Jiwon Ryu
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Jiwon Ryu has a total of 38 co-authors. Here are the top co-authors by number of shared publications:
- Ghiseok Kim
Department of Biosystems Engineering, Seoul National University, Seoul, Republic of Korea
5 shared publications - Chang-Hyup Lee
Department of Biosystems Engineering, Seoul National University, Seoul, Republic of Korea
4 shared publications - Sungjay Kim
Department of Biosystems Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
4 shared publications - Sang-Yeon Kim
Department of Biosystems Engineering, Seoul National University, Seoul, Republic of Korea
3 shared publications - Azfar Ismail
Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
2 shared publications - Suk-Ju Hong
Department of Biosystems and Biomaterials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea
2 shared publications
Latest Publications
- Open Access
- 5 September 2026
- Published by Elsevier in SSRN Electronic Journal
Temporal latent fusion for sequential 3D shape completion in on-plant Korean melon growth monitoring
Growers need to assess fruit growth and harvest timing, and monitoring individual fruit volume informs both. However, this remains challenging on the plant because leaves occlude the fruit and a single viewpoint reveals only part of its surface. Three-dimensional (3D) shape completion can recover fruit geometry, and thereby volume, from partial point clouds. Most methods treat each observation independently and ignore the temporal continuity of repeated visits to the same fruit, so the estimated volume trajectories become noisy and unstable. We present SCoRe (Sequential CoRe), which extends a single-frame DeepSDF-based encoder with temporal latent fusion. The fusion averages the shape code across visits, favoring the latest observation as gaps grow, and keeps that code from moving backward along a growth axis found in the data, since a healthy fruit does not shrink before harvest. It introduces no learned parameters and runs at inference time. We evaluate SCoRe on 2,513 RGB-D frames of Korean melon (Cucumis melo L. var. makuwa, 210 fruits) imaged across two seasons and three greenhouses, using post-harvest photogrammetric meshes as ground truth and caliper measurements as an intermediate-frame reference. Against an identical single-frame encoder, SCoRe reduces the last-frame volume root mean squared error (RMSE) from 87.4 to 50.6 mL, a 42% reduction, and raises F1 at 5 mm from 66.1% to 83.0%. It surpasses established single-frame shape completion baselines, with the largest gains under heavy occlusion, and remains robust under irregular revisit intervals, as repeated crop monitoring requires. Code, trained weights, and data are publicly available.
- 5 September 2026
- Published by Elsevier in SSRN Electronic Journal
Open AccessTemporal latent fusion for sequential 3D shape completion in on-plant Korean melon growth monitoring
Growers need to assess fruit growth and harvest timing, and monitoring individual fruit volume informs both. However, this remains challenging on the plant because leaves occlude the fruit and a single viewpoint reveals only part of its surface. Three-dimensional (3D) shape completion can recover fruit geometry, and thereby volume, from partial point clouds. Most methods treat each observation independently and ignore the temporal continuity of repeated visits to the same fruit, so the estimated volume trajectories become noisy and unstable. We present SCoRe (Sequential CoRe), which extends a single-frame DeepSDF-based encoder with temporal latent fusion. The fusion averages the shape code across visits, favoring the latest observation as gaps grow, and keeps that code from moving backward along a growth axis found in the data, since a healthy fruit does not shrink before harvest. It introduces no learned parameters and runs at inference time. We evaluate SCoRe on 2,513 RGB-D frames of Korean melon (Cucumis melo L. var. makuwa, 210 fruits) imaged across two seasons and three greenhouses, using post-harvest photogrammetric meshes as ground truth and caliper measurements as an intermediate-frame reference. Against an identical single-frame encoder, SCoRe reduces the last-frame volume root mean squared error (RMSE) from 87.4 to 50.6 mL, a 42% reduction, and raises F1 at 5 mm from 66.1% to 83.0%. It surpasses established single-frame shape completion baselines, with the largest gains under heavy occlusion, and remains robust under irregular revisit intervals, as repeated crop monitoring requires. Code, trained weights, and data are publicly available.
- Open Access
- 30 March 2026
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Access
- Vol. 14, 48842-48858
Automated External Quality Grading of Oriental Melons Using Diffusion-Enhanced Semantic Segmentation and Field Validation
The external quality of high-value crops like the Oriental melon (Cucumis melo L. var. makuwa) directly determines market value, yet conventional manual inspection suffers from subjectivity, labor intensity, and inconsistency. Unlike existing single-factor automated systems, this study developed an integrated sorting system that simultaneously and quantitatively evaluates morphology, color, and surface defects, addressing the critical gap in comprehensive external quality assessment. The proposed hybrid model integrates digital image processing for morphological and color analysis with a state-of-the-art semantic segmentation model for defect evaluation. To specifically address the severe data imbalance inherent in Oriental melon defect datasets, the framework incorporates a Denoising Diffusion Probabilistic Model for targeted data augmentation. This approach enabled the generation of high-fidelity images of rare critical defects (e.g., cracks, damage) even with sparse training data, significantly enhancing overall performance. The Mask2Former (Swin-T) model, fine-tuned with the augmented dataset, achieved a superior mDice score of 81.5. The fully integrated system demonstrated a final grading accuracy of 86.3-96.5% on a test set. Field deployment in a commercial sorting facility validated the system's robustness, achieving 85.4-99.0% grading accuracy on independently collected samples and processing speeds of 43 fps (14 samples/second), substantially exceeding typical facility requirements (4-5 samples/second). This research demonstrates the first comprehensive automated grading system for Oriental melons, establishing a transferable framework applicable to other high-value crops facing class imbalance and addressing labor shortage challenges in modern agriculture.
- 30 March 2026
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Access
- Vol. 14, 48842-48858
Open AccessAutomated External Quality Grading of Oriental Melons Using Diffusion-Enhanced Semantic Segmentation and Field Validation
The external quality of high-value crops like the Oriental melon (Cucumis melo L. var. makuwa) directly determines market value, yet conventional manual inspection suffers from subjectivity, labor intensity, and inconsistency. Unlike existing single-factor automated systems, this study developed an integrated sorting system that simultaneously and quantitatively evaluates morphology, color, and surface defects, addressing the critical gap in comprehensive external quality assessment. The proposed hybrid model integrates digital image processing for morphological and color analysis with a state-of-the-art semantic segmentation model for defect evaluation. To specifically address the severe data imbalance inherent in Oriental melon defect datasets, the framework incorporates a Denoising Diffusion Probabilistic Model for targeted data augmentation. This approach enabled the generation of high-fidelity images of rare critical defects (e.g., cracks, damage) even with sparse training data, significantly enhancing overall performance. The Mask2Former (Swin-T) model, fine-tuned with the augmented dataset, achieved a superior mDice score of 81.5. The fully integrated system demonstrated a final grading accuracy of 86.3-96.5% on a test set. Field deployment in a commercial sorting facility validated the system's robustness, achieving 85.4-99.0% grading accuracy on independently collected samples and processing speeds of 43 fps (14 samples/second), substantially exceeding typical facility requirements (4-5 samples/second). This research demonstrates the first comprehensive automated grading system for Oriental melons, establishing a transferable framework applicable to other high-value crops facing class imbalance and addressing labor shortage challenges in modern agriculture.
- Open Access
- 27 May 2025
- Published by MDPI AG in Agriculture
- Vol. 15 (11) , 1148
Advanced 3D Depth Imaging Techniques for Morphometric Analysis of Detected On-Tree Apples Based on AI Technology
This study developed non-destructive technology for predicting apple size to determine optimal harvest timing of field-grown apples. RGBD images were collected in field environments with fluctuating light conditions, and deep learning techniques were integrated to analyze morphometric parameters. After training various models, the EfficientDet D4 and Mask R-CNN ResNet101 models demonstrated the highest detection accuracy. Morphometric metrics were measured by linking boundary box information with 3D depth information to determine horizontal and vertical diameters. Without occlusion, mean absolute percentage error (MAPE) using boundary box-based methods was 6.201% and 5.164% for horizontal and vertical diameters, respectively, while mask-based methods achieved improved accuracy with MAPE of 5.667% and 4.921%. Volume and weight predictions showed MAPE of 7.183% and 6.571%, respectively. For partially occluded apples, amodal segmentation was applied to analyze morphometric parameters according to occlusion rates. While conventional models showed increasing MAPE with higher occlusion rates, the amodal segmentation-based model maintained consistent accuracy regardless of occlusion rate, demonstrating potential for automated harvest systems where fruits are frequently partially obscured by leaves and branches.
- 27 May 2025
- Published by MDPI AG in Agriculture
- Vol. 15 (11) , 1148
Open AccessAdvanced 3D Depth Imaging Techniques for Morphometric Analysis of Detected On-Tree Apples Based on AI Technology
This study developed non-destructive technology for predicting apple size to determine optimal harvest timing of field-grown apples. RGBD images were collected in field environments with fluctuating light conditions, and deep learning techniques were integrated to analyze morphometric parameters. After training various models, the EfficientDet D4 and Mask R-CNN ResNet101 models demonstrated the highest detection accuracy. Morphometric metrics were measured by linking boundary box information with 3D depth information to determine horizontal and vertical diameters. Without occlusion, mean absolute percentage error (MAPE) using boundary box-based methods was 6.201% and 5.164% for horizontal and vertical diameters, respectively, while mask-based methods achieved improved accuracy with MAPE of 5.667% and 4.921%. Volume and weight predictions showed MAPE of 7.183% and 6.571%, respectively. For partially occluded apples, amodal segmentation was applied to analyze morphometric parameters according to occlusion rates. While conventional models showed increasing MAPE with higher occlusion rates, the amodal segmentation-based model maintained consistent accuracy regardless of occlusion rate, demonstrating potential for automated harvest systems where fruits are frequently partially obscured by leaves and branches.
- 9 April 2024
- Published by Elsevier in Journal of Food Engineering
- Vol. 377
Nondestructive freshness evaluation of mackerel fish using Vis/NIR hyperspectral imaging and multivariate analysis
- 9 April 2024
- Published by Elsevier in Journal of Food Engineering
- Vol. 377
Nondestructive freshness evaluation of mackerel fish using Vis/NIR hyperspectral imaging and multivariate analysis
- Open Access
- 1 September 2023
- Published by Springer Nature in Food Science of Animal Resources
- Vol. 43 (5) , 840-858
Quality Evaluation of Mackerel Fillets Stored under Different Conditions by Hyperspectral Imaging Analysis
Food Science of Animal Resources (Food Sci. Anim. Resour.) is an international, peer-reviewed bimonthly journal publishing original research and reviews on basic and applied aspects of the use of animal resources including the meat, egg, dairy, and edible insect/worm products. Food Sci. Anim. Resour. is published and distributed by the Korean Society for Food Science of Animal Resources.
- 1 September 2023
- Published by Springer Nature in Food Science of Animal Resources
- Vol. 43 (5) , 840-858
Open AccessQuality Evaluation of Mackerel Fillets Stored under Different Conditions by Hyperspectral Imaging Analysis
Food Science of Animal Resources (Food Sci. Anim. Resour.) is an international, peer-reviewed bimonthly journal publishing original research and reviews on basic and applied aspects of the use of animal resources including the meat, egg, dairy, and edible insect/worm products. Food Sci. Anim. Resour. is published and distributed by the Korean Society for Food Science of Animal Resources.
- Open Access
- 21 April 2023
- Published by MDPI AG in Agriculture
- Vol. 13 (4) , 918
Classification of Fresh and Frozen-Thawed Beef Using a Hyperspectral Imaging Sensor and Machine Learning
The demand for safe and edible meat has led to the advancement of freeze-storage techniques, but falsely labeled thawed meat remains an issue. Many methods have been proposed for this purpose, but they all destroy the sample and can only be performed in the laboratory by skilled personnel. In this study, hyperspectral image data were used to construct a machine learning (ML) model to discriminate between freshly refrigerated, long-term refrigerated, and thawed beef meat samples. With four pre-processing methods, a total of five datasets were prepared to construct an ML model. The PLS-DA and SVM techniques were used to construct the models, and the performance was highest for the SVM model applying scatter correction and the RBF kernel function. These results suggest that it is possible to construct a prediction model to distinguish between fresh and non-fresh meat using the spectra obtained by purifying hyperspectral image data cubes, which can be a rapid and non-invasive method for routine analyses of the meat storage state.
- 21 April 2023
- Published by MDPI AG in Agriculture
- Vol. 13 (4) , 918
Open AccessClassification of Fresh and Frozen-Thawed Beef Using a Hyperspectral Imaging Sensor and Machine Learning
The demand for safe and edible meat has led to the advancement of freeze-storage techniques, but falsely labeled thawed meat remains an issue. Many methods have been proposed for this purpose, but they all destroy the sample and can only be performed in the laboratory by skilled personnel. In this study, hyperspectral image data were used to construct a machine learning (ML) model to discriminate between freshly refrigerated, long-term refrigerated, and thawed beef meat samples. With four pre-processing methods, a total of five datasets were prepared to construct an ML model. The PLS-DA and SVM techniques were used to construct the models, and the performance was highest for the SVM model applying scatter correction and the RBF kernel function. These results suggest that it is possible to construct a prediction model to distinguish between fresh and non-fresh meat using the spectra obtained by purifying hyperspectral image data cubes, which can be a rapid and non-invasive method for routine analyses of the meat storage state.
- Open Access
- 31 December 2021
- Published by The Korean Society of Nephrology in Kidney Research and Clinical Practice
- Vol. 40 (4) , 634-644
Renal outcomes of laparoscopic versus open surgery in patients with rectal cancer: a propensity score analysis
A laparoscopic approach is widely used in abdominal surgery. Although several studies have compared surgical and oncological outcomes between laparoscopic surgery (LS) and open surgery (OS) in rectal cancer patients, there have been few studies on postoperative renal outcomes. We conducted a retrospective cohort study involving 1,633 patients who underwent rectal cancer surgery between 2003 and 2017. Postoperative acute kidney injury (AKI) was diagnosed according to the serum creatinine criteria of the Kidney Disease: Improving Global Outcomes classification. Among the 1,633 patients, 1,072 (65.6%) underwent LS. After matching propensity scores, 395 patients were included in each group. The incidence of postoperative AKI in the LS group was significantly lower than in the OS group (9.9% vs. 15.9%; p = 0.01). Operation time, estimated blood loss, and incidence of transfusion in the LS group were significantly lower than those in the OS group. Cox proportional hazard models revealed that LS was associated with decreased risk of postoperative AKI (hazard ratio [HR], 0.599; 95% confidence interval [CI], 0.402–0.893; p = 0.01) and postoperative transfusion was associated with increased risk of AKI (HR, 2.495; 95% CI, 1.529–4.072; p < 0.001). In the subgroup analysis, the incidence of postoperative AKI in patients with middle or high rectal cancer who underwent LS was much lower than in those who underwent OS (HR, 0.373; 95% CI, 0.197–0.705; p = 0.002). This study showed that LS may have a favorable effect on the development of postoperative AKI in patients with rectal cancer.
- 31 December 2021
- Published by The Korean Society of Nephrology in Kidney Research and Clinical Practice
- Vol. 40 (4) , 634-644
Open AccessRenal outcomes of laparoscopic versus open surgery in patients with rectal cancer: a propensity score analysis
A laparoscopic approach is widely used in abdominal surgery. Although several studies have compared surgical and oncological outcomes between laparoscopic surgery (LS) and open surgery (OS) in rectal cancer patients, there have been few studies on postoperative renal outcomes. We conducted a retrospective cohort study involving 1,633 patients who underwent rectal cancer surgery between 2003 and 2017. Postoperative acute kidney injury (AKI) was diagnosed according to the serum creatinine criteria of the Kidney Disease: Improving Global Outcomes classification. Among the 1,633 patients, 1,072 (65.6%) underwent LS. After matching propensity scores, 395 patients were included in each group. The incidence of postoperative AKI in the LS group was significantly lower than in the OS group (9.9% vs. 15.9%; p = 0.01). Operation time, estimated blood loss, and incidence of transfusion in the LS group were significantly lower than those in the OS group. Cox proportional hazard models revealed that LS was associated with decreased risk of postoperative AKI (hazard ratio [HR], 0.599; 95% confidence interval [CI], 0.402–0.893; p = 0.01) and postoperative transfusion was associated with increased risk of AKI (HR, 2.495; 95% CI, 1.529–4.072; p < 0.001). In the subgroup analysis, the incidence of postoperative AKI in patients with middle or high rectal cancer who underwent LS was much lower than in those who underwent OS (HR, 0.373; 95% CI, 0.197–0.705; p = 0.002). This study showed that LS may have a favorable effect on the development of postoperative AKI in patients with rectal cancer.
- Open Access
Joint Angle Estimation of a Tendon-Driven Soft Wearable Robot through a Tension and Stroke Measurement
The size of a device and its adaptability to human properties are important factors in developing a wearable device. In wearable robot research, therefore, soft materials and tendon transmissions have been utilized to make robots compact and adaptable to the human body. However, when used for wearable robots, these methods sometimes cause uncertainties that originate from elongation of the soft material or from undefined human properties. In this research, to consider these uncertainties, we propose a data-driven method that identifies both kinematic and stiffness parameters using tension and wire stroke of the actuators. Through kinematic identification, a method is proposed to find the exact joint position as a function of the joint angle. Through stiffness identification, the relationship between the actuation force and the joint angle is obtained using Gaussian Process Regression (GPR). As a result, by applying the proposed method to a specific robot, the research outlined in this paper verifies how the proposed method can be used in wearable robot applications. This work examines a novel wearable robot named Exo-Index, which assists a human’s index finger through the use of three actuators. The proposed identification methods enable control of the wearable robot to result in appropriate postures for grasping objects of different shapes and sizes.
Open AccessJoint Angle Estimation of a Tendon-Driven Soft Wearable Robot through a Tension and Stroke Measurement
The size of a device and its adaptability to human properties are important factors in developing a wearable device. In wearable robot research, therefore, soft materials and tendon transmissions have been utilized to make robots compact and adaptable to the human body. However, when used for wearable robots, these methods sometimes cause uncertainties that originate from elongation of the soft material or from undefined human properties. In this research, to consider these uncertainties, we propose a data-driven method that identifies both kinematic and stiffness parameters using tension and wire stroke of the actuators. Through kinematic identification, a method is proposed to find the exact joint position as a function of the joint angle. Through stiffness identification, the relationship between the actuation force and the joint angle is obtained using Gaussian Process Regression (GPR). As a result, by applying the proposed method to a specific robot, the research outlined in this paper verifies how the proposed method can be used in wearable robot applications. This work examines a novel wearable robot named Exo-Index, which assists a human’s index finger through the use of three actuators. The proposed identification methods enable control of the wearable robot to result in appropriate postures for grasping objects of different shapes and sizes.