• Geomechanics and Engineering
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• 제38권4호
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• pp.421-437
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• 2024

The soil nailing method entails the utilisation of nails to reinforce and stabilise a zone of soil mass. This is widely used for various applications due to its effective performance under various loading conditions. The seismic response of 6m high vertical soil-nailed cut in various site classes under dynamic excitations has been investigated in this study considering various lengths and inclinations of nails. The influence of frequency content of dynamic excitation on the response of structure has been assessed through finite element analysis using time history data of three different earthquakes. The seismic stability of the nailed cut in retaining soil in various sites under El Centro, Kobe and Trinidad earthquake ground motion is evaluated based on maximum acceleration response, maximum horizontal deformation, earth pressure distribution on the wall and maximum axial force mobilised in nails. The optimum nail inclination is identified as 15° and a minimum nail length ratio of 0.7 is essential for a stable vertical cut under dynamic excitations.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.170-177
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• 2020

A mixer with a new concept design has been adapted into water treatment plants. It reportedly cuts down the energy consumption of the mixer by the new mixer, which moves vertically and creates internal flows toward its bottom. However, no experimental observations have been made on the internal flow caused by a vertical impeller. In this study, a radiotracer experiment, radioactive particle tracking (RPT) technique, and particle image velocimetry (PIV) were carried out to visualize the flow in the mixer, and compared to each other. The results show that the flow patterns from these techniques are very similar to each other, and the performance of the mixer was good enough to mix the inner materials.

• Geomechanics and Engineering
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• 제2권2호
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• pp.71-88
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• 2010

Soil nailing technique is being widely used for stabilization of vertical cuts because of its economic, environment friendly and speedy construction. Global stability and lateral displacement are the two important stability criteria for the soil nail walls. The primary objective of the present study is to evaluate soil nail wall stability criteria under the influence of in-situ soil variability. Finite element based numerical experiments are performed in accordance with the methodology of $2^3$ factorial design of experiments. Based on the analysis of the observations from numerical experiments, two regression models are developed, and used for reliability analyses of global stability and lateral displacement of the soil nail wall. A 10 m high prototype soil nail wall is considered for better understanding and to highlight the practical implications of the present study. Based on the study, lateral displacements beyond 0.10% of vertical wall height and variability of in-situ soil parameters are found to be critical from the stability criteria considerations of the soil nail wall.

• 한국지형학회지
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• 제24권3호
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• pp.27-45
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• 2017

At the upper part of terrace deposits at Jeongdongjin area, there is a structure in which reddish brown and grayish white layers laying horizontally. Previous studies have reported the existence of these structures within the deposits and suggested the theoretical background related to the formation process. However, the analysis of physical properties and chemical composition such as particle size, classification, etc. of the materials constituting the reddish brown and grayish white layers is scarcely done. In this study, the physico - chemical properties of gray - white and reddish brown beds are investigated. The mean grain size of the particles was less than $4{\varphi}$ in both layers and the reddish brown layer was more coarse. The results shows that the sorting of the grayish white layer is better. The chemical composition of both layers shows that the average concentration of $SiO_2$, $Al_2O_3$ and $K_2O$ of the grayish white layer was higher than those of the reddish brown layer. The concentration of $Fe_2O_3$ of reddish brown lyaer was 3 times higher than those of the grayish white layer. The degree of chemical weathering (CIA) is 90 or so in both the reddish brown and grayish white layers, indicating a significant level of chemical weathering. In conclusion, reddish brown layers had been formed by the processes related to the migration of iron and the migration of water that induced aggregation after the formation of sediments (psudo-gleization). In this study area, a vertical layer of grayish white which cuts off horizontal reddish brown and grayish white color was found. The vertical layer or wedge similar to a ice-wedge or columnar structure that in a cold environment, and there is a difference in shape and size. The vertical layer appears to have occurred three or more cycles. The vertical layers begin to form at a certain height within the outcrop and descend downwards, which of course is difficult to see as directing certain times.

• 한국정밀공학회지
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• 제26권2호
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• pp.141-147
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• 2009

We introduce a noble method to find a variation of the optimal path problem. The problem is to find the optimal decomposition of an original planar region such that the number of paths in the region is minimized. The paths are required to uniformly cover each subregion and the directions of the paths in each sub-region are required to be either entirely vertical or entirely horizontal. We show how we can transform the path problem into a graph s-t cut problem. We solve the transformed s-t cut problem using the Ford-Fulkerson method and show its performance. The approach can be used in zig-zag milling and layerd manufacturing.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권4호
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• pp.226-234
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• 2004

A rapid Prototyping system that laser-cuts and laminates thick layers can fabricate 3D objects promptly with a variety of materials. Building such a system must consider the surface distortions due to both vertical-cut layers and triangular surfaces. We developed a tangential layer-cutting algorithm by rearranging tangential lines such that they reconstruct 3D surfaces more closely and also constitute smoother laser trajectories. An energy function that reflects the surface-closeness with the tangential lines was formulated and then the energy was minimized by a gradient descent method. Since this simple method tends to cause many local minima for complex 3D objects, we tried to solve this problem by adding a simulated annealing process to the proposed method. To view and manipulate 3D objects, we also implemented a 3D visual environment. Under this environment, experiments on various 3D objects showed that our algorithm effectively approximates 3D surfaces and makes laser-trajectory feasibly smooth.

• Imaging Science in Dentistry
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• 제44권2호
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• pp.171-175
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• 2014

One of the most common oral surgical procedures is the extraction of the lower third molar (LTM). Postoperative complications such as paresthesia due to inferior alveolar nerve (IAN) injury are commonly observed in cases of horizontal and vertical impaction. The present report discusses a case of a vertically impacted LTM associated with a dentigerous cyst. An intimate contact between the LTM roots and the mandibular canal was observed on a panoramic radiograph and confirmed with cone-beam computed tomographic (CBCT) cross-sectional cuts. An orthodontic miniscrew was then used to extrude the LTM prior to its surgical removal in order to avoid the risk of inferior alveolar nerve injury. CBCT imaging follow-up confirmed the success of the LTM orthodontic extrusion.

• 한국지반공학회논문집
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• 제19권6호
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• pp.161-168
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• 2003

대부분의 자연상태의 사질토는 어느 정도 경화되어 있다. 경화의 정도는 흙의 체적변형 거동이나 강도에 중요한 영향을 준다. 경화된 사질토 지반의 중요한 특징은 사질토임에도 불구하고 굉장히 높이 서 있을 수 있다는 것이다. 많은 현장 관측이나 경화모래로 된 사면의 파괴 해석들은 기존의 사면해석방법이 적절하지 않다는 것을 보여준다. 이것은 단지 파괴면이 원호가 아니라는 점뿐만 아니라 파괴면에서의 전단응력이 실험으로부터 얻어진 전단강도보다 훨씬 작기 때문일 것이다. 이러한 사실은 파괴양상이 Mohr-Coulomb 전단파괴와 다르다는 것을 말한다. 이런 파괴는 파괴역학 개념과 이론으로 설명될지도 모른다. 이 논문에서는 파괴 역학 개념을 이용해서 경화모래로 이루어진 급경사 사면의 해석을 수행하였다. FEM 해석 결과는 파괴역학의 개념을 이용한 해석방법이 경화사질토로 이루어진 지반구조물의 설계나 안정해석에 훌륭한 대안임을 보여주고 있다.

• 한국콘텐츠학회논문지
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• 제13권1호
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• pp.83-90
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• 2013

이 연구는 애니메이션 <파프리카> 작품을 통하여 연상 몽타주에서 나타나는 수직적 몽타주에 관한 해석을 시도하고 있다. 몽타주는 프도프킨, 에이젠슈테인, 자끄 오몽 등 현재까지 지속적으로 연구되어지고 있다. 하지만 기존의 연구들은 몽타주를 시각적 이미지에 보다 더 비중을 두었다. 영상은 시각과 청각으로 이루어져 있고, 이 두 관계는 서로 상호 작용을 하여 효과를 극대화시키는 요소로 작용한다고 볼 수 있다. 이에 앞서 연구한 시각 영상을 분석한 연상 몽타주에 기초하여 청각적 요소를 분석한다면, 좀 더 심층적으로 접근할 수 있을 것이다. 그러므로 이 연구에서 수직적 몽타주는 논리적 몽타주와 충돌 몽타주에서 어떻게 사용되었으며 어떠한 의미를 생성하고 있는지 분석하고자 하는 것이다. 분석 결과, 수직적 몽타주는 논리적 몽타주와 충돌 몽타주에서 전체적으로는 자연적인 일치로 시각 영상에 대한 보완을 하고 선율적 일치로 전체적인 정서를 반영하게 하는 연결 관계를 보였다. 또한 시간과 장소, 그리고 명확하지 않은 공간들에서 운율적 일치를 나타낸다면, 그 요소들이 서로 관계적으로 이어지게 하는 연속성을 나타낸다. 하지만 그 연속성을 끊어내는 역할, 즉 부분적으로 관객을 몰입하게 하는 음조적 요소가 공간과 시간을 뒤집거나 변화할 때 적절하게 사용된다면, 효과를 극대화 시키고 사건의 전환점을 나타내며 등장인물에 대한 집중도를 높이는 것으로 분석되었다.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5902-5909
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• 2011

본 논문에서는 비디오 데이터에서 확신도 추론을 이용하여 급진적인 화면변환과 점진적인 화면변환을 동시에 검출하는 새로운 방법을 제안한다. 제안된 방법에서 급진적인 화면변환은 컷을 의미하고, 점진적인 화면변환은 페이드 인, 페이드 아웃, 디졸브, 수평 와이프, 수직 와이프, 반도어(Barn Doors), 아이리스 라운드(Iris Round)를 의미한다. 먼저, 각 화면변환을 대표하는 특징을 추출한 후 확신도를 이용하여 특징들을 효과적으로 통합하면서 발생한 화면변환을 추출한다. 실험결과에서는 제안된 방법이 기존의 방법에 비해 여러 가지 종류의 화면변환을 보다 정확하게 추출함을 다양한 비디오 데이터를 이용한 실험을 통해 보여준다.