• Ocean and Polar Research
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• v.43 no.2
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• pp.65-72
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• 2021

In order to evaluate the dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM), as indicators of organic matter in the coastal environments, we measured the concentrations of DOC, FDOM, and chemical oxygen demand (COD) in saline groundwater (Woljeong, Pyoseon, and Hwasun beaches) and coastal seawater (Haengwon, Gwideok, Pyoseon, and Yeongnak) in Jeju, Korea. The highest concentrations of DOC and COD in groundwater were found in Woljeong and Pyoseon, and those in coastal water were observed in Haengwon and Pyoseon, indicating that the higher concentrations of DOC and COD seem to be associated with saline groundwater-driven dissolved organic matter (DOM) and/or biogeochemical processes. According to origin and optical properties of DOM using FDOM as a tracer, proportion of humic-like FDOM, more refractory DOM, was relatively greater in the groundwater than in the coastal water. With regard to this result, there was no relationship between DOC and COD in groundwater, while DOC showed a good positive correlation (r² = 0.66) with COD in coastal water. This result indicates that COD as an indicator of assessment of DOM has a limitation in which it is difficult to quantify refractory DOM. Although DOC is a potential alternative to COD in the coastal environments, particulate organic carbon cannot be negligible due to relatively higher concentration compared to the open ocean. Therefore, the use of total organic carbon (TOC) as a replacement of COD in the coastal ocean is important, and the evaluation criterion of the TOC is necessary in order to evaluate of organic matter indicator in the various coastal environments.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.487-487
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• 2018

본 연구에서는 2017년 5월부터 12월까지 주단위로 낙동강 수계 5개 보 구간(칠곡보~창녕함안보)에서 본류와 유입지천의 유기물(BOD, $COD_{Mn}$, TOC) 분석 및 상관관계 조사하였으며, 강정고령보~창녕함안보의 대표지점에 대해서는 용존유기물(DOC)의 분해특성을 조사하였다. 본류의 유기물 농도는 BOD $2.7mgO_2/L$($2.3{\sim}3.1mgO_2/L$), $COD_{Mn}$ $5.6mgO_2/L$($5.0{\sim}6.2mgO_2/L$), TOC 4.7 mgC/L($4.2{\sim}5.2mgO_2/L$), 유입지천은 BOD $3.4mgO_2/L$($1.1{\sim}5.6mgO_2/L$), $COD_{Mn}$ $7.1mgO_2/L$($2.5{\sim}10.9mgO_2/L$), TOC $5.7mgO_2/L$(2.3~8.7 mgC/L)로 각각 나타났다. 유기물간 상관성 분석결과 본류의 BOD와 COD, TOC 상관계수(r)은 각각 0.97, 0.98, COD와 TOC는 0.91, 유입지천의 BOD와 COD, TOC는 각각 0.81, 076, COD와 TOC는 0.99로 나타났다. 본류 구간에서 탄소로 환산된 BOD-C/TOC 산화율은 21.5%(20.4~22.5%), COD-C/TOC 45.7%(44.3~48.0%), 유입지천의 BOD-C/TOC 산화율은 23.6%(13.1~31.0%), COD-C/TOC 48.0%(41.3~53.3%)로 각각 나타났다. 강정고령보~창녕함안보 대표지점의 DOC 분해특성은 DOC 중 R-DOC가 86.9%(74.5~94.3%), L-DOC 13.0%(5.7~25.5%)로 나타났다. L-DOC의 분해속도(k)는 0.21 /day(0.11~0.38 /day)로 계산되었으며, 보별 평균 분해속도는 합천창녕보(0.25 /day) > 강정고령보(0.22 /day) > 창녕함안보(0.21 /day) > 달성보(0.18 /day)순으로 나타났다. 유기물 농도는 본류에서는 하류로 갈수록 증가하는 경향을 보였으며, 유입지천은 지점별로 다양하게 나타났다. 유기물간 상관성은 유입지천보다 본류구간이 상관계수가 높게 나타났다. TOC에 대한 BOD와 $COD_{Mn}$산화율은 본류구간 보다 유입지천에서 큰 변동을 보였으며, 실제 유기물 총량 대비 BOD와 $COD_{Mn}$은 각각 77.0%, 52.7% 낮게 나타났다. DOC 중 난분해성 유기물이 대부분을 차지하였으며, 타 보 대비 달성보 내에 난분해성 유기물이 높은 것으로 나타났다.

• Korean Journal of Microbiology
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• v.36 no.2
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• pp.136-141
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• 2000

The temporal variation of bacterial community and environmental factors, affecting on bacterial community structure were estimated monthly kom April, 1998 to May, 1999. Bacterial community structures were determined by in situ hyblidization with rRNA-targeted fluorescently labeled oligonucleotide probes (FISH) and epifluorescence microscopy; and the statistical analysis was done by SPSS program. The oligonucleotide probes used in this study were EUB338, ALFlb, GAM42a, and CF. In surface water, $\alpha$-group was related to only DOC (-0.538, p<0.05) and Chlorophyll a concentration was related to y-group (-0.630, p$\beta$-group and Cytophaga-Flavobacterium group were related to water temperature as 0.665, and 0.685 @<0.05). Between pH and $\beta$-group, there was a positive relationship (0.541, p<0.05), and Cytophaga-Flavobactevizim group was represent to correlation (0.672, p

• Journal of Environmental Science International
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• v.15 no.4
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• pp.379-384
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• 2006

Eight USA soils were used for this study. The purpose of this study is to illustrate the characteristics of metals in the soil based on the sequential extraction with increasing pH. Extracts were analyzed for metals by ICP-MS and for dissolved organic carbon(DOC). As the pH increasing, the DOC extracted in each increment initially decreased and reached the minimum at pH 3 and then increased substantially at higher pH values. According to the pH increasing, the extraction of Ca, Cu, and Zn were illustrated as L type. It was found that there were strong correlation between the extracted Fe and DOC($r=0.64{\sim}0.97$).

• Journal of environmental and Sanitary engineering
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• v.13 no.1
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• pp.166-173
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• 1998

This study was to investigate the effects of preozonation on the waterborne organic removal by the biologically active GAC fluidized bed on a laboratory scale. The raw water to be treated comes from midstream of Han river. As the ozone dose was increased in the range of $1~3{;\}mgO_{3}/mgDOC$, it produced BDOC from 1.82 to 2.65 times. And BDOC formation can be expressed as [BDOC] = 0.74 + 0.21[DOC] ($R^{2}{\;}={\;}0.8399$). The effects of combination of ozonation followed by BACFB (Biological Activated Carbon Fluidized Bed) process were analyzed. At the ozone doze of $1~3{\;}mgO_{3}/mgDOC$, the large fraction of BDOC was removed by BACFB, but parameter revealed only around 10% reduction.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.295-311
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• 2023

Cloud computing has evolved significantly, intending to provide users with fast, dependable, and low-cost services. With its development, malicious users have become increasingly capable of attacking both its internal and external security. To ensure the security of cloud services, encryption, authorization, firewalls, and intrusion detection systems have been employed. However, these single monitoring agents, are complex, time-consuming, and they do not detect ransomware and zero-day vulnerabilities on their own. An innovative Record and Replay-based hybrid Honeynet (R2NET) system has been developed to address this issue. Combining honeynet with Record and Replay (RR) technology, the system allows fine-grained analysis by delaying time-consuming analysis to the replay step. In addition, a machine learning algorithm is utilized to cluster the logs of attackers and store them in a database. So, the accessing time for analyzing the attack may be reduced which in turn increases the efficiency of the proposed framework. The R2NET framework is compared with existing methods such as EEHH net, HoneyDoc, Honeynet system, and AHDS. The proposed system achieves 7.60%, 9.78%%, 18.47%, and 31.52% more accuracy than EEHH net, HoneyDoc, Honeynet system, and AHDS methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.64-70
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• 2018

The development of weapon systems (or components) is hindered by the number of tests due to the limited development period and cost, which reduces the scale of accumulated data related to failures. Nevertheless, because a large amount of failure data and maintenance details during the operational period are managed by computerized data, the cause of failure of weapon systems (or components) can be analyzed using the data. On the other hand, analyzing the failure and maintenance details of various weapon systems is difficult because of the variation among groups and companies, and details of the cause of failure are described as unstructured text data. Fortunately, the recent developments of big data processing technology, machine learning algorithm, and improved HW computation ability have supported major research into various methods for processing the above unstructured data. In this paper, unstructured data related to the failure / maintenance of defense weapon systems (or components) is presented by applying doc2vec, a machine learning technique, to analyze the failure cases.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.715-722
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• 2014

Effects of coagulation types on flocculation were investigated by using a photometric dispersion analyzer (PDA) as an on-line monitoring technique in this study. Nakdong River water were used and alum and ferric chloride were used as coagulants. The aim of this study is to compare the coagulation characteristics of alum and ferric chloride by a photometric dispersion analyzer (PDA). Floc growing rates ($R_v$) in three different water temperatures ($4^{\circ}C$, $16^{\circ}C$ and $30^{\circ}C$) and coagulants doses (0.15 mM, 0.20 mM and 0.25 mM as Al, Fe) were measured. The floc growing rate ($R_v$) by alum was 1.8~2.8 times higher than that of ferric chloride during rapid mixing period, however, for 0.15 mM~0.25 mM coagulant doses the floc growing rate ($R_v$) by ferric chloride was 1.1~2.3 times higher than that of alum in the slow mixing period at $16^{\circ}C$ water temperature. Reasonable coagulant doses of alum and ferric chloride for turbidity removal were 0.1 mM (as Al) and 0.2 mM (as Fe), respectively, and the removal efficiency of those coagulant doses showed 94% for alum and 97% for ferric chloride. The appropriate coagulant dose of alum and ferric chloride for removing dissolved organic carbon (DOC) showed about 0.3 mM (as Al, Fe) and at this dosage, DOC removal efficiencies were 36% and 44%, and ferric chloride was superior to the alum for removal of the DOC in water.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.178-187
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• 2020

The current emission regulations, US Tier-4 and EU Stage-V, are only able to satisfy the regulations when all currently mass-produced emission reduction technologies such as EGR, DOC, DPF, and SCR are applied. Therefore, in this study, for the application of the Urea-SCR system to non-road diesel engines, the database was established by measuring the NO, NO2 concentration and calculating the NO2/NOx ratio based on the catalyst temperature and exhaust mass flow rate. Also, based on the measured NO2/NOx ratio data, a mathematical model was proposed to predict the NO2/NOx ratio at SCR catalyst, and the suitability of the model was verified through steady-state and transient mode. As a result of comparing the NO2/NOx ratio measured at the DOC outlet under the steady-state condition to two model values separately, the R2 was 0.9811 for the 3D map model and 0.9303 for the mathematical model. And in the case of the NO2/NOx ratio measured at the DPF outlet, the R2 was 0.9797 for the 3D map model and 0.935 for the mathematical model. It was confirmed that the R2 with the model value of the 3D Map of the mathematical model in the transient mode is 0.957, which shows high reliability.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.60-66
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• 2001

Natural organic matters(NOMs) are found everywhere such as soil, surface and ground waters and consist of both humic and nonhumic components, and their heterogeneith makes each source unique. This study was carried to evaluate the removal characteristics of NOMs by mixing coagulants and the variation of apparent molecular weight distribution(AMWD) in coagulation process. Ratio of optimum coagulants dosage for removal of DOC and turbidity by mixing coagulants was 1.83 mM F $e^{3+}$/mM $Al^{3+}$. DOC removal increased at lower pH. The pH6 control focused on the removal of organic matters could reduce the amount of coagulant consumption by 2 to 3 times based on the pH8.5 of natural water. The dissolved organic matters in the natural water from the mid-stream of Han River were composed of the low molecular weight(LMW,<1 K) of 59.7%, and the medium and high molecular weight(M.HMW, 1~30 K) of 40.3%, respectively. At pH6, the DOC removal efficiencies of LMW(<1 K) and M.HMW(1~30 K) in coagulation process were 27~35%, 62~72%, respectively. The fraction smaller than 1 K was not eliminated to a noticeable degree, while the fraction of 1~30 K was relatively well removed. In conclustion, mixing coagulants were fairly effective in the removal of natural organic matter.r.