Grating lobe reduction in ultrasonic synthetic focusing

Two novel schemes of data acquisition in synthetic aperture ultrasonic imaging systems using a linear array transducer are presented to solve the troublesome grating lobe problem. Simulation and experimental results show that in both schemes the grating lobes are significantly reduced without appreciable degradation of the main lobe characteristics.<>     

Microstructure Controlled Porous Silicon Particles as a High Capacity Lithium Storage Material via Dual Step Pore Engineering

To overcome the lithium storage barriers of current lithium‐ion batteries, it is imperative that conventional low capacity graphite anodes be replaced with other higher capacity anode materials. Silicon is a promising alternative anode material due to its huge energy densities; however, its lithium‐concentration‐dependent volumetric changes can induce severely adverse effects that lead to drastic degradations in capacity during cycling. The dealloying of Si–metal alloys is recently suggested as a scalable approach to fabricate high‐performance porous Si anode materials. Herein, a microstructure controlled porous Si is developed by the dealloying in conjunction with wet alkaline chemical etching. The resulting 3D networked structure enables enhancement in lithium storage properties when the Si‐based material is applied not only as a single active material but also in a graphite‐blended electrode.     

成本有效的用于互连线条的稀释酸刻蚀后清洗

铝线条条和硅氧化物通孔刻蚀后,传统上都是使用包含胺,重金属结合剂,表面活性剂及其他成分进行清洗.这些混合剂是用来高效去除刻蚀后残留物的,而不会对硅氧化物介质造成过量的刻蚀,也不会破坏或进一步腐蚀铝.羟胺(许多此类溶解混合物的主要成分)所带来的供应、成本和残留物等问题,促使集成电路制造商寻求可替换的清洗化学试剂. 在集成电路制造的过程中,在只使用硅和硅氧化物的时期,使用浓缩和稀释的酸混合物用来清洗硅晶已有十多年的历史了.但是,当出现了铝或其他金属后,不能使用浓缩酸进行清洗,因为会对金属产生过量的破坏.近来,稀释酸混合物已成功用来高效去除铝线条和硅氧化物通孔刻蚀后的残留物,而不会对氧化物造成过量的刻蚀,也不会破坏或进一步腐蚀铝.稀释酸混合物的特征是含有两种或两种以上的硫磺酸,双氧和氢氟酸.这些化学试剂在当今的IC制造厂很容易得到,并可采用目前的清洗设备,如FSI ZETA 系统,方便地在线混合稀释.在线混合稀释化学试剂可以明显节约成本.一个批量喷雾系统可以同时处理多达100片的200mm晶圆或50片300mm晶圆,提高了产量从而节约了成本.性价比高的铝互连线条的稀释酸刻蚀后清洗已被成功验证并用于生产中.     

Implementation of mmWave long-range backhaul for UAV-BS

Uncrewed aerial vehicles (UAVs) have become a vital element in nonterrestrial networks, especially with respect to 5G communication systems and beyond. The use of UAVs in support of 4G/5G base station (uncrewed aerial vehicle base station [UAV-BS]) has proven to be a practical solution for extending cellular network services to areas where conventional infrastructures are unavailable. In this study, we introduce a UAV-BS system that utilizes a high-capacity wireless backhaul operating in millimeter-wave frequency bands. This system can achieve a maximum throughput of 1.3 Gbps while delivering data at a rate of 300 Mbps, even at distances of 10 km. We also present the details of our testbed implementation alongside the performance results obtained from field tests.     

A step-and-repeat UV-nanoimprint lithography process using an elementwise patterned stamp

Ultraviolet-nanoimprint lithography (UV-NIL) is a promising cost-effective method for defining nanoscale structures at room temperature and low pressure. To apply a large-area stamp to a high throughput step-and-repeat process at atmospheric conditions, we proposed a new UV-NIL process that uses an elementwise patterned stamp (EPS), which consists of elements separated by channels, and additive gas pressurization. The proposed UV-NIL process required just four imprints to press an 8-in. wafer. EPS features measuring 50-80 nm were successfully transferred onto the wafers. The experiments demonstrated that a 5 × 5-in.² EPS could be used with a step-and-repeat UV-NIL process to imprint 8-in. wafers under atmospheric conditions.     

Evaluation of Geometric Modeling for KOMPSAT‐1 EOC Imagery Using Ephemeris Data

Using stereo images with ephemeris data from the Korea Multi‐Purpose Satellite‐1 electro‐optical camera (KOMPSAT‐1 EOC), we performed geometric modeling for three‐dimensional (3‐D) positioning and evaluated its accuracy. In the geometric modeling procedures, we used ephemeris data included in the image header file to calculate the orbital parameters, sensor attitudes, and satellite position. An inconsistency between the time information of the ephemeris data and that of the center of the image frame was found, which caused a significant offset in satellite position. This time inconsistency was successfully adjusted. We modeled the actual satellite positions of the left and right images using only two ground control points and then achieved 3‐D positioning using the KOMPSAT‐1 EOC stereo images. The results show that the positioning accuracy was about 12‐17 m root mean square error (RMSE) when 6.6 m resolution EOC stereo images were used along with the ephemeris data and only two ground control points (GCPs). If more accurate ephemeris data are provided in the near future, then a more accurate 3‐D positioning will also be realized using only the EOC stereo images with ephemeris data and without the need for any GCPs.     

Stimuli‐Responsive Nucleic Acid‐Based Polyacrylamide Hydrogel‐Coated Metal–Organic Framework Nanoparticles for Controlled Drug Release

The synthesis of doxorubicin‐loaded metal–organic framework nanoparticles (NMOFs) coated with a stimuli‐responsive nucleic acid‐based polyacrylamide hydrogel is described. The formation of the hydrogel is stimulated by the crosslinking of two polyacrylamide chains, P_A and P_B, that are functionalized with two nucleic acid hairpins ( 4 ) and ( 5 ) using the strand‐induced hybridization chain reaction. The resulting duplex‐bridged polyacrylamide hydrogel includes the anti‐ATP (adenosine triphosphate) aptamer sequence in a caged configuration. The drug encapsulated in the NMOFs is locked by the hydrogel coating. In the presence of ATP that is overexpressed in cancer cells, the hydrogel coating is degraded via the formation of the ATP–aptamer complex, resulting in the release of doxorubicin drug. In addition to the introduction of a general means to synthesize drug‐loaded stimuli‐responsive nucleic acid‐based polyacrylamide hydrogel‐coated NMOFs hybrids, the functionalized NMOFs resolve significant limitations associated with the recently reported nucleic acid‐gated drug‐loaded NMOFs. The study reveals substantially higher loading of the drug in the hydrogel‐coated NMOFs as compared to the nucleic acid‐gated NMOFs and overcomes the nonspecific leakage of the drug observed with the nucleic‐acid‐protected NMOFs. The doxorubicin‐loaded, ATP‐responsive, hydrogel‐coated NMOFs reveal selective and effective cytotoxicity toward MDA‐MB‐231 breast cancer cells, as compared to normal MCF‐10A epithelial breast cells.     

The implementation of TS MAC (transmitter station monitor, alarmand control) system for digital DBS system

The implementation of TS MAC system for KOREASAT DBS (direct broadcast satellite) system is presented. This TS MAC controls and monitors the status of the TS equipment and gathers the alarm for them. The advantage of this system is the center-concentrated, real time processing, remote control, and object oriented module decomposing