• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.827-834
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• 2000

A granular herbicide applicator attached to conventional ride-on rice transplanter with 6 rows was developed in order to carry out both transplanting and herbicide application at once. It resulted in labor saving by 98%. The prototype is composed of a metering device and a spinning disc spreader. The application rate per 10a can be varied from 1 to 3 kg and the application swath is 1.8 m, which is the planting width of the ride-on rice transplanter with 6 rows. The angular speed of spinning disc and the application height were used as design factors to obtain the uniform distribution of herbicide granules. As the result of experiment, the distribution uniformity showed a tendency to be proportional to the increases of both spinner angular speed and application height. The prototype with angular speed of spinning disc of 7359 rpm and the application height of 20 cm was made and its distribution uniformity was relatively uniform with the CV(coefficient of variation) of 21.7%. In field test, when the tested herbicides such as ACl40+Stomp and Londax+YRC were applied, the weed control has continued for 65 days since transplanting was done.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.1
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• pp.72-75
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• 2016

In this paper, we proposes a internal antenna for wireless DVI dongle device using the folded monopole structure. The proposed antenna uses a basic structure of spiral and monopole. The antenna optimized for parameters length, gap, width, and rectangle of folded monopole antenna using the spiral structure. To confirm the characteristics of the antenna parameters, HFSS from ANSYS Inc. was used for the analysis. We used an FR4 dielectric substrate with a dielectric constant of 4.4. The DVI dongle size of the proposed antenna is $50{\times}40{\times}1.6mm$, and the size of the antenna area is $10{\times}40mm$. There is a value of return loss less then -10dB in 2.4GHz and 5.8GHz, band and the maximum antenna gain is -4.13dBi. The utilization possibility of the wireless DVI Dongle antenna have a folded monopole with spiral shape could be confirmed according to compare and analyze the simulation and measurement data.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.5
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• pp.317-320
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• 2016

In order to acquire clear images capable of diagnosing cracked tooth by light transmission, the optical properties of LED light source were examined. Based on the results, the prototype which basically consisted of LED light source, bandpass filter and commercial compact camera module was designed and manufactured. The wavelength and optical power of the LED in the prototype were 850 nm and 7 mW/Sr, respectively. In evaluation of the prototype using microscope, the observation of the crack with width of above $17{\mu}m$ was possible. In addition, image analysis to obtain shape information on the observed tooth cracks was carried out.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.635-643
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• 2016

Graphene has shown exceptional properties for high performance devices due to its high carrier mobility. Of particular interest is the potential use of graphene nanoribbons as field-effect transistors. Herein, we introduce a facile approach to the fabrication of graphene nanoribbon (GNR) arrays with ~200 nm width using nanoimprint lithography (NIL), which is a simple and robust method for patterning with high fidelity over a large area. To realize a 2D material-based device, we integrated the graphene nanoribbon arrays in field effect transistors (GNR-FETs) using conventional lithography and metallization on highly-doped $Si/SiO_2$ substrate. Consequently, we observed an enhancement of the performance of the GNR-transistors compared to that of the micro-ribbon graphene transistors. Besides this, using a transfer printing process on a flexible polymeric substrate, we demonstrated graphene-silicon junction structures that use CVD grown graphene as flexible electrodes for Si based transistors.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.932-934
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• 1999

In this paper, the new IGBT structures with trap injection are proposed to improve switching characteristics of the conventional SOI LIGBT. The simulations are used in order to investigate the effects of the position, width and concentration of trap injection region using 2D device simulator MEDICI. And, their electrical characteristics are analyze and the optimum design parameters are extracted. As a result of simulation, the turn off time for the proposed LIGBT model A by the trap injection is $0.78{\mu}s$. And, the latch up voltage is 3.4V and forward blocking voltage is 168V which are superior to that of conventional structure. In addition, the proposed model is achieved more efficient in switching time and process effort. Therefore, It is shown that the trap injection is very effective to reduce the turn off time with a little increasing of on-state voltage drop if its design and process parameters are optimized.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.12
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• pp.607-613
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• 2001

Molybdenum thin films were deposited on the soda lime glass(SLG) substrates by direct-current planar magnetron sputtering, with a sputtering power density of $4.44W/cm^2$. The working pressure was varied from 0.5 mtorr to 20 mtorr to gain a better understanding of the effect of sputtering pressure on the morphology and microstructure of the Mo film. Thin films of $CU(InGa)Se_2$ (CIGS) were deposited on the Mo-coated glass by three stage co-evaporation process. The highest efficiency device was obtained at the maximum value of the tensive stress. The morphology of Mo-coated films were examined by using scanning electron microscopy The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the residual intrinsic stress were examined by X-ray diffraction.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.156.1-156.1
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• 2015

Neon and argon plasma group velocities (ug) are obtained by intensified charge coupled device (ICCD) camera images at fixed gate width time of 5 ns. The propagation velocities in upstream and downstream region are in the order of 104-105 m/s. The plasma ambipolar diffusion velocities are calculated to be in the order of 101-102 m/s. Plasma jet is generated by sinusoidal power supply in varying voltages from 1 to 4 kV at repetition frequency of 40 kHz. By employing one dimensional convective wave packet model, the neon and argon electron temperatures in non-thermal atmospheric-pressure plasma jet are estimated to be 1.95 and 1.18 eV, respectively.

• Steel and Composite Structures
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• v.26 no.4
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• pp.439-452
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• 2018

This paper presents experimental and numerical study on buckling behaviors and hysteretic performance of Class 1 H-shaped steel beam subjected to cyclic pure bending within the scope of ultra-low cycle fatigue (ULCF). A loading device was designed to achieve the pure bending loading condition and 4 H-shaped specimens with a small width-to-thickness ratio were tested under 4 different loading histories. The emphasis of this work is on the impacts induced by local buckling and subsequent ductile fracture. The experimental and numerical results indicate that the specimen failure is mainly induced by elasto-plastic local buckling, and is closely correlated with the plastic straining history. Compared with monotonic loading, the elasto-plastic local buckling can occur at a much smaller displacement amplitude due to a number of preceding plastic reversals with relative small strain amplitudes, which is mainly correlated with decreasing tangent modulus of the material under cyclic straining. Ductile fracture is found to be a secondary factor leading to deterioration of the load-carrying capacity. In addition, a new ULCF life evaluation method is proposed for the specimens using the concept of energy decomposition, where the cumulative plastic energy is classified into two categories as isotropic hardening and kinematic hardening correlated. A linear correlation between the two energies is found and formulated, which compares well with the experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.70-73
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• 2001

MFIS(Metal-ferroelectric-insulator- semiconductor) structures using silicon oxynitride(SiON) buffer layers were fabricatied and demonstrated nonvolatile memory operations. Oxynitride(SiON) films have been formed on p-Si(100) by RTP(rapid thermal process) in O$_2$+N$_2$ ambient at 1100$^{\circ}C$. The gate leakage current density of Al/SiON/Si(100) capacitor was about the order of 10$\^$-8/ A/cm$^2$ at the range of ${\pm}$ 2.5 MV/cm. The C-V characteristics of Al/LiNbO$_3$/SiON/Si(100) capacitor showed a hysteresis loop due to the ferroelectric nature of the LiNbO$_3$ thin films. Typical dielectric constant value of LiNbO$_3$ film of MFIS device was about 24. The memory window width was about 1.2V at the electric field of ${\pm}$300 kV/cm ranges.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1304-1314
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• 1988

An experimental study of the influences of HF concentration, current density, reaction time and the silicon surface, on the formation and properties of porous silicon are reported. The SOI (Silicon-On-Insulator) strip lines with 100 um width are fabricated at room temperature by anodic oxidation of PSL (Porous Silicon Layers). The stress on the silicon island induced by the anodic oxidation can be avoided by the two-step PSL formation technique. At the final step of IC fabrication process, device isolation will be achieved at room temperature by this method.