• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.162-166
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• 2000

In this paper, we studied the relation between using amount of Ferrite and electromagnetic wave absorbing properties of ferrite-rubber composite. The variation of using amount of Ferrite have been 52 wt.% ~ 62 wt.%. As s result, it has been shown that the electromagnetic wave absorbing properties of ferrite-rubber composite are related to the using amount of Ferrite in composite. And, we can control electromagnetic wave absorbing properties of ferrite-rubber composite by the control of using amount of Ferrite.

• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.379-389
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• 1996

To experimentally investigate the several wave patterns for the horizontal countercurrent stratified air-water flow, a series of systematic experimental studies have been performed. The experiments are carried out in a horizontal pipe with 4m in length and 102mm in inner diameter. The oater and air superficial velocities vary from 0.0004 to 0.0204 and from 0 to 6m/s, respectively. The instantaneous water thickness is measured by parallel-wire conductance probes, and the wave field is recorded by high speed video camera. Also, to evaluate the wave effect on interfacial friction factor, the pressure drop is measured. Statistical data anal)sis is accomplished in order to obtain the fundamental wave parameters such as un amplitude, length and velocity, and spatial growth factor. By using these statistical parameters, the wave regime boundaries can be verified.

• Journal of the Korean Society of Food Culture
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• v.29 no.3
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• pp.250-258
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• 2014

This research investigated the relationship among Korean Wave Cultural Contents consumption of Korean food, Korean products, and Learning of the Korean language. The survey targeted non-Koreans who were either interested in or experienced Korean Wave Cultural Contents. Exactly 61.3% of subjects had traveled to Korea. The most common method of experiencing the Korean Wave was via the Internet (57.7%), followed by TV (21.1%) and Mobile (7.7%). The most popular Korean Wave Contents were K-pop (35.2%) and TV Dramas (31.0%). Movies were preferred in the Americas ($3.63{\pm}0.83$) and Asia ($3.63{\pm}1.09$), whereas K-pop was preferred in Asia ($3.68{\pm}1.12$) and games preferred in Europe ($2.50{\pm}1.56$). Regarding Korean food, most participants had tasted Kimchi (81.7%), followed by Bulgogi (74.6%), Bibimbap (66.9%), and Galbi (66.2%). According to the country-by-country survey, in the case of Galbi (p<0.05), Bibimbap (p<0.05), and Bulgogi (p<0.05), Asians had more experiences with Korean food compared to those from other regions. Meanwhile, in the case of satisfaction of Korean food, Bulgogi ($4.22{\pm}1.05$) was ranked highest, whereas Kimchi ($3.85{\pm}1.15$) was ranked lowest. According to the region-by-region survey, those from Oceania and other regions preferred Kimchi ($4.25{\pm}0.71$) and Bulgogi ($4.50{\pm}4.50$) while the Americas preferred Galbi ($4.82{\pm}0.39$) and Bibimbap ($4.54{\pm}0.81$). Bulgogi ($2.76{\pm}0.06$) was highly ranked as a representative Korean Food while Kimchi ($2.44{\pm}0.71$) was ranked the lowest. This research explained that among Korean Wave Cultural Contents, movies and music positively influenced on the 'Image of Korea', movies and K-pop effected 'Purchasing intention of Korean products', and TV Dramas, movies, and K-pop effected 'Purchasing intention of Korean Food'.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.142-149
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• 2019

In this study, the past erosion history and current status in the CHUNG-UI beach of Eulwang-dong, Jung-gu, Incheon-Si, South Korea were investigated and analyzed the wave with wave-induced current to investigate the causes of coastal erosion. As a result, the significant wave height ($H_{1/3}$) was in the range of 0.07~1.57 m and the mean value was 0.21 m. The maximum wave height ($H_{max}$) was in the range of 0.02-4.76m and the mean value was 0.27m. The vertical wave height and cycles were estimated through numerical model experiments of wave transformation. The 50-year frequency design wave height ranged from 0.82m to 3.75m. As a result of the experiment of wave-induced current, wave-induced current in the CHUNG-UI beach was decreased after the installation of the Detached breakwater and the Jetty. On the other hand, when the crest elevation was increased up to 5 m, there was no significant change, but when the crest elevation was increased to 8m, strong wave-induced current occurred around the submerged breakwaters due to lowered depth of water. In addition, the main erosion of the CHUNG-UI beach is due to the intensive invasion of the wave characteristics coming from the outer sea into the white sandy beach. The deformation of the wave centered on the front of the sandy beach caused additional longshore currents flowing parallel to the sandy beach and rip currents in the transverse direction, thus confirming that the longshore sediment was moved out of the front and out of the sea. The results of this study can be used as preliminary data for the recovery of the sand and the selection of efficient erosion prevention facilities.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.147-153
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• 2013

There exist various types of the WEC (Wave Energy Converter), and among them, the point absorber is the most popularly investigated type. However, it is difficult to find examples of systematically measured data analysis for the design of the point absorber type of power buoy in the world. The study investigates the wave load acting on the point absorber type resonance power buoy wave energy extraction system proposed by Kweon et al. (2010). This study analyzes the time series spectra with respect to the three-year wave data (2002.05.01~2005.03.29) measured using the pressure type wave gage at the seaside of north breakwater of Hupo harbor located in the east coast of the Korean peninsula. From the analysis results, it could be deduced that monthly wave period and wave height variations were apparent and that monthly wave powers were unevenly distributed annually. The average wave steepness of the usual wave was 0.01, lower than that of the wind wave range of 0.02-0.04. The mode of the average wave period has the value of 5.31 sec, while mode of the wave height of the applicable period has the value of 0.29 m. The occurrence probability of the peak period is a bi-modal type, with a mode value between 4.47 sec and 6.78 sec. The design wave period can be selected from the above four values of 0.01, 5.31, 4.47, 6.78. About 95% of measured wave heights are below 1 m. Through this study, it was found that a resonance power buoy system is necessary in coastal areas with low wave energy and that the optimal design for overcoming the uneven monthly distribution of wave power is a major task in the development of a WEF (Wave Energy Farm). Finding it impossible to express the average spectrum of the usual wave in terms of the standard spectrum equation, this study proposes a new spectrum equation with three parameters, with which basic data for the prediction of the power production using wave power buoy and the fatigue analysis of the system can be given.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.251-261
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• 2007

The wind-wave interaction around the Kyung-gi Bay, Korea, was studied using the observed data from ocean buoy at DeuckJeuck-Do from Jan. to Dec., 2005, and from waverider data at KeuckYeulBee-Do on Mar. 19-26 and May 23-28, 2005. Wind-driven surface waves and wave-driven wind speed decrease were estimated from the ocean buoy data, and the characteristics of wave spectrum response were also investigated from the waverider data for the wave developing and calm stages of sea surface, including the time series of spectrum pattern change, frequency trend of the maximum energy level and spectrum slope for the equilibrium state range. The wind speed difference between before and after considering the wave effect was about $2ms^{-1}$ (wind stress ${\sim}0.1Nm^{-2}$) for the wind speed range $5-10ms^{-1}$ and about $3ms^{-1}$ (wind stress ${\sim}0.4Nm^{-2}$) for the wind speed range $10-15ms^{-1}$. Correlation coefficient between wind and wave height was increased from 0.71 to 0.75 after the wave effect considered on the observed wind speed. When surface waves were generated by wind, the initial waves were short waves about 4-5 sec in period and become in gradual longer period waves about 9-10 sec. For the developed wave, the frequency of maximum energy was showed a constant value taking 6-7 hours to reach at the state. The spectrum slope for the equilibrium state range varied with an amplitude in the initial stage of wave developing, however it finally became a constant value 4.11. Linear correlation between the frictional velocity and wave spectrum for each frequency showed a trend of higher correlation coefficient at the frequency of the maximum energy level. In average, the correlation coefficients were 0.80 and 0.82 for the frequencies 0.30 Hz and 0.35 Hz, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.12
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• pp.787-791
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• 2012

Characteristics of particle separation in water using labscale acoustic standing wave were studied. Acoustic standing wave is similar to either sound wave or ultrasonic, which makes a constant wave while returning to the origin by reflector. During that time, particulates dispersed in water are collected on the node of wave, where a sound pressure is zero. Acoustic standing wave transducer as of 28.0 kHz and 1.0 MHz were utilized and $6.8{\mu}m$ kaolin and $100.5{\mu}m$ redmud in average diameter were used as experimental materials in water. Once acoustic standing wave are generated in water, water temperature rises by $0.15{\sim}0.20^{\circ}C/min$ due to a sound pressure. Initial concentration of kaolin and redmud were controlled to have same as of 0.1, 0.2, 0.3, 0.4, 0.5 g/L, respectively. Removal efficiency of the turbidity in a reacting chamber after 5 minutes, when acoustic sound wave was formed in most distinct, was measured to have 18.2~56.2% for kaolin and 23.0~53.6% for redmud at 1.0 MHz. Particle separation was not observed at 28.0 kHz.

• Journal of the Korean Chemical Society
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• v.7 no.1
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• pp.34-37
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• 1963

Cobalt(Ⅲ) ion gives two step waves with $E_{1/2}$－0.1V(?)(vs.S.C.E.) and $E_{1/2}$－1.37V(vs. S.C.E.) from a base electrolyte consisting of 0.1 M TEA＋sodium borate＋0.0002% gelatin. The first wave results from the reduction Co(Ⅲ) to Co(Ⅱ). The second wave corresponding to the reduction Co(Ⅱ) to Co(0) and this wave is diffusion controlled. The diffusion current constant of the second wave is 2.7. Under these-conditions, diffusion current of the second wave is proportional to the concentration of Co (Ⅱ) in the range of $10^{-3}{\sim}10^{-4}$ M.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.309-316
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• 2017

In this paper, numerical modeling is conducted to analyze the tension of an anchor line by varying the size and drag coefficient of a buoy when the trapnet is influenced by the wave and the current simultaneously. A mass-spring model was used to analyze the behavior of trapnet underwater under the influence of waves and current. In the simulation of numerical model, wave height of 3, 4, 5 and 6 m, a period of 4.4 s, and the flow speed of 0.7 m/s were used for the wave and current condition. The drag coefficients of buoy were 0.8, 0.4 and 0.2, respectively. The size of buoy was 100, 50 and 25% based on the cylindrical buoy ($0.0311m^3$) used for swimming crab trap. The drag coefficient of the trapnet, the main model for numerical analysis, was obtained by a circular water channel experiment using a 6-component load cell. As a result of the simulation, the tension of the anchor line decreased proportional to buoy's drag coefficient and size; the higher the wave height, the greater the decrease rate of the tension. When the buoy drag coefficient and size decreased to one fourth, the tension of the anchor line decreased to a half and the tension of the anchor line was lower than the holding power of the anchor even at 6 m of wave height. Therefore, reducing the buoy drag coefficient and size appropriately reduces the trapnet load from the wave, which also reduces the possibility of trapnet loss.

• Journal of Navigation and Port Research
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• v.34 no.4
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• pp.299-304
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• 2010

In this paper, the EM wave absorber was developed for the 94-GHz detecting radar system. To analysis an EM wave absorber in millimeter wave band, we fabricated three absorber samples using carbon black and titanium dioxide and permalloy with chlorinated polyethylene. After measuring the complex relative permittivity, the absorption characteristics are simulated by 1D FDTD according to different thicknesses of less than 1.0 mm. Then, the EM wave absorber was fabricated based on the FDTD simulation. As a result, the measured results agreed well with the simulated ones, and the developed EM wave absorber with a thickness of 0.7 mm had the desired absorption characteristics of more than 14 dB in the frequency range of the 94-GHz band.