• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.3
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• pp.336-341
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• 2014

When using a higher-order modulation scheme, there are variations in bit-reliability depending on the bit position in a modulation symbol. Variations of bit-reliability in the codeword block lower the decoding performance. Also, the decoding performance increases as the sum of the bit-reliabilities in the codeword block increases. This paper presents a novel hybrid automatic repeat request scheme that increases the sum of the reliabilities of the transmitted bits by lowering the modulation order, and decreases the variations of bit-reliability in the codeword block by preferentially retransmitting bits with low reliability. The proposed scheme outperforms the constellation rearrangement scheme. Furthermore, the proposed scheme also provides a good solution in cases where the size of the retransmission block is smaller than the size of the initial transmission block.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.676-677
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• 2015

최근 사물인터넷(IoT)의 기반이 되는 아두이노 기술을 접목하여 다양한 스위치와 센서로 입력 값을 받아들여 LED, 모터와 같은 외부출력장치를 제어함으로써 상호 작용을 만들어 낼 수 있는 시스템개발이 유행이다. 본 논문에서는 아두이노를 이용하고 여러 가지 센서들을 활용하여 RC카 제작 및 거리제어 센서를 통한 DC모터 정지와 RFID를 통하여 LCD광고를 할 수 있는 자동차 시스템을 개발하였다. 개발한 시스템은 모터제어를 통하여 RC카의 전진과, 후진, 좌, 우 등 서브모터와, DC모터를 제어 하게 하였으며, 모터제어를 한 RC카에 블루투스 모듈을 장착하여 블루투스를 통하여 스마트폰으로 조종이 가능하도록 하였다. 안드로이드 어플을 사용하는 과정 중에 멈춤 오류로 인하여 S값을 한번만주는 형식의 안드로이드 어플을 이클립스로 제작하여 수정하였으며 전방에 거리감지센서를 장착하여 자동차의 20~150cm앞에 물체가 있을시 모터를 정지하게 하여 속도를 제어 하도록 하였다. 또한 RFID리더기를 사용하여 태그키가 RFID리더기에 태그 될시 LCD화면에 광고를 노출할 수 있게 하였다.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.115-124
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• 2013

In this paper, we suggest a secure data dissemination by Lightweight Individual Encryption Multicast scheme over wireless sensor networks using the individual encryption method with Forward Error Correction instead of the group key encryption method. In wireless sensor networks, a sink node disseminates multicast data to the number of sensor nodes to update the up to date software such as network re-programming and here the group key encryption method is the general approach to provide a secure transmission. This group key encryption approach involves re-key management to provide a strong secure content distribution, however it is complicated to provide group key management services in wireless sensor networks due to limited resources of computing, storage, and communication. Although it is possible to control an individual node, the cost problem about individual encryption comes up and the individual encryption method is difficult to apply in multicast data transmission on wireless sensor networks. Therefore we only use 0.16% of individually encrypted packets to securely transmit data with the unicast to every node and the rest 99.84% non-encrypted encoded packets is transmitted with the multicast for network performance.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.3
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• pp.155-164
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• 1997

A comprehensive and systematic field monitoring program was initiated since October 1989, in order to investigate the temporal and spatial variation of shoreline position at northern part of Pea Island, North Carolina. Aerial photographs were taken every two months on the shoreline extending from the US Coast Guard Station at the northern end of Pea Island to a point 6 miles to the south. Aerial photographs taken were digitized initially to obtain the shoreline position data. in which a wet-dry line visible on the beach was used to identify the position of shoreline. Since the wet-dry line does not represent the “true" shoreline .position but includes the errors due to the variations of wave run-up heights and tidal elevations at the time the photos taken, it is required to eliminate the tide and wave runup effects from the initially digitized shoreline .position data. Runup heights on the beach and tidal elevations at the time the aerial photographs taken were estimated using tide data collected at the end of the FRF pier and wave data measured from wave-rider gage installed at 4 km offshore, respectively A runup formula by Hunt (1957) was used to compute the run-up heights on the beach from the given deepwater wave conditions. With shoreline position data corrected for .wave runup and tide, both spatial and temporal variations of the shoreline positions for the monitoring shoreline were analyzed by examining local differences in shoreline movement and their time dependent variability. Six years data of one-mile-average shoreline indicated that there was an apparent seasonal variation of shoreline, that is, progradation of shoreline at summer (August) and recession at winter (February) at Pea Island. which was unclear with the uncorrected shoreline position data. Determination of shoreline position from aerial photograph, without regard to the effects of wave runup and tide, can lead to mis-interpretation for the temporal and spatial variation of shoreline changes.nges.