• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.387-392
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• 2010

This study focuses on improving MIMO-OFDM systems by combining a wireless communication architecture known as vertical BLAST(bell laboratories layered space-time) or V-BLAST and STTC(space time trellis coding). In this paper, the combination is done by introducing STTC in each V-BLAST layer. Moreover, this architecture uses multiple antennas that are grouped into small number of antennas which makes it less complex to decode by decoding every group. Whereas, in traditional V-BLAST, all the antennas form one group and they are decoded together at the receiver, therefore, this increases the complexity as the number of antennas is getting high. We compare the bit error rate performance of this system with MIMO-OFDM that uses convolutional coding instead of STTC. Under the same spectral efficiency, the simulation results prove that joining V-BLAST with STTC improves MIMO-OFDM systems performance.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.2
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• pp.163-168
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• 2015

The conventional simple-injection and unilateral-learning methods have the great disadvantages in special education outcomes for intellectual disabilities student. In this paper, we propose a digital micro-mirror system that learners themselves can manipulate the contents by using the various technology on user-interaction and augmented reality. Through the verification tests conducted by special education professionals, it is confirmed that the proposed commercial system can be used as a useful system in the special learning fields requiring high immersion.

• Korea Science and Art Forum
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• v.19
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• pp.623-633
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• 2015

Use of technology through utilization of ICT (Information Communication Technology) in field study area is rapidly increasing. Thus, when applying ICT to experiential education, apart from experiential education contents in simple form, the demand for new high quality contents is increasing considering change in education paradigm focusing on creativity. As a result, high quality interactive experiential education content for developing self-directed future talents is required. As a result of this, the development of ARD-based ICT experiential education content system that enhances learning effect of students by integrating ARD-based (Augmented Reality Display) ICT and experiential education to promote existence and immersion is being tested. This paper aims to improve efficacy and achieve vitalization through case analysis of AR-based ICT experiential education content. As a result of case analysis, the composition of content for improving education content included 1) constant securing and strengthening of experiential education content, 2) necessity for development of participating education content by diverse age groups, 3) development of differentiated ICT experiential education content, and 4) securing professional manpower and development of content in connection with education process. Therefore, with the efficacy of ARD-based ICT experiential education content, this study can first, enhance bond between students, second, enable self-directed learning, third, increase practical understanding in contents that were difficult to control by textbook contents, and fourth, increase interest and immersion in learning. Therefore, the contents on new converging technology that can maximize the development of constant content and cooperation between ICT technology and pedagogy for educating creativity and autonomy of ICT experiential education content.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.185-196
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• 2006

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2375-2393
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• 2016

Key agreement is paramount in secure wireless communications. A promising approach to address key agreement schemes is to extract secure keys from channel characteristics. However, because channels lack randomness, it is difficult for wireless networks with stationary communicating terminals to generate robust keys. In this paper, we propose a Robust Secure Key Agreement (RSKA) scheme from Received Signal Strength (RSS) in stationary wireless networks. In order to mitigate the asymmetry in RSS measurements for communicating parties, the sender and receiver normalize RSS measurements and quantize them into q-bit sequences. They then reshape bit sequences into new l-bit sequences. These bit sequences work as key sources. Rather than extracting the key from the key sources directly, the sender randomly generates a bit sequence as a key and hides it in a promise. This is created from a polynomial constructed on the sender's key source and key. The receiver recovers the key by reconstructing a polynomial from its key source and the promise. Our analysis shows that the shared key generated by our proposed RSKA scheme has features of high randomness and a high bit rate compared to traditional RSS-based key agreement schemes.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.1
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• pp.49-53
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• 2010

e-learning and m-learning have some problems that data transmission frequently discontinuously, communication cost increases, the computation speed of mass data drops, battery limitation in the mobile learning environments. In this paper, we propose the PULIMS for u-learning systems. The proposed system intellectualize the education environment using intelligent mobile agent, supports the customized education service, and helps that learners feasible access to the education information through mobile phone. We can see the fact that the efficience of proposed method is outperformed that of the conventional methods. The PULIMS is new technology that can be used to learn whenever and wherever learners want in Ubiquitous education environment.

• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.216-222
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• 2013

It is known that blood circulation in human body causes the skin tone to change concurrently with heartbeats. A number of apps have been developed to measure the heartbeat using smartphone camera; however, no any further analysis is performed. In this paper we propose an algorithm that detects heartbeats from the phone's camera and further extracts the heart rate variability (HRV). We compare the HRV extracted from the camera with the HRV extracted from the electrocardiogram. We estimated a number of commonly used HRV characteristics and compared them. Our results show that smartphone camera leads to slightly overestimated characteristics although the difference in extracted HRV signals is negligible. As a consequence we suggest that a smartphone camera can be employed in a quick heart diagnosis and diagnosis of autonomic nervous system.

• Journal of the Korea Convergence Society
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• v.2 no.4
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• pp.21-27
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• 2011

Recently, new distributed power sources such as photovoltaic, wind power, fuel cell systems etc. are energetically interconnected and operated in the distribution feeders, as one of the national projects for alternative energy. When new power sources are considered to be interconnected to distribution systems, bi-directional power flow and interconnection conditions of new power sources may cause several power quality problems like voltage sag, voltage swell, harmonics, since new power sources can change typical characteristics of distribution systems. Under these situations, this paper deals with the analysis the power quality problems at primary and secondary feeders in distribution systems, when new power sources like photovoltaic (PV) systems are interconnected, by using the test devices for PV systems based on the LabVIEW S/W. This paper presents the test device which is consisted with model distribution system and model PV systems. By performing the simulation for power quality operation characteristic based on the test facilities, this paper presents the optimal countermeasures for power quality.

• Journal of The Korean Association of Information Education
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• v.8 no.2
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• pp.213-224
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• 2004

Textbooks are the basic materials for school education and the best instruments that the teachers can use. The textbooks for information and communication technology education that are authorized by the superintendent of schools are currently used in the elementary schools and the various kinds of the ICT textbooks are adopted in accordance with the cities and provinces. In this study, we make a comparative study of the 11 ICT textbooks for year 4 students from the view points of the present conditions, the organizations, and the contents. Also, using Romey's method we investigate them whether their contents are suitable for the inquiring activities. We expect that our study will be the basis of the development of the next authorized ICT textbooks and contribute to the ICT education.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.1812-1824
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• 2019

The location and human activity are usually used as one of the important parameters to monitor the health status in healthcare devices. However, nearly all existing location and monitoring systems have the limitation of short-range communication and high power consumption. In this paper, we propose a new mechanism to collect and transmit monitoring information based on LoRa technology. The monitoring device with sensors can collect the real-time activity and location information and transmit them to the cloud server through LoRa gateway. The user can check all his history and current information through the specific designed mobile applications. Experiment was carried out to verify the communication, power consumption and monitoring performance of the entire system. Experimental results demonstrate that this system can collect monitoring and activity information accurately and provide the long rang coverage with low power consumption.