• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.1
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• pp.56-62
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• 2015

The potential impact of water temperature on sea level and air temperature rise in response to recent global warming has been noticed. To predict the effect of temperature change on river water quality and aquatic environment, it is necessary to understand and predict the change of water temperature. Air-water temperature relationship was analyzed using air temperature data at Buan and water temperature data of Shinsi, Garyeok, Mangyeong and Dongjin. Maximum and minimum water temperature was predicted by neural network and the results show a very high correlation between measured and predicted water temperature.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.769-775
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• 2011

An experimental study of biofilm nitritation system for high-strength ammonium wastewater has been carried out to examine the temperature effect on different organic and solid concentration. Operating temperature varied from $35^{\circ}C$ to $15^{\circ}C$. The influent N concentration of identical three reactors was adjusted to about $300mg\;NH_4-N/L$. A control unit fed with a synthetic wastewater, while the others were fed with reject water which is consisted of the supernatant of both digester and thickener. The results indicated that nitrite accumulation was stable in temperature range of $35^{\circ}C$ to $25^{\circ}C$. However, nitritation was significantly reduced at below $20^{\circ}C$. Free ammonia (FA) and free nitrous acid (FNA) were major inhibitors to the nitrite oxidizer for nitrite accumulation in lower temperature. From the estimation of temperature coefficient (${\Theta}$) of biofilm and suspended nitritation system, biofilm nitritation system could absorb the negative temperature effect compared with suspended nitritation system.

• Journal of the Speleological Society of Korea
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• no.85
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• pp.18-20
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• 2008

To find out the natural environmental characteristics of Ondal Cave, temperature, humidity, wind speed and water temperature have been investigated. When compared to other caves, in sum, Ondal Cave has shown no significant difference interms of natural environment. Inparticular, Ondal Cave was higher than other limestone caves by 1-2$^{\circ}C$ in terms of water temperature due to high inflow of river water nearby.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.169.2-169.2
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• 2010

The research assesses the performance of the water-to-water heat pump system installed in Cheongju water treatment plant for cooling and heating ventilation. In summer season monthly averaged COP is ranged from 3.85 to 4.56 according to the water source temperature, and the performance is increased as the raw water temperature is dropped. While, heating performance is increased for the high temperature water source, and the monthly averaged COP is changed from 2.92 to 3.82. The correlation of the water source temperature and the heat pump performance shows a linear tendency by the simple regression of average data. In heating, the COP of heat pump system linearly rises according to the water source temperature. In comparison, the COP in cooling linearly reduces as the raw water temperature is raised. The goodness of fit at the simple regression shows the coefficient of determination 82% in cooling, 46% in heating. The electric cost of water-to-water heat pump is reduced by 40% compared to that of air source heat pump.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.379-380
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• 2002

Steam generators (S/G) of pressurized water reactors are large heat exchangers that use the heat from the primary reactor coolant to make steam in the secondary side for driving turbine generators. Reciprocating sliding wear experiments have been performed to examine the wear properties of Incoloy 800 and Inconel 690 steam generator tubes in high temperature water. In present study, the test rig was designed to examine the reciprocating and rolling wear properties in high temperature (room temperature - $300^{\circ}C$) water. The test was performed at constant applied load and sliding distance to investigate the effect of test temperature on wear properties of steam generator tube materials. To investigate the wear mechanism of material, the worn surfaces were observed using scanning electron microscopy. At $290^{\circ}C$, wear rate of Inconel 690 was higher than that of Incoloy 800. It was assumed to be resulted from the oxide layer property difference due to the a\loy composition difference. Between 25 and $150^{\circ}C$ the wear loss increased with increasing temperature. Beyond $150^{\circ}C$, the wear loss decreased with increasing temperature. The wear loss change with temperature were due to the formation of wear protective oxide layer. From the worn surface observation, texture patterns and wear particle layers were found. As test temperature increased, the proportion of particle layer increased.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1969-1973
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• 2007

The purpose of this study is to investigate the performance of a sea water heat source cascade heat pump system. R717(Ammonia) is used for a low-stage working fluid while R134a is for a high-stage. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. In this study, two experiments were carried out. One is a system starting test from the low load temperature of $10^{\circ}C$. The other is a system performance investigation over the R717 compressor capacity changes. Experimental results show that when it starts from the low load temperature, the suction temperature of the low-stage compressor is higher than that of a high-stage. The system performance increases when a water source temperature or a low-stage compressor rotational frequency goes higher.

• ALGAE
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• v.19 no.3
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• pp.247-255
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• 2004

This study was to clarify the variations in a marine ecosystem through examining the species composition of phytoplankton in the coastal water of Baegyado Island during winter. Water temperature, salinity, SS, NH$_4$-N, NO$_2$-N, NO$_3$-N and SiO$_2$-Si were significantly different and in inverse proportion to the chlorophyll a and species number according to stations and water depth. The total number of species was 88, composed of 94% Bacillariophyceae, 3.4% Chrysophyceae, 2.2% Dinophyceae and 1.1% Euglenophyceae. The dominant species were Rhizosolenia setigera, Skeletonema costatum and Stephanopyxis palmeriana. The maximum of standing crops was $5,450cells{\cdot}ml^(-1)$, while the minimum was $1,700cells{\cdot}ml^(-1)$. The coastal water was influenced with two water bodies which had characteristics of low water temperature - low salinity and high water temperature - high salinity.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.6
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• pp.99-105
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• 2023

Submarines, which require a high degree of survivability, are among the most critical combat weapon systems in military strategic assets. Conventional submarines need air to operate their propulsion systems. Exhaust gases released into the water during snorkel navigation heat the surrounding fluid, producing a temperature wake. This wake, in turn, reduces the submarine's survivability. In this study, we conducted a preliminary experiment on the temperature traces formed by an underwater submarine's waste discharge. For this purpose, we collected propulsion system and navigation condition data from domestically introduced submarines and developed an experimental system to measure the temperature traces. As a result, we observed that high-temperature bubbles injected into the tank broke down into smaller sizes, and their temperature dropped to levels similar to the surrounding fluid. This observation was confirmed using a thermocouple sensor. Consequently, the thermal imaging system designed to measure the temperature trace of the water's surface did not detect any significant temperature traces.

• Tribology and Lubricants
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• v.19 no.1
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• pp.21-25
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• 2003

The 440C stainless steel is used for ball bearings and bevel gears in the control rod drive mechanism for the integral reactor, SMART. The friction characteristics of 400C stainless steel a investigated in sliding motion using the reciprocating tribometer which can simulate the operating conditions of the control rod drive mechanism. Highly purified water is used as lubricant, and the water is heated and pressurized in the autoclave. Friction force on the reciprocating specimens is measured by the load cells and transformed into friction coefficient. It is verified that frictional characteristic of the 440c steel is not drastically changed up to operating temperature and variation of friction coeffcient at operating temperature from room temperature to 160$^{\circ}C$ is within 5%.

• Fashion & Textile Research Journal
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• v.19 no.5
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• pp.646-652
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• 2017

In order to clarify an availability of water treatment for persimmon extract dyeing, effect of color developing by water treatment process on cotton fabrics dyed with persimmon extract was investigated. Dyed fabrics were dipped still water and circulation water in various temperature. Concerning water color developing, still water color developing and circulation water color developing have been examined, and the temperature of water has been apprehended to prepare an effective basis of water color development. The surface color based on circulation water color development displays low values of $a^{\ast}$ and $b^{\ast}$, and the range of the c value(Munsell chroma) is narrow and has the value of 2 to 3, thus displays the coloration of a dark tone. The effect of temperature in water color development was insignificant, due to the small difference in temperature from $20^{\circ}C$ to $40^{\circ}C$. At $80^{\circ}C$, remarkable color development manifested, which is evidence of the high influence of temperature. The effects of circulation were clear at low temperatures, and the effects of temperature highly manifested at high temperatures. Circulation water color development display great color development at all temperatures to allow industrial color development with the absence of sunlight, thereby having an effect of energy reduction and developing color in dark tones, however this also is a strength of persimmon extract concerning color diversification, and is judged to have great value of industrial and practical application.