• Proceedings of the Korea Technology Innovation Society Conference
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• 2017.11a
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• pp.1533-1549
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• 2017

정부 R&D성과의 질적 수준을 제고하고 중장기 국가 재정사업의 효율성을 높이기 위한 각 연구 기관의 시도들이 있어 왔다. 연구사업의 발굴, 기획 및 수행에 있어 효과적인 정부 R&D 예산의 배분, 우선순위를 도출, 기술개발 전략 수립을 하는 것이 매우 중요해지고 있다. 정부 재정사업인 국가 R&D사업은 국가 기간산업을 활성화하고 경제발전을 수반할 수 있는 중요한 모멘텀으로서의 역할을 하고 있다. 또한, 국가 R&D사업의 한 축인 거대과학은 최첨단 기술의 개발과 미래성장동력의 발굴이라는 대명제로 그 중요성이 강조되고 있다. 거대과학 연구는 그 분야의 특수성으로 인해 대학의 과학자, 공공 연구기관의 연구원, 기업의 엔지니어가 함께 참여하여야 하고 대규모 국가 예산을 동원하는 과학 연구 사업이다. 이는 대규모 예산을 기반으로 하고 있기에 집중적 투자가 수반된다면 단기적으로 기초과학의 발전을 이뤄낼 수 있다. 이것은 산업발전에 밑거름이 되어 그 분야 자체로 하나의 산업생태계를 구성하고 요소 기술들의 응용으로 파생기술이 전파된다면 새로운 신산업 창출 등 국가산업에 많은 혜택을 줄 수 있다. 하지만 많은 인력과 대규모 투자 그리고 중장기 프로젝트라는 특성으로 인해 실패 가능성도 높아 전략적 선택 및 추진이 필요하다. 따라서 본 논문에서는 거대과학의 기술개발전략의 수립을 위하여 중이온 입자가속기 핵심부품 국산화 전략수립 사례를 중심으로 효율적인 R&D추진 방안을 도출해보고자 한다. 또한, 논문, 특허를 기반으로 한 3P분석을 통하여 중이온 가속기 핵심부품의 국산화 전략을 제안하고, 추진 우선순위 및 전략을 제시하고자 한다.

• Journal of Radiation Protection and Research
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• v.48 no.3
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• pp.131-143
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• 2023

Background: This study examined the detection limit of thyroid screening monitoring conducted at the time of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011 using a Monte Carlo simulation. Materials and Methods: We calculated the detection limit of a NaI(Tl) survey meter to measure ¹³¹I accumulation in the thyroid gland of children. Mathematical phantoms of 1- and 5-year-old children were developed in the simulation of the Particle and Heavy Ion Transport code System code. Contamination of the body surface with eight radionuclides found after the FDNPP accident was assumed to have been deposited on the neck and shoulder area. Results and Discussion: The detection limit was calculated as a function of ambient dose rate. In the case of 40 Bq/cm² contamination on the body surface of the neck, the present simulations showed that residual thyroid radioactivity corresponding to thyroid dose of 100 mSv can be detected within 21 days after intake at the ambient dose rate of 0.2 µSv/hr and within 11 days in the case of 2.0 µSv/hr. When a time constant of 10 seconds was used at the dose rate of 0.2 µSv/hr, the estimated survey meter output error was 5%. Evaluation of the effect of individual differences in the location of the thyroid gland confirmed that the measured value would decrease by approximately 6% for a height difference of ±1 cm and increase by approximately 65% for a depth of 1 cm. Conclusion: In the event of a nuclear disaster, simple measurements carried out using a NaI(Tl) scintillation survey meter remain effective for assessing ¹³¹I intake. However, it should be noted that the presence of short-half-life radioactive materials on the body surface affects the detection limit.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.301-308
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• 2024

Ceramic materials are being explored as alternatives to toxic lead sheets for radiation shielding due to their favorable properties like durability, thermal stability, and aesthetic appeal. However, crafting effective ceramics for radiation shielding entails complex processes, raising production costs. To investigate local viability, this study evaluated Malaysian ceramic tiles for shielding in diagnostic X-ray rooms. Different ceramics in terms of density and thickness were selected from local manufacturers. Energy Dispersive X-ray Fluorescence (EDXRF) and X-ray Fluorescence (XRF) characterized ceramic compositions, while Monte Carlo Particle and Heavy Ion Transport code System (MC PHITS) simulations determined Linear Attenuation Coefficient (LAC), Half-value Layer (HVL), Mass Attenuation Coefficient (MAC), and Mean Free Path (MFP) within the 40-150 kV energy range. Comparative analysis between MC PHITS simulations and real setups was conducted. The C3-S9 ceramic sample, known for homogeneous full-color structure, showcased superior shielding attributes, attributed to its high density and iron content. Notably, energy levels considerably impacted radiation penetration. Overall, C3-S9 demonstrated strong shielding performance, underlining Malaysia's potential ceramic tile resources for X-ray room radiation shielding.

• Resources Recycling
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• v.16 no.6
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• pp.3-9
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• 2007

Although the ferrous material was separated by the magnetic separation before the incineration process, the municipal solid waste incineration bottom ash generated during incinerator in metropolitan area consists of many iron products which account for about $3{\sim}11%$ as well as ceramics and glasses. The formation of $NiFe_2O_4$ and $FeCr_2O_4$ with a $Fe_3O_4-Fe_2O_3$ (similar to pure Fe) on the surface of iron product was found during air-annealing in the incinerator at $1000^{\circ}C$, because Ni and Cr has a chemical attraction about iron is using to coat with Ni and Cr metals for poish or to prevent corrosion. Therefore, Fe-Ni Cr oxide can be formed on durface of the iron product and it can be separated from bottom ash through the magnetic separation. So, in this study, the separation ratio of heavy metals as magnetic separation and mineralogical formation of Fe-ion(heavy metal) in ferrous metals corroded were investigated. As the result, the separation ratio of Ni and Cr based on particle sizes accounted for about $45{\sim}50%$, and Cu and Pb accounted for below 20%. Also, the leaching concentration of Ni and Cr in bottom ash separated by magnetic separation was lower than that in fresh bottom ash.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.704-712
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• 2006

This research was designed to investigate the removal of heavy metals, such as $Al^{3+}$, $Cu^{2+}$, $Mn^{2+}$, $Pb^{2+}$ and $Zn^{2+}$, by adsorption on clay minerals. Bentonite(Raw-Bentonite), $Ca^{2+}$ and $Na^+$ ion exchanged bentonite(Ca- and Na-Bentonite) and montmorillonite, such as KSF and K10 from Sigma Aldrich, were used as adsorbents. The component of five inorganic adsorbents was analyzed by XRF, and the concentration of metal ions was measured by ICP. The cation exchange capacity(CEC) and the particle charge of adsorbents were measured. The initial concentration range of metal ions was $10{\sim}100$ mg/L. From the experimental results, it was shown that the adsorption equilibrium was attained after $1{\sim}2$ hours. The maximum percentage removal of $Al^{3+}$, $Cu^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ on Na-Bentonite were more than 98% and that of $Mn^{2+}$ was 66%. $Al^{3+}$ was leached out from KSF with the higher concentration of hydrogen ion. Percentage removals of $Pb^{2+}$ and $Zn^{2+}$ on KSF were 88% and 59%, respectively. In general, the percentage removal of metal ions was decreased with the higher initial concentration of metal ions. The adsorption capacity of metal ions on Na-Bentonite was $1.3{\sim}19$ mg/g. Freundlich equation was used to fit the acquired experimental data. As the results, the adsorption capacity of metal ions was in the order of Na-Bentonite$\gg$Raw-Bentonite$\cong$K10>Ca-Bentonite>KSF. Freundlich constant, K of Na-Bentonite was the largest for metal ions. The order K of Na-Bentonite was Al>Cu>Pb>Zn>Mn, and the adsorption intensity(1/n) was determined to be $0.2{\sim}0.39$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.112-118
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• 2018

In order to meet the strict emission regulations for internal combustion engines based on fossil fuel, the proportion of after-treatments for vehicles and vessels is gradually increasing. Diesel engines have high power, good fuel economy, and lower $CO_2$ emissions, and their market shares are increasing in commercial vehicles and passenger cars. However, NOx is generated in the localized high-temperature combustion regions, and particulate matter is formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for after-treatment of the exhaust gas to reduce NOx in diesel vehicles. This study aims to improve the NOx reduction performance of Cu SCR catalyst, which is widely used in light, medium, and heavy-duty diesel engines. The de-NOx performance of $5Cu-2ZrO_2$/93Zeolyst(Si/Al=13.7) SCR catalyst was about 5-50% higher than that of $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) at catalyst temperatures of $300^{\circ}C$ or higher. The zeolite had lower metal dispersion than zeolyst, and the reaction rate of the catalyst decreased as the average particle size increased. The $10Cu-2ZrO_2$/88Zeolyst catalyst loaded with 10wt% Cu had the highest NOx conversion rate of 40% at $200^{\circ}C$ and about 65% at $350^{\circ}C$. The ion exchange rate of Cu ions increased with that of Al, the crystalline compound of zeolite, and the de-NOx performance was improved by 20-40% compared to other catalysts.

• Journal of Radiation Protection and Research
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• v.45 no.3
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• pp.130-141
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• 2020

Background: Concrete activation in cyclotron vaults is a major concern associated with their decommissioning because a considerable amount of activated concrete is generated by secondary neutrons during the operation of cyclotrons. Reducing the amount of activated concrete is important because of the high cost associated with radioactive waste management. This study aims to investigate the capability of the neutron absorbing materials to reduce concrete activation. Materials and Methods: The Particle and Heavy Ion Transport code System (PHITS) code was used to simulate a cyclotron target and room. The dimensions of the room were 457 cm (length), 470 cm (width), and 320 cm (height). Gd₂O₃, B₄C, polyethylene (PE), and borated (5 wt% ^natB) PE with thicknesses of 5, 10, and 15 cm and their different combinations were selected as neutron absorbing materials. They were placed on the concrete walls to determine their effects on thermal neutrons. Thin B₄C and Gd₂O₃ were placed between the concrete wall and additional PE shield separately to decrease the required thickness of the additional shield, and the thermal neutron flux at certain depths inside the concrete was calculated for each condition. Subsequently, the optimum combination was determined with respect to radioactive waste reduction, price, and availability, and the total reduced radioactive concrete waste was estimated. Results and Discussion: In the specific conditions considered in this study, the front wall with respect to the proton beam contained radioactive waste with a depth of up to 64 cm without any additional shield. A single layer of additional shield was inefficient because a thick shield was required. Two-layer combinations comprising 0.1- or 0.4-cm-thick B₄C or Gd₂O₃ behind 10 cm-thick PE were studied to verify whether the appropriate thickness of the additional shield could be maintained. The number of transmitted thermal neutrons reduced to 30% in case of 0.1 cm-thick Gd₂O₃+10 cm-thick PE or 0.1 cm-thick B₄C+10 cm-thick PE. Thus, the thickness of the radioactive waste in the front wall was reduced from 64 to 48 cm. Conclusion: Based on price and availability, the combination of the 10 cm-thick PE+0.1 cmthick B₄C was reasonable and could effectively reduce the number of thermal neutrons. The amount of radioactive concrete waste was reduced by factor of two when considering whole concrete walls of the PET cyclotron vault.

• Journal of Environmental Impact Assessment
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• v.29 no.3
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• pp.157-181
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• 2020

Sediments from rivers, lakes and marine ports serve as end points for pollutants discharged into the water, and at the same time serve as sources of pollutants that are continuously released into the water. Until now, the contaminated sediments have been landfilled or dumped at sea. Landfilling, however, was expensive and dumping at sea was completely banned due to the London Convention. Therefore, this study applied contaminated sedimentation soil of 'Royal Palace Livestock Complex' as soil purification method. Soil remediation methods were applied to pretreatment, composting, soil washing, electrokinetics, and thermal desorption by selecting overseas application cases and domestically applicable application technologies. As a result of surveying the site for pollutant characteristics, Disolved Oxigen (DO), Suspended Solid (SS), Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP) exceeded the discharged water quality standard, and especially SS, COD, TN, and TP exceeded the standard several tens to several hundred times. Soil showed high concentrations of copper and zinc, which promote the growth of pig feed, and cadmium exceeded 1 standard of Soil Environment Conservation Act. In the pretreatment technology, hydrocyclone was used for particle size separation, and the fine soil was separated by more than 80%. Composting was performed on organic and Total Petroleum Hydrocarbon (TPH) contaminated soils. TPH was treated within the standard of concern, and E. coli was analyzed to be high in organic matter, and the fertilizer specification was satisfied by applying the optimum composting conditions at 70℃, but the organic matter content was lower than the fertilizer specification. As a result of continuous washing test, Cd has 5 levels of residual material in fine soil. Cu and Zn were mostly composed of ion exchange properties (stage 1), carbonates (stage 2), and iron / manganese oxides (stage 3), which facilitate easy separation of contamination. As a result of applying acid dissolution and multi-stage washing step by step, hydrochloric acid, 1.0M, 1: 3, 200rpm, 60min was analyzed as the optimal washing factor. Most of the contaminated sediments were found to satisfy the Soil Environmental Conservation Act's standards. Therefore, as a result of the applicability test of this study, soil with high heavy metal contamination was used as aggregate by applying soil cleaning after pre-treatment. It was possible to verify that it was efficient to use organic and oil-contaminated soil as compost Maturity after exterminating contaminants and E. coli by applying composting.