• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.823-830
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• 2013

The purpose of this study is to develop a noise reduction device installed at the top of noise barrier for further decreasing of noise level of 400 km/h class high-speed railroad. For this, the frequency spectrum of 400 km/h class high-speed railroad was analyzed through the field noise test, and the tuning frequency was determined to design a noise reduction device. The noise reduction device was designed to have noise reduction performance of at least 3 dB(A) using the prediction method(2D BEM) and through the laboratory test with the prototype. Finally, the outdoor test showed that this device could decrease noise level of 400 km/h class high-speed railroad even more than 3 dB(A).

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.997-999
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• 1999

We fabricated white light-emitting organic electroluminescent device which have a mixed single emitting layer containing poly(N-vinylcarbazole)[PVK], tris(8-hydroxyquinoline)aluminum[Alq3] and poly(3-hexylthiophene)[P3HT] and investigated the emission properties of it. We expect to obtain a blue light from PVK, green light from Alq3 and red light from P3HT The fabricated device emits white light over 18V with slight orange light. We think that the energy transfer in a mixed layer occurred from PVK to $Alq_3$ and P3HT resulted in decreasing the blue light intensity from PVK. With mixing of N, N'-diphenyl-N, N'-(3-methylphenyl)-[1,1'-biphenyl]-4, 4'-diamine[TPD], hole transport material, to the emitting layer, the luminance intensity of device was increased 50 times than that of the device which not contain TPD. We find that the efficiency of the white light electroluminescent device can be improved by injecting electron more effectively and blue light need to improve the color purity of white light.

• Journal of KIBIM
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• v.13 no.4
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• pp.45-53
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• 2023

The educational benefits and potential of XR as a new medium are well recognized. However, there are still limitations in understanding the specific effects of XR compared to the more widely utilized representation of images on computer monitors. This study therefore aims to demonstrate the differences in effectiveness between the two technologies and to draw implications from a cognitive comparison of three-dimensional objects represented on a flat surface and virtually. The study was conducted a quantitative research method with an experiment involving two independent groups, and the results were tested using regression analysis. The results showed that for low-level, two-dimensional objects, the computer monitor method may be more effective, but above a certain level of complexity, the effectiveness of learning through the monitor tends to decrease rapidly. On the other hand, the group that used extended reality technology showed relatively high comprehension compared to the monitor group even as the complexity increased, and in particular, unlike the monitor group's rapidly decreasing comprehension level, the extended reality technology group showed a trend of decreasing comprehension with the level of complexity, suggesting the potential for compatibility and predictability in the use of technology.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.156-159
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• 2005

The outer race of CV(constant velocity) joint is an important load-supporting automotive put that transmits torque between the transmission gear box and driving wheel. The outer race is difficult to forge because its shape is very complicated and the required dimensional tolerances are very small. To guarantee the dimensional accuracy of the forged CV Joint, the quick and precise measurement is required to increase the inspection speed of forged products. Therefore in this study, PP(Pre-Position) Device to decrease the inspection time of measuring system has been developed to cope with forging cycle time. The measured inspection time confirms that the PPD is very effective in decreasing inspection time.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.554-557
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• 2018

A catch basin sump is one major habitat for mosquito larvae, especially in urban areas. This study developed a device for mosquito control, specifically for the catch basin sump. It consists of a housing, is a little smaller than the catch basin sump, numerous floating materials, which the key component for mosquito control, and mesh nets. The small balls or pyramid-shaped floating materials inhibit mosquito enclosures and spawning by significantly decreasing the surface area of the water, which is essential for the mosquito life cycle. These floating materials were designed to keep the water flowing. The mesh nets were installed to prevent the outflow of floating materials. The efficiency of the floating materials was tested with 3 conditions (1, 2, 3 layers of floating materials) and a control group. The emergence of mosquito adults decreased by 20% in one-layer, and 70-80% in second and third layers. Therefore, this device is expected to certainly contribute to mosquito population control in the catch basin sump.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.90-93
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• 2002

In the surface pressure-area isotherms of mixed monolayers, mixtures containing as much as 30 mol% of AA form stable condensed monolayer while the monolayer without AA is in the expanded state because PVK take on 3D collapsed. All of the mixed monolayers with 0, 10, 20 and 30 mol% of AA could be readily transferred onto ITO substrate at 16, 17, 24 and 26 mN/m, respectively. The monolayer containing 30 mol% of AA, however, showed a roughness value of 28A and became homogeneous decreasing with the phase separation. We fabricated organic EL device of ITO/CuPc/MEL/BBOT/iLiF/Al using mixed monolayer of 13, 19 and 25 layer deposited by LB method as a emitting layer. In the voltage-current characteristics of EL device, current density was much smaller than that of the spin-coated devices. It may due to the large contact resistance existed at the interface of LB layer/organic layer inhibit carrier injection to the emitting layer. EL spectra of device showed peaks at 450. 470, 505, 555 and 650 nm and the white light emission indicate the CIE coordinate x=0.306, y=0.353.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.169-170
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• 2018

With improving living standards, there is a growing interest in health. As the life patterns of modern people are convenient and diversified, relative movement is decreasing. These changes in lifestyle are also affecting our health, and the signs of health anomalies are also manifested in various and complex ways. Therefore, in this study, we need a device to measure abnormal symptoms of varicose veins, and to investigate basic data of varicose veins for development of such device. This will be used as a basic research for future device development.

• Journal of the Korean Solar Energy Society
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• v.28 no.2
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• pp.50-57
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• 2008

This study intends to evaluate the effect on indoor environment(annual thermal load, sunshine)by the application of the movable horizontal shading device on summer and winter season. For these purpose, we supposed the models which are composed of the several horizontal shading devices. Then we analyzed the simulation using the IES5.5.1 and Seoul weather data. The results of this study are as follows: 1) The proper length, angle of horizontal shading device is 2.1m, 28 degree, respectively. 2) The decreasing rate of the annual load of the Movable Horizontal Shading Model(MHSM) in comparison with the No Shading Model(NSM) & Conventional Horizontal Shading Model(CHSM) is 31.11%, 6.63% respectively. 3) The decrease of sunshine of the MHSM on summer season is effective the alleviation of visual displeasure. On the other hand, the increase of sunshine of the MHSM on winter season is effective the psychological comfort. Further study is to be required the sensitivity analysis on the various shading length for the realistic proper shading length.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.6
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• pp.381-387
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• 2020

According to the increase of concern for environmental problems, the energy saving becomes an important issue because it is one of the most effective methods of decreasing CO2 which is major environmental problem. In the present study, the post device after propeller related with rudder has been focussed. Recently the full-spade twisted rudder has been frequently used not only to increase the efficiency but also to remove the cavitation risk on leading edge. In addition to that the rudder bulb is also applied to the rudder to increase the propulsion efficiency as well as to minimize the cavitation erosion risk around twisting part. The parametric study has been conducted for investigating the optimum configuration of twisting rudder with bulb by CFD. The present optimization has been applied to the KVLCC2 full-body ship. The verification of the computed results is also expected to be conducted by the comparison with experimental results in the near future.

• Journal of the Korean Magnetics Society
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• v.12 no.5
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• pp.163-167
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• 2002

In order to study the temperature dependence of the magnetostatic wave modes for an YIG thin film, grown by a liquid phase epitaxy method, The ferromagnetic resonance was performed by an FMR spectrometer in the temperature range -140$\^{C}$∼200$\^{C}$. The magnetostatic surface wave and backward volume wave modes show periodic excitations in parallel configuration. The resonance fields of all modes and intensities decreased with decreasing the temperature. All magnetostatic modes can be well explained by the Walker and Damon-Eshbach theory. The calculated saturation magnetization Ms of the YIG thin film was increased with decreasing the temperature. The line widths of magnetostatic modes changed in various trends with decreasing the temperature.