• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.79-84
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• 2011

In this paper we design MIMO antenna with high isolation between antennas by using an isolation aid for WLAN. Two dual-band PIFAs which operates IEEE 802.11n are arranged symmetrically along the central axis of antenna frame and ground plane. By inserting an isolation aid between two PIFAs the isolation is improved maximum 5dB and 7dB for 2.4GHz band and 5GHz band respectively. Total efficiency is above 60%. ECC is below 0.1.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.1068-1072
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• 2011

Hydrogen Fuel Cell Vehicle(HFCV) is system that uses electrical energy of fuel cell stack to main power source, which is different system with other vehicles that use high-voltage, large-current. Isolation performance of this system which is connected with electrical fire and electrical shock is important point. Isolation resistance of electric installation is divided according to working voltage, it follows criterion more than $100{\Omega}$/VDC (or $500{\Omega}$/VAC) about system operation voltage in a hydrogen fuel cell vehicle. Although measurement of isolation resistance in a hydrogen fuel cell vehicle is two methods, it uses mainly measurement by megger. However, the present isolation resistance measurement system that is optimized to use in electrical facilities is unsuitable for isolation performance estimation of a hydrogen fuel cell vehicle because of limit of maximum short current and difference of measurement resolution. Therefore, this research developed the isolation resistance measurement system so that may be suitable in isolation performance estimation of a hydrogen fuel cell vehicle, verified isolation performance about known resistance by performance verification of laboratory level about developed system, and executed performance verification through comparing results of developed system by performance verification of vehicle level with ones of existing megger. Developed system is judged to aid estimation and upgrade of isolation performance in a hydrogen fuel cell vehicle hereafter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.473-477
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• 2009

In general, the softer the stiffness of a linear vibration isolator the better the performance of isolation can be achieved. However, the stiffness of the isolator cannot be made too soft because it needs a sufficient stiffness to hold the load. This is the most critical limitation of a linear vibration isolator. Recently, a HSLDS (High-Static-Low-Dynamic-Stiffness) magnetic vibration isolator was proposed to overcome this fundamental limitation. The suggested isolator utilizes two pairs of attracting magnets that that introduces negative stiffness. Previously, this new type of vibration isolator was merely introduced and showed a possibility of practical use. In this paper, detailed dynamics of the HSLDS magnetic isolator are studied using computer simulations. Then, the isolation performance is examined for various design parameters to aid the practical use.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.1
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• pp.92-97
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• 2010

In general, the softer the stiffness of a linear vibration isolator the better the performance of isolation can be achieved. However, the stiffness of the isolator cannot be made too soft because it needs a sufficient stiffness to hold the load. This is the most critical limitation of a linear vibration isolator. Recently, a HSLDS(high-static-low-dynamic-stiffness) magnetic vibration isolator was proposed to overcome this fundamental limitation. The suggested isolator utilizes two pairs of attracting magnets that introduces negative stiffness. Previously, this new type of vibration isolator was merely introduced and showed a possibility of practical use. In this paper, detailed dynamics of the HSLDS magnetic isolator are studied using computer simulations. Then, the isolation performance is examined for various design parameters to aid the practical use.

• Structural Engineering and Mechanics
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• v.46 no.1
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• pp.19-37
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• 2013

The optimum design of base isolation system considering model parameter uncertainty is usually performed by using the unconditional response of structure obtained by the total probability theory, as the performance index. Though, the probabilistic approach is powerful, it cannot be applied when the maximum possible ranges of variations are known and can be only modelled as uncertain but bounded type. In such cases, the interval analysis method is a viable alternative. The present study focuses on the bounded optimization of base isolation system to mitigate the seismic vibration effect of structures characterized by bounded type system parameters. With this intention in view, the conditional stochastic response quantities are obtained in random vibration framework using the state space formulation. Subsequently, with the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem is transformed to appropriate deterministic optimization problems correspond to a lower bound and upper bound optimum solutions. A lead rubber bearing isolating a multi-storeyed building frame is considered for numerical study to elucidate the proposed bounded optimization procedure and the optimum performance of the isolation system.

• Journal of Power Electronics
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• v.2 no.2
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• pp.112-123
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• 2002

This paper presents a novel prototype of the utility AC power interfaced soft-switching sinewave pulse modulated inverter using the high-frequency flyback for the small scale distributed renewable energy power conditioner. The proposed cricuit with a high-frequency isolation link has a funtion of electrical isolation, which is more cost-effective and reliable for the small-scale distributed renwal energy utilization system from a safety point of riew. The discontinuous conduction mode(DCM) operation of the high-frequency flyback transformer is adopted to establish a simple and low-cost circuit configuration and control scheme. For the simplicity, the circuit operating principle is described on the basis of the modified conventional full bridge inverter, whitch is the typical conventional high-frequency full-bridge inverter employing the high requency flyback transformer to eanble the effictive function of the electrical isolation. Than, the new circuit topology of the unility-interfaced soft-switching sinewave pulse modulated inverter using IGBTs is proposed. The proposed cricuit topology is additionally composed of the auxiliary power regenerating snubber cricuits, which are also mathematically analyzed for the parameter desigen settings. Finally, the performance of the propose inverter is evaluated on the basis of computer-aid simulation. It is noted that the sinewave pulse modulated output current of the inverter is synchronous to the AC main voltage.

• YAKHAK HOEJI
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• v.54 no.1
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• pp.1-7
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• 2010

Valerian (Valeriana officinalis L.) is a perennial that has been used for medicinal purposes from the ancient times and valerian preparations including root and rhizome extracts are known to possess a variety of biological activities such as anticonvulsant, antidepressant, sleep aid, tranquilizer, and anti-HIV activities. Main components of the extracts were classified according to the structural features. Importantly, one of the main components, isovaleramide, has drawn our attention due to the concise structure, broad spectrum, and low toxicities. The general aspects including generation of this interesting molecule, a variety of activities, pharmacokinetic properties, derivatization, and fusion with other known drugs were described. Isovaleramide has been isolated from valerian probably as an isolation artifact after treatment of ammonia to prepare ammoniated tincture, and is known to exhibit anticonvulsant, anxiolytic, sedative, and sleep aid activities without distinct side effects such as excessive sedation and decreasing muscle tone. It was also found to be well absorbed into the circulation system without specific cytotoxicity and genotoxicity. The derivatives of isovaleramide, valpromide, valrocemide and valnoctamide were also briefly discussed.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.438-446
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• 2003

This paper presents the development of the remotely operated decontamination systems for use in a highly radioactive zone of the DUPIC Fuel Development facility of the Irradiated Material Examination Facility at the Korea Atomic Energy Research Institute. The remotely operated decontamination systems were designed to completely eliminate human interaction with hazardous radioactive contaminants. These decontamination systems are mainly classified into three systems depending on the task environment - a fabrication equipment decontamination system, a hot-cell floor decontamination system, and an isolation room floor decontamination system. A decontamination system for contaminated fabrication equipment utilizes dry ice pellet blasting method to decontaminate contaminated surface of the equipment. The decontamination systems for the hot-cell floor and isolation room floor employ a vacuum cleaning method to decontaminate the contaminated floor and collect loose dry spent nuclear fuel debris and other radioactive waste placed on the floor. The human operator from the out-of-cell performs a series of decontamination tasks remotely by manipulating decontamination systems located in-cell via a handcontroller with the aid of vision feedback information. The environmental, functional and mechanical design considerations, control system and capabilities of the remotely operated decontamination systems at a high radioactive environment are also described.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.568-572
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• 1994

This paper presents equipment for charging and discharging with high power factor aid high efficiency. This equipment is consisted of $3{\phi}$SPWM AC/DC converter for improving input current waveform and input power factor, and bidirectional DC/DC converter for electric isolation in the DC link Part. Therefore, Input power factor and the total efficiency in the proposed system can be increased more than in the conventional phase-controlled thyristor Charging - Discharging System.

• Journal of Applied Biological Chemistry
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• v.48 no.2
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• pp.93-96
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• 2005

Three limonoids and two phenolics were isolated from stem bark of Pellodendron amurense Rupr. (Rutaceae) and were defined clearly as calodendrolide (1), obacunone (2), limonin (3), methyl 4-hydroxybenzoate (4), and syringin (5) based on NMR spectroscopy results obtained with the aid of X-ray crystallographic analysis. This is the first report on the isolation of calodendrolide (1) from this plant.