• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.3
• /
• pp.237-245
• /
• 2008

We developed a computational method on coupled dynamics of tracked vehicle on seafloor and long flexible pipe. The tracked vehicle is modeled as rigid-body vehicle, and the linked flexible pipe is discretized according to a lumped-parameter model. The equations of motion of the rigid-body vehicle on the soft seafloor are combined with the governing equations of flexible pipe dynamics. Four Euler parameters method is used to express the orientations of the vehicle and the flexible pipe. In order to solve the nonlinear coupled dynamics of vehicle and flexible pipe an incremental-iterative formulation is implemented. For the time-domain integration $Newmark-\beta$ method is adopted. The total Jacobean matrix has been derived based on the incremental-iterative formulation. The interactions between the dynamics of flexible pipe and the mobility of the tracked vehicle on soft seafloor are investigated through numerical simulations in time domain.

• Journal of Navigation and Port Research
• /
• v.34 no.3
• /
• pp.195-203
• /
• 2010

This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely cohesive soft soil is applied to the self-propelled miner. Hinged and ball constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, self-propelled miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-${\beta}$ method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

• Journal of the Korean Wood Science and Technology
• /
• v.42 no.3
• /
• pp.346-355
• /
• 2014

Confocal reflection microscopy (CRM) was utilized to create 3-dimensional images of bordered pits and cell wall in the tracheid of Korean red pine (Pinus densiflora). Ultrastructures of torus, margo, and pit border were clearly observable in the CRM micrograph. Micrograph of cross-field pit revealed the connecting and supporting structure between tracheid and ray parenchyma cell. The CRM micrographs enabled to investigate detailed structures of tracheid cell wall such as S1, S2, S3 layers, transition layers between these layers, and microfibril (MF) orientation in S3 and S2 layers as well as complicated distribution of MF orientation around bordered pits. Not only concentric MF orientation of border thickening in the pit border was observed, but also changes in MF orientation from the cell wall to the border. From the experimental results, the CRM was thought to be a versatile microtechnique to investigate detailed structures of cell wall and bordered pit in the tracheid and cross-field pit between tracheid and ray parenchyma cell.

• Journal of Korean Society of Forest Science
• /
• v.87 no.2
• /
• pp.153-163
• /
• 1998

Genetic relationships of some poplars in the section Leuce, including 5 species and 11 clones of Populus alba${\times}$glandulosa, were investigated on the basis of RAPD marker analysis. Twenty-two of the 88 arbitrary 10-mer primers, showed reproducible amplification in the preliminary experiment with 6 samples, were used for PCR and generated a total of 181 RAPD markers. Genetic relationships among the analyzed samples were tested by two phenetic methods of the UPGMA and the neighbor-joining, which revealed the close genetic relationship between P. glandulosa and P. alba. And the close genetic relationship between P. glandulosa and P. davidiana was ascertained by the principal component analysis. Based on the observation of the close genetic relationship between them, it was deduced that P. glandulosa might be originated by the saltational speciation caused by the hybridization between P. alba and P. davidiana in nature.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.895-896
• /
• 2010

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.12
• /
• pp.1213-1220
• /
• 2015

A deep seabed integrated mining system consists of a mining vessel, a lifting pipe, a buffer station, a flexible pipe, and a mining robot for collecting manganese nodules. Recently, the concept of multiple mining robots was introduced to enhance to mining productivity. In this paper, the subsystem synthesis method was applied to the deep seabed integrated mining system in order to improve the efficiency of system analysis and to facilitate its extension to the system of multiple mining robots. Large deflections of the lifting and flexible pipe were considered by dividing a flexible pipe into several substructures, and applying flexible multibody dynamics to each substructure. Theoretical study has been carried out for the efficiency of the subsystem synthesis method for the integrated mining system, by comparing the arithmetic operational counts of the subsystem synthesis method with those of the conventional method.

• Journal of Digital Convergence
• /
• v.17 no.1
• /
• pp.423-432
• /
• 2019

The purpose of this study was to investigate the effect of cushion insole on lumbar flexibility and motor fitness in patients with lumbar spinal stenosis. 26 patients with lumbar spinal stenosis were randomly assigned to the experimental group 13 and the control group 13. Volunteers were allowed to wear cushioned insoles for two hours a day for six weeks. The experimental group was 8 mm and the control group was 4 mm, wearing a cushion insole as a blinded experiment. There was a significant increase(p<0.05) in the flexion test of the experimental group ($3.38{\pm}3.12$), but not statistically significant in the other tests(p>0.05). In conclusion, cushion insole was not suitable for intervention for lumbar spinal stenosis. There is a need to study the height and material of the insoles in the future.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.463-468
• /
• 1998

수직 관다발형 비등관에서의 밀도파 진동 및 유동 폭주형 이상유동 불안정성을 해석하기 위하여 선형화 기법 및 D-partition 방법론에 근거한 해석 코드(ALFS)를 개발하고 기존 실험자료 분석을 통해 코드의 예측 성능을 평가하였다. 그 결과 이상유동이 평형상태에 있는 것으로 가정하는 가장 단순한 모델인 HEM은 전반적으로 유동 불안정성 발생 시점의 열출력을 실험치보다 약 20% 정도 낮게 예측하였으며, 이상 유동의 속도 및 온도의 비평형 상태를 고려하는DEM과 DNEM에 의한 예측 결과는 7∼15%의 평균 오차 범위에서 실험 자료를 예측하는 것으로 나타났다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.10a
• /
• pp.136-136
• /
• 1998

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.3
• /
• pp.252-259
• /
• 2008

The deep-sea mining system is generally composed of surface vessel, lifting system, buffer, flexible pipe and miner. The mining system can be regarded as a large-scale system in which each subsystem is interconnected to other ones. In order to control a large-scale system, decentralized control approaches have been proposed recently. In this paper, as a basic study on application of decentralized control, firstly, the mining system was modeled in a simplified way. Lifting system and buffer were regarded as a spherical pendulum and the flexible pipe was taken as a two-dimensional linear spring connection. Based on the simplified model dynamics, the mining system can be decentralized two subsystems, the one consisting of surface vessel, lifting system and buffer, and the other, the miner. Next, this paper proposed the design of controller for each decentralized subsystem by regarding the interacting terms as disturbances. The controllers kept the constant distance between two subsystems during the miner was moving on the specified track. Finally, the efficiency of proposed controller was proven through the numerical simulation of the derived model.