• Smart Structures and Systems
• /
• 제14권4호
• /
• pp.659-678
• /
• 2014

The study is aimed at investigating the feasibility of a high TRL solution for a wing flap segment characterized by morphable camber airfoil and properly tailored to be implemented on a real-scale regional transportation aircraft. On the base of specific aerodynamic requirements in terms of target airfoil shapes and related external loads, the structural layout of the device was preliminarily defined. Advanced FE analyses were then carried out in order to properly size the load-carrying structure and the embedded actuation system. A full scale limited span prototype was finally manufactured and tested to: ${\bullet}$ demonstrate the morphing capability of the conceived structural layout; ${\bullet}$ demonstrate the capability of the morphing structure to withstand static loads representative of the limit aerodynamic pressures expected in service; ${\bullet}$ characterize the dynamic behavior of the morphing structure through the identification of the most significant normal modes. Obtained results showed high correlation levels with respect to numerical expectations thus proving the compliance of the device with the design requirements as well as the goodness of modeling approaches implemented during the design phase.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2006년 추계학술발표대회 개요집
• /
• pp.225-227
• /
• 2006

As rail steel at a crossing area must undergo much higher loading than those at regular railway, Mn-alloyed steel is normally used for its high load-carrying capability and reduced wear rate. However, as these Mn-alloyed steel is tend to have casting defects, manufacturing cost to produce defect-free Mn-alloyed steel becomes quite expensive. Therefore, in order to replace Mn-alloyed steel, we performed build-up welding using CH-90 and investigated regarding to wear characteristics of build-up weld metal.

• Tribology and Lubricants
• /
• 제12권3호
• /
• pp.85-91
• /
• 1996

An analysis for turbulent hybrid beatings with fluid inertia and swirl injection effect was derived for studying static characteristics of swirl-controlled hybrid journal. The swirl-controlled hybrid journal beating is considered to have more freedom in stability control in high speed rotating machinery. Current analysis is compared with experimental results with 3-recess hydrostatic journal bearing. The analysis revealed that the fluid momentum exchange at orifice discharge could produce pressure rise inside the recess region which can control the shear flow induced by journal rotation. The analysis also shows that the swirl-controlled hybrid journal beating has a capability of controlling load carrying capacity and stability by manipulating supply pressure and injection angle.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2005년도 추계학술발표대회 개요집
• /
• pp.177-179
• /
• 2005

As rail steel at a crossing area must undergo much higher loading than those at regular railway, Mn-containing casting steel is normally used for its high load-carrying capability and reduced wear rate. However, as these Mn-containing casting steel is tend to have casting defects, manufacturing cost to produce defect-free Mn-containing casting steel becomes quite expensive. Therefore, in order to investigate the possibilities of replacing expensive Mn-containing casting steel with a mild steel with a surface build-up using a Mn-alloyed steel electrode.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
• /
• pp.39-42
• /
• 2005

This test program is to investigate the benefits of using headed bars to replace conventional stirrups and using steel fibers to reinforce in the disturbed regions in the dapped ended beam, This distribution of reinforcement was selected for aspects associated with the portion of beam section in bridge structures. The beams containing T-headed bars have a superior performance such as improved ductility, larger energy adsorption and enhanced post-peak load carrying capability. The capacity of DEB with steel fibers also show increase of ductility, shear strength, and crack.

• 전기학회논문지
• /
• 제59권1호
• /
• pp.26-32
• /
• 2010

This paper proposes a new effective installed reserve rate in order to evaluate reliability of power system considering renewable generators, which include uncertainty of resource supply. It is called EIRR(effective installed reserve rate) in this paper. It is developed with considering capacity credit based on ELCC by using LOLE reliability criterion. While the conventional installed reserve rate index yields over-evaluation reliability of renewable generators, the proposed EIRR describes actual effective installed reserve rate. However, it is not the probabilistic reliability index as like as LOLE or EENS but another deterministic effective reliability index. The proposed EIRR is able to evaluate the realistic contribution to the reliability level for power system considering wind turbine generators and solar cell generators with high uncertainty in resource supply. The case study in model system as like as Jeju power system size presents a possibility that the proposed EIRR can be used practically as a new deterministic reliability index for generation expansion planning or operational planning in future.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.816-823
• /
• 2007

As the South Korean rolling stock industry is developing designs for full compliance with the European Standards, it is fitting to take a look at these two core standards. The paper presents an overview of the load cases and structural requirements developed in Europe for the design of safe and compatible rolling stock vehicles. These load cases and structural requirements have been compiled into two standards namely EN12663 and EN15227. Standard EN12663 was developed as a reference design requirements standard. The work was mandated and sponsored by the European Committee for Standardization and Standard issuing National Institutions. EN12663 specifies a series of proof and fatigue load cases for European rolling stock regulations compliant vehicle designs. As EN12663 does not address the crashworthiness issue, a dedicated crashworthiness standard, EN15227, was therefore developed in a similar manner through industry wide consultations managed by a Trans-European working group of experienced engineers and specialists. In both standards, the vehicle and/or trains are grouped into categories reflecting the vehicle types and/or their indented operational function. EN15227, developed to complement EN12663, addresses the "passive" crashworthiness capability of the vehicles and trains. EN15227 specifies reference crash scenarios similar to those found in the Technical Specification for Interoperability (TSI) of high speed trains operating in Europe. The overview also touches on a general comparison with the corresponding British Group Standard (GM/RT2100) and also the UIC leaflet based load cases. The exercise is extended to pertinent design load cases specified by the Federal Railroad Administration (FRA) in the US.

• 한국정밀공학회지
• /
• 제29권8호
• /
• pp.818-823
• /
• 2012

In order to predict necking behaviour of aluminium sheets, a crystal plasticity model is introduced in the finite element analysis of tensile test. Due to the computational limits of time and memory, only a small part of tensile specimen is subjected to the analysis. Grains having different orientations are subjected to numerical tensile tests and each grain is discretized by many elements. In order to predict the sudden drop of load carrying capacity after necking, a well-known Cockcroft-Latham damage model is introduced. The mismatch of grain orientation causes stress concentration at several points and damage is evolved at these points. This phenomenon is similar to void nucleation. In the same way, void growth and void coalescence behaviours are well predicted in the analysis. For the comparison of prediction capability of necking, same model is subjected to finite element analysis using uniform material properties of polycrystal with and without damage. As a result, it is shown that the crystal plasticity model can be used in prediction of necking and fracture behavior of materials accurately.

• Composites Research
• /
• 제14권4호
• /
• pp.27-34
• /
• 2001

토탈 라그랑지안 방법과 변형율을 가정한 Hellinger-Reissner 원리에 기초한 유한요소법을 이용하여 패치로 보강된 구형 복합재료 쉘의 후좌굴 거동 및 진동 특성을 살펴보았다. 패치 요소는 따로 다른 유한요소를 사용하지 않고 쉘의 중앙면과 다른 기준점을 잡아 두께 변수를 택하여 정식화를 하였다. 비선형 해법으로 원통형 호-길이법을 적용하였고, 후 좌굴 진동은 미소 진폭을 갖는다고 가정하였다. 구형 쉘 패넬에서 패치가 비선형 거동 및 진동수에 미치는 영향을 고찰하였고, 그 결과 패치는 하중지지도를 개선시키킨다. 패치로 보강된 패널의 1차 고유진동수는 등가 패널에 비하여 낮으나, 하중을 받는 경우 1차 고유진동수는 급격히 감소하지 않았다.

• Composites Research
• /
• 제28권2호
• /
• pp.52-57
• /
• 2015

Soft morphing robotics making use of smart material and based on biomimetic principles are capable of continuous locomotion in harmony with its environment. Since these robots do not use traditional mechanical components, they can be built to be light weight and capable of a diverse range of locomotion. This paper illustrates a flexible smart phone robot made of smart soft composite (SSC) with inchworm-like locomotion capable of two-way linear motion. Since rigid components are embedded within the robot, bending actuators with embedded rigid segments were investigated in order to obtain the maximum bending curvature. To verify the results, a simple mechanical model of this actuator was built and compared with experimental data. After that, the flexible robot was implemented as part of a smart phone robot where the rigid components of the phone were embedded within the matrix. Then, experiments were conducted to test the smart phone robot actuation force under different deflections to verify its load carrying capability. After that, the communication between the smart phone and robot controller was implemented and a corresponding phone application was developed. The locomotion of the smart phone robot actuated through an independent controller was also tested.