• 한국지반환경공학회 논문집
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• 제17권8호
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• pp.29-37
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• 2016

해상처분장에서 내부 오염물질의 외부 유출을 방지하기 위하여 연직차수벽체가 설치된다. 연직차수벽체가 오염물질의 이동을 효과적으로 차단하기 위해서는 연직차수벽체가 해저지반의 적정 근입깊이까지 설치되어야 한다. 본 연구에서는 연직차수벽체 근입심도에 따른 해저지반을 통한 침투 및 오염물질 이동특성을 분석하기 위하여 2차원 유한요소해석 프로그램인 SEEP/W를 이용한 침투해석과 3차원 유한차분해석 프로그램인 Visual Modflow를 이용한 오염물질 이동해석을 수행하였다. 수치해석결과, 연직차수벽체는 저투수성 지반으로 일정 깊이 이상 근입되면 오염물질 유출방지 효과를 갖는 것으로 나타났다. 따라서 경제적인 연직차수벽체 설계를 위해서는 오염물질 이동을 차단할 수 있는 효과적인 최소 근입심도를 산정하여 적용하는 것이 효과적일 것으로 판단된다.

• 대한임베디드공학회논문지
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• 제12권2호
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• pp.105-112
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• 2017

To control the depth of an underwater glider, a control method by using Lyapunov's direct method is proposed. The underwater glider has a torpedo-shape hull, a movable mass in the hull, and an inflatable buoyancy bag in the hull, but doesn't have large wings that increase the lift force for the conventional underwater glider. The control laws to adjust the position of the movable mass and the mass of the inflatable buoyancy bag are derived. For a selected speed and an angle of attack, we simulated the operation of the underwater glider using Matlab/Simulink. The efficiency of the proposed controller is shown in the fact that the control effort is active during only a short period of time when the zigzag trajectory is changed from downward to upward or vice versa.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.517-520
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• 2005

The embedded suction anchor(ESA) is and anchor that is driven by a suction pile. The cross-sectional shape of the ESA anchor is circle. Its diameter is the same as that of the suction pile that is used to drive it into the seafloor. For the installation, the anchor is attached to the tip of the suction pile and then driven as a unit with the pile by and applied suction pressure. Once the ESA anchor reaches the desired depth, the pile is retrieved by applying a positive pressure. Finally, only the ESA anchor remains in the soil layer. This paper presents the results of centrifuge model tests to investigate ESA pullout capacity. The main parameters that have effects on the pullout capacity of ESA may include g-level, embedded depth, direction of loading, and loading point. The results of tests show that the pullout loading capacities increase as the loading point shift toward the tip of the anchors for a given loading direction. They also indicate that the loading point associated with the maximum pullout loading capacity is located at approximately 67 percent of the anchor length from the top for the horizontal load.

• 한국지진공학회논문집
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• 제24권5호
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• pp.211-217
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• 2020

Earthquake preparedness has become more important with recent increase in the number of earthquakes in Korea, but many existing structures are not prepared for earthquakes. There are various types of liquefaction prevention method that can be applied, such as compaction, replacement, dewatering, and inhibition of shear strain. However, most of the liquefaction prevention methods are applied before construction, and it is important to find optimal methods that can be applied to existing structures and that have few effects on the environment, such as noise, vibration, and changes in underground water level. The purpose of this study is to estimate the correlation between the displacement of a structure and variations of pore water pressure on the ground in accordance with the depth of the sheet file when liquidation occurs. To achieve this, a shaking table test was performed for Joo-Mun-Jin standard sand and an earth pressure, accelerometer, pore water pressure transducer, and LVDT were installed in both the non-liquefiable layer and the liquefiable layer to measure the subsidence and excess pore water pressure in accordance with the time of each embedded depth. Then the results were analyzed. A comparison of the pore water pressure in accordance with Hsp/Hsl was shown to prevent lateral water flow at 1, 0.85 and confirmed that the pore water pressure increased. In addition, the relationship between Hsp/Hsl and subsidence was expressed as a trend line to calculate the expected settlement rate formula for the embedded depth ratio.

• 한국지능시스템학회논문지
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• 제21권5호
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• pp.581-587
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• 2011

이 논문은 임베디드 소프트웨어 설계 과목을 위한 실습 키트 하드웨어와 이 키트를 사용한 임베디드 소프트웨어 설계 교육 과정에 대해서 소개한다. 임베디드 소프트웨어 설계 과목은 그 특성상 실습과 한 학기에 걸친 프로젝트 위주로 진행되는데 이를 위해서는 소프트웨어를 실행시킬 실습 키트가 꼭 필요하다. 학생들이 하드웨어를 완벽하게 이해하고 소프트웨어 설계 및 개발을 진행할 수 있도록 학생들의 수준에 맞는 맞춤형 실습 키트 하드웨어를 설계하고 제작하였다. 학생들은 제작된 실습 키트를 사용하여 디바이스구동 소프트웨어에서부터 사용자 인터페이스까지 임베디드 소프트웨어 전 계층에 걸친 프로그램 설계하고 구현해 봄으로써 보다 수월하게 임베디드 시스템에 대한 이해를 넓히고 프로그램 개발 능력을 향상시킬 수 있었다.

• Geomechanics and Engineering
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• 제30권2호
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• pp.123-138
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• 2022

Present study computes the ultimate bearing capacity of an embedded strip footing situated on the rock slope subjected to seismic loading. Influences of embedment depth of strip footing, horizontal seismic acceleration coefficient, rock slope angle, Geological Strength Index, normalized uniaxial compressive strength of rock mass, disturbance factor, and Hoek-Brown material constant are studied in detail. To perform the analysis, the lower bound finite element limit analysis method in combination with the semidefinite programming is utilized. From the results of the present study, it can be found that the magnitude of the bearing capacity factor reduces quite substantially with an increment in the seismic loading. In addition, with the increment in slope angle, further reduction in the value of the bearing capacity factor is observed. On the other hand, with an increment in the embedment depth, an increment in the value of the bearing capacity factor is found. Stress contours are presented to describe the combined failure mechanism of the footing-rock slope system in the presence of static as well as seismic loadings for the different embedment depths.

• Geomechanics and Engineering
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• 제10권6호
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• pp.737-755
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• 2016

The load transfer depth of a ground anchor is the minimum length required to transfer the initial prestressing to the grout column through the bonded part. A thorough understanding of the mechanism of load transfer as well as accurate prediction of the load transfer depth are essential for designing an anchorage that has an adequate factor of safety and satisfies implicit economic criteria. In the current research, experimental and numerical studies were conducted to investigate the load transfer mechanism of ground anchors based on a series of laboratory and field load tests. Optical FBG sensors embedded in the central king cable of a seven-wire strand were successfully employed to monitor the changes in tensile force and its distribution along the tendons. Moreover, results from laboratory and in-situ pullout tests were compared with those from equivalent case studies simulated using the finite difference method in the FLAC 3D program. All the results obtained from the two proposed methods were remarkably consistent with respect to the load increments. They were similar not only in trend but also in magnitude and showed more consistency at higher pullout loading stages, especially the final loading stage. Furthermore, the estimated load transfer depth demonstrated a pronounced dependency on the surrounding ground condition, being shorter in hard ground conditions and longer in weaker ones. Finally, considering the safety factor and cost-effective design, the required bonded length of a ground anchor was formulated in terms of the load transfer depth.

• 대한임베디드공학회논문지
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• 제7권4호
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• pp.187-191
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• 2012

In these days, there are huge increases of concerning underwater acoustic sensor networks (UWASNs) to explore marine resources and to monitor climate change. To collect information from sensor nodes which are randomly deployed in underwater, Multi-Dimensional Scaling (MDS) based locating methods have been recently introduced, which consider sound speed to be constant in underwater. However, underwater sound speed tends to vary depending on underwater environment factors, such as depth, temperature, and salinity. In this paper, we propose a method considering environment factors, can influence upon sound speed in underwater, and introduce experimental setup which can follow up environmental factors.

• 대한임베디드공학회논문지
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• 제3권3호
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• pp.143-150
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• 2008

In this paper, we investigate a real-time environment recognition system based on stereo vision for moving object. This system consists of stereo matching, obstacle detection and distance estimation. In stereo matching part, depth maps can be obtained real road images captured adjustable baseline stereo vision system using belief propagation(BP) algorithm. In detection part, various obstacles are detected using only depth map in case of both v-disparity and column detection method under the real road environment. Finally in estimation part, asymmetric parabola fitting with NCC method improves estimation of obstacle detection. This stereo vision system can be applied to many applications such as unmanned vehicle and robot.

• 대한임베디드공학회논문지
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• 제14권1호
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• pp.25-31
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• 2019

An underwater glider is a type of autonomous unmanned vehicle and it advances using a vertical zig-zag glide. For this purpose, the position of an internal battery is regulated to control its attitude, and the amount of water in a buoyancy bag is regulated to control the depth. Underwater glider is suitable for a long-distance mission for a long time, because the required energy is much smaller than the conventional autonomous unmanned vehicle using propeller propulsion system. In this paper, control of horizontal tail wing is newly added to the conventional battery position and buoyancy control. The performance of the proposed controller is shown through Matlab simulation.