Publications by authors named "Jonggi Hong"

This paper proposes a retinal prosthesis edge detection (RPED) algorithm that can achieve high visual acuity and low power. Retinal prostheses have been used to stimulate retinal tissue by injecting charge via an electrode array, thereby artificially restoring the vision of visually impaired patients. The retinal prosthetic chip, which generates biphasic current pulses, should be located in the foveal area measuring 5 mm × 5 mm.

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Article Synopsis
  • Teachable object recognizers help blind individuals with object recognition, but rely on visual inspection for training, which poses accessibility issues.
  • Researchers developed real-time data descriptors that assess photo quality and content for training an assistive iOS app, MYCam.
  • A study with 12 blind participants showed that while the app was user-friendly and improved training set quality, some users found the training process tedious, highlighting the need to balance information overload with user efficiency.
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In this study, a pulse frequency modulation (PFM)-based stimulator is proposed for use in biomedical implantable devices. Conventionally, functional electrical stimulation (FES) techniques have been used to reinforce damaged nerves, such as retina tissue and brain tissue, by injecting a certain amount of charge into tissues. Although several design methods are present for implementing FES devices, an FES stimulator for retinal implants is difficult to realize because of the chip area, which needs to be inserted in a fovea, sized 5 mm x 5 mm, and power limitations to prevent the heat generation that causes tissue damage.

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Smartphone-based navigation apps allow blind and visually impaired (BVI) people to take images or videos to complete various tasks such as determining a user 's location, recognizing objects, and detecting obstacles. The quality of the images and videos significantly affects the performance of these systems, but manipulating a camera to capture clear images with proper framing is a challenging task for BVI users. This research explores the interactions between a camera and BVI users in assistive navigation systems through interviews with BVI participants.

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Researchers have adopted remote methods, such as online surveys and video conferencing, to overcome challenges in conducting in-person usability testing, such as participation, user representation, and safety. However, remote user evaluation on hardware testbeds is limited, especially for blind participants, as such methods restrict access to observations of user interactions. We employ smart glasses in usability testing with blind people and share our lessons from a case study conducted in blind participants' homes ( = 12), where the experimenter can access participants' activities via dual video conferencing: a third-person view via a laptop camera and a first-person view via smart glasses worn by the participant.

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In this study, we propose a low-area multi-channel controlled dielectric breakdown (CDB) system that simultaneously produces several nanopore sensors. Conventionally, solid-state nanopores are prepared by etching or drilling openings in a silicon nitride (SiNx) substrate, which is expensive and requires a long processing time. To address these challenges, a CDB technique was introduced and used to fabricate nanopore channels in SiNx membranes.

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Negative attitudes shape experiences with stigmatized conditions such as dementia, from affecting social relationships to influencing willingness to adopt technology. Consequently, attitudinal change has been identified as one lever to improve life for people with stigmatized conditions. Though recognized as a scaleable approach, social media has not been studied in terms of how it should best be designed or deployed to target attitudes and understanding of dementia.

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For people with visual impairments, photography is essential in identifying objects through remote sighted help and image recognition apps. This is especially the case for teachable object recognizers, where recognition models are trained on user's photos. Here, we propose real-time feedback for communicating the location of an object of interest in the camera frame.

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The Korea Basic Science Institute (KBSI) has been developing a heavy ion accelerator system to accelerate high current, multi-charge state ions produced by a 28 GHz superconducting electron cyclotron ion source. A beam analyzing system as a part of the low energy beam transport apparatus was developed to select charged particles with desirable charge states from the ion beams. The desired species of ion, which is generated and extracted from the ECR ion source including various ion particles, can be selected by 90° dipole electromagnet.

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The gas cluster ion beam (GCIB) and liquid metal ion beam have been studied in the context of ion beam usage for analytical equipment in applications such as X-ray photoelectron spectroscopy and secondary ion mass spectroscopy (SIMS). In particular, small ion sources are used for the secondary ion generation and ion etching. To set the context to this study, the SIMS project has been launched to develop ion-gun based analytical equipment for the Korea Basic Science Institute.

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The 28 GHz superconducting electron cyclotron resonance (ECR) ion source has been developed to produce a high current heavy ion for the linear accelerator at KBSI (Korea Basic Science Institute). The objective of this study is to generate fast neutrons with a proton target via a p(Li,n)Be reaction. The design and fabrication of the essential components of the ECR ion source, which include a superconducting magnet with a liquid helium re-condensed cryostat and a 10 kW high-power microwave, were completed.

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The installation of the 28 GHz electron cyclotron resonance ion source (ECRIS) ion implantation beamline was recently completed at the Korea Basic Science Institute. The apparatus contains a beam monitoring system and a sample holder for the ion implantation process. The new implantation system can function as a multipurpose tool since it can implant a variety of ions, ranging hydrogen to uranium, into different materials with precise control and with implantation areas as large as 1-10 mm(2).

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