• Fisheries and Aquatic Sciences
• /
• v.1 no.2
• /
• pp.260-268
• /
• 1998

A flow pattern and water exchange in Sagami Bay is examined using a barotropic hydraulic model. In the model experiments, the volume transports of the Kuroshio Through Flow were changed with time. The results of the model experiments show that when the volume transport is increased with time, water mass and vorticity are transferred to the inner part of the bay by wakes from the western part of the bay. In the case of decrease, as the wakes are ceased, the inner cyclonic circulation water is discharged to the outside of the bay by its southward extension through the Oshima eastern channel. It is found that the water exchange by the short-term variation of volume transport in time is about 20% of all the bay water.

• ETRI Journal
• /
• v.33 no.3
• /
• pp.299-309
• /
• 2011

Energy consumption is a key issue in body sensor networks (BSNs) since energy-constrained sensors monitor the vital signs of human beings in healthcare applications. In this paper, packet size optimization for BSNs has been analyzed to improve the efficiency of energy consumption. Existing studies on packet size optimization in wireless sensor networks cannot be applied to BSNs because the different operational characteristics of nodes and the channel effects of in-body and on-body propagation cannot be captured. In this paper, automatic repeat request (ARQ), forward error correction (FEC) block codes, and FEC convolutional codes have been analyzed regarding their energy efficiency. The hop-length extension technique has been applied to improve this metric with FEC block codes. The theoretical analysis and the numerical evaluations reveal that exploiting FEC schemes improves the energy efficiency, increases the optimal payload packet size, and extends the hop length for all scenarios for in-body and on-body propagation.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.3
• /
• pp.109-115
• /
• 2009

Recently, the relay communication is focused for the power saving and coverage extension of ad-hoc networks. For the high date rate transmission, it is proposed to adapt OFDMA relays. In this paper, we assume the 2 hop cooperative OFDMA relays between the source and the destination. The performance of 3 different relaying methods are derived and compared. We noticed that the selective OFDMA relaying method has the best performance followed by opportunistic OFDMA relaying and repetition-based OFDMA relaying method under the same threshold mutual information rate.

• Proceedings of the IEEK Conference
• /
• 2003.11c
• /
• pp.297-301
• /
• 2003

The binary clipping PW/CDMA system is considered. This system can be constructed with effective cost. leading to reduce the influence of the non-linear amplifier because of converting multi-level signals into constant envelope signals. In addition, the clipping method which is to clip out signal amplitude at some level when multi-level signals are converted into constant envelope signals is used. The multi-level signals are clipped at 1 and -1 to limit the extension of bandwidth and to maintain the bandwidth after clipping. In this paper, the performance of the binary clipping PW/CDMA system with the non-linear amplifier analyzed by simulation over AWGN and flat fading channels respectively. The binary clipping PW/CDMA system with the non-linear amplifier is 2.2dB and 0.9dB better than conventional DS/CDMA system over the flat fading channels when the number of users are 9 and 17 respectively.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.9
• /
• pp.2456-2469
• /
• 1996

A digital satellite communication channel has a nonlinearity with memory due to saturation characeristis of the high poer amplifier in the satellite and transmitter/receiver linear filter used in the overall system. In this paper, we propose a complex radial basis function network(CRBFN) based adaptive equalizer for compensation of nonlinearities in digital satellite communication channels. The proposed CRBFN untilizes a complex-valued hybrid learning algorithm of k-means clustering and LMS(least mean sequare) algorithm that is an extension of Moody Darken's algorithm for real-valued data. We evaluate performance of CRBFN in terms of symbol error rates and mean squared errors nder various noise conditions for 4-PSK(phase shift keying) digital modulation schemes and compare with those of comples pth order inverse adaptive Volterra filter. The computer simulation results show that the proposed CRBFN ehibits good equalization, low computational complexity and fast learning capabilities.

• Proceedings of the IEEK Conference
• /
• 2000.07b
• /
• pp.973-976
• /
• 2000

This paper proposes a new polarization diversity scheme for OPFDM (Orthogonal Polarization and Frequency Division Multiplexing). OPFDM is an extension of OFDM (Orthogonal Frequency Division Multiplexing) in conjunction with polarization multiplexing in order to ensure the orthogonality amongst subcarriers. Since OPFDM uses two orthogonally polarized channels, it can easily employ the polarization diversity. In order to get the diversity gain effectively in a frequency selective fading channel, the proposed scheme combines the signals in subcarrier-by-subcarrier basis. The computer simulation results confirm that the proposed scheme is superior to conventional one in the two orthogonally polarized two-ray Rayleigh fading channels with cross-talk between the two channels.

• Wind and Structures
• /
• v.21 no.4
• /
• pp.425-442
• /
• 2015

This paper discusses the processing of the wind loads measured in wind tunnel tests by means of multi-channel pressure scanners, in order to compute the response of 3D structures to atmospheric turbulence in the time domain. Data compression and the resulting computational savings are still a challenge in industrial contexts due to the multiple trial configurations during the construction stages. The advantage and robustness of the bi-orthogonal decomposition (BOD) is demonstrated through an example, a sail glass of the Fondation Louis Vuitton, independently from any tentative physical interpretation of the spatio-temporal decomposition terms. We show however that the energy criterion for the BOD has to be more rigorous than commonly admitted. We find a level of 99.95 % to be necessary in order to recover the extreme values of the loads. Moreover, frequency limitations of wind tunnel experiments are sometimes encountered in passing from the scaled model to the full scale structure. These can be alleviated using a spectral extension of the temporal function terms of the BOD.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39A no.2
• /
• pp.69-76
• /
• 2014

Multiple-input and multiple-output (MIMO) technique is used in many communication fields in order to increase the channel capacity. However, this MIMO system has difficulty of miniaturization of antenna size due to the multiple RF chains Also, multiple RF chain raises some problems which increase power consumption at RF circuit and degrade the system performance due to the interference between RF chains. Because of these reasons, beamspace MIMO (BS-MIMO) technique with only single RF chain was proposed for MIMO transmission. This BS-MIMO system basically uses electronically steerable parasitic array radiator (ESPAR) antenna. Existing ESPAR antenna has a 5-element structure. So, it is possible to do only $3{\times}3$ MIMO transmission. Therefore, in order to extend BS-MIMO dimension, extension of ESPAR antenna structure is essential. In this paper, we show that BS-MIMO dimension can be increased according to the extension of structure of the ESPAR antenna, as in the conventional MIMO techniques. For example, we show that it is possible to design the $7{\times}7$ BS-MIMO transmissions with the 13-element ESPAR antenna. Also, when the number of parasitic elements of ESPAR antenna increases by two elements, MIMO dimension is expanded by 1.

• 한국가시화정보학회:학술대회논문집
• /
• 2003.11a
• /
• pp.39-42
• /
• 2003

Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modern air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras$(1280pixel\times1024pixel)$ were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

• Food Science of Animal Resources
• /
• v.25 no.3
• /
• pp.271-276
• /
• 2005

A totally 178 housewives in Gyeongnam were surveyed on consumer's purchase behavior and perception of branded pork. The degree of consumers' perception and reliance on the branded pork was still low. Consumers' consideration quality factors when buying pent is higher in order of safety/hygiene>taste/tenderness>meat color, In taste, consumer preferred Korean native pig meat when compared to the common meat. But the consumers have a notion that the price of Korean native pig meat was too expensive. The consumer preferred consumer group to government agency as a official approval organ for pork quality assurance. The consumers had different behavior in information channel, purchase frequency and place depending on age, income. In the development of branded pork, further studied are required on consumers' purchase behavior, perception, preference choice and decision-making process of branded pork.