• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.2
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• pp.105-116
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• 2000

In order to investigate the seasonal variation of watermass in the central coast of the southern sea of korea, oceanographic observation on the fishing grounds were carried out by the trainingship of Yosu University on May, Aug. and Nov. in 1998 and Feb. in 1999. The resultes obtained are summerized as follows : 1). The watermass in the fishing ground were divided into the coastal water(30.0~31.6$\textperthousand$ ), mixing water(31.7~33.4$\textperthousand$) and the offshore water(33.5~35.0$\textperthousand$) according to the distribution of salinity from T-S diagram plotted all salinity data observed on May, Aug. and Nov. in 1998 and Feb. in 1999. 2) The ranges of temperature and salinity were from 14.1$^{\circ}C$ to 18.8$^{\circ}C$ and from 32.2$\textperthousand$ to 34.9$\textperthousand$ in spring(May), from 14.2$^{\circ}C$ to 27.7$^{\circ}C$ and from 29.0$\textperthousand$ to 34.7$\textperthousand$ in summer(August), from 13.4$^{\circ}C$ to 21.3$^{\circ}C$ and from 31.45$\textperthousand$ to 34.5$\textperthousand$ in autumn(November) and from 8.2$^{\circ}C$ to 14.8$^{\circ}C$ and from 33.9$\textperthousand$ to 34.6$\textperthousand$ in winter(February), respectively. 3) The distribution of watermass in the fishing ground varied largely each seasons, but a general tendency on the distribution was obtained. That is, in spring and autumm the offshore water was distributed most widely and in summer the coastal and mixing water occupied the fishing ground but in winter the offshore water prevailed. 4) Variation of temperature and salinity were appeared between the surface and 30m in the coastal region and between the surface and 50m in the open ocaen region. Therefore, in the summer the thermocline and halocline were made between surface and 30m layer with vertical gradients of 10.5$^{\circ}C$/30m and 4.0$\textperthousand$/30m in the coastal region and in the open ocean region the thermocline and halocline were made between surface and 50m layer with vertical gradients of 13.$0^{\circ}C$/50m and 3.8$\textperthousand$/50m.

• Korean Journal of Environmental Agriculture
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• v.13 no.3
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• pp.251-261
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• 1994

This study was conducted to get some basic information about rice plant development rate and heading ecology in various climatic conditions, growing nine varieties at three locations, Jinbu as the mountainous cool area, Suweon and Iri as the plain area for two years from 1987 to 1988. Average daily air temperature and day length from transplanting to heading date were analyzed in relation to the heading. Heading date and development rate of each variety were estimated by the Symplex method and the fitness of the model was evaluated. The results obtained as follows: Average daily air temperatures among varieties during the period from transplanting to heading ranged from 18 to $19^{\circ}C$ in Jinbu, from 22.5 to $23.5^{\circ}C$ in Suweon, and from 23.5 to $24.5^{\circ}C$ in Iri, the late-maturing varieties requiring the higher temperatures. The average heading days were about 20 days longer in Jinbu and $3{\sim}5$ days shorter in Iri than those in Suweon in all varieties. Little differences in accumulated temperature from transplanting to heading were observed in regions and years, and also among varieties. Developmental stages could be expressed as the accumulation of daily development rate and the predicted heading dates by the Symplex method were similar to the observed ones. The development rate of each variety varies with air temperatures. The early maturing Japonica types including the Unbong variety were fast in development rate at lower temperatures, but the late-maturing varieties of the Japonica type were late. A model to predict the heading dates of rice varieties by the Symplex method using air temperatures and day lengths was feasible.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.101-115
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• 2018

This study was carried out to evaluate the effects of various filter conditions on unconfined aquifer (alluvial aquifer). We made model test device which has filter layer, pumping well and observation well which consist of sand layer and gravel layer to test. Step drawdown test and long term pumping tests were carried out using the device. The permeability characteristics of each test group were confirmed and the optimal yield was calculated. As a result of comparing the optimal yield of double filter and single filter in sand, dual-filter SD-300 was valued at 216.8 % higher final optimal yield than single-filter SS-300. Comparing the dual filter SD-300 and the single filter SS-100 with a thin filter layer, dual-filter SD-300 was valued at 709.2% higher final optimal yield than single-filter SS-300. As a result of analysis of optimal yield change over time, It was confirmed that the ratio of optimal yield of single filter and dual filter increase over time. In order to evaluate the long-term change in water intake efficiency, we considered the point at which the initial optimal yield was reduced by 50%. The dual filter SD-300 is about 351.1% higher than SS-300, which is the same thickness filter, and about 579.0% higher than SS-100. From these results, Assuming that the point at which the initial quantity of water intake is reduced to 50% is the well life, double filters are expected to increase their lifespan by about 3.5 times over single filters of the same thickness and by about 5.8 times over typical single filter. These results can be used to design wells to river bank filtration or filtered seawater. In addition, it is possible to clarify the effect of the double filter through the comparison with the future field test results.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.10 no.1
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• pp.1-18
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• 1974

Some coastal oceanographic investigations in Kwang Yang Bay were carried out bimonthly from April to September (The first half period of the research project) in 1974. The behaviour of the waters, distributions of water temperature and salinity and diffusion characteristic by dye release experiments in the bay are studied for the problems of practical importance in connection with water pollution. Velocities and directions of tidal currents at five fixed stations were observed. And dye diffusion experiment was also carried out on the sea. According to the results from this study, the salinity of the water is lower, ranging from about $28\;\textperthousand\;to\;32\textperthousand$, on all over the surface in the bay with the cause that the fresh water flows in from the Sumjin river. Diffusivities in this sea by means of Rhodamine B diffusion elliperiment were $785.6\;{\times}\;10^2\;\textrm{m}^2/sec$ in major axis, $15.6\;{\times}\;10^2 \;\textrm{m}^2/sec$/sec in minor axis in the direction on patch after 30 minutes from the dye release.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.306-317
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• 2014

This study has been executed to understand the additional and removal processes of nutrients in the Saemangeum Salt-water Lake, and discussed with other monthly-collected environmental parameters such as water temperature, salinity, dissolved oxygen, suspended solids, and Chl-a from 2008 to 2010. $NO_3$-N, TP, $PO_4$-P, and DISi showed the removal processes along with the salinity gradients at the surface water of the lake, whereas $NO_2$-N, $NH_4$-N, and Chl-a showed addition trend. In the bottom water all water quality parameters except $NO_3$-N appeared addition processes indicating evidence of continuous nutrients suppliance into the bottom layer. The mixing modelling approach revealed that the biogeochemical processes in the lake consume $NO_3$-N and consequently added $NH_4$-N and $PO_4$-P to the bottom water during the summer seasons. The $NH_4$-N and $PO_4$-P appeared strong increase at the bottom water of the river-side of the lake and strong concentration gradient difference of dissolved oxygen also appeared in the same time. DISi exhibited continuous seasonal supply from spring to summer. Internal addition of $NH_4$-N and $PO_4$-P in the river-side of the lake were much higher than the dike-side, while the increase of DISi showed similar level both the dike and river sides. The temporal distribution of benthic flux for DISi indicates that addition of nutrients in the bottom water was strongly affected by other sources, for example, submarine ground-water discharge (SGD) through bottom sediment.

• Journal of Korea Water Resources Association
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• v.51 no.2
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• pp.141-150
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• 2018

The purpose of this study is to evaluate the future hydrologic behavior affected by the potential climate and land use changes in upstream of Anseong-cheon watershed ($366.5km^2$) using SWAT. The HadGEM3-RA RCP 4.5 and 8.5 scenarios were used for 2030s (2020-2039) and 2050s (2040-2059) periods as the future climate change scenario. It was shown that maximum changes of precipitation ranged from -5.7% in 2030s to +18.5% in 2050s for RCP 4.5 scenarios and the temperature increased up to $1.8^{\circ}C$ and $2.6^{\circ}C$ in 2030s RCP 4.5 and 2050s 8.5 scenarios respectively based on baseline (1976-2005) period. The future land uses were predicted using the CLUE-s model by establishing logistic regression equation. The 2050 urban area were predicted to increase of 58.6% (29.0 to $46.0km^2$). The SWAT was calibrated and verified using 14 years (2002-2015) of daily streamflow with 0.86 and 0.76 Nash-Sutcliffe model efficiency (NSE) for stream flow (Q) and low flow 1/Q respectively focusing on 2 drought years (2014-2015) calibration. For future climate change only, the stream discharge showed maximum decrease of 24.2% in 2030s RCP 4.5 and turned to maximum increase of 10.9% in 2050s RCP 4.5 scenario compared with the baseline period stream discharge of 601.0 mm by the precipitation variation and gradual temperature increase. While considering both future climate and land use change, the stream discharge showed maximum decrease of 14.9% in 2030s RCP 4.5 and maximum increase of 19.5% in 2050s RCP 4.5 scenario by the urban growth and the related land use changes. The results supported that the future land use factor might be considered especially for having high potential urban growth within a watershed in the future climate change assessment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.435-444
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• 2001

Daily time series of longshore wind at 8 stations, sea surface temperature (SST) at 11 stations in the eastern coast of the Korean peninsula during $1983\~1997$ and the NOAA/AVHRR satellite data during $1990\~1998$ were used in order to study the temporal and spatial variations of the upwelling cold water which occurred in the summer season. The cold water occurred frequently in the eastern coastal waters of Korea such as Soimal, Kijang, Ulgi, Kampo, Pohang, Youngduk, Chukbyun, Chumunjin and Sokcho, During the upwelling cold water phenomenon, SST came down more than $-5^{\circ}C$ in a day. The maximum of the averaged RMS amplitude of daily SST was $5.8^{\circ}C$ along the eastern coast of Korea on Julian day 212 from $1983\~1997$. The cross correlation coefficients were higher than 0.5 between Sokcho and Chumunjin in the northern part of the East Sea, and along Soimal, Kijang, Ulgi, Kampo and Pohang in the southern part of the East Sea. In late July, 1995 the cold water occurred at Ulgi coastal area and extended to Ullung island which is located 250 km off the Ulgi coast. Even though the distance between Soimal and the Ulgi coast area is more than 120 km, the cross correlation coefficient related to the anomalies of SST due to upwelling cold water was the highest (0.7) in the southeastern coastal area of the Korean peninsula. This connection may be due to the cyclonic circulation of the Tsushima Current in this area and the topography of the ocean rather than the local south wind which induced the coastal upwelling.

• Journal of Animal Science and Technology
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• v.55 no.1
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• pp.41-49
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• 2013

In vitro and in situ incubation studies were conducted to determine effects of yeast culture supplements (Saccharomyces cerevisiae) on cellulolytic bacterial function and fiber digestion in rice straw. In vitro dry matter digestibility of rice straw gradually increased according to supplemental levels of yeast culture (0.0, 0.2, 0.4, 0.6, 0.8 and 1.0%). Digestibility of rice straw started to increase apparently when yeast culture was added more than 0.6% level (p<0.05). Also, we reconfirmed that in vitro dry matter digestibility was significantly increased by 0.6% of yeast culture addition in 4% NaOH treated and non-treated rice straws (p<0.05). When in situ dry matter digestibility was tested in Korean native goats fed basal diet or experimental diet which contained 1.0% of yeast culture, the yeast culture feeding improved in situ dry matter digestibility in both 4% NaOH treated and non-treated rice straws (p<0.05). In case of real-time PCR monitoring cellulolytic bacterial function, the bacterial population attached on rice straw showed the increasing trends with higher level of yeast culture spraying on rice straw. F. succinogenes and R. flavefaciens were significantly increased in accordance to spraying levels of yeast culture (0.0, 0.1 and 0.3%) at both 12 and 24 hrs of in situ incubation (p<0.05). R. albus was significantly higher population in yeast culture spraying than non-soraying at 12 hrs of in situ incubation (p<0.05). These bacterial populations were showed the increasing trends with digestibility enhancement of rice straw according to the higher levels of yeast culture supplement. Overall, these results clearly suggest that the presence of yeast culture result in noticeable increase of rice straw digestion, which is modulated via good effect on cellulolytic bacterial attachment to fiber substrates.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.109-119
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• 2016

The height datum of Korea is currently separated into land and sea, which makes it difficult to acquire homogeneous and accurate height information throughout the whole nation. In this study, we therefore tried to suggest the more effective way to transform the height information were constructed separately according to each height datum on land and sea to those on the unique height datum using precise geoid models and tidal observations in Korea. For this, Anmyeon island was selected as a study area to develop the precise geoid models based on the height datums land (IMSL) and sea (LMSL), respectively. In order to develop two hybrid geoid models based on each height datum of land an sea, we firstly develop a precise gravimetric geoid model using the remove and restore (R-R) technique with all available gravity observations. The gravimetric geoid model were then fitted to the geometric geoidal heights, each of which is represented as height datum of land or sea respectively, obtained from GPS/Leveling results on 15 TBMs in the study area. Finally, we determined the differences between the two hybrid geoid models to apply the height transformation between IMSL and LMSL. The co-tidal chart model of TideBed system developed by Korea Hydrographic and Oceanographic Agency (KHOA) which was re-gridded to have the same grid size and coverage as the geoid model, in order that this can be used for the height datum transformation from LMSL to local AHHW and/or from LMSL to local DL. The accuracy of height datum transformation based on the strategy suggested in this study was approximately ${\pm}3cm$. It is expected that the results of this study can help minimize not only the confusions on the use of geo-spatial information due to the disagreement caused by different height datum, land and sea, in Korea, but also the economic and time losses in the execution of coastal development and disaster prevention projects in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.3
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• pp.269-274
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• 2010

Present state of nationwide marine facilities reported to Minister of Land, Transport and Maritime Affairs{MLTM} in Korea for two years 2008 and 2009 was analyzed, and management plan was proposed in this study. As of the end of 2009, total number of nationwide marine facilities was reported to be 672 and to be scattered along the coasts all over the nation. 124 marine facilities reported to Masan regional maritime affairs and port office occupied 18.5% of total nationwide number. 69 marine facilities reported to Mokpo regional office and 69 marine facilities reported to Pohang regional office occupied 10.3%, respectively. 181 marine facilities reported to Busan and Masan regional offices occupied 26.9%, meaning that about a quarter of total nationwide marine facilities concentrated in Southeastern Sea of Korea centering around Busan and Masan. 320 oil and noxious liquid substances storage facilities occupied 47.6% of total nationwide number. 11 pollutant storage facilities occupied 1.6%. 178 ship construction, repair and scrap facilities occupied 26.5%. 7 cargo handling facilities occupied 1.0%. 12 waste storage facilities occupied 1.8%. none of marine facilities for tourism, housing and restaurant were reported. 88 water intake and outlet facilities occupied 13.1%. 37 fishing spots at play occupied 5.5%. 13 other marine facilities occupied 1.9%. 6 integrated marine science base facilities occupied 0.9% of total nationwide number. The guidance and the public relation for national report system of marine facilities, the improvement of national report system and management plan, the advancement and complement of national report affairs-handling guides, and the voluntary participation in national report system and the performance of duties by the owners of marine facilities were proposed for better management plan of marine facilities.