• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.61-61
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• 2021

온도 성층화는 많은 저수지와 댐에서 흔히 발생하는 현상으로 호수나 저수지의 표면 온도가 바닥보다 상대적으로 높아 깊이에 따른 열 구배를 나타낸다. 이러한 온도 성층화 현상은 여름철과 같이 상부와 하부의 온도 차가 클수록 안정적이게 나타나며 이러한 층화 현상으로 수직 확산이 제어되어 수질에 영향을 미친다고 알려져 있다. 따라서 댐이나 호수 등 층화 현상이 심한 유체 내부 바닥에 물순환장치를 설치하여 외부로부터 공기를 끌어와 하부에서 공기를 분출하여 온도 성층을 약화시키기도 한다. 물순환 장치를 설비하면 수체의 혼합이 용이해지며 물질전달이 개선되어 수질이 향상된다. 국내의 경우 대청댐, 보령댐, 영주 댐 등 많은 국내 댐 내부에 물순환장치가 설비되어있다. 본 연구에서 댐의 물순환장치의 성능을 파악하기 위해 산기식 물순환 장비가 설치되어있는 영주댐을 연구 대상 지역으로 잡았다. 연구지역의 계절별 성층구조 및 특성을 조사하기 위해, 봄, 여름, 가을 영주댐에 방문하여 관측 자료를 취득하였으며 물순환 장치는 봄철의 경우만 가동하였다. 봄철의 물순환 장치 가동 전후 관측 데이터를 바탕으로 수치모형실험을 실행하여 관측 결과와 비교 및 검증하였다. 이를 바탕으로 여름, 가을에 물순환장치를 가동하였을 경우 댐 내부 수체의 혼합과정을 살펴보는 연구를 진행하였다. 본 연구는 CFD (Computational Fluid Dynamic) 시뮬레이션을 수행하기 위해 오픈 소스 소프트웨어 OpenFOAM(version 4.0)에서 열 전달이 포함되어있는 비압축성 VOF 솔버를 사용하였다. 본 솔버는 물과 공기를 동시에 나타낼 수 있으며 온도의 확산 방정식을 포함하고 있다. 또한 유동해석 수행 시 사용한 물순환장치의 효울은 실제 장치의 효율과 동일하다. 본 연구의 목표는 다음과 같다. (1) 관측만으로 파악하기 어려운 수체의 혼합거동을 유동해석 자료를 통해 면밀히 살펴보고 (2) 봄철 물순환 장치가 작동하기 전후 자료를 바탕으로 여름 및 가을철 물순환장치 가동 전후 데이터를 유동해석 자료로 취득한다. (3) 또한 물순환장치 가동 전후 데이터를 통해 계절별 혼합 효율을 취득한다.

• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.21-26
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• 2024

The one of the famous deep learning models for object detection task is you only look once version 5 (YOLOv5) framework based on the one stage architecture. In addition, YOLOv5 model indicated high performance for accurate lesion detection using the bottleneck CSP layer and skip connection function. The purpose of this study was to evaluate the performance of YOLOv5 framework according to various hyperparameters in position emission tomogrpahy (PET) phantom images. The dataset was obtained from QIN PET segmentation challenge in 500 slices. We set the bounding box to generate ground truth dataset using labelImg software. The hyperparameters for network train were applied by changing optimization function (SDG, Adam, and AdamW), activation function (SiLU, LeakyRelu, Mish, and Hardwish), and YOLOv5 model size (nano, small, large, and xlarge). The intersection over union (IOU) method was used for performance evaluation. As a results, the condition of outstanding performance is to apply AdamW, Hardwish, and nano size for optimization function, activation function and model version, respectively. In conclusion, we confirmed the usefulness of YOLOv5 network for object detection performance in nuclear medicine images.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.691-702
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• 2019

Flood inundation map has various important roles in terms of municipal planning, timely dam operation, economic levee design, and building flood forecasting systems. Considering that the riparian areas adjacent to national rivers with high potential flood vulnerability conventionally imposed special cares to justify applications of recently available two- or three-dimensional flood inundation numerical models on top of digital elevation models of dense spatial resolution such as LiDAR irrespective of their high costs. On the contrary, local streams usually could not have benefits from recent technological advances, instead they inevitably have relied upon time-consuming manual drawings or have accepted DEMs with poor resolutions or inaccurate 1D numerical models for producing inundation maps due mainly to limited budgets and suitable techniques. In order to efficiently and cost-effectively provide a series of flood inundation maps dedicatedly for the local streams, this study proposed an OpenGIS-based flood mapping tool named Open Flood Mapper (OFM). The spatial accuracy of flood inundation map derived from the OFM was validated throughout comparison with an inundation trace map acquired after typhoon Nari in Hancheon basin located in Jeju Island. Also, a series of inundation maps from the OFM were comprehensively investigated to track the burst of flood in the extreme flood events.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.361-366
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• 2017

As the recent development of computing architecture and application software technology, real world simulation, which is the ultimate destination of computer simulation, is emerging as a practical issue in several research sectors. In this paper, metal plate motion in a square shock tube for small time interval was calculated using a supercomputing-based fluid-structure-combustion multi-physics simulation tool called Illinois Rocstar, developed in a US national R amp; D program at the University of Illinois. Afterwards, the simulation results were compared with those from experiments. The coupled solvers for unsteady compressible fluid dynamics and for structural analysis were based on the finite volume structured grid system and the large deformation linear elastic model, respectively. In addition, a strong correlation between calculation and experiment was shown, probably because of the predictor-corrector time-integration scheme framework. In the future, additional validation studies and code improvements for higher accuracy will be conducted to obtain a reliable open-source software research tool.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.7
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• pp.319-326
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• 2016

Given the attributes of mobile apps that shorten the time to make purchase decisions while enabling easy purchase cancellations, usability can be regarded to be a highly prioritized quality attribute among the diverse quality attributes that must be provided by mobile apps. With that backdrop, mobile app developers have been making great effort to minimize usability hampering elements that degrade the merchantability of apps in many ways. Most elements that hamper the convenience in use of mobile apps stem from those potential errors that occur when GUIs are designed. In our previous study, we have proposed a technique to analyze the usability of mobile apps using user behavior logs. We proposes a technique to detect usability hampering elements lying dormant in mobile apps' GUI models by expressing user behavior logs with finite state models, combining user behavior models extracted from multiple users, and comparing the combined user behavior model with the expected behavior model on which the designer's intention is reflected. In addition, to reduce the burden of the repeated test operations that have been conducted by existing developers to detect usability errors, the present paper also proposes a mobile usability error detection automation tool that enables automatic application of the proposed technique. The utility of the proposed technique and tool is being discussed through comparison between the GUI issue reports presented by actual open source app developers and the symptoms detected by the proposed technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.211-218
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• 2014

Recently, software-based programmable logic controller (PLC) systems, which are implemented in standard PLC languages on general hardware, are gaining popularity because they overcome the limitations of classical hardware PLC systems. Another noticeable trend is that the use of integrated development environment (IDE) is becoming important. IDEs can help developers to easily manage the growing complexity of modern control systems. Furthermore, industrial Ethernet, e.g. EtherCAT, is becoming widely accepted as a replacement for conventional fieldbuses in the distributed control domain because it offers favorable features such as short transmission delay, high bandwidth, and low cost. In this paper, we implemented the extension of open source IDE, called Beremiz, for developing EtherCAT-based real-time, synchronized motion control applications. We validated the EtherCAT system management features and the real-time responsiveness of the control function by using commercial EtherCAT drives and evaluation boards.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.291-299
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• 2010

As recent advances in science, technology and performance requirements of the weapons system are getting highly diversified and complex, the performance requirements also get stringent and strict. Moreover, the weapons system should be intimately connected with other systems such as watchdog system, command and control system, C4I system, etc. However, a tremendous amount of time, cost and risk being spent to acquire new weapons system, and not being diminished compared to the rapid pace of its development speed. Defense Modeling and Simulation(M&S) comes into the spotlight as an alternative to overcoming these difficulties as well as constraints. In this paper, we propose the development process of virtual test framework based on the synthetic environment as a tool to analyze the effectiveness of the weapons system of underwater engagement model. To prove the proposed concept, we develop the test-bed of virtual test using Delta3D simulation engine, which is open source S/W. We also design the High Level Architecture and Real-time Infrastructure(HLA/RTI) based Federation for the interoperation with heterogeneous simulators. The significance of the study entails (1)the rapid and easy development of simulation tools that are customized for the Korean Theater of War; (2)the federation of environmental entities and the moving equations of the combat entities to manifest a realistic simulation.

• The Korean Journal of Archival Studies
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• no.42
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• pp.135-183
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• 2014

Korea has a high standard of IT environment to serve exhibit programs through the web with internet propagation and IT technology. However, the web exhibition of public institutions not only seem to introduce off-line exhibitions but also not to invigorate. It is caused by the lack of awareness, the cost of system installation and the lack of professional manpower. In this situation, OMEKA could suggest practical solutions to archives where need their own exhibition through the web. Especially, it would helpful for small record management organizations which are not enough budget and personal. OMEKA is an open source software program for digital collection and contents management. It has an affinity with users unlike traditional archives service programs. It also has been variously used by libraries, museums and schools because of exceptional exhibit functions. In this article, we introduce to the installation of a practical use about OMEKA. Regarding to OMEKA features, we consider it to raise exhibit effects. OMEKA would reduce the cost related to plans of exhibitions because it could display various contents and programs which reflecting characteristics of institutions. In addition, the availability of installation and widespread technological environment would lessen burden of public institutions. Using OMEKA, they would improve service level of public institutions and, make users satisfy. Therefore, they can change the social recognition of public institutions. OMEKA can contribute to various exercises of public records. It is not just the stereotypical system but, serves exhibition and collections with the strategy which each public institution would like to display. After all, it not only to connect to users with producers but also to improve the public image of institutions positively. Then, OMEKA would bring the great result through this interaction between public institutions and users.

• The Korean Journal of Archival Studies
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• no.71
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• pp.49-89
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• 2022

This study suggests the necessity and domestic application plan a national authority database that promotes an integrated access, richer search, and understanding of historical information sources and archival resources distributed among cultural heritage institutions through the "Social Networks and Archive Context" project case. As the SNAC project was transformed into an international cooperative organization led by NARA, it was possible to secure a sustainable operating system and realize cooperative authority control. In addition, SNAC authority records have the characteristics of providing richer contextual information about life and history and social and intellectual network information compared to libraries. Through case analysis, First, like SNAC, a cooperative body led by the National Archives and having joint ownership of the National Library of Korea should lead the development and expand the scope of participating institutions. Second, in the cooperative method, take a structure in which divisions are made for each field with special strengths, but the main decision-making is made through the administrative team in which the two organizations participate. Third, development of scalable open source software that can collect technical information in various formats when constructing authority data, designing with the structure and elements of archival authority records, designing functions to control the quality of authority records, and building user-friendly interfaces and the need for a platform design reflecting content elements.

• Journal of health informatics and statistics
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• v.43 no.4
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• pp.307-317
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• 2018

Objectives: This study aimed to verify the effectiveness of Internet-based intervention programs for adults with diabetes by conducting a meta-analysis of studies conducted since 2000. Methods: We conducted a systematic review of research papers published in domestic and overseas journals from January 2000 to December 2015, and selected 9 papers that met the analysis criteria. Data analysis was performed using the open source statistical software R 3.5.0, to analyze the effectiveness of Internet-based interventions on experimental and control groups. Results: The analysis showed that intervention programs for controlling HbA1c levels in adult patients with diabetes most commonly comprised 7 sessions on Internet-based management (77.8%), and the most common frequency of application of intervention programs was 4 session in 6 months (33.4%). The present meta-analysis revealed statistically significant effects of Internet-based intervention activities (SMD = 0.92, 95% CI 0.45-1.40). The analysis of the effect size according to the intervention period showed that the 3-month, 6-month, and 12-month interventions reported in eight studies (89%) had a high effect on the Internet-based intervention group. Conclusions: The results of this study confirm the effectiveness of Internet-based intervention programs for adult patients with diabetes. The need for research on the utilization of Internet-based intervention programs for the steady management of diabetes, a chronic disease; for the development of specific guidelines for intervention activities; and for establishing appropriate protocols are acknowledged.