• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.110-115
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• 2012

Satellite structure should be designed to accommodate and support safely the payload and equipments necessary for its own missions and to secure satellite and payloads from severe launch environments. The launch environments imposed on satellites are quasi-static accelerations, aerodynamic loads, acoustic loads and shock loads. Currently KARI(Korea Aerospace Research Institute) is developing Geo-KOMPSAT-2(Geostationary Earth Orbit KOrea Multi-Purpose Satellite) with technologies which were acquired during COMS(Communication, Ocean and Meteorological Satellite) development. As compared to COMS Geo-KOMPSAT-2 requires more propellant due to mass increase of Advanced Meteorological Payload with high resolution and increase of miss life, it is difficult to apply the design concept of COMS to Geo-KOMPSAT-2. This paper deals with conceptual design of Structural Subsystem for Geo-KOMPSAT-2.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.515-517
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• 2018

Access to public facilities such as substations, dams and railway facilities is strictly controlled, and unmanned surveillance equipment has been introduced and operated recently due to the development of IT technology and the government's cost reduction policy. However, if an unmanned surveillance system is broken, surveillance space, information leakage caused by intruders, and damage to facilities may occur. Also, it is necessary to check periodical visit by the manager in order to check the surveillance facilities, which causes additional management costs. In order to solve this problem, we designed a system to check the operation status of the unmanned monitoring facility in real time, attempt to recover automatically when a problem occurs, and notify the administrator of the problem. The designed system consists of an NVR that receives and judges information such as image, sound, and lighting condition, and a control device that detects and restores the state of the unmanned monitoring facility. The system proposed in this paper is expected to contribute to the improvement of the economic efficiency due to the minimization of surveillance space due to the failure of the unmanned monitoring facility and the reduction of the inspection cost.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.119-126
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• 2018

In this study, In this study, the Datum Level-based hydrography surveying system and the ellipsoid-based system were analyzed to acquire more consistent depth data. For the study, the ellipsoid-based surveying for hydrography was conducted twice for the same track line. And the depth was calculated by correcting rise and fall of water level (water level change by tidal energy and other marine environmental energies) respectively by the traditional water level correction method and ellipsoidally referenced water level correction method. there is able to check that Ellipsoid-based hydrographic surveying data is more improved than Datum Level-based hydrographic surveying data in aspect of level difference phenomenon in the same area (surveying line). This result shows that if the Ellipsoid-based hydrographic surveying is performed, the sea level change (tidal energy and other marine environmental energy) of the survey area in real time could be reflected to more consistent generating bathymetric data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.271-277
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• 2003

Recently as the environmental noise getting influential social problem, it is the fact that the demand on noise reduction increases with the advance of the standard of living. Therefore increasing the interest on the noise in common, it is eagerly demanded that the endeavour for reducing the noise of the rotating machinery, especially the machinery related a flowing including the household electric products, which is pointed out the primary noise source in environment. As proceeding study for fan noise, theory of fan noise property is arranged and this control method is shown. Blade passage noise of total noise spectrum. Thus in the aspect of noise reduction, noise source and identification of noise radiation characteristics of axial flow fan are demanded in detail. The sound source is analyzed by using sound pressure and sound intensity. In that time, synchronization of axial flow fan using optical sensor is executed, and to identify the location of exact noise source in the fan profile determination of recording time is proposed. In the rotating of tan, it is explained that the location of noise source exists in and by the directivity, the noise radiation pattern of axial flow fan is determined and the flow of sound is visualized in the figure of contour mapping.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.1
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• pp.1-7
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• 2007

As fiber reinforced composite materials are widely used in aircraft, space structures and robot arms, the study on non-destructive testing methods has become an important research area for improving their reliability and safety. AE (acoustic emission) can evaluate the defects by detecting the emitting strain energy when elastic waves are generated by the initiation and growth of crack, plastic deformation, fiber breakage, matrix cleavage, or delamination. In the paper, AE signals generated under uniaxial tension were measured and analyzed using the $8{\times}8$ matrix piezo electric sensor. The electronic circuit to control the transmitting distance of AE signals was designed and constructed. The optical data storage system was also designed to store the AE signal of 64channels using LED (light emitting diode) elements. From the tests, it was shown that the source location and propagation path of AE signals in composite materials could be detected effectively by the $8{\times}8$ matrix piezo electric sensor.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.229-238
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• 2015

This study is to look into importance and achievement on awareness of creative musical audiences, who use SNS, by the use of Importance Performance Analysis(IPA), and to find ways to improve the recognition of creative musical by performance enterprise. In other words, the study is to discover choice attributes, that need to be urgently improved, which importance is rated high but which achievement is rated low. As a result, it is learned that composition of content(memorable dialogue), admission fee(ticket prices, charges of using additional facilities), theater(parking), composition of stage(acoustics of the stage), staff services(ticket box staff, usher, and etc. are should be properly controlled by staff expertise) need to be consistently improved. In addition, it is learned for SNS non-user group that choice items such as creative musical choice attribute(admission fee), composition of stage(acoustics of the stage), production(overall music from a musical), admission fee(ticket prices, charges of using additional facilities), and theater(parking) need to be improved.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.93-100
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• 2005

In this paper, we implement the embedded speech recognition system to support various application services such as audio and video control using speech recognition interface on cars. The embedded speech recognition system is implemented and ported in a DSP board. Because MIC type and speech codecs affect the accuracy of speech recognition. And also, we optimize the simulation and test environment to effectively remove the real noises on a car. We applied a noise suppression and feature compensation algorithm to increase an accuracy of sppech recognition on a car. And we used a context dependent tied-mixture acoustic modeling. The performance evaluation showed high accuracy of proposed system in office environment and even real car environment.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.169-177
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• 2002

We develop the weighted-averaging finite-element method which uses four kinds of element sets. By constructing global stiffness and mass matrices for four kinds of element sets and then averaging them with weighting coefficients, we obtain a new global stiffness and mass matrix. With the optimal weighting coefficients minimizing grid dispersion and grid anisotropy, we can reduce the number of grid points required per wavelength to 4 for a $1\%$ upper limit of error. We confirm the accuracy of our weighted-averaging finite-element method through accuracy analyses for a homogeneous and a horizontal-layer model. By synthetic data example, we reconfirm that our method is more efficient for simulating a geological model than previous finite-element methods.

• Journal of KIISE
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• v.42 no.11
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• pp.1372-1379
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• 2015

This paper presents an analysis of feature extraction methods used for distinguishing the speech of patients with cleft palates and people with normal palates. This research is a basic study on the development of a software system for automatic recognition and restoration of speech disorders, in pursuit of improving the welfare of speech disabled persons. Monosyllable voice data for experiments were collected for three groups: normal speech, cleft palate speech, and simulated clef palate speech. The data consists of 14 basic Korean consonants, 5 complex consonants, and 7 vowels. Feature extractions are performed using three well-known methods: LPC, MFCC, and PLP. The pattern recognition process is executed using the acoustic model GMM. From our experiments, we concluded that the MFCC method is generally the most effective way to identify speech distortions. These results may contribute to the automatic detection and correction of the distorted speech of cleft palate patients, along with the development of an identification tool for levels of speech distortion.

• Journal of Broadcast Engineering
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• v.1 no.1
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• pp.67-73
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• 1996

In general, the high quality audio coding(HQAC) has the structure of the convertional data compression techniques combined with moodels of human perception. The primary auditory characteristic applied to HQAC is the masking effect in the spectral domain. Therefore spectral techniques such as the subband coding or the transform coding are widely used[1][2]. However no effort has yet been made to apply the temporal masking effect and temporal redundancy removing method in HQAC. The audio data compression method proposed in this paper eliminates statistical and perceptual redundancies in both temporal and spectral domain. Transformed audio signal is divided into packets, which consist of 6 frames. A packet contains 1536 samples($256{\times}6$) :nd redundancies in packet reside in both temporal and spectral domain. Both redundancies are elminated at the same time in each packet. The psychoacoustic model has been improved to give more delicate results by taking into account temporal masking as well as fine spectral masking. For quantization, each packet is divided into subblocks designed to have an analogy with the nonlinear critical bands and to reflect the temporal auditory characteristics. Consequently, high quality of reconstructed audio is conserved at low bit-rates.