Remediation of soil contaminated with arsenic and heavy metals using soil washing and stabilization technologies

In the present thesis, a study has been performed of remediating mine tailings around abandoned mine contaminated with high concentrations of arsenic and heavy metals using techniques of soil washing and stabilization sequentially. The soil washing was applied to removing arsenic, whereas the stabilization was to minimizing the mobility of the heavy metals remained in soils after the washing. The optimal conditions in the type and concentration of washing reagent, mixing ratio of soil and washing reagent, and washing time were derived through the removal experiment of arsenic using the soil-washing technique. Results showed that the most effective washing reagents to remove arsenic from soils were phosphoric acid (65% efficiency) and oxalicacid (72%), while the oxalic acid (89%) was the most effective for removal of the heavy metals containing Cu. The economical and efficient washing concentration was 0.25M and the suitable washing time was 90 minutes. The optimal mixing ratio of soil and washing reagent was 1:20 (mass/vol) in viewpoint of minimization of wastewater produced after the washing, in addition to the washing effectiveness. Although the mixture of washing reagents did not help in removal of arsenic, it lead to much elevated synergy effect in removing Cu and Zn, compared to the single reagent. Over 80% of heavy metals were removed from the wastewater through the natural sedimentation for 30 days with no additive, whereas most of arsenic (over 70%) remained. The adjustment of pH at 9-10 in the wastewater enabled over 99% of arsenic to be sedimentated. By performing the stabilization, with 10wt% of calcium phosphate (CaHPO4) for 14 days, of heavy metals remained in soils after the washing, high treatment efficiencies were obtained asfollows: Pb (99.7%), Cd (87.1%), Cu (97.9%), Zn (99.4%). In the adsorption/desorption experiments of arsenic, a column of diameter 2.5cm and length 10cm was used and the arsenic concentration and flow rate were respectively 0.39-0.42mmol/L as As and 1.0-2.9mL/min. The experiments were performed in an oxidized condition for the case of As(V) and in a reduced condition for that of As(III). As(V) reached a quasi-equilibrium state when the solution passed through the column was over 900mL (9 hours) for the adsorption and 500mL (6 hours) for the desorption. On the other hand, As(III) reached a quasi-equilibrium state when the solution was over 390mL (3.5 hours) for the adsorption and 400mL (2.5 hours) for the desorption. In addition, the adsorption and desorption for As(V) proceeded more slowly than for As(III).Table of Contents i List of Figures iii List of Tables v Abstract vii 1. 서론 1 2. 이론적 고찰 4 2.1 토양의 특성 4 2.2 토양 내 중금속의 화학적 분포 11 2.3 중금속 오염토양의 처리기술 및 동향 14 2.4 토양세척기법 23 2.5 고형화/안정화기법 30 3. 실험재료 및 방법 34 3.1 실험재료 34 3.2 실험방법 36 3.2.1 토양의 특성 파악 36 3.2.2 토양세척실험 40 3.2.3 세척폐액 처리 실험 42 3.2.4 안정화실험 44 3.2.5 비소의 흡착·탈착실험 46 4. 결과 및 고찰 49 4.1 토양의 특성파악 49 4.1.1 시료의 물리화학적 특성 49 4.1.2 총 중금속 함량 52 4.1.3 중금속의 화학적 결합형태별 분포 52 4.2 토양세척기법을 이용한 비소 처리 55 4.2.1 최적 세척제 및 최적 농도 결정 실험 55 4.2.2 토양과 세척제의 혼합비 실험 59 4.2.3 최적 세척시간 결정 실험 61 4.2.4 혼합 세척제를 이용한 세척실험 63 4.3 세척폐액 처리 실험 64 4.4 안정화기법을 이용한 중금속 처리 67 4.5 비소 흡착·탈착 70 5. 결론 73 6. 참고문헌 7

멀티미디어서버에서 참조패턴을 고려한 버퍼관리정책 연구

학위논문(석사)--서울대학교 대학원 :전기·컴퓨터공학부,2002.Maste

Studies on the Kidney of the Korean Fetus I. Morphological Observation

Author observed morphologically and stastically the kidneys of 542 (0288. l? 254) Korean Fetuses and g otthe conclusion as follows: 1. Among the three kinds of the linear measurements: kidney length , kidney width and kidney thickness, the kidney length is the largest and kidney thickness is the smallest. The average means of three measurements increased gradually with the constant ratios as the fetal age proceeded. 2. Until the 5th month of fetal age kidney weight and kidney volume increased slowly. from the 5th month to 7th month rather rapidly and after that more rapidly. 3. The index of kidney length to body length increased very slowly as the fetal age proceeded , and this indicate that the kidney length developed a little more rapidly than the body length. 4. The indices of width to length and thickness to length of the kidney were almost constant through the entire fetal period. 5. The index of kidney weight to body weight increased very slowly as the fetal age proceeded , and this fact indicate that the kidney weight developed more rapidly than the body weight. 6. The boundaries of the kidney lobes were distinct during the 6th- 9th fetal months and rather indistinct during the 4th , 5th and 10th fetal months. The number of the lobes of each kidney was 16~ 17 in average. 7. There was no sexual difference. 8. The difference between the right and left sides was not so conspicuous but in general length of left kidney , width of right kidney , thickness of left kidney and weight of left kidney were greater than that of the opposite side. 9. Concering the racial differences, the size of the Korean fetus kidney is quite same as the Japanese but smaller than the European

이질적 워크로드를 지닌 멀티미디어 스토리지 시스템을 위한 데이터 관리 기법

학위논문(박사) --서울대학교 대학원 :전기. 컴퓨터공학부,2007.Docto

DC magnetron reactive sputtering 으로 증착한 ZrTiO₄박막의 유전특성 고찰

Thesis (master`s)--서울대학교 대학원 :금속공학과,2000.Maste

SURF 특징점을 이용한 유사 비디오 스트림 검색

학위논문 (석사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2012. 2. 심규석.최근 다양한 멀티미디어 기기와 통신 인프라의 발달로 인하여 많은 비디오 동영상들이 인터넷을 통하여 스트림 동영상으로 전송되고 있다. 이러한 영향으로 스트림 비디오 영상을 검색하는 동영상 검색엔진의 필요성이 크게 증가하였다. 기존의 비디오 이미지 처리에는 전체적 특징을 이용한 비디오 검색을 사용하여 동일한 동영상을 찾는 것은 가능하였지만, 유사한 동영상을 찾는 것은 불가능 하였다. 본 논문에서는 유사한 이미지들은 서로 비슷한 부분이 많이 존재한다는 점에 착안하여, 부분을 나타내는 지역 특징 점들을 이용하여 지역 특징 점들을 심볼로 나타내어 유사 이미지를 정의하였다. 또한 동영상 클립의 키 프레임 성질을 이용하여 중요 특징점을 추출 하였으며 이후 가중치 있는 최대 이분매치를 이용한 유사도를 계산하여 비슷한 동영상 검색을 할 수 있게 하였다Recently as a various multimedia and communication techniques, many video streams is sent by a internet. So a similar video search in video streams is on high demand. The existing video search that uses global feature can find the exact same video. But it cant search similar video. In this paper, similar video can be search by using local feature. And by using videos key frame, local feature can be reduced. And maximum weighted bipartite matching is applied to find the video similarity. The suggested method not only improves the quality of similar video search exploiting the local feature of frames but also saves the searching time using key frames property and LSHMaste

The Mediating Effect of Career Decision Making Self-Efficacy in the Relation between Narcissism and Career Decision Level in College Students

본 연구는 남녀 대학생 188명(남: 73명, 여: 115명)을 대상으로 외현적 자기애 및 내현적 자기애 성향과 진로 결정수준 간의 관계에서 진로결정자기효능감의 매개 효과를 검증하고자 하였다. 매개 효과 검증을 위해 중다회귀 방법을 이용하여 분석한 결과, 외현적 자기애와 진로결정수준과의 관계는 진로결정자기효능감에 의해 완전 매개 되었다. 그리고 외현적 자기애를 하위 요인으로 구분하여 살펴본 추가 분석에서는 리더십/자신감 요인에서 완전 매개 효과가 나타났다. 반면 내현적 자기애는 진로결정자기효능감을 부분 매개하여 진로결정수준에 영향을 미쳤 으며, 내현적 자기애를 하위 요인으로 구분한 추가 분석에서는 하위 요인 중 목표불안정에서 부분 매개 효과가 나타났다. 이 같은 결과를 바탕으로 진로 상담 시 적절한 개입방법과 차별적 처치의 중요성에 대하여 논의하였다. The current study examined the mediation effect of career decision making self-efficacy(CDMSE) in the relation between a persons overt/covert narcissism tendency and career decision level. 188 college students (73 males, 115 females) participated in the study. Using multiple regression analysis, the current study found that CDMSE fully mediated between overt narcissism and career decision level. Additional analysis were performed dividing the overt narcissism tendency into sub-categories. The results showed that CDMSE fully mediated between leadership/confidence and career decision level. On the other hand, covert narcissism partially mediated CDMSE, affecting the career decision level. In the additional analysis dividing covert narcissism into sub-categories, there was a partial mediation effect of CDMSE in the relationship between goal instability and career decision level. Based on the results, the current study further discussed the appropriate intervention methods and the importance of discriminative treatment