Publications by authors named "Kwangtaek Kim"

12 Publications

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Skin tactile surface restoration using deep learning from a mobile image: An application for virtual skincare.

Skin Res Technol 2021 Mar 2. Epub 2021 Mar 2.

Haptic Engineering Research Laboratory, Department of Information and Telecommunication Engineering, Incheon National University, Incheon, Republic of Korea.

Background: For virtual skincare using a touch feedback interface, reconstructing a 3D skin tactile surface from a mobile skin image is imperative for a dermatologist to palpate the skin surface that presents tactile characteristics of the subcutaneous tissues. However, the precise tactile reconstruction from a single view image is a challenging research problem due to varying illumination conditions.

Methods: In this study, a deep learning-based tactile reconstruction scheme is proposed to restore tactile properties from light distortion and reconstruct the 3D tactile surface from a mobile skin image. Our method consists of light distortion removal using deep learning, cGAN, and 3D tactile surface generation based on image gradients.

Results: The proposed method was tested by conducting two evaluation experiments in terms of removing light distortion and reconstructing 3D skin tactile surface in comparison with other well-known methods. The results demonstrated that our method outperforms existing other methods in both illumination-free image restoration and 3D surface reconstruction.

Conclusion: The proposed method is a promising approach in that tactile property distorted by illuminations can be completely restored using deep learning with a smaller training set and the precise reconstruction of 3D skin tactile surface can be achieved to be ready for a remotely touchable interface for virtual skincare applications.
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http://dx.doi.org/10.1111/srt.13009DOI Listing
March 2021

Anaesthetists' attitudes towards attending the funerals of their patients: A cross-sectional study among Australian and New Zealand anaesthetists.

PLoS One 2020 5;15(11):e0239996. Epub 2020 Nov 5.

Department of Anaesthesia, Austin Hospital, Heidelberg, Victoria, Australia.

A patient's death can pose significant stress on the family and the treating anaesthetist. Anaesthetists' attitudes about the benefits of and barriers to attending a patient's funeral are unknown. Therefore, we performed a prospective, cross-sectional study to ascertain the frequency of anaesthetists' attendance at a patient's funeral and their perceptions about the benefits and barriers. The primary aim was to investigate the attitudes of anaesthetists towards attending the funeral of a patient. The secondary aims were to examine the perceived benefits of and barriers to attending the funeral and to explore the rate of bonds being formed between anaesthetists, patients and families. Of the 424 anaesthetists who completed the survey (response rate 21.2%), 25 (5.9%) had attended a patient's funeral. Of the participants, 364 (85.9%) rarely formed special bonds with patients or their families; 233 (55%) believed that forming a special bond would increase the likelihood of their attendance. Showing respect to patients or their families was the most commonly perceived benefit of attending a funeral. Participants found expression of personal grief and caring for the patient at the end-of-life and beyond beneficial to themselves and the family. Fear of their attendance being misinterpreted or perceived as not warranted by the family as well as time restraints were barriers for their attendance. Most anaesthetists had never attended a patient's funeral. Few anaesthetists form close relationships with patients or their families. Respect, expression of grief and caring beyond life were perceived benefits of attendance. Families misinterpreting the purpose of attendance or not expecting their attendance and time restraints were commonly perceived barriers. Trial registration: ACTRN 12618000503224.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239996PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7643987PMC
December 2020

Bereavement practices employed by hospitals and medical practitioners toward attending funeral of patients: A systematic review.

Medicine (Baltimore) 2019 Sep;98(36):e16692

Department of Anaesthesia, Austin Health.

Objectives: To ascertain bereavement practices offered by hospitals and medical practitioners (MPs), factors that influence the likelihood of MPs' involvement in funeral attendance, the benefits and barriers to attendance to a patient's funeral as perceived by MPs and the rate of attendance to patients' funeral by MPs.

Design: MEDLINE (Ovid), Embase, PubMed, and Google Scholar were searched with a systematic search structure for randomized controlled trials, comparative observational studies, case series, cross-sectional studies, editorials, and letters. The search was limited to English only. The study was registered with Prospero (Registration Number: CRD42018095368).

Results: A total of 381 articles were identified with 46 articles meeting the inclusion criteria. Of the 46, 16 were editorials and 12 were letters. Eighteen were cross-sectional studies conducted in the United States, Canada, Australia, Israel, and Ireland. Year of publication ranged from 1990 to 2017. Of these, 12 were quantitative, 3 were qualitative, and 3 were mixed-method studies. Two of the cross-sectional studies involved family members of deceased patients while others involved MPs. Bereavement practices offered by hospitals included memorial services, letters, and services provided by bereavement coordinators. Bereavement practices employed by MPs included answering or making phone calls, attending family meetings, and sending condolence letters. MPs' attendance at a patient's funeral was influenced by MPs' gender, age years of experience the medical specialty. Perceived benefits of MPs' attendance at a patient's funeral included providing support to the family, extending the professional relationship, illustrating respect to the patient and the family, resolving guilt and personal growth. Barriers to the attendance included a lack of time, blurring of professional boundaries, personal discomfort with death, emotional arousal, and discouragement by colleagues. General practice had an attendance rate of 71%. Attendance rates for palliative care, oncology, and psychiatrists ranged from 63% to 81%, 7.1% to 67%, and 15% to 67%, respectively. Intensivists had an attendance rate of 22%.

Conclusion: Several bereavement practices are provided by hospitals and MPs. Funeral attendance is an uncommon bereavement practice. MPs' attitudes toward attending a patient's funeral are understudied in many specialties. Patient factors that influence MPs' participation in bereavement practices are poorly understood.
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http://dx.doi.org/10.1097/MD.0000000000016692DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6739025PMC
September 2019

Accurate depth estimation of skin surface using a light-field camera toward dynamic haptic palpation.

Skin Res Technol 2019 Jul 9;25(4):469-481. Epub 2019 Jan 9.

Haptic Engineering Research Laboratory, Department of Information and Telecommunication Engineering, Incheon National University, Incheon, Korea.

Background: Haptic skin palpation with three-dimensional skin surface reconstruction from in vivo skin images in order to acquire both tactile and visual information has been receiving much attention. However, the depth estimation of skin surface, using a light field camera that creates multiple images with a micro-lens array, is a difficult problem due to low-resolution images resulting in erroneous disparity matching.

Methods: Multiple low-resolution images decoded from a light field camera have limitations to accurate 3D surface reconstruction needed for haptic palpation. To overcome this, a deep learning method, Generative Adversarial Networks, was employed to generate super-resolved skin images that preserve surface detail without blurring, and then, accurate skin depth was estimated by taking multiple subsequent steps including lens distortion correction, sub-pixel shifted image generation using phase shift theorem, cost-volume building, multi-label optimization, and hole filling and refinement, which is a new approach for 3D skin surface reconstruction.

Results: Experimental results of the deep-learning-based super-resolution method demonstrated that the textural detail (wrinkles) of super-resolved skin images is well preserved, unlike other super-resolution methods. In addition, the depth maps computed with our proposed algorithm verify that our method can produce more accurate and robust results compared to other state-of-the-art depth map computation methods.

Conclusion: Herein, we first proposed depth map estimation of skin surfaces using a light field camera and subsequently tested it with several skin images. The experimental results established the superiority of the proposed scheme.
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http://dx.doi.org/10.1111/srt.12675DOI Listing
July 2019

Gradient-based 3D skin roughness rendering from an in-vivo skin image for dynamic haptic palpation.

Skin Res Technol 2019 May 3;25(3):305-317. Epub 2019 Jan 3.

Department of Information & Telecommunication Engineering, Incheon National University, Incheon, Korea.

Background/purpose: Many studies have revealed the importance of palpation for dermatologists; however, palpation is not always possible due to the risk of secondary infections or the risk of damaging the affected area. Thus, haptic rendering for indirect palpation using in-vivo skin images, which will enable to examine a real three-dimensional (3D) skin sample by virtual touch without directly palpating the infected skin area, could be a useful technology in dermatology.

Methods: We propose a new method of accurate 3D skin surface reconstruction using simple gradients from a single skin image for accurate 3D roughness rendering with a haptic device. Our approach takes advantage of bilateral filtering to preserve skin roughness and image gradients in order to generate a 3D skin surface (polygonal meshes) while preserving skin wrinkles and rough surface textures.

Results: Our method was evaluated using two experiments. The accuracy was tested with six 3D ground-truth surfaces and four clinical skin images (acne, miliaria, sweet syndrome, and herpes simplex). For objective evaluation, a well-known 3D roughness estimation method and the Hausdorff distance were adopted to compute errors. All results showed that the accuracy of our method is superior to that of the two existing methods.

Conclusion: Haptic roughness rendering for skin palpation examination requires efficient and accurate 3D surface reconstruction. In this study, we developed a new method that can be used to reconstruct a 3D skin surface accurately while preserving roughness through the use of a single skin image.
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http://dx.doi.org/10.1111/srt.12650DOI Listing
May 2019

Analysis of resistance-associated gene expression in docetaxel-resistant prostate cancer cells.

Oncol Lett 2017 Sep 8;14(3):3011-3018. Epub 2017 Jul 8.

Department of Urology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 110-744, Republic of Korea.

Docetaxel-based chemotherapy is the standard treatment for metastatic castration-resistant prostate cancer (CRPC). However, a number of patients with metastatic CRPC are refractory to docetaxel or develop docetaxel resistance. The underlying molecular mechanisms of docetaxel resistance remain unclear, which is a significant burden to the management of metastatic prostate cancer. In the present study, the differential gene expression between docetaxel-sensitive (PC3) and docetaxel-resistant (PC3DR2) prostate cancer cells was identified using DNA microarrays, western blot analysis and reverse transcription-quantitative polymerase chain reaction. Of the genes implicated in cancer-associated pathways, insulin-like growth factor 1 receptor, DBF4 homolog, sterile α motif and leucine zipper-containing kinase AZK, Patched 1, serpin peptidase inhibitor, clade E, member 1 and breast cancer 2 (BRCA2) were >3-fold upregulated in PC3DR2 cells compared with PC3 cells. BRCA2 knockdown with small interfering RNA decreased the docetaxel resistance of PC3DR2 cells. These results suggest that BRCA2 serves an important role in the docetaxel resistance of prostate cancer cells. In addition, BRCA2 modulation may be a strategy to partially reverse docetaxel resistance in prostate cancer.
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http://dx.doi.org/10.3892/ol.2017.6541DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5588173PMC
September 2017

Image-based haptic roughness estimation and rendering for haptic palpation from in vivo skin image.

Authors:
Kwangtaek Kim

Med Biol Eng Comput 2018 Mar 8;56(3):413-420. Epub 2017 Aug 8.

Department of Information and Telecommunication Engineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012, South Korea.

Despite the advancement of measuring technologies, there was a need for palpation by hands to be able to better diagnose skin diseases and to learn about the tactile properties of in vivo skin surface. However, directly touching in vivo skin surface can cause secondary infections or damages. Therefore, a technology providing infection- and damage-free skin palpations and precise haptic skin roughness rendering is needed. A multidimensional (2D and 3D) rendering system was developed for multimodal (visual and haptic) rendering that can run with any given in vivo input skin images. For haptic rendering, a commercial haptic device with 3 degrees of freedom (3DOF), Geomagic Touch X, was used. To improve haptic roughness rendering, a force shading algorithm that reduces force discontinuity on rough surface patches but preserves the original roughness values was implemented and applied. In addition, a new image-based roughness estimation method was introduced and the results were compared with haptic roughness results to verify roughness rendering in the system. The developed haptic roughness rendering system will help to diagnose abnormalities on in vivo skin surfaces by virtual haptic palpation with no concern about secondary infections or damages (caused by touch interactions) especially in case of psoriasis, atopic dermatitis, or aging, which results in significant changes of skin roughness. Besides, the system can also be a good tool to examine skin condition changes before and after the use of skin care products (cosmetics). In addition, the proposed 2D skin roughness estimation method can be applied for mobile applications to provide an online roughness estimation tool with a simple phone camera.
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http://dx.doi.org/10.1007/s11517-017-1700-4DOI Listing
March 2018

Depth camera-based 3D hand gesture controls with immersive tactile feedback for natural mid-air gesture interactions.

Sensors (Basel) 2015 Jan 8;15(1):1022-46. Epub 2015 Jan 8.

Department of Electrical and Electronic Engineering, Institute of BioMed-IT, Energy-IT and Smart-IT Technology (Best), Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea.

Vision-based hand gesture interactions are natural and intuitive when interacting with computers, since we naturally exploit gestures to communicate with other people. However, it is agreed that users suffer from discomfort and fatigue when using gesture-controlled interfaces, due to the lack of physical feedback. To solve the problem, we propose a novel complete solution of a hand gesture control system employing immersive tactile feedback to the user's hand. For this goal, we first developed a fast and accurate hand-tracking algorithm with a Kinect sensor using the proposed MLBP (modified local binary pattern) that can efficiently analyze 3D shapes in depth images. The superiority of our tracking method was verified in terms of tracking accuracy and speed by comparing with existing methods, Natural Interaction Technology for End-user (NITE), 3D Hand Tracker and CamShift. As the second step, a new tactile feedback technology with a piezoelectric actuator has been developed and integrated into the developed hand tracking algorithm, including the DTW (dynamic time warping) gesture recognition algorithm for a complete solution of an immersive gesture control system. The quantitative and qualitative evaluations of the integrated system were conducted with human subjects, and the results demonstrate that our gesture control with tactile feedback is a promising technology compared to a vision-based gesture control system that has typically no feedback for the user's gesture inputs. Our study provides researchers and designers with informative guidelines to develop more natural gesture control systems or immersive user interfaces with haptic feedback.
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http://dx.doi.org/10.3390/s150101022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4327062PMC
January 2015

Stereo camera based virtual cane system with identifiable distance tactile feedback for the blind.

Sensors (Basel) 2014 Jun 13;14(6):10412-31. Epub 2014 Jun 13.

Department of Electrical and Electronic Engineering, Institute of BioMed-IT, Energy-IT and Smart-ITTechnology (Best), Yonsei University, Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea.

In this paper, we propose a new haptic-assisted virtual cane system operated by a simple finger pointing gesture. The system is developed by two stages: development of visual information delivery assistant (VIDA) with a stereo camera and adding a tactile feedback interface with dual actuators for guidance and distance feedbacks. In the first stage, user's pointing finger is automatically detected using color and disparity data from stereo images and then a 3D pointing direction of the finger is estimated with its geometric and textural features. Finally, any object within the estimated pointing trajectory in 3D space is detected and the distance is then estimated in real time. For the second stage, identifiable tactile signals are designed through a series of identification experiments, and an identifiable tactile feedback interface is developed and integrated into the VIDA system. Our approach differs in that navigation guidance is provided by a simple finger pointing gesture and tactile distance feedbacks are perfectly identifiable to the blind.
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http://dx.doi.org/10.3390/s140610412DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4118356PMC
June 2014

A case of synchronous presentation of primary non-small cell lung carcinoma and pheochromocytoma.

Tuberc Respir Dis (Seoul) 2013 Apr 30;74(4):181-6. Epub 2013 Apr 30.

Department of Internal Medicine, Hallym University College of Medicine, Seoul, Korea.

We report a rare synchronous presentation of primary lung cancer and adrenal pheochromocytoma. A 59-year-old woman was diagnosed with right upper lobe non-small cell lung carcinoma measuring 2.8 cm and a right adrenal gland mass measuring 3.5 cm, which displayed increased metabolic activity on (18)F-fluorodeoxyglucose positron emission tomography-computed tomography. The adrenal lesion was revealed to be asymptomatic. The patient underwent right adrenalectomy and histological examination revealed a pheochromocytoma. Ten days later, right upper lobectomy was performed for lung cancer. This case indicates that incidental adrenal lesions found in cases of resectable primary lung cancer should be investigated.
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http://dx.doi.org/10.4046/trd.2013.74.4.181DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3651929PMC
April 2013

Visuohaptic discrimination of 3D gross shape.

Seeing Perceiving 2012 27;25(3-4):351-64. Epub 2012 Mar 27.

Haptic Interface Research Lab, School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA.

Human sensitivity to 3D gross shape changes was measured for the visual and haptic sensory channels. Three volume-invariant affine transformations were defined: compressing, shearing and stretching. Participants discriminated a reference 3D object (cube or sphere) from its deformed shape under three experimental conditions: visual only (on a computer monitor), haptic only (through a point-contact force-feedback device) and visuohaptic simulations. The results indicate that vision is more sensitive to gross shape changes than point-based touch, and that vision dominated in the visuohaptic condition. In the haptic alone condition, thresholds were higher for shearing and stretching than for compressing. Thresholds were otherwise similar for the three transformations in the vision only or visuohaptic conditions. These trends were similar for the two shapes tested. A second experiment, conducted under similar conditions but preventing participants from manipulating object orientations, verified that the main conclusion of our research still holds when visual inspection can rely only on a single perspective view of the object. Our earlier studies on 3D visuohaptic watermarking showed that the haptic channel is more sensitive to surface texture and roughness changes than vision. The thresholds from the present and our earlier studies can potentially be used as the upper limits for selecting watermark strengths in order to ensure watermark imperceptibility in a 3D visuohaptic watermarking system.
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http://dx.doi.org/10.1163/187847612X629937DOI Listing
September 2012

A Frequency-Domain Analysis of Haptic Gratings.

IEEE Trans Haptics 2010 Jan-Mar;3(1):3-14. Epub 2009 Aug 21.

The detectability and discriminability of virtual haptic gratings were analyzed in the frequency domain. Detection (Exp. 1) and discrimination (Exp. 2) thresholds for virtual haptic gratings were estimated using a force-feedback device that simulated sinusoidal and square-wave gratings with spatial periods from 0.2 to 38.4 mm. The detection threshold results indicated that for spatial periods up to 6.4 mm (i.e., spatial frequencies >0.156 cycle/mm), the detectability of square-wave gratings could be predicted quantitatively from the detection thresholds of their corresponding fundamental components. The discrimination experiment confirmed that at higher spatial frequencies, the square-wave gratings were initially indistinguishable from the corresponding fundamental components until the third harmonics were detectable. At lower spatial frequencies, the third harmonic components of square-wave gratings had lower detection thresholds than the corresponding fundamental components. Therefore, the square-wave gratings were detectable as soon as the third harmonic components were detectable. Results from a third experiment where gratings consisting of two superimposed sinusoidal components were compared (Exp. 3) showed that people were insensitive to the relative phase between the two components. Our results have important implications for engineering applications, where complex haptic signals are transmitted at high update rates over networks with limited bandwidths.
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http://dx.doi.org/10.1109/TOH.2009.36DOI Listing
August 2017