• Journal of Aquaculture
• /
• v.13 no.4
• /
• pp.309-316
• /
• 2000

Feeding habits of A. luridus were studied by analyzing the stomach contents of monthly collected fish from the intertidal zone of Dodun-ri, Sochon from July 1996 to June 1997. Fullness of stomach increased twice a day, first in the morning and second in the afternoon. A. luridus (1.2-5.9 em in standard length) was a carnivore consuming mainly decapods (natantia larvae, Acetes japonicus, Penaeus japonicus and reptantia larvae), amphipods (caprellids, gammarids and hyperiids) and copepods (Acartia sp., Calanus sinicus, Corycaeus affinis, and Microsetella sp.). Its diets also included minor quantities of isopods, cirriped larvae, polychaete larvae and stomatopods. According to fish size, some changes in feeding habits were apparent, i.e. smaller fish preferred to prey in the following order : copepods < decapods < amphipods. However, as the size increased, decapods and amphipods were selected.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.29 no.4
• /
• pp.719-725
• /
• 2000

This study focused on the purification and characterization of ACE inhibitor from Porphyra yezoensis. The dried Porphyra yezoensis was ground and hydrolyzed with 2.5 N HCl, followed by neutralization and centrifugation. Then, the subsequential purification of ACE inhibitor was carried out by Amberlite XAD 8, DEAE-Toyopearl 650C, Sephadex LH-20 column chromatography and reverse phase HPLC with C18 column. The purified ACE inhibitor was peptide which consisted of glycine (24.5%), arginine (56.8%) and proline (18.8%). Also, it showed the competitive inhibition pattern to ACE. The apparent molecular mass of purified peptide was 580 dalton, and an IC50 value of ACE inhibitor was 10.6 $\mu\textrm{g}$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.14 no.4
• /
• pp.217-220
• /
• 1981

A trematode, Cercaria tapidis which is parasitic to short necked clam, Tapes philippinarum was studied in terms of its morphology and incidence of infection rate. The host bivalve was collected from Solri near Gunsan from September 1980 to August 1981. Sporocysts were observed mainly in tissues of gonad of the short necked clams. Minimum infection rate ($0.85\%$) was found in May, while maximum infection rate ($23.27\%$) in December. The sporocyst is 1.1 mm long and 0.27 mm wide. Ellipsoidal body of cercaria is $283{\mu}m$ long and $120{\mu}m$ wide. Oral sucker is much larger than ventral sucker. Moderately small pharynx, a long esophagus, and a long intestine reaching to the posterior end of the body are distinctive. Globular excretory bladder is located at the posterior part of the body and bears numerous granules of various size. The flame-cell arrangement is represented by a formula 2[(3+3+3)+(3+3)]=30. Tail is five times body length.

• Korean Journal of Weed Science
• /
• v.8 no.1
• /
• pp.1-8
• /
• 1988

In order to get basic information for establishing weed control methods, weed distribution was surveyed at 15 days interval in garlic and red pepper fields at 8 locations in Chungnam Province. In garlic fields, 68 weed species(27 families) were distributed. Portulaca oleracea, Chenopodium album and Digitana sanguinalis were most dominant and Equisetum arvense, Alopecurus aequalis, and Setaria viridis dominant among them. Highest number of weeds emerged in May and dry weight or weeds was more heavy in June and summer broadleaf weeds were most abundant throughout garlic growing period. In red pepper fields, 38 weed species(17 families) were distributed, D. sanguinalis, Cyperus amuricus and P. oleracea were most dominant and Echinochloa crus-galli, Eleusine indica, D. violascens, and Centipeda minima also dominant among them. The highest number of weeds were emerged in June and summer, grasses and summer broadleaf weeds were more abundant in June and July. Seasonal Shannon's diversity index(H'), maximum diversity(Hmax') and eveness(J') for the Shannon diversity index, and Simpson index were high in both red pepper and garlic fields. Interspecific competition(probability for interspecific encounter) was more severe than intraspecific competiton.

• Explosives and Blasting
• /
• v.41 no.3
• /
• pp.62-72
• /
• 2023

The aging of plant structures due to industrialization in the 1970s has increased the demand for blast demolition. While blasting can reduce exposure to environmental pollution by shortening the demolition period, improper blasting design and construction plans pose significant safety risks. Thus, it is vital to consider optimal blasting demolition conditions and other factors through collapse behavior simulation. This study utilizes a 3-D combined finite-discrete element method (FDEM) code-based 3-D DFPA to simulate the collapse of a chimney structure in a thermal power plant in Seocheon, South Korea. The collapse behavior from the numerical simulation is compared to the actual structure collapse, and the numerical simulation result presents good agreement with the actual building demolition. Additionally, various numerical simulations have been conducted on the chimney models to analyze the impact of the duct size in the pre-weakening area. The no-duct, duct, and double-area duct models were compared in terms of crack pattern and history of Z-axis displacement. The findings show that the elapse-time for demolition decreases as the area of the duct increases, causing collapse to occur quickly by increasing the load-bearing area.

• Journal of Wetlands Research
• /
• v.18 no.3
• /
• pp.301-312
• /
• 2016

This study has performed comparative analysis on characteristics of contaminated 35 tributaries on seasonal variation/point discharge load/pollutant distribution of water quality factors(8) in order to understand the effect of the watershed in Nakdong River Basin. As a results, the water quality of $BOD_5$(Biochemical Oxygen Demand), Chl-a(Chlorophyll a) and Fecal E. Coli shows II grade at tributaries of more than 50% without COD(Chemical Oxygen Demand), TP(Total Phosphate), TOC(Total Oxygen Carbon) and TN(Total Nitrogen) factors. The specific discharge(Q) were occupied about 54.4% (19 sites) as $0.05m^3/sec/km^2$ value. Among these results, the contaminant level of Dalseocheon, Hyeonjicheon, Seokkyocheon 1, Uriyeongcheon and Dasancheon was also high, which has to consider a discharged pollutant load(kg/day). The 35 major tributaries of Nakdong River were included in 7 mid-watershed, such as Nakdong Waegwan, Geumho River, Nakdong Goryung, Nakdong Changnyung, Nam River, Nakdong Milyang, Nakdong River Hagueon. Especially, the discharged pollutant load of Nam River and Geumho River also was high according to the amount of discharge such as Kachang dam, Gongsan dam and Nam river dam. Seasonal difference of the water quality factors such as $BOD_5$, TN, SS and Q was observed largely, on the other hand the TP and Chl-a was not. This is guessed due to the precipitation effect of site, biological and physicochemical degradation properties of pollutant and etc. The co-relationship between the seasonal difference and water quality factors was observed using a Pearson correlation coefficients. Besides, the Multiple Regression analysis using a Stepwise Regression method was conducted to understand the effect between seasonal difference and water quality factors/regression equations. As a result, the Multiple Regression analysis was adapted in the spring, summer and autumn without the winter, which was observed high at spring, summer and autumn in the order COD/TP, Chl-a/TOC, TOC/COD/$BOD_5$ water quality factors, respectively.

• Journal of agriculture & life science
• /
• v.46 no.6
• /
• pp.105-115
• /
• 2012

The detailed proximate, fatty/amino acid, mineral composition, texture, color, chemical and taste compounds of six oysters (four kinds of cultured oysters and two kinds of wild oysters) in Korea were investigated. Length and weight of the shell removed cultured and wild oysters were 4.7~5.1 and 3.0~4.2 cm, and 5.9~9.1 and 2.6~5.5 g, respectively. The proximate compositions were not significantly different between cultured and wild oysters. Amino nitrogen and volatile basic nitrogen content of these ones were 232.8~258.2 and 160.5~213.9 mg/100 g, 9.5~12.0 and 7.8~9.5 mg/100 g, respectively. As a texture characteristic of muscle, shearing force were 95~114 and 105~132 g. Amounts of total amino acids of cultured and wild oysters were 9,004~10,198 and 8,165~8,942 mg/100 g, respectively. Major amino acids and inorganic ions were aspartic acid, glutamic acid, proline, alanine, leucine, phenylalanine, lysine, arginine and K, Na, Ca, Fe, S, P, Zn. Major fatty acids of these ones were 16:0, 18:0, 16:1n-9, 18:1n-9, 22:1n-9, 16:4n-3, 20:5n-3 and 22:6n-3, and there was little difference between the two groups. Amounts of free amino acids of cultured and wild oysters extracts were 1,444~1,620 and 1,017~1,277 mg/100 g, respectively, and major ones were taurine, glutamic acid, glycine, alanine, tryptophan, ornithine and lysine. There is a little difference in glycine, tryptophan, ornithine and arginine contents, but TMAO and TMA contents were low in amount, and were not significantly different between the two groups.