• Journal of Navigation and Port Research
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• v.28 no.7
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• pp.619-627
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. We also considered the increase of water depth at the entrance channel by dredging work up to 15 meters depth in order to see the dredging effect. Among several model analyses, the nonlinear and breaking wave conditions are showed the most applicable results. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.151-158
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• 2007

The static and dynamic behaviour of VGT and EGR systems has a significant impact on overall engine performance, fuel economy and exhaust emissions. This is because they define the state and composition of the air charge entering the engine. This work focused on the effect of the aperture ratio of VGT and EGR on the emission and flow characteristics under partial loads conditions. The investigation carried out using 2 liter PCCI 4 cylinder diesel engine with VGT and EGR. The result of this study shows that smoke increases with increasing EGR rate and NOx decreases with increasing EGR rate. It was also found that the residual gas contents greatly impact on soot emission under partial load condition. Finally, it can be concluded that VGT and EGR aperture ratio can greatly impact not only on soot and NOx but also air charging.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.10
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• pp.960-964
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• 2005

In this paper, we dealt with a partial discharge(PD) measurement method that has been accepted as an effective and non-destructive technique to estimate insulation performance of low-voltage electric and electronic devices. The PD measurement system Is composed of a coupling network, a low noise amplifier, and associated electronics. h shielded box Is adopted to make a better measurement environment against around noise. A low cut-off frequency of the coupling network estimated by a sinusoidal wave input was 125 kHz (-3 dB). Calibration tests on laboratory set-up have shown that the PD measurement system has a stable sensitivity of 10 mV/pC. In an application test oil a low-voltage three phase Induction motor (5 HP), we could detect 0.53 pC level of partial discharge at the applied voltage of AC 650 $V_{peak}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2184-2188
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• 2007

We developed a novel method of partial discharge(PD) location based on the fact that the waveform of PD signal propagate along the GIB (Gas Insulated Bus) is composed of several modes of electromagnetic wave with different group velocities and cut-off frequencies. From the PD waveform, measured at a broadband PD sensor attached on the GIB, we could derive arrival time and frequency components of different modes using the short term Fourier transform or etc. After the group velocities of different modes are calculated, the location of the PD source could be estimated. To show the effectiveness of this new locating method in a real on site application, we used this method to locate the position of a PD source at a 76 m long 345 kV GIB substation. The estimated location of the PD source using the method proposed above was in good agreement with the actual location found from the inspection result of internal component in the GIB with 2.4% of the estimation error.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.217-225
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.296-305
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• 2019

With the growth of the Korean Wave and the importance of the fandom economy, it is necessary to consider the competitiveness of the Korean Wave with its fandom viewpoint. Particularly, the fandom phenomenon shows the characteristics of identifying the favorite star and actively acquiring and sharing related information in the fan community. Therefore, in this study, we examined the influence of Korean national image on consumers' intention to use Korean contents, and examined the mediating effects of fandom identification among Chinese, Japanese and Vietnamese consumers. As a result of the empirical analysis, cultural image, corporate image, and product image were found to have statistically significant influence on the intention to use Korean Wave contents. In addition, star identification and pan community identification showed partial mediation in the effect of cultural images on the intention to use Korean contents. The results of this study suggest that the Korean Wave is a leading factor for the continuous development of Korean Wave, not the halo effect point for improving the national image, and the mediating effect of the fandom phenomenon is tested empirically.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1861-1868
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• 2014

In wireless communication systems, a frequency offset exist at the received signal due to the transmitter-receiver oscillator mismatch and Doppler effect in mobile environments. Those offsets rotate the received signal's phase and degrade the receiver performance. Hence, estimation and compensation of the frequency offset is crucial at the receiver. This paper proposes a new frequency offset estimation technique based on partial correlation. The proposed method requires less computational complexity than that of the conventional method. In addition, since the proposed one can estimate a wide range of frequency offset without estimation accuracy loss, the application of the method is desirable for the communication environments that have a large frequency offset. In order to verify the performance of our proposed scheme, a series of computer simulations have been carried out and compared against those of the conventional method.

• The Journal of Internal Korean Medicine
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• v.30 no.3
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• pp.525-533
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• 2009

Objectives : There are lots of reports that cardiovascular disease, including hypertension, cerebro-vascular accident, and coronary heart disease, is related to atherosclerotic changes. Increased serum levels of lipids could play a role in these changes. This study aimed to investigate the relationship between PWV and risk factors of cardiovascular disease, including serum lipid values. Methods : This study included 261 subjects ($49.32{\pm}11.79$ years, 112 male) who underwent PWV and serum lipid evaluation. We investigated the correlation between serum lipid values, blood pressure, body mass index (EMI) and PWV. Pearson's correlation and partial correlation analysis were applied to examine the relationship between PWV and risk factors of cardiovascular disease. Results : Serum triglyceride, total cholesterol, systolic blood pressure, and diastolic blood pressure were significantly correlated with PWV. Partial correlation coefficient adjusted by age yielded significant correlation between serum triglyceride, systolic blood pressure, diastolic blood pressure and PWV. Conclusion : In this study, it seems that there are significant relationships between PWV, triglyceride and blood pressure. We could suggest that PWV might have some relationships with Dam-eum and blood stasis in oriental theory.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.2
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• pp.86-98
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• 2016

In this study, after the installation of a subsea pipeline, backfilling was performed in the trenched area. During these operations, a stability problem in the subsea pipeline occurred. The pipeline was directly impacted by environmental loading such as waves and currents that were caused by backfill material when scouring or sediment transport and siltation was carried out. Therefore, this study reviewed whether trenching was necessary, and conducted research into an indigenous seabed property that contains granular soil. A study of cohesive soil was also conducted in order to cross-correlate after calculating the values of the critical Shields parameter relevant to elements of the external environment such as waves and current, and the shear Shields parameter that depends on the actual shearing stress. In case of 1), sedimentation or erosion does not occur. In the case of 2), partial sedimentation or erosion occurs. If the case is 3), full sedimentation or erosion occurs. Therefore, in the cases of 1) or 2), problems in structural subsea pipeline stability will not occur even if partial sedimentation or erosion occurs. This should be reflected particularly in cases with granular and cohesive soil when a reduction in shear strength occurs by cyclic currents and waves. In addition, since backfilling material does not affect the original seabed shear strength, a set-up factor should be considered to use a reduced of the shear strength in the original seabed.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.34-40
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• 2010

Bragg reflection of nonlinear waves is simulated by a 2D fully nonlinear numerical wave tank (NWT). The developed NWT was based on the Boundary Element Method (BEM) with potential theory and the mixed Eulerian-Lagrangian (MEL) time marching scheme with Runge-Kutta 4th-order time integration. A spatial variation of wave elevations and their Fourier amplitudes of each component are compared to investigate the effect of sea bottom ripples and their relative heights. The incident waves over an undulated sea bottom are partially reflected and changed to partial standing waves due to Bragg reflection. The present results are verified with linear calculations and experimental data. It is found that the 1st-order wave component is mainly affected by Bragg reflection and its spatial modulation is significant in front of the bottom ripples.