• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.44 no.2 s.314
• /
• pp.24-31
• /
• 2007

This paper presents self tuning PI(STPI) controller of IPMSM drive using neural network. In general, PI controller in computer numerically controlled machine process fixed gain. They may perform well under some operating conditions, but not all. To increase the robustness of fixed gain PI controller, STPI controller proposes a new method based neural network. STPI controller is developed to minimize overshoot, rise time and settling time following sudden parameter changes such as speed, load torque and inertia. Also, this paper is proposed speed control of IPMSM using neural network and estimation of speed using artificial neural network(ANN) controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The results on a speed controller of IPMSM are presented to show the effectiveness of the proposed gain tuner. And this controller is better than the fixed gains one in terms of robustness, even under great variations of operating conditions and load disturbance.

• Journal of the Korean housing association
• /
• v.19 no.2
• /
• pp.11-18
• /
• 2008

Due to an increasing amount of high rise apartment complexes and rapid city development, traditional houses and traditional housing districts have disappeared rapidly. Recognizing importance of traditional housing value, City of Seoul initiated public supports for traditional house preservation and revitalization of traditional housing district, especially Bukchon area. The purpose of this study is to examine the effects of public support for Bukchon area by investigating land value changes. Land value changes were compared among the three periods, 1) before the municipal support initiated ($1997{\sim}1999$), 2) initial period of governmental policy and support ($2000{\sim}2003$), 3) development period in which policy has activated and governmental preservation and revitalization efforts have exercised ($2004{\sim}2007$). For the comparison of land value changes, houses in other districts in City of Seoul have been selected. As a result, land value has been changed along with land value changes in other areas in Seoul. Land values of Bukchon area appeared in the middle range in Seoul area. However, the increasing rate of land value of traditional houses and traditional housing district are much higher than that of other areas. Except for economical support and legislation for preservation and revitalization of traditional housing district, there is few factors explaining the sudden increase of land values. The result indicated the positive impacts of municipal committment and policies on development and preservation projects and suggested that governmental policy and support should be practiced continuously for gradual development for the traditional housing district.

• Journal of the Korean Institute of Gas
• /
• v.23 no.6
• /
• pp.67-73
• /
• 2019

Hydrogen is difficult to accurately measure the amount of charge due to sudden temperature changes and pressure rise when charging the vehicle. In order to construct a hydrogen infrastructure, it is important to precisely measure the amount of charge that can be a sensitive issue in commercial transactions. In this study, the accuracy of metering of domestic hydrogen stations was evaluated as a study for metering management of hydrogen dispenser. For the experiment, we constructed metering system using master meter method and measured the flow rate in the actual hydrogen vehicle charging environment. As a result of error occurred about 10% on average, and the hydrogen loss per one charge was found to be up to 60g.

• Journal of Powder Materials
• /
• v.4 no.3
• /
• pp.179-187
• /
• 1997

Milling media of steel and zirconia were used to produce $MoSi_2$ by mechanical alloying (MA) of Mo and Si powders. The effect of milling media on MA of Mo-65.8at%Si powder mixture has been investigated by SEM, XRD, DTh and in-situ thermal analysis. The powders mechanically alloyed by milling medium of steel for 8 hours showed the structure of fine mixture of Mo and Si, and those mechanically alloyed by milling medium of zirconia for longer milling time showed the structure of fine mixture of Mo and Si. The tetragonal $\alpha$-$MoSi_2$ Phase and the tetragonal $Mo_5Si_3$ phase appeared with small Mo peaks in the powders milled by milling medium of steel for 4 and 8 hours. The $\alpha$-$MoSi_2$ phase and the hexagonal $\beta$-$MoSi_2$ phase were formed after longer milling time. The $\alpha$-$MoSi_2$ phase appeared with large Mo peaks in the powders milled by milling medium of zirconia for 4 hours. The phases, $\alpha$-$MoSi_2$ and $\beta$-$MoSi_2$. were formed in the powders milled for longer milling time. DTA and annealing results showed that Mo and Si were transformed into $\alpha$-$MoSi_2$ and $Mo_5Si_3$, while $\beta$-$MoSi_2$ into $\alpha$-$MoSi_2$. In-situ thermal analysis results demonstrated that there were a sudden temperature rise at 212 min and a gradual increase in temperature in case of milling media of steel and zirconia, respectively. The results indicate that MA can be influenced by materials of milling medium which can give either impact energy on powders or thermal energy accumulated in vial.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.7
• /
• pp.65-73
• /
• 2006

This paper presents speed control of IPMSM drive using neural network(NN) PI controller. In general, PI controller in computer numerically controlled machine process fixed gain. They may perform well under some operating conditions, but not all. To increase the robustness of fixed gain PI controller, NNPI controller proposes a new method based neural network. NNPI controller is developed to minimize overshoot rise time and settling time following sudden parameter changes such as speed, load torque and inertia. Also, this paper is proposed speed control of IPMSM using neural network and estimation of speed using artificial neural network(ANN) controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The results on a speed controller of IPMSM are presented to show the effectiveness of the proposed gain tuner. And this controller is better than the fixed gains one in terms of robustness, even under great variations of operating conditions and load disturbance.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.14 no.1
• /
• pp.100-108
• /
• 2006

Time-resolved current and voltage measurements for an inductive automotive spark system were made. Also presented are measurements of the total energy delivered to the spark gap. The measurements were made in air for a range of pressures from 1-18atm, at ambient temperatures. The measured voltage and current characteristics were found to be a function of many ignition parameters; some of these include: spark gap distance, internal resistance of the spark plug and high tension wire, and pressure. The voltages presented were measured either at the top of the spark plug or at the spark gap. The measurements were made at different time resolutions to more accurately resolve the voltage and current behavior throughout the discharge process. This was necessary because the breakdown event occurs on a time scale much shorter than the arc and glow phases. The breakdown, are, and glow voltages were found to be functions of spark plug resistance, gas density, and spark plug gap as expected from the literature. Spark duration was found to decrease as either pressure or gap was increased. The transition from the arc to glow phase is usually distinguished by a sudden rise in the voltage across the gap. At pressures above about 7atm this transition was not observed suggesting that a glow phase was not present. Energy delivered to the gap increased with increasing pressure. The effective resistance of the spark gap during discharge was about twice as large for the glow phase as the arc phase.

• The Bulletin of The Korean Astronomical Society
• /
• v.38 no.1
• /
• pp.52.1-52.1
• /
• 2013

We present preliminary results of the photometric variability analysis in SDSS r, i and z bands for a newly confirmed FU Orionis-type object, HBC 722. We observed HBC 722 from 2011 April to 2012 November, with Camera for Quasars in Early uNiverse (CQUEAN) attached to the 2.1m Otto Struve telescope at McDonald Observatory, USA. The rapid cadence monitoring observations (minute timescale) were conducted in chosen photometric nights during observation campaigns to get adequate number of samples for short term period analysis. As this object is in active state, temperature at the inner disk/stellar surface can be characterized by the colors between r, i and z bands. Also, It is theorized that a sudden cataclysmic accretion associated with FU Orionis-type outburst can give rise to detectable "hot spots" on the central star and rotational asymmetries in the disk instability region. Thus the periodic variabilities of three bands would trace the stellar rotation or Keplerian rotation at the instability region of the inner accretion disk. Additionally, the range of instabilities could be estimated on the assumption of a temperature distribution for the HBC 722 disk. This analysis can provide a clue for understanding enhanced disk accretion of Class II young stellar object.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.5-13
• /
• 2017

To lunch the Korea Space Launch Vehicle-II(KSLV-II), the second launch complex will be constructed on the Naro Space Center and Kerosene Filling System (KFS) will be also installed newly. KFS of KSLV-II launch complex system is being designed based on Naro Launch Complex. But this must supply fuel to fuel tanks of the vehicle with only a supply pump because KSLV-II is a 3-stage launch vehicle unlike Naro Launch Vehicle or Test Launch Vehicle (TLV). A sudden rise of pump output pressure is recognized during fuel filling scenario selection process. This occurs because return flow can not actively deal with a lot of flow change using flow control method of orifice type. To solve this problem, it is verified that fuel can be stably supplied by installation of accumulator and an appropriate adjustment of filling mode change sequence through flow analysis of various cases.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.20 no.43
• /
• pp.211-218
• /
• 1997

Since Industrial Revolution, the sudden industrialization and population explosion have brought about a serious environmental pollution on the air of the earth, the quality of water and the soil, and the greenhouse effect by the destruction of the ozone layer and the greenhouse gas, the organism diversity decline, the desertification by the ruining of woods and the overall global environmental pollution such as the contamination of the ocean and rivers have been come to the front. So the new recognition on the environment is being spreaded in construction business and the efforts for certification acquisition of ISO 14000 being followed by ISO 9000 are progressing, Accordingly, with an example of H Company where integration system is built so that it can minimize the efforts and cost at the construction of the management system, operation and management after the fact, this paper shall suggest the practical scheme of 3 steps through a study to integrate both existing quality management system and new environmental management system. As the integration system of the quality and environment which is constructed by this method is executed, the number of the established and managed document is cut by about a third and so the disorder to encounter between these documents is prevented and unnecessary efforts is reduced in constructing a system, consequently the efficiency of the system is accomplished. Also as the dualization of quality management system and environmental management system additionally needs more men and money after certification acquisition, the non-construction of the integration system may give rise to a cause to aggravate the burden of the company and hereafter when a new system is imported, it may be very difficult to integrate the system. This system integration enables a efficient and effective system to be constructed , operated , and managed after the fact.

• Journal of the Korean GEO-environmental Society
• /
• v.2 no.1
• /
• pp.57-65
• /
• 2001

In this study, the seepage behavior and the stability of the extension embankment were estimated for three cases the permeability coefficient of an extension part and the rising velocity due to the rainfall of flood period. In parallel flow condition, the unstability of the slope due to embankment erosion was examined by analyzing the variation of seepage line by the seepage modeling tests and FEM analysis, and the stability of the embankment slope accompanied by the sudden rise of the water level after the flood. The seepage behavior of extension embankment indicates that the larger permeability of the extension part the longer initial seepage distance, and the exit point from embankment slope is gradually increased, and then shows unstable seepage behavior that occurs a partial collapse as safety factor decreases with time. It is because of the increment of exit points due to variation of seepage line and rising velocities of water level. Also, the collapse aspect of embankment slope shows that the increment rising velocities of water level causes the increment collapse height and depth.