Christine Dewi

Dr. Christine Dewi

Satya Wacana Christian University, Salatiga, Indonesia
orcid
Senior Lecturer at Satya Wacana Christian University

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
23 July 2020 in Journal of Big Data
Verified
Journal Article
Open access
PDF file
Rung-Ching ChenRung-Ching Chen
Rung-Ching Chen
Christine DewiChristine Dewi
Christine Dewi
SHSu-Wen Huang
Su-Wen Huang
Rezzy Eko CarakaRezzy Eko Caraka
Rezzy Eko Caraka
Feature selection becomes prominent, especially in the data sets with many variables and features. It will eliminate unimportant variables and improve the accuracy as well as the performance of classification. Random Forest has emerged as a quite useful algorithm that can handle the feature selection issue even with a higher number of variables. In this paper, we use three popular datasets with a higher number of variables (Bank Marketing, Car Evaluation Database, Human Activity Recognition Using Smartphones) to conduct the experiment. There are four main reasons why feature selection is essential. First, to simplify the model by reducing the number of parameters, next to decrease the training time, to reduce overfilling by enhancing generalization, and to avoid the curse of dimensionality. Besides, we evaluate and compare each accuracy and performance of the classification model, such as Random Forest (RF), Support Vector Machines (SVM), K-Nearest Neighbors (KNN), and Linear Discriminant Analysis (LDA). The highest accuracy of the model is the best classifier. Practically, this paper adopts Random Forest to select the important feature in classification. Our experiments clearly show the comparative study of the RF algorithm from different perspectives. Furthermore, we compare the result of the dataset with and without essential features selection by RF methodsvarImp(),Boruta, and Recursive Feature Elimination (RFE) to get the best percentage accuracy and kappa. Experimental results demonstrate that Random Forest achieves a better performance in all experiment groups.

2 July 2021 in IEEE Access
Verified
Journal Article
Open access
Christine DewiChristine Dewi
Christine Dewi
Rung-Ching ChenRung-Ching Chen
Rung-Ching Chen
YLYan-Ting Liu
Yan-Ting Liu
XJXiaoyi Jiang
Xiaoyi Jiang
KHKristoko Dwi Hartomo
Kristoko Dwi Hartomo
Convolutional Neural Networks (CNN) achieves perfection in traffic sign identification with enough annotated training data. The dataset determines the quality of the complete visual system based on CNN. Unfortunately, databases for traffic signs from the majority of the world's nations are few. In this scenario, Generative Adversarial Networks (GAN) may be employed to produce more realistic and varied training pictures to supplement the actual arrangement of images. The purpose of this research is to describe how the quality of synthetic pictures created by DCGAN, LSGAN, and WGAN is determined. Our work combines synthetic images with original images to enhance datasets and verify the effectiveness of synthetic datasets. We use different numbers and sizes of images for training. Likewise, the Structural Similarity Index (SSIM) and Mean Square Error (MSE) were employed to assess picture quality. Our study quantifies the SSIM difference between the synthetic and actual images. When additional images are used for training, the synthetic image exhibits a high degree of resemblance to the genuine image. The highest SSIM value was achieved when using 200 total images as input and 32×32 image size. Further, we augment the original picture dataset with synthetic pictures and compare the original image model to the synthesis image model. For this experiment, we are using the latest iterations of Yolo, Yolo V3, and Yolo V4. After mixing the real image with the synthesized image produced by LSGAN, the recognition performance has been improved, achieving an accuracy of 84.9% on Yolo V3 and an accuracy of 89.33% on Yolo V4.

24 April 2021 in Neural Computing and Applications
Verified
Journal Article
Closed access
PDF file
Christine DewiChristine Dewi
Christine Dewi
Rung-Ching ChenRung-Ching Chen
Rung-Ching Chen
YLYan-Ting Liu
Yan-Ting Liu
Shao Kuo TaiShao Kuo Tai
Shao Kuo Tai

18 April 2022 in PeerJ Computer Science
Verified
Journal Article
Open access
PDF file
Christine DewiChristine Dewi
Christine Dewi
Rung-Ching ChenRung-Ching Chen
Rung-Ching Chen
XJXiaoyi Jiang
Xiaoyi Jiang
Hui YuHui Yu
Hui Yu
Blink detection is an important technique in a variety of settings, including facial movement analysis and signal processing. However, automatic blink detection is very challenging because of the blink rate. This research work proposed a real-time method for detecting eye blinks in a video series. Automatic facial landmarks detectors are trained on a real-world dataset and demonstrate exceptional resilience to a wide range of environmental factors, including lighting conditions, face emotions, and head position. For each video frame, the proposed method calculates the facial landmark locations and extracts the vertical distance between the eyelids using the facial landmark positions. Our results show that the recognizable landmarks are sufficiently accurate to determine the degree of eye-opening and closing consistently. The proposed algorithm estimates the facial landmark positions, extracts a single scalar quantity by using Modified Eye Aspect Ratio (Modified EAR) and characterizing the eye closeness in each frame. Finally, blinks are detected by the Modified EAR threshold value and detecting eye blinks as a pattern of EAR values in a short temporal window. According to the results from a typical data set, it is seen that the suggested approach is more efficient than the state-of-the-art technique.

19 November 2021 in Journal of Ambient Intelligence and Humanized Computing
Verified
Journal Article
Closed access
PDF file
Christine DewiChristine Dewi
Christine Dewi
Rung-Ching ChenRung-Ching Chen
Rung-Ching Chen
Hui YuHui Yu
Hui Yu
XJXiaoyi Jiang
Xiaoyi Jiang

28 August 2023 in IEEE Access
Verified
Journal Article
Open access
Rung-Ching ChenRung-Ching Chen
Rung-Ching Chen
Christine DewiChristine Dewi
Christine Dewi
YZYong-Cun Zhuang
Yong-Cun Zhuang
JCJeang-Kuo Chen
Jeang-Kuo Chen
In recent years, artificial intelligence has led to rapid development and application across various industries, which has prompted this. One of the significant developments is the improvement of transportation methods. Accidents involving vehicles frequently result in a high number of fatalities as well as economic damage. Road detection is one of the applications that can be used by self-driving cars. Traffic accidents happen, but artificial intelligence is used in many nations to construct smart cities and apps for self-driving cars. Since public road sign datasets have been used in significant research for road sign identification and analysis, these datasets are particularly significant for training autonomous vehicles. This study records the roads of various cities in Taiwan through road driving. It manually collects traffic signs in Taiwan to create a data set of road signs in Taiwan in daytime environments as well as nighttime environments. Since there is currently no data set of road signs in Taiwan, this study is necessary to create a data set of road signs in Taiwan. The YOLO model is utilized in this work to design road signs in Taiwan for mark detection. The techniques of Contrast Stretching (CS), Histogram Equalization (HE), and Contrast Limited Adaptive Histogram Equalization (CLAHE) are evaluated in a nighttime setting and compared to the original image captured at night. The experimental results show that the best model during the day is YOLO V4 (no flip), the test set mAP is 86.77%, the Precision is 82%, the Recall is 87%, the F1-score is 84%, and the IoU is 63.92%. At night, the CLAHE image method works best in the YOLOv5x model, with a mAP of 86.40%. And YOLOv5 can be used in mobile devices or embedded devices, so this study recommends using CLAHE’s YOLOv5x as the best model at night and used to improve the effect of road sign detection at night.