• Journal of KIISE:Software and Applications
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• v.27 no.4
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• pp.422-431
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• 2000

This paper proposes a new codebook generation method, called a PCA-Based VQ, that incorporates the PCA (Principal Component Analysis) technique into VQ (Vector Quantization) codebook design. The PCA technique reduces the data dimensions by transforming input image vectors into the feature vectors. The cluster of feature vectors in the transformed domain is bisectioned into two subclusters by an optimally chosen partitioning hyperplane. We expedite the searching of the optimal partitioning hyperplane that is the most time consuming process by considering that (1) the optimal partitioning hyperplane is perpendicular to the first principal axis of the feature vectors, (2) it is located on the equilibrium point of the left and right cluster's distortions, and (3) the left and right cluster's distortions can be adjusted incrementally. This principal axis bisectioning is successively performed on the cluster whose difference of distortion between before and after bisection is the maximum among the existing clusters until the total distortion of clusters becomes as small as the desired level. Simulation results show that the proposed PCA-based VQ method is promising because its reconstruction performance is as good as that of the SOFM (Self-Organizing Feature Maps) method and its codebook generation is as fast as that of the K-means method.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.2
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• pp.261-267
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• 2014

Various types of external loads can be applied to the tunnel structure. In a shield tunnel, the vibration from the train may affect the behavior of the adjacent ground. In this study, the railway-induced vibration was estimated and applied to the shield tunnel through 3D numerical simulation. The effective stress analysis based on the finite difference method and Finn model was performed to investigate the potential of liquefaction below the tunnel. Furthermore, pore water pressure and displacement were monitored on a time domain; consequently, the liquefaction potential and dynamic response of the shield tunnel were analyzed. Consequently, it is confirmed that the generation of excess pore water pressure by train-induced vibrating load, however, the amount does not meaningfully affect the potential of liquefaction.

• Structural Engineering and Mechanics
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• v.66 no.6
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• pp.677-691
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• 2018

Reliability assessment of complex structures using simulation methods is time-consuming. Thus, surrogate models are usually employed to reduce computational cost. AK-MCS is a surrogate-based Active learning method combining Kriging and Monte-Carlo Simulation for structural reliability analysis. This paper proposes three modifications of the AK-MCS method to reduce the number of calls to the performance function. The first modification is related to the definition of an initial Design of Experiments (DoE). In the original AK-MCS method, an initial DoE is created by a random selection of samples among the Monte Carlo population. Therefore, samples in the failure region have fewer chances to be selected, because a small number of samples are usually located in the failure region compared to the safe region. The proposed method in this paper is based on a uniform selection of samples in the predefined domain, so more samples may be selected from the failure region. Another important parameter in the AK-MCS method is the size of the initial DoE. The algorithm may not predict the exact limit state surface with an insufficient number of initial samples. Thus, the second modification of the AK-MCS method is proposed to overcome this problem. The third modification is relevant to the type of regression trend in the AK-MCS method. The original AK-MCS method uses an ordinary Kriging model, so the regression part of Kriging model is an unknown constant value. In this paper, the effect of regression trend in the AK-MCS method is investigated for a benchmark problem, and it is shown that the appropriate choice of regression type could reduce the number of calls to the performance function. A stepwise approach is also presented to select a suitable trend of the Kriging model. The numerical results show the effectiveness of the proposed modifications.

• Journal of Biomedical Engineering Research
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• v.28 no.5
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• pp.636-646
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• 2007

Adequate postural control depends on the spatial and temporal integration of vestibular, visual, and somatosensory information. Especially, the musculoskeletal function is essential to maintain the postural control. The experimental studies was performed on the muscular activities in the lower extremities during maintaining and moving exercises on an unstable platform with Magneto Rheological(MR) dampers. The unstable platform of the developed system was controlled by electric currents to the MR dampers. A subject executed the maintaining and moving exercises which are presented through the display monitor. The electromyographies of the eight muscles in lower extremities were recorded and analyzed in the time and the frequency domain: the muscles of interest were rectus femoris(RF), biceps femoris(BF), tensor fasciae latae(TFL), vastus lateralis(VL), vastus medialis(VM), gastrocnemius(Ga), tibialis anterior(TA), Soleus(So). The experimental results showed that the muscular activities differed in the four moving exercises and the nine maintaining exercises. For the anterior-posterior pattern, the TA showed highest activities; for the left-right pattern, the TFL; for the 45, $-45^{\circ}$ pattern, the TFL and TA. Also, the rate of the increase in the muscular activities were affected by the condition of the unstable platform with MR dampers for the maintaining and moving exercises. The experimental results suggest that the choice of different maintaining and moving exercises could selectively train different muscles in various intensity. Futhermore, the findings suggested that the training using this system can improve the ability of postural control.

• Nutrition Research and Practice
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• v.4 no.1
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• pp.36-42
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• 2010

A cross-sectional survey was used to investigate the rates of overweight and obesity (BMI$\geq$25), and eating attitudes among college students. Data were collected at a large southeastern university. Adolescents (ages 18-25) self-reported weight and height (to calculate BMI), and, in addition to demographic information, completed the eating attitudes (EAT 26) scale to assess dieting tendencies. Significance of the mean BMI differences between gender and ethnic background were assessed by one-way analysis of variance (one-way ANOVA). Chi-square was used to determine whether the rate of those with BMI$\geq$25 between gender and ethnic background was statistically significant. While 52.7% of the students' BMI were within the normal weight category, 15.2% were underweight, 21.3% were overweight, and 10.8% were obese. The rate of BMI$\geq$25 differed by gender and ethnicity, with males and African Americans having higher rates. About 12 % of the participants reported disturbed eating behavior, which is lower than previously reported. Even so, results support the generally held belief that disturbed eating attitudes and unhealthy dieting are common among college students, especially among females. At the same time, disturbed eating attitudes are not just the domain of young female students; about 10% of college males reported disturbed eating attitudes. Findings of this study call for obesity prevention/intervention and lifestyle modification outreach programs among college students. Weight status and unhealthy eating behaviors of college. students should be a concern to health care professionals. While obese young adults will likely remain obese throughout their adult life, excessive dieting among students, which is linked to eating disorders and other health hazards, does not provide healthy and adequate alternatives for maintaining a normal BMI. Implications for obesity prevention programs are discussed.

• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.117-126
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• 2003

A semiotic approach to modern visual arts has emerged since French post-structuralism was introduced to Anglo -American academics by "deconstruction" or "postmodernism." It views a work of art as a sign, which is its methodical assumption ana at the same time makes its application more accessible In the milieu of modern visual arts'effort to be intimate to with general audience, modern art photography is now faced with the request to be a familar and universal domain instead of being left only in photo books as artistic and academic achievements More specifically, various photo images 1mm such visual media as newspapers TVs, and computer graphics to such megaexhibitions as "Gwangju Biennale," "Media City Seoul," and "Pusan International Art Festival," are main objects of s030y. A coherent and scientific analysis of visual semitotics is still on the way; however, it is an urgent task how to read and interpret a photo image with multiple meanings This study argues that visual semiotics can be a powerful tool to enhance the understanding of art photography. After all, semiotics is a product of age; we live in the age of legibility, that is, of reading the work of art well as the social events and phenomena.rk of art well as the social events and phenomena.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.253-260
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• 1989

The time domain methods of estimating the attenuation coefficient are generally based on the analysis of statisical properties of the reflected echoes form an attenuating medium. Hence, it is often required to have a large number of data samples in order to obtain a statistically stable estimation result. In the attenuation estimation problem, this means that many different speckle patterns are required in the spatial resolution volume of an attenLlation image. In this paper, by using the fact that the speckle pattern Is sensitive to the point spread function of the ultrasound beam, we suggest a method to generate the statiscally uncorrelated or slightly correlated data samples in a given region by rotating a linear transducer and carrying out lateral scans for all rotating angles. This technique is applied to the entropy method for attenuation estimation proposed recently by the authors where the performance is verified by experiments using a tissue equivalent phantom.

• Journal of the Korea Society for Simulation
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• v.25 no.2
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• pp.41-49
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• 2016

Counter Fire Operations can be characterized as having a system of systems that key features include situational awareness, command and control systems and highly responsive strike achieved by precision weapons. Current modeling methodology cannot provide an appropriate methodology for a system of systems and utilizes modeling and simulation tools to implement analytic options which can be time consuming and expensive. We explain developing methodology and tools for the effectiveness analysis of the counter fire operations under Network Centric Warfare Environment and suggest how to support a efficient decision making with the methodology and tools. Theater Counter Fire Operations tools consist of Enemy block, ISR block, C2 block and Shooter block. For the convenience of using by domain expert or non simulation expert, it is composed of the environments that each parameter and algorithm easily can be altered by user.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.831-838
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• 2016

The disaster preventing system using vegetation has been growing in the field of coastal engineering in recent years. To analyze wave and flow fields under nonlinear interactions between tsunami and vegetation, the purpose of this study is to evaluate newly-developed 3-D numerical wave tank including energy dissipation by tsunami-vegetation interaction based on existing N-S solver with porous body model. Comparing numerical results using mean drag coefficient and dynamic drag coefficient due to Reynolds number to existing experimental results it is revealed that computed results considering the dynamic drag coefficient are in good agreement with the laboratory test results for time-domain waveform. In addition, the calculated transmission coefficients of solitary waves in various vegetation densities and incident wave heights are also in good agreement with the experimental values. This confirms the validity and effectiveness of the developed 3-D numerical wave tank with the fluid resistance by vegetation.

• The Korean Journal of Malacology
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• v.29 no.2
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• pp.155-161
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• 2013

Cathepsins are lysosomal/cysteine proteases belong to papain family (C1 family) that is involved in intracellular protein degradation, antigen processing, hormone maturation, and immune responses. In this study, member of cathepsin family was identified from Manila clam (Mc-Cathepsin D) and investigated the immune response against brown ring disease (BRD) causing Vibrio tapetis challenge. The identified Mc-Cathepsin D gene encodes characteristic features typical for the cathepsin family including eukaryotic and viral aspartyl protease signature domain and two highly conserved active sites ($^{84}VVFDTGSSNLWV^{95}$ and $^{270}IADTGTSLLAG^{281}$). Moreover, MC-Cathepsin D shows higher identity values (-50-70%) and conserved amino acids with known cathepsin D members. Transcriptional results (by quantitative real-time RT-PCR) showed that Mc-Cathepsin D was expressed at higher levels in gills and hemocytes than mantle, adductor muscle, foot, and siphon. After the V. tapetis challenge under laboratory conditions, Mc-Cathepsin D mRNA was up-regulated in gills and hemocytes. Present study indicates that Mc-Cathepsin D is constitutively expressed in different tissues and potentially inducible when infecting BRD by V. tapetis. It is further suggesting that Mc-Cathepsin D may be involved in multiple role including immune response reactions against BRD.