Maritime autonomous surface ships (MASS) are proposed as a future technology of the maritime industry. One of the key technologies for the development of MASS is condition-based maintenance (CBM) based on prognostics and health management (PHM). The CBM technology can be used for early detection of abnormalities based on the database and for a prediction of the fault occurring in the future. However, this technology has a problem that requires a high-quality database that reproduces the operation state of the actual ships and quantitatively and systematically indicates the characteristics for the various fault state of the device. To solve this problem, this paper presents a study on the development method of the fault database based on the reliability. Firstly, the reliability analysis of the target device was performed to select five types of the core fault modes. After that, a fault simulation scenario that defined the fault simulation test methodology was drawn. A land-based testbed was built for the fault simulation test. The fault simulation database was developed with a total of 109 sets through the fault simulation test. Additionally, a fault classification algorithm based on deep learning is proposed. The classification performance was evaluated with a confusion matrix. The developed database will be expected to serve as the basis for the development CBM technology of MASS in the future.

Tae-whan Kim 1 , Tae-hyun Lee 2 , Tae-beom Seo 3 , JI-hoon Cho 4 , Ki-hyuk Lee 5 , Jong-baek Lee 1* OBJECTIVES The purpose of this study was to examine the differences of wearing shoes and barefoot on lower limb muscle functions in martial arts athletes of university. METHODS Fourteen martial arts athletes participated in this study. Lower limb muscle functions (maximum strength, power, and electromyography) and balance were measured when wearing shoes (WS) and barefoot (BF). Measured data were analyzed using IBM SPSS Statistics ver. 23.0 (IBM Co., Armonk, NY, USA). Paired t-test was used for comparison between WS and BF. RESULTS Maximum muscle strength (absolute and relative squat 1RM) and static balance (Standing on one leg with eyes close) were significantly higher in BF compared to WS. Although maximum muscle power and dynamic balance were higher in BF compared to WS, were non-significant. Muscle activities of rectus femoris and vastus lateralis were higher during WS than BF. CONCLUSIONS The results of this study suggest that Application of barefoot training seems to be effective on expression of lower limb maximum muscle strength and static balance in martial arts athletes of university.