Byungrak Son

Daegu Gyeongbuk Institute of Science and Technology | DGIST · Division of Energy Technology

When the polymer electrolyte membrane fuel cell (PEMFC) is operated under low humidity, the proton conductivity decreases due to membrane dehydration, causing adverse effects on fuel cell performance. Introducing appropriate additives to the membrane and catalyst layer to prevent membrane degradation at low humidity brings significant performance i...

Nafion, a perfluorosulfonic acid (PFSA) polymer, is a vital electrolyte that extensively contributes to the commercialization of polymer electrolyte fuel cells (PEFCs). However, adopting Nafion in high-temperature (HT) PEFCs (HT-PEFCs) is still a great challenge. Herein, we present a potential additive (carbon nitride-gadolinium zirconium oxide (gC...

In this study, the proton conductivity enhancement mechanism of Nafion–silica sulfuric acid (SSA) composite membranes was studied using the vibrating tip technique of atomic force microscopy. The Nafion–SSA composite membranes showed enhanced proton conductivity and thermal and mechanical properties compared to those of pristine Nafion. Among the s...

A block copolymer composite membrane of sulfonated poly(arylene ether sulfone ketone) (SPESK) decorated with porous hygroscopic titanium oxide nanotubes (TNT) is designed and fabricated for low relative humidity (RH) operating polymer electrolyte fuel cells (PEFCs). The SPESK-TNT composite membrane in a PEFC operated at 100% RH, and 80 °C resulted...

Understanding the ionic channel network of proton exchange membranes that dictate fuel cell performance is crucial when developing proton exchange membrane fuel cells. However, it is difficult to characterize this network because of the complicated nanostructure and structure changes that depend on water uptake. Electrostatic force microscopy (EFM)...

Herein, NiCo2S4 supported on sulfur-doped carbon with multi-porous nanostructures are developed to achieve excellent bifunctional catalytic activities. We present a comprehensive study on the composite effect between NiCo2S4 and sulfur-doped carbon as a bifunctional catalyst for oxygen reduction reaction and oxygen evolution reactions. Further, the...

A proton exchange membrane fuel cell uses perfluorosulfonic acid polymers as a proton exchange membrane but exhibits poor performance and durability under dry operating condition. Herein, we develop a composite membrane by incorporating porous inorganic filler, Zr2Gd2O7 into a perfluorosulfonic acid, Nafion. Zr2Gd2O7 nanorods (ZrGdNR) are synthesiz...

Sulfonated silica, synthesized by using tetraethyl orthosilicate and chlorosulfuric acid through calcination, was used as a filler to create Nafion-SSA composite membranes for applying proton exchange membrane fuel cells under low relative humidity (RH)condition. High water uptake and ion exchange capacity values were observed, and the Nafion-SSA c...

Air‐breathing proton exchange membrane fuel cells (AB‐PEMFCs) have a great potential for commercialization owing to their simple mechanical configuration and low cost compared with traditional proton exchange membrane fuel cells (PEMFCs). However, AB‐PEMFCs perform worse than traditional PEMFCs owing to the omission of the humidifier and a poor air...

Unmanned aerial vehicles (UAVs) have gained significant attention in recent times due to their suitability for a wide variety of civil, military, and societal missions. Development of an unmanned amphibious vehicle integrating the features of a multi-rotor UAV and a hovercraft is the focus of the present study. Components and subsystems of the amph...

A phosphotungstic acid (PW) decorated graphene oxide (GO) is explored as a filler for sulfonated poly(arylene ether ketone) (SPAEK) block copolymer. The SPAEK/PW-mGO composite membrane shows higher proton conductivity than a pristine SPAEK membrane. At 80 °C under 25% relative humidity (RH) condition, the fuel cell configured with the SPAEK/PW-mGO...

The design of high performance oxygen reduction reaction (ORR) electrocatalysts play an important role in the commercialization of polymer electrolyte membrane fuel cells. The morphology, structure, and composition of the support material significantly affect the catalytic activity of the fuel cell catalyst. In this work, we report a systematic and...

The design of high performance oxygen reduction reaction (ORR) electrocatalysts play an important role in the commercialization of polymer electrolyte membrane fuel cells. The morphology, structure, and composition of the support material significantly affect the catalytic activity of the fuel cell catalyst. In this work, we report a systematic and...

1. Introduction – Transition metal oxides are considered to be promising as anode materials for sodium ion batteries (SIB) [1, 2]. Among them tin oxide has attracted attention because of its high theoretical capacity, however the capacity drops steadily in the subsequent cycles due to large volume change [3]. A novel solvoplasma technique to produc...

1. Introduction – Secondary Li ion batteries, regarded as the current benchmark for new battery technologies, are under extensive development throughout the world [1]. However, their requirement that organic electrolytes be used limits the rate capacity and specific power the cell can achieve and present several safety hazards and cost limitations...

A minimum balance of plant (BOP) is desired for an open-cathode high temperature polymer electrolyte membrane (HTPEM) fuel cell to ensure low parasitic losses and a compact design. The advantage of an open-cathode system is the elimination of the coolant plate and incorporation of a blower for oxidant and coolant supply, which reduces the overall s...

Proton exchange membrane fuel cells are a promising energy conversion device which can help to solve urgent environmental and economic problems. Among the various types of fuel cells, the air breathing proton exchange membrane fuel cell, which minimizes the balance of plant, has drawn a lot of attention due to its superior energy density. In this s...

Maintaining proper hydration in the proton exchange membrane (PEM) is a crucial issue for passive air breathing PEM (ABPEM) fuel cells. The inorganic filler Nafion composite membrane has great potential for replacing commercialized PEM for ABPEM. We synthesize sulfonated graphene and Nafion composite membrane by using functionalized graphene to enh...

Highly single-crystalline ruthenium dioxide (RuO2) nanoneedles were successfully grown on polycrystalline electrospun titanium dioxide (TiO2) nanofibers for the first time by a combination of thermal annealing and electrospinning from RuO2 and TiO2 precursors. Single-crystalline RuO2 nanoneedles with relatively small dimensions and a high density o...

The goal of the work presented here was to develop a simulation approach for studying the effects of materials and geometry on the performance of Li-ion Solid State Batteries (SSB). Simulation provides the opportunity to explore, with ease, different material properties and cell geometries to optimize a Li-ion SSB's performance. Simulations shown i...

1. Introduction – Sodium batteries are being studied to overcome the drawbacks of Li ion based batteries viz. cost, poor cycle life of Li etc. [1]. Layered compounds are finding applications as anodes and cathodes as these are able to intercalate the large sized Na+ ion better [2]. Prussian blue and layered transition metal oxides are the compounds...

Among many technical barriers for the commercialization of proton exchange membrane fuel cells (PEMFC), low working temperature and carbon monoxide poisoning to catalyst have to be solved; however, they are not easy problems because they are related intrinsic properties of per-fluorinated Sulfonic Acid (PFSA) electrolytes such as Nafion. Recently,...

Passive air breathing proton exchange membranes fuel cells (AB-PEMFC) have a unique advantage such as remarkably reducing stack weight by minimizing balance of plant (BOP). However, the performance of the AB-PEMFC is worse than general PEMFC because it is difficult to controlling humidification and stack temperature. Thus, the proton exchange membr...

1. Introduction – Lithium-ion batteries are regarded as the current benchmark for new battery designs. While lithium-ion batteries offer both high energy densities and large cell potentials, they also possess many inherent disadvantages such as flammability and high material costs [1, 2]. Potassium-ion (K+) batteries can be of great environmental a...

We report a facile synthesis of electrospun RuO2-Co3O4hybrid nanotubes as well as their enhanced electrochemical responses. Among all RuO2-Co3O4hybrid nanotubes, the polycrystalline RuO2-Co3O4hybrid nanotubes with optimum relative atomic ratios of Ru/Co=2.3:1.0 show the highly efficient catalytic activity for oxygen reduction reaction (ORR). Additi...

We present a facile synthetic route of ruthenium dioxide (RuO2)-rhenium oxide (ReO3) electrospun composite nanofibers and their electrocatalytic responses for capacitance and H2O2 sensing. The contents of rhenium oxide of electrospun ruthenium dioxide (RuO2) were carefully controlled by an electrospinning process with the preparation of the precurs...

This paper proposes a novel method that enables location sensing for a mobile object by utilizing deployed passive UHF Radio Frequency Identification (RFID) tags and a stationary RFID reader. In order to estimate the mobile object location, the proposed method utilizes the second order under damped system based tag to tag interference model. The em...

In recent, autonomous navigation techniques to avoid obstacles have been studied by using unmanned aircraft vehicles(UAVs) since the increment of UAV's interest and utilization. Particularly, autonomous navigation based UAVs are utilized in several areas such as military, police, media, and so on. However, there are still some problems to avoid obs...

Recently, in power system studies, Multiple Energy Carriers (MECs) such as Energy Hub has been broadly utilized in power system planners and operators. Particularly, Energy Hub performs one of the most important role as the intermediate in implementing the MECs. However, it still needs to be put under examination in both modeling and operating conc...

A proton exchange membrane is a core component in the proton exchange membrane fuel cell because the role of proton exchange membrane(PEM)is supplying proton conductivity to fuel cell, a gas separator, and insulating between an anode and cathode. Among various role of PEM, supplying proton conductivity is the most important and the proton conductiv...

The design of a fuel cells stack is important to get optimal output power. This study focuses on the evaluation of fuel cell system for unmaned aerial vehicles (UAVs). Low temperature proton exchange membrane (LTPEM) fuel cells are the most promising energy source for the robot applications because of their unique advantages such as high energy den...

This study presents the analysis of the changes in cerebral activation state induced by the visual stimuli delivered through the combination of colors, and derived significant results associated with the changes in cerebral activation state in relation to concentration index, psychological index, etc., based on the variation of stimulation. The res...

The high temperature proton exchange membrane fuel cell (HT-PEMFC) is a key of solving corrosion problem in catalyst layer from CO Poisonning. The key issue of HT-PEMFC is developing novel proton exchange membrane which has good proton conductivity under dry condition and thermal properties compare with Nafion. Sulfonated graphene (S-graphene) and...

1. Introduction – Solid state batteries overcome many of the essential drawbacks of liquid electrolyte batteries, such as liquid electrolyte and leakage issues [1]. Another major issue is the degradation of the Li based cathode from continuous cycling due to a change in its microstructure [2]. Nanoscale coatings are thought to prevent the degradati...

Since the increment of the interesting for smart refrigerator in recent, the several kinds of smart refrigerator have been launched. A smart refrigerator has various functions such as refrigerator’s function, internet shopping, grocery management, and remote control. However, it has still problems in order to utilize the refrigerator conveniently u...

In recent, the demand of Unmanned Aerial Vehicles (UAVs) that can autonomous navigation and remote control has been increased in military, civil and commercial field. Particularly, existing researches focused on autonomous navigation method based on vanish point and remote control method based on event processing in indoor environments. However, th...

In this paper, we propose a novel indoor localization technique of Unmanned Aerial Vehicle (UAV) using passive UHF far-field RFID systems. First, this paper presents impact of existence of UAV to RFID system. According to our empirical results, the existence of UAV, in a monitoring area, induces RF shadowing and Received Signal Strength Indicator (...

This paper introduces a bio-inspired GAORI robot with renewable energy source and presents its command and data acquisition system for remote commanding as well as data forwarding/backup/relay. The hardware architecture design and software implementation of GAORI command and data acquisition system are presented in this paper.

In this research, we studied several factors which impact the performance of passive UHF far-field RFID based localization systems with KNN and LDTI algorithms. According to the empirical results, the localization system can be significantly interfered by distance relative factors such as the true positive reference identification rate and interrog...

In the recent research technical solutions have been studied to integrate renewable energy into unmanned aerial vehicles to use it as the main power source. As the weight of the aerial vehicle body is essential for its performance, we consider to use light-weight solar cell technology. Furthermore fuel cells are also integrated create a highly ener...

In intelligent environments, detecting possible errors and completing missing values then deciding about the quality and validity of the sensed data are roles of context reasoning in order to improve the reliability of information. Particularly, learning to associate operations and roles with dynamic contexts is necessary for adapting user needs an...

In this paper, we describe an automatic people-counting and environment monitoring system based on a wireless sensor network at a mountain area. Several people-counting systems and monitoring systems have been proposed separately. However, these systems are not suitable to a place such as the mountain area because of a few problems. In this paper,...

Summary Wireless Sensor Networks (WSNs) become an important issue such as environmental monitoring, home or factory automation, logistics and so on. Many wild fires cause to damage on forest and a mountain which have valuable natural resources during the dry winter season. Current surveillance systems use a camera, an infrared sensor system and a s...

We describe an exceptional case of a frontal convexity chondroma arising at the site of a compound depressed skull fracture operated on 12 years earlier. We conclude that intracranial chondroma should be included in the differential diagnosis of a calcified mass for the patients who had had a compound, depressed skull fracture along the suture line...

Holmes' (rubral or midbrain) tremor is an unusual combination of 2 Hz to 5 Hz rest, postural, and kinetic tremors of an upper extremity. This tremor has been considered to result from the lesions in the vicinity of the red nucleus in the midbrain. There has been no systematic analysis of the surgical target in the Holmes' tremor so far of nucleus v...

Objective: To determine, using proton magnetic resonance spectroscopy (H-1 MRS) whether thalamotomy in patients with Parkinson's disease gives rise to significant changes in regional brain metabolism. Materials and Methods: Fifteen patients each underwent stereotactic thalamotomy for the control of medically refractory parkinsonian tremor. Single-v...

Red wine polyphenols (RWPs) have been shown to have an antiatherogenic activity mainly through antioxidative effects on LDL oxidation. Although vascular smooth muscle cell (SMC) migration is critical to atherosclerosis formation, the effect of RWPs on SMC migration has not been elucidated. In this study, we investigated whether RWPs could affect th...

The object of this study is to assess the changes in regional cerebral blood flow (rCBF) following stereotactic limbic leukotomy in patients with medically intractable Obsessive-Compulsive Disorder (OCD). Technetium-99-Hexa Methyl Propylene Amine Oxime (99mTc-HMPAO) Single Photon Emission Computed Tomography (SPECT) data obtained before and after l...

To add metabolic information during stereotactic biopsy target selection, the authors adopted proton chemical shift imaging (1H CSI)-directed stereotactic biopsy. Currently, proton single voxel spectroscopy (SVS) technique has been reported in stereotactic biopsy. We performed 1H CSI in combination with a stereotactic headframe and selected targets...

The best operative intervention for children with arachnoid cysts remains the subject of controversy. Recent reports stress that craniotomy for cyst fenestration is associated with a low incidence of morbidity and mortality and may leave the child shunt-independent. Among a total of 66 intracranial arachnoid cysts operated on in the authors' depart...

In order to define metabolic brain changes associated with mild traumatic brain injury, proton magnetic resonance spectroscopy (MRS) was performed in patients with regional brain contusion and 13–15 of initial GCS score. The authors measured N-acetylasparta-te(NAA)/creatine(Cr) ratio and lactate signal on in vivo proton MRS, which indicated cell lo...

The authors investigate whether there is a lateral effect of 1H-magnetic resonance spectroscopy (MRS) observable metabolite ratios between the symptomatic and the asymptomatic side in Parkinson's disease with unilateral symptoms. Localized in vivo 1H MRS was used to measure the metabolite levels in the symptomatic and the asymptomatic sides of the...