• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.308-313
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• 2006

The effect of coating time on surface properties of the TiN-coated high speed steel(SKH51) by arc ion plating is and presented in this paper. Surface roughness, micro-hardness, coated thickness, atomic distribution of TiN and adhesion strength are measured for various coating times. It has been shown that the coating time has a deep influence more than 60 minites on the micro-hardness, coated thickness, atomic distribution of Ti and adhesion strength of the SKH51 steels, but that the coating time has little influence on the surface roughness.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.345-350
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• 2000

The objective of this study makes investigation into the effect on the properties of underwater antiwashout concrete. which is followed by mixing time and mixing quantity. There is an tendency that (the compressive strength of underwater antiwashout concrete made and cured in fresh water or sea water) is increase when dry mixing time, mixing quantity, total mixing time is increase as unit weight grows. The difference of compressive strength (in case of no dry mixing time and 60 second) is averagely 46.8kgf/㎠ in the fresh water and 35.6kgf/㎠ in sea water. it's considered that dry mixing is dispersed by underwater antiwashout admixture.

• Korean Journal of Child Studies
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• v.28 no.5
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• pp.161-174
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• 2007

To analyze the effect of reminder type on the development of time-based prospective memory of children, 270(90 each 5-, 7-, and 9-year old) participants were randomly divided by age group into three subgroups : self-cued reminder, other-cued reminder, and control groups. Results showed that the performance of time-based prospective memory significantly increased with age, and the presentation of reminders was effective for improving the performance of time-based prospective memory. For younger children the presentation of other-cued reminder was more effective than self-cued reminder, but for the older children, presentation of self-cued reminder was more effective than other-cued reminder.

• Journal of Korea Multimedia Society
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• v.17 no.4
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• pp.433-440
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• 2014

Wireless communication offers the flexibility to the node movement at the spatial dimension more than the wire communication not only in IP architecture but also in Content-Centric Networking. Although it gives such advantage, the intra-domain movement of a node especially the data source node affects the communication to the access point node which in the end affects the acceptance ratio of the client node that requests the data packets from the data source node. In this paper, we use time-division access method to maintain the acceptance ratio of the client node as the effect of the intra-domain data source node movement in Content-Centric Networking. The simulation result shows that the acceptance ratio of the client node can be maintained using the time-division access method as long as the interval access time is less than the coherence time.

• MALSORI
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• no.47
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• pp.85-96
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• 2003

It is difficult to implement sound field effect on real time using linear convolution in time domain because linear convolution needs much multiply operations. In this paper three ways is introduced to reduce multiplication operations. Firstly, linear convolution in time domain is replaced with circular convolution in frequency domain. It means that it operates multiplication in place of convolution. Secondly, one frame will be divided into several frames. It will reduce the multiplication operation in processing that transforms time domain into frequency domain. Finally, QFT will be used in place of FFT. Three ways result much reduction in multiplication operations. The reduction of the multiplication operation makes the real time implementation possible.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.12
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• pp.695-702
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• 2009

Dynamic behavior of Libr-water absorption system using low-temperature hot water was investigated numerically. Thermal-hydraulic model of single-effect/double-lift 100 RT chiller was developed by applying transient conservation equations of total mass, Libr mass, energy and momentum to each component. Transient variations of system properties and transport variables were analysed during start-up operation. Numerical analysis were performed to quantify the effects of bulk concentration and part-load operation on the system performance in terms of cooling capacity, coefficient of performance, and time constant of system. For an absorption chiller considered in the present study, optimum bulk concentration was found to exist, which resulted in the minimum time constant with stable cooling capacity. COP and time constant increased as the load decreased down to 40%, below which the time constant increased abruptly and COP decreased as the load decreased further.

• Smart Structures and Systems
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• v.7 no.1
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• pp.59-82
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• 2011

In this study, an output-only modal identification approach is proposed for decentralized wireless sensor nodes used for linear structural systems. The following approaches are implemented to achieve the objective. Firstly, an output-only modal identification method is selected for decentralized wireless sensor networks. Secondly, the effect of time-unsynchronization is assessed with respect to the accuracy of modal identification analysis. Time-unsynchronized signals are analytically examined to quantify uncertainties and their corresponding errors in modal identification results. Thirdly, a modified approach using complex mode shapes is proposed to reduce the unsynchronization-induced errors in modal identification. In the new way, complex mode shapes are extracted from unsynchronized signals to deal both with modal amplitudes and with phase angles. Finally, the feasibility of the proposed approach is evaluated from numerical and experimental tests by comparing with the performance of existing approach using real mode shapes.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2156-2159
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• 2005

ADS(Address Display Period Separation) driving method has been considered to be the most appropriate driving technique for AC PDP. ADS driving method is composed of reset, address, sustain and erase period. Therefore, a long time should be allocated to an address period, which results in a reduction of brightness. To realize a high luminance and high picture quality, it is necessary to high speed addressing. However, address discharge time lag increases as the temperature decreases, which can cause the misfiring and low picture quality In this paper, the electric field effect and priming particle effect are investigated in order to reduce the address discharge time lag at low temperature. Address discharge time lag was reduced effectively when the priming particles are provided.

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.4
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• pp.4799-4804
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• 1978

In order to investigate the effect of delayed compaction on the strength of the lime soil mixtures, labroatory test with two kind of soils was performed at four levels of lime content, at five levels of water content, and at six love's of delayed times. The results are summarized as follows; 1. Maximum dry density and optimum moisture content decreased with increase of the delayed times. The decreasing rate of those values at the earlier delayed time were large, and those values showed almost constant after about four hours of delayed time. 2. According to the increase of the delayed time, the decreasing rate of maximum dry density and optimum moisture content was large ia S-2 sampl, but was a little in S-1 sample. 3. Unconfined compressive strength of lime soil mixtures decreased with the increase of the delayed time, and the decreasing rate of its strength increased with the increase of the lime content. 4. Water content corresponding to the maximum strength was a little higher than the optimum moisture content along the increase of lime content and delayed time but its value was large in fine soil.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1247-1251
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• 2016

This study aims to investigate the effect of sampling frequency to the time domain and frequency domain analysis of pulse rate variability (PRV). Typical time domain variables - AVNN, SDNN, SDSD, RMSSD, NN50 count and pNN50 - and frequency domain variables - VLF, LF, HF, LF/HF, Total Power, nLF and nHF - were derived from 7 down-sampled (250 Hz, 100 Hz, 50 Hz, 25 Hz, 20 Hz, 15 Hz, 10 Hz) PRVs and compared with the result of heart rate variability of 10 kHz-sampled electrocardiogram. Result showed that every variable of time domain analysis of PRV was significant at 25 Hz or higher sampling frequency. Also, in frequency domain analysis, every variable of PRV was significant at 15 Hz or higher sampling frequency.