• Journal of Soil and Groundwater Environment
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• v.22 no.4
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• pp.33-48
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• 2017

An optimum disposal plan of disused sealed radioactive sources (DSRSs) should be established to ensure long-term disposal safety at the low- and intermediate-level radioactive waste (LILW) disposal facility in Gyeongju. In this study, an optimum disposal system was suggested and preliminary post-closure safety assessment was performed. The DSRSs disposal system was composed of a rock cavern and near surface disposal facilities at the Gyeongju LILW disposal facility. The assessment was conducted using GoldSim program, and probabilistic assessment and sensitivity analysis were implemented to evaluate the uncertainties in the input parameters of natural barriers. Deterministic and probabilistic calculations indicated that the maximum dose was below the regulatory limits ($0.1mSvyr^{-1}$ for the normal scenario, $1mSvyr^{-1}$ for the well scenario). It was concluded that the DSRSs disposal system would maintain environmental safety over a long-time. Moreover, the partition coefficient of Np in host rock, Darcy velocity in host rock, and density of the host rock were the most sensitive parameters in predicting exposure dose in the safety assessment.

• Corrosion Science and Technology
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• v.20 no.4
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• pp.175-182
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• 2021

Magnesium alloy is limited in the industrial field because its standard electrode potential is -2.363 V vs. NHE (Normal Hydrogen Electrode) at 25 ℃. This high electrochemical activity causes magnesium to quickly corrode with oxygen in air; chemical conversion coating prevents corrosion but causes surface defects like cracks and pores. We have examined the anti-corrosion effect of sol-gel coating sealed on the defected conversion coating layer. Sol-gel coatings produced higher voltage current and smaller pore than the chemical conversion coating layer. The conversion coating on magnesium alloy AZ31 was prepared using phosphate-permanganate solution. The sol-gel coating was designed using trimethoxymethylsilane (MTMS) and (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) as precursors, and aluminum acetylacetonate as a ring-opening agent. The thermal shock resistance was tested by exposing specimens at 140 ℃ in a convection oven; the results showed changes in the magnesium alloy AZ31 surface, such as oxidization and cracking. Scanning electron microscope (FE-SEM) analysis confirmed a sealed sol-gel coating layer on magnesium alloy AZ31. Electrochemical impedance spectroscopy (EIS) measured the differences in corrosion protection properties by sol-gel and conversion coatings in 0.35 wt% NaCl solution, and the potentiodynamic polarization test and confirmed conversion coating with the sol-gel coating show significantly improved resistance by crack sealing.

• Corrosion Science and Technology
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• v.21 no.1
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• pp.68-76
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• 2022

Several technologies are employed to protect substrates from corrosion and erosion damage. In particular, arc thermal spray coating technology is widely used as anti-corrosive technology for steel and concrete structures and is applied to offshore plants and petrochemical and drilling facilities. In this investigation, solid particle impingement erosion experiments were performed on an arc thermal spraying-coated specimen using 85% Al-14% Zn-1% Zr wire rod in KR-RA steel. This study investigated the effect of fluorosilicone sealing on the erosion resistance characteristics of the thermal spray coating layer. The erosion rates of the thermal spray-coated and sealed specimens were 4.1×10^-4 and 8.5×10^-4, respectively. At the beginning of the experiment, the fluorosilicone sealant was almost destroyed by the impact of the solid particles. The destruction time for the coating layer was 10 minutes for the thermal spray-coated specimen and 13 minutes for the sealed specimens, indicating that the sealed specimens had better erosion resistance characteristics to solid particle impingement.

• Korean Journal of Agricultural Science
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• v.18 no.2
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• pp.148-156
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• 1991

This study was carried out to investigate the storage conditions and methods required for commercialization of Jeung-Pyon. The storage characteristics of Jeung-Pyon were examined with Universal Testing Machine (UTM, Instron model 1000) for textural properties during storage of under the conditions such as sealing, nonsealing, and temperatures. The differences in storage characteristics on the different varieties and years of rices were not shown. When the Jeung-Pyon was lost it's quality as a commercial product, the measured value of UTM was increased as hardness 0.74Kg to 1.0Kg, gumminess 0.23Kg to 0.59Kg, chewiness 6Kg.mm to 18Kg.mm, but decreased in adhesiveness 0.65Kg.mm to 0.40Kg.mm, cohesiveness 0.61 to 0.34, springiness 41mm to 32mm. The nonsealed Jeung-Pyon was lost it's quality for storing at room temperature because of the case-hardening after 2 days. In the case of sealed Jeung-Pyon, the case-hardening phenomena by the evaporation of moisture was not occured, therefore it was a significant factor for an extension in sealed Jeung-Pyon. The shelf-life of sealed Jeung-Pyon was 20 days and 5 days respectively during storage at $-20^{\circ}C$ and $20^{\circ}C$. The sealed Jeung-Pyon stored at $5^{\circ}C$ was lost it's quality, in consideration of cold chain this temperature was suitable for retrogradation of starch. The Jeung-Pyon sealed with air and mosture proof packaging material stored at the accelerated condition as 92% R.H. and $35^{\circ}C$ lost it's quality within two or three days.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.54-61
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• 2000

Amalgam, though a widely used dental material, does not bond to the tooth substrate Therefore, retentive preparation of the cavity is necessary. Such amalgam restorations, until corrosion products form and plug the margin, will show significant marginal leakage. Unless this is prevented early on, saliva and bacteria may enter the cavity causing postoperative hypersensitivity, dissolution and collapse of the restoration, discoloration of the margin and secondary caries, leading to shortened life-span of the restoration and pulpal pathosis. Recently, a method of restoration has been introduced whereby tooth material can be preserved, cavity margin can be sealed and preventive treatment of pit and fissure can be administered while retaining all the advantages of conventional amalgam restorations. Such sealed amalgams involve removing the carious lesion without extending the cavity for prevention and using pit and fissure sealants to seal cavity margins and pit and fissures to reduce microleakage. In this study, finishing of the amalgam and sealant application were performed after different intervals following of amalgam restoration to compare the microleakage of sealed and conventional amalgam restorations. Thirty bicuspids were prepared with Class V cavity preparations on the buccal and lingual surfaces. After amalgam placement, they were divided into the following groups and treated accordingly. Group 1 : Polishing after 24 hours Group 2 : Immediate sealant application without polishing Group 3 : No polishing, but sealant applied after thermocycling 500 times After treatment, the samples were thermocycled 500 times between $5^{\circ}C$ and $55^{\circ}C$ with a dwell time of 30 seconds. After thermocycling, the samples were dipped into 1% methylene blue kept in a $37^{\circ}C$ incubator at 100% humidity for 24 hours. The teeth were then embedded in resin and cut bucco-lingually along the tooth axis and observed with a stereomicroscope to determine the degree of microleakage, The following results were obtained : 1. Group 2 showed the least microleakeage, while group 1 showed the greatest. 2. Group 1 showed significantly greater microleakage compared to group 2 (p<0.05). However, no significant differences were found between group 1 and 3(p>0.05). No significant differences in microleakage were also found between cup 2 and 3(p<0.05).

• Bulletin of the Korean Chemical Society
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• v.16 no.12
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• pp.1235-1237
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• 1995

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.343-347
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• 1991

• Tribology and Lubricants
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• v.18 no.4
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• pp.273-278
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• 2002

Grease deterioration of mineral oil type grease was investigated using sealed deep groove ball bearings (6203) and bearing life test rig. The bearing test was performed under 3,000 rpm and 245 N radial load at 120。C. Grease taken ken tested bearings was checked in using certain evaluation methods, for example, oxidation induction time (OIT), FT-IR peak intensity, leakage .ate, bleeding .ate, total acid number. (TAN) and bearing noise increase. Within these test conditions, OIT, TAN, bleeding rate were changed gradually in accordance with bearing operating time and showed useful indices for deterioration of grease.

• Tribology and Lubricants
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• v.16 no.2
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• pp.75-83
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• 2000

The present paper proposes a new type of an electro-rheological squeeze film damper (ER SFD) of which the damping capacity can be controlled by the application of electric field. The new ER .SFD- is sealed with slotted rings having electrodes at the inside of the constant gap. The ER SFD can provent the problem of electric short which might be occurred in a previous ER SFD. Reynolds lubrication equation for a Newtonian fluid and the end leakage equation for ER fluids are numerically solved to get the pressure distributions and the damping coefficients of the ER SFD. The results show that the damping coefficients greatly increase with increasing the yield shear stress of ER fluid. In addition, the unbalance response analysis of a flexible rotor supported on the new ER SFD implies that the rotor system can be operated with the minimum of rotor amplitude and force transmissibility by controlling the yield shear stress of ER fluids properly.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.76-78
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• 2001

인터넷 사용이 급증하고 전자상거래의 발달과 동시에 전자 경매들이 인터넷 상에서 활발히 이루어지고 있다. 그 중에서 아웃크라이(Out-Cry) 스타일의 경매들은 봉인입찰(Sealed Bid) 경매에 비해서 많이 행해지고 있다. 봉인입찰 경매들을 인터넷 상에서 수행되었을 때에 보안상의 문제점을 가지고 있다. 가장 치명적인 단점은 경매자(Auctioneer)에 대한 신뢰문제로 입찰자(Bidder)들은 경매자가 자신의 입찰정보를 알아내어 다른 입찰자를 도와주거나 더 많은 이익을 얻기 위해서 입찰 정보를 조작하지 않을까 걱정한다. 이런 문제를 해결하기 위해서 몇몇의 보안 프로토콜이 등장하였는데, 그것들은 신뢰할 수 있는 제삼자(Trusted Third Party)와 다수의 입찰 매니져(Bidding Manager)를 둠으로써 해결하고 있다. 첫 번째 방법에서는 경매자에 대한 절대적 신뢰를 전제로 하고 두 번째 방법에서는 경매자와는 별도의 다른 기관들이 요구되어 진다. 이 논문에서는 다른 기관 없이 인터넷 상에서 안전하게 행해질 수 있는 봉인입찰 경매방법을 제시한다. 이 프로토콜은 Vickrey 경매와 FPSB 경매에서 모두 사용될 수 있고 다른 신뢰할 수 있는 제삼자의 도움 없이 입찰자와 경매자의 통신만으로 가능하기 때문에 비용이 절감된다.