• Korean Journal of Ichthyology
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• v.6 no.2
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• pp.222-236
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• 1994

Sexual maturation and spawning of the spottybelly greenling, Hexagrammos agrammus were histologically studied under photomicroscopy by considering changes in gonadosomatic index, hepatosomatic index and fatness, egg diameter composition, first sexual maturity and fecundity. The fish samples were collected monthly at the coastal area of Tongbaeksom, Pusan, Korea from July 1991 to July 1992. The gonadosomatic index(GSI) increased in September and reached the maximum value(female 4.31, male 1.61) in November when the gonad was mature and ripe. The values were decreased suddenly during the spawning season from December, and declined from January to August. The annual variations of hepatosomatic index(HSI) appeared to be correlated with those of GSI in female but were not significantly correlated in male. HSI in female began to increase in autumn with the increase of GSI, and reached the maximum in winter when the ovary was mature. Percentages of first sexual maturity in female and male fish were 50 % in 11.0~11.9 cm and 100 % in 13.0~13.9 cm groups. Both sexes participated in reproduction from one year old. H. agrammus was considered as a polycyclic species and spawns 3 times or more in the spawning season. Number of total and mature eggs in the absolute fecundity were proportional to standard length and body weight, respectively. Number of total and mature eggs in relative fecundity were also proportional to standard length, but rather decrease with increasing of body weight. Fatness coefficients reached the maximum value(female 15.32, male 15.14) in September(growing stage), and the values were sharply decreased after spawning. Thereafter, fatness values were gradually increased, therefore, the monthly changes in fatness coefficient closely correlated with the reproductive cycle. Sex ratios of female and male sexes of this species are showed 54.18 %, 45.82 %, respectively.

• Journal of Life Science
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• v.19 no.12
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• pp.1851-1854
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• 2009

This study correlated changes in the plasma levels of estradiol-$17{\beta}$ (E2) with changes in the gonadosomatic index (GSI) and ovarian development during the annual reproductive cycle of the pike eel Muraenesox cinereus, collected at the Tongyung coast region. Ovarian maturity was classified based on histological observations; the perinucleolus stage (November to February), the oil droplet stage (March to April), the early vitellogenic stage (April to May) and the late vitellogenic stage (June to October). Seasonal changes in the GSI were correlated with water temperature and reflected the degree of ovarian maturity. Plasma E2 levels were correlated with changes in the GSI, which increased from April to a peak in July, and the levels remained comparatively high until October. These data indicated that changes in the GSI and plasma E2 levels are correlated with the annual ovarian activity of the pike eel. In this study, however, female pike eels were not collected during the spawning stage. Therefore, spawning of this species seemed to be closely related to its migration toward the deep sea of offshore.

• The Journal of Engineering Geology
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• v.33 no.2
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• pp.307-322
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• 2023

Rock-mass grouting plays a crucial role in the construction of dams and deep caverns, effectively preventing seepage in the foundations, enhancing stability, and mitigating hazards. Most rock grouting is affected by hydrogeological and rock engineering indices such as rock quality designation (RQD), rock mass quality (Q-value), geological strength index (GSI), joint spacing (Js), joint aperture (Ap), lugeon value (Lu), secondary permeability index (SPI), and coefficient of permeability (K). Therefore, accurate geological analysis of basic rock properties and guidelines for grouting construction are essential for ensuring safe and effective grouting design and construction. Such analysis has been applied in dam construction sites, with a particular focus on the geological characteristics of bedrock and the development of prediction methods for grout take. In South Korea, many studies have focused on grout injection materials and construction management techniques. However, there is a notable lack of research on the analysis of hydrogeological and rock engineering information for rock masses, which are essential for the development of appropriate rock grouting plans. This paper reviews the current state of research into the correlation between the grout take with important hydrogeological and rock engineering indices. Based on these findings, future directions for the development of rock grouting research in South Korea are discussed.

• Development and Reproduction
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• v.14 no.4
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• pp.225-231
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• 2010

Gonadal development and reproductive cycles of red sea urchin Pseudocentrotus depressus were investigated based on the monthly variations of gonadosomatic index (GSI), gametogenesis and developmental phases of gonad. The specimens were sampled monthly in the north coastal waters of Ongpo and the south coastal waters Bubhwan of Jeju Island, Korea, from December 1994 to December 1995. Monthly changes of GSI values and reproductive cycles showed similar trends in Ongpo and Bubhwan. In females GSI values were reached the maximum in December ($17.8{\pm}4.04$ in Ongpo, $13.8{\pm}1.51$ in Bubhwan). In males GSI values were reached the maximum in December ($15.4{\pm}1.53$ in Ongpo, $13.6{\pm}1.32$ in Bubhwan). In both Ongpo and Bubhwan major spawning probably occurred between November and February when water temperatures and daylengths decrease. The histological observations of the gonads suggested that this species seemed to have a synchronous gametogenesis and one spawning season a year in Jeju Island costal waters.

• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.179-186
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• 2011

Slime flounder, Microstomus achne is distributed in the coastal waters of Korea, west sea of Japan, BoHai, Yellow sea and East china sea. They are mainly caught by bottom trawl net during winter, from December to March. Sexual maturation of slime flounder were investigated using samples collected from commercial catch in the southern coast of Korea from November, 2006 to March, 2007. The ovary of the slime flounder is a conical bag in shape and is bilateral structure develops lengthily from the posterior of the abdomen to the end of the anal fin. The testis also is bilateral in structure, usually located in small size in the abdomen. In females, the gonadosomatic index (GSI) were peaked in January (12.46), then decreased rapidly thereafter. Female GSI values plummeted to 2.72 in March just after spawning. Male GSI values were peaked in December (2.46) before in the spawning season, then decreased slowly thereafter. The reproductive cycle would be classified into three successive developmental stages : maturation stage (November to January), ripe and spawning stage (December to February), degenerative and resting stage (February to March). Relationships between the fish sizes in total length (TL) and the number of ovarian eggs (F), the body weights (BW) and the number of ovarian eggs were indicated by the exponential equation respectively: F=29.027TL-767.8 (r$^2$=0.7686), F=0.3998BW+24.288 (r$^2$=0.8919).

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.87-93
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• 2008

To assess effects of contaminants on fish in Nakdong river, feral yellowfin goby Acanthogobius flavimanus were caugt in two different sites and its hepatic monooxygenase enzyme, including cytochrome P450 (CYP), NADPH-cytochrome P450 reductase (P450R), NADH-cytochrome b5 reductase (b5R), ethoxyresorufin deethylase (EROD), glutathione S-transferase (GST) were quantitatively determined. Gonadosomatic index (GSI), hepatosomatic index (HSI) and three sex steroid hormone (17$\beta$-estradiol, E2; testosterone, T; 11-ketotestosterone, 11-KT) levels of the fish were also investigated. HSI of fish from polluted site (site 1) were significantly higher than that of unpolluted site (site 2), but GSI levels were significantly lower in polluted site. No significant differences in plasma 11-KT and T levels were observed in two sites surveyed. E2 level was, however, significantly (p<0.05) higher in female fish from site 1 than site 2. In addition, hepatic EROD activity and CYP level of site 1 fish were lower than those of site 2 fish, whereas relatively high levels of P450R, b5R and GST activities were found in site 1. The results imply that yellowfin goby, especially female fish in Nakdong river estuary are affected from contaminants disrupting sex steroid hormone system.

• Korean Journal of Ichthyology
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• v.31 no.3
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• pp.141-149
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• 2019

This study presents data on spawning season, weight-length relationships (WLRs) and condition factor of Gadus chalcogrammus inhabiting the middle East Sea, Korea. Monthly changes in the gonadosomatic index (GSI) revealed that the spawning period was from December to March. Overall value of the exponent b, estimated by nonlinear least squares from weight and length data was 2.806, ranging from 2.778 for female fishes to 2.985 for immature group. The b values were similar between spawning and non-spawning, and between female and male fishes, but it was significantly higher for immature than mature fishes. The condition factors were significantly higher for immature than mature groups, and during non-spawning than spawning periods, but it was not significant between male and female fishes.

• Journal of Aquaculture
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• v.17 no.2
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• pp.128-132
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• 2004

Reproductive cycle of the brown sole, Limanda herzensteini was investigated by means of histological methods. The testis showed the presence of seminiferous tubule. The tubule consisted of many testicular cysts, each of which contained numerous germ cells - all at the same developmental stage. The ovary consisted of several ovarian lamellae and the oogonia originated from the inner surface of the ovarian lamella. Oocyte development was group-synchronous. Gonadosomatic index (GSI) of the male and female was the highest in January and March, respectively. Reproductive cycle could be classified into the growing (June-September), maturation (October-December), ripe and spent (January-March), and recovery and resting (April-May).

• Korean Journal of Ichthyology
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• v.27 no.4
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• pp.263-274
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• 2015

Change in morphological and biological characteristics of Japanese eel, Anguilla japonica, by maturation were determined by examination of 182 individuals collected in Korea waters from September to December 2014. Eels were classified into four stages based on the silvering index. The proportion of silver eels collected from streams and estuaries (34.6%) was higher than that from the freshwater reservoirs (3.8%). The sex ratio between female and male was 1:0.11 (n=182). Mean total length and weight were positively related to the silvering process. The ratios of head and pectoral lengths to total length and the ratio of horizontal and vertical orbital diameters to head length were significantly different between the maturation stages. However the ratio of pre-dorsal and pre-anal lengths to total length were not significantly different between the maturation stages. The gonado-somatic index was the single character that could identify the whole four stages among the indices examined: gonado-somatic index (GSI), condition factor (K), gut index (GI) and eye index (EI) but hepato-somatic index (HSI). One pseudo-silver eel collected. looked like a late silver eel in the S2 stage according to its external body color and morphology, but most of other characteristics suggested that it might be in Y1 (yellow eel) or Y2 stage (late yellow eel).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.199-209
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• 2000

Recently, GSIS is introduced in the various fields. Especially in hydrology, the useful of GSIS is emphasized to analyze parameters, which are necessary for the analysis of watershed. In this paper, to estimate the direct runoff volume, I used the SCS-CN method which was useful to calculate direct runoff volume in a watershed that was not observed. But because SCS-CN method must treat a great number of spatial data, if we use the GSIS, we can treat numbers of the data easily. GSIS databases is constructed by using the data which is related to soil type, landuse. And runoff curve number was estimated by means of these databases in the study area. Also, the area of covered each subbasin rainfall gauge station was estimated by thiessen polygon network technique. The direct runoff volume was calculated by these subbasin area to the rainfall gauge station. I knew, from this study, that using GSIS, I can calculate parameters needed in direct runoff volume analysis, fast, exactly.