• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.199-202
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• 2017

Silicon carbide (SiC) is being spotlighted as a next-generation power semiconductor material owing to the characteristic limitations of the existing silicon materials. SiC has a wider band gap, higher breakdown voltage, higher thermal conductivity, and higher saturation electron mobility than those of Si. When using this material to implement Schottky barrier diode (SBD) devices, SBD-state operation loss and switching loss can be greatly reduced as compared to that of traditional Si. However, actual SiC SBDs exhibit a lower dielectric breakdown voltage than the theoretical breakdown voltage that causes the electric field concentration, a phenomenon that occurs on the edge of the contact surface as in conventional power semiconductor devices. Therefore in order to obtain a high breakdown voltage, it is necessary to distribute the electric field concentration using the edge termination structure. In this paper, we designed an edge termination structure using a field plate structure through oxide etch angle control, and optimized the structure to obtain a high breakdown voltage. We designed the edge termination structure for a 650 V breakdown voltage using Sentaurus Workbench provided by IDEC. We conducted field plate experiments. under the following conditions: $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $75^{\circ}$. The experimental results indicated that the oxide etch angle was $45^{\circ}$ when the breakdown voltage characteristics of the SiC SBD were optimized and a breakdown voltage of 681 V was obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.3-4
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• 2006

In this paper, a nickel silicide technology with post-silicidation annealing effect for thin film SOI devices is investigated in detail. Although lower resistivity Ni silicide can be easily obtained at low forming temperature, poor thermal stability and changing of characteristic are serious problems during the post silicidation annealing like ILD (Inter Layer Dielectric) deposition or metallization. So these effects are observed as deposited Ni thickness differently on As doped SOI (Si film 30nm). Especially, the sheet resistance of Ni thickness deposited 20nm was lower than 30nm before the post silicidation annealing. But after the post silicidation annealing, the sheet resistance was changed. Therefore, in thin film SOI MOSFETs or Ni-FUSI technology that the Si film is less than 50nm, it is important to decide the thickness of deposited Ni in order to avoid forming high resistivity silicide.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.820-824
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• 2014

TiNOx multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. 4 multi-layers of $TiO_2$/TiNOx(LMVF)/TiNOx(HMVF)/Ti/substrate have been prepared with ratio of Ar and ($N_2+O_2$) gas mixture. $TiO_2$ of top layer is anti-reflection layer on double TiNOx(LMVF)/TiNOx(HMVF) layers and Ti metal of infrared reflection layer. In this study, the crystallinity and surface properties of TiNOx thin films were estimated by X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM), respectively. The grain size of TiNOx thin films shows to increase with increasing sputtering power. The composition of thin films has been investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The TiNOx multi-layer films show the excellent optical performance beyond 9% of reflectance in those ranges wavelength.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.533-544
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• 2016

This paper provides a reference to determine the seal performance of metallic O-rings for a reactor pressure vessel (RPV). A nonlinear elastic-plastic model of an O-ring was constructed by the finite element method to analyze its intrinsic properties. It is also validated by experiments on scaled samples. The effects of the compression ratio, the geometrical parameters of the O-ring, and the structure parameters of the groove on the flange are discussed in detail. The results showed that the numerical analysis of the O-ring agrees well with the experimental data, the compression ratio has an important role in the distribution and magnitude of contact stress, and a suitable gap between the sidewall and groove can improve the sealing capability of the O-ring. After the optimization of the sealing structure, some key parameters of the O-ring (i.e., compression ratio, cross-section diameter, wall thickness, sidewall gap) have been recommended for application in megakilowatt class nuclear power plants. Furthermore, air tightness and thermal cycling tests were performed to verify the rationality of the finite element method and to reliably evaluate the sealing performance of a RPV.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.138-142
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• 2012

The ${\epsilon}$ type copper phthalocyanine (${\epsilon}$-CuPc), called as a pigment blue 15 : 6, is a significant material to produce a blue pixel in LCD (Liquid Crystal Display) panel. In this study, ${\epsilon}$-CuPc sample was synthesized at various reaction conditions by applying the seed method using ${\epsilon}$-CuPc nanoparticles as a seed. Adequate synthetic conditions of the samples were selected by analyzing and comparing crystalline structure, crystalline purity, microstructure, and synthetic yield of the samples with ${\alpha}$ and ${\beta}$ crystalline CuPc samples. The chemical and crystalline structure of the samples were tested using FT-IR spectrometer and X-ray diffractometry, respectively. The shape of the particle was examined using field emission scanning electiron microscope while the thermal property was tested utilizing thermogravimetric analysis.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.803-810
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• 1998

The mechanical and thermal properties of solutions of acorn starch were investigated, to determine the effect of sucrose on the retrogradation. The contents of moisture and amylose of purified acorn starch was 9.35, 27% respectively. From the moecular weight distribution, Mw and Mn of acorn starch were 1,220,432 and 137,201 relatively and the polydispersity of acorn starch was 8.8952. The creep compliance of acorn starch with and without sucrose were decreased with increasing sucrose concentration in the short term. The temperatures of DSC curve of 15% acorn starch solution containg sucrose shifted slightly to higher temperatures with increasing sucrose content. The enthalpy change associated with the gelatinization was increased with increasing sucrose content. After 7 days storage, the creep compliance of acorn starch gel with sucrose were shown higher than acorn starch gel. Regelatinization enthalpy of acorn starch/sucrose/water system was decreased with increasing sucrose content and increased with storage time. In addition, the characteristic temperatures such as onset temperature, peak temperature and conclusion temperature was increased by sucrose addition. Retrogradation ratio decreased with increasing sucrose content, thus sucrose inhibit retrogradation in the long term. Sucrose acts as an antistaling reagents and retatards the retrogradation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.5
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• pp.97-105
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• 2008

The micro capacitors are passive elements necessary to electronic circuits and wireless portable PAN(personal area network) and Mobile Communications device modules in the baseband circuits in combination with another passive and active devices. As capacitance is proportionally increased with dielectric constant and electrode areas, in addition, inversely decreased the thickness of the dielectric material, thus thin film capacitors are generally seen as a preferable means to achieve high performance and thin film capacitors are used in a variety of functional circuit devices. In this paper, propose dielectric material as AIN(Aluminium nitride) to make micro thin film capacitor, and this capacitor has the MIM(metal-insulator-metal) structure. AIN thin films are widespread applied because they had more excellent properties such as chemical stability, high thermal conductivity, electrical isolation and so on. In addition, AIN films show low frequency response for baseband signal ranges, I-V and C-V electrical characterization of a thin film micro capacitor. The above experimental test and estimated results demonstrate that the thin film capacitor has sufficient and efficient functional performance to be the baseband range frequency of general electronics circuit and passive device applications.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.460-465
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• 2019

In this study, we aim to derive a solution from the structural analysis for electrical failure of single board computers for computing navigation information. By analyzing the characteristic factor, we identify that crack occur on the central processing unit board due to a certain structural problem, and that the physical effect by the crack make communication function be impossible to perform, which it causes booting error. In order to find the location of excessive stress causing the crack, structural analysis for the single board computer is done. From the structural analysis, the areas where stress concentration occurs are identified, and improvement methods changing the structures are developed. As a result, we shows that stresses are reduced entirely on the stress distribution for the improved structure. In addition, heat analysis shows that changing the structure to reduce stresses is not affect to the heat radiation, and the thermal resistance of the actual equipment is verified by measuring the temperature of the heat sink applied with the improved structure.

• Journal of Applied Reliability
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• v.17 no.4
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• pp.280-288
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• 2017

Purpose: PBA buried in underwater requires high reliability because of its mission critical characteristic and harsh operational environment during its life cycle. Therefore, various reliability improvement activities are necessary. The defect on PBA manufacturing process have been studied, as a result, many activities and standards have been presented. However, there are less studies regarding failure pattern on physical features based on design. In this paper, we studied a possible failure patten based on physical features that is related with manufacturing process of PBA. And reliability improvement design based on PoF (Physical of Failure) were intruduced in this paper. Methods: A reliability prediction simulation were performed on the components A and B of the H system using Sherlock Software which is a PoF commercial tool from DFR solution. Solder fatigue and PTH fatigue analysis based on thermal cycling profiles and random vibration was analyzed on three earthquake response spectrum. Result: It was validated that life time and reliability improvement design through solder fatigue and PTH fatigue analysis in case of component. For compoenet B, random vibration fatigue was additionally analyzed and validated reliability for earthquakes profile. Conclusion: In design stage prior to manufacturing, PoF can be analyzed, and it is possible to make a reliability improvement/validated design using design data. This study can be applied in every design step and contribute to make more stable development product.

• Elastomers and Composites
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• v.43 no.1
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• pp.18-24
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• 2008

An oligomeric diol was utilized as a modifier for the reaction rate and mechanical properties of a RT-castable polyurethane elastomer. Both the reaction rate and the tensile strength of the blend samples, in which the modifier and the base resins were mixed with one-shot method, showed an exponential decrease as the increase of modifier concentration. Thermal analysis method of Kissinger was also effectively applied in the present study, showing good linearity in the plot of ln $(q/T^2_p)$ vs. $(1/T_p)$ and activation energy $E_a$ of 44.80 kJ/mol, which is similar to the general castable polyurethane. In the mechanical properties, remarkable decrease of strength was found by the addition of modifier concentration range up to about 20 phr, while characteristic elongation property of the elastomer, high elongation at lower strength, was observed over 20 phr of the modifier. Exponential decrease of the break strength of the blend sample exhibited that the mechanical properties of the blend might be considerably sensitive to the modifier concentration.