• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.1-11
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• 2016

We investigate compressive sensing techniques to estimate sparse channel in Orthogonal Frequency Division Multiplexing(OFDM) systems. In the case of large channel delay spread, compressive sensing may not be applicable because it is affected by length of measurement vectors. In this paper, we increase length of measurement vector adding pilot information to OFDM data block. The increased measurement vector improves probability of finding path delay set and Mean Squared Error(MSE) performance. Simulation results show that signal recovery performance of a proposed scheme is better than conventional schemes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.37-42
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• 2009

Cognitive radio (CR), which is proposed as a technology that utilizes the frequency resources effectively, has studied to relive scarcity of the frequency resources. Also, FCC revises the regulation to reuse the TV white spaces for applying CR system and allows to use the TV white spaces by CR devices and use of CR device may be regularized after conversion by DTV in 2009. If CR system's signal appeared in pilot's position, pilot sensing performs false alarm detection because pilot sensing scheme confuse DTV signal and CR system. In order to improve false alarm detection, we propose distinction scheme between DTV and CR system using PN511 sequence in this paper.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.4
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• pp.57-65
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• 2015

In this study, MBTI(Myers-Briggs Type Indicator) test was carried out targeting flight instructors and student pilots in charge of introductory flight training course. The results was analyzed in accordance with the personality type, the preferred indicator, and the combination of preferred indicators in order to see how these characteristics affect the flight training results. Most of personality types of the instructor, regardless of the attitude category such as E or I, were -STJ(70.6%), however the student pilot showed a variety of personality types, rather than professors. Sensing-type(S) students showed higher academic achievement scores than Intuition-type(N), and Judging-type(J) students showed higher academic achievement scores and pilot qualification scores than Perceiving-type(P). The success rate of Extraversion-type(E) student pilots was higher than that of Introversion-type(I) student pilots. As the personality combinations of instructor and student pilot, the academic achievement scores of Judging-Judging(J-J) type were higher than those of Perceiving-Perceiving(P-P) type. The combination of Extraversion-Extraversion(E-E) type showed higher success rate than Extraversion-Introversion(E-I). This result suggests that if both instructor and student pilot have same attitude of Extroversion(E), good training results can be expected.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8A
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• pp.723-729
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• 2011

FCC of U.S. permitted usage of unlicensed system on unused spectrum in TV white space after DTV transition. The unlicensed systems are required to avoid harmful interference to licensed users by employing geo-location database and spectrum sensing. The conventional spectrum sensing algorithms for ATSC signal were focused on detection of pilot signal. However, they can not guarantee detection of ATSC signal when pilot signal is attenuated by channel environment such as fading. To overcome drawbacks of conventional schemes, in this paper, we propose a signal detection and data fusion algorithm using cyclo-stationary feature weighted by signal energy. Simulation results verify that the proposed algorithm can provide 2dB SNR gain for 90% detection probability compare with the conventional scheme. We can reduce quiet period for spectrum sensing and improve signal detection probability by employing the proposed algorithm.

• Journal of Information Processing Systems
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• v.11 no.3
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• pp.342-353
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• 2015

It is widely accepted that single carrier frequency division multiple access (SC-FDMA) is an excellent candidate for broadband wireless systems. Channel estimation is one of the key challenges in SC-FDMA, since accurate channel estimation can significantly improve equalization at the receiver and, consequently, enhance the communication performances. In this paper, we study the application of compressive sensing for sparse channel estimation in a SC-FDMA system. By skillfully designing pilots, their patterns, and taking advantages of the sparsity of the channel impulse response, the proposed system realizes channel estimation at a low cost. Simulation results show that it can achieve significantly improved performance in a frequency selective fading sparse channel with fewer pilots.

• The KIPS Transactions:PartD
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• v.11D no.6
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• pp.1311-1318
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• 2004

Demand of water is increased according to city centralism phenomenon in population and development. In this progress, guarantee of enough water is important factor for water supply policy. For the detection of exact water leakage point, an epochal sensing technique using computer and internet is required, so, the water pipe having sensing wire and sensing technology using TDR(Time Domain Reflectometer), is proposed in this paper. For the prove of effectiveness of this system, pilot system using 300mm 3-layer coated steel pipe is made and tested.

• Journal of Advanced Navigation Technology
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• v.17 no.3
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• pp.298-305
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• 2013

In this paper, we propose simple combining schemes for sensing ATSC digital television signals with spectral correlation density (SCD). The detection algorithms exploiting the cyclostationarity exhibited by the pilot of ATSC digital television signals usually use the SCD value at a given particular frequency. However, we found that non-zero SCDs are found to be distributed over a certain range of frequencies in multipath fading environment. To utilize a set of non-zero SCD values computed in the vicinity of the pilot location, we formulate a class of combining methods in analogy with the maximal ratio combining, the square law combining and the equal gain combining. We show that the proposed simple combining schemes improve the detection performance by 0.5~1.0dB under multipath fading environments.

• Journal of Korea Multimedia Society
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• v.7 no.4
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• pp.567-578
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• 2004

GIS technique enhanced a space data manipulation ability and we are offering a geographic information service through various analysis. The quantity used of the water was increased in such situation according to a population increase and a city concentration phenomenon. But, to secure clear water are difficult, owing to the water shortage phenomenon, seepage and the quality of water change for worse. We decide the seepage and the system to retrieve the seepage location using GIS in order to reduce vast loss from the seepage. In this paper we proposed Leakage Sensing System using TDR technology in GIS, constructed a GIS database and pilot system to prove the validity, and simulated it using TDR in GIS.

• Journal of Distribution Science
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• v.21 no.2
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• pp.35-43
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• 2023

Purpose: As Thailand seeks to become a regional startup hub, Thai startups have been acquiring growth and scalability in the last ten years. Hence, this paper examines influential factors in Thailand's growth of logistics tech startups. The conceptual framework incorporates sensing user needs, sensing technological options, conceptualizing, scaling, and stretching, co-producing, and orchestrating, business strategy, strategic flexibility, and startup growth. Research design, data, and methodology: The quantitative method was applied to distribute the questionnaire to 500 managers and above in logistics tech startups in Thailand. The sampling techniques involve judgmental, convenience, and snowball samplings. Before the data collection, The Item Objective Congruence (IOC) Index and pilot test (n=45) were employed for content validity and reliability. The data were mainly analyzed by Confirmatory Factor Analysis (CFA) and Structural Equation Model (SEM). Results: The findings revealed that sensing technological options, scaling, and stretching, co-producing, and orchestrating, and business strategy significantly influence the growth of startups in Thailand. Nevertheless, sensing user needs, conceptualizing, and strategic flexibility have no significant relationship with startup growth. Conclusions: For Thailand to accelerate its digital economy driven by tech startups, firms must emphasize influential factors to accelerate growth by providing the right tech solutions for people's lives.

• Physical Therapy Rehabilitation Science
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• v.10 no.3
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• pp.374-378
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• 2021

Objective: Bilateral movement training is an effective method for upper extremity rehabilitation of stroke. An approach to induce bilateral movement through functional electrical stimulation is attempted. The purpose of this study is to develop an EMG-triggered functional electrical stimulation device for upper extremity bilateral movement training in stroke patients and test its feasibility. Design: Feasibility and Pilot study design. Methods: We assessed muscle activation and kinematic data of the affected and unaffected upper extremities of a stroke patient during wrist flexion and extension with and without the device. Wireless EMG was used to evaluate muscle activity, and 12 3D infrared cameras were used to evaluate kinematic data. Results: We developed an EMG-triggered functional electrical stimulation device to enable bilateral arm training in stroke patients. A system for controlling functional electrical stimulation with signals received through a 2-channel EMG sensor was developed. The device consists of an EMG sensing unit, a functional electrical stimulation unit, and a control unit. There was asymmetry of movement between the two sides during wrist flexion and extension. With the device, the asymmetry was lowest at 60% of the threshold of the unaffected side. Conclusions: In this study, we developed an EMG-triggered FES device, and the pilot study result showed that the device reduces asymmetry.