• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.469-477
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• 2013

In order to investigate the influence of feed water inequity on the settling performance for parallel arranged upflow sedimentation basin in domestic G_WTP(Water Treatment Plant), CFD(Computational Fluid Dynamics) simulation were employed and ADV(Acoustic Doppler Velocimeter) measurements were carried out. From the results of both CFD simulations and ADV measurements, the differences among inlet flow rates to each inlet structure make turbulent energy dissipation uneven overall sedimentation basin. Especially local velocities in the near of both side wall were observed over the design overflow rate(74.4 mm/min). Also, it was confirmed that this inequity of inlet flow would exert an serious influence on the turbidity of settled water which is out from 8 troughs. Even though experimental velocities in full scale basin about 20% higher than the simulated, the results of ADV measurement were in good accordance with those of CFD simulations.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.315-322
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• 2018

Bamboo culm comprises internodes and nodes and is tapered from the bottom to the top. Anatomically, bamboo culm comprises vascular bundles and parenchymal base tissue. The gross anatomical structure of a transverse section of any culm internode is determined by the shape, size, arrangement, and number of vascular bundles. The purpose of this research was to examine the morphology of culm and the distribution and shape of vascular bundles in Ampel bamboo (Bambusa vulgaris). Bamboo culms were harvested from the base. Test samples were obtained from a central 2-cm long segment of each internode across the entire length of the culm. Results showed an uneven spread of vascular bundles in the internode cross-section. Transitioning from the outer to the inner layer of the internode, the number of vascular bundles per unit area decreased and their shape was variable. The size of vascular bundles in the middle layer of the internode was greater than that of those in the outer and inner layers. The shape of vascular bundles was circular in the outer layer, which gradually transformed into vertical oval toward the middle layer and horizontal oval toward the inner layer. Vascular bundles were of type III and IV in the bottom of the culm and type III in the middle to the top of the culm.

• International Journal of Industrial Entomology and Biomaterials
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• v.32 no.1
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• pp.35-40
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• 2016

Hydrogels are crosslinked hydrophilic matrices for a variety of biomedical applications. Silk fibroin (SF), one of typical natural biomaterials, has been explored as base material for hydrogel. Photocrosslinked SF hydrogel containing poly(ethylene glycol) (PEG) was formulated through visible light initiated thiol-acrylate photopolymerization. The morphological, structural and thermal properties of SF - PEG hydrogel was investigated through scanning electron microscopy, X-ray diffractometry, thermogravimetry, and differential scanning calorimetry. The morphology of SF hydrogel showed dot and uneven surface with network cross-section. X-ray diffraction curves showed that the specific diffraction peaks of PEG were not changed by the intensity of the peaks were affected by sonication. Thermo-degradation behavior of SF - PEG hydrogel sonicated was significantly affected and became complex pattern compared to unsonicated ones. However, the melting endothermic temperature of SF - PEG hydrogel was not changed but the crystalline enthalpy was decreased by gelation and sonication.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.314-319
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• 2005

When a robot navigates in the real environment, it frequently meets various environments that can be expressed by simple geometrical shapes such as fiat floor, uneven floor, floor with obstacles, slopes, concave or convex corners, etc. Among them, the convex corner composed of two plain surfaces is the most difficult one for the robot to negotiate. In this paper, we propose a gait planning algorithm to help the robot overcome the convex environment. The trajectory of the body is derived from the maximum distance between the edge boundary of the corner and the bottom of the robot when it travels in the convex environment. Additionally, we find the relation between kinematical structure of the robot and its ability of avoiding collision. The relation is realized by considering the workspace and the best posture of the robot in the convex structure. To provide necessary information for the algorithm, we use an IR sensor attached in the leg of the robot to perceive the convex environment. The validity of the gait planning algorithm is verified through simulations and the performance is demonstrated using a quadruped walking robot, called "MRWALLSPECT III"( Multifunctional Robot for WALL inSPECTion version 3).

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.672-678
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• 2008

This paper proposes a new rehabilitation robot with upper and lower limb connections for gait training. As humans change a walking speed, their nervous systems adapt muscle activation patterns to modify arm swing for the appropriate frequency. By analyzing this property, we can find a relation between arm swinging and lower limb motions. Thus, the lower limb motion can be controlled by the arm swing for walking speed adaptation according to a patent's intension. This paper deals with the design aspects of the suggested gait rehabilitation robot, including a trajectory planning and a control strategy. The suggested robot is mainly composed of upper limb and lower limb devices, a body support system. The lower limb device consists of a slider device and two 2-dof footpads to allow walking training at uneven and various terrains. The upper limb device consists of an arm swing handle and switches to use as a user input device for walking. The body support system will partially support a patient's weight to allow the upper limb motions. Finally, we showed simulation results for the designed trajectory and controller using a dynamic simulation tool.

• Korean Journal of Agricultural Science
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• v.37 no.3
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• pp.451-455
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• 2010

Cabbage, the main material of coleslaw was not safely washed because it is uneven and tightly layered. In this study, vinegar was used to control the number of E. coli in cabbage for coleslaw production. When cabbage was soaked in 10% acetic acid, The number of bacteria was reduced by $10^{-3}$ was survived after 5min and $10^{-6}$ after 30min. After soaking, 15-20% (w/w of cabbage) of 10% acetic acid was remained in chopped cabbage. Spraying 10% acetic acid up to 3% of cabbage weight decreased the number of bacteria by 1/1000 after 60min. Spraying 3% (v/w of cabbage) of vinegar containing 10% acidity decreased the bacteria by 2/3 after 20min but no further decrease was observed. This result indicated that vinegar can be used only in the case that contamination is low.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1117-1120
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• 2001

Chemical mechanical planarization(CMP) has emerged as the planarization technique of choice in both front-end and back-end integrated circuit manufacturing. Conventional CMP process utilize a polyurethane polishing pad and liquid chemical slurry containing abrasive particles. There have been serious problems in CMP in terms of repeatability and defects in patterned wafers. Since IBM's official announcement on Copper Dual Damascene(Cu2D) technology, the semiconductor world has been engaged in a Cu2D race. Today, even after~3years of extensive R&D work, the End-of-Line(EOL) yields are still too low to allow the transition of technology to manufacturing. One of the reasons behind this is the myriad of defects associated with Cu technology. Especially, dishing and erosion defects increase the resistance because they decrease the interconnection section area, and ultimately reduce the lifetime of the semiconductor. Methods to reduce dishing & erosion have recently been interface hardness of the pad, optimization of the pattern structure as dummy patterns. Dishing & erosion are initially generated an uneven pressure distribution in the materials. These defects are accelerated by free abrasive and chemical etching. Therefore, it is known that dishing & erosion can be reduced by minimizing the abrasive concentration. Minimizing the abrasive concentration by using Ce$O_2$ is the best solution for reducing dishing & erosion and for removal rate. This paper introduce dishing & erosion generating mechanism and a method for developing a semi-rigid abrasive pad to minimize dishing & erosion during CMP.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.169-171
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• 1993

In order to estimate space charging process in the corona charging apparatus which has been used to make polymer electret cell, the electrical properties of 30[${\mu}m$] thick polypropylene film were obtained from TSC measurement after corona charging between copper knife electrode and aluminum cylinder electrode with the voltage of -8, -7, -6, -5 (kV). And, the electrostatic contour and the electric field vector were calculated using Finite Element Method with the electrical properties obtained from TSC spectra analysis. The edge effect around the edge of knife electrode affects electrostatic contour on the surface of specimen and the electric field concentration inside the polymer. As a result the uneven charging state in the electret cell due to the mistake of design was calculated, and the optimal design of corona charging apparatus opprobriate to various specimen was come to be practicable.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.129-136
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• 2000

Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed Information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan, and to calculate the effects of small vanes that are attached in original impeller - Splitter impeller. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The splitter impeller changes the acoustic characteristics as well as performance. Two-splitter type impeller and splitter impeller which splitter locates in jet region are good for acoustic characteristics.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.56-63
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• 1998

The purpose of this is to analyze experimentally how the change of cutting speed have effects on hole over size of cutting hole, surface roughness of workpiece and roundness during the deep hole machining of SM55C with solid BTA drill using BTA drilling system. Conclusion reached is as follows. (1) The diameter was expanded for 25$\mu$m at the first section and then was reduced 0$\mu$m and 15$\mu$m respectively at the 10m and 20m section comparing to the diameter of tool with respect to the variation of cutting length at 70m/min of cutting speed. 0.15mm/rev of feed. (2) It was proved that roughness was below 8.67$\mu$m for the whole section of cutting length. (3) The roundness has been below 12$\mu$m. Regarding the polygon phenomenon, it has been proved that not only uneven best at 70m/min of cutting speed. 0.15mm/rev of feed.