• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1327-1334
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• 2008

In this paper, the purpose is to investigate the stability of cracked Timoshenko cantilever beams subjected to subtangential follower force. In addition, an analysis of the instability(critical follower force of flutter and divergence) of a cracked beam as slenderness ratio and subtangential coefficient is investigated. The governing differential equations of a Timoshenko beam subjected to an end tangential follower force is derived via Hamilton's principle. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. The results of this study will contribute to the safety test and stability estimation of structures of a cracked beam subjected to subtangential follower force.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.569-574
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• 2008

In Because DTV comes to origin of car body shock or brake pedal flutter occurrence in car. This in development of measurement device that can examine this in driver protection dimension or at production early sending of goods visual point purpose of this study have. In this paper, I developed portable Brake Judder measurement system by use of the DTV.

• Wind and Structures
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• v.1 no.1
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• pp.67-75
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• 1998

Tiger Gate Bridge, a steel suspension bridge with a main span of 888 m and a stiffening box girder, is located at the Pearl River Estuary, Guangdong Province, one of the typhoon-prone area in China. Focusing on the developing of the full aeroelastic model of the bridge and simulation of the wind field of the bridge site in a large boundary wind tunnel at Tongji University, Shanghai, China, some main results about the wind resistant properties of the bridge including aerodynamic instability, buffeting responses both being in operation and erection stages by using of a full aeroelastic model wind tunnel testing are introduced. Some of analytical approaches to those aerodynamic behaviours are also presented, and compared with experimental data of the testing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.170-171
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• 2022

Recently, artificial intelligence has been widely used in various fields. Traditionally, students have studied in cramming methods rather than self-directed learning through schools and numerous extracurricular activities. In order to alleviate the problem of injection-type education, students can be expected to improve their self-directed learning skills by considering the level of students through the artificial intelligence English word app. In this paper, we will propose ways to utilize artificial intelligence for efficient learning.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.463-464
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• 2023

본 논문에서는 플루터와 파이어베이스를 기반으로 구글 맵에서 위치 정보를 받아 높은 정확도와 빠른 위치 정보 업데이트가 가능한 버스 등하교 시스템을 개발하고 위치 정보가 제대로 업데이트되는지 확인하기 위해 대중교통을 타고 직접 실험하였다. 최근 어린 자녀에 대한 학부모의 걱정이 커지고 있으며 부모와 교사 간의 갈등도 빈번하게 발생한다. 가장 대표적인 원인으로 학부모와 교사 간의 불필요한 연락 그리고 아이들의 안전을 꼽을 수 있다. 하지만 위 플랫폼을 통하면 학부모와 교사 간의 연락을 최소화하고 자녀들의 안전을 지키고 혹시 모를 돌발 상황이 생겼을 때 빠른 해결이 가능하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.149-150
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• 2023

반려동물이 혼자 있는 시간이 많아지면 분리불안, 우울증, 이식증 등 질병이 생기기 때문에 이것을 방지하기 위해 보호자가 외부에 있어도 혼자 있는 반려동물을 돌보기 위한 앱이다. 플러터로 다중플랫폼 앱을 개발하였고 기능에는 원격 조작, 건강 상태 진단, 자동 급식, 청소, 놀이, 실시간 모니터링 기능이 포함되어 있다. 아두이노와 통신을 위한 flutter Blue 패키지를 사용하였다. 반려동물 돌봄 로봇은 아두이노와 블루투스 모듈을 활용하여 스마트폰 앱에서 조작 가능한 Caterpillar 모바일 로봇을 활용하였다. 이 연구의 목적은 반려동물과 보호자에게 편의성 제공을 목표로 한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.287-288
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• 2024

본 논문에서는 플루터, 파이어베이스와 구글맵을 기반으로 라즈베리파이에 GPS 모듈을 장착하여 위치 정보를 실시간으로 받아 대형견, 소형견 위치를 파악하여 경고 알림을 송신하고 자신의 애완동물과 거리가 멀어지게 된다면 경고 알림을 송신하여 대형견에 의한 피해 사례를 감소시키고 유실 및 실종 동물 사례를 감소시킨다. 또한 게시판을 통해서 산책 친구와 산책 아르바이트를 구할 수 있는 기능을 추가하고 산책 시 유의 사항, 오픈웨더를 통해 날씨 등 산책에 필요한 정보들을 추가하여 산책 시 위험한 요소를 해결할 수 있고 필요한 요소를 통합한 애플리케이션을 개발한다.

• Korean Journal of Applied Biomechanics
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• v.27 no.4
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• pp.247-255
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• 2017

Objective: The purpose of this study was to investigate the maximum core muscle activation angle according to core-strengthening exercises. Method: Twenty-six young female football players (age: $17.84{\pm}0.80years$, height: $163.08{\pm}5.25cm$, weight: $54.96{\pm}7.41kg$) registered in the Korea Football Association from D High School located in Seoul were the subjects of this research. An electromyogram (Noraxon, USA) was used for monitoring the maximum core muscle contraction activity. Results: The angle for the maximum core muscle strength per core exercise and muscle was the smallest for the upper rectus abdominis in the windshield wiper exercise. The angle of the vastus medialis was significantly the largest. The range of angles at which the maximum strength was observed for each core exercise were as follows: 1) abdominal flutter kicks ($11{\sim}40^{\circ}$), 2) leg raises ($21{\sim}34^{\circ}$), 3) scissors ($45{\sim}66^{\circ}$), 4) knee to elbow sit-ups ($42{\sim}64^{\circ}$), 5) reverse crunches ($9{\sim}40^{\circ}$), 6) butt-ups ($24{\sim}32^{\circ}$), 7) V sit-ups ($5{\sim}24^{\circ}$), 8) windshield wipers ($11{\sim}20^{\circ}$), 9) bird dog ($11{\sim}18^{\circ}$), and 10) raised leg plank ($38{\sim}50^{\circ}$). Conclusion: Four kinds of motion could be classified according to the range of angles at which the core muscles were maximally activated. The first group involves the range of motion that gives the maximum muscle strength when the lower extremity and ground angle was between $5^{\circ}$ and $24^{\circ}$, such as the V sit-ups, windshield wipers, and bird dog. The second group comprised the flutter kicks and reverse crunches at an angle between $9^{\circ}$ and $40^{\circ}$. The third group comprised the leg raise and butt-up exercises at an angle between $21^{\circ}$ and $34^{\circ}$. The fourth group included the scissors, knee to elbow sit-ups, and raised leg plank at an angle between $38^{\circ}$ and $66^{\circ}$. These results may be useful as basic data for core movement and core muscle training according to the purpose of exercise.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.91-99
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• 2005

Flight compatibility certification is performed to substantiate the compatibility between ALQ-X ECM pod and KF-16D/RF-4C aircraft. A certification plan for the ALQ-X flight compatibility is established. Similarity analysis, mass/inertia analysis, structural analysis/test, and ground vibration test/flutter analysis are made to support the safety of MIL-HDBK-1763 Test 250 (Captive compatibility flight profile). Aircraft flew along flight envelope boundary with representative ALQ-X configurations. Handling qualities are evaluated by comparing flight characteristics of the aircraft with and without ALQ-X. Structural integrity and endurance is evaluated using measured flight test data. Results of these flight tests showed that ALQ-X is compatible with KF-16D/RF-4C without altering the flight envelope which has originally been certified for ALQ-88 and ALQ-119 ECM pods. ALQ-X certification program made following technical achievements: Type III certification for foreign designed fighter, flutter analysis program development using GVT results, and utilization of MIL-STD-1553B data bus in flight test.

• Journal of the Korea Computer Graphics Society
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• v.28 no.3
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• pp.79-89
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• 2022

With the popularity and the advanced graphics hardware technology of mobile devices, various mobile applications that help children with physical activities have been studied. This paper presents SandUp, a mobile application that guides the play of building sand castles using artificial intelligence and augmented reality(AR) technology. In the process of building the sandcastle, children can interactively explore the target virtual sandcastle through the smartphone display using AR technology. In addition, to help children complete the sandcastle, SandUp informs the sand shape and task required step by step and provides visual and auditory feedback while recognizing progress in real-time using the phone's camera and deep learning classification. We prototyped our SandUp app using Flutter and TensorFlow Lite. To evaluate the usability and effectiveness of the proposed SandUp, we conducted a questionnaire survey on 50 adults and a user study on 20 children aged 4~7 years. The survey results showed that SandUp effectively helps build the sandcastle with proper interactive guidance. Based on the results from the user study on children and feedback from their parents, we also derived usability issues that can be further improved and suggested future research directions.