• 한국지반신소재학회논문집
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• 제8권1호
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• pp.33-40
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• 2009

본 논문에서는 도로를 보강하는 토목섬유 중 지오셀을 이용하였을 때의 보강효과를 알아보기 위해서 실내시험과 현장시험을 실시하였다. 실내 시험은 실대형 직접전단시험기와 모형토조 직접전단시험기를 이용하여 수직응력에 따른 전단응력 곡선을 산정하고 이를 통해 지오셀이 점착력과 내부마찰각을 증가하는 효과를 볼 수 있었다. 실내시험의 결과값을 Terzaghi 공식과 Meyerhof의 공식을 이용하여 극한지지력값을 계산하고 현장시험에서 확인한 극한 지지력값과 비교하여 지오셀의 보강효과를 확인하였다. 분석결과, 직접전단시험을 통해 지오셀의 보강효과가 내부마찰각의 증가에 영향을 미치는 것을 확인하였다. 또한 셀의 개수가 커질수록 내부마찰각이 커짐을 확인하여 보강면적이 넓을수록 보강효과가 증가하는 것으로 나타났다. 지지력에 미치는 영향요소중 내부마찰각을 증가시키는 지오셀을 도로저부에 시공할 경우 내부마찰각의 증가로 지지력 또한 증가하는 것을 확인하였으며, 평판재하시험의 결과값을 통해 지오셀보강이 극한지지력값의 증가효과에 2배정도의 보강효과를 확인하였다. 수치해석을 통해 변형의 분포와 침하량을 확인한 결과, 침하량은 지오셀에 의해 줄어드는 결과를 보여 침하에 대한 보강효과를 확인하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제17권12호
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• pp.5127-5132
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• 2016

Objective: The aim of this study was to identify associations of internal motivation, perceived health competency, and health literacy with primary and secondary cancer prevention. Methods: A telephone survey was conducted with a sample of 2,700, 30-69 year olds, proportionally extracted from Gangwon Province, South Korea. The dependent variables were actions in primary and secondary prevention and the explanatory variables were 13 questions in three areas: internal motivation (4 items), perceived health competency (4 items), and health literacy (5 items). Result: Multiple linear regression analysis showed that internal motivation, perceived health competency, and health literacy positively impacted primary prevention after controlling for gender and age. As internal motivation, perceived health competency, and perceived literacy increased by 1 point, primary prevention scores increased by 0.11, 0.11, and 0.07 points, respectively. In addition, logistic regression results for secondary prevention showed that health literacy had a positive impact on secondary behavior. As health literacy increased by 1 point, the odds ratio of the practice of secondary prevention was 1.4 times higher. Conclusion: This study suggests that primary and secondary prevention of cancer are significantly related to intrinsic motivation factors, perceived health competency, and actual health literacy. Health literacy concepts that cover the capacity of health management in comprehensive areas need to be applied to education and promotion for improvement of primary and secondary prevention of cancer.

• 한국지반공학회지:지반
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• 제13권6호
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• pp.37-44
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• 1997

본 연구는 토질 역학적인 측면에서 원유로 오염된 사질토의 압축강도 특성, 전단강도, 투수계수, 지지력 특성을 통하여 원유로 오염된 모래의 물리적 거동을 파악하였다. 실험 결과에 의하면 원유로 오염된 모래 지반의 내부마찰각이 오염되지 않은 지반의 내부마찰각보다 간극속에 있는 원유로 인하여 감소하고 있으며,오염도에 따라서 강도정수들 또한 현저한 영향을 보이고 있다. 모래지반의 지지력은 원유오염 도에 따라 크게 영향을 받는다.

• 조명전기설비학회논문지
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• 제27권4호
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• pp.31-40
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• 2013

This paper proposes a performance improvement of synchronous generator using exciter control with field coils parameter estimation technique. In general, the generator excitation system controller uses the PID controller. When the Field winding impedance changed, the PID gains must be changed. General method is difficult to apply varying capacity of the synchronous generator. The proposed control method determine automatically measure the internal impedance of the synchronous generator's exciter and configure the controller. This method can be applied regardless of the generator capacity. So it is possible to apply a variety of synchronous generator systems. The validity of the proposed algorithm is verified by simulations and experiments.

• 대한기계학회논문집
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• 제7권3호
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• pp.335-343
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• 1983

Modified-Shrink-Fit(MSF) method of compound cylinder is studied to increase elastic load carrying capacity (ELCC) of pressure vessel. The autofrettage and the shrink-fit processes are used to study the MSF process. Theoretical analyses based on the Tresca yield criterion, Hencky's total strain theory and elastic linearly strain-hardening material are carried out to derive closed form solutions. Experimental results are compared with theoretical results with various diameter ratios between outer (SM45C) and inner (SM20C) bloc cylinder. For various diameter ratios, increments of ELCC have errors in strains vs. internal loading pressures between experimental and theoretical results. But experimental results show good agreements with theoretical results in reyield pressurizing state. The increments of ELCC of compound cylinder manufactured by the MSF process is proved by measuring the residual stresses.

• Structural Engineering and Mechanics
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• 제57권4호
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• pp.763-783
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• 2016

A methodology based on Teaching Learning-Based Optimization (TLBO) algorithm is proposed for optimum design of reinforced concrete retaining walls. The objective function is to minimize total material cost including concrete and steel per unit length of the retaining walls. The requirements of the American Concrete Institute (ACI 318-05-Building code requirements for structural concrete) are considered for reinforced concrete (RC) design. During the optimization process, totally twenty-nine design constraints composed from stability, flexural moment capacity, shear strength capacity and RC design requirements such as minimum and maximum reinforcement ratio, development length of reinforcement are checked. Comparing to other nature-inspired algorithm, TLBO is a simple algorithm without parameters entered by users and self-adjusting ranges without intervention of users. In numerical examples, a retaining wall taken from the documented researches is optimized and the several effects (backfill slope angle, internal friction angle of retaining soil and surcharge load) on the optimum results are also investigated in the study. As a conclusion, TLBO based methods are feasible.

• 경영과학
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• 제34권2호
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• pp.35-56
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• 2017

Technology innovations have been accelerating changes across industries and intensifying competition. Enterprises are therefore required to continuously secure their internal and external competitiveness. Based on the principle that core competencies of a firm are essential to its competitiveness, many research studies have been conducted to figure out the effect of core competencies to business performance. However, individual research works considered a part of core competencies or limited to a specific industry, which means that their findings may differ when additional core competencies are included in their analysis. After re-establishing the definition of each core competency from literature review, this study comprehensively investigated the effect relationship among core competencies and business performance. Structural equation modeling and multiple regression analysis with 421 survey respondents from various industries were conducted for our empirical study.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.94-100
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• 2004

In order to improve the frontal crash performance of an Aluminum Space Frame Vehicle, this presents a systematic optimal design process to maximize the crush energy absorption capacity of side-members while satisfying the maximum displacement constraint. In this study, five design types are studied for selecting a good collapse initiator. Then, for the selected collapse initiator type, 7 design variables are defined to represent cross section shape, thickness and bead interval. The systematic optimization processor, R-INOPL uses DOE, RSM and numerical optimization techniques. R-INOPL uses only 14 analyses to solve the 7 design variable optimization problem the final design can improve 103.9% of the internal energy and reduce 13.9% of the maximum displacement.

• 한국공간구조학회논문집
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• 제15권1호
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• pp.47-55
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• 2015

This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers' models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.

• Geomechanics and Engineering
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• 제1권2호
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• pp.113-120
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• 2009

The results of FLAC3D-based numerical evaluation of the bearing capacity shape factor $s_{\gamma}$ are presented for square and rectangular footings on granular soils. The results confirm a peculiar effect found earlier by Zhu and Michalowski (2005), where for large values of internal friction angle, $s_{\gamma}$ exhibits a peak at some aspect ratio of the footing, and then decreases towards unity at large aspect ratios. The Zhu and Michalowski's results were derived using the finite element program ABAQUS, and the results presented in this note corroborate their earlier findings.