To analyse and review the fishing performance and species composition according to the size of the entrance and mesh of the pot in the southern coastal waters (Tongyeong, Gyeongsangnam-do and Yeosu, Jeollanam-do), the experiment in this study caught one class, eight orders, 17 families, 23 species, 662 fishes, and 99,833 g. The largest number of fish species was Conger myriaster (301 fishes caught) accounting for 45.5%, followed by Octopus vulgaris (152) accounting for 23.0%, Charybdis japonica (45) accounting for 6.8%, Sebastiscus marmoratus (43) accounting for 6.5%, and Parapercis sexfasciata (42) accounting for 6.3%. Conger myriaster, Octopus vulgaris, Charybdis japonica, Sebastiscus marmoratus, and Parapercis sexfasciata accounted for 88.1% of the total catch. For other fish species, 68 fishes of 18 species were caught, accounting for 12.5% of the total. As a result of the total catch survey, the catch rate of Conger myriaster was the highest at 50.9% in B. 22 mm/280 mm. In addition, the average total length per fish increased as the entrance size increased. The weight ratios of Conger myriaster, Octopus vulgaris, and other fish species based on the total weight caught in each pots of the six species of test fishing gear are as follows. A pots 66.6%, 26.5%, 6.9%, B pots 57.2%, 24.5 %, 18.3%, C pots 43.2%, 31.5%, 25.3%, D pots 7.4%, 56.7%, 35.9%, E pots 43.6%, 0%, 56.4%, and F pots 5.0%, 79.6%, 15.4%.

Research has been conducted on a wide variety of 3D printer circular fin heads. In this study, we proposed a sequence and method for a more efficient mesh study in the CFD model to calculate the Nusselt number of the circular fin head of an FDM 3D printer using the Taguchi method, sensitivity, and ANOVA. As a result, the CFD model to calculate the Nusselt number of the circular fin head of an FDM 3D printer has high sensitivity and contribution in the order of Base target mesh size, Prism layer number, and Prism layer thickness. We propose to increase work efficiency by performing mesh optimization in the order of factors with high sensitivity to level changes.

The existing wire mesh clip forming process requires improvement as the production process is semi-automatic, which greatly threatens the safety of workers and exposes them to labor intensity and industrial accidents. In this research and development, we designed and developed an automated wire mesh automatic clip system by improving problems in the existing welded wire mesh production process. As a result, the production volume per hour was improved from 450 to 516, and the clip formation time was improved, shortening the production time to 42.5 seconds. Additionally, the defect rate was reduced from 7% to less than 3%.

본 논문에서는 역학적 변수들을 측정하는 방안으로 디지털 이미지 프로세싱과 강형식 기반의 MLS 차분법을 융합한 DIP-MLS 시 험법을 소개하고 추적점의 위치와 이미지 해상도에 대한 영향을 분석하였다. 이 방법은 디지털 이미지 프로세싱을 통해 시료에 부착 된 표적의 변위 값을 측정하고 이를 절점만 사용하는 MLS 차분법 모델의 절점 변위로 분배하여 대상 물체의 응력, 변형률과 같은 역 학적 변수를 계산한다. 디지털 이미지 프로세싱을 통해서 표적의 무게중심 점의 변위를 측정하기 위한 효과적인 방안을 제시하였다. 이미지 기반의 표적 변위를 이용한 MLS 차분법의 역학적 변수의 계산은 정확한 시험체의 변위 이력을 취득하고 정형성이 부족한 추 적 점들의 변위를 이용해 mesh나 grid의 제약 없이 임의의 위치에서 역학적 변수를 쉽게 계산할 수 있다. 개발된 시험법은 고무 보의 3 점 휨 실험을 대상으로 센서의 계측 결과와 DIP-MLS 시험법의 결과를 비교하고, 추가적으로 MLS 차분법만으로 시뮬레이션한 수치 해석 결과와도 비교하여 검증하였다. 이를 통해 개발된 기법이 대변형 이전까지의 단계에서 실제 시험을 정확히 모사하고 수치해석 결과와도 잘 일치하는 것을 확인하였다. 또한, 모서리 점을 추가한 46개의 추적점을 DIP-MLS 시험법에 적용하고 표적의 내부 점만을 이용한 경우와 비교하여 경계 점의 영향을 분석하였고 이 시험법을 위한 최적의 이미지 해상도를 제시하였다. 이를 통해 직접 실험이 나 기존의 요소망 기반 시뮬레이션의 부족한 점을 효율적으로 보완하는 한편, 실험-시뮬레이션 과정의 디지털화가 상당한 수준까지 가능하다는 것을 보여주었다.

폭발 수치해석 기법 중 Arbitrary Lagrangian-Eulerian(ALE)는 구조물의 파괴뿐만 아니라 폭발 이후 충격파의 전파 과정까지 관찰할 수 있는 장점이 있다. 그러나 동적 해석 시 유한요소 모델의 격자망 크기가 일정 수준 이하로 감소하게 되면 해석 결과의 신뢰도가 부 정확해진다. 본 연구에서는 ALE 수치해석 기법을 활용하여 대기의 격자망 크기가 해석의 정확도에 미치는 영향을 조사한다. 다양한 조건의 격자망 크기와 폭발 중량을 갖는 대기 중 폭발모델을 구축하고, 폭발 중심으로부터 거리에 따른 폭발압력을 관찰한다. 수치해 석과 실험에서 얻은 최대 폭발압력 결과에 대해 평균 제곱 오차를 계산하여 최적의 격자망 크기를 제안하고, 제안된 크기를 바탕으로 폭발물 중량과 대기의 최적 격자망 크기에 대한 상관관계를 분석한다. 본 연구는 다양한 중량을 가진 폭발물 해석에서 최적의 격자망 크기를 제공함으로써 신뢰성이 향상된 폭발 수치해석 모델 개발에 도움이 될 것으로 기대한다.

As nuclear decommissioning ventures become increasingly complex, the role of digitalization in facilitating and enhancing these operations is becoming indispensable. This transition to a more digitized approach presents a myriad of advantages, including: augmented avenues for data acquisition, analysis, and visualization to bolster dismantling strategies; simulations in virtual environments for operator training; precise forecasting of future waste emergence, culminating in refined cost estimations; and more immersive decommissioning visualizations for both operators and external stakeholders. Salient benefits conferred by the integration of digital technologies in decommissioning encompass improved collaboration, enriched knowledge transfer, clarity regarding present technological constraints, insights into key influencing factors, clearer criteria for technology selection, and a profound understanding of the potential challenges and merits of a broader incorporation of digital tools in decommissioning endeavors. Of paramount importance is the opportunity presented for superior workforce training and safety measures, exemplified by ALARAbased planning. Amidst the myriad facets of digital adoption, 3D modeling of nuclear facilities derived from laser-scanned point clouds stands out as a pivotal domain in the digitalization. The transformation of intricate point cloud data into a comprehensible 3D mesh remains the crux of this paper. The process of mesh generation, despite being simpler than its counterpart of converting to a 3D solid model, is crucial for multiple reasons. The resultant 3D mesh offers an enhanced visual representation compared to a sparse point cloud, paving the way for improved spatial perception. Furthermore, it serves as a rudimentary tool for approximating component volumes and the ensuing waste, thereby playing an instrumental role in waste manipulation strategies, notably in collision detection. This paper delves deep into the nuances of mesh generation, conducting an parametric study of mesh conversion algorithms, including down-sampling rates. Through this rigorous examination, we endeavor to shed light on optimal methodologies, hoping to catalyze advancements in the digitalization of nuclear decommissioning processes.

In the fluid-structure interaction analysis, the finite element formulation is performed for the wave equation for dynamic fluid pressure, and the dynamic pressure is defined as a degree of freedom at the fluid nodes. Therefore, to connect the fluid to the structure, it is necessary to connect the degree of freedom of fluid dynamic pressure and the degree of freedom of structure displacement through an interface element derived from the relationship between dynamic pressure and displacement. The previously proposed fluid-structure interface elements use conformal finite element meshes in which the fluid and structure match. However, it is challenging to construct conformal meshes when complex models, such as water purification plants and wastewater treatment facilities, are models. Therefore, to increase modeling convenience, a method is required to model the fluid and structure domains by independent finite element meshes and then connect them. In this study, two fluid-structure interface elements, one based on constraints and the other based on the integration of nonsmooth functions, are proposed in nonconformal finite element meshes for structures and fluids, and their accuracy is verified.

APro, developed in KAERI for the process-based total system performance assessment (TSPA) of deep geological disposal systems, performs finite element method (FEM)-based multiphysics analysis. In the FEM-based analysis, the mesh element quality influences the numerical solution accuracy, memory requirement, and computation time. Therefore, an appropriate mesh structure should be constructed before the mesh stability analysis to achieve an accurate and efficient process-based TSPA. A generic reference case of DECOVALEX-2023 Task F, which has been proposed for simulating stationary groundwater flow and time-dependent conservative transport of two tracers, was used in this study for mesh stability analysis. The relative differences in tracer concentration varying mesh structures were determined by comparing with the results for the finest mesh structure. For calculation efficiency, the memory requirements and computation time were compared. Based on the mesh stability analysis, an approach based on adaptive mesh refinement was developed to resolve the error in the early stage of the simulation time-period. It was observed that the relative difference in the tracer concentration significantly decreased with high calculation efficiency.

In this study, a comparative test operation was conducted through the alternate haul method to examine the selectivity of the four mesh sizes (60 mm, 90 mm, 110 mm, and 130 mm) of the trawl codend. The selectivity was analyzed using the SELECT model considering the fishing efficiency (split parameter) of each fishing gear in the comparative test fishing operation in the trawl and the maximum likelihood method for parameter estimation. A selectivity master curve was estimated for several mesh sizes using the extended-SELECT model. As a result of analyzing the selectivity for silver croaker based on the results of three times hauls for each experimental gear, it was found that the size of the fish caught increased as the size of the mesh size increased. When the selectivity for each mesh size analyzed by the SELECT model considering the split ratio was evaluated based on the size of the AIC value, the estimated split model was superior to the equal split model. Based on the master curve, the 50% selection length value was 2.893, which was estimated to be 136 mm based on the mesh size of 60 mm. In some selectivity models, there was a large deviance between observed and theoretical values due to the non-uniformity of the distribution of fished length classes. As a result, it is considered that appropriate sea trials and selectivity evaluation methods with high reliability should be applied to present trawl fishery resource management methods.

대부분의 모바일 AR 컨텐츠들은 모바일 디바이스의 기술적 한계로 인해 평면 탐지 후, 그 위에서만 구현되는 제한된 구조를 가지고 있다. 이러한 문제는 제한된 공간이 표현의 범위를 제한하기 때문에 모바일 AR의 확산 에 크게 저해가 될 수 있다. 한편 Unity의 AR Foundation이 제공하는 ‘Meshing’은 실제 오브젝트의 크기와 위 치에 알맞게 메시를 생성해주는데, 이를 활용한다면 모바일 AR 컨텐츠들은 평면에서 벗어나 더 넓은 현실 공 간에 구현될 수 있다. 하지만 ‘Meshing’은 모바일 기기의 센서가 닿지 못하는 부분에는 메시를 생성하지 않기 때문에 별도의 작업 없이 그대로 사용한다면 게임 오브젝트가 빠져나갈 수 있는 구멍이 생길 수 있다. 이 구 멍은 컨텐츠 구현에 있어서 치명적이기에 Hole-Filling 알고리즘을 사용하여 구멍을 메우고자 하는 연구가 있 었다. 하지만 기존 연구에서 사용하는 Hole-Finding 알고리즘은 특정 상황에서 외곽선과 구멍을 제대로 구별해 내지 못하는 문제가 있다. 이 문제는 일부 구멍은 메우지 못하고 외관선끼리 이어버려 컨텐츠에 치명적인 문 제를 야기한다. 본 논문에서는 Meshing이 제공하는 노말 벡터와 경계선들로 계산한 노말 벡터 간의 차이를 이 용해 구멍과 외곽선을 구분하는 방법을 제안한다. 이 방법을 적용한 결과, 이전 연구의 방법보다 좀 더 빠르 면서 구멍과 외곽선을 제대로 구별하는 모습을 확인하였다.

The structural analysis module is an essential part of any integrated structural system. Diverse integrated systems today require, from the analysis module, efficient real-time responses to real-time input such as earthquake signals, extreme weather-related forces, and man-made accidents. An integrated system may also be for the entire life span of a civil structure conceived during the initial conception, developed throughout various design stages, effectively used in construction, and utilized during usage and maintenance. All these integrated systems’ essential part is the structural analysis module, which must be automated and computationally efficient so that responses may be almost immediate. The finite element method is often used for structural analysis, and for automation, many effective finite element meshes must be automatically generated for a given analysis. A computationally efficient finite element mesh generation scheme based on the r-h method of mesh refinement using strain deviations from the values at the Gauss points as error estimates from the previous mesh is described. Shape factors are used to sort out overly distorted elements. A standard cantilever beam analyzed by four-node plane stress elements is used as an example to show the effectiveness of the automated algorithm for a time-domain dynamic analysis. Although recent developments in computer hardware and software have made many new applications in integrated structural systems possible, structural analysis still needs to be executed efficiently in real-time. The algorithm applies to diverse integrated systems, including nonlinear analyses and general dynamic problems in earthquake engineering.

본 연구에서는 자장에 영향을 미치지 않는 금속성 메시 포화 밴드의 성능을 프로그램을 이용하여 모의실험 함으로써, 부분 촬영 MRI 검사 시 발생하는 둘러겹침허상의 제거 방법으로 적용 가능한지 알아보고자 하였다. 연구 방법은 xFDTD 프로그램을 이용하여 포화 밴드를 사용하지 않은 경우와 기존의 전자파 흡수재 포화 밴드를 사용한 경우, 그리고 전자파 차폐재인 새로운 금속성 메시 포화 밴드를 사용한 경우로 나누어 모의실험 한 후 각각의 결과를 비교평가 하였다. 연구 결과 고주파 필드 맵(RF field map)과 필드 강도(field strength) 모두 포화 밴드를 사용하지 않은 경우나 전자파 흡수재 포화 밴드를 사용한 경우에 비하여 새로운 금속성 메시 포화 밴드를 사용한 경우가 전자파 차폐 능력이 우수한 것으로 나타 났다. 결론적으로 성능을 모의실험 해 봤을 때 새로운 금속성 메시 포화 밴드는 기존 방법들의 문제점을 개선할 수 있어 둘러겹침허상의 제거 방법으로 적용 가능하리라 판단된다.

In this study, the selection action on the mesh in the net pot for whelk (Buccinum opisthoplectum) is experimentally considered, and the selectivity was compared by the SELECT model and the Nashimoto’s method with the probability model according to the contact shape of the mesh and the whelk. The experiments of the mesh size selectivity was conducted for two mesh sizes: 70 mm (inner stretched size 65.4 mm) and 44 mm (inner stretched size 39.5 mm). Selectivity experiments were conducted three times in total for each mesh size used 264 whelks. In addition, Nashimoto’s method analyzed the retention probability using probability model for whether the mesh passed or not based on the carapace width of the whelk. As a result of the selectivity analysis, the 50% selection carapace width for the mesh size of 70 mm was similar to 43.62 mm in the SELECT model and 42.64 mm in the Nashimoto's method. However, the 44 mm mesh with relatively small mesh size showed differences of 40.01 mm and 26.80 mm, respectively. As for the mesh size selectivity of whelk, it was found that the smaller the mesh size, the lower the selectivity. In addition, in the selectivity study on the mesh size of whelk, an evaluation method that closely considers the contact shape between the mesh and the target species is required.

In this study, the analysis of the unsteady viscous flow field using the uRANS equation in a moving mesh was studied. The simulation domain is composed of an overset zone fixed to a propeller and rotating at a constant angular speed and a far zone which is located in the far distance and does not move. Each zone is composed of a polyhedral meshes for the accurate and robust gradient calculation in addition to the reduction of computation time. Simulation technique was applied to the aerodynamic analysis of the 5-inch propeller and compared with those of the MRF and the thrust test. The thrust predicted by the moving mesh showed good correlation with the MRF result within 0.5% difference, but the torque showed a tendency to under-prediction by about 10% compared to the MRF. In the future, we plan to further validate the numerical analysis technique using the moving mesh by applying it to the configurations in which precise test results exist.