• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1768-1774
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• 2001

Drifting Cups on a Meandering Stream (Kyokusui-no-En) is a Poetry Party that had its origin In ancient China, and was introduced to Japan passing through Korea. The flow of the meandering stream was made clear using the flow visualization techniques, surface floating method, PTV and the numerical simulation. At the same time, the motions of floating cup, the floating speed, relating speed and the trajectory of the cup were also analysed by using an originally developed image processing technique. Based on these researches, the model channel was considered. To make this party interesting the channel must has the characteristic that the drifting cups take the random pass and stagnant at the unexpected place. This model channel is satisfied with these conditions and the fluid mechanics consideration is performed on the both points of the experimental visualization and numerical simulation.

• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.160-169
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• 2012

'YTN Science TV' that is the only one specializing in science channel in domestic have struggled low ratings and the restricted access in spite of the performance and significance that it has contributed to the population of science. This study will seek alternatives and development challenges through the comparison with the similar channel of international for the activation of the science channel. Accordingly, this study is to review the BBC knowledge channel that have contributed the successful overseas expansion and the education for the people of its country in pursuing commercial and public interest. This study will provide significant in the activation of the science channel in domestic through review of such cases.

• International Journal of Computer Science & Network Security
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• v.23 no.5
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• pp.121-127
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• 2023

A 500 km/h linear motor high speed terrestrial transportation service is planned to launch 2027 in Japan. In order to support 5G service in the train, the Sub-carrier spacing frequency of 30 kHz is planned to be used instead of common 15 kHz sub-carrier spacing to mitigate Doppler effect in such high-speed transportation. In addition, to increase the cell size of 5G mobile system, plural Base Station antenna will transmit the identical Down Link (DL) signal to form the expanded cell size along the train rail. In this situation, forward and backward antenna signals will be Doppler shifted by reverse direction respectively and the receiver in the train might suffer to estimate accurate Channel Transfer Function (CTF) for its demodulation. In this paper, Delay and Doppler Profiler (DDP) based Channel Estimator is proposed and it is successfully implemented in signal processing simulation system. Then the simulated performances are compared with the conventional Time domain linear interpolated estimator. According to the simulation results, QPSK modulation can be used even under severe channel condition such as 500 km/h, 2 path reverse Doppler Shift condition, although QPSK modulation can be used less than 200 km/h with conventional Channel estimator.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.49-54
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• 2013

Japan and South Korea since 2004 until now for the broadcast channel interference, by measuring the ongoing conflict are expected to prepare for the future, but Korea's preparation are not enough. In this study, it is pointed that cause of the interference through channel environmental analysis, and effective application of propagation prediction model was carried out between neighboring countries. Between Korea and Japan, radio duct occurs on hold due to changes in the refractive gradient, and comfirmed occurrence of broadcasts interference. The results are presented that 1% time variable, -91.80 [N-units/km], 10% time variable, -43.92 [N-units/km], 50% time variable, -586.19 [N-units/km], for effective refractive gradient. Proposed refractive gradient could contribute to actual radio propagation prediction.

• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.18-24
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• 2011

A multi-channel seismic reflection (MCS) survey was conducted in 2009 to explore the deep crustal structure of the Pacific Plate south of Hokkaido. The survey line happened to traverse a 250-km-wide Warm Core Ring (WCR), a current eddy that had been generated by the Kuroshio Extension. We attempted to use these MCS data to delineate the WCR fine structure. The survey line consists of two profiles: one with a shot interval of 200m and the other with a shot interval of 50 m. Records from the denser shot point line show much higher background noise than the records from the sparser shot point line. We identified the origin of this noise as acoustic reverberations between the sea surface, seafloor and subsurface discontinuities, from previous shots. Results showed that a prestack migration technique could enhance the signal buried in this background noise efficiently, if the sound speed information acquired from concurrent temperature measurements is available. The WCR is acoustically an assemblage of concave reflectors dipping inward, with steeper slopes (${\sim}2^{\circ}$) on th ocean side and gentler slopes (${\sim}1^{\circ}$) on the coastal side. Within the WCR, we recognised a 30-km-wide lens-shaped structure with reflectors on the perimeter.

• Journal of Forest and Environmental Science
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• v.12 no.1
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• pp.13-25
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• 1996

In recent erosion control works, securing not only the disaster prevention space but the environmental space, harmonized with surrounding environment and abundant with biological resources, are emphasized. Inspired of by the fact that efforts to secure such spaces have been being briskly promoted in Japan since the beginning of 1990s', we compile and analyze the Japanese sources about the "environmentally-sound erosion control works" to contribute to the erosion control works of our country. Specifically, in this report, we deal with the subjects of "establishment of the comfortable river environment" and "environmentally-sound erosion control works" which includes "erosion control dam", "water channel works and revetments", "fish routes" and "water quality conservation works".

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.196-208
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• 2002

Since radio interference has occurred in the TRS frequency band in the south coastal area, Korea from 1994, similar interference has been observed in the mobile-cellular frequency band. Measurement showed that the sources of the radio interference are those from the base stations for digital cellular systems in Japan. This because the receiving frequency of the base stations in Korea is same as the transmitting frequency of the base stations in Japan. Since the distance between Korea and Japan is 240 ~ 300 km, we can conclude that the main reason of the interference is ducting. In this paper a ducting channel is modeled by split-step DMFT algorithm, and simulation results for measured index profile far east coast and west sea area are analyzed.

• Journal of Communications and Networks
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• v.3 no.4
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• pp.365-373
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• 2001

We propose a new channel reservation protocol which can reduce message delay by using a counter for detection of d source conflict in a WDM single-hop network with non-equivalent propagation delay. A source convict occurs when a source node has the right to transmit more than or equal to two messages simultaneously, which are transmitted using different wavelengths. In such a case, the source node has to newly obtain the right to transmit the message. In the proposed protocol, by using a source conflict counter a source node can detect a source conflict before a wave-length assignment is performed. Therefore, the source node can start a procedure to newly obtain the right to transmit the message which cannot be transmitted due to a source conflict. We analyse the throughput performance by taking the effect of a source conflict into account, and show that the approximate analysis and the computer simulated results are close. Also, from computer simulated results, we show that our proposed protocol can reduce mean message delay dramatically without degrading throughput performance as the offered load becomes large.

• International Journal of Computer Science & Network Security
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• v.23 no.9
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• pp.8-16
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• 2023

In Japan, high-speed ground transportation service using linear motors at speeds of 500 km/h is scheduled to begin in 2027. To accommodate 5G services in trains, a subcarrier spacing frequency of 30 kHz will be used instead of the typical 15 kHz subcarrier spacing to mitigate Doppler effects in such high-speed transport. Furthermore, to increase the cell size of the 5G mobile system, multiple base station antennas will transmit identical downlink (DL) signals to form an expanded cell size along the train rails. In this situation, the forward and backward antenna signals are Doppler-shifted in opposite directions, respectively, so the receiver in the train may suffer from estimating the exact Channel Transfer Function (CTF) for demodulation. In a previously published paper, we proposed a channel estimator based on Delay and Doppler Profiler (DDP) in a 5G SISO (Single Input Single Output) environment and successfully implemented it in a signal processing simulation system. In this paper, we extend it to 2×2 MIMO (Multiple Input Multiple Output) with spatial multiplexing environment and confirm that the delay and DDP based channel estimator is also effective in 2×2 MIMO environment. Its simulation performance is compared with that of a conventional time-domain linear interpolation estimator. The simulation results show that in a 2×2 MIMO environment, the conventional channel estimator can barely achieve QPSK modulation at speeds below 100 km/h and has poor CNR performance versus SISO. The performance degradation of CNR against DDP SISO is only 6dB to 7dB. And even under severe channel conditions such as 500km/h and 8-path inverse Doppler shift environment, the error rate can be reduced by combining the error with LDPC to reduce the error rate and improve the performance in 2×2 MIMO. QPSK modulation scheme in 2×2 MIMO can be used under severe channel conditions such as 500 km/h and 8-path inverse Doppler shift environment.

• Journal of the Korean Society of Food Culture
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• v.35 no.5
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• pp.407-416
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• 2020

Food tourism is recognized as a unique form of tourism product that combines traditions and regional characteristics and has become an international trend. However, research on food tourism in Korea is limited. Thus, this study investigated the selection attributes of food tourism in Italy, France and Japan. A qualitative study was conducted among 34 foreign food tourism experts on food tourism in their respective countries to find possible directions for Korean food tourism. As a result of this study, 'Food attraction', 'Traditionality', 'Locality', 'Convenience', 'Cultural Characteristics', and 'Appropriateness of price' were the attributes identified from the expert's comments. Marketing strategies such as improving quality of service and food itself, quality of service, developing diverse food tourism product, and building marketing channel will improve the status of food tourism in Korea.