• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.345-348
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• 2004

For practical applications, the evaluation of reliability or endurance of HTS conductors is necessary. The mechanical properties and the critical current, $I_c$, of multifilamentary Bi-2223 superconducting tapes, externally reinforced with stainless steel foils, subjected to high cycle fatigue loading in the longitudinal direction were investigated at 77K. The S-N curves were obtained and its transport property was evaluated with the increase of repeated cycles at different stress amplitudes. The effect of the stress ratio, R, on the $I_c$ degradation behavior under fatigue loading was also examined considering the practical application situation of HTS tapes. Microstructure observation was conducted in order to understand the L degradation mechanism in fatigued Bi-2223 tapes.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.391-399
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• 1974

Corrosion and passivation of metallic cobalt was studied by means of electrochemical experiments including potentiostatic and galvanostatic measurements and cyclic voltammograms. The mechanisms of active dissolution and passivation of cobalt at the metal/borate buffer solution interface are deduced from the Tafel slope, pH dependence of the Flade potential, and dissolution kinetic data. Hydroxyl group adsorbed on cobalt surface seems to participate in surface oxidation and formation of the passive layer. The growth kinetic data as measured by the current density suggests a mechanism in which the growth of the passive layer is determined by field-assisted transport of ions through the layer. Thickness of the passive layer was estimated by coulometry to be about 10${\AA}$ at the lowest passive potential and to grow gradually with anodic potential to about 20${\AA}$.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.3
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• pp.234-244
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• 1994

Longshore currents driven by monochromatic waves have been described using 2-equation $textsc{k}$-ι turbulence transport model. When using $textsc{k}$-ι closure both profiles of eddy viscosity and current velocity are found to be satisfactory. Several terms of ι equation are related to various variables concerned with turbulence mechanism. New form of turbulence frequency used in ι equation is suggested in the present approach, and non-dimensional parameters are evaluated by comparing the computational results with the laboratory measurements. Various values of a large range are applied to the non-dimensional parameters for the sensitivity test and in order to improve the predictability common values of constants are deduced, which produce similarly good computational results for the well-controlled laboratory measurements.

• Journal of Powder Materials
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• v.31 no.2
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• pp.146-151
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• 2024

Pure SnO₂ has proven very difficult to densify. This poor densification can be useful for the fabrication of SnO₂ with a porous microstructure, which is used in electronic devices such as gas sensors. Most electronic devices based on SnO₂ have a porous microstructure, with a porosity of > 40%. In pure SnO₂, a high sintering temperature of approximately 1300℃ is required to obtain > 40% porosity. In an attempt to reduce the required sintering temperature, the present study investigated the low-temperature sinterability of a current system. With the addition of TiO₂, the compositions of the samples were Sn_1-xTi_xO₂-CoO(0.3wt%)-CuO(2wt%) in the range of x ≤ 0.04. Compared to the samples without added TiO₂, densification was shown to be improved when the samples were sintered at 950℃. The dominant mass transport mechanism appears to be grain-boundary diffusion during heat treatment at 950℃.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.393-400
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• 2011

The mass transport is very complicated at the area which has the macro tide and complex geometry such as Gyeonggi bay. Especially, the long period current has a strong influence on the estuarine ecosystem and the long-term distribution of substances. The long period current is caused by several external forcing, whose unique characteristic varies spatially and temporally. The variation characteristics of long period current is analysed and its generation mechanism is studied. The tidal nonlinear constituents such as overtide and compound tide are generated due to nonlinear interaction and it causes mean sea level setup. The tidal wave propagating up into estuary is transformed rapidly by decrease of cross-sectional area and depth. Therefore the mean sea level is getting rise toward upriver. The high and low tide level is similar between down-river(Incheon) and up-river(Ganghwa) during neap tide when the tidal deformation is decreased. The tidal phase difference between two tidal stations causes a periodic fluctuation of sea level difference. The low water level of Ganghwa station during spring tide does not descend under EL(-)2.5 m, but the low water level of Incheon fall down under EL(-)4.0 m. The variation of tidal range and its sea level are increased during spring tide. It is found that the long period current $M_{sf}$ is quite similar to that of sea level difference between the two tidal stations. It means that the sea surface inclination caused by the spatial difference of tidal deformation is important forcing for the generation of long period current.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.360-360
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• 2012

Zn-Sn-O (Zinc-Tin-Oxide; ZTO) thin films have been gaining extensive academic and industrial attentions owing to a semiconducting channel materials applicable to large-sized flat-panel displays. Due to the constituent oxides i.e., ZnO and SnO2, the resultant Zn-Sn-O thin films possess artificially controllable bandgaps and transmittances especially effective in the visible regime. The current approach employed RF sputtering in depositing the Zn-Sn-O thin films onto glass substrates at ambient conditions. This work places its main emphases on the electrical/optical features which are closely related to the combinations of processing variables. The electrical characterizations are performed using dc-based current-voltage characteristics and ac-based impedance spectroscopy. The optical constants, i.e., refractive index and extinction coefficient, are calculated through spectroscopic ellipsometry along with the estimation of bandgaps. The charge transport of the deposited ZTO thin films is based on electrons characteristic of n-type conduction. In addition to the basic electrical/optical information, the delicate manipulation of n-type conduction is indispensible in diversifying the industrial applications of the ZTO thin films as active devices in information and energy products. Ultimately, the electrical properties are correlated to the processing variables along with the underlying mechanism which largely determines the electrical and optical properties.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.268-277
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• 2004

process (ACP), electrochemical properties of high heat-generating alkali and alkali earth oxides in molten salt were measured and the behavior of those elements were analyzed. The reduction potentials of Cs, Sr, and Ba in a molten LiCl-$Li_2O$ system were more cathodic than that of Li and closely located one another. Thus, it is expected that the alkali and alkali earth would not hinder the reaction mechanism which is via lithium reduction. Alkali and alkali earth metals are likely to recycle into molten salt when the process is operated beyond metal reduction potentials and the effect of electric current on the mass transport is also determined by measuring the metal concentrations in the molten salt phase at different current conditions.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.1
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• pp.14-23
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• 2001

The characteristics of tidal circulation with Hyungsan River discharges in Youngil Bay by the numerical experiments is elucidated. For the simulation of tidal residual currents related to inflow by the river discharges in Youngil Bay located in the southeastern part of Korean Peninsula, the two-dimensional numerical experiment is peformed. The tidal elevation boundary conditions of the 4 main tidal harmonic constituents (M₂, S₂, K₁ and O₁) on the open boundary and river discharges at the river boundary are considered. The computed results obtained from numerical experiment showed good agreements with the field observation ones. The residual currents generally flow toward the inner bay through the western (Dalman-Gap) and central areas of the bay, and then the currents go toward the outer bay along the eastern shore (Changgi-Gap) of the bay with anti-clockwise circulation. Especially, in the numerical experiment without Hyungsan River discharges, these flow patterns are disappeared. Based on the results, it showed that the Hyungsan River discharges play the dominant role in the patterns of tidal residual currents. This flow pattern of tidal residual currents are important mechanism of water quality, material transport in Youngil Bay.

• Journal of Korea Trade
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• v.23 no.6
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• pp.113-130
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• 2019

Purpose - This paper investigates applicability of blockchain based bill of lading under the current legal environment. Legal requirements of electronic bill of lading will be analyzed based on the Rotterdam Rules and recently enacted UNCITRAL Model Law on Electronic Transferable Records. Using comparative analysis with the previous registry model for electronic bill of lading, this paper examines the advantages of blockchain based bill of lading. Design/methodology - This research reviewed previous efforts for dematerializing bill of lading with its limitation. Main features of blockchain technology which can make up for deficiencies of registry model also be investigated to analyze whether these features can satisfy the requirements for the legal validity of the negotiable electronic transport record or electronic transferable records under the Rotterdam Rules and the MLETR. Findings - Main findings of this research can be summarized as follows: Blockchain system operated in an open platform can improve transparency and scalability in transfer of electronic bill of lading by assuring easy access for transaction. Distributed ledger technology of blockchain makes it more difficult to forge or tamper with transactions because all participants equally shares identical transaction records. Consensus mechanism and timestamp in a blockchain transaction guarantee the integrity and uniqueness of a transaction. These features are enough to satisfy the requirements of electronic transferable records under the Rotterdam Rules and MLTER. Originality/value - This study has significance in that it provided implications for the introduction of electronic bill of lading by analyzing whether the blockchain based electronic bill of lading model meets the legal requirements under the current legal system prepared prior to the introduction of blockchain technology, and by presenting the advantages of the blockchain based bill of lading model through comparative analysis with the existing registry model.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.1-7
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• 2000

The SNOSFET memory devices with ultrathin ONO(tunnel oxide-nitride-blocking oxide) gate dielectric were fabricated using n-well CMOS process and investigated its characteristics. The thicknesses of tunnel oxide, nitride and blocking oxide were $23{\AA},\; 53{\AA}\; and\; 33{\AA}$, respectively. Auger analysis shows that the ONO layer is made up of $SiO_2(upper layer of blocking oxide)/O-rich\; SiO_x\N\_y$. It clearly shows that the converting layer with $SiO_x\N\_y(lower layer of blocking oxide)/N-rich SiO_x\N\_y(nitride)/O-rich SiO_x\N\_y(tunnel oxide)$. It clearly shows that the converting layer with $SiO_x\N\_y$ phase exists near the interface between the blocking oxide and nitride. The programming condition of +8 V, 20 ms, -8 V, 50 ms is determined and data retention over 10 years is obtained. Under the condition of 8 V programming, it was confirmed that the modified Fowler-Nordheim tunneling id dominant charge transport mechanism. The programmed threshold voltage is distributed less than 0.1 V so that the reading error of memory stated can be minimized. An $8\times8$ NAND type flash EEPROM with SONOSFET memory cell was designed and simulated with the extracted SPICE parameters. The sufficient read cell current was obtained and the upper limit of $V_{TH}$ for write state was over 2V.