• Tunnel and Underground Space
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• v.19 no.6
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• pp.517-525
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• 2009

Stereophotogrammetry is used to extract spatial information of an interested object by constructing a stereo-image from two or more photos. In this study, the stereophotogrammetry was adopted for a rock joint survey in mine tunnels. The orientations of discontinuities were measured from two mine tunnels with a clinocompass. To evaluate the effect of photographing light level on the stereophotogrammetry analysis, the light intensity was changed within a predefined range for every photograph. Those photographs were analyzed by using a commercial code for stereophotogrammetry - ShapeMetriX 3D, and the results from the analysis were compared with the manual measurement using a clinocompass.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1357-1363
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• 1997

Currently it is increasing to use th bonded dissimilar materials in the various field of advanced engineering such as the highly rigid and lighter vehicle, plastic molding LSI package and metal/ceramic bonded joint. In spite of such a wide application of the bonded dissimilar materials, the evaluation method of the bonding strength has not been established yet. Therefore in this paper we analyze the interface crack problem by introducing fracture mechanics parameters as the basic research about estimating of the strength of adhesive joints. The variation of stress intensity factor according to the elastic modulus of adherend and thickness of bonded layer are investigated. Numerical results are based on the results of boundary element analysis of four different type butt joints subjected to uniaxial tension loading.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.465-474
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• 1999

A recently developed numerical method based on a volume integral formulation is applied to calculate the accurate stress intensity factors at the crack tips in unbounded isotropic solids in the presence of multiple anisotropic inclusions and cracks subject to external loads. In this paper, a detailed analysis of the stress intensity factors are carried out for an unbounded isotropic matrix containing an orthotropic cylindrical inclusion and a crack. The accuracy and effectiveness of the new method are examined through comparison with results obtained from analytical method and finite element method using ANSYS. It is demonstrated that this new method is very accurate and effective for solving plane elastostatic problems in unbounded solids containing anisotropic inclusions and cracks.

• Speech Sciences
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• v.14 no.1
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• pp.121-135
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• 2007

The purpose of this paper is to examine how Korean speakers realize English stress and rhythm at the sentence level, and investigate what different acoustic characteristics of English sentence stress and rhythm Korean speakers have, compared with those of American English speakers. Stressed words in the sentence were analyzed in terms of duration, fundamental frequency, and intensity of the stressed vowel in the word with neutral stress and with emphatic stress, respectively. According to the results, when the words had emphatic stress, both Koreans' and Americans' F0 and intensity of the stressed vowel were higher than those with neutral stress. Korean speakers of English realized the sentence stress with shorter vowel duration and higher F0 than American English speakers when the words had emphatic stress. The analysis of the timing of the sentence with increased unstressed syllables showed that both Americans and Koreans produced the sentence with longer duration as the number of unstressed syllables increased. However, the duration of unstressed syllables between stressed syllables by Koreans was longer than that by Americans. Americans seemed to produce unstressed syllables between stressed syllables faster than Koreans for regular intervals of stressed syllables. This analysis implies that if there are more unstressed syllables between stressed syllables, Koreans might produce unstressed syllables and the whole sentence with longer duration.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.136-142
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• 2004

Effects of Nb(Niobium) contents and solution annealing on the strength and fatigue lift of 18%Ni maraging steel commonly using in aircraft, space field, nuclear energy, and vehicle etc. were investigated. Also the fatigue life stress intensity factor were compared experiment result and FEA(finite element analysis) result. The more Nb content, the higher or the lower fatigue lift on base metal specimens or solution annealed specimens showing that the fatigue life was almost the same. The maximum stresses of X, Y, and Z axis direction showed about 2.12${\times}$10$^2$MPa, 4.40${\times}$10$^2$MPa and 1.32${\times}$10$^2$MPa respectively. The Y direction stress showed the highest because of the same direction as the loading direction. The fatigue lives showed about 7% lower FEA result than experiment result showing almost invariable error every analyzed cycle. Stress intensity factor of the FEA result was lower about 3.5∼10% than that of the experiment result showing that the longer fatigue crack length, the higher error. It considered that the cause for the difference was the modeled crack tip having always the same shape and condition regardless of the crack growth.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.435-446
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• 2014

Tidal turbulence was examined using three-dimensional tidal velocity data observed at a trench offshore of Tongyoung, Korea. The kinetic energy and intensity, including the variation period of the flow velocity and direction, were used to investigate the relationships between tidal turbulence and fishing gear dynamics, including the effects of swimming fish during fishing operations. As the resultant velocity increased from 0.2 to 0.9 m/s, the kinetic energy also significantly increased, while the turbulence intensity decreased from 50 to 10%. Tidal flow in strong flow fields displayed shorter periods of between 4 and 10 s, as determined by fast Fourier transform, the global wavelet method, and peak event analysis, and the periods were compared with the period of response to swimming fish and to oscillation of fishing gear. As mean velocity increased, velocity amplitude also increased from 0.1 to 0.6 m/s, and its directional amplitude changed markedly from 20 and $90^{\circ}$. Our study suggests that tidal turbulence can influence fish behavior or fishing gear geometry during fishing operations, although our analysis considered only a limited area. In future work, observations should be carried out over a more extensive depth and area.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1316-1317
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• 2011

This paper presents analysis of temperature and light intensity characteristics of PV modules with solar cell type. Taking the effect of sunlight irradiance on the cell temperature, the first experiment takes ambient temperature as reference input and uses the solar insolation as a unique varying parameter. Then taking the effect of the cell temperature on sunlight irradiance, the second experiment takes 1000W/$m^2$ as reference input and uses the cell temperature as a unique varying parameter. As a result, varying sunlight irradiance, the Cell-Type with the smallest change in output is HIT and the Cell-Type with the biggest change in output is a-Si. Varying the cell temperature, the Cell-Type with the smallest change in output is a-Si and the Cell-Type with the biggest change in output is Single-Si. And considering both temperature and light intensity characteristics, the Cell-Type with the smallest change in output is HIT.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.544-551
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• 2008

We have studied the dielectric characteristics of low-k interlayer dielectric materials fabricated by PECVD for various precursor's flow rates. BTMSM precursor was introduced with the flow rates from 42 sccm to 60 sccm by 2 sccm step in the constant flow rate of 60 sccm $O_2$. The absorption intensities of Si-O-$CH_x$ bonding group and Si-$CH_x$ bonding group changed synchronously for the variation of precursor flow rate, but the intensity of Si-O-Si(C) responded asynchronously with the $CH_x$ combined bonds. The heat treatment reduced the FTIR absorption intensity of Si-O-$CH_x$ bonding group and Si-$CH_x$ bonding group but increased the intensity of Si-O-Si(C). The nanopore and free space formed by the increasement of caged link mode and cross link mode of Si-O-Si(C) group implied the origin of low-k SiOCH films.

• The Journal of the Acoustical Society of Korea
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• v.10 no.3
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• pp.13-18
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• 1991

In this study, the analysis technique of fracture stress using the reflection coefficient of SAW reflected from a brittle solid with surface crack has been studied. Fracture stress of brittle solid with surface crack has been obtained by the function of the critical stress intensity factor and the maximum normalized stress intensity factor of the crack in the body. And the maximum normalized stress intensity factor of a surface crack can be inferred from a measurement of reflection coefficient of SAW. In experiment, the surface cracks ranging from 0.5mm to 0.9mm in crack depth has been made at the center of each Pyrex disc, and the SAW wedge transducer has been set up for the pitch-catch mode. It has been compared the theoretical values of the fracture stress calculated from the reflection coefficient of SAW with the values of the fracture stress measured from UTM.

• Journal of the Korean Institute of Navigation
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• v.2 no.1
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• pp.15-34
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• 1978

This paper deals with the study of the effective reflecting area of the land targets for the improvement of the map of the Radar Simulator, through the analysis of the pictures on P.P.I Scope. It is very important to anticipate the effective refiecting area of land marks, either forinterpretation of radar scope or for simulating accurately the radar scope, but has seldom been studied theoretically or experimentarily, especially on the stand point of simulating the radar scope. Most of the maps of Radar Simulator in use are made without consideration of the effective reflecting area of land marks, so that the P.P.I. Scope of the Radar Simulator may show much different pictures from the actual shore line and other targets. This paper has derived the following conclusiions by experimental procedures. 1. The effective area of the land target greatly varies according to the gradient of the contours, roughness and material of the land surfaces, so that simulator maps of uniformly coated land taret practically used now many be effectively improved by varying the intensity of the land marks proposed in this paper. 2. The intensity of the land targets on the P.P.I. is also related much to the distance from the radar, so that the precalculation of this effect may results in a much simulated P.P.I. picture improved. 3. If the ambient condition is constant, the intensity of the picture increases as the height of the targets is increased.