• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1135-1142
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• 2017

In this paper, we propose an algorithm that can automatically mix the screen and sound by tracking the change of the sound data according to the screen change so that the real sound can be implemented in the personal broadcasting service. Since the personal broadcasting service is often broadcasted lively, it should be convenient to have a real-time mixing. Through experiments, it was confirmed that the sound pressure changes in a wide range in the high frequency band related to the clarity for understanding according to the rotation angle change of the screen. Regression analysis of the sound pressure changes at 2kHz, 4kHz, and 8kHz, The attenuation change of sound pressure was observed at the slope of -1.17, the slope of -2.0, and the slope of -2.44 for each frequency. Therefore, these experiment results can be applied to the VR service. This study is expected to be useful data in the implementation of personal broadcasting service.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.112-117
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• 2006

We experimentally investigated the transmission characteristics of 400 Gbit/s (10 Gbit/s ${\times}$ 40 channels) WDM signals with 100 GHz channel spacing over 323 km of installed NZ_DSF. The installed fiber has optical properties of 0.28 dB/km attenuation, 4.3 ps/nm/km dispersion, $0.083ps/nm^2/km$ dispersion slope and less than $0.05ps/km^{1/2}$ PMD coefficient. In this experiment, two cases of dispersion compensation schemes, the lumped type and the distributed type, were compared. The results implied that the distributed type dispersion compensation in which dispersion compensation devices are inserted at the end of the each span showed better transmission performance than the lumped one in which dispersion compensation devices are located at the transmitter and receiver sites. From the analysis of the experimental results, we verified that different transmission performance comes from the power penalty induced by XPM in the distributed scheme is lower than the lumped scheme case.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.89-96
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• 2000

Landslide damage comprise most part of the damages from the earthquake and it only causes the damage to lives and structures directly but also cease the operation of social system by road or lifeline failure. For these reasons hazard assesment on the landslides has been recognized very important. And hazard maps have been used to visualize the hazard of the landslide. In this study as first step for application of hazard map to domestic cases hazard maps are made for the Ul-Joo Ul-san Korea, Where the Yan-san faults are located. For building hazard maps the degree of hazard are evaluated based on Newmark displacement and the resulting maps are constructed by GIS technique. In hazard assesment maximum ground acceleration obtained from attenuation equation of wave propagation and design earthquake acceleration suggested by Ministry of construction are used for acceleration term. Hazard maps are made by GIS programs Arc/Info and Arc/View based on the digital maps and data from lab tests and elastic wave surveys The maps show the possible landslide regions significantly and the displacements of slide are proportional to the slope angles.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.561-566
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• 2008

Recently, because of development of the high speed train technology, the vibration loads by train is significantly increased ever than before. This buried gas pipelines are exposed to both repeated impact loads, and, moreover, they have been influencing by vibration loads than pipeline which is not located under vehicle loads. The vibration characteristic of pipeline is examined by dynamic analysis, and variable is only train speed. Since an effect of magnitude of vibration loads is more critical than cover depth, as increasing the train speed, the vibration speed of buried pipelines is also increased. The slope of vibration velocity is changed by attenuation of wave, at train speed, 300 km/h. From the analysis results, the vibration velocity of pipelines is satisfied with the vibration velocity criteria which are established by Korea Gas Corporation. The results present operation condition of pipelines under rail loads has fully sound integrity based on KOGAS specification.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.3
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• pp.74-80
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• 1993

Runoff simulation tests to investigate the flow mechanics of nonsuomerged overland flow in a natural grass intervening land system were condueted and a modified kinematic wave overland runoff model developed by Choi et al. (1993) was verified. Nonhomogeneity and heterogeneity of the soil, slope, local topography, infiltration, grass density, and the density and activity of the soil microhes and wild animals were the major factors affecting the flow. Streamlines were disturbed by grass stems and small concentrated flows due to the disturbed streamlines and local topography were observed a lot. Relatively larger concentrated flows were observed where bundles of grass were dominant than where individual grasses were growing. Predicted hydrographs were agreed verv well with measured hydrographs. Since the modified model considers grass density in computing flow depth and hydraulic radius, it can be better than existing kinematic wave model if it were used to route nonpoint source pollutant attenuation processes in many grass intervening land systems.

• Journal of Korea Multimedia Society
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• v.17 no.11
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• pp.1270-1278
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• 2014

The modern infrared (IR) imaging systems use mainly one or more wavelength bands among short wavelength IR (SWIR), middle wavelength IR (MWIR), and long wavelength IR (LWIR) bands. In the process of IR image synthesis and modeling, IR image wavelength-band conversion which transforms arbitrary band image to other band one is required. The wavelength-band conversion procedure includes a temperature estimation process of an object surface. However, in this procedure, an approximated Planck's radiation equation causes errors in estimated temperature. In this paper, we propose an estimation temperature error attenuation method in IR image band conversion procedure. The estimated temperature is corrected with a slope information of radiance according to it. The corrected temperature is used for generation of the other band IR image. The verification of proposed method is demonstrated through the simulation.

• Tribology and Lubricants
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• v.17 no.6
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• pp.482-489
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• 2001

Changes in light transmission characteristics caused by various types of oil contaminations were experimentally measured with a built-in type wear monitoring device. Three kinds of iron powders of different size distribution, carbon duct, two kinds of solutions and grease were used for the test contaminants in this work. Light intensity of the transmitted light was measured with the contamination level. Results showed that the transmitted light intensity decreased linearly with the contamination concentration in the oil and the slope was affected by the size distribution. Light attenuation was also caused greatly by carbon dust, water contamination and poly-meric fibers in terms of the light absorption. As a result, it was proved that the optical measurement device could be applicable effectively for detecting any significant change in lubricating oils.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.15-22
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• 2014

The automobile cruise control system tries to maintain a constant velocity in the face of disturbance mainly caused by mass changes or changes in the slope of a road. The controller should compensate for such disturbances and model uncertainties. In this paper, we study on the disturbance observer based controller for cruise control system. In the presence of disturbances and model uncertainties, we carry out computer simulations in order to compare the performance of the conventional PI controller and DOB controller. From the simulation results, we found that the performance of DOB controller is superior to that of the conventional PI controller.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.287-298
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• 2001

Change in light transmission characteristics caused by various types of oil contaminations was experimentally measured with a built-in type wear monitoring device. Three kinds of iron powders of different size distribution, carbon dust, two kinds of solutions and grease were used for the lest contaminants in this work. Light intensity of the transmitted light was treasured with the contamination level. Results showed that the transmitted light intensity decreased linearly with the contamination concentration in the oil and the slope was affected by the size distribution. Light attenuation was also caused greatly by carbon dust, water contamination and polymeric fibers mainly due to the light absorption. As a result, it was proved that the optical measurement device could be applicable effectively for detecting any significant change iii lubricating oils.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.2
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• pp.110-117
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• 1999

In order to ultrasonically evaluate creep cavities pure copper samples were subjected to creep test and their microstructures were examined. Ultrasonic velocities. frequency-dependent magnitude spectra and attenuations were measured on a series of copper samples obtained from the different stages of creep test. Velocities measured in three directions with respect to the loading axis decreased and their anisotropy increased as a function of the creep-induced porosity. The anisotropic behavior could be attributed to the progressive change of pore shape and preferred orientation as the creep advanced. The 2% porosity by volume decreased the longitudinal and shear wave velocities by 11% and 4%, respectively. Furthermore, both velocities decreased nonlinearly with the porosity. As the creep damage developed, the magnitude spectra lost high frequency components and their central frequencies shifted to lower values. The attenuation showed almost linear behavior in the frequency range used. Normalized velocity, central frequency shift and attenuation slope were selected as nondestructive evaluation parameters. These results were presented and showed good relations with the porosity content.