• Resources Recycling
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• v.25 no.2
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• pp.10-16
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• 2016

In this study, the Ni base superalloy was recycled by Argon oxygen decarburization(AOD) process using an inconel 713C scrap. During AOD process, argon gas was continuously injected 1,000 sccm and oxygen gas was injected into 10, 20 and 30 minutes of 100, 250 and 500 sccm.. In early stage of oxygen injection, the oxygen dose increased with increasing Al, Cr, and Mo content and decreasing C content. And Al content was decreased by carburization with added elements in late stage Because of oxidation was occurred with Al, Cr etc. after the reaction of carbon has been finished. From the results, the ratio of ${\gamma}^{\prime}$ phase reduced due to decreasing of Al content for that reason Al is the main element to form the ${\gamma}^{\prime}$ phase. Also carbide reduced owing to decreasing of C content so the mechanical properties of the specimens excessively injected by excess $O_2$ gas were decreased.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.121.2-121.2
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• 2011

석탄가스화복합발전과 연계하여 사용할 수 있는 $CO_2$분리법으로 연소 전 탈탄소화는 연료가 연소되기 전에 $CO_2$를 회수하는 방법으로 현재 여러가지 분리법이 사용되고 있다. 본 연구에서는 가스 하이드레이트의 다양한 응용 분야 중 이산화탄소 격리분야에서 합성가스로부터 $CO_2$롤 효과적으로 분리/회수하기 위하여 가스 고형화법에 관한 연구를 진행하였다. 가스 하이드레이트 형성과정에서의 반응 특성을 살펴보기 위하여 순수계와 촉진제 첨가계(TBAB, TBAF, THF)에 대하여 반응시간에 따른 가스소모량 및 기상의 $CO_2$ 조성 변화를 측정하였다. 그 결과 하이드레이트 상에 고농도의 $CO_2$가 포집되는 것을 확인 할 수 있었다. 순수계와 THF 첨가계의 경우 가스 소모량이 다른 계에 비하여 높게 나타났다. 이는 순수계의 경우 구조-I의 큰 동공과 작은 동공에 모두 기체가 점유되기 때문이며, THF 첨가계의 경우 구조-II의 큰 동공에만 기체가 점유되지만 THF의 첨가로 인해 전환율이 증가되기 때문이다. 반면, TBAF와 TBAB 첨가계의 경우에는 상재적으로 낮은 가스 소모량을 보였다. 기체 소모량이 큰 경우 최종 기상의 $CO_2$ 조성이 낮게 나타났다. 그리고 모든 실험조건에서 1시간 이내에 하이드레이트 형성반응이 종결되는 것을 확인할 수 있었다. 또한, 촉진제 첨가에 의한 하이드레이트의 구조적인 변화를 확인하기 위하여 Raman 분광법과 $^1H$-NMR을 이용하여 혼합가스 하이드레이트를 분석하였다. 본 실험으로 얻어진 결과는 가스 고형화법을 이용한 합성가스 분리 공정 설계 및 개발에 중요한 기초자료가 될 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.401-401
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• 2022

우리나라 대규모 하수처리장에 상용화되어있는 응집공정의 운영상 난점을 극복하고자 대체공정으로 고안된 인 결정여과공정(HCF, Hydroxyapatite Crystallization-Filtration process)의 pilot plant를 구축하고 부산슬러지의 자원화를 위해 그 특성을 검토하였다. 기존의 hydroxyapatite(HAP) 결정화공정 내 탈탄산(decarbonation) 단계를 생략하는 HCF공정의 경우에 고농도의 Ca²⁺ 주입과 처리수내 탄산염으로 인해 HAP을 포함하는 석회계 슬러지가 발생하는데, 이는 산성화된 토양의 개량제(중화제)로 널리 사용될 수 있다. 본 연구를 위해 경기도 I하수처리장 2차침전지 후단에 구축된 처리용량 27.1 - 135.6 m³/day HCF pilot plant의 전처리 조건은 pH 10.0 - 11.0, Ca²⁺ 농도 80 mg/L이었다. 결정여과조는 선속도 1.0 - 5.0 m/hr, 상향류로 운전되며, 여재는 2.0 - 3.0 mm의 석회석 모래를 충전하였다. 역세척은 중앙에 Air lifting pipe를 설치하여 역세척수가 처리수와 분리배출되도록 설계하였고, 침전시켜 역세척 슬러지를 회수하였다. 처리수의 평균 T-P, PO₄-P 및 SS는 각각 0.05, 0.04, 1.1 mg/L으로 모든 항목에서 방류수 수질기준 이하로 안정적으로 유출되었다. 회수된 HCF 슬러지는 SEM-EDX, XRD, FT-IR을 활용하여 그 특성을 분석하였다. SEM-EDX로 분석된 슬러지의 원자분율은 CaCO₃ 또는 HAP으로 추측되었다. 또한, XRD spectrum 분석결과, 슬러지의 주요 구성성분은 calcite, HAP, phosphoric acid(H₃PO₄) 및 brusite로 나타났다. FT-IR 분석결과, 슬러지는 대부분 인산염 및 탄산염의 무기물로 구성되어 있으며, 유입수의 인 농도가 높을수록 슬러지 내 HAP의 함량이 calcite보다 높은 것으로 나타났다. 고농도의 Ca²⁺을 주입하여 탈탄산단계를 생략한 HCF의 부산슬러지는 HAP 이외에도 CaCO₃와 칼슘-인 화합물로 구성되어 있는 것으로 나타났다. 하수 인 고도처리를 위한 HCF공정의 하수처리시설 인 고도처리 적용이 검증되었으며, 부산슬러지를 산성화된 토양의 개량제(중화제) 또는 비료로서의 재활용 및 자원화 가능성이 시사되었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.1
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• pp.27-38
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• 2023

How the port, shipping, shipbuilding, and vender industries in Korea can have a seamless value chain through their digitally smooth cooperation by applying the latest information and communications technology through the "4th industrial revolution" was examined. Also considered was the proposition that the value chain should be a smart, seamless value chain among industries with successful hyperconnection. Their cooperative relationships were defined, and the crucial elements for the sustainable development of these industries were considered. As a result, the direction for achieving environmental, social, and governance management by realizing decarbonization through today's digitalization could be studied. In particular, the importance of digitization as a way to respond to the future market from the perspective of small and medium-sized enterprises and the role of digitization realized by small and medium-sized equipment companies in the overall industry were examined. The results simultaneously show the state of linkage between industries and the reason why the value chain must maintain a smooth relationship. In addition, using the lessons learned from recent failure cases from the Korean shipbuilding industry as a cornerstone, the direction for creating a strategic pathway for intelligent connection was investigated.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.1-8
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• 2023

In this study, to reduce CO₂ emission in the cement manufacturing process, we evaluated the limestone that is used as a raw material for cement, substituted with steel slag by the various substituted levels. Based on the chemical composition of each raw materials including limestone, and blast furnace slow cooling slag, converter slag, and KR slag as an alternative raw material, we simulated the optimal cement raw mixture by the substitution levels of limestone. Test results indicated that the steel slags contain a certain level of CaO that can be used as alternative decarbonated raw materials, and it has enough to partially reduce the amount of limestonem. And we estimated the maximum usable levels of each raw material. In particular, it was confirmed that by using a mixture of these raw materials rather than using them one by one, the effect of reducing limestone was increased and CO₂ emission from the cement manufacturing process could be reduced.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.68-69
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• 2023

Recently, decarbonization has been emphasized worldwide to cope with climate change, and carbon neutrality by 2050 has emerged as a global agenda. The domestic port authorities have been participating in the global agenda in line with the government regulations. Since 2010, when decarbonization has been regarded as an important assignment in ports, container terminal efficiency considering undesirable outputs such as Carbon dioxide has been analyzed. However, most previous studies measured carbon dioxide emissions according to the Tier 1 and it is a first time to analyze container terminal efficiency based on the Tier 3 presented in the IPCC guidelines. 17 domestic container terminal operators were considered as decision making units and DEA-SBM Model was used. Subsequently, Undesirable outputs model was conducted to calculate the environmental efficiency.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.171-180
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• 2024

Recently, there has been a global emphasis on decarbonization in order to address climate change and achieve carbon neutrality by 2050. In line with government regulations, domestic port authorities have also started participating in this global agenda. Since 2010, when decarbonization became an important task in ports, there have been studies analyzing the environmental efficiency of container terminals, taking into account undesirable outputs. However, most of these previous studies only measured carbon dioxide emissions based on Tier 1, whereas this study is the first to analyze the environmental efficiency of South Korea's container terminals based on Tier 3, as presented in the IPCC guidelines. The study considered 17 container terminal operators in South Korea as decision-making units and used the DEA-SBM Model. Subsequently, an Undesirable Outputs Model was conducted to calculate the environmental efficiency.

• Journal of Korea Foundry Society
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• v.12 no.4
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• pp.298-304
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• 1992

Decarburization phenomena of SM50C steel casted in ceramic mold was investigated. As result, decarburized depth increased by increased by increasing the volume-to-surface area ratio and mold temperature. And the relations between them is $y(cm)=(1.96{\times}10^{-5}T+0.0135)\;{\times}M-1.05{\times}10^{-5}T+9.73{\times}10^{-3}$. When mold is controlled by Ar ags, reducing atmosphere, decarburized depth is decreased. In case of adding graphite powder in the mold, decarburization is decreased more. Specially, when graphite powder is added on the mold materials and the wax is layed on the mold, decarburization is almost prevented.

• YAKHAK HOEJI
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• v.38 no.6
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• pp.791-794
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• 1994

Sixteen kinds of naturally occurring phenolic compounds including 5 stilbenes, 7 flavonoids and 4 anthraquinones were examined in the inhibitory activity against rat liver AADC(aromatic L-amino acid decarboxylase) in vitro, using 5-hydroxytryptophan as a substrate. Three hydroxystilbenes, resveratrol 1, rhapontigenin 3 and piceatanol 5, which were known to be monoamine oxidase A inhibitors, exhibited a significant inhibition against AADC($IC_{50}$=20, 8 and $5\;{\mu}M$, respectively). By the comparison of the activity of each phenolic compound, it was suggested that the 3',4'-dihydroxyphenyl group of stilbenes or flavones was the best pharmacophore for the AADC inhibitory activity.

• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.28-33
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• 2001

WC-6%Co 소결체를 열처리할 때 발생하는, 시편 표면에서의 급격한 입자 성장 거동을 열처리 분위기를 변수로 하여 관찰하였다. 열처리 분위기로 수소와 메탄을 각각 사용하였고, 온도는 1400~145$0^{\circ}C$, 압력은 1~3 Torr, 그리고 시간은 100분까지 변화시켰다. 표면에서의 입자 성장은 수소 분위기보다 메탄 분위기를 사용하는 경우 훨씬 빠르게 일어났다. 그리고 열처리 온도가 증가할수록, 압력이 감소할수록 입자 성장 속도가 증가하였다. 이때 성장한 입자의 크기 분포는 비정규 분포를 보였다. 한편, 입자 성장은 열처리시 증발하는 시편의 Co 무게 감소와 밀접한 관계를 보였다. 이러한 표면에서의 입자 성장 현상을 열처리한 조건과 관련되어 WC-Co 상태도에서 예측할 수 있는, 탈탄-탄화 반응 및 비정상 입자 성장 현상 관점으로 설명하였다.