• Structural Engineering and Mechanics
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• 제69권5호
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• pp.499-509
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• 2019

While the wheel flat is an asymmetrical phenomenon in the railway, majority of researches have used two-dimensional models in the investigation of the effect of wheel flat on the wheel rail forces. This is due to the considerably low computational costs of two dimensional (2D) models although their reliability is questionable. This leaves us with the question of "what is the optimum modeling technique?". It is addressed in this research. For this purpose, two and three dimensional numerical models of railway vehicle/track interaction were developed. The three dimensional (3D) model was validated by comparisons of its results with those obtained from a comprehensive field tests carried out in this research and then, the results obtained from the 2D and 3D models were compared. The results obtained indicate that there are considerable differences between wheel/rail forces obtained from the 2D and 3D models in the conditions of medium to large wheel-flats. On the other hand, it was shown that the results of the 2D models are reliable for particular ranges of vehicle speed, railway track stiffness and wheel-fats lengths and depths. The results were used to draw a diagram, which presents the optimum modeling technique, compromising between the costs and accuracy of the obtained results.

• 농업과학연구
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• 제48권3호
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• pp.515-526
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• 2021

The frequency of typhoons and torrential rainfalls has increased due to climate change, and the concurrent risk of breakage of dams and reservoirs has increased due to structural aging. To cope with the risk of dam breakage, a more accurate emergency action plan (EAP) must be established, and more advanced technology must be developed for the prediction of flooding. Hence, the present study proposes a method for establishing a more effective EAP by performing flood and inundation analyses using one- and two-dimensional models. The probable maximum flood (PMF) under the condition of probable maximum precipitation (PMP) was calculated for the target area, namely the Gyeong-cheon reservoir watershed. The breakage scenario of the Gyeong-cheon reservoir was then built up, and breakage simulations were conducted using the dam-break flood forecasting (DAMBRK) model. The results of the outflow analysis at the main locations were used as the basis for the one-dimensional (1D) and two-dimensional (2D) flood inundation analyses using the watershed modeling system (WMS) and the FLUvial Modeling ENgine (FLUMEN), respectively. The maximum inundation area between the Daehari-cheon confluence and the Naeseong-cheon location was compared for each model. The 1D flood inundation analysis gave an area of 21.3 km², and the 2D flood inundation analysis gave an area of 21.9 km². Although these results indicate an insignificant difference of 0.6 km² in the inundation area between the two models, it should be noted that one of the main locations (namely, the Yonggung-myeon Administrative and Welfare Center) was not inundated in the 1D (WMS) model but inundated in the 2D (FLUMEN) model.

• 대한토목학회논문집
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• 제30권1B호
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• pp.33-40
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• 2010

본 연구에서는 조석으로 인한 만에서 부유사 이동과 해저지형변화 예측에 대한 2차원 유사운송모형인 HSCTM-2D 모형의 적용성을 평가하였다. 또한, 보정된 모형을 이용하여 아산만 해역과 천수만 해역에서 점착성 부유사의 유입으로 인한 장기 퇴적량을 추정하였다. HSCTM-2D 모형을 보정하기 위하여 대상해역에 위치한 검조소의 실측조위자료와 모의기간 동안 측정한 유속 및 부유사농도 자료를 모의결과와 비교하였으며, 실측자료와 모의결과가 유사한 경향을 나타내는 것으로 확인되었다. 대상해역의 퇴적환경을 고려하여 외해유입 부유사 농도를 결정하고 장기간의 조석활동에 의한 점착성 부유사의 퇴적량을 추정하였으며, 아산만 해역에서는 연간 퇴적율이 8.1 cm/yr, 천수만 해역에서는 연간 퇴적율이 14.5 cm/yr를 나타냈다. 이와같은 연구결과로부터 적용된 모델링 시스템이 해역의 점착성 부유사 이동 및 퇴적과정에 대한 이해와 완화대책수립에 유용할 것으로 판단된다.

• 대한공간정보학회지
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• 제24권2호
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• pp.71-78
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• 2016

After the 'Guidelines for the preservation of digital heritage' were published by UNESCO, interests in the fabrication of digital cultural heritage have been increasing throughout the world. The present study was intended to fabricate digital cultural heritages for existing cultural properties using the reverse engineering technology and obtain two-dimensional drawings. Jinju Castle Gongbukmun, which is a cultural property, was selected as a study subject and 3D modeling of Jinju Castle Gongbukmun was conducted by implementing 3D scanning and processing the point cloud data. Using the Gongbukmun 3D model (3D-Gongbukmun) made as such, requirements as a digital heritage were reviewed and 2D drawings of Gongbukmun such as front views, ground plans, and side views could be prepared.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권5호
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• pp.220-229
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• 2004

We have examined a technique of one-dimensional (1D) fluid modeling for radio-frequency Ar capacitively coupled plasmas (CCP) between unequal-sized powered and grounded electrodes. In order to simulate a practical CCP reactor configuration with a grounded side wall by the 1D model, it has been assumed that the discharge space has a conic frustum shape; the grounded electrode is larger than the powered one and the discharge space expands with the distance from the powered electrode. In this paper, we focus on how much a 1D model can approximate a 2D model and evaluate their comparisons. The plasma density calculated by the 1D model has been compared with that by a two-dimensional (2D) fluid model, and a qualitative agreement between them has been obtained. In addition, 1D and 2D calculation results for another reactor configuration with equal-sized electrodes have also been presented together for comparison. In the discussion, four CCP models, which are 1D and 2D models with symmetric and asymmetric geometries, are compared with each other and the DC self-bias voltage has been focused on as a characteristic property that reflects the unequal electrode surface areas. Reactor configuration and experimental parameters, which the self-bias depends on, have been investigated to develop the ID modeling for reactor geometry with unequal-sized electrodes.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.240-240
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• 2015

As Simpson et al. (1990) emphasized the importance of the straining process in the stratification and mixing in the estuarine circulation process, various researches have investigated on the relative contribution of each process to the overall potential energy anomaly dynamics. However, many numerical works have done only for two dimensional modeling along channel or the short distance cross sectional three dimensional simulations as Burchard et al. (2008) and the estuarine channel was not simulated so far. But, in the study on the physics of shallow coastal seas, spatial dimension in the three dimensional way affects significantly on results of a particular numerical model. Therefore, the comparison of two and three dimensional models is important to understand the real physics of mixing and stratification in an estuary. Also, as Geyer and MacCready (2013) pointed out that the lateral process seems to be important in determining the periodic stratifications, to study such process the three dimensional modeling must be required. The present study uses a numerical model to show the signification roles of each term of the time-dependent dynamic equation for the potential energy anomaly (PEA) in controlling along and lateral channel flows and different stratification structures. Moreover, we present the relationships between the ${\Phi}$-advection, the depth mean straining, vertical mixing and vertical advection can explain well how water level, salinity distribution and across velocity 2D model are slightly different from 3D.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제27권3호
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• pp.401-408
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• 2024

New technological advancements that are available in price and usability for K-12 classrooms result in new content areas to be explored and advancement of previous content area struggles. Visualizations of two-dimensional (2D) representations of three-dimensional (3D) figures and the actual 3D figure is a struggle not only limited to mathematics teaching and learning. However, if this struggle can be rectified and potentially improved through mathematics teaching and learning, the broader impacts of this extends beyond classroom mathematics. New 3D modeling software and 3D printers allow users to easily create and share models or download 3D models from online resources and print them to manipulate in their hand. There is plenty of literature now on classroom use of 3D modeling and printing. This article serves to build onto Ball and Stacey's (2005) suggestions for judicious use of calculators and computer software to address the judicious use of 3D modeling and printing technology for teaching mathematics for student learning. We discuss the following teaching strategies: promote careful decision making about 3D modeling and/or printing use, integrate 3D modeling and or printing into the curriculum, tactically restrict use of 3D modeling and or printing, and promote habits of spatial visualization.

• Structural Engineering and Mechanics
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• 제33권5호
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• pp.621-633
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• 2009

In this paper we compare the solution of the one-dimensional beam model and the numerical solution of the two-dimensional linearized elasticity problem for rectangular domain of the beam-like form. We first derive the beam model starting from the two-dimensional linearized elasticity, the same way it is derived from the three-dimensional linearized elasticity. Then we present the numerical solution of the two-dimensional problem by finite element method. As expected the difference of two approximations becomes smaller as the thickness of the beam tends to zero. We then analyze the applicability of the one-dimensional model and verify the main properties of the beam modeling for thin beams.

• Restorative Dentistry and Endodontics
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• 제40권2호
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• pp.161-165
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• 2015

Three-dimensional (3D) reconstruction of cone-beam computed tomography (CBCT) scans appears to be a valuable method for assessing pulp canal configuration. The aim of this report is to describe endodontic treatment of a mandibular second premolar with aberrant pulp canal morphology detected by CBCT and confirmed by 3D modeling. An accessory canal was suspected during endodontic treatment of the mandibular left second premolar in a 21 year old woman with a chief complaint of pulsating pain. Axial cross-sectional CBCT scans revealed that the pulp canal divided into mesiobuccal, lingual, and buccal canals in the middle third and ended as four separate foramina. 3D modeling confirmed the anomalous configuration of the fused root with a deep lingual groove. Endodontic treatment of the tooth was completed in two appointments. The root canals were obturated using lateral compaction of gutta-percha and root canal sealer. The tooth remained asymptomatic and did not develop periapical pathology until 12 months postoperatively. CBCT and 3D modeling enable preoperative evaluation of aberrant root canal systems and facilitate endodontic treatment.

• Journal of Welding and Joining
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• 제28권2호
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• pp.60-65
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• 2010

Although two dimensional axi-symmetric modeling is useful for calculating the residual stresses of a cylindrical weldment such as a core barrel, this conventional axi-symmetric modeling can not express the behavior of shrinkage well in the locally heated weld zone. New technique of two dimensional axi-symmetric modeling using a virtual fixture is suggested to simulate the behavior of dimensional changes in the weld zone during the heating period of the welding. The virtual fixture in the model has a role to restrain the expansion of the high temperature heated region, which simulates equivalent intrinsic restraint effect of the weldment. In the restraint condition of the virtual fixture above the critical yield strength, the calculated shrinkages by using the suggested axi-symmetric model agreed well with those measured in a welded mock-up. The calculated residual stresses by using the suggested axi-symmetric model also agreed well with those calculated by using conventional axi-symmetric model which has beenused for calculating residual stresses in the weldment.