In this study, we performed algorithms to predict algae of Chlorophyll-a (Chl-a). Water quality and quantity data of the middle Nakdong River area were used. At first, the correlation analysis between Chl-a and water quality and quantity data was studied. We extracted ten factors of high importance for water quality and quantity data about the two weirs. Algorithms predicted how ten factors affected Chl-a occurrence. We performed algorithms about decision tree, random forest, elastic net, gradient boosting with Python. The root mean square error (RMSE) value was used to evaluate excellent algorithms. The gradient boosting showed 10.55 of RMSE value for the Gangjeonggoryeong (GG) site and 11.43 of RMSE value for the Dalsung (DS) site. The gradient boosting algorithm showed excellent results for GG and DS sites. Prediction value for the four algorithms was also evaluated through the Receiver operating characteristic (ROC) curve and Area under curve (AUC). As a result of the evaluation, the AUC value was 0.877 at GG site and the AUC value was 0.951 at DS site. So the algorithm‘s ability to interpret seemed to be excellent.

ABSTRACT
1. 서 론
2. 연구방법
    2.1 조사지점 및 시기
    2.2 자료수집 및 기계학습
    2.3 분석방법
3. 결과 및 고찰
    3.1. 수질항목별 상관분석 결과
    3.2. RMSE를 통한 알고리즘 성능평가
    3.2 Receiver operating characteristic (ROC) 커브를 통한 예측값 정확성 평가
4. 결 론
References

• 이상민(부경대학교 환경공학과) | Sang-Min Lee (Department of Environmental Engineering, Pukyong National University)
• 박경덕(부경대학교 마린융합디자인공학과) | Kyeong-Deok Park (Department of Marine Design Convergence engineering, Pukyong National University)
• 김일규(부경대학교 환경공학과) | Il-Kyu Kim (Department of Environmental Engineering, Pukyong National University) Corresponding author