• Journal of the Korean Society for Nondestructive Testing
• /
• v.26 no.5
• /
• pp.306-314
• /
• 2006

Instrumented indentation technique is a new way to evaluate nondestructive such mechanical properties as flow properties, residual stress and fracture toughness by analyzing indentation load-depth curves. This study evaluated quantitatively the flow properties of steels and residual stress of weldments. First, flow properties can be evaluated by defining a representative stress and strain from analysis of deformation behavior beneath the rigid spherical indenter and the parameters obtained from instrumented indentation tests. For estimating residual stress, the deviatoric-stress part of the residual stress affects the indentation load-depth curve, so that by analyzing the difference between the residual-stress-induced indentation curve and residual-stress-free curve, the quantitative residual stress of the target region can be evaluated. The algorithm for flow property evaluation was verified by comparison with uniaxial tensile test and the residual stress evaluation model was compared to mechanical cutting and ED-XRD results.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.5
• /
• pp.109-119
• /
• 2017

In the present study, to determine walking imbalance using the walking analysis method, where limitations in the existing walking analysis have been minimized, we propose a new walking analysis method that adopts the following: self-developed equipment to measure the angles of left-right hip joints and knee joints; a determination system using symmetry index (SI); and dynamic time warping (DTW) similarity analysis algorithm to analyze individual walking styles. Normal and imbalanced walking tests were conducted for 12 subjects without walking disorder. From the SI calculation to determine imbalanced walking, both the normal and imbalanced walking styles can be determined using the angle measurements of the left-right hip joints and knee joints. In the analysis of the individual walking styles, the similarities at the center of the lower back, left-right thighs, and dorsum of the feet of the 12 subjects in both normal and imbalanced walking cases were compared. From the similarity analysis of the measured values during the normal and imbalanced walking tests, I determined that the walking pattern does not maintain the same stance when the body parts move during walking.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.6
• /
• pp.107-118
• /
• 2011

This paper shows a u-Health management system in user's Life environment, which is different from previous ones by enterprises. It's designed for users(citizens) and service provider(especially providing medical service). This paper is discussing on the proof on the service model being operated near the Tancheon stream in the city of Sung-nam. To maximize users' satisfaction, this service has been designed on four disciplines(so easy, so simple, well-customized, funny feedback) in the viewpoint for users. Its algorithm has 4 levels which are measurement, prescription, monitoring and feedback. In the system. there are HCBs(health check boothes) checking out status and assessment of users, customized health prescription customized a health management service prescription engine, exercise programs customized on exercise equipments near the stream and monitoring system.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.3 s.345
• /
• pp.84-94
• /
• 2006

In this paper, we propose the algorithm to reduce guard time of UWB MAC time slot for throughput gain. In the proposed draft by multiband ofdm alliance (MBOA), Guard time of each medium access slot (MAS) is composed of shortest inter-frame space (SIFS) and MaxDrift which is the time caused by maximum frequency offset among devices. In this paper, to reduceguard time means that we nearly eliminate MaxDrift term from guard time. Each device of a piconet computes relative frequency offset from the device initiating piconet using periodically consecutive transferred beacon frames. Each device add or subtract the calculated relative frequency offset to the estimated each MAS starting point in order to synchronize with calculated MAS starting point of the device initiating piconet. According to verification of simulations, if the frequency offset estimator is implemented with 8 decimal bit, the ratio of the wasted time to Superframe is always less than 0.0001.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.3 s.345
• /
• pp.1-9
• /
• 2006

In this paper, we propose a MIMO-OFDMA (Multi Input Multi Output-Orthogonal Frequency Division Multiple Access) system based on beamforming for performance improvement of downlink real-time traffic transmission in harsh channel conditions with low CIR (Carrier-to-Interference Ratio). In the proposed system, we first consider the M-GTA-SBA (Modified-Grouped Transmit Antenna-Simple Bit Allocation) using effective CSI (Channel State Information) calculation procedure based on spatial resource grouping, which is adequate for the combination of MRT (Maximum Ratio Transmission) in the transmitter and MRC (Maximum Ratio Combining) in the receiver. In addition, to reduce feedback information for the beamforming, we also apply QEGT (Quantized Equal Gain Transmission) based on quantization of amplitudes and phases of beam weights. Furthermore, considering multi-user environments, we propose the P-SRA (Proposed-Simple Resource Allocation) algorithm for fair and efficient resource allocation. Simulation results reveal that the proposed MIMO-OFDMA system achieves significant improvement of spectral efficiency in low CRI region as compared to a typical open-loop MIMO-OFDMA system using pseudo-orthogonal space time block code and H-ARQ IR (Hybrid-Automatic Repeat Request Incremental Redundancy).

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.47 no.1
• /
• pp.15-21
• /
• 2010

This paper proposes the multimedia fingerprinting code insertion algorithm when video content is distributed in P2P environment, and designs the collusion codebook SRP(Small RISC Processor) embedded system for the collusion attack prevention. In the implemented system, it is detecting the fingerprinting code inserted in the video content of the client user in which it requests an upload to the web server and in which if it is certified content then transmitted to the streaming server then the implemented system allowed to distribute in P2P network. On the contrary, if it detects the collusion code, than the implemented system blocks to transmit the video content to the streaming server and discontinues to distribute in P2P network. And also it traces the colluders who generate the collusion code and participates in the collusion attack. The collusion code of the averaging attack is generated with 10% of BIBD code v. Based on the generated collusion code, the codebook is designed. As a result, when the insert quantity of the fingerprinting code is 0.15% upper in bitplane 0~3 of the Y(luminance) element of I-frame at the video compression of ASF for a streaming service and MP4 for an offline offer of video content, the correlation coefficient of the inserted original code and the detected code is above 0.15. At the correlation coefficient is above 0.1 then the detection ratio of the collusion code is 38%, and is above 0.2 then the trace ratio of the colluder is 20%.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.2
• /
• pp.64-70
• /
• 2011

Portable artificial electronic nose (E-nose) system suffers from noisy fluctuation in surroundings such as temperature, vapor concentration, and gas flow, because its measuring condition is not controled precisely as in the laboratory. It is important to develop a simple and robust vapor recognition technique applicable to this uncontrolled measurement, especially for the portable measuring and diagnostic system which are expanding its area with the improvements in micro bio sensor technology. This study used a PDA-based portable E-nose to collect the uncontrolled vapor measurement signals, and applied the image matching algorithm developed in the previous study on the measured signal to verify its robustness and improved accuracy in portable vapor recognition. The results showed not only its consistent performance under noisy fluctuation in the portable measurement signal, but also an advanced recognition accuracy for 2 similar vapor species which have been hard to discriminate with the conventional maximum sensitivity feature extraction method. The proposed method can be easily applied to the data processing of the ubiquitous sensor network (USN) which are usually exposed to various operating conditions. Furthermore, it will greatly help to realize portable medical diagnostic and environment monitoring system with its robust performance and high accuracy.

• 전자공학회논문지 IE
• /
• v.46 no.4
• /
• pp.57-65
• /
• 2009

This paper presents the image contrast enhancement technique suitable for local dimming backlight of small-sized mobile display while achieving the reduction of the power consumption. In addition to the large-sized TFT-LCD, small-sized one has adopted LED for backlight. Since, conventionally, LED was mounted on the side edge of a display panel, global dimming method has been widely used. However, recently, new advanced method of local dimming by placing the LED to the backside of the display panel and it raised the necessity of sub-blocked processing after partitioning the target image. When the sub-blocked image has low brightness, the supply current of a backlight LED is reduced, which gives both enhancement of contrast ratio and power consumption reduction. In this paper, we propose simple and improved image enhancement algorithm suitable for the small-sized mobile display. After partitioning the input image by equal sized blocks and analyzing the pixel information in each block, we realize the primary contrast enhancement by independently processing the sub-blocks using the information such as histogram, mean, and standard deviation values of luminance(Y) component. And then resulting information is transferred to each backlight control unit for local dimming to realize the secondary contrast enhancement as well as reduction of power consumption.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.9
• /
• pp.131-143
• /
• 2011

Previous alerting service based on LBS was caused severe overload problem of server by using the method to confirm the location of each moving object on server. In this paper, by loading an App on smart moving object, we proposed a novel algorithm named ADAS(Active Disaster Alert Service) for accessing to the server site with oneself location information as needed and implemented the disaster alerting service system with visualization for user. In the proposed method, running App access to the server periodically with the present location coordinate gained from GPS module or network module and the ID of moving object. Then, the server compare the present location coordinate of moving object and the coordinates of disasters registered in DIDB and transmit the n NDIs existed in near distance orderly from the coordinate of present moving object to the client. The App compares the coordinate of present location for moving object and the coordinates of NDI is transmitted from server by real time and executes the service with classifying levels of alert into three steps such as danger, carefulness and safety. And new NDIs are gained by accessing DIDB on Server periodically during running App. Therefore, this will be become a novel method for reducing fundamentally the server overload problem in comparison with previous alerting service that the career of moving object is managed on server.

• Journal of Korea Port Economic Association
• /
• v.36 no.1
• /
• pp.41-58
• /
• 2020

This study aims to investigate the technical efficiency of major container ports in the Bay of Bengal area and to study how certain factors influence the efficiency of container ports and terminals. The research is conducted on the four main container ports in the Bay of Bengal area, namely, Colombo Port in Sri Lanka, Chennai Port in India, Chittagong Port in Bangladesh, and Yangon Port in Myanmar. There are three input variables (quay length, storage area, and the number of cranes) and two output variables (throughput twenty-foot equivalent units and vessel calls) chosen for the process in this study. This paper evaluates the efficiency score of the defined variables and suggests implications for further improvement of the core competitiveness of the four selected ports. The findings indicate that Colombo Port is the most efficient on a technical scale, followed by Chennai Port, Yangon Port, and Chittagong Port. However, the slack and radial movement calculation results show that the inputs and outputs of the four ports need to be adjusted to be efficient and to reduce the amount of resources that are wasted. The results validate the adaptability of the improved data envelopment analysis algorithm in port efficiency analysis. The research findings provide an overview of the efficiencies of the selected container ports and can potentially affect the port management decisions made by policymakers, terminal operators, and carriers.