• Journal of Aerospace System Engineering
• /
• v.13 no.4
• /
• pp.37-42
• /
• 2019

The objective of this study was to study the bending characteristics of Ag nano ink using EHD (Electrohydrodynamics) inkjet printing technology for flexibility and miniaturization of devices. The optimal conditions for the technology were derived, and bending characteristics of the Ag nano circuit obtained. For the EHD printing, it is essential to find the optimal point for each parameter such as material characteristics, density, flow rate, voltage, discharge height etc. Therefore, it was derived as the point from the working height and the applied voltage. Also, bending characteristics are confirmed by measuring resistance with each radius of curvature using a fabricated bending module. It was confirmed that rate of resistance change increases rapidly as the radius of curvature increases.

• Geomechanics and Engineering
• /
• v.28 no.2
• /
• pp.171-180
• /
• 2022

Time-dependent stress-strain behaviour significantly influences the compressibility characteristics of the clayey soil. In this paper, a series of oedometer tests were conducted in two loading patterns and investigated the time-dependent compressibility characteristics of Indian Montmorillonite Clay, also known as black cotton soil (BC) soil, during loading-unloading stages. The experimental data are analyzed using a new non-linear function of the Elasto-Visco-Plastic Model considering Swelling behaviour (EVPS model). From the experimental result, it is found that BC soil exhibits significant time-dependent behaviour during creep compared to the swelling stage. Pore water entrance restriction due to consolidated overburden pressure and decrease in cation hydrations are responsible factors. Apart from it, particle sliding is also evident during creep. The time-dependent parameters like strain limit, creep coefficient and C_αe/C_c are observed to be significant during the loading stage than the swelling stage. The relationship between creep coefficients and applied stresses is found to be nonlinear. The creep coefficient increases significantly up to 630 kPa-760 kPa (during reloading), and beyond it, the creep coefficient decreases continuously. Several parameters like loading duration, the magnitude of applied stress, loading history, and loading path have also influenced secondary compressibility characteristics. The time-dependent compressibility characteristics of BC soil are presented and discussed in detail.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.08a
• /
• pp.15-18
• /
• 2003

Fault current limiters (FCL) are extensively needed to suppress fault currents, especially for trunk power systems heavily connected to high voltage/large current transmission lines. Due to its ideal electrical behavior, high-temperature superconductor fault current limiter (HTSFCL) becomes one of the most important developing trends of limiters in power system. This paper describes the result of an investigation of the dielectric characteristics of turn-to-turn insulation for pancake and solenoid type reactor coil in liquid nitrogen. The influence of thickness in a variety length, on AC, DC and impulse surface flashover has been investigated. Also, the relationships between the number of turn and breakdown characteristics were clarified. The information gathered in this test series should be helpful in the design of liquid nitrogen filled DC reactor type HTSFCL.

• Korean Journal of Food Science and Technology
• /
• v.18 no.3
• /
• pp.173-180
• /
• 1986

To investigate on the biochemical characteristics of muscle fiber, myofibrils and actomyosins were prepared front red muscle and white muscle, and their ATPase activities and SDS-polyacrylamide gel electrophoretic patterns were compared. Also biochemical characteristics of bovine muscle were compared with those of chicken muscle for the detection of species characteristics. SDS-polyacrylamide gel electrophoretic analysis indicated that red muscle contained nlore 30K component of myofibril than white muscle. Differences in KCI concen-tration dependency of actomyosin ATPase activities and ATPase activity-pH cone were observed, when bovine muscle were compared with chicken muscle.

• Journal of Engineering Education Research
• /
• v.21 no.2
• /
• pp.60-66
• /
• 2018

This study aims to compare human resource development by industrial and occupational characteristics of science and engineering graduates. To achieve research objectives, this study analyzed whether differences exist in human resource development, such as participation in vocational training, wage levels, and cuture of talened person preference, by industrial and occupational characteristics. The results showed that workers in engineering fields received more benefits and support compared to those in non-science and engineering field occupations at the quantitative statistics of vocational training and wage levels. On the contrary, according to the qualitative statistics, workers of non-science and engineering field have a culture of talented person preference compared to those in science and engineering occupation.

• The Journal of Korea Robotics Society
• /
• v.12 no.2
• /
• pp.194-205
• /
• 2017

A redundantly actuated planar 3-degree-of-freedom parallel mechanism is analyzed to show its high application potential as a haptic device. Its structure along with the closed form forward position solutions is briefly discussed. Then its geometric and kinematic characteristics via singularity analysis, the kinematic isotropy index, and the input-output force transmission ratio are investigated both for the redundantly actuated cases and for the non-redundantly actuated case. In addition, comparative joint torque simulations of the mechanism with different number of redundant actuations as well as without redundant actuation are conducted to confirm the improved joint torque distribution characteristics. Through these analyses it is shown that the geometric and kinematic characteristics of the redundantly actuated mechanism are superior to the ones of the mechanism without redundant actuation. Thus, it can be concluded that the suggested planar mechanism with redundant actuation has a very high potential for haptic device applications.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.14 no.3
• /
• pp.68-74
• /
• 2006

The evaluation of durability performance in Virtual Testing Laboratory(VTL) is a new concept of vehicle design, which can reduce the automotive design period and cost. In this study, the multibody dynamics model of a car is built with a reverse engineering design. Hard points and masses of components are measured by a surface scanning device and imported into CAD system. In order to simulate the non-linear dynamic behavior of force elements such as dampers and bushes, components and materials are tested with specialized test equipments. An optimized numerical model for the damping behavior is used and the hysteresis of bush rubber is considered in the simulation. Loads of components are calculated in VTL and used in the evaluation of durability performance. In order to verify simulation results, loads of components in the vehicle are measured and durability tests are performed.

• Journal of Mechanical Science and Technology
• /
• v.18 no.2
• /
• pp.246-252
• /
• 2004

The modal characteristics of rotating structures vary with the rotating speed. The material and the geometric properties of the structures as well as the rotating speed influence the variations of their modal characteristics. Very often, the modal characteristics of rotating structures need to be specified at some rotating speeds to meet their design requirements. In this paper, rotating cantilever beam is chosen as a design target structure. Optimization problems are formulated and solved to find the optimal shapes of rotating beams with rectangular cross section.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.45-48
• /
• 2004

This study is a preview of characteristics of (1st/2nd) rubber suspension parts in low temperature, it will be researched before Trans Korean Railway and continental railway network connection. Rubber material characteristics are different to steel materials. Behavior of rubber material shows large deformation in hyper-elastic region. Moreover, added dashpot and low temperature condition shows various non-linear characteristics.

• International Journal of Fluid Machinery and Systems
• /
• v.9 no.2
• /
• pp.160-168
• /
• 2016

In high speed turbopumps, cavitation occurs and often causes the flow instabilities such as cavitation surge and rotating cavitation. The occurrence of these cavitation instabilities is considered to relate to dynamic characteristics of the cavitation, which are modelled using a cavitation compliance and a mass flow gain factor. Various types of cavitation such as a blade surface cavitation, a tip leakage vortex cavitation, and a backflow vortex cavitation occur at the same time in the inducer and the dynamic characteristics of each cavitation have not been clarified yet in experiments. Focusing on the blade surface cavitation as one of fundamental cavitation, we investigated the dynamic characteristics of the blade surface cavitation on a flat plate hydrofoil in experiments in the present study.