The Korean Journal of Applied Statistics (응용통계연구)

The Korean Statistical Society (한국통계학회)
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Fraud detection support vector machines with a functional predictor: application to defective wafer detection problem

불량 웨이퍼 탐지를 위한 함수형 부정 탐지 지지 벡터기계

  • Received : 2022.07.21
  • Accepted : 2022.08.14
  • Published : 2022.10.31
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Abstract

We call "fruad" the cases that are not frequently occurring but cause significant losses. Fraud detection is commonly encountered in various applications, including wafer production in the semiconductor industry. It is not trivial to directly extend the standard binary classification methods to the fraud detection context because the misclassification cost is much higher than the normal class. In this article, we propose the functional fraud detection support vector machine (F2DSVM) that extends the fraud detection support vector machine (FDSVM) to handle functional covariates. The proposed method seeks a classifier for a function predictor that achieves optimal performance while achieving the desired sensitivity level. F2DSVM, like the conventional SVM, has piece-wise linear solution paths, allowing us to develop an efficient algorithm to recover entire solution paths, resulting in significantly improved computational efficiency. Finally, we apply the proposed F2DSVM to the defective wafer detection problem and assess its potential applicability.

빈번하지는 않지만 한번 발생하면 상대적으로 큰 손실을 가져오는 사례를 통칭하여 부정 사례(Fraud)라고 부르며, 부정 탐지의 문제는 많은 분야에서 활용된다. 부정 사례는 정상 사례에 비해 상대적으로 관측치가 매우 적고 오분류의 비용이 월등히 크기 때문에 일반적인 이항분류 기법을 바로 적용할 수 없다. 이러한 경우에 활용할 수 있는 방법이 부정 탐지 지지 벡터기계(FDSVM)이다. 본 논문에서는 공변량이 함수형일 때 활용 가능한 함수형 부정 탐지 지지 벡터기계(F2DSVM)를 제안하였다. 제안된 방법을 사용하면 함수형 공변량을 가진 데이터에서 사용자가 목표하는 부정 탐지의 성능을 만족시키는 제약하에서 최적의 예측력을 가지는 분류기를 학습시킬 수 있다. 뿐만아니라, 통상적인 SVM과 마찬가지로, F2DSVM도 자취해의 조각별 선형성을 보일 수 있으며 이를 바탕으로 효율적인 자취해 알고리즘을 활용할 수 있고 분류기의 학습 시간을 크게 단축시킬 수 있다. 마지막으로, 반도체 웨이퍼 불량 탐지 문제에 제안된 F2DSVM을 적용해 보았고, 그 활용 가능성을 확인하였다.

Keywords

Acknowledgement

이 논문은 정부 (미래창조과학부)의 재원으로 한국연구재단의 지원을 받아 수행된 연구임(NRF-2018R1D1A1B07043034).

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