• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.3
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• pp.5-16
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• 2021

In this study, the applicability of the MBR(Membrane Bio Reactor) process of oxygen dissolve was evaluated through comparison and evaluation of the efficiency of oxygen dissolve device and conventional aeration device in the explosive tank within the MBR process. The organic matter and ammonia oxidation by oxygen dissolve device were evaluated, and the efficiency of persaturation was evaluated by applying real waste water (anaerobic digester effluent treatement from food waste). SCOD and ammonia removal rates for oxygen dissolve device and conventional aeration device methods were similar. However, it was determined that the excess sludge treatment cost could be reduced as the yield of microorganisms by oxygen dissolve device is about 0.03 g MLSS-produced/g SCOD-removed lower than that of microorganisms by conventional aeration device. The removal rates of high concentrations of organic matter (4,000 mg/L) and ammonia (1,400 mg/L) in anaerobic digester effluent treatment from food waste were compared to the conventional aeration device and the oxygen dissolve device organic matter removal rate was approximately 13% higher than that of the conventional aeration device. In addition, for MLSS, the conventional aeration device was 0.3 times higher than for oxygen dissolve device. This is believed to be due to the high progress of sludge autooxidation because the dissolved oxygen is sufficiently maintained and supplied in the explosive tank for oxygen dissolve device. Therefore, it was determined that the use of oxygen dissolve device will be more economical than conventional aeration device as a way to treat wastewater containing high concentrations of organic matter.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.1-5
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• 2012

A complex energy saving device has been developed for middle class vessels. The propulsive performance of the developed device is described through a model test. The pre-swirl stator, which recovers the rotational energy of the propeller slipstream, is a well-known energy saving device for large vessels. The pre-swirl stator for a large vessel is usually cast as a part of the stern frame and has a high cost. The manufacture of a cast stator for an existing vessel is almost impossible. The complex device that was developed can be fitted on astern frame by welding. The model tests show a 4-6% efficiency gain for middle class vessels with the developed appendages compared to those with bare hulls.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.445-446
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• 2012

Recently the interest in wireless power transfer have been studied. ECR (Electromagnetic Coupled Resonance) device, depending on the size of the frequency characteristics of the structure, increasing in volume and larger volume of wireless power transmission device to make use of ECR is a big barrier. So to solve this problem for ECR device miniaturization and high efficiency has been actively studied. In this paper, the size of the device for ECR IM (Impedance Matching) by applying a one-turn coil circuit, remove the device in the form of ECR Network Analyzer measured by removing the one-turn coil has demonstrated the possibility of the device in the form of ECR.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.90-96
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• 2014

This paper is about increasing transfer efficiency of wireless power transmission. The new method is proposed to detect the alignment of transmitter and receiver of wireless charger and so smart phone can display the position of wireless charging receiver on its LCD panel for the maximum charging efficiency. The previous method is only to show the transfer efficiency, but this method is to show not only the efficiency but also coordinates of receiver. The apparatus of the wireless charger is based on WPC(Wireless Power Consortium) standard and has planar air coil combined with magnet shield in Tx and Rx device so that the leakage flux is minimized on condition of under hundreds of kHz operating frequency. In this paper, it's showed that relation of magnet field and distance of each coils can be linearized and position information of Tx and Rx device is calculated thru trigonometry. Through the experiment, the obstacles of linearity are discovered and also showed that it can be optimized. and so the presented method is suitable for alignment detection method of Tx and Rx device in WPC wireless charger.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.373-378
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• 2004

Recently the electrostatic 2-axis MEMS stages have been fabricated for the purpose of an application to PSD (Probebased Storage Device). However, most of them have low area efficiency, which is undesirable as data storage devices, since all of the components (springs, comb electrodes, anchors, platform, etc.) are placed in-plane. In this paper, we present a novel structure of electrostatic 2-axis MEMS stage that is characterized by having large area platform. For large area efficiency, the actuator part consisting of mainly comb electrodes and springs is placed right below the platform. In this article, the structures and operational principle of the MEMS stages are described, followed by design procedure, structural and modal analysis using FEM(Finite Element Method). The area efficiency of the MEMS stage was designed to be about 55％, that is very large compared with conventional ones having a few percentage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.2
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• pp.94-97
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• 2018

Lead zirconate titanate/poly-vinylidene fluoride (PZT/PVDF) piezoelectric devices were fabricated by incorporating carbon nanotubes (CNTs), for use as flexible energy harvesting devices. CNTs were added to maximize the formation of the ${\beta}$ phase of PVDF to enhance the piezoelectricity of the devices. The phase transition of PVDF induced by the addition of CNTs was confirmed by analyzing the X-ray diffraction patterns, scanning electron microscopy images, and atomic force microscopy images. The enhanced output efficiency of the PZT/PVDF piezoelectric devices was confirmed by measuring the output current and voltage of the fabricated devices. The maximum output current and voltage of the PZT/PVDF piezoelectric devices was 200 nA and 350 mV, respectively, upon incorporation of 0.06 wt% CNTs.

• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.518-524
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• 2007

This paper describes several improved characterizations of the EPIC CCD, which now has modified electrode and channel structures. From a 3-D numerical simulation of the device, its channel doping and potential distributions are then observed for the optimization of the charge transfer. A wavelength-dependence on the device structure is observed in terms of the reflectivity of the incident radiation. The optical properties of ultra-low energy levels, when using an open-electrode structure, are then considered to improve their quantum efficiency.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1411-1414
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• 2007

We have developed a top-emitting white organic electroluminescent device (TWOLED) incorporating a low-reflectivity molybdenum (Mo) anode and doped transport layers as well as a dual-layer architecture of doped blue and yellow emitters with the same blue host. The EL efficiency and operational lifetime of TWOLED can be enhanced by a factor of 1.2 and 3.4 than that of standard TWOLED, respectively, with a co-doping technology in yellow emitter by doping another blue dopant. The enhancement in device performances can be attributed to improve the energy transfer efficiency from blue host to yellow dopant through a blue dopant as medium in yellow emitter.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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• pp.523-531
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• 2012

This paper proposes a high efficiency power conversion system for battery-ultracapacitor hybrid energy storages. The proposed system has only one bidirectional dc-dc converter for hybrid power source with batteries and ultracapacitors. The hybrid power source has bidirectional switching circuits for selecting one energy storage device. Bidirectional power flow between the energy storage device and high voltage capacitor can be controlled by one bidirectional converter. An asymmetrical switching method is applied to the bidirectional converter for high power efficiency. Switching power losses are reduced by zero-voltage switching of power switches. System operation and design considerations are presented. The experimental results are provided to verify the performance of the proposed system.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.766-769
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• 2002

We have seen the effects of hole-injection buffer layer in organic light-emitting diodes using copper phthalocyanine(CuPc), poly(vinylcarbazole)(PVK), and Poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS) in a device structure of ITO/buffer/TPD/$Alq_3$/Al. Polymer PVK and PEDOT:PSS buffer layer was made using spin casting method and the CuPc layer was made using thermal evaporation. Current-voltage characteristics, luminance-voltage characteristics and efficiency of device were measured at room temperature with a thickness variation of buffer layer. We have obtained an improvement of the external quantum efficiency by a factor of two, four, and two and half when the CuPc, PVK, and PEDOT:PSS buffer layer are used, respectively. The enhancement of the efficiency is attributed to the improved balance of holes and elelctrons due to the use of hole-injection buffer layer. The CuPc and PEDOT:PSS layer functions as a hole-injection supporter and the PVK layer as a hole-blocking one.