• Journal of information and communication convergence engineering
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• v.2 no.2
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• pp.67-70
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• 2004

In this paper, we propose two novel high-rate high-performance space-time codes for multiple-input multiple-output (MIMO) systems. When $n_T$ transmit antennas and When $n_R$ ＝ When $n_T$ receive antennas are deployed, the two proposed codes respectively offer transmission rates of (When $n_T$ -1) and (When $n_T$ -2) symbols per channel use and diversity orders of 3 and 5. As a consequence, our proposed codes allow the MIMO systems to employ a simple detection technique based on QR decomposition. Moreover, for equal or even higher spectral efficiencies, our proposed codes always provide much better bit error rate (BER) performances than V-BLAST architecture does when When $n_R$ ＝ When $n_T$. Computer simulation is given to verify performances of our proposed codes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.114-120
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• 2005

High speed milling experiment on the hardened mold steel (CALMAX at hardness of HRc 55) is carried out using small diameter ball endmill. Tool lift and wear characteristics under the various machining parameters are investigated. Effect of dynamic runout on the wear of the tool is also studied. For most of the cases, catastrophic chipping of tool edge is not observed and uniformly distributed wear on the flank surface of the tool is obtained. It is found that lower rate of tool wear is obtained as the cutting speed is increased. Also, high pick feed rate is found to be more favorable in terms of tool wear and material removal rate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.473-476
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• 2008

In this paper, we designed the main mechanism of high throughput device for rod-cuts of spent fuel. For this, we analyzed the mechanical methods(slitting, ball mill, roller straightening) and chemical methods(muffle furnace, rotary kiln). As the results, methods of ball drop and rotary drum for concepts design were selected in the analysis step. For enhancement of oxidation rate, we devised the blades on the reactor with mesh type. Also, for enhancement of decladding rate, we designed ball size and rotation reactor with mesh type and devised the vacuum system for fission products. Mechanisms of oxidation and recovery can simultaneously handle the rod-cuts of spent fuel and independently recover. The results of mechanism design can be used for scale-up of high throughput device.

• Journal of Broadcast Engineering
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• v.25 no.7
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• pp.1073-1080
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• 2020

360-degree video streaming technologies have been widely developed to provide immersive virtual reality (VR) experiences. However, high computational power and bandwidth are required to transmit and render high-quality 360-degree video through a head-mounted display (HMD). One way to overcome this problem is by transmitting high-quality viewport areas. This paper therefore proposes a motion-constrained tile set (MCTS)-based tile extractor for versatile video coding (VVC). The proposed extractor extracts high-quality viewport tiles, which are simulcasted with low-quality whole video to respond to unexpected movements by the user. The experimental results demonstrate a savings of 24.81% in the bjøntegaard delta rate (BD-rate) saving for the luma peak signal-to-noise ratio (PSNR) compared to the rate obtained using a VVC anchor without tiled streaming.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.9
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• pp.1241-1244
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• 2020

In this paper, we consider a downlink non-orthogonal multiple access system with a base station and N mobile stations, where we assume that instantaneous channel state information (CSI) is available at the base station. A power allocation scheme is proposed to achieve perfect fairness, which means equal data rates for all mobile stations. However, the power allocation scheme using full CSI requires high complexity. Hence, a simple power allocation scheme with low complexity is proposed by using high signal-to-noise power ratio (SNR) approximation. The simple power allocation scheme can achieve perfect fairness only for high SNR. However, it needs only the best CSI and the simple procedure to obtain power allocation coefficients. From simulation results, we show that the simple power allocation scheme provides remarkable fairness performance at high SNR.

• Journal of Environmental Science International
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• v.31 no.8
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• pp.707-713
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• 2022

This study aimed to comprehensively analyze the usage characteristics of children's parks according to location in Gangneung-si. Weekday and weekend, gender, time of stay, and usage behavior according to age group were analyzed and a video analysis of unmanned camera data for park management was conducted. On the average, the use of children's parks during spring and autumn was more than twice that during summer, and the use rate of children's parks located in old central districts by elderly people was relatively higher than the use rate of those located in housing development district. Overall, the usage ratio (24.6%) by elderly people was high, and their usage ratio (31.3%) in the morning period from dawn was significantly high. Among the usage behaviors, the rate at which dogs walk was analyzed to be somewhat high. As the usage ratio by elderly people is high with diverse usage behavior, it is necessary to provide complex functions to children's parks in the future.

• Women's Health Nursing
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• v.19 no.1
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• pp.36-47
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• 2013

Purpose: This study was to explore subjectivity on childbearing in high school students. Methods: A Q-methodology which provides a method of analyzing the subjectivity of each type was used. Forty-three high school students classified 40 selected Q-statements into 9 points standard. The obtained data were analyzed by using the pc-QUANL program. Results: High school students' subjectivity on childbearing were analyzed into two types: Type 1 turned out to be 'FOLS (family oriented life style)' and Type 2 'CINK (couple important no kid)'. Conclusion: In order to resolve such problems as low birth rate and the advanced age of the population, effective youth and adult programs, policy and institution are required. The current demographic, economic and other factors such as personal values and policies may lower birth rate. In particular, youths' need for children and birth rate tend to be lower. There are positive and negative patterns in high school students' subjectivity on childbearing. Thus, national and social efforts are needed to change negative factors into positive ones. In order to maintain positive subjectivity on childbearing in high school students, it is necessary to apply family-centered educational programs and to implement birth-friendly and realistic programs for promoting child birth.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.849-853
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• 2002

A specific experimental method, the split Hopkinson pressure bar (SHPB) technique has been widely used to determine the dynamic material properties under the impact compressive loading conditions with strain-rate of the order of 103/s~104/s. In this paper, dynamic deformation behaviors of rubber materials widely used for the isolation of vibration from varying structures under dynamic loading are determined using a Split Hopkinson Pressure Bar technique.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.17-18
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.261-262
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• 2009