• 설비공학논문집
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• 제20권7호
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• pp.508-516
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• 2008

Fault detection and diagnosis(FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. An experimental study has been performed on fault detection and diagnosis method for a water chiller. Bayes classifier, which is one of classical pattern classifiers, is adopted in deciding whether fault occurred or not. Failure modes in this study include refrigerant leakage, decrease in mass flow rate of the chilled water and cooling water, and sensor error of the cooling water inlet temperature. It is possible to detect and diagnose faults in this study by adopting FDD algorithm using only four parameters(compressor outlet temperature, chilled water inlet temperature, cooling water outlet temperature and compressor power consumption). Refrigerant leakage failure is detected at 20% of refrigerant leakage. When mass flow rate of the chilled and cooling water decrease more than 8% or 12%, FDD algorithm can detect the faults. The deviation of temperature sensor over $0.6^{\circ}C$ can be detected as fault.

• 한국수소및신에너지학회논문집
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• 제24권1호
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• pp.70-75
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• 2013

It has fabricated membrane electrode assemblies (MEA) for proton exchange membrane fuel cell by hot-pressing method. The hot-pressing was used for the fabrication of MEA which is composed of commercial platinum electrode on carbon paper. The performance of MEA was studied with different fabrication conditions of temperature, pressure and torque. As the temperature increased, the performance of MEA was increased. and started to decrease l after arrived at the maximum performance of MEA. This is related with good contact between electrode and polymer electrolyte membrane at high temperature and microstructural change at much higher temperature. Similarly, as the pressure increased, the performance of the MEA increased up to highest values and start to decrease. According to the our results, the maximal performance of the MEA was at the temperature of $140^{\circ}C$ and the pressure of $1.5{\times}10^3$ kPa. The optimal torque to assemble the single stack was 3.2 N m.

• 한국주조공학회지
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• 제12권6호
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• pp.450-457
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• 1992

The study aims to investigate the influence of alloying elements(V,Ti) and heat treatment on the mechanical properties in hypo-eutectic chromium cast iron. Before heat treatment, all of the specimen were fully annealed(950$^{\circ}C{\times}5Hr$) to homogenize their structures. The influence of heat treatment and alloying elements(V,Ti) on hardness, retained austenite volume, and charpy impact energy as well as tensile strength of the specimen was tested systematically. Retained austenite decreased with the increase of V and Ti, but incresed with the increase of number of cycles. The impact energy decreased, and hardness and tensile strength increased with the increase of alloying elements (V,Ti) and the decrease of the number of cycles. The hardness and tensile strength increased, but impact energy decreased with the increase of V and Ti elements and the temperature of destabillization heat treatment. After the destabillization heat treatment at the same temperature, the impact energy is increased, while hardness and tensile strength decreased as the increase of tempering temperature. Retained austenite increased with increase of destabilizatoin heat treatment temperature, while decrease with the increase of tempering temperature.

• Tribology and Lubricants
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• 제39권2호
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• pp.76-80
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• 2023

This paper describes an experimental investigation of the effect of cooling flow rate on gas foil thrust bearing (GFTB) performance. In a newly developed GFTB test rig, a non-contact type pneumatic cylinder provides static loads to the test GFTB and a high-speed motor rotates a thrust runner up to the maximum speed of 80 krpm. Force sensor, torque arm connected to another force sensor, and thermocouples measures the applied static load, drag torque, and bearing temperature, respectively, for cooling flow rates of 0, 25, and 50 LPM at static loads of 50, 100, and 150 N. The test GFTB with the outer radius of 31.5 mm has six top foils supported on bump foil structures. During the series of tests, the transient responses of the bearing drag torque and bearing temperature are recorded until the bearing temperature converges with time for each cooling flow rate and static load. The test data show that the converged temperature decreases with increasing cooling flow rate and increases with increasing static load. The drag torque and friction coefficient decrease with increasing cooling flow rate, which may be attributed to the decrease in viscosity and lubricant (air) temperature. These test results suggest that an increase in cooling flow rate improves GFTB performance.

• Asian-Australasian Journal of Animal Sciences
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• 제10권6호
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• pp.652-656
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• 1997

This study was conducted to determine the relationships between abdominal temperature (Tabd) and some thermoregulatory responses, such as heat production (HP), heart rate (HR), respiration rate (RR), temperature of external ear tract (Tee), comb surface temperature (Tcs) and shank skin temperature (Tss), for revealing the role of deep body temperature in the thermoregulation of broiler chickens. Tabd was divided into 5 zones of 40-41, 41-42, 42-43, 43-44 and $44-45^{\circ}C$, and maintained for 3 hours in each zone by varying environmental temperature from 11 to $33^{\circ}C$. HP and HR had a greater increase with Tabd above $42.5^{\circ}C$. RR increased markedly with Tabd above $41.5^{\circ}C$, and reached a maximum when Tabd was at $42.5^{\circ}C$, then began to decrease. In addition, HP and HR increased significantly with decrease RR during the decreasing phase of panting. Tcs and Tss changed rapidly with Tabd when Tabd was below $41.5^{\circ}C$, and increased more slowly above $41.5^{\circ}C$. Tee was lower than Tabd, and its increase was less than that of Tabd. These results suggest that changes in thermoregulatory responses are induced by an increase in abdominal temperature. Tabd increases to adjust the ratio of sensible and evaporative heat loss when Tabd is below $42.5^{\circ}C$, while the ability in body temperature regulation gradually disappears when abdominal temperature exceeds $42.5^{\circ}C$ and heat balance can not be maintained.

• 대한임상전기생리학회지
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• 제5권2호
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• pp.61-72
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• 2007

INTRODUCTION: Local heat and cold application has been frequently used as means of muscle relaxation and blood circulation or reinforcing muscle strength, relaxing muscle tension in clinical situation. In particular, it has been known that long-term heat and cold application for relaxing muscle tension inhibits muscle spasticity or tension. But, it has been rarely reported that what influences of heat and cold application on activation of muscle action potential. Therefore, this study aims to analyze surface temperature and electromyography activities according to the heat and cold application. METHODE: Subjects of this research were 10 normal men and women (5 men, 5 women). Hot pack and cold pack was applied to vastus medialis muscle of thigh and rectus femoris muscle for 20 min. Surface temperature of vastus medialis muscle and rectus femoris muscle was measured, knee joint of subjects was in $45^{\circ}$ flexion, sitting on a chair, maximal isometric contraction was induced, surface electromyography (sEMG) signals were collected and root mean square (RMS) and median frequency (MOF) were analyzed. All measurements were conducted before and immediately after experiment, 10 min., 20 min. and 30 min. after experiment. Data were analyzed with SPSS 12.0 program, comparison of changes in superficial temperature and sEMG signals through repeated measurement was conducted with repeated measures ANOVA and significance level $\alpha$ was 0.05. RESULTS: Changes of surface temperature of vastus medialis muscle according to cold application were radically decreased immediately after application, but it was recovered after 30 min. of application and it showed significant difference (F4. 36=72.216, P<0.001). Surface temperature of rectus femoris also showed radical decrease immediately after application, but it was recovered after 30 min. of application and showed significant difference (F4. 36=88.930, P<0.001). Changes of surface temperature of vastus medialis muscle according to heat application were radically increased immediately after application, but it was recovered after 30 min. of application and it showed significant difference (F4. 36=27.267, P<0.001). Surface temperature of rectus femoris also showed radical decrease immediately after application, but it was recovered after 30 min. of application and showed significant difference (F4. 36=19.774, P<0.001). Changes of sEMG by heat and cold application were no statistical difference. Surface temperature of skeletal muscle after heat and cold application showed significant change for 30 min., but it was found that increase or decrease of surface temperature had not great influence on sEMG activities.

• 대한한의학회지
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• 제39권1호
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• pp.22-34
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• 2018

Objectives: The purpose of this study is to investigate changes of the marker compounds and anti-inflammatory effect of Gamisoyo-san decoction (GMSYS) depending on storage temperature and periods. Methods: GMSYS was stored at room temperature or refrigeration for 12 months. According to storage temperature and periods, pH and sugar content of GMSYS were measured. To determine the marker compounds of GMSYS, high-performance liquid chromatography analysis was performed. To estimate the anti-inflammatory effect of GMSYS, LPS-induced pro-inflammatory mediators and cytokines were measured in RAW 264.7 cells. Results: There was no change in pH and sugar content depending on storage temperature and periods of GMSYS. The contents of gallic acid and mangiferin in both of room temperature and refrigerated decoctions reduced with increasing storage periods. Chlorogenic acid was time-dependently decreased in case of stored at room temperature. GMSYS significantly inhibited the LPS-induced production of nitric oxide, prostaglandin $E_2$ ($PGE_2$) and IL-6 in RAW 264.7 cells. These effects equally maintained up to 3 months at both of room temperature and refrigeration. Since 4 months, the inhibitory effect of GMSYS on LPS-induced $PGE_2$ production was time-dependently reduced, and the decrease in $PGE_2$ inhibitory effect of decoction stored at refrigeration was lower than that of stored at room temperature. Conclusions: Our results indicate that the anti-inflammatory effect of GMSYS are maintained up to 12 months, but it shows optimal efficacy up to 3 months. It is recommended to store in a refrigeration for short periods since some components decrease as storage periods becomes longer.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.625-628
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• 2003

This paper presents the behaviors of reinforced concrete columns under high temperature. When columns are exposed high temperature, temperature distribution of a section becomes nonlinear and it is calculated by using finite difference method(F.D.M). The interaction curves show the strength of columns at various exposure times. The strength of columns decreases according to the increase of the exposure time and the decrease of concrete cover.

• 대한화학회지
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• 제15권5호
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• pp.223-228
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• 1971

In the electrolytic preparation of persulphate from sulphate solution, the current efficiency decrease with temperature increase at the platinum anode. But in case of electrodeposited lead peroxide anode, the current efficiency increase with temperature of the solution. The reason seems to be that the ozone formation is faster in platinum anode than in lead peroxide as temperature increase.

• 천문학회지
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• 제13권1호
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• pp.35-44
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• 1980

Various assumptions used in interpreting the observations of hydrogen recombination lines are critically assessed to confirm the gradient of electron temperature with distance from the galactic center. The total temperature increase from 5 to 13 kpc is about 2,500 K. Among many suggestions, we have singled out the decrease of trace dement abundances with the galactoccntric distance as the most viable cause for the temperature gradient. This will impose an important constraint on evolutionary models of the Galaxy.