• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.73-93
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• 2012

With an active structural involvement in spiral case structure (SCS) that is always the design and research focus of hydroelectric power plant (HPP), the compressible membrane sandwiched between steel spiral case and surrounding reinforced concrete was often assumed to be linear elastic material in conventional design analysis of SCS. Unfortunately considerable previous studies have proved that the foam material serving as membrane exhibits essentially nonlinear mechanical behavior. In order to clarify the effect of membrane (foam) material's nonlinear stress-strain behavior on SCS, this work performed a case study on SCS with a compressible membrane using the ABAQUS code after a sound calibration of the employed constitutive model describing foam material. In view of the successful capture of fitted stress-strain curve of test by the FEM program, we recommend an application and dissemination of the simulation technique employed in this work for membrane material description to structural designers of SCS. Even more important, the case study argues that taking into account the nonlinear stress-strain response of membrane material in loading process is definitely essential. However, we hold it unnecessary to consider the membrane material's hysteresis and additionally, employment of nonlinear elastic model for membrane material description is adequate to the structural design of SCS. Understanding and accepting these concepts will help to analyze and predict the structural performance of SCS more accurately in design effort.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.256-263
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• 1998

Among process synthesis problems, the heat exchanger network (HEN) has been subjected to the most concentrated effort because this kind of problems was well defined for solving it and 20-30% energy savings could be realized in the present chemical processes. In this paper, we use an evolutionary approach for HEN synthesis because this approach can overcome the local optimum and combine some heuristic rules. The basic evolutionary approach is composed of three parts, that is, initialization step, growth step and mutation step, as in the simulated annealing and genetic algorithm. This algorithm uses the ecological rule that a better cell will live and worse cell should decompose after repeated generations. With this basic concept, a new procedure is developed and a more efficient method is proposed to generate initial solutions. Its effectiveness is shown using test examples.

• International Journal of Advanced Culture Technology
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• v.8 no.2
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• pp.184-191
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• 2020

This study is conducted to find out the nurses' character for care and the workplace bullying for the early stage nurses working in the clinical field and their relation in order to understand the factors which would affect the consequence of the workplace bullying. Data collected from 131 early stage nurses working at one general hospital for 7 months was used for this study. The data was analyzed with descriptive statistics, Independent t-test, one-way ANOVA, Pearson's correlation coefficient, Hierarchical multiple regression by using SPSS/WIN 21.0. It was found that high the nurses' character for care was related to the lower workplace bullying (type and consequence) (r=-.31, p<.001; r=-.26, p=.003) and that the worse the score in the type of bullying wasthe higher consequence (r=.54, p<.001). The multiple regression analysis showed that the factors affecting the consequence of the workplace bullying were the type of bullying (β=.48), dissatisfaction with nursing (β=.22), and moderate satisfaction with nursing (β=.19) and that the explanation of the model by variables was 32.5%. Based on the results of the study, it is suggested that the effort of lowering the occurrence of the type of bullying and the strategy of enhancing the satisfaction with nursing such as improvement in the quality of nursing education be made in order to improve the consequence of workplace bullying at the workplace for the early stage nurses.

• Hwankyungkyoyuk
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• v.20 no.1
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• pp.118-130
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• 2007

This article investigated the effects of students' knowledge, beliefs, and attitudes about environment on environmental issue-based environmental problem solving in secondary school students. This article also investigated whether these factors are related to the environmental problem solving. Therefore, we first developed the test instruments to measure secondary school students' environmental knowledge, environmental beliefs, and environmental attitudes. Then, we developed the environmental issue-based teaching materials for secondary school students. The subjects participated in a environmental issue-based approach that consist of 3 lesson over an three weeks period. The results of this study presents that environmental knowledge and environmental beliefs are effective for the environmental problem solving in middle school environment class. First, secondary school students knew well ecological knowledge about environmental problem, and was entertaining most ecological beliefs. Second, secondary school students were having attitude which is most pro-environmental behaviors. Third, secondary school students are referring necessity of development partially about environment point at issue of country level. But, they were retaining situation of preservation about environment point at issue of area level. It's not easy to generalize these results because of many different variables, but the results suggests that teachers should make an effort to improve student's environmental problem solving ability applying environmental issue-based learning. And it's necessary to develop many kinds of environmental issues and teacher's instruction method to enrich problem solving ability in the process of environmental issue-based learning.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.120-125
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• 2011

As an effort to secure economically viable heat recovery units, innovative fin shapes for industrial boilers are studied for better performance. In the present study a numerical modeling for the analysis of heat exchanger performance is conducted using a commercial software, ANSYS CFX and the results are compared with the experimental data. Out of several candidate fin shapes curved wavy fin is selected for the present study. Both numerical and experimental data are directly compared for heat transfer rate and pressure drop with the assumed constant surface temperature of $60^{\circ}C$. Exhaust gas is obtained from a test apparatus which supplies variable flow rates. The numerical results show reasonable agreements with the experimental data within 10% in terms of both total heat transfer and pressure loss.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.330-335
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• 2009

kDomestic studies on meteorologicaldata have been carried out, however they were mostly not constant but limited to fragment compilation. The studies on solar energy, among others, have been relatively active but the measurement of solar irradiance is also limited to some extent. This study, in an effort to identify the difference in data between solar radiance and cloud cover, was intended to compare and analyze the typical meteorological data developed by Korean Solar Energy Society with the solar irradiance calculated using the typical meteorological data and cloud cover data provided by current simulation program. Monthly average solar irradiance from the meteorological data (ISO TRY) of Korea's typical meteorological data which was actuallymeasured appeared to be far below the monthly solar irradiance from the American Department of Energy. The solar irradiance calculated based on cloud cover indicates very limited difference between the two data, so the solar irradiance measured by Korean typical metrologicaldata (ISO TRY) indicated the similar value, which demonstrates the solar irradiance data from Korean Meteorological Administration is more accurate than those US National Weather Center.

• Journal of Gastric Cancer
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• v.15 no.1
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• pp.10-18
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• 2015

The purpose of this study was to determine if international guidelines differ in their recommendations concerning additive therapy for advanced, but potentially curable, gastric cancer. A systematic search of the English and German literature was conducted in the databases Medline, Cochrane Database, Embase, and PubMed. The search terms used were 'guidelines gastric cancer,' 'guidelines stomach cancer,' and 'Leitlinien Magenkarzinom.' Six different guidelines published after January 1, 2010, in which the tumors were classified according to the seventh edition of the TNM system (2010), were identified. Although the examined guidelines were based on the same study results, their recommendations concerning accompanying therapy for gastric cancer differ considerably. While perioperative chemotherapy is recommended in Germany, Great Britain, and large parts of Europe, postoperative adjuvant radiochemotherapy or perioperative chemotherapy is recommended in the USA and Canada. In Japan, postoperative adjuvant chemotherapy is recommended. The results of identical studies were interpreted differently in different countries. Since considerable effort is required for each country to separately test relevant studies for their validity and suitability, an international cooperation could simplify the creation of a common basis for guidelines and contribute to improved comparability of international guidelines.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.319-329
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• 2007

This paper presents a price-based quality-of-service (QoS) control framework for two-class network services, in which circuit-switched and packet-switched services are defined as "premium service class" and "best-effort service class," respectively. Given the service model, a customer may decide to use the other class as a perfect or an imperfect substitute when he or she perceives the higher utility of the class. Given the framework, fixed-point problems are solved numerically to investigate how static pricing can be used to control the demand and the QoS of each class. The rationale behind this is as follows: For a network service provider to determine the optimal prices that maximize its total revenue, the interactions between the QoS-dependent demand and the demand-dependent QoS should be thoroughly analyzed. To test the robustness of the proposed model, simulations were performed with gradually increasing customer demands or network workloads. The simulation results show that even with substantial demands or workloads, self-adjustment mechanism of the model works and it is feasible to obtain fixed points in equilibrium. This paper also presents a numerical example of guaranteeing the QoS statistically in the short term-that is, through the implementation of pricing strategies.

• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.41-45
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• 2007

Short circuit and ground fault account for the primary causes of electrical fires. In this research, real-scale experiments were conducted to assess the possibility of electrical fires due to these causes. The experiment conditions were identical with an actual fire accident, in which the power cable was supported by an iron fence. The purposes of this research are to investigate the short circuit caused by wire cutting, the conductivity of the iron fence depending on its coating conditions, and the ground fault of one wire or two wires in an effort to reconstruct the fire accident. The test results show that, owing to the instant operation of circuit breaker in the moment of short circuit or ground fault, the generated ignition energy is far less than necessary to start an ignition. Therefore it is concluded that electrical fire is highly unlikely if the electric system is protected by a circuit breaker with normal functions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1157-1163
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• 2014

Needs for a new technologies of infrastructure systems arose, following the development of next generation EMU(Electric Multiple Unit) train with maximum speed over 400km/h. For high-speed operation tests of the new EMU, a high-speed railway infrastructure test-bed was constructed in a 28km long section of the Honam High-speed Railway. Diverse sensors and monitoring system was installed for continuous monitoring of the railway. Due to such effort, further demands and needs of the integrated monitoring system was derived in a more comprehensive and long-term perspective.