# Self-Reporting Technique-Based Clinical-Trial Service Platform for Real-Time Arrhythmia Detection
## 3 Results
### Interworking Experiments  
The interworking experiment of the platform was performed to verify the fidelity of the data-transmission and saving processes. The assumed operation scenario was as follows: the acquired ECG data and the self-reported health information were transmitted to the AWS-VPC and DMZ, respectively, through the mobile app installed on the Galaxy S8 smartphone (Samsung Electronics, Suwon, Korea) with an Android 8.0 operating system. In the internal network, the arrhythmia-detection algorithm is executed repeatedly, and the raw ECG data, HRs, arrhythmia-detection outcomes, and other self-reported data are saved. During the process, the raw ECG is displayed through a live-streaming service.  
To evaluate the performance, a 2 Hz sinusoidal wave (amplitude: 1 mV) was applied to the VP-100. The VP-100 was 1 m away from the smartphone, and Bluetooth was paired normally. The experiment was conducted for 6 h continuously, and exactly 240 data files were expected because such files were created every 90 s. However, in the early stages of development, fewer than 200 data files were created. The loss rates were approximately 16-17% in terms of the number of created text files. To address this problem, the data-transmission processes through several pathways were scrutinized, i.e., VP-100 \(\rightarrow\) mobile app, mobile app \(\rightarrow\) AWS-VPC, AWS-VPC \(\rightarrow\) internal network. All the ECG data transmitted to the AWS-VPC were processed and saved without loss. Data were missed during the Bluetooth communication. To solve this problem, the communication protocol between the VP-100 and mobile app was improved by utilizing the index information as follows: before the transmission of the data packet, the VP-100 sends the index information, which indicates that the \(n\)th data packet is ready to be transmitted. The mobile app receives the index number and determines whether the number is correct. If the number is correct, the mobile app requests the corresponding data packet, and the VP-100 then sends the data packet immediately. However, if the number is wrong, the mobile app requests the correct number and the VP-100 responses with a modified index number. If the new number is correct, the mobile app requests the corresponding data packet. However, if it is also wrong, the corresponding data packet is regarded as missing data, and the mobile app requests the next data packet with the index number increased by one to the VP-100. With this improvement, noticeably lowered loss rates < 0.8% were obtained. During the experiments, 238-240 files were created, and all the data contained the entire sinusoidal signal without distortion. These results prove that the measured ECG can be transmitted and saved accurately using this platform.  
The real ECG were obtained from four volunteers in the SNUH-CTC. The acquisition of the ECG data from human subjects was approved by the Institutional Review Board of SNUH (Approval code: D-2001-074-1094). Figure 4 shows the real-time ECG data displayed on the mobile app and the web client, respectively. In Figure 4, a single-channel ECG, obtained from a single participant, was presented with HRs and the time of acquisition. A green CONNECTED symbol indicates a normal Bluetooth communication. Different types of symptoms and emotions can be reported at the bottom of the screen. In Figure 4, ECG data of the four participants, which were forwarded through the live-streaming service,were displayed on the web client at the same time. Each ECG datum was presented on the resizable window, separately, and clinicians could open and close these windows at any time. These data were saved in the contents server, simultaneously.