• 제목/요약/키워드: a diffusion model

검색결과 2,096건 처리시간 0.03초

Hyperoxia-Induced ΔR1: MRI Biomarker of Histological Infarction in Acute Cerebral Stroke

  • Kye Jin Park;Ji-Yeon Suh;Changhoe Heo;Miyeon Kim;Jin Hee Baek;Jeong Kon Kim
    • Korean Journal of Radiology
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    • 제23권4호
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    • pp.446-454
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    • 2022
  • Objective: To evaluate whether hyperoxia-induced ΔR1 (hyperO2ΔR1) can accurately identify histological infarction in an acute cerebral stroke model. Materials and Methods: In 18 rats, MRI parameters, including hyperO2ΔR1, apparent diffusion coefficient (ADC), cerebral blood flow and volume, and 18F-fluorodeoxyglucose uptake on PET were measured 2.5, 4.5, and 6.5 hours after a 60-minutes occlusion of the right middle cerebral artery. Histological examination of the brain was performed immediately following the imaging studies. MRI and PET images were co-registered with digitized histological images. The ipsilateral hemisphere was divided into histological infarct (histological cell death), non-infarct ischemic (no cell death but ADC decrease), and nonischemic (no cell death or ADC decrease) areas for comparisons of imaging parameters. The levels of hyperO2ΔR1 and ADC were measured voxel-wise from the infarct core to the non-ischemic region. The correlation between areas of hyperO2ΔR1-derived infarction and histological cell death was evaluated. Results: HyperO2ΔR1 increased only in the infarct area (p ≤ 0.046) compared to the other areas. ADC decreased stepwise from non-ischemic to infarct areas (p = 0.002 at all time points). The other parameters did not show consistent differences among the three areas across the three time points. HyperO2ΔR1 sharply declined from the core to the border of the infarct areas, whereas there was no change within the non-infarct areas. A hyperO2ΔR1 value of 0.04 s-1 was considered the criterion to identify histological infarction. ADC increased gradually from the infarct core to the periphery, without a pronounced difference at the border between the infarct and non-infarct areas. Areas of hyperO2ΔR1 higher than 0.04 s-1 on MRI were strongly positively correlated with histological cell death (r = 0.862; p < 0.001). Conclusion: HyperO2ΔR1 may be used as an accurate and early (2.5 hours after onset) indicator of histological infarction in acute stroke.

열풍건조 시의 건조 온도와 입경에 따른 콩(Glycine max)의 건조 특성 (Effect of Grain Size and Drying Temperature on Drying Characteristics of Soybean (Glycine max) Using Hot Air Drying)

  • 박현우;한원영;윤원병
    • 한국식품영양과학회지
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    • 제44권11호
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    • pp.1700-1707
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    • 2015
  • 입경과 건조 온도에 따른 수분 함량의 변화에 대한 연구를 수행하고 콩의 건조 특성을 박층 건조 모델을 적용하여 설명하였으며, Midilli-Kucuk 모델이 콩의 열풍건조를 서술하기에 가장 적합하였다($R^2$ >0.99). 입경을 달리한 S, M, L 군 모두에서 건조 온도가 증가할수록 건조 속도가 증가하였으며, 같은 건조 온도에서 입경이 증가할수록 건조 속도가 감소하였고, 초기 수분 함량(25%)으로부터 목표 수분 함량(10%)까지 건조시키기 위해 25, 35, $45^{\circ}C$ 건조에서 L군과 S군의 필요 건조 시간은 1,160분과 787분, 598분과 391분, 405분과 260분을 나타내어 건조 온도뿐 아니라 입경 역시 콩의 열풍건조를 위해 반드시 고려되어야 함을 확인하였다. 유효 수분확산도는 Fick's second law를 사용하여 평가되었다. 유효 수분확산도는 입경이 증가하고 건조 온도가 증가할수록 증가하였으며, 콩의 크기에 따른 콩의 온도 증가와 건조속도 증가에 의한 다공성 조직의 수축이 수분확산도의 차이를 유도하였음을 확인할 수 있었다. S, M, L 군의 유효 수분확산도는 각각 $0.83{\times}10^{-10}{\sim}1.51{\times}10^{-10}m^2/s$, $1.17{\times}10^{-10}{\sim}2.17{\times}10^{-10}m^2/s$, $1.53{\times}10^{-10}{\sim}2.95{\times}10^{-10}m^2/s$의 범위를 나타내었다. 이는 대부분의 식품 및 bioproduct의 수분확산도 범위 내에 속했다. 활성화 에너지($E_a$)는 건조 온도로부터 Arrhenius 식을 사용하여 평가되었다. 열풍건조에서 콩의 $E_a$는 24.73 kJ/mol의 값을 나타냈으며, 입경에 따른 유의적 차이는 없었다.

스마트폰의 지각된 가치와 지속적 사용의도, 그리고 개인 혁신성의 조절효과 (An Empirical Study on Perceived Value and Continuous Intention to Use of Smart Phone, and the Moderating Effect of Personal Innovativeness)

  • 한준형;강성배;문태수
    • Asia pacific journal of information systems
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    • 제23권4호
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    • pp.53-84
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    • 2013
  • With rapid development of ICT (Information and Communications Technology), new services by the convergence of mobile network and application technology began to appear. Today, smart phone with new ICT convergence network capabilities is exceedingly popular and very useful as a new tool for the development of business opportunities. Previous studies based on Technology Acceptance Model (TAM) suggested critical factors, which should be considered for acquiring new customers and maintaining existing users in smart phone market. However, they had a limitation to focus on technology acceptance, not value based approach. Prior studies on customer's adoption of electronic utilities like smart phone product showed that the antecedents such as the perceived benefit and the perceived sacrifice could explain the causality between what is perceived and what is acquired over diverse contexts. So, this research conceptualizes perceived value as a trade-off between perceived benefit and perceived sacrifice, and we need to research the perceived value to grasp user's continuous intention to use of smart phone. The purpose of this study is to investigate the structured relationship between benefit (quality, usefulness, playfulness) and sacrifice (technicality, cost, security risk) of smart phone users, perceived value, and continuous intention to use. In addition, this study intends to analyze the differences between two subgroups of smart phone users by the degree of personal innovativeness. Personal innovativeness could help us to understand the moderating effect between how perceptions are formed and continuous intention to use smart phone. This study conducted survey through e-mail, direct mail, and interview with smart phone users. Empirical analysis based on 330 respondents was conducted in order to test the hypotheses. First, the result of hypotheses testing showed that perceived usefulness among three factors of perceived benefit has the highest positive impact on perceived value, and then followed by perceived playfulness and perceived quality. Second, the result of hypotheses testing showed that perceived cost among three factors of perceived sacrifice has significantly negative impact on perceived value, however, technicality and security risk have no significant impact on perceived value. Also, the result of hypotheses testing showed that perceived value has significant direct impact on continuous intention to use of smart phone. In this regard, marketing managers of smart phone company should pay more attention to improve task efficiency and performance of smart phone, including rate systems of smart phone. Additionally, to test the moderating effect of personal innovativeness, this research conducted multi-group analysis by the degree of personal innovativeness of smart phone users. In a group with high level of innovativeness, perceived usefulness has the highest positive influence on perceived value than other factors. Instead, the analysis for a group with low level of innovativeness showed that perceived playfulness was the highest positive factor to influence perceived value than others. This result of the group with high level of innovativeness explains that innovators and early adopters are able to cope with higher level of cost and risk, and they expect to develop more positive intentions toward higher performance through the use of an innovation. Also, hedonic behavior in the case of the group with low level of innovativeness aims to provide self-fulfilling value to the users, in contrast to utilitarian perspective, which aims to provide instrumental value to the users. However, with regard to perceived sacrifice, both groups in general showed negative impact on perceived value. Also, the group with high level of innovativeness had less overall negative impact on perceived value compared to the group with low level of innovativeness across all factors. In both group with high level of innovativeness and with low level of innovativeness, perceived cost has the highest negative influence on perceived value than other factors. Instead, the analysis for a group with high level of innovativeness showed that perceived technicality was the positive factor to influence perceived value than others. However, the analysis for a group with low level of innovativeness showed that perceived security risk was the second high negative factor to influence perceived value than others. Unlike previous studies, this study focuses on influencing factors on continuous intention to use of smart phone, rather than considering initial purchase and adoption of smart phone. First, perceived value, which was used to identify user's adoption behavior, has a mediating effect among perceived benefit, perceived sacrifice, and continuous intention to use smart phone. Second, perceived usefulness has the highest positive influence on perceived value, while perceived cost has significant negative influence on perceived value. Third, perceived value, like prior studies, has high level of positive influence on continuous intention to use smart phone. Fourth, in multi-group analysis by the degree of personal innovativeness of smart phone users, perceived usefulness, in a group with high level of innovativeness, has the highest positive influence on perceived value than other factors. Instead, perceived playfulness, in a group with low level of innovativeness, has the highest positive factor to influence perceived value than others. This result shows that early adopters intend to adopt smart phone as a tool to make their job useful, instead market followers intend to adopt smart phone as a tool to make their time enjoyable. In terms of marketing strategy for smart phone company, marketing managers should pay more attention to identify their customers' lifetime value by the phase of smart phone adoption, as well as to understand their behavior intention to accept the risk and uncertainty positively. The academic contribution of this study primarily is to employ the VAM (Value-based Adoption Model) as a conceptual foundation, compared to TAM (Technology Acceptance Model) used widely by previous studies. VAM is useful for understanding continuous intention to use smart phone in comparison with TAM as a new IT utility by individual adoption. Perceived value dominantly influences continuous intention to use smart phone. The results of this study justify our research model adoption on each antecedent of perceived value as a benefit and a sacrifice component. While TAM could be widely used in user acceptance of new technology, it has a limitation to explain the new IT adoption like smart phone, because of customer behavior intention to choose the value of the object. In terms of theoretical approach, this study provides theoretical contribution to the development, design, and marketing of smart phone. The practical contribution of this study is to suggest useful decision alternatives concerned to marketing strategy formulation for acquiring and retaining long-term customers related to smart phone business. Since potential customers are interested in both benefit and sacrifice when evaluating the value of smart phone, marketing managers in smart phone company has to put more effort into creating customer's value of low sacrifice and high benefit so that customers will continuously have higher adoption on smart phone. Especially, this study shows that innovators and early adopters with high level of innovativeness have higher adoption than market followers with low level of innovativeness, in terms of perceived usefulness and perceived cost. To formulate marketing strategy for smart phone diffusion, marketing managers have to pay more attention to identify not only their customers' benefit and sacrifice components but also their customers' lifetime value to adopt smart phone.

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

  • 박창묵;장형준;고찬;김광호
    • 디지털융복합연구
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    • 제12권4호
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    • pp.11-20
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    • 2014
  • 최근 K-POP의 인기와 '싸이'의 성공은 한국 문화콘텐츠의 주류시장 편입 가능성을 시사하고 있다. 또한 한류콘텐츠의 글로벌 구매력 증대는 문화콘텐츠의 유통이 상당한 경제적 이익을 확보할 수 있는 비즈니스 모델이 될 수 있음을 보여준다. 하지만 한류문화의 지속 확산을 위해서는 안정적으로 콘텐츠를 공급할 수 있는 글로벌 유통플랫폼의 구축 등과 같은 글로벌 시장으로 사업의 범위를 확대하는 노력이 필요하다. 따라서 본 연구에서는 글로벌 콘텐츠 유통산업의 활성화를 위해 필수적인 핵심요인들을 파악해 보고, 그 요인들의 중요도를 분석하여 이를 활용한 전략적 대안을 제시하기 위하여 AHP 기법을 활용하였다. 연구결과의 신뢰성 확보를 위하여 인터뷰 대상 전문가 모집단은 관련 업무에 10년 이상 종사한 전문가(30명)를 대상으로 하였다. 연구결과, 콘텐츠 측면의 상대적 중요도가 정책적 측면과 기술적 측면보다 높게 분석되었다. 하부요인 중요도 분석에서는 정책적 측면의 비즈니스 모델이 가장 우선시 되어야할 요인으로 분석되었으며, 고품질의 콘텐츠제작이 그 다음 순위의 중요한 요인으로 선택되었다.

영재교육기관 컨설팅에 대한 영재교육 이해관계자의 관심도 연구 (The Study on Stakeholder' Concerns Regarding Consulting for Gifted Education Institutes)

  • 이미순;손성국
    • 영재교육연구
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    • 제26권2호
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    • pp.235-255
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    • 2016
  • 본 연구는 영재교육기관 컨설팅에 대한 관심도를 조사하기 위하여, 영재교육 이해관계자를 대상으로 설문을 실시하였다. 122명의 이해관계자가 SoCQ(The Stages of Concerns Questionnaire, Hall & Hord, 2011)에 응답하였으며, Hall과 Hord(2011)의 채점표(SoCQ scoring device)를 활용하여 이해관계자의 응답 반응을 상대적 강도(relative intensity)로 환산하였다. 본 연구는 영재교육 이해관계자의 특성(소속기관, 영재교육경력, 영재업무 지속여부, 영재 연수유형)에 따른 영재교육기관 컨설팅에 대한 관심도를 살펴보기 위하여 t 분석과 일원분산분석을 실시하였다. 연구결과, 영재교육 이해관계자들은 1단계(정보)에 대한 관심이 가장 높고, 4단계(결과)에 대한 관심이 가장 낮은 변화초기 단계의 양상을 보여주었다. 한편, 전문가 연수를 받은 이해관계자들은 6단계(재조정)에 대한 관심도가 높게 나타나, 영재교육기관 컨설팅에 대하여 저항을 보이는 것으로 나타났다. 이에 본 연구에서는 연구결과에 기초하여 성공적인 영재교육기관 컨설팅을 정착하고 확산하는 방안을 제안하였다.

금강수계 내 환경기초시설 운영실태에 관한 연구 (A Study of Actual Condition on Operation and Management of Environmental Infrastructure in the Geum River System)

  • 이재운;박동기;권영호
    • 환경위생공학
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    • 제24권1호
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    • pp.1-12
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    • 2009
  • The various environmental problems that we face on today are basically about environmental quality. Since early 1960s affluent material was produced because of remarkable economic growth by many cooperations. However, for the lack of environmental policy, environmental pollutions has been serious. The central government should transfer the producing and consuming structure to environmental affinity through the regulations for developing Korea as a model of environmental nation which takes an active part in global environmental programme and in which the environment and economy are well harmonized. Moreover, the central government should take the lead in prevention of environmental pollution through the direct policies such as strengthening the discharge limit or setting up environmental basic institutions by securing budget for conserving environment. This thesis emphasize on the public institution among many environmental basic institutions for environmental anti-pollution project. It will find the problems with running those institutions, and will suggest the preview of improvement. Also, it is necessary to investigate of variation trend for inflow and pollutant loading to environmental infrastructure as increased of the diffusion rate as established and maintenance of sewer system. The purpose of this study is to investigate for inflow and pollutant loading to environmental infrastructure, and also to provide the method of efficiently maintenance and management. The results obtained were summarized as follows; 1. Survey of actual condition on operation and management of environmental infrastructure was evaluated the propriety of treatment process and problem of plant management. 2. Analysis of pollutant loading contribution for river system of environmental infrastructure with data analysis of water quality measuring network. 3. To investigate on case study for efficiently maintenance and management of environmental infrastructure. The result on this study was provide the method of efficiently maintenance and management with survey for establish and repair of sewer system and survey of actual condition on operation and management of environmental infrastructure in the water area of discharge to Geum River System. Application as guideline for establish and management of environmental infrastructure, and management of Geum River System. Also, application for preliminary data for fulfill-assess of total effluent regulation of water pollution.

Feed Resources for Animals in Asia: Issues, Strategies for Use, Intensification and Integration for Increased Productivity

  • Devendra, C.;Leng, R.A.
    • Asian-Australasian Journal of Animal Sciences
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    • 제24권3호
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    • pp.303-321
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    • 2011
  • The availability and efficient use of the feed resources in Asia are the primary drivers of performance to maximise productivity from animals. Feed security is fundamental to the management, extent of use, conservation and intensification for productivity enhancement. The awesome reality is that current supplies of animal proteins are inadequate to meet human requirements in the face of rapidly depleting resources: arable land, water, fossil fuels, nitrogenous and other fertilisers, and decreased supplies of cereal grains. The contribution of the ruminant sector lags well behind that of non-ruminant pigs and poultry. It is compelling therefore to shift priority for the development of ruminants (buffaloes, cattle, goats and sheep) in key agro-ecological zones (AEZs), making intensive use of the available biomass from the forage resources, crop residues, agro-industrial by-products (AIBP) and other non-conventional feed resources (NCFR). Definitions are given of successful and failed projects on feed resource use. These were used to analyse 12 case studies, which indicated the value of strong participatory efforts with farmers, empowerment, and the benefits from animals of productivity-enhancing technologies and integrated natural resource management (NRM). However, wider replication and scaling up were inadequate in project formulation, including systems methodologies that promoted technology adoption. There was overwhelming emphasis on component technology applications that were duplicated across countries, often wasteful, the results and relevance of which were not clear. Technology delivery via the traditional model of research-extension linkage was also inadequate, and needs to be expanded to participatory research-extension-farmer linkages to accelerate diffusion of technologies, wider adoption and impacts. Other major limitations concerned with feed resource use are failure to view this issue from a farming systems perspective, strong disciplinary bias, and poor links to real farm situations. It is suggested that improved efficiency in feed resource use and increased productivity from animals in the future needs to be cognisant of nine strategies. These include priorities for feed resource use; promoting intensive use of crop residues; intensification of integrated ruminant-oil palm systems and use of oil palm by-products; priority for urgent, wider technology application, adoption and scaling up; rigorous application of systems methodologies; development of adaptation and mitigation options for the effects of climate change on feed resources; strengthening research-extension-farmer linkages; development of year round feeding systems; and striving for sustainability of integrated farming systems. These strategies together form the challenges for the future.

입상활성탄에 의한 수용액으로부터 오로라 레드의 흡착에 대한 평형, 동력학 및 열역학 파라미터에 관한 연구 (Equilibrium, Kinetic and Thermodynamic Parameter Studies on Adsorption of Allura Red from Aqueous Solution by Granular Activated Carbon)

  • 이종집
    • 공업화학
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    • 제25권4호
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    • pp.430-436
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    • 2014
  • 오로라레드(Allura Red, AR)는 수용성의 유해한 타르계 식품착색제(적색 40호)이다. 역청탄계 입상활성탄을 사용한 AR의 회분식 흡착실험은 흡착제의 양, 초기농도, 접촉시간과 흡착온도를 조작변수로 선택하여 수행되었다. 흡착평형자료를 가지고 Langmuir와 Freundlich 및 Temkin 흡착등온식에 대한 적합성을 평가하였다. 흡착평형은 Langmuir 흡착등온식이 더 잘 맞았으며, 계산된 분리계수($R_L$) 값으로부터 입상활성탄이 AR을 효과적으로 처리할 수 있다는 것을 알 수 있었다. Temkin parameter, B의 값은 1.62~3.367 J/mol로 흡착공정이 물리흡착임을 나타내었다. 흡착속도실험으로부터, 입자내확산속도상수($k_m$)는 온도증가와 함께 커졌으며, 흡착공정은 유사이차반응속도식에 잘 맞았음을 알았다. 흡착공정의 특성을 평가하기 위하여 활성화에너지, 엔탈피, 엔트로피 및 Gibbs 자유에너지변화와 같은 열역학 파라미터들을 298~318 K의 온도 범위에서 조사하였다. Gibbs 자유에너지변화값(${\Delta}G$ = -7.02~-8.79 kJ/mol)과 엔탈피변화값(${\Delta}H$ = + 82.2 kJ/mol)으로부터 흡착공정이 자발적이고 흡열과정임을 알았다.

미세먼지 저감대책으로서 바람길 적용 방안 : 세종시를 대상으로 (Application of Ventilation Corridor to Mitigate Particulate Matter for the Sejong-Si)

  • 남성우;성선용;박종순
    • 한국콘텐츠학회논문지
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    • 제20권3호
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    • pp.1-9
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    • 2020
  • 본 연구에서는 내륙 분지에 위치하여 대기 정체율이 높은 세종시를 대상으로 미세먼지의 저감을 위한 바람길의 적용방안을 도출하고 정책적 대안을 제시하였다. 도시내 바람길의 도입을 위해서는 첫째, 신도시 건설에 따른 신선한 대기의 변화 흐름을 파악하고 둘째, 도시공간에서 바람길을 확보함으로써 대기순환을 촉진해야 함을 밝혀낼 수 있었다. 본 연구에서는 미세먼지 저감 효과를 검증하기 위하여 전산유체역학모형을 활용하였다. 구체적으로는 도시 건설 전과 후의 탁월풍의 풍속, 풍향 변화와 일몰 후 생성된 시원한 공기가 낮은 지대를 따라 흐르는 특성이 분석되었다. 이와 더불어 블록단위에서 바람길과 순응하는 건축물을 배치 시 미세먼지 저감 효과를 정량적으로 검증하였다. 모의실험을 통해 제시 가능한 정책적 함의는 다음과 같다. 첫째, 산, 숲, 골짜기에서 내려오는 신선한 공기가 도시 안으로 원활히 유입, 분산되어 미세먼지 농도를 낮출 수 있도록 바람 통로를 조성하고, 적절한 건축물 배치계획을 수립한다. 둘째, 미세먼지 농도가 낮은 지역에는 공원, 광장, 놀이터 등 공공시설들을 우선적으로 설치하여 미세먼지로부터 안전한 옥외활동을 유인하도록 한다. 마지막으로, 지구단위계획 등 도시계획 수립 과정에서 바람길 분석을 통해 최적의 대안을 마련할 것을 제안한다.

전기 및 수소차 보급 확산의 환경적·경제적 영향분석: 계산가능일반균형모형(CGE)의 적용 (Environmental and Economic Impact of EV and FCEV Penetration into the Automobile Industry: A CGE Approach)

  • 한택환;임동순;김진태
    • 자원ㆍ환경경제연구
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    • 제28권2호
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    • pp.231-276
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    • 2019
  • 본 연구는 정태적 계산가능일반균형 모형을 사용하여 전기 및 수소차 도입이 국내총생산과 이산화탄소 배출 등에 미치는 영향을 분석하고 평가하였다. 전기 및 수소차 확산이 경제에 미치는 영향에 대한 기존의 견해는 투입구조가 투입절약적으로 변화하기 때문에 경제에 부정적인 영향을 미칠 수 있다는 견해와 전기 및 수소차의 투입절약적 기술진보가 경제에 긍정적인 영향을 준다는 견해가 병존하고 있다. 또한 전기 및 수소차 도입이 가져올 이산화탄소 배출에 관하여서도 분명한 결론은 부재하다. 본 연구는 이러한 전기차 수소차의 환경적 경제적 영향에 대한 견해의 불일치에 대한 하나의 답을 모색하기 위한 시도이다. 본 연구는 전기차 및 수소차가 자동차산업 내에서의 확산에 대한 Bass 모형의 결과를 계산가능일반균형모형(CGE)에 충격으로 통합시키는 방식의 접근을 취하였다. 자동차산업과 자동차 사용 산업의 투입계수와 에너지 최종수요의 변화를 충격으로 주는 계산가능일반균형모형 분석을 통하여 경제 환경적 영향을 추정한 결과 전기차는 이산화탄소 배출 면에서 부정적인 영향을 주고 반면에 수소차는 이산화탄소 배출을 감소시키며, 국내총생산 면에서는 전기차와 수소차 공히 긍정적인 영향을 가져오는 것으로 나타났다. 수소차는 전기차보다 이산화탄소와 국내총생산 면에서 우위를 가지고 있는 것으로 나타났다. 전기차 수소차의 이산화탄소 배출량 변화패턴은 다음과 같이 설명된다. 자동차 사용부문 이산화탄소 배출 측면에서 전기차는 배출량 소폭 증대, 수소차는 소폭감소라는 상반된 결과를 보인다. 그러나 전기차 수소차 공히 자동차 제조 관련 부문에서의 이산화탄소 배출이 증대하는 것으로 나타나고 있으나 이 증가 폭이 자동차 사용부문에서의 변화의 크기보다 상당히 작다. 전기차 수소차의 이산화탄소 배출 패턴은 이 두 가지 효과가 결합하여 나타난 것으로 해석된다.