• Proceedings of the ESK Conference
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• 1997.04a
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• pp.17-25
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• 1997

The evoked potentials for concentrations of solutions of the four qualities of tastes(i.e., sweet, salty, sour, and bitter tastes) were measured. The solution was applied to the chorda tympani nerve located on the left side of the tongue at 20mm from the tip and 15mm left from the center line. The evoked potentials were detected from Cz referred to A1(left lobe) with the ground at the Fpz position. The Maximum potential level and its latency were evaluated. The individual threshold level of concentration of the solutions of four tastes were measured. Artificial saliva was used as a control solution. The evoked positive potentials for four qualities of tastes (i.e., gustatory evokde potentials) were found to be around 150ms by averaging eight responses. The arbitrary concentration of the solutions were presented by the relative concentration, which was the ratio of the arbitrary concentration to the individual threshold level. The characteristic relations between the latency and the relative concentration ;and those between the potential level and the relative concentration were evaluated. These evalutions showed that (1) the latencies for salty and bitter tastes denoted the minimum values due to for the change of relative concentration, and that (2) the latency for sour taste decreased as the relative concentrations increased, while the latency for sweet taste denoted the inverse tendency, Sinificant differences between any two maximum potential levels were not recognized. A response latencies to sucrose were abolished after treatment of tongue by a sweet-suppressing agent.

• Journal of Sensor Science and Technology
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• v.4 no.1
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• pp.43-50
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• 1995

We measured the traceability error for nine high temperature calibration service centers including KRISS through the round-robin test. In this test the type S thermocouple, which used as a calibration standard thermometer commonly, was accommodated as a test thermocouple. Intercomparison data of three institutions were coincident with KRISS's data within ${\pm}0.5^{\circ}C$, which was the calibration uncertainty of the type S thermocouple, but the remaining six institution's data were deviated from the assigned uncertainty level. Deviation of the intercomparison data increased gradually according to the increase of the test temperature. and the maximum difference was so large as about $2.0^{\circ}C$ at the highest test temperature, gold point. In this study we found the traceability error of high temperature calibration service center for a high temperature standard was within $2.0^{\circ}C$.

• Progress in Medical Physics
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• v.23 no.4
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• pp.285-291
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• 2012

In the present study, we measured the pure beta particle energy spectra of $^{147}Pm$, $^{85}Kr$, $^{90}Sr+^{90}Y$ radionuclide sources. We confirmed the residual maximum energies of KRISS sources meet the requirement of ISO 6980 and calculated mass collision stopping power ratio, which is essential for absolute measurement of absorbed dose from the reference ${\beta}$-rays. The residual maximum energies of KRISS $^{147}Pm$, $^{85}Kr$, $^{90}Sr+^{90}Y$ sources are 0.14, 0.57 and 0.93 MeV, respectively and the mass collision stopping power ratios are 1.123, 1.120 and 1.109, respectively.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.78-87
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• 2018

This paper describes specular reflectance measurements of dielectric plates in three waveguide frequency bands: D-band (110-170 GHz), G-band (140-220 GHz), and J-band (220-325 GHz). The transmit (Tx) part of the proposed specular reflectance measurement system is stationary, while the receive (Rx) part and the material under test (MUT) holder are concentric-rotating with a 2:1 speed ratio for specular reflectance measurements. In specular reflectance measurements, the first step measures the specular reflection coefficients of an MUT and a metal plate on the MUT holder located at the center of the Tx and Rx parts, and the second step calculates the specular reflectance defined by the specular reflection power (i.e., intensity) of the MUT normalized to that of the metal plate. Multiple reflection effects between the Tx and Rx antennas and the MUT on the measured specular reflectance are minimized by averaging out the multiple specular reflectances measured with changing the separation distance between the two antennas by ${\lambda}/8$ intervals. Measurement results of the perpendicular-polarized specular reflectance of commonly used dielectric plates are verified by comparing those with the analytic results and show that the results measured over the overlapped frequency range of the D-/G-bands and at the boundary frequency of the G-/J-bands agree well with the results for the other band, respectively.

• Applied Microscopy
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• v.36 no.spc1
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• pp.35-40
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• 2006

Self-assembled InAs/GaAs quantum dots (QDs) were grown by the atomic layer epitaxy (ALE) and molecular beam epitaxy (MBE) techniques, The structure and the thermal stability of QDs have been studied by high resolution electron microscopy with in-situ heating experiment capability, The ALE and MBE QDs were found to form a hemispherical structure with side facets in the early stage of growth, Upon capping by GaAs layer, however, the apex of QDs changed to a flat one. The ALE QDs have larger size and more regular shape than those of MBE QDs. The QDs collapse due to elevated temperature was observed directly in atomic scale, In situ heating experiment within TEM revealed that the uncapped QDs remained stable up to $580^{\circ}C$, However, at temperature above $600^{\circ}C$, the QDs collapsed due to the diffusion and evaporation of In and As from the QDs, The density of the QDs decreased abruptly by this collapse and most of them disappeared at above $600^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.30 no.12
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• pp.1885-1895
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• 2020

Rumex japonicus Houtt (RJH) is a valuable plant used in traditional medicine to treat several diseases, such as scabies and jaundice. In this study, Jurkat cell growth inhibitory extracts of R. japonicus roots were subjected to bioassay-guided fractionation, resulting in the isolation of three naphthalene derivatives (3-5) along with one anthraquinone (6) and two phenolic compounds (1 and 2). Among these compounds, 2-methoxystypandrone (5) exhibited potent anti-proliferative effects on Jurkat cells. Analysis by flow cytometry confirmed that 2-methoxystypandrone (5) could significantly reduce mitochondrial membrane potential and promote increased levels of mitochondrial reactive oxygen species (ROS), suggesting a strong mitochondrial depolarization effect. Real-time quantitative polymerase chain reaction (qPCR) analysis was also performed, and the results revealed that the accumulation of ROS was caused by reduced mRNA expression levels of heme oxygenase (HO-1), catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD). In addition, 2-methoxystypandrone (5) triggered strong apoptosis that was mediated by the arrest of the G0/G1 phase of the cell cycle. Furthermore, 2-methoxystypandrone (5) downregulated p-IκB-α, p-NF-κB p65, Bcl2, and Bcl-xl and upregulated BAX proteins. Taken together, these findings revealed that 2-methoxystypandrone (5) isolated from RJH could potentially serve as an early lead compound for leukemia treatment involving intracellular signaling by increasing mitochondrial ROS and exerting anti-proliferative effects.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.217-225
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• 2021

This study aimed to investigate the neuroprotective effects of 1-methoxylespeflorin G11 (MLG), a pterocarpan, against glutamate-induced neurotoxicity in neuronal HT22 hippocampal cells. The protective effects of MLG were evaluated using MTT assay and microscopic analysis. The extent of apoptosis was studied using flow cytometric analysis performed on the damaged cells probed with annexin V/propidium iodide. Moreover, mitochondrial reactive oxygen species (ROS) were assessed using flow cytometry through MitoSOXTM Red staining. To determine mitochondrial membrane potential, staining with tetramethylrhodamine and JC-1 was performed followed by flow cytometry. The results demonstrated that MLG attenuates glutamate-induced apoptosis in HT22 cells by inhibiting intracellular ROS generation and mitochondrial dysfunction. Additionally, MLG prevented glutamate-induced apoptotic pathway in HT22 cells through upregulation of Bcl-2 and downregulation of cleaved PARP-1, AIF, and phosphorylated MAPK cascades. In addition, MLG treatment induced HO-1 expression in HT22 cells. These results suggested that MLG exhibits neuroprotective effects against glutamate-induced neurotoxicity in neuronal HT22 cells by inhibiting oxidative stress and apoptosis.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.156-157
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• 1998

It is a diffcult and challenging pproblem to control the growth of eppitaxial films. Heteroeppitaxy is esppecially idfficult because of the lattice mismatch between sub-strate and depposited layers. This mismatch leads usually to a three dimensional(3D) island growth. But the use of surfactants such as As, Sb, and Bi can be beneficial in obtaining high quality heteroeppitaxial films. In this study medium energy ion scattering sppectroscoppy(MEIS) was used in order to reveal the growth mode of Ge on Si(001) and the strain of depposited film without and with dynamically supplied atomic hydrogen at the growth thempperature of 35$0^{\circ}C$. It was ppossible to control the growth mode from layer-by-layer followed by 3D island to layer-by-layer by controlling the hydrogen flux. In the absent of hydro-gen the film grows in the layer-by-layer mode within the critical thickness(about 3ML) and the 3D island formation is followed(Fig1). The 3D island formation is suppressed by introducing hydrogen resulting in layer-by-layer growth beyond the critical thickness(Fig2) We measured angular shift of blocking dipp in order to obtain the structural information on the thin films. In the ppressence of atomic hydrogen the blocking 야 is shifted toward higher scattering angle about 1。. That means the film is distorted tetragonally and strained therefore(Fig4) In other case the shift of blocking dipp at 3ML is almost same as pprevious case. But above the critical thickness the pposition of blocking dipp is similar to that of Si bulk(Fig3). It means the films is relaxed from the first layer. There is 4.2% lattice mismatch between Ge and Si. That mismatch results in about 2。 shift of blocking dipp. We measured about 1。 shift. This fact could be due to the intermixing of Ge and Si. This expperimental results are consistent with Vegard's law which says that the lattice constant of alloys is linear combination of the lattic constants of the ppure materials.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.76.3-77
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• 2021

GMT secondary mirror system consists of 7 segmented adaptive mirrors. Each segment consists of a thin shell mirror, actuators and a reference body. The thin shell has a few millimeters of thickness so that it can be easily bent by push and pull force of actuators to compensate the wavefront disturbance of light due to air turbulence. The one end of actuator is supported by the reference body and the other end is adapted to this thin shell. One of critical role of the reference body is to provide the reference surface for the thin shell actuators. Therefore, the reference body is one of key components to succeed in development of GMT ASM. Recently, Korea Research Institute of Standards and Science (KRISS) and University of Arizona (UA) has signed a contract that they will cooperate to develop the first set of off-axis reference body for GMT ASM. This project started August 2021 and will be finished in Dec. 2022. The reference body has total 675 holes to accommodate actuators and 144 pockets for lightweighting. The rear surface has a curved rib shape with radius of curvature of 4387 mm with offset of 128.32mm. Since this reference body is placed just above the thin shell so that the front surface shape needs to be close to that of thin shell. The front surface has a concave off-axis asphere, of which radius of curvature is 4165.99 mm and off-axis distance is about 1088 mm. The material is Zerodur CTE class 1 (CTE=0.05 ppm/oC) from SCHOTT. All the actuator holes and pockets are machined normal to the front surface. It is a very complex challenging optical elements that involves sophisticated machining process as well as accurate metrology. After finishing the fabrication of reference body in KRISS, it will be shipped to UA for final touches and finally sent to Adoptica in Italy, in early 2023. This paper presets the development plan for the GMT ASM Reference Body and relevant fabrication and metrology plans.

• Analytical Science and Technology
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• v.22 no.4
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• pp.302-306
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• 2009

A trace amount of boron in steel significantly influences its mechanical and physical properties. A prompt gamma ray activation analysis (PGAA) method is used to measure boron in low alloy steel samples of KRISS 101-01-C21~C26. NIST SRMs of 362, 364, 1761 and 1767 serve as the control standards to validate the measurement method. The measured values of the NIST SRMs are consistent with their certified values within the expected uncertainties, except for that of NIST SRM 362. Experimental uncertainties are evaluated according to the guidelines given by the International Organization for Standardization (ISO). The expanded uncertainties are calculated with a coverage factor of 2, at approximately 95% confidence level. The calculated relative expanded uncertainties of boron mass fractions are between 3% and 7% at the mg/kg level. The results are compared with the results measured by the solvent extraction-inductively coupled optical emission spectrometry (ICP/OES) method.