• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.36-41
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• 2001

This article presents a new acceleration/deceleration method for real-time control of autonomous mobile robots. In this method, a function which produces the table of acceleration/deceleration in real-time is proposed. This function, while sat- isfying the basic concept of mechanics, can choose both various ranges of velocity and distance ranges for the selected velocities. Moreover it can control motors in real time. This function is convenient to be realized by programming. In addi- tion, it is faster than other functions because it can be written by assembly language.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.602-609
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• 2010

To investigate desalinization patterns of surface reclaimed saline-sodic soil (RSSS) with subsurface layer of macroporous medium, multi-layered soil columns were constructed. For the multi-layered soil columns, gypsum was treated at the rate of 5 cmolc $kg^{-1}$ in surface (top) while coal bottom ash (CBA) was placed into intermediate layer below the gypsum-treated surface soils followed by the reclaimed saline-sodic soil as bottom layer (BL). The lengths of top soil was 30 cm long while the lengths of the CBA were 20 and 30 cm long. The saturated hydraulic conductivities (Ksat) were $0.39{\times}10^{-4}$ and $0.31{\times}10^{-4}cm\;sec^{-1}$ for RSSS(30 cm)-CBA(20 cm)-BL(20 cm) and RSSS(30 cm)-CBA(20 cm)-RSSS(20 cm), respectively while the lowest $K_{sat}$. was $0.064{\times}10^{-4}cm\;sec^{-1}$ for RSSS(30 cm)-CBA(20 cm)+BL(20 cm). The time required to reach the lowest EC in eluent, 0.3 dS $m^{-1}$ from 33.9 dS $m^{-1}$ was shorter in multi-layered soil columns with GR-CBA than that of RS-SRS, representing that rate of desalinization was greater than 99%. Exchangeable Na decreased by 94.8~96.2 %, while exchangeable Ca increased by 98~129 %.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7B
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• pp.595-601
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• 2006

This study presents an ultrasonic location awareness system for the ubiquitous computing with absolute position. The flight time of ultrasonic waves is determined by a period detecting technique which is able to extend the sensing range compared with traditional methods. For location awareness, ultrasonic waves are sent successively from each ultrasonic transmitter and synchronized by radio frequency (RF) signal, where the transmitting part is fixed and the receiving part is movable. To expand the recognizing range, cell matching technique and coded ultrasonic technique are introduced. The experimentation for various distances is accomplished to verify the used period detecting technique of U-SAT system. The positioning accuracy by using cell matching is also verified by finding the locations of settled points and the usability of coded ultrasonic technique is verified. As a result, the possibility of ultrasonic location awareness system for the ubiquitous computing can be discussed as a pseudo-satellite system with low cost, a high update rate, and relatively high precision, in the places where GPS is not available.

• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.417-425
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• 1998

Monte Carlo analysis is performed for the first acquisition and tracking of the KOMP-SAT spacecrat in GSOC tracking station after separation from Taurus launch vehicle. The error bounds in position and velocity vector in Earth-fixed coordinate system at injection point are assumed based on the previous launch mission. Ten thousands injection orbital elements with normal distribution are generated and propagated for Monte Carlo analysis. The tracking antenna pointing errors at spacecraft rising time and closest approach time at German Space Operations Center(GSOC) Weiheim track-ing station are derived. Then the tracking antenna scanning angles are analyzed for acquisition and tracking of the KOMPSAT signal.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.95-102
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• 2006

To properly interpret and define climatic warming trends of the last $100\~150$ years.; climatic changes over the past several centuries must be constrained. High resolution surface air temperatures (SATs) to reconstruct global temperature trends extend back only to the late of 19th century. Fortunately, on long time scale and over large areas, ground surface temperatures (GSTs) track SATs. GST changes penetrate into the subsurface and are recorded as transient temperature perturbation. Therefore, borehole temperatures can be used to recover climate change over the last millennium in an area; paleoclimate change inferred from borehole temperatures can be used to interpret global warming over the last century, little ice age, and medieval warm period.

• The Journal of Korean society of community based occupational therapy
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• v.7 no.1
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• pp.1-8
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• 2017

Objective : The purpose of this study was to identify the effect of vestibular stimulation activity on visual perception. Methods : A total of 58 healthy adults in chungnam was participated in this study. I divided into the total 3 groups and studied. Group A was no vestibular stimulation, they sat on general chair and performed the visual perception task. Group B and C sat on general chair and ball chair respectively, after vestibular stimulation activity and they performed visual perception task. I measured the visual perception task with the time. Results : There was a significant difference between Group A and B and C. There was no significant difference between group B and C. Conclusion : The result shows that the vestibular stimulation activity is effective for an improvement in visual perception.

• Journal of the Korean Home Economics Association
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• v.27 no.1
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• pp.111-126
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• 1989

The aim of the present study is to research into the household work time change and its structure in urban home makers by the choosen eleven studies and KBS's Data 1981, 1983, 1985, 1987. This study were proceeded under some limitations, it is choosen eleven studies that is different region: large city, medium and small town, and the household work's categories of original auther were changed. And KBS's Data was composed of general formation without personal character of home maker: FLC, number of childeren, family type, education, region. Although this study have a certain meaning of implementation, research into the household work time change and its's structure. The major findings of this study can be autlined as follows: (1) Total household work time did'nt so much changed through the choosen eleven studies compared with the last twenty years ago. In the change of each province household work time, time connected with meals and dwelling did not showed consistancy of change. But cloth laundering and mending time of 80's were declined compared with 70's. Family care time of 80's was increased, home management and buying time was declined untill '85, but again increasing trend '87. In choosen eleven studies, the household work time structure of urban home makers can be outlined: time connected with Meals>Family care>Cloth laundering and mending>Dwelling>Home management and Buying. (2) KBS's time-series data were analized as follows: a) Total household work time of '87 was declining gradually in weekday (34 minutes), sat. (41 minutes), sun (1 house and 2 minutes) compared with '81. b) The change of each province household work time: the time of cooking and sewing home management were declining gradually in its Mean time and its ratio of acters. The acter ratio of household worker in '81, '83, '85 was composed Cooking > Cleaning > Laundering > Home management > Buying > Child care > Sewing. In '87 was composed Cooking > Cleaning > Laundering > Buying > Home management > Child care > Sewing. c) The structure of household work time revealed some differences in each year and a day of the week.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.177-180
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• 2020

This paper focuses on the 1,200-V level reverse conducting-insulated gate bipolar transistor (RC-IGBT). The structure of the RC-IGBT has an n+ collector at the collector terminal. The breakdown voltage, V_th, V_ce-sat, and turn-off time, and the electrical characteristics of a field-stop IGBT (FS-IGBT) and RC-IGBT are compared and analyzed using simulations. Based on the results, the RC-IGBT obtained a turn-off time of 320.6 ㎲ and a breakdown voltage of 1,720 V, while the FS-IGBT obtained a turn-off time of 742.2 ㎲ and a breakdown voltage of 1,440 V. Therefore, RC-IGBTs have faster on/off transitions and a higher breakdown voltage, which can reduce the size of the element.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.39.3-40
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• 2020

For the space weather research, KASI (Korea Astronomy and Space Science Institute) is developing the SNIPE (Small-scale magNetospheric and Ionospheric Plasma Experiment) mission, which consists of four 6U CubeSats of ~10 kg. Besides of space weather research, the SNIPE mission has another astrophysical objective, detecting Gamma-Ray Bursts(GRB). By cross-correlating the light curves of the detected GRBs, the fleet shall be able to determine the time difference of the arriving signal between the satellites and thus determine the position of bright short bursts with an accuracy ~100'. To demonstrate the technology of the GRB observation, CSI gamma-ray detectors combined with GPS and IRIDIUM communication modules are placed on each SNIPE CubeSat. The time of each spacecraft is synchronized and when the GRB is detected, the light curve will be transferred to the Mission Operation Center (MOC) by IRIDIUM communication module. By measuring time difference of each GRB signals, the technology for localization of GRB will be proved. If the results show some possibilities, we can challenge the new astrophysical mission for investigating the origin of GRB.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.563-564
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• 2008

This paper presents a new Insulated Gate Bipolar Transistor(IGBT) for power switching device based on Non Punch Through(NPT) IGBT structure. The proposed structure has adding N+ beside the P-base region of the conventional IGBT structure. The proposed device has faster turn-off time and lower forward conduction loss than the conventional IGBT structure.