• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.114.3-114
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• 2001

The pure navigation system using Inertial Navigation Unit(INU) which has very accurate short term stabilities but not long term gives rise to position errors propotional to time. On the contrary, Global Positioning System(GPS) which is bounded its errors to some fixed ranges shows higher accuracy in the long term, and lower accuracy in the short term than that of INS. Recently the integration of these two systems is one of the main topic in the field of navigation system. In this thesis, the implementation of kalman filter on the real time navigation computer and step jump error compensation method is suggested.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.3
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• pp.136-145
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• 2006

Two major processing technologies of GaAs HBT and pHEMT have been released in production at Win Semiconductors corp. to address the strong demands of power amplifiers and switches for both handset and WLAN communications markets. Excellent performance with low processing cost and die shrinkage features is reported from the manufactured MMICs. With the stringent tighter manufacturing quality control WIN has successfully become one of the major pure open foundry house to serve the communication industries. The advancing of both technologies to include E/D-pHEMTs and BiHEMTs likes for multifunctional integration of PA, LNA, switch and logics is also highlighted.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.213-216
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• 2002

This paper describes a new approach to estimate induction motor speed from terminal voltages and currents for speed-sensorless vector control. This algorithm is based on Model Reference Adaptive System(MRAS). The proposed technique is simple and robust to the variation of motor parameters. Specially, this algorithm is not affected by the variation of stator resistance and it does not require any pure integration at all. The validity of this new approach is proved by simulations.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.99-104
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• 2001

Discrete-time controller design is proposed using feedback system identification in frequency domain. System Stability imposed by a new controller is checked in the function of a conventional closed-loop system, instead of a poorly modeled plant due to non-linearity and disturbance as well as unstable components, etc. The stability of the system is evaluated in view of Popov criterion. All the equations are formulated in the framework of the discrete-time system. Simulation results are shown on the plant with input saturation components, DC disturbance and a pure integration.

• Journal of Power Electronics
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• v.14 no.4
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• pp.796-805
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• 2014

A digital controller with a low-power approach for point-of-load synchronous buck converters is discussed and compared with its analog counterpart to confirm its feasibility for system integration. The tri-mode digital controller IC in $0.35{\mu}m$ CMOS process is presented to demonstrate solutions that include a PID, quarter PID, and robust RST compensators. These compensators address the steady-state, stand-by, and transient modes according to the system operating point. An idle-tone free condition for ${\Sigma}-{\Delta}$ DPWM reduces the inherent tone noise under DC-excitation. Compared with that of the traditional approach, this condition generates a quasi-pure modulation signal. Experimental results verify the closed-loop performances and confirm the power-saving mechanism of the proposed controller.

• Journal of Digital Convergence
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• v.18 no.1
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• pp.73-81
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• 2020

The purpose of this paper is to analyze the efficiency of on-off-line integrated operations of listed retailers, propose ways to identify and improve the problems of inefficient enterprises, and accelerate the integration of on-off-line. The 28 listed retail companies selected total capital, management expenses, number of employees and wage rates as input factors as of 2018 and total operating income and operating profit were selected as output indicators to analyze efficiency using DEA. The results show that the integrated enterprise has a higher overall level of operational efficiency, but it is still in a state of stagnation. The pure technical efficiency of the integrated enterprise is generally higher, and the scale efficiency is the main reason that the overall efficiency of the enterprise is not improved. This study can help retail companies adjust their development strategies of online and offline integration according to their own degree of online and offline integration. This study has limitations in explaining the change in efficiency of retailers by conducting a cross-sectional analysis using data limited to 2018. It is necessary to utilize data over the next several years to conduct a longitudinal analysis.

• School Mathematics
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• v.7 no.1
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• pp.1-15
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• 2005

In this paper, some characteristics of actual state of school mathematics terms in north Korean mathematics textbooks, which were issued in 2000-2002, are discussed. In north Korea, terms are expressed in north Korean orthography. Many Chinese style terms are translated into pure Korean terms, but there are still so many Chinese style terms. It is known that there is deep gap between north and south Korean terms. But actually it is not. This means that integration of north and south Korean terms can be easily realized. It is known that translating Chinese style terms into pure Korean term can be useful in mathematics teaching and learning, but north Korean experiences tell that we should act with prudence in doing so. We need sufficient discussion in case of north Korean terms which are totally different with south Korean terms. Semantical analysis is needed with preference survey.

• Journal of Periodontal and Implant Science
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• v.34 no.4
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• pp.699-709
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• 2004

The present study was performed to evaluate histomorphological difference in various surface-treated implants in beagle. Implants($Implantium^{(R)}$, Dentium Co. Korea) with pure titanium machined surface, acid treated surface, and $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid treated surface were used in this study. All mandibular premolars of $1.5{\sim}2$ year old male beagle dogs were extracted. At 3 months after extraction, the implants(${\Phi}$ 4mm, l 6mm) were installed. The beagle were sacrificed at 1, 3 months after installation and then tissues including implants were prepared for non-decalcified specimens. These specimens were analyzed comparatively under light microscope. The results of this study were as follow 1. Higher rate of osseointegration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid-treated surface. 2. Increased osseointegration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acidtreated surface with time. 3. Higher maturation of integration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid-treated surface. In conclusion, surface treatment of $Al_2O_3blasted$ with acid might be considered to shorten healing time and improve success rate as increasing contact of implant and bone.

• Journal of the Korean institute of surface engineering
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• v.54 no.4
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• pp.178-183
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• 2021

The temperature and frequency dependence of the dielectric constant of the BaTiO₃ substituted with two types of donor dopants, Nb⁵⁺ and Ta⁵⁺, respectively, were compared and analyzed. Dielectric specimens of four specific compositions, Ba_0.95Nb_0.05TiO₃, Ba_0.90Nb_0.10TiO₃, Ba_0.95Ta_0.05TiO₃, and Ba_0.90Ta_0.010TiO₃ were prepared by calcining at 1100 ℃ and sintering at 1300 ℃ to have a perovskite structure to measure capacitance. XRD and SEM analysis were used to observe the structure, with particular focus on the integration into the Nb⁵⁺ and Ta⁵⁺ substituted BaTiO₃ crystal lattice. X-ray diffraction peaks in the (200) and (002) planes were observed between 45.10° and 45.45° of the BaTiO₃ solid solution substituted with different fractions of Nb⁵⁺ and Ta⁵⁺. The dielectric properties were analyzed and the relationship between the properties and structure of the substituted BaTiO₃ was established. The fine particles and high density of the substituted BaTiO₃ were maintained like pure BaTiO₃, and in particular, a shift toward the low temperature side of the phase transition temperature range was clearly found, unlike pure BaTiO₃. In addition, the phase transition at a temperature higher than the Curie temperature relatively satisfies the modified Curie-Weiss law.

• Korean Journal of Materials Research
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• v.20 no.6
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• pp.319-325
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• 2010

3-D IC integration enables the smallest form factor and highest performance due to the shortest and most plentiful interconnects between chips. Direct metal bonding has several advantages over the solder-based bonding, including lower electrical resistivity, better electromigration resistance and more reduced interconnect RC delay, while high process temperature is one of the major bottlenecks of metal direct bonding because it can negatively influence device reliability and manufacturing yield. We performed quantitative analyses of the interfacial properties of Al-Al bonds with varying process parameters, bonding temperature, bonding time, and bonding environment. A 4-point bending method was used to measure the interfacial adhesion energy. The quantitative interfacial adhesion energy measured by a 4-point bending test shows 1.33, 2.25, and $6.44\;J/m^2$ for 400, 450, and $500^{\circ}C$, respectively, in a $N_2$ atmosphere. Increasing the bonding time from 1 to 4 hrs enhanced the interfacial fracture toughness while the effects of forming gas were negligible, which were correlated to the bonding interface analysis results. XPS depth analysis results on the delaminated interfaces showed that the relative area fraction of aluminum oxide to the pure aluminum phase near the bonding surfaces match well the variations of interfacial adhesion energies with bonding process conditions.