Analysis of Quantization Noise in Magnetic Resonance Imaging Systems (자기공명영상 시스템의 양자화잡음 분석)
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- Investigative Magnetic Resonance Imaging
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- v.8 no.1
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- pp.42-49
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- 2004
Purpose : The quantization noise in magnetic resonance imaging (MRI) systems is analyzed. The signal-to-quantization noise ratio (SQNR) in the reconstructed image is derived from the level of quantization in the signal in spatial frequency domain. Based on the derived formula, the SQNRs in various main magnetic fields with different receiver systems are evaluated. From the evaluation, the quantization noise could be a major noise source determining overall system signal-to-noise ratio (SNR) in high field MRI system. A few methods to reduce the quantization noise are suggested. Materials and methods : In Fourier imaging methods, spin density distribution is encoded by phase and frequency encoding gradients in such a way that it becomes a distribution in the spatial frequency domain. Thus the quantization noise in the spatial frequency domain is expressed in terms of the SQNR in the reconstructed image. The validity of the derived formula is confirmed by experiments and computer simulation. Results : Using the derived formula, the SQNRs in various main magnetic fields with various receiver systems are evaluated. Since the quantization noise is proportional to the signal amplitude, yet it cannot be reduced by simple signal averaging, it could be a serious problem in high field imaging. In many receiver systems employing analog-to-digital converters (ADC) of 16 bits/sample, the quantization noise could be a major noise source limiting overall system SNR, especially in a high field imaging. Conclusion : The field strength of MRI system keeps going higher for functional imaging and spectroscopy. In high field MRI system, signal amplitude becomes larger with more susceptibility effect and wider spectral separation. Since the quantization noise is proportional to the signal amplitude, if the conversion bits of the ADCs in the receiver system are not large enough, the increase of signal amplitude may not be fully utilized for the SNR enhancement due to the increase of the quantization noise. Evaluation of the SQNR for various systems using the formula shows that the quantization noise could be a major noise source limiting overall system SNR, especially in three dimensional imaging in a high field imaging. Oversampling and off-center sampling would be an alternative solution to reduce the quantization noise without replacement of the receiver system.
The distribution patterns of Chromophoric Dissolved Organic Matter (CDOM) and the chemical characteristics of CDOM in the Seomjin river estuary were investigated in March, June and July 2012 in order to determine the spatial and temporal variability of CDOM along the salinity gradient considering the effects of mixing, nutrients and Chl a. The average CDOM values were
With the slowdown in environmental issues and the change of environmental consciousness, ecotourism is being discussed in various social fields. Ecotourism is being popularized for environmental protection, and now it is becoming a mainstream product from one of mass tourism. Ecotourism's emphasis on sustainable development in the tourism destination's society, economy, and environment, through ecotourism study and education, enable people to understand the core value of the ecological environment. 2011 was nominated as "the Year of World Forest" by the UN. In the recent years, forests are becoming increasingly important with their own values and functions in environment, economy, society, and culture. In particular, the global environmental issues caused by climate change are becoming an international agenda. Forests are the only effective solution for the carbon dioxide that causes global warming. Moreover, forests constitute a major part of ecotourism, and are now most used by ecotourists. For example, Korea, wherein 60% of the land is forest, attracts ecotourists. With the increasing interests in environment, the number of tourists visiting the ecosystem forest, which is highly valued for its conservation, is increasing significantly every year and is receiving considerable attention from the government. However, poor facilities in the forest ecotourism sites and improper market strategies are the reasons for the poor running of these sites. Furthermore, tourists' environmental awareness affects ecology environmental pollution or the optimization of forest ecotourism. In order to verify the relationships among tourist attractiveness, environmental consciousness, charm degrees of the attractions, and attitudes after tours, we established some scales based on existing research achievement. Then, using these scales, the researcher completed the questionnaire survey. From December 20, 2010 to February 20, 2011, after conducting surveys for 12 weeks, we finally obtained 582 valid questionnaires, from a total of 700 questionnaires, that could be used in statistical analysis. First, for the method of research and analysis, the researcher initially applied the Cronbach's (Alpha) for verifying the reliability, and subsequently applied the Exploratory factor analysis for verifying the validity. Second, in order to analyze the demographics, the researcher makes use of the Frequency analysis for the AMOS, measurement model, structural equation model computing, and also utilizes construct validity, convergent validity, discriminant validity, and nomological validity. Third, for the analysis of the ecotourists' environmental consciousness, impacts on tourist attractiveness, charm degrees of the attractions, and attitudes after the tour, the researcher uses AMOS 19, with the path analysis and equation of structure. After the research, researchers found that high awareness of natural protection lead to high tourist motivation and satisfaction and more positive attitude after the tour. Moreover, this research shows the psychological and behavioral reactions of the ecotourists to the ecotourist development. Accordingly, environmental consciousness does not affect the tourist attractiveness that has been interpreted as significant. Furthermore, people should focus on the change of natural protection consciousness and psychological reaction of ecotourists while ensuring the sustainable development of ecotourists and developing some ecotourist programs.
We identified the benthos collected from intertidal zone in Sacho, Naedong, Oran and Kusong of Haenam peninsula in October, 1990 and May, 1991 and examined the distribution pattern on the bases of the analysis of community structure and the physicochemical analysis of sediment including the grain component. The identified benthos consisted of 141 species and 4,641 individuals. The number of species and individuals of Mollusca, Arthropoda and Annelida occupy more than
As oral diseases are developed by mixed infections, not by any single element, an accurate analysis of the causative microorganisms related to dental caries and periodontal diseases is required. In this study, saliva was collected from selected adults to determine if the bacteria that are well known as the causative microorganisms of dental caries and periodontal diseases would be detected in their saliva. In addition, this study examined whether there would be any differences among adults according to age, smoking, drinking and presence or absence of diseases in the distribution of oral bacteria to determine the risk factors for oral bacteria. The study subjects were 120 adults ranging in age from 20 to 65 years. The experiment data was collected from March 15, to May 2014. The gDNA was collected from the saliva, and the distribution of bacteria for oral diseases was investigated by PCR. The findings of the study were as follows. S. mutans was detected from 72 adults, and P. intermedia was detected from 88 adults. Both bacteria were detected from 54 adults, and no oral bacteria was detected in 14 adults. An analysis of the risk factors of oral bacteria showed that smokers had a 2.8-fold higher risk of S. mutans than nonsmokers, and the former had a 3.5-fold higher risk of P. intermedia than the latter. Drinkers had a 3.3-fold higher risk of S. mutans than nondrinkers. Patients who suffered from systemic diseases had a 4.1-fold higher risk of P. intermedia than those with no diseases. Therefore, smoking, drinking and systemic diseases are factors that increase the likelihood of oral bacteria detection. More periodontal disease bacteria were detected from older adults, and more oral bacteria were found in adults who were in their 20s, as dental caries and periodontal diseases were more common in this age group. The adults in which oral bacteria were detected are more likely to have dental caries or periodontal diseases, and they should try to keep their mouth cavity clean and make regular visits to a dental clinic to prevent possible oral diseases.
Conceptualization of store image have been suggested in the past by many marketing scholars. The dominant perspective about store image is treated as the results of a multi-attribute model. Store image is expressed as a function of the salient attributes of a particular store that are evaluated. Though, there is a little confusions about what elements compose the store image, most scholars agree that merchandise, service, atmosphere, physical facilities, comfort, and location are generally accepted elements as store image. A considerable researches support that shopping can provide both hedonic and utilitarian value. Hedonic shopping value reflects the value received from fantasy and emotive aspects of shopping experience, while utilitarian shopping value reflects the acquisition of products. These two types of shopping value can affect shopping satisfaction. This study examines the relationships among stores images(store atmosphere, salespeople services, facilities, product assortment, and store location), shopping values(utilitarian shopping value and hedonic shopping value), and shopping satisfaction based on discount stores (E-Mart, Home plus, and Lotte Mart). The author hypothesized that five store image components affect shopping values, and these shopping values affect shopping satisfaction. The author focused on the roles of perceived retail crowding between these relationships. Specifically, the author hypothesized that perceived retailing crowding moderated the relationship between shopping values and shopping satisfaction. The author also hypothesized the direct effect of perceived retail crowding on shopping satisfaction. Finally, the author hypothesized that five store image components affect directly shopping satisfaction. Research model is presented in
Well-being is a reflection of current sociocultural trends that focus on the quality of life based on economic growth. Furthermore, organic food is believed to help people maintain good health and therefore leads to increased consumption of organic foods. Therefore, consumer interest in organic food is increasing, causing its market to grow, and this trend will be maintained in the future. The abuse of agricultural pesticides, gene manipulation, and bovine spongiform encephalopathy has caused consumers to worry about food safety. The well-being trend has also contributed to consumers' growing interest inorganic food and organic agricultural products. A consumer's choice offood is a complex processes affected by various factors. In particular, organic food is considered an individualistic merit good, considering the consumers' preferences related to certification policies. Therefore, various factors such as personal characteristics and sense of value could affect consumers' decisions. This research focused on an analysis of the factors influencing consumers' purchasing intention for organic food on the basis of an increase in organic food consumption. The research method was based on the theory of planned behavior (TPB). Factors such as consumer characteristics regarding food consumption, purchasing frequency, and other factors affecting purchasing intention were presented. The hypothesis was set using advanced research and stated that it is easier to forecast purchasing intentions by combining the theory of planned behavior and personal characteristics of consumer. The results show that two dimensions, attitude and perceived behavioral control, have statistically significant influence on the purchasing intention. It can be said that a positive attitude toward organic foods in particular increases the possibility of purchasing intention. In addition, consumers who consume more organic food products are more likely to have positive attitudes, and, in the past, purchasing frequency has positively influenced purchasing intention of organic foods. Consumers' negative feelings about the non-purchase of organic foods also showed a negative influence on purchasing intentions. In other words, even though consumers feel uncomfortable when not consuming organic food products, they do not try to purchase such products because of this feeling of discomfort. Furthermore, the subjective norm and the behavioral control of food-related involvement do not have a statistically significant influence on the purchasing intention or attitudes. This research verified the influence of factors related to purchasing intention. This study has several limitations: (1) even though consumers' responses can change based on the type of food, the types of food were not classified in this study; (2) future studies are necessary to analyze the attitudes of consumers on the basis of their purchasing experiences with organic foods.
The concept of Corporate Social Responsibility (CSR) was first introduced sixty years ago in the academic field. However, the phrase CSR was not explicitly stated before the 1990s in Korean business and academic researches. Recently CSR is more considered a corporate strategy than a philanthropic donation. CSR comprises contributions to local communities as well as using environmentally beneficial and humane practices. Sponsoring is one available marketing tactic used in order to communicate with the market. This study of sponsorship has concentrated on developing brand asset by accessing potential values of sporting events or star-players. However, sponsorship includes providing funds or goods to non-profit institutions as well as sports or entertainment organizations. Accordingly corporate community-specific sponsorship is defined as firms offering to provide money, goods and/or services to individuals and/or institutions within a particular community, thus establishing an interdependent relationship between the partners aspiring to gain social and economic assets. National sponsorship is typically targeted toward commonly recognized individuals and/or organizations with the intent to maximize exposure of a sponsor's brand, and is known to positively affect brand equity(community-specific sponsorship is committed to a limited local area) that a firm could benefit from by gaining a specific asset. POSCO sponsors the Jukdo Market, locate dinthe city of Pohang, tohelp revive their traditional market. Inreturn, the Jukdo Market merchant suni on display sflags with the POSCO embleminfrontof stores with in the market intending to make shopper sand merchant saware of POSCO's sponsorship. POSCO has succeeded in acquiring public support from the citizens of Pohang. However, the economic effects resulting from the cooperative relationship between POSCO and the Jukdo Market have yet to be measured by any empirical research. The purpose of this study is to assess the economic effects created by the community-specific sponsorship from the groups of merchants and shoppers, measuring its influence on the corporate image and subsequent brand loyalty, as parts of brand equity. The result of the study shows that the community-specific sponsorship of POSCO of the Jukdo Market had different influences on its corporate image and the brand loyalty of shoppers and merchants. First, the merchant group who was more frequently exposed to POSCO's flag recognized the sponsorship of POSCO more than the shopper group, and, therefore, had a better image of the company. Second, the recognition of POSCO's sponsorship had a positive influence on its corporate image, and that positive corporate image had a positive effect on brand loyalty development. However, the recognition of the sponsorship did not have a direct influence on brand loyalty. The friendly corporate image developed by the recognition of the sponsorship consequently could have had an effect on brand loyalty. Therefore, companies should not relinquish investments to corporate image development if they require more brand loyalty. Third, the influence of corporate image on brand loyalty shows stronger results in the shopper group rather than in the merchant group. Psycho-graphic factors of shoppers and merchants might give rise to the difference between the two groups.
Purpose - This study aimed to investigate the correlation between the social activity of the elderly and recognition of family cohesion of the elderly who are exposed to the current aging society. In addition, the study has delved into the method of family cohesion improvement through the differences between groups based on the mediator effect of how the results have effects on the elderly's self-control capabilities. Research design, data, and methodology - This study has targeted the elderly who are attending the elderly university among users in seven community centers located in Seoul and Gyeonggi-do area. The study has also conducted a survey by the format of a half-structured questionnaire. It is aiming to investigate the elderly's family cohesion with children and their self-control capability, and understand their satisfaction of social activity to help successful elderly life. The study has suggested the following as mentioned. First, the study analyzed that the perceptual factor of family cohesion with children would be deducted based on advanced researches. Second, the influencing relationship would be analyzed through the relational analysis between the elderly's family cohesion and social activity. Results - The family cohesion with children has a significant effect on psychological happiness and it showed the influencing relationship with improvement of the elderly's self-control capability. Therefore, creating fellowship through meaningful conversation with children would be needed. In addition, various programs and consultant service would be offered to build healthy relationship between aged parents and their children. Through this, the elderly will be able to have not only better relationships with their family, but also increased psychological health and well-being as well. Conclusions - It is needed that not only supporting policies for children who take care of aged parents but also that the elderly who need long-term care could meet their children whenever they want through increased numbers of sanatoriums operated by cities and countries. In addition, the nation would offer financial and administrative support continuously so that people receive the benefits from sanatoriums located in the locality of children's residence beyond the elderly's residence. Moreover, social infra would be established as well.
An adequate method to identify chromium separation, Cr(III) and Cr(VI), in water samples were studied by using High Performance Liquid Chromatography(HPLC) coupled with Inductively Coupled Plasma Mass Spectometer(ICP-MS) equipped with Dynamic Reaction Cell(DRC). The characteristic distribution of Cr(III) and Cr(VI) in the raw water taken at the six water intake stations in Seoul, was analyzed by the method developed by the authors. The chromium species separated by HPLC was isocratically conducted by using tetrabutylammonium phosphate monobasic(1.0 mM TBAP), ethylenediaminetetraacetic acid(0.6 mM EDTA) and 2% v/v methanol as the mobile phase. 5% v/v methanol was used as flushing solvent. A reactive ammonia(. To test model and hypotheses, data were collected from 114 consumers located mid-size city in local area. The author employs PLS methodology (SmartPLS 2.0) to test hypotheses. Data analysis results indicate that among five store images salespeople services, and store location affect utilitarian shopping value. Store atmosphere, salespeople services, and store location affect hedonic shopping value. Two shopping values affect shopping satisfaction. Hedonic shopping value affect more shopping satisfaction than utilitarian shopping value. Data analysis results is presented in . The author examines the moderating effects of perceived retail crowding between shopping values and shopping satisfaction. Results indicate that there are no moderating effects between shopping values and shopping satisfaction. Moderating effects of perceived retail crowding between utilitarian shopping value and shopping satisfaction are presented in
. Moderating effects of perceived retail crowding between hedonic shopping value and shopping satisfaction is presented in
. The author analyzed the relationship between perceived retail crowding and shopping satisfaction using WarpPLS 3.0 which can analyze the non-linear relationship. Result indicates that perceived retail crowding affects directly shopping satisfaction and there is a non-linear relationship between them. Among five store image components, store atmosphere and salespeople services affect directly shopping satisfaction. The author describes about the managerial implications, limitations, and future research issues.
A Study of the Factors Influencing Behavioral Intention for Organic Food: Using the Theory of Planned Behavior
(유기농식품에 대한 소비자의 구매의도 영향요인 분석 계획적 행동이론을 중심으로)
How community-specific sponsorship of a traditional market creates brand equity: The interdependent relationship between POSCO and the Jukdo Market
(전통시장에 대한 기업의 지역사회 특화 스폰서십이 브랜드 자산에 미치는 영향: 포스코와 포항 죽도시장의 협력사례를 중심으로)
A Study of Family Cohesion on Self-Regulation Ability of the Elderly
(노인의 가족결속력이 자기조절능력에 미치는 영향 연구)
New Analytical Method to Identify Chromium Species, Cr(III) and Cr(VI), and Characteristic Distribution of Chromium Species in the Han River
(한강수계해서의 크롬(III,VI) 종(species) 분포 및 분석방법 정립)
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