• Earthquakes and Structures
• /
• v.24 no.2
• /
• pp.141-153
• /
• 2023

The presented paper considers infill masonry walls' influence on the seismic reliability of precast concrete frames. The recent Bojnord earthquake on May 13th, 2017 in Iran (MW 5.4) illustrated that the infill masonry walls play a crucial role in the damage extent and life safety issues of inhabitants in the precast concrete buildings. The incremental dynamic analysis (IDA) approach was used to determine the fragility curves of the represented damaged precast frame. Then, by integrating site hazard and structural fragilities, the seismic reliability of the represented precast frame was evaluated in different damage limit states. Additionally, the static pushover analysis (SPA) approach was used to assess the seismic performance assessment of the precast frame. Bare and infilled frames were modeled as 2D frames employing the OpenSees software platform. The multi-strut macro-model method was employed for infill masonry simulation. Also, a relatively efficient and straightforward nonlinear model was used to simulate the nonlinear behavior of the precast beam-column joint. The outputs show that consideration of the masonry infilled wall effect in all spans of the structural frame leads to a decrease in the possibility of exceedance of specified damage limit states in the structures. In addition, variation of hazard curves for buildings with and without consideration of infilled walls leads to a decrease in the reliability of the building's frames with masonry infilled walls. Furthermore, the lack of infill walls in the first story significantly affects the precast concrete frame's seismic reliability and performance.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.28-28
• /
• 2022

본 연구는 용담댐유역을 포함한 금강 유역 상류 지역을 대상으로 Sentinel-1 SAR (Synthetic Aperture Radar) 위성영상을 기반으로 한 토양수분 산정을 목적으로 하였다. Sentinel-1 영상은 2019년에 대해 12일 간격으로 수집하였고, 영상의 전처리는 SNAP (SentiNel Application Platform)을 활용하여 기하 보정, 방사 보정 및 Speckle 보정을 수행하여 VH (Vertical transmit-Horizontal receive) 및 VV (Vertical transmit-Vertical receive) 편파 후방산란계수로 변환하였다. 토양수분 산정에는 Water Cloud Model (WCM)이 활용되었으며, 모형의 식생 서술자(Vegetation descriptor)는 RVI (Radar Vegetation Index)와 NDVI (Normalized Difference Vegetation Index)를 활용하였다. RVI는 Sentinel-1 영상의 VH 및 VV 편파자료를 이용해 산정하였으며, NDVI는 동기간에 대해 10일 간격으로 수집된 Sentinel-2 MSI (MultiSpectral Instrument) 위성영상을 활용하여 산정하였다. WCM의 검정 및 보정은 한국수자원공사에서 제공하는 10 cm 깊이의 TDR (Time Domain Reflectometry) 센서에서 실측된 6개 지점의 토양수분 자료를 수집하여 수행하였으며, 매개변수의 최적화는 비선형 최소제곱(Non-linear least square) 및 PSO (Particle Swarm Optimization) 알고리즘을 활용하였다. WCM을 통해 산정된 토양수분은 피어슨 상관계수(Pearson's correlation coefficient)와 평균제곱근오차(Root mean square error)를 활용하여 검증을 수행할 예정이다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2023.05a
• /
• pp.745-747
• /
• 2023

깃허브는 개발자의 명함이라는 말이 있듯, 많은 수의 개발자들이 깃허브를 활용해 자신의 개발 이력과 프로젝트들을 관리한다. 이를 위해 기존의 깃허브 정보 요약 서비스들이 제공되어졌으나, 정보 공유의 불편함과 많은 정보를 담지 못한다는 불편함이 존재했다. 본 논문에서는 이러한 불편함을 해소하기 위해 서버 기반의 깃허브 웹 명함 제작 및 멀티플랫폼에서의 서비스를 기반으로 한 효율적인 개발자 명함 생태계 구축을 제안한다. 본 서비스에서는 Next.js 기술을 활용한 한 명함 제작 및 웹, 앱 클라이언트를 통한 명함 관리 기능을 제공한다. Github oauth를 통해 인증된 정보를 바탕으로 Next.js를 활용해 사용자에 대한 정보를 정해진 형식으로 요약한 명함을 제작한다. 제작된 명함은 웹 / 앱 플랫폼을 기반으로 관리되며, 추가적으로 명함의 공유 및 저장 기능을 수행한다. 이를 통해, 명함 공유를 바탕으로 한 개발자 네트워크 형성을 목표로 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.06a
• /
• pp.213-213
• /
• 2022

본 논문은 슬로싱(Sloshing) 거동에 놓인 극저온 액체수소 화물창의 BOG 예측을 위한 CFD 해석 절차를 다루고 있다. 특히, 적재율(Filling Ratio)에 따라 달라지는 열 유입과 그에 따른 액체수소의 기화 경향을 파악하기 위한 목적으로 수행되었다. 액체수소와 기체수소의 혼재에 의한 다상 열유동(Multiphase-Thermal flow) 특성을 반영하고 유동에 따른 강제 대류 현상을 열유속에 반영하기 위한 CFD 해석을 수행하였다. 다상 유동 모델의 정확성을 검증하기 위하여 슬로싱 실험의 압력 계측 값과 해석의 압력 값 및 자유수면(Free surface) 형상을 비교하였다. 소형 C-Type 독립형 액화수소 탱크를 대상으로 슬로싱 유동과 BOG 발생을 수치적으로 예측하였다. 해석 과정에서 VOF(Volume of fraction) 모델과 Eulerian 모델을 모두 적용하여, 액체수소에 유입되는 열 유속(Heat flux)의 예측 정확성을 비교하였다. 슬로싱 유무에 따라 액체수소에 유입되는 열 유속을 비교하여 슬로싱 유동의 포함 여부에 따른 BOG 발생량의 변화를 제시하였으며, 최종적으로 액체수소의 충전율(Filling ratio) 별로 BOG 발생량의 경향성을 제시하였다.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2023.07a
• /
• pp.251-253
• /
• 2023

본 연구는 spring framework와 각 SNS들의 API를 활용한 각 플랫폼들을 한 사이트에 연동하여 사용자들이 손쉽게 관리하기 위하여 진행하였다. SNS 통합 플랫폼에서의 중요한 요소는 사용자들의 SNS 관리 시간을 단축시키는 것인데 이를 위해 플랫폼들의 게시물들을 한 곳에서 게시, 수정, 삭제 그리고 여러 플랫폼에 게시물을 동시에 업로드하는 기능과 게시물들을 필터링하는 기능을 제공하였다. 이를 통해 사용자의 편의성은 올라가며 더 효율적으로 게시물들을 관리하여 시간을 단축시킬 수 있다.

• Geomechanics and Engineering
• /
• v.35 no.4
• /
• pp.367-383
• /
• 2023

The present paper examines the natural frequency responses of the bi-directional (n_x-n_y, n_y-n_z and n_z-n_x) and multidirectional (n_x-n_y-n_z) functionally graded (FG) plate and curved structures with and without porosity. The even and uneven kind of porosity pattern are considered to observe the influence of porosity type and porosity index. The numerical findings have been obtained using a higher order shear deformation theory (HSDT) based isometric finite element (FE) approach generated in a MATLAB platform. According to the convergence and validation investigation, the proposed HSDT based FE model is adequate to predict free vibrational responses of multidirectional porous FG plates and curved structures. Further a parametric analysis is carried out by taking various design parameters into account. The free vibrational behavior of bidirectional (2D) and multidirectional (3D) perfect-imperfect FGM structure is examined against various power law index, support conditions, aspect, and thickness ratio, and for the curvature of curved structures. The results indicate that the maximum non-dimensional fundamental frequency (NFF) value is observed in perfect FGM plates and curved structures compared to porous FGM plates and curved structures and it is maximum for FGM plates and curved structures with uneven kind of porosity than even porosity.

• Journal of Practical Engineering Education
• /
• v.15 no.2
• /
• pp.331-339
• /
• 2023

In programming classes, there is always a need to efficiently manage programming assignments. This is especially important as class sizes and assignment complexity grows. GitHub and GitHub Classroom makes the management of student assignments much simpler than uploading files and folders to a LMS or shared online drive. Additionally, git and GitHub are industry standard tools, so introducing students these tools in class provides them a good opportunity to start learning about how software is developed in the real-world. This study describes a workflow that uses both GitHub Pages and GitHub Classroom for more efficient classroom and assignment management. The workflow outlined in this study was used in two practical web programming classes in Spring 2023 with 46 third and fourth-year university students. GitHub Pages was used as a classroom website to distribute class announcements, assignments, lecture slides, study guides, and exams. GitHub Classroom was used as a class roster and assignment management platform. The workflow presented in this study is expected to assist other lecturers with the formidable tasks of distributing, collecting, grading, and leaving feedback on multiple students' multi-file programming assignments in practical programming classes.

• Journal of Distribution Science
• /
• v.22 no.4
• /
• pp.91-104
• /
• 2024

Purpose: The study aims to assess the current status of domestic public food delivery apps and analyze the process through which sellers choose between private delivery apps and public delivery apps. This involves exploring strategiesto achieve the original purpose of public food delivery apps, which is to enhance the small business owners income and promote consumer welfare by preventing the monopoly of private food delivery apps. Research design, data and methodology: the research methodology is based on a model that introduces adjustments for non-economic effects, considering the preferences of multi-homing consumers, to more realistically reflect the benefits of sellers' choices. For data analysis, real business performance data from 'Daeguro', 'Meokkaebi', and 'Somunnan Shop' were used. Results: The study revealed that if the market share of public delivery apps within a specific region increases beyond a certain level, the benefits for small-business sellers also increase. This leads to the strategic advantage of simultaneously using both delivery apps. Furthermore, the results exhibit a tendency similar to real social phenomena. Conclusions: This analysis confirmed the role of public food delivery apps in the domestic delivery app market and presents policy recommendations, including application integration and the implementation of exclusive public interest functions, to effectively fulfill this role.

• Journal of Broadcast Engineering
• /
• v.20 no.3
• /
• pp.388-397
• /
• 2015

High Efficiency Video Coding (HEVC)/H.265 is a new video coding standard which is known as high compression ratio compared to the previous standard, Advanced Video Coding (AVC)/H.264. Due to achievement of high efficiency, HEVC sacrifices the time complexity. To apply HEVC to the market applications, one of the key requirements is the fast encoding. To achieve the fast encoding, exploiting thread-level parallelism is widely chosen mechanism since multi-threading is commonly supported based on the multi-core computer architecture. In this paper, we implement both the Tile-level parallelism and the Frame-level parallelism for HEVC encoding on multi-core platform. Based on the implementation, we present two approaches in combining the Tile-level parallelism with Frame-level parallelism. The first approach creates the fixed number of tile per frame while the second approach creates the number of tile per frame adaptively according to the number of frame in parallel and the number of available worker threads. Experimental results show that both improves the parallel scalability compared to the one that use only tile-level parallelism and the second approach achieves good trade-off between parallel scalability and coding efficiency for both Full-HD (1080 x 1920) and 4K UHD (3840 x 2160) sequences.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.35 no.2
• /
• pp.57-63
• /
• 2012

Software release planning model of software product lines was formulated as a precedence-constrained multiple 0-1 knapsack problem. The purpose of the model was to maximize the total profit of an entire set of selected features in a software product line over a multi-release planning horizon. The solution approach is a dynamic programming procedure. Feasible solutions at each stage in dynamic programming are determined by using backward dynamic programming approach while dynamic programming for multi-release planning is forward approach. The pre-processing procedure with a heuristic and reduction algorithm was applied to the single-release problems corresponding to each stage in multi-release dynamic programming in order to reduce the problem size. The heuristic algorithm is used to find a lower bound to the problem. The reduction method makes use of the lower bound to fix a number of variables at either 0 or 1. Then the reduced problem can be solved easily by the dynamic programming approaches. These procedures keep on going until release t = T. A numerical example was developed to show how well the solution procedures in this research works on it. Future work in this area could include the development of a heuristic to obtain lower bounds closer to the optimal solution to the model in this article, as well as computational test of the heuristic algorithm and the exact solution approach developed in this paper. Also, more constraints reflecting the characteristics of software product lines may be added to the model. For instance, other resources such as multiple teams, each developing one product or a platform in a software product line could be added to the model.