Seunghyun Kim

Ms. Seunghyun Kim


Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

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

Representative Publications

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17 July 2024 in Sensors
Verified
Journal Article
Open access
PDF file
SJSeungmin Jeong
Seungmin Jeong
SKSeunghyun Kim
Seunghyun Kim
ELEui Chul Lee
Eui Chul Lee
HKHan Joon Kim
Han Joon Kim
Patients suffering from Parkinson’s disease suffer from voice impairment. In this study, we introduce models to classify normal and Parkinson’s patients using their speech. We used an AST (audio spectrogram transformer), a transformer-based speech classification model that has recently outperformed CNN-based models in many fields, and a CNN-based PSLA (pretraining, sampling, labeling, and aggregation), a high-performance model in the existing speech classification field, for the study. This study compares and analyzes the models from both quantitative and qualitative perspectives. First, qualitatively, PSLA outperformed AST by more than 4% in accuracy, and the AUC was also higher, with 94.16% for AST and 97.43% for PSLA. Furthermore, we qualitatively evaluated the ability of the models to capture the acoustic features of Parkinson’s through various CAM (class activation map)-based XAI (eXplainable AI) models such as GradCAM and EigenCAM. Based on PSLA, we found that the model focuses well on the muffled frequency band of Parkinson’s speech, and the heatmap analysis of false positives and false negatives shows that the speech features are also visually represented when the model actually makes incorrect predictions. The contribution of this paper is that we not only found a suitable model for diagnosing Parkinson’s through speech using two different types of models but also validated the predictions of the model in practice.

24 May 2023 in Applied Sciences
Verified
Journal Article
Open access
PDF file
KLKunyoung Lee
Kunyoung Lee
SKSeunghyun Kim
Seunghyun Kim
ELEui Chul Lee
Eui Chul Lee
As emotional states are diverse, simply classifying them through discrete facial expressions has its limitations. Therefore, to create a facial expression recognition system for practical applications, not only must facial expressions be classified, emotional changes must be measured as continuous values. Based on the knowledge distillation structure and the teacher-bounded loss function, we propose a method to maximize the synergistic effect of jointly learning discrete and continuous emotional states of eight expression classes, valences, and arousal levels. The proposed knowledge distillation model uses Emonet, a state-of-the-art continuous estimation method, as the teacher model, and uses a lightweight network as the student model. It was confirmed that performance degradation can be minimized even though student models have multiply-accumulate operations of approximately 3.9 G and 0.3 G when using EfficientFormer and MobileNetV2, respectively, which is much less than the amount of computation required by the teacher model (16.99 G). Together with the significant improvements in computational efficiency (by 4.35 and 56.63 times using EfficientFormer and MobileNetV2, respectively), the decreases in facial expression classification accuracy were approximately 1.35% and 1.64%, respectively. Therefore, the proposed method is optimized for application-level interaction systems in terms of both the amount of computation required and the accuracy.

5 April 2024 in Electronics
Verified
Journal Article
Open access
PDF file
SKSeunghyun Kim
Seunghyun Kim
HSHyunSoo Seo
HyunSoo Seo
ELEui Chul Lee
Eui Chul Lee
In the realm of manufacturing processes, equipment failures can result in substantial financial losses and pose significant safety hazards. Consequently, prior research has primarily been focused on preemptively detecting anomalies before they manifest. However, within industrial contexts, the precise interpretation of predictive outcomes holds paramount importance. This has spurred the development of research in Explainable Artificial Intelligence (XAI) to elucidate the inner workings of predictive models. Previous studies have endeavored to furnish explanations for anomaly detection within these models. Nonetheless, rectifying these anomalies typically necessitates the expertise of seasoned professionals. Therefore, our study extends beyond the mere identification of anomaly causes; we also ascertain the specific adjustments required to normalize these deviations. In this paper, we present novel research avenues and introduce three methods to tackle this challenge. Each method has exhibited a remarkable success rate in normalizing detected errors, scoring 97.30%, 97.30%, and 100.0%, respectively. This research not only contributes to the field of anomaly detection but also amplifies the practical applicability of these models in industrial environments. It furnishes actionable insights for error correction, thereby enhancing their utility and efficacy in real-world scenarios.

16 April 2022 in Sensors
Verified
Journal Article
Open access
PDF file
SKSeunghyun Kim
Seunghyun Kim
SJSu-Min Jeon
Su-Min Jeon
ELEui Chul Lee
Eui Chul Lee
Spoofing attacks in face recognition systems are easy because faces are always exposed. Various remote photoplethysmography-based methods to detect face spoofing have been developed. However, they are vulnerable to replay attacks. In this study, we propose a remote photoplethysmography-based face recognition spoofing detection method that minimizes the susceptibility to certain database dependencies and high-quality replay attacks without additional devices. The proposed method has the following advantages. First, because only an RGB camera is used to detect spoofing attacks, the proposed method is highly usable in various mobile environments. Second, solutions are incorporated in the method to obviate new attack scenarios that have not been previously dealt with. In this study, we propose a remote photoplethysmography-based face recognition spoofing detection method that improves susceptibility to certain database dependencies and high-quality replay attack, which are the limitations of previous methods without additional devices. In the experiment, we also verified the cut-off attack scenario in the jaw and cheek area where the proposed method can be counter-attacked. By using the time series feature and the frequency feature of the remote photoplethysmography signal, it was confirmed that the accuracy of spoof detection was 99.7424%.

31 December 2024 in IEEE Transactions on Intelligent Transportation Systems
Verified
Journal Article
Closed access
KLKunyoung Lee
Kunyoung Lee
HSHyunsoo Seo
Hyunsoo Seo
SKSeunghyun Kim
Seunghyun Kim
BAByeong Seon An
Byeong Seon An
SPShinwi Park
Shinwi Park
ELEui Chul Lee
Eui Chul Lee
Remote photoplethysmography (rPPG) is a method for monitoring pulse signal by utilizing a camera sensor to capture a facial video including variations in blood flow beneath the skin. Recently, rPPG advancements have enabled the measurement of an individual’s heart rate with a Root Mean Square Error (RMSE) of approximately 1.0 in controlled indoor environments. However, when applied in car dataset including driving environments, the RMSE of rPPG measurements significantly increases to over 9.07. This limitation, caused by motion-related artifacts and fluctuations in ambient illumination, becomes particularly noticeable while driving, resulting in a Percentage of Time that Error is less than 6 beats per minute (PTE6) of up to 65.1%. To address these limitations, we focus on the assessment of rPPG noise, with an emphasis on evaluating noise components within facial video and quantifying quality of the rPPG measurement. In this paper, we propose a deep learning framework that infers rPPG signal and quality based on video vision transformer. the proposed method demonstrates that the top 10% quality measurements yield PTE6 of 91.98% and 99.59% in driving and garage environments, respectively. Additionally, we introduce a quality-based rPPG compensation method that improves accuracy in driving environments by predicting rPPG quality based on noise assessment. This compensation method demonstrates superior accuracy compared to the current state-of-the-art, achieving a PTE6 of 68.24% in driving scenarios.

6 September 2023 in Electronics
Verified
Journal Article
Open access
PDF file
SKSeunghyun Kim
Seunghyun Kim
HLHyeji Lim
Hyeji Lim
BJBaek Junho
Baek Junho
ELEui Chul Lee
Eui Chul Lee
Blood pressure is a fundamental health metric widely employed to predict cardiac diseases and monitor overall well-being. However, conventional blood pressure measurement methods, such as the cuff method, necessitate additional equipment and can be inconvenient for regular use. This study aimed to develop a novel approach to blood pressure measurement using only an RGB camera, which promises enhanced convenience and accuracy. We employed the U-Net Basic generative model to achieve our objectives. Through rigorous experimentation and data analysis, our approach demonstrated promising results, attaining BHS (British Hypertension Society) baseline performance with grade A accuracy for diastolic blood pressure (DBP) and grade C accuracy for systolic blood pressure (SBP). The mean absolute error (MAE) achieved for DBP was 4.43 mmHg, and for SBP, it was 6.9 mmHg. Our findings indicate that blood pressure measurement using an RGB camera shows significant potential and may be utilized as an alternative or supplementary method for blood pressure monitoring. The convenience of using a commonly available RGB camera without additional specialized equipment can empower individuals to track their blood pressure regularly and proactively predict potential heart-related issues.