• Magazine of RCR
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• v.17 no.2
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• pp.59-63
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• 2022

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.15-15
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• 2009

최근 컨테이너선은 점차 대형화되고 있으며, 이에 따라 선체의 외판 상부의 철판 두께도 최대 80mm 까지 설계되고 있다. 블록 외판의 수직 맞대기 용접의 경우 고능률 용접기법인 Electro Gas Weldig(이하 EGW)이 적용되고 있으나, 극 후판의 경우, 기존의 한 개의 전극만으로는 적용 가능한 두께 범위의 한계가 있어 수직 맞대기 용접의 용접생산을 향상시키기 위해 2개의 전극을 사용하는 탄뎀 EGW 기법에 의한 시공법이 고려되었다. 탄뎀 EGW 기법의 시공법에 관한 보고서는 국내외에서 많이 발표되어져 왔다. 하지만 실선 적용에 있어 두께 80mm, 길이 2M 이상의 철판을 안정적으로 용접하기 위한 장애요소는 용접 중 적절한 슬래그의 배출 조절이다. 두개의 용접 와이어를 동시에 공급할 때 발생하는 슬래그를 균형있게 배출하지 못하는 경우 용융, 금속 상부에 적층되는 슬래그의 양이 증가하게 되고, 아크는 불안해져서 전극팁에의 슬래그 부착, 전극 팁의 발열 등에 의한 요인들이 송급을 불안하게 하여 연속 용접이 어려워진다. 본 연구에서는 탄뎀 EGW 기법을 실제로 현업에 적용하기 위해서는 안정적인 슬래그 배출에 착안하여 동당금의 형상에 따라 슬래그의 배출 성능을 확인하고 형상별 전류, 전압 파형을 측정하고, 파형 결과에 따라 아크 안정성을 평가함으로서 탄뎀 EGW 용접기법에 적정한 동당금을 설계한 결과를 소개하고자 하였다.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.1
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• pp.69-75
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• 2013

This study is a fundamental research to test the applicability of powdered MSWI(Municipal Solid Waste Incinerator) ash melted slag as a seed Crystal for crystallization reaction. Powdered ash melted slag was melted at $1100^{\circ}C$ and ground to lesser than 0.35mm. According to the result of the tests, calcium, enough for crystallization reaction, was eluted from powdered ash melted slag. Moreover, sample(Phosphorus concentration is under 10 mg/L), more than 90% of Phosphorus can be removed. So we rectify the Phosphorus concentration to 100 mg/L. Alkalinity, being well known that it interferes crystallization reaction, effect was studied for synthetic solution(100 mg/L initial Phosphorus concentration, 50 mg/L calcium, pH 8, 1% powdered ash melted slag dosage). For this result, we know that Phosphorus removal is hindered by alkalinity. In addition, the effect of reaction temperature was performed at the same method. The reaction velocity was increased through raising the reaction temperature.

• Journal of the Korea Institute of Building Construction
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• v.19 no.5
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• pp.391-399
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• 2019

This study reviewed the possibility of recycling into exhausted aggregate resources in Korea as a means of utilizing coal gasification slag(CGS) from integrated gasification combined cycle(IGCC) while being commissioned in order to introduce the new system to Korea. In other words, in order to solve the problem of insufficient aggregate resources, CGS generated by IGCC as a residual aggregate for concrete secondary products, which is an empty mortar, was considered to replace CGS in the range of 0 to 100 % for mixed residual aggregate mixed with crushed sand A(CSa) of good quality and sea sand(SS) of deep particles, which are the most commonly used in the domestic construction industry. According to the study, replacing CGS with CSa or crushed sand B(CSb)+SS by 25 % to 50 % resulted in good results in the aspect of the granularity of the aggregate and the workability and compressive strength of cement mortar, which were found to be usable.

• Resources Recycling
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• v.17 no.4
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• pp.57-65
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• 2008

The behavior of Na-A type zeolite formed in hydrothermal synthesis of melting slag from municipal incineration ash has been investigated with varying synthesis time and $SiO_2/Al_2O_3$ ratio. Sodium silicate and sodium aluminate feed was found to initially form nuclei of Na-A type zeolite in the behavioral study of the reaction products with different synthesis times. As the synthesis time increased, the nuclei have grown to Na-A type zeolite crystals by reacting with $SiO_2$ and $Al_2O_3$ dissolved from the melting slag. The hydrothermal synthesis was completed in 10 hr in the $SiO_2/Al_2O_3$ ratio of 1.38 and after that time, the Na-A type zeolite formed was dissolved and transformed into hydroxysodalite. Only Na-A type zeolite was formed in the $SiO_2/Al_2O_3$ ratio ranging 0.80 to 1.96, whereas Na-P type zeolite as well as Na-A type was formed in the $SiO_2/Al2O_3$ ratio of 2.54.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.114-118
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• 2009

With the advance of industrialization and urbanization, a lot of waste has been discharged and treated by incineration. But fly and bottom ashes are generated in this process. In addition, the treatment method to recycle sewage sludge and melting slag is required to manage these wastes. The objective of this research was to prepare of multi-functional brick which were made from MSWI (Municipal solid wastes incinerator) fly ash, sewage sludge and slag. The bricks were made by mixing raw materials and then drying for 24 hours. Next, they were dried for 24 hours at $160^{\circ}C$ and fired for 2 hours. Calcination temperature was changed to discuss the effect of temperature from $1,080^{\circ}C$ to $1,130^{\circ}C$. Compressive strength of a brick was creased with the increase of temperature. To increase mixing ratio of fly ash and slag reduce the compressive strength the optimal condition was the mixing ratio of fly ash : melting slag : sewage sludge : clay as 10 : 20 : 5 : 65 and $1,150^{\circ}C$ of calcination temperature. Compressive strength was obtained as about 41 MPa at this condition.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.25-31
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• 2010

In this study, it was intended to suggest new cooling method that enables to improve the applicability and added value higher than existing slag by applying new cooling method(powder cooling slag) at the time discharging slag, which is produced from the ash melting system that the plasma torch is used for the first time in Korea. It is suggested the applicative direction in the development of future recycling process by discovering its nature of material and applicative possibility as earthwork material. The ashes produced after the sewage sludge discharged from Y city was incinerated by the fluidized bed method and was used as test materials. As result of XRF(X-Ray Flourescence Spectrometry) analysis, main ingredient of sewage sludge ashes was $SiO_2$(32%) besides CaO, $Al_2O_3$, $Fe_2O_3$, and so on. In addition, as result of XRD analysis, traditional diffuse pattern of glass could be found from granulated air-cooled slags, while a minor crystal phase could be observed from powder cooling slag, because the powder on the surface exists in the state not melted. From EDX(Energy Dispersive X-ray Spectroscopy) analysis, it is deemed that powder ingredient has no change before and after it is used as cooling medium, and accordingly it is thought that the powder can be produced as the material where the function is added if used in different shape.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.166-167
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• 2019

In this study, to test the performance of concrete used as a concrete admixture as a recycling method of CGS, gypsum was mixed and the chloride ion penetration resistance test of CGS and BFS substituted concrete was conducted. As a result, it was found that without gypsum type test specimen, the CGS sustituted test specimens had lower chloride ion penetration resistance than the BFS substituted specimens. When gypsum was added, it was confirmed that the chloride ion penetration resistance was poor regardless of the type of admixture. In addition, it was confirmed that both admixtures were less resistant to chloride ion penetration than OPC, regardless of the presence of gypsum. However, considering the uneven quality variation of coal, which greatly affects the quality of CGS, further research is needed.

• Resources Recycling
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• v.13 no.1
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• pp.47-53
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• 2004

As a basic study of the re-using molten converter slag as an ordinary portland cement by conversion process, molten slag and sintered CaO pellet was reacted each other. The dissolution rate of the sintered CaO pellet into the molten slag was measured and the changes of the reaction layer was also investigated. The converter slag reagent-grade $SiO_2$ added was melted and hold for 30 minutes in MgO crucible between $1350∼1500 ^{\circ}C$. Then sintered CaO pellet heated at the same temperature was dipped into the molten slag and hold for 10∼30 min. After the reaction, the crucible was cooled in air and the specimen was cut off to the horizontal direction of the crucible. The dissolution rate of CaO pellet was measured by the change of the radius of sintered CaO pellet and the interface layer was observed by SEM/EDX and XRD. The dissolution rate of sintered CaO pellet contacted with the slag of basicity 1 was 9.8 $\mu\textrm{m}$/min at $1350^{\circ}C$ and increased to 18.0 $\mu\textrm{m}$/min at $1500^{\circ}C$. The rate was slightly decreased to 7.6 $\mu\textrm{m}$/min at $1350^{\circ}C$ and 15.0 $\mu\textrm{m}$/min at $V^{\circ}C$ in the slag of basicity 2. The dissolution rate of CaO in converter slag was followed to the rule of Arrhenius' temperature dependency, and the apparent activation energy of the dissolution of CaO was 36 kcal/mole. In case of the slag basicity of 1, the thickness of $C_2$S layer was 64-118 $\mu\textrm{m}$ and the thickness of $C_3$S was 28∼90 $\mu\textrm{m}$ for 10∼30 minutes at $1500^{\circ}C$. And the thickness of the $C_3$S layer was 90∼120 $\mu\textrm{m}$ at the same conditions in the slag basicity of 2.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2002.05a
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• pp.103-104
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• 2002