• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.235-235
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• 2011

Lau basin of south Pacific, as an active back arc basin, is promising area bearing seafloor massive hydrothermal deposit that is located in a subduction zone between the Pacific ocean plate and Indo-Australian continental plate. Korea Ocean Research and Development Institute tracked from 2004 to 2006 the hydrothermal activity to the extension of the northeast Lau Basin, targeting seamount. hydrothermal activity by tracking was found hydrothermal evidences. In this study, Marine seismic survey was carried out in the Lau basin seamount of the possibility of hydrothermal deposit. In particular, Marine magnetic survey and seismic survey was carried out at the same time in TA-12 seamount and noise characteristics were found in the seamount. the main process of data processing is Bandpass filter, FK filter, Deconvolution for noise attenuation such backscatter and multiple reflections. the migration is performed to compensate for reflection points followed by seamount of a slope. In this study, bedrock and upper strata could be identified and in the Future, the comparative method with Multi Beam Echo Sounder(MBES) are likely to derive the correct velocity model, the marine magnetic survey results should be considered.

• The Journal of the Acoustical Society of Korea
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• v.23 no.8
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• pp.554-561
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• 2004

As the technologies of semiconductor and multimedia communication have been improved. the high-quality video and the multi-channel audio have been highlighted. MPEG Audio Layer 3 decoder has been implemented as a Processor using a standard. Since the synthesis filter of MPEG-1 Audio Layer 3 decoder requires the most outstanding operation in the entire decoder. the synthesis filter that can reduce the amount of operation is needed for the design of the high-speed processor. Therefore, in this paper, the synthesis filter. the most important part of MPEG Audio, is materialized in FPGA using the method of DAULT (distributed arithemetic look-up table). For the design of high-speed synthesis filter, the DAULT method is used instead of a multiplier and a Pipeline structure is used. The Performance improvement by 30% is obtained by additionally making the result of multiplication of data with cosine function into the table. All hardware design of this Paper are described using VHDL (VHIC Hardware Description Language) Active-HDL 6.1 of ALDEC is used for VHDL simulation and Synplify Pro 7.2V is used for Model-sim and synthesis. The corresponding library is materialized by XC4013E and XC4020EX. XC4052XL of XILINX and XACT M1.4 is used for P&R tool. The materialized processor operates from 20MHz to 70MHz.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.77-82
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• 2017

This paper related with the VSS_SE-MMA (Varying Step Size_Signed Error-MMA) which possible to improving the equalization performance that employing the varying adaptive step size based on the nonlinearities of error signal of SE-MMA (Signed Error-MMA), compensates the intersymbol interference by distortion occurs at the communication channel, in the transmitting the spectral efficient nonconstant modulus signal such as 16-QAM. The SE-MMA appeared to the reducing the computational arithematic operation using the polarity of error signal in the updating the tap coefficient of present MMA adaptive equalizer, but have a problem of equalization performance degradation. The VSS_SE-MMA improves the problem of such SE-MMA, using the varying step size consider the error signal in the update the adaptive equalizer tap coefficient, and its improved performance were confirmed by simulation. For this, the output signal constellation of equalizer, the residual isi and maximum distortion, MSE and SER were applied. As a result of computer simulation, it was confirmed that the VSS_SE-MMA algorithm has nearly same in convergence speed and has more good performance in every performance index at the steady state.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.103-108
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• 2016

In daily life, humans get stress very often. Stress is one of the important factors of healthy life and closely related to the quality of life. Too much stress is known to cause hormone imbalance of our body, and it is observed by the brain and bio signals. Based on this, the relationship between brain signal and stress is explored, and brain signal based stress index is proposed in our work. In this study, an EEG measurement device with 32 channels is adopted. However, only two channels (FP1, FP2) are used to this study considering the applicability of the proposed method in real enveironment, and to compare it with the commercial 2 channel EEG device. Frequency domain features are power of each frequency bands, subtraction, addition, or division by each frequency bands. Features in time domain are hurst exponent, correlation dimension, lyapunov exponent, etc. Total 6 subjects are participated in this experiment with English sentence reading task given. Among several candidate features, ${\frac{{\theta}\;power}{mid\;{\beta}\;power}}$ shows the best test performance (70.8%). For future work, we will confirm the results is consistent in low price EEG device.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.19-25
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• 2008

In this study, we fabricated Organic Thin Film Transistors(OTFTs) with $C_{60}$ hole injection layer between organic semiconductor(pentacene) and metal electrode, and we compared the electrical characteristics of OTFTs with/without $C_{60}$. When the $C_{60}$ hole injection layer was introduced, the mobility and the threshold voltage were improved from 0.298 $cm^2/V{\cdot}s$ and -13.3V to 0.452 $cm^2/V{\cdot}s$ and -10.8V, and the contact resistance was also reduced. When the $C_{60}$ is inserted, the hole injection was enhanced because the $C_{60}$ prevent the unwanted chemical reaction between pentacene and Au. Furthermore, we fabricated the OTFTs using Al as their electrodes. When the OTFTs were made by only aluminum electrode, the channel were not mostly made because of the high hole injection barrier between pentacene and aluminum, but when the $C_{60}$ layer with an optimal thickness was applied between aluminum and pentacene, the device performances were obviously enhanced because of the vacuum energy level shift of Al and the consequent decrease of the hole injection barrier which was induced by the interface dipole formation between $C_{60}$ and Al. The mobility and $I_{ON}/I_{OFF}$ current ratio of OTFT with $C_{60}/Al$ electrode were 0.165 $cm^2/V{\cdot}s$ and $1.4{\times}10^4$ which were comparable with the normal Au electrode OTFT.

• Journal of the Korean Geographical Society
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• v.40 no.4 s.109
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• pp.416-427
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• 2005

This paper aims to investigate morphological changes of deltaic barrier islands in the Nakdong Estuary and especially their spatial variations after barrage construction. We analyzed shorelines, geometrical centroids, and areas to reveal the changes of barrier islands. Here, we suggest three interesting points from this study. First, each individual barrier island in the Nakdong estuary goes through a different stage of the geomorphic cycle. The frontal barrier islands such as Sinja-do and Doyo-deung grow because they are located in front of the gates of the barrage. Sediments in water out of the gates are moved to offshore and then reworked by coastal processes such as waves and tides. Second, on the contrary, Baekhap-deung located behind Doyo-deung now diminishes indicating that sediments mainly move to the frontal growing island. Third, there is no morphological change in several barrier islands far away from the main flow of the Nakdong river such as Jinwoo-do, Daema-deung, and Jangja-do. In conclusion, barrier islands in the Nakdong estuary show distinct spatial variations. As a barrier island is closer to the main channel or is in the frontal location, there happens a very dynamic change in the morphology of the island.

• Journal of Distribution Research
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• v.16 no.5
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• pp.19-41
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• 2011

Home shopping is called the flower of future distribution. Among them, for TV home shopping, Korea should lead the industry as an advanced country in IT technology. It is difficult for small and medium businesses, however. This is due to the failure of the policies of Korea Communications Commission. In order to complement such policy failure, this study intends to analyze the preceding domestic studies and foreign status, and reflect such on the policy. Especially the domestic business will be predicted through foreign home shopping status and policy cases, and the items that should be supplemented with governmental policy in order to vitalize small & medium businesses were analyzed; these should be actively reflected by the government. In case of general PP, it already runs on the registration system, and the home shopping channel should also be the same and be committed to the market. The increased number of channels would allow a greater opportunity for small and medium businesses who are the suppliers, and for the consumers, the product prices would be able to be stabilized at an appropriate cost and high quality and diversity of items could be obtained through home shopping, thus improving consumer welfare. If it is difficult to adopt the registration system for home shopping right away, the best alternative is to strengthen the approval system. As home shopping requires a re-approval every 3 years, strengthened re-approval conditions would resolve part of the problem.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.97-102
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• 2000

Subband coding is to divide the signal frequency band into a set of uncorrelated frequency bands by filtering and then to encode each of these subbands using a bit allocation rationale matched to the signal energy in that subband. The actual coding of the subband signal can be done using waveform encoding techniques such as PCM, DPCM and vector quantizer(VQ) in order to obtain higher data compression. Most researchers have focused on the error in the quantizer, but not on the overall reconstruction error and its dependence on the filter bank. This paper provides a thorough analysis of subband codecs and further development of optimum filter bank design using vector quantizer. We compute the mean squared reconstruction error(MSE) which depends on N the number of entries in each code book, k the length of each code word, and on the filter bank coefficients. We form this MSE measure in terms of the equivalent quantization model and find the optimum FIR filter coefficients for each channel in the M-band structure for a given bit rate, given filter length, and given input signal correlation model. Specific design examples are worked out for 4-tap filter in 2-band paraunitary filter bank structure. These optimum paraunitary filter coefficients are obtained by using Monte Carlo simulation. We expect that the results of this work could be contributed to study on the optimum design of subband codecs using vector quantizer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.17-22
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• 2016

For the self-adaptive equalization of higher-order QAM systems, this paper proposes a new soft decision-directed (SDD) algorithm that opens the eye patterns quickly as well as significantly reducing the error level in the steady-state when it is applied to the initial equalization stage with completely closed eye patterns. The proposed method for M-QAM application minimized the computational complexity of the existing SDD by the symbol estimated based on the two symbols closest to the observation, and greatly simplified the soft decision independently of the QAM order. Furthermore, in the symbol estimating it increased the reliability of the estimates by applying the superior properties of the sigmoid function and avoiding the erroneous estimation of the threshold function. In addition, the initialization performance was improved when an error is generated to update the equalizer, weighting the symbol decision by the threshold function to the error, resulting in an extension of the range of error fluctuations. As a result, the proposed method improves remarkably the computational complexity and the properties of initialization and convergence of the traditional SDD. Through simulations for 64-QAM and 256-QAM under multipath channel conditions with additive noise, the usefulness of the proposed methods was confirmed by comparing the performance of the proposed 2-SDD and two forms of weighted 2-SDD with CMA.

• The Korean Journal of Financial Management
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• v.24 no.3
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• pp.1-27
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• 2007

When banks prefer securities holding to lending, bank-dependent borrowers would be rationed in bank loan markets. This paper examines, both theoretically and empirically, the incentive of banks to hold securities rather than loans. When banks are in trouble due to an external shock and subsequent drain of deposit, they cannot reduce their loans quickly because loans are illiquid and are not easy to sell. Therefore, banks should respond to insured deposit drain by raising uninsured CDs or debentures. However, they cannot raise enough money through uninsured CDs or debentures when there is costly external finance premium. Meanwhile, if banks hold securities which are highly liquid, they can sell those securities and thus endure deposit drain without costly external financing. This explains why banks hold liquid securities of which yields to maturity are lower than those of loans. Banks' preference for securities comes from the existence of costly external finance premium, which is inversely related with bank net worth. After all, if bank net worth is kept high enough or capital market incompleteness is not severe, the preference for securities should be weakened.