• Korean Journal of Ichthyology
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• v.32 no.1
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• pp.1-7
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• 2020

Investigations of distribution status and extinction threat evaluation of the Korean endemic species, Iksookimia yongdokensis were undertaken from 2017 to 2018. Among the 22 streams and 97 sampling sites investigated during the study period, samples of I. yongdokensis were collected from 9 streams at 37 sites (from Daejongcheon Stream of Gyeongju-si to Songcheon Stream of Yeongdeok-gun). The appearance of I. yongdokensis was relatively common in streams such as Hyeongsangang River (15 stations), Yeongdeok Oshipcheon Stream (4 stations), Gokgangcheon Stream (4 stations), Chuksancheon Stream (3 stations) and Daejongcheon Stream (3 stations). The main habitat of I. yongdokensis was in pools on flat-land in streams of clean water with slow velocity, and with pebble, gravel and sand bottoms. Previous records of the appearance of I. yongdokensis, indicate they were first seen at seven stations including Jangsacheon Stream, but they were not present in Songcheon Stream. Compared to our results there is evidence as noted for a 38.9% reduction in occupancy within 3 generations (10.5 years), and a decline inhabitat quality. Therefore, I. yongdokensis is now considered vulnerable (VU A2ace) based on the IUCN Red List categories and criteria. The main reasons for the decline were assumed to be dry weathering in the river, the introduction and diffusion of exotic fish species Micropterus salmoides, and river refurbishment project.

• Journal of Aquaculture
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• v.11 no.3
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• pp.337-344
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• 1998

This paper documented mophological changes of embryonic development and first zoea larvae of snow crab, Chinoecetes opilio. Female crabs were sampled by the Danish seine fishery at the depth about 200m in Sep. 1997 in the eastern coast of Korea. Female with newly berried eggs was reared at the water temperature of 5$^{\circ}C$ till the time of hatching. The results obtained are as follwos. Embryonic development : According to morphogenesis of fertilized eggs, the developemental process of the embryo was classified into the following seven stages : First stage (cleavage and blastula stage, 24 days) Second stage (gastrula stage, 72 days) Third stage (nauplius stage, 22 days) Fourth stage (metanauplius stage, 57days) Fifth stage (stage of a pigmentary deposit in the compound eye, 30 days) sixth stage (chromatophore appearance stage in maxillipede, 56 days) Seventh stage (hatching stage, 36 days) Larvae hatched as prezoeas and they molted to first zoea in about an hour. The first zoea is 4.6 to 5.1mm in length, 3.2~3.6mm in width. The abdomen consists of five segments and a bifurcate telson.

• Journal of Preventive Medicine and Public Health
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• v.34 no.2
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• pp.131-140
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• 2001

Objectives : During March-May, 2000, a measles outbreak occurred at Youngduk, Korea. This county is divided into two areas with different historical and socioeconomic background. The outbreak occurred in one of these areas. We conducted a comparative epidemiologic study on the two areas in order to evaluate the factors related to the epidemic. Materials and Methods : We selected two groups, grades 3 and 5 in a primary schools in each area. We investigated outbreak-related factors using parent-questionnaires, the vaccination history from the student's health record and the records concerning the recent measles-outbreak from the local health center. Serologic test on measles-IgG and -IgM antibody was done. Results : The infection rate was 31.5% for the epidemic area and 3.7% for non-the epidemic area according to clinical or serological criteria (p<0.001). No difference was seen in the measles vaccination rate, residence at the time of vaccination or past measles infection history between the two areas. In the epidemic area, the attack rate for the 4-6 year-old MMR booster group(20.5%) was higher than the non-booster group(32.4%), but was not found significantly. Vaccine efficacy was 29.6% in the epidemic area and 87.0% in the non-epidemic area (p<0.001). The IgG level and positive rate were significantly different between the two areas (median 10727 IU/ml, 98.9% in epidemic area; median 346 IU/ml, 85.9% in the non-epidemic area, p<0.001). However, the IgG level and positive rate between the measles-cases and non-cases were not significantly different. Conclusions : This outbreak took place in mostly vaccinated children. These results suggest that a reduction of herd immunity for immunity failure after vaccination may be one of the feasible factors related to the outbreak pattern in the two areas. The results of the IgG level and positive rate suggest that re-establishment of a normal value for IgG level and of a qualitative method for IgG are needed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.497-502
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• 1996

Artificial fertilization of ice fish, Mypomesus transpaciticus nipponensis caught at Milyang-river and Osib-chun brook was performed in March 24, 1990, and the hatched larvae were reared for 25 days to describe the development of eggs and larvae. Fertilized eggs were spherical in shape, measuring $0.85\~1.05\;mm$ in diameter (mean: 0.97 mm) and translucent adhesive with many small-sized oil globules on the surface. Hatching in the indoor tank started from the 170 hours after fertilization under $16.5^{\circ}C$ water temperature. Newly-hatched larvae were measured $3.85\~4.25\;mm$ in total length (mean: 4.05 mm), and mouth and anus were not yet open. They had one yolk sac on the anterior part of abdomen, straight-type's notochord, and $52\~54$ myotomes. The larva of 5 days old transformed to postlarval stage and measured $5.20\~5.65\;mm$ (mean: 5.37 mm) in total length. As the yolk sac was completely absorbed, mouth and anus were open, and they fed rotifers vigorously. In 20 days after hatching, the larvae grew to 8.38 mm in TL, and the caudal notochord flex at $45^{\circ}$. In 25 days after hatching, total length reached 9.63 mm. The pan of the fin-fold of the future dorsal and anal fins became high.

• The Journal of the Petrological Society of Korea
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• v.25 no.2
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• pp.121-142
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• 2016

The Satkatbong pluton was studied with other plutons together, but some fundamental petrological characteristics were missing. This study mainly reports the petrography and geochemistry of the Satkatbong pluton comparing with the Daebo and the Bulguksa granitoids in south Korea. The Satkatbong pluton, which is host rock including a number of Mafic Magmatic Enclaves (MME), is north-south shaped dioritic pluton, located along the east coast of south Korea. The Satkatbong pluton seems to be unconformable with Cretaceous sedimentary rocks from fieldwork result. In geochemistry, the Satkatbong pluton, which is roughly similar with the Daebo granitoids, is classified into calc-alkali series rock and volcanic arc granitoid Tectonically. The fact that AlT value in marginal parts of amphiboles in the Satkatbong pluton is lower than other granitoids implies emplacement depth of the Satkatbong pluton was relatively shallow. The Satkatbong pluton shows different geochemical feature compared to the adjacent adakitic Yeongdeok granite. This seems to be caused by mafic mantle material expected from the occurrence of MMEs.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.239-248
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• 2016

The habitat, age and spawning characteristics of the Korean eastern spined loach, Iksookimia yongdokensis, were investigated to obtain baseline data for its ecological characteristics in the Chuksancheon (stream), Yeongdeok-gun, Gyeongsangbuk-do, Korea. The difference between the habitats of juveniles (0+) and 1~4 year old loaches was that juveniles mainly inhabited sandy bottoms (substratum particle size $0.6{\pm}1.44\;cm$) with very slow velocities of water current ($2.4{\pm}2.09\;cm/sec$) and low depths ($29.2{\pm}7.57\;cm$), whereas 1~4 year old loaches inhabited pebble and cobble bottoms (substratum particle size 5.5~6.1 cm) with relatively fast velocities of water current (3.8~4.6 cm/sec) and deep depths (50~70 cm). The age groups for I. yongdokensis (female) estimated by the frequency distribution of total length in the spawning season (July) indicated that the 35~64 mm is 1-year old, the 65~94 mm group is 2-year old, the 95~119 mm is 3-year old, and the 120~145 mm is more than 4-year old. The sex ratio (♂/♀) was 0.69, and females were 10~30 mm larger than males. The lamina circularis at the base of the pectoral fins in males, a secondary sexual characteristic, formed at the 13th month after hatching. The spawning season according to the gonadosomatic index (GSI) was June to July with water temperatures of $20{\sim}25^{\circ}C$. The average number of eggs was $2,292{\pm}618$, with a diameter of $1.46{\pm}0.02\;mm$ for mature eggs.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.479-486
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• 2010

We analyzed the relationships between the daily yield and quality of pine-mushroom to predict the annual production pattern and unit price of the mushroom with the records of pine-mushroom trade at Yeongdeok forestry cooperative's market for nine years (2000~2008). Although there were some exceptions due to extreme drought or extraordinary temperature, the production ratio of high quality (first and second grade) was more than 50% in early stage and decreased, while that of low quality (pileus opened and defected ones) showed increasing pattern after the production reached in peak. The ratio of high quality and that of low quality were reversed 1~9 days before the mushroom production reached the acme of daily yield, which allowed us to predict that the mushroom production would be decreased when the ratio of low quality overcomes that of high quality. The ratio of high quality preceded about 3~4 days prior to that of daily yield, and the mushroom yield showed significant correlations with the ratio of high quality mushroom prior to 3~4 days of the day with the coefficient larger than 0.5 (r=0.51 for 3 days and r=0.54 for 4 days). Thus, we concluded that the analysis of grade distribution of pine-mushroom at the market may provide a significant clue to predict production pattern of the mushroom. In addition, the price of high quality pine-mushroom showed clear negative correlations with the yield. Thus, the analysis may take a good role for the trading of pine-mushroom with providing information for predicting the price of pine-mushroom.

• Korean Journal of Heritage: History & Science
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• v.44 no.1
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• pp.122-137
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• 2011

The purpose of this study was to present the characteristics of tree growth and the status of the ecosystem in Yeongdeok Docheon-ri Docheon forest, which was designated as Natural Monument No. 514. Results showed that most of the soil properties were generally within desirable levels except for some properties. The forest was composed of 503 trees. Major trees included Zelkova serrata, Celtis sinensis, Cornus walteri, Diospyros lotus, Hemiptelea davidii, and Evodia daniellii. In particular, trees such as Zelkova serrata, Celtis sinensis, and Cornus walteri showed D.B.H ranging from 10cm to 70cm. These trees appeared to be major tree species since the beginning of Docheon forest's existence. The wild birds observed from the site were from 18 families, 20 species, and 95 individuals. Also were found 1 mammal species, 1 reptile species, and 1 amphibian species. A dead Aix galericulata (designated Natural Monument No. 327) was found in the forest. The annual tree diameter growth of the sample trees was 2.3mm per year on average. The average age of the overstory trees was approximately 101 years, and the oldest tree was estimated to be 300~400 years old.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.165-175
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• 2006

To analyze the deformation and failure of slopes, generally, two types of model, Polynomial model and Growth model, are applied. These two models are focused on the behavior of the slope by time. Therefore, this research is more focused on predicting of slope failure than analyzing the slope behavior by time. Generally, Growth model is used to analyze the soil slope, to the contrary, Polynomial model is used for rock slope. However, 3-degree polynomial($y=ax^3+bx^2+cx+d$) is suggested to combine two models in this research. The main trait of this model is having an asymptote. The fields to adopt this model are Gosujae Danyang(soil slope) and Youngduk slope(rock slope), which are the cut-slope near national road. Data from Gosujae are shown the failure traits of soil slope, to the contrary, those of Youngduk slope are shown the traits of rock slope. From the real-time monitoring data of the slope, 3-degree polynomial is proved as excellent system to analyze the failure and behavior of slope. In case of Polynomial model, even if the order of polynomials is increased, the $R^2$ value and shape of the curve-fitted graph is almost the same.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.321-331
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• 2014

Patinopecten yessoensis is known to be farmed only in the northern part of the East Sea today. In an attempt to extend its production area, we have conducted experiments both in the northern and southern parts of the East Sea and studied on their growth in an aim to use the results for increasing overall productivity of the species. Early juvenile scallops producted in February 2014 showed an average shell length of $0.23{\pm}0.002$. The high growth group showed an average shell length and shell height of $4.11{\pm}0.08mm$ and $4.28{\pm}0.09mm$, respectively, in June while they were $23.63{\pm}3.4mm$ and $24.19{\pm}4.5mm$ in October. The low growth group showed an average shell length and shell height of $2.23{\pm}0.7mm$ and $1.99{\pm}0.9mm$, respectively, in June while they were $1.99{\pm}0.9mm$ and $17.59{\pm}4.5mm$ in October. The daily growth rate of the high growth group was 0.037 mm/day and 0.027 mm/day for the low growth group. In August, we measured the shell length of Patinopecten yessoensis from Yangyang-gun, Gangneung-si, Yeongdeok-gun, and Pohang-si. Patinopecten yessoensis from Pohang-si showed the best growth performance with its shell length of $26.90{\pm}3.6mm$. Patinopecten yessoensis from Yeongdeok was the second largest with its shell length of $23.56{\pm}3.4mm$. We presume that optimal water temperature and phytoplankton abundance of the two regions have contributed to the good growth performance of the species.