• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.6
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• pp.773-778
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• 2007

This study was performed to develop a more simple and convenient heat treatment process for increasing heating temperature than the traditional 9-times steaming process for Rehmanniae radix Preparata (R. radix P.). The R. radix was heated to various temperatures (110, 120, 130, 140 and $150^{\circ}C$) for different lengths of time (1, 2, 3, 4 and 5 hr). Chromaticity, free sugar, amino acid, catalpol and 5-HMF (5-hydroxy-methyl-2-furaldehyde) content of water extracts of R. radix P. were analysed. With increasing heating temperature and time, the L, a and b-value of samples gradually decreased. Fructose and glucose contents were increased to $120^{\circ}C$ for 5 hr (5.21 and 6.67%, respectively) with no changes afterward. Sucrose content was not detected after $130^{\circ}C$. Total amino acid was increased to $140^{\circ}C$ and decreased afterward. The maximum total amino acid content was 4,172 mg/100 g at $140^{\circ}C$ for 2 hr (R. radix L.: 3,029 mg/100 g). The catalpol was decreased to $130^{\circ}C$ for 1 hr and not detected afterward. The 5-HMF content increased with increasing heating temperature and time. The maximum content of 5.HMF was 2.5% in $150^{\circ}C$ for 5 hr. Hence, it can be suggested that the heat treatment at $130^{\circ}C$ for 2 hr or more is the most optimum processing conditions, instead of the traditional 9.times steaming process.

• Applied Biological Chemistry
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• v.24 no.1
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• pp.50-58
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• 1981

The influence of high temperature storage on the chemical composition and color intensity of the concentrated red ginseng extract(RGE) was investigated. The concentrated RGE was prepared by extraction of red ginseng tails with water and concentrated under reduced pressure. Changes in free sugars, saponin patterns and brown color intensity were measured during 96 hours of heat treatment at various temperature. A decrease in the contents of glucose, fructose and sucrose was resulted as the brown color intensity increased during the storage. The sugar contents and color intensity showed rapid initial change followed by slowing down at higher temperature. A significant relationship was found between sugar content and browning rate. The saponin pattern measured by high performance liquid chromatography, particularly in the region of protopanaxtriol, was also affected significantly. The peak heights of ginsenoside -Re and $-Rg_1$ were decreased while those of ginsenoside $-Rg_2$ and -Rh group were increased.

• Journal of Life Science
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• v.18 no.1
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• pp.63-68
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• 2008

This study was carried out to investigate the effect of the addition of pine needle juice and mugwort juice on the color, hardness, pH, VBN content, TBARS value and total plate count of beef jerky during storage at room temperature for 60 days. Beef jerky was prepared by three types such as beef jerky containing 50 ml water (control), beef jerky containing 50 ml pine needle juice (PBJ) and beef jerky containing 50 ml mugwort juice (MBJ). The L (lightness) value of the control and PBJ was not significantly changed during storage, but the $L^*$ value of MBJ tended to increase during storage (p<0.05). The $a^*$ (redness) value had the highest at the 60 day storage, and the $a^*$ value of PBJ and MBJ were higher than that of the control (p<0.05). The $b^*$ (yellowness) had the highest at the 60 day storage (p<0.05), and the $b^*$ value was not significantly different among samples. The addition of pine needle juice and mugwort juice had no effect on the changes of color of beef jerky. The hardness tended to increase during storage period, the hardness of the control was higher than those of PBJ and MBJ until storage for 30 days (p<0.05). The pH of samples tended to decrease during storage period (p<0.05). The VBN content of samples tended to increase during storage period, and the VBN content of the control was higher than those PBJ and MBJ on the storage of 60 days (p<0.05). The TBARS value of samples tended to decrease during storage period, and the TBARS value of MBJ had the lowest during storage period (p<0.05). The total plate count tended to decrease during storage period (p<0.05), and the total plate count of control, PBJ and MBJ were 4.93, 4.11 and 4.17 log CFU/g, respectively.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.201-210
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• 2007

In this study, physical properties of Elk antler was investigated to develop the optimum drying and packaging methods for improving the antler quality as well as deal with diversify of demand. After the antler was sliced with 5 mm thickness, and the compressive, shear, and tensile stresses were measured at the center and velvet parts of pre-dried and dried antlers after the contained water rate of the dried antlers was maintained below 10%. The results are as follows. 1. Considering the center of pre-dried antlers, the compressive stresses were $60.73\;g/mm^2$, $145.65\;g/mm^2$, and $260.97\;g/mm^2$, respectively at the upper, middle, and lower parts while $70.67\;g/mm^2$, $811.90\;g/mm^2$, $3,235.52\;g/mm^2$, respectively for velvet layer. Considering the center of dried antlers, the compressive stresses were $190.43\;g/mm^2$, $445.81\;g/mm^2$, and $705.86\;g/mm^2$, respectively at the upper, middle, and lower parts while $734.01\;g/mm^2$, $1,238.40\;g/mm^2$, $4,134.03\;g/mm^2$, respectively for velvet layer. 2. For the pre-dried, the shear stresses were $50.24\;g/mm^2$, $294.44\;g/mm^2$, and $423.47\;g/mm^2$, respectively, and $124.14\;g/mm^2$, $367.69\;g/mm^2$, and $425.86\;g/mm^2$, respectively for the dried antlers. 3. The tensile stresses were $13.59\;g/mm^2$, $62.85\;g/mm^2$, and $112.07\;g/mm^2$, respectively for the pre-dried and $77.24\;g/mm^2$, $175.87\;g/mm^2$, and $184.06\;g/mm^2$, respectively for the dried antlers. 4. In the case of drying antlers, the physical characteristics of the antlers was. changed such as moisture evaporation, contraction, and surface hardening. For the center part, the changes of the physical characteristics were more significant at the lower part while at the upper part for the velvet layer. 5. The stress changes of Elk antlers was shown very remarkably according to growth point. Moreover, the stress was clearly higher at velvet layer part to the center part, base parts compared to the upper parts.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.109-122
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• 2022

Currently, most of the pig manure generated from pig farms in Korea is in the form of a slurry with a moisture content of about 97%. Pig manure slurry is a mixture of pig manure and cleaning water in the pig house. In this study, changes in properties of pig manure liquid fertilizer according to whether air was supplied or not and with the passage of storage period were analyzed for 120 days. During the experimental period, the degree of maturity of the pig manure liquid fertilizer was higher in the experimental closed batch reactors supplied with air than in the same type reactors not supplied with air. As the liquid fertilizer storage period elapsed, there was a tendency that liquid fertilizer was converted to a state of complete maturity. In the batch reactor in which air was supplied, the moisture content of pig manure slurry, which had a moisture content of 97.90%, was reduced to 96.82% at the end of the experiment. On the other hand, the moisture content in the reactor without air was reduced to 97.33%. The pH of the liquid fertilizer, which was 8.82 at the start of the experiment, changed to 7.57 in the reactor with air supplied and 8.75 in the reactor without air at the completion of the experiment. The nitrogen content in the liquid fertilizer was 0.198 mg/L on average at the start of the experiment and it was lowered to 0.076 mg/L in the air supplied reactor at the end of the experiment. On the other hand, the nitrogen content of the liquid fertilizer was lowered to 0.121 mg/L in the reactor to which air was not supplied. The phosphoric acid (P₂O₅) concentration in the liquid decreased higher in the liquid fertilizer filled in the reactor without air than the liquid fertilizer filled in the reactor with air supplied as the storage period elapsed. Considering the experimental results, it is considered that the quality of pig manure liquid fertilizer is improved when air is supplied to pig manure slurry and the storage period of pig manure slurry is longer.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.283-296
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• 2014

The distribution of heavy metals in the stormwater runoffs from industrial sites around Shihwa Lake that implements the total pollutant load management system (TPLMS) was studied to characterize the temporal changes of metal concentrations and to assess the ecological risk in dissolved and particulate phases of the selected metals. The dissolved Co and Ni concentration demonstrated first flush and tended to decrease with increasing of the duration of rainfall. The intensity of precipitation was found to be the main controlling factor of particulate metals in the stromwater runoffs. The particulate concentration of Pb accounted for 97.2% so the particulate phase was its main form. Other metals followed the sequence: Pb>Cu>Cd>Co>Zn>Ni. The particulate-dissolved partitioning coefficient ($K_d$) indicated that the $K_d$ of Pb were bigger than that of other metals because the metal Pb in the stormwater runoffs is quickly removed into the particulate phase. In a single day rainfall event, total runoff fluxes for total metals as the sum of dissolved and particulate forms through only two sewer outlets were 2.21 kg for Co, 30.5 kg for Ni, 278.3 kg for Cu, 398.3 kg for Zn, 0.39 kg for Cd and 40.0 kg for Pb, respectively. Given the annual rainfall, the number of rain days and the basin area for total pollutant load management system (TPLMS) of Shihwa area, enormous amount of non-point metal pollutants were entered into Lake with any treatment. The dissolved metals (e.g., Ni, Cu and Zn) in the stormwater runoffs exceeded the acute water quality criteria. Additionally, all metals were significantly enriched in the particulate phase and exceeded the PEL criteria of sediment quality guidelines (SQGs). These results indicated that the heavy metals in the stormwater runoffs may pose a very high ecological risk to the coastal environments and ecosystem.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.448-455
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• 2004

Changes in quality characteristics of Bijijang (fermented soybean curd residus) prepared at $35^{\circ}C\;and\;40^{\circ}C$ for 0, 12, 24, 36, and 48 hr were investigated. Acidity of Bijijang increased, whereas pH and Hunter's color values decreased during fermentation. Immediately after Bijijang preparation, ${\alpha}-and\;{\beta}-amylase$ activities were very low, ${\beta}-Amylase$ activity during fermentation increased rapidly, with those fermented at $40^{\circ}C$ higher than at $35^{\circ}C$. Neutral pretense activity was significantly higher than acidic pretense activity, and increased gradually after 12 hr. Change in total nitrogen content in Bijijang was insignificant, whereas contents of amino-type and water-soluble nitrogens increased significantly during fermentation. Major free amino acids of Bijijang were Arg, Pro, Glu, Thr, Ser, and Lys at initial fermenting stage, and, as fermentation progressed, contents of Cys, Met Glu, Ile, Leu, and Phe increased. Reducing sugar contents of Bijijang fermented at $40^{\circ}C$ were higher than those fermented at $35^{\circ}C$. Sucrose content decreased and glucose content increased. Glucoside (genistin and daidzin) contents decreased and aglycone (genistein and daidzein) contents increased during preparation of Biji and fermentation of Bijijang. Contents of free sugars and isoflavones were higher in Bijijang fermented at $40^{\circ}C$ than at $35^{\circ}C$. Based on these results, fermentation at $40^{\circ}C$ for 48 hr was determined to be optimum fermentation condition for Bijijang.

• Journal of Dairy Science and Biotechnology
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• v.27 no.2
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• pp.7-16
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• 2009

Appenzeller cheese samples were prepared by addition of 0.5, 1.0, and 2.0% green tea (Camellia sinensis, CS) powder and control cheese. We examined various quality characteristics of the novel cheese, such as viable-cell counts, pH, water-soluble nitrogen (WSN), non-casein nitrogen (NCN), non-protein nitrogen (NPN), and catechin level during maturation for 16 weeks at $14^{\circ}C$. To develop a Korean natural cheese containing green tea powder, we also analyzed the changes in the polyacrylamide gel electrophoresis pattern, chemical composition, and sensory qualities. The viable cell counts of the samples were not significantly different. Until the $3^{rd}$ week, the pH of the CS cheese decreased with an increase in the maturation time. However, the pH gradually increased by the $12^{th}$ week, while WSN, NCN, NPN also increased. The WSN, NCN, NPN, and catechin values for the CS cheese samples were significantly higher than the values for the control cheese. The polyacrylamide gel electrophoretic pattern of caseins for the CS cheese indicated that this cheese degraded more rapidly than the control cheese did. In the sensory evaluation, cheese with 1.0% CS powder showed the highest scores in taste and appearance and good scores in flavor and texture. These results indicate that 1.0% CS is the optimal value for addition to cheese, and cheese containing 1.0% CS shows good physiological properties and reasonably high overall sensory acceptability.

• Korean journal of food and cookery science
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• v.30 no.4
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• pp.402-411
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• 2014

This study investigated the quality characteristics of tea leaf pickle with different pickling solutions. Blanched tea leaf at $100^{\circ}C$ for 3 min was pickled using pickling solutions (mixture of water, soy sauce, sugar and vinegar) with different vinegar contents (10, 20, 30 and 40%, v/v). and stored for 30 days at $4^{\circ}C$. The color values, hardness, pH, total acidity, sensory evaluation, antioxidant compound contents, DPPH radical scavenging and ABTS radical scavenging of the pickled tea leaf during storage were determined. The pH of tea leaf pickles decreased consistently and total acidity was increased during storage. The L-value of tea leaf pickles was decreased and the a-value was increased significantly during storage; however, the b-value had no significant changes (p<0.05). The hardness of the tea leaf pickles decreased consistently during storage. On the sensory evaluation, the highest score of overall acceptance was presented to the tea leaf pickle using a 20% vinegar pickling solution stored for 20 days. The antioxidant compound contents and antioxidant activity consistently decreased during storage; further, the experimental group of vinegar with 20% content tea leaf pickle displayed the lowest antioxidant compound content and antioxidant activity.