• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.1-25
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• 1982

Limnological study on the physico-chemical properties and biological characteristics of the Lake Ok-Jeong was made from May 1980 to August 1981. For the planktonic organisms in the lake, species composition, seasonal change and diurnal vertical distribution based on the monthly plankton samples were investigated in conjunction with the physico-chemical properties of the body of water in the lake. Analysis of temperature revealed that there were three distinctive periods in terms of vertical mixing of the water column. During the winter season (November-March) the vertical column was completely mixed, and no temperature gradient was observed. In February temperature of the whole column from the surface to the bottom was $3.5^{\circ}C$, which was the minimum value. With seasonal warming in spring, surface water forms thermoclines at the depth of 0-10 m from April to June. In summer (July-October) the surface mixing layer was deepened to form a strong thermocline at the depth of 15-25 m. At this time surface water reached up to $28.2^{\circ}C$ in August, accompanied by a significant increase in the temperature of bottom layer. Maximum bottom temperature was $r5^{\circ}C$ which occurred in September, thus showing that this lake keeps a significant turbulence Aehgh the hypolimnial layer. As autumn cooling proceeded summer stratification was destroyed from the end of October resulting in vertical mixing. In surface layer seasonal changes of pH were within the range from 6.8 in January to 9.0 in guutuost. Thighest value observed in August was mainly due to the photosynthetic activity of the phytoplankton. In the surface layer DO was always saturated throughout the year. Particularly in winter (January-April) the surface water was oversaturated (Max. 15.2 ppm in March). Vertical variation of DO was not remarkable, and bottom water was fairly well oxygenated. Transparency was closely related to the phytoplankton bloom. The highest value (4.6 m) was recorded in February when the primary production was low. During summer transparency decreased hand the lowest value (0.9 m) was recorded in August. It is mainly due to the dense blooming of gnabaena spiroides var. crassa in the surface layer. A. The amount of inorganic matters (Ca, Mg, Fe) reveals that Lake Ok-Jeong is classified as a soft-water lake. The amount of Cl, $NO_3-N$ and COD in 1981 was slightly higher than those in 1980. Heavy metals (Zn, Cu, Pb, Cd and Hg) were not detectable throughout the study period. During the study period 107 species of planktonic organisms representing 72 genera were identified. They include 12 species of Cyanophyta, 19 species of Bacillariophyta, 23 species of Chlorophyta, 14 species of Protozoa, 29 species of Rotifera, 4 species of Cladocera and 6 species of Copepoda. Bimodal blooming of phytoplankton was observed. A large blooming ($1,504\times10^3\;cells/l$ in October) was observed from July to October; a small blooming was present ($236\times10^3\;cells/l$ in February) from January to April. The dominant phytoplankton species include Melosira granulata, Anabaena spiroides, Asterionella gracillima and Microcystis aeruginota, which were classified into three seasonal groups : summer group, winter group and the whole year group. The sumner group includes Melosira granulate and Anabaena spiroides ; the winter group includes Asterionella gracillima and Synedra acus, S. ulna: the whole year group includes Microtystis aeruginosa and Ankistrodesmus falcatus. It is noted that M. granulate tends to aggregate in the bottom layer from January to August. The dominant zooplankters were Thermocpclops taihokuensis, Difflugia corona, Bosmina longirostris, Bosminopsis deitersi, Keratelle quadrata and Asplanchna priodonta. A single peak of zooplankton growth was observed and maximum zooplankton occurrence was present in July. Diurnal vertical migration was revealed by Microcystis aeruginosa, M. incerta, Anabaena spiroides, Melosira granulata, and Bosmina longirostris. Of these, M. granulata descends to the bottom and forms aggregation after sunset. B. longirostris shows fairly typical nocturnal migration. They ascends to the surface after sunset and disperse in the whole water column during night. Foully one species of fish representing 31 genera were collected. Of these 13 species including Pseudoperilnmpus uyekii and Coreoleuciscus splendidus were indigenous species of Korean inland waters. The indicator species of water quality determination include Microcystis aeruginosa, Melosira granulata, Asterionelta gracillima, Brachionus calyciflorus, Filinia longiseta, Conochiloides natans, Asplanchna priodonta, Difflugia corona, Eudorina elegans, Ceratium hirundinella, Bosmina longirostris, Bosminopsis deitersi, Heliodiaptomus kikuchii and Thermocyclops taihokuensis. These species have been known the indicator groups which are commonly found in the eutrophic lakes. Based on these planktonic indicators Lake Ok-Jeong can be classified into an eutrophic lake.

• Korean Journal of Plant Resources
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• v.10 no.1
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• pp.1-5
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• 1997

Proximate composition and the contents of free sugar and amino acid of Korean arrowroot were invesigated to develop and produce the high quality processed products. A higher content of moisture, protein, and fiber were found in male arrowroot than in those of female. Among the total free sugars, sucrose was the highest components and fructose and glucose were follwed. In Korean arrowroot, 17 amino acids were determined and proline of male arrowroot and aspartic acid of female arrowroot were found to be the major components. Arginine was abundant in male arrowroot, while aspartic acid was abundant in female arrowroot on the samples of November. Leucine was abundant in male arrowroot and glutamic acid was in female arrowroot in the samples of February. Among the free amino acid of Korean arrowroots, proline was the most plentiful and major components were histidine, alanine and serine.

• Korean Journal of Plant Resources
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• v.9 no.3
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• pp.249-253
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• 1996

The study was conducted to investigate the effect of the culture with trickle with trickle irrigation in transparent vinyl house on the seed productivity of onion. Growth, number o tiller and leavers, plant height, leaf sheath length, flowering rate, diameter of flower wheel, number of little flower per flower stalk and fertilization rate are best in the case of the seed production under the culture with trickle irrigation in transparent vinyl mulching house, catch in the rain with vinyl from February to March, so it is found that it is appropriate to plant the onion mother bulb under the culture with trickle irrigation in transparent vinyl mulching house, catch in the rain with vinyl from February to March in the Southern areas of Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.4
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• pp.361-366
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• 2000

To study the abundances and species composition of microzooplankton during summer, microzooplankton were sampled fortnightly from 22 May to 3 August in Kwangyang Bay, Korea, The dominant species were Tintinnopsis spp. and Coaonellopsis sp. of tintinnids, and eggs and nauplii of copepods, They occupied $83.8{\%}$ of the total microzooplankton. The abundance of microzooplankton on 22 May was $374.6 ind./l$. It increased to 1,276.0 ind./l and 1,234.9 ind./l in June, and then reduced to $528.2{\~}609.8 ind./l$ in July and August. The abundances and species composition of microzooplankton were affected by the predation of fish larvae.

• Review of KIISC
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• v.33 no.4
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• pp.65-74
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• 2023

국제전기통신연합(ITU)은 국제연합(UN) 산하 정보통신기술(ICT)에 대한 전문 국제 표준화기구이다. 193개 회원국, 약 900개 기업 및 학계 멤버 등으로 구성되어 있으며, 산하에 전기통신표준화부문(ITU-T), 전기통신개발부문(ITU-D), 그리고 전파통신 부문(ITU-R) 등 3개의 부문으로 구성되어 있다[1]. ITU-T는 역할과 임무에 따라 11개의 연구반(SG, Study Group)으로 구성되어 있으며, 각 업무에 맞는 선도 그룹(Lead Study Group)을 지정하여 국제 표준을 개발하고 있다. 정보보안 분야 국제 표준은 ITU-T SG17(보안)에서 담당한다[2]. ITU-T 국제 표준화 조직은 4년 주기의 연구회기(Study Period)로 연구반 구조조정, 의장단 선출 및 표준화 추진 방향을 WTSA(World Telecommunication Standardization Assembly) 총회에서 결정한다. 다음 총회는 2024년 10월에 인도에서 열릴 예정이다. 본 논문에서는 지난 2022년 8/9월과 2023년 2/3월 스위스 제네바에서 열린 ITU-T SG17 회의에서 한국이 주도적으로 수행한 정보보호 표준화 활동 결과를 알아보고, 차기 연구회기(2025-2028)를 위한 SG17 구조조정에 대해 2023년 2/3월 SG17 회의 결과와 서신 그룹(CG, 5월-7월) 회의의 주요 결과를 중심으로 제시한다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.103-109
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• 1970

The results of this work concerning the growth of the mussel, Mytilus edulis cultured by the hanging method in Koje Bay are as follows: The major spawning time is confined to the period from March to April. The mean growth of the mussel is indicated by the following formula; $$Y\;=\;1.508+0.659X-0.0559X^{2}+0.00367X^3$$ The major growing seasons are June and October The variance varied in proportion to the growth of the mussel, and each ranged, in shell height, from $1.25\~2.75\;to\;2.25\~4.25$ (mean:1.60 to 2.78)cm, $2.25\~5.25(3.00)cm,\;2.25\~7.75(4.83)cm,\;2.25\~7.75(5.05)cm\;and\;2.25\~8.25(5.95)cm$, and the variance were $0.278\~0.230$, 0.368, 0.701, 1.053 and 1.209, respectively. On the other hand, the variances differed in proportion to the growth of the mussel. The average length of the mussel life was about eighteen months. The mussels growing on the hanging line for arrestation undergo seasonal vicissitudes, and the mussels which fall off, mass into countless numbers during the period from August to October and finally disappear completely in November. The dimensions of the largest mussel are as follows: The shell height : 9.48cm The shell length: 4.49cm The shell breath : 3.55cm The shell weight : 22.05g The weight of the soft parts 19.25g The relative growth of the mussel is indicated as follows: Relationship between the shell height and the shell length: Y =0.486X+0.334 Relationship between the shell height and the shell breadth: Y = 0.359X+0.107 Relationship between the weight of the soft part and the shell weight: Y = 0.882X+0.901 Relationship between the shell height and the weight of the soft part: $$Y\;=\;0.02828X^{2.90518}$$

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.76-86
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• 2008

The seasonal variations of primary production were investigated by phyto-PAM chlorophyll fluorometry as well as classical methods (standing crops of phytoplanktons and chlorophyll ${\alpha}$) in the Beopsu Marsh, Haman-gun, Gyeongsangnam-do. The amounts of turbidity, SS, T-N, T-P, BOD, COD, Ca$^{2+}$ and Cl$^-$ were the highest at the station 3, where located in flowout site of wastewater treated by the filtration plants. The water quality was the third level by the standard of BOD and COD. The amount of chlorophyll a (268.8 mg L$^{-1}$) was the highest at the station 2 in April because the cell density (2,677 cells mL$^{-1}$) of Micractinium pusillum increased suddenly from February (180 cells mL$^{-1}$). The patterns of primary production of phytoplankton by phyto-PAM chlorophyll fluorometry were fallen in with those of standing crops and chlorophyll a of phyto-planktons. The primary production was varied according to stations and seasons. The water environments of the Beopsu Marsh as a natural mounument should be under the control of a regular examination in order to preserve the ecosystem.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.70-77
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• 2003

From March 1998 to August 2000, the phenological and morphometric changes of Zostera marina L. were examined at the Duksan Port in the eastern coast of Korea. Morphometric characteristics, phenological stage, shoot density, biomass of Z. marina population and environmental parameters were also measured. Nutrient levels in water column varied over the season. Morphometric characteristics of vegetative shoot changed with season; shoot heights ranged from 54.2 cm (March) to 100.0 cm (October). Reproductive shoots appeared from mid-March to early September of which the height was ranged from 97.8 cm (March) to 213.0 cm (July). The flowering phase started at 12$^{\circ}C$ and the fruit development was resulted up to 21$^{\circ}C$. The seed maturing was developed at 22$^{\circ}C$-$25^{\circ}C$. Shoot density and biomass in permanent quadrate (0.25 m$^2$) were significantly different among seasons ranging from 38 to 136 shoots (mean 80.3$\pm$6.5) for shoot density, and 190 g dry wt m$^{-2}$ in October 1998 to 922 g dry wt m$^{-2}$ in June 1998 for biomass respectively. Relationships between shoot morphometrics and physico-chemical parameters were not significantly correlated. Seasonal changes in water temperature seemed responsible for the replacement of reproductive phases and the annual changes of shoot morphometrics in Z. marina populations.

• Development and Reproduction
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• v.11 no.3
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• pp.155-165
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• 2007

Gonad index (GI), conditon index, the reproductive cycle with gonadal development of the Neptunea (Barbitonia) arthritica cumingii, were investigated histologically, based on the samples which have been collected from the subtidal zone of Oeyeondo, Boryeong, Korea from January to December, 2006. Neptunea (Barbitonia) arthritica cumingii is dioecious and oviparous. Monthly changes in the gonad index (GI), studied for determination of spawning period, were closely associated with gonad developmental phases. The GI reached a maximum in April, and gradually decreased from May to August due to spawning. The gonadsomatic index and condition index showed similar patterns to gonad developmental phases and the spawning period. The reproductive cycle according to gonad developmental phases of this species can be classified into five successive stages in females and males: in females, early active stage (September to October), late active stage (November to February), ripe stage (February to June), partially spawned stage (May to August) and recovery stage (June to August); in males, the early active stage (September to October), late active stage (November to February), ripe stage (February to June), copulation (April to July), and recovery stage (July to August). Spawning occurred between May to August in females and April to July in males, and spawning peak in females was observed between June and July when the seawater temperature rose to above $19^{\circ}C$. Percentages of first sexual maturity of female and male snails ranging from $50.1{\sim}60.0\;mm$ in shell height were over 50%, and 100% for snails over 60.1 mm in shell height. The sex ratios of females to males were not significantly different from a 1:1 sex ratio.

• 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.