• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.2
• /
• pp.670-683
• /
• 2016

Network coding, as a new technique to improve the throughput, is studied combined with multi-relay model in this paper to address the challenges of long distance and power limit in deep space communication. First, an amplify-and-forward relaying approach based on analog network coding (AFNC) is proposed in multi-relay network to improve the capacity for deep space communication system, where multiple relays are introduced to overcome the long distance link loss. The design of amplification coefficients is mathematically formulated as the optimization problem of maximizing SNR under sum-power constraint over relays. Then for a dual-hop relay network with a single source, the optimal amplification coefficients are derived when the multiple relays introduce non-coherent noise. Through theoretic analysis and simulation, it is shown that our approach can achieve the maximum transmission rate and perform better over single link transmission for deep space communication.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.2074-2079
• /
• 2018

Global state space's optimal policy is used for offline controller in the form of table by using Dynamic Programming. If an optimal policy table has a large amount of control data, it is difficult to use the system in a low capacity system. To resolve these problem, controller using the compressed optimal policy table is proposed in this paper. A DCT is used for compression method and the cosine function is used as a basis. The size of cosine function decreased as the frequency increased. In other words, an essential information which is used for restoration is concentrated in the low frequency band and a value of small size that belong to a high frequency band could be discarded by quantization because high frequency's information doesn't have a big effect on restoration. Therefore, memory could be largely reduced by removing the information. The compressed output is stored in memory of embedded system in offline and optimal control input which correspond to state of plant is computed by interpolation with Inverse DCT in online. To verify the performance of the proposed controller, computer simulation was accomplished with a one link inverted pendulum.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.939-944
• /
• 2007

Generally, development of a robot capable of fast movements or high payloads is progressed by the analysis of dynamic characteristics, DOF positioning, actuator selection, structure of links, and so on. This paper highlights the design of a robot manipulator handled by a human for man-machine cooperation. The requirements of the proposed system include its having multi-DOF(Degree of Freedom)and the capacity for a high payload in the condition of its maximum reach. The primary investigation factors are motion range, performance within the motion area, and reliabilityduring the handling of heavy materials. Traditionally, the mechanical design of robots has been viewed as a problem of packaging motors and electronics into a reasonable structure. This process usually transpires with heavy reliance of designerexperience. Not surprisingly, the traditional design process contains no formally defined rules for achieving desirable results, as there is little opportunity for quantitative feedback during the formative stages. This work primarily focuses on the selection of proper joint types and link lengths, considering a specific task type and motion requirements of the heavy material handling.

• Journal of Ocean Engineering and Technology
• /
• v.27 no.2
• /
• pp.100-106
• /
• 2013

This paper deals with the design method for a small waterproof 4-axis robot arm. An extensive analysis was performed on the torque applied to the robot joint as a result of the payload, as well as the design of the joint actuator capacity. In addition, a study was undertaken on the design of a waterproof joint actuator that works at depths greater than 10 m and the wiring design for a small waterproof connector to avoid obstructing the robot motion. Finally, a finite element method simulation was carried out to analyze the strength of the designed robot arm link, and its stability was verified through a simulation test.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.3
• /
• pp.131-137
• /
• 2017

In order to safely protect high over current flowing into the main circuit at short-circuit without any explosion or fire, the enclosed cartridge fuse with a high interrupting capacity should be applied. But this fuse is impossible to be applied to an inner electronic circuit because of a limited space problem result from the miniaturization trend of products. Therefore, it is necessary to apply a sub-miniature fuse with a relatively small size. However the semi-enclosed fuse which is more free for an influx of air than the enclosed cartridge fuse and is possible to protect fuse elements with chemical and physical combination can be adoptable. But it has a limit of implementing the characteristic of a high breaking capacity. For these reasons, the Fe-42wt％Ni fuse elements alloy and fuse-link with less space were designed to increase a breaking capacity of sub-miniature fuse and its safety for fire and explosion was confirmed in this paper.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.9A
• /
• pp.2153-2164
• /
• 1998

This paper has presented the parameters for the coexistence between two systems in macro/microcell ovelaid W-CDMA WLL (wideband CDMA wireless local loop) and has calculated the capacity of forward/reverse link in microcell. To produce the capacity for analyzing system interference effects, we have shown tables and graphs with the parameters sucyh as RF channel bandwidth of WLL(W), the transmission rate of service message(R), the required signal power to noise power ratio( $E_{b/}$ $N_{0}$) for achieving accepatable error rate, te user number ( $N_{W1}$, $N_{W2}$) of the neighboring system, the signal power to interference power ratio(.GAMMA.$_{C1B}$, .GAMMA.$_{C2B}$) of the neighboring system, the normalized distance(d) between microcell and macrocell base-station, and microcell to macrocell radius ratio ( $R_{d}$). From the results, we have convinced that the capacity of microcell diminishes as increasing the user number ( $N_{W2}$) in macrocell, increasing the microcell radius, and decreasing the normalized distance(d) between microcell and macrocell base-station. Especially, we have known that when $R_{d}$=0.1, $N_{W2}$ must be below 24 at .GAMMA.$_{C2B}$ = 0 dB and below 8 at .GAMMA.$_{C2B}$ = 4 dB for the acceptable capacity raito to be over 80%. Therfore, this paper is usefult to design microcell W-CDMA WLL for accommodating more user number under the interference effects of macrocell W-CDMA WLL and is expected to be reference in power control if base-station.ation.ion.ation.ation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.5
• /
• pp.644-650
• /
• 2018

According to a miniaturization and integration of electric device, a little size of fuse satisfying the current carrying capacity as well as an explosive tolerance and current interrupt rating are required. Fe-Ni alloy is applied to decrease an oxidation of fuse elements. A resistance and T.C.R(temperature coefficient of resistance) of a fuse are analyzed by changing a content of Ni And full rated current I-T curve from 1A to 6.3A has been tested. In order to an explosive energy, a straight wire type is selected to reduce a fuse melting time. An interrupt rating test was conducted by changing a content of Ni and the optimal content of Ni is to be 40%.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.7
• /
• pp.2365-2382
• /
• 2014

While single-user spatial multiplexing multiple-input multiple-output (SU-MIMO) allows spatially multiplexed data streams to be transmitted to one node at a time, multi-user spatial multiplexing MIMO (MU-MIMO) enables the simultaneous transmission to multiple nodes. However, if the transmission time required to send packets to each node varies considerably, MU-MIMO may fail to utilize the available MIMO capacity to its full potential. The transmission time typically depends upon two factors: the link quality of the selected channel and the data length (packet size). To utilize the cumulative capacity of multiple channels in MIMO applications, the assignment of channels to each node should be controlled according to the measured channel quality or the transmission queue status of the node.A MAC protocol design that can switch between MU-MIMO and multiple SU-MIMO transmissions by considering the channel quality and queue status information prior to the actual data transmission (i.e., by exchanging control packets between transmitter and receiver pairs) could address such issues in a simple but in attractive way. In this study, we propose a new MAC protocol that is capable of performing such switching and thereby improve the system performance of very high throughput WLANs. The detailed performance analysis demonstrates that greater benefits can be obtained using the proposed scheme, as compared to conventional MU-MIMO transmission schemes.

• ETRI Journal
• /
• v.34 no.3
• /
• pp.352-360
• /
• 2012

This paper proposes a low-cost, low-power, and high-capacity optical-electrical-optical-type reach extender that can provide 3R frame regeneration and remote management to increase the reach and split ratio with no change to a legacy time division multiple access passive optical network. To provide remote management, the extender gathers information regarding optical transceivers and link status per port and then transmits to a service provider using a simple network management protocol agent. The extender can also apply to an Ethernet passive optical network (E-PON) or a gigabit-capable PON (G-PON) by remote control. In a G-PON, in particular, it can provide burst mode signal retiming and burst-to-continuous mode conversion at the upstream path through a G-PON transmission convergence frame adaptor. Our proposed reach extender is based on the quad-port architecture for cost-effective design and can accommodate both the physical reach of 60 km and the 512 split ratios in a G-PON and the physical reach of 80 km and the 256 split ratios in an E-PON.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.6
• /
• pp.2949-2963
• /
• 2019

A novel distributed compress-and-forward (CF) system based on multi-relay network is presented. In this system, as the direct link between the source and destination is invalid due to some reasons, such as the limited power, special working environment, or even economic factors, relays are employed to receive analog signals and carry on distributed compressed encoding. Subsequently, the digital signals are transmitted to the destination via wireless channel. Moreover, a theoretical analysis for the system is provided by utilizing the Chief Executive Officer (CEO) theory and Shannon channel capacity theory, and the rate-distortion function as well as the connection between the transmission rate and the channel capacity are constructed. In addition, an optimal signal-to-noise ratio (SNR) -based power allocation method is proposed to maximize the quantization SNR under the limited total power. Simulation result shows that the proposed CF system outperforms the amplify-and-forward (AF) system versus the SNR performance.