• Journal of Sensor Science and Technology
• /
• v.15 no.1
• /
• pp.7-12
• /
• 2006

The multi-functional one-chip sensor has been fabricated to reduce output variation under various water environment. There were a temperature sensor, a piezoresistive type pressure sensor, and a electrode type conductivity sensor in the fabricated one-chip sensor. This sensor was measured water depth in the range of $0{\sim}180cm$, temperature in the range of $0{\sim}50^{\circ}C$, and salinity in the range of 0 $0wt%{\sim}5wt%$, respectively. Since the change of water depth in solution environment depends on various factors such as salinity, latitude, temperature, and atmospheric pressure, the water depth sensor is needed to be compensated. We tried to compensate the salinity and temperature dependence for the pressure in water by using lookup-table method.

• Journal of Korean Society of Water Science and Technology
• /
• v.26 no.6
• /
• pp.89-97
• /
• 2018

The purpose of this reaserch is to analyze the charateristics of water quality in space through the operation of ARA River in Artificial Rivers of the Brackish Water Zone. The spatial distribution measured water temperature and salt levels for the surface, middle and deep layers by dividing the four areas of Incheon, Sicheon, Gyeyang and Gimpo. Water temperature did not vary much by water depth and branch, and its purpose is to maintain stable water environment through correlation analysis and operation. To examine the temporal and spatial distribution patterns of the Arachon, we measured DO on the Incheon branch, Sicheon, Gyeyang and Gimpo branch twice a month, and on the surface, the temperature level, The water temperature did not vary much by depth and location, and the water temperature in January and March tended to rise from Incheon to Gimpo, with the average difference of 1.1 degrees during the same period. The salinity difference between Incheon and Gimpo sites was 3.3 psu deep and 5.4 psu deep. In particular, floodgates from July to September are found to be less than 10psu overall, which is considered to be a gas due to the effects of floods and the inflow of Gulpo Stream. D.O. is located in some areas due to summer rains. The hypoxic layer has been identified.Analysis of seasonal data shows that water temperature and DO are strongly correlated in autumn. It was found that the water temperature and salt levels in the fall showed a weak correlation.

• Journal of Environmental Science International
• /
• v.21 no.2
• /
• pp.125-133
• /
• 2012

Climatological trend for the period of 1970 to 2009 in sea water temperature around the Antarctic Peninsular waters in the Southern Ocean was investigated. During the period from 1970 to 2009, sea water temperature in the top 500 m water column except 100 m increased at a rate of $0.003-0.011^{\circ}C{\cdot}yr^{-1}$, but at 100 m it decreased at a rate of $-0.003^{\circ}C{\cdot}yr^{-1}$. Although long-term trend is generally warming, there were several periods of sharp changes between 1970 and 2009. Annual mean sea water temperature between surface and 500 m except 100 m decreased from the early of 1970s to the end of 1980s, and then it increased to the end of 2000s. In the entire water column between the surface and 500 m, sea water temperature closely correlated with the El Nino events expressed as the Southern Oscillation Index(SOI), and SOI and sea water temperature have a dominant period of about 3-5 years and decade.

• Journal of Korea Multimedia Society
• /
• v.22 no.2
• /
• pp.242-249
• /
• 2019

Old people and patients with cardiovascular disease could die of a heart attack in the bath with heated water for a long time. Various researches have been studied to prevent these accidents from happening such as measuring the ECG signal when taking bath. However, these devices are hard to use and the higher price is not easily accepted by the public. In this paper, a low-cost and use-friendly, real time high precision water temperature monitoring device to prevent heart attack in the bath was developed. The device with waterproof design that lets the device can float on the surface of the water, and an accurate way to make water temperature measurement method was proposed by this paper that is immerging the sensor into water with 4cm depth to measure the temperature of underwater. The manufactured device was conducted to two experiments; one was to verify the basic functions of the device, and another one was for compare the proposed device with commercial products for monitoring the water temperature in the bathtub. As the experimental results shown, the proposed device has stable performance for the water temperature measurement and communicating with laptop in wireless.

• Journal of Korean Society on Water Environment
• /
• v.24 no.1
• /
• pp.44-53
• /
• 2008

To recognize the spatial and temporal variability of water temperature and dissolved oxygen in the Youngsan reservoir formed after dike construction, water temperature and dissolved oxygen data have been observed and analyzed from April, 2002 until March, 2003. As the results, certain stratifications were not distinctly observed in the Youngsan reservoir during summer, which was estimated due to the drainage characteristic from the Youngsan water gates. The yearly variation of water temperature in the Youngsan reservoir is shown seasonally ups and downs by the heat exchange between the atmosphere and the reservoir. On the other hand, dissolved oxygen and water temperature in the Youngsan reservoir have been shown inversed proportional correlation. As the calculation results of residence time and water exchange rate, it is considered that the feature of oxygen distribution is determined by the drainage characteristics caused the shortest residence time during summer, which also disturbed the formation of stratification in the Youngsan reservoir.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.2
• /
• pp.188-195
• /
• 2018

Time series analysis was conducted to identify the factors affecting short-term variation of water temperature in Wando. Spectrum analysis showed that air temperature peaks at diurnal period, while water temperature and tide level peak at both semi-diurnal and diurnal periods. Coherence between water temperature and the tide level presented 0.92 at semi-diurnal period. Numerical experiment were carried out to understand the spatio-temporal distribution of water temperature in the study area. Average water temperature difference between maximum ebb and flood was $0.3^{\circ}C$ in spring tide, but $0.13^{\circ}C$ in neap tide. The reason for the large difference in spring tide is that relatively cold water entered with strong tidal currents at flood tide and flowed out at ebb tide. Water temperature on coasts was higher than out at sea. This is because the depth in the coast is shallower than at sea, and water temperature increases rapidly due to solar radiation.

• Journal of Bio-Environment Control
• /
• v.25 no.4
• /
• pp.270-276
• /
• 2016

This study analysed overall heat transfer coefficient, heat transmission, and rate of indoor air heating provided by water curtain in order to determine the heat transfer characteristic of double-layered greenhouse equipped with a water curtain system. The air temperatures between the inner and outer layers were determined by the water flow rate and inlet water temperature. Higher water flow rate and inlet water temperature resulted in the increased overall heat transfer coefficient between indoor greenhouse air and water curtain. However, it was found that with higher levels of water flow rate and inlet water temperature, indoor overall heat transfer coefficient was converged about $10W{\cdot}m^{-2}{\cdot}^oC^{-1}$. The low correlation of overall heat transfer coefficient between water curtain and air within double layers was likely because the combination of greenhouse shape, wind speed and outdoor air temperature as well as water curtain affected the heat transfer characteristics. As water flow rate and inlet water temperature increased, the heat transferred into the greenhouse by water curtain also tend to rise. However it was demonstrated that the rate of heat transmission from water curtain into greenhouse with water curtain system using underground water was accounted for 22% to 28% for total heat lost by water curtain. The results of this study which quantify heat transfer coefficient and net heat transfer from water curtain may be a good reference for economical design of water curtain system.

• Corrosion Science and Technology
• /
• v.21 no.5
• /
• pp.327-339
• /
• 2022

The water-jet technique started by Bridgman can cut metal and alloys without harmful gas and fume. However, while this technique is convenient to cut metals and alloys, in the case of coated pipe, water jet induces the degradation of coatings on the pipes, and may facilitate structural failure, leakage, and loss of products. While there are many reports on the effect of water jet on cut metals and the damage of metallic materials, research on the effect of water impingement on the epoxy coatings has been little studied. In this work, we therefore control the velocity of water jet, distance between nozzle and specimen, and water temperature, and discuss the effect of water impingement on the epoxy coatings. Increasing water velocity and water temperature and reducing nozzle distance increased the degradation rates of three epoxy coatings were increased. Among three test parameters - water velocity, nozzle distance and water temperature, water temperature was relatively effective to increase the degradation rate of epoxy coatings.

• Solar Energy
• /
• v.20 no.1
• /
• pp.55-62
• /
• 2000

An experimental study on the stratified fluids with water and silicon oil of same volume in the cavity with upper cooling surface was carried out to investigate the flow characteristics, heat transfer through the interface of fluids, and the applications of thermal behaviors in a square cavity. The experiments were performed with variation of initial temperature and cooling surface temperature. The temperature drop of oil was faster than that of water and freezing was initiated from the interface of oil and water and propagated downward. For the water above $4^{\circ}C$, the cooling rate was faster than that below $4^{\circ}C$ and showed almost same temperature distribution but for the water that of below $4^{\circ}C$, it showed the stable stratified temperature distribution. The lower the initial temperature and the higher the cooling surface temperature was, the longer the supercooling duration.

• Journal of Environmental Policy
• /
• v.12 no.2
• /
• pp.17-32
• /
• 2013

The potential impact of water temperature on air temperature in response to recent anthropogenic global warming has been noticed. To predict climate, induced change in river aquatic environment, it is necessary to understand the thermal constrains of fish species and the timing of the projected river temperature. As a preliminary study, air-water temperature relationship was analyzed on the basis of the observed data during the time period of 2009-2011 and the number of data corresponds to 873-1083. As a result of analyzing the auto-and cross-correlation coefficient between air-water temperature, high correlation is shown (~0.9). It is also found that the correlation coefficient of air temperature is higher than that of water temperature at the lag time less than approximately 10 days. Observed data was divided into two groups to investigate hysteresis: rising limb and falling limb. For some stations there is strong evidence that hysteresis exist between air-water temperature relationships. Consequently it is recommended that seasonal hysteresis needs to be included in determining an airwater relationship.