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2013년 서울북부지역 유통농산물의 잔류농약 모니터링 및 위해성 평가
김남훈,이정숙,김욱희,최영희,한성희,김윤희,김희선,이새람,이정미,유인실,정권 한국식품위생안전성학회 2014 한국식품위생안전성학회지 Vol.29 No.3
The aim of this study was to investigate pesticide residues in 2,877 market vegetables in the northernarea of Seoul in 2013. Pesticide residues in the samples were analysed by multiresidue method for 285 pesticides usingGC-ECD/NPD and HPLC-DAD/FLD. 385 samples(13.4%) were detected with pesticide residues at or below MRL,and 15 samples(0.5%) were found to detect pesticide residues exceeding MRL. The most frequently detected sampleswere sedum(63.6%), chamnamul(45.8%), leek(44.5%) and green&red pepper(30.8%). Among the 15 violated samples,leek(5 cases) and welsh onion(4 cases) showed the highest violation rate. A total of 74 samples(18.5%) containedmultiple pesticide residues in one vegetable. Procymidone, chlorofenapyr and cypermethrin were the pesticide mostfrequently found. As a tool of risk assessment through the consumption of pesticide detectable agricultural products,the ratio of estimated daily intake (EDI) to acceptable daily intake (ADI) was calculated into the range of1.05~28.61%. The results have meant that there was no health risk through dieting commercial agricultural productsdetected with pesticide residues.
Modified Direct Torque Control System of Five Phase Induction Motor
김남훈,김민회 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.2
In this paper, improved direct torque control(DTC) of five-phase induction motor(IM) is proposed. Due to the additional degrees of freedom, five-phase IM drives present unique characteristics. One of them is the ability of enhancing the torque producing capability of the motor. Also five-phase motor drives possess many others advantage compared with the traditional three-phase motor drives. Such as, reducing the amplitude and increasing of frequency of torque pulsation, reducing amplitude of current per phase without increasing the voltage per phase and increasing the reliability. The direct torque control method is advantageous when it is applied to the five-phase IM. Because the five-phase inverter provides 32 space vectors in comparison to 8 space voltage vectors by the three-phase inverter. The 32 space voltage vectors are divided into three groups according to their magnitudes. The characteristics and dynamic performance of traditional five-phase DTC are analyzed and new DTC for five-phase IM is proposed. Therefore, a more precise flux and torque control algorithm for the five-phase IM drives can be suggested and explained. For presenting the superior performance of the proposed direct torque control, experimental results is presented using a 32 bit fixed point TMS320F2812 digital signal processor
Low Cost Rotor Fault Detection System forInverter Driven Induction Motor
김남훈,최창호 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.4
In this paper, the induction motor rotor fault diagnosis system using current signals, whichare measured using axis-transformation method, and speed, which is estimated using current currents have numerous harmonics components and therefore fault diagnosis using stator curents is very difficult. The curent and speed signal for rotor fault diagnosis needs to be precise. Also, high resolution information, which means the diagnosis system, demands additional hardware such as low pass filter, high resolution ADC, encoder and etc. Therefore, the proposed axis-transformation and speed estimation method are expected to contribute to low cost fault diagnosis systems in inverter-fed motor drives without the need for an encoder and any additional hardware. In order to confirm validity spectrum of each faulty situation using Park transformation and speed estimation method are compared with the results obtained from fast Fourier transforms.
김남훈,이원용 한국목재공학회 1995 목재공학 Vol.23 No.3
The crystal transformation from cellulose I to cellulose II during alkaline swelling of waste wood, shich has been used for cultivating oak mushroomi(Cortinellus edodes (Beck.) Ito et Imai). was investigated and compared to that of normal wood by a series of X-ray diffraction analysis When the sapwood of cultivated wood was treated with 20% NaOH solution for 2 hours. the cellulose I can be easily transformed into Na-cellulose I than normal wood or heartwood of cultivated wood. Certainly, the formation of Na-cellulose I in wood is proportional to alkali swelling duration. and the formation of cultivated sapwood was Luster tiara that of the other woods. Cellulose I in the sapwood of cultivated wood was easily transformed into cellulose II during mercerization. but the sapwood of normal wood and the heartwood of cultivated wood hardly converted to cellulose II. Namely. most of Na-cellulose I in normal wood can be reconverted to cellulose I in the process of washing and drying. Therefore, it can be concluded from this study that, in cell wall lignin and hemicellulose can prevent the alkaline swelling of cellulose in wood and the transformation from cellulose I to cellulose II as well.
Rapid Laser Annealing of Cu(In,Ga)Se2 Thin Films by Using a Continuous Wave Nd:YAG Laser (0= 532 nm)
김남훈,고필주,조금배,박찬일 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.8
Rapid laser annealing of a Cu(In,Ga)Se2 (CIGS) thin film absorber was proposed and demonstrated using a continuous 532-nm Nd:YAG laser, following sputtering with Cu0.9In0.7Ga0.3Se2 target, because the conventional annealing temperature for improving the crystallinity of CIGS thin films is higher than the decomposition temperature of a typical flexible polymer substrate. When the laser optical power was incrementally increased over the range from 2.00 to 3.00 W, for 200 s, XRD patterns showed the formation of CIGS chalcopyrite (112), (220/204), and (312/116) phases in the laser-annealed CIGS thin films, at laser optical powers of 2.75 and 3.00 W. The band gaps of these laser-annealed CIGS thin films varied from 1.45 to 1.83 eV and depended on the laser optical power. The relative mean absorbance of the laser-annealed CIGS thin films was 1.806, suggesting that approximately 98.44% of the incident photons were observed by the 600-nm-thick film in the visible spectral region. Conductivity type varied with changes in the laser optical power. The resistivities of the laser-annealed CIGS thin films were of order of 10−3 - 101 -cm.
김남훈,Guoqing Xin,조성민,방창현,채희엽 한국물리학회 2015 Current Applied Physics Vol.15 No.9
Microwave-assisted reduced graphene oxide (MR-GO) layer was applied to hole extraction layer (HEL) of polymer solar cells (PSCs) and was compared with the widely used poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) in bulk hetero-junction (BHJ) solar cells. The power conversion efficiency (PCE) of 3.57% was achieved with the MR-GO layer, which is 21% higher than that of PSCs with the conventional PEDOT:PSS HEL material. This enhancement of PCE is mainly attributed to the increase of short-circuit current density originated from the hydrophobic surface of the MR-GO layer. The hydrophobic graphene oxide surface is believed to improve wetting property and physical contact of active blends. In addition, the MR-GO interfacial layer is found to show the excellent device stability in atmospheric condition. The PCE of conventional PEDOT:PSS based PSCs showed total degradation when the device was exposed to atmospheric condition for 1000 h without any encapsulation, while that of MR-GO based PSC showed over 85% of PCE.
김남훈,박주선,이우선 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.3
The Cadmium telluride (CdTe) thin film solar cell is one of the strongest candidates due to the optimum band gap energy (about 1.4 eV) for solar energy absorption, high light absorption capability and lower cost requirements for solar cell production. However, the maximum efficiency of CdTe thin film solar cell still remains just 16.5% despite its excellent absorption coefficient; i.e., the electrical properties of CdTe thin film, including the resistivity, must be improved to enhance the energy conversion efficiency. Silver (Ag) was doped by helium-neon (He-Ne) laser (632.8 nm) exposure into the sputtering deposited <I>p</I>-type CdTe thin films. The Ag-doped CdTe thin films reduced the resistivity from 2.97 × 10<SUP>4</SUP> Ω-cm to the order of 5.16 × 10<SUP>-2</SUP> Ω-cm. The carrier concentration of CdTe thin films increased to 1.6 × 10<SUP>18</SUP> cm<SUP>-3</SUP> at 15 minutes of exposure time in the He-Ne laser. The average absorbance value of CdTe thin films improved from 1.81 to 3.01 by the doping of Ag due to impurity-scattering. These improved properties would contribute to the efficiency of the photovoltaic effects of the photogenerated charged carriers. The methodology in this study was very simple and effective to dope the multilayered thin film solar cell with a relatively short process time, no wet-process, and selective treatment.