• Geotechnical Engineering
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• v.14 no.6
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• pp.5-16
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• 1998

In order to study the behavior of the sheet pile under vertical load in sands, model pile tests using calibration chamber are performed. For this research, five model piles, with the same section area and different degree of inclination of flange, were made. And model pile tests were conducted for each of these piles with different relative density and direction of applied load. For model pile which has the same shape, compression capacity is about 100% higher than pullout capacity and the difference increases with increasing relative density. Pullout ultimate capacity and corresponding displacement increase with increasing relative density and the pullout capacities remained almost the same irrespective of the inclination of flanges for the same density. The ultimate capacity under compression load is highest at 30$^{\circ}$ of inclination of flanges and the trend is more evident with increasing relative density. From the analysis of load distribution, the higher loading capacity at 30$^{\circ}$ of inclination of flanges with same section area may be attributed to the partial soil plug between flanges.

• Journal of the Korean Geotechnical Society
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• v.33 no.2
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• pp.17-26
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• 2017

Pile foundations that support offshore structures or transmission towers are dominantly subjected to cyclic lateral loads due to wind and waves, causing permanent displacement which can severely affect stability of the structures. In this study, a series of cyclic lateral load tests were conducted on a pre-installed aluminum flexible pile in sandy soil with three different relative densities (40%, 70% and 90%) in order to evaluate the permanent displacement of a cyclic laterally loaded pile. Test results showed that the cyclic lateral loads accumulated the irreversible lateral displacement, so-called permanent displacement. As the number of cyclic lateral load increased, accumulated permanent displacement increased, but the permanent displacement due to one loading cycle gradually decreased. In addition, the permanent displacement of a pile increased with decrement of relative density and decreased by soil saturation. From the test results, the normalized permanent displacement defined as the cumulative permanent displacement to the initial permanent displacement ratio was investigated, and empirical equations for predicting the normalized permanent displacement was developed in terms of relative density of the soil and the number of cyclic lateral load.

• Geotechnical Engineering
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• v.4 no.3
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• pp.43-52
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• 1988

The behavior of clays subjected to Repeated loading has been shown to be very different from the behavior under a single load application. Especially the behavior of pore water pressure is Qf considerable importance. The objective of this work is to experimentally study the stress-strain characteristics of clays, and this study includes the pore water pressure which is built up during the load repetition. For this study, the samples were consolidated isotropically in the triaxial cell during 24 hours, .and monotonic strain controlled triaxial test is carried out by uslng the tests of Compression failure, Cycled at failure, and Nonfailure equilibrium on remoulded samples under undrained .condition . Consequently there exists a critical level of repeated loading which seperates the behavior of a particular sample into two distinctly different patterns.

• Journal of the Korean GEO-environmental Society
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• v.22 no.1
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• pp.5-12
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• 2021

Owing to economically efficient and easy installation, bucket foundation is a promising solution for offshore wind turbines. This paper aims at finding the behavior of suction caissons and soil surrounding the foundation by using three-dimensional finite element analysis. Under various loading conditions, a wide range of foundation geometries installed in dense and medium dense sandy soil was considered to evaluate ultimate horizontal load and overturning moment capacity. The results show that the rotation and displacement of the bucket due to monotonic loading are largely dependent on the foundation geometry, soil density and load eccentricity. Normalized diagrams and equations for the ultimate horizontal load and overturning moment capacities are presented that are useful tool for the preliminary design of such foundation type.

• Journal of the Korean GEO-environmental Society
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• v.11 no.3
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• pp.17-22
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• 2010

This paper analyzed the characteristics of p-multiplier and the load distribution of H-pile group installed in weathered soil under horizontal loading. The results of this study conducted in pile arrangement ($2{\times}3$, $3{\times}3$), the pile center to center spacing (2D, 4D, 6D), and soil density (relative density: 40%, 80%) were drawn as follows. As to the average horizontal loading applied to each pile in pile groups, the fewer number of piles was, the larger average horizontal resistance became. As the result of analysis on p-y curves of single piles and pile groups according to the pile distance and the soil density, as the pile spacing was increased from 2D to 6D, the interaction coefficients of pile group showed 0.85~0.94 (piles in the front row), 0.57~0.79 (piles in the middle row), and 0.60~0.71 (piles in the rear row) in the loose ground and showed 0.76~0.82 (piles in the front row), 0.58~0.73 (piles in the middle row), and 0.53~0.70 (piles in the rear row) in the dense ground. As above, the wider pile distance was, the larger interaction coefficient value was shown among piles. In addition, piles in the front row showed bigger interaction coefficients than that of piles in the middle and back row.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.26-26
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• 2000

KM(Kick Motor)는 항우연에서 주관하여 개발하고 있는 3단형 과학관측로켓(KSR-III)이다. 본 연구는 이 KM에 적용되는 추진제 개발로서 추진기관에서 요구하는 성능, 밀도, 연소특성, 기계적특성, 점화성, 추진제/라이너/EFDM 접착력을 달성하고, 장기저장시 추진제에 작용하는 온도, 중력등 하중에 대한 추진제의 내구성을 확인하는 수면예측시험을 통해 KM이 사용하는 기간중 요구성능을 발휘할 수 있는 추진제 개발을 목표로 하고 있다. 본 논문에서는 KM 추진제 개발중 1차적으로 추진기관 요구성능을 달성하기 위해서 추진제 성능분석을 통한 기본조성을 설정하고, 이 기간조성을 토대로 밀도, 연소특성, 기계적 특성, 추진제/라이너/EPDM 접착력 실험 결과등을 정리하였고, 추진제 성능을 확인하는데 일반적으로 널리 이용하는 있는 표준모타(ST-8)에 적용하여 이론적 성능분석 및 실제 연소시험을 실시하여 그 결과를 비교 분석하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.401-402
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• 2010

This research initially suggest flexural toughness density as a key parameter describing energy absorption capacity of High Performance Fiber Reinforced Cementitious Composites [HPFRCC] regardless of the size of specimen. Two types of high strength steel fibers, Hooked and Twisted fiber, were used in two types of flexural specimen ($100{\times}100{\times}350mm^3$ and $150{\times}150{\times}500mm^3$) to estimate and validate the flexural toughness density.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.737-744
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• 2017

A new ultralow density material (ULDM) named Shellular was recently introduced. Shellular has a periodic cellular structure with smooth-curved shells. The template for the first Shellular was fabricated using lithography and its shape was similar to the P-surface, a type of triply periodic minimal surface (TPMS). In this paper, a new fabrication method of Shellular with D-surface, named W-Shellular, is described. W-Shellular is fabricated based on weaving of polymer wires. The compressive properties are evaluated by experiments and analysis in comparison with the previous ULDMs.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.79-85
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• 2000

본 논문에서는 사질토 지반에 일정기간 계속하여 증가되는 단계별 하중이 작용할 때 발생할수 있는 지반의 밀도화 현상을 hyperbolic model의 매개변수 변화를 고려한 방법으로 유한요소법에 의한 수치적 침하해석에 반영해 주었다. 이를 위해 사질토의 상대밀도별 삼축압축실험을 실시하여 매개변수를 산정하였으며, 이를 토대로 각각의 상대밀도의 변화에 따른 매개변수값을 Lagrange의 다항식 수치보간법으로 프로그램에 반영하였다. 또한 유한요소프로그램 내에서 요소의 체적을 계산하고 체적의 변화를 상대밀도 개념으로 접근함으로서 지반의 밀도화를 프로그램내에서 모사할수 있도록 하였다. 본 연구에서 개발한 해석 프로그램에 의한 지반의 밀도화현상의 모사 결과를 실내 모형기초재하실험에 의하여 비교 분석해 본 결과 기존의 해석 보다 향상된 결과를 나타냄을 알 수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2004.11a
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• pp.90-92
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• 2004

본 연구에서는 절삭 가공시 공구가 받는 절삭력과 칩-공구 사이에서 발생하는 절삭 열에 의한 공구의 변형을 예측하였다. 3D CAD를 이용하여 공구를 모델링 하였으며 절삭력과 절삭 열을 하중조건으로 부여하여 유한요소해석을 수행하였다. 하중조건으로 사용한 절삭력과 절삭 열은 절삭이론을 이용한 절삭력 모델을 사용하여 예측하였으며 실험을 통해 모델의 타당성을 검증한 결과이다. 그러므로 본 연구는 어떠한 사전 실험도 없이 절삭조건과 재료 물성치 그리고 공구 형상만을 알면 이에 따른 절삭력성분 및 절삭열 등을 얻을 수 있고, 이를 이용하여 절삭 가공시 공구의 변형을 예측할 수 있다.