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Feasibility Study for the Evaluation of Chicken Meat Storage Time Using Surface Acoustic Wave Sensor
김건우,조병관,오상협,김기복 한국농업기계학회 2020 바이오시스템공학 Vol.45 No.4
Purpose The objectives of this study are to provide the detailed information of designing, fabrication process, and performance test results of a surface acoustic wave (SAW) sensor for evaluating chicken meat storage time (up to 15 days). Methods The aldehyde gas generated from chicken meat was selected as the reactive material, and Love wave was used among various SAWs due to its high sensitivity of the aldehyde gas particles. The SAWsensor was fabricated on the surface of LiNbO3 piezoelectric wafer with a cross-linked polydimethylsiloxane (PDMS)-sensitive layer using standard photolithographic techniques. To analyze the fabricated SAW sensor characteristics, the S21 parameters and base line noise were acquired by a vector network analyzer. Before measuring chicken meat gas samples, a reference gas (a mixture of 25, 50, 75, and 100 ppm acetaldehyde (a functional group with the structure –CHO, CH3CHO) and nitrogen (N2) gas) was measured to verify the reactive performance of the SAWsensor. Among the VOCs from chicken meat gas, CH3CHO was selected as an intrinsic biomarker due to its harmful effects on the human body. Then, aldehyde gas from chicken meat samples was measured and the phase changes of the response signals with increasing the chicken meat storage time were obtained by the SAW sensor. Results About − 4 dB insertion loss occurred due to the PDMS coating and the high electromechanical coupling factor of used substrate. The phases of the response signals decreased linearly with increase of both the reference gas concentration and the storage time of the chicken meat samples. The determination coefficients of the reference gas and the storage time were over 0.9. The results show that the developed SAW sensor can provide valuable information about evaluating the chicken meat storage time. Conclusion The newly developed SAW sensor clearly demonstrates that chicken meat storage could be evaluated by detecting aldehyde gas. This opens a promising research avenue to explore.
Client-Side Deduplication to Enhance Security and Reduce Communication Costs
김건우,윤택영,조남수,장구영 한국전자통신연구원 2017 ETRI Journal Vol.39 No.1
Message-locked encryption (MLE) is a widespread cryptographic primitive that enables the deduplication of encrypted data stored within the cloud. Practical clientside contributions of MLE, however, are vulnerable to a poison attack, and server-side MLE schemes require large bandwidth consumption. In this paper, we propose a new client-side secure deduplication method that prevents a poison attack, reduces the amount of traffic to be transmitted over a network, and requires fewer cryptographic operations to execute the protocol. The proposed primitive was analyzed in terms of security, communication costs, and computational requirements. We also compared our proposal with existing MLE schemes.
김건우,한정규,문건우 전력전자학회 2019 전력전자학회 논문지 Vol.24 No.6
Three-level (3L) DC–DC converters are appropriate for high-input-voltage applications. Although the voltage stress of TL converter switches can be reduced to half of the input voltage, the primary side has a large circulating current, which degrades efficiency. In this study, a dual half-bridge cascaded TL converter is presented to reduce this circulating current and thus decrease the conduction loss of the primary circuit. Moreover, the proposed converter can reduce the voltage stress of rectifier diodes, thereby reducing their conduction loss. Therefore, efficiency can be improved by reducing the conduction loss of the primary circuit and rectifier diodes.