• Korean Journal of Materials Research
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• v.23 no.9
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• pp.489-494
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• 2013

In this study, by using nickel chloride solution as a raw material, a nano-sized nickel oxide powder with an average particle size below 50 nm was produced by spray pyrolysis reaction. A spray pyrolysis system was specially designed and built for this study. The influence of nozzle tip size on the properties of the produced powder was examined. When the nozzle tip size was 1 mm, the particle size distribution was more uniform than when other nozzle tip sizes were used and the average particle size of the powder was about 15 nm. When the nozzle tip size increases to 2 mm, the average particle size increases to roughly 20 nm, and the particle size distribution becomes more uneven. When the tip size increases to 3 mm, particles with an average size of 25 nm and equal to or less than 10 nm coexist and the particle size distribution becomes much more uneven. When the tip size increases to 5 mm, large particles with average size of 50 nm partially exist, mostly consisting of minute particles with average sizes in the range of 15~25 nm. When the tip size increases from 1 mm to 2 mm, the XRD peak intensities greatly increase while the specific surface area decreases. When the tip size increases to 3 mm, the XRD peak intensities decrease while the specific surface area increases. When the tip size increases to 5 mm, the XRD peak intensities increase again while the specific surface area decreases.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.1-10
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• 2002

Relatively being economical in installation and easy in operation, hot-air heating system has been generally used in greenhouse for heating system regardless of high cost in maintenance and uneven distribution of air temperature. Therefore to overcome the disadvantages in maintenance and in distribution of air temperature and to improve efficiency of heating system, this experimental study is performed. This experimental study aims to improve the character of uneven temperature distribution in vertical direction and to reduce energy consumption for heating in a greenhouse. The experiment had been performed to investigate change of thermal environment and effects on reducing energy consumption for heating in greenhouse by additional surface insulation and reduction of indoor-air volume that come by installing transparent vinyl membranes with different height in each house. The results show that there is a wide difference in oil-energy consumption between houses according to condition of surface insulation and change of indoor-air volume. Furthermore, the results show that the efficiency of dual surface is higher than that of change of indoor-air volume in terms of energy saving.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.56-62
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• 2011

Terrain recognition ability is crucial to the performance of legged robots in an outdoor environment. For instance, a robot will not easily walk and it will tumble or deviate from its path if there is no information on whether the walking surface is flat, rugged, tough, and slippery. In this study, the ground surface recognition ability of robots is discussed, and to enable walking robots to recognize the surface state and changes, a central moment method was used. The values of the sensor signals (load cell) of robots while walking were detected in the supported section and were analyzed according to signal variance, skewness, and kurtosis. Based on the results of such analysis, the surface state was detected and classified.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.3
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• pp.115-119
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• 2002

An adsorption isotherm on the heterogeneous surface which has spatially periodic adsorption heat distribution was formalized. Usefulness of the formalized adsorption isotherm is discussed with the help of a model calculation. Statistical thermodynamics is used throughout.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.4
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• pp.247-252
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• 2016

In this paper, we propose a new defect detection technology for micro-defect on the surface of steel products. Due to depth and size of microscopic defect, slop of surface and vibration of strip, the conventional optical method cannot guarantee the detection performance. To solve the above-mentioned problems and increase signal to noise ratio, a novel retro-schlieren method that consists of retro reflector and knife edge is proposed. Moreover dual switching lighting method is also applied to distinguish uneven micro defects and surface noise. In proposed method, defective regions are represented by a black and white pattern. This pattern is detected by a defect detection algorithm with Gabor filter. Experimental results by simulator for sample defects of cold rolled steel show that the proposed method is effective.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.8
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• pp.334-340
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• 2006

Copper is widely used in electric wire, cable, conductor in electric devices. As the demand for electric power is increasing rapidly, electric power devices are getting amazingly bigger and complicated. The using of light-weight conductor can reduce the size and making cost of the electric devices. In high-frequency application, Electric current in a conductor tends to shift to the surface of the conductor, resulting in an uneven current distribution in the inner conductor. In the extreme case the current may essentially concentrate in the 'skin' of the inner conductor as a surface current. In high frequency application, therefore, inner area of copper conductor may replace with aluminum conductor, which reduces the weight of conductor. This paper describes the manufacture and evaluation of composite conductors made of copper and aluminum. The optimum extruding ratio was 16 at $300^{\circ}C$. The electrical resistance of manufactured composite bus bar was $57{\mu}{\Omega}$ at DC and $49.5{\mu}\{Omega}$ at 300Hz.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.1
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• pp.47-60
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• 2006

Due to the uneven illumination of FPD panel surface, it is difficult to detect the defects. The paper proposes a method to find the uneven illumination compensation using wavelets, which are done based on multi-resolution structure. The first step is to decompose the image into multi-resolution levels. Second, elimination of lowest smooth sub-image with highest frequency band removes the high frequency noise and low varying illumination. In particular, the main algorithm was implemented by lifting scheme for realtime inline process.

• Applied Science and Convergence Technology
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• v.26 no.2
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• pp.21-25
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• 2017

The shape of the reflection spectrum is complex and appears to overlap with several signals, because the surface state is uneven due to the natural oxide film, so that the spectrum becomes a complicated signal shape divided into regions 1 and 2 due to diffuse reflection. On the other hand, it is seen that the reflection spectrum after PEO surface treatment is overlapped with several signals. In addition, the reflectance of the energy band varies from 1.32 to 1.46 eV. Usually, the MgO-type oxide film was observed at an energy band of ~4.2 eV. The thickness of the oxide film was increased as the DC voltage was increased by the thin film thickness meter (QuaNix; 7500M) after Plasma Electrolytic Oxidation (; PEO) surface treatment. This is because the higher the DC voltage, the easier the binding of the $OH^-$ ions in the solution solution and the $Mg^+$ ions of the magnesium alloy. An important part of the bonding of ordinary ions is the energy source (plasma) which can promote bonding. However, when a certain threshold voltage or more is applied, the material is adversely affected. The oxide film of the surface may be destroyed without increasing the thickness of the oxide film, that is, whitening of the material may occur.

• Korean Journal of Materials Research
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• v.30 no.7
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• pp.327-332
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• 2020

Laser induced surface activation (LISA) technology requires refined selection of process variables to fabricate conductive microcircuits on a general polymer material. Among the process variables, laser mode is one of the crucial factors to make a reliable conductor pattern. Here we compare the continuous wave (CW) laser mode with the pulse wave (PW) laser mode through determination of the surface roughness and circuit accuracy. In the CW laser mode, the surface roughness is pronounced during the implementation of the conductive circuit, which results in uneven plating. In the PW laser mode, the surface is relatively smooth and uniform, and the formed conductive circuit layer has few defects with excellent adhesion to the polymer material. As a result of a change of laser mode from CW to PW, the value of Ra of the polymer material decreases from 0.6 ㎛ to 0.2 ㎛; the value of Ra after the plating process decreases from 0.8 ㎛ to 0.4 ㎛, and a tight bonding force between the polymer source material and the conductive copper plating layer is achieved. In conclusion, this study shows that the PW laser process yields an excellent conductive circuit on a polymeric material.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.124-129
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• 2013

Hexapod walking robots are superior to biped or quadruped ones in terms of walking stability. Therefore hexapod robots have the advantage in performing intelligent tasks based on walking stability. In this paper, we propose a hexapod robot that has one fore leg, one hind leg, two left legs, and two right legs and can perform various intelligent tasks. We build the robot by using 26 motors and implement a controller which consists of a host PC, a DSP main controller, an AVR auxiliary controller, and smart phone/pad. We show by several experiments that the implemented robot can perform various intelligent tasks such as uneven surface walking, tracking and kicking a ball, remote control and 3D monitoring by using data obtained from stereo camera, infrared sensors, ultra sound sensors, and contact sensors.