• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.55-56
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• 2015

본 논문에서는 여러 접속 인터페이스를 가진 노드로 구성된 저전력 손실 네트워크 기반의 로컬 Infra IoT 환경에서 로컬 Infra-less IoT 서비스를 제공하기 위한 네트워크 구성 방법을 제안한다. 우선, Infra IoT 네트워크환경의 분석을 통해 문제점을 정의하고 이후 로컬 Infra-less IoT 네트워크 모델을 정의하고 정의된 네트워크 모델에 필요한 네트워크 구성 방법을 제안한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.01a
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• pp.227-229
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• 2015

본 논문에서는 IETF 표준화 단체에서 고려되고 있는 저전력 손실 네트워크 환경으로 구성되는 로컬 Infra IoT 네트워크에서 로컬 Infra-less IoT 서비스를 제공하기 위한 네트워크 구성 방법을 제안한다. 우선, Infra IoT 네트워크를 분석하고 이 네트워크에서 Infra-less IoT 서비스 지원에 대한 문제점을 기술한다. 이후 로컬 Infra-less IoT 네트워크 모델을 정의하고 정의된 네트워크 모델에 필요한 네트워킹 요구 사항 및 네트워크 구성 방법을 제안한다.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.112-117
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• 2006

We experimentally investigated the transmission characteristics of 400 Gbit/s (10 Gbit/s ${\times}$ 40 channels) WDM signals with 100 GHz channel spacing over 323 km of installed NZ_DSF. The installed fiber has optical properties of 0.28 dB/km attenuation, 4.3 ps/nm/km dispersion, $0.083ps/nm^2/km$ dispersion slope and less than $0.05ps/km^{1/2}$ PMD coefficient. In this experiment, two cases of dispersion compensation schemes, the lumped type and the distributed type, were compared. The results implied that the distributed type dispersion compensation in which dispersion compensation devices are inserted at the end of the each span showed better transmission performance than the lumped one in which dispersion compensation devices are located at the transmitter and receiver sites. From the analysis of the experimental results, we verified that different transmission performance comes from the power penalty induced by XPM in the distributed scheme is lower than the lumped scheme case.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.406-408
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• 2015

최근 사물인터넷 환경은 다양한 서비스 개발로 인해 동일 지역 내에 다양한 서비스 디바이스로 구성된 네트워크가 형성되어 있다. 이런 네트워크 환경은 효율적 서비스 제공을 위해 스스로 서비스를 인지하고 서비스 별 네트워크 구성 기법이 필요하다. 따라서 본 논문에서는 Infra-less IoT 환경에서의 Self-Organization Network (SON) 기반 서비스 지향형 IoT 네트워크 구성 방법을 제안한다. 제안하는 기법은 서비스 제공 시 필요한 네트워크 시그널링을 최소활 할 수 있는 기법으로 활용될 수 있다.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.10
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• pp.357-364
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• 2014

The first mission for the IoT based hyper-connectivity communication is developing a device-to-device communication technique in infra-less low-power and lossy networks. In a low-power and lossy wireless network, IoT devices and routers cannot keep the original path toward the destination since they have the limited memory. Different from the previous light-weight routing protocols focusing on the reduction of the control messages, the proposed scheme provides the light-weight IPv6 address auto-configuration, IPv6 neighbor discovery and routing protocol in a IoT capable infra-less wireless networks with the bloom filer and enhanced rank concepts. And for the first time we evaluate our proposed scheme based on the modeling of various probability distributions in the IoT environments with the lossy wireless link. Specifically, the proposed enhanced RPL based light-weight routing protocol improves the robustness with the multi-paths locally established based on the enhanced rank concepts even though lossy wireless links are existed. We showed the improvements of the proposed scheme up to 40% than the RPL based protocol.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.135-142
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• 2010

Wireless mesh network, which is an access network technology, adopts ubiquitous features of ad-hoc network that includes capabilities of self-configuration and self-management. This paper proposes a scheme which enables nodes along route in wireless mesh network to authenticate data and verify data integrity. The scheme distinguishes infra-node, which is a network device used to form mesh network, and user node in ad-hoc network, which operates functions as a sender, receiver or relayer, to deploy different authentication scheme. That is, hop-based authentication scheme along route forming wireless backbone differs from authentication scheme for user nodes in route over MANET. The proposed scheme is less complex than previously proposed schemes from the repects of security setup procedures and managements. In addition, the scheme is able to reduce transmission delay from a source to a destination owing to fast authentication over wireless backbone.

• Journal of Korea Multimedia Society
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• v.10 no.4
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• pp.462-469
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• 2007

ATM protocol has the techniques such as cell discarding priority, traffic shaping and traffic policing. ATM based MPLS(Multiprotocol Label Switching) is discussed for its provisioning QoS commitment capabilities, traffic engineering and smooth migration for BcN using conventional ATM infra in Korea. This paper proposes preventive congestion control mechanism for detecting HTR(Hard To Reach) LSP(Label Switched Path) in ATM based MPLS systems. In particular, we decide HTR LSP using real time signaling information(etc., PTI,AIS/RDI) for applying HTR concept in circuit switching to ATM based MPLS systems and use those session gap and percentage based control algorithm that were used in conventional PSTN call controls. We concluded that it maximized the efficiency of network resources by restricting ineffective machine attempts. Proposed control can handle 208% call processing and more than 147% success call, than those without control. It can handle 187% BHCA(Busy Hour Call Attempts) with 100 times less than use of exchange memory.

• Journal of Internet Computing and Services
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• v.5 no.1
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• pp.25-32
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• 2004

Mobile computing environment makes it possible for computing activities to be maintained during movement even if a user changes its network point of attachment. Mobile IP is a standard protocol designed to be used in such mobile computing environment. However, Mobile IP has a drawback to incur a lot of handoff delays and waste network resources, since CoA(Care of Address) registration packets need to go through a HA(Home Agent) first whenever a mobile node moves. To solve this long-standing problem, this paper proposes a new scheme that, for infra-domain movement, efficiently performs local handoff without notifying the HA Specifically, based on the notion of load balance, the proposed scheme allows every FA(Foreign Agent) in a domain to become the root FA(also known as domain FA) dynamically, thus distributing the registration task into many other foreign agents. The dynamic root assignment through load balancing ultimately leads to fast network response due to less frequent transmission of registration packets.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.624-629
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• 2018

The current study was conducted to develop a portable composite gas detector allowing the detection of both $CO_2$ and $CH_4$ gases by means of the Non Dispersive Infra-Red (NDIR) method. The gas detector is configured to radiate infrared waves using infrared lamps, where the wavelength of the infrared light is reduced due to absorption throughout the chamber, and this reduction (absorption) is detected by the absorption detector, before being converted and amplified to a 3.5V~6V electrical signal, providing as accurate a measurement as possible. The conventional singe sensor method measures the relative measurement by absorbing only specified wavelengths of infrared radiation, which in the case of gas detection leads to problems with accuracy due to the lack of a reference sensor when detecting light with a wavelength of only $4.26{\mu}m$. The dual sensor employed in this study provides a comparative measurement between the reference value derived from the wavelength of $3.91{\mu}m$, which is not influenced by other gas sources, and the measurement value derived from the wavelength of $4.26{\mu}m$, in order to reduce the errors and enhance the reliability, thereby allowing low power consumption for portable devices and multi-gas detection for both $CO_2$ and $CH_4$ gases. The portable composite gas detector developed herein provides a measurement rage of 0ppm~5,000ppm for $CO_2$ gas, and 0.5%vol for $CH_4$, which allows the determination of whether the $CO_2$ and $CH_4$ contents in indoor air are less than 1,000ppm or not. The current study established that the composite gas detector can be interlinked with firefighting appliances through portable devices or home automation, and is anticipated to be very effective in fire prevention.