• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.275-281
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• 2014

Recently, the need for various underwater application systems targeting efficient resource exploration and aquatic ecosystem monitoring is rapidly increasing in littoral sea and inland waters. In this paper, we focus on the research and development of digital module of acoustic micro modem which can be used for underwater mobile communication systems and underwater sensor network systems. Specifically, a digital module of acoustic modem embedding digital signal processor is designed and implemented. On top of the developed hardware platform, physical layer frame generation and recovery and channel coding algorithms are mounted and tested in a water tank and a pond to verify its functionality and performance. According to experimental results, less than 1 percent of total computational power is consumed in the processing of frame control and convolutional code with the data rate of 1 kbps. Thus, the performance of micro modem could be improved by loading efficient baseband algorithms into the processor while maintaining the implemented hardware.

• Journal of Adhesion and Interface
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• v.19 no.3
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• pp.118-122
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• 2018

In this study, polyurethane hot melt adhesive containing ester groups was synthesized. Three kinds of chain extenders were used to find out the best chain extender. Results showed that adhesive containing 1,4-butanediol as a chain extender exhibited the highest peel strength among them. Also, it was found that there existed the optimum molecular weight of 1,4-butanediol containing adhesive for make the highest peel strength.. Moreover, hot melt adhesive containing 1,4-butanediol chain extender was applied to various kinds of textiles substrate such as cotton, polyester, and urethane coated polyester textiles to study the effects of different substrates on the peel strength and water resistance at $60^{\circ}C$. It was found that cotton substrate showed the highest peel strength and urethane coated polyester substrate showed the highest resistance on $60^{\circ}C$ water.

• Journal of agriculture & life science
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• v.44 no.1
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• pp.69-80
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• 2010

The purpose of this study is to analyse current marketing practices and marketing efficiency using operational efficiency. Through field survey on marketing situations and channels, we found that major marketing channels of paprika were classified into six types : channels in exporting market included (1) producer's organization leading channel (type I), (2) regional cooperative leading channel (type II), (3) individual producer leading channel (type III), and channels in domestic market included (4) wholesale markets targeting channel (type IV), (5) distribution agents targeting channel (type V), (6) cooperative system selling channel (type VI). According to the estimated result of operational efficiency of marketing channels, marketing efficiency of type III and IV was relatively higher than type I,II and type V, VI respectively.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.167-174
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• 2022

The Ministry of Oceans and Fisheries promoted the installation of eel-ladder for the purpose of creating inland water resources. Currently, eel-ladder have been installed and operated at the Geumgang Estuary Bank (2018), Yeongam Embankment (2019), and Asanman Embankment (2020). In this study, the number of glass eels in eel-ladder in 2021 was monitored and factors affecting the rise that from ocean to river of eels were investigated. Glass eels in eel-ladder were found when the salinity was relatively low, and they started when the freshwater and seawater temperatures were above 20℃. Comparing the number of occurrences by year, the largest number of glass eels was observed in 2021, but it is judged that this is not according to the distribution of glass eels in sea, but rather as a result of the investigator's eel-ladder repair and guidance on illegal fishing.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.504-504
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• 2023

최근 세계적인 기후변화로 인한 홍수의 빈도 및 규모가 커지게 되면서 최초 구조물의 설계시의 설계용량을 초과하는 국지적 집중호우가 발생하고 있다. 이는 도시방재를 위하여 기계획하였던 내수배제 시스템의 설계성능을 넘어 도시지역에 침수를 유발하게 된다. 이에 대한 해결책으로 도시의 내수배제 시스템을 개선하기 위한 우수저류조, 우수관거개선 등이 이루어지고 있지만 설치 이후 구체적인 효과분석이 이루어지지 않고 있다. 본 연구에서는 우수저류시설의 설치 여부에 따른 침수발생 양상을 분석하고 우수저류시설 침수저감효과를 정량적으로 분석할 수 있는 방안을 제시하였다. 이를 위하여 XP-SWMM을 이용하여 2차원 침수해석 모의를 실시하였고 다양한 조건에서의 모의를 위하여 2차원 침수해석 모의조건을 설정하였다. 기계획된 우수저류시설의 설계시의 임계지속기간을 기준으로 IDF Curve를 통하여 설계강우량, 확률강우량 및 방재성능목표량을 재산정하였고 Huff4분위법을 이용하여 강우분포를 시켜 XP-SWMM에 적용하였다. 또한, 유역 최종 방류구에서 기점수위 조건과 자유방류 조건을 분리하여 모의하였으며 최종적으로 우수저류시설의 설치여부에 따른 2차원 침수해석을 실시하였다. 2차원 침수모의 결과를 이용하여 월류량의 저감율과 격자별 침수심 분포 분석을 진행하였다. 월류량은 총량적인 지표를 가지고 있지만 격자별 침수심 분포 분석은 격자의 최대 침수심을 0.1m 간격으로 나누어 각 단계별 침수심 격자의 발생빈도를 산정하였다. 제안된 방법을 사용하여 분석을 진행한결과 우수저류조를 설치한 후에 격자의 최대침수심이 더 낮은 침수심 단계로 이동한 현상을 확인하였다. 이는 구조물의 설치 후에도 침수가 일어난다는 양적인 면이 아닌 격자의 침수심 분포 양상을 통해 도시침수에 직접적으로 저감이 나타나 효과를 기여할 수 있다는 지표라고 판단된다.

• Journal of fish pathology
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• v.3 no.1
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• pp.21-25
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• 1990

In inland aquaculture, a lot of fishes often died cause of touch of L. carteri which is attached on the net cage. In this works, the experiment were carried out on classification of species, toxin test, and extermination with some chemicals. A bryozoa from net cage in lake Okjeong is classified into the Phylactolaemata, Lophopodella carteri Hyatt. A bryozoa broke out firstly on the 30th of June with water temperature up to $31^{\circ}C$ and it reattached on the net with water temperature below $30^{\circ}C$. Size of bryozoa colony is about $0.8{\times}0.6{\sim}1.7{\times}1.5cm$. Water column of attachment was 0~5m and the peak is 2~3m. In toxin test on the israeli carp, goldfish and catfish touched with bryozoa for 1 minute at $25^{\circ}C$ of water temperature, a dead fish appeared at 20 minutes after touched. Mortality was 90% for israeli carp and 100% for goldfish at 100 minuties after touched, but catfish was not died at all. It was supposed that the toxin is from nematocyst being around tentacles and this toxin act a deadly poison on a israeli carp and goldfish. In extermination test, the bryozoa treated with 300ppm of formalin, 5% of sodium chloride, 5ppm of malachite green, 200ppm of potassium permanganate, 1000ppm of potassium iodide, 10ppm of DDVP for minute respectively, all of them were not effected.

• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.228-237
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• 2003

Temporary control schedules were tested at sweet persimmon orchards to development new control programs to meet the quarantine repuirements of America in 2001 and 2002. The 'MRL-type control orchards' were sprayed with chemicals which were possibly adaptable to the pome trees in America. A control schedule consisted of those chemicals registered for persimmon in Korea was incorporated in the 'domestic-type control orchards'. The efficacy of these two control type against insect pests was compared with that of a conventional control schedule. In 2001, MRL orchard and domestic orchard were sprayed 7 and 6 times, and two conventional orchards were 6 and 9 times, respectively. In 2002, acaricide was added once to the MRL orchards at late September to reduce the density of mites on harvested fruits. However no insecticide to plant bug control could be applied to the MRL orchards, because no insecticide against bugs was registered for pome trees in America. This resulted in 7 times of applications in MRL and domestic orchards. The conventional orchard was sprayed 9 times. Only the occurrence of the peach pyralid moth, Dichocrocis puntiferalis (PPM) out of 4 quarantine inset species was observed. The PPM was observed during growing season in MRL, domestic, and conventional orchards. However no fruits damaged by PPM larvae were observed after mid October and after harvest. In 2002 only 1 fruit out of 1,350 fruits inspected in June was damaged by the larvae of PPM at MRL orchards. A fungus-feeding mites and collembolan were under calyx of vested fruits. In 2001 they were found on 45.3% of harvested fruits at MRL orchard. However the percentage of fruits with mites in 2002 was greatly reduced to 3.5% at MRL orchard, presumably because of a added application of acaricide at late September. However percentage of fruits damage by hemipteran bugs at harvesting time was quite high 11.3 % at MRL orchards, because no application of insecticide against plant bugs.

• Journal of Digital Convergence
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• v.12 no.1
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• pp.149-161
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• 2014

According to the economic advancement, the position of service industry in GDP has increased. Development of service industry has solved the employment issue and derived the activation of the internal market. It has contributed to demand creation in health care, education, and culture, enhancing competition of the manufacturing industry and entire economic development. By the development of information communication technologies, improvement of the quality of life from those, and changes in the competitive environment, customers, from businesses and public agencies, or the customer's needs are increasing. In these circumstances, companies are operating non-face-to-face contact call center for the purpose to communicate with customers, handle customer complaints, attract and retain new customers. In this study, to improve the performance of the non-face-to-face contact call center, this study tried to derive the call center's 'Service Process Modeling' and future policy assignment by analyzing the problem from the research of the service and process summary, performance evaluation, call center evaluation and etc.

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.105-117
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• 2019

In order to investigate the characteristics of benthic macroinvertebrate communities in the Gihwa stream, a tributary of the Dong River, we surveyed the community and environmental factors in April and November 2013 at 6 sites. The benthic macroinvertebrate taxa represented total 63 species belonging to 29 families, 12 orders, 5 classes and 4 phyla. Total 48 (10~28 in each site) species were collected in April and 44 (13~24 in each site) in November. The number of individuals increased slightly from $560{\sim}2,290m^{-2}$ in April to $806{\sim}3,674m^{-2}$ in November. Chironomidae spp. was dominant species in April and Stenopsyche bergeri was dominant species in November. In the Functional Feeding Groups, Gathering-collector(53.9%) was dominant in April, while Filtering-collector (44.3%) increased in November. Intolerant order category (i.e. EPT species richness) in St.1, St.5 and St.6 increased in November compared to April due to the increase of Trichoptera. St.2, St.3 and St.4, which were located near the fish farm, were low EPT as a whole, but Benthic macroinvertebrate index (BMI) was good state in November than April due to decrease of Chironomidae spp.. The environmental factors in the survey site showed similar tendency except for St.1 between both seasons, and electrical conductivity, salinity, and water width showed seasonal differences. Cluster analysis and Nonmetric multidimensional scaling (NMDS) based on benthic macroinvertebrate community data were divided into two groups according to season. Electrical conductivity, salinity and substrate composition were the most influential factors determining the distribution patterns of macroinvertebrate communities.

• Journal of fish pathology
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• v.24 no.2
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• pp.121-129
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• 2011

Aquatic animal raised in hatcheries play an important role in supplying seedling to stock enhancement and seed quality, especially, seed health is the key factor for survival in the field after release and for stocking effectiveness. We have inspected the hatchery-reared seeds of 33 marine species and 12 freshwater species for legally designated diseases in stock enhancement program in 2010. Results showed that abalone was the most abundant as 20.0% in the marine species group and then sea cucumber (15.6%), olive flounder (8.4%), rockfish (6.7%), black sea bream (6.3%) and swimming crab (6.1%) were followed. Crucian carp was the most abundant as 19.4%, and then eel (11.8%), Korean bullhead (10.9%), mandarin fish (10.8%), melanian snail (8.4%), catfish (7.7%) were followed in the freshwater species group. The total number of inspection cases for eight pathogens in this study were 2,105 and disqualification cases were 30 by detection of aquatic animals pathogens such as koi herpesvirus (KHV), red sea bream iridovirus (RSIV), white spot syndrome virus (WSSV) or viral haemorrhagic septicemia virus (VHSV).