• Title/Summary/Keyword: Diffusion models

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A Study on Security Architecture for Digital Content Dissemination (디지탈 컨텐츠 배포를 위한 보안 체계에 관한 연구)

  • 김대엽;주학수
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.13 no.1
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    • pp.147-155
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    • 2003
  • The diffusion of internet infrastructure and a fast increase of Population to use it is becoming a base of the service that can use various information, data and digital contents which were provided through off-line physically and used. Recently, the. techniques for copy deterrence and copyright protection have been important in e-commerce because various contents in digital form can be duplicated easily. The Access Control(AC) technique that only a user having the qualifications can access and use contents normally has been studied. The Conditional Access System(CAS) used in a satellite broadcasting md Digital Right Management System(DRMS) used for contents service are representative models of current commercialized access control. The CAS and DRM can be considered as an access control technique based on the payment based type(PBT). This paper describe the access control method of payment free type(PFT) suggested in [5] which are independent on the payment structure. And then we suggest a new access control method of payment free type which is more efficient than the previous one.

Self-Sovereign Identity (SSI): Structured Literature Reviews with Socio-Technical Perspective (Self-Sovereign Identity (SSI: 자기주권신원) 연구 동향 분석: 사회경제, 법률, 기술적 고찰을 중심으로)

  • Son, Young Jin;Park, Min Jung;Park, Jung Suk;Hwang, Hwa Jung;Chai, Sang Mi
    • The Journal of Information Systems
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    • v.30 no.4
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    • pp.119-152
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    • 2021
  • The concept of Self-Sovereign Identity (SSI) has emerged to overcome the limitations of traditional centralized personal identity management systems in our society. Therefore, in this study, 36 seminal researches out of 112 collected studies were investigated with a systematic literature review method to deliver a core common definition as well as the research trends on SSI in the socioeconomic, legal and technological fields. SSI studies in the legal field have mainly considered the conflicts with relevant laws such as General Data Protection Regulation (GDPR) and privacy protection laws. The study of SSI in the technology field have looked at the trends of the technical components to implement SSI and discussed the necessities of establishing standards to increase interoperability for SSI diffusion worldwide. This study ultimately derived the core definition of SSI from a various academic fields as "a trust-based personal identity management system that enables autonomous self-identification by a identity owner without a centralized system or 3rd party intervention". The results of this study contribute to the understanding of the essential SSI concept which were varied on different research fields and industries. The results also provide a foundation for discovering various SSI-based business models, applications as well as future research opportunities. Furthermore, this study suggested that SSI must be developed with interdisciplinary manner among the socioeconomic, legal, and technological fields to be practically applicable system to enable autonomous self-identification by a identity owner in our society.

Jacobian-free Newton Krylov two-node coarse mesh finite difference based on nodal expansion method

  • Zhou, Xiafeng
    • Nuclear Engineering and Technology
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    • v.54 no.8
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    • pp.3059-3072
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    • 2022
  • A Jacobian-Free Newton Krylov Two-Nodal Coarse Mesh Finite Difference algorithm based on Nodal Expansion Method (NEM_TNCMFD_JFNK) is successfully developed and proposed to solve the three-dimensional (3D) and multi-group reactor physics models. In the NEM_TNCMFD_JFNK method, the efficient JFNK method with the Modified Incomplete LU (MILU) preconditioner is integrated and applied into the discrete systems of the NEM-based two-node CMFD method by constructing the residual functions of only the nodal average fluxes and the eigenvalue. All the nonlinear corrective nodal coupling coefficients are updated on the basis of two-nodal NEM formulation including the discontinuity factor in every few newton steps. All the expansion coefficients and interface currents of the two-node NEM need not be chosen as the solution variables to evaluate the residual functions of the NEM_TNCMFD_JFNK method, therefore, the NEM_TNCMFD_JFNK method can greatly reduce the number of solution variables and the computational cost compared with the JFNK based on the conventional NEM. Finally the NEM_TNCMFD_JFNK code is developed and then analyzed by simulating the representative PWR MOX/UO2 core benchmark, the popular NEACRP 3D core benchmark and the complicated full-core pin-by-pin homogenous core model. Numerical solutions show that the proposed NEM_TNCMFD_JFNK method with the MILU preconditioner has the good numerical accuracy and can obtain higher computational efficiency than the NEM-based two-node CMFD algorithm with the power method in the outer iteration and the Krylov method using the MILU preconditioner in the inner iteration, which indicates the NEM_TNCMFD_JFNK method can serve as a potential and efficient numerical tool for reactor neutron diffusion analysis module in the JFNK-based multiphysics coupling application.

Domestic Automotive Exterior Lamp-LEDs Demand and Forecasting using BASS Diffusion Model (BASS 확산 모형을 이용한 국내 자동차 외장 램프 LED 수요예측 분석)

  • Lee, Jae-Heun
    • Journal of Korean Society for Quality Management
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    • v.50 no.3
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    • pp.349-371
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    • 2022
  • Purpose: Compared to the rapid growth rate of the domestic automotive LED industry so far, the predictive analysis method for demand forecasting or market outlook was insufficient. Accordingly, product characteristics are analyzed through the life trend of LEDs for automotive exterior lamps and the relative strengths of p and q using the Bass model. Also, future demands are predicted. Methods: We used sales data of a leading company in domestic market of automotive LEDs. Considering the autocorrelation error term of this data, parameters m, p, and q were estimated through the modified estimation method of OLS and the NLS(Nonlinear Least Squares) method, and the optimal method was selected by comparing prediction error performance such as RMSE. Future annual demands and cumulative demands were predicted through the growth curve obtained from Bass-NLS model. In addition, various nonlinear growth curve models were applied to the data to compare the Bass-NLS model with potential market demand, and an optimal model was derived. Results: From the analysis, the parameter estimation results by Bass-NLS obtained m=1338.13, p=0.0026, q=0.3003. If the current trend continues, domestic automotive LED market is predicted to reach its maximum peak in 2021 and the maximum demand is $102.23M. Potential market demand was $1338.13M. In the nonlinear growth curve model analysis, the Gompertz model was selected as the optimal model, and the potential market size was $2864.018M. Conclusion: It is expected that the Bass-NLS method will be applied to LED sales data for automotive to find out the characteristics of the relative strength of q/p of products and to be used to predict current demand and future cumulative demand.

1D Kinetics Model of NH3-Fed Solid Oxide Fuel Cell (암모니아 공급 고체산화물 연료전지의 1D 반응 모델)

  • VAN-TIEN GIAP;THAI-QUYEN QUACH;KOOK YOUNG AHN;YONGGYUN BAE;SUNYOUP LEE;YOUNG SANG KIM
    • Transactions of the Korean hydrogen and new energy society
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    • v.33 no.6
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    • pp.723-732
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    • 2022
  • Cracking ammonia inside solid oxide fuel cell (SOFC) stack is a compact and simple way. To prevent sharp temperature fluctuation and increase cell efficiency, the decomposition reaction should be spread on whole cell area. This leading to a question that, how does anode thickness affect the conversion rate of ammonia and the cell voltage? Since the 0D model of SOFC is useful for system level simulation, how accurate is it to use equilibrium solver for internal ammonia cracking reaction? The 1D model of ammonia fed SOFC was used to simulate the diffusion and reaction of ammonia inside the anode electrode, then the partial pressure of hydrogen and steam at triple phase boundary was used for cell voltage calculation. The result shows that, the ammonia conversion rate increases and reaches saturated value as anode thickness increase, and the saturated thickness is bigger for lower operating temperature. The similar cell voltage between 1D and 0D models can be reached with NH3 conversion rate above 90%. The 0D model and 1D model of SOFC showed similar conversion rate at temperature over 750℃.

Empirical Research on the Interaction between Visual Art Creation and Artificial Intelligence Collaboration (시각예술 창작과 인공지능 협업의 상호작용에 관한 실증연구)

  • Hyeonjin Kim;Yeongjo Kim;Donghyeon Yun;Hanjin Lee
    • The Journal of the Convergence on Culture Technology
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    • v.10 no.1
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    • pp.517-524
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    • 2024
  • Generative AI, exemplified by models like ChatGPT, has revolutionized human-machine interactions in the 21st century. As these advancements permeate various sectors, their intersection with the arts is both promising and challenging. Despite the arts' historical resistance to AI replacement, recent developments have sparked active research in AI's role in artistry. This study delves into the potential of AI in visual arts education, highlighting the necessity of swift adaptation amidst the Fourth Industrial Revolution. This research, conducted at a 4-year global higher education institution located in Gyeongbuk, involved 70 participants who took part in a creative convergence module course project. The study aimed to examine the influence of AI collaboration in visual arts, analyzing distinctions across majors, grades, and genders. The results indicate that creative activities with AI positively influence students' creativity and digital media literacy. Based on these findings, there is a need to further develop effective educational strategies and directions that incorporate AI.

Acute Cerebral Infarction in a Rabbit Model: Perfusion and Diffusion MR Imaging (가토의 급성 뇌경색에서 관류 및 확산강조 자기공명영상)

  • Heo Suk-Hee;Yim Nam-Yeol;Jeong Gwang-Woo;Yoon Woong;Kim Yun-Hyeon;Jeong Young-Yeon;Chung Tae-Woong;Kim Jeong;Park Jin-Gyoon;Kang Heoung-Keun;Seo Jeong-Jin
    • Investigative Magnetic Resonance Imaging
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    • v.7 no.2
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    • pp.116-123
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    • 2003
  • Purpose : The present study was undertaken to evaluate the usefulness of cerebral diffusion (DWI) and perfusion MR imaging (PWI) in rabbit models with hyperacute cerebral ischemic infarction. Materials and Methods : Experimental cerebral infarction were induced by direct injection of mixture of Histoacryl glue, lipiodol, and tungsten powder into the internal cerebral artery of 6 New-Zealand white rabbits, and they underwent conventional T1 and T2 weighted MR imaging, DWI, and PWI within 1 hour after the occlusion of internal cerebral artery. The PWI scan for each rabbit was obtained at the level of lateral ventricle and 1cm cranial to the basal ganglia. By postprocessing using special imaging software, perfusion images including cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps were obtained. The detection of infarcted lesion were evaluated on both perfusion maps and DWI. MTT difference time were measured in the perfusion defect lesion and symmetric contralateral normal cerebral hemisphere. Results : In all rabbits, there was no abnormal signal intensity on T2WI. But on DWI, abnormal high signal intensity, suggesting cerebral infarction, were detected in all rabbits. PWI (rCBV, CBF and MTT map) also showed perfusion defect in all rabbits. In four rabbits, the calculated square of perfusion defect in MTT map is larger than that of CBF map and in two rabbits, the calculated size of perfusion defect in MTT map and CBF map is same. Any rabbits do not show larger perfusion defect on CBF map than MTT map. In comparison between CBF map and DWI, 3 rabbits show larger square of lesion on CBF map than on DWI. The others shows same square of lesion on both technique. The size of lesion shown in 6 MTT map were larger than DWI. In three cases, the size of lesion shown in CBF map is equal to DWI. But these were smaller than MTT map. The calculated square of lesion in CBF map, equal to that of DWI and smaller than MTT map was three. And in one case, the calculated square of perfusion defect in MTT map was largest, and that of DWI was smallest. Conclusion : DWI and PWI may be useful in diagnosing hyperacute cerebral ischemic infarction and in e-valuating the cerebral hemodynamics in the rabbits.

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A Study on Industries's Leading at the Stock Market in Korea - Gradual Diffusion of Information and Cross-Asset Return Predictability- (산업의 주식시장 선행성에 관한 실증분석 - 자산간 수익률 예측 가능성 -)

  • Kim Jong-Kwon
    • Proceedings of the Safety Management and Science Conference
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    • 2004.11a
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    • pp.355-380
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    • 2004
  • I test the hypothesis that the gradual diffusion of information across asset markets leads to cross-asset return predictability in Korea. Using thirty-six industry portfolios and the broad market index as our test assets, I establish several key results. First, a number of industries such as semiconductor, electronics, metal, and petroleum lead the stock market by up to one month. In contrast, the market, which is widely followed, only leads a few industries. Importantly, an industry's ability to lead the market is correlated with its propensity to forecast various indicators of economic activity such as industrial production growth. Consistent with our hypothesis, these findings indicate that the market reacts with a delay to information in industry returns about its fundamentals because information diffuses only gradually across asset markets. Traditional theories of asset pricing assume that investors have unlimited information-processing capacity. However, this assumption does not hold for many traders, even the most sophisticated ones. Many economists recognize that investors are better characterized as being only boundedly rational(see Shiller(2000), Sims(2201)). Even from casual observation, few traders can pay attention to all sources of information much less understand their impact on the prices of assets that they trade. Indeed, a large literature in psychology documents the extent to which even attention is a precious cognitive resource(see, eg., Kahneman(1973), Nisbett and Ross(1980), Fiske and Taylor(1991)). A number of papers have explored the implications of limited information- processing capacity for asset prices. I will review this literature in Section II. For instance, Merton(1987) develops a static model of multiple stocks in which investors only have information about a limited number of stocks and only trade those that they have information about. Related models of limited market participation include brennan(1975) and Allen and Gale(1994). As a result, stocks that are less recognized by investors have a smaller investor base(neglected stocks) and trade at a greater discount because of limited risk sharing. More recently, Hong and Stein(1999) develop a dynamic model of a single asset in which information gradually diffuses across the investment public and investors are unable to perform the rational expectations trick of extracting information from prices. Hong and Stein(1999). My hypothesis is that the gradual diffusion of information across asset markets leads to cross-asset return predictability. This hypothesis relies on two key assumptions. The first is that valuable information that originates in one asset reaches investors in other markets only with a lag, i.e. news travels slowly across markets. The second assumption is that because of limited information-processing capacity, many (though not necessarily all) investors may not pay attention or be able to extract the information from the asset prices of markets that they do not participate in. These two assumptions taken together leads to cross-asset return predictability. My hypothesis would appear to be a very plausible one for a few reasons. To begin with, as pointed out by Merton(1987) and the subsequent literature on segmented markets and limited market participation, few investors trade all assets. Put another way, limited participation is a pervasive feature of financial markets. Indeed, even among equity money managers, there is specialization along industries such as sector or market timing funds. Some reasons for this limited market participation include tax, regulatory or liquidity constraints. More plausibly, investors have to specialize because they have their hands full trying to understand the markets that they do participate in

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A Comparative Study on the Measurement Model of Anti-Corruption Index : Anti-Corruption Index and CCEJ's Corruption Index (부패지수 측정모형에 대한 비교연구 : 서울시 시정청렴성지수 측정모형과 경실련 부패지수 측정모형을 중심으로)

  • Park, Yong-Chie;Lee, Chung-Min
    • Survey Research
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    • v.6 no.1
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    • pp.1-38
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    • 2005
  • Considering the importance of corruption index measurement model and the diffusion of popular awareness about the importance of anti-corruption, this research compared and analyzed existing corruption index measurement models. This paper has selected "Anti-Corruption Index model(ACI model)" that was developed by Seoul Development Institute and "CCEJ's Corruption Index model" which is under use by the Citizens' Coaltion for Economic Justice. These two models were analyzed in terms of appropriateness of 'the indicator and index choice method', 'the research design' and 'the use of statistical data'. This analysis shows that two models have some problems. First, at the level of indicator and index choice method, the indicators of CCEJ's corruption index model is too atomized and redundant. As not putting weight of indicator, it did not consider importance of each indicator. Citizens who evaluated the level of corruption didn't participate in the weight evaluation team, which results in failure of the model to reflect the citizens' opinion. Also, because the question about Seoul Metropolis' corruption level is not included, it is not detected difference between real corruption level and perceptive corruption level. Second, in terms of appropriateness of research design, the sample of the CCEJ' corruption index model is too small to get credibility. The objectivity of research method seems to be low because survey was performed by exit interview. In addition, 38 items are overfull in the questionnire of CCEJ's corruption index model compare to 13 items in ACI model. Also, in making up questions, the terms are redundant and unobvious. Third, in regarding with feasibility of the statistical data, the CCEJ's corruption index model uses regulation data for disciplinary punishment of 25 local governments in Seoul from 1995 to 1999. But, it is common ideas of scholars that statistical data indicates the tip of an iceberg in corruption. So for using a statistical data, it needs a data of enough quantity and has a high level credibility. In addition, objective method of giving weight is not developed. In this point of view, the use of statistical data has some limits. To solve this problem, ① objective data should be included in the indicators, ② various indicators should be developed and ③ a method of giving weight should be improved.

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Analysis of Factor's Priority for Activating the Industry of Global Content Distribution (글로벌 콘텐츠 유통산업 활성화 요인 중요도 분석)

  • Park, Chang-Mook;Jang, Hyung-Jun;Koh, Chan;Kim, Kwang-Ho
    • Journal of Digital Convergence
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    • v.12 no.4
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    • pp.11-20
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    • 2014
  • Recently K-POP's popularity and the success story of 'Psy' suggests that Korean Culture can get the possibility of entry into the global major market. Increasing the purchasing power of global contents distribution also shows that the delivery of cultural content can be a big business model to create economic benefits. However, for sustainable diffusion of Korean culture, we need efforts to expand the business scope to the global market like the establishment of global distribution platform. In this study, we investigated key factors for activating the global content distribution and then analyzed priority of importance of the factors to be utilized the strategic alternatives using AHP method. To ensure the reliability of the study, experts (30patients) who worked more than 10 years of relevant work were included as population of the questionnaire. The results of analysis, the relative importance of content aspects were higher than technical aspects and policy aspects. In the analysis of the importance of the second layer factors, the business models of policy aspects were analyzed as a factor of top priority, then high-quality content production was selected as an important factor of the next higher ranks.