• 한국BIM학회 논문집
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• 제14권1호
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• pp.11-21
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• 2024

This study is about a case of web application development using representative commercial BIM platform-linked APIs from Autodesk and Bentley Systems. The development method was aimed at application development using Autodesk's Forge API and Bentley System's iTwin API. The specific development content was limited to the Model Viewer, Issues, and File Transfer API, and the administrator's site. The first research result is that parts with different internal configurations of commercial platforms were independently modularized and developed, and the common front-end was unified. The second research result is that a web front-end technology, was used to visualize 3D models using the viewer API, and the possibility of additional application expansion was discovered.

• 한국분무공학회지
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• 제16권1호
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• pp.27-36
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• 2011

The impact force on the single and overlap region of twin spray was experimentally evaluated using visualization method in full cone type swirl nozzle spray. Visualization of spray was conducted to obtain the spray angle and breakup process. The photography/imaging technique, based on Particle Image Velocimetry (PIV) using high-speed camera, was adopted for the direct observation of droplet motion and axial velocity measurement, respectively. Droplet size was measured by Particle Motion Analyze System (PMAS). The purpose of this study is to provide fundamental information of spray characteristics, such as impact force, for higher etching factor in the practical wet etching system. It was found that the spray angle, axial velocity and impact force were increased with increasing the nozzle pressure while droplet size decreased with increasing the nozzle pressure. Droplet size increased as the distance from nozzle tip was decreased. The impact force of twin spray in the overlap region was about 63.29, 67.02, 52.41% higher than that of single spray at 40, 50 and 60 mm of nozzle pitch, respectively. Also, the nozzle pitch was one of the important factors in the twin spray characteristics.

• 전기학회논문지
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• 제67권5호
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• pp.688-694
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• 2018

The transition section of the overhead rigid conductor rail (ORCR) consists of a direct induction device and a limit point to prevent the power supply failure and failure of the electric railway vehicle pantograph due to the difference of the uplift in the catenary line. In T-Bar transition section, a twin simple catenary is mostly installed between the overhead catenary system (OCS) in the ground section and the ORCR in the underground section. In this paper, we compare and analyze the possibility of replacing the twin simple catenary with heavy simple catenary. The reliability of numerical analysis results was confirmed by comparing field test with numerical results. Comparing the numerical results of the twin simple catenary with the heavy simple catenary in the transition section, the difference uplift is 5.9[mm] on average. When applying heavy simple catenary instead of twin simple catenary, the slight difference of uplift can be compensated by adjusting the height of hanger-ear or support bracket.

• 대한기계학회논문집B
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• 제24권10호
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• pp.1300-1308
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• 2000

The objectives of this study was to investigate the spray characteristics of single spray and twin spray in the overlap region such as mean axial velocity, mean radial velocity, mean droplet size and probability density function of droplet size. A phase doppler anemometer was used as the measurement system for droplet size and velocity. In case of single spray, injection pressure was varied from 0.2MPa to 0.7MPa. Mean axial velocity, mean radial velocity and droplet size were decreased as the distance below nozzle tip was increased. In case of twin spray, the spray characteristics were measured by varying the distance between two nozzles from 127mm to 155mm. In the overlap region, the boundary of the overlap region was determined by obtaining the distribution of mean axial and radial velocity. Droplet size was increased as the distance from nozzle tip was increased. It was found that the distribution of droplet size for twin spray in the overlap region was different to single spray.

• 품질경영학회지
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• 제45권4호
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• pp.601-610
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• 2017

Purpose: Authors observe the digital twin enabled smart factory and/or digital manufacturing processes where Industry 4.0 technologies and quality management principles intersect. In this regard, this study reviews existing research regarding digital twins from the perspective of quality management. Methods: Initially, attention was given to how digital twins are manifested in the Industry 4.0 environment. Then, authors identify quality management elements amongst digital twin models, to align the concept of quality with the functional purpose of digital twins. After introducing specific examples of quality management tools applied to digital twins, the authors extend the domain of quality management into the analysis of multimedia format quality data obtained through machine vision. Results: Inspired by cases on the quality management application to digital twins, the authors suggest a framework for Industry 4.0 quality management. The envisioned suggested framework encompasses 4 dimensions, namely, 4M&1E, an application time window, new methodologies, and enabling technologies. Conclusion: Finally, the authors unfold the emerging trend of digital twin enabled smart factories, while emphasizing the necessity of quality management in conjunction with the introduction of digital twins.

• Geomechanics and Engineering
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• 제6권3호
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• pp.263-275
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• 2014

The development of transportation in large cities requires the construction of twin tunnels located at shallow depth. As far as twin tunnels excavated in parallel are concerned, most of the cases reported in literature focused on considering the effect of the ground condition, tunnel size, depth, surface loads, the relative position between two tunnels, and construction process on the structural lining forces. However, the effect of the segment joints was not taken into account. Numerical investigation performed in this study using the $FLAC^{3D}$ finite difference element program made it possible to include considerable influences of the segment joints and tunnel distance on the structural lining forces induced in twin tunnels. The structural lining forces induced in the first tunnel through various phases are considerably affected by the second tunnel construction process. Their values induced in a segmental lining are always lower than those obtained in a continuous lining. However, the influence of joint distribution in the second tunnel on the structural forces induced in the first tunnel is insignificant. The critical influence distance between two tunnels is about two tunnel diameters.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1459-1466
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• 2004

The purpose of this study is to investigate the effect of swirler angle and the aspect ratio of swirl chamber of nozzle on the characteristics of single and twin spray. The characteristics of sprays have been investigated by measuring the spray angle, droplet size and velocity. Visualization of spray was conducted to obtain the spray angle and breakup process. The spray characteristics such as droplet size and velocity were measured by Phase Doppler Anemometry(PDA). It was found that the spray angle was increased with increasing the swirler angle. For both sprays, the axial velocity and SMD were decreased with increasing the swirler angle. It was also shown that the axial velocity and SMD were decreased with increasing the aspect ratio of swirl chamber, but for the twin spray, the axial velocity and SMD were not influenced significantly by the changing the aspect ratio of swirl chamber. The effect of swirler angle on the spray characteristics was greater than the aspect ratio of swirl chamber for single spray. The nozzle pitch was one of the important factors affecting the spray characteristics of twin spray.

• 한국수정란이식학회지
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• 제14권3호
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• pp.171-176
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• 1999

This study was carried out to investigate the effect of co-culture system(bovine oviduct epithelial cells; BOEC) and defined culture system (modified TALP ; mTALP) on the conception of embryos transferred, and pregnancy and twin birth rates after transfer of fresh or frozen-thawed bovine blastocysts produced in vitro were also evaluated. Oocytes from the slaughterhouse ovaries were matured and fertilized using general protocol. The results obtained were as the following. The pregnancy rate after transfer was higher in co-culture group than in mTALP group, but was not signficantly different, and there is no difference between fresh embryo group and frozen-thawed embryo group in conception rate. The conception rate was not different whether 3∼4 blastocysts or 2 blatocysts transferred into a recipient, but the production rate of twin calves was significantly higher (p<0.05) when 3∼4 embryos transferred. The average birth weight of twin calves(24.38kg) was numerically, but not significantly lighter than that of single calves(26.68kg).

• 한국인터넷방송통신학회논문지
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• 제23권5호
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• pp.89-95
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• 2023

지하공동구는 도시의 상하수, 전력, 통신 등과 같은 중요한 시설을 수용하여 관리하는 도시기반시설로 화재, 지진, 침수 등과 같은 재난으로부터 보호해야 하는 국가 시설이다. 예측, 예방, 대비, 대응, 복구 등의 재난안전 전주기 관리 체계를 구축함에 있어서 첨단 ICT 기술과 데이터가 융합된 디지털 트윈 기술을 활용하여 지하공동구의 재난안전관리 플랫폼을 개발 중에 있다. 이 논문에서는 재난안전 디지털 트윈에 대한 성숙도 모델을 살펴보고 각 성숙도 단계 별 재난안전 디지털 트윈 구현을 위해 필요한 데이터셋을 정의하였다. 정의된 데이터셋의 카테고리의 조합에 따라 성숙도 단계를 다르게 하여 디지털 트윈 구현이 가능하도록 구성하였다.

• 한국농공학회논문집
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• 제66권3호
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• pp.53-62
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• 2024

The purpose of this study is to examine the methodology for applying digital twin technology to pumping station, identify the factors to be determined at each stage, and present its applicability. When analyzing the requirements for developing a digital twin for pumping station, they were categorized into service requirements, IoT device requirements, and gateway requirements, with a total of 39 requirements established. In system design, it was structured according to the principles of modularity, abstraction, stepwise decomposition, and information hiding, allowing the implementation of planned items for diagnosis and operational management. There are difficulties in setting communication-related protocols and applying them in the field due to the complexity of overseeing the entire system with data. Therefore, it is necessary to clarify the purpose of the system, and there are challenges in identifying the characteristics of individual facilities, such as pumps in pumping station, and fully incorporating them into the system process. Thus, the framework of the initial design is crucial for implementing a digital twin.