• 소성∙가공
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• 제23권3호
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• pp.159-163
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• 2014

In the current study, the effect of small surface defects in the starting material including roughness, indentations, or scratches, which are perpendicular to the direction of drawing, on the product quality is investigated using the finite element method. An axisymmetric defect is assumed. Such defects are defined by a cylindrical defect area and two tapered regions connecting the defect area to the non-defective area of the material. Various conditions for these initial surface defects are considered, including defect depth, defect slope and defect length. To describe the plastic deformation of the defect in detail during the simulation, local remeshing is applied. Based on the finite element results, defect disappearance maps were generated. It was found that defect disappearance is significantly dependent on the defect depth and the defect length coupled with the defect slope.

• Journal of Biosystems Engineering
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• 제3권2호
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• pp.34-34
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• 1978

동력경운깅가 일반 경사지에서 견인주행하는 경우 견인주행성능과 주행특성을 구명하기 위하여 토양의 종류 및 상태는 일정하게 하고 지면의 기하학적 조건과 견인주행속도 및 견인하중을 변수로 하여 외부동력전달계의 시점인 좌우차륜과 토양간에 발생하는 차륜구동력 및 굴름정항과 Engine에서 구동륜까지 내부전달계를 통하여 전달된 동력의 이론치와 실험치와의 부합여부를 검정하고 부가적으로 동력경운기가 경사지기계화의 동력기로써의 가능성여부와 문제점을 찾으려한다.

• 말소리와 음성과학
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• 제5권3호
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• pp.47-54
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• 2013

The purpose of this study is to analyse prosodic characteristics of accentual phrases (AP, hereafter) produced by Chinese learners of Korean in Korean text reading. The study is restricted only to the initial APs. Subjects are students who have been studying Korean at a beginner level. The results showed that Chinese learners of Korean tended to make errors in the realization of the tonal patterns of the initial 2 syllables of the initial APs. Also they showed different F0 slopes across the initial and second syllables in the initial APs. Chinese learners of Korean, therefore, need to focus on the prosodic characteristics of the initial 2 syllables of Korean APs to realize fluent Korean intonation.

• 아동학회지
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• 제36권6호
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• pp.147-164
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• 2015

The purpose of the present study was to examine the trajectories of children's negative emotionality and mother's social parenting over a 3-year period (for children at ages 1-3) and to then analyze the bidirectional effects between the two variables. The longitudinal casual relationship among children's negative emotionality, mother's social parenting and peer interaction at age 3 was also examined. The data, taken from the Panel Study on Korean Children, were analyzed using latent growth modeling. The results were as follows. First, the level of negative emotionality was seen to have increased by 2 years of age, whereas the level of mother's social parenting decreased by this point. Second, higher initial negative emotionality predicted decreases in mother's social parenting, However, higher initial mother's social parenting predicted increases in children's negative emotionality. The initial level and slope of mothers' positive parenting predicted peer interaction at age 3, while only the slope of negative emotionality predicted peer interaction. These findings suggest that temperament and parenting predict changes in each other and peer interaction.

• 한국농공학회논문집
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• 제66권1호
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• pp.15-24
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• 2024

Unlike artificially created homogeneous materials, the process of calculating the elastic modulus of natural soil involves the possibility of errors. Because the stress-strain behavior of soil is nonlinear, the secant modulus of elasticity is often used based on 1/2 of the stress at failure. Since soil has the property of changing its elastic modulus depending on the confining pressure, numerical analysis models that analyze its behavior inevitably include complex elements. The hyperbolic model, which relatively accurately simulates the behavior immediately after loading in soft ground, assumes that the stress-strain curve of the consolidated undrained triaxial test is hyperbolic and requires the slope of the tangent line at the starting point. However, the slope of the initial tangent in the stress-strain curve obtained from an actual triaxial test is difficult to have regularity according to changes in confining pressure. Additionally, due to the characteristics of a hyperbola, even small changes in related factors cause large changes in the hyperbola. Therefore, there is a lot of randomness in the process of calculating model parameters from the triaxial test results, which causes large differences in the results. Therefore, the method of calculating the initial elastic modulus by the consolidation test presented in this study is also used to verify the method by the triaxial test. It can be applied. However, since this study was applied to only one sample showing typical consolidation characteristics, it is necessary to check samples with various physical properties in the future.

• 한국지반환경공학회 논문집
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• 제16권4호
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• pp.23-32
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• 2015

This paper addresses the effects of extreme rainfall on the stability of cut slopes in Yen Bai city, Northern Viet Nam. In this area, natural slopes are excavated to create places for infrastructures and buildings. Cut slopes are usually made without proper site investigations; the design is mostly based on experience. In recent years, many slope failures have occurred along these cuts especially in rainy seasons, resulting in properties damaged and loss of lives. To explain the reason that slope failure often happens during rainy seasons, this research analyzed the influence of extreme rainfalls, initial ground conditions, and soil permeability on the changes of pore water pressure within the typical slope, thereafter determining the impact of these changes on the slope stability factor of safety. The extreme rainfalls were selected based on all of the rainfalls triggering landslide events that have occurred over the period from 1960 to 2009. The factor of safety (FS) was calculated using Bishop's simplified method. The results show that when the maximum infiltration capacity of the slope top soil is less than the rainfall intensity, slope failures may occur 14 hours after the rain starts. And when this happens, the rainfall duration is the deciding factor that affects the slope FS values. In short, cut slopes in Yen Bai may be stable in normal conditions after the excavation, but under the influence of tropical rain storms, their stability is always questionable.

• 한국재난정보학회 논문집
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• 제14권4호
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• pp.421-429
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• 2018

연구목적 : 본 연구는 기후변화에 따른 강우량 및 강우패턴을 분석하여 강우시 비탈면 거동을 파악하기 위해 강우사상을 합리적으로 적용하여 절토부 비탈면 안정성해석에 활용하고자 수치해석기법을 이용하여 비탈면 높이별, 강우사상별 침투해석을 실시하여 강우사상 및 강우지속시간에 따른 지하수위 변화를 고려한 비탈면 안정성검토를 실시하였다. 연구결과 : 강우사상(Uniform Rainfall, US Army Corps., Huff 4분위법 중 1/4법 및 4/4법)에 따른 화강풍화토 비탈면의 수치해석결과 비탈면이 높을수록 침투된 강우가 지하수위까지 빠르게 도달하지 못하여 지하수위 상승은 작아지고, 비탈면의 안전율도 작게 분석되었다. 결론 : 초기강우강도가 제일 큰 강우패턴 Case 3조건인 Huff 4분위법 중 1/4법에서 지하수위 상승량이 제일 크게 나타났으며, 안전율은 가장 작게 나타났다.

• 대한음성학회:학술대회논문집
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• 대한음성학회 1996년도 2월 학술대회지
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• pp.137-155
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• 1996

The purpose of this paper is to generate a pitch contour which is affected by tile phonetic environment and the number of syllables in each Korean isolated word using a neural network. To do this, we analyzed a set of 513 Korean isolated words, consisting of 1-4 syllables and extracted the pitch contour and the duration of each phoneme in all the words. The total number of phonemes we analyzed is about 3800. After that we approximated the pitch contour with a 1st order polynominal by a regression analysis. We could get the slope, the initial pitch and the duration of each phoneme. We used these 3 parameters as the target pattern of the neural network and let the neural network learn the rule of the variation of the pitch and duration, which was affected by the phonetic environment of each phoneme. We used 7 consecutive phoneme strings as an input pattern for a neural network to make the network learn the effect of phonetic environment around the center phoneme. In the learning phase, we used 3545 items(463 words) as target patterns which contained the phonetic environment of front and rear 3 phonemes and the neural network showed the correctness rate of 98.43%, 98.59%, 97.7% in the estimation of the duration, the slope, the initial pitch. In the recall phase, we tested the performance of tile neural network with 251 items(50 words) which weren't need as learning data and we could get the good correctness rate of 97.34%, 95.45%, 96.3% in the generation of the duration, the slope, and the initial pitch of each phoneme.

• 대한토목학회논문집
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• 제28권1C호
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• pp.41-51
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• 2008

본 논문은 말뚝 및 기초지반의 강성이 수평재하말뚝의 거동에 미치는 영향을 알아보고자 주문진 표준사와 김해점토를 기초지반으로 수평재하말뚝에 대한 실내실험을 실시하였다. 또한 실험 결과를 바탕으로 영향계수를 정량화 할 수 있는 경험식을 산정하였다. 말뚝과 지반의 강성을 고려하기 위하여 길이가 다른 3개의 알루미늄 모형말뚝을 제작하였으며 이를 사질토와 점성토 지반에 설치한 후 기초지반의 상대밀도(사질토 지반) 및 비배수전단강도(점성토 지반)를 변화시켜가며 수평재하 실내실험을 수행하였다. 실험을 통하여 산정된 p-y 곡선의 초기기울기는 사질토와 점성토 지반 모두에서 깊이와 말뚝-지반의 강성에 비례하였으나 점성토 지반의 경우 사질토 지반에 비하여 깊이에 따른 초기기울기의 증가율이 작은 경향을 나타내었다. 또한 극한 지반반력의 경우 모든 지반 조건에서 수평지반반력계수와 유사하게 깊이와 지반강성에 비례하여 증가하였으나 말뚝 강성에 대한 영향은 적게 나타났다. 이와 같은 특성을 고려하여 본 논문에서는 p-y 곡선의 초기기울기 산정 식을 실험결과와 가장 유사한 형태를 지니는 쌍곡선으로 지반 조건에 따라 제시하였으며 제안된 식을 기존의 연구 및 현장재하시험과 비교하여 제안 식의 적용성을 검증하였다.

• 한국환경복원기술학회지
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• 제8권3호
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• pp.1-12
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• 2005

A study on ecological restoration of landfill slope was conducted in Nanjido to compare immediate and long time effect and supply continuous back data for ecological restoration of landfill slope. As a result, all region constructed by SF and CODRA was effective on improving soil environment and preventing slope erosion. In case of former, by adapting flowers the initial scenery was beautifully built however there was tendency that as time passes the introduced plants were being overtaken by native plants thus it was necessary to select plants which are not being overtaken by native plants. In case of latter, by introducing leguminous plants the natural adaptation of plants were moving smoothly.