• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.4
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• pp.59-66
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• 2010

Aerospace structures need high stability and long life because many personal injuries can result from an accident and securing structural integrity for various external environments is more important than any other thing. So first of all we must prove the destruction properties for operating environment, have prediction technology about damage evolution and life, and develop an economical non-destructive technology capable of detecting structure damage. Acoustic emission (AE) have no need of artificial environment like ultrasonic inspection or radio fluoroscopy to emit a certain energy, is a testing technique using seismic signal resulting from interior changes of solids, and enables to observe if any fault is appeared and it grows seriously or not while running. In this study we suggest the method of structural integrity evaluation for aerospace structures through the acoustic emission technique, for which a model plane was manufactured and an actual operation test was conducted.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.299-301
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• 2006

It is very important to protect life, property at sea and marine environments from any pollution. The RFID when it applies a technique, is able to raise the stability of vessel as controling the mobile course and an entrance and exit of the crews as well as previously preventing accident from the vessel. The RFID technique which is applied, It show the effect which prevents an accident in advance, Currently it is used plentifully from physical distribution field and RFID KS domestic Standard $860MHz{\sim}960MHz$ band use the crew has the RFID tag and it will grasp incoming, leaving and movement.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1322-1328
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• 2010

Recently, keyword spotting system is greatly in the limelight as UI(User Interface) technology of ubiquitous home network system. Keyword spotting system is vulnerable to non-stationary noises such as TV, radio, dialogue. Especially, speech recognition rate goes down drastically under the embedded DSP(Digital Signal Processor) environments because it is relatively low in the computational capability to process input speech in real-time. In this paper, we propose a new keyword spotting system using the call-command method, which is consisted of small number of recognition networks. We select the call-command such as 'narae', 'home manager' and compose the small network as a token which is consisted of silence with the noise and call commands to carry the real-time recognition continuously for input speeches.

• ETRI Journal
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• v.35 no.6
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• pp.1084-1093
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• 2013

problem of pedestrian localization using mobile nodes containing impulse radio ultra wideband (IR-UWB) is considered. IEEE 802.15.4a-based IR-UWB can achieve accurate ranging. However, the coverage is as short as 30 m, owing to the restricted transmit power. This factor may cause a poor geometric relationship among the mobile nodes and anchor nodes in certain environments. To localize a group of pedestrians accurately, an enhanced cooperative localization method is proposed. We describe a sequential algorithm and define problems that may occur in the implementation of the algorithm. To solve these problems, a batch algorithm is proposed. The batch algorithm can be carried out after performing the sequential algorithm to linearize the nonlinear range equation. When a sequential algorithm cannot be performed due to a poor geometric relationship among nodes, a batch algorithm can be carried out directly. Herein, Monte Carlo simulations are presented to illustrate the proposed method and verify its performance.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.151-156
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• 2020

A technology for calculating the position of a device is very important for users who receive positioning services, regardless of various indoor/outdoor or with/without any positioning infrastructure existence environments. One of the positioning resources widely used at present, LTE, is a typical infrastructure that can overcome the space limitation, however its positioning method based on the position of the LTE base station has low accuracy. A method of constructing a radio wave map of an LTE signal has been proposed as a method for overcoming the accuracy, but it takes a lot of time and cost to perform high-density collection in a wide area. In this paper, we describe a method of creating a high-density DB for the entire region by using vehicle-based partial collection data. To create a positioning database, we applied the idea of Generative Adversarial Network (GAN), which has recently been in the spotlight in the field of deep learning, and learned the collected data. Then, a virtually generated map which having the smallest error from the actual data is selected as the optimum DB. We verified the effectiveness of the positioning DB generation algorithm using the positioning data obtained from un-collected area.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.58.2-58.2
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• 2014

We present the results of the KVN observations of central galaxies in cool-core and non cool-core clusters. The goal is to study how cooling environments affect the AGN activities in the core where their host galaxies are embedded. From the HIghest FLUx Galaxy Cluster Sample (HIFLUGCS), we have selected 19 radio bright AGNs located in the center of clusters with various cooling timescale. In our pilot study, we have obtained 22 and 43 GHz fluxes and morphologies of the sample using the Korean VLBI network. We find that 22/43 GHz fluxes do not strongly depend on the presence of a cool gas flow. However, an intriguing fact is that most AGNs in the cool-core clusters show the hint of a pc-scale jet component while the ones in the non cool-core clusters do not. Based on these results, we discuss the role of cooling flows in the central cluster AGNs and their co-evolution.

• ETRI Journal
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• v.38 no.2
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• pp.280-290
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• 2016

To implement high-order multiuser multiple input and multiple output (MU-MIMO) for massive MIMO systems, there must be a feedback scheme that can warrant its performance with a limited signaling overhead. The interference-to-noise ratio can be a basis for a novel form of Codebook (CB)-based MU-MIMO feedback scheme. The objective of this paper is to verify such a scheme's performance under a practical system configuration with a 3D channel model in various radio environments. We evaluate the performance of various CB-based feedback schemes with different types of overhead reduction approaches, providing an experimental ground with which to optimize a CB-based MU-MIMO feedback scheme while identifying the design constraints for a massive MIMO system.

• Journal of The Korean Astronomical Society
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• v.33 no.1
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• pp.37-45
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• 2000

We have investigated the properties of the high-latitude cloud MBM 7 using the 3 mm transitions of CO, CS, HCN, $HCO^+,\;C_3H_2,\;N_2H^+$, and SiO. The molecular component of MBM 7 shows a very clumpy structure with a size of $\le$0.5 pc, elongated along the northwest-southeast direction, perpendicularly to an extended HI component, which could be resulted from shock formation. We have derived physical properties for two molecular cores in the central region. Their sizes are 0.1-0.3 pc and masses 1-2 M$\bigodot$ having an average volume density $\~2{\times}10^3 cm^{-3}$ at the peak of molecular emission. We have tested the stability of the cores using the full version of the virial theorem and found that the cores are stabilized with ambient medium, and they are expected not to be dissipated easily without external perturbations. Therefore MBM 7 does not seem to be a site for new star formation. The molecular abundances in the densest core appear to be much less (by about one order of magnitude) than the 'general' dark cloud values. If the depletions of heavy elements are not significant in the HLCs compared with those in typical dark clouds, our results may suggest different chemical evolutionary stages or different chemical environments of the HLCs compared with dense dark clouds in the Galactic plane.

• Proceedings of the Korea Contents Association Conference
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• 2010.05a
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• pp.16-18
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• 2010

유비쿼터스 컴퓨팅 환경에서 다양한 위치 기반 서비스(LBS)를 위해 객체 식별은 필수적인 기술이다. 객체 식별을 위해서 영상 분석 식별, 무선 신호(RF: Radio Frequency) 식별, MIT Cricket 시스템의 RF 신호와 초음파를 활용한 객체 식별 등의 시스템들이 제안되었다. 그 중 가장 널리 이용되는 Cricket 시스템은 RF 신호에 객체의 식별 정보를 포함시켜 초음파 신호와 동시에 송신하고, 수신단에서 RF 신호의 정보를 통해 객체를 식별하는 방식을 이용한다. 하지만 유비쿼터스 컴퓨팅 환경에서 이용되는 단말 노드의 소형의 특성을 유지하기위해 다수의 장치 모듈을 내장하기 힘들다. 본 논문에서는 신호의 정확도가 높은 초음파를 활용하여 RF 통신모듈 없이 신호 중첩 분석으로 통해 다중 객체를 인식하기 위한 기술을 제안한다. 본 논문에서 제안하는 알고리즘의 가능성을 시뮬레이션을 통해 입증하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.273-278
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• 2012

Wired communication signals that are generated in a wheelchair and using GPS to gather speed in this study. And occupants in the helmet, and save your current location information in a wheelchair and speed information that is passed by smartphone to take advantage of the Black Box App and radio feature multi-Communications App S/W development.The results of this study can be utilized effectively a pseudo-real-time information can be shared in each other's wheelchair with many people moving. Limitations of the study at the Institute of Experimental concrete measures for the commercial approach to the development of operational models as required.