Jeonghwan Gwak

Prof. Dr. Jeonghwan Gwak

Department of Software, Korea National University of Transportation, Chungju 27469, Republic of Korea
orcid

Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

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

Representative Publications

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22 March 2021 in Sensors
Verified
Journal Article
Open access
PDF file
Jaeyong KangJaeyong Kang
Jaeyong Kang
Zahid UllahZahid Ullah
Zahid Ullah
JGJeonghwan Gwak
Jeonghwan Gwak
Brain tumor classification plays an important role in clinical diagnosis and effective treatment. In this work, we propose a method for brain tumor classification using an ensemble of deep features and machine learning classifiers. In our proposed framework, we adopt the concept of transfer learning and uses several pre-trained deep convolutional neural networks to extract deep features from brain magnetic resonance (MR) images. The extracted deep features are then evaluated by several machine learning classifiers. The top three deep features which perform well on several machine learning classifiers are selected and concatenated as an ensemble of deep features which is then fed into several machine learning classifiers to predict the final output. To evaluate the different kinds of pre-trained models as a deep feature extractor, machine learning classifiers, and the effectiveness of an ensemble of deep feature for brain tumor classification, we use three different brain magnetic resonance imaging (MRI) datasets that are openly accessible from the web. Experimental results demonstrate that an ensemble of deep features can help improving performance significantly, and in most cases, support vector machine (SVM) with radial basis function (RBF) kernel outperforms other machine learning classifiers, especially for large datasets.

21 February 2019 in IEEE Access
Verified
Journal Article
Open access
Jaeyong KangJaeyong Kang
Jaeyong Kang
JGJeonghwan Gwak
Jeonghwan Gwak
Colorectal cancer is the second most frequently diagnosed cancer in women and the third most frequently diagnosed cancer in men. At least 80%-95% of the colorectal cancers are evolved from intestinal polyps. Although colonoscopy is regarded as the most effective method for screening and diagnosis, the success of the procedure is highly dependent on the level of hand-eye coordination and the operator skills. Thus, we are primarily motivated by the need for obtaining an early and accurate diagnosis of polyps in the colonoscopy images. In this paper, we employed the powerful object detection neural network “Mask R-CNN” to identify and segment polyps in the colonoscopy images. Also, we proposed an ensemble method to combine the two Mask R-CNN models with different backbone structures (ResNet50 and ResNet101) to enhance the performance. Mask R-CNNs in our model were first trained on COCO dataset, and then finely tuned using intestinal polyp dataset since a large number of annotated colonoscopy images are not easily accessible. In order to evaluate our proposed model, we used three open intestinal polyp datasets, CVC-ClinicDB, ETIS-Larib, and CVC-ColonDB. Our results show that our transfer learning-based ensemble model significantly outperforms state-of-the-art methods.

1 January 2017 in Journal of Healthcare Engineering
Verified
Journal Article
Open access
PDF file
RLRamesh Kumar Lama
Ramesh Kumar Lama
JGJeonghwan Gwak
Jeonghwan Gwak
JPJeong-Seon Park
Jeong-Seon Park
Sang-Woong LeeSang-Woong Lee
Sang-Woong Lee
Alzheimer’s disease (AD) is a progressive, neurodegenerative brain disorder that attacks neurotransmitters, brain cells, and nerves, affecting brain functions, memory, and behaviors and then finally causing dementia on elderly people. Despite its significance, there is currently no cure for it. However, there are medicines available on prescription that can help delay the progress of the condition. Thus, early diagnosis of AD is essential for patient care and relevant researches. Major challenges in proper diagnosis of AD using existing classification schemes are the availability of a smaller number of training samples and the larger number of possible feature representations. In this paper, we present and compare AD diagnosis approaches using structural magnetic resonance (sMR) images to discriminate AD, mild cognitive impairment (MCI), and healthy control (HC) subjects using a support vector machine (SVM), an import vector machine (IVM), and a regularized extreme learning machine (RELM). The greedy score-based feature selection technique is employed to select important feature vectors. In addition, a kernel-based discriminative approach is adopted to deal with complex data distributions. We compare the performance of these classifiers for volumetric sMR image data from Alzheimer’s disease neuroimaging initiative (ADNI) datasets. Experiments on the ADNI datasets showed that RELM with the feature selection approach can significantly improve classification accuracy of AD from MCI and HC subjects.

2 October 2019 in Applied Sciences
Verified
Journal Article
Open access
PDF file
THThi Kieu Khanh Ho
Thi Kieu Khanh Ho
JGJeonghwan Gwak
Jeonghwan Gwak
The accurate localization and classification of lung abnormalities from radiological images are important for clinical diagnosis and treatment strategies. However, multilabel classification, wherein medical images are interpreted to point out multiple existing or suspected pathologies, presents practical constraints. Building a highly precise classification model typically requires a huge number of images manually annotated with labels and finding masks that are expensive to acquire in practice. To address this intrinsically weakly supervised learning problem, we present the integration of different features extracted from shallow handcrafted techniques and a pretrained deep CNN model. The model consists of two main approaches: a localization approach that concentrates adaptively on the pathologically abnormal regions utilizing pretrained DenseNet-121 and a classification approach that integrates four types of local and deep features extracted respectively from SIFT, GIST, LBP, and HOG, and convolutional CNN features. We demonstrate that our approaches efficiently leverage interdependencies among target annotations and establish the state of the art classification results of 14 thoracic diseases in comparison with current reference baselines on the publicly available ChestX-ray14 dataset.

7 April 2021 in Electronics
Verified
Journal Article
Open access
PDF file
- Imran- Imran
- Imran
ZGzeba ghaffar
zeba ghaffar
AAAbdullah Alshahrani
Abdullah Alshahrani
MFMuhammad Fayaz
Muhammad Fayaz
Ahmed Mohammed AlghamdiAhmed Mohammed Alghamdi
Ahmed Mohammed Alghamdi
JGJeonghwan Gwak
Jeonghwan Gwak
In recent years, rapid development has been made to the Internet of Things communication technologies, infrastructure, and physical resources management. These developments and research trends address challenges such as heterogeneous communication, quality of service requirements, unpredictable network conditions, and a massive influx of data. One major contribution to the research world is in the form of software-defined networking applications, which aim to deploy rule-based management to control and add intelligence to the network using high-level policies to have integral control of the network without knowing issues related to low-level configurations. Machine learning techniques coupled with software-defined networking can make the networking decision more intelligent and robust. The Internet of Things application has recently adopted virtualization of resources and network control with software-defined networking policies to make the traffic more controlled and maintainable. However, the requirements of software-defined networking and the Internet of Things must be aligned to make the adaptations possible. This paper aims to discuss the possible ways to make software-defined networking enabled Internet of Things application and discusses the challenges solved using the Internet of Things leveraging the software-defined network. We provide a topical survey of the application and impact of software-defined networking on the Internet of things networks. We also study the impact of machine learning techniques applied to software-defined networking and its application perspective. The study is carried out from the different perspectives of software-based Internet of Things networks, including wide-area networks, edge networks, and access networks. Machine learning techniques are presented from the perspective of network resources management, security, classification of traffic, quality of experience, and quality of service prediction. Finally, we discuss challenges and issues in adopting machine learning and software-defined networking for the Internet of Things applications.

8 April 2019 in Journal of Biophotonics
Verified
Journal Article
Closed access
PDF file
TNThien Nguyen
Thien Nguyen
MKMinhee Kim
Minhee Kim
JGJeonghwan Gwak
Jeonghwan Gwak
JLJang Jae Lee
Jang Jae Lee
KCKyu Yeong Choi
Kyu Yeong Choi
Jae Gwan KimJae Gwan Kim
Jae Gwan Kim