• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.148-157
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• 1981

This experiment was carried out to evaluate the sanitary quality of sea water at popular swimming beaches such as Haeundae, Kwanganri and Songjeong which are located in the suburbs of Busan Korea. One hundred and seventy five sea water samples were collected from the 25 stations during the both summer seasons in 1979 and in 1980. The sampling stations were established in the above 3 swimming beaches and the estuary of Suyeong river (See Fig.1.). To evaluate the sanitary quality, coliform group, fecal coliform, viable cell count and Vibrio parahaemolyticus were observed. The median value of coliform group MPN of the samples ranged 2,300 to 6,500/100m1 in Kwanganri, 670 to 910/100m1 in Haeundae and 430 to 460/100m1 in Songjeong swimming beach. Geometric mean of fecal coliform MPN was 3,200/100m1 in Kwanganri, 500/100m1 in Haeundae and 360/100m1 in Songjeong swimming beach. Composition of coliform was $23\%$ Escheri-chia coli group, $20\%$ Citrobacter freundii group, $41\%$ Klebsiella aerogenes group and $16\%$others. The density of Vibrio parahaemolyticus in Kwanganri was much higher than those of in other beaches by 5 to 6 times. Plate count of the samples in the estuary of Suyeong river was varied from 300 to $8.5\times10^6/ml$ during the study period. No remarkable difference was observed in bacterial density by tide in swimming beaches but the bacterial density of sea water at ebb tide was obviously higher than those of the samples at flood tide in the estuary of Suyeong river.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.220-230
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• 1992

Soil temperature is one of the important environmental factors which control all the physical, chemical and biological processes in soil including germination and root growth of plants and other organisms living in the soil ecosystem. Soil water and nutrient availability and mobility are temperature dependent. Soil temperature change is depended primarily upon energy exchange in soil surface, meteorological variance and physical properties of the soils which are closely related to heat transfer mechanism. In this study physical properties including bulk density, soil texture and organic matter content were measured and thermal diffusivity on the soils was calculated. Soil samples from the 66 meteorological stations under the Korea Meteorology were collected and the physical parameters were measured. To obtain relationship between thermal diffusivity and soil water content a heat probe thermal diffusivity measurement apparatus was designed and used in this experiment. According to the survey on soil physicsal properties on the 66 meteorological stations, the 52% of the surface soil texture were sandy loam and laomy sand or sand, 38% were loam and silty loam, and 10% were clay loam and silty clay loam. The bulk density which was closely related with thermal properties showed average of $1.41g/cm^3$ for sandy soils, $1.33g/cm^3$ for loam and silty loam soils, and $1.21g/cm^3$ for clay loam and silty clay loam soils. The apparent thermal diffusivity of the upper layer from 0 to 30cm ranged from 1.16 to $8.40{\times}10^{-3}cm^3/sec$ with average of $3.53{\times}10^{-3}cm^3/sec$. The apparent thermal diffusivities of the Jeju soils of which organic matter contents were high and the bulk densities were low were near $2{\times}10^{-3}cm^3/sec$. The thermal diffusivity of snow measured in Chuncheon ranged from 0.822 to $2.237{\times}10^{-3}cm^3/sec$. The damping depth calculated from the thermal diffusivity ranged from 5.92 to 13.65cm for daily basis and 124 to 342cm for yearly basis. The significant regression equation to estimate thermal diffusivity with bulk density and soil water content was obtained by the heat probe in laboratory.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1739-1756
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• 2021

Atmospheric nitrogen dioxide (NO₂) is mainly caused by anthropogenic emissions. It contributes to the formation of secondary pollutants and ozone through chemical reactions, and adversely affects human health. Although ground stations to monitor NO₂ concentrations in real time are operated in Korea, they have a limitation that it is difficult to analyze the spatial distribution of NO₂ concentrations, especially over the areas with no stations. Therefore, this study conducted a comparative experiment of spatial interpolation of NO₂ concentrations based on two linear-regression methods(i.e., multi linear regression (MLR), and regression kriging (RK)), and two machine learning approaches (i.e., random forest (RF), and support vector regression (SVR)) for the year of 2020. Four approaches were compared using leave-one-out-cross validation (LOOCV). The daily LOOCV results showed that MLR, RK, and SVR produced the average daily index of agreement (IOA) of 0.57, which was higher than that of RF (0.50). The average daily normalized root mean square error of RK was 0.9483%, which was slightly lower than those of the other models. MLR, RK and SVR showed similar seasonal distribution patterns, and the dynamic range of the resultant NO₂ concentrations from these three models was similar while that from RF was relatively small. The multivariate linear regression approaches are expected to be a promising method for spatial interpolation of ground-level NO₂ concentrations and other parameters in urban areas.

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.227-233
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• 2007

The amount of Batillus cornutus captured in Jeju Island was about 2,000 tons/year for three years after 2000. The mean size of B. cornutus by shell height was 7.7 cm in 2001, 7.9 cm in 2002, and 8.1 cm in 2003. Local mean size of B. cornutus by shell height was 8.7 cm in eastern waters, 7.4 cm in western waters, 7.8 cm in southern waters, and 7.7 cm in northern waters of Jeju Island. To investigate the effect of the growth pattern, an experiment was conducted: the samples were tagged and released in southern coastal waters of Jeju Island on 2nd April (a release test) and 29th October (a recapture test) in 2003. The release stations were two sites, natural reef and artificial reef, where their environmental conditions were different from each other. In April, the size of B. cornutus released in the natural reef was 6.2 cm in mean shell height, and 58.9 g in mean shell weight. The size of B. cornutus released in the artificial reef was 6.6 cm in mean shell height, and 65.9 g in mean shell weight. During the release period, most of B. cornutus were not moved much (less than 10 m) from the original release sites. When B. cornutus was recaptured in October after 7 months, the size of B. cornutus released in the natural reef became 7.4 cm in mean shell height, and 89.4 g in mean shell weight. The size of B. cornutus released in the artificial reef became 7.2 cm in mean shell height, and 84.9 g in mean shell weight. This indicates that the growth rate of B. cornutus released in the natural reef was higher than that of B. cornutus in the artificial reef. These differences in the growth of B. cornutus between study sites were ascribed to the abundance of marine algae grazed by immobile B. cornutus. Namely, with relatively high growth rate of B. cornutus in the natural reef, the number of species (23 species) and biomass (26,703.4 g) of algae were more diverse and abundant than those (7 species and 17,018.4 g) of algae in the artificial reef. The growth of B. cornutus in the natural reef was also correlated to high water temperature $(15.5-25.9^{\circ}C)$.

• Journal of Aquaculture
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• v.7 no.4
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• pp.251-264
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• 1994

To study the causes of occurring toxic dinoflagellate Alexandriwn species, an experiment was undertaken in Jinhae Bay shellfish harvesting areas. The water and sediment samples were collected to record the abundance of Alexandriwn species, and to study the distribution and the germinability of those benthic cysts from September 1993 to July 1994. Alexandrium species were began to appear at all the sample stations after January, and reached maximum concentration (530 cells/l) at Taekok station (Chilcheon-do) in March 1994. Alexandrium cysts were also found at every station surveyed, of which several sites showed the higher concentration of 700-800 $cysts/cm^3$ at the upper sediment profile (0-4cm), but the concentrations were wide range of 100-800 $cysts/cm^3$. The results of each sampling season showed a great difference in the cyst germination experiments, were potentially high in cold season; $72.5\%$ (Jan.), $68\%$ (Apr.),$44\%$(Jul.), and $9\%$ (Oct.). These results suggested that germination of Alexandrium resting cysts in 15 m depth of coastal waters in Jinhae Bay would be controlled by a seasonal endogenous clock instead of the general environmental factors like temperature. Therefore, it is possible that Alexandrium species could be abundant by the germination of resting cysts in cold season, and contribute to the regional paralytic shellfish poisoning (PSP) toxification.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.1
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• pp.72-77
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• 1985

This study was performed to obtain some basic informations about the effects of irrigation water on the growth of rice plant. The water quality was surveyed at six pumping stations from the Nam river tributary to the downstream of Nakdong river, and sampling sites of soil and plant were five paddy fields near-by each station during rice growing periods in 1983. 1. Average value of COD was 5.1-7.1 ppm at 2 sites of the Nam river tributary, 11.4 ppm at 1 site of the midstream and 9.1-13.4 ppm at 3 sites of the downstream of Nakdong river. 2. The relationships between irrigation water and soil were $r=0.98^{**}$ for EC and $r=0.91^*$ for SAR, but the rest components did not. 3. Root activity of rice plant was low tendency as go by go the downstream of Nakdong river, and it was related to dry matter of rice plant ($r=0.62^{**}$), SAR ($r=-0.67^{**}$), and EC ($r=-0.62^{**}$) of soils.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.48-54
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• 2008

Biochemical weapons, called as a poor nation's nuclear-weapon, are most favorable Weapons of Mass Destruction(WMD). At the beginning of war, these biochemical weapons, which can threaten the operations of our forces and cause the anxiety and chaos of people, should be used to attack our principle facilities. And these attacks might be conducted as a long term scenario over the war. Consequentially, our military training as well as civilian-military joint training have been focused on these circumstances to improve defense capability against the invasion of biochemical weapons. Add to these efforts, there have been a lot of researches to develop advanced decontaminations that can secure our troops and equipments. In this study, applicability of the water-soluble decontaminant for the contaminated aircraft was evaluated. The water-soluble decontaminant has been applied to the military stations and ground weapon systems only. According to the theoretical analyses and published papers, the water-soluble decontaminant has been shown better decontamination capability than commercial cleaner by roughly 50%. Furthermore, as a result of experiment efforts in this study, it was showed that the water-soluble decontaminant can reduce corrosion risk which is primary concern for the aircraft structures.

• International Journal of Aeronautical and Space Sciences
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• v.10 no.1
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• pp.75-82
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• 2009

In this parer, we propose a new way of improving DGNSS service using combination of multiple SBAS information. Because SBAS uses Geostationary Earth Orbit (GEO) satellites, it has very large coverage but it can be unavailable in urban canyon because of visibility problem. R. Chen solved this problem by creating Virtual Reference Stations (VRS) using the SBAS signal [1]. VRS converts SBAS signal to RTCM signals corresponding its location, and broadcast the converted RTCM signals over the wireless internet. This method can solve the visibility problem cost effectively. Furthermore it can solve DGNSS coverage problem by creating just a transmitter instead of a reference station. Developing above method, this paper proposes the methods that integrate two or more SEAS signals into one RTCM signal and broadcast it. In Korea, MSAS signal is available even though it is not officially certified for Korean users. As a Korean own SBAS-like system, there is the internet-based KWTB (Korean WADGPS Test Bed) which we developed and released at ION GNSS 2006. As a result, virtually two different SBAS corrections are available in Korea. In this paper, we propose the integration methods for these two independent SBAS corrections and present the test results using the actual measurements from the two systems. We present the detailed algorithm for these two methods and analyze the features and performances of them. To verify the proposed methods, we conduct the experiment using the logged SBAS corrections from the two systems and the RINEX data logged at Dokdo monitoring station in Korea. The preliminary test results showed the improved performance compared to the results from two independent systems, which shows the potential of our proposed methods. In the future, the newly developed SBASs will be available and the places which can access the multiple SBAS signals will increase. At that time, the integration or combination methods of two or more SBASs will become more important. Our proposed methods can be one of the useful solutions for that. As an additional research, we need to extend this research to the system level integration such as the concept of the decentralized W ADGPS.

• Journal of Korea Water Resources Association
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• v.32 no.5
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• pp.547-555
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• 1999

The economical manufacturing process of fluorescent sediments (FS) which makes use of the understanding of coastal sediment path has been suggested with respect to the Lagrangian viewpoint. First, the fluorescent liquids were made by the mixing of the fluorescent materials, acetone, and xylene. Second, the sediments collected in Gamami beach were desalinized by the freshwater washing, dried indoors to protect the fine-sediment scattering, and classified by the sieve analysis. Finally, the FS which have seven different colors were manufactured by the mixing of fluorescent liquids and prepared sediments. The FS were used to figure out the major sediment supply routes of the intake channel in the YoungKwang nuclear power plant. From the field experiments, it was shown that the sediments were suspended and dispersed by the strong seasonal NW wind and the tide, and the sediments in suspension were flowing into the intake channel due to very strong suction speed. All the FS injected in stations were detected in the channel sampling points, thus we concluded that the sediments in suspension and dispersion were flowing into the intake channel from all directions in adjacent coastal zone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.1
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• pp.31-36
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• 1983

This experiment was carried out to evaluate the sanitary quality of ground water in Pusan area(see Fig. 1). One hundred and thirty two water samples were collected from the 11 stations from October 1981 to Sept ember 1982. To evaluate the sanitary quality, coliform group, fecal coliform, viable cell count and composition of coliform group by IMViC reaction were observed. The median value of coliform group MPN of the samples were 59/100 ml in Udong and Daesindong, 68/100 ml in Suyeong, Yeonsandong and Sungjigog, 43/100 ml in Jenpodong and Mangmidong, 33/100 ml in Yeongdo and Dongrae, and 13.3/100 ml in Gammandong. Geometric mean of fecal coliform MPM was 4.1/100ml in Udong, 8.6/100 ml in Suyeong, 8.1/100 ml in Jenpodong, 6.1/100 ml in Daesindong and Dongrae, 8.7/100 ml in Yeongdo, 7.1/100 ml in Mangmidong, 6.5/100 ml in Yeonsandong, 9.1/100 ml in Sungjigog, 3.0/100 ml in Gammandong and 7.6/100 ml in Gupo. The seasonal difference of total coliform showed much more contamination in June or July when there were more climers than in December though it was caused by the rise of loafer temperature. With 50 percentile of total coliform MPN July was about 30 times higher than December for July was 163.5/100 ml and December 5.3/100 ml, Particularly, June was about 1.3 times higher than July in contamination because of a sudden increase of people using it. Composition of coliform was $7.64\%$ Escherichia coli, group, $42.86\%$ Citrobacter freundii group, $16.78\%$ Klebsiella aerogenes group and $32.72\%$ others. Plate count of samples was varied from 48 to $4.4{\times10}^2/ml$ during the study period.