• Journal of Wetlands Research
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• v.25 no.4
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• pp.326-334
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• 2023

The purpose of this study is to use long-term water quality monitoring data from tributaries of the Nakdong River system to identify problematic substances in tributaries by examining the rate of exceedance and increase in water quality targets. In the Nakdong River system, monitoring is conducted once a month for 38 tributaries that require intensive management, and this data was used to analyze trends in exceeding and increasing target water quality at each point. The analysis items are eight items that can be evaluated based on river water quality standards: DO, BOD, COD, TOC, SS, total phosphorus, fecal coliform, and total coliform. As a result of the analysis, the target water quality exceedance rate was more than 50%, and the items with an increasing trend were TOC, fecal coliform and total E. coli counts, and the items with an exceedance rate of less than 50% but an increasing trend were SS. TOC is believed to be caused by an increase in non-degradable substances, and the continued increase in Total Coliform will require management of Total ColiformTotal Coliform in effluent water from sewage treatment facilities in the future.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.509-516
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• 2023

The use of sulfur(S) in concrete has been variously studied as a way to improve salt resistance in concrete. However, sulfur is a solid material and is difficult to powder, which has disadvantages in its usability as an admixture or mixture for cement and concrete. For these problem, polymers such as dicyclopentadiene have been used to modify sulfur, but this also exists in a sticky state after modifying and does not improve the fundamental problem. So, reforming sulfur with slaked lime and the effect on cement hydration was examined by reforming sulfur with slaked lime, and the following conclusions were obtained. Depending on the reaction conditions, slaked lime modified bio-sulfur exists in a slurry state containing unreacted sulfur, unreacted slaked lime, calcium-sulfur(Ca-S) compounds and water. When slaked lime modified bio-sulfur is used as a cement mixture, salt resistance of concrete with slaked lime modified bio-sulfur is to be superior to that of plain concrete. This is believed to be because structure of cement hydrates with slaked lime modified bio-sulfur is to be more dense to that of plain cement hydrates by the continued presence of ettringite and can be used as a cement mixture in concrete.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.305-314
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• 2023

In this study, a mathematical model of a 9.77 G/T small fishing vessel was established based on captive model tests. The powering and manoeuvring performances of the vessel in the harbor and coastal sea were focused on, so captive model tests were conducted up to the full-scale speed of 8 knots. Propeller open water, resistance, and self-propulsion tests of a 1/3.5-scaled model ship were performed in a towing tank, and the full-scale powering performance was predicted. Hydrodynamic coefficients in the mathematical model were obtained by rudder open water, horizontal planar motion mechanism tests of the same model ship. In particular, in static drift and pure yaw tests which were conducted at a speed of 2 to 8 knots, the linear hydrodynamic coefficients varied with the ship speed. The effect of the ship speed on the linear coefficients was considered in the mathematical model, and manoeuvring motions, such as turning circles and zig-zags, were simulated with various approach speeds and analyzed.

• Journal of the Korean Geosynthetics Society
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• v.23 no.1
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• pp.39-47
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• 2024

In this study, physical property tests and standard consolidation tests were conducted on the marine clay of Busan New Port and North Port, the middle and lower reaches of the Nakdong River including Gimhae and Yangsan, and Ulsan regions. The moisture content, a property unrelated to sample disturbance with small individual test errors, was used for regression analysis with the compression index, virgin compression index, consolidation coefficient, expansion index, and secondary compression index, among others. Subsequently, the correlation and accuracy were evaluated. Upon analyzing the correlation between the moisture content, void ratio, and liquid limit commonly used physical properties for calculating compression indexes, it was confirmed that the liquid limit had the lowest correlation. Through a linear regression analysis of the consolidation constants using the current moisture content in the natural state, a high correlation was demonstrated. Relationship equations were then presented to determine settlement and settlement time. This study suggests that moisture content can be utilized as an alternative for evaluating and calculating consolidation constants when examining ground settlement in sedimentary clays distributed in the Busan and Gyeongnam regions.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.1
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• pp.49-59
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• 2024

Biodegradable coating urea plays an important role in reducing the non-pollutants in agroecosystems, maximizing the plant nutrient utilization efficiency and slow-releasing nitrogen. Herein, the objective of this study was to investigate the nitrogen-releasing patterns and greenhouse gas emissions on different biodegradable coating urea. The treatments consisted of the control as an application of chemical fertilizers, NBCF as the non-biodegradable coating urea, NB60, and MDS as biodegradable coating urea. As a result of this study, the maximum accumulated total nitrogen (TN) concentration in the NBCF was higher at 33% than one in the NB60 during the precipitation periods. Its leaching period in the NCBF was prolonged for day 10 compared to the NB60. TN and NO₃-N releasing patterns in the NBCF and NB60 were fitted well on linear types(R²≥0.991), but their control and MDS were fitted well on Sigmoid curves(R²≥0.994) with high releasing concentration in the MDS compared to the control during leaching periods. For the greenhouse gas emissions, CH₄ emissions in the NBCF, NB60, and MDS were increased at 0.38%, 11.36%, and 5.91%, and N₂O emissions were also increased at 50.5%, 32.4%, 58.8% as compared to the control, respectively. Therefore, application of biodegradable polymer coating urea might mitigate the non-point pollutants in agro-ecosystem.

• Journal of the Korean Society of Radiology
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• v.85 no.1
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• pp.240-246
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• 2024

Epithelioid angiosarcoma is a rare variant of angiosarcoma characterized by an epithelioid morphology that mimics carcinoma. Therefore, multicentric epithelioid angiosarcoma is easily misdiagnosed as bone metastasis from carcinoma and has an aggressive clinical course. Here, we present a rare case of a 61-year-old male with multicentric epithelioid angiosarcoma of the bone. Plain radiography, CT, and MRI revealed multiple osteolytic lesions in both femurs; some lesions showed soft tissue extension with cortical bone destruction. Interestingly, PET-CT revealed that the lesions were only distributed along the bones of the lower extremities, including the pelvic bones, femurs, and tibiae. Despite histological analysis initially suggesting metastatic carcinoma, after additional immunohistological staining, including that for vascular markers (CD31 and ERG), the final diagnosis was epithelioid angiosarcoma. A better understanding of the clinicoradiological features of this disease may help eliminate diagnostic confusion and provide better management.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.1
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• pp.89-97
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• 2010

In this study, to investigate the effect of chemical pretreatment for livestock wastewater, laboratory scale test for ozonation and linked treatment of sewage were conducted. and the results were obtained as follows. The ozonation of livestock wastewater showed the COD removal rate per hour to be 17%, 78% and 62% at each pH 4, 7 and 10, respectively. With transformation of NBDCOD to biodegradable BDCOD by ozonation, the ratio of SCODcr/TCODcr was increased from 26% to 38%. Accordingly, pretreatment of livestock wastewater affected to the biological post treatment process to elevate removal efficiency by transformation of nonbiodegradable mass to biodegradable mass. As the results of linked treatment of pre-ozonated livestock wastewater and sewage in the MLE process, the treatment efficiencies of TCODcr 93.8%, T-N 74.3%, T-P 89.7%, SS 97.5% were earned at 100% of internal recycle rate. When the internal recycle rate was increased to 150%, the treatment efficiencies of TCODcr 94.5%, T-N 54.5%, T-P 70.8%, SS 98.5% were earned. Also the removal efficiencies of TCODcr 92.6%, T-N 83.1%, T-P 81.9%, SS 98.5% were earned as the internal recycle rate was increased to 200%. Especially, nitrogen removal efficiency in the linked treatment showed 74.3%, 54.5%, 83.1% at 100%, 150% and 200% of internal recycle ratio, respectively, which revealed the tendency of higher removal efficiency than that of sewage treatment.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.3
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• pp.299-306
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• 1984

The influences of applications of organochlorine insecticide (HCH: Hexachlorocyclohexane, 10 ppm), fungicide (TPN: Tetrachloroisophthalonitrile, 40 ppm) and manure ($3Kg/m^2$) each or together on changes in soil microflora for consecutive years were investigated in the experimental field plots. The insecticide had a little effect on soil microbial numbers. In particular, the number of total bacteria, Gram-negative bacteria and fungi were gradually increased at the latter stage of the consecutive application, but the number of sporeforming bacteria reduced. The fungicide reduced the counts of sporeforming bacteria, actinomycetes and fungi respectively, whereas increased prominently the counts of total bacteria and Gram-negative bacteria. TPN-resistant bacteria, particulary TPN-resistant Gram-negative bacteria were gradually accumulated by the long-term application of TPN, and further the number of TPN-resistant total bacteria and the of TPN-resistant Gram-negative bacteria correlated fairly well during all the period. The influences of combined applications of both HCH and TPN on the number of soil microorganisms were equal to the respective sums of the effects of single application of each pesticide. The combined application of manure and these pesticides elevated the increasing extents of microbial numbers, while weakened the detrimental efforts of these pesticides on microbial numbers. These data suggest that the long-term application of these materials have resulted in the remarkable changes of composition of soil microflora.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.259-264
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• 2001

Typhoon and neap tide on Cochlodinium polykrikoides bloom and water temperature on disappearance of C. polykrikoides bloom were investigated to elucidate the outbreak mechanism of C. polykrikoides blooms at Naro and Namhae coastal area in South Sea of Korea. The first observation of C. polykrikoides blooms were observed when thermocline was disappeared by typhoon, tide, etc. The first blooms of C. polykrikoides were observed on neap tide or before one day from neap tide in 1996-1998 and 2000. However, thermocline was disappeared by typhoon in 1994 and 1999, the first blooms were observed early 12-30 day than 1996-1998 and 2000. The main reason of disappearance of C. polykrikoides blooms after typhoon on 1997-2000 seems to be other environmental change by typhoon rather than low water temperature. In the future, the first C. polykrikoides bloom will be appear around the first neap tide of latter part of August with breaking down of thermocline, but if the thermocline be collapsed by typhoon in July, the C. polykrikoides bloom will be appear at beginning of August. The outbreak of C. polykrikoides blooms will be explain as follows: The vegetative cells, which was germinated by environmental change or already exist in surface water at low level, input to the surface water, and then nutrients and trace metals which were suppled from out side of C. polykrikoides bloom area inflow to surface. The vegetative cells are growth by the nutrients and trace metals at suitable environmental conditions e.g. water temperature, salinity, and sufficient light.

• The Korean Journal of Petroleum Geology
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• v.5 no.1_2 s.6
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• pp.1-8
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• 1997

Seismic stratigraphic analysis of the high resolution profiles obtained from the southeastern shelf of Korea divided the deposits into 4 sequences; 1) sequence D, 2) sequence C, 3) sequence B and 4) sequence A (Holocene sediments). Sequence D was deposited in shallow-water environment at west of the Yangsan Fault as the basin subsided. On the other hand, the eastern part was formed at the slope front. Landward part of the slope-front fill sediments were eroded and redeposited nearby slope due to the syndepositional tilting of the basin. This tilting probably resulted from the continuous closing of the Ulleung Basin. Sequence C is made of stacked successions of the lowstand fluvial sediments, transgressive sediments and marine highstand sediments derived from the paleo-river in the western part of the Yangsan Fault. Sequence C in the eastern part of the Yanshan Fault was formed at the shelf break. Progradation of the lowstand sediments resulted in broadening of the shelf. Sequence C in the eastern part was also tilted but the tilting was weaker than in Sequence D. During the formation of sequence B the tilting stopped and the point source instead of the line source started in both sides of the Yangsan Fault. Sequence B was composed of the highstand systems tract partially preserved around the Yokji island, lowstand systems tract mainly preserved in the Korea Trough and transgressive systems tract. After the stop of the tilting, the force of compression due to the closing of the Ulleung Basin may be released by the strike-slip faults instead of tilting.