• Ocean and Polar Research
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• v.33 no.spc3
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• pp.349-358
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• 2011

In order to ascertain latitudinal variation of lipid contents and compositions in copepods, we collected warm water copepod species (Euchaeta sp. and Pleuromamma spp.) from four different regions from low (sub-tropical) to mid (temperate) latitudes in the Northwest Pacific Ocean. Total lipid contents of Pleuromamma spp. were about 11 $ug{\cdot}ind^{-1}$ with little latitudinal variation, whereas Euchaeta sp. showed slightly higher lipid content (20 $ug{\cdot}ind^{-1}$) than Pleuromamma spp. with latitudinal gradient (low at subtropic and high at temperate). Wax esters, known as the major storage lipid classes, were found to be the dominant lipid classes (accounting for more than 35% of total lipids) in Euchaeta sp., whereas in Pleuromamma spp., phospholipids, known as cellular membrane components, were the dominant lipid classes. However, the exception was specimens from warm pool region exhibiting dominance in storage of lipids as a form of triacylglycerols. Among fatty acids, polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA : 22:6(n-3)) (about 35% of total fatty acids), were most abundant in Euchaeta sp., while saturated fatty acids (SAFA), specially hexadecanoic acid (16:0) (about 30% of total fatty acids), were most abundant in Pleuromamma spp.. Among the neutral fraction of lipids, phytol, originated from the side chain of chlorophyll, was found in all samples which generally indicate active copepods feeding on algae. While only trace amounts of short-chain fatty alcohols were found in Pleuromamma spp., significant amounts of fatty alcohols were found in Euchaeta sp.. Particularly, significant amounts of long chain monounsaturated fatty alcohols (20:1 and 22:1), generally found in cold water species, were found in Euchaeta sp. from low latitudes. The latitudinal variation of trophic lipid markers in these copepods could be significantly related with in-situ food availability and species-specific diet preference. The result of this study suggests that the lipid contents and compositions in copepods may not only indicate their nutritional condition and feeding ecology but also provide insight into species-specific living strategies under different environmental conditions (i.e. water temperature, food availability).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.135-144
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• 1980

The reproductive cycle and the breeding season of the freshwater clam, Anodonta (Sinanodonta) woodiana (Lea) have been investigated by histological examination of the gonadal development under photomicroscopy. The materials were monthly collected from the Nakdong River for one year from September 1979 to August 1980. Sexuality of Anodonta (Sinanodonta) woodiana is dioecious, and the species are ovoviviparous. The gonads are irregularly arranged from the subregion of mid-intestinal gland in visceral cavity to reticular connective tissue of foot. The ovary is composed of a number of small ovarian sacs, The epithelium of ovarian sac has a function of the germinal epithelium. Oogonia actively proliferate along the germinal epithelium of the ovarian sac, in which young oocytes are growing. The testis is composed of a number of seminiferous tubules, and the epithelium of the tubule has function of germinal epithelium, along which spermatogonia actively proliferate. A great number of undifferentiated mesenchymal tissue and eosinophilic granular cells are abundantly distributed between the growing oocytes and spermatocytes in the early development stages. With the further development of the ovary and testis these tissues and cells gradually disappear. Then the undifferentiated mesenchymal tissue and granular cells are considered to be related to the growing of the oocytes and spermatocytes. The gonads had function year-round the individuals which have various developmental stages of gonads appearing all the time. Spawning continued year-round except for the period of high temperature of water, during August and September. The peak spawning seasons appeared twice a year between January and March, and between June and July in 1980. Individuals which have trochophore larvae in the marsupium of the adult appeared year-round except September 1579 and August 1980. The rate of individuals which have glochidia in the marsupium was 72.7 percent in May 1980 which was the highest brooding fate.

• Journal of Radiation Protection and Research
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• v.21 no.1
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• pp.1-7
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• 1996

In this paper, we discussed the fabrication and characterization of bulk type CdZnTe detector for pocket surveymeter. The resistivity of CdZnTe single crystal grown by the High Pressure Bridgman method is in the mid of $10^9$ ohm-cm. The detector structure is Au/CdZnTe/Au and gold electrode is formed by electroless deposition method. Resolutions of 4.8keV and 2.2keV were observed at 22.2keV line of $^{109}Cd$ and 59.6keV line of $^{241}Am$ at room temperature, respectively. We also constructed the small size pocket surveymeter using home made CdZnTe detector. It shows the good linearity over a range from 1mR/hr to 10R/hr with deviation less than 5%. The sensitivity of the surveymeter developed is $2.2{\times}10^3 cps/Rad\;hr^{-1}$ for the 662keV of $^{l37}Cs\;{\gamma}-ray$.

• Journal of Mushroom
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• v.18 no.3
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• pp.179-188
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• 2020

The oak mushroom (Lentinula edodes) is a popular edible mushroom that has long been cultivated and eaten throughout Northeast Asia (including Korea). Its taste and flavor are unique. Oak mushrooms are cultivated on logs and in sawdust. The cultivation period on logs is 4-5 years, while the cultivation period in sawdust is 6 months, which is rapidly driving a shift from log to sawdust based cultivation. In particular, the Sanjo 701ho cultivar of L. edodes is a mid-range to high-temperature variety that is widely known for its suitability for summer cultivation on sawdust in Korea. This study summarizes new developments and achievements in the oak mushroom industry in Korea, and details the cultivation history of Sanjo 701ho, its culturing characteristics, various demonstration tests, and the expansion of domestic varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.427-435
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• 1984

Alfalfa field was established to investigate seasonal changes of nodule activity and contents of carbohydrates, and nitrogen, and also to examine their relationships in alfalfa (Medicago sativa L.). Periodical sampling of alfalfa in cutting and uncutting plots was collected to measure growth of plants, development and activity of nodule, and content of carbohydrates and nitrogen in the third year following year of establishment. Nodule activity of alfalfa root appeared to early April, increased to a maximum in beginning of June (flowering stage), and then decreased and generally remained low from late-July to mid-August, and again increased from early September, and then decreased and generally remained low for the rest of growing season. After flowering, nodule weight tended to decrease slowly throughout the growing season. Until flowering stage, increase of dry weight was closely related with that of nodule activity. But after flowering the curve pattern of dry weight did not fit to that of nodule activity due to decrease of supply of assimilate to nodule, drought, and high temperature. Total nonstructural carbohydrates in roots were closely correlated with nodule weight and nodule activity. While, nitrogen contents in leaves were closely correlated with nodule weight and nodule activity. Also cutting on July prevented unnessesary losses of respiration during summer to provide rapid recovery of nodule activity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.1
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• pp.27-32
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• 1970

A study on the purification of the surf clam Mactra Sulcataria REEVE for the remove of sand and fecal piles was conducted in the laboratory. The sand was mostly distributed around the inhalent and exhalent siphon, mantle and gill, and were also distributed in the digestive tract including the mid-gut gland. The sand particles in the digestive tract were extremely small and their sizes were about $180\times10\mu\;to\;550\times200\mu$. It could be seen that there was little, if any, difference in the rate of sand removal when either the hanging Purification method was used or the method of laying the surf clams in thick or thin layers on the bottom of the experimental vessel was used. The surf clam removed about $50\%$ of its sand during the first hour of purification. The weight of the removed sand and fecal piles on a dry basis reached a constant value after 22 to 26 hours of purification. After 42 hours of Purification, no sand could be seen in the fecal piles. The surf clam removed the sand in its body more rapidly when it was in sea water with the pH of 8.75 than when it was in natural sea water. Also high temperature had a much greater depressing effect upon the removal of sand In the surf clam than did natural sea water. Also low salinity had greater accelerating effect upon the removal of sand in the body than did natural sea water. However the surf clam died when the salinity was $8.19\%_{\circ}$.

• Journal of the Korean Geographical Society
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• v.42 no.6
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• pp.863-878
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• 2007

The time-spatial distribution of Scrub typhus and its relationship with environmental ecology, such as climate, and habitat change are analyzed in respect of the geography of disease. Scrub typhus was firstly reported in 1951, and reemerged in 1986 mainly in southwestern Korea. later it has sharply increased and spreaded out toward whole country in 1998 and 2004, except mid-eastern mountainous region. Hwasung City is the typical example of sudden upsurge of Scrub typhus. High incidence of Scrub typhus patients might due to elevated temperature and decreased precipitation during the summer, as well as milder autumn. Sharp increase of Scrub typhus patients at rural area since 1980's might also be the result of the rapid changes of land use pattern, which eventually have contributed for the active development of dense vegetation and propagation of chigger mites around cultivated land.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.297-306
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• 2023

Saemangeum Lake is the largest artificial lake in Korea. The continuous deterioration of lake water quality necessitates the introduction of novel water quality management strategies. Therefore, this study aims to identify the spatiotemporal water quality characteristics of Saemangeum Lake using data from the National Water Quality Measurement Network and provide basic information for water quality management. In the water quality parameters of Saemangeum Lake, water temperature and total phosphorous content were correlated, and salt, total nitrogen content, pH, and chemical oxygen demand were significantly correlated. Other parameters showed a low correlation. The spatial principal component analysis of Saemangeum Lake showed the characteristics of its four zones. The mid-to-downstream section of the river affected by freshwater inflow showed a high nutrient salt concentration, and the deep-water section of the drainage gate and the lake affected by seawater showed a high salt concentration. Two types of water qualities were observed in the intermediate water area where river water and outer sea water were mixed: waters with relatively low salt and high chemical oxygen demand, and waters with relatively low salt and high pH concentration. In the principal component analysis by time, the water quality was divided into four groups based on the observation month. Group I occurred during May and June in late spring and early summer, Group II was in early spring (March-April) and late autumn (November-December), Group III was in winter (January-February), and Group IV was in summer (July-October) during high temperatures. The water quality characteristics of Saemangeum Lake were found to be affected by the inflow of the upper Mangyeong and Dongjin rivers, and the seawater through the Garuk and Shinshi gates installed in the Saemangeum Embankment. In order to achieve the target water quality of Saemangeum Lake, it is necessary to establish water quality management measures for Saemangeum Lake along with pollution source management measures in the upper basin.

• Korean Journal of Microbiology
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• v.32 no.2
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• pp.155-162
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• 1994

Cells of Acinetobacter sp. strain JC1 DSM 3803, an aerobic monoxide-oxidizing bacterium, growing on glucose exhibited high catalase activity at the mid-exponential growth phase. The enzyme activity decreased gradually after then until the early stationary phase, increased again at the mid-stationary phase, and then decreased again thereafter. Cells growing on glucose was found to contain three kinds of catalses. Cat1, Cat2 and Cat3. The activities of Cat1 and Cat3 did change significantly during growth, but that of Cat2 exhibited significant variation. Cat3 was found to present only in cells growing on glucose, but not in cells growing on carbon monoxide of methanol. The activities of call and Cat3 in cell-free extracts were stable upon treatment with ethanol and chloroform, but decreased to some extent when the enzymewere treated with 2mM $H_2O_2$ and/or 3-amino-1,2,4-triazole (AT). Cat2 was found to be extremely sensitive to the ethanol-chloroform and $H_2O_2$ treatments, but was insensitive to the AT treatment. Cat1 exhibited enzyme activity after incubation for 1 min at 80$^{\circ}C$. Cat2 and Cat3 did not show enzyme activity after incubation for 1 min at 60$^{\circ}C$ and 70$^{\circ}C$, respectively. Cat2 was found to have peroxidase activity. Cat3 was purified to homogenity in seven steps. The molecular weight of the native enzyme was estimated to be 150,000. Sodium dodecyl sulfate-gel electrophoresis revealed two identical subunits of molecular weight 65,000. The enzyme was found to show two $K_m$ values of 39 mM and 58mM. The optimal pH for the enzyme activity was 7.0, but the activities at pH 6.0, 8.0, and 9.0, were found to be comparable to that at the optimal pH. The optimal temperature for the enzyme activity was found to be 40$^{\circ}C$. The enzyme also exhibited strong activity at 20$^{\circ}C$, 30$^{\circ}C$, and 50$^{\circ}C$. The purified enzyme was not affected by the ethanol-chloroform treatment. The enzyme, howerver, showed less than 10% of the original activity when it was treated with 12 mN AT, 0.1 mM $NaN_3$ of 1mM KCN.

• Journal of Sericultural and Entomological Science
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• v.22 no.1
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• pp.7-25
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• 1980

Some substances and freezing tolerance in the mulberry (Morus species) branch have been studied on the basis of varietal differences and harvesting times along with harvesting methods in autumn. The results obtained are summarized as follows; 1. The highest freezing tolerance was shown in the varieties of Yongcheon-chou, Jasan, Kang-weon No. 3 and Ichihei, the medium in Roso. Kairyonezumigaeshi, Yanagida and Kokuso No. 28, and the lowest in Ichinose, Mokuso, Kokuso No. 21 and Suweousang No. 3. 2. There was a signifiant negative correlation (r= -0.59＊) between death atop percentage in the field and the temperature required to kill 50% of the mulberry buds (T$_{50}$) with the harvesting times and methods in autumn. Cold hardening occurred in the early through the end of September with the peak at the mid-september. During this period, leaf harvest decreased freezing tolerance with remarkable decrease due to picking all the leaves and leaving several leaves at the base of branch. Greater cold hardening was induced by leaving several leaves after topping. 3. Negative correlations were observed between freezing tolerance and the contents of soluble (r =-0.70＊) and crude (r= -0.70＊) protein. However, positive correlations were shown between freezing tolerance and total carbohydrate contents per crude (r=0.31＊) and per soluble (r=0.71＊) protein . There were also positive correlations between freezing tolerance and total sugar (r=0.67＊) and RNA content (r=0.99＊＊). No relationships of dry matter. fat. total carbohydrate and DNA contents were observed to the freezing tolerance. 4. Such sugars as raffinose. lactose, sucrose, glucose, fructose. arabinose. xylose. ribose (assumed) and rhamnose were detected in winter mulberry branch. Major sugars such as sucrose, glucose, and fructose were supposed to have higher relationship to the freezing tolerance than the other sugars. 5. Late harvesting increased RNA content except in the case of total leaf picking at mid-September. Leaf picking decreased RNA content. Some amount of RNA was, however, maintained by leaving several leaves after topping Leaving upper-middle leaves of a branch showed high RNA content. Leaving young leaves at the top and the overmatured leaves at the base showed low content. A positive correlation (r=0.51＊) was noted between RNA content and freezing tolerance in the different harvesting methods.s.