본 논문에서는 기어 소음 및 진동 저감을 위해 베이지안 최적화 기법을 이용하여 기어 전달오차를 최소화하는 최적설계 기법을 제 안하였다. 이는 기어의 형상에 큰 영향을 받는다. 기존의 ISO 6336과 AGMA 2101 기반의 전달오차 해석은 기어 형상과 물림률을 충 분히 반영하지 못하며, 유한요소해석은 정확도가 높으나 세밀한 요소망과 접촉 비선형 해석으로 인해 계산 비용이 매우 크다는 한계 가 있다. 본 연구에서는 물림률을 고려한 유한요소 간소화모델을 구성하여 비교적 적은 샘플로 정확한 확률 모델을 만들 수 있는 가우 시안 프로세스 기반 대리모델과, 여기서 얻어진 기대치 개선값을 바탕으로 새로운 최적점을 탐색하였다. 제안된 기법의 결과를 유전 자 알고리즘 기법과 비교하여 유효성을 검증하였다.

Marine debris has become a serious global environmental and economic concern with abandoned fishing gear identified as one of the primary drivers threatening marine ecosystems. In South Korea, a substantial amount of fishing gear continues to enter the ocean annually; however, the current land-based disposal system faces inherent limitations including high transportation costs and low recycling efficiency. To address these challenges, this study evaluated the feasibility of repurposing decommissioned fishing vessels as marine pre-treatment platforms to collect and process abandoned fishing gear at sea. Results indicate that marine pre-treatment vessels can reduce the volume of discarded fishing gear, thereby cutting transport and disposal costs. Refitting decommissioned vessels is more cost-effective than new construction and increases their recycling value. This research provides a policy and technical foundation to improve the marine debris management system by assessing the economic and environmental benefits of deploying marine pre-treatment vessels.

This study proposes a hierarchical optimization methodology for two-stage gear systems using Monte Carlo enhanced Genetic Algorithm (MCeGA). The approach integrates reliability-based design with genetic algorithms to overcome the inherent randomness of traditional GA methods. A two-phase optimization framework was developed. The system incorporates Unity engine for real-time 3D visualization and interactive design evaluation. Key design constraints including contact ratio, gear ratio, and meshing conditions were parameterized according to ISO 6336 and AGMA 2101 standards. The proposed framework enables application-specific optimal gear configurations through Pareto analysis and weighted optimization, providing engineers with practical design solutions for various industrial requirements.

This study aimed to improve safety and reduce labor intensity in offshore crab pot fisheries through the development of six types of automated fishing gear: a bait cutter, bait crusher, mainline arranging device, automatic pot hauler, cold water tank system, and crab pot unloading device. Sea trials demonstrated that both the bait cutter and bait crusher effectively reduced overall operation time. The mainline arranging device lowered the risk of injury compared to the conventional manual handling. The automatic pot hauler enabled the automated separation of crab pots, significantly decreasing the physical workload. The cold water tank system facilitated the efficient sorting of live crabs while enhancing onboard safety. Additionally, the crab pot unloading device reduced physical strain on workers and minimized catch damage. A satisfaction survey revealed high levels of approval among fishers, particularly regarding labor reduction and improved safety. Economic analysis indicated that vessels equipped with the automated gear experienced reduced overall operating costs. These findings suggest that the developed technologies will contribute to the long-term sustainability and modernization of offshore crab pot fisheries.

This study examined the operational characteristics and fishing performance of an offshore pot fishery targeting swimming crabs (Portunus trituberculatus) to identify key issues and proposed strategies for improving efficiency and fisher safety. Analysis was based on approximately one year of fishing logbook data recorded by a pot fishing vessel. The total annual catch amounted to 30,084 kg, with the highest catch per unit effort of 0.07 kg per trap observed in autumn at depths of 20–25 m. No crabs were caught below 15℃ while the peak catch occurred at around 25℃. Catches were geographically concentrated in the mid-northern West Sea, especially near Taean and Boryeong. Economically important bycatch species, including sand crabs, octopus, and turban snails, exhibited distinct spatial distributions. An average of 1,996 traps were deployed per operation with a low loss rate of 1.6 traps. Based on field-level observations, this study proposed the development of automated or semi-automated equipment, such as bait cutters, automatic mainline arranging devices, pot-hauling and separation systems, chilled water tanks for sorting, and automated unloading systems. These technologies are expected to reduce labor demands, improve safety, and enhance the overall operational efficiency of the pot fishery.

This study aimed to enhance the operational efficiency and safety of offshore eel trap fisheries by developing six types of automated fishing equipment: a bait crusher, bait cutter, main line arranging device, trap cleaning device, eel sorting device, and fish pump system. Sea trials demonstrated that the bait crusher and bait cutter significantly reduced manual labor and processing time while maintaining bait quality. The main line arranging device improved productivity and safety by automating the sorting of looped cords. The trap cleaning device effectively removed fouling organisms using high-pressure water and rotating brushes. The eel sorting device enabled automatic size-based selection, improving resource management and operational efficiency. The fish pump system transferred eels rapidly with minimal physical damage, reducing unloading time by over 80% and decreasing labor requirements. A satisfaction survey of fishery participants confirmed that all developed devices were highly effective in reducing workload, enhancing safety, and improving operational performance. The automated equipment developed in this study is expected to contribute to the sustainable management of offshore eel trap fisheries and to offer potential applicability to other coastal and offshore fisheries.

In four-wheel-drive vehicle, improving traction with the road surface enhances the vehicle's ability to respond to various driving conditions, increasing its overall versatility. Consequently, various studies have been conducted on four-wheel-drive vehicles that support torque distribution through electronic control. The driving unit that operates the transfer case assists in smooth torque distribution by providing high torque. Therefore, this study developed a reduction mechanism by vertically arranging a planetary gear set in the driving unit to increase the reduction ratio. To achieve this, a common ring gear with 52 teeth was used, and the design included a first-stage planetary gear with a sun gear having 18 teeth, a planet gear with 17 teeth, a second-stage sun gear with 12 teeth, and a planet gear with 20 teeth. The corresponding tooth profiles and structures were also designed. Based on this, a transfer case drive reduction module was developed, which improved torque performance: the first-stage planetary gear system provides 4.23 kgf·m of torque, and the second-stage planetary gear system achieves a final torque of 5.98 kgf·m

Various vibrations occur while a ship is in operation. In the propulsion shaft systems of medium and small-sized vessels, it is common to install elastic couplings to prevent fluctuating torque from being directly transmitted to the reduction gear system and to avoid damage caused by torsional vibrations. However, the majority of elastic couplings are currently imported. The engine speed was gradually increased during the coupling test, while the vibrations were measured. At the point of maximum output, the engine speed was maintained at a constant level to observe the structural vibrations of the engine. This study aims to localize the production of elastic couplings by addressing the issue from the perspectives of torsional and structural vibrations to verify their operational performance.

This study sought various ways to prevent the occurrence of waste fishing gear and promote the recovery. It is expected that the problem of waste fishing gear can be effectively solved through measures such as strengthening education and publicity, technical measures, establishment of recovery infrastructure, and provision of incentives. In particular, introduction of the waste fishing gear recovery promotion point system gives fishermen practical motivation. It can be an important means of inducing leisure and sustainable fishing activities. In addition, by inducing the participation of private companies, it is expected to promote the recovery and recycling of waste fishing ports and contribute to the protection of the marine environment and fisheries resources. The government or local government should actively review the measures suggested in this study and prepare related laws and policies. In addition, it is necessary to establish a system to induce the participation of various stakeholders and support sustainable fishing activities through public-private cooperation. Through this, we will be able to achieve carbon neutrality goals in the fishing sector in response to climate change. This study suggests an early stage plan, and in future research, it is necessary to evaluate and find and improve practical effects through pilot projects. Moreover, it is necessary to study the management of closed fishing gear and carbon neutrality practice measures at the global level by seeking international cooperation measures. Consequently, more effective and sustainable marine environment and fishery resource protection measures can be prepared.

In response to the global interest and efforts towards reducing plastic use and promoting resource recycling, there is a growing need to establish methods for recycling discarded fishing gear. In Korea, various technologies are being developed to recycle discarded fishing gear, but significant technical and policy challenges still remain. In particular, biodegradable gill nets require a pre-treatment process to separate biodegradable materials from other substances and to remove salt before recycling. Therefore, this study aims to develop a pre-treatment device for recycling biodegradable gill nets and to evaluate the feasibility of recycling them.

The parking gear is very important part of automotive because it is related to safety. Nonlinear gear groove of parking gear is used to enlarge the contact area between parking gear and pawl. The die has been widely applied for many industrial parts such as machine, automotive and so on. The purpose of this study is to investigate the stability of upper and lower dies by using numerical analysis. As the results, the lower die was weaker than the upper die in this study, and the lower die showed that it should be used within 500ton in terms of safety factor. Further the most weak point of lower die was low location in front of gear. Its minimum value of safety factor was 0.578 in case of 4000ton of press load, therefore, this weak point was needed to be reinforced.

As discarded fishing gear settles or floats on the seabed, it destroys the spawning and habitat of fisheries resources that causes various safety accidents and adverse effects on the environment, such as generating microplastics and causing ship accidents. In order to solve this problem, this study is intended to present an implementation plan for establishing a fishing gear deposit system in order to use it as basic data for establishing policies for fishing gear management in Korea. In order to successfully implement the fishing gear deposit system, the deposit system must be established in the form of fishing gear completed at the production stage. It was found that the marking of the object should be easy, and that determining an appropriate deposit amount to motivate the return of waste fishing gear and establishing a convenient return procedure for returned waste fishing gear were important factors. In addition, transparent management of unreturned deposits and mandatory use of fishing gear subject to the deposit system for fishermen will be necessary. The role of a specialized organization to manage and operate all of these procedures is also very important. It is necessary to establish a new mandatory provision in the Fisheries Act to require fishermen who directly use fishing gear to use fishing gear with a deposit refund mark, and to ensure the implementation of the deposit system by linking it with the evaluation items of government policy projects. Since the main purpose of the deposit system is to collect discarded fishing gear, a support plan will be necessary in accordance with the purchase project for fishing waste salvaged by local governments in 2020.

In the actual sea, the additional resistance due to external force such as wind, current and wave is accompanied, and the required power is added in response to these resistance. Especially when the ship is sailing at low speed, the effects of wind and current have a great impact on the safe control of the ship. Likewise, it is thought that the effects of wind and current have a great impact on the trawl ship control since the towing speed of a bottom trawl ship is a low speed of 3 to 4 knots. If the reduce of ship speed and the increase of engine power due to the influence of wind and current can be identified, the safe towing power can be calculated based on a given engine output. Thus, the appropriate size of a fishing gear can be determined. In this study, a total of 20 trawl operations were conducted for seasonal maritime research in the same research area according to the operation mode of propeller. Based on navigation data, trawl fishing data, and engine performance data acquired during the towing fishing gear, and data of ship speed, hull resistance, fishing gear resistance, wind force and current force according to an incidence angle were estimated. The overall power for these loads was calculated and compared with the measured engine power, and the effects of wind force and current force on the engine power were investigated.