국내에는 현재 50,435척의 5톤 미만 어선이 존재하나, 국내외 법규상 이러한 선박에서 발생하는 선저폐수를 관리하기 위한 제 도적·기술적 장치가 마련되어 있지 않다. 이로 인해 무단으로 배출되는 선저폐수는 심각한 환경오염을 유발하고, 이에 따른 경제적 손실 도 발생한다. 이에 본 연구는 소형선박용 유수 분리 장치의 내부 유동 분포를 개선하기 위해 Filter case cover 형상을 개발하였다. 입구각 0°, 30°, 45°의 세 가지 형상을 대상으로 Computational Fluid Dynamics 해석을 수행하였으며, 45° 형상에서 균일한 속도 분포와 안정적 선회 유동이 형성되어 Filter 전체 면적을 효율적으로 활용하는 것을 확인하였다. 이후 상용 Filter 6종에 대해 단일 성능평가를 수행한 결과, 양 전하막 처리된 활성탄이 유성분 흡착에 효과적임을 확인하였다. 이를 기반으로 기계적 여과 필터와 활성탄 필터로 구성된 3단계 여과 시 스템을 제안하였으며, 30ppm 유수 혼합액을 이용한 실험에서 배출수의 유분 농도를 0ppm에 근접하게 낮추고, 장시간 운전 중에도 안정적 인 유량과 처리 특성을 유지하였다. 본 연구는 형상 및 필터 구성을 최적화하여 설계 효율이 향상된 소형선박용 유수 분리 시스템의 기초 기술을 제시하며, 국내 연안의 환경오염을 방지하고 지속 가능한 생태계를 조성하는데 기여할 수 있을 것으로 기대된다.

페어리드 체인 스토퍼(Fairlead Chain Stopper, FCS)는 10MW급 부유식 해상풍력 발전기에 설치하기 위해 새롭게 개발된 탈착형 계류 시스템이다. 본 연구에서는 다양한 메타모델과 입자군집최적화 알고리즘을 이용하여 FCS의 구조설계에 대한 최적설계안을 탐색하 였다. FCS의 구조설계는 선급규정 설계하중조건을 산정하여 유한요소해석을 통해 수치해석적으로 평가하였고, 수치해석모델을 최적설계 에 연계하여 적용하였다. 최적설계의 수렴 효율성을 향상시키기 위해 반응표면모델, 크리깅, 체비쇼프직교다항식, 그리고 신경망과 같은 다양한 메타모델이 사용되었다. 최적설계에서 제한조건은 설계하중조건 별 응력을 고려하였고, 주요 구조부품의 두께 치수를 이산설계변 수와 연속설계변수로 각각 적용하여 목적함수인 최소중량설계를 달성할 수 있는 최적해의 특성을 비교하였다. 최적설계 알고리즘은 이산 설계변수의 최적해 탐색이 가능한 입자군집최적화가 적용되었다. FCS의 구조설계에 대해 신경망 기반의 메타모델이 적용된 경우에 4.72% 이하의 오차율로 최적해의 결정이 가능한 것으로 확인되었다.

Spirodela polyrhiza (L.) has been known as greater duckweed or great duckmeat. It is native inhabited in Korea. It is considered as a rich source of primary metabolites including protein, carbohydrates, and fats. Thus, it is considered as an alternative food source for the future. In addition, it has a strong phytoremediation capacity to remove various environmental pollutants, especially inorganic elements and pesticides. With a variety of duckweed’s application, there is an urgent need to develop a cultivation method for a sustainable supply of S. polyrhiza. In this study, an indoor vertical farm has been introduced to optimize duckweed cultivation. Indoor cultivated S. polyrhiza showed about 2-fold higher fresh weight than outdoor cultivated duckweed. Contents of inorganic elements were also significantly reduced in indoor cultivated S. polyrhiza. Especially, lead (Pb), cadmium (Cd), and arsenic (As) were approximately 10-fold decreased in indoor cultivated duckweed. On the other hand, contents of proteins and fats were significantly increased in indoor cultivated S. polyrhiza, while carbohydrates were found more in outdoor cultivated S. polyrhiza. Increasing N content in a homemade nutrition solution also enhanced fresh and dried weights of S. polyrhiza by about 1.8-fold in comparison with other commercial nutrition solutions. Proliferation rate (%) was doubled every 24 hours in this indoor vertical farm, indicating the accomplishment of a sustainable supply for S. polyrhiza. Further studies need to be undertaken to cultivate other duckweeds such as Wolffia arrhiza and Lemna minor using the same indoor farming system.

The demand for automated diagnostic facilities has increased due to the rise in high-risk infectious diseases. However, small and medium-sized centers struggle to implement full automation because of limited resources. An integrated molecular diagnostics automation system addresses this issue by integrating small-scale automated facilities for each diagnostic process. Nonetheless, determining the optimal number of facilities and human resources remains challenging. This study proposes a methodology combining discrete event simulation and a genetic algorithm to optimize job-shop facility layout in the integrated molecular diagnostics automation system. A discrete event simulation model incorporates the number of facilities, processing times, and batch sizes for each step of the molecular diagnostics process. Genetic algorithm operations, such as tournament, crossover, and mutation, are applied to derive the optimal strategy for facility layout. The proposed methodology derives optimal facility layouts for various scenarios, minimizing costs while achieving the target production volume. This methodology can serve as a decision support tool when introducing job-shop production in the integrated molecular diagnostics automation system

This study analyzes the aerodynamic and structural characteristics of an H-Darrieus vertical-axis wind turbine (VAWT) under varying inlet velocities using transient analysis. The k-ε turbulence model and six-DOF were applied to simulate urban environments in the flow analysis, while the structural analysis considered blade momentum of inertia and RPM conditions. The numerical results showed that the drag and lift forces increased by 60% and 53% respectively from the nominal wind speed to the cut-off wind speed conditions. Structural analysis indicated that the maximum Von-Mises stress in the blade did not exceed the yield strength of 69 MPa of PC-ABS, ensuring structural stability. However, the connecting rod exceeded the yield strength of SPCC 270 MPa, suggesting potential failure due to repeated rotational loads. This study confirms that materials with a yield strength of more than 1,100 MPa required for connecting rods to ensure reliable operation at high wind speed. These findings provide important insights for the design of robust VAWTs suitable for extreme environments.

This study aims to optimize the SDC (Spinning Dust Collector) system in amphibious assault vehicle engines through numerical analysis of dust and moisture particle separation efficiency using CFD-DPM. Focusing on an axial cyclone structure, the research evaluates separation efficiency across various particle sizes and flow conditions. The results demonstrate that vortices generated by cyclone blades play a critical role in influencing particle trajectories and improving separation performance. Additionally, the study highlights the significant impact of engine flow conditions and housing design, emphasizing that their careful optimization enhances the system's efficiency in separating dust and water. These findings offer valuable insights into optimizing inlet and outlet flow paths and cyclone housing design, providing a solid foundation for advancing SDC system performance in high-efficiency engines.

ars using diesel have always had problems with reducing exhaust fumes, and have been studied steadily in this regard. There were studies on the remanufacturing effect of DOC catalyst deactivated by diesel vehicle smoke reduction device, analysis of vehicle fire accident cases caused by damage to diesel vehicle smoke reduction device, and related studies on the remanufacturing effect of diesel vehicle smoke reduction device DPF. This study also developed an optimized system for complete combustion of smoke generated by institutions using diesel engines in low-temperature exhaust gases. The main systems to be developed are high-performance heaters, burner structures that can maintain ignition in exhaust flows, and exhaust flow control units that reduce exhaust gas backflow effects caused by diesel engines.

Background: Despite considerable technological advancements, polyspermy remains a significant challenge in in vitro fertilization (IVF) procedures in pigs, disrupting normal embryonic development. Here, we aimed to determine whether optimal fertilization conditions reduce the polyspermy incidence in pigs. Methods: In vitro -matured oocytes were co-incubated with sperm according to a modified two-step culture system. Results: In the first experiment, oocytes were briefly co-incubated with sperm, washed in IVF medium, and then moved to fresh IVF medium for 5 or 6 h. Although the 6 h sperm-free cultured group had a higher penetration rate than the 5 h cultured group, the polyspermy rate significantly increased in the 6 h sperm-free cultured group. The gamete co-incubation period was either 20 or 40 min. The 40 min cultured group had a higher rate of blastocyst formation and number of total cells in blastocysts than the 20 min cultured group. In experiment 2, oocytes were inseminated with sperm separated by Pecroll treatment. Percoll treatment increased the rate of oocyte penetration and blastocyst formation compared to the control. In experiment 3, fertilized oocytes were cultured in 25 μL microdroplets (10 gametes/drop) or 500 μL (100 gametes/well) of culture medium in 4-well plates. The large volume of medium significantly reduced the number of dead oocytes and increased the rate of blastocyst formation compared to the small volume. Conclusions: Collectively, these results demonstrate that various fertilization conditions, including modified co-culture period, active sperm separation, and culture medium volume, enhance fertilization efficiency and subsequent embryonic development by decreasing polyspermy occurrence.

In this study, a model to optimize residual chlorine concentrations in a water supply system was developed using a multi-objective genetic algorithm. Moreover, to quantify the effects of optimized residual chlorine concentration management and to consider customer service requirements, this study developed indices to quantify the spatial and temporal distributions of residual chlorine concentration. Based on the results, the most economical operational method to manage booster chlorination was derived, which would supply water that satisfies the service level required by consumers, as well as the cost-effectiveness and operation requirements relevant to the service providers. A simulation model was then created based on an actual water supply system (i.e., the Multi-regional Water Supply W in Korea). Simulated optimizations were successful, evidencing that it is possible to meet the residual chlorine concentration demanded by consumers at a low cost.

Fast service access involves keeping track of the location of mobile users, while they are moving around the mobile network for a satisfactory level of QoS (Quality of Service) in a cost-effective manner. The location databases are used to keep track of Mobile Terminals (MT) so that incoming calls can be directed to requested mobile terminals at all times. MT reporting cell system used in location management is to designate each cell in the network as a reporting cell or a non-reporting cell. Determination of an optimal number of reporting cells (or reporting cell configuration) for a given network is reporting cell planning (RCP) problem. This is a difficult combinatorial optimization problem which has an exponential complexity. We can see that a cell in a network is either a reporting cell or a non-reporting cell. Hence, for a given network with N cells, the number of possible solutions is  . We propose a biogeography based optimization (BBO) for design of mobile station location management system in wireless communication network. The number and locations of reporting cells should be determined to balance the registration for location update and paging operations for search the mobile stations to minimize the cost of system. Experimental results show that our proposed BBO is a fairly effective and competitive approach with respect to solution quality for optimally designing location management system because BBO is suitable for combinatorial optimization and multi-functional problems.

억새와 같은 초본계 바이오매스로부터 cellulose, hemicellulose, lignin 등 주요성분을 추출하기 위해서는 알칼리 전처리가 효율적이며, 본 연구에서는 수산화칼륨(KOH)을 이용한 전처리 조건을 최적화하였다. 전처리 변수의 최적화는 반응표면분석법(RSM)을 적용하였다. RSM의 변수는 3개였으며, 변수범위는 각각 KOH 0.2∼0.8M, 반응온도 110∼190℃ 및 반응시간 10∼90min 이었다. 억새의 알칼리 전처리를 위한 최적조건은 KOH 농도 0.47M, 반응온도 134℃ 및 반응시간 65min 이었다. 최적 전 처리 조건에 따라 전처리를 수행한 후 고형물의 cellulose 함량은 66.1±1.1% 이었으며, hemicellulose 및 lignin 함량은 각각 26.4±0.4%, 3.7±0.1% 이었다. RMS 모델식에 따라 계산된 예측값은 실제값 대비 95% 범위 내에서 유효하였다. 최종적으로 전처리물을 동시당화발효를 통해 검증한 결과 에탄올 생산 수율은 96% 이었다.

A hybrid mid-story seismic isolation system with a smart damper has been proposed to mitigate seismic responses of tall buildings. Based on previous research, a hybrid mid-story seismic isolation system can provide effective control performance for reduction of seismic responses of tall buildings. Structural design of the hybrid mid-story seismic isolation system is generally performed after completion of structural design of a building structure. This design concept is called as an iterative design which is a general design process for structures and control devices. In the iterative design process, optimal design solution for the structure and control system is changed at each design stage. To solve this problem, the integrated optimal design method for the hybrid mid-story seismic isolation system and building structure was proposed in this study. An existing building with mid-story isolation system, i.e. Shiodome Sumitomo Building, was selected as an example structure for more realistic study. The hybrid mid-story isolation system in this study was composed of MR (magnetorheological) dampers. The stiffnessess and damping coefficients of the example building, maximum capacity of MR damper, and stiffness of isolation bearing were simultaneously optimized. Multi-objective genetic optimization method was employed for the simultaneous optimization of the example structure and the mid-story seismic isolation system. The optimization results show that the simultaneous optimization method can provide better control performance than the passive mid-story isolation system with reduction of structural materials.