• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.471-478
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• 2018

Static tests of the composite wing structure were performed to verify damage tolerance design. Both 5 cases of DLLT and 3 cases of DULT were completed to meet requirements for static strength. After inducing BVID and open hole damages on the critical areas of the composite wing based on associated regulations, the DULT and fracture test were performed. In major wing parts, the measured strains and displacements agreed well with those of structural analysis. The initial structural fracture occurred at the area having minimum margin of safety as expected by analysis. As a result, it was confirmed that results from analytic model and strength evaluation were similar to behaviors of the composite wing structure.

• Computational Structural Engineering
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• v.10 no.3
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• pp.145-155
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• 1997

In this study, static and dynamic transient analysis of tracked vehicle structure with recoil impact load is performed for transient impact and traveling load using ANSYS and ABAQUS FEM codes. When transient impact loads are applied at tracked vehicle, the maximum dynamic Von Mises stress occurs between beam stiffener of upper plate and race ring and stress level is about 390-450 MPa. The results of transient analysis shows similar level and tendency with static stress with dynamic force effect of 1.6. The excessive stresses occur around the race ring for the both cases. When the traveling loads are applied on the tracked vehicle, the maximum Tresca stress occurs around suspension #1 and is about 450 MPa and results of static and nonlinear transient analysis are quite similar.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.141-145
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• 2007

The part in the structure that is most affected by changes of external temperature is the protective concrete layer that protects a waterproofing layer. Also, the waterproofing layer that is situated under or on the back of such a protective concrete layer is affected by temperature and the behavior of the protective concrete layer under the condition of consolidation or close adhesion. In particular, in many cases, the damage is serious mainly around the projection (such as a parapet), crack, and joint (expansion joint). However, there is no proper way of examining again the non-exposed waterproofing layer once it has been constructed. Therefore, there is an assessment only on the physical property of materials and the capability of the layer in construction, and there is no actual assessment in consideration of its environmental condition or the condition of the use of buildings after construction. Therefore, in order to create more pleasant buildings and to enhance the durability of structures, this study conducts research into the change of capability of non-exposed waterproofing material after the application of a static load and moving load on the waterproofing layer situated under or on the back of protective concrete.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.155-160
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• 1993

A design method for web frame scantling on engine room structures was described. The parameters determining the scantling of web frame were studied on the basis of the empirical ship's data. It is found that the parameters determining the scanting of web frame consist of tween deck height, main engine and propeller excitation frequency, scantling draft, web frame spacing, the number of decks and main engine BHP etc. And a formula proposed by empirical ship's data was established in view points of static and dynamic structural behavior. In this study, it can be shown that at initial design stage, a method for web frame scantling of engine room structure is provided as very practical design processes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.12
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• pp.3767-3781
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• 1996

Generally, dynamic loads are applied to real structures. Since the analysis with the dynamic load is extremely difficult, static loads are utilized by proper conversions of the dynamic loads. The dynamic loads are usually converted ot static loads by safety foactors of experiences. However, it may increase weight and decrease reliability. In this study, a method is proposed for the conversion process. An equivalent static load is calculated ot generate a same maximum displacement. The method is verified through numerical tests on a spring-mass systems of one and multi degrees-of freedom. It has been found that the duration time of the loads and the natural frequencies of the structures are critical in the conversion process. A road arem is a self-propelled howizer is selected for the application of the proposed method. The shape of the road arm is optimized under the converted static loads.

• Geotechnical Engineering
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• v.9 no.4
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• pp.27-36
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• 1993

The drained and undrained behavior of pure silt was investigated experimentally. Special attention was given to the stress-strain behavior of silt prior to failure and behavior at failure under monotonic and cyclic loading. A pure silica flour was chosen to form samples with two different densities of D,=80%, eo=0.68 and D,=35%, eo=0.9. The isotropically consolidated samples were tested in the triaxial testing device under monotonic undrained, drained compression and extension conditions. Also samples were tested under cyclic undrained condition. Based on the experimental results. it was qualitively identified that the overall behavior of silt is similar to that of sand. When compared with clay, silt shows a significantly different behavior due to its dilatant nature under both the monotonic and cyclic shear loadings.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1256-1261
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• 2004

Nonlinear Response Optimization using Equivalent Static Loads (NROESL) method/algorithm is proposed to perform optimization of non-linear response structures. It is more expensive to carry out nonlinear response optimization than linear response optimization. The conventional method spends most of the total design time on nonlinear analysis. Thus, the NROESL algorithm makes the equivalent static load cases for each response and repeatedly performs linear response optimization and uses them as multiple loading conditions. The equivalent static loads are defined as the loads in the linear analysis, which generates the same response field as those in non-linear analysis. The algorithm is validated for the convergence and the optimality. The function satisfies the descent condition at each cycle and the NROESL algorithm converges. It is mathematically validated that the solution of the algorithm satisfies the Karush-Kuhn-Tucker necessary condition of the original nonlinear response optimization problem. The NROESL algorithm is applied to two structural problems. Conventional optimization with sensitivity analysis using the finite difference method is also applied to the same examples. The results of the optimizations are compared. The proposed method is very efficient and derives good solutions.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.11-20
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• 2015

An unbonded post-tensioned anchor using a 15.2 mm diameter 7-wire strand was developed based on finite element analysis and experimental testing. In order to evaluate its performance, static load tests and load transfer tests were conducted following KCI-PS101. The static load tests and additional strand tensile tests confirmed that the developed anchor had a capacity more than nominal tensile strength of a 7-wire strand without any damage or deterioration. According to the result of load transfer tests for many different reinforcing details, specimens with no additional reinforcing bars sustained at least 1.64 times the nominal tensile strength of the strand.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.89-100
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• 2010

Although various methods for determination of damage threshold in rock have been suggested, clear damage thresholds were determined by some methods, but different thresholds were measured by other methods. We determined the damage thresholds in Hangdeung granite using all the methods suggested, and investigated the best methods, applicability and errors of each method. The crack initiation threshold and the crack damage threshold which are important in investigation of characteristics of crack development and failure were verified by field strength ratio method and long-term constant load test. The crack closure stress and the crack initiation stress were 57.5 MPa and 77.6 MPa, and the most exact values were yielded by crack volumetric strain. The secondary crack initiation stress was 90.6 MPa and AE event count and AE event count rate were the effective methods. The volumetric stiffness, AE event count and AE event count rate were the most effective methods for determination of crack coalescence threshold and crack coalescence stress was 110.3 MPa. The crack damage stress was 127.5 MPa and was measured correctly by volumetric stiffness and AE event count rate. The ratio between crack initiation stress and uniaxial compressive strength was 0.47 which was very similar with the FSR value of 0.46. The ratio between crack damage stress and uniaxial compressive strength was almost the same as the ratio between long-term strength and uniaxial compressive strength, indicating that the crack initiation stress and the crack damage stress measured were correct.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.61-63
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• 2002

멀티미디어 컨텐츠의 지능형 선택/검색 시스템(MISS: Multimedia Content Intelligent Selection/search) 는 콘텐츠를 공급하는 서버에 다량의 멀티미디어 컨텐츠들이 존재하며, 이 컨텐츠 중에서 원하는 것을 검색, 선택하는 시스템이다. 지능적 검색, 선택기능을 갖는 MISS 시스템은 인터넷 및 네트워크상에 연결된 시스템들간의 맞춤형 서비스 구현에 필요한 핵심이며, 모든 종류의 멀티미디어 콘텐츠에 적용 가능하다. 현재 WWW 서비스경우는 정보를 찾기 위하여 웹상에서 문서를 찾아주는 텍스트 기반 정보검색기술이 사용되고 있는데, 점점 우리가 접하는 정보의 형태는 텍스트와 함께 화상, 음성, 동영상 등의 멀티미디어화 및 디지털화하고 있다. 사용자들에게는 멀티미디어 데이터를 효과적으로 찾아야 하는 필요성이 증가하고 이에 따라 방대한 양의 분산된 멀티미디어 데이터를 처리할 수 있는 색인 및 검색 도구의 요구가 커지게 되었다. MISS 시스템은 WWW 서비스의 요구에도 적용될 수 있다. MISS 시스템은 다량의 동영상 콘텐츠 중에서 특정 배우, 감독등의 여러 가지 검색 조건으로 콘텐츠를 검색/선택할 수 있고, 하나의 동영상 콘텐츠 내에서 특정Video Segment를 검색할 수 있다. 본 MISS 시스템은 동영상에 대한 Search/Query를 위한DS 구조로써 MPEG-7의 User preference metadata를 이용하였다.