• Proceedings of the Korean Vacuum Society Conference
• /
• 2000.02a
• /
• pp.165-165
• /
• 2000

Glass slides were chemically etched with sulfuric acid using five different methods. we investigated the effects of the chemical etching conditions on such properties as chemical composition, surface roughness, and the thermal stability of the glass. Sodium and carbon atoms in the surface of the glass are effectively eliminated by chemical etching with sulfuric acid. The glass slides were boiled for 30 min in 95% sulfuric acid and were depth profiled at room temperature with X-ray photoelectron spectroscopy (XPS), the Na ls signal was not detected in the detection limit of XPS. Surface morphology of the glass was very different depending on the concentration of sulfuric acid. The surface of the glass etched with 50% sulfuric acid was rougher than that of glass etched with 95% sulfuric acid. The sodium concentration of the glass boiled for 30 min in 95% sulfuric acid was nearly zero at the glass surface, and the sodium composition changed very little with annealing temperatures up to 35$0^{\circ}C$ in a vacuum environment. However the sulfur concentration at the glass surface due to the sulfuric acid increased with increasing temperature.

• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4759-4775
• /
• 2022

The RVACS is a versatile and robust safety system driven by two natural circulations: in-vessel coolant and ex-vessel air. To observe interaction between the two natural circulations, SINCRO-IT facility was designed with two different similarity laws simultaneously. Bo' based similarity law was employed for the in-vessel, while Ishii's similarity law for the ex-vessel excluding the radiation. Compared to the prototype, the sodium and air system, SINCRO-IT was designed with Wood's metal and air, having 1:4 of the length reduction, and 1.68:1 of the time scale ratio. For the steady state, RV temperature limit was violated at 0.8% of the decay heat, while the sodium boiling was predicted at 1.3%. It showed good accordance with the system code, TRACE. For an arbitrary re-criticality scenario with RVACS solitary operation, sodium boiling was predicted at 25,100 s after power increase from 1.0 to 2.0%, while the system code showed 30,300. Maximum temperature discrepancy between the experiments and system code was 4.2%. The design and methodology were validated by the system code TRACE in terms of the convection, and simultaneously, the system code was validated against the simulating experiments SINCRO-IT. The validated RVACS model could be imported to further accident analysis.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.68 no.2
• /
• pp.35-46
• /
• 2023

The transplanting period limit considering the rice yield in the Dague region, the inland plains of Gyeongsangbuk-do, was estimated to be July 15^th for early and mid-maturing rice and July 5^th for mid-late maturing rice. However, as the transplanting time was delayed, the characteristics of rice starch changed significantly. In the case of early and mid-maturing rice varieties, the starch granule size increased as the transplanting time was delayed; the opposite tendency was observed for mid-late maturing varieties. In all mature rice types, the late transplanting resulted in a longer pasting time and a higher pasting temperature. In addition, the peak viscosity, breakdown, and gelatinization temperature were significantly lowered, the relative crystallinity degree decreased, and the setback was significantly increased. In the case of Ilpum, a mid-late maturing rice variety, the distribution of amylopectin short chains tended to increase when rice was transplanted on June 30^th.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.23 no.3
• /
• pp.263-274
• /
• 2020

In the Southeast Sea of Korea, a cold water mass is formed intensively in summer every year, causing frequent abnormal sea conditions. In order to analyze the spatial changes of sea surface temperature distribution in this area, ocean fields buoy data observed at Gori and Jeongja and reanalyzed sea surface temperature(SST) data from GHRSST Level 4 were used from June to September 2018. The buoy data were used to analyze the time-series water temperature changes at two stations, and the GHRSST data were used to calculate the daily SST variance and weighted mean center(WMC) across the study area. When the buoy's water temperature was lowered, the variance of SST in the study area trend to increase, but it did not appear consistently for the entire period. This is because GHRSST is a reanalysis data that does not reflect sensitive changes in water temperature along the coast. As such, there is a limit to grasping the local small-scale water temperature change in the coast or detecting the location and extent of the cold water zone only by the statistical variance representing the SST change in the entire sea area. Therefore, as a result of using WMC to quantitatively determine the spatial location of the cold water mass, when the cold water zone occurred, WMC was located in the northwest sea area from the mean center(MC) of the study area. This means that it is possible to quantitatively identify where and to what extent the distribution of cold surface water temperature appears through SST's WMC location information, and we could see the possibility of WMC's use in detecting the scale of cold water zones and the extent of regional spread in the future.

• Journal of Environmental Science International
• /
• v.20 no.8
• /
• pp.943-951
• /
• 2011

We investigated the effects of temperature changes on the oxygen consumption rhythm in Japanese eels, Anguilla japonica, using an automatic intermittent flow respirometer (AIFR). The endogenous rhythm of the oxygen consumption rate (OCR) in the eels (n = 18; 44-74 cm, 145-690 g), freshly collected by bag net from estuaries, was nearly synchronous with the tidal pattern of the estuarine collection site. The magnitude of mean OCR (mOCR) of eels showed variable range of 82.2 - 116.5 ml $O_2\;kg^{-1}ww \;h^{-1}$ under constant conditions. In case of increasing temperature from 25 to $38^{\circ}C$, the OCR of eels exhibited a gradually increasing trend with a rhythmic pattern until $36^{\circ}C$. Above $36^{\circ}C$ the rhythms of the OCR dampened and the OCR decreased rapidly at around $36-37^{\circ}C$. The OCR of the eels exhibited the maximum value at $38^{\circ}C$, and then it sharply decreased. The results suggested that the critical thermal maximum (CTM) regarding the endogenous rhythms of the eels was at around $36-37^{\circ}C$ when water temperature increased at $0.5^{\circ}C$/14 h following the acclimation at $25^{\circ}C$. In case of decreasing temperature ($0.5^{\circ}C$/14 h) from 25 to $0^{\circ}C$, the OCR of the eels displayed a abrupt decrease up to $23^{\circ}C$, and between at 23 and $20^{\circ}C$, there was an agitation which showed a slight increase in the OCR with a duration of 1-2 days. Below $9^{\circ}C$, the OCR rhythm of the eels showed a constant state regardless of temperature decreasing. These results suggest that the Japanese eel has an upper incipient lethal temperature at $36^{\circ}C$, with a lower thermal limit at $9^{\circ}C$. The biochemical aspects of the eels influenced by water temperature need to be further studied.

• Journal of Energy Engineering
• /
• v.25 no.1
• /
• pp.113-121
• /
• 2016

Polymer electrolyte membrane fuel cell(PEMFC) requires cooling system to maintain the proper operating temperature(about $65^{\circ}C{\sim}75^{\circ}C$) because the efficiency and power are affected by operating temperature. In order to retain the operating temperature of PEMFC, cooling system and coolant control logic are needed. Hardware-in-the-loop simulation(HILS) is one of effective methods to study and evaluate control algorithm. In this paper, the HILS system was designed to study the coolant control algorithm. The models of HILS system consisted of PEMFC, heat exchanger, and external environment associated with temperature. The hardwares in HILS system are 3-way valves, pumps, and a heat exchanger. The priority control and the control target temperature were investigated to improve the control performance using HILS. The 3-way valve in $1^{st}$ cooling circuit was selected as priority control target. The under limit value of $2^{nd}$ 3-way valve set as a function of PEMFC power and $2^{nd}$ circuit coolant temperature to correct temperature control performance. As a result, the temperature of PEMFC is stably controlled.

• Korean Journal of Ichthyology
• /
• v.30 no.3
• /
• pp.131-136
• /
• 2018

Decrease in seawater temperature during winter is one of the most important and serious issues confronted by fish net-cage aquaculture farms. This can become the cause of the manifestation of diseases and ensuing mass mortality. The present study was conducted to assess the survival rate, the range of limited low-temperature, the response of oxidative stress in the blood of red sea bream Pagrus major with decrease of water temperature. Low-lethal temperature for 7 days of P. major ($7day-LT_{50}$) was $6.54^{\circ}C$ (confidence limit: $6.31{\sim}6.71^{\circ}C$). Oxygen consumption rate was decreased with lower temperature. It showed the minimum value at the range of low-lethal temperature. Osmolality at $5^{\circ}C$ and $6^{\circ}C$ experimental group was higher significantly than control group. SOD (superoxide dismutase) activity was increased significantly at $5^{\circ}C$ experimental group compared to control group. This study data will be used to determine the appropriate area for aquaculture of red sea bream. It also manage fish net-cage farm to cope with the mass mortality occurring frequently during winter season.

• Archives of Pharmacal Research
• /
• v.23 no.1
• /
• pp.26-30
• /
• 2000

The enantiomers of the bronchodilator terbutaline were separated by reversed-phase high performance liquid chromatograhy after derivatization with 2,3,4,6-tetra-O-acetyl-\beta-D-glucopyranosyl isothiocyanate(GITC) reagent. The derivatization proceeded quantitatively within 1 h at room temperature. The corresponding diastereomeric thiourea derivatives were well resolved on an ODS column with acetonitrile-acetate buffer as a mobile phase. Elution orders of the diastereomers were confirmed by derivatization of R-(-)-terbutaline and S-(+)-terbutaline which were collected by semi-preparative chiral HPLC using Sumichiral OA-4700 column. The native fluorescence of terbutaline was quenched by derivatization with GITC. The detection limit was 25ng when monitored at UV 278 nm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.399-402
• /
• 2009

The Clad sheet is made roll-bonding process of the one or more material with the different property. Good formability is an essential property in order to deform a clad metal sheet to a part or component. In this study, the mechanical properties and formability of a Mg-Al-SUS clad sheet are investigated. The clad sheet was deformed at elevated temperatures because of its poor formability at room temperature. Tensile tests of the each material and clad sheet were performed at various temperatures and at various strain rates. The limited draw ration (LDR) was obtained using a deep drawing test to measure the formability of the clad sheet. A finite element (FE) analysis was performed to predict formability of the cup drawing product, one_layer model and three_layer model.

• Fire Science and Engineering
• /
• v.22 no.3
• /
• pp.246-251
• /
• 2008

Oil Fire easily generates fire in the pressure of the atmosphere and below the normal temperature. Because these discharge flammable gas and ignite within the combustibles limit in conditioning to be assisted air and an invariable density. But Kitchen Fire shows very specific properties of matter and energy Qualification in most cases even though the same oil fires occured. In this Paper, around these specific character that Kitchen Fire have Properties of matter or energy Qualification studied on the genetic mechanism and counter measure scheme.