• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권6호
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• pp.1418-1432
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• 2013

This paper studies the problem of secure information exchange between two sources via multiple relays in the presence of an eavesdropper. To this end, we propose a relay beamforming scheme, i.e., relay beamforming with artificial noise (RBwA), where the relay beamforming vector and the artificial noise vector are jointly designed to maintain the received signal-to-interference-ratio (SINR) at the two sources over a predefined Quality of Service (QoS) threshold while limiting the received SINR at the eavesdropper under a predefined secure threshold. For comparison, the relay beamforming without artificial noise (RBoA) is also considered. We formulate two optimization problems for the two schemes, where our goal is to seek the optimal beamforming vector to minimize the total power consumed by relay nodes such that the secrecy of the information exchange between the two sources can be protected. Since both optimization problems are nonconvex, we solve them by semidefinite program (SDP) relaxation theory. Simulation results show that, via beamforming design, physical layer secrecy of two-way relay networks can be greatly improved and our proposed RBwA outperforms the RBoA in terms of both low power consumption and low infeasibility rate.

• 여성건강간호학회지
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• 제19권2호
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• pp.99-107
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• 2013

Purpose: This study was conducted to identify relationships among knowledge and attitudes of unmarried mothers toward emergency contraceptive pills. Methods: Data were collected through structured questionnaires from 135 unmarried mothers enrolled in 7 single mothers' facilities nationwide. Data were analyzed using the SPSS/WIN 17.0 program for descriptive statistics, t-test, ANOVA, Scheffe-test, and Pearson correlation coefficients. Results: For knowledge about emergency contraceptive pills, there were significant differences among who live with her before pregnancy, experience of past pregnancies, state of present pregnancy and preparation in using contraceptives. For attitude toward emergency contraceptive pills, there were significant differences according to age, education level and religion. There were significant positive relationships between knowledge and attitudes toward emergency contraceptive pills. Conclusion: The results of this study suggest that unmarried women should be better informed about emergency contraceptive pills, and reassured about their safety. Efforts are needed to disseminate up-to-date information to experts in sex education including nurses.

• Geomechanics and Engineering
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• 제9권4호
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• pp.513-530
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• 2015

Commonly, the base stability of sheeted excavation pits against seepage failure by heave is evaluated by using two-dimensional groundwater flow models and Terzaghi's failure criterion. The objective of the present study is to investigate the effect of three-dimensional groundwater flow on the heave for sheeted excavation pits with various dimensions. For this purpose, the steady-state groundwater flow analyses are performed by using the finite element program ABAQUS 6.12. It has been shown that, in homogeneous soils depending on the ratio of half of excavation width to embedment depth b/D, the ratio of safety factor obtained from 3D analyses to that obtained from 2D analyses $FS_{(3D)}/FS_{(2D)}$ can reach up to 1.56 and 1.34 for square and circular shaped excavations, respectively. As failure body, both an infinitesimal soil column adjacent to the wall (Baumgart & Davidenkoff's criterion) and a three-dimensional failure body with the width suggested by Terzaghi for two-dimensional cases are used. It has been shown that the ratio of $FS_{(Terzaghi)}/FS_{(Davidenkoff)}$ varies between 0.75 and 0.94 depending on the ratio of b/D. Additionally, the effects of model size, the shape of excavation pit and anisotropic permeability on the heave are studied. Finally, the problem is investigated for excavation pits in stratified soils, and important points are emphasized.

• 비파괴검사학회지
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• 제8권1호
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• pp.12-21
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• 1988

The behaviour of pressure vessel made of SS41 steel was investigated during hydrotest. AE tests were carried out for the vessels in as-manufactured, V-notched and weld-cracked state using microcomputer-based AE instrumentation. The following results were obtained: 1) In the case of source location using cylindrical program, to minimize the error of source location, the difference of max. Delta T values measured from each sensor should be kept as small as possible. 2) When crack grew, AE event rate increased continuously but AE event from the inclusions occurred intermittently, so by analyzing event rate, the source of AE could be derived. 3) From the spot welding part of supporter, many events with low energy occurred independent of Kaiser effect, which could be confirmed by analyzing energy parameter. 4) The b-value from the tensile specimen of was lower than that from normal specimen and the b-value from crack propagation was lower than that from deformation, so by analyzing peak amplitude distribution, the source mechanism could be derived from the b-value.

• 환경위생공학
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• 제14권4호
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• pp.9-20
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• 1999

This paper studies regarding the problems of transmitting disease through food and its prevention in terms of current problematic food poisoning and the transfer of bacterial disease while providing lunch for school children. As the problems of school lunch program, the number of food poisoning and of the transfer of bacterial disease is highly increasing because of the shortcomings of systematic safety management toward food and of the lack of meal supplier's awareness about sanitation.For the prevention the following suggestions are provided:1. It is necessary to shift from the system of meal supply for nutrition to that of meal supply for health. 2. A system that offers a responsibility for nutrition to that of meal supply to a person in charge of hygienist, or a cook, including the a nutritionist, is needed. 3. It is necessary to gain the help from the department of sanitation in city or country for the sanitation guidance and inspection of school meal supply, not to totally rely on the local ministry of education. 4. A manager or employees related to school/group meal supply need to get education constantly on sanitation and public information. 5. For the long term, a systematic sanitary management needs to be accomplished by introducing HACCP system.

• 한국농공학회논문집
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• 제55권3호
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• pp.75-84
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• 2013

The seepage quantity analysis of reservoir embankment is very important for assessment of embankment safety. However, the conventional analysis does not consider uncertainty of soil properties. Permeability is known that the coefficient of variation is larger than other soil properties and seepage quantity is highly dependent on the permeability of embankment. Therefore, probabilistic analysis should be carried out for seepage analysis. To designers, however, the probabilistic analysis is not an easy task. In this paper, the method that can be performed probabilistic analysis easily and efficiently through the numerical analysis based commercial program is proposed. Stochastic response surface method is used for approximate the limit state function and when estimating the coefficients, the moving least squares method is applied in order to reduce local error. The probabilistic analysis is performed by LHC-MCS through the response surface. This method was applied to two type (homogeneous, core zone) earth dams and permeability of embankment body and core are considered as random variables. As a result, seepage quantity was predicted effectively by response surface and probabilistic analysis could be successfully implemented.

• 한국대기환경학회지
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• 제34권4호
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• pp.588-609
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• 2018

The objective of this study is to provide information for improving the domestic particulate matter (PM) management. To achieve the study goal, we reviewed the past and current practice of PM management in the United States (US). Our review includes the assessment about the philosophical foundation and effectiveness of PM management, systematic program implementation to reach desirable PM conditions, and steady development of analytical tools including photochemical air quality models. We noticed that the current US PM management approach has improved annual $PM_{2.5}$ concentrations 22-48% in various parts of the US in the last 16 years. In addition, we analyzed strengths and difficulties in the past US PM management implementation. Based on the results of our analyses, we propose key elements to establish more effective domestic PM management in the future than now: steady investment in technological innovations and close-communications between local governments and the central government at various stages of PM management.

• 한국유기농업학회지
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• 제18권2호
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• pp.155-176
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• 2010

This study was conducted to research the status, history and prospects of farm scale milk processing and to develop a management strategy for small scale milk process plant in Korea. Also it aims to provide ways to apply it so as to vitalize the farm made milk products market practically. This study was also treats the practical development of dairy farm school programs through the farm scale milk processing. Farm-scale milk plant (FMP) should be some of the ideas to develop small scale and using the resources according to the local features, limited expanding in regional market, produce by consumers order amounts, management policy will be transferred organic dairy farm. A few policy suggestions to put FMP system of financial support would not from beginner, it is better to settled FMP system by government or co-operation group in practical support programs were proposed. What the state needs to do through direct involvement were to put efforts at demand expansion on FMP system products, to certificate and safety the farm made milk products marketing system settings, to build more variation chance of the milk products. What was more important, however, was support policy, to create the network of FMP market and to develop of training program contents for each FMP operation unit. The ideal FMP model for the development of Dairy Farming proposed in this research will be applied as a relevant reference in managing and realizing environmental friendly and sustainable dairy industry at the national level.

• 한국군사과학기술학회지
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• 제21권6호
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• pp.894-903
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• 2018

In the case of helicopters, the development of parts technology is rapidly changing, and the complexity is rapidly increasing. Particularly, the surge of various electric and electronic systems is recognized as a problem that is directly related to the safety of the helicopter. Due to these problems, there is a growing interest in reliability evaluation in the face of the problem of confirming and certifying the reliability of parts in the development stage. In this paper, the analysis of the failure mechanism of the wiper system was carried out, and the priority and importance of each failure mode were checked by using the results, and major stress factors were derived and the corresponding acceleration model was selected. Also, the accelerated lifetime test time was calculated according to the life test time, acceleration status and acceleration level of the steady state by using the selected acceleration model and characteristic values.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1525-1531
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• 2019

The indigenous nuclear power program of India is based mainly on a series of Pressurised Heavy Water Reactors (PHWRs). A burst correlation for Indian PHWR fuel claddings has been developed and empirical burst parameters are determined. The burst correlation is developed from data available in literature for single-rod transient burst tests performed on Indian PHWR claddings in inert environment. The heating rate and internal overpressure were in the range of 7 K/s-73 K/s and 3 bar-80 bar, respectively, during the burst tests. A burst criterion for inert environment, which assumes that deformation is controlled by steady state creep, has been developed using the empirical burst parameters. The burst criterion has been validated with experimental data reported in literature and the prediction of burst parameters is in a fairly good agreement with the experimental data. The burst criterion model reveals that increasing the heating rate increases the burst temperature. However, at higher heating rates, burst strain is decreased considerably and an early rupture of the claddings without undergoing considerable ballooning is observed. It is also found that the degree of anisotropy has significant influence on the burst temperature and burst strain. With increasing degree of anisotropy, the burst temperature for claddings increases but there is a decrease in the burst strain. The effect of anisotropy in the ${\alpha}$-phase is carried over to ${\alpha}+{\beta}$-phase and its effect on the burst strain in the ${\alpha}+{\beta}$-phase too can be observed.