• Title/Summary/Keyword: radio sources

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Neutron activation analysis: Modelling studies to improve the neutron flux of Americium-Beryllium source

  • Didi, Abdessamad;Dadouch, Ahmed;Jai, Otman;Tajmouati, Jaouad;Bekkouri, Hassane El
    • Nuclear Engineering and Technology
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    • v.49 no.4
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    • pp.787-791
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    • 2017
  • Americium-beryllium (Am-Be; n, ${\gamma}$) is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci), yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: primarily, it will help us perform neutron activation analysis. Next, it will give us the opportunity to produce radio-elements with short half-lives. Am-Be single and multisource (5 sources) experiments were performed within an irradiation facility with a paraffin moderator. The resulting models mainly increase the thermal neutron flux compared to the traditional method with water moderator.

Comparative Study of Coupling Factors for Assessment of Low-Frequency Magnetic Field Exposure

  • Shim, Jae-Hoon;Choi, Min-Soo;Jung, Kyu-Jin;Kwon, Jong-Hwa;Byun, Jin-Kyu
    • Journal of Magnetics
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    • v.21 no.4
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    • pp.516-523
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    • 2016
  • In this paper, coupling factors are calculated based on numerical analysis in order to assess various non-uniform low-frequency magnetic field exposure situations. Two types of non-uniform magnetic field sources are considered; circular coil and parallel wires with balanced currents. For each magnetic field source, source current values are determined so that reference magnetic field magnitude can be measured at the specified point on the human model. Various exposure situations are investigated by changing parameters such as the distance between source and human model, radius of circular coil, and the gap between parallel wires. For equivalent human models, prolate spheroid model and simplified human model from IEC 62311 standard are used. The calculated coupling factor values are compared with those obtained by 2D uniform disk human model, and the dependence of coupling factor on the choice of equivalent human model is analyzed.

A Study of Static Bias Correction for Temperature of Aircraft based Observations in the Korean Integrated Model (한국형모델의 항공기 관측 온도의 정적 편차 보정 연구)

  • Choi, Dayoung;Ha, Ji-Hyun;Hwang, Yoon-Jeong;Kang, Jeon-ho;Lee, Yong Hee
    • Atmosphere
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    • v.30 no.4
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    • pp.319-333
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    • 2020
  • Aircraft observations constitute one of the major sources of temperature observations which provide three-dimensional information. But it is well known that the aircraft temperature data have warm bias against sonde observation data, and therefore, the correction of aircraft temperature bias is important to improve the model performance. In this study, the algorithm of the bias correction modified from operational KMA (Korea Meteorological Administration) global model is adopted in the preprocessing of aircraft observations, and the effect of the bias correction of aircraft temperature is investigated by conducting the two experiments. The assimilation with the bias correction showed better consistency in the analysis-forecast cycle in terms of the differences between observations (radiosonde and GPSRO (Global Positioning System Radio Occultation)) and 6h forecast. This resulted in an improved forecasting skill level of the mid-level temperature and geopotential height in terms of the root-mean-square error. It was noted that the benefits of the correction of aircraft temperature bias was the upper-level temperature in the midlatitudes, and this affected various parameters (winds, geopotential height) via the model dynamics.

Vibration Fatigue Life for Slot Array RF Antenna Applied to Small Aviation Platform (적층제조 공법이 적용된 소형 항공 플랫폼용 슬롯 배열 초고주파 안테나의 진동피로수명평가에 대한 연구)

  • Kim, Ki-Seung;Kim, Hyo-Tae;Choi, Hye-Yoon;Jung, Hwa-Young
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.1
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    • pp.73-80
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    • 2022
  • Sensors are applied to small aviation platforms for various purposes. Radio frequency (RF) antennas, which are representative sensors, are available in many forms but require the application of slot array RF antennas to ensure high performance and designation. Slot RF array antennas are applied to dip brazing techniques, but the yield and production time are determined by the proficiency of production personnel in a labor-intensive form. Unmanned aerial vehicles or drones, which are representative small aviation platforms, are continuously exposed to various random vibrations because propellers and multiple power sources are used in them. In this study, the fatigue life of slot array RF antennas applied with additive manufacturing was evaluated through the cumulative damage method (Miner's rule) in a vibration environment with a small aviation platform. For the evaluation, an S N curve obtained from a fatigue strength test was used.

FLASH: The First Large Absorption Survey in HI with the Australian Square Kilometre Array Pathfinder

  • Yoon, Hyein;Sadler, Elaine;Allison, James;Moss, Vanessa;Mahony, Elizabeth;Whiting, Matthew;Su, Renzhi
    • The Bulletin of The Korean Astronomical Society
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    • v.45 no.1
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    • pp.63.2-63.2
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    • 2020
  • FLASH is a blind neutral hydrogen (HI) absorption line survey, eventually targeting about 100,000 background radio continuum sources in the entire southern sky using the full 36-antenna of the Australian Square Kilometre Array Pathfinder (ASKAP). Our primary goal is to search for associated and intervening HI absorption lines in the intermediate redshift range 0.4 < z < 1.0. The survey aims to understand the evolution of HI gas in galaxies as well as various physical mechanisms in active galactic nuclei, such as accretion and feedback processes. In this poster, we give an overview of the FLASH survey and present the preliminary results from our first 100-hrs of pilot observations. The latest survey data covers 1,000 square degrees and is ideal for validating observation and data processing in the continuous 300MHz-width low frequency ASKAP band (700-1000MHz). One of the crucial objectives of the pilot survey is to establish the analysis methodology that will be applied to upcoming large absorption surveys in the future. We discuss our data quality validation and present some detections of associated/intervening HI absorption lines. These absorption lines allow us to trace the cold gas properties of active and normal galaxies at higher redshifts where the HI emission line is too weak to be detectable.

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Performance Analysis of a UAV Energy Harvesting Relay Network in the Terahertz Band (테라헤르츠 대역 무인비행체 에너지 수확 릴레이 네트워크 성능분석)

  • Yeongi Cho;Saifur Rahman Sabuj;Han-Shin Jo
    • Journal of IKEEE
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    • v.27 no.4
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    • pp.411-417
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    • 2023
  • Unmanned aerial vehicle (UAV)-assisted relay has the advantages of ease of deployment, good communication channels, and mobility over traditional terrestrial relay, which greatly improves wireless connectivity. In this paper, we design a UAV-enabled relay network that can utilize radio frequency bands to harvest energy from sources and utilize terahertz (THz) bands to transmit information between secondary transmitters and receivers. Next, we solve the optimal position of the UAV that maximizes the relay channel capacity, and propose an algorithm to design two trajectories of UAV (a straight and an elliptical trajectory) using the derived solution. Numerical results show that the straight trajectory is better in terms of harvested energy and channel capacity.

A Study on the Purchase Behavior for Health Food of Residents in Seoul Area (서울지역 거주자의 건강식품 구매행동에 관한 연구)

  • 남궁석;김규동
    • Journal of the East Asian Society of Dietary Life
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    • v.11 no.6
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    • pp.455-465
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    • 2001
  • In a rapidly changing society, the rise in standard of living and level of education has brought about a Qualitative change in consumption, especially food consumption. Accordingly, consumers' interest in and the consumption of health foods has also grown at a rapid pace, expanding the health food market. However. because of the consumer's lack of understanding and knowledge about health foods, the reality is a difficulty in establishing sound consumption. Accordingly, this study was conducted to analyze the consumers' purchase behavior for health food. Through this study, consumers will be able to rationally plan for the use of health food items and further to provide necessary information for planning and executing effective marketing strategies producers and distributors of health foods items. The subjects of this study are the 473 Seoul residents over the age of 20 who have used health food items in the past year. The result of this study showed the use of fatigue rehabilitators, with 93.2% of the respondents saying they have used it. was the highest. with natural products honey, vitamin supplements. restorative foods, mineral supplements, young-gi fellowing in order. Recovery from fatigue. with 3.81, was the top reason the respondents started using health food items, followed by maintenance of health, supplement nutrition. and prevent disease. Family and relatives topped the list of information sources with 3.76. followed by TV and friends. On the other the Internet(2.32) and radio(2.35) were shown to be the lowest information sources. Those surveyed listed quality(4.00), safety(3.99). and nutrition(3.93) as evaluative criteria for health food items, in order of importance. The place of purchase most frequented by consumers in the survey were specialty stores(35.3%) leading the way with department stores and door-to-door sales, pharmacy following behind. On the other hand. purchases from direct mail were the lowest with 1.5% The people who bought health food Items were shown to be parent/siblings(37.2%) , self(33.6%) followed by spouse(23.7%) Purchases made by children were very low with only 4.9%. Finally, the level of satisfaction after using health food products were generally not very high. Consumers seem to be satisfied with the effectiveness(3.37) and safety (3.15) of the products. which is very minute, and they were slightly dissatisfied with the quality of the products.

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New Directions in Communicating Better Nutrition to Older Adults

  • Guldan, Georgia-Sue;Wendy Wai-Hing Hui
    • Journal of Community Nutrition
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    • v.2 no.1
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    • pp.62-70
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    • 2000
  • Nutrition education should be an important component of ongoing health promotion for older adults and their caregivers. This is because prevention through sound nutrition and food hygiene practices and regular excercise is the most cost-effective way to reduce risks for and deal with their major health problems. nutritions education services should effectively promote optimum intake and successful self-care. Unfortunately, however relative to other vulnerable groups, nutrition education for older adults has not been systematically developed or evaluated. Usually oder adults care a lot about their health, so this should be a relatively easy group to teach - but their increasing numbers, longevity and great diversity with respect to health, physical, and economic status and educational level present challenges. Some older adults may not perceive they would benefit from nutrition education, so interesting and motivating them is a challenge. The food and nutrition knowledge of older people has been acquired through a lifetime of experience. For most older adults in the Asian region, their sources are restricted by their restricted education, so that their major sources of information have been informal sources, such as television, radio, friends, family, and perhaps newspapers and magazines if they are literature. Nonetheless, dietary advice for older people should build on their existing knowledge and ingrained values. It should provide information useful in daily food selection, and focus on food, not nutrients - the same foods and groups considered appropriate for younger people, with consistent messages as given throughout the population. Attention must also be paid to discovering learning styles in older people. When we teach in schools, the young students are a captive audience resigned to their learning role. Learning by an older adult, however, reflects an effort to meet his or her perceived needs. Therefore, nutrition education should be a positive experience in a non-threatening environment, relaxed and non-competitive, and perhaps even social environment. The messages also need to be practical and achievable. A needs assessment is essential, because our ability to provide the most effective nutrition education will depend on our success in matching the needs, both perceived and unperceived. of this vulnerable group. Therefore, go to the potential older learners to assess their interest and preferences. Nutrition education activities for older adults are widespread, but few have been evaluated. Evaluation is therefore also recommended, particularly when new methods are used. Tips from other countries for giving successful nutrition education will be given, including some examples of applications as attempted in Hong Kong. Research needs will also be described. In conclusion, successful nutrition education for older adults depends on positive needs-based messages. This is may be hard to do, as few good examples are available to illustrate these principles.

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Development of Software Correlator for KJJVC (한일공동VLBI상관기를 위한 소프트웨어 상관기의 개발)

  • Yeom, J.H.;Oh, S.J.;Roh, D.G.;Kang, Y.W.;Park, S.Y.;Lee, C.H.;Chung, H.S.
    • Journal of Astronomy and Space Sciences
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    • v.26 no.4
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    • pp.567-588
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    • 2009
  • Korea-Japan Joint VLBI Correlator (KJJVC) is being developed by collaborating KASI (Korea Astronomy and Space Science Institute), Korea, and NAOJ(National Observatory of Japan), Japan. In early 2010, KJJVC will work in normal operation. In this study, we developed the software correlator which is based on VCS (VLBI Correlation Subsystem) hardware specification as the core component of KJJVC. The main specification of software correlator is 8 Gbps, 8192 output channels, and 262,144-points FFT (Fast Fourier Transform) function same as VCS. And the functional algorithm which is same as specification of VCS and arithmetic register are adopted in this software correlator. To verify the performance of developed software correlator, the correlation experiments were carried out using the spectral line and continuum sources which were observed by VERA (VLBI Exploration of Radio Astrometry), NAOJ. And the experimental results were compared to the output of Mitaka FX correlator by referring spectrum shape, phase rate, and fringe detection and so on. Through the experimental results, we confirmed that the correlation results of software correlator are the same as Mitaka FX correlator and verified the effectiveness of it. In future, we expect that the developed software correlator will be the possible software correlator of KVN (Korean VLBI Network) with KJJVC by introducing the correlation post-processing and modifying the user interface as like GUI (Graphic User Interface).

Brand Equity and Purchase Intention in Fashion Products: A Cross-Cultural Study in Asia and Europe (상표자산과 구매의도와의 관계에 관한 국제비교연구 - 아시아와 유럽의 의류시장을 중심으로 -)

  • Kim, Kyung-Hoon;Ko, Eun-Ju;Graham, Hooley;Lee, Nick;Lee, Dong-Hae;Jung, Hong-Seob;Jeon, Byung-Joo;Moon, Hak-Il
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.4
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    • pp.245-276
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    • 2008
  • Brand equity is one of the most important concepts in business practice as well as in academic research. Successful brands can allow marketers to gain competitive advantage (Lassar et al.,1995), including the opportunity for successful extensions, resilience against competitors' promotional pressures, and the ability to create barriers to competitive entry (Farquhar, 1989). Branding plays a special role in service firms because strong brands increase trust in intangible products (Berry, 2000), enabling customers to better visualize and understand them. They reduce customers' perceived monetary, social, and safety risks in buying services, which are obstacles to evaluating a service correctly before purchase. Also, a high level of brand equity increases consumer satisfaction, repurchasing intent, and degree of loyalty. Brand equity can be considered as a mixture that includes both financial assets and relationships. Actually, brand equity can be viewed as the value added to the product (Keller, 1993), or the perceived value of the product in consumers' minds. Mahajan et al. (1990) claim that customer-based brand equity can be measured by the level of consumers' perceptions. Several researchers discuss brand equity based on two dimensions: consumer perception and consumer behavior. Aaker (1991) suggests measuring brand equity through price premium, loyalty, perceived quality, and brand associations. Viewing brand equity as the consumer's behavior toward a brand, Keller (1993) proposes similar dimensions: brand awareness and brand knowledge. Thus, past studies tend to identify brand equity as a multidimensional construct consisted of brand loyalty, brand awareness, brand knowledge, customer satisfaction, perceived equity, brand associations, and other proprietary assets (Aaker, 1991, 1996; Blackston, 1995; Cobb-Walgren et al., 1995; Na, 1995). Other studies tend to regard brand equity and other brand assets, such as brand knowledge, brand awareness, brand image, brand loyalty, perceived quality, and so on, as independent but related constructs (Keller, 1993; Kirmani and Zeithaml, 1993). Walters(1978) defined information search as, "A psychological or physical action a consumer takes in order to acquire information about a product or store." But, each consumer has different methods for informationsearch. There are two methods of information search, internal and external search. Internal search is, "Search of information already saved in the memory of the individual consumer"(Engel, Blackwell, 1982) which is, "memory of a previous purchase experience or information from a previous search."(Beales, Mazis, Salop, and Staelin, 1981). External search is "A completely voluntary decision made in order to obtain new information"(Engel & Blackwell, 1982) which is, "Actions of a consumer to acquire necessary information by such methods as intentionally exposing oneself to advertisements, taking to friends or family or visiting a store."(Beales, Mazis, Salop, and Staelin, 1981). There are many sources for consumers' information search including advertisement sources such as the internet, radio, television, newspapers and magazines, information supplied by businesses such as sales people, packaging and in-store information, consumer sources such as family, friends and colleagues, and mass media sources such as consumer protection agencies, government agencies and mass media sources. Understanding consumers' purchasing behavior is a key factor of a firm to attract and retain customers and improving the firm's prospects for survival and growth, and enhancing shareholder's value. Therefore, marketers should understand consumer as individual and market segment. One theory of consumer behavior supports the belief that individuals are rational. Individuals think and move through stages when making a purchase decision. This means that rational thinkers have led to the identification of a consumer buying decision process. This decision process with its different levels of involvement and influencing factors has been widely accepted and is fundamental to the understanding purchase intention represent to what consumers think they will buy. Brand equity is not only companies but also very important asset more than product itself. This paper studies brand equity model and influencing factors including information process such as information searching and information resources in the fashion market in Asia and Europe. Information searching and information resources are influencing brand knowledge that influences consumers purchase decision. Nine research hypotheses are drawn to test the relationships among antecedents of brand equity and purchase intention and relationships among brand knowledge, brand value, brand attitude, and brand loyalty. H1. Information searching influences brand knowledge positively. H2. Information sources influence brand knowledge positively. H3. Brand knowledge influences brand attitude. H4. Brand knowledge influences brand value. H5. Brand attitude influences brand loyalty. H6. Brand attitude influences brand value. H7. Brand loyalty influences purchase intention. H8. Brand value influence purchase intention. H9. There will be the same research model in Asia and Europe. We performed structural equation model analysis in order to test hypotheses suggested in this study. The model fitting index of the research model in Asia was $X^2$=195.19(p=0.0), NFI=0.90, NNFI=0.87, CFI=0.90, GFI=0.90, RMR=0.083, AGFI=0.85, which means the model fitting of the model is good enough. In Europe, it was $X^2$=133.25(p=0.0), NFI=0.81, NNFI=0.85, CFI=0.89, GFI=0.90, RMR=0.073, AGFI=0.85, which means the model fitting of the model is good enough. From the test results, hypotheses were accepted. All of these hypotheses except one are supported. In Europe, information search is not an antecedent of brand knowledge. This means that sales of global fashion brands like jeans in Europe are not expanding as rapidly as in Asian markets such as China, Japan, and South Korea. Young consumers in European countries are not more brand and fashion conscious than their counter partners in Asia. The results have theoretical, practical meaning and contributions. In the fashion jeans industry, relatively few studies examining the viability of cross-national brand equity has been studied. This study provides insight on building global brand equity and suggests information process elements like information search and information resources are working differently in Asia and Europe for fashion jean market.

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