공정조건 변화에 따른 탄산화 녹색건자재의 물성

김유택,Kim, Yootaek 한국결정성장학회 2013 한국결정성장학회지 Vol.23 No.3

발전소에서 발생되는 산업부산물인 석탄재는 포집방법에 따라 크게 저회와 비산회로 구분되는데, 순환유동층 연소방식에서 발생되는 비산회는 탄산화 반응 인자인 Ca 성분을 다량 포함하고 있다. 탄산화 반응 인자가 풍부한 비산회를 시멘트에 일정량 치환하여 제조한 경화체를 초임계 이산화탄소($CO_2$) 분위기조건에서 반응시켜 제작된 경화체의 기계적 물성향상을 도모하였다. 시멘트 대비 비산회 치환량을 10~40 %까지 10 % 단위로 4수준으로 하여 경화체를 제작하였으며 각각 3, 14, 28일 동안 양생하여 각 양생일 마다 탄산화를 진행하였으며 공정조건 변수로 탄산화 시 발생되는 수분과 미수화 반응물의 추가적인 포졸란 반응을 유도하기 위하여 탄산화 후 7일 동안 추가양생을 실시하였다. 공정조건의 변화를 변수로 둔 경화체의 무게변화율, TG/DTA 분석, 1 % 페놀프탈레인 알칼리성 측정을 통하여 탄산화 진행여부를 확인하였으며, 경화체의 압축강도 측정을 통해 기계적 물성향상을 분석하였다. 임계 탄산화 후 7일간 추가 양생시킨 녹색 건자재의 기계적 물성은 추가 양생하지 않은 시편과 비교해 44 % 향상되었다. The purpose of this study is to enhance the mechanical strength of specimens containing fly ash from fluidized bed type boiler, which the recycling rate will be eventually increased. Specimens containing fly ash in a certain portion were made and aged for 3, 14, and 28 days. Specimens were carbonated under the supercritical condition at $40^{\circ}C$. The carbonation process under the supercritical condition was performed to enhance the mechanical property of specimens by filling the voids and cracks existing inside cement specimen with $CaCO_3$ reactants. The additional aging effect after the supercritical carbonation process on mechanical strength of specimens was also investigated by comparing the compressive strength with and without 7 day extra aging. Under the supercritical condition and additional 7 day aging specimens were very effective for enhancement of mechanical strength and compressive strength increased by 44 %.

소형 스크류식 원심펌프의 기액 이상류 특성

김유택,다나카카즈히로,이영호,Kim, You-Taek,Tanaka, Kazuhiro,Lee, Young-Ho 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.4

A screw-type centrifugal pump was manufactured to carry primarily solids and its impeller had a wide flow passage. However, there was an effect on the flow passage shape on delay of the choke due to entrained air not being clarified yet. Moreover, because its impeller has a particular shape, only few studies have tried to clarify the pump performance and details of internal flow pattern of that pump. For this reason, we carried out the pump performance experiment under air-water two-phase flow condition with different impeller tip clearances, pump rotational speeds and void fractions by using a small screw-type centrifugal pump designed to acquire basic data. In a general centrifugal pump, it was reported that there was a loss of pump head from single-phase flow to the choke due to air entrainment near the best efficiency point being large. However, the loss near the best efficient point in a screw-type centrifugal pump became less than that in a general centrifugal pump.

공기 흡입이 소형 스크류식 원심펌프의 특성에 미치는 영향

김유택,다나카카즈히로,이영호,마쯔모토요이치로,Kim, You-Taek,Tanaka, Kazuhiro,Lee, Young-Ho,Matsumoto, Yoichiro 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.3

In a screw-type centrifugal pump, the pump head deteriorates from single-phase flow to the choke due to an increased air entrainment at a wide tip clearance compared to that of a narrow tip clearance. Moreover, at a narrow tip clearance, the pump head became partially higher in a two-phase flow than that of a single-phase flow near the best efficiency point in low void fraction region. Therefore, we observed the internal flow pattern by using a stroboscope and we measured the mean size of bubbles from the images obtained with a high speed camera. Then, we investigated the influences of the mean size of bubbles, tip clearances and flow patterns on pump performance.

SiC/C 경사기능재료 증착층의 변화

김유택,정순득,이성철,박진호,Kim, Yu-Taek,Jeong, Sun-Deuk,Lee, Seong-Cheol,Park, Jin-Ho 한국재료학회 1998 한국재료학회지 Vol.8 No.6

$SiC_{4}$$C_{3}$$H_{ 8}$$H_{2}$와 $C_{3}$$H_{8}$ $H_{2}$, $CH_{3}$$SiCI_{3}$$CH_{4}$$H_{2}$계를 사용하여 흑연기판 위에 SiC와 SiC/C FGM을 CVD법에 의해 코팅하였다. $SiCI_{4}$$C_{3}$$H_{8}$ $H_{2}$ 계에서 SiC 증착 시 바람직한 수소의 비는 10-30사이였고 결정 배향성은 입력가스의 탄소비에 따라 여러번의 대 반전이 일어났다. 성장조건을 {111} 배향성을 갖도록 조절하는 것이 FGM층간 접착상태를 증진시킬 수 있는 방법으로 판단되었다. $CH_{3}$$SiCI_{3}$C$_{3}$$H_{8}$ $H_{2}$ 계에서는 SiC와 C의 비율을 조절하기가 $SiCI_{4}$$C_{3}$$H_{8} $H_{2}$계를 사용했을 때 보다 용이하였고, FGM 단면 관찰에서 층간의 뚜렷한 경계를 발견할 수 없을 정도로 우수한 층간 접착상태를 보였다.

인공경량골재의 소성조건이 블랙코어에 미치는 영향

김유택,류유광,장창섭,이기강,강승구,김정환,Kim, Yoo-Taek,Ryu, Yu-Gwang,Jang, Chang-Sub,Lee, Ki-Gang,Kang, Seung-Gu,Kim, Jung-Hwan 한국결정성장학회 2009 韓國結晶成長學會誌 Vol.19 No.6

본 실험에서는 로터리 킬른으로 제조되는 인공경량골재의 실험실적 제어 가능성을 찾고자 여러 가지 소성조건에서 석탄 화력발전소에서 발생되는 바닥재와 준설토를 이용하여 인공경량골재를 제조하였다. 인공경량골재 조성은 바닥재 70 wt%와 준설토 30 wt%의 무게비로 성형하였고, 산화 분위기, 불활성 분위기, 환원 분위기에서 각각 $1150^{\circ}C$, $1200^{\circ}C$에서 소성하여 제조된 인공경량골재는 산화 분위기에서 명확한 블랙코어와 껍질(shell)간의 경계를 보이나, 불활성 분위기에서는 질소량이 증가할수록 그리고 소성온도가 증가할수록 경계가 없어지는 경향을 보이며, 환원 분위기에서는 단면 전체가 진회색을 띄게 된다. 로터리 킬른의 분위기와 가장 근접한 소성 분위기는 불활성분위기였으며 밀도나 흡수율 또한 그것과 유사하였다. 이러한 결과로 소형 전기로에서 로터리 킬른의 환경과 유사하게 조건을 제어할 수 있고, 물성을 예측할 수 있는 실험이 가능할 것으로 생각된다. The lightweight aggregates made of bottom ash (70 wt%) and dredged soil (30 wt%) were prepared to investigate the property differences at various sintering atmospheres. The green aggregates were sintered at $1150^{\circ}C$ and $1200^{\circ}C$ with oxidized, neutralized and reduced atmospheres. The aggregates sintered with oxidized atmosphere showed a clear border between shell and black core area. However, the aggregates sintered with a reduced atmosphere showed only black core area in the entire cross-section of the aggregates. The black core area of the aggregates sintered with a neutralized atmosphere increased with increasing $N_2$ gas flow rates. It was determined that the sintering atmosphere was similar to that of rotary kiln when the CO gas flow was 100 cc/min to make a reduced atmosphere in tube furnace. The water absorption rates of both aggregates from tube furnace with reduced atmosphere and rotary kiln were very similar to each other.

Adsorption behavior of heavy metal ions in the solutions of clay minerals under various conditions

김유택,J.H. Kim,K.G. Lee,강승구 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.1

The adsorption rates and characteristics of heavy metal ions (Cd, Cr, and Zn) were examined with solutions mixed with red clay, white clay, a mixture of red & white clay and zeolite under various pHs and initial concentrations. As expected, adsorption rates of heavy metal ions generally increased with increasing pH; however, Cr showed a particular behavior. A mixture of red & white clay among the clay minerals tried in this study showed the highest Cr adsorption rate at the low pH conditions (lower than pH 5) and red clay with additions of Cu, Fe and Pb ions at pH 5 showed above an 85% adsorption rate of Cr which was far from expectations. From the result, it is concluded that the adsorption characteristics of heavy metal ions depend not only on the physical properties of the absorbent itself such as the cation exchange capacity (CEC) but also on the concentration and existence of exchangeable cations, pH, ligands, etc.. The adsorption rates and characteristics of heavy metal ions (Cd, Cr, and Zn) were examined with solutions mixed with red clay, white clay, a mixture of red & white clay and zeolite under various pHs and initial concentrations. As expected, adsorption rates of heavy metal ions generally increased with increasing pH; however, Cr showed a particular behavior. A mixture of red & white clay among the clay minerals tried in this study showed the highest Cr adsorption rate at the low pH conditions (lower than pH 5) and red clay with additions of Cu, Fe and Pb ions at pH 5 showed above an 85% adsorption rate of Cr which was far from expectations. From the result, it is concluded that the adsorption characteristics of heavy metal ions depend not only on the physical properties of the absorbent itself such as the cation exchange capacity (CEC) but also on the concentration and existence of exchangeable cations, pH, ligands, etc..

Recycling of dust wastes as lightweight aggregates

김유택,J.H. Kim,K.G. Lee,강승구 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.2

Various kinds of industrial dust wastes were recycled by a wet ceramic process. Compounding various dusts gave allowed us compositional variation of dust wastes which originated from various places and conditions. One of the main problems for recycling wastes is caused by compositional variations. Success in recycling depends on how to control compositions and maintain the allowed purity level in the wastes. Grouping of dust wastes into three categories and compounding were introduced to raw material preparation processes for the successful recycling of various dusts. Pretreatment processes were also important to stabilize heavy metals in the raw materials. These processes consist of ion exchange, control of electrolyte concentration and pH etc. After these processes, industrial dust wastes were turned into safe, ecological construction materials such as bricks or lightweight aggregates by a final sintering process. Various kinds of industrial dust wastes were recycled by a wet ceramic process. Compounding various dusts gave allowed us compositional variation of dust wastes which originated from various places and conditions. One of the main problems for recycling wastes is caused by compositional variations. Success in recycling depends on how to control compositions and maintain the allowed purity level in the wastes. Grouping of dust wastes into three categories and compounding were introduced to raw material preparation processes for the successful recycling of various dusts. Pretreatment processes were also important to stabilize heavy metals in the raw materials. These processes consist of ion exchange, control of electrolyte concentration and pH etc. After these processes, industrial dust wastes were turned into safe, ecological construction materials such as bricks or lightweight aggregates by a final sintering process.

강제대류계(强制對流系)에 있어서 막비등열전달(膜沸騰熱傳達)에 관한 연구(硏究)

김유택,권순석,정대인,Kim, Y.T.,Kwon, S.S.,Jung, D.I. 대한설비공학회 1991 설비공학 논문집 Vol.3 No.1

The aim of this study is to investigate the heat transfer characteristics in the transient cooling process of a high temperature wall. The slow transient cooling experiment was carried out with a copper block of high thermal capacity. The results of these experiments are as follows. 1. Temperature histories measured by the thermocouple, which is 0.99, 2.00, 2.99mm from the heat transfer surface showed monotonous during the cooling process. These variation are the curves of typical temperature histories in film-boiling, transition-boiling, and nucleate-boiling regions. 2. The temperature histories were measured by thermocouple installed in the copper block. The variations of the surface heat fluxes and surface temperature were computed from the numerical solution method TDMA from the measured temperature histories for radial position one dimensional heat transfer inverse problem. The boiling curves were found by the computed temperature histories. 3. The rewetting point which starts to change from film boiling to nucleate boiling is not connected with the mass velocity and it were found that the temperature of rewetting point indicated about $100^{\circ}C$. 4. The heat flux of rewetting point was about $10^5Kcal/m^2h$, at that time, the heat transfer coeficient indicated about $1000Kcal/m^2h^{\circ}C$ irrelevent to mass velocity. 5. The wall superheat decreases as the pressure increases. But I found that rewetting point appeared under higher condition in the wall temperature.

석탄회 및 용융폐기물 슬래그에 소량의 알칼리 활성화제를 첨가한 무시멘트 모르타르의 특성

김유택,이경우,Kim, Yootaek,Lee, Kyongwoo 한국결정성장학회 2015 韓國結晶成長學會誌 Vol.25 No.6

현재 전 세계적으로 지구온난화의 주범인 $CO_2$ 저감을 위한 노력을 하고 있으며, 산업발전에 필요한 화력발전 등에서 발생한 부산물을 재활용하는 방안이 시급하다. 따라서 본 연구는 산업부산물인 비산재와 폐기물 슬래그를 이용하여 모르타르 경화체를 제작하였으며 알칼리 활성화제 첨가에 따른 물성을 비교하기 위해 비교적 낮은 농도인 3 M의 NaOH solution을 사용하였고, 이 경화체에 초임계 이산화탄소 조건($40^{\circ}C$, $80kgf/cm^2$ pressure, 60 min)에서 탄산화를 통하여 $CO_2$를 경화 체내에 안정적으로 고정화 시켜 이에 따른 물성을 평가하였다. 탄산화 인자인 CaO의 함량이 많을수록 탄산화율은 높게 나타났으며, 탄산화 후 무게변화율이 최대 약 12 % 증가하였다. 탄산화 후 압축강도는 전과 비슷한 수준이었으며, 이를 통해 탄산화를 통해 $CO_2$를 안정하게 고정화시킨 친환경 소재에 적용 가능성을 확인할 수 있었다. 또한 탄산화 반응 후에 생성되는 $H_2O$로 인해 추가적인 양생을 통해 장기적인 관점에서 탄산화를 통해 물성향상 또한 기대해 볼 수 있을 것으로 생각된다. Recently the world wide efforts reduce occurrence of $CO_2$; global warming main reason. The aim of this study is to improve recycling rate of the fly ash (FA) and fused waste slag (FWS) from the power plant and to carbonate under supercritical condition ($40^{\circ}C$, $80kgf/cm^2$ pressure, 60 min) for $CO_2$ fixation. Specimens of mortar with various mixing ratios of FA, FWS (from 100:0 to 20:80 in 5 steps of 20 % reduction each time), distilled water and 3 M NaOH alkali activators were prepared. As a result, the proportion of weight change ratio increases with CaO content, to 12 % after carbonation under the supercritical condition. There is difference of compressive strength between the carbonated and the alkali activator mortar specimens. The stabilization of $CO_2$ fixation through carbonation which could confirm the applicability of the eco-friendly materials without loss of compressive strength.

경제개발(經濟開發) 5개년계획(個年計劃)을 성공(咸功)시키는 길

김유택,Kim, Yu-Taek 한국과학기술정보연구원 과학기술정보센터 1963 Journal of Information Science Theory and Practice Vol.1 No.1