• Journal of Sensor Science and Technology
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• v.31 no.5
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• pp.353-359
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• 2022

This study investigated via computational analysis the application utility of series-cascaded ring resonators based on silicon-on-insulator (SOI) slot optical waveguides in integrated optical biochemical sensors. The radii of the two rings in the series-cascaded ring resonators were 59.4 ㎛ and 77.6 ㎛ respectively, and the coupling distance was 0.5 ㎛. The series-cascaded ring resonators were computationally analyzed using FIMMProp and PICWave numerical software. The free spectral range (FSR), full width at half maximum (FWHM), sensitivity, and quality-factor (Q-factor) of the series-cascaded ring resonators were 12.2 nm, 0.134 nm, 4100 nm/RIU, and 11580, respectively, and the measurement range was calculated to be slightly smaller than 3×10^-3 RIU. Although the measurement range was smaller than that of the single ring resonator, upon considering other characteristic parameters, the series-cascaded ring resonators are found to be more effective as integrated sensors than single ring resonators.

• Journal of Arbitration Studies
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• v.15 no.2
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• pp.93-123
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• 2005

As the international commercial transaction has drastically grown up with the mainland China, commercial disputes that are required to settle through ADR have tremendously increased during the last decade. Since China has not been fully exposed to the Free World for a long period of time, there would have been a great amount of misunderstanding about their competency and integrity to deal with internationally oriented commercial transactions with a view to internationally acceptable manner. This arbitration case was related to the contract in dispute of C&A Inc. as the importer v. China XX Importation Co. as the exporter for the sale of Silicon Metal. But after the contract were formed, exporter(respondent) declined to deliver the goods under the contracts because the market price of Silicon Metal increased according to the argument of the importer(claimant). Importer had to purchase alternative goods from other companies to substitute for the goods subject to the contracts in dispute. Importer purchased silicon metal of the same quality as under the contracts from two other Chinese companies as the necessary measure to mitigate the loss, paying prices higher than the contract price. Since exporter had breached the contracts, importer's loss should be compensated by the exporter as the Arbitration Tribunal decided for supporting importer's claim of loss for the substitute goods. This study is aiming at analyzing the rationale of the arbitral awards made by the Shanghai Commission in terms of (l)Place of Arbitration, (2)Applicable Law, (3)Validity of the Contracts, (4)Doctrine of Frustration, (5)Responsibility for the Mitigation of Damage by the Importer.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.52-57
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• 1999

Funtional metal prototypes are often required in numerous industrial applications. These components are typically needed in the early stage of a project to determine form, fit and function. Recent R/P(Rapid Prototyping) part are made of soft materials such as plastics, wax, paper, these master models cannot be employed durable test in real harsh working environment. Parts by direct metal rapid tooling method, such as laser sintering, by now are hard to get net shape, pores of the green parts of powder casting method must be infiltrated to get proper strength as tool, and new type of 3D direct tooling system combining fabrication welding arc and cutting process is reported by song etc. But a system which can build directly 3D parts of high performance functional material as metal part would need long period of system development, massive investment and other serious obstacles, such as patent. In this paper, through the rapid tooling process as silicon rubber molding using R/P master model, and fabricate wax pattern in that silicon rubber mold using vacuum casting method, then we tranlsated the wax patterns to numerous metal prototypes by new investment casting process combined conventional investment casting with rapid pototyping & rapid tooling process. with this wax-injection-mold-free investment casting, we developed new investment casting process of fabricating numerous functional metal prototypes from one master model, combined 3-D CAD, R/P and conventional investment casting and tried to expect net shape measuring total dimension shrinkage from R/P part to metal part.

• Journal of the Korean institute of surface engineering
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• v.47 no.2
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• pp.68-74
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• 2014

The seed step-coverage enhancement process (SSEP) using Pd/Cu/PVP colloids was investigated for the filling of through silicon via (TSV) without void. TEM analysis showed that the Pd/Cu nano-particles were well dispersed in aqueous solution with the average diameter of 6.18 nm. This Pd/Cu nano-particles were uniformly deposited on the substrate of Si/$SiO_2$/Ti wafer using electrophoresis with the high frequency Alternating Current (AC). After electroless Cu deposition on the substrate treated with Pd/Cu/PVP colloids, the adhesive property between deposited Cu layer and substrate was evaluated. The Cu deposit obtained by SSEP with Pd/Cu/PVP colloids showed superior adhesion property to that on Pd ion catalyst-treated substrate. Finally, by implementing the SSEP using Pd/Cu/PVP colloids, we achieved 700% improvement of step coverage of Cu seed layer compared to PVD process, resulting in void-free filling in high aspect ratio TSV.

• Journal of Sensor Science and Technology
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• v.14 no.2
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• pp.96-100
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• 2005

The planar Schottky diodes were fabricated and modeled to probe the device applicability of the cracked GaN epitaxial layer on a (111) silicon substrate. On the unintentionally n-doped GaN grown on silicon, we deposited Ti/Al/Ni/Au as the ohmic metal and Pt as the Schottky metal. The ohmic contact achieved a minimum contact resistivity of $5.51{\times}10.5{\Omega}{\cdot}cm^{2}$ after annealing in an $N_{2}$ ambient at $700^{\circ}C$ for 30 sec. The fabricated Schottky diode exhibited the barrier height of 0.7 eV and the ideality factor was 2.4, which are significantly lower than those parameters of crack free one. But in photoresponse measurement, the diode showed the peak responsivity of 0.097 A/W at 300 nm, the cutoff at 360 nm, and UV/visible rejection ratio of about $10^{2}$. The SPICE(Simulation Program with Integrated Circuit Emphasis) simulation with a proposed model, which was composed with one Pt/GaN diode and three parasitic diodes, showed good agreement with the experiment.

• Metals and materials international
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• v.24 no.6
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• pp.1394-1402
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• 2018

This study investigates the mechanism of MnS precipitation on $Al_2O_3-SiO_2$ inclusions during the solidification of non-oriented silicon steel, especially the influence of the phase structures and sizes of the oxides on the MnS precipitation, by scanning electron microscopy and transmission electron microscopy coupled with energy dispersive spectrometry. The investigation results show that MnS tends to nucleate on submicron-sized $Al_2O_3-SiO_2$ inclusions formed by interdendritic segregation and that it covers the oxides completely. In addition, MnS can precipitate on micron-sized oxides and its precipitation behavior is governed by the phase structure of the oxides. The MnS embryo formed in a MnO-containing oxide can act as a substrate for MnS precipitation, thus permitting further growth via diffusion of solute atoms from the matrix. MnS also precipitates in a MnO-free oxide by the heterogeneous nucleation mechanism. Furthermore, MnS is less prone to precipitation in the $Al_2O_3$-rich regions of the $Al_2O_3-SiO_2$ inclusions; this can be explained by the high lattice disregistry between MnS and $Al_2O_3$.

• Korean Journal of Materials Research
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• v.31 no.5
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• pp.301-311
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• 2021

The conversion of all carbon preforms to dense SiC by liquid infiltration can become a low-cost and reliable method to form SiC-Si composites of complex shape and high density. Reactive sintered silicon carbide (RBSC) is prepared by covering Si powder on top of 0.5-5.0 wt% Y₂O₃-added carbon preforms at 1,450 and 1,500℃ for 2 hours; samples are analyzed to determine densification. Reactive sintering from the Y₂O₃-free carbon preform causes Si to be pushed to one side and cracking defects occur. However, when prepared from the Y₂O₃-added carbon preform, an SiC-Si composite in which Si is homogeneously distributed in the SiC matrix without cracking can be produced. Using the Si + C = SiC reaction, 3C and 6H of SiC, crystalline Si, and Y₂O₃ phases are detected by XRD analysis without the appearance of graphite. As the content of Y₂O₃ in the carbon preform increases, the prepared RBSC accelerates the SiC conversion reaction, increasing the density and decreasing the pores, resulting in densification. The dense RBSC obtained by reaction sintering at 1,500 ℃ for 2 hours from a carbon preform with 2.0 wt% Y₂O₃ added has 0.20 % apparent porosity and 96.9 % relative density.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.15-15
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• 2011

As you know, boron compounds, borax ($Na_2B_4O_5(OH)_4{\cdot}8H_2O$) etc. were known thousands of years ago. As for natural boron, it has two naturally occurring and stable isotopes, boron 11 ($^{11}B$) and boron 10 ($^{10}B$). The neutron absorption $^{10}B$ is included about 19~20% with 80~81% $^{11}B$. Boron is similar to carbon in its capability to form stable covalently bonded molecular networks. The mass difference results in a wide range of ${\beta}$ values between the $^{11}B$ and $^{10}B$. The $^{10}B$ isotope, stable with 5 neutrons is excellent at capturing thermal neutrons. For example, it is possible to decrease a thermal neutron required for the nuclear reaction of uranium 235 ($^{235}U$). If $^{10}B$ absorbs a neutron ($^1n$), it will change to $^7Li+^1{\alpha}$ (${\alpha}$ ray, like $^4He$) with prompt ${\gamma}$ ray from $^{11}B$ $^{11}B$ (equation 1). $$^{10}B+^1n\;{\rightarrow}\;^{11}B\;{\rightarrow}\; prompt \;{\gamma}\;ray (478 keV), \;^7Li+4{\alpha}\;(4He)\;\;\;\;{\cdots}\; (1)$$ If about 1% boron is added to stainless steel, it is known that a neutron shielding effect will be 3 times the boron free steel. Enriched boron or $^{10}B$ is used in both radiation shielding and in boron neutron capture therapy. Then, $^{10}B$ is used for reactivity control and in emergency shutdown systems in nuclear reactors. Furthermore, boron carbide, $B_4C$, is used as the charge of a nuclear fission reaction control rod material and neutron cover material for nuclear reactors. The $B_4C$ powder of natural B composition is used as a charge of a control material of a boiling water reactor (BWR) which occupies commercial power reactors in nuclear power generation. The $B_4C$ sintered body which adjusted $^{10}B$ concentration is used as a charge of a control material of the fast breeder reactor (FBR) currently developed aiming at establishment of a nuclear fuel cycle. In this study for new boron compound, silicon boride ceramics for capturing thermal neutrons, preparation and characterization of both silicon tetraboride ($SiB_4$) and silicon hexaboride ($SiB_6$) and ceramics produced by sintering were investigated in order to determine the suitability of this material for nuclear power generation. The relative density increased with increasing sintering temperature. With a sintering temperature of 1,923 K, a sintered body having a relative density of more than 99% was obtained. The Vickers hardness increased with increasing sintering temperature. The best result was a Vickers hardness of 28 GPa for the $SiB_6$ sintered at 1,923K for 1 h. The high temperature Vickers hardness of the $SiB_6$ sintered body changed from 28 to 12 GPa in the temperature range of room temperature to 1,273 K. The thermal conductivity of the SiB6 sintered body changed from 9.1 to 2.4 W/mK in the range of room temperature to 1,273 K.

• Resources Recycling
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• v.18 no.1
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• pp.38-43
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• 2009

In this study, binderless consolidation processes of ultra foe Si powder, by-products of making high purity poly-Si in the current method, were systematically investigated for use as economical solar-grade feedstock. The average diameter of the silicon powder was $7.8{\mu}m$. The main contaminants of the fine silicon powder were $SiO_2$ type oxide and humidity. The chemical pretreatment using the HF solution was observed to be effective for the improvement of the compactability of the silicon powder and the density ratio and the strength of the silicon powder compacts. The yield of the binder-free consolidation process increased by 20% under a vacuum condition. In as-received state, the silicon powder were not pure enough to be used as solar grade feed-stock material. After the dry chemical treatments, a sufficiently high purity above solar-grade was able to be achieved.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.277-277
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• 2013

The epitaxial graphene on the 4H- or 6H-SiC(0001) surface has been intensively studied due to the possibility of wafer-scale growt. However the existence of interface layer (zero layer graphene) and its influence on the upper graphene layer have been considered as one of the main obstarcles for the industrial application. Among various methods tried to overcome the strong interaction with the substrate through the interface layer, it has been proved that the hydrogen intercalation successfully passivate the Si dangling bond of the substrate and can produce the quasi-free standing epitaxial graphene (QFEG) layers on the siC(0001) surface. In this study, we report the results of the angle-resolved photoemission spectroscopy (ARPES) and Raman spectroscopy for the QFEG layers produced by ex-situ and in-situ hydrogen intercalation.From the ARPES measurement, we confirmed that the Dirac points of QFEG layers exactly coincide with the Fermi level. The band structure of QFEG layer are sustainable upon thermal heating up to 1100 K and robust against the deposition of several metals andmolecular deposition. We also investigated the strain of the QFEG layers by using Raman spectroscopy measurement. From the change of the 2D peak position of graphene Raman spectrum, we found out that unlike the strong compressive strain in the normal epitaxial graphene on the SiC(0001) surface, the strain of the QFEG layer are significantly released and almost similar to that of the mechanically exfoliated graphene on the silicon oxide substrate. These results indicated that various ideas proposed for the ideal free-standing graphene can be tested based on the QFEG graphene layers grown on the SiC(0001) surface.