• Korean Journal of Environmental Biology
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• v.28 no.3
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• pp.125-132
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• 2010

In order to assess the effect of pollution on marine ecosystem, we examined the plankton health assessment at 16 stations during summer season in Jinhae Bay. The organic and inorganic pollutant sources (dissolved organic carbon; DOC, chemical oxygen demand; COD and Chlorophyll a; Chl.a), including planktonic orangism such as enterobacteria Escherichia coli, heterotrophic bacteria (HB), autotrophic nano-flagellates (ANF), heterotrophic nano flagellates (HNF), ciliate and harmful algal bloom species (HABs) were used to characterize marine ecosystem health assessment. Of these, we tentatively selected those items Chl.a, HABs, HB and E. coli for plankton health index (PHI). Also, the scoring criteria for each metric were based on a statistical analysis and then, the grades are rated on four levels. As a result, the ecological assessment of these data reveals that PHI in Jinhae Bay is rated as "Good or fair" for overall conditions. The present study suggests that the PHI might be considered as one of important management tool to assess marine ecosystem health of Jinhae Bay.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.703-708
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• 2011

In this paper, most of the church except for a large church has accommodated many audience to install a balcony floor in a small space. therefore, dead zone and dislocated sound image localization is made due to this under-balcony seats. This paper propose that the problems of dead zone and dislocated sound image localization could be solved using computer simulation in the view of practical side. The economical computer simulation tool, Mapp online that can be found easily was used to the specified church. Installation a sub speaker for dead zone and -10 dB power control of the sub speaker to main speaker power for dislocated sound image localization was proposed. Computer simulation result shows that the value of definition for area was improved from "Normal" to "Very Good" which means about 52% improvement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.595-601
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• 2018

Recently, as the fine dust level has risen rapidly, there is a great interest. Exposure to fine dust is associated with the development of respiratory and cardiovascular diseases and has been reported to increase death rate. In addition, there exist damage to fine dusts continues at industrial sites. However, exposure to fine dust is inevitable in modern life. Therefore, predicting and minimizing exposure to fine dust is the most efficient way to reduce health and industrial damages. Existing fine dust prediction model is estimated as good, normal, poor, and very bad, depending on the concentration range of the fine dust rather than the concentration value. In this paper, we study and implement to predict the PM10 level by applying the Artificial neural network algorithm and the K-Nearest Neighbor algorithm, which are machine learning algorithms, using the actual weather and air quality data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.493-504
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• 2021

The target site, Goejeongcheon flows through downtown of Saha-gu, Busan and it connects to the Nakdong-gang estuary. But non-point pollutants and sewage sludge are partially flowing into the stream and deposited. As a result, dissolved oxygen concentrations of the stream were observed close to the anaerobic condition. Multistage Vortex Aerator was applied for restoring this urban stream. It dissolves oxygen by repeatedly causing collisions between water and oxygen by vortex flow. The changes in water quality and odor were monitored for 2 months while circulating 1 m³/min of water with 22 ppm dissolved oxygen. As a result of the operation, the dissolved oxygen was improved from slightly Bad (4)~Bad (5) to Good (1b)~Normal (3) grade, and the total phosphorus concentration was decreased by 76 % on average. In the case of complex odor, a maximum reduction of 84.5 % was observed on the day the entire river was anaerobic. Through this study, we evaluated the feasibility of applying pure oxygen and Vortex Aerator for the the stream restoration. It is expected that the results of this study can be used for full-scale design.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.723-728
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• 2022

The vitality of the city's commercial district, which in the base of city life and provides vitality and diversity of life, has a great impact on the vitality of the entire city and the revitalization of the local economy. The revitalization of the commercial street is related to the activation of walking, and walking is closely related to the quality of life because it involves a wide range of interactions with the surrounding environment beyond simple movement. This quality of life leads to 'Livability'. In order to revitalize pedestrians on the commercial street, the liberty factor was derived and the importance of what was the most important and effective for the activation of the commercial street was analyzed. As a result, it was found that the items representing the atmosphere and purpose, which are detailed indicators of placeness, had a high priority, and it was found that the detailed indicators belonging to accessibility came out with a lower priority. In order to increase the livability of the commercial street, the priority is to increase the spatiality of the space, and if pedestrians are activated as the number of visits and stay time of visitors increases, it can be extended to the vitality of the entire area.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.212-212
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• 2020

도시하천의 경우 비 강우시 하천의 유지용수가 부족하고, 도시지역에서 유입되는 오염물질로 인하여 수질악화, 악취 등의 문제가 발생하고 있다. 최근 생태하천 및 친수 공간에 대한 관심이 증가하고 있고, 이에 정부는 도시하천 복원사업을 적극적으로 추진하여 수환경개선을 위한 많은 노력을 기울이고 있다. 굴포천은 인천 부평구에서 경기도 김포시로 이어져 있는 국가하천으로서 수질 향상 및 유지용수 확대를 위한 굴포 하수처리수의 재이용수 활용 계획이 수립되었다. 이에 2019년 3월 자연생태하천 조성사업이 준공되었고, 굴포하수처리수에 오존처리과정을 거친 유지용수가 굴포천 상류부에 공급되고 있다. 본 연구에서는 굴포천 내 오존처리 재이용수 공급 전·후의 수질 개선 효과를 분석하기 위하여 하천수 수질기준을 활용하여 계절 별 주요 수질인자의 농도를 정량적으로 비교하였다. 유지용수 방류지점과 굴포하수처리수 방류 위치를 기준으로 굴포천 내 해석구간을 나누고, 재이용수 공급전·후 각 1년에 대하여 주요 수질을 분석하였다. 하천수 수질환경기준에 사용되는 DO, BOD, COD, TOC, SS, T-P를 중심으로 분기별 수질 분석을 한 결과, 굴포천 모든 지점에서 DO 농도는 평균적으로 증가하였고, 다른 주요 수질 인자의 농도는 감소되어 수질 개선 효과가 높은 것으로 나타났다. 분기별 하천수 수질등급 비교 결과 재이용수 공급 전 '매우 좋음(1a)'였던 수질인자는 재이용수 공급 후에도 동일 등급을 유지하였고, 모든 수질 항목에서 계절에 따른 편차가 있었지만 재이용수 공급 이후 모든 수질등급이 향상된 것으로 나타났다.

• Management & Information Systems Review
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• v.39 no.2
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• pp.181-193
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• 2020

This study is a study that analyzes consumer perception by utilizing text mining, which is a recent issue. we analyzed the consumer's perception of Samsung Galaxy by analyzing consumer reviews of Samsung Galaxy YouTube ads. for analysis, 1,819 consumer reviews of YouTube ads were extracted. through this data pre-processing, keywords for advertisements were classified and extracted into nouns, adjectives, and adverbs. after that, frequency analysis and emotional analysis were performed. Finally, clustering was performed through CONCOR. the summary of this study is as follows. the first most frequently mentioned words were Galaxy Note (n = 217), Good (n = 135), Pen (n = 40), and Function (n = 29). it can be judged through the advertisement that consumers "Galaxy Note", "Good", "Pen", and "Features" have good functional aspects for Samsung mobile phone products and positively recognize the Note Pen. in addition, the recognition of "Samsung Pay", "Innovation", "Design", and "iPhone" shows that Samsung's mobile phone is highly regarded for its innovative design and functional aspects of Samsung Pay. second, it is the result of sentiment analysis on YouTube advertising. As a result of emotional analysis, the ratio of emotional intensity was positive (75.95%) and higher than negative (24.05%). this means that consumers are positively aware of Samsung Galaxy mobile phones. As a result of the emotional keyword analysis, positive keywords were "good", "good", "innovative", "highest", "fast", "pretty", etc., negative keywords were "frightening", "I want to cry", "discomfort", "sorry", "no", etc. were extracted. the implication of this study is that most of the studies by quantitative analysis methods were considered when looking at the consumer perception study of existing advertisements. In this study, we deviated from quantitative research methods for advertising and attempted to analyze consumer perception through qualitative research. this is expected to have a great influence on future research, and I am sure that it will be a starting point for consumer awareness research through qualitative research.

• Korean Journal of Environment and Ecology
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• v.30 no.6
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• pp.986-995
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• 2016

The objective of this study was to analyze the distribution of endangered fish species and elucidate their relations on chemical water quality, physical habitat conditions and ecological stream health. The dominant species in the watershed was Pseudopungtungia nigra (Pn), Gobiobotia macrocephala (Gm), Gobiobotia brevibarba (Gb), Liobagrus obesus (Lo), and Iksookimia choii (Ic) in the order. The species of Pn designated as "critical endangered species (I) (CER)", was most widely distributed species among the endangered species, so the designation of the species should be re-evaluated. The endangered species was most popular (4 species, 384 individuals) in the Cho-River region of eighteen lotic regions. According to the analysis of chemical tolerance limits in the habitats with endangered fish species, biological oxygen demand (BOD) and total phosphorus (TP) was analyzed as "very good" (Ia) and "good condition" in the chemical criteria of the Ministry of Environment, Korea. Also, chemical conditions, based on ammonia-N ($NH_{4+}$), total nitrogen (TN), phosphate-P ($PO_{4^-}P$) were much better in the habitat with endangered species (Hw) than the habitat without endangered species (Ho). In the meantime, the species of Ic showed wide ranges on the chemical tolerance, so physical habitat conditions, such as the size of substrate particles (sand) and hydrological regime, were considered as more important factors than the chemical water quality, if the water quality is not largely degraded. The endangered species were also more distributed in the high-order (4-6) streams than the low-order (1-3) streams. The evaluation of ecological stream health, based on multi-metric model of the Index of Biological Integrity (IBI), showed the large difference between the Hw (21.6, fair condition)and Ho (30.5, good condition), indicating that the habitat maintained well chemically and physically had higher distributions of endangered species. Overall, the designation of CER on the Pn should be re-evaluated due to wide-distributions, and the protections from water pollution and the habitat conservations on the endangered species are necessary in the watershed.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.296-304
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• 2011

This study was carried out to investigate the relation between water quality and structure of the aquatic ecosystem in the Lake Gachang from February to December in 2010. The annual mean COD (Chemical Oxygen Demand) in Lake Gachang was 3.5 mg $L^{-1}$, indicating, level II of environmental standards and the trophic state was mesotrophic. The seasonal succession of phytoplankton showed that Bacillariophyceae was mostly dominant species throughout the year except August. In case of zooplankton, rotifers dominate in the most seasons, but copepod (Nauplii) in August. The macrophyte plants showed diverse species composition consisted of 9 varieties, 77 species, 64 genera, 34 families and 24 orders. Surveyed species of macroinvertebrates were classified into 1 phyla, 2 classes, 4 orders, 7 families, 9 species. The macroinvertebrates showed FFG (Functional Feeding Groups) such as GC (Gathering-Collector) and SH (Shedder). A total of 42 species of fish was collected including $Zacco$ $koreanus$ and $Coreoperca$ $herzi$. In this study, we investigated environmental factors including pollutant source, load, water quality and distribution characteristics of biota such as phytoplankton, zooplankton, macrophyte plants, macroinvertebrates, fish.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.45-58
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• 2012

For the development of reference values and evaluation of water quality in various environmental conditions, we divided the coastal region around Korean peninsular into 5 distinctive ecological regions based on the influence of surface current, depth, tidal range, turbidity, and climate condition. We used national marine environment monitoring data collected by National Fisheries Research & Development Institute(NFRDI) from 2000-2009. For the reference values, we used maximum seasonal mean from 2000 to 2007 for DIN, DIP, and chlorophyll-a and minimum seasonal mean for secchi depth measured at stations without the influence of river runoff in each ecological regions. For the reference value of bottom dissolved oxygen saturation, we used minimum mean value of 90% calculated from minimal riverine influence stations of whole regions. We calculated enrichment score for each assessment criteria. The enrichment score of DIN, DIP, and Chlorophyll-a was 1 (=< reference value), 2 (< 110% of reference value), 3 (< 125% of reference value), 4 (< 150% of reference value), and 5 (> 150% of reference value). The enrichment score of DO saturation and Secchi depth was 1 (> reference value), 2 (> 90% of reference value), 3 (>75 % of reference value), 4 (> 50% of reference value), and 5 (< 50% of reference value). We calculated water quality index using weighted linear combination of five enrichment score for the comparison of whole regions. From the water quality index distribution calculated from all stations between 2000 and 2007 period, we classified into 5 grade based on the standard deviation calculated from total water quality index. We assigned grade very good(I), good(II), moderate(III), bad(IV), and very bad(V) when the water quality index was less than 23, minimum + 1 sd, +2 sd, +3 sd, and grater than minium+ 3 sd, respectively.