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선체 구조강성 변화에 따른 컨테이너선의 파랑하중 연구 2 : 수직 전단력 및 굽힘모멘트
김영식(KIM YoungShik),김진하(KIM JinHa),김병완(KIM ByoungWan) 한국항해항만학회 2008 한국항해항만학회 학술대회논문집 Vol.2008 No.추계
최근, 대형 및 고속 컨테이너선의 설계 단계에서 엄밀한 구조해석의 필요성이 강조되고 있다. 선박의 신뢰성 있는 구조 및 운동 해석을 위해서는 운항선박에 작용하는 선형 및 비선형 파랑하중의 초기 추정이 매우 중요하다. 따라서 본 논문에서는 9분할 모형에 상이한 강성을 갖는 백본센서를 장착하여 2가지 구조 강성을 갖는 선박 모형을 제작하였다. 제작된 분할모형을 사용하여 규칙 및 불규칙 파랑 조건에서 운항하는 컨테이너선의 시나리오를 모형시험을 수행하였다. 시험으로부터 운항하는 컨테이너 선박에 발생하는 수직 전단력, 수직 굽힘 및 비틀림 모멘트 등의 파랑하중 응답을 비교분석하였고 이를 구조해석을 위한 초기자료를 활용하고자 한다. In the design process of shipbuilding for very large and high speed vessel, exact structural analysis is getting emphasized. To have resonable results of structural analysis, the estimation of initial wave loads is very important. In this paper, a experimental method which use backbone sensor and divided ship model is introduced to estimate the wave loads on a going containership. A experiment following the proposed method was conducted, and vertical shear force, vertical bending moment and torsional moment are estimated.
Design of Linked 2-DOF IPMC Actuator Moudule
Youngshik Kim(김영식),Bong-Jo Ryu(유봉조),Kyoung-Wan Koo(구경완),Buhyun Shin(신부현) 대한전기학회 2019 전기학회논문지 Vol.68 No.7
The 2-DOF IPMC module is introduced in this research. Each rotation axis of 2-DOF IPMC module is perpendicular each other. A second segment of IPMC is attached across to end tap of the first segment of IPMC directly without any frame. The link method with 2 IPMC actuator is assemble using a slot simply and conductive epoxy adhesive is used for wiring. The single IPMC strips are connected to rigid links, the open-loop control of the IPMC manipulator. The inverse kinematics of the linked 2-DOF IPMC was established. The experimental results show 2-DOF motion of the IPMC actuator module. This 2-DOF IPMC actuator module can be improved or modified for example by adding more links to even more increase the workspace by adding an extra soft link to the tip of the manipulator for extra soft manipulation.
김영식(Youngshik Kim),심현호(Hyun-Ho Shim),이경민(Kyung-min Lee),신부현(Buhyun Shin) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.7
The proposed two degree-of-freedom electromagnetic oscillatory actuator has a novel structure to combine two electromagnetic actuators of the moving-coil type. In order to rotate the actuator, the coil is attached to the moving frame, acting as the moving-coil type. There is three magnets, in the middle and inside each moving frame. The direction of the magnetism is perpendicular to the coil in order to change the direction of current induced to the coil and oscillate the moving frame. There are two types of forces applied to the 2-DoF electromagnetic oscillatory actuator. The magnetic force between the magnets holds the moving frame on the left or right side. That magnetic force is called as a holding force. The electromagnetic force generates the oscillatory motion when the current is applied to the coil. The overall size is 15 mm (W) × 15 mm (D) × 50 mm (H). All frames are made of ABS plastic using a rapid prototyping process to reduce inertia. The magnet material is ND35. The dynamic modeling and electromagnetic simulations and experiments are conducted. Resonance frequency is 18.5 Hz with only moving parts and 15.5 Hz including middle magnet. The laser beam profile shows 2-D motion for swing motion for various applications.
배액전극제어법에 의한 토마토 펄라이트 자루재배시 일중 첫 배액 제어
김성은(SungEun Kim),심상연(SangYoun Sim),김영식(YoungShik Kim) 한국원예학회 2010 원예과학기술지 Vol.28 No.3
배액전극 제어법을 이용한 토마토 펄라이트 자루재배에서 일중 첫 배액시각을 조절함으로써 적정관수법을 도출하고 배양액을 절감하기 위해 수행되었다. 배액전극 제어법은 다양한 일일 적산일사량, 온도, 습도에서도 식물체의 요구에 능동적으로 급액회수가 변하며 배지의 무게가 안정적으로 유지되었다. 작물의 생육특성상 목표한 첫 배액시각을 정확히 맞추는 것은 어려웠으며, 일중 첫 배액시각을 10시로 제어한 급액처리에서 전후 20분, 10시30분으로 제어한 급액처리에서 전후 50분 정도의 오차범위를 나타내었다. 일중 첫 배액시각은 고려하지 않고 30분 이내에는 관수가 반복되지 않도록 제어한 처리에서는 일중 첫 배액시각은 일정하지 않았으나 실험기간동안 오전 중 첫배액 발생이 고르게 나타났다. 배액전극 제어법은 타이머법에 비해 배액율이 비교적 균일하게 유지되었고, 수분이용효율과 비료이용효율의 분석 결과 매우 경제적인 급액방법이었다. 생육과 총수확량, 당도 등은 처리간 차이가 뚜렷하지 않았으나, 평균과중은 배액전극 제어법이 타이머법보다 컸다. The first drainage time in a day was controlled for precise irrigation management with low consumption of nutrient solution in tomato perlite bag culture system by measuring water level of drained water in drainage catchment part. This method automatically adjusted the irrigation time under any condition of light, temperature and humidity, resulting in stable water content in substrates. However, it was difficult to keep the time consistent as they were set. It drained with the deviation of 20 min in the treatment in which the first drainage time was set at 10:00 and 50 min in the treatment set at 10:30. The first drainage time was not constant, but the drain occurred stably before noon in the treatment of which irrigation frequency was longer than 30 min. The drainage ratio was better balanced in all the treatments using drainage level sensors than the treatment using time clock for irrigation control. High water and fertilizer efficiencies were obtained. Although the growth, total yield and sugar content were not significantly different between the treatments, fruit weight was higher in the treatments using drainage level sensors than that using timer.
인공지능을 적용한 소형 모바일 로봇을 위한 물체 및 환경 인식 연구
김현태(Hyuntae Kim),김영식(Youngshik Kim) 한국디지털콘텐츠학회 2020 한국디지털콘텐츠학회논문지 Vol.21 No.4
In this research we study artificial intelligence-based environment recognition for autonomous navigation of a small mobile robot with limited hardware resources. Toward this goal, we designed a wheel-leg mobile robot that could transform its circular wheel configuration into wheel-leg configuration for rugged terrain locomotion. Size of a wheel-leg can be increased up to 2.5 times larger when compared to circular wheel configuration applying gear-driven mechanisms. A web camera and less expensive embedded board integrated with a GPU are used in the case. We used YOLOv3 as a deep learning model to recognize obstacles in real time. Performance of learned model is verified using mAP and GIoU. Our proposed object recognition algorithm is implemented in the real wheel-leg mobile robot and its performance is verified in unstructured environments.