• 한국대기환경학회지
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• 제27권6호
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• pp.751-771
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• 2011

Biogenic Volatile Organic Compound (BVOC) emissions are estimated with BEIS3.12 (Biogenic Emissions Inventory System version 3.12) over the Seoul Metropolitan Area (SMA) and then used in CMAQ (Community Multiscale Air Quality) simulations for two high ozone episodes in 2004 and 2007 June. The first- and second-order sensitivity coefficients of ozone to BVOC emissions are estimated with High-order Decoupled Direct Method (HDDM) simulation in order to estimate the influence of BVOC emissions on ozone using the Zero-Out Contribution (ZOC) approach. ZOC analysis shows that relative contribution of BVOC emissions on daily maximum 1-hr ozone is as high as 30% for high ozone days above 100 ppb. However simulated isoprene concentrations were over-estimated by a factor of 2 when compared to the observations at the PAMS (Photochemical Air Monitoring Station) for the 2007 episode. When assumed that actual BVOC emissions are 50% less than estimated, the ZOC of BVOC emissions on daily maximum ozone drops by more than 10 ppb for the episode. The result indicates that uncertainty in BVOC emissions may have significant impact on high ozone prediction in the SMA.

• 한국구조물진단유지관리공학회 논문집
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• 제17권6호
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• pp.1-10
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• 2013

복합재료가 신재생 에너지 산업 관련 구조물 및 해양 구조물에서 좀 더 신뢰도 있는 주 하중 부재로 사용되기 위하여 복합재료평판의 확률론적 비선형 초기 파단 하중과 원공과 곡률이 있는 복합재료판의 확률론적 비선형 좌굴 하중이 평가되었다. 주어진 설계 추출점에서의 확정론적 유한요소해석 결과를 바탕으로 반응면기법을 이용하여 한계상태면을 확률변수로 이루어진 2차 다항식으로 근사하였다. 또한, MPFP 근처에서 좀 더 정확하게 한계상태면을 근사하기 위하여 반복적 선형보간법이 적용되었다. 파괴확률을 평가하기 위하여 근사된 한계상태면 상에서 향상된 일계이차모멘트법과 몬테카를로법이 수행되었다. 마지막으로 파단에 영향을 주는 주요한 확률변수를 파악하기 위하여 변환된 확률변수에 대한 신뢰도지수의 감도를 계산하였다.

• 한국환경교육학회지:환경교육
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• 제24권4호
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• pp.1-10
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• 2011

The purpose of this study is to investigate effects of environmental education using method of rephrasing lyrics of songs on environmental sensitivity. In order to perform this study, 60 sixth-grade students in an elementary school in Seoul are selected and divided into two groups. Half of the students belong to the experimental group which undergoes environmental education using method of rephrasing lyrics of songs. The others are in the control group which gets traditional environmental education with textbook. A questionnaire was used to survey effects of environmental education using method of rephrasing lyrics of songs. The results of this study are as follows: First, it is found that the environmental education using method of rephrasing lyrics of songs is effective on building up the environmental sensitivity. Second, the environmental education using method of rephrasing lyrics of songs is effective on 4 domains of the environmental sensitivity - positive reception, expectation, disagreeableness and anger for environment and environmental problems. Moreover, the environmental education using method of rephrasing lyrics of songs makes the students in the experimental group have pro-environmental attitudes and behavior. This study revealed that using method of rephrasing lyrics of songs could be effective on the environmental education. Therefore, we have to provide a variety of chances using this method to enhance the environmental sensitivity.

• Structural Engineering and Mechanics
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• 제20권3호
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• pp.293-312
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• 2005

In this paper, free vibration of rotating beam with random properties is studied. The cross-sectional area, elasticity modulus, moment of inertia, shear modulus and density are modeled as random fields and the rotational speed as a random variable. To study uncertainty, stochastic finite element method based on second order perturbation method is applied. To discretize random fields, the three methods of midpoint, interpolation and local average are applied and compared. The effects of rotational speed, setting angle, random property variances, discretization scheme, number of elements, correlation of random fields, correlation function form and correlation length on "Coefficient of Variation" (C.O.V.) of first mode eigenvalue are investigated completely. To determine the significant random properties on the variation of first mode eigenvalue the sensitivity analysis is performed. The results are studied for both Timoshenko and Bernoulli-Euler rotating beam. It is shown that the C.O.V. of first mode eigenvalue of Timoshenko and Bernoulli-Euler rotating beams are approximately identical. Also, compared to uncorrelated random fields, the correlated case has larger C.O.V. value. Another important result is, where correlation length is small, the convergence rate is lower and more number of elements are necessary for convergence of final response.

• 한국구조물진단유지관리공학회 논문집
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• 제12권6호
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• pp.129-139
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• 2008

콘크리트 구조물의 내구성 해석 변수들의 변동성과 불확실성으로 인해 확률론적인 접근법의 사용이 증가되어 왔다. 특히, 몬테칼로시뮬레이션 방법(Level III 방법)은 접근성의 용이함으로 인해 많은 내구신뢰성 해석에 사용되어왔지만, 결과를 얻기위해서는 수 십만번의 반복계산이 필요하다. Level II 수준의 신뢰성 해석법인 일계이차모멘트법(FOSM)은 MCS법과 비교할 수 없을 정도의 짧은 시간에 신뢰도지수나 파괴확률을 계산할 수 있어, 유효성만 검증된다면 편리성과 신속성으로 인해 폭넓은 사용이 가능할 것이다. 본 연구에서는 FOSM법과 MCS법에 의한 부식확률(내구성 파괴확률)을 서로 비교하여 FOSM법의 유효성을 검증하고 각 내구성 해석변수들의 변동성이 부식확률에 미치는 영향을 검토하였다.

• 대한기계학회논문집A
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• 제24권1호
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• pp.215-224
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• 2000

In order to reduce the variation effects of uncertainties in the engineering environments, new robust optimization method, which considers the uncertainties in design process, is proposed. Both design variables and system parameters are considered as random variables about their nominal values. To ensure the robustness of performance function, a new objective is set to minimize the variance of that function. Constraint variations are handled by introducing probability constraints. Probability constraints are solved by the advanced first order second moment (AFOSM) method based on the reliability theory. The proposed robust optimization method has an advantage that the second derivatives of the constraints are not required. The suggested method is examined by solving three examples and the results are compared with those for deterministic case and those available in literature.

• 수산경영론집
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• 제29권2호
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• pp.199-216
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• 1998

An economic appraisal of a proposed marine ranching project is analysed using capital budgeting model such as net present value(NPV) and internal rate of return( IRR) as well as sensitivity analysis and goal seeking model. Of the factors for economic appraisal, direct benefits are to be determined by estimated harvest, prices and costs incurred by catching fishes, and indirect benefits include the additional economic effect of recreational fishing. And judging the worth of these project options depends upon the choice of discount rate of which 8.5% is recommended here. On the basis of estimated production, prices and costs the project is expected to yield NPV=615 million won and IRR=8.8%, which is quite accepted for an economic feasibility, under the first scenario, and NPV= -127 million won and IRR=7.93%, which is rejected, under the second scenario. Sensitivity analysis has been performed by calculating the switching value and sensitivity indicator in respect of the main project parameters. The results suggest that the project NPV and IRR are especially sensitive to fishes(rock fish and other rock fish) prices and fixed costs. Finally goal seeking analysis is carried out in order to reach a desired level of performance like NPV=0 in respect of the amount of hatchery-reared juverniles, the prices and the discount rate.

• 복식
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• 제52권5호
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• pp.1-13
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• 2002

The purposes of this study are to examine the relation between twenties women consumer's fashion-color reception and clothing purchase behaviors, and to propose the most effective plans of color-marketing. A questionnaire survey examined 384 persons' opinions in total. First, consumers are classified into 3 groups. according to their preferring colors and the degrees of their concerning : 'type of leading fashion-color', 'type of following fashion-color', and 'type of being indifferent to fashion-color'. Second, this study analyzed the factors of consumers' clothes-purchasing motives. : all consumer groups showed their purchasing motives in the order of 'aesthetic sense'-pursuit factor. 'sensitivity'-pursuit factor, and 'actual profit and sociality'-pursuit factor. Third, the types of consumers' purchasing clothes were divided into 2 groups: type of planned buying. And type of unplanned buying. And the relations between the above 2 groups and purchasing motives were investigated, as a result. it was proved that the consumers who have the purchasing motives of 'sensitivity'-pursuit and 'actual profit and sociality'-pursuit conducted 'planned buying'. Fourth. the relations between motive of clothing purchase and the type of purchase behavior were examined by consumer group : in the consumer group of leading fashion-color, the more did they have the purchasing motives of 'sensitivity'-pursuit or 'actual profit and sociality'-pursuit, the more did they conduct' planned buying'. In the fashion-color following group, the more did they have the purchasing motives of 'sensitivity'-pursuit or 'actual profit and sociality'-pursuit, the more did they conduct 'unplanned buying'.

• 소음진동
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• 제10권4호
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• pp.584-595
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• 2000

We design a new actuator for high density optical device in order to control the radial tilting motion. The newly designed actuator makes it possible to control the tilting motion actively, while the coventional actuator compress tilting motion with passive spring. First of all, We present 3-dimensional modeling of actuator and accomplish the modal analysis and magnetic analysis of actuator. Due to these results, a new designed actuator has performance of high sensitivity and high second resonance frequency. Secondly, We present the 3-DOF dynamic modeling of the 4-wire spring type actuator. sensitivity analysis is performed to consider the assembling error, such as the difference of mass center and force center. From these results, the sensitivities of rotation due to the assembly error are revealed and design criteria of rotation is presented. And experimental results of a newly designed actuator are presented and compared with theoretical results. Finally, We propose a dynamic tilt compensation and high acceleration actuator for high density optical storage devices.

• 한국산학기술학회논문지
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• 제21권12호
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• pp.570-577
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• 2020

본 연구의 목적은 영유아교사의 놀이성, 민감성, 놀이교수효능감 간의 관계를 분석하고 놀이성, 민감성이 놀이교수 효능감에 미치는 영향에 대해 알아보고자 한다. 이를 위하여 본 연구에서는 J도에 소재하고 있는 유치원, 어린이집 18개소에 근무하고 있는 영유아교사 262명을 대상으로 설문 조사를 하였다. 본 연구에 사용된 연구도구는 놀이성 척도, 민감성 척도, 놀이 교수 효능감 척도이며 본 연구에 맞게 수정, 보완하여 사용하였다. 본 연구의 결과를 분석하기 위하여 SPSS 22.0 프로그램을 사용하였으며, 빈도와 백분율, Pearson의 적률상관관계, 중다회귀분석을 통해 자료를 분석하였다. 연구 결과 첫째, 영유아교사의 놀이성, 민감성, 놀이교수 효능감 간에는 정적인 상관관계가 있는 것으로 나타났다. 둘째 영유아교사의 놀이성, 민감성이 놀이교수 효능감에 미치는 영향을 살펴 본 결과 모두 통계적으로 유의한 영향을 미치는 것으로 나타났다. 결론적으로 영유아교사의 놀이성, 민감성, 놀이교수 효능감 간에는 모두 유의미한 상관이 있었으며, 두 변인 모두 유아-교사 상호작용에 영향을 미치는 요인이었으며, 이는 영유아교사가 민감하고 놀이성이 높으면 놀이교수 효능감도 높다라는 것을 확인하였다는 점에서 본 연구의 의의를 찾을 수 있다.