• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7A
• /
• pp.770-777
• /
• 2007

Smaller cell size in the micro-cell or pico-cell structure brings about more frequent hand-overs between cells, and higher speed movement of the mobile terminal makes short the permissible time interval for executing these hand-over procedures. In this situation the hand-over failure may occur or some packets may be lost during the hand-over. Moreover a rapid degradation of throughput is triggered by packet re-transmission for compensating such errors. The QoS (Quality of Services) of mobile multimedia applications with higher bits rate requirements and higher speed mobility are severely affected by even shot service interruption. This paper proposes a new hand-over scheme to provide seamless services in the next generation mobile communication systems. Simulation is done to evaluate the performance of the proposed scheme based on its hand-over failure rate and packet loss rate.

• Journal of KIISE:Software and Applications
• /
• v.30 no.7_8
• /
• pp.599-609
• /
• 2003

Video abstraction is a process to pick up some important shots on a video, while the important shots might vary on the persons subjectivity. Previous works on video abstraction use only one low level feature to choose an important shot. This thesis proposes an abstraction scheme that selects a set of shots which simultaneously satisfies the desired features(or objective functions) of a good abstraction. Since the complexity of the computation to find a set of shots which maximizes the sum of object function values is $0({2^n})$, the proposed .scheme uses a simulated annealing based searching method to find the suboptimal value within a short period of time. Upon the experimental results on various videos, we could argue that the proposed abstraction scheme could produce a reasonable video abstraction. The proposed abstraction scheme used to build a digital video library.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.9
• /
• pp.8-13
• /
• 2008

Noise in homogeneous extrinsic semiconductor samples is calculated due to distributed diffusion noise sources. As the length of the device shrinks at a fixed bias voltage, the ac-wise short-circuit noise current shows excess noise as well as thermal noise spectra. This excess noise behaves like a full shot noise when the channel length becomes very small compared with the extrinsic Debye length. For the first time, the analytic formula of the excess noise in extrinsic semiconductors from velocity-fluctuation noise sources is given for finite frequencies. This formula shows the interplay between transit time, dielectric relaxation time, and velocity relaxation time in determining the terminal noise current as well as the carrier density fluctuation. As frequency increases, the power spectral density of the excess noise rolls off. This formula sheds light on noise in nanoscale MOSFETs where quasi-ballistic transport plays an important role in carrier transport and noise.

• Geophysics and Geophysical Exploration
• /
• v.6 no.1
• /
• pp.28-34
• /
• 2003

A problem of ground subsidence has been a focus of our research over the past 3 years. The purpose of this study is to investigate the disturbed stratigraphic structure by mining and to separate the possible ground subsidence area using shallow seismic reflection survey and processing. To overcome the problems such as the distortion and attenuation of seismic signal caused by ground disturbance and to acquire the high frequency data, an array with short spacing (0.3m) for both the shot and receivers, yielding near-offset (<30m) and CMP spacing of 0.15m was implemented. Data were acquired along the survey line with length of about 43m by fixed receiver array. By considering statics caused by the ground disturbance and offset distribution of data, careful processing steps such as muting and residual statics correction were applied for successful shallow reflection imaging. By correlating the ground subsidence data and stack section, possible subsidence zone could be interpreted quantitatively.

• The Journal of the Korea Contents Association
• /
• v.10 no.2
• /
• pp.146-154
• /
• 2010

Argument on the postmodernism of philosophy and history, epic and effect, and culture and art is becoming more ambiguous in scope due to digital technology development. Digital technology makes to change of aesthetic approach over the length and breadth of art and culture including medium art. Analysis of Digital images is changed from presence of images to feature analysis of images which is made by digital technology, and raise the question of how to analyze the images of reproducing digital technology focused on realism. Digital image, focused on hyper reality, should be approached not by film aesthetic approach but by shot unit. Due to emphasizes image reality reproduction by frame unit and not the short unit of the narrative approach, the artistic approach should differ from previous realism practice. Particularly, when considering movies which is focused on illusion, the realistic approach should be realized not in the of realistic approach in narrative aspect but in the aspect of realistic approach in painting aspect.

• Korean Journal of Applied Biomechanics
• /
• v.20 no.3
• /
• pp.253-259
• /
• 2010

The aim of IAAF's Biomechanics project, initially launched at the 1987 World Championships in Rome, is to support athletes and coaches in the optimization and improvement of their training and competition performance. The IAF and the IAAF supports biomechanical projects, as a service to their Member Federations, starting from the IAAF World Championships in Rome 1987. In 1997, at the IAAF World Championships of Athens. In 1995, at the IAAF World Championships in Goteborg and in co-operation with the Swedish Sport Institute of Karlstad and under the leadership of Anders Bergstrom a biomechanical research on "Throws" was conducted. In 2005, at the IAAF World Championships in Helsinki on 100m - Pole vault, High Jump, Triple Jump, Javelin, under the leadership of Prof. Paavo Komi. The IAAF published the final report in 2008 with a supplement of NSA. In 2007, at the IAAF World Championships of Osaka, in co-operation with Osaka University of Health and Sport Sciences and under the leadership of Prof. Michiyoshi Ae the IAAF received a final report on; short sprint, distance running, high jump, long jump, shot put and javelin. In 2009, at the IAAF World Championships of Berlin, in co-operation with the DLV and the leadership of Helmar Hommel (GER). The purpose of this study is to draw up a plan to perform an effective biomechanics project at 2011 IAAF World championship in Daegu.

• Journal of Korean Society of Rural Planning
• /
• v.24 no.2
• /
• pp.91-100
• /
• 2018

This study aims to identify more reasonable and efficient development plans to engage local university students in landscape improvement projects in rural areas. To survey university students, residents, administrators and experts involved in such projects on important considerations in this regard, SWOT analysis was employed to identify important factors, followed by analytic hierarchy process (AHP) to evaluate their relative importance, identify problems and suggest implications for improvement. The results are summarized as follows: the relative importance of the SWOT group was in the order of opportunity, strength, threat, and weakness. For each SWOT factor, the relative importance of strengths was in the order of students' aspiration and passion, availability of creative ideas and designs, and improved attachment to their community. The relative importance of weaknesses was in the order of the lack of spontaneous participation of residents, short preparation periods and insufficient budgets, and the lack of experience in similar projects. The relative importance of opportunities was in the order of young students' activity itself being a boost factor to the community, students' endeavors arising a consensus among residents, and students feeling a sense of duty as representatives of their school. The relative importance of threats was in the order of projects being one-shot, temporary events, immaturity, and differences in preferences between older and younger generations. To draw an overall ranking of the sub-factors evaluated, the overall relative importance of the decision-making factors was evaluated. Among the sub-factors for each SWOT group, young students' activity itself being a boost factor to the community as an opportunity factor was shown to be the most important, while the lack of experience in similar projects was shown to be the least important as administrators and experts made appropriate interventions in each stage.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.5
• /
• pp.2298-2304
• /
• 2012

X-ray fluorescence spectrum analysis method can be applied in many areas, including concentration analysis of RoHS elements and heavy metals etc. and we can get analysis results in a relatively short time. Because X-ray fluorescence spectrum has noises and several artifacts that lowers the accuracy of the analysis. This paper analyzes the characteristics of the noise of the X-ray fluorescence spectrum to increase the accuracy of analysis. X-ray fluorescence spectrum have the characteristics of shot noise (Poisson noise), so the noise size is relatively large in the small signal portion and the noise the size is relatively small in the large part of the signal. Existing methods of analysis and to remove noises is a method for general purposes algorithm. Since these algorithm does not reflect these noise characteristics, we get distorted analysis result. We can design efficient noise remove algorithm based on the accurate noise analysis method, and we expect high accuracy results of the elemental concentration analysis result.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.23 no.4
• /
• pp.388-395
• /
• 2015

The waste gate valve (WGV) for gasoline vehicles operate in a harsh high-temperature environment. Hence, WGVs are typically made of Inconel 713C, which is a type of Ni-based superalloy. Recently, the metal injection molding (MIM) process has attracted considerable attention for parts used under high-temperature conditions. In this study, an MIM analysis for the head and other parts of the WGV is conducted using a commercial CAE program Moldflow. Further, optimal manufacturing conditions are determined by analyzing flow characteristics at various injection times and locations. Moreover, to improve the accuracy of the analysis results, we compare the actual temperature of the mold during injection processing with that observed through the analysis. As the results, metal injection patterns of analysis are well in accord with these of short shot test. And the temperature variations of analysis is also very similar with those of feedstock when metal injection molding.

• Journal of Korea Foundry Society
• /
• v.31 no.5
• /
• pp.274-283
• /
• 2011

The vacuum die casting is a promising candidate of the stamping process for fabrication of fuel cell bipolar plate due to its advantages, such as precision casting, mass production and short production time. This study proposes vacuum die casting process to fabricate bipolar plates in fuel cell. Bipolar plates were fabricated under various injection conditions such as molten metal temperature and injection velocity. Also, according to injection velocity conditions, simulation results of MAGMA soft were compared to the experimental results. In case of melt temperature $650^{\circ}C$, misrun occurred. When the melt temperature was $730^{\circ}C$, mechanical properties were low due to dendrite microstructure. Injection velocity has to set at more than 2.0 m/s to fabricate the sound sample. When melt temperature, injection velocity (Fast shot), and vacuum pressure are $700^{\circ}C$, 2.5 m/s and 30 kPa respectively, sample had good formability and few casting defects. Simulation results are mostly in agreement with experimental results.