• Journal of Positioning, Navigation, and Timing
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• v.6 no.3
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• pp.95-104
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• 2017

Positioning signals transmitted by Global Positioning System (GPS) satellites located at approximately 20,000 km height is very weak. For the reason, GPS signals are vulnerable to intentional jamming and unintentional disturbance. Recently, the number of jamming has been increased significantly all over the world. For the applications where continuous and reliable positioning is required when GPS jammers are activated, other positioning systems are strongly required. In this work, a set of Time Division Multiple Access (TDMA)-based transmitters and receivers utilizing Universal Software Radio Peripheral (USRP) and GNU Radio are designed and implemented. To eliminate the undesirable effects of GPS jamming, a frequency band which does not overlap L band is utilized. To demonstrate the accuracy of the proposed method, an experiment was performed.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.2
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• pp.47-53
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• 1984

Breakdown characteristics, specifically, soft breakdown phenomena of the PN junction isolation were studied in terms of their dependence on the mask misaliglment and the amount of process-related defects. Varying the distance between the buried layer and the isolation by intentional misalignment of the isolation masts had no effects on the soft breakdown phenomena except for the change of the breakdown voltage. The soft breakdown phenomena, as characterized as a state of excessive reverse current below the breakdown voltage, were found out to result mainly from the oxidation-induced stacking faults (OSF) introduced during the fabrication process.

• Korean Journal of Childcare and Education
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• v.12 no.4
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• pp.93-110
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• 2016

The purpose of this study was to analyze the effects of toddler's temperament and toddler-teacher relationship on their peer interaction, focusing on gender differences. A total of 221 toddlers(122 boys and 99 girls) attending 16 child care centers in South Korea participated in this study. Each toddler was observed during a free-play period in the classroom over 4 sessions of 5 minutes, so a total of 20 minutes was measured. Two observers scored recorded observation scenes with two peer interaction criteria, including interaction initiation and interaction participation level. The main results of this study are as follows: First, there was a signigicant gender difference in peer interaction and toddler's temperament and toddler-teacher relationship. Second, the factor of toddler-teacher relationship significantly predicted the boys' peer interaction, while for the girls, the significant predictor was intentional control of temperamental factors. Further, implications for different approaches according to the gender difference of the affecting factor on toddlers' peer interaction have been discussed.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.82-86
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• 2011

This paper presents an RF Electric field assessment at 2.290 [GHz] inside launcher PROTON M/Breeze M long fairings, produced by COMS TM. COMS intentional RE due to TM ON under fairing has been assessed considering PROTON M / BREEZE M fairing characteristics. As fairings of all launchers present similar sizes, a similar E-field level under fairing is expected for the other launchers. As a result, the RE level under faring is compliant with COMS RS limits, but is not compliant with RS requirements of the launcher PROTON M/Breeze M.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.4
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• pp.739-749
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• 2015

A new conceptual dual-buoy Wave Energy Converter (WEC) for the enhancement of energy extraction efficiency is suggested. Based on actual wave data, the design process for the suggested WEC is conducted in such a way as to ensure that it is suitable in real sea. Actual wave data measured in Korea's East Sea (position: $36.404N^{\circ}$ and $129.274E^{\circ}$) from May 1, 2002 to March 29, 2005 were used as the input wave spectrum for the performance estimation of the dual-buoy WEC. The suggested WEC, a point absorber type, consists of two concentric floating circular cylinders (an inner and a hollow outer buoy). Multiple resonant frequencies in proposed WEC affect the Power Ttake-off (PTO) performance of the WEC. Based on the numerical results, several design strategies are proposed to further enhance the extraction efficiency, including intentional mismatching among the heave natural frequencies of dual buoys, the natural frequency of the internal fluid, and the peak frequency of the input wave spectrum.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.108-110
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• 2017

The global positioning system (GPS) is a useful system in civilian and military applications. However, because of the weak signal, GPS receivers are vulnerable to interference caused by unwanted signals or intentional jammers. To alleviate this issue, a controlled reception pattern antenna (CRPA) array can be employed to adaptively place radiation pattern nulls toward the direction of the signal interference. The performance of the CRPA array improves as the number of antenna elements increases. Therefore, antenna miniaturization is highly desirable for CRPA applications. We designed a compact CRPA array based on seven electrically miniaturized microstrip patch antennas (MPAs) on a 5-inch ground platform. We used a non-Foster matching circuit to match efficiently miniaturized MPAs on an FR-4 substrate. Experimental results show that the non-Foster matching circuit significantly improves such elements of antenna performance as return loss and antenna gain. In addition, we confirmed that the mutual coupling of the proposed CRPA array is less than -45 dB.

• Journal of the Korean Home Economics Association
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• v.49 no.7
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• pp.81-95
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• 2011

In order to build a successful cohousing, active residents' participation is necessarily needed. However, there is no evidence of participating in communal residents' facility in the step of design or planning in our country. In this study, the workshop process was analyzed to obtain the improvement of the residents' participation and its result was presented to help understand the concept of cohousing and its residents' participation. The workshop was conducted twice with six couples aged in their 30s and 40s. The design and planning of whole town was conducted in the first workshop. In the second workshop, the contents which was decided at the first was reviewed and revised. Through two workshop, participants became a positive mind for the cohousing and gave the active opinions of future's involvement. In the conclusion, the workshop guided by professionals is important to establish the effective cohousing village.

• Korean Institute of Interior Design Journal
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• v.16 no.6
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• pp.36-46
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• 2007

Regeneration of old buildings is one of the most imperative responses to the 21th century issue of sustainable urban architectural environment. In particular, creative circulation of generation which conversion means highlights the conversion as a new design method. In this study, by examining buildings built over the last decade, the mutual relationship between old elements of existing buildings and new elements of newly required functions was analyzed and types of relationships such as 'alien insertion', 'mediate intervention', 'endogenous expansional enveloping', 'contrastive confliction' and 'over-layering' were defined. In addition, design strategies including the paradoxical curio, fore-grounding and unification were derived from each relationship. Finally, according to the relation type and design strategy, this study suggests several features of conversion design; (1) maximization of symbolism using unfamiliarities - emphasizing futuristic or contextual symbol with intentional contrasts by preserving the work or using contemporary addition; (2) time confusion using neutral space - meeting the need by harmonizing and cooperating existing elements and new elements; (3) mutual emphasizing by individualization - revealing differences between old and new for an aesthetical tension; (4) synchronism by constructional combination - making the one unity of different layers; (5) expansion by enveloping - experience of visual reverse and creation of extra space by roofing above building groups. The reconversion should be continuously researched in the future since conversion is a sustainable design method for the future of architecture.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.1009-1019
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• 2018

Bitcoin is the first application utilizing the blockchain, but it has limitations in terms of scalability. The concept of Lightning Network was recently introduced to address the scalability problem of Bitcoin. In this paper, we found that the real-world Bitcoin Lightning Network shows the scale-free property. Therefore, the Bitcoin Lightning Network can be vulnerable to the intentional attacks targeting some specific nodes in the network while it is still robust to the random node failures. We experimentally analyze the robustness of the Bitcoin's Lightning Network via the simulation of network attack model. Our simulation results demonstrate that the real-world Lightning Network is vulnerable to target attacks that destroy a few nodes with high degree.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.30-37
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• 2003

In this paper, a discrete wavelet transform (DWT)-based watermarking system is proposed. The main feature of proposed system is that the embedding system uses adaptive thresholds to control the trade-off between the qualify of the watermarked image and the capacity of the watermark, and the trade-off between the quality and robustness of the watermarked image. Also, the extracting system rebuilds threshold according to various attacks and decides a watermark bit from the least distorted coefficient after measuring the distortion of coefficient. Finally, a new measure to detect the uniqueness of watermark is proposed. The experimental result shows that the proposed watermarking system is robust against conventional signal processing and intentional attacks.