• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.2
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• pp.131-146
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• 2014

High-resolution seismic profiles coupled with sediment sampling were analyzed to investigate the acoustic characters and distribution patterns of the late Holocene sediments in Gamak Bay of the South Sea, Korea. The mean grain size of surficial sediment lies around $6.3{\sim}9.7{\Phi}$. Sediments in the bay consist of silt and clay with progressive decrease toward the inner bay. The seismic sedimentary sequence overlying the acoustic basement can be divided into two sedimentary units (GB I and II) by a prominent mid-reflector (Maximum Flooding Surface; MFS). The acoustic basement occurs at the depth between 20 m and 40 m below the sea-level and deepens gradually southward. The GB I, mostly occupying the channel-fill, is characterized by reflection-free seismic facies. It can be formed as late Transgressive System Tract (TST), interpreted tidal environment deposits. MFS appears at the depth of about 15~28 m below the sea-level and is well defined by even and continuous reflectors on the seismic profile. The GB II overlying MFS is composed of acoustically transparent to semitransparent and parallel internal reflectors. GB II is interpreted as the Highstand System Tract (HST) probably deposited during the last 6,000 yrs when the sea level was close to the present level. Especially, it is though that the GB II was subdivided into two layers (GB II-a and II-b) by a HST-reflector and this was classified by wind, sea water flux, and tidal current.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.223-231
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• 2018

Recently, due to various environmental problems, blast tracks in tunnel are replaced with concrete tracks, but they have more adverse effects on noise than blast tracks so that additional noise measures are needed. Among these measures, sound-absorbing blocks start to be used due to its easy and quick installation. However, the performance of sound absorption blocks need to be verified under real environmental and operational conditions. In this paper, interior noise levels in KTX train cruising in Dalseong tunnel are measured before and after the installation of sound-absorbing blocks and the measured data are analyzed and compared. Additionally, noise reduction are estimated by modeling the high speed train, the tunnel and absorption blocks. Measurement devices and methods are used according to ISO 3381 and the equivalent sound pressure levels during the cruising time inside the tunnel are computed. In addition to overall SPLs(Sound Pressure Levels), 1/3-octave-band levels are also analyzed to account for the frequency characteristics of sound absorption and equipment noise in a cabin. In addition, to consider the effects of train cruising speeds and environmental conditions on the measurements, the measured data are corrected by using those measured during the train-passing through the tunnels located before and behind the Dalseong tunnel. Analysis of measured results showed that the maximum noise reduction of 6.8 dB (A) can be achieved for the local region where the sound-absorbing blocks are installed. Finally, through the comparison of predicted 1/3-octave band SPLs for the KTX interior noise with the measurements, the understanding of noise reduction mechanism due to sound-absorbing blocks is enhanced.

• Journal of Korea Entertainment Industry Association
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• v.15 no.4
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• pp.73-87
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• 2021

Special theaters were created to provide a sense of immersion and spectacles due to differentiated screens, sound, seating facilities, and advanced services, and also expanded screens. The purpose of this study is to perform comparative analysis of the technical characteristics formats shown in special theaters(3D film, 4DX, IMAX, ScreenX, and VR) in order to identify and find ways to overcome the technological limitations in production. The various formats show differences in field of view depending on the exhibition technology and these differences affect the mise-en-scene, narrative, and editing of the film and consequently result in changes in the production environment and process. Therefore, directors and creators must understand the technological features and limitations of the new formats before making their approach. However, a new format encounters limitations on production sets due to the decline of technical education and succession. In situations where shooting with a special camera is essential, the particular characteristics of each format should be carefully considered from the planning stage but financial problems arise due to increase in production period and cost. To overcome these various obstacles, it is essential to first identify problems and present alternatives through in-depth research on the production set of each format. Finally, this research aims to explore the prototype of each format and analyze the current state of production technology with formats that have not been adapted to the market trends by combining with the other formats and showing that they can survive in new ways.

• Archives of design research
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• v.16 no.4
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• pp.121-128
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• 2003

This is the research to find out which one is the best for using manual among the 3 kinds of methods such as 'Text manual' and 'Animation I' and 'Animation II' which is made by Virtual Realities. Three kinds of methods have been experimented respectively. The manual for 'Animation I' adopt the motion video with basis sound and the additional comment and sound is added on the 'Animation II'. Every 3 manual has been studied and estimated by T-test and additional subjective estimation respectively, and the conclusions are as follows. The 1st answer is that 'Animation manual' is more easier than 'text manual', and the 2nd answer is that 'Animation II' is easier than 'Animation I'. Through post-interview and test, It is known that the animation manuals, which has been showing the multimedia, is more attractive than text manual.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.522-528
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• 2011

Artificial basilar membranes made of PVDF(polyvinylidene fluoride) are manufactured using microfabrication processes. The mechanical behavior of PVDF artificial basilar membrane was measured to evaluate its performance as a mechanical frequency analyzer using scanning LDV(laser Doppler vibrometer). The experimental setup consists of the microfabricated artificial basilar membrane, a loud speaker connected to an amplifier for generating acoustic pressure of specific spectral pattern, and a scanning LDV with controlling unit for measuring the displacement of the membrane on the incoming acoustic stimulation. The microfabricated artificial basilar membrane was attached tightly upon a package containing a chamber which can be filled with silicone oil before placed on the experimental setup stage. The experiment results showed that the microfabricated artificial basilar membrane has a property as a mechanical frequency analyzer.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.115-124
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• 2004

The content-based retrieval using low-level features can hardly provide the retrieval result that corresponds with conceptual demand of user for intelligent retrieval. Video includes not only moving picture data, but also audio or closed-caption data. Knowledge-based video retrieval is able to provide the retrieval result that corresponds with conceptual demand of user because of performing automatic indexing with such a variety data. In this paper, we present the knowledge-based video retrieval system using Korean closed-caption. The closed-caption is indexed by Korean keyword extraction system including the morphological analysis process. As a result, we are able to retrieve the video by using keyword from the indexing database. In the experiment, we have applied the proposed method to news video with closed-caption generated by Korean stenographic system, and have empirically confirmed that the proposed method provides the retrieval result that corresponds with more meaningful conceptual demand of user.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.177-180
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• 2008

SHCC shows the high energy tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For effective material design and application of SHCC, it is needed to investigate the damage process and micro-fracture mechanism of cement matrix reinforced with different types of fibers. The objective of this paper is to investigate the direct tensile response of cement composites reinforced with single and hybrid fibers using acoustic emission(AE) technique. In this study, the correlations between AE signal and result of the direct tensile response of SHCC. For these purposes, three kinds of fibers were used: PET1.5%, PET1.0+PE0.5%, PET1.0%+PVA0.5%. The result of the direct tensile response of SHCC, for the same volume fraction of fibers, ultimate strength of PET-PE specimen was 2.7 times higher than specimens with PET fibers. And from AE signal value, AE event numbers and cumulative energy were different according to kind of fiber because of the different material properties of reinforced fiber.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.260-261
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• 2017

최근 사회구조의 복잡화, 산업구조의 다변화, 기후변화 등에 의해 자연재해 및 산업재해, 도시재난이 급증하고, 그 규모 또한 대형화하고 있다. 이로 인해 에너지, 통신, 교통, 금융 등 공공 인프라의 피해가 급증하면서 작은 재해도 큰 재난으로 변하는 예가 늘어나고 있다. 한편 현대사회에 대한 IT의 관여도가 급속도로 늘어나면서 IT 서비스의 궁극적인 형태이자, 모든 산업을 수용하는 개념의 플랫폼(Platform)이 IT를 넘어서 글로벌 사회의 절대적 지배자로 등장했다. 또한 전 세계 유저들의 관점에서 보면 개개인들이 손에 든 스마트폰이 생활의 모든 분야에 걸쳐 소통, 정보, 쇼핑, 제보, 오락 등 모든 활동의 수단으로 절대적 가치를 창출하고 있다. 이는 스마트폰이 가진 스마트 데이터 생산 및 공유 기능에서 비롯된다. 이처럼 스마트 데이터를 기반으로 한 IT플랫폼이 중요한 위치를 점하지만, 아직 재난관리 분야에서 이를 본격적으로 도입, 활용하지 못하고 있다는 점은 큰 문제이다. 국내의 사정을 보면 다행히 벤처기업들을 중심으로 이 같은 플랫폼 구축 움직임이 시작되었으며, 여기에 활용될 데이터 자원을 창출할 수 있는 솔루션 및 특허기술들 역시 속속 등장하고 있다. 시민들이 재난현장을 스마트폰으로 실시간 공유하면 이 스마트 데이터들이 이미지 및 음향정보, 위치기반(GPS)정보, 시각정보, 3D정보, 빅데이터 정보, 센서정보 등으로 분류되어 플랫폼 안에서 인공지능(AI) 딥러닝 방식에 의해 분석되고, 이를 즉시 재난당국 및 시민들에게 재난긴급문자 등 자동으로 경보로 전해주는 것이 이 플랫폼의 핵심 기능이다. 몇몇 벤처기업이 보유한 특허기술을 기반으로 공공자본이 투입되어 이러한 플랫폼이 구축될 경우 국내 재난관리 수준의 획기적 발전은 물론 전 세계를 시장으로 한 플랫폼 수출 또는 글로벌 재난정보 수집능력에서도 엄청난 힘을 발휘할 것으로 기대된다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.545-555
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• 2020

This paper presented efficient transceiver structure using sub-band processing for underwater communication in terms of covertness and performance improvement. In aspect of covertness, encrypted coded-bits are divided into groups, and center frequency and sub band are determined by coded-bits of each group. Therefore, as center frequencies are changed randomly, it maintain the covertness effectively. In aspect of performance improvement, the performance of underwater communication mainly depends on multi-path propagation characteristics, Doppler-spread, and frame synchronization. Accordingly, in order to overcome these effects, non-coherent energy detector and turbo equalization method are employed in receiver side. Furthermore, optimal frame synchronization was proposed. Through the simulation and lake experiment, performance analysis was conducted. Especially in the lake experiment, as a result of applying optimal frame synchronization method to receiver structure, errors are corrected in most frames.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1097-1107
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• 2020

A methodology has been proposed to understand the spatiotemporal changes of the river topography through the longitudinal change of the geometric characteristics of the cross-sections and the properties related thereto. Three-dimensional spatial information of the riverbed was obtained through the detailed bathymetry survey using an acoustic echo sounder for the reach from Gumi Weir to Chilgok Weir in the Nakdong river. Geometric informations for the reference sections were extracted using the acquired bathymetry survey data. By comparing the geometric properties for the reference sections, it was possible to catch the topographic characteristics and its changes over a reach of the channel. Through comparison with past survey data, it was also possible to quantitatively grasp the amount of change in cross-sectional area and volumetric change of riverbed. It is expected that a quantitative evaluation of river topography changes will be possible by applying the method proposed in this study.