• Science of Emotion and Sensibility
• /
• v.12 no.3
• /
• pp.341-350
• /
• 2009

Archer's capability of attention and relaxation control during shooting process was evaluated using EEG technology. Attention and meditation algorithms were used to represent the levels of mental concentration and relaxation levels. Elite, mid-level, and novice archers were tested for short and long distance shootings in the archery field. Single channel EEG was recorded on the forehead (Fp1) during the shooting process, and attention and meditation levels were computed by real time. Four types of variations were defined based on the increasing and decreasing patterns of attention and meditation levels during shooting process. Elite archers showed increases in both attention and relaxation while mid-level archers showed increased attention but decreased relaxation. Elite archers also showed higher levels of attention at the release than mid-level and novice archers. Levels of attention and relaxation and their variation patterns were useful to categorize archers and to provide feedback in training.

• Clean Technology
• /
• v.19 no.1
• /
• pp.1-7
• /
• 2013

In this study, the effects of spacer and variation of spacer height in reverse electrodialysis (RED) on the seawater and ion transport were investigated. A three-dimensional computational fluid dynamics (CFD) simulation for a hexagonal spacer was constructed. The results showed that the swirl in the channel and ion transport rate to the membrane were enhanced at higher Reynolds number, on the other hand, pressure difference between the inlet and outlet was increased. Moreover thicker spacer increased Power number and Sherwood number.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.5A
• /
• pp.433-440
• /
• 2007

In this paper, we have proposed WiBro receiver structure employing joint adaptive antenna scheme at the base station (BS) and the mobile station (MS) and evaluated its performance. In WiBro system, the joint use of transmit beamforming at BS and receive beamforming at MS can improve the SINR significantly and increase the capacity compared to the conventional system. Moreover, power allocation level can be decreased because channel variation can be reduced by using the jointly updated weight. However, it needsthe calculation of the antenna weights in every subcarrier for performance improvement. This could imply an enormous computational burden. However, the computational complexity can be reduced significantly by using the same set of the antenna weights for the adjacent subcarriers instead of calculating antenna weights for every subcarrier. We have analyzed the impact of subcarrier grouping for weight calculation on the system performance.

• Korean Journal of Optics and Photonics
• /
• v.19 no.3
• /
• pp.193-198
• /
• 2008

A novel refractive index sensor, which consists of polymer channel waveguide overlaid with $TiO_2$ thin film, is demonstrated. To evaluate the fabricated sensor, we measured the polarimetric interference induced by concentration change of injected glycerol solution. Our experimental results show that thicker $TiO_2$ film improves the sensitivity of the polarimetric interferometer. For the fabricated waveguide with a 20 nm thick $TiO_2$ film, the measured index change to lead phase variation of $2{\pi}$ is $1.8{\times}10^{-3}$.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.6
• /
• pp.15-20
• /
• 2016

In this paper, we consider selective mapping (SLM) based OFDM systems without side information, where SLM is one of the promising peak-to-average power ratio (PAPR) reduction techniques due to its simplicity and no distortion in the transmitted signal. First, we construct a new phase sequence where a part of phase sequence is replaced by an orthogonal sequence. Based on the proposed phase sequence, we propose a new scheme for detecting coherently the index of the phase sequence used in transmitter without side information. Computer simulation shows that the proposed detection scheme performs well in SLM-based OFDM systems, and specifically outperforms the existing ones when channel variation is relatively small between sub-carriers used in phase sequence detection.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.14 no.4
• /
• pp.249-256
• /
• 2011

Lagrangian particle transport model coupled with the EFDC have been performed to estimate the residence time and water exchange rate by release time of pollutants over a tidal cycle in Masan Bay. The modelled residence time for the whole bay was about 40 days, ranging from less than 20 days in the southern parts of Budo, to over 100 days in the upper parts of Somodo. The spatial difference of residence time was controlled by tidal residual currents and the distance to the bay channel. The area mean residence time during spring and neap tides was estimated to be about 36 days and 42 days, respectively. The time required for 30% exchange of water was calculated as ranging from 65 to 105 days by release time of pollutants.

• Journal of Navigation and Port Research
• /
• v.34 no.5
• /
• pp.331-336
• /
• 2010

The free surface influenced the wake behind a circular cylinder and its effects were investigated experimentally in a circulating water channel with the variation of water depth. Instantaneous velocity fields were measured in this paper. The measured results has been compared with each other to investigate the flow characteristics of the circular cylinder's 2-dimensional section at $Re=1.0{\times}10^3$ using 2-frame grey level cross correlation PIV method. The flow around the circular cylinder with free surface affected the wake structure. Especially, in case of d=1.0D, the boundary layer was measured in the whole area. The separation point and boundary layer of the circular cylinder could be controlled by the water depth.

• The Journal of the Acoustical Society of Korea
• /
• v.33 no.4
• /
• pp.255-261
• /
• 2014

This paper presents an underwater acoustic communication with nonlinear chirp modulation. The information is carried by the carrier amplitude, frequency or phase in the most common underwater acoustic communications. However, the proposed method includes the information within frequency variation of carrier wave for a symbol. Especially, as carrier wave the hyperbolic frequency modulated signal, one of the nonlinear chirp signal, is used and it is robust in the Doppler channel. The proposed method was analyzed and compared to conventional method by simulation. When the doppler shift existed, the error probability of the proposed method is reduced by 5~12 % than conventional method with linear frequency modulated signal. Sea trial was performed to analyze the performance of the proposed method.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.6
• /
• pp.1229-1236
• /
• 2015

In this study, flow characteristics and bed changes during a short term flood event were analyzed using the two-dimensional CCHE2D model for a meandering sand-bed river, the Naesung Stream. Flow and bed change simulation was carried along the three sub-reaches with sinuosity of 1.2, 1.6 and 2.2 for the 6-day flood event occurring in June 2011. The simulation results indicated that velocity variation due to flow concentration was larger along the sub-reach with the sinuosity less than 1.5 and bed erosion at the outside of the bend was increased by time. In the sub-reach with the sinuosity less than 1.5, the maximum flood discharge produced the maximum flow velocity over 1.6 m/s to 2 m/s locally.

• Journal of the Korean Society of Visualization
• /
• v.5 no.1
• /
• pp.9-11
• /
• 2007

We introduce an in vivo imaging flow cytometer, which provides fluorescence images simultaneously with quantitative information on the cell population of interest in a live animal. As fluorescent cells pass through the slit of light focused across a blood vessel, the excited fluorescence is confocally detected. This cell signal triggers a strobe beam and a high sensitivity CCD camera that captures a snap-shot image of the cell as it moves down-stream from the slit. We demonstrate that the majority of signal peaks detected in the in vivo flow cytometer arise from individual cells. The instrument's capability to image circulating T cells and measure their speed in the blood vessel in real time in vivo is demonstrated. The cell signal irradiance variation, clustering percentage, and potential applications in biology and medicine are discussed.