• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.919-928
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• 2023

Rainfall characteristics in Korea are concentrated during the summer flood season. In particular, when a large amount of turbid water flows into the dam due to the increasing trend of concentrated rainfall due to abnormal rainfall and abnormal weather conditions, prolonged turbid water phenomenon occurs due to the overturning phenomenon. Much research is being conducted on turbid water prediction to solve these problems. To predict turbid water, turbid water data from the upstream inflow is required, but spatial and temporal data resolution is currently insufficient. To improve temporal resolution, the development of the Turbidity-SS conversion equation is necessary, and to improve spatial resolution, multi-item water quality measurement instrument (YSI), Laser In-Situ Scattering and Transmissometry (LISST), and hyperspectral sensors are needed. Sensor-based measurement can improve the spatial resolution of turbid water by measuring line and surface unit data. In addition, in the case of LISST-200X, it is possible to collect data on particle size, etc., so it can be used in the Turbidity-SS conversion equation for fraction (Clay: Silt: Sand). In addition, among recent remote sensing methods, the spatial distribution of turbid water can be presented when using UAVs with higher spatial and temporal resolutions than other payloads and hyperspectral sensors with high spectral and radiometric resolutions. Therefore, in this study, the Turbidity-SS conversion equation was calculated according to the fraction through laboratory analysis using LISST-200X and YSI-EXO, and sensor-based field measurements including UAV (Matrice 600) and hyperspectral sensor (microHSI 410 SHARK) were used. Through this, the spatial distribution of turbidity and suspended sediment concentration, and the turbidity calculated using the Turbidity-SS conversion equation based on the measured suspended sediment concentration, was presented. Through this, we attempted to review the applicability of the Turbidity-SS conversion equation and understand the current status of turbid water occurrence.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.1
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• pp.107-124
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• 2023

As getting in 4th Industrial Revolution Times, Continuing Education Enrolled Students(CEES) trying to find loophole for jepordized current life and need job transfer have surged their interest significantly on starting new business to bring up their post career after retirement through self-improvement. Government and university have actively initiated diverse policies of promoting startup for CEES in kicking off entrepreneurship courses and programs. However, relevant main policy, 'The 2nd University Startup Education Five-Year Plan (draft)' have too chiefly focused on theoretical start-up education rather than practical courses, causing the problem of inappropriate support for implementing real startup and business (Ministry of Education, 2018). This study is brought to empirically investigate the effect of self-efficacy as perspective of the impact of entrepreneurship education on entrepreneurial intention and behavior to come up with problem of poor entrepreneurial environment and entrepreneurship education to CEES. As to empirical research, this paper deliver on-line survey to CEES from September to October 2022, collect 207 effective feedbacks, In order to verify the reliability of the scale, the Cronbach's Alpha Coefficient (Cronbach's α) was calculated, analyzed, and measured. For hypothesis test, this paper utilize the multiple regression analysis statistical analysis method and use the SPSS 22.0 statistical processing program. Empirical results show, first, it was found that self-efficacy had a significant effect on start-up education. Second, start-up education had a significant effect on the intention to start a business of adult learners. Third, start-up education had a significant effect on the start-up behavior of adult learners. Fourth, self-efficacy had a significant effect on the intention of adult learners to start a business. Fifth, self-efficacy had a significant effect on the start-up behavior of adult learners. Sixth, self-efficacy had a mediating effect in the relationship between entrepreneurship education and adult learners' intention to start a business. Seventh, self-efficacy had a complete mediating effect in the relationship between start-up education and adult learners' start-up behavior. This paper is brought three significant implications. First, main consideration developing entrepreneurship education tools for CEES need to falls on defining potential needs of CEES as segmenting as to coming up with diversity of CEES's characteristics such as gender, age, experience, education, and occupation. Second, as to design specific entrepreneurship education program, both practical training program of utilizing CEES's career field experience benchmarking best practice startup and venture cases from domestic and global, and professional startup program of CEES initiating directly startup from ideation to develop business plan with pitching and discussing. Third, entrepreneurship education for CEES should be designed to incubate self-efficacy to enhance entrepreneurial intention of implementing entrepreneurial behavior as a real, eventually leading solid support system of self-improvement for CEES' Retirement life planning.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.102-117
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• 2009

This study was carried out to investigate the extent to which benthic environment of Ulsan Bay was disturbed by organic materials and trace metals from the megacity and industrial complex. Field survey for benthic environment and macroinvertebrate community was seasonally conducted from February to November 2006 at nine stations covering the inside and outside of the bay. TOC was on average 1.7% while four (As, Cu, Pb, Zn) out of seven trace metals measured exceeded the Effects Range Low (ERL) in most of the stations. Total number of species sampled was 199 and mean density was 4,578 ind./$m^2$, both of which were greatly dominated by the polychaetes. Dominant species were Aphelochaeta monilaris (22.6%), Ruditapes philippinarum (17.1%), Magelona japonica (12.2%), Lumbrineris longifolia (9.9%) and their distribution was ruled by the difference in the benthic environmental condition of each station. From the multivariate analyses, four stational groups were identified: northern part of the bay, middle and lower part of the bay, the intersection of Taewha River and Gosa stream and outside of the bay. As a result, the community heterogeneity of inner bay was much more greater than that of outer bay. SIMPER analysis showed that four groups were represented by R. philippinarum-Capitella capitata, A. monilaris-Balanoglossus carnosus, Sinocorophium sinensis-Cyathura higoensis and M. japonica-Ampharete arctica, respectively. Spatio-temporal changes of macroinvertebrate communities in Ulsan Bay were closely related to those of depth, mean grain size and organic content, and Zn was also a meaningful factor in that context.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.2
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• pp.51-61
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• 2010

Surface particulate organic carbon (POC) concentration was measured in the Northeastern Gulf of Mexico on 9 cruises from November 1997 to August 2000 to investigate the seasonal and spatial variability related to synchronous remote sensing data (Sea-viewing Wide Field-of-view Sensor (SeaWiFS), sea surface temperature (SST), sea surface height anomaly (SSHA), and sea surface wind (SSW)) and recorded river discharge data. Surface POC concentrations have higher values (>100 $mg/m^3$) on the inner shelf and near the Mississippi Delta, and decrease across the shelf and slope. The inter-annual variations of surface POC concentrations are relatively higher during 1997 and 1998 (El Nino) than during 1999 and 2000 (La Nina) in the study area. This phenomenon is directly related to the output of Mississippi River and other major rivers, which associated with global climate change such as ENSO events. Although highest river runoff into the northern Gulf of Mexico Coast occurs in early spring and lowest flow in late summer and fall, wide-range POC plumes are observed during the summer cruises and lower concentrations and narrow dispersion of POC during the spring and fall cruises. During the summer seasons, the river discharge remarkably decreases compared to the spring, but increasing temperature causes strong stratification of the water column and increasing buoyancy in near-surface waters. Low-density plumes containing higher POC concentrations extend out over the shelf and slope with spatial patterns and controlled by the Loop Current and eddies, which dominate offshore circulation. Although river discharge is normal or abnormal during the spring and fall seasons, increasing wind stress and decreasing temperature cause vertical mixing, with higher surface POC concentrations confined to the inner shelf.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.1
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• pp.67-82
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• 2008

This study was performed to investigate changes in benthic environment and macrobenthic polychaete communities in Gamak Bay where various environmental quality improvement projects have been implemented in recent years. Field surveys were carried out in February, 2005 and February, 2006 and twenty stations were selected to explore whether or not there were between-year differences in biotic and abiotic variables. Of 10 environmental variables measured, only three variables including dissolved oxygen (DO), total ignition loss (IL), acid volatile sulfide (AVS) showed significant between-year differences. Specifically, IL and AVS were, on average, 1.5 and 3 times lower in 2006 compared to those in 2005, respectively, which was more pronounced in the northern part of the bay. A total of 95 polychaete species was sampled from the two sampling occasions. Between-year differences in the number of species, abundance, and diversity were varied from place to place. In the northern part of the bay, fewer species were found in 2006 rather than in 2005, but diversity increased in 2006 due to the reduction in dominance of a few species. On the contrary, in the central part of the bay, the number of species, abundance and diversity prominently increased in 2006. In the southern part of the bay, all the biological indices maintained similarly during the two years. Dominant species in 2005 were such opportunistic or organic pollution indicator species as Lumbrineris longifolia, Capitella capitata, Mediomastus californiensis, Pseudopolydora paucibranchiata, etc. and most of them were mainly distributed in the northern part of the bay and in the proximity of it. In 2006, however, Euchone alicaudata, L. longifolia, Paraprionospio pinnata, Flabelligeridae sp., etc. were dominant and distributed mainly in the central part of the bay. Multivariate analyses showed that the whole polychaete community could be divided into 5 groups reflecting the geographical positions of the sampling stations and temporal variation particularly in the northern part of the bay. According to the results of BIO-ENV procedure, TOC (${\rho}=0.52$) and AVS (${\rho}=0.49$) as a single variable best explained the polychaete community structure. The best combination was made by such variables as TOC, AVS, sorting coefficient, and water temperature (${\rho}=0.60$). In conclusion, between-year differences in biotic and abiotic variables imply that recent efforts for the environmental improvement produced positive influences on the benthic environment of Gamak Bay, particularly the northern part of the bay.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.56-60
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• 2009

Purpose: The various studies and efforts to develop program are in progress in the field of nuclear medicine for the purpose of reducing scan time. The Oncoflash is one of the programs used in whole body bone scan which allows to maintain the image quality while to reduce scan time. When Those applications are used in clinical setting, both the image quality and reduction of scan time should be considered, therefore, the purpose of this study was to determine the criteria for proper scan speed. Materials and Methods: The subjects of this study were the patients who underwent whole body bone scan at the departments of nuclear medicine in the Asan Medical Center located in Seoul from 1st to 10th, July, 2008. The whole body bone images obtained in the scan speed of 30cm/min were classified by the total counts into under 800 K, and over 800 K, 900 K, 1,000 K, 1,500 K, and 2,000 K. The image quality were assessed qualitatively and the percentages of those of 1,000K and under of total counts were calculated. The FWHM before and after applying the Oncoflash were analyzed using images obtained in $^{99m}Tc$ Flood and 4-Quadrant bar phantom in order to compare the resolution according to the amount of total counts by the application of the Oncoflash. Considering the counts of the whole body bone scan, the dosed 2~5 mCi were used. 152 patients underwent the measurement in which the counts of Patient Postioning Monitor (PPM) were measured with including head and the parts of chest which the starting point of whole body bone scan from 7th to 26th, August, 2008. The correlations with total counts obtained in the scan speed of 30cm/min among them were analyzed (The exclusion criteria were after over six hours of applying isotopes or low amount of doses). Results: The percentage of the whole body bone image which has the geometric average of total counts of under 1,000K among them obtained in the scan speed of 30cm/min were 17.6%(n=58) of 329 patients. The qualitative analysis of the image groups according to the whole body counts showed that the images of under 1,000K were assessed to have coarse particles and increased noises. The analysis on the FWHM of the images before and after applying the Oncoflash showed that, in the case of PPM counts of under 3.6 K, FWHM values after applying the Oncoflash were higher than that before applying the Oncoflash, whereas, in the case of that of over 3.6 K, the FWHM after applying the Oncoflash were not higher than that before applying the Oncoflash. The average of total counts at 2.5~3.0 K, 3.1~3.5 K, 3.6~4.0 k, 4.1~4.5 K, 4.6~5.0 K, 5.1~6.0 K, 6.1~7.0 K, and 7.1 K over (in PPM) were $965{\pm}173\;K$, $1084{\pm}154\;K$, $1242{\pm}186\;K$, $1359{\pm}170\;K$, $1405{\pm}184\;K$, $1640{\pm}376\;K$, $1,771{\pm}324\;K$, and $1,972{\pm}385\;K$, respectively and the correlations between the counts in PPM and the total counts of image obtained in the scan speed of 30 cm/min demonstrated strong correlation (r=.775, p<.01). Conclusions: In the case of PPM coefficient over 3.6 K, the image quality obtained in the scan speed of 30cm/min and after applying the Oncoflash was similar to that obtained in the scan speed of 15 cm/min. In the case of total counts over 1,000 K, it is expected to reduce scan time without any damage on the image quality. In the case of total counts under 1,000 K, however, the image quality were decreased even though the Oncoflash is applied, so it is recommended to perform the re-image in the scan speed of 15 cm/min.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.1
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• pp.1-17
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• 1975

Laboratory experiments on the phosphorus adsorption by soil were conducted to evaluate the parameters for determination of phosphorus adsorption capacity of soil, which serve as a basis for establishing the amount of phosphorus required to improve newly reclaimed soil and volcanic ash soil. The calculated Langmuir adsorption maxima varied from 6.2-32.9, 74.7-90.4 and 720-915mg p/100g soil for cultivated soils, non-cultivated soils, and volcanic ash soils respectively. The phosphorus absorption coefficient ranged from 116-179, 161-259 and 1,098-1,205mg p/100g soil for cultivated soils, non-cultivated soils, and volcanic ash soils respectively. The ratio of the phosphorus absorption coefficient to Langmuir adsorption maximum was low in soils of high phosphorus adsorption capacity (1.3-1.5) and high in soils of low phosphorus adsorption capacity (2.2-18.7). Changes in the amount of phosphurus adsorption induced by liming and preaddition of phosphorus were hadly detected by the phosphorus absorption coefficient, which is measured using a test solution with a relatively high phosphorus concentration. The Langmuir adsorption maximum was a more sensitive index of the phosphorus adsorption capacity. The Langmuir adsorption maxima of the non-cultivated soils, which were treated with an amount of calcium hydroxide equivalent to the exchangeable Al and incubated ($25-30^{\circ}C$) for 40 days at field capacity, were lower than the original soils. The change in the adorption maximum on incubation following the liming of soils was insignificant for other soils. The secondary adsorption maximum of soils, which received phosphorus equivalent to the Langmuir adsorption maximum of the limed soils incubated ($25-30^{\circ}C$) for 50 days at held capacity, was 74.5, 5.6 and 23.8% of the primary adsorption maximum for volcanic ash soils, non-cultivated soils, and cultivated soils respectively. The amount of phosphorus adsorbed by soils increased quadratically with the concentration of phosphorus solution added to the soils. The amount of phosphorus adsorbed by 5-g soil samples from 100ml of 100- and 1,000mg p/l solution for the mineral soils and volcanic ash soils respectively was found to be close to the Langmuir adsorption maximum. The amount of the phosphorus adsorbed at these concentrations is defined as a saturation adsorption maximum and proposed as a new parameter for the phosphorus adsorption capacity of the soil. The evaluation of the phosphorus adsorption capacity by the saturation adsorption maximum is regarded as a more practical method in that it obviates the need for the various concentrations used for the determination of the Langmuir adsorption maximum.

• The Korean Journal of Pesticide Science
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• v.13 no.1
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• pp.1-12
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• 2009

To assess the effect of butachlor on freshwater aquatic organisms, acute toxicity studies for algae, invertebrate and fishes were conducted. The algae grow inhibition studies were carried out to determine the growth inhibition effects of butachlor (Tech. 93.4%) in Pseudokirchneriella subcapitata (formerly knows as Selenastrum capriconutum), Desmodesmus subspicatus (formerly known as Scendusmus subspicatus), and Chlorella vulgaris during the exposure period of 72 hours. The toxicological responses of P. subcapitata, D. subspicatus, and C. vulgaris to butachlor, expressed in individual $ErC_{50}$ values were 0.002, 0.019, and $10.4mgL^{-1}$, respectively and NOEC values were 0.0008, 0.0016, and $5.34mg\;L^{-1}$, respectively. P. subcapitata was more sensitive than any other algae species. Butachlor has very high toxicity to the algae, such as P. subcapitata and D. subspicatu. In the acute immobilisation test for Daphnia magna, the 24 and $48h-EC_{50}$ values were 2.55 and $1.50mg\;L^{-1}$, respectively. As the results of the acute toxicity test on Cyprinus carpio, Oryzias latipes and Misgurnus anguillicaudatus, the $96h-LC_{50}s$ were 0.62, 0.41 and $0.24mg\;L^{-1}$, respectively. The following ecological risk assessment of butachlor was performed on the basis of the toxicological data of algae, invertebrate and fish and exposure concentrations in rice paddy, drain and river. When a butachlor formulation is applied in rice paddy field according to label recommendation, the measured concentration of butachlor in paddy water was $0.41mg\;L^{-1}$ and the predicted environmental concentration (PEC) of butachlor in drain water was $0.03 mg\;L^{-1}$. Residues of butachlor detected in major rivers between 1997 and 1998 were ranged from $0.0004mg\;L^{-1}$ to $0.0029mg\;L^{-1}$. Toxicity exposure ratios (TERs) of algae in rice paddy, drain and river were 0.004, 0.05 and 0.36, respectively and indicated that butachlor has a risk to algae in rice paddy, drain and river. On the other hand, TERs of invertebrate in rice paddy, drain and river were 3.6, 50 and 357, respectively, well above 2, indicating no risk to invertebrate. TERs of fish in rice paddy, drain and river were 0.58, 8 and 57, respectively. The TERs for fish indicated that butachlor poses a risk to fish in rice paddy but has no risk to fish in agricultural drain and river. In conclusion, butachlor has a minimal risk to algae in agricultural drain and river exposed from rice drainage but has no risk to invertebrate and fish.

• Journal of radiological science and technology
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• v.26 no.2
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• pp.37-42
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• 2003

Purpose : Computed tomographic equipment is essential for diagnosis by means of radiation. With passage of time and development of science computed tomographic was developed time and again and in future examination by means of this equipment is expected to increase. In this connection these authors measured rate of scatter ray generation at front of lead glass for patients within control room of computed tomographic equipment room and outside of entrance door for exit and entrance of patients and attempted to ind out method for minimizing exposure to scatter ray. Material and Method : From November 2001 twenty five units of computed tomographic equipments which were already installed and operation by 13 general hospitals and university hospitals in Seoul were subjected to this study. As condition of photographing those recommended by manufacturer for measuring exposure to sauter ray was use. At the time objects used DALI CT Radiation Dose Test Phantom fot Head (${\oint}16\;cm$ Plexglas) and Phantom for Stomache(${\oint}32\;cm$ Plexglas) were used. For measurement of scatter ray Reader (Radiation Monitor Controller Model 2026) and G-M Survey were used to Survey Meter of Radical Corporation, model $20{\times}5-1800$, Electrometer/Ion Chamber, S/N 21740. Spots for measurement of scatter ray included front of lead glass for patients within control room of computed tomographic equipment room which is place where most of work by gradiographic personnel are carried out and is outside of entrance door for exit and entrance of patients and their guardians and at spot 100 cm off from isocenter at the time of scanning the object. The results : Work environment within computed tomography room which was installed and under operation by each hospital showed considerable difference depending on circumstances of pertinent hospitals and status of scatter ray was as follows. 1) From isocenter of computed tomographic equipment to lead glass for patients within control room average distance was 377 cm. At that time scatter ray showed diverse distribution from spot where no presence was detected to spot where about 100 mR/week was detected. But it met requirement of weekly tolerance $2.58{\times}10^{-5}\;C/kg$(100 mR/week). 2) From isocenter of computed tomographic equipment to outside of entrance door where patients and their guardians exit and enter was 439 cm in average, At that time scatter ray showed diverse distribution from spot where almost no presence was detected to spot with different level but in most of cases it satisfied requirement of weekly tolerance of $2.58{\times}10^{-6}\;C/kg$(100 mR/week). 3) At the time of scanning object amount of scatter ray at spot with 100 cm distance from isocenter showed considerable difference depending on equipments. Conclusion : Use of computed tomographic equipment as one for generation of radiation for diagnosis is increasing daily. Compared to other general X-ray photographing field of diagnosis is very high but there is a high possibility of exposure to radiation and scatter ray. To be free from scatter ray at computed tomographic equipment room even by slight degree it is essential to secure sufficient space and more effort should be exerted for development of variety of skills to enable maximum photographic image at minimum cost.

• Progress in Medical Physics
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• v.27 no.2
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• pp.64-71
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• 2016

We develop a manufacture procedure for the production of a patient specific customized bolus (PSCB) using a 3D printer (3DP). The dosimetric accuracy of the 3D-PSCB is evaluated for electron beam therapy. In order to cover the required planning target volume (PTV), we select the proper electron beam energy and the field size through initial dose calculation using a treatment planning system. The PSCB is delineated based on the initial dose distribution. The dose calculation is repeated after applying the PSCB. We iteratively fine-tune the PSCB shape until the plan quality is sufficient to meet the required clinical criteria. Then the contour data of the PSCB is transferred to an in-house conversion software through the DICOMRT protocol. This contour data is converted into the 3DP data format, STereoLithography data format and then printed using a 3DP. Two virtual patients, having concave and convex shapes, were generated with a virtual PTV and an organ at risk (OAR). Then, two corresponding electron treatment plans with and without a PSCB were generated to evaluate the dosimetric effect of the PSCB. The dosimetric characteristics and dose volume histograms for the PTV and OAR are compared in both plans. Film dosimetry is performed to verify the dosimetric accuracy of the 3D-PSCB. The calculated planar dose distribution is compared to that measured using film dosimetry taken from the beam central axis. We compare the percent depth dose curve and gamma analysis (the dose difference is 3%, and the distance to agreement is 3 mm) results. No significant difference in the PTV dose is observed in the plan with the PSCB compared to that without the PSCB. The maximum, minimum, and mean doses of the OAR in the plan with the PSCB were significantly reduced by 9.7%, 36.6%, and 28.3%, respectively, compared to those in the plan without the PSCB. By applying the PSCB, the OAR volumes receiving 90% and 80% of the prescribed dose were reduced from $14.40cm^3$ to $0.1cm^3$ and from $42.6cm^3$ to $3.7cm^3$, respectively, in comparison to that without using the PSCB. The gamma pass rates of the concave and convex plans were 95% and 98%, respectively. A new procedure of the fabrication of a PSCB is developed using a 3DP. We confirm the usefulness and dosimetric accuracy of the 3D-PSCB for the clinical use. Thus, rapidly advancing 3DP technology is able to ease and expand clinical implementation of the PSCB.