• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1465-1468
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• 1996

In this paper, we suggest tele operation system of reclaimers and some side technologies for performing easy operation. The reclaimers in the raw ore yard are being used to dig ironstone and transfer it to the blast furnaces. The side technologies are to determine the minimum stacking distance between piles, collision avoidance of reclaimers and stackers. For simplicity, the pile and the boom of the reclaimer are mathematically modeled as a cone and a line in the 3-dimensional space respectively. The minimum stacking distance is obtained using the condition that the cone and the line never met. The modeling errors for the pile and reclaimers are compensated by considering the width of their reclaimer. We have also proposed a 2-stage collision detection method for the moving machines. The reclaiming heights of the pile are set to predetermined ones to make tele-operation easy.

• 대한기계학회논문집A
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• 제30권4호
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• pp.409-419
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• 2006

The actuating performance of plate-type unimorph piezoelectric composite actuators having various stacking sequences was evaluated by three dimensional finite element analysis on the basis of thermal analogy model. Thermal residual stress distribution at each layer in an asymmetrically laminated plate with PZT ceramic layer and thermally induced dome height were predicted using classical laminated plate theory. Thermal analogy model was applied to a bimorph cantilever beam and LIPCA-C2 actuator in order to confirm its validity. Finite element analysis considering thermal residual deformation showed that the bending behavior of piezoelectric composite actuator subjected to electric loads was significantly different according to the stacking sequence, thickness of constituent PZT ceramic and boundary conditions. In particular, the increase of thickness of PZT ceramic led to the increase of the bending stiffness of piezoelectric composite actuator but it did not always lead to the decrease of actuation distance according to the stacking sequences of piezoelectric composite actuator. Therefore, it is noted that the actuating performance of unimorph piezoelectric composite actuator is rather affected by bending stiffness than actuation distance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1554-1556
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• 2000

Normal zone propagation(NZP) characteristics were investigated on Ag sheathed multi filamentary Bi-2223 tape and cylindrical stacking conductor. The critical current($I_c$) of Ag sheathed Bi-2223 tape and cylindrical stacking conductor were 12 A, 63 A at 77 K, 0 T. Normal zone propagation(NZP) experiments with tape were conducted with refrigerator in temperature from 45 K to 77 K, 0 T. Cylindrical stacking conductor was molding with epoxy and experiments were conducted with adiabatic condition in $LN_2$. NZP velocities of tape with two condition of DC and AC were almost same at each temperature. Temperature ($T_1$) of tape with distance of 0.5 cm from heater was strongly climbed up to 95K and slowly decreased. NZP velocities of cylindrical stacking conductor were 1.9-2.4 cm/sec in $LN_2$.

• 대한화학회지
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• 제34권3호
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• pp.267-279
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• 1990

Amberlite XAD-2 및 XAD-7 수지에 대한 페놀과 그 할로겐 일치환체들에 대한 흡착성을 분포계수를 측정하여 조사하였다. XAD 수지에 대한 페놀의 흡착은 Langmuir 등온흡착으로 설명될 수 있었으며, 이 때의 흡착은 분자의 크기에 따르는, 즉 분산상호작용에 기인하는 전형적인 물리흡착임을 알았다. 고분자 합성수지에 대한 페놀류의 흡착에너지는 Lennard-Jones potential로 계산하였다. 이 때 고분자 수지의 반지름은 수지의 최소기본단위의 van der Waals 부피로부터 계산하였으며 페놀류의 분자 반지름도 같은 방법으로 구하였다. 페놀유도체들의 흡착성은 각 수지에 대한 시료의 Stacking factor (F)-고분자 수지와 페놀류사이의 van der Waals 부피로부터 구한 평형거리의 보정인자-로부터 흡착에너지를 구하고 뱃치법으로 측정한 흡착엔탈피값과 비교함으로써 설명할 수 있었다. 각 수지에 대한 페놀이온의 흡착엔탈피는 쌍극자 작용력이나 하전-쌍극자 상호작용보다 분산상호작용이 주 요인인 것으로 나타났다.

• 대한기계학회논문집A
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• 제27권4호
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• pp.623-631
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• 2003

It is considered that the application of advanced composite materials to the prostheses for the disables is important to improve their bio-mechanical performance. Particularly, energy storing foot prosthesis is mostly important to restore gait ability of the disables with low-extremity amputation since it could provide propulsion at terminal stance enhancing the disables ability to walk long distance even run and jump. Therefore, the energy storing spring of Prosthetic foot keel under cyclic bending moment use mainly of high strength glass fiber reinforced plastic. The main objective of this study was to evaluate the stacking sequence effect using the delamination growth rate(dA$_{D}$/dN) of energy storing spring in glass fiber reinforced plastic under cyclic bending moment. The test results indicated that the shape of delamination zone depends on stacking sequence in GFRP laminates. Delamination area(A$_{D}$) turns out that variable types with the contour increased non-linearly toward the damage zones.nes.

• Journal of Mechanical Science and Technology
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• 제14권9호
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• pp.1005-1012
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• 2000

Numerical optimization techniques combined with a three-dimensional thin-layer Navier-Stokes solver are presented to find an optimum shape of a stator blade in an axial compressor through calculations of single stage rotor-stator flow. Governing differential equations are discretized using an explicit finite difference method and solved by a multi-stage Runge-Kutta scheme. Baldwin-Lomax model is chosen to describe turbulence. A spatially-varying time-step and an implicit residual smoothing are used to accelerate convergence. A steady mixing approach is used to pass information between stator and rotor blades. For numerical optimization, searching direction is found by the steepest decent and conjugate direction methods, and the golden section method is used to determine optimum moving distance along the searching direction. The object of present optimization is to maximize efficiency. An optimum stacking line is found to design a custom-tailored 3-dimensional blade for maximum efficiency with the other parameters fixed.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.841-843
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• 2008

We elucidated a way to increase the mobility of $\pi$-stacked materials by comparing various single-crystal OFETs. A high field-effect mobility (of $3.7\;cm^2/Vs$) was obtained by increasing the effective $\pi$-stacking area and decreasing the $\pi$-stacking distance.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.98-100
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• 2008

A series of new channel materials using triisopropylsilylethynyl anthracene(TIPSAN) derivatives are synthesized by well known reaction. The TIPSAN derivatives exhibit an excellent field-effect mobility with hole mobility as high as 0.1 cm2V-1s-1 by solution-process and slip stack structure of core and end groups with short $\pi-\pi$ stacking distance of $3.525{\sim}3.485\;{\AA}$ by single crystal structures.

• Tribology and Lubricants
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• 제16권5호
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• pp.389-394
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• 2000

Scanning Probe Microscope (SPM) such as Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AEM) was shown to be the powerful tool for nano-scale characterization of material surfaces. Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform, and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.79-85
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• 2006

CFRP(Carbon Fiber Reinforced Plastics) of the advanced composite materials as structural materials for vehicle, has a wide application in light-weigh structural materials of airplanes, ships and automobiles because of high strength and stiffness, However, there is a design variable to be considered in practical application of the laminate composite materials, these materials are vulnerable to transverse impact. This paper is to study the effects of stacking sequence and curvature on the penetration characteristics of composite laminate shell. They are stacked to $[0_3/90_3]S,\;[90_3/0_3]s\;and\;[0_2/90_3/0]s,\;[90_2/0_3/90]s$ and their interlaminar number two and four. They are manufactured to various curvature radius (R=100, 150, 200mm and $\infty$), When the specimen is subjected to transverse impact by a steel ball, the velocity of the steel ball was measured both before and after impact by determing the time for it to pass two ballistics-screen sensors located a known distance apart. The critical penetration energy of specimen A and B with less interfaces were a little higher than those of C and D. As the curvature increases, the critical penetration energy increases linearly because the resistance to the in-plane deformation as well as bending deformation increases, which need higher critical penetration energy. The specimen A and C have higher critical penetration energy than B and D because of different stacking sequences. We examined crack length through a penetration test. For the specimen A with 2interfaces, the longest circumferential direction crack length were observed on the first interface from the impact point. For the specimen B 4-interface, the longest circumferential direction crack length were observed on the second interface from the impact point.