Enhanced Convolutional Neural Network for In Situ AUV Thruster Health Monitoring Using Acoustic Signals.

As the demand for ocean exploration increases, studies are being actively conducted on autonomous underwater vehicles (AUVs) that can efficiently perform various missions. To successfully perform long-term, wide-ranging missions, it is necessary to apply fault diagnosis technology to AUVs. In this study, a system that can monitor the health of in situ AUV thrusters using a convolutional neural network (CNN) was developed. As input data, an acoustic signal that comprehensively contains the mechanical and hydrodynamic information of the AUV thruster was adopted. The acoustic signal was pre-processed into two-dimensional data through continuous wavelet transform. The neural network was trained with three different pre-processing methods and the accuracy was compared. The decibel scale was more effective than the linear scale, and the normalized decibel scale was more effective than the decibel scale. Through tests on off-training conditions that deviate from the neural network learning condition, the developed system properly recognized the distribution characteristics of noise sources even when the operating speed and the thruster rotation speed changed, and correctly diagnosed the state of the thruster. These results showed that the acoustic signal-based CNN can be effectively used for monitoring the health of the AUV's thrusters.

A Case of Invasive Squamous Cell Carcinoma of the Vulva / 대한피부과학회지

Vulvar cancer is uncommon and represents about 4% of malignancies of the female genital tract. Squamous cell carcinomas account for about 90% of the cases. However few cases are reported in dermatologic literatures. Theses lesions are usually characterized by firm, hyperkeratotic papules, plaques or indurated erosions. Human papilloma virus(HPV)DNA has been reported in 20-60% of patients with invasive vulvar cancer. The HPV-positive group has been characterized by a younger mean age, more tobacco use, and simultaneous presence of vulvar intraepitherial neoplasia(VIN) and the invasive component. We report a case of invasive squamous cell carcinoma of the vulva associated with HPV type 16 positive according to polymerase chain reaction.