• Journal of the Korean Society for Precision Engineering
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• v.30 no.11
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• pp.1187-1192
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• 2013

In the case of 4 wheel drive (4-WD) type car, power switching occurs to 4-WD by operating lever or switch that operates power switching device attached in transfer case which can operate motor by electric signal. So if the RPM of motor is high, power switching will not exactly occur and can cause damage to gear in transfer case according to circumstances. So in this study, we applied 2 level of planet gear type motor spindle of motor drive part of a power train. And conducted decelerating to increase torque to switch power safe and accurately. Also, we researched efficiency of gear by designing reduction gear ratio and gear type and by calculating contact stress and bending strength. Based on researched content, we made drive head of power switching device and a reduction module which uses type that uses motor spindle as sun gear and ring gear as cover.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.78.2-78.2
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• 2010

We report the detection of a low-amplitude 380.8-day radial velocity (RV) variations in oscillating K2 III star ${\alpha}$ Ari (HD 12929). We do not found the correlation between RV variations and equivalent widths of chromospheric activity indicators ($H{\alpha}$ and CaII 8662 ${\AA}line$). The bisector analysis shows that bisector velocity span (BVS) and RV variations are not strongly correlated with each other. These result suggest that the RV variations could have been produced either by planetary companion or by the surface spots. If this RV variation is indeed caused by a planetary companion, an orbital solution with a period of P = 381 days, a semi-amplitude of K = 41 m/s, and an eccentricity of e = 0.25 fits the data best. Assuming a possible stellar mass of $M_{\bigstar} = 1.4-5.6 M\odot$, we estimate the minimum mass for the companion of m sini = 1.8-4.5 $M_{Jup}$ with an orbital semi-major axis of 1.2-1.9 AU. If confirmed, our finding gives a support to search for exoplanets around giant stars with multi-periodic oscillations.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.9
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• pp.909-915
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• 2008

Recently, the interests in the development and application of unmaned robots are increasing in various fields including surveillance and reconnaissance, planet exploration, and disaster relief. Unmaned robots are usually controlled from distance using radio communications but they should be equipped with an autonomous travelling function to cope with unexpected terrains and obstacles. This means that they should be able to evaluate terrain's characteristics quantitatively using mounted sensors so as to traverse harsh natural terrains autonomously. For this purpose, this paper presents a method for extracting terrain information, that is, slope and roughness from elevation maps as a prior step of traversability analysis. Slope is extracted using the curve fitting based on the least squares method and roughness using three metrics and their weighted average. The effectiveness of the proposed method is verified on both a fractal map and the world model map of a real terrain.

• The Journal of Information Technology
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• v.6 no.4
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• pp.81-91
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• 2003

This paper is concerned with the implementation of power line communication system with 9.6Kbps. This system is suitable to establish the smart home using the power line having been installed in house. In the suggested power line communication system, we use the chirp signal with a linearity and spread spectrum frequency band of 100KHz~200KHz. We had the performance experiment for the implementation system. The experiment was achieved in the pseudo load network similar to real circumstance of power line communication. As the result, the communications under the circumstance were accomplished satisfactorily. We confirmed that the suggested 9.6Kbps power line communication system with the Chirped-SS method had the performance enough to commercialize the smart home.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.119.1-119.1
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• 2014

Toxic waste disposal: Many people think that when toxic waste is dumped into the ocean or into the air, it disappears. This belief is incorrect. Rather than disappearing, it accumulates over time and slowly destroys the environment. Ultimately, it leads to the destruction of human race. Plasma is environmentally friendly: Plasma is environmentally friendly because it is created and disappears. When plasma is formed on the earth, you need certain conditions such as accelerating electrons by an electrical discharge or a particle accelerator. When this is gone, plasma completely disappears, leaving no impact on the environment. Plasmas produce radicals: Even if plasma density is low at atmospheric pressure, many radicals (excited states of molecules) are created. These radicals are chemically very aggressive. So instead of using harmful chemicals, plasma can be utilized for less of an impact on the environment. Plasma can reach very high temperatures: Plasma is also useful because when you control the density, you can easily reach high temperatures up to $5000{\sim}6000^{\circ}C$ at atmosphere pressure. Because of this heat and the chemical aggressiveness of the plasma, there are many green applications for plasma technology. Pulsed power technology: Pulsed electric field for extraction, drying and killing bacteria. Treatment of biological tissue by pulsed electric fields: Extraction of substances from cells: Sterilisation, Medical applications, Growth stimulation, Food preparation. Each application has its specialities, especially with respect to pulse shape and electric field strength.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.233-236
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• 2008

Recently, the development and application of unmaned robots are increasing in various fields including surveillance and reconnaissance, planet exploration and disaster relief. Unmaned robots are usually controlled from distance using radio communications but they should be equipped with autonomous travelling function to cope with unexpected terrains and obstacles. This means that unmanned robots should be able to evaluate terrain's characteristics quantitatively using mounted sensors so as to traverse harsh natural terrains autonomously. For this purpose, this paper presents an algorithm for extracting terrain information from elevation maps as an early step of traversability analysis. Slope and roughness information are extracted from a world terrain map based on least squares method and fractal theory, respectively. The effectiveness of the proposed algorithm is verified on both fractal and real terrain maps.

• Journal of Biosystems Engineering
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• v.25 no.6
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• pp.445-456
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• 2000

A can type high-speed transplanting mechanism was developed. The mechanism consists of a cam and an epicycle gear train with one sun gear in the middle and four planet gears in a row but symmetric with respect to the sun gear. Two planting knives are pivoted on the two outer gears. When sun gear rotates with a constant velocity the planting knife rotates also with a constant velocity. This constant motion of the transplanting knife is accelerated partially by a cam fixed in the gear housing so that the locus of the planting knife becomes similar to that generated by a crank-type transplanting mechanism. This cam-type transplanting mechanism can solve the problems associated with the rotary-type transplanting mechanisms. The mechanism was designed with an aid of computer simulation and proved applicable to high speed transplanters by its mock-up model. The design process of the mechanism was presented and dynamic analysis was also carried out to show the advantages of the mechanism over the rotary type high-speed planting mechanism.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.442-444
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• 2007

How to observe the atmosphere is a subject of atmospheric research. The meteorological satellites and the ground states are used to do observation. However, both ways do not satisfy the requirement of scientists, especially the profiles of atmosphere on the ocean and the data for global atmosphere. Radio occultation (RO) technique, which has been used in planet science, is a method to solve the problem. In RO technique, the low Earth orbit (LEO) satellite receives the two frequency signal of Global Positioning System (GPS) satellite. The excess phase of the signal is calculated to retrieve the profiles of atmosphere parameters. In moist troposphere, the fluctuations appear in the phase of the signal and open loop (OL) is used to resolve it. The quality of the GPS signal generally deteriorates as the altitude decreases. In the procedure, the SNR of the GPS signal is used as the criterion. However, the SNR decreases with fluctuation which makes it difficult to locate the data of poor quality. In this paper, the phase of the signal will be used as part of the criterion.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3258-3275
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• 2015

The rise in recent technology has changed the ways, in which people communicate with one another. Social networking services (SNSs) have become one of the most representative means. General SNSs allow users to create their own unique profiles, search for fellow members, share information, etc., while other SNSs have functions that cater to different needs of users. As a result, users of SNSs have begun to pick and choose different SNSs and concurrently use multiple SNSs in order to fulfill all their needs. This exploratory study examined which SNSs are used together and the characteristics that predict the use of multiple SNSs. In addition, it observed the differences between consumers' usage of multiple SNSs in different cultures. An online survey was administered to SNS users in the United States and Korea. The results of the study showed that the use of multiple SNSs is not yet prevalent in Korea, the country that represented a collectivistic culture. In addition, in the U.S., the highest number of users reported that they were active on at least three SNSs.

• International Journal of Automotive Technology
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• v.2 no.2
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• pp.77-83
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• 2001

Effect of ethene on the $DeNO_X$ conversion process in a simulated diesel engine operating conditions was investigated experimentally and theoretically. With the addition of even a small amount of ethene the NO to $NO_2$ conversion enhances greatly. The energy required to convert one NO molecule is 27 eV with 250 ppm ethene added, while 137 eV without ethene at 473 K. The effect of energy density, temperature, and the initial concentrations of ethene and oxygen are also discussed and the results show that the increase of the mentioned parameters lead to the promotion of NO oxidation. A kinetic model used in this study shows good agreement with the experimental result. Byproducts like formaldehyde ($CH_2$ 0) and methyl nitrite ($CH_3$ ONO) predicted by model calculation are broken up into CO and $H_2O$ eventually when high energy is delivered to the gas mixture. Sensitivity analysis shows that the main reactions of NO oxidation when ethene is added we: $HO_2+ NO \arrow NO_2 + OH, RO_2 + NO \arrow NO_2 + RO$, where R is a hydrocarbon radical. Also the direct oxidizing reaction of NO with O cannot be neglected.