• 한국도로학회논문집
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• 제18권3호
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• pp.21-32
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• 2016

PURPOSES : In this paper, the analytical solutions suggested to simulate the behavior of rheological fluids were rigorously re-derived and investigated for fixed conditions to evaluate the applicability for the solutions on a mini-cone slump test of cement paste. The selected solutions with proper boundary conditions can be used as reference solutions to evaluate the performance of numerical simulation approaches, such as the discrete element method. METHODS : The slump, height, and spread radius for the given boundary and yield stress conditions that are determined by five different analytical solutions are compared. RESULTS : The analytical solution based on fluid mechanics for pure shear flow shows similar results to that for intermediate flow at low yield stresses. The fluid mechanics-based analytical solution resulted in a very similar trend to the geometry-based analytical solution. However, it showed a higher slump at high yield stress and lower slump at low yield stress ranges than the geometry-based analytical model. The analytical solution based on the mini-cone geometry was not significantly affected by the yield criteria, such as von Mises and Tresca. CONCLUSIONS : Even though differences among the analytical solutions in terms of slump and spread radius existed, the difference can be considered insignificant when the solutions were used as reference to evaluate the appropriateness of numerical approaches, such as the discrete element method.

• 한국도로학회논문집
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• 제19권4호
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• pp.19-25
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• 2017

PURPOSES : In this paper, the flow of construction material was simulated using computational fluid dynamics in a 2D axisymmetric condition to evaluate the effect of initial or varying material properties on the final shape of a specimen. METHODS : The CFD model was verified by using a well-known analytical solution for a given test condition followed by performing a sensitivity analysis to evaluate the effect of material properties on the final shape of material. Varying dynamic viscosity and yield stress were also considered. RESULTS : The CFD model in a 2D axisymmetric condition agreed with the analytical solution for most yield stress conditions. Minor disagreements observed at high yield stress conditions indicate improper application of the pure shear assumption for the given material behavior. It was also observed that the variation of yield stress and dynamic viscosity during curing had a meaningful effect on the final shape of the specimen. CONCLUSIONS : It is concluded that CFD modeling in a 2D axisymmetric condition is good enough to evaluate fluidal characteristics of material. The model is able to consider varying yield stress and viscosity during curing. The 3D CFD-DEM coupled model may be required to consider the interaction of aggregates in fluid.

• Earthquakes and Structures
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• 제14권5호
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• pp.389-398
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• 2018

The seismic isolation system makes a structure isolated from ground motions to protect the structure from seismic events. Seismic isolation techniques have been implemented in full-scale buildings and bridges because of their simplicity, economic effectiveness, inherent stability and reliability. As for the responses of an isolated structure due to seismic events, it is well known that the most uncertain aspects are the seismic loading itself and structural properties. Due to the randomness of earthquakes and uncertainty of structures, seismic response distributions of an isolated structure are needed when evaluating the seismic fragility assessment (or probabilistic seismic safety assessment) of an isolated structure. Seismic response time histories are useful and often essential elements in its design or evaluation stage. Thus, a large number of non-linear dynamic analyses should be performed to evaluate the seismic performance of an isolated structure. However, it is a monumental task to gather the design or evaluation information of the isolated structure from too many seismic analyses, which is impractical. In this paper, a new methodology that can evaluate the seismic fragility assessment of an isolated structure is proposed by using stochastic response database, which is a device that can estimate the seismic response distributions of an isolated structure without any seismic response analyses. The seismic fragility assessment of the isolated nuclear power plant is performed using the proposed methodology. The proposed methodology is able to evaluate the seismic performance of isolated structures effectively and reduce the computational efforts tremendously.

• 한국콘텐츠학회논문지
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• 제10권6호
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• pp.156-165
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• 2010

국내에선 ESM(Enterprise Security Management)이 보안관리를 대표하고 있고, 이를 더욱 고도화해야 한다는 요구가 증가하고 있다. 본 논문에서는 기업보안관리(ESM) 제품의 질적인 면을 평가하고 품질 수준을 파악하여 개선방향을 도출함으로써 품질향상을 지원할 수 있는 보안성 평가모델과 시험 방법론에 대해서 개발하였다. 그리고 제품의 보안성 품질을 측정하고 그 결과를 적절한 기준에 따라 판정하는 방법에 대해 연구를 수행하고자 성능시험사례를 제시하여 평가방법을 제시하였다. 도출된 품질평가 모델은 침입방지 시스템의 품질을 평가하고 향상시키는데 중요한 역할을 하게 될 것으로 기대한다.

• Journal of Welding and Joining
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• 제14권2호
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• pp.36-45
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• 1996

Fatigue strength of the spot welded lap joint is considerably influenced by corrosive environments. Particularly, the chloride and the sulfide are most injurious to strength of the spot welded lap joint. Therefore, there is a need to evaluate its effect to corrosion fatigue strength for safe life design of spot welded structures. In order to evaluate their corrosion fatigue strength, corrosion fatigue tests on the spot welded lap joints of the uncoated and the coated high strength steel sheets were conducted in air and in 10% NaCl solution. Corrosion fatigue strength of the uncoated specimens were entirely lower than the coated one in NaCl solution, but those of the coated specimens in NaCl solution were lower than in air. And stress distribution in single spon welded lap joint subjected to tension-shear load was investigated by the finite element method. Using these results, we tried to evaluate corrosion fatgue strength of the various spot welded lap joints with maximum stress $\sigma_{max}$ at edge on loading side of the spot welded lap joint. We could find that corrosion fatigue strength could be quantitatively and systematically rearranged by $\sigma_{max}$.

• 대한인간공학회지
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• 제34권3호
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• pp.235-245
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• 2015

Objective: The purpose of this study is to develop visual complexity metrics based on theoretical bases. Background: With the development of IT technologies, drivers process a large amount of information caused by automotive human-machine interface (HMI), such as a cluster, a head-up display, and a center-fascia. In other words, these systems are becoming more complex and dynamic than traditional driving systems. Especially, these changes can lead to the increase of visual demands. Thus, a concept and tool is required to evaluate the complicated systems. Method: We reviewed prior studies in order to analyze the visual complexity. Based on complexity studies and human perceptual characteristics, the dimensions characterizing the visual complexity were determined and defined. Results: Based on a framework and complexity dimensions, a set of metrics for quantifying the visual complexity was developed. Conclusion: We suggest metrics in terms of perceived visual complexity that can evaluate the in-vehicle displays. Application: This study can provide the theoretical bases in order to evaluate complicated systems. In addition, it can quantitatively measure the visual complexity of In-vehicle information system and be helpful to design in terms of preventing risks, such as human error and distraction.

• 기본간호학회지
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• 제16권2호
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• pp.171-180
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• 2009

Purpose: This study was done to examine the frequency of irritable bowel syndrome (IBS), entrance examination stress, mental health, and quality of life among adolescent women. Methods: A survey conducted to collect data from 925 adolescent women in Gyeonggi Province. The measurements included the Rome III criteria (to diagnose IBS), the entrance examination stress scale (to evaluate stress), symptom check list90R (SCL-90R to evaluate mental health), and World Health Organization Quality of Life Abbreviated Version (WHOQOL-BREF to evaluate quality of life). Frequency, $X^2$-tests, t-test, and analysis of variance (ANOVA) with the SPSS 16.0 program were used to analyze the data. Results: The frequency of IBS in the women was 22.8%. One hundred thirty eight women (65.4%) had the mixed constipation and diarrhea subtype of IBS. Compared to the women without IBS, those with IBS reported significantly higher scores on entrance examination stress scale, SCL-90R, all subscales of SCL-90R, and lower scores on WOLQOL-BREF. Conclusion: Nursing interventions targeting adolescent women with IBS should be developed in order to alleviate the associated stress and mental health and to promote quality of life.

• 토지주택연구
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• 제9권4호
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• pp.33-42
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• 2018

As a radiant heating panel gets more popularity, the need to study on evaluation method of thermal output of the panel also becomes increasing. Generally, the chamber using method is applied to evaluate the thermal output through an experiment. However, the chamber using method cannot be used due to the limitations on space and cost. EN1264 addresses the test equipment to evaluate the thermal output by using simpler experimental setup, and introduces application method in detail. However, there is not enough description of control methods to meet the experiment condition, and it is difficult to meet this when practical experiment. Therefore, this paper analysed the control error factors of when the thermal output experiment is performed. When EN1264 method is applied to evaluate the thermal output of the radiant floor heating panel, the error factor which is caused by the characteristic of test equipment cannot be removed by the control methods of chamber using method. In addition, the error factor can be occurred at the element which is located out of the control system. These possible error factors are defined as the characteristic error factors.

• 한국간호교육학회지
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• 제19권4호
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• pp.508-517
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• 2013

Purpose: The purpose of this study was to evaluate the effectiveness of infant CPR (Cardiopulmonary Resuscitation) immediate remediation[LAB2]. Methods: This is a quasi-experimental study with a non-equivalent comparison group pre-post test design. Participants were 73 child care teachers in J district in Seoul. The experimental group (35) received immediate remediation with video learning [LAB3]for infant CPR education and the control group (38) received video learning only. We investigated confidence of infant CPR and tested single-rescuer infant CPR performance depending on a checklist (8 items). Data were collected before and right after to evaluate the confidence of infant CPR and before, right after and 2 weeks after the education to evaluate the skill performance and final acceptance. Results: There was a significant increase in confidence of infant CPR in the experimental group and control group. There was a statistically significant difference in the degree of skill performance between groups according to the amount time (F=10.58, p<.001). The degree of skill performance was tested two weeks after the education and immediate remediation was 5.35 times more effective compared to the video image demonstration (B=1.677, p<.001). Conclusion: The findings provide the necessity of immediate remediation education of infant CPR to increase confidence and skill performance ability.

• Journal of Communications and Networks
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• 제7권3호
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• pp.377-384
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• 2005

The purpose of this research is to develop and evaluate a traffic engineering architecture that uses local state information. This architecture is applied to an Internet protocol radio access network (RAN) that uses multi-protocol label switching (MPLS) and differentiated services to support mobile hosts. We assume mobility support is provided by a protocol such as the hierarchical mobile Internet protocol. The traffic engineering architecture is router based-meaning that routers on the edges of the network make the decisions onto which paths to place admitted traffic. We propose an algorithm that supports the architecture and uses local network state in order to function. The goal of the architecture is to provide an inexpensive and fast method to reduce network congestion while increasing the quality of service (QoS) level when compared to traditional routing and traffic engineering techniques. We use a number of different mobility scenarios and a mix of different types of traffic to evaluate our architecture and algorithm. We use the network simulator ns-2 as the core of our simulation environment. Around this core we built a system of pre-simulation, during simulation, and post-processing software that enabled us to simulate our traffic engineering architecture with only very minimal changes to the core ns-2 software. Our simulation environment supports a number of different mobility scenarios and a mix of different types of traffic to evaluate our architecture and algorithm.