• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.323-323
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• 2016

최근 강우강도 등의 기후변화로 인한 표토침식량이 증가하고 있고, 이에 따른 사회적 환경적 문제가 부각되고 있다. 특히 표토는 인류에게 식량생산의 기반이 되고, 정주공간을 제공할 뿐만 아니라 에너지 생산, 수자원 함양, 기후변화 대응, 생물 다양성 유지, 생태계의 건전성, 자원함양 및 순환, 오염물질 정화 등 소중한 생명자원이다. 이에 환경부에서는 2012월 12월 표토의 침식현황에 관한 고시를 제정하고, 표토 유실 대책 방안을 수립하기 위한 노력을 기울이고 있다. 이에 자원으로서의 표토를 보전하기 위한 단기적 관점의 대책 수립을 위한 웹GIS 기반 단일 강우에 의한 표토침식량을 예측하는 시스템을 개발하였다. 본 연구는 크게 표토침식 예측 모듈 개발과 정확성 평가를 위한 시험포 단위 모니터링 그리고 모듈을 적용한 웹GIS 시스템 개발, 시범적용을 위한 강원도 홍천군 자운리 DB 구축으로 구분된다. 표토침식예측 모듈의 정확성을 검증하기 위하여 가로 4m ${\times}$ 세로 22m, 경사도 3%, 9% 시험포 2개를 조성, 2015년 5월 11일부터 2015년 11월 23일까지 강우량, 유출량, 표토침식량을 조사하였으며, 웹 GIS 시스템은 Open Source Software인 Geoserver, PostGIS, OpenLayers를 활용하여 개발하였다. 마지막으로 개발된 웹GIS 표토침식예측시스템의 시범적용을 위하여 강원도 홍천군 자운리의 농경지 경계, 경사도, 경사장, 작물특성 등에 대한 GIS DB를 구축하였다. 시험포 모니터링 결과 강우발생일수는 총 64일로 관측되었고, 이중 유출은 총 30회가 발생되었다. 이 결과를 활용하여 표토침식 예측 모듈을 검증한 결과 3 % 시험포의 유출량 NSE : 0.88, $R^2$ : 0.91, 표토침식량 NSE : 0.87, $R^2$ : 0.90, 9 % 시험포의 유출량 NSE : 0.76, $R^2$ : 0.82, 표토 침식량 NSE : 0.82, $R^2$ : 0.88로 나타났다. 웹GIS 표토침식 예측 시스템은 Layer 정보, 맵, GIS tool, 경작기 정보, 날씨 정보 등으로 구성되어 있으며, 기상청 Open API와 연동하여 당일의 강수량 예보 데이터와 표토침식량 산정 모듈을 이용하여 예측 표토 침식량 데이터를 제공한다. 하루가 지나면 기상청에서 실측한 강수량 데이터를 이용하여 표토 침식량 산정모듈이 자동적으로 수행된 뒤 실측 강우량에 대한 표토침식량 정보가 제공된다 본 연구에서 개발된 웹GIS기반 표토침식 예측 시스템은 시범 대상 유역인 강원도 홍천군 자운리 유역을 대상으로 구축되었으며, 지속적으로 대상유역을 확대할 계획이다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.6
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• pp.253-262
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• 2018

Oscillating Water Column (OWC) Wave Energy Converters (WEC) harness electricity through a Power-Take-Off (PTO) system from the induced-airflow by seawater oscillating inside a chamber. In general, an air chamber with a relatively small cross-sectional area is required compared to seawater chamber to obtain high-velocity air in the PTO system, and in order to simulate an accurate air flow rate in the air chamber, a three-dimensional study is required. In this study, the dynamic response of OWC-WEC that is equipped with the channel of seawater exchange for the case of irregular waves has been numerically studied. The open source CFD software, OLAFLOW for the simulation of wave dynamics to the openFOAM and FOAM-extend communities, was used to simulate the interaction between the device and irregular waves. Based on the numerical simulation results, we discussed the fluctuation characteristics of three dimensional air flow in the air-chamber, wave deformation around the structure and the seawater flow inside the channel of seawater exchange. The numerical results the maximum air flow velocity in the air-chamber increases as the Ursell value of the significant wave increases, and the velocity of airflow flowing out from the inside of air chamber to the outside is greater than the speed of flowing into the air chamber from the outside.

• Journal of Korea Entertainment Industry Association
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• v.15 no.4
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• pp.15-29
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• 2021

Many countries and companies are pursuing and developing Artificial intelligence as it is the core technology of the 4th industrial revolution. Global IT companies such as Apple, Microsoft, Amazon, Google and Samsung have all released their own AI assistant hardware products, hoping to increase customer loyalty and capture market share. Competition within the industry for AI agent is intense. AI assistant products that command the biggest market shares and customer loyalty have a higher chance of becoming the industry standard. This study analyzed the current status of major overseas and domestic IT companies in the field of artificial intelligence, and suggested future strategic directions for voice UI technology development and user satisfaction. In terms of B2B technology, it is recommended that IT companies use cloud computing to store big data, innovative artificial intelligence technologies and natural language technologies. Offering voice recognition technologies on the cloud enables smaller companies to take advantage of such technologies at considerably less expense. Companies also consider using GPT-3(Generative Pre-trained Transformer 3) an open source artificial intelligence language processing software that can generate very natural human-like interactions and high levels of user satisfaction. There is a need to increase usefulness and usability to enhance user satisfaction. This study has practical and theoretical implications for industry and academia.

• Journal of the Korea Society of Computer and Information
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• v.25 no.9
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• pp.91-100
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• 2020

This paper presents an evaluation framework for prototyping multimedia streaming services including audio and video in a distributed and/or decentralized storage that can evaluate service quality and performance under various network conditions. The evaluation framework focuses on important indicators which measure and improve service quality by applying decentralized storage to multimedia streaming services that can mimic the scalability of the existing server-client software architecture and the issue of a single point of failure. The integrated framework not only measures performance indicators for evaluating the quality and performance of multimedia streaming on open source based multimedia content streaming services, but also adjusts network quality using network virtualization technology for comprehensive evaluations. The experimental results show that the integrated framework has low overhead in building and operating a decentralized storage with multimedia streaming services on a single host computer which validates the scalability of the developed framework.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.345-358
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• 2018

The high altitude scientific balloon has been used for decades in advanced aerospace countries such as United States, France, and Japan to carry out various research objectives. Since the initial cost for development and operation is enormous, it has been conducted by national research institutes. Recently, the advent of open source software/hardware ecosystems with low-cost yet high-performance have lowered barriers to enter into scientific balloon research and development. In this study, a zero pressure balloon prototype was designed considering the cost, usability, compatibility, and development period by using commercial off the shelf (COTS) items. In addition, the flight operation experience was accumulated through eight times of the flight tests, and operational reliability of the balloon system was verified. Finally, the foundation for the operation of the large zero pressure balloon was established.

• Journal of The Korean Association of Information Education
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• v.20 no.3
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• pp.235-242
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• 2016

Physical computing is utilizing principles of computing in the process of expressing one's ideas creatively and implementing them into tangible objects by combining hardware and software. Recent deployment of open source hardware and 3D printers increased the accessibility of physical computing. However, incorporating these into educational practices requires teachers' interest and competencies. This study aims to share the perceived opportunities of developing physical computing based lessons and challenges from teachers' experiences while primary teachers participated in learning fundamentals of physical computing and developing lessons. The findings of this study provide implications to the teachers who are interested in adopting physical computing into classes and in designing teacher training programs.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1239-1243
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• 2010

The web environment is evolving rapidly. Testing in the web based software is an essential process to improve stability and productivity. Testing of complex web contents and ill(user interface) is most important thing. Implemented test cases are efficient when they are automated and reusable. But, most of the testing automation tools are focused on technical accessibility and functions still. A collaboration of the persons concerned and reusability of implemented test case are ignored. In this paper we propose an efficient way to design automated test case in web environment, and to share and pattern automated test cases we introduce testing framework called NTAF(NHN Test Automation Framework.). The NTAF is based on open source framework. It provides integrated testing environment that web testing cane be automated and managed continuously.

• Journal of KIISE
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• v.44 no.10
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• pp.1034-1044
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• 2017

Although traversal strategies are important for the performance of model checking, many studies have ignored the impact of traversal strategies in model checking with a block-encoded abstract reachability graph. Studies have considered traversal strategies only for an abstract reachability graph without block-encoding. Block encoding plays a crucial role in the model checking performance. This paper therefore describes Dual-traversal strategy, a simple and novel technique to control traversal strategies in a block-encoded abstract reachability graph. This method uses two traversal strategies for a model checking, one for effective block-encoding, and the other for traversal in an encoded abstract reachability graph. Dual-traversal strategy is very simple and can be implemented without overhead compared to the existing single-traversal strategy. We implemented the Dual-traversal strategy in an open source model checking tool and compare the performances of different traversal strategies. The results show that the model checking performance varies from the traversal strategies for the encoded abstract reachability graph.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.7
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• pp.329-336
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• 2017

As web apps have evolved faster and become more complex, their validation and verification have become essential for their development and maintenance. Efficient validation and verification require understanding of how web components collaborate with each other to meet user requests. Thus, this paper proposes a new approach to automatically extracting such collaboration when a user issues a request for a new page. The approach is dynamic and less sensitive to web development languages and technologies, compared to static extraction approaches. It considers an orignal web app as a black-box and does not change the app's behavior. The empirical evaluation shows that our approach can be applicable to extract component collaboration and understand the behavior of open source web apps.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.72-77
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• 2017

In recent years, internet of things (IoT) technology has developed rapidly and has been applied in many fields. IoT devices collect and analyze information in various environments and provide useful information to users. Due to the recent increase in IoT devices, many open source platforms based on hardware and software that are cheap and easy to use have been developed and provided. In this paper, we have studied the IoT system based on Arduino which can communicate Bluetooth wireless data with smart phone in real time. And we have developed a wireless system control app based on App Invertor 2 for communication with Android smart phone. Also, we propose an IoT system based on Arduino which can control the devices and implement the function of connectivity between devices.