• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.753-757
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• 2015

This paper introduces an experimental rescue robot, HUBO T-100 and presents the optimal motion control method. The objective of the rescue robot is to extract patients or wounded soldiers in the battlefield and hazardous environments. Another mission is to dispose and transport an explosive ordnance to safe places. To execute these missions, the upper body of the rescue robot is humanoid in form to execute various kinds of tasks. The lower body features a hybrid tracked/legged design, which allows for a variety of mode of locomotion, depending on terrain conditions in order to increase traversability. The weight lifting motion is one of the most important task for performing rescue related missions because the robot must lift an object or impaired person lying on the ground for transferring. Here, dynamics based motion optimization is employed to minimize joint torques while maintaining stability simultaneously. Physical experiments with a real humanoid robot, HUBO T-100, are presented to verify the proposed method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.1-6
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• 2017

Due to the recent advances in IoT technologies, reducing power consumption in battery-based IoT devices becomes an important issue. An IoT device is a kind of real-time systems, and processor voltage scaling is known to be effective in reducing power consumption. However, recent research has shown that power consumption in memory increases dramatically in such systems. This paper aims at combining processor voltage scaling and low-power NVRAM technologies to reduce power consumption further. Our main idea is that if a task is schedulable in a lower voltage mode of a processor, we can expect that the task will still be schedulable even on slow NVRAM memory. We incorporate the NVRAM memory allocation problem into processor voltage scaling, and evaluate the effectiveness of the combined approach.

• ETRI Journal
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• v.38 no.5
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• pp.981-987
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• 2016

We present a cost-effective dual polarization quadrature phase-shift coherent receiver module using a silica planar lightwave circuit (PLC) hybrid assembly. Two polarization beam splitters and two $90^{\circ}$ optical hybrids are monolithically integrated in one silica PLC chip with an index contrast of $2%-{\Delta}$. Two four-channel spot-size converter integrated waveguide-photodetector (PD) arrays are bonded on PD carriers for transverse-electric/transverse-magnetic polarization, and butt-coupled to a polished facet of the PLC using a simple chip-to-chip bonding method. Instead of a ceramic sub-mount, a low-cost printed circuit board is applied in the module. A stepped CuW block is used to dissipate the heat generated from trans-impedance amplifiers and to vertically align RF transmission lines. The fabricated coherent receiver shows a 3-dB bandwidth of 26 GHz and a common mode rejection ratio of 16 dB at 22 GHz for a local oscillator optical input. A bit error rate of $8.3{\times}10^{-11}$ is achieved at a 112-Gbps back-to-back transmission with off-line digital signal processing.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.37-44
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• 2005

This paper proposes a hybrid scheme for dynamic bandwidth allocation(DBA) in Ethernet passive optical network(EPON), which combines advantages of adaptive cycle and constant cycle-based schemes. The proposed scheme is based on IPACT scheme, but it operates as adaptive cycle or constant cycle mode according to the queue status of optical line terminal(OLT) for downstream transmission. Simulation results showed that the proposed scheme could achieve a similar throughput in downstream transmission to a constant cycle-based DBA scheme, while producing a similar delay performance to the IPACT scheme in upstream transmission.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.6
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• pp.637-645
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• 2014

This paper presents a new $4{\times}4$ multi-port amplifier(MPA) structure using reconfigurable switching matrices as input and output hybrid matrices(IHM, OHM), and phase/amplitude error calibration circuits. According to the mode selection of the switches, output power can be flexibly and effectively managed since the number of PA's to be used and the number of output port to distribute/combine amplified signals can be controlled. In addition, the proposed structure contains the phase and amplitude error calibration block that helps produce identical amplitudes and desired phase differences to the $4{\times}4$ OHM, resulting in optimizing the port-to-port isolation of the MPA system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.3
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• pp.453-460
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• 2014

Fault injection attack is the process of attempting to acquire the information on-chip through inject artificially generated error code into the cryptographic algorithms operation (or perform) which is implemented in hardware or software. From the details above, the laser-assisted failure injection attacks have been proven particularly successful. In this paper, we propose an improved laser probing system for fault injection attack which is called the Dual-Laser FA tool set, a hybrid approach of the Flash-pumping laser and fiber laser. The main concept of the idea is to improve the laser probe through utilizing existing equipment. The proposed laser probe can be divided into two parts, which are Laser-I for laser cutting, and Laser-II for fault injection. We study the advantages of existing equipment, and consider the significant parameters such as energy, repetition rate, wavelength, etc. In this approach, it solves the high energy problem caused by flash-pumping laser in higher repetition frequency from the fiber laser.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.586-594
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• 2009

This paper is the study on random, sinusoidal and shock vibration responses for the STSAT-3(science and technology satellite-3) proto-model which is the first small size all-composite satellite in Korea. The structure system of the STSAT-3 forms box type structure by joining several hybrid sandwich panels comprised of honeycomb core and carbon fiber reinforced laminated composite skins on both side. Mode shape, stress, displacement and acceleration responses are obtained on both the frequency domain and time domain by means of a commercial FEA software MSC/NASTRAN. From these analysis results, failure, safety factor and design validity are assessed. These results can be successfully applicable as reference data when a new satellite is developed as well as giving out an excellent criteria in satellite vibration treatment design.

• Journal of KIISE:Information Networking
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• v.36 no.3
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• pp.222-230
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• 2009

A sensor network is an important element of the ubiquitous and it consists of sensor fields that contain sensor nodes and sink nodes that collect data from sensor nodes. Since each sensor node has limited resources, one of the important issues covered in the past sensor network studies has been maximizing the usage of limited energy to extend network lifetime. However, most studies have only considered fixed sink nodes, which created various problems for cases with multiple mobile sink nodes. Accordingly, while maintaining routes to mobile sink nodes, this study aims to deploy the hybrid communication mode that combines single and multi-hop modes for intra-cluster and inter-cluster transmission to resolve the problem of failed data transmission to mobile sink nodes caused by disconnected routes. Furthermore, a 2-level hierarchical routing protocol was used to reduce the number of sensor nodes participating in data transmission, and cross-shape trajectory forwarding was employed in packet transmission to provide an efficient data dissemination method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.193-203
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• 2014

Temperature-dependent stress analysis and heat transfer analysis of a rotating gas turbine blade made of functionally graded materials (FGMs) are presented considering turbine operating temperature and ceramic particle size. The material properties of functionally graded materials are assumed to vary continuously and smoothly across the thickness of the thin-walled blade. For obtaining system stiffness reflecting these characteristics, the one-dimensional heat transfer equation is applied along the thickness of the thin-walled blade for determining the temperature distribution. Using the results of the temperature analysis, the equations of motion of a rotating blade are derived with hybrid deformation variable modeling method along with the Rayleigh-Ritz assumed mode methods. The validity of the derived rotating blade model is evaluated by comparing its transient responses and temperature distribution with the results obtained using a commercial finite element code. The maximum tensile stress with operating speed and gradient index are obtained. Furthermore, the gradient index that minimizes blade temperature was investigated.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.11
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• pp.409-418
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• 2014

The amount of data located in storage servers has dramatically increased with the growth in cloud and social networking services. Storage systems with very large capacities may suffer from poor reliability and long latency, problems which can be addressed by the use of a hybrid disk, in which mechanical and flash memory storage are combined. The Linux-based SSD(solid-state disk) uses a caching technique based on the DM-cache utility. We assess the limitations of DM-cache by evaluating its performance in diverse environments, and identify problems with the caching policy that it operates in response to various commands. This policy is effective in reducing latency when Linux is running in native mode; but when Linux is installed as a guest operating systems on a virtual machine, the overhead incurred by caching actually reduces performance.