• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.472-477
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• 2017

Oil spills cause a lot of damage to the environment. Oil destroys the water environment and ecosystem in a very short period of time once they are contaminated by it, it takes a lot of time to recover from the contamination and the cleaning process is very difficult. Therefore, oil detectors are greatly needed as they can monitor any oil spills over the sea, rivers, and lakes. There are two kinds of technology available for detecting oil, viz. the contact and non-contact types. The former is based on the use of the conductivity, capacitance and microwaves, while the latter employs infrared, UV, laser, optic and radar technologies. As there are also various hurdles in the measuring of oil on water, such as the presence of waves, refraction of light, temperature and saltiness, it is imperative to select the right oil detector which is appropriate for the specific environment. In this study, a contact type oil detector is developed, which can be used in oil related industries, such as refineries, petrochemical companies, and power generation stations. The detector is made up of the sensor module, which floats on the water, and the controller which processes the signal coming from the sensor module and displays it. It is designed in such a way that the existence of oil is detected through the sensor and the change in the permittivity is observed to determine the volume and type of spilled oil.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.6
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• pp.637-644
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• 2010

The purpose of this study is to analyze characteristics of water quality factor scientifically and develop the multiple regression model predicting dissolved oxygen to save periodic replacement costs for dissolved oxygen sensor. Correlation analysis using the environmental data obtained from 2 different land-based fish farms of the Geogeum-do, Geheung-gun coastal area during the periods from November 2008 to January 2009 shows that water temperature was negatively correlated with dissolved oxygen and pH butpH was positively correlated with salinity and dissolved oxygen. The information of Keumho fish farm in 2009 is presented by the tables which are monthly statistics of water quality factors and seasonable difference by the Duncan's post-test. Also we developed multiple regression model predicting dissolved oxygen, the usefulness of which was verified by the comparison graph between estimates and actual observations. The developed regression model shows that seawater temperature and salinity give negative affect to dissolved oxygen while pH gives positive affect to it. Lastly the seawater temperature has much higher explanatory power than pH factor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.374-380
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• 2022

This paper shows the results of a study that predicts changes in seawater conditions in sea farms using machine learning-based long short term memory (LSTM) algorithms. Hardware was implemented using dissolved oxygen, salinity, nitrogen ion concentration, and water temperature measurement sensors to collect seawater condition information from sea farms, and transferred to a cloud-based Firebase database using LoRa communication. Using the developed hardware, seawater condition information around fish farms in Tongyeong and Geoje was collected, and LSTM algorithms were applied to learning results using these actual datasets to obtain predictive results showing 87% accuracy. Flask and REST APIs were used to provide users with predictive results for each of the four parameters, including dissolved oxygen. These predictive results are expected to help fishermen reduce significant damage caused by fish group death by providing changes in sea conditions in advance.

• Food Science and Preservation
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• v.24 no.7
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• pp.923-933
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• 2017

This study was carried out to examine the quality characteristics of Doenjang manufactured with or without soaking Meju in brine according to salt concentrations (8 and 12%) during fermentation for 6 months. The moisture content and salinity of Doenjang fermented for 6 months were 54.9-60.3% and 7.8-12.5%, respectively. Doenjang using soaking Meju in brine had higher pH and lower titratable acidity than that using non-soaking Meju. The reducing sugar content in all samples was increased until 2 months and then decreased regardless of soaking Meju, especially that of non-soaking 8% Doenjang was the highest. The 8% low-salt Doenjang was shown the highest amino-type nitrogen content, especially the soaking Doenjang was higher than the non-soaking Doenjang. ${\alpha}$-amylase activity of all samples during fermentation were continuously decreased from 0.91-0.94 Unit/g to 0.01-0.06 Unit/g, especially the 8% soaking Doenjang was shown the highest activity after 2 months. Total bacterial count of the soaking Doenjang at the 6 months was in range of 7.8-8.0 log CFU/g and that of the non-soaking Doenjang was in range of 7.2-7.5 log CFU/g. By taste analysis, the 8% soaking Doenjang was shown the similar taste pattern with commercial Doenjang. In conclusion, the 8% low-salt Doenjang manufactured with soaking Meju in brine was a suitable concentration in order to reduce salt intake.

• Food Science and Preservation
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• v.23 no.6
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• pp.788-796
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• 2016

This study presented the change of quality characteristics of Doenjang with various salt concentrations (4, 8, 15, and 20%) during 12 months. The pHs of Doenjang during fermentation were gradually increased for 12 months, whereas the pHs of Doenjang with 4 and 8% salt increased rapidly. Titratable acidity of Doenjang with 4 and 8% salt was high at initial time, while Doenjang with 15 and 20% salt was high at the 9 and 12 months. The amino-type nitrogen content of Doenjang with 4 and 8% salt was increased and ${\alpha}-amylase$ activity of all Doenjang was decreased during whole fermentation period. The protease activity of Doenjang with 4 and 8% salt was higher than Doenjang with 15 and 20% salt until 7 months. Total aerobic bacteria number 8.0~9.1 log CFU/g for 12 months, which was steady during fermentation period. Doenjang with 8% salt showed the highest score in umami taste whereas the lowest score in bitterness, astringency, and sourness tastes between 5 and 12 months. In conclusion, Doenjang with 8% salt was a suitable concentration for low-salt fermented foods.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.329-338
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• 2019

Suction of unsaturated bentonite buffers is a very important input parameter for hydro-mechanical performance assessment and design of an engineered barrier system. This study analyzed suction measurement techniques and constitutive models of unsaturated porous media reported in the literature, and suggested suction measurement techniques and constitutive models suitable for bentonite buffer in an HLW repository. The literature review showed the suction of bentonite buffer to be much higher than that of soil, as measured by total suction including matric suction and osmotic suction. The measurement methods (RH-Cell, RH-Cell/Sensor) using a relative humidity sensor were suitable for suction measurement of the bentonite buffer; the RH-Cell /Sensor method was more preferred in consideration of the temperature change due to radioactive decay heat and measurement time. Various water retention models of bentonite buffers have been proposed through experiments, but the van Genuchten model is mainly used as a constitutive model of hydro-mechanical performance assessment of unsaturated buffers. The water characteristic curve of bentonite buffers showed different tendencies according to bentonite type, dry density, temperature, salinity, sample state and hysteresis. Selection of water retention models and determination of model input parameters should consider the effects of these controlling factors so as to improve overall reliability.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.478-488
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• 2023

This paper investigates the naval application of laser communication as a potential replacement for traditional acoustic wave communication in underwater environments. We developed a laser transceiver using Arduino and MATLAB, conducting a water tank experiment to validate communication feasibility across diverse underwater conditions. In the first experiment, when transmitting data through a laser, the desired message was converted into data and transmitted, received, and confirmed to be converted into the correct message. In the second experiment, the operation of communication in underwater situations was confirmed, and in the third experiment, the intensity of light was measured using the CDS illuminance sensor module and the limits of laser communication were measured and confirmed in various underwater situations. Additionally, MATLAB code was employed to gather data on salinity, water temperature, and water depth for calculating turbidity. Optimal wavelength values (532nm, 633nm, 785nm, 1064nm) corresponding to calculated turbidity levels (5, 20, 55, 180) were determined and presented. The study then focuses on analyzing potential applications in naval tactical communication, remote sensing, and underwater drone control. Finally, we propose measures for overcoming current technological limitations and enhancing performance.