• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.432-437
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• 2002

현재 비파괴 상태진단기술의 세계적인 연구동향은 비접촉식 시험기술, 실시간 광역기술, 고온 환경 하에서의 시험기술, 온라인 감시기술, 고감도, 고분해능, 소형화 및 무선통신기술 등을 개발하는 방향으로 연구가 활발히 진행되고 있다. 특히 고온 환경 하에서의 시험기술의 경우 철강공장 등에서 그 수요가 급증하고 있는데 반하여 국내의 경우 개발기술이 거의 전무하며 외국에서 전량 수입에 의존하고 있는 실정이다. 최근 여러 가지 다양한 복합재료와 공업용 재료들이 개발됨에 따라 이들 재료의 제작 공정이 복잡해질 뿐만 아니라 고온 및 고압의 공정조건이 요구되는 경우가 많다. 따라서 고온환경 하에서 재료의 특성을 비파괴적으로 검사할 수 있는 초음파 탐촉자가 요구된다고 하겠다. (중략)

• Proceedings of the KSEEG Conference
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• 2002.04a
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• pp.463-465
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• 2002

연구지역은 좁은 면적에 비하여 800m 이상의 지형기복을 보이며, 계곡과 하천 충적층을 따라 마을이 발달된 전형적인 수계 상류의 농촌지역이다. 주요 상수원은 천부지하수이며, 농업용으로는 하천수를 이용한다. 지표수는 연구지역의 소유역(A, B)간 계절별 수질차이를 보이나, 지하수의 경우 유역간 및 계절별 변동이 상대적으로 작게 나타난다. B 소유역의 하류부에서는 지질매체의 영향으로 보이는 Fe, Mn, Zn 농도의 부화현상이 나타났으며, 이는 방이리층과 길왕리층을 기반암으로 하는 지역에 대한 전체적인 지하수질 조사가 필요함을 지시한다. 국지적인 수질오염원으로 과거에 개발되었던 폐금광이 존재하며, 이로 인한 산성수의 발생도 인지되었다.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.18-20
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• 2011

한류 문화를 비롯해 방송사들에서 시행하는 각종 오디션 프로그램들로 인해 대중음악계가 상당히 부각되고 있다. 이러한 가요계의 발전과 더불어 가수가 되고자 하는 지망생들이 급격히 증가하였는데, 아직은 이들을 가르치고 훈련을 받을 수 있는 교육적인 여건이 미비하다. 본 논문은 가수지망생, 즉 보컬이 기복적으로 갖추어야 할 호흡과 발성법에 관한 논문이다. 호흡과 발성은 노래를 잘하기 위한 과정이지만, 노래를 잘하기에 앞서 목소리를 크게 만들고 라이브 공연 시 목소리를 안정적으로 내기 위한 필수적인 요건이다. 명성에 비해 라이브 실력이 부족한 가수들을 흔히 볼 수 있는데 이것이 모두 호흡과 발성훈련을 소홀히 해서 생긴 결과이다. 따라서 본 논문에서는 크고, 안정적인 목소리를 만들기 위한 발성훈련 방법에 대해 알아보는 논문이다.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.109-116
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• 2013

To extract the 3D geometric information from SAR(Synthetic Aperture Radar) images, two different techniques, interferometric SAR and radargrammetry, have been widely used. InSAR is most widely used for the generation of precise DEM(Digital Elevation Model) until now. But, Interferometric SAR requires severe temporal correlation over areas covered with vegetation and high relief areas. Because radargrammetry is less sensible to temporal correlation, it can provide better results than interferometric SAR in certain, especially X-band SAR. In this paper, we assess the properties of DEMs generated by radargrammetry using stereo C-band RADARSAT-1 images and X-band TerraSAR-X images.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.8 no.2
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• pp.45-51
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• 1990

DEM must have a high accuracy against the actual topographic model. A model which can compute heights responding to random plane position by using of the topographic data and interpolation must be constructed. Interpolation affected by the accuraccy of the observations included noise, which affected by the slop and curvature weight. Data smoothing is a method to reduce the noise. Average declination and area ratio are variable which result similarity in according to slope. But in local area, area ratio well shows a local change. This study try to classify the terrain by the declination to analysis the effects of the declination and curvature weights, and then to represent the most probable model. The result are following : In terrain classification by the slop, p16 and p24 were fitted in the plane surface fit p16 and S in the varying surface, and S and p24 in the irregular surface in classification by curvature, p24 and S were fitted in the plane or varying surface, and p16 in the irregular surface In case of hybrid, p16, p24 and S are fitted in the plane, varying and irregular surface respectively. Smoothing is the most effective in case of slope of 50 persentage and of curvature weight of 0.0015.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.405-419
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• 2002

Fracture roughness of rock specimens is observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wave length of laser is 488 nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The function of laser reflection auto-focusing enables us to measure line data fast and precisely. The system improves resolution in the light axis (namely z) direction because of the confocal optics. Using the CLSM, it is Possible to measure a specimen of the size up to $10{\;}{\times}{\;}10{\;}cm$ which is fixed on a specially designed stage. A sampling is managed in a spacing $2.5{\;}\mu\textrm{m}$ along x and y directions. The highest measurement resolution of z direction is $10{\;}\mu\textrm{m}$, which is more accurate than other methods. Core specimens of coarse and fine grained granite are provided. Fractures are artificially maneuvered by a Brazilian test method. Measurements are performed along three scan lines on each fracture surface. The measured data are represented as 2-D and 3-D digital images showing detailed features of roughness. Line profiles of the coarse granites represent more frequent change of undulation than those of the fine granite. Spectral analyses by the fast Fourier transform (FFT) are performed to characterize the roughness data quantitatively and to identify influential frequency of roughness. The FFT results suggest that a specimen loaded by large and low frequency energy tends to have high values of undulation change and large wave length of fracture roughness.

• Journal of Korea Water Resources Association
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• v.54 no.8
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• pp.629-641
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• 2021

In this study, a two-dimensional numerical model (Nays2DH) was applied to analyze the process of morphological changes in the river channel bed depending on the changes in the amount of flooding after fully opening the Sejong weir, which was constructed upstream of the Geum River. For this, numerical simulations were performed by assuming the flow conditions, such as a non-uniform flow (NF), unsteady flows (single flood event, SF), and a continuous flood event (CF). Here, in the cases of the SF and CF, the normalized hydrograph was calculated from real flood events, and then the hydrograph was reconfigured by the peak flow discharge according to the scenario, and then it was employed as the flow discharge at the upstream boundary condition. In this study, to quantitatively evaluate the morphological changes, we analyzed the time changes in the bed deformation the bed relief index (BRI), and we compared the aerial photographs of the study area and the numerical simulation results. As simulation results of the NF, when the steady flow discharge increases, the ratio of lower width to depth decreases and the speed of bar migration increases. The BRI initially increases, but the amount of change decreased with time. In addition, when the steady flow discharge increases, the BRI increased. In the case of SF, the speed of bar migration decreased with the change of the flow discharge. In terms of the morphological response to the peak flood discharge, the time lag also indicated. In other words, in the SF, the change of channel bed indicates a phase lag with respect to the hydraulic condition. In the result of numerical simulation of CF, the speed of bar migration depending on the peak flood discharges decreased exponentially despite the repeated flood occurrences. In addition, as in the result of SF, the phase lag indicated, and the speed of bar migration decreased exponentially. The BRI increased with time changes, but the rate of increase in the BRI was modest despite the continuous peak flooding. Through this study, the morphological changes based on the hydrological characteristics of the river were analyzed numerically, and the methodology suggested that a quantitative prediction for the river bed change according to the flow characteristic can be applied to the field.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.49-55
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• 2007

Various away methods are required in the electrical resistivity survey in order to find anomalous zone reliably. Array methods are classified as several groups. Among these group, a curved survey along the fixed elevation is designed to increase the mobility of men and survey equipments at the rough terrain. Another method is performed at the survey using inclined, curved, and horizontal boreholes. A survey can also be conducted in an arbitrary location by measurements of potentials for a multi sources. The complex data acquired using various away methods are represented by a correct images reconstructed from the 3D inversion. The element division is applied to the region in which the boreholes are curved and inclined because of a spatial discrepancies between the coordinate of each electrode and the nodal point in a model. The resistivity images are obtained from a good agreement for the anomalous zones in open slope and in survey using an inclined borehole.

• Geophysics and Geophysical Exploration
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• v.23 no.4
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• pp.253-260
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• 2020

The five-story stone pagoda in Tamni-ri located in Uiseong County in Gyeongsangbuk-do had an unstable upper structure, and the structural deformation of the foundation stone and the stylobate was severe. In order to repair the base of the pagoda, it must be confirmed if there are support stones inside the base. Resistivity survey was performed to study the inner base stone structure during the repair work. The stylobate was exposed soil and broken stones after removing the walls and the cover of the stylobate. Modified pole-dipole array II was used for the resistivity survey, and compared with the typical pole-dipole array method. And in this study, a physical scale-down model experiment was performed to compare and analyze distortions caused by severe topographical undulations such as right-angled lines. The results show that the stylobate of Five-story Stone Pagoda in Tamni-ri Uiseong has base stones inside the reinforced filling soil and are located beneath the pillar of the body and supporting the pagoda.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.192-197
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• 2012

In this paper, a non-contact microwave technique was presented to detect the surface crack of the metals. An open-ended coaxial cable line was used as a sensor at 11 GHz, and the reflection coefficients were measured by scanning along the metal surface including artificial surface cracks. A parameter, the K value which was defined as the difference between maximum and minimum reflection coefficients, was measured and used to estimate the crack depth. A linear relationship between the K value and crack depth was found. This study showed that non-contact detection of the surface cracks of metals is possible using the open-ended coaxial line sensor at X-band.