• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.23-28
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• 2001

Since non-corrosive Fiber Reinforced Polymer(FRP) tendons have been in increasing use for underground and coastal structures constantly contacted with fresh water or sea water because of their superiority to metallic ones in corrosion-resistance, new non-metallic anchoring system for FRP tendons has been developed and investigated to verify the effectiveness of tendon force, which consist of mainly FRP pipes and Highly Expansive Mortar(HEM). The major factors considered in this experiment were expansive pressures of HEM during its hydration, sleeve lengths and types, and anchoring methods of tendon. New anchoring system were investigated from the pull-out tests. The pull-out procedures of the FRP tendons in the various pipe filled with HEM were analyzed and improved ideas were suggested to develop novel non-metallic anchoring system for FRP tendons The pull-out tests for the FRP tendon and new non-metallic anchoring system were conducted. The results show that non-metallic anchoring system for the FRP tendon has been more stablized due to the gradual expansive pressrure of HEM, as tims goes. Since tile lower stiffness of FRP pipes causes the weakness of anchoring force, it requires the increase of stiffness using a carbon fiber or an increased section area.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권2호
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• pp.269-281
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• 2014

This paper examines the suitability of using the Computational Fluid Dynamics (CFD) tools, ANSYS-CFX, as an initial analysis tool for predicting the drag and propulsion performance (thrust and torque) of a concept underwater vehicle design. In order to select an appropriate thruster that will achieve the required speed of the Underwater Disk Robot (UDR), the ANSYS-CFX tools were used to predict the drag force of the UDR. Vertical Planar Motion Mechanism (VPMM) test simulations (i.e. pure heaving and pure pitching motion) by CFD motion analysis were carried out with the CFD software. The CFD results reveal the distribution of hydrodynamic values (velocity, pressure, etc.) of the UDR for these motion studies. Finally, CFD bollard pull test simulations were performed and compared with the experimental bollard pull test results conducted in a model basin. The experimental results confirm the suitability of using the ANSYS-CFX tools for predicting the behavior of concept vehicles early on in their design process.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권7호
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• pp.307-314
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• 2001

A moving coil linear oscillatory actuator is consisted of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure and an iron core as a pathway for magnetic flux. The variation of mover position and the consequent changes of coil flux path affect the coil inductance, because coil flux leaks at the open region of LOA stator. The interaction between permanent magnet and armature field is to shift the airgap flux density variation due to the magnet alone by a certain amount. The unbalanced reciprocation force due to armature reaction field decreases the advantage of moving coil LOA, such as a high degree of linearity and controllability in the force ad motion control. This paper firstly describes the coil inductance, the deviation of flux density, and the unbalanced reciprocation force, which are derived form the permeance model of LOA. Secondly, the analytical method are verified using the 2D finite element method and tests. Finally, the dynamic simulation algorithm taking the armature reaction effect and variable inductance into account, is proposed and confirmed through the experiment.

• Clinics in Shoulder and Elbow
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• 제21권4호
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• pp.246-251
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• 2018

Compared to single row repair, use of lateral row anchors in suture bridge rotator cuff repair enhances repair strength and increases footprint contact area. If a lateral knotless anchor (push-in design) is inserted into osteoporotic bone, pull-out of the lateral row anchor can developed. However, failures of lateral row anchors have been reported at several months after surgery. In our cases, even though complete cuff healing occurred, delayed pull-out of the lateral row anchor in the suture bridge repair occurred. In comparison to a conventional medial anchor, further biomechanical evaluation of the pull-out force, design, and insertion angle of the lateral anchor is needed in future studies. We report three cases with delayed pull-out of lateral row anchor in suture bridge rotator cuff repair with a literature review.

• 한국지구과학회지
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• 제37권1호
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• pp.62-77
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• 2016

초기의 판 구조론에서 지각 판은 연약권 위에 떠서 맨틀의 움직임에 따라 움직이는 수동적인 모습으로 그려졌고, 자연히 해령에서 발산되는 힘이나 암석권 하부의 맨틀 견인력(drag force)이 판을 움직이는 주된 원동력으로 묘사되었다. 하지만 최근 여러 연구들은 판의 이동을 일으키는 원동력이 맨틀의 대류보다는 섭입대에서 침강하는 판이 만드는 섭입판 인력(slab pull)이라고 보고 있다. 최근 학계는 무거운 해양판과 주변 연약권의 밀도 차이가 섭입판 인력의 핵심이라고 설명한다. 해양판의 높은 밀도는 중력에 의해 판이 해구에서 맨틀 속으로 가라앉는 원인이 되며, 이것이 판이 움직이는 가장 큰 원동력을 발생시키는 것이다. 이러한 연구 결과들을 바탕으로, 본 연구는 고등학교 지구과학 교과서의 관련 내용을 검토하고 최근 수십 년 간의 서술 경향을 분석하였다. 그 결과 5차 교육과정 이래로 지금까지 거의 대부분의 고등학교 교과서가 맨틀 대류를 판 이동의 주 원동력으로 서술하고 있다는 것을 확인하였으며, 이는 대학교 교재가 개정판을 통해 새로운 학설을 꾸준히 제시해온 것과 대조적인 모습이라 할 수 있다. 따라서 학생들에게 더욱 정확한 학술적 정보를 제공하기 위해 이와 같은 새로운 판 구조론 내용이 해당 교과서 관련 단원에 추가되어야 할 것이다.

• 동력기계공학회지
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• 제13권4호
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• pp.62-67
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• 2009

In this paper we designed a prototype hybrid type linear pulse motor (HLPM) with single side stator structure for low cost. The measurement system which can get the motor characteristics of the HLPM was suggested. The static and dynamic characteristics of the thrust force are measured analyzed. And the microstep drive method is adopted and tested to the drive of prototype HLPM. The thrust waveform is measured respectively to know the differences of the thrust waveform between the microstep drive method and rectangular wave. From the experimental results, it can be confirmed that the repetitive ripple of the thrust force of the prototype HLPM is reduced by taking the microstep drive method.

• 한국지반환경공학회 논문집
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• 제17권10호
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• pp.55-62
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• 2016

매년 이상기후로 인하여 비탈면 붕괴 빈도는 좀처럼 줄어들지 않고 막대한 인명 및 재산 피해로 연결되어 피해규모도 점차 증가하고 있는 상황이다. 이를 억제하기 위해 기술자들은 보다 나은 보강재를 개선하고 인발력이나 전단력을 향상시키는 노력을 계속하고 있다. 본 연구에서는 쏘일 네일 공법을 발전시킨 것으로 네일 선단에 강화구를 장착하여 인발저항력을 증대하고 네일과 일체된 강화구는 접촉면적을 극대화 시켜 지반-그라우트체간 마찰력을 증대시킴으로써 비탈면 안정에 증가효과를 보인다. 보강효과를 검증하고자 일반적인 쏘일 네일과 강화구 네일의 실내인발시험과 현장실험을 통한 거동 특성과 적용성을 확인하기 위하여 실험을 진행하였다. 실험결과 강화구 네일의 경우 인발시험을 통해 일반 네일의 인장력과 비교하여 약 20% 증가하는 것을 분석하였다.

• 한국해안·해양공학회논문집
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• 제33권3호
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• pp.131-138
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• 2021

소파블록은 제체의 보호와 파랑에너지 소산을 목적으로 사용되므로 피복된 블록의 안정성을 평가하는 것은 매우 중요하다. 소파블록의 안정성은 주로 수리모형실험으로부터 산정되는 안정계수를 통해 평가되어 왔다. 본 연구에서는 새로운 형태의 소파블록인 K-블록을 활용하여 블록의 맞물림 효과를 포함한 안정성 평가를 위해 인발력에 기반한 새로운 안정성 실험방법을 제시하였다. 소파블록의 인발 실험은 일정 경사면 소파블록을 설치하고 수직 및 수평 방향으로 인장력을 작용시켜 사면 상의 피복층으로부터 블록이 분리되는데 필요한 힘을 직접 계측하는 방법이다. 제안된 실험방법은 소파블록의 맞물림 효과를 정량적으로 평가할 수 있음을 확인하였으며, 맞물림 영향에 의한 단층 피복블록(K-블록)의 높은 안정성을 검증하였다.

• Macromolecular Research
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• 제13권3호
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• pp.257-264
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• 2005

Polyurethanes containing z-Iysine segments in the main chain (PULL) were synthesized from 4,4'-diphe-nylmethyl diisocyanate, poly(tetramethylene glycol), and z-Iysine oligomer as a chain extender. The PULL film was treated first with a $10\%$ HBr-acetic acid solution and subsequently with a saturated sodium bicarbonate aqueous solution to produce a primary amine group on the surface (PULL-N). Lactobionic acid (LA)-immobilized PULL (PULL-L) was prepared by the coupling reaction of the PULL surface amine groups and the LA carboxylic acid groups. The surface-modified PULLs were then characterized by attenuated total reflection-Fourier transform infra-red spectroscopy, electron spectroscopy for chemical analysis, atomic force microscopy, and contact angle goniometry. In the hepatocytes adhesion experiment, the cells poorly adhered to the PULL surface, although they adhered moderately well to the PULL-N surface. On the other hand, the cells adhered well to the PULL-L surface, suggesting the good affinity of the surface $\beta$-galactose moieties for hepatocytes. When hepatocytes were cultured in the presence of epidermal growth factor for 48 h, the cells rapidly aggregated on the PULL-L surface, whereas they aggregated only slowly on the other surfaces. The PULL prepared in this study has the potential to be used as a coating material for the enhancement of hepatocyte adhesion.

• 대한조선학회논문집
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• 제58권3호
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• pp.158-166
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• 2021

In this paper, a numerical analysis technique using a body force model is investigated to estimate the available net thrust of multi-pod-driven ice-breaking vessels under bollard pull and overload conditions. To employ the body force model in present flow simulations, drag and thrust components acting on the pod unit are calculated by using Propeller Open Water (POW) test data. The available net thrusts according to the direction of operation are evaluated in both bollard pull and overload conditions under deep water. The simulation results are compared with the model test data. The available net thrusts, calculated by the present analysis for ahead operating modes at 3~6 knots which are typical speeds of the target vessel in arctic field, are agreed well with the model test results. It is also found that the present result for astern operating mode appears approximately 6 % larger than the model test result. In addition, the available net thrusts are calculated under the both operating conditions accompanied by shallow water effects, and the main cause of the difference is studied. Based on the result of the present study, it is confirmed that the body force model can be applied to the performance evaluation of multi-pod propulsion system and the main engine selection in early design stage of the vessel.