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As industrial safety increases, various industrial accident prevention technologies using smart factory technology are being studied. However, small and medium enterprises (SMEs), which account for the majority of industrial accidents, are having difficulties in preventing industrial accidents by applying these smart factory technologies due to practical problems. In this study, customized monitoring and warning systems for each type of industrial accident were developed and applied to the actual field. Through this, we demonstrated industrial accident prevention technology through appropriate smart factory technology used by SMEs. A customized monitoring system using vision, current, temperature, and gas sensors was established for the four major disaster types: worker body access, short circuit and overcurrent, fire and burns due to high temperature, and emission of hazardous gas. In addition, a notification method suitable for each work environment was applied so that the monitored risk factors could be recognized quickly, and real-time data transmission and display enabled workers and managers to understand the disaster risk effectively. Through the application and demonstration of these appropriate smart factory technologies, the spread of these industrial safety technologies is to be discussed.

Demands for micro-machining on glass have been increasing in various industries due to the unique properties of glass, such as transparency or biocompatibility. However, micro-channel fabrication on glass with high precision has been challenging due to its brittle characteristics. This research presents the CO2 laser-assisted micro-milling process and investigates the machining characteristics experimentally. Micro-channels without cracks were fabricated using micro-end mill and CO2 laser irradiation as an assisting heat source. Compared to the process without laser heating in the same matching conditions, the average surface roughness was reduced by 96%, and cutting force was reduced by 28% and 66% for the feed and thrust direction, respectively. Continuous and sheared chips were observed with laser heating, indicating the process is in ductile-regime machining. Through the investigation of machining parameters, it was found that micro-channels with low average surface roughness can be achieved at the proper laser power when the workpiece is heated up to the strain point at tool position, at low feed rate, and at high axial depth of cut, as long as the tool withstands the cutting forces. Consequently, it can be concluded that it is possible to increase the material removal rate in micro-milling of borosilicate glass with high quality by using the CO2 laser, which was found to be an effective and suitable heating method.

In the machining of silicon compound ceramic materials via laser beam, processing in water has been found to enhance machining quality, while processing in air has limitations such as the generation of a recast layer, heat affected zone, and thermal crack. However, few studies have investigated the effects of water on the ablation rate of silicon compound ceramics. In this research, the ablation behavior and machining principles of the laser beam machining of silicon compound ceramics in water are investigated. The research concluded that the increase in temperature induced by laser irradiation promotes hydrothermal reaction between the silicon compound ceramics and water. The hydrothermal reaction assists in the removal of the oxide layer at the machined area and enhances the efficiency of the process in water. The effects of water on ablation are confirmed for various machining parameters such as the flow rate of sprayed water on the workpiece and laser conditions. Finally, the various micro-structures were fabricated on the silicon compound ceramics to evaluate the processability.

Glass is a well-known non-conductive material that has many useful properties, and considerable research has been conducted into making circuits on glass. Many deposition techniques have been studied, and laser-induced chemical liquid phase deposition (LCLD) is a well-known and cost-effective method for rapid prototyping of copper deposition on glass. However, the deposition results from the LCLD method on the surface of glass, which shows an issue in its detachment from the substrates because of the relatively low adhesion between deposited copper and the nontreated glass surface. This problem undermines the usability of deposited glass in industrial applications. In this study, the laser-induced backside wet etching (LIBWE) method was performed as a preceding process to fabricate microchannels, which were filled with copper by LCLD. Additional durable copper wire was produced as a result of the enhanced adhesion between the glass and the deposited copper. The adhesion was enhanced by a rough surface and metal layer, which are characteristics of LIBWE machining. Furthermore, the proposed method is expected to broaden the use of deposited glass in industrial applications, such as in stacked or covered multilayer structures with built-in copper wires, because the inserted copper can be physically protected by the microstructures.

Laser induced backside wet etching (LIBWE), a simple-setup process capable of processing transparent materials, has been studied to overcome difficulties in glass micromachining. However, LIBWE still show practical difficulty in machining various glass applications due to the crack occurrence and unprecise final geometry. This study proposes the error-compensating scan path generation method for the precise fabrication of glass microstructures without additional devices. In conventional scan paths, the overlap of scan path’s initial and final points, constant scan path patterns and uneven distributions of laser irradiation were the leading causes of geometric errors. The scan path generation method was developed to minimize or eliminate the causes of geometric errors in conventional scan path methods. Machined results, with error-compensating scan path, showed the removal of significant error from conventional paths with proper material removal rates. The effects of scan path generation parameters on the machining characteristics were also investigated. By adjusting the scan duty ratio and laser irradiation distribution of the entire scan path, micropockets with an average surface roughness of 0.26 μm could be processed at a material removal rate of 29,700 μm3/s. Based on machining characteristics of the error-compensating scan path, various glass microstructures were fabricated and the feasibility of the proposed method was verified.

Laser-induced backside wet etching (LIBWE) is one of the most promising manufacturing processes for fabricating high aspect ratio microfeatures of glass. However, cracks inside the glass during the LIBWE process due to high thermal stress limits the manufacturable shape. In this study, we propose a new technique to prevent the crack generation in the near-infrared (NIR) LIBWE process by adding phosphoric acid to the absorbent. It was possible to increase the maximum fabricable depth by approximately five times compared to the absorbent without phosphoric acid. The nature of the crack suppression mechanism in the absorbent with added phosphoric acid was investigated by in situ observation of the process and chemical analysis. To investigate the effects of phosphoric acid on LIBWE with added phosphoric acid, the influences of phosphoric acid concentration on maximum fabricable depth, fabrication speed and sidewall roughness were studied. Based on the investigated principle and process characteristics, we found that high aspect ratio microchannels of different shapes could be produced.

Bipolar plates of a proton exchange membrane fuel cell (PEMFC) play an important role in removing liquid phase water as a by-product in order to facilitate the reaction between fuel and oxygen. A great amount of effort has been made to improve the performance of a fuel cell such as maximum current density or maximum power, by improving water removability of a bipolar plate. Most of the studies, however, are conducted numerically because of the complexity of analysing gas and liquid and the poor manufacturability of graphite bipolar plates. In this proceeding, we demonstrate that the performance of a PEMFC with metal bipolar plates can be enhanced by reducing the dimension of the channel. Bipolar plates were machined with stainless steel (type 316L) to have three different channel size (1000 μm, 500 μm and 300 μm) and the performance of each assembled cells were tested. As a result, the maximum power density and the maximum current density increased by 25%.