• Journal of Korea Water Resources Association
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• v.56 no.6
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• pp.403-417
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• 2023

In this research, a methodology was developed for constructing an appropriate rainfall image database for estimating rainfall intensity based on CCTV video. The database was constructed in the Large-Scale Climate Environment Chamber of the Korea Conformity Laboratories, which can control variables with high irregularity and variability in real environments. 1,728 scenarios were designed under five different experimental conditions. 36 scenarios and a total of 97,200 frames were selected. Rain streaks were extracted using the k-nearest neighbor algorithm by calculating the difference between each image and the background. To prevent overfitting, data with pixel values greater than set threshold, compared to the average pixel value for each image, were selected. The area with maximum pixel variability was determined by shifting with every 10 pixels and set as a representative area (180×180) for the original image. After re-transforming to 120×120 size as an input data for convolutional neural networks model, image augmentation was progressed under unified shooting conditions. 92% of the data showed within the 10% absolute range of PBIAS. It is clear that the final results in this study have the potential to enhance the accuracy and efficacy of existing real-world CCTV systems with transfer learning.

• (The)Study of the Eastern Classic
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• no.49
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• pp.73-107
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• 2012

Yeoheon Jang Hyeongwang(1554-1637), one of the greatest Mid-Joseon Confucianists did systematic studies on universe and nature. It can be considered that he inherited the academic tradition of Cho Sik (曺植) and Jeong Gu(鄭逑) and followed their steps of fengshui (風水) and compilation of geographical records. His living and thought and deserve researching with regard to geographical studies. This paper attempts to analyze Yeoheon's recognition of geography in general. In other words, I shall prove that his view of geography is Neo-Confucian. At the same time, I shall discuss how he named people's residence, how he understanded the Joseon territory, what he thought about fengshui, and what significance the complication of geographical records by his disciples had. Yeoheon considered that land is composed of water, fire, earth, and rock, and understanded the land according to the theory of Zhouyi (周易). He analyzed geographic environments by the system of Zhouyi. His study of geography is basically intended for practical use, and as a result is necessary for people to choose where to live and where to cultivate. In his opinion, it is essential to divide the land of the Joseon by means of geographical differences in order to help people to find a better place to live. We can see his Confucian view from the fact that he placed a greater emphasis on human beings over nature. Therefore, the practical use for humans is the first priority in his study of geography. Meanwhile, he considered nature itself as only the object of study. He realized the vitality of life by making a close observation of nature and attained the mind of the Heaven and Earth in a detached way. He, as a follower of Neo-Confucianism, enjoyed the land by feeling comfortable with his present status and by being satisfied with himself. He put his Confucian view of universe and world into practice in his life. As a part of his efforts, he named his residence and surrounding natural environments with the polar star and 28 stars, and accordingly they are reconstructed in a system of universe. The Confucian tradition of dongcheon gugok (洞天九曲) starting with Zhu Xi's administration of wuyi jiugu (武夷九曲) was widely prevalent during the Joseon period, but Yeoheon's system of organizing places is original. His sense of naming places reflects his ideas of following his predecessors, comparing natural objects to human emotions, and desiring to live in retirement. Yeoheon understanded the Joseon territory with comparison of the Chinese land. He expressed his knowledge in the form of changing geographical features of a district, appreciating natural beauty, locating towns, and being familiar with a region, and proposing his own climatology and view of the reality. His recognition of the Joseon territory resolves itself into the following several points. He regarded the Joseon territory as one organism, and considered the territory to be composed of ki (氣) as Neo-Confucianists usually do. In addition, he understanded not only natural environments but also towns from a perspective of the fengshui and adopted a comparative methodology in dividing regions. He also applied climatology to analyze persons and customs. He employed the methodology of fengshui from the comprehensive theory of the Yijing. It is because he was influenced by Cho Sik and Jeng Gu. Yeoheon chose dwelling places for people, or gave advice on several places of his hometown relying on his knowledge of fengshui. When it comes to his theory of fengshui, he agreed with the theory of topography with regards to the fengshui of tombs, but criticized the custom of delaying funerals in order to turn fortune in one's favor. In addition, he accepted that it is necessary to complement a town by creating forests around it. We need to pay attention to the fact that Yeoheon's disciples complied several geographical records. It proves that they inherited the tradition of "valuing practical use and governing on behalf of the people" from Cho Sik and Jeong Gu. Yeoheon put a great emphasis on geographical records and encouraged his disciples to compile them. In other words, he emphasized that they, as administrator or intellectual, need to be erudite in the history and custom of a region where they have lived, and have to establish a standard to encourage or warn people in the region while considering the geographical records. His opinion functioned as a guideline for his successors to compile geographical records later. This paper only analyzed several facts with regard to Yeoheon's knowledge of geography and an academic tradition concerning the study of geography. In the future, I shall discuss how his predecessors and successors understanded geography and how the tradition of compiling geographical records was transferred and developed between them. I believe that this study will contribute to establishing the history of geography, which the Joseon Confucianists researched for a long time but we have not paid an enough attention to until now.

• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.537-548
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• 2017

The purpose of this study was to investigate the species composition and the aquatic environment of Jojong Stream and Sudong Stream, which were the original habitats of Zacco koreanus population and restored population re-introduced in Bongseonsa Stream. It also compared and analyzed the states of the growth and reproductive ability of Z. koreanus habiting in each of the three streams. The investigation was conducted in June 2016 which was known as the spawning season of Z. koreanus. The results of the physical aquatic environments showed the slight differences in altitude, width and depth of water among three streams, but the bottom structure was found to be quite different in the composition of the boulder, cobble, and pebble among the streams. The result of the physicochemical aquatic environment analysis showed that there were no significant differences in water temperature, pH, DO, BOD, and EC among the three stream. In the fish fauna investigation, 530 individuals of 11 species of 3 families were collected in Bongseonsa Stream, 293 individuals of 12 species of 4 families were collected in Jojong Stream, and 361 individuals of 11 species of 4 families were collected in Sudong Stream. All three streams were dominated by Z. koreanus and Z. platypus. Six Korean endemic species appeared in each of the three streams, showing the high occurrence rate of indigenous species of 50.0% or more. The aggregation index analysis revealed that the mean dominance index ranged from 0.63 (${\pm}0.05$, BS) to 0.72(${\pm}0.01$, JJ), mean diversity index from 1.55 (${\pm}0.06$, JJ) to 1.78 (${\pm}0.11$, BS), mean evenness index from 0.71 (${\pm}0.03$, JJ) to 0.76 (${\pm}0.02$, BS), and mean richness index from 1.61 (${\pm}0.33$, JJ) to 1.73 (${\pm}0.24$, SD). The result indicated that the observed differences between the stream community indices were statistically nonsignificant. The similarity analysis showed that 75.4% similarity was divided into two groups of A and B and that the fish fauna on each analyzed point was similar. The quantitative habitat evaluation index (QHEI) analysis showed that the average value of QHEI was 151.0 (${\pm}46.0$), which means that it was a suboptimal habitat environment. The result of length-weight analysis of Z. koreanus populations showed that the regression coefficient b of the restoration population and the original habitat population were at 3.0 or higher while the condition factor had a positive slope. Moreover, it was found that the slopes of the regression coefficient b and condition factor of the original habitat population were larger than the restored population. The analysis of the length frequency distribution of the Z. koreanus population revealed that all three streams maintained the stable life cycle although it was found that the growth rate of the original habitat population was faster than the restored population in the one-year-old class. The result of the gonadosomatic index (GSI) analysis showed that the GSI median value of the Z. koreanus population in the restored habitat Bongseonsa Stream was higher than the population in the original habitat Jojong Stream and Sudong Stream for both of males and females.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.4
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• pp.223-237
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• 2011

The intermittent freshwater discharge has an critical influence upon the biophysical environments and the ecosystems of the Yeongsan Estuary where the estuary dam altered the continuous mixing of saltwater and freshwater. Though freshwater discharge is controlled by human, the extreme events are mainly driven by the heavy rainfall in the river basin, and provide various impacts, depending on its magnitude and frequency. This research aims to evaluate the magnitude and frequency of extreme freshwater discharges, and to establish the magnitude-frequency relationships between basin-wide rainfall and freshwater inflow. Daily discharge and daily basin-averaged rainfall from Jan 1, 1997 to Aug 31, 2010 were used to determine the relations between discharge and rainfall. Consecutive daily discharges were grouped into independent events using well-defined event-separation algorithm. Partial duration series were extracted to obtain the proper probability distribution function for extreme discharges and corresponding rainfall events. Extreme discharge events over the threshold 133,656,000 $m^3$ count up to 46 for 13.7y years, following the Weibull distribution with k=1.4. The 3-day accumulated rain-falls which occurred one day before peak discharges (1day-before-3day -sum rainfall), are determined as a control variable for discharge, because their magnitude is best correlated with that of the extreme discharge events. The minimum value of the corresponding 1day-before-3day-sum rainfall, 50.98mm is initially set to a threshold for the selection of discharge-inducing rainfall cases. The number of 1day-before-3day-sum rainfall groups after selection, however, exceeds that of the extreme discharge events. The canonical discriminant analysis indicates that water level over target level (-1.35 m EL.) can be useful to divide the 1day-before-3day-sum rainfall groups into discharge-induced and non-discharge ones. It also shows that the newly-set threshold, 104mm, can just separate these two cases without errors. The magnitude-frequency relationships between rainfall and discharge are established with the newly-selected lday-before-3day-sum rainfalls: $D=1.111{\times}10^8+1.677{\times}10^6{\overline{r_{3day}}$, (${\overline{r_{3day}}{\geqq}104$, $R^2=0.459$), $T_d=1.326T^{0.683}_{r3}$, $T_d=0.117{\exp}[0.0155{\overline{r_{3day}}]$, where D is the quantity of discharge, ${\overline{r_{3day}}$ the 1day-before-3day-sum rainfall, $T_{r3}$ and $T_d$, are respectively return periods of 1day-before-3day-sum rainfall and freshwater discharge. These relations provide the framework to evaluate the effect of freshwater discharge on estuarine flow structure, water quality, responses of ecosystems from the perspective of magnitude and frequency.

• Journal of Intelligence and Information Systems
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• v.26 no.4
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• pp.87-109
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• 2020

Currently, thanks to the major stride made in developing wired and wireless communication technology, a variety of IT services are available on land. This trend is leading to an increasing demand for IT services to vessels on the water as well. And it is expected that the request for various IT services such as two-way digital data transmission, Web, APP, etc. is on the rise to the extent that they are available on land. However, while a high-speed information communication network is easily accessible on land because it is based upon a fixed infrastructure like an AP and a base station, it is not the case on the water. As a result, a radio communication network-based voice communication service is usually used at sea. To solve this problem, an additional frequency for digital data exchange was allocated, and a ship ad-hoc network (SANET) was proposed that can be utilized by using this frequency. Instead of satellite communication that costs a lot in installation and usage, SANET was developed to provide various IT services to ships based on IP in the sea. Connectivity between land base stations and ships is important in the SANET. To have this connection, a ship must be a member of the network with its IP address assigned. This paper proposes a SANET-CC protocol that allows ships to be assigned their own IP address. SANET-CC propagates several non-overlapping IP addresses through the entire network from land base stations to ships in the form of the tree. Ships allocate their own IP addresses through the exchange of simple requests and response messages with land base stations or M-ships that can allocate IP addresses. Therefore, SANET-CC can eliminate the IP collision prevention (Duplicate Address Detection) process and the process of network separation or integration caused by the movement of the ship. Various simulations were performed to verify the applicability of this protocol to SANET. The outcome of such simulations shows us the following. First, using SANET-CC, about 91% of the ships in the network were able to receive IP addresses under any circumstances. It is 6% higher than the existing studies. And it suggests that if variables are adjusted to each port's environment, it may show further improved results. Second, this work shows us that it takes all vessels an average of 10 seconds to receive IP addresses regardless of conditions. It represents a 50% decrease in time compared to the average of 20 seconds in the previous study. Also Besides, taking it into account that when existing studies were on 50 to 200 vessels, this study on 100 to 400 vessels, the efficiency can be much higher. Third, existing studies have not been able to derive optimal values according to variables. This is because it does not have a consistent pattern depending on the variable. This means that optimal variables values cannot be set for each port under diverse environments. This paper, however, shows us that the result values from the variables exhibit a consistent pattern. This is significant in that it can be applied to each port by adjusting the variable values. It was also confirmed that regardless of the number of ships, the IP allocation ratio was the most efficient at about 96 percent if the waiting time after the IP request was 75ms, and that the tree structure could maintain a stable network configuration when the number of IPs was over 30000. Fourth, this study can be used to design a network for supporting intelligent maritime control systems and services offshore, instead of satellite communication. And if LTE-M is set up, it is possible to use it for various intelligent services.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.245-253
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• 2009

The importance of chloride ions in the corrosion of steel in concrete has led to the concept for chloride threshold level (CTL). The CTL can be defined as the content of chlorides at the steel depth that is necessary to sustain local passive film breakdown and hence initiate the corrosion process. Despite the importance of the CTL, due to the uncertainty determining the actual limits in various environments for chloride-induced corrosion, conservative values such as 0.4% by weight of cement or 1.2 kg in 1 $m^3$ concrete have been used in predicting the corrosion-free service life of reinforced concrete structures. The paper studies the CTL for blended cement concrete by comparing the resistance of cementitious binder to the onset of chloride-induced corrosion of steel. Mortar specimens were cast with centrally located steel rebar of 10 mm in diameter using cementitious mortars with ordinary Portland cement (OPC) and mixed mortars replaced with 30% pulverized fuel ash (PFA), 60% ground granulated blast furnace slag (GGBS) and 10% silica fume (SF), respectively, at 0.4 of a free W/B ratio. Chlorides were admixed in mixing water ranging 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binder(Based on $C1^-$). Specimens were curd 28 days at the room temperature, wrapped in polyethylene film to avoid leaching out of chloride and hydroxyl ions. Then the corrosion rate was measured using the polarization resistance method and the order of CTL for binder was determined. Thus, CTL of OPC, 60%GGBS, 30%PFA and 10%SF were determined by 1.6%, 0.45%, 0.8% and 2.15%, respectively.

• Korean Journal of Environment and Ecology
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• v.16 no.1
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• pp.34-45
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• 2002

Of the four tidal flat areas(Yeocha-ri, Dongmak-ri, Sundu-ri and Donggum-ri) on Southern Ganghwa Island, the distribution of migratory waterbirds showed a difference in the numbers of individuals and species. Higher numbers of individuals and species were observed on the Yeocha-ri tidal flat. The dominant waterbirds species at the four areas was the Dentin(Calidris alpina). This species showed an occupancy rate(42.0-79.1%) on the Yeocha-ri tidal flat, which was much higher relative to the other areas. The Yeocha-ri tidal flats were higher relative to MSL than the other tidal flats. When the Dongmak-ri tidal flat was covered by sea water, the Yeocha-ri tidal flat was 0.0317$\textrm{km}^2$ in area and on this space we observed many resting waterbirds. The biomass of the waterbirds' potential prey on the Yeocha-ri tidal flat was higher(1.6~2.5$\times$) than other tidal flats. Twenty-three species and 266 individuals were found on the Yeocha-ri tidal flat, which was higher than the tidal flats. The food of Dunlin, which was the dominant species in these four areas, was mainly Reticunassa festiva and Umbonium thomasi(Gastropoda) and Perinereis aibuitensis(Polychaeta). A Dunlin(38.11g) used to eat 1,295 individuals of these food items for daily basal energy. Gastropod, its density was highest on Yeocha-ri tidal flats. The distribution of waterbirds seemed to be closely related with the distribution of the benthos, space and safety of resting site. We suggest that the environments of tidal flats, which are rich foraging habitats, are important factors for conservation of waterbirds.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.263-270
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• 2012

The objectives of the study were to determine fish fauna and compositions during 2010~2011 in Walpyung Conservation Park along with analysis of fish community structures and trophic and tolerance guilds. Total number of species and individuals sampled were 31 and 2667, respectively and dominant species was Zacco platypus (46.6%) and subdominant species was Acheilognathus lanceolatus (8.7%), which were composed of >50% of the total. Total number of Korean endemic species including Microphysogobio yaluensis was 10 and the proportion of the individuals was 8.7%. Also, natural monument No. 454 of Iksookimia choii, which is endangered species and legal protected species, was sampled and the total number of individuals was only three. According to the analysis of fish community structures, species richness index in the mid-stream reach ($M_r$) was 3.145, which is higher than any other stream reaches ($U_r$ and $D_r$). In contrast, the richness index was 2.180 in the up-stream reach ($U_r$), which is minimum among the sampling sites. Species diversity index was 1.785 and 1.975, respectively in the headwater ($U_r$) and mid-stream reach ($M_r$) and the low values in the down-stream reach ($D_r$, 1.660) were due to the influences of pointsource (i.e., road construction) and non-point sources (sporadic agricultural spots). According to analysis of tolerance guilds, the proportion of tolerant species (TS), based on the number of individuals, was composed of 64.2% and sensitive species (SS) was only 3.3%, indicating a predominance of tolerant fishes in the compositions. The proportion of omnivore species (OS), however, was composed of 64.0% and insectivore species (IS) was 29.3%, indicating a predominance of omnivore fishes in the stream. The high proportions of tolerant and omnivore species in this stream indicates that the water quality and physical habitat environments were degradated in this system. For these reasons, especially natural monument and endemic fish species in this region should be protected from the massive constructions and required to provide efficient stream management strategies.

• Journal of Food Hygiene and Safety
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• v.26 no.3
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• pp.273-282
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• 2011

This study established hazards which may cause risk to human at farm during cultivation stage of paprika. Samples of plants (paprika, leaf, stem), cultivation environments (water, soil), personal hygiene (hand, glove, clothes), work utensils (carpet, basket, box) and airborne bacteria were collected from three paprika farms (A, B, C) located in Western Gyeongnam, Korea. The collected samples were assessed for biological (sanitary indications and major foodborne pathogens), chemical (heavy metals, pesticide residues) and physical hazards. In biological hazards, total bacteria and coliform were detected at the levels of 1.9~6.6 and 0.0~4.610g CFU/g, leaf, mL, hand or 100 $cm^2$, while Escherichia coli was not detected in all samples. In major pathogens, only Bacillus cereus were detected at levels of ${\leq}$ 1.5 log CFU/g, mL, hand or 100 $cm^2$, while Staphylococuus aureus, Listeria monocytogenes, E. coli O157 and Salmonella spp. were not detected in all samples. Heavy metal and pesticide residue as chemical hazards were detected at levels below the regulation limit, physical hazard factors, such as insects, pieces of metal and glasses, were also found in paprika farms. Proper management is needed to prevent biological hazards due to cross-contamination while physical and chemical hazards were appropriate GAP criteria.

• Journal of the Korean Geographical Society
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• v.36 no.2
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• pp.111-125
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• 2001

An estuary is semi-inclosed inlets, located between terrestrial and marine environment. Since many estuaries along south-western coasts of Korean peninsula were affected by human settlements and activities, significant changes in sedimentation environments have been observed. The research area is divided into three distinct morpho-stratigraphic units: fluvial dominated area(Area1), mixed area(Area 2), tide-dominated area(Area3). The landform of this area has been changed by reclamation and river channel change. Temporal variations affected by dam construction, periodic freshet was iterrupted. Sediments began to continuously accmulate on estuary banks by tide. Meanwhile, because of the continuous but reduced discharge of fresh water, the salinity of estuarine sediments was declined. That processes made vegetated area( Phregmites lonivalvis and Suaeda japonica) to be expanded. It indicates that the magnitude and frequency of geomorphic processes has been significantly changed.