• 한국의상디자인학회지
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• 제17권3호
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• pp.29-43
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• 2015

This study investigates transformable designs in contemporary fashion. In contemporary society, designs are accompanied by various changes such as transformation of shapes or variation of material beyond the certain form of dress. As a result of having interest in transformable designs with the various attempts on the overall design, transformable design is being suggested as an attempt as the new manner, radical concept, or alternative of multi-purpose lifestyle. With the constant research and collection presentation by the designers of empirical disposition, transformable dress has been evolving gradually. The feature of transformable design appeared in dress is considered as 'variability' which changes in the flow of time. Furthermore, the morphological variability and variability of material have been examined as visual stimuli and conversion of material. By analyzing and assorting diverse transformable dresses comprehensively, it could be divided into technique-oriented transformable design and transformable design with a wearer's intervention. The technique-oriented transformable design is subdivided into the conversion of material and the conversion of form; the transformable design with a wearer's intervention into the conversion of functional frame and the conversion of aesthetic feature.

• 한국자동차공학회논문집
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• 제8권5호
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• pp.67-77
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• 2000

Investigated was the effect of propene(C3H6) on the NO-NO2 conversion in dry exhaust gases from lean burn engine using a pulsed corona discharge. A kinetic model was developed to characterize the plasma chemistry in simulated exhausts containing propene. The model uses ELENDIF program to solve Boltzmann equation for electron energy distribution function, and CHEMKIN-II program to solve stiff ODE(ordinary differential equation) problems for species concentrations. The corona discharge energy per pulse and the time-space averaged E/N were obtained by fitting the model to experimental data. The model calculation shows good agreement for NO and NO2 concentrations with the experimental data, and predicts the formation of byproducts such as CH2O, CH3HCO, CO AND CH3NO2 Propene enhances the NOx conversion enormously at lower energy density and the NOx conversion increases with the increase of initial propene and oxygen concentration, and temperature.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.17-17
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• 2012

Magnesium alloys exhibit many attractive properties such as low density, high strength/weight ratio, high thermal conductivity, very good electromagnetic features and good recyclability. However, most commercial magnesium alloys require protective coatings because of their poor corrosion resistance. Attempts have been made to improve the corrosion resistance of the Mg alloys by surface treatments, such as chemical conversion coatings, anodizing, plating and metal coatings, are commonly applied to magnesium alloys in order to increase the corrosion resistance. Among them, chemical conversion coatings are regarded as one of the most effective and cheapest ways to prevent corrosion resistance. In this study, zinc phosphate conversion coatings on various Mg alloys have been developed by selecting proper phosphating bath composition and concentration and by optimizing phosphating time, temperature. Morphology, coatings composition, corrosion resistance, adhesion and its formation and growth mechanism of the zinc phosphate conversion coatings were studied. Results have shown some attractive properties such as simplicity in operation, significantly increased corrosion protective property. However, adhesions between coatings and substrate and also between coatings and paint are still not satisfied. Resolving the problems and understanding the mechanism of phosphating process are targets of our study.

• 한국표면공학회지
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• 제49권1호
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• pp.1-13
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• 2016

This review deals with one of the surface modification techniques, chemical conversion coating and particularly cerium-based conversion coatings (CeCC) as a promising substitute for chromium and phosphate conversion coating on magnesium and its alloys. The CeCCs are commonly considered environmentally friendly. The effects of surface preparation, coating thickness, bath composition, and e-paint on the corrosion behavior of CeCCs have been studied on the AZ31 magnesium alloy. This review also correlates the coating microstructural, morphological, and chemical characteristics with the processing parameters and corrosion protection. Results showed that the as-deposited coating system consists of a three layer structure (1) a nanocrystalline MgO transition layer in contact with the Mg substrate, (2) a nanocrystalline CeCC layer, and (3) an outer amorphous CeCC layer. The nanocrystalline CeCC layer thickness is a function of immersion time and cerium salt used. The overall corrosion protection was crucially dependent on the presence of coating defects. The corrosion resistance of AZ31 magnesium alloy was better for thinner CeCCs, which can be explained by the presence of fewer and smaller cracks. On the other hand, maximum corrosion protection was achieved when AZ31 magnesium samples with thin CeCCs are e-painted. The e-paint layer further restricts and hinders the movement of chloride and other aggressive ions present in the environment from reaching the magnesium surface.

• 한국음향학회지
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• 제29권1호
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• pp.41-47
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• 2010

음성변환을 위한 피치변경법은 시간영역법과 주파수영역법, 혼성영역법이 많이 사용되고 있으며 시간-주파수 혼성영역법은 스펙트럼 왜곡이 적고 명료성과 자연성이 우수하다는 장점이 있는 반면 영역변환을 위한 처리시간이 매우 길다는 단점을 가지고 있었다. 본 논문에서는 시간-주파수 혼성 영역 피치변경법의 처리시간을 단축하는 방법을 제안하였다. 음성신호를 켑스트럼으로 변경하는 과정에서 사용되는 FFT와 IFFT의 비트-재정렬 과정을 생략함으로써 처리시간을 단축하는 방법이다. 이를 적용함으로써 기존의 켑스트럼 피치변경법과 같은 음성품질을 유지하면서도 처리시간은 86.26%로 단축할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1767-1770
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• 2003

This paper proposes an efficient network architecture for reflective memory system (RMS). Using this architecture, the time for broadcasting a shared-data to all nodes can be significantly shortened. The device named topology conversion switch (TCS) is implemented to realize the network architecture. The implemented TCS is applied to the ethernet based real time control network (ERCnet) to evaluate the performance.

• Journal of Power Electronics
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• 제16권4호
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• pp.1367-1374
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• 2016

This paper presents a discrete-time version of voltage and current limited operation using an enhanced direct torque and flux control method for interior permanent magnet synchronous motor (IPMSM) drives. A command voltage vector for airgap torque and stator flux regulation can be uniquely determined by the finite-settling-step direct torque and flux control (FSS-DTFC) algorithm under physical constraints. The proposed command voltage vector trajectories can be developed to achieve the maximum inverter voltage utilization for the discrete-time current limit (DTCL)-based FSS-DTFC. The algorithm can produce adequate results over a number of the potential secondary upsets found in the steady-state current limit (SSCL)-based DTFC. The fast changes in the torque and stator flux linkage improve the dynamic responses significantly over a wide constant-power operating region. The control strategy was evaluated on a 900W IPMSM in both simulations and experiments.

• 전기학회논문지
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• 제56권10호
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• pp.1757-1762
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• 2007

Recently, the demand for the low cost power conversion equipment is rapidly increased. To develop this three phase voltage source inverter, optimum power conversion equipment to system is designed. The optimum operation method to minimize the power loss also satisfy the life time of the power electronics that is request in the present industry. In this paper, the efficient operating method to change of the acceleration, jerk, and switching frequency in the interval of acceleration is selected to optimize the power loss and life time of the power electronics by using the elevator model. So, we proposed the method that 50[A] rating power electronics is adopted in 9[kW] load.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 추계학술대회 논문집
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• pp.5-6
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• 2012

In this paper, a simplified maximum power point tracking technique for the solar charger is presented. Main advantages of the proposed charger include low cost and optimized charge time. The maximum power point tracking method is used to deliver the maximum power from PV array to the battery thereby reducing the charge time. Moreover, the proposed technique which tracks the maximum power point by adjusting output current helps reduce the quantity of required number of sensors for the charger. The experimental protype was implemented by using an 80W PV array, a buck converter and a digital signal processor to verify the feasibility of the proposed method.

• Korean Chemical Engineering Research
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• 제56권5호
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• pp.738-751
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• 2018

The effect of the reaction temperature and reaction time on the thermal oxidative purification quality of detonation nanodiamond (NDsoot) was investigated in a gas-solid fluidized bed reactor of a $0.10m-ID{\times}1.0m$-high stainless steel column with zirconia beads ($d_{SV}=99.2{\mu}m$). The carbon conversion increased with increasing the reaction temperature; however, when the reaction temperature was greater than 773 K, the carbon conversion did not increase. The content of $sp^3$-hybridized carbon at the reaction temperature of 703 K barely changed when the reaction time was more than 30 minutes, but at 773 K, the content decreased as preferred. At 703 K, the purification quality increased with the increasing reaction time; however, at 773 K, the purification quality increased up to 30 minutes and then decreased rapidly.