• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.53-56
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• 2001

The simple construction and low cost, fault tolerant power electronic drive has made the switched reluctance drive a strong contender for many applications. But the switched reluctance drive does exhibit higher levels of vibration and acoustic noise than most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial force when phase current is extinguished by commutation action. In this paper, a hybrid excitation method is proposed to reduce vibration and acoustic noise of the switched reluctance drive. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are reduced because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.635-636
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• 2006

A pulse with modulation(PWM) that keeps a constant angle of dwell and adjust duty ratio is a good method to control a speed of SRM. And a method of one pulse control is proper a operation on range of high speed in SRM for a good energy efficiency. Because PWM method is more safety than one pulse method, conversion of those is best choice according the speed range. So, some algorithm is need for smooth conversion of the mode of control. This paper presents a factor of conversion that proper the conversion of control mode between PWM and one pulse method This factor is from estimation of torque and proper at the variable range of conversion and show the better conversion characteristic than constant factor of conversion.

• Journal of ILASS-Korea
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• v.15 no.4
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• pp.163-169
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• 2010

Jetting stability is the most important factors in inkjet printing because printing quality is totally determined by shape of the droplets on the substrate. In order to acquire stable jet, viscosity and dynamic behavior of the ink must be considered. In addition, waveform to drive the inkjet printhead is also to be controlled. In this study, the driving waveform composed of rising time, dwell time and falling time is optimized to obtain a stable jetting using drop watcher system. Also, effect of ink viscosity on jetting is experimentally investigated by changing the temperature of ink cartridge. As a result, jetted drop having uniform velocity is acquired.

• Carbon letters
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• v.11 no.4
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• pp.304-310
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• 2010

To manufacture a carbon/carbon composite the coal tar pitch was used as the matrix precursor and the PAN (polyacrylonitrile)-based carbon fiber was used as the reinforcing material to weave 3-directional preform. For pressure carbonization HIP equipment was used to produce a maximum temperature of $1000^{\circ}C$ and a maximum pressure of 100 MPa. The carbonization was induced by altering the dwell temperature between $250^{\circ}C$ and $420^{\circ}C$, which is an ideal temperature for the moderate growth of the mesophase nucleus that forms within the molten pitch during the pressure carbonization process. The application of high pressure during the carbonization process inhibits the mesophase growth and leads to the formation of spherical carbon particles that are approximately 30 nm in size. Most particles were spherical, but some particles were irregularly shaped. The spread of the carbon particles was larger on the surface of the carbon fiber than in the interior of the matrix pocket.

• Korean Journal of Optics and Photonics
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• v.8 no.1
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• pp.52-57
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• 1997

We report an investigation of the statistical fluctuations of the two-mode laser output as the asymmetry parameter is varied. The above results relate to computer solutions of the coupled Langevin equations both with and without pumping fluctuations. We find that as the asymmetry parameter is changed positively, the mean intensity of one mode is increased because the normalized intensity auto-correlation is decreased so that the natural dwell time is lengthen. The laser output does respond to a sinusoidally injected asymmetry parameter for small pump parameter.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.1
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• pp.18-25
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• 2006

In mobile ad-hoc networks(MANETs), nodes are mobile and network topology changes very frequently. The mobility of nodes does affect the system performance. There has been considerable attention on the mobility models, however, most work is confined to the simulation or test-bed. In this paper, we propose an analytical method to evaluate the performances of MANETs such as the average radio range dwell time of mobile nodes, link holding time, and transmission failure probability considering the node's mobility. In the proposed model, MANETs consist of the multi-hop and multicasting routing paths. A simulation is done to validate our proposed analytical model.

• Journal of Information Science Theory and Practice
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• v.2 no.2
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• pp.33-47
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• 2014

Mobile devices are the most important equipment for accessing various kinds of services. These services are accessed using wireless signals, the same used for mobile calls. Today mobile services provide a fast and excellent way to access all kinds of information via mobile phones. Mobile service providers are interested to know the access behavior pattern of the users from different locations at different timings. In this paper, we have introduced an associated tree for analyzing user behavior patterns while moving from one location to another. We have used four different parameters, namely user, location, dwell time, and services. These parameters provide stronger frequent accessing patterns by matching joins. These generated patterns are valuable for improving web services, recommending new services, and predicting useful services for individuals or groups of users. In addition, an experimental evaluation has been conducted on simulated data. Finally, performance of the proposed approach has been measured in terms of efficiency and scalability. The proposed approach produces excellent results.

• Journal of the Korea Safety Management & Science
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• v.8 no.2
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• pp.71-80
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• 2006

There are many display panels in the flight cockpit and pilots get various flight information from those displays. The ergonomic layout of the displays must be determined based upon frequency of use and sequence of use. This study investigated the visual search patterns of the six display groups(one head-up-display: HUD, two multi function displays: MFDs, one engine group: EG, one flight display group: FD and others) in a fighting aircraft. Four expert pilots conducted Imaginary flight in the physical mock-up and the eye movements were collected using eye tracking system. Data of dwell time, frequency of use, and eye movement path were collected. Pilots spent most of time on HUD(55.2%), and others (21.6%), FD(14.2%), right MFD(4.7%), EG(3.2%), and left MFD(1.1%) in descending order. Similarly HUD(42.8%) and others(30.0%) were the most frequently visited displays. These data can be used in the layout of cockpit displays and the determination of optimal visual search pattern.

• Korean Institute of Interior Design Journal
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• v.15 no.2 s.55
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• pp.158-165
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• 2006

God, existing in the Tabernacle was designed not by man but was designed by Him Personally. The LORD said to Moses..... 'Then have them make a sanctuary for me, and I will dwell among them. Make this tabernacle and all its furnishings exactly like the pattern I will show you(Exodus25:1-9). These words represent the Godly Origin of the Tabernacle. He referred to it as'A copy and shadow of what is in heaven' (Hebrews8:5) , Furthermore, The Tabernacle, a copy and shadow of what is in heaven, used in the Old Times, was his body(John2:21). Therefore The Lord is the true designer of the Tabernacle(Exodus25:8-9), and is where He dwells(Exodus29:46), and is where the sinful man meets the Lord(Exodus30:6). It is where the Lord dwells(Exodus29:46) and where Forgiving takes place(Leviticus4:20,26,31). Because of this, The Tabernacle is the most important out of any piece of architecture designed by man.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.9
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• pp.438-444
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• 2001

The simple motor construction and low cost, fault tolerant power electronic drive has made the switched reluctance drive a strong contender for many applications. But the switched reluctance drive does exhibit higher levels of vibration and acoustic noise than that of most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial force when phase current is extinguished during commutation action. In this paper, a hybrid excitation method is proposed to reduce vibration and acoustic noise of the switched reluctance drive. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are reduced because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.