• 한국해안·해양공학회논문집
• /
• 제27권1호
• /
• pp.1-8
• /
• 2015

우리나라 남서해안은 풍력발전에 최적지로 평가받고 있으며 최근 해상풍력 구조물을 포함하는 해안구조물의 건설이 증가하고 있다. 그러나 우리나라 남서해안의 조차는 3~8 m까지 발생하여 남서해안에 설치되는 풍력기초들은 횡방향력과 조류의 다방향 흐름에 의한 세굴로 전체 구조물에 예상치 못한 진동에 의한 불안정성이 야기될 수 있다. 이 연구에서는 회전식 수리저항성능 실험기를 이용하여 인공지반시료의 수리저항성능을 평가하였으며 전기비저항 측정결과와 비교하여 수리저항성능과 전기비저항 특성과의 상관관계에 대한 연구를 진행하였다. 실험결과 일방향 한계전단응력과 양방향 한계전단응력을 상한계와 하한계로 표시하고 전기비저항 특성과 상관관계를 도시하면 조립토와 세립토가 비교적 명확히 구분되고 한계전단응력과의 상관관계 도출이 가능한 것으로 나타났다.

• 한국생산제조학회지
• /
• 제19권6호
• /
• pp.776-781
• /
• 2010

Optimum design of movable hydraulic crane's booms for weight reduction was performed in this study. Since the boom weight of the present used booms is very heavy, it is needed to make them lighter structure as possible as we can. Optimum design was performed for the booms by changing from the hexagonal cross section to triangular truss structure under the conditions, which are the allowable stress for the present cross section must be maintained, and the optimized weight must be minimized. CATIAV5 was used for stress analysis and design variables were established as the height and width of the triangular truss structure. As the results, it is found that the height of the truss structure is increased in proportion to the height of the booms and the maximum stress for optimal truss structure was obtained as 412MPa, which is lower than the allowable stress for the present hexagonal cross section. The optimized weight of the booms is reduced to about 19.88% comparing to the original weight.

• 드라이브 ㆍ 컨트롤
• /
• 제18권4호
• /
• pp.52-58
• /
• 2021

The variable structure controller is designed such that in sliding mode, the system moves along the switching plane in the vicinity of the switching plane, thus it is robust because it is not affected by the parameter fluctuations of the plant. However, a controller based on a variable structure may not meet the desired performance when it is commanded to track any input or is exposed to disturbances. This study proposes a sliding mode controller that follows the IVSC (Integral Variable Structure Control) approach with ELO (Extended Luenberger observer) to solve this problem. The proposed sliding mode control is applied to the velocity control of the hydraulic motor. The sliding plane was determined by the pole placement, and the control input was designed to ensure the existence of the sliding mode. The feasibility of modeling and controller are reviewed by comparing with conventional proportional-integral control through computer simulation using MATLAB software and experimenting on the cases of significant plant parameter fluctuations and disturbances.

• 제어로봇시스템학회논문지
• /
• 제17권9호
• /
• pp.863-868
• /
• 2011

This paper presents a method to achieve a synchronous positioning objective for a dual-cylinder electro-hydraulic system with friction characteristics. The control system consists of a VSC (Variable Structure Controller) for each of the hydraulic cylinders and a PID (Proportional-Integral-Derivative) feedback controller. The PID controller is used for controlling the non-synchronous error generated by both cylinders when motion synchronization is carried out. To enhance the position-tracking performance of the individual cylinders friction characteristics is modeled in model, based on the estimated friction force. The simulation and experimental results show that the proposed method can effectively achieve the objective of position synchronization in the dualcylinder electro-hydraulic system, with maximum synchronization error with ${\pm}2\;mm$.

• Earthquakes and Structures
• /
• 제14권2호
• /
• pp.143-153
• /
• 2018

Correlation among different factors must be considered for selection of influencing factors in safety monitoring of high dam including positive correlation of variables. Therefore, a new factor selection method was constructed based on Copula entropy and mutual information theory, which was deduced and optimized. Considering the small sample size in high dam monitoring and distribution of daily monitoring samples, a computing method that avoids causality of structure as much as possible is needed. The two-dimensional normal information diffusion and fuzzy reasoning of pattern recognition field are based on the weight theory, which avoids complicated causes of the studying structure. Hence, it is used to dam safety monitoring field and simplified, which increases sample information appropriately. Next, a complete system integrating high dam monitoring and uncertainty prediction method was established by combining Copula entropy theory and information diffusion theory. Finally, the proposed method was applied in seepage monitoring of Nuozhadu clay core-wall rockfill dam. Its selection of influencing factors and processing of sample data were compared with different models. Results demonstrated that the proposed method increases the prediction accuracy to some extent.

• 한국산학기술학회논문지
• /
• 제12권11호
• /
• pp.4738-4744
• /
• 2011

본 연구는 상부에 설치되는 콘크리트 구조물 없이 설치되어 작동하는 새로운 소형 수문 시스템을 제안하였다. 주요 메커니즘은 유압시스템, 수문 상하 이송 메커니즘, 수문 잠금 제어장치, 이물질이 감지되면 수문이 파손되지 않도록 하는 안전장치 등으로 구성하였다. 유압 펌프 및 제어 시스템은 수문 시스템의 위치에서 떨어진 장소에 설치하여 상부 구조물을 제거할 수 있도록 하여 제어 하였다. 수문 인양 장치는 유압 액추에이터가 달린 래크와 피니언이 측면에 설치되어 작동되며 그 결과 제품의 원가 절감, 작동시 안전성 확보 및 제품의 컴팩트화를 구현하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.1366-1369
• /
• 2010

Along with the increasing need of sea development, the hydraulic stability of seabed structure on a soft seafloor ground is becoming an issue in the course of seaside development recently. However, the movement and hydraulic resistance or hydraulic stability of seafloor ground are mutually coupled with various phenomena, and there has been no clear proof for the issue, which makes it difficult to forecast. Furthermore, most researches are focused on hydraulic variables and the conditions of marine external force, while there have been few researches into the assessment in consideration of the type of a seafloor ground and the geotechnical characteristics. In addition, according to the periodic change of the flow direction, possible changes in hydraulic resistance performance of the seafloor deserves all the recognition. But there is no way to measure the hydraulic unstability of the sea ground due to tidal flow quantitatively. In this study, conventional hydraulic resistance measurement apparatus was improved to consider direction change of the current flow. Various artificial clayey soil specimens were made from Kaolinite and Jumunjin standard sand and hydraulic resistance tests were performed by changing the flow direction to validate the effect of the direction change on the scour of the seafloor.

• 전기학회논문지
• /
• 제62권12호
• /
• pp.1809-1812
• /
• 2013

The bogie of monorail vehicles applies rubber wheel system not steel wheel system. In addition, The structure of the bogie is very complicated because vehicle operates on the elevated road and vehicle drives with wrapping the guide way. When the monorail vehicle applies air brake system, lower device of vehicle may be complex and some devices may be limited. On the other hand, hydraulic brake equipment is compact and not weighing. Braking force is also outstanding compared with air brake so the hydraulic brake equipment is suitable for monorail vehicle. Also urban transit system such as monorail, applies mixed system both friction brake and electric brake in order to save electric energy. But application case of hydraulic brake in the country is very rare because hydraulic brake have difficulty in satisfaction of control requirement and maintenance. Therefore, this study suggests ways to design hydraulic brake system with blending brake for monorail vehicle and applies the ways to future monorail.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
• /
• pp.310-314
• /
• 1988

In designing a high performance electrohydraulic control system for a large flexible structure, several flexible structural modes should be taken into account in a range of hydraulic control system bandwidth. The procedures of modeling a flexible mode control system and designing the high pass filter of load pressure feedback are presented. Example analysis varifies the presented analysis.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2008년도 학술발표회 논문집
• /
• pp.1818-1822
• /
• 2008

여수로와 같은 3차원 수리구조물을 설계하고 수리현상을 조사하거나, 형상 및 안정성을 파악하기 위해서는 일반적으로 수리모형실험을 통하여 실제 현상을 모의하는 경우가 많다. 그러나 수리모형실험을 하기 위해서는 많은 시간과 비용 및 공간이 필요하며 실제 수리구조물을 축소시켜 측정하는 것은 대단히 어렵고 표면장력 등이 실험결과에도 상당한 영향을 미칠 수 있으며 다양한 경우의 실험은 현실적으로 불가능하다. 따라서, 수치해석을 통하여 적정한 초기결과를 도출할 필요성이 있으며, 이를 통하여 수리모형실험의 대상을 결정하고 결과를 비교한다면 경제적이고 합리적인 수리구조물의 설계와 평가가 가능하다. 본 연구에서는 최적의 여수로를 설계하기 위하여 월류형 여수로를 대상으로 수치해석을 수행하였고, 수리모형실험에 대한 실험적인 접근을 통하여 수리적 조건을 향상시킬 수 있는 보다 나은 설계안을 제시하였다. 이러한 수리모형실험 계측결과를 통하여 개선된 수리구조물 설계안을 제안하였고, 개선된 설계안에 대한 개선효과를 조사하였다.