Journal Jurnal Teknologi dan Sistem Komputer-
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 134-140; doi:10.14710/jtsiskom.7.4.2019.134-140
This study examines the user position tracking system using marker-based AR on smartphones camera. The tracking system uses a homographic algorithm integrated into the Galeri Museum VR application. In the test, the user performed exploration interactions by 6 degrees of freedom in ten different positions in the museum gallery. The physical space used in this study was 4 x 4 m2 and a marker attached to the wall in front of the user. This system results in errors in XYZ field (0.102 m, 0.047 m, 0.044 m). If the camera's orientation is not directing to the marker and the user is moving, jitter appears because of the untracked marker. The use of marker-based AR successfully applied to track the position of users who perform natural locomotion interactions in the VR environment.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 154-160; doi:10.14710/jtsiskom.7.4.2019.154-160
Propagation is one of the important factors to understand in wireless communication systems. Prediction of the value of propagation, especially for closed areas, is very necessary to determine success in building wireless networks. Various kinds of propagation modeling were developed to find the best approach to calculate the value of signal losses. A comparative study of 4 types of empirical propagation modeling was made to provide the most suitable propagation modeling analysis for campus wireless networks. The ITU-R model (P.1238) provides predictive results that are closest to the actual data in the field, with a relative error rate of 16.381%.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 166-171; doi:10.14710/jtsiskom.7.4.2019.166-171
The threat of earthquake calamity spread throughout most of the Indonesian archipelago. Smartphone’s accelerometer usage as a seismic parameter detector in Indonesia, of which the noise has obstacles, mainly due to human activities. This study aims to classify linear acceleration signals caused by human activity and earthquake acceleration signals as an initial effort to reduce noise caused by human activity in the smartphone’s accelerometer signals. Both signals are classified by using the Support Vector Machine (SVM) algorithm of which consists of several steps, respectively, data collection, data preprocessing, data segmentation, feature extraction, and classification. These algorithms are tested to 2545 human activity signals in trouser pocket, 2430 human activity signals in shirt pocket and earthquake acceleration signals. Based on the test results by using the confusion matrix, linear acceleration signal data caused by human activity and earthquake acceleration signals can be classified properly using an SVM algorithm with Polynomial or Gaussian kernel with a small kernel scale value. The algorithms can achieve an accuracy of 87.74% to 97.94%.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 161-165; doi:10.14710/jtsiskom.7.4.2019.161-165
This study aims to apply the Internet of Things (IoT) technology to control electronic devices and monitor the electrical power usage remotely via the Internet. The system was implemented using Wemos D1, ACS712 current sensor, relay, and the Blynk application as the system interface on the smartphone. The system used an average of 0.4-3.3 seconds to respond to commands from the Blynk application via a Wifi connection at a distance of 50-1000 meters and the device control and power monitoring system can function properly. The system response time was not affected by distance. This system with Wifi access can be an alternative to control devices and monitor their power usage in addition to a longer time of SMS access and shorter range of Bluetooth.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 127-133; doi:10.14710/jtsiskom.7.4.2019.127-133
This study examines the performance of a communication gateway for IoT devices by utilizing the XMPP protocol so that these devices can be connected and communicate using the Internet. The sensor nodes, which are IoT devices, were implemented using NodeMCU connected to the DHT11 sensor module and LED lights to simulate the incoming data. Sensor nodes can communicate using the XMPP protocol gateway and process the request-response data. Gateway data transmission performance with size variations from 10-100 MB gets an average delay time of 9.3 ms, an average jitter of 0.00178 ms, and an average throughput of 161.4 kbps. The CPU usage parameter has an average increase of 12%, and memory usage tends to be constant when data transmission occurs.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 147-153; doi:10.14710/jtsiskom.7.4.2019.147-153
This study aims to measure the quality of service of agricultural extension workers at the UPT. BPP Sukaraja uses the fuzzy service quality (servqual) method by grouping question attributes into five service dimensions criteria, namely the dimensions of tangibles (direct evidence), reliability (responsibility), responsiveness, assurance, and empathy. The study showed that the value of the gap that requires the priority of improvement and improvement in service quality is the dimension of Tangibles with a negative gap value of -0.45 that means that the expectations of farmers are still not achieved. The customer satisfaction index is 87.93%, which means farmers are satisfied with the services provided. The study can be a motivation to improve the quality of service to farmers for UPT BPP Sukaraja.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 141-146; doi:10.14710/jtsiskom.7.4.2019.141-146
The encryption of digital images has become essential since it is vulnerable to interception while being transmitted or stored. A new image encryption algorithm to address the security challenges of traditional image encryption algorithms is presented in this research. The proposed scheme transforms the pixel information of an original image by taking into consideration the pixel location such that two neighboring pixels are processed via two separate algorithms. The proposed scheme utilized the Gray code number system. The experimental results and comparison shows the encrypted images were different from the original images. Also, pixel histogram revealed that the distribution of the plain images and their decrypted images have the same pixel histogram distributions, which means that there is a high correlation between the original images and decrypted images. The scheme also offers strong resistance to statistical attacks.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 121-126; doi:10.14710/jtsiskom.7.4.2019.121-126
Software Defect Prediction (SDP) provides insights that can help software teams to allocate their limited resources in developing software systems. It predicts likely defective modules and helps avoid pitfalls that are associated with such modules. However, these insights may be inaccurate and unreliable if parameters of SDP models are not taken into consideration. In this study, the effect of parameter tuning on the k nearest neighbor (k-NN) in SDP was investigated. More specifically, the impact of varying and selecting optimal k value, the influence of distance weighting and the impact of distance functions on k-NN. An experiment was designed to investigate this problem in SDP over 6 software defect datasets. The experimental results revealed that k value should be greater than 1 (default) as the average RMSE values of k-NN when k>1(0.2727) is less than when k=1(default) (0.3296). In addition, the predictive performance of k-NN with distance weighing improved by 8.82% and 1.7% based on AUC and accuracy respectively. In terms of the distance function, kNN models based on Dilca distance function performed better than the Euclidean distance function (default distance function). Hence, we conclude that parameter tuning has a positive effect on the predictive performance of k-NN in SDP.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 98-102; doi:10.14710/jtsiskom.7.3.2019.98-102
During the process of using containers by the importer, the shipping company as the owner of the container is often faced with the problem of those who must be responsible for handling containers that are damaged when shipping goods. This study examines the application of the Naïve Bayes method to help the container owner to make a decision in analyzing each case of objection from the importer. The analysis was carried out for each objection case submitted by the importer regarding subsidizing the cost of repairs to be given a FREE or PAID decision by considering 4 factors, which are the damaging side, the damage, the type of damage, and the cost of repairs. From 48 datasets collected and analyzed, the decision has an accuracy rate of 63.3% in subsidizing of container repair costs.
Jurnal Teknologi dan Sistem Komputer, Volume 7, pp 116-120; doi:10.14710/jtsiskom.7.3.2019.116-120
In the campaign period of regional heads election, fraud can occur, such as money politics, blaming campaign facilities, campaign time violations, and black campaign. This study implemented a secure SMS application for election fraud complaints as a tool for the society to report all forms of election fraud that have occurred to the election supervisory department safely. The RSA algorithm was applied to encrypt the messages for sender privacy protection. The application was able to perform the message randomization function properly with a 10.44% avalanche effect. Brute force attack using a 16-bit key length needs 3.7 milliseconds for each try to find 32.768 possible private keys.