• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.519-526
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• 2010

The construction site for $\bigcirc\bigcirc$ transformer substation was located at a mountain valley. In order to prepare the site, the valley was first filled with crushed rock debris up to 63m. Since the main concern of this project is to minimize differential settlement of the foundation of transformer facilities, dynamic compaction was performed every 7m followed by reinforcement with EMP(Ez-Mud Piling). The EMP is one of bored piling methods, in which a hole is bored by means of air percussion and maintain by injecting Ez-Mud. Then a PHC pile (Pretensioned spun High strength Concrete pile) is embedded and finalized with a hammer. In this study, bearing capacities and long term behavior of a pile installed by EMP were investigated. To achieve these objectives, a series of tests such as static and dynamic load tests were conducted. In addition, a construction quality control standard was proposed based on the test results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1172-1175
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• 2004

At present, CHS(Compression Hip Screw) is one of the best prosthesis for the intertrochanteric fracture. There is nothing to evaluate the CHS itself with the finite element analysis and mechanical tests. They have same ways of the experimental test of the ASTM standards. The purpose of this study is to evaluate the existing CHS and the new CHS which have transformational design factors with finite element analysis and mechanical tests. The mechanical tests are divided into compression tests and fatigue test for evaluating the failure load, strength and fatigue life. This finite element method is same as the experimental test of the ASTM standards. Under 300N of compression load at the lag screw head. There are less differences between Group (5H, basic type) and Group which has 8 screw holes. However, there are lots of big differences between Group and Group which is reinforced about thickness of the neck range. Moreover, the comparison of Group and Group shows similar tendency of the comparison of Group and Group . The Group is reinforced the neck range from Group. After the experimental tests and the finite element analysis, the most effective design factor of the compression hip screws is the reinforcement of the thickness, even though, there are lots of design factors. Moreover, to unite the lag screw with the plate and to analyze by static analysis, the result of this method can be used with experimental test or instead of it.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.134-139
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• 2002

Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear power plant. However, effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. Acoustic emission(AE) has been widely used in various fields because of its extreme sensitivity, dynamic detection ability and location of growing defects. In this study, we investigated failure modes of locally wall thinned pipes and AE signals by bending test. From test results, we could be divided four types of failure modes of ovalization, crack initiation after ovalization, local buckling and crack initiation after local buckling. And fracture behaviors such as elastic region, yielding range, plastic deformation range and crack progress could be evaluated by AE counts, accumulative counts and time-frequency analysis during bending test. It is expected to be basic data that can protect a risk according to local wall thinning of pipes, as a real time test of AE.

• 한국방재학회 논문집
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• 제2권2호
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• pp.95-104
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• 2002

이 논문은 콘크리트 콘 파괴에 의해 지배될 때의 인장력의 예측과 Headed bar의 인발 파괴 양상을 보여준다. 1개의 다른 플레이트 형상과 세가지의 서로 다른 용접 방법에 따라 시험이 이루어졌다. 시험의 변수는 Headed plate에 연결된 철근의 직경(16mm, 19mm, 22mm), 형상(원형, 직사각형, 정사각형)과 head plate의 차원(면적, 두께), 철근과 head plate와의 연결을 위한 용접 방법(일반용접, 마찰용접)이다. Headed bar는 ASTM 970-98에 기초한 모양과 두께를 가진 다른 단면적으로 제조되었으며 콘크리트의 부착 길이는 CSA 23.3-94에 의거하여 산정되었다. 정적 인장하중이 적용되었으며 시험 인발 성능은 ACI-349와 CCD 방법과 같은 현재의 설계방법에 의해 산출된 값과 비교하였다. 실험결과와 기존식을 비교하면 Headed bar가 앵커와 달리 넓은 플레이트 면적과 이형철근으로 인해 기준식에 비해 높은 강도와 큰 파괴 반경을 나타내었다.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.29-35
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• 2014

This paper aims to obtain the effect of lightweight on Radius rod. The response surface method used in the paper is the statistical method. Optimization method is performed with the Radius rod using the lightweight material. Structural analysis is executed by using the ANSYS program to find static and dynamic responses. From this study result, it is verified that the response surface method has the advantage of optimum value in comparison with other optimization methods. The analysis is also performed by response surface method to derive optimal design values. Steel model and aluminium initial model are obtained by finite element analysis to clarify design criteria and the results are compared with three models each other. The weights can be reduced by optimal design analysis results of these models similar to those of existing products. The quantitative goals in this study can also attained through results of fatigue analyses. The reliability on optimal design of Radius rod can be improved by use of structural and fatigue analysis results.

• 지질공학
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• 제18권1호
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• pp.7-16
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• 2008

석회암지역은 외부의 압력에 의한 파쇄대와 용해성공동 등과 같은 지질학적인 결함을 대부분 갖고 있다. 특히, 장대교량을 건설할 경우 지질학적인 결함을 갖고 있는 석회암공동의 처리는 꼭 필요하다. 석회암 공동에서 기초의 침하량을 줄이고 지반을 보강하기 위한 대책공법으로 고압분사주입공법이 많이 활용되고 있다. 그러나 고압분사주입공법은 석회암공동에 대한 보강공법으로 활용되어 왔으나 연구실적과 기술적인 자료의 축적이 부족한 편이다. 그러므로 본 논문은 고압분사주입공법에 의하여 보강된 석회암공동 구간에 대하여 강도특성과 변형특성에 대한 연구결과를 제시하였다. 그리고 하중전이시험이 수반된 정재하시험에 의하여 지지력특성도 논의하였다.

• 한국산업융합학회 논문집
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• 제20권1호
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• pp.27-33
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• 2017

An agriculture machines are subjected to different loads conditions. Due to this loads variations there will be certain deformations and stress which affect the performance of the electric vehicle in adverse manner. The purpose of this paper is to analyze the total deformation and stress of the electric farm vehicle middle frame based on the finite element method. The proposed electric farm vehicle has lifting and dumping capability. Therefore, in this research four operational condition such as normal condition, dumping condition, lifting condition, and lifting-dumping condition was analyzed. In this research, the design for whole frame structure is elaborated. According to the mechanical characteristics of the frame, materials are selected and manufacturability requirements are limited. Based on ANSYS 15 software, the finite element model of electric farm vehicle is established to carry out static analysis on full-loaded conditions. The simulation results shows that the proposed design meet the strength requirements and displacement requirements. The maximum deformation 0.53611 mm and maximum stress 30.163 MPa occurred at lifting-dumping condition.

• 한국콘텐츠학회논문지
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• 제10권8호
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• pp.283-291
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• 2010

이 연구의 목적은 인체모형을 이용하여 옮기기 활동을 하는 동안 발의 배치(11자 배치와 $90^{\circ}$배치)와 옮기는 지면의 높이(휠체어 좌석과 같은 높이와 다른 높이)가 허리척추에 미치는 영향을 알아보는 것이었다. 자발적으로 실험참여에 동의한 건강한 남성 15명을 대상으로 4가지 조건에 따라 옮기기 활동을 실시 하였다. 옮기기 활동 동안 허리척추의 작업부담을 알아보기 위해, 위팔두갈래근, 척추세움근, 넙다리근의 근활성도를 표면근전도로 측정하였고, 힘판을 이용하여 수직 지면반발력을 측정하였고, L4/L5에 가해지는 압박력을 3DSSPP를 이용하여 측정하고 분석하였다. 그 결과, 오른쪽 넙다리근의 근활성도를 제외한 나머지 근육의 근활성도는 각 조건 사이 유의한 차이가 없었다. 수직 지면반발력은 각 조건 사이 유의한 차이가 있었다(p<.05). 또한 L4/L5에 가해지는 압박력은 같은 높이인 경우 발의 배치에 따라 유의한 차이가 있었다(p<.05). 따라서 옮기기 시 발을 11자로 배치하는 것보다 발을 90°로 배치하는 것이 체중이 한쪽으로 쏠리는 경향과 L4/L5 압박력을 줄이는데 도움이 되기 때문에 환자 옮기기 시 이를 적용하는 교육이 필요할 것이다.

• Earthquakes and Structures
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• 제10권4호
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• pp.939-963
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• 2016

According to the new directives about the rational and efficient use of energy, thermal bridges in buildings have to be avoided, and the thermal insulation (TI) layer should run without interruptions all around the building - even under its foundations. The paper deals with the seismic response of multi-storeyed reinforced concrete (RC) frame building structures founded on an extruded polystyrene (XPS) layer placed beneath the foundation slab. The purpose of the paper is to elucidate the problem of buildings founded on a TI layer from the seismic resistance point of view, to assess the seismic behaviour of such buildings, and to search for the critical parameters which can affect the structural and XPS layer response. Nonlinear dynamic and static analyses were performed, and the seismic response of fixed-base (FB) and thermally insulated (TI) variants of nonlinear RC building models were compared. Soil-structure interaction was also taken into account for different types of soil. The results showed that the use of a TI layer beneath the foundation slab of a superstructure generally induces a higher peak response compared to that of a corresponding system without TI beneath the foundation slab. In the case of stiff structures located on firm soil, amplification of the response might be substantial and could result in exceedance of the superstructure's moment-rotation plastic hinge capacities or allowable lateral roof and interstorey drift displacements. In the case of heavier, slenderer, and higher buildings subjected to stronger seismic excitations, the overall response is governed by the rocking mode of oscillation, and as a consequence the compressive strength of the XPS could be insufficient. On the other hand, in the case of low-rise and light-weight buildings, the friction capacity between the layers of the applied TI foundation set might be exceeded so that sliding could occur.

• Smart Structures and Systems
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• 제15권4호
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• pp.1085-1101
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• 2015

Changes in substructure conditions, such as ballast fouling and subgrade settlement may cause the railway quality deterioration, including the differential geometry of the rails. The objective of this study is to develop and apply a hybrid cone penetrometer (HCP) to characterize the railway substructure. The HCP consists of an outer rod and an inner mini cone, which can dynamically and statically penetrate the ballast and the subgrade, respectively. An accelerometer and four strain gauges are installed at the head of the outer rod and four strain gauges are attached at the tip of the inner mini cone. In the ballast, the outer rod provides a dynamic cone penetration index (DCPI) and the corrected DCPI (CDCPI) with the energy transferred into the rod head. Then, the inner mini cone is pushed to estimate the strength of the subgrade from the cone tip resistance. Laboratory application tests are performed on the specimen, which is prepared with gravel and sandy soil. In addition, the HCP is applied in the field and compared with the standard dynamic cone penetration test. The results from the laboratory and the field tests show that the cone tip resistance is inversely proportional to the CDCPI. Furthermore, in the subgrade, the HCP produces a high-resolution profile of the cone tip resistance and a profile of the CDCPI in the ballast. This study suggests that the dynamic and static penetration tests using the HCP may be useful for characterizing the railway substructure.