• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.610-617
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• 2011

This paper proposes a novel and direct dead-time compensation method of the 3-phase inverter using space vector pulse width modulation(SVPWM) topology. The proposed dead-time compensation method directly compensates the dead-time to the turn-on time of the effective voltage vector according to the current direction of the medium voltage reference. Each phase voltages are determined by the switching times of the effective voltage vectors, and the practical switching times have loss according to the current direction by the dead-time effect in the 3-phase inverter. The proposed method adds the dead-time to the switching time of the effective voltage vector according to the current direction, so it does not require complex d-q transform and controller to compensate the voltage error. The proposed dead-time compensation scheme is verified by the computer simulation and experiments of 3-phase R-L load.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.38-44
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• 2005

In a voltage source inverter, the dead time is necessary to prevent short circuits in the dc link. The dead time effect appears as a distortion of output voltages and currents. In recent years, the dead time compensation methods have been investigated in many literatures. This paper presents not the dead time compensation by sensing and calculation but the dead time elimination. The proposed inverter system doesn't need to sense load current and to calculate dead time. Adding some transformers to each leg, dead times in the inverter system are eliminated automatically. The proposed method is analyzed on each mode and verified through simulation results.

• Journal of Chest Surgery
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• v.25 no.8
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• pp.850-855
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• 1992

Dead space of empyema occurrs from incomplete obliteration of infected pleural space from pulmonary tuberculosis, pyogenic infection, esophageal disease and post pulmonary resection. Chronic empyema can be treated by obliteration of dead space with autologous tissues such as, extrathoracic muscle flap and omental flap and thorachoplasty. Between May, 1986 to July, 1991 we treated 17 chronic empyema patients with autologous tissues and analysed the result. 1. Sex distribution was 14 males and 3 females between 5~62 years old. [mean 39.7 years old] 2. The volume of the dead space ranged from 100 to 450cc. [mean 213. 76cc] 3. The majority of used muscle flap were serratus anterior and latissimus dorsi, and there were 2 cases of am ntal flap. 4. The majority of underlying disease were pulmonary tuberculosis and there were 8 BPF[47%] in 17 patients 5. In 7 cases, thorachoplsty was needed. 6. Three cases recurred and there were no death.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.451-457
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• 2006

We measured pumping speed of a sputter ion pump with a honeycomb anode cell structure and compared the result with that of another sputter ion pump with a typical cylindrical anode cell structure. A cell module with a honeycomb structure has no dead space which is about 10 % of the entire horizontal area of the cell module with a cylindrical structure. This dead space makes a little contribution to the ionization of the gas, so the pumping performance of the pump with dead space is expected to be lowered by the amount. From the experimental data we concluded that the honeycomb cell structure is superior to the cylindrical structure by $5{\sim}10%$ in performance.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.71-72
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• 2011

This paper presents a novel and direct dead time compensation method of the 3 phase inverter using space vector pulse width modulation(SVPWM) topology. In the turn on time calculation of the effective voltage, the dead time effect is directly compensated according to the current direction of the midium voltage reference. Since the turn on time of the effective voltage vector is affected by the dead time, the loss time is compensated to turn on time of the effective voltage vector. And the dead time is added to the calculated voltage vector switching times according to the current direction. For the more effective compensation, the direction of the midium phase current is considered by the practical direction and voltage drops in the power devices. The proposed method can compensate the dead time which is considered feedback error or direction of middle phase current without coordinate transform in added controller. The proposed dead time compensation scheme is verified by the computer simulation and experiments of 3 phase R L load.

• Journal of the Korean housing association
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• v.7 no.2
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• pp.19-27
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• 1996

The aim of this study is to analyze the intrinsic meaning of housing according to meaning of ritual space in Korean housing. At a traditional housing the rites give a sacred characteristic and grade of ranks to space. According to rites Malu(Dae-Chung) is a male's space and An-Bang is a female's space. At a present housing the central characteristic of An-Bang and sexual division of space are weakened and the space of dead person is disappered. But the rites and ritual space give sacred characteristic stability and identification in housing.

• Journal of the Korean housing association
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• v.26 no.4
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• pp.63-73
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• 2015

'Alley' is the community space as the fundamental living space for local residents and also it's the space which characterize the local community. Research is needed to rediscover the value of alleys which are disappearing due to urban planning. This research focuses on Seochon (current Saejong village) alleys and classify the types of alleys where residential density is seen. Further, this research aims the analysis of dwellings which use the alleys and the characteristics of the layout of alleys. Followings are the research results; 1) Major classifications are 'through alleys' and 'dead end alleys' and there is higher ratio for dead end alleys. 2) Majority of Seochon alleys have the width of more than 1.5 m and less than 3.6 m. 3) There are four types of alleys and straight alleys are most common. 4) Various type of alleys can be found where the width is wider. 5) In case of dead end alleys, there is a tendency of both sides layout rather than one side layout of dwellings. 6) Clusters of hanok can be found at Chebu-dong, Tongin-dong, Nuha-dong and Tongui-dong whereas modern dwellings and villas are more common in Nusang-dong and Ogin-dong. This research analyzes the current status of Seochon alleys and rediscover the value of alleys. This research also provides and presents the basic data materials for continuous sustainable method to keep alleys which characterize the local area.

• Journal of Power Electronics
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• v.9 no.3
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• pp.438-446
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• 2009

The performance of direct torque controlled (DTC) interior permanent magnet (IPM) machines is poor at low speeds due to a few reasons, namely limited accuracy of stator voltage acquisition and the presence of offset and drift components in the acquired signals. Due to factors such as forward voltage drop across switching devices in the three phase inverter and dead-time of the devices, the voltage across the machine terminals differ from the reference voltage vector used to estimate stator flux and electromagnetic torque. This can lead to instability of the IPM drive during low speed operation. Compensation schemes for forward voltage drops and dead-time are proposed and implemented in real-time control, resulting in improved performance of the space vector modulated DTC IPM drive, especially at low speeds. No additional hardware is required for these compensators.

• Journal of Power Electronics
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• v.13 no.1
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• pp.77-85
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• 2013

This paper proposes a new dead time compensation method of independent six-phase permanent magnet synchronous motors (IS-PMSM). The current of the independent phase machines contains odd-numbered harmonics because of the dead time and the nonlinear characteristics of the switching devices. By using the d-q-n three-dimensional vector analysis, these harmonics can be extracted at the n-axis current. Thus, the current distortion can be compensated by controlling the n-axis current of the IS-PMSM to zero. The proposed method is simple and can be easily implemented without additional hardware setup. The validity of the proposed compensation method is verified with simulations and several experiments.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.9
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• pp.618-625
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• 2000

Recently PWM inverters are widely utilized for many industrial applications e.g. high performance motor drive and PWM techniques are newly developed for an accurate output voltage. Among them space voltage vector PWM(SVPWM) inverter has high voltage ratio and low harmonics compared to the conventional sinusoidal PWM inverter. However output voltage of PWM inverter is distorted and has error duet o the conducting voltage drop of switching devices and the dead time that is inevitable to prevent the shoot-through phenomenon. This paper investigates 3-phase SVPWM inverter which has a new compensation method against dead time and voltage drop. Proposed algorithm calculates gate pulse periods which directly compensates the dead time and nonlinear voltage drop without modification of reference voltages. Direct compensation of gate pulse periods produces exact output voltage and does not need additional circuits. The propose algorithm is verified through the simulation and experiments.