• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.201-209
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• 1998

The presence of elevated temperature can alter significantly the structural response of fibre-reinforced laminated composites. A thermal environment causes degradation in both strength and constitutive properties, particularly in the case of fibre-reinforced polymeric composites. Furthermore, associated thermal expansion, either alone or in combination with mechanically induced deformation, can result in buckling, large deflections, and excessively high stress levels. Consequently, it is often imperative to consider environmental effects in the analysis and design of laminated systems. Exact analytical solutions of higher-order shear deformation theory is developed to study the thermal buckling of cross-ply and antisymmetric angle-ply rectangular plates. The buckling behavior of moderately thick cross-ply and antisymmetric angle-ply laminates that are simply supported and subject to a uniform temperature rise is analyzed. Numerical results are presented for fiber-reinforced laminates and show the effects of ply orientation, number of layers, plate thickness, and aspects ratio on the critical buckling temperature and compared with those obtained using the classical and first-order shear deformation theory.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.1-10
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• 2013

Probabilistic nonlinear first ply failure loads of flat composite panels and nonlinear buckling loads of curved composite panels with cutouts are estimated to provide the more reliable main load carrying structure in the renewable energy industry and offshore structures. The response surface method approximates limit state surface to a second order polynomial form of random variables with the results of deterministic finite element analyses at given sampling design points. Furthermore, the iterative linear interpolation scheme is used to obtain a more accurate approximation of the limit state surface near the most probable failure point (MPFP). The advanced first order second moment method and the Monte Carlo method are performed on an approximated limit state surface to evaluate the probability of failure. Finally, the sensitivity of the reliability index with respect to transformed random variables is investigated to figure out the main random variables that have an effect on failures.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.131-139
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• 2009

The existing vessel monitoring system using the ground surveillance radar has a difficulty in monitoring ships continuously due to the limited range of detecting ships. For resolving this problem, we carry out a research on ship detection which is to be the core technology of vessel monitoring system for ocean monitoring using SAR imagery. There are two different methods of detecting ships in SAR imagery: detection of the ship target itself and detection of the ship wake. In this paper, we mainly focus on algorithms which detect the ship itself, and also present the accuracy test after extracting positional and directional figures of the ships. After rectifying input SAR imagery using polynomial transformation, we use Wiener filter to remove speckle noises. A labeling technique and morphological filtering in conjunction with Otsu's method are used to automatically detect the ships based on the image processing domain. For ground truth data, information from a radar system is used, which allows assessing the accuracy of the proposed method. The results show that the proposed method has the high potential in automatically detecting the ships and its positional/directional figures in a fast way.

• Science of Emotion and Sensibility
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• v.20 no.1
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• pp.75-82
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• 2017

We propose a novel method for modeling emotional dimensions using expansion of Russell's (1980) emotional dimensions (Circumplex Model). The Circumplex Model represents emotional words in two axes (Arousal, Valence). However, other researchers have insisted that location of word in Russell's model which is expressed by single point could not represent exact position. Consequently, it is difficult to apply this model in engineering fields (such as Science of Emotion & Sensibility, Human-Computer-Interaction, Ergonomics, etc.). Therefore, we propose a new modeling method which expresses emotional word not as a single point but as a region. We conducted survey to obtain actual data and derived equations using ellipse formula to represent emotional region. Furthermore, we applied ANEW and IAPS which are commonly used in many studies to our emotional model using pattern recognition algorithm. Using our method, we could solve problems with Russell's model and our model is easily applicable to the field of engineering.

• Survey Research
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• v.7 no.2
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• pp.97-122
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• 2006

Korean Longitudinal Study of Ageing(KLoSA)', launched in 2006, has developed a research network with 'Health and Retirement Study(HRS, US),' Studies on Health and Retirement in Europe(SHARE, EU),' and 'English Longitudinal Study of Ageing(ELSA, UK)'and tried to construct a mega data library. The KLoSA team has designed their research with focusing on the following three points, in order to use KLoSA for international comparative studies. First, KLoSA shares the key research areas such as family structure, health, employment, income, asset, subjective expectations with the comparable studies. Second, KLoSA team has developed the instrument to reflect the Korean culture and institutions. They considered the institutional characteristics in public pension and health care system and in employment practices. They also counted the cultural conventions in family life such as financial management and care exchange, Finally, KLoSA tries to capture the psychological characteristics of the Korean elderly by making the measurement scales more understandable.

• Korean Journal of Social Welfare
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• v.60 no.3
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• pp.129-150
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• 2008

This study examined the factors affecting service utilization of elderly residential care among long term care services recipients during long term care insurance pilot project period in Korea. Help-seeking Behavior model developed by Andersen and Newman(1973) was used to analyze the factors affecting their utilization residential care service among 1,939 long term care services recipients. Frequency and Decision Tree Regression analysis on SPSS 13.0 used. Analyses show strong significant factor is service preference(predisposing factors), and then significant factors are enabling factors such as co-residence type, household income. According to this results, need factors such as cognition disorder, problem behavior, ADL and IADL disabilities are affecting utilization behavior of elderly residential care services. These findings provide implications and suggestions about how long term care service system would be settled in Korea. And these finding provide information about target-efficient long term care continuum system to policy makers and helping professionals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10C
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• pp.1001-1009
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• 2009

In this paper, an efficient blind frequency offset estimation method for radio resource saving in orthogonal frequency division multiplexing (OFDM) systems is proposed. In the proposed method, we obtain two time different received OFDM signal blocks by using the cyclic prefix and define the cost function by using the two OFDM signal blocks. We show that the cost function can be approximately expressed as a closed form cosine function. The approximated cosine function can be obtained from three independent cost function values calculated at three different frequency offsets. In the proposed method, the frequency offset can be estimated by calculating a frequency offset minimizing the approximated cosine function without searching all the frequency offset range. Unlike the conventional methods such as MUSIC method, the accuracy of the proposed method is independent of the searching resolution since the closed form solution exists. The computer simulation shows that the performance of the proposed method is superior to those of the MUSIC and the oversampling method.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.146-151
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• 1999

We demonstrated a harmonic mode locking scheme that used regeneratie phase modulation to get a high and stable repetition rate in a figure-of-eight fiber soliton laser. From the detected beat spectra of the laser output, a sinusoidal clock freguency tone of 400 MHz, the 96th harmonics of the fundamental mode locking frequency, was extracted with a high Q filter and was used to drive the phase modulator, resulting in stable output of soliton pulse train synchronized with the modulation signal. Generated soliton pulses had FWHM pulsewidth of 930 fs and 3.1 nm linewidth, yielding pulsewidth-bandwidth product of 0.359 that was close to the transform limit. As the modulation frequency always followed the beat frequency of laser modes, stable harmonic mode locking was achieved without the adjustment of the cavity length, which has been commonly required in actively mode-locked lasers.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.201-206
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• 2008

Determining the coefficient of weathering(CW) for stone heritage plays very important role in investigation and conservation plan. In most case, CW is obtained from the empirical relation, which use the difference between sonic velocities of fresh and weathered rocks. In this paper, we measured sonic velocities for the samples from Iksan, Geochang, Wonju, Goesan and Chungju of which our stone heritages are made. We first investigate the uncertainty of velocity by portable measurement by comparing it to lab measurement. There were small difference, but we conclude that the difference is not major. However, the velocity of fresh rock differs significantly among samples: ranging from 3200 to 4400m/s. This cause a lot of error in CW estimation if we use typical fresh rock velocity as of 5000m/s. Thus accurate measurement of the velocity of fresh rock is crucial to CW estimation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.151-160
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• 2004

In the present study, Loop scheme is applied to generate smooth surfaces. To be consistent with the limit points of target surface, the initial sampling points are properly rearranged. The pointwise errors of curvature and position in the sequence of subdivision process are evaluated in the Loop subdivision scheme. A first-order shear deformable Loop subdivision triangular element which can handle transverse shear deformation of moderately thick shell are developed. The developed element is more general than the previous one based on classical shell theory, since the new one includes the effect of transverse shear deformation and has standard six degrees of freedom per node. The quartic box spline function is used as interpolation basis function. Numerical examples for the benchmark static shell problems are analyzed to assess the performance of the developed subdivision shell element and locking trouble.