• 한국자동차공학회논문집
• /
• 제18권4호
• /
• pp.1-7
• /
• 2010

Large quantity of bending deformation as well as irregular rotating torque fluctuation are the main struggles of the balance shaft module during a high speed rotation. Since two issues are much sensitive to the location of both supporting bearing and unbalance mass at a balance shaft, it is recommended to construct a design strategy on balance shaft at the early stage so as to save developing time and effort before approaches to the detailed design process. In this paper, an optimal design formulation is proposed to minimize the elastic strain energy due to bending as well as the kinematic energy of polar moment of inertia in rotation. Case studies of optimal design are conducted for different mass ratio as well as linear combination of objective function and its consequence reveals that global optimum of balance shaft model is existed over possible design conditions. Simulation shows that best locations of both supporting bearing and unbalance are globally 20% and 80%, respectively, over total length of a balance shaft.

• 한국태양에너지학회 논문집
• /
• 제27권1호
• /
• pp.29-38
• /
• 2007

In order to analyze the performance comparison of dish solar collector with mirror arrays and receiver shapes, the radiative heat flux distribution inside the cavity receiver is numerically investigated. The solar irradiation reflected by dish solar collector is traced using the Monte-Carlo method. Five different dish solar collectors and three different cavity receivers are considered. A parabolic-shaped perfect mirror of which diameter is 1.5 m is considered as a reference dish solar collector and four different arrays of twelve identical parabolic-shaped mirror facets of which diameter are 0.4 m are used. Their reflecting areas, which are $1.5\;m^2$, are the same. Three different cavity receiver shapes are dome, conical, and cylindrical. In addition, the radiative properties of the concentrating surfaces can vary the thermal performance of the cavity receiver so that variation of the surface reflectivity of each mirror is considered. Based on the calculation, the design information of dish solar collector for producing the electric power can be obtained. The results show that the dome type has the best performance in receiver shapes and the 2AND4 INLINE has the best performance in mirror arrays except perfect mirror.

• International Journal of Ocean System Engineering
• /
• 제3권2호
• /
• pp.68-76
• /
• 2013

In this study, a 3D numerical model was used to predict nonlinear wave forces on a cylindrical pile installed in a shallow water region. The model was based on solving the viscous and incompressible Navier-Stokes equations for a two-phase flow (water and air) model and the volume of fluid method for treating the free surface of water. A new application was developed based on the cut-cell method to allow easy installation of complicated obstacles (e.g., bottom geometry and cylindrical pile) in a computational domain. Free-surface elevation, water particle velocities, and inline wave forces were calculated, and the results show good agreement with experimental data obtained by the Danish Hydraulic Institute. The simulation results revealed that the proposed model can, without the use of empirical formulas (i.e., Morison equation) and additional wave analysis models, reliably predict non-linear wave forces on an offshore wind turbine foundation installed in a shallow water region.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
• /
• pp.31-34
• /
• 2006

The characteristic of carbon nano fiber (CNF) as electron emitters was described. Carbon nano fiber (CNF) of herringbone was prepared by thermal chemical vapor deposition(CVD), mixed with binders and conductive materials, and then were formed by screen-printing process. In order to increase effectively field emissions, the surface treatment of rubbing & peel-off was applied to the printed CNF emitters on cathode electrode. The measurements of field emission properties were carried out by using a diode structure inline vacuum chamber. CNF of herringbone type showed good emission properties that a turn on field was as low as $2.5V/{\mu}m$ and current density was as large as $0.15mA/cm^2$ of $4.5V/{\mu}m$ with electric field. After the vacuum packaged panel of 5-inch in diagonal, the measured white brightness was as high as $7000cd/m^2$ at 1900V of anode and 700V of gate voltage.

• 펄프종이기술
• /
• 제46권5호
• /
• pp.51-60
• /
• 2014

To find a practical application approach of polyelectrolyte multilayering (PEM) on inorganic filler, we introduced PEM process without washing step and investigated the effect of shear condition on the washless PEM treatment of ground calcium carbonate (GCC). Washless multilayering on GCC was conducted under various shear conditions such as stirring, homogenization, and ultrasonication. Highly charged polyelectrolytes combination of polydiallyldimethylammonium chloride (PDADMAC) and poly sodium 4-styrene sulfonate (PSS) and low charged polyelectrolytes combination with cationic starch and anionic polyacrylamide (PAM) were compared. In the case of highly charged polyelectrolytes combination, shear conditions did not affect the zeta potential and the particle size of treated GCC. However, the modified GCC particles with low charged polyelectrolytes were more dispersed under higher shear condition while maintaining the zeta potential. In addition, GCC was successfully modified through laboratory inline washless polyelectrolyte multilayering system which consists of homogenizers and pumps.

• 대한물리의학회지
• /
• 제10권2호
• /
• pp.9-16
• /
• 2015

PURPOSE: The objective of this study was to identify the effects of shoulder abduction strength and EMG activities of the selected scapular and shoulder muscles during isometric shoulder abduction. METHODS: Thirty-four healthy young females were recruited for this study. Surface EMG equipment with inline force sensor was used to determine the shoulder abductor strength and the activity of the serratus anterior (SA), upper trapezius (UT), lower trapezius (LT), and middle deltoid (MD) during three shoe heel height conditions: (1) barefoot, (2) 3-cm shoe heel height, and (3) 7-cm shoe heel height. RESULTS: Isometric shoulder strength showed statistically significant difference among the conditions (p<0.05), and post-hoc test showed lower strength during the 7-cm condition ($49.98{\pm}17.56kg$) than during the barefoot ($44.97{\pm}20.15kg$) and 3-cm conditions ($36.59{\pm}17.07kg$). Furthermore, EMG activities of the SA, UT, and MD appeared to be statistically significantly different among the conditions, with lower values in the 7-cm condition compared to the barefoot condition (p<0.05). EMG ratios (MD/UT and SA/UT) were lower during the 7-cm condition than during the barefoot condition (p<0.05). CONCLUSION: These findings suggest that isometric shoulder abduction strength and EMG activities of scapular and shoulder muscles may be adversely changed with increasing shoe heel height.

• Journal of Acupuncture Research
• /
• 제36권4호
• /
• pp.282-285
• /
• 2019

Scoliosis is a 3-dimensional spinal deformity defined as lateral curvature of the spine in the coronal plane of more than $10^{\circ}$. This study describes a case of functional scoliosis after hip injury. In this case, the patient fell whilst inline skating (June 2015) causing severe tilting of her spine, and left hip pain. She received outpatient treatment from July 14, 2015 to December 28, 2015. For approximately 5 months, acupuncture therapy was performed to relax the tension in both hips, Chuna therapy, and foot orthosis were applied to reduce the body's imbalance. Based on X-ray images, the Cobb angle had decreased from $14.73^{\circ}$ (pretreatment) to $1.90^{\circ}$ (posttreatment). This case report suggested that Korean medicine treatment could be an effective therapeutic choice for functional scoliosis.

• Wind and Structures
• /
• 제29권1호
• /
• pp.65-75
• /
• 2019

A heated square cylinder (with height $A^*$) is kept parallel to the cold wall at a fixed gap height $0.5A^*$ from the wall. Another adiabatic rectangular cylinder (of same height $A^*$ and width $0.5A^*$) is placed upstream in an inline tandem arrangement. The spacing between the two cylinders is fixed at $3.0A^*$. The inlet flow is taken as Couette-Poiseuille flow based non-linear velocity profile. The conventional fluid (also known as base fluid) is chosen as water (W) whereas the nanoparticle material is selected as $Al_2O_3$. Numerical simulations are performed by using SIMPLE algorithm based Finite Volume approach with staggered grid arrangement. The dependencies of hydrodynamic and heat transfer characteristics of the cylinder on non-dimensional parameters governing the nanofluids and the fluid flow are explored here. A critical discussion is made on the mechanism of improvement/reduction (due to the presence of the upstream cylinder) of heat transfer and drag coefficient, in comparison to those of an isolated cylinder. It is observed that the heat transfer increases with the increase in the non-linearity in the incident velocity profile at the inlet. For the present range studied, particle concentration has a negligible effect on heat transfer.

• 한국산업융합학회 논문집
• /
• 제25권2_2호
• /
• pp.199-208
• /
• 2022

The steel wire or steel bar processing process applied to the manufacture of various bolts and power transmission shafts was improved by applying in-line phosphate film treatment technology. By applying a polymer lubricant for a non-reactive metal forming process and a non-reactive non-phosphorus lubricating coating agent, the film formation for each process time was comparatively analyzed and reviewed. Compared to the nine processes applied previously, the in-line phosphate film treatment technology applied with only two processes has been effectively improved in terms of reduction of treatment time, reduction of facility installation area, prevention of water pollution due to wastewater, and non-use of ozone-depleting substances. In addition, it was found that it can have an important effect on productivity improvement and price competitiveness from the simplification of quality control and process control as well as improvement of the working environment.

• 한국해양공학회지
• /
• 제30권2호
• /
• pp.91-99
• /
• 2016

The global demand for oil and natural gas has increased, and resource development is moving to the deep sea. Floating and flexible offshore structures such as semi-submersible, spar, and FPSO structures have been widely used. The major equipment of floating structures is always exposed to waves, currents, and other marine environmental factors, which cause structural damage. Moreover, flexible risers are susceptible to an exciting force due to the motion of the floating body. The inline and transverse responses from the three-dimensional behavior of a floating structure occur because of various forces. Typical risers are made of steel pipe and applied in the oil and gas development field, but flexible materials such as polyethylene are suitable for OTEC risers. Consequently, the optimal design of a flexible offshore plant requires a dynamic behavior analysis of slender bodies made of the different materials commonly used for offshore flexible risers. In this study, a three-dimensional motion measurement device was used to analyze the displacements of riser models induced by external force factors, and forced oscillation of a riser was linked to forced oscillation under a steady flow and regular wave condition.