• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.25-39
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• 2018

NIST(National Institute of Standards and Technology) has recently published SP 800-90B second draft which is the document for evaluating security of entropy source, a key element of a cryptographic random number generator(RNG), and provided a tool implemented on Python code. In SP 800-90B, the security evaluation of the entropy sources is a process of estimating min-entropy by several estimators. The process of estimating min-entropy is divided into IID track and non-IID track. In IID track, the entropy sources are estimated only from MCV estimator. In non-IID Track, the entropy sources are estimated from 10 estimators including MCV estimator. The running time of the NIST's tool in non-IID track is approximately 20 minutes and the memory usage is over 5.5 GB. For evaluation agencies that have to perform repeatedly evaluations on various samples, and developers or researchers who have to perform experiments in various environments, it may be inconvenient to estimate entropy using the tool and depending on the environment, it may be impossible to execute. In this paper, we propose high-speed implementations and an efficient memory usage technique for min-entropy estimation algorithm of SP 800-90B. Our major achievements are the three improved speed and efficient memory usage reduction methods which are the method applying advantages of C++ code for improving speed of MultiMCW estimator, the method effectively reducing the memory and improving speed of MultiMMC by rebuilding the data storage structure, and the method improving the speed of LZ78Y by rebuilding the data structure. The tool applied our proposed methods is 14 times faster and saves 13 times more memory usage than NIST's tool.

• Journal of the Korean Society of Costume
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• v.49
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• pp.125-136
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• 1999

The present study was conducted to analyze(1) if there are any differences in jean's brand royalty according to the age·sex·educational background and income of consumers (2) the criteria for store choice by jean's brand royalty of consumers (3) the use of information souces by jean's brand royalty of consumers. The research method employed was normative-descriptive survey and questionnaires were main instrument to gather research materials. The survey was implemented from July 1st 1998 to the schools and two colleges and those who work at a comuter-related company and at a trade company. The data gathered was analyzed by mean standard deviation t-test ANOVA and Duncan -multiple range test. The results are summarized as follows: (1) 58.6% of the respondents were categorized as the brand loyalty group that was bigger than the non-brand loyalty group (41.4%) People in their late 2-'s were inclined to have the highest brand loyalty for jeans People in university and above had relatively higher brand royalty than to people with a high school or lower (2) Brand royalty group paid more attention on the quality on the quality of the fabric use; the trands of the products: brand name of the product: the distance of the store location : and the comfortable atmosphere of the store. Pleasant and kind services of the salesperson was considered as more important factor for store selection by the non-brand royalty group than by brand royalty group. (3) Almost all the information sources were used more often by brand royalty group than non-brand royalty group. For both groups their own experiences is most important information sources. The results shows that consumers have high brand loyalty for jeans product and also have many differences not only in the usage of information sources but also in the store selection criteria accorrding to the level of jeans brand loyalty . Therefore those industries carrying jeans should these points on their marketing strategies.

• Journal of Welding and Joining
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• v.25 no.6
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• pp.71-77
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• 2007

Until now, many researches on laser-arc hybrid welding processes have been conducted mainly for high power CW laser and high direct current arc to weld the thick steel plates for shipbuilding. Recently, however the usage of thin steel plates, which tend to be deformed easily by thermal energy, is been increasing because of demand of light structure such as car body in the automobile industry. Accordingly, heat sources having relatively low heat input such as pulsed laser, dip-transfer DC GMA and pulsed GMA seem to be applied more increasingly and the study about those heat sources is needed more intensively. Any heat source mentioned above can not stand alone without weld defects at a relatively high welding speed for increasing the welding productivity. This is main reason to apply the hybrid welding process which uses pulsed laser and low-heat-input GMA heat sources simultaneously to weld the thin steel plate. In this study, parameters of pulsed laser and dip-transfer DC GMA welding are studied firstly through preliminary experiments, and then analyzed in the viewpoint of their physical phenomena. Before conducting the hybrid welding, a pulse control technique is developed based on the parallel port communication and Visual C++ 6.0. Owing to development of this technique, interactions of laser and arc pulses can be controlled consistently. Using the pulse control technique, the hybrid welding is conducted and then its interactive welding phenomenon is analyzed.

• Journal of Nutrition and Health
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• v.30 no.2
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• pp.139-146
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• 1997

Use of the viamin-mineral supplements markedly increased with the awareness of diet and health. Data were collected from the self-administered questionnaire of 450 free living elderly, 60 to 94 years old, in Korea, to assess the relationships between socioeconomic variables, beliefs about nutrition, and the factors affecting gupplements usage. In addition, vitamin-mineral intakes through the supplements were calculated, and compared with RDA. 44.9% of the subjects took the vitamin-mineral supplements, and significantly higher percentage of women(49.3%) than men(38.1%) took supplements(p<0.05). The higher the education level, monthly pocket money, the percentage of supplements consumption was higher. People living in large cities took more supplements than those in small cities. One of the mainly cited reasons for taking supplements was to maintain health. The most favored nutrient supplements used by the subjects were in the order of vitamin B complex, vitamin E and Calcium, and vitamin-mineral intake through the supplements were much greater than RDA and ranges of their intakes were very wide. Vitamin B1 and vitamin E were observed to consume excessive amount(63 times of RDA and 40 times of RDA, respectively). The reasons for supplementation were often inappropriate and unreliable sources of information were used. Thus nutritional understanding and education of the elderly peopled are needed in regard to the use of vitamin-mineral supplements, and the relationship between adequate diet and good health.

• Journal of the Korean Dietetic Association
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• v.11 no.4
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• pp.440-448
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• 2005

This study explores some basic issues behind adults' seeking and using patterns of alternative medicine as well as health food (health food/medicine). In order to do this, 791 adult participants in Seoul and Busan were interviewed face-to-face. The results of the survey showed that 1) interpersonal influence was the most influential factor in relation to the adoption of health food/medicine(46.9% of the participants reported on the influences), 2) keeping healthy was the main motivation for the usage of health food/medicine(34.5% of the participants), 3) mass media was the important information source for health food/medicine, 4) with regard to trustworthiness of information sources, experts were believed to be the most trustworthy while information from acquaintances were thought less, and finally, 5) pharmacies and health food stores were main suppliers of health food/medicine. This study suggests some marketing strategies for health food/medicine. For example, it can be suggested that interpersonal communication among other information channels should be focused and might be increased trust by using professionals.

• Journal of Environmental Health Sciences
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• v.35 no.6
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• pp.510-516
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• 2009

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in soil samples of Ansung in Kyonggi-province to investigate concentration distribution of PBDEs and PCBs. The 10 soil samples were collected using a stainless steel hand-held corer that was cleaned before and after each sample using hexane. Total concentration of PBDE and PCBs were 2,205.3 and 348.1 pg/g dry weight (DW) in soil sample, respectively. BDE-209 showed as the most abundant congener in soil samples which was related to imported amount and usage amount of deca-BDE technical mixture in Korea. Also, BDE-99, BDE-47, BDE-100 deposition in soil sample was higher than other congeners and was related to the imported and usage amount reported for penta-BDE technical mixture in Korea. Correlation coefficient between PBDE contribution and technical mixture formulation (Bromokal 70-5DE) were significant (r=0.91, p<0.01) which suggests the influence of sources in this technical mixtures.

• Journal of the Korean Solar Energy Society
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• v.32 no.5
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• pp.75-82
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• 2012

This study aims to investigate the usage of the renewable energy systems installed in buildings and make suggestions for the effective management. In this regard, a questionnaire survey was conducted on 1)design and construction, 2) operation and management, 3) user satisfaction and improvements about the renewable energy systems in buildings. Findings from this study can be summarized as follows; a lack of the basic information about systems, non-use of energy management systems, the differences in the features by energy source, and a lack of expertise of managers. The requirements to resolved these problems include the integrated management of various electric heat sources including a renewable energy source, an operation schedule based on the prediction of production and consumption, and so on. Furthermore the necessity of multiplex energy sources management system was confirmed and the basic data needed to establish the targets of this system were obtained.

• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.51-66
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• 2024

Modern society is making numerous efforts to reduce reliance on carbon-based energy systems. A notable solution in this transition is the adoption of lithium-ion batteries (LIBs) as potent energy sources, owing to their high energy and power densities. Driven by growing environmental challenges, the application scope of LIBs has expanded from their initial prevalence in portable electronic devices to include electric vehicles (EVs) and energy storage systems (ESSs). Accordingly, LIBs must exhibit long-lasting cyclability and high energy storage capacities to facilitate prolonged device usage, thereby offering a potential alternative to conventional sources like fossil fuels. Enhancing the durability of LIBs hinges on a comprehensive understanding of the reasons behind their performance decline. Therefore, comprehending the degradation mechanism, which includes detrimental chemical and mechanical phenomena in the components of LIBs, is an essential step in resolving cycle life issues. The LIB systems presently being commercialized and developed predominantly employ graphite anode and layered oxide cathode materials. A significant portion of the degradation process in LIB systems takes place during the electrochemical reactions involving these electrodes. In this review, we explore and organize the aging mechanisms of LIBs, especially those with graphite anodes and layered oxide cathodes.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.449-454
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• 2000

Sustainable development has been the key concept, both in economic policies and in environmental management. On the basis of an systems ecology perspective, this suggests the sustainable development of Korea\`s natural environment and economic activity using the EMERGY evaluation. The total EMERGY use(7,730E20sej/yr) in Korea is 81 percent from imported sources, fuels and goods and services. The ratio of outside investment to attracting natural resources is already large, like other industrialized countries. Continued availability of purchased inputs at a favorable balance of EMERGY trade, currently about 2.85 to 1 net EMERGY, tis the basis for present economic activity and must decrease as the net EMERGY of purchased inputs including fossil fuels goes down. EMERGY yield ratio and environmental loading ratio were 1.23 and 20.30, respectively. The population level is already in excess of carrying capacity. Its carrying capacity for steady state on its renewable sources is only 2.2 million people, compared to 45.9 million in 1977. EMERGY sustainability index is therefore less than one, which is indicative of highly developed consumer oriented economies. Until now the development of a country has been achieved by the economic growth, but it can be sustained in the long run by the use of renewable resource systems. the efficiency of energy usage, and the transformation of the social-economic structure based on an ecological-recycling concept.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.58-65
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• 2014

We developed a low-cost automatic diagnosis system for water quality in cooling towers to measure the concentrations of key ingredients such as $Ca^{2+}$, $Cl^-$, $PO{_4}^{3-}$, and $Fe^{2+}$. $Ca^{2+}$, and $Cl^-$ are the main factors that cause the generation of scale, corrosion, and sludge in water pipes. $PO{_4}^{3-}$ prevents corrosion, sludge and scale by inhibiting the ions (i.e., $Ca^{2+}$, $Cl^-$) from sticking to the pipes. $Fe^{2+}$ is an indicator of pipe corrosion. The proposed system consists of a microprocessor, a specimen container and heater, a precision pump, relays and valves, LED optical sources, and photo detectors. It automatically collects water samples and carries out pretreatment for determining the concentration of each chemical, and then estimates the concentration of each ion using low-cost LED optical sources and detectors. Experimental results showed that the accuracy of the proposed system is sufficiently high for water quality diagnosis and management of cooling towers, demonstrating the possibility of the proposed system's wide usage in real environments.