• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.2
• /
• pp.655-666
• /
• 2014

Recently, as the appearance and exterior design of the construction structure are highlighted, the irregularly shaped structures are increasing in a construction facility. Many softwares provide a quantity take-off function of 3D object under BIM environment, however, they are focused on the limited function based on the solid modeling method. Because the vast geometric information of the curved surface is difficult to extract in the 3D objects that consist of major changes in vertical section shape as the irregularly shaped structures, it is difficult to express a 3D object as a solid model. On the other hand, the irregularly shaped structures can be expressed in relatively free in the surface model because the surface model consists of points, lines and surfaces. Accordingly, the surface modeling method is suitable for the modeling of large irregularly shaped structures. This study suggests a quantity take-off algorithm for the irregularly shaped structures using the surface modeling approach that is beneficial in the design work of structures. Some case projects are used for verifying the accuracy of the proposed method.

• 대한공업교육학회지
• /
• v.36 no.1
• /
• pp.115-130
• /
• 2011

When the hollow cylinder structure moves in underwater with high speed structural can be propagated from the end of the structure to the front side. This noise can reduce the sensitivity of the conformal array which installed in the surface of the cylinder. To reduce this noise propagation it is suggested to install two self-reduction rings at the surrounding of the cylinder which is 500mm in diameter and 840mm in length. The places of the two noise reduction rings are 120mm and 240mm point from the end of the structure. Two noise reduction rings reduced 10.1 % of maximum stress. When outside noise frequency applied to the structure from the 4kZ to 6kHz, 20dB noise reduction was calculated using 6 order polynomial equation. When outside noise frequency also applied to the structure with 200Hz, 500Hz, 900Hz, maximum sound pressure level point moved to the end of the structure. Most conformal sensors are fabricated at the front side of the structure. Based on the simulation results proposed two rings can be reduced noise propagation from the tail of the structure effectively.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.4
• /
• pp.1665-1673
• /
• 2013

Recently, the interest and demand on free formed structure providing aesthetic value as well as functionality has been increasing. Formwork has numerous advantages such as high strength, convenience, accuracy and good quality of surface roughness. Nevertheless, it increases construction cost and period to build complex shapes. For these purpose, deposition construction systems such as Contour Crafting and Concrete Printing have been developed with active collaboration between university and industry by applying the rapid prototyping technology to the construction industry in USA and England. Since there has been no related research in Korea, the possibility of spin-off technology and its fusion cannot be expected. In this paper, design elements including mechanical system and control system related to automatic deposition construction system prototype for constructing a free curved structure without mold are described. As for an appropriate material for the system, fiber reinforced mortar was selected by experiments on compressive strength, fluidity, viscosity and setting time. By performing transfer and extrusion experiments, the possibility of the development of deposition construction system was demonstrated. Based on this research results, it is required to keep the automatic deposition construction system improve and extend it into the new application area in construction industry.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.214-217
• /
• 1999

본 논문은 비균일, 비선형 분포를 가지는 비정형 하이드로폰 어레이를 견인하여 목표물로부터 발생된 협대역 신호에 대한 DOAs(Direction-Of-Arrivals) 및 도플러 주파수 정보를 동시에 추정하는 기법을 제안한다. 균일분포 선형 어레이를 견인하는 전통적인 처리기법은 DOA 추정에 국한되어 활용될 수 있다는 한계점을 가지고 있을 뿐 아니라 목표물의 특징을 파악할 수 있는 중요한 정보 중의 하나인 발생신호의 주파수 성분을 추정하기 위해서는 주파수 스펙트럼을 별도로 구성하여야하는 등의 난점을 지니고 있어 조기 경보 능력의 치명적인 제한점을 가질 수 있으며, 하이드로폰 어레이의 구조가 외부적인 환경요인에 의하여 선형을 유지하지 못함으로써 추정능력을 저하시킬 수 있다. 본 논문에서는 이러한 한계성을 극복하기 위하여 불규칙한 곡면을 가지고 있는 모함의 측면에 하이드로폰 어레이를 설치하여 목표물의 DOA 뿐만 아니라 모함의 이동에 의해 목표물과 사이에서 발생하는 도플러 주파수까지 동시에 추정하는 기법을 제안한다 특별히, 도플러 주파수 추정은 취득신호에 대한 퓨리에 변환과정을 거치지 않고 추정함으로써 계산량을 감소시킬 수 있다.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.11
• /
• pp.51-60
• /
• 2020

Estimation of passive earth pressure is an important factor in anchor block, temporary retaining wall and support block of raker that resist lateral earth pressure. In practice, due to ease of use, it is common to estimate the earth pressure using the theory of Coulomb and Rankine, which assumes the failure plane as a straight line. However, the passive failure plane generated by friction between the wall surface and the soil forms a complex failure plane: a curve near the wall and a flat plane near the ground surface. In addition, the limit displacement where passive earth pressure is generated is larger compared to where the active earth pressure is generated. Thus, it is essential to calculate the passive earth pressure that occurs at the allowable displacement range in order to apply the passive earth pressure to the design for structural stability reasons. This study analyzed the mobilized passive earth pressured to various displacement ranges within the passive limit displacement range using the semi-empirical method considering the complex failure plane.

• Proceedings of the KAIS Fall Conference
• /
• 2009.05a
• /
• pp.565-570
• /
• 2009

국내의 비정형 건축물은 현재 도입기로, 동대문디자인파크, 전곡선사박물관, 부산국제영화센터 등이 건설 계획 되어지고 있지만 대부분이 실시설계 또는 착공단계에 머물고 있고, 아직까지 구체적인 시공단계에 이른 건축물이 없는 실정으로 비정형외장재의 이중곡률 (Non-Uniform Rational B-Spines)을 반영한 프로토타이핑(Prototyping), 패널화(Panelizing), 현장조립 시 기하학 통제기법, 시공오차 측정기법, As-Planned 도면과 As-Built 도면의 비교를 통한 준공도면의 작성기법 등에 대한 준비가 절실히 필요한 상황이다. 그러나 현재 비정형 건축물의 설계는 초기계획(Concept Design) 단계에서 건축가와 구조기술자의 협업 중요성만 강조되고 있고, 건축물이 비정형화됨에 따라 기하학적으로 설계 및 시공되어야 하는 건축물의 외장재에 대한 설계방법과 시공단계에서 시공품질 확보방안, 시공 하자를 유발시키는 다양한 변수에 대한 대응방안 등은 아직까지도 그 중요성을 인식하지 못하고 있는 실정이다. 따라서 본 연구에서는 비정형 건축물의 설계에 사용되는 Architectural Geometry Control 도구 중 그 활용성이 부각되어 지고 있는 Bentley 사의 Generative Components를 활용하여 비정형 건축물의 이중곡률 곡면외장재의 부재생산을 위한 패널화, 제작도면 추출에 관한 연구를 수행하고자 한다.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.2
• /
• pp.106-115
• /
• 2018

The forward and afterward parts of ships and offshore structures are designed to improve the fuel consumption performance. These are made of curved plates with a large thickness. If a fabricated curved plate has some dimensional errors, a lot of additional cost is incurred in the assembly process. Thus, an accurate dimensional assessment is very important for fabrication. In this paper, we propose an assessment method for the dimensional quality management of curved plates. This can be applied to data measured using a variety of three-dimensional instruments, with boundary measurement points automatically classified and sorted to create a measurement surface. The assessment is evaluated after matching the CAD surface and the measured surface considering constrained conditions. The fabrication assessment is evaluated as a probability of how much the tolerance is satisfied.

• Journal of the Korean earth science society
• /
• v.31 no.6
• /
• pp.555-562
• /
• 2010

Three-dimensional laser scanner was used to accurately measure any possible strain on a slope under pertaining stress with the time difference of 7 months. The laser scanner has the ability to measure the 3-D coordinate of a target point by calculating the travel time of laser beam between the laser device and the target point, and has been proved to be effective for analysis of the displacement of slopes or large construction. The scanning data measured with time difference were analyzed to find any strain by approaches of plane angle change, curvature variation, twist of frame, displacement of merging point, etc. From the analysis, some weak points showing heavily distorted shape were detected, which was used to design the reinforcement.

• Journal of Energy Engineering
• /
• v.24 no.3
• /
• pp.135-141
• /
• 2015

The core melts stratifies into lower mixture layer and upper metal layer by density in a severe accident condition. The decay heat generated from the mixture layer threatens the integrity of the reactor vessel. This study simulated the natural convection heat transfer of the mixture layer with volumetric heat source using the mass transfer system. $H_2SO_4-CuSO_4$ electroplating system was used as the mass transfer system. With the modified Rayleigh number of $3{\times}10^{14}$, the Nusselt number showed minimum at the bottom and increased along curvature to the top of the experimental apparatus.

• Transactions of Materials Processing
• /
• v.22 no.4
• /
• pp.196-203
• /
• 2013

Flexible stretch forming is an appropriate process for manufacturing of components for aerospace, shipbuilding and architecture structures. Flexible stretch forming has several advantages including that it could be applied to form various shapes such as ones with double curved surfaces. In this study, a systematic numerical simulation was conducted for forming double curved surfaces using flexible stretch forming. The desired surface had a saddle type configuration. It had two radii one of 2500mm and the other of 2000mm along its length and width. In the simulation, the decrease of elastic recovery due to the stretching was confirmed. Experiments were also conducted to confirm the viability of the process. By comparing the simulation to the experiment results, the suitability of flexible stretch forming for double curved surfaces was verified. From the results, the maximum error from desired surface was confirmed at about 1.3mm at the edge of the surface. Hence, it is confirmed that flexible stretch forming has the capability and feasibility to manufacture curved surfaces for architectural skin-structures of buildings.