• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.147-158
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• 2007

To clarify the bloom pattern and species succession in phytoplankton community, the population dynamics with the determination of physico-chemical factors have been studies in Masan Bay, the south sea of Korea, for the periods November 2003-October 2004. Concentration of $NH_4-N$ was always higher than that of $NO_3-N$, which was similar level as compared to other costal areas. $PO_4-P$ concentration was lower than those in other coastal areas but similar to oligotrophic environments. Thus, phosphate seems the limiting nutrient rather than nitrogen. $SiO_2-Si$ concentration was also low as compared to other costal areas. Si:P ratio was low from autumn to winter, suggesting silicate and/or phosphate limitation during this period. The cell density of phytoplankton was high in winter 2003 and early autumn 2004. The carbon biomass was high in winter 2003 and summer 2004. And chlorophyll-a concentration was high in late autumn 2003 and summer 2004. Among 78 species of phytoplankton found in the bay during the investigated period, dominant species were two diatoms of Cylindrotheca closterium, Skeletonema costatum, and three dinoflagellates of Heterocapsa triquetra, Prorocentrum minimum, P. triestinum, and one raphidophyte of Heterosigma akashiwo. P. minimum dominated from late autumn to winter, but it was replaced by H. triquetra in late winter. P. triestinum dominated from late spring to early summer. Simultaneously, H. akashiwo cell density steadily increased, and it became dominant with C. closterium in late summer. With decreasing of H. akashiwo and C. closterium, S. costatum became the most dominant species in autumn. The canonical analyses showed that total phytoplankton cell density related to diatom cell density and it was affected by temperature, and concentrations of $NO_3-N\;and\;PO_4-P$. The carbon bio-mass and $chlorophyll-{\alpha}$ concentration related to diatom- and dinoflagellate cell densities and these were affected by flagellate cell density, salinity, and concentrations of $SiO_2-Si\;and\;PO_4-P$. Last six years monitoring data in Masan city obtained from Korean Meteorological Agency indicates gradual increase in air temperature. And the precipitation decreased especially in spring season. The winter bloom found in 2003 may be caused by the increase in the temperature and this bloom subsequently induced the nutrients depletion, which continued until next spring probably due to no precipitation. Therefore, the spring bloom, which had been usually observed in the bay, might disappear in 2004.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.102-112
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• 2006

The change of species composition and stand structure along altitudinal gradients in different aged stands was studied in five natural stands located each at 400 m, 800 m, 1,000 m, and two at 1,300 m above sea level (asl) in the western part of Mt. Chiri in Korea. Trees larger than 2.5 cm DBH were inventoried in 3 to 8 $20m{\times}20m$ quadrats in each study site. Stand ages were estimated based on the ages of Pinus densiflora Siebold & Zucc. and Abies koreana Wilson, and used to analyze the changes in species composition and stand structure including diameter and height distributions. Species composition was changed along altitudinal gradients as P. densiflora dominated stands at 400 m asl while A. koreana dominated stands at 1,300 m asl. Major species of Quercus also changed along altitudinal gradients as Quercus variabilis Blume at 400 m asl, Quercus serrata Thunb. ex Murray at 800 m asl, and Quercus mongolica Fisch. ex Ledeb. at higher than 1,000 m asl. The diameter distribution did not show significant differences among stands of different altitudes. However, the height distributions of upper crown layers were significantly different among stands at below and above 1,000 m as) (P < 0.0001). Trees taller than 20 m rarely appeared in stands over 1,000 m asl. P. densiflora dominant stands at 400 m asl developed two clumped age groups as one in 30-40 ages and the other around 70 years old. Q. serrata dominant stands at 800 m asl, Q. mongolica dominant stands at 1,300 m asl and A. koreana dominant stands at 1,300 m asl were estimated to be around 30, 70, and over 140 years old after major disturbances, respectively. The diameter distribution with age structure indicated that P. densiflora at 1,300 m asl might be replaced by Q. mongolica, and Q. mongolica might be replaced by A. koreana and Pinus koraiensis later. A. koreana dominant stand seemed to stay its dominance quite long if the large disturbance would be absent.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.1
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• pp.11-22
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• 2010

According to IPCC 4th Assessment Report, concentration of carbon dioxide has been increasing by 30% since Industrial Revolution. Most of IPCC $CO_2$ emission scenarios estimate that the concentration will reach up to double of its present level within 100-year if the current tendency continues. The global warming has resulted in the agro-climate change over the Korean Peninsula as well. Accordingly, it is necessary to understand the future agro-climate induced by the increase of greenhouse gases in terms of the agro-climatic indices in the Korean peninsula. In this study, the future climate is simulated by an atmosphere/ocean/land surface/sea ice coupled general circulation climate model, Pusan National University Coupled General Circulation Model(hereafter, PNU CGCM), and by a regional weather prediction model, Weather Research and Forecasting Model(hereafter, WRF) for the purpose of a dynamical downscaling. The changes of the vegetable period and the crop growth period, defined as the total number of days of a year exceeding daily mean temperature of 5 and 10, respectively, have been analyzed. Our results estimate that the beginning date of vegetable and crop growth periods get earlier by 3.7 and 17 days, respectively, in spring under the $CO_2$-doubled climate. In most of the Korean peninsula, the predicted frost days in spring decrease by 10 days. Climatic production index (CPI), which closely represent the productivity of rice, tends to increase in the double $CO_2$ climate. Thus, it is suggested that the future $CO_2$ doubled climate might be favorable for crops due to the decrease of frost days in spring, and increased temperature and insolation during the heading date as we expect from the increased CPI.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.254-259
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• 2012

Peeling damage of trees is usually caused by Cervidae such as deer, roe deer because of the lack of food in forests. However, it happens as part of the developing of antlers in Jeju Island when the roe deer try to remove the Velvet-the skin of the antlers. The research area is the Hannam experimental forest (400 m up to 500 m above sea level) of Korea Forest Research Institute in Jeju Island, and the survey was carried out along the 6 km long of forest road with 5 m width on both sides. Twenty five tree species (total 267 stands) are damaged by peeling; 18 (134 stands) deciduous broad-leaved species, 5 (71 stands) in evergreen broad-leaved species, 2 (62 stands) coniferous species. The most common damaged species are in order of Daphniphyllum macropodum, Cryptomeria japonica, Lindera erythrocarpa, Clerodendrum trichotomum, Zanthoxylum schinifolium. Mainly damaged trees are approximately 3~4 years old saplings, and they show the mean height $120.7{\pm}42.4cm$, diameter measured at 5 cm height $1.5{\pm}0.5cm$. The Lowest peeling beginning height is $22.1{\pm}10.1cm$, and the mean length of peeling is $27.5{\pm}10.6cm$. Once the peeling damage happens, the saplings are infected by fungi secondly, and are distorted or dead, therefore the future structure of warm-temperate forests could be in influenced in species. Warm-temperate forest landscape and species change related to the climate change is a rising issue in Jeju Island. However the changes caused by peeling damage also could be an important issue in the natural process of forest environment, afforestation, local nursery and sustainable forest management of Jeju Island.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.3
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• pp.88-102
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• 2017

Long-term changes in bathymetry and grain size of surface sediments were investigated for understanding depositional sedimentary environments in the channelized Yeongsan River Estuary, Korea. The results revealed that an average depth of the estuary had decreased up to 2.1 m from 1982 to 2006, while it had increased to 0.3 m from 2006 to 2012. The rapid decrease of the water depth from 1982 to 2006 was due to the vast deposition of mud caused by the change of water course and flow velocity after the estuary was dammed. Meanwhile the increase of the water depth from 2006 to 2012 may be associated with multiple erosional processes, including a dredging at the southern part of the estuary and other erosions from the dike sluice expansion work. Considering the water-depth change and tidal-level variation in the study area, an depositional rate in the estuary is estimated to be 8~9 cm/yr for the last 2 decades (1982~2006). The sediments of Yeongsan River Estuary are largely composed of silt-clay mixtures: overall, silt is distributed mainly in the shallow area of the estuary edge, while clay is confined to the deep area of the estuary center. Mean grain size of the sediments is 6.0 Ø on average in 1997, 7.8 Ø on average in 2005 and 7.7 Ø on average in 2012, respectively, suggesting that the sediments became finer due to the increase of silt and clay contents in 1997~2005. Furthermore, several lines of evidences, including the comparison between the amounts of the sediment influx discharged from the Yeongsan River and the sediments in the estuary, and the changes in distribution pattern of silt and clay contents implying that they moved from offshore to estuary dike, indicate that the mud sediments are originated mainly from the offshore, not from the river.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.136-143
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• 2021

Pacific island countries, including Kiribati, are suffering from a shortage of essential resources as well as a reduction in their living space due to sea level rise and coastal erosion from climate change, groundwater pollution and vegetation changes. Global activities to solve these problems are being progressed by the UN's efforts to implement SDGs. Pacific island countries can adapt to climate change by using abundant marine resources. In other words, seawater plants can assist in achieving SDGs #2, #6 and #7 based on SDGs #14 in these Pacific island countries. Under the auspice of Korea International Cooperation Agency (KOICA), Korea Research Institute of Ships and Ocean Engineering (KRISO) established the Sustainable Seawater Utilization Academy (SSUA) in 2016, and its 30 graduates formed the SSUA Kiribati Association in 2017. The Ministry of Oceans and Fisheries (MOF) of the Republic of Korea awarded ODA fund to the Association. By taking advantage of seawater resource and related plants, it was able to provide drinking water and vegetables to the local community from 2018 to 2020. Among the various fields of education and practice provided by SSUA, the Association hope to realize hydroponic cultivation and seawater desalination as a self-support project through a pilot project. To this end, more than 140 households are benefiting from 3-stage hydroponics, and a seawater desalination system in connection with solar power generation was installed for operation. The Association grows and supplies vegetable seedlings from the provided seedling cultivation equipment, and is preparing to convert to self-support business from next year. The satisfaction survey shows that Tarawa residents have a high degree of satisfaction with the technical support and its benefits. In the future, it is hoped that SSUA and regional associations will be distributed to neighboring island countries to support their SDGs implementations.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.526-536
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• 2015

Changes of oxygen consumption in juvenile giant grouper, Epinephelus lanceolatus were investigated in order to find out the physiological responses associated with freshwater and low salinities acclimation. Salinity changes in this experiment were set as follows; 35 psu (Exp. I) as control, decrease in the manners of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu (Exp. II), $35{\rightarrow}10{\rightarrow}0$ psu (Exp. III) and $35{\rightarrow}0$ psu (Exp. IV). The average oxygen consumption at $27^{\circ}C$ in Exp. I (control) was $106.9{\pm}0.7mg$ $O_2/kg/h$. In Exp. II, according to the changes of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu in freshwater acclimation, fish showed the gradual decrease in oxygen consumption as $108.1{\pm}2.1$, $99.6{\pm}2.9$, $74.6{\pm}0.9$ and $62.7{\pm}1.0mg$ $O_2/kg/h$, respectively. The fish in Exp. III also revealed the same tendency as $106.5{\pm}1.3$, $77.0{\pm}1.2$ and $64.7{\pm}1.2mg$ $O_2/kg/h$, respectively. In Exp. IV, fish showed the decreased oxygen consumption from $109.0{\pm}0.9mg$ $O_2/kg/h$ of 35 psu to $71.6{\pm}2.0mg$ $O_2/kg/h$ of 0 psu. Giant grouper is thought to be a diurnal fish species, because the level of oxygen consumption during light period was higher than that during dark period.

• Journal of Wetlands Research
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• v.17 no.1
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• pp.26-37
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• 2015

Halophyte distribution pattern and area in the Suncheon-bay and Beolgyo estuary coastal wetlands were analyzed using KOMPSAT-2 landsat images were taken in 2008 and 2009, and field investigations were fulfilled for confirming the precise boundaries of individual halophyte areas. The salt-marsh vegetation in those areas can be classified mainly into two dominant communities: Suaeda japonica-dominant and Phragmites communis-dominant communities. In order to identify sedimentary characteristics, tidal-flat surface leveling and sedimentary facies analysis had been conducted. The sedimentary facies of marsh area are mostly silty clayey and clay facies with a little seasonal change and its slope is very gentle (0.0007~0.002 in gradient). Phragmites communis and Suaeda japonica communities were distributed in the mud-flat zone between 0.7 m and 1.8 m higher than MSL (mean sea level): zone of 1.1~1.8 m in the former and zone of 0.7~1.3 m in the latter. In the Suncheon-bay estuarine wetland, on the basis of 2009 distribution, Phragmites communis-dominant and Suaeda japonica-dominant communities are about $0.79km^2$ and $0.22km^2$ in distribution area, respectively. On the other hand, Bulgyo estuarine marsh shows that the distribution areas of Phragmites communis-dominant and Suaeda japonica-dominant communities are about $0.31km^2$ and 0.031km2 in distribution area, respectively. Individual 105 and 60 dominant community areas and their distribution patterns can be well defined and indicated in the Suncheon-bay and Bulgyo estuarine marshes, respectively. The distribution pattern and area of hylophyte communities analyzed in this study based on 2008/2009 satellite images would be valuable as a base of future monitoring of salt-marsh related studies in the study area which is the most important salt-marsh research site in Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.81-96
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• 2011

Sediment oxygen demand(SOD) and denitrification rates were measured in four major estuaries(Suncheon Bay, Seomjin river estuary, Goseong stream estuary and Masan Bay) in south coast of Korean peninsula from March of 2009 to May 2010 to estimate organic matter cleaning capacity. SOD was estimated from the temporal dissolved oxygen concentration change and isotopic pairing technique was employed to measure denitrification. Sediment oxygen demand(SOD) was ranged from -5.1 to 24.6 mmole $O_2m^{-2}d^{-1}$ and denitrification rate was ranged from 0.0 to 3.9 mmole $N_2m^{-2}d^{-1}$in the study area. SOD was the highest in Masan Bay(-2.2 to 19.2, average = 10.2 mmole $O_2m^{-2}d^{-1}$) and Suncheon, Goseong, Tae-an and Seomjin followed. Denitrification was also the highest in Masn Bay(0.0 to 3.9, average = 1.0 mmole $N_2m^{-2}d^{-1}$) and Goseong, Seomjin, Suncheon and Taean followed. The effect of benthic photosynthesis by microphytobenthos on denitrification was evident in some season of Tae-an, Seomjin, and Masn Bay. The increased oxygen level produced by photosynthesis stimulated nitrification without severe adverse effect on denitrification and, as a result, coupled nitrification and denitrification was enhanced in these areas. A difference of seasonal patterns of denitrification at each site depended on relative importance of denitrification on different nitrate source($D_w$: nitrate from water column and $D_n$: nitrated produced during nitrification). Denitrification was maximum during spring in Goseong, Suncheon and Masan Bay. On the contrary, denitrification was the highest during summer in Tae-an and Seomjin estuary.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.95-101
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• 2012

This study was conducted to investigate the effect of climate conditions during cultivation and harvesting on the quality and storability of fresh bulb cabbage (Brassica oleracea L. var. capitata). Plug seedlings of six cabbage cultivars were transplanted to Gangneung-Wonju University high elevation research station in Gangwon province (780 m above sea level, lat. $37.5^{\circ}N$.) and harvested with four different harvest times like August 3 ($1^{st}$), August 13 ($2^{nd}$), August 23 ($3^{rd}$), and September 10 ($4^{th}$), respectively from 50 days after transplanting. Weight loss, Hunter color factors, firmness, and soluble solids content (SSC) of the cabbage bulbs were investigated during storage at $3^{\circ}C$ (85% RH) and $25^{\circ}C$ (60% RH). Decreased bulb weight and poor quality cabbages were apparent at the late transplanting (July 14) and harvest (September 10) respectively. Quality index such as firmness and SSC at August 23 ($3^{rd}$) harvested cabbage was better than August 3 ($1^{st}$) and August 13 ($2^{nd}$) cabbages due to the good weather condition just before harvesting. The cv. 'Speed king' and 'Minix 40' showed good qualities among the cultivars, especially when the bulbs were harvested during sunny day conditions from one week before harvesting. Also SSC was influenced by weather condition before harvesting rather than transplanting date, while firmness was influenced by transplanting and harvest date. However, the differences among the cultivars were not significant. The potential of storage as maintaining the quality was different, depending on weather conditions at harvest time. Generally the storage periods of six cultivars were around 3~5 days and 9~10 days at room and low temperature, respectively. However, the August 3 ($1^{st}$) harvested cabbage lost their marketable quality very fast because of rainy and cloudy weather condition before harvesting and also storability of bulbs was 2 days and 4 days at room temperature and $3^{\circ}C$, respectively. Quality index was also not significant difference among cultivars.