• Title/Summary/Keyword: dynamic effect

Search Result 5,667, Processing Time 0.054 seconds

Contrast Media in Abdominal Computed Tomography: Optimization of Delivery Methods

  • Joon Koo Han;Byung Ihn Choi;Ah Young Kim;Soo Jung Kim
    • Korean Journal of Radiology
    • /
    • v.2 no.1
    • /
    • pp.28-36
    • /
    • 2001
  • Objective: To provide a systematic overview of the effects of various parameters on contrast enhancement within the same population, an animal experiment as well as a computer-aided simulation study was performed. Materials and Methods: In an animal experiment, single-level dynamic CT through the liver was performed at 5-second intervals just after the injection of contrast medium for 3 minutes. Combinations of three different amounts (1, 2, 3 mL/kg), concentrations (150, 200, 300 mgI/mL), and injection rates (0.5, 1, 2 mL/sec) were used. The CT number of the aorta (A), portal vein (P) and liver (L) was measured in each image, and time-attenuation curves for A, P and L were thus obtained. The degree of maximum enhancement (Imax) and time to reach peak enhancement (Tmax) of A, P and L were determined, and times to equilibrium (Teq) were analyzed. In the computed-aided simulation model, a program based on the amount, flow, and diffusion coefficient of body fluid in various compartments of the human body was designed. The input variables were the concentrations, volumes and injection rates of the contrast media used. The program generated the time-attenuation curves of A, P and L, as well as liver-to-hepatocellular carcinoma (HCC) contrast curves. On each curve, we calculated and plotted the optimal temporal window (time period above the lower threshold, which in this experiment was 10 Hounsfield units), the total area under the curve above the lower threshold, and the area within the optimal range. Results: A. Animal Experiment: At a given concentration and injection rate, an increased volume of contrast medium led to increases in Imax A, P and L. In addition, Tmax A, P, L and Teq were prolonged in parallel with increases in injection time The time-attenuation curve shifted upward and to the right. For a given volume and injection rate, an increased concentration of contrast medium increased the degree of aortic, portal and hepatic enhancement, though Tmax A, P and L remained the same. The time-attenuation curve shifted upward. For a given volume and concentration of contrast medium, changes in the injection rate had a prominent effect on aortic enhancement, and that of the portal vein and hepatic parenchyma also showed some increase, though the effect was less prominent. A increased in the rate of contrast injection led to shifting of the time enhancement curve to the left and upward. B. Computer Simulation: At a faster injection rate, there was minimal change in the degree of hepatic attenuation, though the duration of the optimal temporal window decreased. The area between 10 and 30 HU was greatest when contrast media was delivered at a rate of 2 3 mL/sec. Although the total area under the curve increased in proportion to the injection rate, most of this increase was above the upper threshould and thus the temporal window was narrow and the optimal area decreased. Conclusion: Increases in volume, concentration and injection rate all resulted in improved arterial enhancement. If cost was disregarded, increasing the injection volume was the most reliable way of obtaining good quality enhancement. The optimal way of delivering a given amount of contrast medium can be calculated using a computer-based mathematical model.

  • PDF

The Effects of the Computer Aided Innovation Capabilities on the R&D Capabilities: Focusing on the SMEs of Korea (Computer Aided Innovation 역량이 연구개발역량에 미치는 효과: 국내 중소기업을 대상으로)

  • Shim, Jae Eok;Byeon, Moo Jang;Moon, Hyo Gon;Oh, Jay In
    • Asia pacific journal of information systems
    • /
    • v.23 no.3
    • /
    • pp.25-53
    • /
    • 2013
  • This study analyzes the effect of Computer Aided Innovation (CAI) to improve R&D Capabilities empirically. Survey was distributed by e-mail and Google Docs, targeting CTO of 235 SMEs. 142 surveys were returned back (rate of return 60.4%) from companies. Survey results from 119 companies (83.8%) which are effective samples except no-response, insincere response, estimated value, etc. were used for statistics analysis. Companies with less than 50billion KRW sales of entire researched companies occupy 76.5% in terms of sample traits. Companies with less than 300 employees occupy 83.2%. In terms of the type of company business Partners (called 'partners with big companies' hereunder) who work with big companies for business occupy 68.1%. SMEs based on their own business (called 'independent small companies') appear to occupy 31.9%. The present status of holding IT system according to traits of company business was classified into partners with big companies versus independent SMEs. The present status of ERP is 18.5% to 34.5%. QMS is 11.8% to 9.2%. And PLM (Product Life-cycle Management) is 6.7% to 2.5%. The holding of 3D CAD is 47.1% to 21%. IT system-holding and its application of independent SMEs seemed very vulnerable, compared with partner companies of big companies. This study is comprised of IT infra and IT Utilization as CAI capacity factors which are independent variables. factors of R&D capabilities which are independent variables are organization capability, process capability, HR capability, technology-accumulating capability, and internal/external collaboration capability. The highest average value of variables was 4.24 in organization capability 2. The lowest average value was 3.01 in IT infra which makes users access to data and information in other areas and use them with ease when required during new product development. It seems that the inferior environment of IT infra of general SMEs is reflected in CAI itself. In order to review the validity used to measure variables, Factors have been analyzed. 7 factors which have over 1.0 pure value of their dependent and independent variables were extracted. These factors appear to explain 71.167% in total of total variances. From the result of factor analysis about measurable variables in this study, reliability of each item was checked by Cronbach's Alpha coefficient. All measurable factors at least over 0.611 seemed to acquire reliability. Next, correlation has been done to explain certain phenomenon by correlation analysis between variables. As R&D capabilities factors which are arranged as dependent variables, organization capability, process capability, HR capability, technology-accumulating capability, and internal/external collaboration capability turned out that they acquire significant correlation at 99% reliability level in all variables of IT infra and IT Utilization which are independent variables. In addition, correlation coefficient between each factor is less than 0.8, which proves that the validity of this study judgement has been acquired. The pair with the highest coefficient had 0.628 for IT utilization and technology-accumulating capability. Regression model which can estimate independent variables was used in this study under the hypothesis that there is linear relation between independent variables and dependent variables so as to identify CAI capability's impact factors on R&D. The total explanations of IT infra among CAI capability for independent variables such as organization capability, process capability, human resources capability, technology-accumulating capability, and collaboration capability are 10.3%, 7%, 11.9%, 30.9%, and 10.5% respectively. IT Utilization exposes comprehensively low explanatory capability with 12.4%, 5.9%, 11.1%, 38.9%, and 13.4% for organization capability, process capability, human resources capability, technology-accumulating capability, and collaboration capability respectively. However, both factors of independent variables expose very high explanatory capability relatively for technology-accumulating capability among independent variable. Regression formula which is comprised of independent variables and dependent variables are all significant (P<0.005). The suitability of regression model seems high. When the results of test for dependent variables and independent variables are estimated, the hypothesis of 10 different factors appeared all significant in regression analysis model coefficient (P<0.01) which is estimated to affect in the hypothesis. As a result of liner regression analysis between two independent variables drawn by influence factor analysis for R&D capability and R&D capability. IT infra and IT Utilization which are CAI capability factors has positive correlation to organization capability, process capability, human resources capability, technology-accumulating capability, and collaboration capability with inside and outside which are dependent variables, R&D capability factors. It was identified as a significant factor which affects R&D capability. However, considering adjustable variables, a big gap is found, compared to entire company. First of all, in case of partner companies with big companies, in IT infra as CAI capability, organization capability, process capability, human resources capability, and technology capability out of R&D capacities seems to have positive correlation. However, collaboration capability appeared insignificance. IT utilization which is a CAI capability factor seemed to have positive relation to organization capability, process capability, human resources capability, and internal/external collaboration capability just as those of entire companies. Next, by analyzing independent types of SMEs as an adjustable variable, very different results were found from those of entire companies or partner companies with big companies. First of all, all factors in IT infra except technology-accumulating capability were rejected. IT utilization was rejected except technology-accumulating capability and collaboration capability. Comprehending the above adjustable variables, the following results were drawn in this study. First, in case of big companies or partner companies with big companies, IT infra and IT utilization affect improving R&D Capabilities positively. It was because most of big companies encourage innovation by using IT utilization and IT infra building over certain level to their partner companies. Second, in all companies, IT infra and IT utilization as CAI capability affect improving technology-accumulating capability positively at least as R&D capability factor. The most of factor explanation is low at around 10%. However, technology-accumulating capability is rather high around 25.6% to 38.4%. It was found that CAI capability contributes to technology-accumulating capability highly. Companies shouldn't consider IT infra and IT utilization as a simple product developing tool in R&D section. However, they have to consider to use them as a management innovating strategy tool which proceeds entire-company management innovation centered in new product development. Not only the improvement of technology-accumulating capability in department of R&D. Centered in new product development, it has to be used as original management innovative strategy which proceeds entire company management innovation. It suggests that it can be a method to improve technology-accumulating capability in R&D section and Dynamic capability to acquire sustainable competitive advantage.

The Effect of Moisture Content on the Compressive Properties of Korean Corn Kernel (함수율(含水率)이 옥수수립(粒)의 압축특성(壓縮特性)에 미치는 영향(影響))

  • Lee, Han Man;Kim, Soung Rai
    • Korean Journal of Agricultural Science
    • /
    • v.13 no.1
    • /
    • pp.113-122
    • /
    • 1986
  • In order to promote mechanization of corn harvesting in Korea, this study was conducted to find out the effect of moisture content on compressive properties such as force, deformation, energy and modulus of stiffness to the bioyield and the rupture point for Korean corn kernel. In this study, the loading positions of corn were flat, edge, longitude and the moisture contents were about 13, 17, 21, 25% in wet basis. The compression test was carreied out with flat plate by use of dynamic straingage for three varieties of Korean corn under quasi-static force when the loading rate was 1.125mm/min. The results of this study are summarized as follows; 1. When the moisture content of corn ranged from 12.5 to 24.5 percent, at flat position, the bioyied force was in the range of 13.63-26.73 kg and the maximum compressive strength was in the range of 21.55-47.65kg. Their values were reached minimum at about 17% and maximum at about 21% moisture content. The bioyield force was in the range of 13.58-6.70kg at edge position and the maximum compressive strength which was 16.42 to 7.82kg at edge position was lower than that which was 18.55-9.05kg at longitudinal position. 2. Deformation of corn varied from 0.43 to 1.37 mm at bioyield point and from 0.70 to 2.66mm at rupture point between 12.5 to 24.5% moisture content. As the moisture content increased, deformation was increased. 3. The moduli of resilience and toughness of corn ranged from 2.60 to 8.57kg. mm and from 6.41 to 34.36kg. mm when the moisture content ranged from 12.5 to 24.5 percent, respectively. As the moisture content increased, the modulus of toughness was increased at edge position and decreased at longitudinal position. And their values were equal each other at 22-23% moisture content. 4. The modulus of stiffness was decreased with increase in the moisture content. Its values ranged from 32.07 to 5.86 kg/mm at edge position and from 42.12 to 18.68kg/mm at flat position, respectively. Also, the values of Suweon 19 were higher than those of Buyeo. 5. It was considered that the compressive properties of corn at flat position were more important on the design data for corn harvesting and processing machinery than those of edge or longitudinal position. Also, grinding energy would be minimized when a corn was processed between about 12.5 to 17% moisture content and corn damage would be reduced when a corn was handled between about 19 to 24% moisture content in wet basis.

  • PDF

The Building Plan of Online ADR Model related to the International Commercial Transaction Dispute Resolution (국제상거래 분쟁해결을 위한 온라인 ADR 모델 구축방안)

  • Kim Sun-Kwang;Kim Jong-Rack;Hong Sung-Kyu
    • Journal of Arbitration Studies
    • /
    • v.15 no.2
    • /
    • pp.3-35
    • /
    • 2005
  • The meaning of Online ADR lies in the prompt and economical resolution of disputes by applying the information/communication element (Internet) to existing ADR. However, if the promptness and economical efficiency are overemphasized, the fairness and appropriateness of dispute resolution may be compromised and consequently Online ADR will be belittled and criticized as second-class trials. In addition, as communication is mostly made using texts in Online ADR it is difficult to investigate cases and to create atmosphere and induce dynamic feelings, which are possible in the process of dispute resolution through face-to-face contact. Despite such difficulties, Online ADR is expanding its area not only in online but also in offline due to its advantages such as promptness, low expenses and improved resolution methods, and is expected to develop rapidly as the electronic government decided to adopt it in the future. Accordingly, the following points must be focused on for the continuous First, in the legal and institutional aspects for the development of Online ADR, it is necessary to establish a framework law on ADR. A framework law on ADR comprehending existing mediation and arbitration should be established and it must include contents of Online ADR, which utilizes electronic communication means. However, it is too early to establish a separate law for Online ADR because Online ADR must develop based on the theoretical system of ADR. Second, although Online ADR is expanding rapidly, it may take time to be settled as a tool of dispute resolution. As discussed earlier, additionally, if the amount of money in dispute is large or the dispute is complicated, Online ADR may have a negative effect on the resolution of the dispute. Thus, it is necessary to apply Online ADR to trifle cases or domestic cases in the early stage, accumulating experiences and correcting errors. Moreover, in order to settle numerous disputes effectively, Online ADR cases should be analyzed systematically and cases should be classified by type so that similar disputes may be settled automatically. What is more, these requirements should reflected in developing Online ADR system. Third, the application of Online ADR is being expanded to consumer disputes, domain name disputes, commercial disputes, legal disputes, etc., millions of cases are settled through Online ADR, and 115 Online ADR sites are in operation throughout the world. Thus Online ADR requires not temporary but continuous attention, and mediators and arbitrators participating in Online ADR should be more intensively educated on negotiation and information technologies. In particular, government-led research projects should be promoted to establish Online ADR model and these projects should be supported by comprehensive researches on mediation, arbitration and Online ADR. Fourth, what is most important in the continuous development and expansion of Online ADR is to secure confidence in Online ADR and advertise Online ADR to users. For this, incentives and rewards should be given to specialists such as lawyers when they participate in Online ADR as mediators and arbitrators in order to improve their expertise. What is more, from the early stage, the government and public institutions should have initiative in promoting Online ADR so that parties involved in disputes recognize the substantial contribution of Online ADR to dispute resolution. Lastly, dispute resolution through Online ADR is performed by organizations such as Korea Institute for Electronic Commerce and Korea Consumer Protection Board and partially by Korean Commercial Arbitration Board. Online ADR is expected to expand its area to commercial disputes in offline in the future. In response to this, Korean Commercial Arbitration Board, which is an organization for commercial dispute resolution, needs to be restructured.

  • PDF

The Smartphone User's Dilemma among Personalization, Privacy, and Advertisement Fatigue: An Empirical Examination of Personalized Smartphone Advertisement (스마트폰 이용자의 모바일 광고 수용의사에 영향을 주는 요인: 개인화된 서비스, 개인정보보호, 광고 피로도 사이에서의 딜레마)

  • You, Soeun;Kim, Taeha;Cha, Hoon S.
    • Information Systems Review
    • /
    • v.17 no.2
    • /
    • pp.77-100
    • /
    • 2015
  • This study examined the factors that influence the smartphone user's decision to accept the personalized mobile advertisement. As a theoretical basis, we applied the privacy calculus model (PCM) that illustrates how consumers are engaged in a dynamic adjustment process in which privacy risks are weighted against benefits of information disclosure. In particular, we investigated how smartphone users make a risk-benefit assessment under which personalized service as benefit-side factor and information privacy risks as a risk-side factor accompanying their acceptance of advertisements. Further, we extend the current PCM by considering advertisement fatigue as a new factor that may influence the user's acceptance. The research model with five (5) hypotheses was tested using data gathered from 215 respondents through a quasi-experimental survey method. During the survey, each participant was asked to navigate the website where the experimental simulation of a mobile advertisement service was provided. The results showed that three (3) out of five (5) hypotheses were supported. First, we found that the intention to accept advertisements is positively and significantly influenced by the perceived value of personalization. Second, perceived advertisement fatigue was also found to be a strong predictor of the intention to accept advertisements. However, we did not find any evidence of direct influence of privacy risks. Finally, we found that the significant moderating effect between the perceived value of personalization and advertisement fatigue. This suggests that the firms should provide effective tailored advertisement that can increase the perceived value of personalization to mitigate the negative impacts of advertisement fatigue.

Analysis and Evaluation of Frequent Pattern Mining Technique based on Landmark Window (랜드마크 윈도우 기반의 빈발 패턴 마이닝 기법의 분석 및 성능평가)

  • Pyun, Gwangbum;Yun, Unil
    • Journal of Internet Computing and Services
    • /
    • v.15 no.3
    • /
    • pp.101-107
    • /
    • 2014
  • With the development of online service, recent forms of databases have been changed from static database structures to dynamic stream database structures. Previous data mining techniques have been used as tools of decision making such as establishment of marketing strategies and DNA analyses. However, the capability to analyze real-time data more quickly is necessary in the recent interesting areas such as sensor network, robotics, and artificial intelligence. Landmark window-based frequent pattern mining, one of the stream mining approaches, performs mining operations with respect to parts of databases or each transaction of them, instead of all the data. In this paper, we analyze and evaluate the techniques of the well-known landmark window-based frequent pattern mining algorithms, called Lossy counting and hMiner. When Lossy counting mines frequent patterns from a set of new transactions, it performs union operations between the previous and current mining results. hMiner, which is a state-of-the-art algorithm based on the landmark window model, conducts mining operations whenever a new transaction occurs. Since hMiner extracts frequent patterns as soon as a new transaction is entered, we can obtain the latest mining results reflecting real-time information. For this reason, such algorithms are also called online mining approaches. We evaluate and compare the performance of the primitive algorithm, Lossy counting and the latest one, hMiner. As the criteria of our performance analysis, we first consider algorithms' total runtime and average processing time per transaction. In addition, to compare the efficiency of storage structures between them, their maximum memory usage is also evaluated. Lastly, we show how stably the two algorithms conduct their mining works with respect to the databases that feature gradually increasing items. With respect to the evaluation results of mining time and transaction processing, hMiner has higher speed than that of Lossy counting. Since hMiner stores candidate frequent patterns in a hash method, it can directly access candidate frequent patterns. Meanwhile, Lossy counting stores them in a lattice manner; thus, it has to search for multiple nodes in order to access the candidate frequent patterns. On the other hand, hMiner shows worse performance than that of Lossy counting in terms of maximum memory usage. hMiner should have all of the information for candidate frequent patterns to store them to hash's buckets, while Lossy counting stores them, reducing their information by using the lattice method. Since the storage of Lossy counting can share items concurrently included in multiple patterns, its memory usage is more efficient than that of hMiner. However, hMiner presents better efficiency than that of Lossy counting with respect to scalability evaluation due to the following reasons. If the number of items is increased, shared items are decreased in contrast; thereby, Lossy counting's memory efficiency is weakened. Furthermore, if the number of transactions becomes higher, its pruning effect becomes worse. From the experimental results, we can determine that the landmark window-based frequent pattern mining algorithms are suitable for real-time systems although they require a significant amount of memory. Hence, we need to improve their data structures more efficiently in order to utilize them additionally in resource-constrained environments such as WSN(Wireless sensor network).

Earthquake Monitoring : Future Strategy (지진관측 : 미래 발전 전략)

  • Chi, Heon-Cheol;Park, Jung-Ho;Kim, Geun-Young;Shin, Jin-Soo;Shin, In-Cheul;Lim, In-Seub;Jeong, Byung-Sun;Sheen, Dong-Hoon
    • Geophysics and Geophysical Exploration
    • /
    • v.13 no.3
    • /
    • pp.268-276
    • /
    • 2010
  • Earthquake Hazard Mitigation Law was activated into force on March 2009. By the law, the obligation to monitor the effect of earthquake on the facilities was extended to many organizations such as gas company and local governments. Based on the estimation of National Emergency Management Agency (NEMA), the number of free-surface acceleration stations would be expanded to more than 400. The advent of internet protocol and the more simplified operation have allowed the quick and easy installation of seismic stations. In addition, the dynamic range of seismic instruments has been continuously improved enough to evaluate damage intensity and to alert alarm directly for earthquake hazard mitigation. For direct visualization of damage intensity and area, Real Time Intensity COlor Mapping (RTICOM) is explained in detail. RTICOM would be used to retrieve the essential information for damage evaluation, Peak Ground Acceleration (PGA). Destructive earthquake damage is usually due to surface waves which just follow S wave. The peak amplitude of surface wave would be pre-estimated from the amplitude and frequency content of first arrival P wave. Earthquake Early Warning (EEW) system is conventionally defined to estimate local magnitude from P wave. The status of EEW is reviewed and the application of EEW to Odesan earthquake is exampled with ShakeMap in order to make clear its appearance. In the sense of rapidity, the earthquake announcement of Korea Meteorological Agency (KMA) might be dramatically improved by the adaption of EEW. In order to realize hazard mitigation, EEW should be applied to the local crucial facilities such as nuclear power plants and fragile semi-conduct plant. The distributed EEW is introduced with the application example of Uljin earthquake. Not only Nation-wide but also locally distributed EEW applications, all relevant information is needed to be shared in real time. The plan of extension of Korea Integrated Seismic System (KISS) is briefly explained in order to future cooperation of data sharing and utilization.

Yoo Young-kuk's Early Constructivism: Utopianism in (1937) (유영국(劉永國)의 초기 구성주의: <랩소디>(1937)에 나타난 유토피아니즘)

  • 유영아
    • The Journal of Art Theory & Practice
    • /
    • no.9
    • /
    • pp.93-121
    • /
    • 2010
  • This study is about Yoo Young-kuk's early works which show constructivism, especially focus on his debut painting, for the 7th Dokuritsu Bijutsu Kyokai(獨立美術協會, the Independent Fine Arts Association) in Tokyo in 1937. The work was painted 2 years after he had started his study in Japan in 1935. It was the first painting that applied Constructivism. played an important role for Constructivism to be a leading art in his abstraction. After this picture, Yoo was soon devoted to the principles of Constructivism-- Faktura(material), Tektonika (tectonics), Tekhnika(technique), space, construction-- in his painterly reliefs. This article examined why Yoo concentrated on Constructivism for , what the characteristics were, and what influences were on other works from 1935 to 1949. In addition, I investigated in which period was painted and how Constructivism was spread in 1930s and early 1940s in chapter 2. I scrutinized Rhapsody in chapter 3. When Yoo created Japan was under the Fifteen Years War(1931-1945), and a major discourse was the Japanese Spirit at that time. It was connected with construction of an ideal nation which the Japanese ultra-national fascism pursued. This ideological pursuit was intended to unite the Japanese people for total war system and to restore a national dignity which had been fallen down due to Manchurian Incident(1931). Thus, on the hand, Kokusai Bunka Shinkokai(國際文化振興, The Society for International Cultural Relations) and the Nippon Kosaku Bunka Renmei(日本工作文化連盟, Japanese Werkbund) were supported financially by the Japanese government. On the other hand, the government enacted regulations to opposing parties which would distract Japanese people's unification. As for the Japanese art world, the merge of art groups was carried out through remodeling of Teikoku Bijutsuin(帝國美術院, The Imperial Fine Arts Academy) in 1935. This brought out continuous dispute and disorder. Young artists who felt difficulty of entering an entry of Imperial Fine Arts Exhibition repeatedly grouped and disbanded for small art groups to build their standing, which they pursued Surrealism and Abstract art. Among them Constructivism was considered as the latest trend and was popular in craft, design, architecture as well as fine arts. In the year before he painted , Avant-garde theatres including Constructivism theatre were introduced in a feature article of September, 1936 in Atelier, which was dealing with mainly avant-garde arts. Books related with Constructivism were translated into Japanese, and Gestaltung Education had become active since the publication of A Compendium of Gestaltung Education("構成敎育大系"(1934)), Salvador Dali(1904-1989) was also introduced, so Surrealism was drawn more attention by young artists. reflected popular trends. Yoo analyzed the Japanese avant-gardists' archaic taste in the Independent Art Association that he submitted his painting to. And then he entitled 'Rhapsody' which derives from Ancient Greek's epic poetry and deliberately set up images in a scene. In chapter 3, I examined a theme which was planned carefully by sorting favorite images from the Japanese Surrealism. was a result that Yoo Young-kuk observed objectively the phenomenon that young artists dreamt of Utopia or longed for Nostalgia passively and lethargically under wars. And then he otherized himself from that circumstance. First of all, for he used the typical icons of Japanese Surrealism such as the horizon, flowing clouds, and vast plain that were considered stereotypes of Arcadia. He, however distinguished himself form those Japanese Surrealists. He made his own vision about Utopia by referring Lyubov Popova(1889-1924)'s stage design. His objective point of view was expressed by positive and dynamic images of structure and human's actions. Constructivism which was attempted in had an effect on other early constructive works, and the principles of Constructivism were sought hard in reliefs, paintings, and photos.

  • PDF

A Theoretical Model for the Analysis of Residual Motion Artifacts in 4D CT Scans (이론적 모델을 이용한 4DCT에서의 Motion Artifact 분석)

  • Kim, Tae-Ho;Yoon, Jai-Woong;Kang, Seong-Hee;Suh, Tae-Suk
    • Progress in Medical Physics
    • /
    • v.23 no.3
    • /
    • pp.145-153
    • /
    • 2012
  • In this study, we quantify the residual motion artifact in 4D-CT scan using the dynamic lung phantom which could simulate respiratory target motion and suggest a simple one-dimension theoretical model to explain and characterize the source of motion artifacts in 4DCT scanning. We set-up regular 1D sine motion and adjusted three level of amplitude (10, 20, 30 mm) with fixed period (4s). The 4DCT scans are acquired in helical mode and phase information provided by the belt type respiratory monitoring system. The images were sorted into ten phase bins ranging from 0% to 90%. The reconstructed images were subsequently imported into the Treatment Planning System (CorePLAN, SC&J) for target delineation using a fixed contour window and dimensions of the three targets are measured along the direction of motion. Target dimension of each phase image have same changing trend. The error is minimum at 50% phase in all case (10, 20, 30 mm) and we found that ${\Delta}S$ (target dimension change) of 10, 20 and 30 mm amplitude were 0 (0%), 0.1 (5%), 0.1 (5%) cm respectively compare to the static image of target diameter (2 cm). while the error is maximum at 30% and 80% phase ${\Delta}S$ of 10, 20 and 30 mm amplitude were 0.2 (10%), 0.7 (35%), 0.9 (45%) cm respectively. Based on these result, we try to analysis the residual motion artifact in 4D-CT scan using a simple one-dimension theoretical model and also we developed a simulation program. Our results explain the effect of residual motion on each phase target displacement and also shown that residual motion artifact was affected that the target velocity at each phase. In this study, we focus on provides a more intuitive understanding about the residual motion artifact and try to explain the relationship motion parameters of the scanner, treatment couch and tumor. In conclusion, our results could help to decide the appropriate reconstruction phase and CT parameters which reduce the residual motion artifact in 4DCT.

AN ORBIT PROPAGATION SOFTWARE FOR MARS ORBITING SPACECRAFT (화성 근접 탐사를 위한 우주선의 궤도전파 소프트웨어)

  • Song, Young-Joo;Park, Eun-Seo;Yoo, Sung-Moon;Park, Sang-Young;Choi, Kyu-Hong;Yoon, Jae-Cheol;Yim, Jo-Ryeong;Kim, Han-Dol;Choi, Jun-Min;Kim, Hak-Jung;Kim, Byung-Kyo
    • Journal of Astronomy and Space Sciences
    • /
    • v.21 no.4
    • /
    • pp.351-360
    • /
    • 2004
  • An orbit propagation software for the Mars orbiting spacecraft has been developed and verified in preparations for the future Korean Mars missions. Dynamic model for Mars orbiting spacecraft has been studied, and Mars centered coordinate systems are utilized to express spacecraft state vectors. Coordinate corrections to the Mars centered coordinate system have been made to adjust the effects caused by Mars precession and nutation. After spacecraft enters Sphere of Influence (SOI) of the Mars, the spacecraft experiences various perturbation effects as it approaches to Mars. Every possible perturbation effect is considered during integrations of spacecraft state vectors. The Mars50c gravity field model and the Mars-GRAM 2001 model are used to compute perturbation effects due to Mars gravity field and Mars atmospheric drag, respectively. To compute exact locations of other planets, JPL's DE405 ephemerides are used. Phobos and Deimos's ephemeris are computed using analytical method because their informations are not released with DE405. Mars Global Surveyor's mapping orbital data are used to verify the developed propagator performances. After one Martian day propagation (12 orbital periods), the results show about maximum ${\pm}5$ meter errors, in every position state components(radial, cross-track and along-track), when compared to these from the Astrogator propagation in the Satellite Tool Kit. This result shows high reliability of the developed software which can be used to design near Mars missions for Korea, in future.