2020, Vol.15, No.4

Journal of Knowledge Information Technology and Systems 2023 KCI Impact Factor : 0.89

pISSN : 1975-7700 / eISSN : 2734-0570
https://journal.kci.go.kr/kkits

In modern society, security-enhanced access control systems are an important factor. In this paper real-time smart access control system using a face recognition camera and OTAC(One Time Access Code) is proposed. This system especially focuses on the response speed of the embedded board to implement a delay-free system. Most access control systems on the market uses RFID to authenticate users. RFID has the advantage of fast authentication time and high usability. However, system’s weak points arise because others can steal and manipulate them. There are biometric recognition methods as supplant method, such as facial recognition, vein matching, iris recognition and fingerprint recognition are used as technical methods. The method proposed in this paper uses facial recognition technology and OTAC authentication. This is implemented on the embedded board by linking the depth information camera and the user DB server which is built on cloud environment. The embedded system was designed using Python, C++, C and PHP on Raspberry Pi 3 Model B+, Ubuntu 18.04 LTS and Arduino Due. Then communicated with each other using Wi-Fi and Serial Communication. In addition, the driving speed, one of the important specs, was 300 ms, which resulted in conformity with the designed specification. This system’s prototype was manufactured to prove the practicality and efficiency of the system.

E-commerce product recommendation uses various recommendation techniques. The recommendation techniques that are generally applied include the collaborative filtering technique, the user based collaborative filtering, and the item based collaborative filtering technique, and utilizes recommended techniques based on artificial intelligence technologies such as Recurrent Netural Network (RNN) and Long Short Term Memory (LSTM). The recommendation data generated through these recommendation techniques are stored in a database and are recommended in the form of static data by user actions (search, order, etc.). However, the recommendation through the static recommendation product list is limited in improving the purchasing power of the user. Providing a variety of recommended products and real-time properties, it is possible to further improve purchasing power if it is possible to dynamically construct a recommended product list. Therefore, this paper proposes an architecture and procedure for providing dynamic recommendations. The proposed dynamic recommendation architecture constructs a dynamic recommendation product by applying a static recommendation product based on Elasticsearch. In the experiment, accuracy was compared and analyzed by applying the same transaction data to existing recommendation techniques, and it was confirmed that the accuracy of the dynamic recommendation technique proposed in this paper is improved compared to the existing recommendation techniques.

In designing the branch line coupler, it is very important to set the impedance of each line because the amount of signal coupling at the output port is determined by the impedance of each line constituting the branch line. Since the coupling coefficient between the input and output ports is determined by the impedance condition of the line in the multi-stage branch line structure, the impedance of each line to obtain the desired coupling coefficient can be obtained by applying even-odd mode circuit analysis. In this paper, the multi-stage microstrip branch line structure is constructed and a hybrid coupling structure is used to distribute the half-power type of circuit lines connected to each port for signal transmission. We also obtained the broadband characteristics by optimizing the width and length of the line impedance to reduce the phase error within the operating range. We also analyzed the influence of the output signal amplitude and phase error on the beam pattern and beam steering direction obtained from the wide band design results of the five-stage branch line coupler. The fabricated hybrid branch line coupler has the operating frequency band of 2.15 GHz to 3.4 GHz, with a relative bandwidth of about 47%. In the band, the transmission characteristic and phase difference between output ports are less than 3.3 ± 0.5 dB and 90±1°. It shows good insertion loss, a half power and wide band characteristics.