• Journal of Digital Convergence
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• v.11 no.7
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• pp.149-155
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• 2013

Recently, automobile traffic systems are evolving toward Intelligent Traffic Systems(ITS) with smart sensor technology and collaboration between traffic systems and external ones. On the contrary, Korean ITS services have little improvement comparing with other communication services. The main causes of this phenomenon are due to already allocation of ITS recommended frequency band to broadcasting services, and also dedication of DSRC frequency band over ISM band resulting in interferences. This paper provides the analysis of current Korean ITS technology status, and two suggestions to activate the ITS industry. First, need to fix the ITS standard combining WAVE and DSRC specifications soon. Second, ITS frequency allocation to complete its standard implementation in near time frame.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.83-91
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• 1998

Fiber Bragg grating which has a blazed ang1e to the plane of incident wave generates a side-mode as well as main-mode. The side-mode has an identical characteristics with a long period grating that couples with a cladding mode, so rejects the special wavelength. We experimented on the side-mode characteristics with two fibers which Ge doped depressed index fiber and very high photosensitive H$_2$ loaded step index fiber according to the tilted angle. Also, using a phase mask equipped with rotation plate which has 0.02$^{\circ}$ resolution, we can control the bandwidth and the peak value of a total loss spectrum by aligned tilted grating in a fiber and using this, tried to compose the ASE band rejection filter of the Erbium doped fiber amplifier.

• Journal of Digital Convergence
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• v.14 no.7
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• pp.11-20
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• 2016

This study examines the possibility of implementing the technology financing for export-import based small and medium sized enterprises. Our sample consists of 2,753 small and medium sized enterprises, receiving financial support from the Export-Import Bank of Korea for the period of 2011-2013. We find that only 400(200) firms reserve IPs(patents) annually. Given that IPs are likely to concentrate on manufacturer industries such as electronic components, computers, video, sound and communication equipment manufacturing(KSIC 26), other machinery and equipment manufacturing(KSIC 29), manufacture of motor vehicles and trailers(KSIC 31). We also find that the total assets, sales and R&D expenses of IP holding companies greatly exceeds those of companies without IPs. In addition, IP holding companies' liquidity seems slight edge and the leverage ratio is somewhat lower. However, profitability ratios of IP holding companies are rather than harsh or similar level. 20~30% of IP holding firms show very week credit scores, implying that banks' default risk is expected to be significant.

• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.376-383
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• 2012

The The purpose of this study is to develop survival kit prepared at the outbreak of the civil defense situation and to explore ways to ensure the safety and well-being of the people. Consider the civil defense shelters in a short two hours, from six days to live long, emergency life support food and other items needed for the basic right to life of the facility users. Minimum survival kit per capita personal weight 4.85kg, state and local governments (the government) is 2.65kg. They consists of a total of 26 items in eight categories such as food, clothing, CBR supplies, cold winter supplies, personal hygiene supplies, medicines, tools, communication supplies.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1201-1209
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• 2016

While the legacy electric grid evolving into the smart grid, various communication standards have been used for interoperability between many components. In this situation, the needs emerged for protocol conversion and mapping method for connecting the outside components to the operation center. In this paper, according to the surge of IEC 61850-based substation automation, we studied the protocol conversion gateway for linking legacy DNP3-based control center and IEC 61850-based substation automation. This paper is based on the IEEE 1815.1 standard for the protocol mapping. We suggested the direction of development the gateway and developed prototype for evaluate the proposed gateway. Also, we bring up a security problem and give a solution.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.8
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• pp.245-250
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• 2014

In recent years, the developments of medical technology and emergency medical services have been changed to home from the hospital. In this regard, the researches for the prevention or early diagnosis have become actively. In particular, bio-signal monitoring is applied to a variety of u-healthcare application services. The proposed system in this paper is to provide a security technology to protect the medical information measured from the various sensors. Especially, bio-signal information is privacy-sensitive personal information that must be protected. We applied a two-dimensional code technology, QR code, for the protection and management. In the client side, it can analyze the QR code and confirm the results on devices. Finally, with this proposed platform, we show the results of application service to verify the creation and distribution of integrated image file between the bio-signal and medical image information.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.484-490
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• 2013

With the rapid development of wireless communication at VHF and UHF bands, there is an increasing need for the reliable propagation prediction tools. Therefore, the different propagation models that have been developed in many countries as well as korea has been trying to secure a model suitable for their geographical area but then it is giving us a different result when we compared it to measured values. In this paper, based on the measurements of DTV broadcasting services in domestic urban area, analysis and comparison of ITU-R P.1546 and BCAST models provide errors between measured and predicted values, and some points for improving SMI system has been proposed. As a result, P.1546 model provides the valid predicted data similar to measured data, but BCAST model has some problems of large deviation and higher prediction to measured data. In future, these problems and diffractions due to high buildings need to be studied further.

• Korean Journal of Remote Sensing
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• v.17 no.3
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• pp.243-251
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• 2001

GPS is one of today's most widely used surveying techniques. But, users can't acquire an enough accuracy in applications of the navigation or geodesy by the GPS positioning technique because of the effects of the ionosphere and troposphere. The solution of these restrictions in the DGPS technique that is to eliminate the common errors and can achieve a high accuracy. Although of sufficient density for good DGPS, accuracy of positioning is just not dense enough to provide complete coverage for real-time positioning, because distances between base and rover is short. In this paper, we suggest Realtime Long-Distance Transmission Method of DGPS Error Correction Signal, which consist of TCP, UDP and IP, which allows a user to increase the distance at which the rover receiver is located from the base, due to radio modem.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.35-41
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• 2018

Unmanned Aerial Vehicles (UAV) have been used for various purposes in multiple fields, such as observation, communication relaying, and information acquisition. Nowadays, UAVs must have high performance in order to acquire more precise information in larger amounts than is now possible while performing for long periods. At present, domestically, a high-altitude long-endurance UAV (HALE UAV) for long-term flight in the stratosphere has been developed in order to replace some functions of the satellite. In this study, as a part of structural soundness evaluation of the aircraft structure developed for the HALE UAV, the structural soundness of the fasteners of the fuselage and tail is evaluated by calculating the margin of safety(M.S). The result confirms the validity of the design of the fasteners in the aircraft structure of the UAV.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.321-326
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• 2003

We constructed grating- tuned external cavity semiconductor lasers using Littman and Littrow configuration, for which the wavelengths are tuned by rotation of the grating. This wavelength tunable semiconductor laser is one of the main devices of WDM optical communication. In Littman configuration, the wavelength range of about 60 nm (The C- and L-band range of 1,530~1,590 nm) was obtained by changing the incidence angle of the grating about $\pm$1$^{\circ}$ from the incidence angle of 70$^{\circ}$. In the 40 nm tuning range, the output power variation was less than 1.25 ㏈ and the side mode suppression ratio(SMSR) was 32 ㏈. In Littrow configuration (The incidence angle and the first order diffraction angle is the same, i.e. $\alpha$=$\delta$), the wavelength tuning range was about 80 nm for the same conditions used in Littman configuration except the incidence angle ($\alpha$=49$^{\circ}$). In 60 nm tuning range, the output power variation was less than 1.5 ㏈ and SMSR was 35 ㏈.