• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.46-60
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• 2023

Climate change causes fluctuations in water quality in the aquatic environment, which can cause changes in water circulation patterns and severe adverse effects on aquatic ecosystems in the future. Therefore, research is needed to predict and respond to water quality changes caused by climate change in advance. In this study, we tried to predict the dissolved oxygen (DO), chlorophyll-a, and turbidity of the Paldang reservoir for about two weeks using long short-term memory (LSTM) and gated recurrent units (GRU), which are deep learning algorithms based on recurrent neural networks. The model was built based on real-time water quality data and meteorological data. The observation period was set from July to September in the summer of 2021 (Period 1) and from March to May in the spring of 2022 (Period 2). We tried to select an algorithm with optimal predictive power for each water quality parameter. In addition, to improve the predictive power of the model, an important variable extraction technique using random forest was used to select only the important variables as input variables. In both Periods 1 and 2, the predictive power after extracting important variables was further improved. Except for DO in Period 2, GRU was selected as the best model in all water quality parameters. This methodology can be useful for preventive water quality management by identifying the variability of water quality in advance and predicting water quality in a short period.

• KIEAE Journal
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• v.11 no.5
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• pp.91-96
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• 2011

This study is to analysis the characteristics of electric power consumption of apartments complex in Korea. This study shows the pattern of electric power consumption and correlation of each apartment complex's completion year monthly and timely. With this result, we are able to predict the demand pattern of electricity in a house and make the schedule by demand pattern. It is expected this data is used as reference of electric consumption of Daejeon area to operate the simulation tools to predict the building energy. The yearly data of 10 apartment complexes of 2010 are analyzed. The results of this study are followed. The averaged amount of electricity consumption in winter is higher as summer because of the high capacity of heating equipment. All of the house has electric base load from 0.26kWh to 0.5kWh. The average of the electricity consumption of month is shown as 310.2kWh. A week is seperated, as 4 part such as week, weekend, Saturday and Sunday. During week, the average of timely electricity consumption is shown as 0.426kWh. The Saturday consumption is 0.437kWh. The Sunday is 0.445kWh. The peak electricity consumption in summer and winter is measured. The peak consumption on summer season is 1.389kW on 22th August 64% higher than winter season 0.887kW on 3rd January.

• Ocean and Polar Research
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• v.27 no.3
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• pp.351-358
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• 2005

Reproductive condition of the tropical blacklip pearl oyster, Pinctada margaritifera collected during the period July through September 2003 from Chuuk Lagoon, Federated State of Micronesia was investigated using histology. The level of gonad development for each pearl oyster was determined with an average score of five microscopic fields, and the average score was used as the maturity index (ML). All wild pearl oysters collected in July did exhibit fully ripe eggs in their ovaries ($45{\sim}50{\mu}M$ in diameter), indicating that they were ready for spawning. In mid August most wild pearl oysters were in spawning and M1 dropped dramatically from mid- to late September, suggesting that the wild pearl oyster completed spawning during this period. In contrast, the cultivated pearl oysters collected in mid-September held ripe eggs in the ovaries and only a few of them spawned, indicating that gonad maturation of the cultivated pearl oyster was somewhat slower than that of the wild pearl oyster in Chuuk Lagoon during the summer period. Histological analysis also indicated that spawning of the pearl oyster is rather incomplete and they may spawn continuously during summer.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.399-405
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• 2005

In this study, we investigated the gas chromatography (GC) and pulsed flame photometric detection (PFPD) system for the analysis of four major reduced S compounds including hydrogen sulfide ($H_2S)$; methyl mercaptan ($CH_3SH$); dimethyl sulfide (DMS); and dimethyl disulfide(DMDS) contained in environmental samples. To analyze these compounds in high concentration range (above ppb level), we developed a high mode analytical setting with the loop-injection system. By contrast, we also established a low mode setting for the analysis of low concentration samples (ppt-level samples from ambient air) by the combination with thermal desorption unit(TDU). Comparative analysis of both settings revealed that relative detection properties of four S compounds are systematic enough. The results of high mode analysis indicated that the patterns were systematic among compounds: H2S exhibited the lowest sensitivity, while DMBS showed the strongest one. The results were also compared in terms of sensitivity reductions for all compounds by dividing slope ratios between low and high mode system. Although low mode system exhibited significant reductions on the order of a few tens times, their detection characteristics were highly consistent as it was shown in the high mode setting. To learn more about absolute and relative relations between two different modes of S analysis, future studies may have to be directed to cover more complicated nature of GC/PFPD performance. Hydrogen sulfide($H_2S$) was over in summer about low level of olfactory sense 410 ppt, Methyl mercaptan(C$H_3SH$) was over in apring and summer about low level of olfactory sense 70, Dimethyl sulfide(DMS) was not over in four season about low level of olfactory sense 2,200 ppt. Carbon disulfide($CS_2$) was not over in four deason about Tow level of olfactory sense 210,000, Dimethyl disulfide(DMDS) was not over in summer about low level of olfactory sense2,000.

• Journal of the Korean earth science society
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• v.31 no.7
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• pp.708-719
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• 2010

The Gochang-gun Dongho macro-tide pocket-type beach, located on the southwestern coast of Korea, is investigated in terms of the seasonal variations of surface sediment and sedimentary environment. Surface sediments of 45 sites in four seasons (May 2006-February 2007) are sampled across three survey lines (15 sites in each survey line). The surface sediments of the Dongho Beach are mainly composed of fine to coarse sands, and the ratio of fine sand is the largest. The average of grain size is the coarsest in the summer. The spatial distribution of surface sediments shows a coast-parallel band of fine and medium sands during three seasons of spring, fall, and winter, whereas medium sands dominated in the northern part of the study area during the summer. These results suggest that a tide is more effective than a wave in the surface sediments of the Dongho Beach during the summer.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.7
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• pp.1019-1029
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• 1999

In order to find out the influences upon not only the thermal resistance of human body but also the clothing action and the clothing weight which are caused by the differences in the thermal living conditions by using air conditioner and so on to adapt themselves to the changes of their residential environment according to the changes of seasons we investigated the clothing practices upon the male and female students in Seoul and Korean male and female students in Yanbian who are estimated to have different thermal living conditions in spite that they are same folk as well as living in the same age. 1. The total clothing weight of body surface erea was increased in order of summer autumn spring and winter seasons and by seasons the changes of the clothing weight were found in both areas, In Seoul the changes of upper outwear clothing weight were found on both sexes but in Yanbian the changes of underwear weight were found on both sexes. And the underwear weight of both sexes in Seoul was lighter than that of both sexes in Yanbian. 2. Those in Seoul tended to fell colder in winter and hotter in summer than those in Yanbian on account that the formers are more sensitive of thermal conditions than the latters. 3. Comparing clo-value claculated by the fomula of with the Winshlow's clo-value those in Yanbian had higher thermal resistance than those in Seoul. Consequently those in Seoul adapted thermselves to the seasons by controling the upper outwear weight but those in Yanbian did it with underwear weight, The male and female students in Seoul tended to feel colder in winter and hotter in summer than hose in Yanbian because the thermal sense of the former is more sensitive than that of the latter.

• Ocean and Polar Research
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• v.32 no.2
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• pp.97-111
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• 2010

Phytoplankton production is affected by various physico-chemical factors of environment. However, one of the most critical factors generally accepted as controlling primary production of phytoplankton is nutrients. It has recently been found that the succession of phytoplankton groups and species are closely related to the chemical properties of ambient water including nutrient limitation and their ratios. In Jangmok Bay, silicate and nitrate are primarily supplied by rainfall, while phosphate and ammonia are supplied by wind stress. Typhoons are associated with rainfall and strong wind stress, and when typhoons pass through the South Sea, such events may induce phytoplankton blooms. When nutrients were supplied by heavy rainfalls during the rainy season and by summer typhoons in Jangmok Bay, the dominant taxa among the phytoplankton groups were found to change successively with time. The dominant taxon was changed from diatoms to flagellates immediately after the episodic seasonal events, but returned to diatoms within 3~10 days. Pseudo-nitzschia spp. were dominant mainly in the presence of low phosphate levels during the first of the survey which included the rainy season, while Skeletonema costatum was dominant when phosphate concentrations were high due to the strong wind stress during the latter half of the survey as a result of the typhoon. The competition between S. costatum and Chaetoceros spp. appeared to be regulated by the silicate concentration. S. costatum preferred high silicate and phosphate concentrations; however, Chaetoceros spp. were able to endure low silicate concentrations. These results implied that, in coastal ecosystems, the input patterns of each nutrient supplied by rainfall and/or wind stress appeared to contribute to the summer succession of phytoplankton groups and species.

• Fisheries and Aquatic Sciences
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• v.8 no.1
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• pp.38-42
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• 2005

We evaluated the effects of different feeding strategies on the growth of young Nile tilapia, Oreochromis niloticus L., in a freshwater recirculating system during summer. Each of twenty fish (Mean body weight$\pm$ SD; 37. 7$\pm$0.10 g) were randomly distributed into each of 24 tanks. Eight treatments were prepared in triplicate. Control fish were hand-fed commercial feed twice daily without starvation. The other seven treatments employed different feeding and starvation strategies ranging from I day starved and 1 day fed (1DS+ 1DF) to 7 days starved to 7 days fed (7DS+7DF). All fish survived to the end of the 44-day feeding trial. The amount of food supplied was highest for the control fish in the control. Food supplied to fish in the 3DS+3DF and 4DS+4DF treatments was significantly lower than that of fish in the 1DS+1DF and 2DS+2DF treatments, but significantly higher than that of fish in the 5DS+5DF, 6DS+6DF and 7DS+7DF treatments. The weight gain of control fish was significantly higher than that of fish in other treatments. Feed efficiency ratio (FER) for fish in the 7DS+7DF treatment was significantly higher than that of fish in the control group, but it did not differ from that of fish in the 1DS+1DF and 2DS+2DF treatments. We concluded that young Nile tilapia raised with different starvation and feeding regimes during the summer in a freshwater recirculating system did not catch up in growth to fish fed daily. However, the enhanced FER of Nile tilapia in the 7DS+ 7DF, 2DS+ 2DF, and 1 DS+ I DF treatments partly explains the compensatory growth of the fish, although their weight gain was relatively low.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.4
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• pp.251-256
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• 2005

For blood cockle Tegillarca granosa acclimated to winter and summer seasons, survival, temperature tolerance and physiological changes at different individual size were investigated for their temperature tolerances by increasing and decreasing temperature at a rate of 1, 2 and $3^{\circ}C/day$. The survival rate of adults and juveniles T. granosa acclimated to winter temperatures began to decrease from $32^{\circ}C$ and all experimental animals died between $37-39^{\circ}C$. In the case of animals acclimated to summer temperatures, the survival rates of adults and juveniles began to decrease from $35^{\circ}C$, and all died at temperatures between $40-44^{\circ}C$. The upper $LT_{50}$ was $27.72^{\circ}C$ for adults and $28.36^{\circ}C$ for juveniles. On the other hand, when the temperature was decreased from $4^{\circ}C\;to\;0^{\circ}C$ in order to investigate lower temperature tolerances, the survival rate of T. granosa was more than $70\%\;at\;2^{\circ}C$ for 25 days. Lower L T 50 was $2.09^{\circ}C$ for adults and $2.34^{\circ}C$ for juveniles. There was no effective difference in temperature tolerance between adults and juveniles. Filtration and respiration rates of T. granosa showed a similar aspect with increase and decrease of temperature. Filtration and respiration rates exhibited irregular conditions of a broken biological rhythm as the group acclimated to winter $(10 ^{\circ}C)$ and summer $(25^{\circ}C)$. In the case of decreasing temperature, filtration and respiration rates of T. granosa reduced to a minimum below $6^{\circ}C$

• Journal of the Ergonomics Society of Korea
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• v.35 no.1
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• pp.1-10
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• 2016

Objective: This study aimed to find good design for summer functional farm shoes under the agricultural environment and working characteristics, which can help safe farm work and further promote the efficiency of working. Background: Most accidents at farms were overturn accidents caused by slipping or falling, and it was found that the main factors which caused the overturn accidents were inappropriate work shoes for the working conditions. These inappropriate work shoes often cause overturn accidents in the rural areas with steep paths. Method: A survey on work shoes was conducted with 174 farmers, and the outcome of this survey was used to find problems of work shoes and improvement ideas for the design of work shoes which can be used at farms. Results: Regarding the form of farm shoes, the ankle height was set at 6 inches to prevent the bending of the ankle and the inflow of foreign substances. The size and groove of the pattern of the outsole were extended to prevent catching of foreign substances. In the upper part, polyurethane and cordura were used in combination to secure air permeability, which was pointed out as the reason for the discomfort during the work wearing existing work shoes. Conclusion: Since farmers felt discomfort with the shoes which they were currently wearing, this study suggested a design of farm shoes by analyzing the important matters of the work shoes in development in order to improve such discomfort. Application: This study can help develop farm shoes that would practically ease farmers' burden of working at farm worksites and keep them safe.