Showing papers by "Hyun-Chul Kim published in 1993"
53 citations
TL;DR: The first measurement of the left-right cross section asymmetry for Z boson production at the SLAC Linear Collider was presented in this paper. But this measurement was performed at a center-of-mass energy of 91.55 GeV with the SLD detector at SLAC and utilized a longitudinally polarized electron beam.
Abstract: We present the first measurement of the left-right cross section asymmetry (${\mathit{A}}_{\mathit{L}\mathit{R}}$) for Z boson production by ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ collisions. The measurement was performed at a center-of-mass energy of 91.55 GeV with the SLD detector at the SLAC Linear Collider which utilized a longitudinally polarized electron beam. The average beam polarization was (22.4\ifmmode\pm\else\textpm\fi{}0.6)%. Using a sample of 10 224 Z decays, we measure ${\mathit{A}}_{\mathit{L}\mathit{R}}$ to be 0.100\ifmmode\pm\else\textpm\fi{}0.044(stat)\ifmmode\pm\else\textpm\fi{}0.004(syst), which determines the effective weak mixing angle to be ${\mathrm{sin}}^{2}$${\mathrm{\ensuremath{\theta}}}_{\mathit{W}}^{\mathit{e}\mathit{f}\mathit{f}}$=0.2378 \ifmmode\pm\else\textpm\fi{}0.0056(stat)\ifmmode\pm\else\textpm\fi{}0.0005(syst).
42 citations
TL;DR: In this paper, the authors determined the strong coupling [alpha][sub [ital s]] from measurements of jet rates in hadronic decays of [ital Z][sup 0] bosons collected by the SLD experiment at SLAC.
Abstract: We have determined the strong coupling [alpha][sub [ital s]] from measurements of jet rates in hadronic decays of [ital Z][sup 0] bosons collected by the SLD experiment at SLAC. Using six collinear and infrared safe jet algorithms we compared our data with the predictions of QCD calculated up to second order in perturbation theory, and also with resummed calculations. We find [alpha][sub [ital s]]([ital M][sub [ital Z]][sup 2])=0.118[plus minus]0.002(stat)[plus minus]0.003(syst)[plus minus]0.010(theory), where the dominant uncertainty is from uncalculated higher order contributions.
16 citations
TL;DR: In this article, a model for the N N → ππ helicity amplitudes was proposed and medium modifications of the σ channel in the NN potential were studied.
16 citations
TL;DR: In this article, the elastic angular distribution for Ni+Al has been measured at five energies from [ital E][sub c.m.]=48.8 to 69.5 MeV.
Abstract: The elastic angular distributions for [sup 58]Ni+[sup 27]Al have been measured at five energies from [ital E][sub c.m.]=48.8 to 69.5 MeV. The optical model analysis assumes both phenomenological and folding model potentials. Regions of sensitivity, where the potential is well determined, are found to be different for the real and the imaginary parts, and to vary with energy. The values of the real potential in the surface are weakly dependent on energy.
12 citations
TL;DR: In this article, the lifetimes of the and B− mesons have been measured with the ALEPH detector at LEP and the decays of the D− meson were partially reconstructed by identifying events containing a lepton with an associated meson.
11 citations
TL;DR: In this paper, the authors measured the Barkhausen noise envelope, the permeability and the hysteresis curve in highly grain-oriented HiB-8, and in annealed and cold-worked conventional 3% Si-Fe were measured simultaneously in order to investigate the microstructural dependence of domain wall dynamics.
9 citations
TL;DR: In this paper, a theoretical method for the analysis of a cylindrical edge-slot antenna with coaxial feed has been considered and theoretical values of the magnitude and phase of the reflection coefficient are compared with experimental values available in the open literature.
Abstract: A theoretical method has been considered for the analysis of a cylindrical edge-slot antenna with coaxial feed. Theoretical values of the magnitude and phase of the reflection coefficient are compared with experimental values available in the open literature. There is good agreement between them.
6 citations
TL;DR: The neural network model has been shown to be successful for the conservative and accurate prediction of the departure from nucleate boiling ratio (DNBR) and several variations of the neural network technique have been proposed and compared based on numerical experiments.
Abstract: Core monitoring models using neural networks have been developed for prediction of the core parameters for pressurized water reactors. The neural network model has been shown to be successful for the conservative and accurate prediction of the departure from nucleate boiling ratio (DNBR). Several variations of the neural network technique have been proposed and compared based on numerical experiments. The neural network can be augmented by use of a functional link to improve the performance of the network model. Use of twofold weight sets or weighted system error backpropagation was very effective for improving the network model accuracy further. An uncertainty factor that is a function of output DNBR is used to obtain a conservative DNBR for actual applications. The predictions by the network model need to be supported by extensive training of network and statistical treatment of the data. Studies for further improvements are suggested for future applications. >
4 citations
01 Jul 1993-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a one-dimensional model for a tapered FEL amplifier with an axial guide field operating in the Raman regime and an IR-FEL amplifier based on a test linac of the Pohang Accelerator Laboratory (PAL).
Abstract: Numerical calculations are performed based on the one-dimensional model for a tapered FEL amplifier with an axial guide field operating in the Raman regime and an IR-FEL amplifier based on a test linac of the Pohang Accelerator Laboratory (PAL). The longitudinal electric field can be formulated either by solving the coupled Maxwell and linear fluid equations or by solving the coupled kinetic and longitudinal wave equations. Both formulations are incorporated into the numerical code and the simulation results are compared. The criterion whether the space charge effect should be considered or not can be described in terms of the electron beam parameter ξ(ξ 2 = e 2 n b ϵ 0 mγ 0 c 2 k w 2 ) . We have also theoretically investigated the possibility of a tunable IR-FEL with a test linac of energy 20–60 MeV of PAL with effects of energy spread and space charge. The current density of the test linac, if properly enhanced, makes it feasible to amplify a 14 kW signal of 10.6 μm radiation to a 2 GW level.
4 citations
TL;DR: In this paper, a simple structure soft recovery driver which can alleviate the loss due to the reverse recovery current of a diode is proposed to reduce the EMI noise and peak reverse current spike in the continuous conduction mode operation.
Abstract: A new simple structure soft recovery driver which can alleviate the loss due to the reverse recovery current of a diode is proposed. By direct feedback of reverse recovery current, the EMI noise and peak reverse current spike can be considerably reduced in the continuous conduction mode operation.
01 Nov 1993
TL;DR: Bilateral small pleural effusion, ground glass opacity, subpleural patchy opacity, and micronodule are common and suggestive findings in the pleuropulmonaη involvement of SLE.
Abstract: To evaluate the high-resolution computed tomography (HRCT) findings of pleurop버monaη involvement in systemic lupus erγthematosus (SLE) , we an혀yzed HRCT findings of 12 patients of clinically confirmed SLE with respiratory symptoms. In four patients, HRCT findings before and after chemotherapy were compared. The common HRCT findings were ground-glass opacity (100%), bronchial wall thickening (66%) , patchy parenchymal opacity (58%) , sept떠 or intralobular line thickening (58%) , micronodule (58%) , central core prominence (41 %), small pleural effusion (91 %), and pericardial effusion (33%). Follow-up HRCT obtained after treatment showed significant 띠lprovement of pleural effusion (4/4) , pericardial effusion (3/3) , pericardial thickening (1 / 1), patchy opacity (2/ 2) , and ground glass opacity (2/4). But bronchial wall thickening (2/ 2) and micronodule (2/2) were not improved Although there are no pathognomonic HRCT findings in SLE, bilateral small pleural effusion, ground glass opacity, subpleural patchy opacity, and micronodule are common and suggestive findings in the pleuropulmonaη involvement of SLE.