• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.110-110
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• 2011

The nanomechanical properties of fully lithiated and unlithiated silicon nanowire deposited on silicon substrate have been studied with atomic force microscopy. Silicon nanowires were synthesized using the vapor-liquid-solid process on stainless steel substrates using Au catalyst. Fully lithiated silicon nanowires were obtained by using the electrochemical method, followed by drop-casting on the silicon substrate. The roughness, derived from a line profile of the surface measured in contact mode atomic force microscopy, has a smaller value for lithiated silicon nanowire and a higher value for unlithiated silicon nanowire. Force spectroscopy was utilitzed to study the influence of lithiation on the tip-surface adhesion force. Lithiated silicon nanowire revealed a smaller value than that of the Si nanowire substrate by a factor of two, while the adhesion force of the silicon nanowire is similar to that of the silicon substrate. The Young's modulus obtained from the force-distance curve, also shows that the unlithiated silicon nanowire has a relatively higher value than lithiated silicon nanowire due to the elastically soft amorphous structures. The frictional forces acting on the tip sliding on the surface of lithiated and unlithiated silicon nanowire were obtained within the range of 0.5-4.0 Hz and 0.01-200 nN for velocity and load dependency, respectively. We explain the trend of adhesion and modulus in light of the materials properties of silicon and lithiated silicon. The results suggest a useful method for chemical identification of the lithiated region during the charging and discharging process.

• Korean Journal of Food Science and Technology
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• v.19 no.2
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• pp.171-175
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• 1987

An objective method for the evaluation of eating quality of cooked noodle was established by using a specially designed shear extrusion cell of Rheometer. From the force-distance curve, the maximum force, initial force, extrusion work, and the slope were determined. In a test with Korean dried noodles made from 17 types of Australian wheat flour, the maximum and initial forces and extrusion work could represent the firm-soft and chewy character, which govern mostly the preference of cooked noodle. On the other hand, the slope could distinguish the textural changes of cooked noodle during the storage after cooking. The parameters showed significant correlation with the protein content, water absorption, development time and extensibility of flour, but no correlation was obtained with the maximum viscosity of viscogram. For the estimation of textural preference, the correlation coefficient obtained from a multiple regression analysis using the maximum viscosity of viscogram and the maximum force of shear extrusion test as the two independent variables was not significantly higher than the coefficient obtained from a simple regression with the maximum force only.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.2
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• pp.17-22
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• 2013

We investigated the optimum bonding conditions for thermo-compression bonding of electrodes between flexible printed circuit board(FPCB) and rigid printed circuit board(RPCB) with Sn-58Bi solder as interlayer. In order to figure out the optimum bonding conditions, peel test of FPCB/RPCB joint was conducted. The peel strength was affected by the bonding conditions, such as temperature and time. The fracture energies were calculated through F-x (Force-displacement) curve during peel test and the relationships between bonding conditions and fracture behaviors were investigated. The optimum condition for the thermo-compression bonding with Sn-58Bi solder was found to be temperature of $195^{\circ}C$ and time of 7 s.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.497-498
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• 2006

Tribological properties of a Magneto-Rheological(MR) fluid in a polishing process are studied. For this polishing process, abrasive wear model is proposed as a function of shear force, normal force and actual mean velocity of MR particles at workpiece surface. Experimental conditions are changed by varying the gap distance between workpiece and tool and the rotational speed of tool. From the experimental results, a modified Stribeck curve is obtained, and the friction coefficient turns out to have linear relationship with a modified Sommerfeld number. The validity of the wear model is supported by additional experiments performed for measuring material removal rates.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.3
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• pp.173-184
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• 2005

A capillary action-induced tension develops in the tear layer between the contact lens and cornea, which leads to the restoring force due to difference in the layer thickness between either upper and lower or left and right side of the lens when it is displaced off the equilibrium position as a result of blinking. Suppose the lens was displaced a certain distance from the equilibrium position, lens starts to oscillate toward the equilibrium position with the decreasing amplitude due to the restoring force as well as the velocity dependent viscous damping force in the tear layer. A mathematical model which consists of the differential equations and their numerical solution was proposed to analyze the damped oscillations of lenses. The model predicts the time dependence of lenses after the blink varying the various parameters such as Be, diameters, masses and positions displaced from equilibrium. As the Be and mass of lens increases the rate of amplitude reduction decreases, which requires a more time for the lens to return to the equilibrium position. It seems that varying the lens' displacement and diameters affect the lens' motion very little.

• Journal of Biosystems Engineering
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• v.37 no.3
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• pp.155-165
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• 2012

This study was performed to offer the data for design of the seedling bed transfer equipment to make the automation of working process in a plant factory. The seedling bed transfer equipment pushing the seedling bed with bearing wheels on the rail for interconnecting each working process by a pneumatic cylinder was made and examined. The examined transfer force to push the seedling bed with a weight of 178.9 N by the pneumatic cylinder with length of 60 cm and section area of 5 $cm^2$ was measured by experiments. The examined transfer forces was compared with theoretical ones calculated by the theoretical formula derived from dynamic system analysis according to the number of the seedling bed and pushing speed of the pneumatic cylinder head at no load. The transfer function of the equipment with the input variable as the pushing speed $V_{h0}$(m/s) and the output variable as the transfer force f(t)(N) was represented as $F(s)=(V_{h0}/k)(s+B/M)/(s(s^2+Bs/M+1/(kM))$ where M(kg), k(m/N) and B(Ns/m) are the mass of the bed, the compression coefficient of the pneumatic cylinder and the dynamic friction coefficient between the seedling bed and the rail, respectively. The examined transfer force curves and the theoretical ones were represented similar wave forms as to use the theoretical formular to design the device for the seedling bed transfer. The condition of no vibration of the transfer force curve was $kB^2>4M$. The condition of transferring the bed by the repeatable impact and vibration force according to difference of transfer distance of the pneumatic cylinder head from that of the bed was as $Ce^{-\frac{3{\pi}D}{2\omega}}<-1$, where ${\omega}=\sqrt{\frac{1}{kM}-\frac{B^2}{4M^2}}$, $C=\{\frac{\frac{B}{2M}-\frac{1}{kB}}{\omega}\}$, $D=\frac{B}{2M}$. The examined mean peak transfer force represented 4 times of the stead state transfer force. Therefore it seemed that the transfer force of the pneumatic cylinder required for design of the push device was 4Bv where v is the pushing speed.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.521-528
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• 2017

In this study, vertical loading tests were conducted to investigate the nonlinear behaviors of the fastening systems that have generally been used in the concrete track of domestic railway lines. Nonlinear load-displacement curve models were derived based on the test results. The uplift forces generated in the fastening systems were evaluated by applying the derived nonlinear models as well as the existing linear models. The influence of the factors on the maximum uplift force of the fastening system was analyzed through a parameter study on the distance between neighboring sleepers, the horizontal distance between the center of the bearing and the nearest fastening system from the deck end, and the height of the bridge girder. From the evaluation results it is known that, for economical track and bridge design, due to deck end deformation, it is necessary to consider the nonlinear behavior of the fastening system in the calculation of the uplift force of the fastening systems.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.388-395
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• 2005

A numerical procedure is proposed as a mesh-size insensitive structural stress definition that gives a stress state at a weld toe with relatively large mesh size. The structural stress values obtained using different finite element types, i.e. shell element and solid element, are examined for typical weld structures. The calculation procedures are performed using the balanced nodal forces and moments obtained from finite element solutions. A consistent formulation based on work equivalent argument has been implemented to transform the balanced nodal forces and moments from shell to line force and line moments at each nodal position. The mesh-insensitivity, the effect of distance $\delta$(where the stress is calculated) and the potential limitations of the structural stress method are examined for various types of weldments. Based on the results from this study, it is expected to develop a more precise stress estimation technique for fatigue strength assessment of welded structures.

• The Korean Journal of Rheology
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• v.2 no.1
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• pp.46-52
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• 1990

배추의 조직감 특성을 기계적으로 측정하는 방법을 수립하기 위하여 여러 가지 형 태의 탐침에 의한 침투 및 절단시험에서 나타난는 힘-거리 곡선을 비교분석하였으며 그 결 과를 배추잎의 미세구조와 관능적특성과 연관하여 해석하였다. 배추잎의 침투심험에서 탐침 의 선단각, 선단면적 및 둘레에 따라 힘-거리 곡선의 형태는 크게 달라지며 선단면적과 둘 레가 커질수록 파열력이 크게 증대되었다. 절단시험에서는 표피와 내부유관속 조직을 절단 하는 세 개의 특징적인 피크를-나타내었다. 배추잎의 염장에 의하여 침투시험의 최대 변형 력은 크게 감소된 반면 파열력은 크게 증대되어 최대 변형력에 대한 파열력의 비(a/c) 는 증가되었으며 이것은 탐침의 선단면적과 둘레가 큰경우에 더욱 두드러지게 나타났다. 염장 에 의하여 탄성한계까지의 변형거리가 커졌으며 최초 변형에서의 탄성치(a/l)는 감소하는 경 향을 나타내었다. 절단시험에서는 염장에의하여 외피의 절단력이 상대적으로 증가하였다. 배 추 및 절인배추의 아삭아삭한 정도는 침투시험의 최대변형력과 a/l의 변화와 밀접한 관계가 있으며 질긴 정도는 침투시험의 파열력과 a/c 절단시험의 절단력과 관계가 있으며 아작아작 한 정도는 침투시험의 a/c와 관계가 있는 것으로 판단되었다.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.25 no.3
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• pp.131-137
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• 2019

Carton clamps, one of forklift attachments, allow users to quickly handle shipping units such as unitized loads, large shipping cases, or crates without the requirement of pallets. As the use of palletless handling by clamp trucks increases, so does the need for simulation research on clamp truck handling. The frictional characteristics for various contact conditions of corrugated paperboards and their constituent boards were analyzed to obtain the data needed in the computer simulation for the handling of carton clamp truck. The overall mean of static-frictional coefficients between selected corrugated paperboards was 0.38 (±0.01), which was 1.3~1.6 times greater than 0.23~0.29 of the frictional coefficients between boards. The overall mean of static-frictional coefficients between the corrugated paperboards and the rubber contact pad was 0.82 (±0.02), which was about 1.1 to 2.8 times greater than 0.29~0.78 of the static-frictional coefficient between the linerboard and the rubber contact pad. The overall mean of kinetic-frictional coefficients between the corrugated paperboards was 0.35 (±0.01), and 0.76 (±0.02) between the corrugated paperboards and the rubber contact pad.