• Structural Engineering and Mechanics
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• 제31권6호
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• pp.679-696
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• 2009

The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann's series. In order to implement this approach, the special recurrent relations for half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading (degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.

• 한국농공학회논문집
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• 제51권3호
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• pp.71-78
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• 2009

Pipe section of bending part at the arch type pipe-house showed an ellipse with oblateness of 0.076 on the average. Flexural rigidity of bending part decreased by average 6.3% than that of an original round shape section. The deflection of arch type pipe-house measured by model experiments showed much bigger than the result of structural analysis. In case of arch type pipe-house, we supposed that the decrease of flexural rigidity for the bending part of pipes had an effect on deflection of roof under the working load. This effect should be considered in the structural analysis. Bending resistance of gable type pipe-house used a prefabricated connector which developed in this study showed about $1.5{\sim}1.8$ times stronger than that of the existing arch type or gable type processed bending. Therefore, we supposed that the gable-roofed prefabricated pipe-house is safer than arch type or bent gable type in case of heavy snowfall. According to house scales and section properties of steel pipe in use, safe snow depths and rafter intervals were presented for design of gable-roofed prefabricated pipe-house. Their standards were established in the range of the durable models recommended by RDA, and the comparative examinations were conducted by means of structural analysis. It was evaluated that the developed greenhouse model had a high applicability in the field.

• 한국주거학회논문집
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• 제14권6호
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• pp.125-133
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• 2003

The purpose of this study is to reveal the characteristics of Kan as a compositional unit in relation with its usage, building base, structural system, and roofing system in Seo Baek Dang and Gwan Ga Jeong. The results are as follows： Seo Baek Dang and Gwan Ga Jeong share a common characteristics： Kan module forms the plan to be 1：1 in shape and enables flexibility in usage and regularity in compositional aspect. In Seo Baek Dang, there are active level differences in base, room floor levels and column heights to achieve intended roof design while minimizing the deviation of module (500 mm) of four sides enclosing the an-madang (inner courtyard) and, in Gwan Ga Jeong, instead of differentiating levels, maximizing the module control (up to 1,560 mm) and lowering the roof slope are found. They are regarded resulting in a rather plane manner. Through a comparative analysis, it is found out that these two houses have a common characteristics of Kan to form a quadrate plan while they have differences both in conceptual and tectonic manner that is 'how to build a house' in similar conditions of region, period and society. In addition, Kan as a module is clarified to have a relative value that regulates both structural and aesthetical aspects.

• Geomechanics and Engineering
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• 제13권3호
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• pp.505-515
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• 2017

Based on the collapse characteristics of a shallow rectangular cavity, a three-dimensional failure mechanism which can be used to study the collapsing region of the rock mass above a shallow cavity roof is constructed. Considering the effects of surcharge pressure and surface bolt on the collapsing block, the external rate of works produced by surcharge pressure and surface bolt are included in the energy dissipation calculation. Using variational approach, an analytic expression of surface equation for the collapsing block, which can be used to study the collapsing region of the rock mass above a shallow cavity roof, is derived in the framework of upper bound theorem. Based on the analytic expression of surface equation, the shape of the collapsing block for shallow cavity is drawn. Moreover, the changing law of the collapsing region for different parameters indicates that the collapsing region of rock mass decreases with the increase of the density of surface bolt. This conclusion can provide reference for practicing geotechnical engineers to achieve an optimal design of supporting structure for a shallow cavity.

• 보존과학회지
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• 제35권1호
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• pp.71-80
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• 2019

This study examined the applicability of digital technologies based on three-dimensional(3D) scanning, modeling, and printing to the restoration of damaged artifacts. First, 3D close-range scanning was utilized to make a high-resolution polygon mesh model of a roof-end tile with a missing part, and a 3D virtual restoration of the missing part was conducted using a haptic interface. Furthermore, the virtual restoration model was printed out with a 3D printer using the material extrusion method and a PLA filament. Then, the additive structure of the printed output with a scanning electron microscope was observed and its shape accuracy was analyzed through 3D deviation analysis. It was discovered that the 3D printing output of the missing part has high dimensional accuracy and layer thickness, thus fitting extremely well with the fracture surface of the original roof-end tile. The convergence of digital virtual restoration based on 3D scanning and 3D printing technology has helped in minimizing contact with the artifact and broadening the choice of restoration materials significantly. In the future, if the efficiency of the virtual restoration modeling process is improved and the material stability of the printed output for the purpose of restoration is sufficiently verified, the usability of 3D digital technologies in cultural heritage restoration will increase.

• 항공우주시스템공학회지
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• 제16권2호
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• pp.25-32
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• 2022

캡 루프 페어링은 상용차가 주행 시 전면부에서 발생하는 유동 박리의 저항을 제어하여 상용차 항력 계수를 줄이는 장치이다. 상용차는 구조적으로 후방의 컨테이너를 적재해야 되기 때문에 차량의 주행방향으로부터 공기역학적 저항력을 피할 수 없게 설계되어 있다. 이러한 이유 때문에 유류비, 환경오염물질과 밀접한 연관을 가진다. 본 연구에서는 랭킨 반체 이론을 바탕으로 3D 페어링 형상을 설계하고 공력 해석을 통해 설계 결과를 검증하였다.

• 건축역사연구
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• 제33권1호
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• pp.7-18
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• 2024

Lots of educational and medical facilities were actively built along with foreign missionary activities under Korean Empire era. Paiwha Girls' High School is one of the educational facilities and at that time dormitory house was essential for recruiting girl students. Especially Paiwha's dormitory was traditional hanok style, but now an auditorium has built in its place. This study carried on to restore its hanok dormitory house based on the plan sketch which drawn Paiwha Girls' High School magazine. Through the analysis and investigation, we found some results as follows. Paiwha's Hanok Dormitory had composed of 23 dormitories rooms, management space, sanitary space, dining space, etc. In living rooms division, there are three types of rooms, and it's room was 4~5 pyung(坪) in size and using area per person was 1pyung. Besides all rooms were connected by a corridor. The structure was 5-ryang(樑) type without high column or with one high column. Looking at structure and the shape of the roof on the historic photos, it seems to be a lower roof slope than other traditional house because of reducing its weight. But its span between two columns was wider relatively.

• 한국지진공학회논문집
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• 제28권4호
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• pp.165-170
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• 2024

This study investigated the impact of soil-structure interaction on multi-degree-of-freedom structures using the shallow-foundation Winkler model, known as the BNWF model. The model's period was determined through eigenvalue analysis and compared to results obtained from FEMA's formula. Results indicated that considering the soil, the structure's period increased by up to 8.7% compared to the fixed-base model, aligning with FEMA's calculations. Furthermore, with adequate ground acceleration, roof displacement increased by 3.4% to 3.8%, while base shear decreased by 4% to 10%. However, roof displacement and base shear increased in some earthquake scenarios due to spectral shape effects in regions with extended structural periods. Foundation damping effects, determined through the foundation's moment-rotation history, grew with higher ground acceleration. This suggests that accounting for period elongation and foundation damping can enhance the seismic design of multi-degree-of-freedom structures.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1-6
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• 2011

In this study, wind tunnel test were conducted to improve an aerodynamic performance of HEMU400X pantograph system with 4 types of pantograph housing models. Experimental models were 1/4 scaled pantograph system, 1/4 scaled ground plate which is scaled down to real roof shape of HEMU-400x, and 4 types of pantograph housing models. The free stream of wind tunnel were 20, 40, 60, 70m/s. The lift and drag forces were measured with 2-axis load cell. And, Total pressure were measured with rake in the wake region of panhead. In addition, Surface flow visualization by tufts were performed to know flow characteristics around pantograph housing. According to the results of force tests and surface visualizations, pantograph housing shape is important part because the shape affects to pantograph system. Therefore, it is considered that adaption of pantograph housing is more advantageous to decrease drag and acoustic noise.

• Design & Manufacturing
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• 제14권4호
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• pp.65-70
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• 2020

Partial reinforcement of sheet metal parts with CFRP patch is a technology that can realize ultra-lightweight body parts while overcoming the high material cost of carbon fiber. Performing these patchworks with highly productive press equipment solves another issue of CFRP: high process costs. The A-pillar is the main body part and has an undercut shape for fastening with other parts such as roof panels and doors. Therefore, it is difficult to bond CFRP patches to the A-pillar with a general press forming tool. In this paper, a flexible system that applies uniform pressure to complex shapes using ceramic particles and silicone rubber is proposed. By benchmarking various A-pillars, a reference model with an undercut shape was designed, and the system was configured to realize a uniform pressure distribution in the model. The ceramic spherical particles failed to realize the uniform distribution of high pressure due to their high hardness and point contact characteristics, which caused damage to the CFRP patch. Compression equipment made of silicone rubber was able to achieve the required pressure level for curing the epoxy. Non-adhesion defects between the metal and the CFRP patch were confirmed in the area where the bending deformation occurred. This defect could be eliminated by optimizing the process conditions suitable for the newly developed flexible system.