• Title/Summary/Keyword: Level Set method

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Banding Artifacts Reduction Method in Multitoning Based on Threshold Modulation of MJBNM (MJBNM의 임계값 변조를 이용한 멀티토닝에서의 띠 결점 감소 방법)

  • Park Tae-Yong;Lee Myong-Young;Son Chang-Hwan;Ha Yeong-Ho
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.43 no.2 s.308
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    • pp.40-47
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    • 2006
  • This paper proposes a multitoning method using threshold modulation of MJBNM(Modified Jointly Blue Noise Mask) for banding artifacts reduction. As banding artifacts in multitoning appear as uniform dot distributions around the intermediate output levels, such multitone output results in discontinuity and visually unpleasing patterns in smooth transition regions. Therefore, to reduce these banding artifacts, the proposed method rearranges the dot distribution by introducing pixels in the neighborhood of output levels that occurs banding artifacts. First of all principal cause of banding artifacts are analyzed using mathematical description. Based on this analytical result, a threshold modulation technique of MJBNM which takes account of chrominance error and correlation between channels is applied. The original threshold range of MJBNM is first scaled linearly sot that the minimum and maximum of the scaled range include two pixel more than adjacent two output levels that cover an input value. In an input value is inside the vicinity of any intermediate output levels produce banding artifacts, the output is set to one of neighboring output levels based on the pointwise comparison result according to threshold modulation parameter that determines the dot density and distribution. In this case, adjacent pixels are introduced at the position where the scaled threshold values are located between two output levels and the minimum and maximum threshold values. Otherwise, a conventional multitoning method is applied. As a result, the proposed method effectively decreased the appearance of banding artifacts around the intermediate output levels. To evaluate the quality of the multitone result, HVS-WRMSE according to gray level for gray ramp image and S-CIELAB color difference for color ramp image are compared with other methods.

A New Method of Registering the XML-based Clinical Document Architecture Supporting Pseudonymization in Clinical Document Registry Framework (익명화 방법을 적용한 임상진료문서 등록 기법 연구)

  • Kim, Il-Kwang;Lee, Jae-Young;Kim, Il-Kon;Kwak, Yun-Sik
    • Journal of KIISE:Software and Applications
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    • v.34 no.10
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    • pp.918-928
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    • 2007
  • The goal of this paper is to propose a new way to register CDA documents in CDR (Clinical Document Repository) that is proposed by the author earlier. One of the methods is to use a manifest archiving for seamless references and visualization of CDA related files. Another method is to enhance the CDA security level for supporting pseudonymization of CDA. The former is a useful method to support the bundled registration of CDA related files as a set. And it also can provide a seamless presentation view to end-users, once downloaded, without each HTTP connection. The latter is a new method of CDA registration which can supports a do-identification of a patient. Usually, CDA header can be used for containing patient identification information, and CDA body can be used for diagnosis or treatment data. So, if we detach each other, we can get good advantages for privacy protection. Because even if someone succeeded to get separated CDA body, he/she never knows whose clinical data that is. The other way, even if someone succeeded to get separated CDA header; he/she doesn't know what kind of treatment has been done. This is the way to achieve protecting privacy by disconnecting association of relative information and reducing possibility of leaking private information. In order to achieve this goal, the method we propose is to separate CDA into two parts and to store them in different repositories.

A study on the oral health behavior of some dental hygiene students and other majors (일부 치위생과 학생과 일반계열 학생의 구강건강행위에 관한 연구)

  • Jeong, Mi-Kyoung;Kim, Yoon-Mi;Hong, Sae-Young
    • Journal of Korean society of Dental Hygiene
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    • v.11 no.5
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    • pp.615-627
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    • 2011
  • Objectives : The study has three aims: 1) to assess the perceptions, attitudes, and behaviors of dental hygiene students and other college students towards oral and dental care, 2) to provide grounds for developing an oral and dental health educational program, and 3) to improve the oral and dental health status among the college student population. Methods : The subjects in this study were 520 students who included dental hygiene students from J health college and other majors from a four-year university located in Seoul. The survey was conducted from September, 2010, to June 3, 2011. The collected 507 questionnaires were analyzed. The collected data were analyzed by the statistical package SPSS WIN 12.0, and the level of significance was set at 0.05. Results : 1. As for a daily toothbrushing frequency, the largest number of the students brushed their teeth three times a day, and the dental hygiene students did that more often than the other majors(p<0.001). Concerning awareness of the toothbrushing method and the time for the change of the toothbrush, the rolling method was more prevailing among the dental hygiene students than the others(p<0.001). 2. In regard to education experience about the toothbrushing method and satisfaction with the existing toothbrushing method, 64.7% of respondents ever received education about the toothbrushing method(p<0.001). 3. As to scaling experience and gingival bleeding, the dental hygiene students had more scaling experiences(p<0.001), and the other majors who underwent gingival bleeding from time to time outnumbered the dental hygiene students who did(p<0.01). 4. In relation to subjective oral health status, the dental hygiene students found themselves to be in better oral health than the other majors(p<0.001), and the latter had more parts of the mouth in which they didn't feel well than the former(p<0.01). The dental hygiene students were more concerned about their oral health(p<0.001) and felt more uncomfortable in chewing(p<0.05). The other majors felt more uncomfortable in pronunciation(p<0.01). Conclusions : The results of this study indicated that dental hygiene students strongly recognized the importance of knowledge, motivation, and self-care behaviors, and attitudes towards oral health and dental care compared to other college students. It suggested that regular educational programs for the college student population should be implemented to increase their concern for oral and dental issues and to improve their oral and dental health status.

An Experimental Study on the Application of End-Expanded Soil Nailing Method (선단확장식 소일네일링 공법의 적용성에 관한 실험적 연구)

  • Lee, Sang-Eun;Jang, Yun-Ho;Moon, Chang-Yeul;Jeong, Gyo-Cheol;Park, Young-Sun
    • The Journal of Engineering Geology
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    • v.17 no.4
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    • pp.525-534
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    • 2007
  • The peculiarity of end-expanded soil nailing method(EESNM) is in fixing the wedge-type steel body spreaded by collars and grouting its surroundings by cement milk within soils, after extending hole bottom over drilling hole diameter with top drill bit. The present study was done to establish the effect of this method. Laboratory model test were carried out to investigate the behavior characteristics with the performance of the pull-out test and failure experiment, after preparing soil test box having 1,300mm length, width 1,000mm, and height 1,100mm, and the same experimental condition was set up to compare with the general soil nailing method(GSNM). The pull-out force of about 23 percentage was increased, and the horizontal displacements 1.2 from 9.1 percentage in soil-nailed wall decreased in EESNM compare with GSNM. The axial force acting on nail increased considerably at load level over 7 ton in EESNM and 5 ton in GSNM. The predicted failure line from the maxima analyzed by axial tensile strain located at long distance from soil-nailed wall in EESNM. The EESNM demonstrated the superiority of reinforcement effect in comparison with GSNM from the results above mentioned.

The studies about the weight-changes during pregnancy and the condition of mother and infant (임신 중 체중변화와 임부 및 신생아 상태에 관한 연구)

  • Park, Kwang-Hee
    • Korean Parent-Child Health Journal
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    • v.4 no.1
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    • pp.68-81
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    • 2001
  • This research is to study about the weight-change of a pregnant woman, conditions of the woman and an infant. The weight-change of a mother during pregnancy was observed and that was expressed as the basis on the body mass index of a mother before pregnancy. The effects of weight-changes on both the discomfort, complications of pregnant mother and the condition of an infant were also investigated. Thus we set a purpose that this study would help pregnant woman and an infant to maintain and enhance their health conditions by proper weight control through nursing mediation. This study was performed in a certain hospital of university in seoul from Feb. 1. 2000 to Mar. 31. 2000. We explained the purpose of this study to the hospital institution and obtained consent of investigation. 152 inpatients who were in condition from PA 37 weeks to PA 42 weeks were the subject of this study. The research materials were made through of question paper that inpatients make answer by themselves and investigation paper. The question paper was about general background, weight and height before pregnancy and discomfort of the physical degree. And the investigation paper was about parity, maternal weight(late pregnancy), high pregnancy, delivery method, hemoglobin level, Apgar score, fetal weight. Physical discomfort was measured using the implement made by Kim hae won(1996) (chronbach's ${\alpha}=0.85$). SPSS was used to do statistics for managing and analyzing data. The results of this study were like followings. 1. The mean value of gained weight during pregnancy was about 13.8kg within from 3 kg to 26 kg. Among 152 research candidates, the gained weight of 80(52.6%) candidates remained within an ideal range. But that of 37 candidates(24.3%) became less than the ideal range. Also that of 35 candidates(23.0%) became over than the ideal range. 2. In the investigation of the relation between the weight change of a pregnant woman and her condition, the scores to represent physical discomfort were middle in all candidates. And the physical discomfort of over weight-gained group was more than that of low weight-gained group, but there was no difference in statistics(F=0.234, p=0.791). The weight-changes of pregnant woman didn't have an influence with the high risk of pregnancy(F=0.509, p=0.477). Also, the weight-changes didn't have an influence on delivery method($x^2=3.825$, p=0.148). However, in the investigation of the relation between weight-change and hemoglobin level, the change of hemoglobin level was highest in over weight gained group(F=3.062, p=0.05). 3. In the investigation of the weight-change of pregnant woman and the condition of infant. the weight changes didn't have an influence on both 1 min Apgar score(F=0.157, p=0.855) and 5 min Apgar score(F=0.030, p=0.970) of infant. Also, in the investigation of weight-change of a pregnant woman and weight difference of a infant with Pearson Correlation Coefficient, the weight-change of a pregnant woman affected vastly the weight of a infant. It was also found that the more pregnant woman gained in weight, the more did gain weighty infants. This relation was in net proportion(r=0.256, p=0.001). In conclusion, these results suggest that the weight-changes during pregnancy in Korea women of these days are more increased than that of the past days and individual variation in weight-changes is very high. Also, these results suggest that the changed hemoglobin level of a mother and weight of an infant were meaningfully affected by the weight-changes of a pregnant woman during pregnancy. However, the physical discomfort of a pregnant woman, the high risks of pregnancy, the delivery method and Apgar score of an infant were not affected by the weight-changes during pregnancy. Because the recommendation suggesting the ideal weight-change, used this study, is basis on the subject of American women, therefore, these results also suggest the necessity of such recommendation which is subject to Korean women.

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Optimization of Support Vector Machines for Financial Forecasting (재무예측을 위한 Support Vector Machine의 최적화)

  • Kim, Kyoung-Jae;Ahn, Hyun-Chul
    • Journal of Intelligence and Information Systems
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    • v.17 no.4
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    • pp.241-254
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    • 2011
  • Financial time-series forecasting is one of the most important issues because it is essential for the risk management of financial institutions. Therefore, researchers have tried to forecast financial time-series using various data mining techniques such as regression, artificial neural networks, decision trees, k-nearest neighbor etc. Recently, support vector machines (SVMs) are popularly applied to this research area because they have advantages that they don't require huge training data and have low possibility of overfitting. However, a user must determine several design factors by heuristics in order to use SVM. For example, the selection of appropriate kernel function and its parameters and proper feature subset selection are major design factors of SVM. Other than these factors, the proper selection of instance subset may also improve the forecasting performance of SVM by eliminating irrelevant and distorting training instances. Nonetheless, there have been few studies that have applied instance selection to SVM, especially in the domain of stock market prediction. Instance selection tries to choose proper instance subsets from original training data. It may be considered as a method of knowledge refinement and it maintains the instance-base. This study proposes the novel instance selection algorithm for SVMs. The proposed technique in this study uses genetic algorithm (GA) to optimize instance selection process with parameter optimization simultaneously. We call the model as ISVM (SVM with Instance selection) in this study. Experiments on stock market data are implemented using ISVM. In this study, the GA searches for optimal or near-optimal values of kernel parameters and relevant instances for SVMs. This study needs two sets of parameters in chromosomes in GA setting : The codes for kernel parameters and for instance selection. For the controlling parameters of the GA search, the population size is set at 50 organisms and the value of the crossover rate is set at 0.7 while the mutation rate is 0.1. As the stopping condition, 50 generations are permitted. The application data used in this study consists of technical indicators and the direction of change in the daily Korea stock price index (KOSPI). The total number of samples is 2218 trading days. We separate the whole data into three subsets as training, test, hold-out data set. The number of data in each subset is 1056, 581, 581 respectively. This study compares ISVM to several comparative models including logistic regression (logit), backpropagation neural networks (ANN), nearest neighbor (1-NN), conventional SVM (SVM) and SVM with the optimized parameters (PSVM). In especial, PSVM uses optimized kernel parameters by the genetic algorithm. The experimental results show that ISVM outperforms 1-NN by 15.32%, ANN by 6.89%, Logit and SVM by 5.34%, and PSVM by 4.82% for the holdout data. For ISVM, only 556 data from 1056 original training data are used to produce the result. In addition, the two-sample test for proportions is used to examine whether ISVM significantly outperforms other comparative models. The results indicate that ISVM outperforms ANN and 1-NN at the 1% statistical significance level. In addition, ISVM performs better than Logit, SVM and PSVM at the 5% statistical significance level.

Effects of firm strategies on customer acquisition of Software as a Service (SaaS) providers: A mediating and moderating role of SaaS technology maturity (SaaS 기업의 차별화 및 가격전략이 고객획득성과에 미치는 영향: SaaS 기술성숙도 수준의 매개효과 및 조절효과를 중심으로)

  • Chae, SeongWook;Park, Sungbum
    • Journal of Intelligence and Information Systems
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    • v.20 no.3
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    • pp.151-171
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    • 2014
  • Firms today have sought management effectiveness and efficiency utilizing information technologies (IT). Numerous firms are outsourcing specific information systems functions to cope with their short of information resources or IT experts, or to reduce their capital cost. Recently, Software-as-a-Service (SaaS) as a new type of information system has become one of the powerful outsourcing alternatives. SaaS is software deployed as a hosted and accessed over the internet. It is regarded as the idea of on-demand, pay-per-use, and utility computing and is now being applied to support the core competencies of clients in areas ranging from the individual productivity area to the vertical industry and e-commerce area. In this study, therefore, we seek to quantify the value that SaaS has on business performance by examining the relationships among firm strategies, SaaS technology maturity, and business performance of SaaS providers. We begin by drawing from prior literature on SaaS, technology maturity and firm strategy. SaaS technology maturity is classified into three different phases such as application service providing (ASP), Web-native application, and Web-service application. Firm strategies are manipulated by the low-cost strategy and differentiation strategy. Finally, we considered customer acquisition as a business performance. In this sense, specific objectives of this study are as follows. First, we examine the relationships between customer acquisition performance and both low-cost strategy and differentiation strategy of SaaS providers. Secondly, we investigate the mediating and moderating effects of SaaS technology maturity on those relationships. For this purpose, study collects data from the SaaS providers, and their line of applications registered in the database in CNK (Commerce net Korea) in Korea using a questionnaire method by the professional research institution. The unit of analysis in this study is the SBUs (strategic business unit) in the software provider. A total of 199 SBUs is used for analyzing and testing our hypotheses. With regards to the measurement of firm strategy, we take three measurement items for differentiation strategy such as the application uniqueness (referring an application aims to differentiate within just one or a small number of target industry), supply channel diversification (regarding whether SaaS vendor had diversified supply chain) as well as the number of specialized expertise and take two items for low cost strategy like subscription fee and initial set-up fee. We employ a hierarchical regression analysis technique for testing moderation effects of SaaS technology maturity and follow the Baron and Kenny's procedure for determining if firm strategies affect customer acquisition through technology maturity. Empirical results revealed that, firstly, when differentiation strategy is applied to attain business performance like customer acquisition, the effects of the strategy is moderated by the technology maturity level of SaaS providers. In other words, securing higher level of SaaS technology maturity is essential for higher business performance. For instance, given that firms implement application uniqueness or a distribution channel diversification as a differentiation strategy, they can acquire more customers when their level of SaaS technology maturity is higher rather than lower. Secondly, results indicate that pursuing differentiation strategy or low cost strategy effectively works for SaaS providers' obtaining customer, which means that continuously differentiating their service from others or making their service fee (subscription fee or initial set-up fee) lower are helpful for their business success in terms of acquiring their customers. Lastly, results show that the level of SaaS technology maturity mediates the relationships between low cost strategy and customer acquisition. That is, based on our research design, customers usually perceive the real value of the low subscription fee or initial set-up fee only through the SaaS service provide by vender and, in turn, this will affect their decision making whether subscribe or not.

The Prediction of DEA based Efficiency Rating for Venture Business Using Multi-class SVM (다분류 SVM을 이용한 DEA기반 벤처기업 효율성등급 예측모형)

  • Park, Ji-Young;Hong, Tae-Ho
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.139-155
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    • 2009
  • For the last few decades, many studies have tried to explore and unveil venture companies' success factors and unique features in order to identify the sources of such companies' competitive advantages over their rivals. Such venture companies have shown tendency to give high returns for investors generally making the best use of information technology. For this reason, many venture companies are keen on attracting avid investors' attention. Investors generally make their investment decisions by carefully examining the evaluation criteria of the alternatives. To them, credit rating information provided by international rating agencies, such as Standard and Poor's, Moody's and Fitch is crucial source as to such pivotal concerns as companies stability, growth, and risk status. But these types of information are generated only for the companies issuing corporate bonds, not venture companies. Therefore, this study proposes a method for evaluating venture businesses by presenting our recent empirical results using financial data of Korean venture companies listed on KOSDAQ in Korea exchange. In addition, this paper used multi-class SVM for the prediction of DEA-based efficiency rating for venture businesses, which was derived from our proposed method. Our approach sheds light on ways to locate efficient companies generating high level of profits. Above all, in determining effective ways to evaluate a venture firm's efficiency, it is important to understand the major contributing factors of such efficiency. Therefore, this paper is constructed on the basis of following two ideas to classify which companies are more efficient venture companies: i) making DEA based multi-class rating for sample companies and ii) developing multi-class SVM-based efficiency prediction model for classifying all companies. First, the Data Envelopment Analysis(DEA) is a non-parametric multiple input-output efficiency technique that measures the relative efficiency of decision making units(DMUs) using a linear programming based model. It is non-parametric because it requires no assumption on the shape or parameters of the underlying production function. DEA has been already widely applied for evaluating the relative efficiency of DMUs. Recently, a number of DEA based studies have evaluated the efficiency of various types of companies, such as internet companies and venture companies. It has been also applied to corporate credit ratings. In this study we utilized DEA for sorting venture companies by efficiency based ratings. The Support Vector Machine(SVM), on the other hand, is a popular technique for solving data classification problems. In this paper, we employed SVM to classify the efficiency ratings in IT venture companies according to the results of DEA. The SVM method was first developed by Vapnik (1995). As one of many machine learning techniques, SVM is based on a statistical theory. Thus far, the method has shown good performances especially in generalizing capacity in classification tasks, resulting in numerous applications in many areas of business, SVM is basically the algorithm that finds the maximum margin hyperplane, which is the maximum separation between classes. According to this method, support vectors are the closest to the maximum margin hyperplane. If it is impossible to classify, we can use the kernel function. In the case of nonlinear class boundaries, we can transform the inputs into a high-dimensional feature space, This is the original input space and is mapped into a high-dimensional dot-product space. Many studies applied SVM to the prediction of bankruptcy, the forecast a financial time series, and the problem of estimating credit rating, In this study we employed SVM for developing data mining-based efficiency prediction model. We used the Gaussian radial function as a kernel function of SVM. In multi-class SVM, we adopted one-against-one approach between binary classification method and two all-together methods, proposed by Weston and Watkins(1999) and Crammer and Singer(2000), respectively. In this research, we used corporate information of 154 companies listed on KOSDAQ market in Korea exchange. We obtained companies' financial information of 2005 from the KIS(Korea Information Service, Inc.). Using this data, we made multi-class rating with DEA efficiency and built multi-class prediction model based data mining. Among three manners of multi-classification, the hit ratio of the Weston and Watkins method is the best in the test data set. In multi classification problems as efficiency ratings of venture business, it is very useful for investors to know the class with errors, one class difference, when it is difficult to find out the accurate class in the actual market. So we presented accuracy results within 1-class errors, and the Weston and Watkins method showed 85.7% accuracy in our test samples. We conclude that the DEA based multi-class approach in venture business generates more information than the binary classification problem, notwithstanding its efficiency level. We believe this model can help investors in decision making as it provides a reliably tool to evaluate venture companies in the financial domain. For the future research, we perceive the need to enhance such areas as the variable selection process, the parameter selection of kernel function, the generalization, and the sample size of multi-class.

Evaluation of Image Quality Change by Truncated Region in Brain PET/CT (Brain PET에서 Truncated Region에 의한 영상의 질 평가)

  • Lee, Hong-Jae;Do, Yong-Ho;Kim, Jin-Eui
    • The Korean Journal of Nuclear Medicine Technology
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    • v.19 no.2
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    • pp.68-73
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    • 2015
  • Purpose The purpose of this study was to evaluate image quality change by truncated region in field of view (FOV) of attenuation correction computed tomography (AC-CT) in brain PET/CT. Materials and Methods Biograph Truepoint 40 with TrueV (Siemens) was used as a scanner. $^{68}Ge$ phantom scan was performed with and without applying brain holder using brain PET/CT protocol. PET attenuation correction factor (ACF) was evaluated according to existence of pallet in FOV of AC-CT. FBP, OSEM-3D and PSF methods were applied for PET reconstruction. Parameters of iteration 4, subsets 21 and gaussian 2 mm filter were applied for iterative reconstruction methods. Window level 2900, width 6000 and level 4, 200, width 1000 were set for visual evaluation of PET AC images. Vertical profiles of 5 slices and 20 slices summation images applied gaussian 5 mm filter were produced for evaluating integral uniformity. Results Patient pallet was not covered in FOV of AC-CT when without applying brain holder because of small size of FOV. It resulted in defect of ACF sinogram by truncated region in ACF evaluation. When without applying brain holder, defect was appeared in lower part of transverse image on condition of window level 4200, width 1000 in PET AC image evaluation. With and without applying brain holder, integral uniformities of 5 slices and 20 slices summation images were 7.2%, 6.7% and 11.7%, 6.7%. Conclusion Truncated region by small FOV results in count defect in occipital lobe of brain in clinical or research studies. It is necessary to understand effect of truncated region and apply appropriate accessory for brain PET/CT.

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Application of Hydro-Cartographic Generalization on Buildings for 2-Dimensional Inundation Analysis (2차원 침수해석을 위한 수리학적 건물 일반화 기법의 적용)

  • PARK, In-Hyeok;JIN, Gi-Ho;JEON, Ka-Young;HA, Sung-Ryong
    • Journal of the Korean Association of Geographic Information Studies
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    • v.18 no.2
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    • pp.1-15
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    • 2015
  • Urban flooding threatens human beings and facilities with chemical and physical hazards since the beginning of human civilization. Recent studies have emphasized the integration of data and models for effective urban flood inundation modeling. However, the model set-up process is tend to be time consuming and to require a high level of data processing skill. Furthermore, in spite of the use of high resolution grid data, inundation depth and velocity are varied with building treatment methods in 2-D inundation model, because undesirable grids are generated and resulted in the reliability decline of the simulation results. Thus, it requires building generalization process or enhancing building orthogonality to minimize the distortion of building before converting building footprint into grid data. This study aims to develop building generalization method for 2-dimensional inundation analysis to enhance the model reliability, and to investigate the effect of building generalization method on urban inundation in terms of geographical engineering and hydraulic engineering. As a result to improve the reliability of 2-dimensional inundation analysis, the building generalization method developed in this study should be adapted using Digital Building Model(DBM) before model implementation in urban area. The proposed building generalization sequence was aggregation-simplification, and the threshold of the each method should be determined by considering spatial characteristics, which should not exceed the summation of building gap average and standard deviation.