• Journal of Digital Contents Society
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• v.18 no.6
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• pp.1101-1107
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• 2017

This study explored the effect of ASR-based pronunciation instruction, using a mobile platform, on EFL learners' pronunciation development. Particularly, this quasi-experimental study focused on whether using mobile ASR, which provides voice-to-text feedback, can enhance the perception and production of target English consonants minimal pairs (V-B, R-L, and G-Z) of Korean EFL learners. Three intact classes of 117 Korean university students were assigned to three groups: a) ASR Group: ASR-based pronunciation instruction providing textual feedback by the mobile ASR; b) Conventional Group: conventional face-to-face pronunciation instruction providing individual oral feedback by the instructor; and the c) Hybrid Group: ASR-based pronunciation instruction plus conventional pronunciation instruction. The ANCOVA results showed that the adjusted mean score for pronunciation production post-test on the Hybrid instruction group (M=82.71, SD =3.3) was significantly higher than the Conventional group (M=62.6, SD =4.05) (p<.05).

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.476-477
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• 2009

The smallest green laser containing a built-in temperature controlling unit has been demonstrated. The device volume was just 0.5 cubic centimeters, which is nearly the same size as existing red and blue diode lasers, has an electrical-to-optical conversion efficiency of 10% and 150 mW power output. Furthermore as an alternative approach for compact green laser development, a quasi-phase matching method with wide spectral bandwidth for the reduction of speckle noise will be presented.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.263-265
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• 2009

In this study, ultrafine grained (UFG) oxygen free high conductivity copper (OFHC Cu) having two different grain morphologies, one the severely elongated and the other the equiaxed, was prepared by equal channel angular pressing (ECAP) with routes A and $B_c$, respectively. The results of quasi-static tensile tests at $10^{-1}\;s^{-1}$ and $1\;s^{-1}$ and dynamic compression tests at $10^3\;s^{-1}$ order revealed that the equiaxed UFG Cu exhibited higher strength and less ductility compared to the elongated one. The difference of the plastic flow characteristics between the two were rationalized by considering their dislocation mean free length based on the orientation relationship between the possible slip planes and the loading direction.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.538-541
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• 2005

Tidal flats develop along the south coast ofthe Korean peninsula. These areas are famous for sea farming. Specially, strong and coherent radar backscattering signals are observed over oyster sea farms that consist of artificial structures. Tide height in oyster farm is possible to measure by using interferometric phase and intensity of SAR data. It is assumed that the radar signals from oyster farm could be considered as double-bouncing returns by vertical and horizontal bars. But, detailed backscattering mechanism and polarimetric characteristics in oyster farm had not been well studied. We could not demonstrate whether the assumption is correct or not and exactly understand what the properties of back scattering were in oyster farm without full polarimetric data. The results of AIRSAR L-band POLSAR data, experiments in laboratory and JERS-l images are discussed. We carried out an experiment simulating a target structure using vector network analyser (Y.N.A.) in an anechoic chamber at Niigata University. Radar returns from vertical poles are stronger than those from horizontal poles by 10.5 dB. Single bounce components were as strong as double bounce components and more sensitive to antenna look direction. Double bounce components show quasi-linear relation with height of vertical poles. As black absorber replaced AI-plate in bottom surface, double bounce in vertical pole decreased. It is observed that not all oyster farms are characterized by double bounced scattering in AIRSAR data. The image intensity of the double bounce dominant oyster farm was investigated with respect to that of oyster farm dominated by single bounce in JERS-l SAR data. The image intensity model results in a correlation coefficient (R2 ) of 0.78 in double bounce dominant area while that of 0.54 in single bouncing dominant area. This shows that double bounce dominant area should be selected for water height measurement using In8AR technique.

• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.1
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• pp.9-16
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• 1974

To contribute towards more accurate estimation of the virtual inertia coefficient for the horizontal vibration of ships, three dimensional correction factor $J_H$ for the added mass of finitely long elliptic prismatic bars in horizontal vibration in a free surface of an ideal fluid are calculated. In the problem formulation Dr. T. Kumai's quasi-finite length concept[1,11,12] is employed. Now that, in Dr. Kumai's work[1] for the horizontal vibration the mathematical model was a circular cylinder, the principal aim of the authors' work is to investigate the influence of the beam-draft ratio B/T on $J_H$. The numerical results of this work are shown in Fig.3 graphically, from which we may recognize that the influence of B/T on $J_H$ is remarkable as much as that of the length-draft ratio L/T(refer to Fig.1 also). In Fig.3 the curves for B/T=2.00 are of those based on Dr. Kumai's result[1]. On the other hand, the experimental data obtained by Burril et al.[9] for the horizontal vibration of finitely long prismatic bars of various cross-section shapes are compared with the theoretical added mass coefficients defined by combination of the authors' $J_H$ from Fig.3 and two dimensional coefficients $C_H$ obtained by Lewis form approximation for the corresponding sections. They are in reasonable correspondence with each other as shown in Fig.2. Finally, considering that the longitudinal profile of full-form ship's hull is well resembled to that of an elliptic cylinder and that the influences of other factors such as the sectional area coefficient and the shape of section contour itself can be well merged in the two dimensional added mass coefficient, the authors recommend that the data given in Fig.3 may be successfully adopted for the three dimensional correction factor the added mass in the horizontal vibration of hull-form ships.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.307-312
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• 2005

In this work, we study the performance of a serial concatenated scheme comprising a convolutional code (CC) and an orthogonal space-time block code (STBC) separated by an inter-leaver. Specifically, we derive performance bounds for this concatenated scheme, clearly quantify the impact of using a CC in conjunction with a STBC, and compare that to using a STBC code only. Furthermore, we examine the impact of performing antenna selection at the receiver on the diversity order and coding gain of the system. In performing antenna selection, we adopt a selection criterion that is based on maximizing the instantaneous signal-to­noise ratio (SNR) at the receiver. That is, we select a subset of the available receive antennas that maximizes the received SNR. Two channel models are considered in this study: Fast fading and quasi-static fading. For both cases, our analyses show that substantial coding gains can be achieved, which is confirmed through Monte-Carlo simulations. We demonstrate that the spatial diversity is maintained for all cases, whereas the coding gain deteriorates by no more than $10\;log_{10}$ (M / L) dB, all relative to the full complexity multiple-input multiple-output (MIMO) system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.55-61
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• 2000

Tungsten heavy metal is characterized bi a high density and novel combination of strength and ductility. Among them, 90W-7Ni-3Fe is used for applications, where the high specific weight of the material plays an important role. They are used as counterweights, rotating inertia members, as well as for defense purposes(kinetic energy penetrators, etc.). Because of these applications, it is essential to detemine the dynamic characteristics of tungsten alloy. In this paper, Explicit FEM(finite element method) is employed to investigate the dynamic characteristics of tungsten heavy metal under base of stress wave propagation theory for SHPB, and the model of specimen is divided into two parts to understand the phenomenon that stress wave penetrates through each tungsten base and matrix. This simulation results were compared to experimental one and through this program the dynamic stress-strain curve of tungsten heavy metal can be obtained using quasi static stress-strain curve of pure tungsten and matrix.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.857-864
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• 2012

A linear stability analysis of a diffusion flame with radiation heat loss is performed to identify linearly unstable conditions for the Damk$\ddot{o}$hler number and radiation intensity. We adopt a counterflow diffusion flame with unity Lewis number as a model. Near the kinetic limit extinction regime, the growth rates of disturbances always have real eigenvalues, and a neutral stability condition perfectly falls into the quasi-steady extinction. However, near the radiative limit extinction regime, the eigenvalues are complex, which implies pulsating instability. A stable limit cycle occurs when the temperatures of the pulsating flame exceed the maximum temperature of the steady-state flame with real positive eigenvalues. If the instantaneous temperature of the pulsating flame is below the maximum temperature, the flame cannot recover and goes to extinction. The neutral stability curve of the radiation-induced instability is plotted over a broad range of radiation intensities.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.28-28
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• 1995

The aim of the present study is to investigate the interannual variabilities of the East Asia monsoon rainfall associated with the global sea surface temperature anomaly(SSTA). For this study, the summer rainfall(from June to August) over the twenty-eight period of 1961-1988 were analyzed with being divided by nine-subregions over East Asia including Korea, China and Japan. From the analysis of the principal modes explaining the interannual variation, the interannual variabilities of summer rainfalls in South Japan and Korea are larger than those of the other subregions of the East Asia. There is a strong negative correlation between the summer rainfalls of south China and Korea. In this study, the relationship between the summer monsoon of each subregion and SSTs of the tropical NINO regions, of western Pacific warm pool, and of the subtropical ocean were investigated. The longitudinal sections of the lagged cross correlations of the summer rainfal1 anomaly in (a) Korea and (b) south China, and the monthly SSTA in the equatorial(averaged from 65 to 6N) Pacific were analyzed. The negative maximum correlation pattems of Korea''s stammer rainfal1 and SSTs over the eastern Pacific is transfered to positive maximum conrlation over central Pacific region with a biennial periodicity. In South China, the significant positive correlations are found at -12 month lag over the eastern Pacific and maximum negative correlation at 16 month lag over the central Pacific with the quasi-biennial oscillation. But the correlation coefficient reverses completely to that in Korea. In order to investigate the most prevailing interannual variability of rainfall related to the favored SSTA region, the lagged cross correlations between East Asia rainfall and SSTs over the moO regions(NINO 1+2(0-105, 90W-80W), NINO 3(5N-5S, 150W-90W), NINO 4(5N-5S, 160E-l50W) and the western Pacific worm pool (5N-5S, 120E-l60E) were analyzed. Among the lagged cross-correlation cycles in NINO regions, the maximum correlations for the negative lagged months prevail in NINO 1+2 and NINO 3, and the cross correlations for the positive lagged months NINO 4. It is noteworthy that correlation between the western Pacific warm pool SSTA and the monsoon rainfall in Korea and South China have the maximum value at negative 4 month lag. The evolution of the correlation between the East Asia monsoon rainfall and SSTA is linked to the equatorial convective cluster and related to northward propagating situation, and raising the possibility that the East Asia monsoon precipitation may be more fundamentally related to the interaction of intraseasonal oscillations and the sub-regional characteristics including the surface boundary conditions and the behavior of climatological air mass.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.413-426
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• 1995

The aim of the present study is to investigate the interannual variabilities of the East Asia monsoon rainfall associated with the global sea surface temperature anomaly(SSTA). For this study, the summer rainfall(from June to August) over the twenty-eight period of 1961-1988 were analyzed with being divided by nine-subregions over East Asia including Korea, China and Japan. From the analysis of the principal modes explaining the interannual variation, the interannual variabilities of summer rainfalls in South Japan and Korea are larger than those of the other subregions of the East Asia. There is a strong negative correlation between the summer rainfalls of south China and Korea. In this study, the relationship between the summer monsoon of each subregion and SSTs of the tropical NINO regions, of western Pacific warm pool, and of the subtropical ocean were investigated. The longitudinal sections of the lagged cross correlations of the summer rainfal1 anomaly in (a) Korea and (b) south China, and the monthly SSTA in the equatorial(averaged from 65 to 6N) Pacific were analyzed. The negative maximum correlation pattems of Korea's stammer rainfal1 and SSTs over the eastern Pacific is transfered to positive maximum conrlation over central Pacific region with a biennial periodicity. In South China, the significant positive correlations are found at -12 month lag over the eastern Pacific and maximum negative correlation at 16 month lag over the central Pacific with the quasi-biennial oscillation. But the correlation coefficient reverses completely to that in Korea. In order to investigate the most prevailing interannual variability of rainfall related to the favored SSTA region, the lagged cross correlations between East Asia rainfall and SSTs over the moO regions(NINO 1+2(0-105, 90W-80W), NINO 3(5N-5S, 150W-90W), NINO 4(5N-5S, 160E-l50W) and the western Pacific worm pool (5N-5S, 120E-l60E) were analyzed. Among the lagged cross-correlation cycles in NINO regions, the maximum correlations for the negative lagged months prevail in NINO 1+2 and NINO 3, and the cross correlations for the positive lagged months NINO 4. It is noteworthy that correlation between the western Pacific warm pool SSTA and the monsoon rainfall in Korea and South China have the maximum value at negative 4 month lag. The evolution of the correlation between the East Asia monsoon rainfall and SSTA is linked to the equatorial convective cluster and related to northward propagating situation, and raising the possibility that the East Asia monsoon precipitation may be more fundamentally related to the interaction of intraseasonal oscillations and the sub-regional characteristics including the surface boundary conditions and the behavior of climatological air mass.