## 1 Introduction  
Fire accidents in ships and offshore plants cause massive system damage and human injury due to flame diffusion. In order to reduce the damage caused by the fire accident, International Maritime Organization (IMO) has strengthened fire protection regulations for some major compartments of ships and offshore plants. Fire resistance design specified in the Safety of Life at Sea (SOLAS) should be applied to A60 class fire protection apparatus to prevent the spread of flames for 60 min in the compartment where the apparatus is installed [1]. A60 class bulkhead penetration piece (A60 BPP) is a fire protection apparatus used in the case that a control or communication cable is installed through the vertical structure of a compartment with a high risk of a fire accident. The IMO requires that the fire-resistance performance of the A60 BPP should be verified in accordance with the Fire Test Procedure (FTP) regulation [2]. The A60 BPP design should satisfy the FTP regulation according to which the temperature measured on the outer parts of A60 BPP should be maintained under 180 \({}^{\circ}\)C during the fire test wherein the specimen is mounted vertically in the furnace and heated gradually to the temperature of 940 \({}^{\circ}\)C for 60 min. A few research studies on fire-resistance performance evaluation for ships or offshore plants have been carried out. [PERSON] et al. [3] conducted fire tests on various fire protection coating samples to investigate the relationship between the thickness of the intumescent fire protection coating and the time exposed to heat. [PERSON] et al. [4] carried out a fire test by adjusting fire-resistance conditions on fire damper blades and coaming to satisfy the fire protection performance of the H-120 class fire damper. [PERSON] et al. [5] conducted a fire test in consideration of various composite material manufacturing conditions to evaluate the fire protection performance of the material used for fiberglass reinforced plastic ship. [PERSON] and [PERSON] [6] performed a fire test by applying specimen specifications, temperature conditions and heating time settings, and temperature measurement and analysis methods specified by the FTP to verify the A60 fire protection performance. [PERSON] and [PERSON] [7] verified the design of A0 class bulkhead penetrating pipe applied to the vertical structure of the ship using heat transfer analysis and fire test. As such, it is difficult to find a case of design optimization research for fire-resistance apparatus such as the A60 BPP or fire protection devices for ships or offshore plants. This study aims to propose an optimization method of fire-resistance design for A60 BPP using various meta-models and genetic algorithms. In this study, meta-model-based approximate optimization using a multi-island genetic algorithm (MIGA) was carried out for the weight minimization design of an A60 BPP with the characteristics of discrete design variables. Genetic algorithm (GA) is one of the global search methods based on evolutionary computation adopting the principle of survival of the fittest in organisms. In contrast with conventional sensitivity-based optimal design methods that require the differentiation of function, the GA can be applied to optimization with discrete variables because it uses a binary coding method and is able to transfer the design solution with the function result itself [8]. Even though there is no restriction on the type of the meta-model that can be applied to the GA-based approximate optimization, the difference in the approximate optimization result by the meta-model may occur depending on the characteristics of the design space. Therefore, it is required to select the meta-model most suitable for the GA-based approximate optimization by applying various meta-models to a given design problem. Although the GA is capable of global optimization search, it is poor in maintaining the diversity of the population and easily accessing local solutions.