• 한국해양공학회지
• /
• 제34권5호
• /
• pp.351-360
• /
• 2020

Of late, demand for test sites for marine equipment such as ASV, AUV, ROV, and various underwater sensors is increasing. The authors have focused on an oscillating water column (OWC), which is being constructed near Chagwido Island Jeju, as one of the test-sites. The main objective of the OWC is to produce wave energy and develop technologies. It has been built in the sea approximately 1 km off the coast. It has berth accommodation and some rooms that can be used as laboratories. To investigate the feasibility of its usage as a test site for marine equipment, we acquired bathymetric data around the OWC by using a multi-beam echo sounder and a single-beam scanning sonar. The accessibility of the OWC from nearby ports and the use of support vessels or ships were also investigated. 3D point cloud data from the multi-beam echo sounder and 2D acoustic images from the scanning sonar are expected to be used as references for identifying changes over time. In addition, through these experiments, we derived a procedure to use this facility as a test site by using the IDEF0 functional modelling method. Based on this preliminary investigation and previously reported examples, we determined the general conditions and preferences for evaluating the performance of various marine equipment heuristically. Finally, we developed five applications that were derived from this investigation.

• 대기
• /
• 제31권4호
• /
• pp.421-431
• /
• 2021

The Yeongdong region is frequently vulnerable to heavy snowfall in winter in terms of societal and economical damages. By virtue of a lot of previous efforts, snowfall forecast has been significantly improved, but the performance of light snowfall forecast is still poor since it is very conducive to synoptic and mesoscale interactions, largely attributable to Taeback mountains and East Sea effects. An intensive observation has been made in cooperation with Gangwon Regional Meteorological Office and National Institute of Meteorological Studies in winter seasons since 2019. Two distinctive Cold Air Damming (CAD) events (14 February 2019 and 6 February 2020) were observed for two years when the snowfall forecast was wrong specifically in its location and timing. For two CAD events, lower-level temperature below 2 km ranged to lowest limit in comparisons to those of the previous 6-years (2014~2019) rawinsonde soundings, along with the stronger inversion strength (> 2.0℃) and thicker inversion depth (> 700 m). Further, the northwesterly was predominant within the CAD layer, whereas the weak easterly wind was exhibited above the CAD layer. For the CAD events, strong cold air accumulation along the east side of Taeback Mountains appeared to prevent snow cloud and convergence zone from penetrating into the Yeongdong region. We need to investigate the influence of CAD on snowfall in the Yeongdong region using continuous intensive observation and modeling studies altogether. In addition, the effect of synoptic and mesoscale interactions on snowfall, such as nighttime drainage wind and land breeze, should be also examined.

• 농촌지도와개발
• /
• 제27권4호
• /
• pp.173-184
• /
• 2020

Is the Fourth Industrial Revolution a revolution for cities only? Through the Fourth Industrial Revolution, Korea has entered quickly in the influence area of intelligent information technology such as IoT, AI, Big data, Cloud, ICT, Digital twin. However, as the information gap between the rural zone and the urban zone worsens, a policy was needed to reduce such a gap. Therefore, this research analyzed EU's smart village project, and investigated the problem and improvement of the actual smart village through the interview and field study with the person in charge of the actual smart village project in Korea. Based on the analytic result, 5 plans were deduced to improve Korea's smart village project. First, make the realistic adjustment of project period to assure the sustainability of smart village; second, make the new establishment of the department in charge of smart village project; third, construct the system of integrating and cooperating the policy that can embrace all the rural zone and the urban zone; the fourth, expand the application area of customized ICT technology according to the new rural policy environment; and finally introduce the residents' capacity development project through the rural guidance project.

• KNOM Review
• /
• 제21권2호
• /
• pp.26-34
• /
• 2018

클라우드 컴퓨팅 및 서비스의 확산으로 인터넷 트래픽과 서비스 품질 향상에 대한 요구가 증가하면서 데이터 센터 내부 서버의 리소스를 보다 효율적으로 사용하는 서버 가상화와 네트워크 가상화 기술에 대한 관심이 증가하고 있다. 트래픽 모니터링을 위해 패킷을 복제하는 기존의 하드웨어 TAP (Test Access Port) 장비는 서버 가상화 환경에서 구성된 가상 데이터 경로 (datapath)에 적합하지 않기 때문에 하드웨어 TAP 장비를 소프트웨어로 구현한 Virtual TAP (vTAP)을 통해 가상 스위치에서 패킷을 복제한다. 그러나 가상 스위치에서 vTAP을 구현하면 호스트 머신의 컴퓨팅 리소스를 가상 스위치 및 가상 머신과 공유하기 때문에 성능 저하 문제가 발생한다. 이 문제를 극복하기 위해 고속 패킷 처리 기술인 eBPF (Extended Berkeley Packet Filter) 기반의 vTAP 구현 기술을 제안하고 기존 방법과 성능을 비교한다.

• 정보교육학회논문지
• /
• 제23권4호
• /
• pp.293-302
• /
• 2019

본 연구에서는 데이터 시각화에 초점을 맞춘 구글 스프레드시트 교육 프로그램을 개발하여 초등학교 4 5학년 학생을 대상으로 적용한 후 그 효과를 검증하였다. 개발한 교육프로그램으로 초등학교 4 5학년 학생 29명에게 총 6일 동안 36시간의 수업을 진행하였다. 교육 프로그램의 적용 결과 창의성에 미치는 효과에 대한 검증을 위하여 Torrance의 TTCT(Torrance Tests of Creative Thinking) 검사지 도형 A, B형을 투입하여 사전 사후 검사를 실시하였다. 검증 결과 데이터 시각화 교육에 초점을 맞춘 구글 스프레드시트 교육 프로그램은 초등학교 4 5학년 학생들의 창의력 요소들에 긍정적인 영향을 미친다는 것을 알 수 있었다.

• 천문학회보
• /
• 제44권1호
• /
• pp.63.3-63.3
• /
• 2019

Active asteroids are celestial bodies that distinctively have asteroid-like orbital elements but show comet-like activity. They exhibit the activities due to the sublimation of volatile ices, impacts with small objects or break-up by rapid rotations. As of 2019 February, 30 active asteroids are detected in the outer main belt (i.e., the semimajor axes a>2.5 au) while only 3 of them in the inner main belt (a<2.5 au), suggesting that sublimation of remaining icy volatiles can be one of the most fundamental mechanisms for the activities. A sudden activity of (6478) Gault was reported in early 2019. The asteroid was discovered in 1988 and has exhibited its inactive appearance until the end of last year. Soon after the report, we have conducted imaging observations using the Seoul National University Observatory 1.0-m telescope and the Korea Microlensing Telescope Network (KMTNet) to monitor the activity. The observed images showed a primary dust tail that consists of dust grains ejected early November in 2018. Later, another tail developed, indicating further dust ejection occurred around late December 2018. Our model simulation to reproduce the morphology of the dust cloud suggests that the slightly-curved primary dust tail results from a continuous dust ejection over weeks. The total mass of ejecta was estimated to XX kg (XX% of the asteroid mass). Such continuous dust ejection for the inner active asteroids was unexpected because ice might have already sublimated from subsurfaces of inner main belt. Based on our observational evidence, we will discuss how inner asteroids are activated and eject dust continuously.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제15권9호
• /
• pp.3274-3297
• /
• 2021

Permission delegation is an important research issue in access control. It allows a user to delegate some of his permissions to others to reduce his workload, or enables others to complete some tasks on his behalf when he is unavailable to do so. As an ideal solution for controlling read access on outsourced data objects on the cloud, Ciphertext-Policy Attribute-Based Encryption (CP-ABE) has attracted much attention. Some existing CP-ABE schemes handle the read permission delegation through the delegation of the user's private key to others. Still, these schemes lack the further consideration of granularity and traceability of the permission delegation. To this end, this article proposes a flexible and fine-grained CP-ABE key delegation approach that supports white-box traceability. In this approach, the key delegator first examines the relations between the data objects, read permission thereof that he intends to delegate, and the attributes associated with the access policies of these data objects. Then he chooses a minimal attribute set from his attributes according to the principle of least privilege. He constructs the delegation key with the minimal attribute set. Thus, we can achieve the shortest delegation key and minimize the time of key delegation under the premise of guaranteeing the delegator's access control requirement. The Key Generation Center (KGC) then embeds the delegatee's identity into the key to trace the route of the delegation key. Our approach prevents the delegatee from combining his existing key with the new delegation key to access unauthorized data objects. Theoretical analysis and test results show that our approach helps the KGC transfer some of its burdensome key generation tasks to regular users (delegators) to accommodate more users.

• International Journal of Internet, Broadcasting and Communication
• /
• 제13권4호
• /
• pp.79-89
• /
• 2021

Electronic learning (e-learning) empowers the higher education in providing sustainable instruction during the infrequent circumstance when the wide-spreading disastrous challenge of the COVID-19 results in the closure of various sectors in the society. During this time, e-learning serves the levels of the education sector such as higher education well by delivering and receiving materials from distance with respect to movement restrictions imposed by the government, for example the Movement Control Order (MCO) in Malaysia. In this qualitative survey, the existing e-learning challenges and the recommended solutions to the problems from the senior lecturers' perspectives were collected through an online open-ended questionnaire. A number of five senior lecturers out of eight at the Universiti Teknologi Malaysia (UTM) answered the questionnaire. The UTM has been capable of providing e-learning courses for all of its lecturers and students during the closure of higher education institutions owing to the pernicious health conditions stemmed from the crisis of the COVID-19. The major existing challenges found in the e-learning program at the UTM and the suggested solutions to address them are listed and the main themes are illustrated in the word cloud format using the NVivo software. In the end, the conclusion is paragraphed and the future work is proposed. Overall, the purpose of this study is to address the e-learning challenges and to prepare a list of recommendations that can serve as solutions from the standpoint of the UTM senior lecturers during the MCO in Malaysia.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
• /
• 제9권12호
• /
• pp.307-314
• /
• 2020

영상 감시 시스템은 광범위한 영역에서 쉽게 설치되고 녹화 장치 혹은 인터넷을 통한 클라우드 저장소에 영상 정보를 관리하는 중앙 관리 방식을 사용하고 있다. 이러한 시스템의 주요한 문제점은 저장 영상의 전송 과정과 저장 대해서 객관적으로 신뢰할 수 있는 방법이 제공되지 않고 있으며, 개인정보보호를 위한 장치 유무와 별개로 모든 권한을 서비스 제공자에게 위임한 상태에서 운영하고 있다는 점이다. 본 연구에서는 공개키 기반 암호화와 블록체인 기반의 키 관리 시스템을 조합한 아키텍처를 이용하여 민감한 정보를 사용자가 안전하게 보호할 수 있는 방안을 제시한다. 제안하는 아키텍처에서는 대칭키를 사용한 블록 암호화(block-cipher) 과정을 통해 영상 정보를 암호화하고, 이때 사용하는 대칭키를 사용자의 공개키로 암호화하여 블록체인의 레저(ledger)로 기록하는 기법을 사용한다. 영상 정보를 암호화하는 과정을 블록체인 네트워크의 특성(분산, 투명성, 데이터 변조 불가)을 활용하여 개인정보 영상의 생성부터 소멸까지 사용자가 추적이 가능하도록 한다.

• 국제물리치료학회지
• /
• 제12권1호
• /
• pp.2261-2266
• /
• 2021

Background: Deep learning related research works on website medical images have been actively conducted in the field of health care, however, articles related to the musculoskeletal system have been introduced insufficiently, deep learning-based studies on classifying orthopedic manual therapy images would also just be entered. Objectives: To create a deep learning model that categorizes cervical mobilization images and establish a web application to find out its clinical utility. Design: Research and development. Methods: Three types of cervical mobilization images (central posteroanterior (CPA) mobilization, unilateral posteroanterior (UPA) mobilization, and anteroposterior (AP) mobilization) were obtained using functions of 'Download All Images' and a web crawler. Unnecessary images were filtered from 'Auslogics Duplicate File Finder' to obtain the final 144 data (CPA=62, UPA=46, AP=36). Training classified into 3 classes was conducted in Teachable Machine. The next procedures, the trained model source was uploaded to the web application cloud integrated development environment (https://ide.goorm.io/) and the frame was built. The trained model was tested in three environments: Teachable Machine File Upload (TMFU), Teachable Machine Webcam (TMW), and Web Service webcam (WSW). Results: In three environments (TMFU, TMW, WSW), the accuracy of CPA mobilization images was 81-96%. The accuracy of the UPA mobilization image was 43~94%, and the accuracy deviation was greater than that of CPA. The accuracy of the AP mobilization image was 65-75%, and the deviation was not large compared to the other groups. In the three environments, the average accuracy of CPA was 92%, and the accuracy of UPA and AP was similar up to 70%. Conclusion: This study suggests that training of images of orthopedic manual therapy using machine learning open software is possible, and that web applications made using this training model can be used clinically.