Pebax 기반 멤브레인은 최근 가스 분리 응용 분야, 특히 이산화탄소(CO2) 포집과 관련하여 큰 주목을 받아왔다. 본 총설은 Pebax 기반 멤브레인에 관한 연구 논문을 종합적으로 다루고 있으며, 전통적인 투과도와 선택성 간의 상충 관계를 극복하기 위한 실험적 및 멤브레인 모듈 전략을 중점적으로 다룬다. 주요 접근법으로는 이산화탄소 친화성 첨가제와의 고분 자 블렌딩, 금속-유기 골격체(MOFs), 제올라이트 이미다졸레이트 골격체(ZIFs), 공유 유기 골격체(COFs), 이차원(2D) 나노소 재와 같은 다공성 충전재를 도입한 혼합매질 멤브레인(MMMs)을 다룬다. 또한, 멤브레인 자체 투과도의 향상을 위한 박막 복 합체(TFCs) 및 중공사형(hollow fiber) 멤브레인 기술에 대해서도 다룬다. 이러한 혁신적 접근은 다수의 Pebax 기반 멤브레인 이 Robeson upper bound를 넘어설 수 있는 높은 이산화탄소 투과도와 선택성을 동시에 달성하였다. 본 총설에서는 충전재의 분산도, 고분자-충전재 간 계면 호환성, 그리고 구조적 형태가 가스 전달 성능에 미치는 영향을 중점적으로 분석한다. 또한 가소화(plasticization), 노화(aging), 습윤 환경에서의 성능과 같은 실용적 멤브레인의 한계를 논의하며, Pebax 기반 기체 분리 멤브레인의 현재 연구 동향, 소재 설계 원리, 향후 발전 방향에 대한 심층적인 내용을 다룬다.

유리상 고분자 멤브레인은 높은 투과도와 선택도를 동시에 달성하면서도 에너지 소비가 낮아, 고성능 기체 분리 용 멤브레인 후보로 주목받아 왔다. 그러나 기존 고분자 멤브레인은 Robeson 상한선으로 표현되는 투과도-선택도 간의 고유 한 상충관계에 의해 성능이 제한되는 한계를 지닌다. 최근 수년간, 고유 자유부피가 큰 유리상 고분자, 특히 고유 미세다공성 고분자(PIMs) 및 6FDA 기반 폴리이미드와 같은 고성능 재료의 개발이 활발히 이루어지며 이러한 병목 현상을 극복하고 있 다. 고분자 주 사슬 구조 설계, 후 합성 기능화, 고분자 블렌딩, 다공성 필러를 포함한 혼합 매질 멤브레인(mixed-matrix membrane, MMM) 제조, 열재배열 공정 등 다양한 전략을 통해 기체 분리 성능이 크게 향상되었다. 본 총설에서는 유리상 고 분자 기반 기체 분리 멤브레인의 최신 연구 동향을 다룬다. 특히, PIM-1 및 유도체, 6FDA 기반 폴리이미드, MMM을 중심으 로 어떻게 투과도-선택도 상충관계, 물리적 노화, 가소화 저항성과 같은 핵심 기술적 과제를 해결하는지를 다룬다. 최신 문헌 분석을 통해, 유리상 고분자 멤브레인이 기체 분리 성능의 새로운 기준을 제시하고 있으며, 탄소 포집부터 천연가스 처리에 이르기까지 상업적 적용 가능성이 높아지고 있음을 논의한다. 마지막으로, 이러한 멤브레인 기술이 산업적 응용으로 이어지 기 위한 주요 과제와 향후 연구 방향에 대해 고찰한다.

Microalgae are efficient fatty acid producers owing to their high photosynthetic activities. They can act as sources of biofuel, feed, and various bioactive compounds. This study aimed to determine optimal culture conditions, including culture medium, temperature, and light intensity, to enhance the biomass and fatty acid content of the indigenous freshwater microalga, Tetradesmus obliquus. Evaluation using a high-throughput photobioreactor revealed that the optimal culture temperature and light intensity were 25°C and 300 μmol m-2 s-1, respectively. Additionally, we optimized components (N, P, and Mg) of the BG-11 medium to enhance the microalgal biomass. Modified BG-11 medium increased the T. obliquus biomass by 37% compared to the standard BG-11 medium. Subsequently, the culture medium was replaced with N- and P-depleted media to determine the abiotic stress factor that could increase the cellular fatty acid content. Notably, fatty acid content was significantly increased from 8.5% up to 14.6% on day 7 of culture in N-deficient (N-P+ and N-P-) media. Sequential optimization effectively increased the biomass by 83% and fatty acid content by >76% in T. obliquus. Our optimization method can be used to enhance the biomass and fatty acid contents of various other microalgae.

In this study, the initial operation characteristics of a multi-type cooling system with three indoor units using an inverter compressor were investigated experimentally using a calorimeter. The operating characteristics of the cooling system were confirmed under the full load condition of simultaneous operation of three rooms and the partial load condition of individual operation of two or one room under the standard cooling conditions. The capacities of A, B and C are 50, 20, and 30% of the total capacity, respectively. The 3 room combination has 100% capacity, the 2 room combination has 50, 70 and 80% capacity, and the 1 room has 20, 30, and 50% capacity. The compressor condensing and evaporating pressures, the electronic expansion valve openings of indoor units A, B, and C, and the compressor operating frequencies were measured for 10 minutes after the cooling system was started. During the initial operation, the changes in the operating time and opening of the electronic expansion valve varied depending on the indoor unit combination and the operating load, and the relationship between the compressor pressure and the operating frequency was found.

For experimental studies on the production of MR fluid for MR dampers, MR fluid with a viscosity of 506 cP and a density of 2.6 g/cc was produced. In order for MR fluid to have suitable performance for MR dampers, it is important to select surfactants, magnetic particles, base oil, and characteristic additives to obtain high damping force and maintain physical and chemical properties. In order to investigate the redispersibility of MR fluid, viscosity, density, saturation magnetic flux density, dispersibility, and temperature effects were evaluated. A particle size distribution meter and a vibrating magnetometer were used, and a yield stress and redispersion device were developed to obtain the yield stress of the MR fluid. The recovery rate of MR fluid was approximately 97% at 0.2% succinic acid coating and 8% anti-settling agent. And when current is applied, the viscosity increases by more than 90% due to magnetic properties.

In order to design a seismic safety of a cabinet affected by an earthquake, vibration analysis was performed using a model cabinet. In order to analyze the vibration characteristics of the cabinet under earthquake conditions, 3D finite element analysis was performed using ANSYS Workbench and SolidWorks. The modal analysis of the cabinet showed nine natural modes and natural frequencies, and showed the deformation and vibration of the cabinet panel for each mode. The frequencies of the 1st and 2nd modes, which are low modes, were 10% of the natural frequency value of the 9th mode, so it was easy to predict the possibility of resonance occurrence. The response spectrum due to the earthquake showed that the displacement, acceleration, and stress distribution of the cabinet had different behaviors in the x, y, and z directions, and especially showed very large values in the z direction. Although the vibration characteristics of the structure were evaluated using the modal characteristics and response spectrum for the cabinet, research on the application of a tuned mass damper is necessary for the dynamic characteristics process of the cabinet due to an earthquake and resonance reduction.

In order to understand the MR fluid flow in the MR damper core, the annular orifice path was simplified into a square channel and the electromagnetic flow was analyzed. For this purpose, the CFD-ACE+ program was used. The temperature and magnetic field of the MR fluid were based on room temperature and orifice wall data, and 2-D steady incompressible laminar flow was assumed. The inlet and outlet of the orifice channel are at atmospheric pressure, and the inflow velocity of the MR fluid is 0.1 m/s. After analyzing the magnetic field of the core, which is a simple model of the 1 stage MR damper, the electromagnetic flow analysis of the MR fluid flowing through the orifice channel was performed. From this, the magnetic field of the orifice channel and the electromagnetic flow of the MR fluid were observed. As the magnetic flux density increased, the flow distribution and velocity of the MR fluid in the channel core changed significantly.