GUN YONG SUNG - Academia.edu (original) (raw)
Papers by GUN YONG SUNG
arXiv: Superconductivity, 2001
The microstructure of the MgB2 superconductor sintered at high temperature under a high pressure ... more The microstructure of the MgB2 superconductor sintered at high temperature under a high pressure of about 3 GPa was investigated by using a high-resolution transmission electron microscope (HRTEM). The TEM images did not show any pores in the specimen. All grains were compactly connected, and no discernable empty spaces or impurities at the boundaries existed over the regions investigated. The HRTEM image showed clearly each constituent atom that formed the basal hexagonal plane, without any defect in a single grain. The a-axis lattice parameter, 0.307 nm, from this direct measurement was shorter than the value, 0.314 nm obtained from samples prepared using diffusion techniques. A minor impurity phase, which was most probably MgB4 and did not form interfacial layers was also observed, but was well isolated from the main MgB2 phase. Our results verify that the MgB2 powder was sintered under high temperature and high pressure into its theoretical density without any porosity or grain ...
International Journal of Molecular Sciences, 2020
The in vitro tests in current research employ simple culture methods that fail to mimic the real ... more The in vitro tests in current research employ simple culture methods that fail to mimic the real human tissue. In this study, we report drug testing with a ‘pumpless skin-on-a-chip’ that mimics the structural and functional responses of human skin. This model is a skin equivalent constituting two layers of the skin, dermis and epidermis, developed using human primary fibroblasts and keratinocytes. Using the gravity flow device system, the medium was rotated at an angle of 15 degrees on both sides so as to circulate through the pumpless skin-on-a-chip microfluidic channel. This pumpless skin-on-a-chip is composed of upper and lower chips, and is manufactured using porous membranes so that medium can be diffused and supplied to the skin equivalent. Drug testing was performed using Curcuma longa leaf extract (CLLE), a natural product cosmetic ingredient, to evaluate the usefulness of the chip and the efficacy of the cosmetic ingredient. It was found that the skin barrier function of th...
Scientific Reports
Perm-selective ion transportation in a nanoscale structure such as nanochannel, nanoporous membra... more Perm-selective ion transportation in a nanoscale structure such as nanochannel, nanoporous membrane or nanojunction has been extensively studied with aids of nanofabrication technology for a decade. While theoretical and experimental advances pushed the phenomenon to seminal innovative applications, its basic observation has relied only on an indirect analysis such as current-voltage relation or fluorescent imaging adjacent to the nanostructures. Here we experimentally, for the first time, demonstrated a direct visualization of perm-selective ion transportation through the nanoscale space using an ionic plasma generation. A micro/nanofluidic device was employed for a micro bubble formation, plasma negation and penetration of the plasma along the nanojunction. The direct observation provided a keen evidence of perm-selectivity, i.e. allowing cationic species and rejecting anionic species. Furthermore, we can capture the plasma of lithium, which has lower mobility than sodium in aqueo...
Biomedicines
Numerous studies have addressed the utilization of glutaraldehyde (GA) as a homobifunctional cros... more Numerous studies have addressed the utilization of glutaraldehyde (GA) as a homobifunctional cross-linker. However, its applicability has been impeded due to several issues, including the tendency of GA molecules to undergo polymerization. Herein, a portable urea biosensor was developed for the real-time monitoring of the flow of physiological fluids; this was achieved by using disuccinimidyl cross-linker-based urease immobilization. Urease was immobilized on a porous polytetrafluoroethylene (PTFE) solid support using different disuccinimidyl cross-linkers, namely disuccinimidyl glutarate (DSG), disuccinimidyl suberate (DSS) and bis-N-succinimidyl-(pentaethylene glycol) ester (BS(PEG)5). A urease activity test revealed that DSS exhibited the highest urease immobilizing efficiency, whereas FT-IR analysis confirmed that urease was immobilized on the PTFE membrane via DSS cross-linking. The membrane was inserted in a polydimethylsiloxane (PDMS) fluidic chamber that generated an electro...
International Journal of Molecular Sciences
A human skin equivalent (HSE) composed of the epidermis and dermis is cultured using a pumpless s... more A human skin equivalent (HSE) composed of the epidermis and dermis is cultured using a pumpless skin-on-a-chip system to supply cultures the desired flow rate using gravity flow without a pump or an external tube connection. Coenzyme Q10 efficacy is tested by adjusting its concentration, as it is known to have anti-aging and antioxidant effects in culture solutions. The relationship between the contraction rate of a full-thickness human skin equivalent and secreted transforming growth factor (TGF) β-1 is analyzed via enzyme-linked immunosorbent assay (ELISA). Following hematoxylin and eosin (H&E) staining, an image of the skin equivalent is analyzed to measure the epidermal layer’s thickness. The cell density and differentiation of the dermis layer are investigated. Gene and protein expression in the dermal and epidermal layers are quantitatively analyzed using quantitative real time polymerase chain reaction (qPCR) and immunohistochemical staining. As the coenzyme Q10 treatment con...
Sensors (Basel, Switzerland), Jan 9, 2018
In this study, a portable urea sensor that monitors the urea concentration in flow conditions was... more In this study, a portable urea sensor that monitors the urea concentration in flow conditions was fabricated. We propose an electrochemical sensor that continually measures the urea concentration of samples flowing through it at a constant flow rate in real time. For the electrochemical sensing, a porous silk fibroin membrane with immobilized urease was mounted in a polydimethylsiloxane (PDMS) sensor housing. The fabricated urea sensor elicited linear current⁻concentration characteristics in the clinically significant concentration range (0.1⁻20 mM) based on peritoneal dialysis. The sensor maintained the linear current⁻concentration characteristics during operation in flow conditions.
Bulletin of the Korean Chemical Society
In this study, we have developed a new detection method using Si field effect transistor (FET)-ty... more In this study, we have developed a new detection method using Si field effect transistor (FET)-type biosensors, which enables the direct monitoring of antigen-antibody binding within very high-ionic-strength solutions such as 1×PBS and human serum. In the new method, as no additional dilution or desalting processes are required, the FET-type biosensors can be more suitable for ultrasensitive and real-time analysis of raw sample solutions. The new detection scheme is based on the observation that the strength of antigen-antibody-specific binding is significantly influenced by the ionic strength of the reaction solutions. For a prostate specific antigen (PSA), in some conditions, the binding reaction between PSA and anti-PSA in a low-ionic strength reaction solution such as 10 µM phosphate buffer is weak (reversible), while that in high-ionic strength reaction solutions such as 1×PBS or human serum is strong.
International Journal of Modern Physics B
We have investigated the crystalline structure of high rate deposited YBa 2 Cu 3 O x thin films p... more We have investigated the crystalline structure of high rate deposited YBa 2 Cu 3 O x thin films prepared by high speed pulsed laser deposition. A cation disordered cubic structure with lattice parameter of 0.39 nm was found in YBCO thin film deposited at 12.2 nm/s deposition rate and 650°C substrate temperature conditions. The short range ordered cubic YBa 2 Cu 3 O x thin film growth at high deposition rate was explained by the short migration length of Y and Ba cation atoms owing to the high incident flux rate.
Advanced Ceramic Materials
ANISOTROPIC GRAIN GROWTH OF ZnO GRAIN IN THE VARISTOR SYSTEM ZnO-Bi 2 O 3-MnO-TiO 2. GY Sung, CH ... more ANISOTROPIC GRAIN GROWTH OF ZnO GRAIN IN THE VARISTOR SYSTEM ZnO-Bi 2 O 3-MnO-TiO 2. GY Sung, CH Kim Adv. Ceram. Mater. 3:66, 604-606, 1988. Selected-area electron diffraction patterns obtained by TEM ...
Advanced Ceramic Materials
To prove the discrepancy between the calculated barrier voltage and the measured barrier voltage ... more To prove the discrepancy between the calculated barrier voltage and the measured barrier voltage resulting from the broad grain-size distribution, the microstructures and grain size distribution with relation to IV characteristics of ZnO-Bi{sub 2}O{sub 3}-MnO and ZnO-Bi{sub 2}O{sub ...
Superconductor Science and Technology, Aug 1, 2002
... of a T flip-flop using high-Tc interface-engineered Josephson junctions JunHo Kim, Sang Hyeob... more ... of a T flip-flop using high-Tc interface-engineered Josephson junctions JunHo Kim, Sang HyeobKim and Gun Yong Sung Telecommunications Basic Research Laboratory, Electronics and Telecommunications Research Institute, Daejon 305-350, Republic of Korea ...
Langmuir, Oct 1, 2009
An antibody immobilization was investigated using a self-assembled monolayer (SAM) over the highl... more An antibody immobilization was investigated using a self-assembled monolayer (SAM) over the highly refractive coatings with a SiO2, TiO2, or Si3N4 substrate. The immobilization was characterized by analyzing the hydrophilic properties of hydroxyl (OH) groups on surface coatings with contact angle (CA) measurements to enhance protein immobilization. The hydroxyl (OH) group was formed in greater amounts as the oxygen plasma exposure time was increased, which resulted in a large enhancement in antibody immobilization. It indicated that hydroxyl (OH) group formation is critical for developing a label-free optical transducer with a high sensitivity.
arXiv: Superconductivity, 2001
The microstructure of the MgB2 superconductor sintered at high temperature under a high pressure ... more The microstructure of the MgB2 superconductor sintered at high temperature under a high pressure of about 3 GPa was investigated by using a high-resolution transmission electron microscope (HRTEM). The TEM images did not show any pores in the specimen. All grains were compactly connected, and no discernable empty spaces or impurities at the boundaries existed over the regions investigated. The HRTEM image showed clearly each constituent atom that formed the basal hexagonal plane, without any defect in a single grain. The a-axis lattice parameter, 0.307 nm, from this direct measurement was shorter than the value, 0.314 nm obtained from samples prepared using diffusion techniques. A minor impurity phase, which was most probably MgB4 and did not form interfacial layers was also observed, but was well isolated from the main MgB2 phase. Our results verify that the MgB2 powder was sintered under high temperature and high pressure into its theoretical density without any porosity or grain ...
International Journal of Molecular Sciences, 2020
The in vitro tests in current research employ simple culture methods that fail to mimic the real ... more The in vitro tests in current research employ simple culture methods that fail to mimic the real human tissue. In this study, we report drug testing with a ‘pumpless skin-on-a-chip’ that mimics the structural and functional responses of human skin. This model is a skin equivalent constituting two layers of the skin, dermis and epidermis, developed using human primary fibroblasts and keratinocytes. Using the gravity flow device system, the medium was rotated at an angle of 15 degrees on both sides so as to circulate through the pumpless skin-on-a-chip microfluidic channel. This pumpless skin-on-a-chip is composed of upper and lower chips, and is manufactured using porous membranes so that medium can be diffused and supplied to the skin equivalent. Drug testing was performed using Curcuma longa leaf extract (CLLE), a natural product cosmetic ingredient, to evaluate the usefulness of the chip and the efficacy of the cosmetic ingredient. It was found that the skin barrier function of th...
Scientific Reports
Perm-selective ion transportation in a nanoscale structure such as nanochannel, nanoporous membra... more Perm-selective ion transportation in a nanoscale structure such as nanochannel, nanoporous membrane or nanojunction has been extensively studied with aids of nanofabrication technology for a decade. While theoretical and experimental advances pushed the phenomenon to seminal innovative applications, its basic observation has relied only on an indirect analysis such as current-voltage relation or fluorescent imaging adjacent to the nanostructures. Here we experimentally, for the first time, demonstrated a direct visualization of perm-selective ion transportation through the nanoscale space using an ionic plasma generation. A micro/nanofluidic device was employed for a micro bubble formation, plasma negation and penetration of the plasma along the nanojunction. The direct observation provided a keen evidence of perm-selectivity, i.e. allowing cationic species and rejecting anionic species. Furthermore, we can capture the plasma of lithium, which has lower mobility than sodium in aqueo...
Biomedicines
Numerous studies have addressed the utilization of glutaraldehyde (GA) as a homobifunctional cros... more Numerous studies have addressed the utilization of glutaraldehyde (GA) as a homobifunctional cross-linker. However, its applicability has been impeded due to several issues, including the tendency of GA molecules to undergo polymerization. Herein, a portable urea biosensor was developed for the real-time monitoring of the flow of physiological fluids; this was achieved by using disuccinimidyl cross-linker-based urease immobilization. Urease was immobilized on a porous polytetrafluoroethylene (PTFE) solid support using different disuccinimidyl cross-linkers, namely disuccinimidyl glutarate (DSG), disuccinimidyl suberate (DSS) and bis-N-succinimidyl-(pentaethylene glycol) ester (BS(PEG)5). A urease activity test revealed that DSS exhibited the highest urease immobilizing efficiency, whereas FT-IR analysis confirmed that urease was immobilized on the PTFE membrane via DSS cross-linking. The membrane was inserted in a polydimethylsiloxane (PDMS) fluidic chamber that generated an electro...
International Journal of Molecular Sciences
A human skin equivalent (HSE) composed of the epidermis and dermis is cultured using a pumpless s... more A human skin equivalent (HSE) composed of the epidermis and dermis is cultured using a pumpless skin-on-a-chip system to supply cultures the desired flow rate using gravity flow without a pump or an external tube connection. Coenzyme Q10 efficacy is tested by adjusting its concentration, as it is known to have anti-aging and antioxidant effects in culture solutions. The relationship between the contraction rate of a full-thickness human skin equivalent and secreted transforming growth factor (TGF) β-1 is analyzed via enzyme-linked immunosorbent assay (ELISA). Following hematoxylin and eosin (H&E) staining, an image of the skin equivalent is analyzed to measure the epidermal layer’s thickness. The cell density and differentiation of the dermis layer are investigated. Gene and protein expression in the dermal and epidermal layers are quantitatively analyzed using quantitative real time polymerase chain reaction (qPCR) and immunohistochemical staining. As the coenzyme Q10 treatment con...
Sensors (Basel, Switzerland), Jan 9, 2018
In this study, a portable urea sensor that monitors the urea concentration in flow conditions was... more In this study, a portable urea sensor that monitors the urea concentration in flow conditions was fabricated. We propose an electrochemical sensor that continually measures the urea concentration of samples flowing through it at a constant flow rate in real time. For the electrochemical sensing, a porous silk fibroin membrane with immobilized urease was mounted in a polydimethylsiloxane (PDMS) sensor housing. The fabricated urea sensor elicited linear current⁻concentration characteristics in the clinically significant concentration range (0.1⁻20 mM) based on peritoneal dialysis. The sensor maintained the linear current⁻concentration characteristics during operation in flow conditions.
Bulletin of the Korean Chemical Society
In this study, we have developed a new detection method using Si field effect transistor (FET)-ty... more In this study, we have developed a new detection method using Si field effect transistor (FET)-type biosensors, which enables the direct monitoring of antigen-antibody binding within very high-ionic-strength solutions such as 1×PBS and human serum. In the new method, as no additional dilution or desalting processes are required, the FET-type biosensors can be more suitable for ultrasensitive and real-time analysis of raw sample solutions. The new detection scheme is based on the observation that the strength of antigen-antibody-specific binding is significantly influenced by the ionic strength of the reaction solutions. For a prostate specific antigen (PSA), in some conditions, the binding reaction between PSA and anti-PSA in a low-ionic strength reaction solution such as 10 µM phosphate buffer is weak (reversible), while that in high-ionic strength reaction solutions such as 1×PBS or human serum is strong.
International Journal of Modern Physics B
We have investigated the crystalline structure of high rate deposited YBa 2 Cu 3 O x thin films p... more We have investigated the crystalline structure of high rate deposited YBa 2 Cu 3 O x thin films prepared by high speed pulsed laser deposition. A cation disordered cubic structure with lattice parameter of 0.39 nm was found in YBCO thin film deposited at 12.2 nm/s deposition rate and 650°C substrate temperature conditions. The short range ordered cubic YBa 2 Cu 3 O x thin film growth at high deposition rate was explained by the short migration length of Y and Ba cation atoms owing to the high incident flux rate.
Advanced Ceramic Materials
ANISOTROPIC GRAIN GROWTH OF ZnO GRAIN IN THE VARISTOR SYSTEM ZnO-Bi 2 O 3-MnO-TiO 2. GY Sung, CH ... more ANISOTROPIC GRAIN GROWTH OF ZnO GRAIN IN THE VARISTOR SYSTEM ZnO-Bi 2 O 3-MnO-TiO 2. GY Sung, CH Kim Adv. Ceram. Mater. 3:66, 604-606, 1988. Selected-area electron diffraction patterns obtained by TEM ...
Advanced Ceramic Materials
To prove the discrepancy between the calculated barrier voltage and the measured barrier voltage ... more To prove the discrepancy between the calculated barrier voltage and the measured barrier voltage resulting from the broad grain-size distribution, the microstructures and grain size distribution with relation to IV characteristics of ZnO-Bi{sub 2}O{sub 3}-MnO and ZnO-Bi{sub 2}O{sub ...
Superconductor Science and Technology, Aug 1, 2002
... of a T flip-flop using high-Tc interface-engineered Josephson junctions JunHo Kim, Sang Hyeob... more ... of a T flip-flop using high-Tc interface-engineered Josephson junctions JunHo Kim, Sang HyeobKim and Gun Yong Sung Telecommunications Basic Research Laboratory, Electronics and Telecommunications Research Institute, Daejon 305-350, Republic of Korea ...
Langmuir, Oct 1, 2009
An antibody immobilization was investigated using a self-assembled monolayer (SAM) over the highl... more An antibody immobilization was investigated using a self-assembled monolayer (SAM) over the highly refractive coatings with a SiO2, TiO2, or Si3N4 substrate. The immobilization was characterized by analyzing the hydrophilic properties of hydroxyl (OH) groups on surface coatings with contact angle (CA) measurements to enhance protein immobilization. The hydroxyl (OH) group was formed in greater amounts as the oxygen plasma exposure time was increased, which resulted in a large enhancement in antibody immobilization. It indicated that hydroxyl (OH) group formation is critical for developing a label-free optical transducer with a high sensitivity.