• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1026-1031
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• 2008

We report on the design and experimental results of a large diameter faraday rotator for the high-power laser system(KLF: Kaeri laser facility) that was completed in late 2007s at Korea Atomic Energy Research Institute. The design involves modelling the magnetic field of cylindrical coil with large diameter(110 mm). Magnetic field generation coil is designed by 6 layers using a rectangular wire with cross-sectional area $3{\times}5[mm^2]$. We obtain an isolation ratio for optical feedback of 35 dB at 1064 nm and magnetic field strengths ${\sim}25kG$. We expect that the design can be widely used optical isolators in high-power laser system.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.368-368
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• 2012

We report solution-processed, high-performance single-crystal organic nanowire transistors fabricated from a novel indolocarbazole (IC) derivative. The direct printing process was utilized to generate single-crystal organic nanowire arrays enabling the simultaneous synthesis, alignment and patterning of nanowires using molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. These new molecules are particularly suitable for p-channel organic field-effect transistors (OFETs) because of the high level of crystallinity usually found in IC derivatives. Selected area diffraction (SAED) and X-ray diffraction (XRD) experiments on these solution-processed nanowires showed high crystallinity. Transistors fabricated with these nanowires gave a hole mobility as high as 1.0 cm2V-1s-1 with nanowire arrays with the direct printing process.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.69.3-69.3
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• 2012

A high-performance low-voltage graphene field-effect transistor (FED array was fabricated on a flexible polymer substrate using solution-processable, high-capacitance ion gel gate dielectrics. The high capacitance of the ion gel, which originated from the formation of an electric double layer under the application of a gate voltage, yielded a high on-current and low voltage operation below 3 V. The graphene FETs fabricated on the plastic substrates showed a hole and electron mobility of 203 and 91 $cm^2/Vs$, respectively, at a drain bias of - I V. Moreover, ion gel gated graphene FETs on the plastic substrates exhibited remarkably good mechanical flexibility. This method represents a significant step in the application of graphene to flexible and stretchable electronics.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.231-234
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• 2002

This thesis is to introduce development process and application for domestic production of Automation System for High Density and Perpendicular Storage used in the industrial field. Most of the traditional Automation Systems for High Density and Perpendicular Storage are imported and using in the industrial field. As a result of this condition, foreign competitive power is decreased cause increasing of production cost. In spite of economical burden to protect a loss with management in the case of the industrial field dealing with various products, imported Automation System for High Density and Perpendicular Storage is used. On this developed Automation System for High Density and Perpendicular Storage solved these problems. Developed system uses managing computer, it is easy to manipulate input and output of production and inventory management. Moreover, Developed system accomplished shortened driving time and mechanical safety.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.303-305
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• 2000

The effect of anisotropy field on the high frequency magnetic characteristics of FeTaN films was investigated. Those films show good magnetic properties : 4$\pi$Ms of 13KG, Hc of 0.6 Oe, effective permeability(${\mu}$') of 800 with a stable frequency response up to 800MHz. The films also show a large anisotropy field(Hk) over 21Oe. It result from the increased anisotropy of patterned FeTaN films. The combination of high saturation magnetization and relatively high Hk in these films is believed to the partly responsible for FeTaN for the excellent high-frequency behavior.

• Korean Journal of Organic Agriculture
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• v.13 no.3
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• pp.301-314
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• 2005

Insect pests were surveyed in 5 Rice paddy field areas of Organic paddy field and conventional paddy field. At the each rice-growth period, the occurrence rate of 'Small brawn plant hopper was high at the case of duck raising and rice bran farming on middle stage of rice paddy field in Gang-Hwa region. The occurrence rate of Rice water weevil was high at the conventional paddy field on the early stage of rice paddy field in Yeo-Ju region. In the Hong-Seong region, the occurrence rate of 'Rice water weevil' and 'Green rice leafhopper' was high at the 'duck raising compare to the conventional farming on the early stage of rice paddy field. According to each period, the occurrence rate of insect was high at late stage of rice paddy field, and there was no difference between each region. It showed high-occurrence tendency at duck pasture farming rice paddy field. The major natural enemies were spiders and parasites. Theridiidae and Linyphiidae were highly occurred on the conventional farming rice paddy field in Hong-Seong. Web builders containing Theridiidae, Linyphiidae and Tetragnathidae was occurred more than wandering spiders containing Lycosidae, Clubionidae and Pisauridae at various regions, and then occurrence of spiders was different at the various regions but was not different at each farming system.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.257-261
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• 2000

The value of I$_c$(critical current) in HTS (High Temperature Superconductor) tape has a great influence on B${\bot}$(vertical field). Therefore, in shape design of field coil for the HTSG(High Temperature Superconducting Generator), a method to reduce the B${\bot}$ should be considered in order to maintain the stability and substantial improvement on the performance. On the basis of the magnetic field analysis, this paper deals with various field coil shape according to the iron plate to obtain small B${\bot}$ by using Biot-Savart's law, image method and 2D FEA(2 Dimensional Finite Element Analysis) considering the stress condition of HTS. Moreover, the analysis is verified by comparison with experimental results. And also this paper presents the advanced model by using 3D FEA, in which flux density at armature is calculated in 5kVA class HTSG.

• Journal of Magnetics
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• v.16 no.2
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• pp.181-185
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• 2011

To improve trapped field characteristics of a high temperature superconducting (HTS) bulk, a technique to implement artificial holes has been studied. The artificial holes, filled up with epoxy or metal, may provide better cooling channel and enhance mechanical strength of the HTS bulk. Although many useful researches based on experiments have been reported, a numerical approach is still limited because of several reasons that include: 1) highly non-linear electromagnetic properties of HTS; and 2) difficulty in modeling of randomly scattered "small" artificial holes. In this paper, a 2-D finite element method with iteration is adopted to analyze trapped field characteristics of HTS bulk with artificial holes. The validity of the calculation is verified by comparison between measurement and calculation of a trapped field in a $40{\times}40\;mm$ square and 3.1 mm thick HTS bulk having 16 artificial holes with diameter of 0.7 mm. The effects of sizes and array patterns of artificial holes on distribution of trapped field within HTS bulk are numerically investigated using suggested method.

• Journal of Magnetics
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• v.16 no.3
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• pp.312-317
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• 2011

NMR over 1 GHz (23.5 T) level has difficulties in design and fabrication with only low temperature superconducting (LTS) wire because of its material characteristics such as the decay of critical current under the magnetic field. Because High temperature superconducting (HTS) tape has a good performance under the extremely high magnetic field, it has been developed for high-field magnet over 23.5 T. In this paper, the LTS magnet was made for applying magnetic fields externally and the HTS coil was designed and fabricated. The electromagnetic field analysis has been done with respect to the structure and the operating current of the LTS and HTS coil. Considering to the field homogeneity and the center field, the design parameters which is suitable for the HTS coil were found. The HTS insert coil was impregnated with epoxy resin in order to prevent the movement of winding during energizing the magnet. The hybrid magnet (LTS/HTS) magnet was fabricated and tested based on the design parameters. The experimental result shows that the LTS background magnet and the HTS insert coil can be operated stable beyond 220 A and 210 A. The final value 4.32 T at the center was acquired.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.140-143
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• 2008

The Operation of high speed train in year 2004 bring about a great change in railroad industry. Especially in railroad construction field we have acquired great Know-how. And up to now we are building up operation skills. But the high speed train system are totally imported, so it is necessary to investigate some of the equipment based on our own environment. In case of Toughened Glass Stem Insulator, we don't have any application case in domestic and limited in abroad. So there must be some characteristic estimation. This paper introduces estimation methode in three different field. First electrical field, Second physical field and finally environment circumstance. In Electrical field, amplitude and number of time for abnormal peak voltage data are collected. And in physical field case, amplitude and trend of vibration in to the insulator are examined. And I circumstance case, possibility of flying gravel and ice clod are investigated. Through this basic data, suitability for Toughened Glass Stem Insulator using in domestic will be accumulated and estimated.