• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.913-922
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• 2020

In this paper, we propose a LoRa communication module using the LoRa RF module of Murata Electronics is designed to configure the IoT digital meter remote meter reading and a method of configuring a remote meter reading network by collecting multiple meter data in a DCU (Data Concentrate Unit) to configure a network with LoRaWAN. The developed system can be installed more easily and economically in the network configuration than the existing system by allowing the meter to be directly connected to the network or matched with a DCU to connect to the network according to the configuration of the consumer. The developed system was constructed using a digital water meter as an example, but it can also be applied to remote meter reading of the metered values of other meters such as electricity, water, gas, hot water and calorie meters. The main development contents are the design, configuration, and construction of digital meters, LoRa modules and DCUs, and how to connect the LoRaWAN network and transmit meter data to the server. By networking these devices, the system is configured, and the actual LoRaWAN communication is tested and the result is shown.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.17-28
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• 2019

6LoWPAN based on IEEE 802.15.4 is a realistic standard platform for various Internet of Things (IoT) applications. To bootstrap the LoWPAN (Low-power Wireless Personal Area Network), each device must perform 6LoWPAN-ND address registration to assign a unique IPv6 address. Without adequate security mechanisms, 6LoWPAN-ND is vulnerable to a variety of security attacks including corrupted node attacks. Several security mechanisms have been proposed as a supplement to the vulnerability, but the vulnerability exists because it relies solely on IEEE 802.15.4 hop-by-hop security. In this paper, we propose and analyze a vulnerability of 6LoWPAN-ND address registration and a new security mechanism suitable for preventing the attack of damaged node. It also shows that the proposed security mechanism is compatible with the Internet Engineering Task Force (IETF) standard and is more efficient than the mechanism proposed in the IETF 6 lo WG.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1104-1109
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• 2005

In this paper, a Ka-band harmonic mixer is designed and fabricated on the base of the multiplier theory that there is a bias point to maximize the third harmonic order($3f_{LO}$) with respect to a fundamental LO frequency($f_{LO}$), which can make the high-order mixing element($f_{RF}{\pm}3f_{LO}$) to be greater than other mixing elements, Pumping a RF frequency($f_{RF}$) and LO frequency($f_{LO}$). The harmonic mixer by the proposed design method is fabricated by using a commercial GaAs MESFET device with a plastic package and overcome these disadvantages that a conventional mixer in Ka-band suffer from a high cost, inefficient productivity and circuit complexity. The harmonic mixer have a -10 dB conversion loss at the IF Sequency($3f_{LO}-f_{RF}$=1.0GHz) by selecting a gate bias voltage for the maximum third-order LO harmonic element($3f_{LO}$=34.5 GHz) as pumping LO frequency($f_{LO}$=11.5 GHz) With respect to RF Sequency ($f_{RF}$=33.5GHz)

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.105-107
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• 2019

최근 몇 년간 소량의 데이터를 송수신하는 Massive IoT 네트워크에 많은 관심을 가지고 있다. 이러한 환경을 구축하기 위해서 저전력 광역 네트워크(LPWAN) 기술 중 LoRa(Long Range) 네트워크를 사용하고 있다. 대부분의 IoT 응용 서비스는 디바이스가 장시간 안정적으로 작동해야 하므로 에너지 효율성을 중점으로 두고 LoRa 디바이스의 수명을 최대화하기 위한 디바이스의 여러 동작들을 설계하는 에너지 소비 모델링이 중요하다. 따라서 본 논문에서는 LoRa Class B 통신 방식의 에너지 소비 모델을 정의하고 성능을 평가한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.95-99
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• 2019

In this paper, the uplink data transmitted from LoRa node is received and decomposed in LoRaWAN Network Server and converted into data with key and value. The data is converted into the data format required by the existing oneM2M platform, and transmitted. The oneM2M platform stores the data, another system for transmitting the data is implemented so that the processing for the data can be started immediately.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.129-132
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• 2019

This paper explains the design idea of a multi-Hop network for LoRaWAN. First, the existing LoRaWAN communication method(Single-Hop) will be described based on the standard specification. It then discusses technical considerations when converting from LoRaWAN to a multi-hop network. Finally, we introduce our ideas in this paper.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1271-1273
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• 2009

6LoWPAN 단위의 네트워크 이동성을 지원하는 6LoWPAN Mobile Router 들이 중첩된 네트워크를 형성하였을 때, 6LoWPAN 노드와 CN 간의 통신을 할 경우 패킷 전달을 위한 경로 최적화가 이루어지지 않는다. 특히 NEMO 프로토콜이 적용된 6LoWPAN 네트워크의 중첩된 레벨이 증가하는 경우 패킷 전달을 위한 루트가 더욱 복잡해지고 오버헤드가 커지는 문제가 발생한다. 따라서, 본 논문에서는 MANEMO 기술을 6LoWPAN 환경에 맞게 적용하여 중첩된 6LoWPAN 네트워크를 형성하지 않고 6LoWPAN Mobile Router 간에 Ad-hoc 네트워크를 형성하여 직접적인 통신이 가능하도록 네트워크를 구성함으로써 NEMO 환경에서의 터널링 오버 헤드 문제를 줄이고 통신 경로를 최적화하여 패킷 전송 지연을 최소화할 수 있는 방안을 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.470-475
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• 2008

6LoWPAN 센서 노드의 이동성을 지원하기 위해 기존의 Mobile IPv6 (MIPv6)와 같은 프로토콜을 활용하는 것은 저전력에 제한적 사양의 하드웨어로 구성된 6LoWPAN 센서 노드에서 구동되는 것이 현실적으로 불가능하다. 따라서 Mobile Access Gateway (MAG)가 6LoWPAN 센서 노드의 이동시 발생하는 바인딩 시그널링을 대신 처리해주는 Proxy Mobile IPv6 (PMIPv6) 프로토콜을 6LoWPAN에 적용하면 효율적으로 이동성을 지원할 수 있다. 하지만 Proxy Mobile IPv6는 6LoWPAN 이동 센서 노드와 1홉으로 연결되는 경우에 6LoWPAN 이동 센서 노드의 이동을 인지하고 Proxy Binding Update(PBU)를 하게 되지만, 6LoWPAN 센서 네트워크와 같이 멀티 홉으로 구성되는 네트워크에는 Proxy Mobile IPv6를 바로 적용할 수 없다. 따라서 본 논문에서는 기존의 1홉 단위로 연결된 6LoWPAN 이동 센서 노드의 이동성을 지원하는 Proxy Mobile IPv6 프로토콜을 멀티를 환경의 6LoWPAN 센서 네트워크에 적용하기 위한 방법을 제안한다.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.3
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• pp.183-188
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• 2010

In this paper we propose a detection method of the medial axis of the continuous stripes on the LoG scale-space. Our method detects the medial axis of continuous stripes iteratively by varying the scale of LoG operator. Small-scale LoG operator detects two +/- pole pairs centered on the edge positions of stripe by the zero-crossing detection. The more increase the scale of LoG scale-space, the more close two poles to the medial axis of stripe. The medial axis of continuous stripe is the position where two poles is overlapped. The proposed method detected robustly the medial axis of continuous stripes stronger than the thinning methods used to binary image.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.164-171
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• 2019

Focusing on the bridge facilities, which occupy the largest proportion among SOC public facilities in Korea, it is possible to reduce the cost compared to existing wired measurement systems or wireless measurement systems developed by domestic telecommunications companies, and to increase the technical perfection to be applied to many bridges. We developed a wireless measurement system for bridges. Using LoRa, one of the unlicensed LPWAN technologies, we have developed an optimized MEMS-based LoRa smart sensor node considering the domestic ISM band and the existing wired sensor LoRa DAQ sensor node that can communicate with the LoRa network. Application server was developed for the test bed performance verification and efficient management of the developed sensor node.