• Title/Summary/Keyword: Closure Model

Search Result 487, Processing Time 0.028 seconds

Chemical Composition of PM2.5 and PM10 and Associated Polycyclic Aromatic Hydrocarbons at a Roadside and an Urban Background Area in Saitama, Japan

  • Naser, TarekMohamed;Yoshimura, Yuji;Sekiguchi, Kazuhiko;Wang, Qingyue;Sakamoto, Kazuhiko
    • Asian Journal of Atmospheric Environment
    • /
    • v.2 no.2
    • /
    • pp.90-101
    • /
    • 2008
  • The chemical compositions of $PM_{2.5}$ and $PM_{10}$ and associated high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) were investigated during winter and summer at a roadside and an urban background site in Saitama, Japan. The average concentrations of $PM_{2.5}$ exceeded the United States Environmental Protection Agency standards during both periods. Carbonaceous components were abundant in both the observed and calculated (by means of a mass closure model) chemical composition of $PM_{2.5}$. Traffic-related pollutants (elemental carbon and high-molecular-weight PAHs) were strongly associated with $PM_{2.5}$ rather than with larger particles. The mass concentrations of $PM_{2.5}$, as well as those of EC and PAHs associated with the particles, at the two sites were strongly correlated. Comparison of our data with source profile ratios indicates that diesel-powered vehicles were probably the main source of the measured PAHs. The PAHs concentrations were affected by meteorological conditions during our study. Our results highlight the need for the establishment of standards for $PM_{2.5}$ in Japan.

Analysis of Forest Cover Information Extracted by Spectral Mixture Analysis (분광혼합분석 기법에 의한 산림피복 정보의 특성 분석)

  • 이지민;이규성
    • Korean Journal of Remote Sensing
    • /
    • v.19 no.6
    • /
    • pp.411-419
    • /
    • 2003
  • An area corresponding to the spatial resolution of optical remote sensor imagery often includes more than one pure surface material. In such case, a pixel value represents a mixture of spectral reflectance of several materials within it. This study attempts to apply the spectral mixture analysis on forest and to evaluate the information content of endmember fractions resulted from the spectral unmixing. Landsat-7 ETM+ image obtained over the study area in the Kwangneung Experimental Forest was initially geo-referenced and radiometrically corrected to reduce the atmospheric and topographic attenuations. Linear mixture model was applied to separate each pixel by the fraction of six endmember: deciduous, coniferous, soil, built-up, shadow, and rice/grass. The fractional values of six endmember could be used to separate forest cover in more detailed spatial scale. In addition, the soil fraction can be further used to extract the information related to the canopy closure. We also found that the shadow effect is more distinctive at coniferous stands.

Analysis of the Impact of COVID-19 on Port Operation (컨테이너 항만운영에 대한 코로나19의 영향 분석 연구)

  • Kim, Sung-Ki;Kim, Chan-Ho
    • Journal of Navigation and Port Research
    • /
    • v.45 no.3
    • /
    • pp.155-164
    • /
    • 2021
  • The major factors that threaten port operation are diversie. Coronavirus disease-19, (COVID-19), which has recently disrupted operations worldwide, is one of them. Port operation was completely stopped due to a confirmed coronavirus involving a Russian sailor in Gamcheon Port, Busan, Korea in 2020, resulting port closure due to the infectious disease outbreak. The port is a national infrastructure facility that controls most of Korea's import and export logistics, and it is absolutely necessary to secure resilience against threats such as infectious diseases. However, due to insufficient data, this study was undertaken to determine a cause-effect relationship of infectious diseases during the container port operation using system dynamics. In addition, the port's resilience against infectious diseases was measured in terms of productivity and cargo volume through simulation. The model built via simulation analysis can actually be used to measure the resilience of a port. In the event of an infectious disease outbreak at a port, a quarantine policy scenario can be implemented and the effect compared, thereby improving the resilience.

A Study on Improved Utilization of Closed School in the Library Based on Characteristics of Closed Area - Based on the analysis of area where closed school occurs through the Socioeconomic Index - (폐교 발생 지역의 특성을 기반으로 한 도서관의 폐교 활용 제고에 관한 연구 - 폐교 발생 지역의 사회경제적 지표 분석을 기반으로 -)

  • Noh, Younghee;Ro, Ji-Yoon
    • Journal of Korean Library and Information Science Society
    • /
    • v.50 no.1
    • /
    • pp.157-176
    • /
    • 2019
  • Recently, as the number of closed schools continues to increase due to the super aging society, low fertility rate, declining school age population, There are cases in which a new facility or space is being reborn by utilizing idle facilities and sites of a closed school. The use of closed schools can be largely understood in the context of urban regeneration, the purpose of this study is to analyze the characteristics of the area where closed school occurred and to analyze the closure type using the evaluation standard of the decline area in urban regeneration projects. In this paper, we propose that the system and model of utilizing closed school in the library should be considered based on the characteristics, type, form, and implications of the are in which closed schools occurred which derived from research results.

School Closures during Coronavirus Disease 2019 Outbreak (코로나바이러스감염증-19 유행과 교육기관 등교 정상화)

  • Cho, Eun Young;Choe, Young June
    • Pediatric Infection and Vaccine
    • /
    • v.28 no.2
    • /
    • pp.57-65
    • /
    • 2021
  • School closures during the coronavirus disease 2019 (COVID-19) pandemic have been outlined in studies from different disciplines, including economics, sociology, mathematical modeling, epidemiology, and public health. In this review, we discuss the implications of school closures in the context of the current COVID-19 pandemic. Modeling studies of the effects of school closures, largely derived from the pandemic influenza model, on severe acute respiratory syndrome coronavirus 2 produced conflicting results. Earlier studies assessed the risk of school reopening by modeling transmission across schools and communities; however, it remains unclear whether the risk is due to increased transmission in adults or children. The empirical findings of the impact of school closures on COVID-19 outbreaks suggest no clear effect, likely because of heterogeneity in community infection pressure, differences in school closure strategies, or the use of multiple interventions. The benefits of school closings are unclear and not readily quantifiable; however, they must be weighed against the potential high social costs, which can also negatively affect the health of this generation.

The Study on the Development and Utilization Plan for Closed Private Universities - Based on the case of A University - (지방사립대학의 폐교에 따른 발전 방안과 활용방안에 관한 연구 - A 대학교의 중심으로 -)

  • Song, Hwa-Yeong;Han, Kun-Hee;Shin, Seung-Soo
    • Journal of Industrial Convergence
    • /
    • v.20 no.4
    • /
    • pp.7-14
    • /
    • 2022
  • The decrease in the school-age population caused the closure of private universities, but the guidelines at closed private universities are ambiguous, causing confusion. Therefore, this study intends to suggest a plan to utilize the closed school university. The government aims to increase the possibility of selling closed schools by preventing alley slums through the recovery of alley commercial districts and local communities. The data were collected through a Google survey from September 30 to October 8, 2021 and an on-site interview conducted on October 2, 2021. A total of 84 nearby citizens of the closed school university were surveyed, and on-site interviews were conducted with a total of five people. The collected data suggested the direction of utilization plan for closed school building. This study will present a model for the use of closed school property in the future and contribute to the establishment of urban regeneration policies.

Empirical Analysis of Effect of Entrepreneurship on Export Performance: Focusing on the Mediated Effect of Technology Capability and Export Support Policy of Start-Ups

  • Joo, Se-Hwan;Shin, Gun-Hoon
    • Journal of Korea Trade
    • /
    • v.24 no.6
    • /
    • pp.173-193
    • /
    • 2020
  • Purpose - This study aims to examine the effect of entrepreneurship of start-ups on export performance when the business closure rate is higher than business start-up rate in Korea. Thus, this study analyzes various factors for start-ups established within the past seven years and uses export performance as an indicator. Prior to analysis of factors, the study defines the concepts of start-up factors based on various studies. Design/methodology - In order to analyze the export performance of startups, this study conducted an empirical analysis using statistical analysis. Theories were established based on previous studies, and hypotheses and research models were designed based on the established theories. Subsequently, in order to verify the research hypothesis and research model, factor analysis such as validity and reliability, and structural equation modeling were analyzed. Findings - As a result of analysis based on previous studies, we found that there is a difference between theoretical and practical aspects. Whereas previous studies showed that market orientation, technology orientation, and social capital have a direct impact on export performance, the present study analyzed that there is no such impact, and that technology capabilities were important as a result of the unique traits of start-ups. Originality/value - Existing studies have limitations in understanding the overall characteristics of a company by using market orientation, technology orientation, and social capital as individual independent variables. In addition, the existing researches have been analyzed in relation to corporate performance, whereas this study has been limited to export performance, so it can be regarded as different from other studies.

Is Tranexamic Acid an Effective Prevention in the Formation of Epidural Fibrosis? Histological Evaluation in the Rats

  • Esra Circi;Yunus Atici;Alican Baris;Ahmet Senel;Cem Leblebici;Saltuk Bugra Tekin;Yusuf Ozturkmen
    • Journal of Korean Neurosurgical Society
    • /
    • v.66 no.5
    • /
    • pp.503-510
    • /
    • 2023
  • Objective : The present study aimed to determine the topical and systemic efficacy of tranexamic acid (TXA) on epidural fibrosis in a rat laminectomy model. Methods : Thirty-two 12-month-old adult Sprague-Dawley rats were used in this study. Each rat underwent bilateral laminectomy at the L1 and L2 vertebral levels. Rats were divided into four groups : in group I (control group, n=8), a laminectomy was performed and saline solution was applied into the surgical space. In group II (topical group, n=8), laminectomy was performed and 30 mg/kg TXA was applied to the surgical site before skin closure. In group III (systemic group, n=8), 30 mg/kg TXA was administered intravenously via the tail vein in the same session as the surgical procedure. In group IV (topical and systemic group, n=8), TXA was administered 30 mg/kg both topical and intravenous. The rats were sacrificed at 4 weeks postoperatively. Masson's trichrome and hematoxylin and eosin were used to assess acute inflammatory cells, chronic inflammatory cells, vascular proliferation, and epidural fibrosis. Results : Epidural fibrosis, acute inflammation, chronic inflammation, and sum histologic score value were significantly lower in the systemic TXA group, systemic and topical TXA groups than in the control group (p<0.05). In addion, the sum histologic score was significantly lower in the topical TXA group than in the control group (p<0.05). Conclusion : In this study, epidural fibrosis formation was prevented more by systemic application, but the topical application was found to be effective when compared to the control group. As a result, we recommend the systemic and topical use of TXA to prevent epidural fibrosis during spinal surgery.

THREE-DIMENSIONAL FINITE ELEMENT ANALYSIS OF THE PHENOMENON PRODUCED DURING RETRACTION OF FOUR MAXILLARY INCISORS (상악 4절치의 후방견인시 나타나는 현상에 관한 유한요소법적 분석)

  • Cheon, Ok-Jin;Kim, Tae-Woo;Suhr, Cheong-Hoon
    • The korean journal of orthodontics
    • /
    • v.25 no.5 s.52
    • /
    • pp.525-541
    • /
    • 1995
  • This study was designed to investigate force systems and tooth movements produced by retraction archwire during retraction of four maxillary incisors after the maxillary canine retraction into the maxillary first premolar extraction space using the computer-aided three-dimensional finite element method. A three-dimensional finite element model, consisting of 2248 elements and 3194 nodes, was constructed. The model consisted of maxillary teeth and surrounding periodontal membranes, .022'$\times$.028'-slot brackets, and 5 types of retraction archwires(.019'$\times$.025' stainless steel archwire) modeled using the beam elements. The contact between the wire and the bracket slot was modeled using the gap elements because of the non-linear elastic behaviors of the contact between them. The forces and moments, End displacements produced by retraction archwire were measured at various conditions to investigate the difference according to types of loops, magnitudes of activation force, gable angle, and anterior lingual root torque. The results were expressed quantitative and visual ways in the three-dimensional method. The following conclusions can be drawn from this study.1. When the tear-drop loop archwire was activated, the mesio-distal and lingual translational movements of the teeth helped to close the extraction space, but unwanted movements of the teeth including intrusions and extrusions, and rotational movements in each direction occurred. 2. Activation of T-loop archwire compared with those of other types of retraction archwires produced the least translational movements of the teeth helped to space closure and also the least unwanted movements of the teeth. 3. Increasing amount of activation in the tear-drop archwire led not only to increase of translational movements of the teeth helped to space closure, but also to increase of unwanted movements of the teeth. 4. Addition of gable bend in the tear-drop archwire helped anterior teeth to translational movements in the mesio-distal direction, but increased unwanted movements of the teeth 5. Addition of anterior lingual root torque in the tear-drop archwire helped central and lateral incisor to improve their facio-lingual inclination, but increased unwanted movements of the teeth.

  • PDF

The Impacts of Need for Cognitive Closure, Psychological Wellbeing, and Social Factors on Impulse Purchasing (인지폐합수요(认知闭合需要), 심리건강화사회인소대충동구매적영향(心理健康和社会因素对冲动购买的影响))

  • Lee, Myong-Han;Schellhase, Ralf;Koo, Dong-Mo;Lee, Mi-Jeong
    • Journal of Global Scholars of Marketing Science
    • /
    • v.19 no.4
    • /
    • pp.44-56
    • /
    • 2009
  • Impulse purchasing is defined as an immediate purchase with no pre-shopping intentions. Previous studies of impulse buying have focused primarily on factors linked to marketing mix variables, situational factors, and consumer demographics and traits. In previous studies, marketing mix variables such as product category, product type, and atmospheric factors including advertising, coupons, sales events, promotional stimuli at the point of sale, and media format have been used to evaluate product information. Some authors have also focused on situational factors surrounding the consumer. Factors such as the availability of credit card usage, time available, transportability of the products, and the presence and number of shopping companions were found to have a positive impact on impulse buying and/or impulse tendency. Research has also been conducted to evaluate the effects of individual characteristics such as the age, gender, and educational level of the consumer, as well as perceived crowding, stimulation, and the need for touch, on impulse purchasing. In summary, previous studies have found that all products can be purchased impulsively (Vohs and Faber, 2007), that situational factors affect and/or at least facilitate impulse purchasing behavior, and that various individual traits are closely linked to impulse buying. The recent introduction of new distribution channels such as home shopping channels, discount stores, and Internet stores that are open 24 hours a day increases the probability of impulse purchasing. However, previous literature has focused predominantly on situational and marketing variables and thus studies that consider critical consumer characteristics are still lacking. To fill this gap in the literature, the present study builds on this third tradition of research and focuses on individual trait variables, which have rarely been studied. More specifically, the current study investigates whether impulse buying tendency has a positive impact on impulse buying behavior, and evaluates how consumer characteristics such as the need for cognitive closure (NFCC), psychological wellbeing, and susceptibility to interpersonal influences affect the tendency of consumers towards impulse buying. The survey results reveal that while consumer affective impulsivity has a strong positive impact on impulse buying behavior, cognitive impulsivity has no impact on impulse buying behavior. Furthermore, affective impulse buying tendency is driven by sub-components of NFCC such as decisiveness and discomfort with ambiguity, psychological wellbeing constructs such as environmental control and purpose in life, and by normative and informational influences. In addition, cognitive impulse tendency is driven by sub-components of NFCC such as decisiveness, discomfort with ambiguity, and close-mindedness, and the psychological wellbeing constructs of environmental control, as well as normative and informational influences. The present study has significant theoretical implications. First, affective impulsivity has a strong impact on impulse purchase behavior. Previous studies based on affectivity and flow theories proposed that low to moderate levels of impulsivity are driven by reduced self-control or a failure of self-regulatory mechanisms. The present study confirms the above proposition. Second, the present study also contributes to the literature by confirming that impulse buying tendency can be viewed as a two-dimensional concept with both affective and cognitive dimensions, and illustrates that impulse purchase behavior is explained mainly by affective impulsivity, not by cognitive impulsivity. Third, the current study accommodates new constructs such as psychological wellbeing and NFCC as potential influencing factors in the research model, thereby contributing to the existing literature. Fourth, by incorporating multi-dimensional concepts such as psychological wellbeing and NFCC, more diverse aspects of consumer information processing can be evaluated. Fifth, the current study also extends the existing literature by confirming the two competing routes of normative and informational influences. Normative influence occurs when individuals conform to the expectations of others or to enhance his/her self-image. Whereas informational influence occurs when individuals search for information from knowledgeable others or making inferences based upon observations of the behavior of others. The present study shows that these two competing routes of social influence can be attributed to different sources of influence power. The current study also has many practical implications. First, it suggests that people with affective impulsivity may be primary targets to whom companies should pay closer attention. Cultivating a more amenable and mood-elevating shopping environment will appeal to this segment. Second, the present results demonstrate that NFCC is closely related to the cognitive dimension of impulsivity. These people are driven by careless thoughts, not by feelings or excitement. Rational advertising at the point of purchase will attract these customers. Third, people susceptible to normative influences are another potential target market. Retailers and manufacturers could appeal to this segment by advertising their products and/or services as products that can be used to identify with or conform to the expectations of others in the aspiration group. However, retailers should avoid targeting people susceptible to informational influences as a segment market. These people are engaged in an extensive information search relevant to their purchase, and therefore more elaborate, long-term rational advertising messages, which can be internalized into these consumers' thought processes, will appeal to this segment. The current findings should be interpreted with caution for several reasons. The study used a small convenience sample, and only investigated behavior in two dimensions. Accordingly, future studies should incorporate a sample with more diverse characteristics and measure different aspects of behavior. Future studies should also investigate personality traits closely related to affectivity theories. Trait variables such as sensory curiosity, interpersonal curiosity, and atmospheric responsiveness are interesting areas for future investigation.

  • PDF