• Journal of Korean Association for Spatial Structures
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• v.7 no.2 s.24
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• pp.63-74
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• 2007

Large spatial structures consist of roof structure and its supporting structure. Authors simply call the supporting structure "lower parts" and roof structure "upper parts". To study the influence of an lower part on the seismic response of the upper part of a structure as a first step, authors substitute the upper part and the lower part of the structure to a single degree of freedom system individually, and set up a new 2 DOF structural model connected by them. It is clarified that the mass ratio and the period ratio of an upper part to a lower part are important parameters to find the amplification or reduction of the seismic response of an upper part.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.65-74
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• 2021

In order to efficiently inspect rapidly increasing old tunnels in many well-developed countries, many inspection methodologies have been proposed using imaging equipment and image processing. However, most of the existing methodologies evaluated their performance on a clean concrete surface with a limited area where other objects do not exist. Therefore, this paper proposes a 6-step framework for tunnel crack detection deep learning model development. The proposed method is mainly based on negative sample (non-crack object) training and Cascade Mask R-CNN. The proposed framework consists of six steps: searching for cracks in images captured from real tunnels, labeling cracks in pixel level, training a deep learning model, collecting non-crack objects, retraining the deep learning model with the collected non-crack objects, and constructing final training dataset. To implement the proposed framework, Cascade Mask R-CNN, an instance segmentation model, was trained with 1561 general crack images and 206 non-crack images. In order to examine the applicability of the trained model to the real-world tunnel crack detection, field testing is conducted on tunnel spans with a length of about 200m where electric wires and lights are prevalent. In the experimental result, the trained model showed 99% precision and 92% recall, which shows the excellent field applicability of the proposed framework.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.951-952
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• 2023

소위 '인생네컷'이라 불리는 셀프사진관은 MZ 세대의 새로운 놀이 문화로 떠오르며 사용자 수가 나날이 증가하고 있다. 그러나 짧은 시간 내에 다양한 포즈를 취해야 하는 셀프사진관 특성상 촬영이 낯선 사람에게는 여전히 진입장벽이 존재한다. 더불어 매번 비슷한 포즈와 사진 결과물에 기존 사용자는 점차 흥미를 잃어가는 문제점도 발생하고 있다. 이에 본 연구에서는 셀프사진관 사용자의 관계를 분류하는 모델을 개발하여 관계에 따른 적합하고 다양한 포즈를 추천하는 프레임워크를 제안한다. 사용자의 관계를 'couple', 'family', 'female_friend', 'female_solo', 'male_friend', 'male_solo' 총 6 개로 구분하였고 실제 현장과 유사하도록 단색 배경의 이미지를 우선으로 학습 데이터를 수집하여 모델의 성능을 높였다. 모델 학습 단계에서는 모델의 성능을 높이기 위해 여러 CNN 기반의 모델을 전이학습하여 각각의 정확도를 비교하였다. 결과적으로 195 장의 test_set 에서 accuracy 0.91 의 성능 평가를 얻었다. 본 연구는 객체 인식보다 객체 간의 관계를 학습시켜 관계성을 추론하고자 하는 것을 목적으로, 연구 결과가 희박한 관계 분류에 대한 주제를 직접 연구하여 추후의 방향성이나 방법론과 같은 초석을 제안할 수 있다. 또한 관계 분류 모델을 CCTV 에 활용하여 미아 방지 혹은 추적과 구조 등에 활용하여 국가 치안을 한층 높이는 데 기대할 수 있다.

• Journal of the Korea Institute of Building Construction
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• v.22 no.5
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• pp.519-530
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• 2022

As online commerce increases, the construction of large logistics buildings worldwide is exploding. Most of these buildings have the characteristics of long span and heavy loaded and use precast concrete components, a pin joint structure, for rapid construction. However, due to construction safety and structural stability requirements, the pin joint structure has many limitations in terms of the erection of the PC member, which increases the time and cost. A structural frame connected with steel joints between precast concrete components, called a SMART frame, has been developed, which addresses these constraints and risks. However, the effect of the appllication of a SMART frame on the time aspect has not been analysed. The study is a time reduction effect analysis of a SMART frame for long span and heavy loaded logistics buildings. For this study, the authors select a case site erected using existing PC components, and compare the time reduction with the SMART frame erection simulations. Through this analysis, it was found that a time reduciton about 4 months, approximately 48% of the conventional PC installation period could be achieved. If the SMART frame is applied when carrying out future large-scale logistics building projects, it can be expected to have the effect of significantly shortening the construction period compared to the conventional method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.1
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• pp.21-28
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• 2021

The main purpose of this study is to assess the safety of the fixed anchorages subjected to the seismic motion for an operating facilities in the actual power plant. Thus, the experimental study was conducted to investigate the load response in the event of an actual seismic to the anchorages of a nonstructural components. Since there are economic and spatial constraints to study nonstructural components that actually have various forms, alternative test specimens of steel frames with mass were built and the shaking table test was carried out. In order to evaluate the dynamic characteristics and seismic performance, the natural frequency of the target structure was identified through the shaking table test and then the load response characteristics of the anchorage were evaluated by generating an artificial seismic effect like actual seismic. Finally, the structural stiffness was reinforced by fixing the steel frame to the test specimen using bolts, thereby reducing the load transmitted to the anchorage. It will be carried out on the reliability verification of the experiments and areas that have not been carried out due to the site conditions through the analytical approach in the future.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.111-118
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• 2011

Single-layer latticed domes with rigid-joint have an advantage in the construction cost and the aesthetic. But, in single-layer latticed domes, the joints are hard to discriminate between pin-joint and rigid-joint, and consisted of semi-rigid joint in practical. And the erection of large roof structures requires special techniques. As one of these special techniques is the Step-Up erection method. This paper verified buckling characteristics of single-Layer lamella domes according to the Joint flexibility under construction by Step-up method. The results are follows: As erection steps increase, the buckling strength decreases. It is occurred the joint buckling by snap through on the top of dome when the joint flexibility close the rigid. And large tensile stress distribution appeared in circumferential member of bottom boundary when the step of construction is low. As the step of construction increase, large compressive stress distribution showed in the top of dome.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.271-280
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• 2011

This study intends to analytically evaluate the vibration serviceability of the bridges for each long-span type having the same span length and road width using the Meister vibration sensation curve. With MIDAS, a structural analysis program, bridges were modeled using the girders as the frame element and slabs as the plate element. The transient analysis was performed using the moving loads of the design vehicles. This study presents the analytical process of reviewing the vibration serviceability during the design of long-span bridges. It involves the comparison of the vibration serviceability of different bridge types by applying the lagging-behind and acceleration amplitude from transient analysis to Meister curve. The result confirms that the process is appropriate.

• Journal of the Korea Society for Simulation
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• v.20 no.4
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• pp.97-104
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• 2011

Defense M&S software industry has carried out a variety of studies related to an efficient implementation of large-scale simulation and interoperability with respect to each of the system and HLA has been developed to provide a common architecture for distributed simulation of them. HLA defines Federate interface specification and provides services through RTI. Meanwhile, the difficulty lies in developing the software based HLA. Federate developer needs to understand how to handle Metadata produced RTI and has to modify the interface code whenever FDD is modified. This paper presents the implementation method of SOM interface using the code generation technique and middleware architecture for providing simple API. It solves the problem for implementing the framework of distributed object communication by using proposed method.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.307-312
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• 2015

The passenger boarding bridge which provides a safe and comfort passenger pathway between an airplane and airport terminal gate is one of the apron equipment. This study investigates the effect of the lift column layout design on structural strength of the passenger boarding bridge by using finite element method, comparing deflection and stress. The overlapped zone of the tunnel frame A and B occurred at the maximum stress. The results of this research show that the lift column layout design is closely the value of the maximum stress.

• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.59-66
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• 2001

This paper describes three modules for development of the Space Frame Integrated Design System(SFIDS). The Control Module is implemented to control the developed system. The Model Generation Module based on PATRAN user interface enables users to generate a complicated finite element model for space frame structures. The Optimum Design Module base on a branch of combinatorial optimization techniques which can realize the optimization of a structure having a large number of members designs optimum members of a space frame after evaluating analysis results. The Control Module and the Model Generation Module Is implemented by PATRAN Command Language(PCL) while C++ language is used in the Optimum Design Module. The core of the system is PATRAN database, in which the Model Generation Module creates information of a finite element model. Then, PATRAN creates Input files needed for the analysis program from the information of the finite element model in the database, and in turn, imports output results of analysis program to the database. Finally, the Optimum Design Module processes member grouping of a space frame based on the output results, and performs optimal member selection of a space frame. This process is repeated until the desired optimum structural members are obtained.