• 한국해양공학회지
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• 제21권1호
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• pp.69-74
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• 2007

This paper is concerned about the dynamic analysis of an underwater test miner, which operates on cohesive soil. The test miner consists of tracked vehicles and a pick-up device. The motion of the pick-up device, relative to the vehicle chassis, is controlled by two pairs of hydraulic cylinders. The test miner is modeled by means of commercial software. A terramechanics model of cohesive soft soil is implemented with the software and applied to a dynamic analysis of the test miner model. The dynamic responses of the test miner are studied with respect to four different types of terrain conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.881-886
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• 2004

This paper presents the inverse dynamic analysis of the wheel loader manipulator based on the experimental data. A three dimensional rigid multi-body model of the wheel loader manipulator was built up. The inverse dynamic analysis for the typical operation mode was carried out by the ADAMS program. In order to verify the analysis result with the measured one, the hydraulic pressure and displacements of the cylinders were measured and the inverse dynamic analysis was carried out using experimental data. From the results of the analysis and measurement, it was concluded that the computational driving force showed good agreement with the measured one.

• 물과 미래
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• 제29권1호
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• pp.249-263
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• 1996

본 논문에서는 고정된 전선과 원형 실린더에 부착되는 icing 으로 인해 발생되는 하중(icing의 무게 및 풍하중)에 관한 실험을 수행하고 그 결과를 수록하였다. 실험은 이동 가능한 풍동을 이용하여 냉동실 실험과 실혼 실험으로 구분하여 실시하였다. 냉동실 실험에서는 icing으로 인한 하중의 시간적 변화를 측정하였으며, 실온 실험에서는 특제작한 icing 모형을 이용하여 풍속 변화에 따른 풍하중 변동을 측정하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.379-382
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• 2006

두께가 얇고 길이가 긴 튜브 제품을 생산하기 위한 방법으로 유동성형 공정이 많이 이용되고 있으며 이는 다른 가공방법에 비해 성형력이 작고 유동성형에 의해 가공된 제품의 기계적인 강도가 우수하며 가공 후 표면 품질이 좋기 때문이다. 특히 유동성형은 로켓 모터 케이스, 연소기, 유압 실린더 그리고 고압용기 등과 같은 고정밀도의 두께가 얇은 실린더 제품을 생산하기 위한 적합한 공정이다. 본 논문에서는 3개의 롤러를 가지는 전후방 유동성형에 대한 유한요소해석을 통해 가공깊이와 가공속도가 성형력에 미치는 영향을 살펴보았다. 다양한 가공깊이와 가공속도 조건에서 얻어진 전후방 유동성형에서의 축방향과 반경방향의 성형력을 비교하였다.

• 한국추진공학회지
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• 제14권4호
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• pp.39-45
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• 2010

자주포 또는 원자로와 같은 두꺼운 실린더는 압력용기 내부에 유익한 잔류 압축응력을 유도하여 작용압력과 피로수명을 증가시키도록 자긴 가공되고 있다. 자긴가공도가 증가하면 구멍에서 압축잔류응력의 크기도 증가한다. 본연구의 목적은 ASME 코드에 의해 적용된 Kendall 모델을 이용하여 고강도 SCM440 강의 정확한 잔류응력을 예측하는 것이다. SCM440 후육실린더의 내부에 유압이 적용되고 30% 변형률까지 자긴 가공하였다. 자긴가공된 시편은 전해연마하고 X-ray 회절법을 이용하여 정확한 잔류응력을 산출하도록 하였다. 그리고 주사전자현미경을 이용하여 자긴가공에 의해 소성변형된 표면층을 분석하였다. 측정한 잔류응력과 계산된 결과를 비교하여 약간의 차이는 있으나 비교적 서로 잘 일치하고 있다.

• Design & Manufacturing
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• 제10권1호
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• pp.51-54
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• 2016

Metal sheet forming has been commonly used as the core technology in manufacturing parts of automobiles. It guarantees the highest production rate due to the process of mass production employing the press die. For precision of the product, the accuracy of the molds and its mechanic structures are considered as essential factors. One of these is fine blanking, which is utilized for the production of the metal sheet spring, with which clear sheer surfaces can be achieved in one operation from the materials. However, the current designs of press dies perform the forming analysis with the molds of rigid body, so they are focused on weight lightening by a rule of thumb. Therefore, this paper practice structural analysis about developing the semi fine-fine blanking technology. The semi fine-blanking can be run through the combination of the hydraulic cylinders and normal presses, so this paper analyze the amount of deformation according to the oil pressure. In addition, based on the plasticity of 50CrV4, the materials of the mold parts, the structural analysis and life analysis are proceeded, so they are expected to be useful as data for manufacturing the mold.

• International Journal of Automotive Technology
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• 제5권4호
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• pp.247-255
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• 2004

The majority of real world frontal collisions involves partial overlap (offset) collision, in which only one of the two longitudinal members is used for energy absorption. This leads to dangerous intrusions of the passenger compartment. Excessive intrusion is usually generated on the impacted side causing higher contact injury risk on the occupants compared with full frontal collision. The ideal structure needs to have extendable length when the front-end structure is not capable to absorb crash energy without violating deceleration pulse requirements. A smart structure has been proposed to meet this ideal requirement. The proposed front-end structure consists of two hydraulic cylinders integrated with the front-end longitudinal members of standard vehicles. The work carried out in this paper includes developing and analyzing mathematical models of two different cases representing vehicle-to-vehicle and vehicle-to-barrier in full and offset collisions. By numerical crash simulations, this idea has been evaluated and optimized. It is proven form numerical simulations that the smart structures bring significantly lower intrusions and decelerations. In addition, it is shown that the mathematical models are valid, flexible, and can be used in an effective way to give a quick insight of real life crashes.

• 한국정밀공학회지
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• 제16권1호통권94호
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• pp.211-218
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• 1999

The traditional robot manipulators are actuated by continuous range of motion actuators such as motors or hydraulic cylinders. However, there are many applications of mechanisms and robotic manipulators where only a finite number of locations need to be reached, and the robot’s trajectory is not important as long as it is bounded. Binary manipulator uses actuators which have only two stable states. As a result, binary manipulators have a finite number of states. The number of states of a binary manipulator grows exponentially with the number of actuators. This kind of robot manipulator has some advantage compared to a traditional one. Feedback control is not required, task repeatability can be very high, and finite state actuators are generally inexpensive. And this kind of robot manipulator has a fault tolerant mechanism because of kinematic redundancy. In this paper, we solve the inverse kinematic problem of a binary parallel robot manipulator using neural network and test the validity of this structure using some arbitrary points m the workspace of the robot manipulator. As a result, we can show that the neural network can find the nearest feasible points and corresponding binary states of the joints of the robot manipulator

• 연구논문집
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• 통권29호
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• pp.57-67
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• 1999

This paper presents the status quo of the development of a piecewise bendable switch system for the urban transit MagLev. MagLev system as well as railroad requires switch systems to reach its destination. Requirements of the switch system for commercial lines are high speed operation satisfying about 2-3 minute headway and system reliability, etc. Parallel moving type switch system was installed on the test track of urban transit MagLev in KIMM. In this system, switch operation from one position to another can be done in about 90 seconds. Therefore, we concluded that this system can not satisfy the headway for the commercial lines. We decided to develop a high speed piecewise bendable switch system in which switching can be done in 20 seconds. Designed switch system is very complicated in view of operating mechanism. It consists of 11 segmented girder beams driven by hydraulic cylinders. To gain the idea of a piecewise bendable switch system, we manufactured and tested a 1/5 scale switch model. We are going to construct a full scale piecewise bendable switch system next year.

• 대한기계학회논문집A
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• 제23권11호
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• pp.1982-1992
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• 1999

This paper presents a novel concept of cargo handling system adapted for a sea port subjected to severe time-varying tide. The proposed system can perform loading or unloading by using a sort of hydraulic elevator associated with real-time position control. In order to achieve a proof-of-concept, a small-sized laboratory model of the cargo handling system is designed and built. The model consists of three principal components container palette transfer (CPT) car, platform with lifting columns, and cargo ship. The platform activated by electro-rheological (ER) valve-cylinders is actively controlled to track the position of the cargo ship subjected to be varied due to the time-varying tide and wave motion. Following the derivation of the dynamic model for the platform and cargo ship motions, an appropriate control scheme is formulated and implemented. The location of the CPT car is sensed by a set of photoelectric switches and controlled via sequence controller. On the other hand, a sliding mode controller (SMC) is adopted as the position controller for the platform. Both simulated and measured control results are presented to demonstrate the effectiveness of the proposed cargo system.