• Journal of the Society of Naval Architects of Korea
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• v.51 no.4
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• pp.274-282
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• 2014

Time series of the dynamic response of a slender marine structure was predicted using quadratic Volterra series. The wave-structure interaction system was identified using the NARX(Nonlinear Autoregressive with Exogenous Input) technique, and the network parameters were determined through the supervised training with the prepared datasets. The dataset used for the network training was obtained by carrying out the nonlinear finite element analysis on the freely standing riser under random ocean waves of white noise. The nonlinearities involved in the analysis were both large deformation of the structure under consideration and the quadratic term of relative velocity between the water particle and structure in Morison formula. The linear and quadratic frequency response functions of the given system were extracted using the multi-tone harmonic probing method and the time series of response of the structure was predicted using the quadratic Volterra series. In order to check the applicability of the method, the response of structure under the realistic ocean wave environment with given significant wave height and modal period was predicted and compared with the nonlinear time domain simulation results. It turned out that the predicted time series of the response of structure with quadratic Volterra series successfully captures the slowly varying response with reasonably good accuracy. It is expected that the method can be used in predicting the response of the slender offshore structure exposed to the Morison type load without relying on the computationally expensive time domain analysis, especially for the screening purpose.

• Journal of Chest Surgery
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• v.41 no.6
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• pp.751-754
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• 2008

Angiosarcoma is the most common primary intracardiac malignancy, but many published papers have reported it to be rather rare. The prognosis of angiosarcoma is known to be very poor, and the treatment of choice has been surgery until recently, but many centers currently tend to try multi modal therapies, including chemotherapy and radiotherapy. In this report, we present a rare case in which an intracardiac angiosarcoma could have threatened the patient's life in short time by the rapid progression of the tumor, which caused right atrial rupture.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.83-92
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• 2005

The purpose of the paper is to analyze an effectiveness before and after implementation of the median arterial bus lanes operation. The paper includes a speed analysis based on the Downs-Thomson Paradox theory, and a reliability analysis based on variance analysis of arrival time. According to the speed analysis, some road sections are now under phase 2 according to the Downs-Thomson Paradox, which is a state in which the bus speeds are greater than the car speeds. In the future it is predicted that cars and buses will reach an equilibrium speed which is in phase 3 of the multi-modal equilibrium theory. According to the reliability analysis of arrival time at each bus stop, in roads of median arterial bus lanes. the variance of arrival time is generally smaller than after the scheme implemented in eight months later.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.2 s.72
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• pp.125-138
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• 2006

The use of system identification approaches for damage detection has been expanded in recent years owing to the advancements in data acquisition system andinformation processing techniques. Soft computing techniques such as neural networks and genetic algorithm have been utilized increasingly for this end due to their excellent pattern recognition capability. In this study, damage detection of bridge structures using neural networks technique based on the modal properties is presented, which can effectively consider the modeling uncertainty in the analysis model from which the training patterns are to be generated. The differences or the ratios of the mode shape components between before and after damage are used as the input to the neural networks in this method, since they are found to be less sensitive to the modeling errors than the mode shapes themselves. Two numerical example analyses on a simple beam and a multi-girder bridge are presented to demonstrate the effectiveness and applicability of the proposed method.

• Computers and Concrete
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• v.3 no.1
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• pp.1-15
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• 2006

The seismic safety of reinforced concrete containment building can be evaluated by probabilistic analysis considering randomness of earthquake, which is more rational than deterministic analysis. In the safety assessment of earthquake-resistant structures by the deterministic theory, it is not easy to consider the effects of random variables but the reliability theory and random vibration theory are useful to assess the seismic safety with considering random effects. The reliability assessment of reinforced concrete containment building subjected to earthquake load includes the structural analysis considering random variables such as load, resistance and analysis method, the definition of limit states and the reliability analysis. The reliability analysis procedure requires much time and labor and also needs to get the high confidence in results. In this study, random vibration analysis of containment building is performed with random variables as earthquake load, concrete compressive strength, modal damping ratio. The seismic responses of critical elements of structure are approximated at the most probable failure point by the response surface method. The response surface method helps to figure out the quantitative characteristics of structural response variability. And the limit state is defined as the failure surface of concrete under multi-axial stress, finally the limit state probability of failure can be obtained simply by first-order second moment method. The reliability analysis for the multiaxial strength limit state and the uniaxial strength limit state is performed and the results are compared with each other. This study concludes that the multiaxial failure criterion is a likely limit state to predict concrete failure strength under combined state of stresses and the reliability analysis results are compatible with the fact that the maximum compressive strength of concrete under biaxial compression state increases.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.2
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• pp.16-24
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• 1997

This paper proposes a modified GA whose individuals have their own ages. Thus, a chromosome will die only when the age becomes zero, as a result, the population size of this method increases according to the generations. This helps a GA to preserve the good characteristics of a few chromosomes during several generations if the ages are evaluated with fitness values. As a result, the performance of the method is better than that of existing ones. A multi-modal function optimization problem is employed to simulate the performance of this method. To show the effective:~esso f ageing paradigm, three ageing evaluation methods are introduced. A paper whose itlea is similar to that of ours have been published in a conference. We also experimented a method that showed the best performance in the paper. Original simple GA was also experimented and the performance is compared with others. However, the perforniance of the previous method shows worse than that of our methods in some aspects because the previous method didn't take the fitness value into account in the selection process.

• Journal of the Korean Data and Information Science Society
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• v.26 no.3
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• pp.593-610
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• 2015

Adaptive Rejection Sampling (ARS) method is a well-known random number generator to acquire a random sample from a probability distribution, and has the advantage of improving the proposal distribution during the sampling procedures, which update it closer to the target distribution. However, the use of ARS is limited since it can be used only for the target distribution in the form of the log-concave function, and thus various methods have been proposed to overcome such a limitation of ARS. In this paper, we attempt to compare five random number generators based on ARS in terms of adequacy and efficiency. Based on empirical analysis using simulations, we discuss their results and make a comparison of five ARS-based methods.

• Journal of the Korean Society of Costume
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• v.53 no.4
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• pp.1-16
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• 2003

The purpose of this study is to investigate the sensibility images of Korean Traditional Chumoni. The detailed methodology of this study is as follows. Selections of stimuli to analyse the sensibility images of Korean Traditional Chumoni were made up of 15 stimuli. The survey has been done for the 15 slide stimuli with semantic differential hi-polar scales which are consist of 23 couples of sensibility words. The subjects were 150 female students majoring in clothing and textile. 150 male students majoring in other department and 150 female students majoring in other department in the twenties between 2001. 3. 30 and 2001. 4. 4. The obtained data were analyzed by factor analysis, cluster analysis. ANOVA. The major finds were as follows. 1. To explain the hierarchy of the sensibility of Korean Traditional Chumoni, two image groups were classified, one is noble and characteristic image the other is splendid and intensive image. Finally it represented noble and splendid image. 2. As result of the factor analysis. 3 factors which are Attraction, Decorativeness, Gravity were found to be constructing factors for the sensibility images of Korean Traditional Chumoni. 3. By cluster analysis, 4 clusters were determined according to Korean Traditional Chumoni. Cluster 1 is splendid. multi-colored and realistic in patteren. Cluster 2 is consist of 'true chumonis' and one-colored. Cluster 3 is modal in pattern. Cluster 4 is simple without any decorations. As to the difference of image of Korean Traditional Chumoni, there were significant differences amang 3 factors by cluster Cluster 1 was found most attractive and grave. Cluster 2 was found most decorative. 4. As to the difference of image of Korean Traditional Chumoni, there were significant differences amang 3 factors by decoration. Gold foil was found most attractive and grave. Embroidery was found most decorative. 5. As to the difference of image of Korean traditional chumoni, there were differences in Decorativeness and Gravity by sex and there were differences in Attraction by major.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.455-466
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• 2013

The purpose of this study was to develop a school violence prevention program "Modujikimi" for young children to be embedded in IrobiQ, the teacher assistive robot. The themes of this program consisted of basic character education, bullying prevention education and sexual violence prevention education. The activity types included large group, individual and small group activities, free choice activities, and finally parents' education, which included poems, fairy tales, music, art, sharing stories. Finally, the multi modal functions of the robot were employed: image on the screen, TTS (Text To Speech), touch function, recognition of sound and recording system. The robot content was demonstrated to thirty early childhood educators whose acceptability of the content was measured using questionnaires. And also the content was applied to children in daycare center. As a result, majority of them responded positively in acceptability. The results of this study suggest that the further research is needed to improve two-way interactivity of teacher assistive robot.

• Korean Journal of Materials Research
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• v.17 no.7
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• pp.390-395
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• 2007

We systematically investigated the effects of InAs coverage variation, two-step annealing and an asymmetric InGaAs quantum well (QW) on the structural and optical characteristics of InAs quantum dots (QDs) by using atomic force microscopy (AFM), transmission electron microscopy (TEM) and photoluminescence (PL) measurement. The transition of size distribution of InAs QDs from bimodal to multi-modal was noticeably observed with increasing InAs coverage. By means of two-step annealing, it is found that significant narrowing of the luminescence linewidth (from 132 to 31 meV) from the InAs QDs occurs together with about 150 meV blueshift, compared to as-grown InAs QDs. Finally, the InAs QDs emitting at longer wavelength of $1.3\;{\mu}m$ with narrow linewidth were grown by an asymmetric InGaAs QW. The excited-state transition for the InAs QDs with an asymmetric InGaAs QW was not noticeably observed due to the large energy-level spacing between the ground states and the first excited states. The InAs QDs with an asymmetric InGaAs QW will be promising for the device applications such as $1.3\;{\mu}m$ optical-fiber communication.