• 한국산학기술학회논문지
• /
• 제8권2호
• /
• pp.372-379
• /
• 2007

전로슬래그는 폐수 중에 함유된 인산염을 고형물 형태로 제거하는데 유용하게 사용될 수 있다 본 연구는 전로슬래그를 이용하는데 있어서 폐수의 초기 조건에 따라 전로슬래그로 인한 폐수의 pH, 알칼리도 그리고 양이온 용출변화에 따른 인산염 제거 등에 관하여 연구하였다. 실험대상 폐수의 pH를 0.5 단위로 7.0부터 8.5까지 다른 초기조건에서 폐수의 pH는 10시간 내에 급격하게 pH 11이상까지 상승하였다. 알칼리도는 pH보다는 급격하게 상승하지는 않았지만 반응시간 10 시간이 경과한 후 꾸준하게 상승하였다. 인산염 제거는 pH상승, 알칼리도 상승과 함께 반응시간 10시간까지 급격하게 제거되다가 서서히 제거되는 양상을 보였다. 반응시간 27시간 경과 후 그리고 36 시간 경과 후 전로슬래그에 함유된 마그네슘 이온 용출 농도를 측정한 결과 2.0 mg/L과 4.3 mg/L 수준까지 지속적으로 용출 되었다. 본 실험 결과 전로슬래그에 함유된 마그네슘이 용출되었기 때문에 물속에 암모니아가 존재한다면 인산염과 함께 스트루바이트 형태의 결정체로 인이 제거될 수 있음을 확인하였다.

• 상하수도학회지
• /
• 제10권1호
• /
• pp.78-84
• /
• 1996

The presence of ammonia, usually in the form of ammonium ion ($NH_4{^+}$), can enhance bacterial growth m the distribution system and make the production of drinking water more costly if ammonium must be removed to ensure good disinfection. Removal of ammonia by biological oxidation could be economical which prevents excess chlorine dosage In this research, effects of hydraulic retention time (HRT) and media type on the ammonia removal efficiencies of submerged biofilm reactor were investigated. The biofilm reactors combined the characteristics of high biological solids capture efficiency and good hydraulic control. The results indicate that biofilms can remove over 77 percent of the ammonia with HRT of longer than 2 hr even at low temperature ranging from 14.6 to $16.6^{\circ}C$. The HRT has a significant effect on nitrification. The overall nitrification and efficiency of ammonia removal increase with increasing HRT. It has also been observed that when the fibrous media was used, the ammonia removal, nitrification rate and endurance to shock improved.

• 산업기술연구
• /
• 제21권A호
• /
• pp.279-284
• /
• 2001

In this study, we analyzed the $NO_X$ removal effiency by the low temperature plasma process and investigated the effect of several process variables. Most of NO is converted into $NO_2$ and, later, into $HNO_3$ which reacts with $NH_3$ to form $NH_4NO_3$ particles. As the frequency of appling voltage increases, as the applied voltage increases or as the residential time increases, removal efficiency of the NO supplied initially increase. The removal efficiency of $NO_X$ also increases with the increase of $NH_3$ supplied.

• Advances in environmental research
• /
• 제7권1호
• /
• pp.53-71
• /
• 2018

Waste glass disposal causes environmental problems in the cities. To find a suitable green environmental solution for this problem low cost adsorbent in this study was prepared from waste glass. An effective new green adsorbent was synthesized by hydrothermal treatment of waste glass (WG), followed by acidic activation of its surface by HCl (WGP). The prepared adsorbent was characterized by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), and BET surface measurement. The developed adsorbent was used for the removal of heavy metals (Cd, Cu, Fe, Pb and Zn) from well water. Batch experiments were conducted to test the ability of the prepared adsorbent for the removal of Cd, Cu, Fe, Pb and Zn from well water. The experiments of the heavy metals adsorption by adsorbent (WGP) were performed at different metal ion concentrations, solution pH, adsorbent dosage and contact time. The Langmuir and Freundlich adsorption isotherms and kinetic models were used to verify the adsorption performance. The results indicated high removal efficiencies (99-100%) for all the studied heavy metals at pH 7 at constant contact time of 2 h. The data obtained from adsorption isotherms of metal ions at different time fitted well to linear form of the Langmuir sorption equation, and pseudo-second-order kinetic model. Application of the resulted conditions on well water demonstrated that the modified waste glass adsorbent successfully adsorbed heavy metals (Cd, Cu, Fe, Pb and Zn) from well water.

• 콘크리트학회논문집
• /
• 제15권1호
• /
• pp.87-94
• /
• 2003

현재 건설생산현장에서 이루어지고 있는 거푸집 제거 시기 결정, 설계기준강도 확보 등의 강도관리는 그 시점을 예측할 수 없다는 단점이 있기 때문에 건설생산현장에서의 공정계획 및 강도관리에서 한계가 있을 수밖에 없다. 이에 따라 콘크리트의 강도를 예측할 수 있으면 보다 합리적인 강도관리 및 공정계획이 가능하게 된다. 본 연구는 적산온도 방법에 의해 새로 제안된 강도예측모델의 적용가능성을 검증하기 위해 기존 강도예측모델 중 Logistic 모델과 비교 평가하였으며, 모의부재에서 채취한 코어공시체와 현장양생공시체의 압축강도를 비교 평가한 후 새로운 강도예측모델에 의해 강도를 예측하여 거푸집 제거시기를 결정하는 것에 대한 합리성을 검증하고자 하였다. 실험결과 Freiesleben의 활성화에너지를 이용한 등가재령함수에 있어서 콘크리트의 강도는 양생온도에 관계없이 유사한 강도수준을 나타내고 있으나 강도-적산온도의 상관성을 높이기 위해서는 등가재령 계산시 이용되는 활성화에너지에 대한 검토가 필요할 것으로 사료된다. 새로 제안된 모델의 경우 Logistic 모델에 비해 초기재령에 있어서 강도예측이 보다 정확한 것으로 나타났으며, SSE는 작고 결정계수는 높게 나타나고 있어 이를 이용한 강도예측이 보다 합리적일 것으로 판단된다. 본 연구의 범위 내에서 양생온도 10~15$^{\circ}C$의 경우 강도관리 측면에서 새로운 강도예측모델 사용시 압축강도 50kgf/${cm}^2$ 발현시점이 기존에 제안된 기간과 비교하여 빠르게 나타나고 있어 이를 건설생산현장에서 적용할 경우 거푸집제거시기의 단축에 의한 공기단축이 가능할 것으로 사료된다.

• 한국정밀공학회지
• /
• 제18권3호
• /
• pp.61-67
• /
• 2001

The finishing process for die is an important process because it has influence on final quality of products. Recently s study on development of 5-axis die automated finishing machine has been progressed. But die must be moved from the cutting machine to the die automated finishing machine. So manufacturing cost and time increase and machining error occurs by transfer. So, in this study, a 3-axis machining center was applied to die finishing. Because cutting tool can be changed to finishing tool by ATC, both of cutting and finishing process are possible on the machine. However, this application results in the decrease of finishing for the improvement of form accuracy. So this study focused on the generation of finishing tool path suitable to 3-axis die finishing for the improvement of form accuracy. The form accuracy evaluation is performed by the measurement of removal depth using a stylus profilometer. From the result, it is confirmed that form accuracy was improved less than 2$\mu$m of removal depth error.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2003년도 학술.기술논문 발표회
• /
• pp.23-26
• /
• 2003

This study is intended to investigate the properties of early strength development by application of TEA to the field. According to the results, when TEA is added, fluidity is almost same to base concrete, and increases upto aimed slump after field flowing. Setting time does not differ in the case of base and TEA, but retarded after flowing. The time when compressive strength gains 5 MPa, which side form can be removed, is 23 hours, and so the removal time is shortened by I hours in comparison with plain concrete. But compressive strength is almost same to that of plain concrete at 28 days. The rebound value of P type schmidt hammer show similar tendency to compressive strength, and the rebound value of structure is higher than that of standard curing specimen due to heat capacity effect and drying by the air outside. Therefore, it is thought that if the rebound value of P type schmidt hammer is controled. by about 26 in consideration of open air environment, it is very effective to determine the removal time of side forms.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2003년도 학술.기술논문발표회
• /
• pp.23.1-26
• /
• 2003

This study is intended to investigate the properties of early strength development by application of TEA to the field. According to the results, when TEA is added, fluidity is almost same to base concrete, and increases upto aimed slump after field flowing. Setting time does not differ in the case of base and TEA, but is retarded after flowing. The time when compressive strength gains 5 MPa, which side form can be removed, is 23 hours, and so the removal time is shortened by 1hours in comparison with plain concrete. But compressive strength is almost same to that of plain concrete at 28 days. The rebound value of P type schmidt hammer show similar tendency to compressive strength, and the rebound value of structure is higher than that of standard curing specimen due to heat capacity effect and drying by the air outside. Therefore, it is thought that if the rebound value of P type schmidt hammer is controled. by about 26 in consideration of open air environment, it is very effective to determine the removal time of side forms.

• Environmental Engineering Research
• /
• 제20권2호
• /
• pp.199-204
• /
• 2015

In this study, a novel phosphorus removal filter made of brass scrubber with higher porosity of over 96% was fabricated and evaluated. The brass scrubber was surface-modified to form copper hydroxide on the surface of the brass, which could be a phosphate removal filter for advanced wastewater treatment because the phosphates could be removed by the ion exchange with hydroxyl ions of copper hydroxide. The evaluation of phosphate removal was performed under the conditions of the batch type in wastewater and continuous type through filters. Filter recycling was also evaluated with retreatment of the surface modification process. The phosphate was rapidly removed within a very shorter contact time by the surface-modified brass scrubber filter, and the phosphate mass of 1.57 mg was removed per gram of the filter. The possibility of this surface-modified brass scrubber filter for phosphorus removal was shown without undesirable sludge production of existing chemical phosphorus removal techniques, and we feel that it would be very meaningful as a new wastewater treatment.

• KSBB Journal
• /
• 제20권5호
• /
• pp.341-344
• /
• 2005

섬유상 담체를 이용한 2단 소형 바이오필터를 이용한 악취가스 처리공정의 운전조건을 확립하기 위하여 BTX를 처리대상 물질로 바이오필터를 연속적으로 운전하여 섬유상 바이오필터 담체에 악취가스 처리용 미생물을 부착시킨 결과 우수한 부착된 생물막을 형성하여 높은 처리효율 $93\%$를 얻을 수 있었다. 또한, 악취 유입 농도 400 ppm 미만에서 체류시간 10 sec일 때 1단 반응기에서 $76\%$ 정도 제거율을 보이다가 2단 반응기에서 약 $93\%$의 제거율을 나타내었다. 그러나 체류시간이 15 sec 이상인 경우에는 제거효율이 $97\%$ 이상 유지되었다.