• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.74-75
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• 2005

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_2O_3$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193 nm) excimer laser. The epilayers of ZnO were achieved on sapphire ($Al_2O_3$) substrate at a temperature of $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence. The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}10^{16}cm^{-3}$ and $299cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T) = 3.3973 eV - ($2.69{\times}10^{-4}$ eV/K)$T_2$/(T + 463 K). The crystal field and the spin-orbit splitting energies for the valence band of the ZnO have been estimated to be 0.0041 eV and 0.0399 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the $\triangle$so definitely exists in the $\ulcorner_6$ states of the valence band of the ZnO. The three photocurrent peaks observed at 10K are ascribed to the $A_1-$, $B_1-$, and $C_1$-exciton peaks for n = 1.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.419-427
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• 2007

Single crystal $ZnIn_{2}S_{4}$ layers were grown on a thoroughly etched semi-insulating GaAs(100) substrate at $450^{\circ}C$ with the hot wall epitaxy (HWE) system by evaporating the polycrystal source of $ZnIn_{2}S_{4}$ at $610^{\circ}C$ prepared from horizontal electric furnace. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $ZnIn_{2}S_{4}$ thin films measured with Hall effect by van der Pauw method are $8.51{\times}10^{17}\;electron/cm^{-3}$, $291{\;}cm^{2}/v-s$ at 293 K, respectively. The photocurrent and the absorption spectra of $ZnIn_{2}S_{4}$/SI(Semi-Insulated) GaAs(100) are measured ranging from 293 K to 10 K. The temperature dependence of the energy band gap of the $ZnIn_{2}S_{4}$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=2.9514 eV. ($7.24{\times}10^{-4}\;eV/K$)$T^{2}$/(T+489 K). Using the photocurrent spectra and the Hopfield quasicubic model, the crystal field energy(${\Delta}cr$) and the spin-orbit splitting energy(${\Delta}so$) for the valence band of the $ZnIn_{2}S_{4}$ have been estimated to be 167.8 meV and 14.8 meV at 10 K, respectively. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1}$-, $B_{1}$-, and $C_{41}$-exciton peaks.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.92-96
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• 2002

A silver indium sulfide $(AgInS_{2})$ epilayer was grown by the hot wall epitaxy method, which has not been reported in the literature. The grown $AgInS_{2}$ epilayer has found to be a chalcopyrite structure and evaluated to be high quality crystal. From the photocurrent measurement in the temperature range from 30 K to 300 K, the two peaks of A and B were only observed, whereas the three peaks of A, B, and C were seen in the PC spectrum of 10 K. These peaks are ascribed to the band-ta-band transition. The valence band splitting of $AgInS_{2}$ was investigated by means of the photocurrent measurement. The crystal field splitting, $\Delta_{cr}$, and the spin orbit splitting, $\Delta_{so.}$ have been obtained to be 0.150 eV and 0.009 eV at 10 K, respectively. And, the energy band gap at room temperature has been determined to be 1.868 eV. Also, the temperature dependence of the energy band gap, $E_{g}(T)$, was determined.

• Korean Journal of Materials Research
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• v.12 no.7
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• pp.587-590
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• 2002

A silver indium sulfide ($AgInS_2$) epilayer was grown by the hot wall epitaxy method, which has not been reported in the literature. The grown $AgInS_2$ epilayer has found to be a chalcopyrite structure and evaluated to be high quality crystal. From the photocurrent measurement in the temperature range from 30 K to 300 K, the two peaks of A and B were only observed, whereas the three peaks of A, B, and C were seen in the PC spectrum of 10 K. These peaks are ascribed to the band-to-band transition. The valence band splitting of $AgInS_2$ was investigated by means of the photocurrent measurement. The crystal field splitting, $\Delta_{cr}$ , and the spin orbit splitting, $\Delta_{so}$ , have been obtained to be 0.150 eV and 0.009 eV at 10 K, respectively. And, the energy band gap at room temperature has been determined to be 1.868 eV. Also, the temperature dependence of the energy band gap, $E_{g}$(T), was determined.d.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.725-733
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• 2022

This study applied a hydraulic rock splitting system equipped with a hybrid packer to the bench-cut method. The hybrid packer system is an improvement of the packer developed in previous studies; it is designed efficiently to reduce vibration and noise during rock excavation by combining the two functions of inducing hydraulic fractures using injection pressure and then expanding and extending them using a rubber packer. Field experiments assessed the efficiency of rock excavation with respect to the injection conditions; the adjusted experimental conditions included the distance from the free surface and the test holes drilled at the top of the slope and the injection settings. Using a separation of 5 m left some unexcavated parts, but using a separation of 1 m left no unexcavated parts. The hydraulic fractures generated by the injection pressure developed generally parallel to the free surface and expanded and extended as the rubber packer expanded, thus facilitating bench-cut excavation. For hydraulic rock splitting to be broadly applicable to bench-cut rock excavation, it is important to accumulate results from many field experiments conducted under varying experimental conditions for various types of rockmass.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.639-655
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• 2023

Recently, there has been a growing demand for underground space, leading to the utilization of earth retaining walls for deep excavations. Earth retaining walls are structures that are susceptible to displacement, and their measurement and management are carried out in accordance with the standards established by the Ministry of Land, Infrastructure, and Transport. However, managing displacement through measurement can be considered similar to post-processing. Therefore, in this study, we not only predicted the horizontal displacement of a retaining wall with ground anchors installed using machine learning, but also analyzed the impact of the prediction model based on data scaling and data splitting methods while learning measurement data using machine learning. Custom splitting was the most suitable method for learning and outputting measurement data. Data scaling demonstrated excellent performance, with an error within 1 and an R-squared value of 0.77 when the anchor tensile force and water pressure were standardized. Additionally, it predicted a negative displacement compared to a model that without scaling.

• Korean Journal of Computational Design and Engineering
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• v.4 no.2
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• pp.79-86
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• 1999

A general approach to automatic generation of triangular meshes on three-dimensional surfaces is presented in this paper. The approach, developed with emphasis on program generality and interface with CAD/CAM systems, is based on the double mapping method and the looping method. The double mapping method is introduced and anew splitting scheme is proposed for the looping method employed for triangular mesh generation on the parametric domain. Several application examples are given.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.181-182
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• 2003

A preconditioned numerical method for gas-liquid to-phase flow is applied to solve cavitating flow. The present method employs a density based finite-difference method of dual time-stepping integration procedure and Roe's flux difference splitting approximation with MUSCL-TVD scheme. A homogeneous equilibrium cavitation model is used. The method permits simple treatment of the whole gas-liquid two-phase flow field including wave propagation, large density changes and incompressible flow characteristics at low Mach number. By this method, two-dimensional internal flows through a venturi tuve and decelerating cascades are computed and discussed.

• Journal of Korea Multimedia Society
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• v.11 no.8
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• pp.1179-1193
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• 2008

Recently, mobile devices enabled with Web services are being considered as equal participants of the Web services environment. The frequent mobility of devices and the intermittent disconnection of wireless network require migrating or replicating Web services onto adjacent devices appropriately. This paper proposes an efficient method for migrating and replicating Web services among mobile devices through code splitting. Specifically, the proposed method split the source code of a Web service into sub-codes based on users' preference to its constituent operations. The sub-code with higher preference is migrated earlier than others. The proposed method also replicates a Web service to other devices to enhance its performance by considering context information such as network traffic or the parameter size of its operations.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1846-1857
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• 2021

Ultrasonic nondestructive testing is important for monitoring the structural integrity of dissimilar metal welds (DMWs) in pressure vessels and piping in nuclear power plants. However, there is a low probability of crack detection via inspection of DMWs using ultrasonic waves because the grain structures (grain orientations) of the weld area cause distortion and splitting of ultrasonic beams propagating in anisotropic media. To overcome this issue, the grain orientation should be known, and a precise ultrasonic wave simulation technique in anisotropic media is required to model the distortion and splitting of the waves accurately. In this study, a method for nondestructive prediction of the DMW grain orientations is presented for accurate simulation of ultrasonic wave propagation behavior in the weld area. The ultrasonic wave propagation behavior in anisotropic media is simulated via finite-element analysis when ultrasonic waves propagate in a transversely isotropic material. In addition, a methodology to predict the DMW grain orientation is proposed that employs a simulation technique for ultrasonic wave propagation behavior calculation and an optimization technique. The simulated ultrasonic wave behaviors with the grain orientations predicted via the proposed method demonstrate its usefulness. Moreover, the method can be used to determine the focal law in DMWs.