• Smart Structures and Systems
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• v.16 no.2
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• pp.243-262
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• 2015

Optimal sensor placement (OSP) is a critical issue in construction and implementation of a sophisticated structural health monitoring (SHM) system. The uncertainties in the identified structural parameters based on the measured data may dramatically reduce the reliability of the condition evaluation results. In this paper, the information entropy, which provides an uncertainty metric for the identified structural parameters, is adopted as the performance measure for a sensor configuration, and the OSP problem is formulated as the multi-objective optimization problem of extracting the Pareto optimal sensor configurations that simultaneously minimize the appropriately defined information entropy indices. The nondirective movement glowworm swarm optimization (NMGSO) algorithm (based on the basic glowworm swarm optimization (GSO) algorithm) is proposed for identifying the effective Pareto optimal sensor configurations. The one-dimensional binary coding system is introduced to code the glowworms instead of the real vector coding method. The Hamming distance is employed to describe the divergence of different glowworms. The luciferin level of the glowworm is defined as a function of the rank value (RV) and the crowding distance (CD), which are deduced by non-dominated sorting. In addition, nondirective movement is developed to relocate the glowworms. A numerical simulation of a long-span suspension bridge is performed to demonstrate the effectiveness of the NMGSO algorithm. The results indicate that the NMGSO algorithm is capable of capturing the Pareto optimal sensor configurations with high accuracy and efficiency.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.1-8
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• 2018

K-means algorithm is one of the most popular and widely used clustering method because it is easy to implement and very efficient. However, this method has the limitation to be used with fixed number of clusters because of only considering the intra-cluster distance to evaluate the data clustering solutions. Silhouette is useful and stable valid index to decide the data clustering solution with number of clusters to consider the intra and inter cluster distance for unsupervised data. However, this valid index has high computational burden because of considering quality measure for each data object. The objective of this paper is to propose the fast and simple speed-up method to overcome this limitation to use silhouette for the effective large-scale data clustering. In the first step, the proposed method calculates and saves the distance for each data once. In the second step, this distance matrix is used to calculate the relative distance rate ($V_j$) of each data j and this rate is used to choose the suitable number of clusters without much computation time. In the third step, the proposed efficient heuristic algorithm (Group search optimization, GSO, in this paper) can search the global optimum with saving computational capacity with good initial solutions using $V_j$ probabilistically for the data clustering. The performance of our proposed method is validated to save significantly computation time against the original silhouette only using Ruspini, Iris, Wine and Breast cancer in UCI machine learning repository datasets by experiment and analysis. Especially, the performance of our proposed method is much better than previous method for the larger size of data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.459-464
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• 2007

Resolution 122 requires to study power limitation applicable for HAPS ground stations to facilitate sharing with space station receivers in 47/48GHz bands. ITU-R Recommendation 1481-1 recommends to improve the side lobe characteristics of HAPS ground station antenna for frequency sharing between FSS system and HAPS system. In this paper, we propose the maximum allowable off-axis e.i.r.p. level of HAPS ground station antennas by considering power limitation to HAPS ground station in Resolution 122, and by improving the side lobe characteristics of HAPS ground station antennas in Recommendation SF.1481-1. The simulation results show that the unfeasible sharing distance between HAPS ground station and FSS earth station can be reduced remarkably, and give the possibility of frequency sharing between two above systems.

• Journal of radiological science and technology
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• v.29 no.3
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• pp.125-132
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• 2006

The PET/CT scanner is an evolution in image technology. The two modalities are complementary with CT and PET images. The PET scan images are well known as low resolution anatomic landmak, but such problems may help with interpretation detailed anatomic framework such as that provided by CT scan. PET/CT offers some advantages-improved lesion localization and identification, more accurate tumor staging. etc. Conventional PET employs tranmission scan require around 4 min./bed position and 30 min. for whole body scan. But PET/CT scanner can reduced by 50% in whole body scan. Especially nowadays PET scanner LSO scintillator-based from BGO without septa and operate in 3-D acquisition mode with multidetectors CT. PET/CT scanner fusion problems solved through hardware rather than software. Such device provides with the capability to acquire accurately aligned anatomic and functional images from single scan. It is very important to effective detection from gamma ray source in PETdetector. And can be offer high quality diagnostic images. So we have study about detection processing of PET detector and high quality imaging process.

• Journal of Nutrition and Health
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• v.38 no.1
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• pp.3-10
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• 2005

The study analyzed the lipid patterns and fatty acid compositions of serum and liver tissues in groups of Sparague-Dawley rats. Some of the groups were fed with an basal diet, which contained com oil (C), grape seed oil (GSO), or perilla oil (P), and the others were fed with a high fat diet, which had cholesterol (1%) and lard (10%) mixed with corn oil (CHF), grape seed oil (GSHF), or perilla oil (PHF). The amount of dietary intake was higher for the basal diet groups than the high fat diet groups. And diet efficiency was significantly low in the group of rats fed with the basal diet mixed with perilla oil. From the analysis of the serum lipid patterns, a significant decrease in total lipid concentration was observed in the group of rats fed on the basal diet mixed with perilla oil and the high fat diet group. The levels of triglyceride and phospholipid were significantly low in the basal diet group when perilla oil or grape seed oil was involved. The ordinary diet groups showed significantly higher in HDL-C than the high fat diet groups. There was no significant difference among the basal diet groups, whether the diet was mixed with grape seed oil, perilla oil, or com oil. However, a significant increase in HDL-C was observed in the group of rats fed with the high fat diet containing perilla oil. For LDL-C, there was a significant difference between the high fat diet groups and the basal diet groups. LDL-C was especially low in the group of rats fed with the high fat diet to which perilla oil was added, and the grape seed-added high fat diet group showed a decreasing tendency in LDL-C. The content of total fat, total cholesterol, and triglyceride was the lowest in the group of rats fed with the perilla oil-containing basal diet, and this group was followed in order by the grape seed oil-containing diet group and com oil-containing diet group. In the analysis of the fatty-acid composition in liver tissue, the high fat diet groups showed an increase in saturated fatty acids and polyunsaturated fatty acids, but a decrease in mono unsaturated fatty acids when compared to the basal diet groups. The composition ratio of fatty acids varied according to which type of oil the diet contains. Our finding suggest that grape seed oil was an apparent diet effect on the fatty-acid composition.

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.325-329
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• 2004

Purpose: Usefulness of mouse liver S9 fraction was evaluated for the measurement of the metabolites in the in vitro metabolism study of $^{18}F$-labeled radiotracers. Materials and Methods: Mouse liver S9 fraction was isolated at au early step in the course of microsome preparation. The in vitro metabolism studies were tarried out by incubating a mixture containing the radiotracer, S9 fraction and NADPH at $37^{\ciirc}C$, and an aliquot of the mixture was analyzed at the indicated time points by radio-TLC. Metabolic defluorination was further confirmed by the incubation with calcium phosphate, a bone mimic. Results: The radiotracer $[^{18}F]1$ underwent metabolic defluorination within 15 min, which was consistent with the results of the in vivo method and the in vitro method using microsome. Radiotracer $[^{18}F]2$ was metabolized to three metabolites including $4-[^{18}F]fluorobenzoic$ acid within 60 min. It is likely that the one of these metabolites at the origin of radio-TLC was identical with the one that obtained from the in vivo and in vitro (microsome) method. Compared with the in vitro method using microsome, the method using S9 fraction gave a similar pattern of the metabolites but with a different ratio, which can be explained by the presence of cytosol in the S9 fraction. Conclusion: These results suggest that the findings of the in vitro metabolism studies using S9 fraction can reflect the in vivo metabolism of novel radiotracers in the liver. Moreover, this method can be used as a tool to determine metabolic defluorination along with calcium phosphate absorption method.