In the present study, the structural and fatigue analysis on the shape change of an automatic press are investigated for prediction of operation safety and reliability of the automatic press along the thickness(t) and length(L) of head, and corner shapes(case 1, 2, 3). The equivalent stress and deformation characteristics of the automatic press were studied by computerized analysis method for the bushing production of the seat frame. An external stress of 14.0 MPa was applied to predict the operation stability and the fatigue limit of the structure. As the thickness of the header increased and the length of the header decreased, the load stability applied by the piston improved and the maximum stress and deformation were reduced. In addition, due to the change in shape of the corners, the load applied at the cross-sectional area of the corners decreases, and then the maximum stress and deformation appearing in the header are reduced. That is, the change of corner shapes affects the equivalent stress and deformation. That is the change of corner shapes affects the equivalent stress and deformation. From the fatigue and vibration analysis, fatigue failure does not occur even when the number of alternating operation of the automatic press increases, and the natural frequency is predicted for dynamic characteristics.

구조용 강재의 용접부는 강재(Base metal, BM), 용접모재(Weld metal, WM), 열영향부(Heat affected zone, HAZ)로 구성된다. 용접부를 구성하는 이들 세 부분의 구조적 성질은 서로 다를 것이므로, 강재의 용접부의 구조 거동은 BM, WM, HAZ로 구성된 복합체의 거동으로 고려할 수 있다. 본 연구에서는 용접부를 구성하는 BM, WM, HAZ 각각의 탄성계수를 나노압입으로 도출하고, 이들의 복합거동(composite action)을 고려한 용접부의 등가탄성계수(equivalent elastic modulus)를 산정하였다.

As an alternative to conventional explosive methods for demolition of concrete structures and rocks, the use of non-explosive demolition agents can be considered to reduce noise, vibration, and dust emissions during the demolition process. In this study, we conduct finite element analysis for crack initiation and propagation caused by the expansion of non-explosive demolition agents in square concrete structures. The predicted crack patterns are compared with the experimental results in the literature. The minimum values of the required expansion pressure of non-explosive demolition agents are also estimated, which depend upon the arrangement of non-explosive demolition agents and empty holes. Furthermore, we investigate the effect of empty holes on the fragmentation of concrete structures, and discuss the effective arrangement of non-explosive demolition agents and empty holes for fragmentation improvement.

The computing environment has changed rapidly to enable large-scale finite element models to be analyzed at the PC or workstation level, such as multi-core CPU, optimal math kernel library implementing BLAS and LAPACK, and popularization of direct sparse solvers. In this paper, the design considerations on a parallel finite element code for shared memory based multi-core CPU system are proposed; (1) the use of optimized numerical libraries, (2) the use of latest direct sparse solvers, (3) parallelism using OpenMP for computing element stiffness matrices, and (4) assembly techniques using triplets, which is a type of sparse matrix storage. In addition, the parallelization effect is examined on the time-consuming works through a large scale finite element model.

Geotextile tubes are excellent design strategies for both shoreline protection and dewatering of fine materials. A difficulty with regard to designing geotextile tubes is the matching of the appropriate fabric with the site-specific infilled material and the unavailability of a test to determine the soil-geotextile consolidation properties. Existing methods simulate and predict the final tube shape based on the initial and final unit weights of the infill but the time required to reach the final shape or the compatibility of the infill are not being considered. This study proposes an improved hanging bag test to evaluate the compatibility of an infill with the geotextile fabric, and at the same time, to obtain the soil-geotextile consolidation properties. With the obtained consolidation properties, a big prototype simulation was possible, explaining the deformation behavior of the tube in the field. An analytical procedure used in modeling the tube was coupled with the large strain consolidation theory to simulate the filling and dewatering process.

도시 스프롤 정의를 구성하는 핵심적인 두 가지 요소는 저밀도와 분절화이다. 밀도를 기반으로 스프롤을 측정하는 경우 분절화 정도를 파악할 수 없고, 분절화를 중심으로 스프롤을 측정하는 경우 밀도 변화를 고려하기 어렵다. 본 연구의 목적은 밀도와 분절화 정도를 동시에 고려하는 새로운 스프롤 측정치를 고안하는 것이다. 이를 위해 동일한 측정 범위를 갖는 밀도 기반의 스프롤 지수와 두 개의 공간구조 기반 스프롤 지수인 인접 통계량과 분할 지수를 가중치 기법을 이용하여 결합하였다. 이 새로운 측정치를 밀도-공간구조 기반 스프롤 지수로 명명하였다. 밀도, 인접 정보 및 도시화된 지역의 면적을 이용하여 지수를 손쉽게 계산할 수 있고 결합한 세 지수의 측정 범위와 해석 방향이 동일하기 때문에 개발된 지수의 해석이 직관적이다. 사례분석의 결과는 개발된 지수가 밀도기반 접근과 공간구조 기반 접근의 단점을 보완할 수 있음을 보여준다.

Wind tower structure has relatively simple shape compared to other structures, but due to its characteristics, various and irregular environmental loads are applied. These loads cause vibrations at tower, and can cause failure of the structure if over vibration occurs. Vibration occurred at structures is gradually exhausted by damping of the structures, and if high damping is ensured, the failure of the structure due to over vibration can be prevented. In this study, the vibration reduction effects are to be analyzed through FEM analysis by examining the top displacement, bottom moment, and bottom fatigue damage of the structure depending on damping ratio of the wind tower structure.

This study investigates dynamic characteristics of a 2MW wind turbine structure by long-term response monitoring with accelerometers, tiltmeter and strain gauges. The object wind turbine structure is located in Jeju Island, Korea. The natural frequency and damping ratio were evaluated by least-square frequency domain decomposition and random decrement technique using acceleration response data. As a result, it was found that natural frequencies with 1st, 2nd and 3rd modes, and blade passing frequencies with 1P, 2P and 3P were clearly showed from power spectral densities of acceleration reponses. Furthermore, 1st model frequencies were almost constant with increase in standard deviations of acceleration responses. Another notable observation was that when standard deviations of acceleration responses were small, damping ratios showed to diverge. However, when standard deviations of acceleration responses had large values, damping ratios were converged to about 0.5%.

Floating PV generation system, renewable energy power plant, is able to overcome the disadvantages of ground PV generation system and improve generating efficiency. The frame structural system is an established technology among a diversity of structural technologies which has been developed for related fields. In this paper, the both structural safety and characteristics of floating PV generation structures depend on the different placement angle of solar module are investigated to improve the commercial viability, the structural safety, and characteristics of floating PV generation structures. In addition, for the estimation of structural safety, FE analyses are conducted. From the results, the lower placement angle of solar module improves the structural safety of floating PV generation system.

While going into troops for writing in the vignette style(小品文) in opposition to the Classical Chinese(古文), Yi Ok stopped by Songgwangsa Temple in Wanju. The things he felt during this stop were recorded in the Temple Chapter ( 寺觀) written in 1795. Therefore, the present dissertation evaluates the Songgwangsa Temple of the time based on this Temple Chapter . Data in the Temple Chapter draws attention to the fact that it records the layout of the temple in detail. Thus the study was able to confirm the change in layout by reviewing relevant records about repair. This reveals that the form of layout in general has been maintained although there were changes involving the relocation of the buildings and their names. Furthermore, the original Buddhist building was changed to a quarter for the monks. Also, in terms of layout after the 18th century, there are frequent name changes of the Myeongbujeon(冥府殿) and Nahanjeon(羅漢殿). After two repairs, in order to find the appearance of a Daeungjeon(Main Buddhist hall) with a two-storied structure of five bays at the front, the study evaluated the Geugnakjeon at Muryangsa Temple and the Daeungbojeon at Magoksa Temple. The evaluation revealed that the ‘Jeol’ used in the Temple Chapter were small pillars erected on a ridgepole just like the Geugnakjeon at Muryangsa Temple, and that the angle rafters were installed to corner bays in rectangular form. The intellectual Yi Ok left behind invaluable architectural data that reveals the Songgwangsa Temple of the 18th century.

본 연구에서는 쌍동형 카페리에 대한 기본 구조 설계 및 구조 해석을 위한 기법을 제시한다. 카페리와 같이 길이 50미터 이상 길이와 폭/ 비가 12보다 큰 중/소형 고속 선박의 강도 해석에 대한 규정이나 방법론은 아직까지 명확하게 제시되지 않고 있다. 따라서 본 논문에서 부재의 스캔 틀링은 한국선급기준을 적용하였고, 설계안에 대한 구조강도 검증을 위해서 카페리 전용선박 기준에 의해 추가적으로 검증하였다. 특히, 카페리 전 용선박 기준을 적용하여, Hull girder ultimate strength를 추가적으로 수행하여, 현재 기준에 의한 설계의 모호성을 극복하도록 제안하였다. 본 연구를 통해 도출된 연구 결과는 앞으로 고속 쌍동형 카페리의 구조설계 및 구조해석에 관련된 기본적인 자료로 유용하게 활용될 것으로 예상된다.

Numerical analysis has been carried out to investigate the structural characteristics of auxiliary shaft system in a compact special vehicle. Stress and deformation distributions with safe factor in the auxiliary axle system are compared. It can be seen that maximum stress happens near the local axle position and deformation at the air spring is also predicted. The results from this study could be applicable for optimal design of variable shaft system in the compact special vehicle.

안동댐 내 저수지 및 유입 하천 6개 지점에 대하여 2016년 7월과 9월, 총 2회에 걸쳐 저서성 대형무척추동물 조사를 수행하였다. 분류군별 출현현황은 저수지 수변부(L1, L2, L3)와 유입 하천(S1, S2, S3)에서 각각 총 9목 31종, 14목 79종이 출현하였다. 군집지수 분석결과, 평균 다양도지수(H')와 균등도지수(J')는 S1에서 각각 3.04와 0.73으로 가장 높았으며, 평균 풍부도지수(R')와 우점도지수(DI)는 각각 S2(2.84), L3(0.98)에서 가장 높게 나타났다. 섭식기능군(FFG) 분석결과, 종수 점유율은 저수지에서 P(Predator)가 41.9%, 유입 하천에서 GC(Gathering Collector)가 30.4%로 가장 높게 나타났다. 서식기능군(FHG) 분석결과, 비교적 유수역을 선호하는 CL(Clinger)의 종수점유율이 유입 하천에서 43.0%로 저수지의 32.3%보다 더 높게 나타났다.

경상북도에 위치한 유전자원보호구역 3개 지역( 봉화지역의 자작나무, 영주지역의 신갈나무, 울진지역의 소나무)을 식생 유형에 따라 2016년 5월에서 9월까지 함정 트랩(pitfall trap)을 5회씩 3반복하여 각각 상대적으로 비교하였다. 채집된 보행성 딱정벌레류는 딱정벌레과 등 총 25과 116종 1,663개체가 확인되었으며 자작나무 군락에서 종풍부도(72), 종균등도(0.829), 종다양도(3.544) 모두 가장 높게 나타났다. MRPP(Multi-response Permutation procedures)분석결과 서식지에 대한 군집차이가 있다고 확인되었으며(p < 0.001), Bray-curtis 분석결과 군집간의 확연한 차이와 함께 자작나무 군락이 보행성 딱정벌레류의 종 풍부도에 큰 영향을 주는 것으로 나타났고 소나무군락은 다른 지역과 비교해 상대적으로 낮은 영향을 받았다. 식생 유형에 대한 지표종 분석결과 자작나무군락에서 끝무늬녹색먼지벌레 (Chlaenius micans Fabricius)를 포함한 4종, 신갈나무 지역에서 긴윤머리먼지벌레(Trichotichnus coruceus Tschitscherine) 를 포함한 9종, 소나무 지역에서 솔곰보바구미(Hylobius harodi Faust)를 포함한 3종의 지표종이 확인되었다.