가스 분리막은 에너지 효율적인 가스 정제와 탄소 포집을 위한 핵심 기술이지만, 기존의 고분자 분리막은 투과도 와 선택도 사이의 상충관계를 피하기 어렵다. 이러한 한계를 극복하기 위해 다공성 소재가 유망한 대안으로 주목받고 있다. 본 리뷰에서는 가스 분리막 분야에서 최근 활발히 연구되고 있는 주요 다공성 소재인 금속-유기 골격체(MOFs), 제올라이트, 그리고 기타 다공성 소재에 대한 연구 동향을 정리한다. 조절 가능한 기공 구조를 갖는 MOF는 혼합매질 막(MMMs)에 필러 또는 단독 막 형태로 적용되어 선택도와 투과도를 향상시킨다. 제올라이트는 우수한 분자체 성능과 높은 내구성을 바탕으로 까다로운 분리 공정에서도 탁월한 성능을 보인다. 또한 다양한 차세대 다공성 소재 는 기존의 한계를 뛰어넘는 성능을 구현 할 수 있는 분리막 재료로 평가된다. 최근 연구들은 다공성 필러를 도입하거나 다공성 구조를 지닌 매트릭스를 설계함으로써, 기존 고분자 분리막의 한계를 넘어서는 높은 선택도와 투과도를 동시에 달성할 수 있음을 보여준다. 본 리뷰는 다공성 소재 기반 고성능 가스 분리막 연구의 최신 동향을 정리하고, 향후 발전 방향에 대한 통찰을 제공하는 데 목적이 있다.

In the present analysis study, an analysis model was developed using ANSYS Workbench to verify the dynamic characteristics of the cabinet and the vibration reduction effect of applying TMD. The analysis modeled a simplified equivalent structure of a nuclear power plant cabinet, and a method was explored to reduce the cabinet's resonant response by installing TMD on top of the cabinet. For the analysis, harmonic loads and SSE seismic waves were input to conduct modal analyses of the cabinet and TMD. The cabinet vibration reduction effect of TMD installation was investigated, as well as the time histories of displacement and acceleration. The analysis results showed that the primary mode of the cabinet had a MPMR of approximately 53.9%, significantly affecting the dynamic behavior of the cabinet compared to other modes. However, a MPMR of approximately 8.9% was also observed in higher-order modes. With TMD installed, the peak response was significantly reduced, the larger curve split into two smaller curves, and the response at the original natural frequency was reduced by up to approximately 60%. The cabinet's time response showed a decrease in displacement/acceleration vibration response as the damping ratio increased. This indicates a narrow bandwidth and peak suppression of the response envelope, and the maximum displacement and acceleration reduction effects were approximately 33.1% and 27%, respectively.

To improve the seismic performance of a cabinet, a TMD was designed and its dynamic behavior was experimentally investigated as a basic study on vibration reduction. For TMD vibration test, a testing machine base, sliding base and jig were constructed. TMD and base were excited at the same frequency, and their natural frequencies showed a phase difference of approximately 90 degrees. The specifications of the experimental TMD were 20 kg mass, 10% damping ratio, and 7 L of oil. Seismic tests were conducted to investigate the dynamic behavior of the cabinet under earthquakes and the vibration characteristics of the cabinet with and without TMD. Vibration tests were conducted with the cabinet door fully closed, and the acceleration at the top of the cabinet was measured. The maximum acceleration was reduced by approximately 36% when TMD was installed compared to when it was not installed. The experimental results clearly demonstrated the effectiveness of TMD in reducing cabinet vibration.

In the present study, to investigate the seismic behavior of a cabinet under earthquakes, three types of mass blocks (top load, center load, and bottom load) were selected as the cabinet's internal structure, and the vibration characteristics according to the load arrangement were studied. The internal structure simulates the device modules installed inside the cabinet. The cabinet's modal characteristics and response spectrum were evaluated under the three types of loads. Six modes, displacement, and acceleration responses for each load were analyzed. The analysis results showed that mode 1 had the lowest frequency, and that the frequency increased by approximately two times as the mode increased. The change in natural frequency according to load placement was confirmed through modal analysis of the cabinet. The cabinet's displacement and acceleration were greatest in the x-axis and lowest in the y-axis. Displacement and acceleration according to the load distribution at the top, center, and bottom were within a certain range, so the vibration characteristics of the internal structure of the cabinet were limitedly affected.

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.

The purpose of this paper is to investigate the vibration phenomenon occurring in the structure such as a ship with the hemispherical substructure and operating at fixed frequency, and to suggest the active vibration control method using the Fx-LMS algorithm to reduce vibration amplification. In order to study the possibility of reducing vibration in the hemispherical structure, the active vibration control model was developed and a vibration control experimental device for the hemispherical structure was constructed. The narrowband Fx-LMS algorithm was developed to enable precise real-time control at a specific frequency, and the secondary path for dynamic control was modeled with two coefficients per frequency. The experimental device is equipped with three exciters, six 3-axis actuators, and six 3-axis error sensors, which can acquire 18 error sensor signals. Real-time secondary path tracking was possible with the secondary path consisting of two coefficients and the control algorithm, and effective vibration control performance was confirmed through this. And the experimental results of active vibration control of the exciter for three frequencies showed that the exciter vibration was reduced by a minimum of 63.7% and a maximum of 97.7%, which shows the possibility of reducing the vibration of the structure in real time using the proposed method.

The purpose of this study is to investigate the dynamic behavior of the internal cabinet of a nuclear power plant due to an earthquake and the characteristics of cabinet vibration reduction by TMD(tuned mass damper). For this purpose, the experimental device was constructed and numerical analysis was performed. The experimental device for the dynamic behavior of the cabinet consists of a cabinet, sliding base, mount, actuator, exciter, and measuring system, and the frequency response function of the cabinet was obtained. In addition, the time history of the cabinet was analyzed for acceleration and displacement through TMD design and cabinet 3D modeling. The natural frequency and response of the cabinet were lowered by approximately 26% due to the structural rigidity of the cabinet under the conditions of door opening and sliding base strong excitation. The acceleration and displacement characteristics of the cabinet varied depending on the TMD mass, and the cabinet vibration reduction effect was the best when the TMD mass was 60kg. The reduction in acceleration and displacement of the cabinet was approximately 12.1–16.2% and 10.1–19.1%, respectively.

In this study, in order to identify the vibration characteristics of the process control cabinet, as a basic study for evaluating the seismic performance of nuclear power plant structures, a cabinet vibration test equipment, sliding base, and measurement system were constructed. The reliability of the base was verified by utilizing ODS and phase data to determine how the cabinet deforms under seismic conditions. In addition, the cabinet was subjected to excitation frequencies from 8 Hz to 15 Hz in order to examine the changes in the natural frequency of the cabinet according to the two types of sliding base motion and the cabinet door open/close status. The vibration characteristics of the empty cabinet were investigated experimentally to examine the cabinet excitation characteristics and changes in natural frequency. Since the structural rigidity of the cabinet changes depending on the excitation conditions and door opening/closing, the natural frequency and response size of the cabinet change. Since the door opening is a condition that greatly amplifies the cabinet vibration response, it causes structural defects and greatly affects the changes in natural frequency.

In this study, an active vibration control experiment was conducted on a display manufacturing system weighing approximately 15 tons. Three pneumatic shakers were installed underneath the equipment to excite the entire structure at three different frequencies. On the top side of the equipment, four inertial-type electromagnetic actuators capable of generating forces in the x, y, and z directions were mounted, enabling 12 degrees of freedom to be controlled. At locations near the actuators, four tri-axial accelerometers were installed to obtain 12 error signals. Vibrations at three distinct frequencies induced by the pneumatic shakers were measured at these 12 locations using the accelerometers. Active vibration control was performed by driving the inertial actuators using a narrow-band Fx-LMS algorithm to reduce the measured error signals. As a result of the control, the vertical vibration at 24 Hz was successfully reduced by 10.95 dB.

In this study, a response model of a beam structure was established through finite element analysis by analyzing the vibration response to external excitation. The vibration control performance of the beam was then evaluated by applying the narrow-band Fx-LMS algorithm for active structural control. The transfer function was obtained at the error sensor location when the structure was excited and the three-axis actuator was operated. The performance of the active control was investigated with 18 channels for error input and actuator output. When the equipment is exciting, the response of the error sensor is the primary path, and when the inertial 3-axis actuator operates, the response of the error sensor position is the secondary path, and the Fx-LMS algorithm is applied. The simulation was performed by changing the control parameters so that the response of the error sensor can satisfy the target performance. From the results of this study, the acceleration results over time showed about 70% vibration reduction after active control, and the average error value of the error sensor also decreased by about 68%. In addition, it was confirmed that real-time control of a system with 18 sensors and 18 actuators is possible even if the secondary path is configured in two orders.

The purpose of this study is to examine the application and effectiveness of tuned mass dampers for reducing cabinet vibration in plants. Cabinet with lower structural rigidity than plant subject to seismic design standards is susceptible to resonance. SolidWorks was used for 3D modeling of the cabinet, and ANSYS Workbench was used to create a mesh. The vibration characteristics of the cabinet were investigated through modal analysis, and the possibility of resonance and vibration reduction performance of the cabinet were evaluated. The number of modes in the cabinet was set to 100, and the frequency and modal participation mass ratio of each mode were calculated. In order to examine the possibility of vibration reduction by tuned mass dampers, the vibration response characteristics of cabinets with and without tuned mass dampers were compared. The analysis results showed that the third mode had a significant effect on the dynamic behavior of the cabinet and that the modal participation effective mass ratio was larger than that of other vibration modes. And as the mass of the tuned mass damper increased, the vibration response of the cabinet decreased significantly, and the peak value of the cabinet decreased by up to 52%.

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.