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수면 지면 동시보행을 위한 Klann 기구 기반 주행메커니즘 최적설계
김현규(Hyun-Gyu Kim),정민석(Min-Suck Jung),신재균(Jae-Kyun Shin),서태원(TaeWon Seo) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.9
Walking mechanisms are very important for legged robots to ensure their stable locomotion. In this research, Klannlinkage is suggested as a walking mechanism for a water-running robot and is optimized using level average analysis. The structure of the Klann-linkage is introduced first and design variables for the Klann-linkage are identified considering the kinematic task of the walking mechanism. Next, the design problem is formulated as a path generation optimization problem. Specifically, the desired path for the foot-pad is defined and the objective function is defined as the structural error between the desired and the generated paths. A process for solving the optimization problem is suggested utilizing the sensitivity analysis of the design variables. As a result, optimized lengths of Klann-linkage are obtained and the optimum trajectory is obtained. It is found that the optimized trajectory improves the cost function by about 62% from the initial one. It is expected that the results from this research can be used as a good example for designing legged robots.
탄성체의 에너지 변환을 이용한 점프 로봇의 기구변수 최적화
최재능(JaeNeung Choi),이상호(Sangho Lee),정경민(Kyungmin Jeong),서태원(TaeWon Seo) 제어로봇시스템학회 2016 제어·로봇·시스템학회 논문지 Vol.22 No.1
Various jumping robot platforms have been developed to carry out missions such as rescues, explorations, or inspections of dangerous environments. We suggested a jumping robot platform using energy conversion of the elastic body like the bar of a pole vault, which is the main part in which elastic force occurs. The compliant link was optimized by an optimization method based on Taguchi methodology, and the robot’s leaping ability was improved. Among the parameters, the length, width, and thickness of the link were selected as design variables first while the others were fixed. The level of the design variables was settled, and an orthogonal array about its combination was made. In the experiment, dynamic simulations were conducted using the DAFUL program, and response table and sensitivity analyses were performed. We found optimized values through a level average analysis and sensitivity analysis. As a result, the maximum leaping height of the optimized robot increased by more than 6.2% compared to the initial one, and these data will be used to design a new robot.
임우리,박원배,이창한,함세영 한국지구과학회 2022 한국지구과학회지 Vol.43 No.4
In the coastal areas of Jeju Island, composed of volcanic rocks, saltwater intrusion occurs due to excessive pumping and geological characteristics. Groundwater level and electrical conductivity (EC) in multi-depth monitoring wells in coastal areas were characterized from 2005 to 2019. During the period of the lowest monthly precipitation, from November 2017 until February 2018, groundwater level decreased by 0.32-0.91 m. During the period of the highest monthly precipitation, from September 2019 until October 2019, groundwater level increased by 0.46-2.95 m. Groundwater level fluctuation between the dry and wet seasons ranged from 0.79 to 3.73 m (average 1.82 m) in the eastern area, from 0.47 to 6.57 m (average 2.55 m) in the western area, from 0.77 to 8.59 m (average 3.53 m) in the southern area, and from 1.06 to 12.36 m (average 5.92 m) in the northern area. In 2013, when the area experienced decreased annual precipitation, at some monitoring wells in the western area, the groundwater level decreased due to excessive groundwater pumping and saltwater intrusion. Based on EC values of 10,000 µS/cm or more, saltwater intrusion from the coastline was 10.2 km in the eastern area, 4.1 km in the western area, 5.8 km in the southern area, and 5.7 km in the northern area. Autocorrelation analysis of groundwater level revealed that the arithmetic mean of delay time was 0.43 months in the eastern area, 0.87 months in the northern area, 10.93 months in the southern area, and 17.02 months in the western area. Although a few monitoring wells were strongly influenced by nearby pumping wells, the cross-correlation function of the groundwater level was the highest with precipitation in most wells. The seasonal autoregressive integrated moving average model indicated that the groundwater level will decrease in most wells in the western area and decrease or increase in different wells in the eastern area.
계층적 베이지안 모델을 적용한 극치 해수위 비정상성 빈도 분석
김용탁(Yong-Tak Kim),오랑치맥 솜야(Sumiya Uranchimeg),권현한(Hyun-Han Kwon),황규남(Kyu Nam Hwang) 한국해안해양공학회 2016 한국해안해양공학회 논문집 Vol.28 No.1
국내의 연안은 지속적 발전으로 해수면 상승(sea level rise, SLR)으로 인한 연안재해 취약성이 가중될 것으로 전망되고 있다. 본 연구에서는 평균해수면 상승에 따른 극치조위 자료에 대한 비정상성 빈도분석을 수행하였다. Mann-Kendall(MK) 검정 결과 연평균조위(annual average tide)의 경우 17개 지점에서 경향성이 통계적으로 유의한 것으로 나타났으며, 연극치 조위의 경우에는 7개 지점에서 유의한 것으로 나타났다. 비정상성 빈도 해석 결과 2100년에 한반도 연안의 극치 해수면 변화는 최소 60.33 mm에서 최대 214.90 mm까지 증가하는 것으로 분석되었다. Urban development and population increases are continuously progressed in the coastal areas in Korea, thus it is expected that vulnerability towards coastal disasters by sea level rise (SLR) would be accelerated. This study investigated trend of the sea level data using Mann-Kendall (MK) test, and the results showed that the increasing trends of annual average sea level at 17 locations were statistically significant. For annual maximum extremes, seven locations exhibited statistically significant trends. In this study, non-stationary frequency analysis for the annual extreme data together with average sea level data as a covariate was performed. Non-stationary frequency analysis results showed that sea level at the coastal areas of Korean Peninsula would be increased from a minimum of 60.33 mm to a maximum of 214.90 mm by 2100.
[응용논문] 다구찌 기법을 적용한 Stone Chipping에 의한 변형량 최소화를 위한 환경 요인 분석
추용주(Yong-Ju Chu),은효준(Hyo-Jun Eun),정시욱(Si-Uk Jung),이승엽(Seung-Yop Lee) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.7
Most electric vehicles manufactured these days include battery packs and powertrain parts mounted at the bottom near the rear axle or rear wheel. In this study, we analyzed and identified the main factors for determining stone chipping deformation, which causes the unwanted destruction of underbody parts while driving electric vehicles. By analyzing the average level on the stone chipping phenomena and signal-to-noise ratio, the influence of external impact factors(e.g., velocity, mass, shape, and material property) on stone chipping deformation was confirmed based on the Taguchi method. Based on the analysis of the stone chipping impact diagram, we can propose a design guideline for the underbody parts in order to reduce the development cost and time.