• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.93-102
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• 2023

Despite recent modifications to building structural standards emphasizing the seismic stability of building foundations, the current design focus remains solely on vertical support, resulting in insufficient consideration of horizontal loads during earthquakes. In this study, we evaluated the dynamic behavior of inclined tripod micropiles (ITMP), which provide additional seismic resistance against horizontal and vertical loads during earthquakes. A comparison of the dynamic characteristics, such as acceleration, displacement, bending moment, and axial force, of ITMP with a 15° installation angle and normal vertical micropiles with a 0° installation angle was performed using dynamic centrifuge model tests. Results show that under moderate seismic loads, the proposed ITMP exhibited lower acceleration responses than the vertical micropiles. However, when subjected to a long-period strong seismic excitation, such as sine (2 Hz), ITMP showed greater responses than the vertical micropiles in terms of acceleration and settlement. These results indicate that the use of ITMP reduces the amplif ication of short-period (high-f requency) contents compared with the use of vertical micropiles. Therefore, ITMP can be used to enhance seismic performance of structures.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.804-809
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• 2001

Optimal design of a portable structure which supports impact loading is presented. The structure requires impact loading capability, stiffness and minimum weight for portability. A collapsible tripod structure with locking mechanism is suggested. Taguchi method has been used to identify the most important design variables and the initial design. Subsequent optimization yields additional weight reduction under stress and displacement constrains.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.1
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• pp.13-24
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• 1992

1) 1/2 Scale Model 실험과 실제품 성형실험을 통하여 정밀 냉간단조에 의한 Tripod Slide Housing의 제조공정 설계기술을 확립하고, 4단계 성형공정으로 시제품 제작에 성공하였다. 2) Triod Slide Housing을 성형할 수 있는 4단계(전방압출, Heading, 후방압출, Ironing)의 금형을 설계 및 제작하여 시제품 생산에 적용하고, 관련 필요기술을 축적하였다. 3)XC 48 등 중,고탄소강의 소둔 실험을 통하여 소둔 조건에 따른 구상화율 및 경도의 변화에 대한 연구를 수행함으로써, 고탄소강의 냉간단조시에 필요한 최적 소둔 조건에 응용할 수 있는 자료를 축적하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.4
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• pp.343-350
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• 2015

Extensive discussion on the optimal types of offshore wind turbine(OWT) among monopile, tripod and jacket in the intermediate depth of water has been actively carried out in worldwide wind turbine industry. Selecting the optimal types of OWT among several substructural types, it is required to consider the economic and technical feasibility including dynamically stable design of a wind turbine system. In this study, the effects of loading levels and uncertainties of soil properties on the natural frequency of OWT have been quantitatively investigated. In conclusion, the natural frequency of monopile-type OWTs has a significant level of uncertainty, hence it is very important to minimize the level of uncertainties in soil properties when the monopile is selected as a foundation for an OWT.

• Journal of Biosystems Engineering
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• v.32 no.5
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• pp.339-347
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• 2007

A hexapod walking robot had been developed for gathering information in the field. The developed robot was $260{\times}260{\times}130$ ($W{\times}L{\times}H$, mm) in size and 14.7 N in weight. The legs had nineteen degrees of freedom. A leg has three rotational joints actuated by small servomotors. Two servomotors placed at ankle and knee played the roles of vertical joint for up and down motions of the leg and the other one placed at coxa played the role of horizontal joint for forward and backward motions. In addition, a servomotor placed at thorax between the front legs and the middle legs played the role of vertical joint for pumping the two front legs to climb stair or inclination. Walking motion of the robot was executed by tripod gait. The robot was controlled by manual remote-controller communicated by an infrared ray. Two controllers were equipped to control the walking of the robot. The sub-controller using PIC microcomputer (Microchips, PIC16F84A) received the 16 bit command signal from the manual remote controller, decoded it to 8bit and transmitted it to the main microcomputer (RENESAS, SH2/7045), which controlled the 19 servomotors using the PWM command signals. Walking speeds were controlled by adjusting the period of command cycle and the stride. Forward walking speed were within 100 cm/min to 300 cm/min. However, experimental walking speed had the error of 4-40 cm/min to compare with the theoretical one, because of slippage of the leg and the circular arc motion of servomotor of coxa.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.490-496
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• 2012

The main object of this research is to minimize the shock effects which frequently result in fatal damage in offshore wind turbine on impact of barge. The collision between offshore wind turbine and barge is generally a complex problem and it is often impractical to perform rigorous finite element analyses to include all effects and sequences during the collision. On applying the impact force of a barge to the offshore wind turbine, the maximum acceleration, internal energy, and plastic strain are calculated for each load case using the finite element method. A parametric study is conducted with the experimental data in terms of the velocity of barge, thickness of the offshore wind turbine, and thickness and Mooney-Rivlin coefficient of the rubber fender. Through the analysis proposed in this study, it is possible to determine the proper size and material properties of the rubber fender and the optimal moving conditions of barge.

• Archives of Plastic Surgery
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• v.44 no.2
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• pp.150-156
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• 2017

Background Digital amputation is a common upper extremity injury and can cause significant impairment in hand function, as well as psychosocial stigma. Currently, the gold standard for the reconstruction of such injuries involves autologous reconstruction. However, when this or other autologous options are not available, prosthetic reconstruction can provide a functionally and aesthetically viable alternative. This study describes a novel technique, known as a tripod titanium mini-plate, for osseointegrated digit prostheses, and reviews the outcomes in a set of consecutive patients. Methods A retrospective review of patients who underwent 2-stage prosthetic reconstruction of digit amputations was performed. Demographic information, occupation, mechanism of injury, number of amputated fingers, and level of amputation were reviewed. Functional and aesthetic outcomes were assessed using the quick disabilities of the arm, shoulder, and hand (Q-DASH) scale and a visual analog scale (VAS) score, respectively. In addition, complications during the postoperative period were recorded. Results Seven patients were included in this study. Their average age was 29 years. Five patients had single-digit amputations and 2 patients had multiple-digit amputations. Functional and aesthetic outcomes were assessed using the Q-DASH score (average, 10.4) and VAS score (average, 9.1), respectively. One episode of mild cellulitis was seen at 24 months of follow-up. However, it was treated successfully with oral antibiotics. No other complications were reported. Conclusions When autologous reconstruction is not suitable for digit reconstruction, prosthetic osseointegrated reconstruction can provide good aesthetic and functional results. However, larger series with longer-term follow-up are required in order to rule out the possibility of other complications.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.457-463
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• 2009

In this paper, a novel foot force distribution algorithm for hexapod walking robots is presented. The considered hexapod robot has fault-tolerant tripod gaits with a failed leg in locked-joint failure. The principle of the proposed algorithm is to minimize the slippage of the leg that determines the stability margin of the fault-tolerant gaits. The fault-tolerant tripod gait has a drawback that it has less stability margin than normal gaits. Considering this drawback, we use the feature that there are always three supporting legs, and by incorporating the theory of Zero-Interaction Force, we calculate the foot forces analytically without resort to any optimization technique. In a case study, the proposed algorithm is compared with a conventional foot force distribution method and its applicability is demonstrated.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.185.1-185.1
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• 2010

The 3MW OWEC demonstrator project in Korea will be the first offshore wind project with Korean turbine, Doosan WinDS3000, and constructed on the north-eastern sea of Jeju Island as the water depth of 15m. Integrated loadings of wind and wave are investigated to describe a design loads for both extreme and fatigue conditions using GH-Bladed. A dynamic behaviour of substructure strongly affects a substructure loadings. The jacket structure is designed in accordance with DNV guidelines. The results of this paper show overall design process of offshore substructure as a complex jacket concept and this design process can be implemented on a design of monopile and tripod structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.81-84
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• 2002

Activation energy value is different according to cement, admixture and water-cement ratio also the relation of age-temperature is as non-linear as activation energy value is large. So to make accurate explanation for the effect of temperature on concrete strength development property, it is necessary to investigation for activation energy value. This study compares activation energy value recommended by Freiesleben and ASTM with activation energy value obtained by consequence of mortar examination according to ASTM C 1074-93. As the result of this study, activation energy value obtained by the study is 37.19KJ/mol, and in case of activation energy value obtained by the study explain temperature's influence about concrete strength development more accurate than activation energy value recommend by Freiesleben and ASTM.