등기하 해석법을 이용한 고유치 해석은 유한요소를 이용한 결과보다 고차 모드에서 더 정확한 결과를 주는 것으로 알려져 있다. 이는 유한요소법이 차수에 상관없이 요소 간에 C0연속성을 보이는 것과 다르게 등기하 해석법은 p차 요소에 대해서 Cp-1의 연속성을 보장하기 때문이다. 본 논문에서는 이러한 장점을 이용하여 등기하 해석법을 이용하여 모드 기반의 축소 모델을 구성하고 동적 거동 해석을 수행하였다. 축소 모델 구성을 위해 Craig-Bampton(CB) 기법을 적용하였다. 수치 예제를 통해 간단한 봉 요소에 대해 등기하 해석법과 유한요소 해석법을 적용하여 요소의 차수에 따른 고유치 해석 결과를 비교 분석하였다. 등기하 해석법에 중첩 노트를 허용하여 요소 간 연속성을 조절하고, 요소 간 연속성이 줄어듦에 따라 고차 모드에서의 수치 오차가 커짐을 확인하였다. 동적 거동 해석을 위한 축소 모델에 높은 차수의 외력이 주어지는 경우 요소간 연속 성이 높은 등기하해석법을 사용하면, 해의 정확도를 높일 수 있다.

이온성 액체를 이용하여 질산 용액으로부터 Am(Ⅲ)과 Eu(Ⅲ)의 추출 거동을 조사하고 이온성 액체의 활용가능성을 살펴보았다. 이온성 액체로는 1-alkyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][Tf2N])을 사용하였고, noctyl( phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO)와 tri-n-butylphosphate (TBP)를 추출제로 사용하여, Am(Ⅲ)과 Eu(Ⅲ)의 추출 분배계수를 질산농도, CMPO, TBP와 같은 변수들의 함수로서 측정하였다. 이온성 액체를 사용함으로써 기존의 n-doodecane (n-DD)과 비교하여 추출 효율이 현저히 증가하였다. 질산 용액의 농도가 높을수록 Am(Ⅲ)과 Eu(Ⅲ)의 추출률은 감소하였으며, Eu(Ⅲ)의 추출률은 Am(Ⅲ)보다 전반적으로 작았다. 이온성 액체를 이용한 Am(Ⅲ)과 Eu(Ⅲ)의 추출 메카니즘은 n-DD와 같은 분자성 유기용매를 사용하는 경우와는 달리 양이온 교환 메카니즘에 의해 일어나는 것으로 판명되었다. 사용한 모든 이온성 액체에 대하여 Am(Ⅲ)과 Eu(Ⅲ)의 추출 분배계수는 CMPO의 농도가 높을수록 증가 하고, CMPO 농도에 대한 추출 데이터의 직선 기울기 값은 약 3.0으로 이온성 액체를 이용한 Am(Ⅲ)과 Eu(Ⅲ)의 추출반응에서 3분자의 CMPO가 복합착물을 형성하는 것으로 나타났다.

선박 축계는 프로펠러 하중의 영향으로 선미관 후부베어링의 국부하중 증가가 현저히 나타나 축계 선미관 베어링 손상의 위험이 증대된다. 이를 방지하기 위해 수행된 추진축계 정렬연구는 주로 준정적 상태(quasi-static condition)에서 축과 지지베어링간의 상대적 경 사각을 감소시키는데 중점을 두어 진행되어 왔다. 그러나 보다 상세한 평가를 위해서는 동적상태를 추가로 고려하는 것이 필요하다. 4,70 0 DWT 선박을 대상으로 NCR로 운전중 급속으로 우현 전타할 때 추진축계가 받는 영향에 대해 연구하였다. 연구결과 선미 유동장 변화 에 의해 프로펠러 편심추력이 과도 상태가 되어 프로펠러에 불평형 진동이 유발되는 것을 확인하였다. 우현 전타시의 프로펠러 편심추력은 NCR 조건대비 축을 선미관 베어링으로부터 들어 올리는 힘으로 작용하여 선미관 베어링 하중완화에 기여하고 있음을 확인하였다.

FRP is a new material that has light, high strength and high durability characteristics and is emerging as a third construction material in and out of countries. However, very few studies have been done on curved FRP construction materials that can be used for tunnels or arched bridges. In particular, many joints are required for the application of curved panels to the open cut tunnel. Experimental data on the performance of the joint is required due to insufficient design criteria. The purpose of this study is to analyze the structural performance of real size, composite materials curved panels. To achieve this goal, curved panels were constructed and bending performance was tested. A numerical analysis was also performed and compared with the results of the test. The results of the test showed that the average load was 757.6 kN and the average displacement of bottom was measured at 53.12 mm. Compression stress on the upper flange and tensile stress on the lower flange were within acceptable limits of 50% of the allowable stress.

PURPOSES: This study aims to evaluate the effects of vehicle dynamic behaviors on ride quality. METHODS: Simulation and field test were conducted to analyze the behavior of a driving vehicle. The simulation program CarSIM was applied and an INS (Inertial Navigation System) was used for field experiments. A small simulator was developed to simulate vehicle behavior such as roll, pitch, and bounce. The panels evaluated the ride quality in five stages from “very satisfied”to “very dissatisfied.”Experiments were conducted on a total of 144 cases of vehicle behavior combinations. RESULTS: In both simulation and field tests, pitch is the largest and yaw the smallest. Especially in the field test, the amount of yaw is very low, about 7% of pitch and 18% of roll. The sensitive and extensive analysis conducted related ride quality with changing the frequency and amplitude. It was found that the most sensitive frequency range is 8 Hz across all amplitudes. Moreover, the combination of the roll and bounce was most sensitive to the ride quality at the low-frequency range. CONCLUSIONS: This result show that the vertical vehicle behavior (bounce) as well as the rotational behavior (roll and pitch) are highly correlated with ride quality. Therefore, it is expected that a more reasonable roughness index can be developed through a combination of vertical and rotational vehicle behavior.

In this study, we conducted a comparative study on user’s perception and behavior on public system service (PSS) using institutionalism theory and MGA (multi-group analysis) methodology. In particular, this study focuses on how institutional isomorphism is applied to public system services and how MGA can be implemented correctly in a variance based SEM (structural equation model) such as PLS (partial least square). A data set of 496 effective responses was collected from pubic system users and an empirical research was conducted using three segmented models categorized by public proximity theory (public firms = 113, government contractors = 210, private contractors = 173). For rigorous group comparisons, each model was estimated by the same indicators and approaches. PLS-SEM was used in testing research hypotheses, followed by parametric and non-parametric PLS-MGA procedures in testing categorical moderation effects. This study applied novel procedures for testing composite measurement invariance prior to multi-group comparisons. The following main results and implications are drawn : 1) Partial measurement invariance was established. Multi-group analysis can be done by decomposed models although data can not be pooled for one integrated model. 2) Multi-group analysis using various approaches showed that proximity to public sphere moderated some hypothesized paths from quality dimensions to user satisfaction, which means that categorical moderating effects were partially supported. 3) Careful attention should be given to the selection of statistical test methods and the interpretation of the results of multi-group analysis, taking into account the different outcomes of the PLS-MGA test methods and the low statistical power of the moderating effect. It is necessary to use various methods such as comparing the difference in the path coefficient significance and the significance of the path coefficient difference between the groups. 4) Substantial differences in the perceptions and behaviors of PSS users existed according to proximity to public sphere, including the significance of path coefficients, mediation and categorical moderation effects. 5) The paper also provides detailed analysis and implication from a new institutional perspective. This study using a novel and appropriate methodology for performing group comparisons would be useful for researchers interested in comparative studies employing institutionalism theory and PLS-SEM multi-group analysis technique.

Despite the importance of behavioral ecotoxicological tests, few researches have been conducted to assess the quality of freshwater using behavior of test species, in part due to lack of standardized test method for quantifying the response. In this study, we developed a new test methods using non-biting midge larva’s burrowing behavior to assess field water quality and a new index, AUC (area under curve), to compare burrowing behavior quantitatively. Four kinds of field samples (residential, natural, agricultural and industrial areas) were tested using the method to validate our methodology and index. There were not significant differences in 96 h mortality and heavy metal concentration between samples, but AUC from the industry sample was significantly decreased.

PURPOSES: This paper presents a finite element model to accurately represent the soil-post interaction of single guardrail posts in sloping ground. In this study, the maximum lateral resistance of a guardrail post has been investigated under static and dynamic loadings, with respect given to several parameters including post shape, embedment depth, ground inclination, and embedment location of the steel post. METHODS: Because current analytical methods applied to horizontal ground, including Winkler’s elastic spring model and the p-y curve method, cannot be directly applied to sloping ground, it is necessary to seek an alternative 3-D finite element model. For this purpose, a 3D FHWA soil model for road-base soils, as constructed using LS-DYNA, has been adopted to estimate the dynamic behavior of single guardrail posts using the pendulum drop test. RESULTS: For a laterally loaded guardrail post near slopes under static and dynamic loadings, the maximum lateral resistance of a guardrail post has been found to be reduced by approximately 12% and 13% relative to the static analysis and pendulum testing, respectively, due to the effects of ground inclination. CONCLUSIONS: It is expected that the proposed soil material model can be applied to guardrail systems installed near slopes.

Stable Isotope Analysis (SIA) of carbon and nitrogen is useful tool for the understanding functional roles of target organisms in biological interactions in the food web. Recently, mixing model based on SIA is frequently used to determine which of the potential food sources predominantly assimilated by consumers, however, application of model is often limited and difficult for non-expert users of software. In the present study, we suggest easy manual of R software and package SIAR with example data regarding selective feeding of crustaceans dominated freshwater zooplankton community. We collected SIA data from the experimental mesocosms set up at the littoral area of eutrophic Chodae Reservoir, and analyzed the dominant crustacean species main food sources among small sized particulate organic matters (POM, <50 μm), large sized POM (>50 μm), and attached POM using mixing model. From the results obtained by SIAR model, Daphnia galeata and Ostracoda mainly consumed small sized POM while Simocephalus vetulus consumed both small and large sized POM simultaneously. Copepods collected from the reservoir showed no preferences on various food items, but in the mesocosm tanks, main food sources for the copepods was attached POM rather than planktonic preys including rotifers. The results have suggested that their roles as grazers in food web of eutrophicated reservoirs are different, and S. vetulus is more efficient grazer on wide range of food items such as large colony of phytoplankton and cyanobacteria during water bloom period.

OBJECTIVES : The objective of this study is to analyze the nonlinear behavior of block pavements using multi-load level falling weight deflectometer (FWD) deflections. METHODS: Recently, block pavements are employed not only in sidewalks, but also in roadways. For the application of block pavements in roadways, the structural capacities of subbase and subgrade are important factors that support the carry traffic load. Multi-load level FWD testing was conducted on block pavements to analyze their nonlinear behavior. The deflection ratio due to the increase in load was analyzed to estimate the nonlinearity of block pavements. Finite element method with nonlinear soil model was applied to simulate the actual nonlinear behavior of the block pavement under different levels of load. RESULTS: The results of the FWD testing show that the center deflections in block pavements are approximately ten times greater than that in asphalt pavements. The deflection ratios of the block pavement due to the increase in the load range from 1.2 to 1.5, indicating that the deflection increased by 20~50%. The material coefficients of the nonlinear soil model were determined by comparing the measured deflections with the predicted deflections using the finite element method. CONCLUSIONS: In this study, the nonlinear behavior of block pavements was reviewed using multi-load level FWD testing. The deflection ratio proposed in this study can estimate the nonlinearity of block pavements. The use of nonlinear soil model in subbase and subgrade increases the accuracy of predicting deflections in finite element method.

The lattice Boltzmann method (LBM) is applied to study the behavior of liquid droplet inside a PEMFC gas channel. To validate the fluid-fluid interaction model, the relationship between the pressure jump across the interface and the bubble radius is investigated for a static bubble to confirm the Laplace’s law. To evaluate the fluid-solid interaction model, static contact angle is calculated by changing the interaction parameter. Also, a constant gravitational force is applied to study the temporal evolution of liquid droplet placed on the bottom wall in a three dimensional periodic channel.

목적 : 본 연구에서는 치매환자에게 전래동화 플래시애니메이션을 활용한 작업중심의 회상치료를 적용하여 인지기능과 상호작용 및 문제행동에 미치는 영향을 알아보고자 하였다. 연구방법 : 본 연구는 C시의 노인전문병원에서 총 24명의 치매환자를 실험군(12명)과 대조군(12명)으로 나누어 주 3회, 매 회기 40분씩 총 6주간 18회기의 회상치료 프로그램을 적용하였다. 중재효과를 검증하기 위해 사용된 평가도구로는 인지기능은 간이정신상태검사-한국판(Mini Mental State Exam-Korean; MMSE-K) 과 노인용 작업인지 평가도구(Loewnstein Occupational Therapy Cognitive Assessment for Geriatric population; LOTCA-G)를 이용하였고, 사회적 상호작용은 사회행동척도(Social Behavior Scale; SBS), 문제행동은 신경정신행동검사-간편형(Neuropsychiatric Inventory-Questionnaire; NPI-Q)으로 중재전 후에 평가하였다. 결과분석은 기술통계와 비모수통계를 이용하여 분석하였다. 결과 : 실험군과 대조군의 사전-사후 점수들을 비교한 결과 MMSE-K의 총점에서 두 집단 간 유의미한 차이가 있었고, LOTCA-G에서는 총점과 하위항목 중 실행력과 기억력 항목에서 유의미한 차이가 나타났음을 확인할 수 있었다. SBS의 경우 총점과 언어적, 비언어적, 대화내용의 세 가지 하위항목 모두 유의미한 차이가 있는 것으로 나타났으며, NPI-Q점수를 비교한 결과 심각도와 고통정도의 총점을 포함하여 세부항목 중 초조/공격 성의 심각도와 고통정도, 우울의 고통정도 항목에서 유의한 차이가 있는 것으로 나타났다(p<0.05). 결론 : 본 연구의 결과를 통하여 치매환자에게 전래동화 플래시애니메이션을 활용한 작업중심의 회상치료 프로그 램을 적용하였을 때, 인지기능유지 및 사회적 상호작용의 향상과 문제행동 완화에 효과가 있음을 확인할 수 있었다.

원자력 발전소 내·외부 계통의 표면에 침적된 방사성핵종은 원자로 구조재 및 핵분열생성물의 부식생성물 활성화에 의해 생성된다. 특히, 1차계통 내부에서 물과 부식된 표면 사이의 지속적인 마찰은 냉각재와 부식생성물을 혼합하게 만든다. 그 리고 이것들은 계통을 따라 순환한다. 본 논문에서는 설계단계에서 사용되는 1차 계통의 부식생성물과 방사성 핵종의 양을 예측하는 CRUDTRAN, DISER, MIGA-RT 및 CPAIR 코드를 분석하였다. 또한, CRUDTRAN을 이용하여 국내 경수로 1차계통 내 부식생성물 거동을 예측하였다. 본 연구목적은 웨스팅하우스형 원전의 실제 데이터로 계산된 값을 측정값과 비교하여 부 식생성물 평가 모델의 신뢰도를 향상시키는데 있다.

심해유전개발 중 원유의 흐름보증과 관련하여 하이드레이츠, 아스팔텐, 무기물 침전 등이 주 된 관심분야가 될 수 있으며, 특히 왁스에 대해서도 그 특성을 이해하는 것이 중요하다. 원유흐름 중단 으로 인한 왁스가 젤을 형성하였을 경우에는, 원유의 흐름을 재시작하기 위해서는 높은 압력의 펌프를 가동해야 하는 어려움이 있다. 본 연구에서는 베인 레오미터를 사용하여 왁스 젤의 항복응력 측정을 통 한 왁스 젤의 강도를 측정하고 예측하였다. 또한, 왁스 젤의 강도측정을 통해서 정성적, 정량적인 예측 을 시도하였다.

So far, square concrete filled tubular(CFT) columns have been used in a limited width thickness ratio. The reason is that local buckling occurs in steel tube easily. Once the local buckling occurs, the confinement effect of steel tube on concrete disappears. In this study, we developed welded built-up square steel tube with reinforcement which are placed at the center of the tube width acts as an anchor. 3 specimens of slender welded built-up square CFT columns and 3 specimens of slender welded built-up square steel tube columns were manufactured with parameters of width(B) of steel tube, width thickness ratio(B/t). we conducted a experimental test on the 6 specimens under eccentric load, and evaluated the structural resistance and behavior of 6 specimens.