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Search Results: 1 - 10 of 50831 matches for " Hyung-Jin;Lee "
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Multi GPU Performance of Conjugate Gradient Algorithm with Staggered Fermions
Hyung-Jin Kim,Weonjong Lee
Physics , 2010,
Abstract: We report results of the performance test of GPUs obtained using the conjugate gradient (CG) algorithm for staggered fermions on the MILC fine lattice ($28^3 \times 96$). We use GPUs of nVIDIA GTX 295 model for the test. When we turn off the MPI communication and use only a single GPU, the performance is 35 giga flops in double precision, which corresponds to 47% of the peak. When we turn on the MPI communication and use multi-GPUs, the performance is reduced down to 12.3 giga flops. The data transfer through the infiniband network and PCI-E bus I/O is a main bottle neck. We suggest two potential solutions of how to optimize the data transfer.
Recent progress in staggered chiral perturbation theory
Bailey, Jon;Kim, Hyung-Jin;Lee, Weonjong;Yoon, Boram
High Energy Physics - Phenomenology , 2013,
Abstract: We present a review on recent progress in staggered chiral perturbation theory (SChPT). In the last decade, the scope of the application of SChPT has been extended beyond the level of calibration into the region of prediction with high precision. SChPT becomes an essential tool to do the data analysis reliably for physical observables calculated using improved staggered fermions. Here, we focus on the following examples: pion spectrum, pion decay constants, $\varepsilon_K$, and $\pi-\pi$ scattering amplitudes. In each subject, we review the recent progress and future prospects.
Multi GPU Performance of Conjugate Gradient Solver with Staggered Fermions in Mixed Precision
Yong-Chull Jang,Hyung-Jin Kim,Weonjong Lee
Physics , 2011,
Abstract: GPU has a significantly higher performance in single-precision computing than that of double precision. Hence, it is important to take a maximal advantage of the single precision in the CG inverter, using the mixed precision method. We have implemented mixed precision algorithm to our multi GPU conjugate gradient solver. The single precision calculation use half of the memory that is used by the double precision calculation, which allows twice faster data transfer in memory I/O. In addition, the speed of floating point calculations is 8 times faster in single precision than in double precision. The overall performance of our CUDA code for CG is 145 giga flops per GPU (GTX480), which does not include the infiniband network communication. If we include the infiniband communication, the overall performance is 36 giga flops per GPU (GTX480).
Non-Goldstone pion masses with NLO in Staggered Chiral Perturbation Theory
Jon A. Bailey,Hyung-Jin Kim,Weonjong Lee
Physics , 2011,
Abstract: We present results of the masses of taste non-Goldstone $(F \ne \xi_5)$ pions and kaons calculated up to the next-to-leading order in the SU(3) staggered chiral perturbation theory (SChPT). The results can be used to fit data and to understand taste symmetry breaking effect quantitatively. The final expressions for the non-Goldstone masses contain 20 low energy constants unique to the non-Goldstone sector. We have calculated the several cases such as the full QCD, partially quenched QCD, and quenched QCD in the $N_f=1+1+1$ flavor and $N_f=2+1$ flavor cases in the SU(3) and SU(2) SChPT. In this paper, we present only the SU(3) part.
Recent progress in staggered chiral perturbation theory
Jon Bailey,Hyung-Jin Kim,Weonjong Lee,Boram Yoon
Physics , 2013,
Abstract: We present a review on recent progress in staggered chiral perturbation theory (SChPT). In the last decade, the scope of the application of SChPT has been extended beyond the level of calibration into the region of prediction with high precision. SChPT becomes an essential tool to do the data analysis reliably for physical observables calculated using improved staggered fermions. Here, we focus on the following examples: pion spectrum, pion decay constants, $\varepsilon_K$, and $\pi-\pi$ scattering amplitudes. In each subject, we review the recent progress and future prospects.
Guest Editorial
Masato Oguchi,Hyung-Jin Choi,Tae-Jin Lee,Seong Keun Oh
Journal of Networks , 2011, DOI: 10.4304/jnw.6.3.341-342
Abstract: This special issue of the Journal of Networks consists of six selected papers from the 4th International Conference on Ubiquitous Information Management and Communication (ICUIMC 2010) held in January 14th - 15th. Among them, six qualified papers have been selected as the papers for the special issue of the Journal of Networks, which covers the recent trends in wireless communications and networking. This issue includes various research field in communications and networking technologies. As one of the recent hot topics in this field, "A Communication Protocol for Sensor Database Construction by Rounding Sink" by Tomoki Yoshihisa and Shojiro Nishio, presents a model and simulation-based analytical results in wireless sensor networks. The rounding sink approach has been presented and studied, in which rounding sinks repeatedly wander about in the area to collect data from each sensor. "An Efficient Mutual Authentication and Access Control Scheme for Wireless Sensor Networks in Healthcare" by Xuan Hung Le, Murad Khalid, Ravi Sankar, and Sungyoung Lee, also discusses an issue in wireless sensor networks. To achieve the protection of data confidentiality and patient privacy in healthcare applications using wireless sensors, a secure, lightweight public key-based security scheme is proposed and evaluated by simulation. "An Energy-efficient Multi-candidate Greedy Routing Scheme in Wireless Sensor Networks" by Dang Tu Nguyen, Wook Choi, Minh Thiep Ha, and Hyunseung Choo, introduces novel multi-candidate greedy routing scheme in wireless sensor networks. According to the simulation results, their method increases the routing performance significantly in terms of packet delivery latency and energy efficiency. A fundamental technology for wireless communications is included in this issue as well. "The Enhanced Decoding Method for QO-SFBC System in Frequency Selective Fading Channel Environment" by Young-il Min, Hwan-min Park, Jun-hee Jang, Keun-dea Kim, and Hyung-jin Choi, proposes a decoding method to improve the performance of quasi orthogonal-space frequency block coding in frequency selective fading channel environment. An analysis and evaluation results by simulation show that the method can provide better performance compared with the conventional methods. This issue also deals with the field of image processing, which can be applied in the various Internet environments. "Image Retrieval with Generative Model for Typicality" by Taro Tezuka and Akira Maeda, discusses the problem to find the most typical image that depicts the object specified by a query. Thei
Finite Volume Errors in $B_K$
Jangho Kim,Hyung-Jin Kim,Weonjong Lee,Chulwoo Jung,Stephen R. Sharpe
Physics , 2011,
Abstract: We discuss finite volume errors in our calculations of $B_K$ using improved staggered fermions on the MILC asqtad lattices. Using GPUs, we are now able to extrapolate using next-to-leading order (NLO) staggered SU(2) chiral perturbation theory including the finite volume corrections arising from pion loops. We find that the impact of FV fitting is very small, giving a 0.5% shift in the continuum limit.
Masses and decay constants of pions and kaons in mixed-action staggered chiral perturbation theory
Jon A. Bailey,Hyung-Jin Kim,Jongjeong Kim,Weonjong Lee,Boram Yoon
Physics , 2015,
Abstract: Lattice QCD calculations with different staggered valence and sea quarks can be used to improve determinations of quark masses, Gasser-Leutwyler couplings, and other parameters relevant to phenomenology. We calculate the masses and decay constants of flavored pions and kaons through next-to-leading order in staggered-valence, staggered-sea mixed-action chiral perturbation theory. We present the results in the valence-valence and valence-sea sectors, for all tastes. As in unmixed theories, the taste-pseudoscalar, valence-valence mesons are exact Goldstone bosons in the chiral limit, at non-zero lattice spacing. The results reduce correctly when the valence and sea quark actions are identical, connect smoothly to the continuum limit, and provide a way to control light quark and gluon discretization errors in lattice calculations performed with different staggered actions for the valence and sea quarks.
Kaon mixing matrix elements from beyond-the-Standard-Model operators in staggered chiral perturbation theory
Jon A. Bailey,Hyung-Jin Kim,Weonjong Lee,Stephen R. Sharpe
Physics , 2012, DOI: 10.1103/PhysRevD.85.074507
Abstract: Models of new physics induce K-Kbar mixing operators having Dirac structures other than the "left-left" form of the Standard Model. We calculate the functional form of the corresponding B-parameters at next-to-leading order in both SU(3) and SU(2) staggered chiral perturbation theory (SChPT). Numerical results for these matrix elements are being generated using improved staggered fermions; our results can be used to extrapolate these matrix elements to the physical light and strange quark masses. The SU(3) SChPT results turn out to be much simpler than that for the Standard Model B_K operator, due to the absence of chiral suppression in the new operators. The SU(2) SChPT result is of similar simplicity to that for B_K. In fact, in the latter case, the chiral logarithms for two of the new B-parameters are identical to those for B_K, while those for the other two new B-parameters are of opposite sign. In addition to providing results for the 2+1 flavor theory in SU(3) SChPT and the 1+1+1 flavor theory in SU(2) SChPT, we present the corresponding continuum partially quenched results, as these are not available in the literature.
Flavored pions and kaons at next-to-leading order in mixed-action staggered chiral perturbation theory
Jon A. Bailey,Jongjeong Kim,Weonjong Lee,Hyung-Jin Kim,Boram Yoon
Physics , 2013,
Abstract: Different versions of improved staggered fermions can be used as valence quarks to reduce discretization effects in lattice QCD calculations while increasing statistics on existing staggered gauge ensembles. Such mixed-action simulations can be used to improve determinations of light quark masses, Gasser-Leutwyler couplings, decay constants, and other parameters relevant to particle phenomenology. We recall the generalization of ordinary, unmixed staggered chiral perturbation theory required to describe data from lattice calculations with a mixed action such as with HYP staggered valence quarks and asqtad sea quarks. We calculate the next-to-leading order loop diagrams contributing to the masses and decay constants of the flavored pseudo-Goldstone bosons of all tastes and here report results for the decay constants and valence-valence masses.
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