeds via an increase in the kinetic energy and a decrease in the potential energy, with the total energy being conserved. We find that the coarsening dynamics exhibits a consistently superdiffusive growth of a characteristic length scale with 1/z > 1/2 (ranging from 0.54 to 0.57). Also, the number of point defects (vortices and antivortices) decreases with exponents ranging between 1.0 and 1.1. On the other hand, the excess potential energy decays with a typical exponent of 0.88, which shows deviations from the energy-scaling relation. The spin autocorrelation function exhibits a peculiar time dependence with non-power law behavior that can be fitted well by an exponential of logarithmic power in time. We argue that the conservation of the total Josephson (angular) momentum plays a crucial role for these novel features of coarsening in the Hamiltonian XY model.
Coarsening of two dimensional XY model with Hamiltonian dynamics: Logarithmically divergent vortex mobility
Keekwon Nam,Woon-Bo Baek,Bongsoo Kim,Sung Jong Lee
Physics , 2012, DOI: 10.1088/1742-5468/2012/11/P11023
Abstract: We investigate the coarsening kinetics of an XY model defined on a square lattice when the underlying dynamics is governed by energy-conserving Hamiltonian equation of motion. We find that the apparent super-diffusive growth of the length scale can be interpreted as the vortex mobility diverging logarithmically in the size of the vortex-antivortex pair, where the time dependence of the characteristic length scale can be fitted as $L(t) \sim ((t+t_{0}) \ln(t+t_{0}))^{1/2}$ with a finite offset time $t_0$. This interpretation is based on a simple phenomenological model of vortex-antivortex annihilation to explain the growth of the coarsening length scale $L(t)$. The nonequilibrium spin autocorrelation function $A(t)$ and the growing length scale $L(t)$ are related by $A(t) \simeq L^{-\lambda}(t)$ with a distinctive exponent of $\lambda \simeq 2.21$ (for $E=0.4$) possibly reflecting the strong effect of propagating spin wave modes. We also investigate the nonequilibrium relaxation (NER) of the system under sudden heating of the system from a perfectly ordered state to the regime of quasi-long-range order, which provides a very accurate estimation of the equilibrium correlation exponent $\eta (E) $ for a given energy $E$. We find that both the equal-time spatial correlation $C_{nr}(r,t)$ and the NER autocorrelation $A_{nr}(t)$ exhibit scaling features consistent with the dynamic exponent of $z_{nr} = 1$.
Numerical analysis of high-index nanocomposite encapsulant for light-emitting diodes
Young-Gu Ju,Guilhem Almuneau,Tae-Hoon Kim,Baek-Woon Lee
Physics , 2005, DOI: 10.1143/JJAP.45.2546
Abstract: We used two-dimensional Finte-Difference-Time-Domain (FDTD) software to study the transition behavior of nano-particles from scatterers to an optically uniform medium. We measured the transmission efficiency of the dipole source, which is located in the high refractive index medium(index=2.00) and encapsulated by low index resin(index=1.41). In an effort to compose index-matched resin and to reduce internal reflection, high-index nano-particles are added to low-index resin in simulations of various sizes and densities. As the size of the nano-particles and the average spacing between particles are reduced to 0.02 lambda and 0.07 lambda respectively, the transmission efficiency improves two-fold compared to that without nanoparticles. The numerical results can be used to understand the optical behavior of nano-particles and to improve the extraction efficiency of high brightness light-emitting-diodes(LEDs), through the use of nano-composite encapsulant.
A Nanopore Structured High Performance Toluene Gas Sensor Made by Nanoimprinting Method
Kwang-Su Kim,Woon-Hyuk Baek,Jung-Min Kim,Tae-Sik Yoon,Hyun Ho Lee,Chi Jung Kang,Yong-Sang Kim
Sensors , 2010, DOI: 10.3390/s100100765
Abstract: Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO2) pores with a diameter of 70~80 nm using this method. This thin film had a Pd/TiO2 nanoporous/SiO2/Si MIS layered structure with Pd-TiO2 as the catalytic sensing layer. The nanoimprinting method was useful in expanding the TiO2 surface area by about 30%, as confirmed using AFM and SEM imaging. The measured toluene concentrations ranged from 50 ppm to 200 ppm. The toluene was easily detected by changing the Pd/TiO2 interface work function, resulting in a change in the I-V characteristics.
Combination therapy of renal cell carcinoma or breast cancer patients with dendritic cell vaccine and IL-2: results from a phase I/II trial
Soyoung Baek, Choung-Soo Kim, Sung-Bae Kim, Yong-man Kim, Seog-Woon Kwon, YongMan Kim, HyunSoo Kim, Hyunah Lee
Journal of Translational Medicine , 2011, DOI: 10.1186/1479-5876-9-178
Abstract: Cancer patients were treated twice with autologous CD34+ hematopoietic stem cell-derived, GM-CSF/IFN-γ-differentiated DCs pulsed with autologous tumor lysate and KLH, by 4-week interval. Following each subcutaneous injection of therapeutic DCs, low-dose (200 MIU) IL-2 was introduced for 14 consecutive days as an immune adjuvant. To determine the DC vaccine-induced immunological alterations, the KLH-specific lymphocyte proliferation, number of IFN-γ secreting T cells (ELISPOT assay), NK activity and the cytokine modulation were measured.Cultured-DCs expressing HLA-DR, CD11c, CD83, and B7.1/B7.2 produced IL-12p70. After vaccination, the patients tolerated it. Clinical response was observed in one RCC patient as stable disease. However DC-vaccine related antigen-specific immune responses including peripheral blood lymphocyte proliferation and the number of IFN-r secreting cells were induced in six patients without clear correlation with clinical responses. Also NK activity was induced significantly in six patients after vaccination. DC vaccine-related decrease of TGF-β level or increase of IL-12p70 level and decline of CD4+CD25+ T cells were observed in three patients. However only in the RCC patient whose disease stabilized, combination of stimulatory as well as inhibitory immune alterations including induction of IFN-γ secreting T cell with reduction of CD4+ CD25+ T cell were correlated with clinical responses.Data indicated that DC vaccine combined with IL-2 is well tolerated without major side effects. DC vaccine induced the specific immunity against introduced antigen. Combinatorial alterations of immunological parameters indicating antigen-specific immune induction along with reduction of inhibitory immunity were correlated with clinical responses in DC vaccine treated patients.As a professional antigen-presenting cell (APCs), DC induces antigen specific cytotoxic T lymphocyte (CTL) response thus DC vaccine has been anticipated as a cancer treatment regimen [1,2]
A WKYMVm-Containing Combination Elicits Potent Anti-Tumor Activity in Heterotopic Cancer Animal Model
Sang Doo Kim, Ha Young Lee, Jae Woong Shim, Hak Jung Kim, Suk-Hwan Baek, Brian A. Zabel, Yoe-Sik Bae
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030522
Abstract: The development of efficient anti-cancer therapy has been a topic of intense interest for several decades. Combined administration of certain molecules and immune cells has been shown to be an effective form of anti-cancer therapy. Here, we examined the effects of administering an immune stimulating peptide (WKYMVm), 5-fluoro-uracil (5-FU), and mature dendritic cells (mDCs) against heterotopic cancer animal model. Administration of the triple combination strongly reduced tumor volume in CT-26-inoculated heterotopic cancer animal model. The induced anti-tumor activity was well correlated with FAS expression, caspase-3 activation, and cancer cell apoptosis. The triple combination treatment caused recruitment of CD8 T lymphocytes and natural killer (NK) cells into the tumor. The production of two cytokines, IFN-γ and IL-12, were strongly stimulated by administration of the triple combination. Depletion of CD8 T lymphocytes or NK cells by administration of anti-CD8 or anti-asialoGM1 antibody inhibited the anti-tumor activity and cytokine production of the triple combination. The triple combination strongly inhibited metastasis of colon cancer cells in a heterotopic cancer animal model as well as in a metastatic cancer animal model, and enhanced the survival rate of the mice model. Adoptive transfer of CD8 T lymphocytes and NK cells further increased the survival rate. Taken together, we suggest that the use of triple combination therapy of WKYMVm, 5-FU, and mDCs may have implications in solid tumor and metastasis treatment.
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