• Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.318-335
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• 2023

It is important to understand the biological aspects of fish for fishing management. This study was conducted from February through October 2021. A total of 1,629 fishes were collected using different fishing gears. The length-weight relationship is a power curve for all fishes and showed a significant (r² > 0.8). All fishes revealed a negative allometric growth pattern except Labeobarbus intermedius. Oreochromis niloticus (1.714 ± 0.009) was found in better condition than other fish species (analysis of variance [ANOVA], p < 0.05). The length at maturity was 24.0 cm and 25.4 cm total length (TL), 28.9 cm and 28.2 cm fork length, and 53.2 cm and 57.5 cm TL for females and males of O. niloticus, L. intermedius and Clarias gariepinus, respectively. Fecundity was ranged between 100-947 eggs/g with absolute fecundity (AF) of 468-3,832 eggs, 200-1,000 eggs/g with AF of 2,752-136,420 eggs, and 505-900 eggs/g with AF of 2,000-6,404 eggs for O. niloticus, C. gariepinus, and L. intermedius, respectively. Their respective mean fecundity was 1,490 ± 91, 23,330 ± 5,070, and 3,096 ± 273 eggs, respectively. Mean fecundity revealed a significant variation between size classes and species (ANOVA, p < 0.05). The fecundity length and fecundity-body weight relationships except (O. niloticus) of fishes were curvilinear while the gonad weight (GW)-fecundity relationship was linear for all fish species. The fecundity was moderately associated with increasing length than body weight, and GW for all fishes (r² > 0.6). In conclusion, a tangible management setup is required to sustain the use of fish in the reservoir.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.3-11
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• 2000

In pretensioned concrete structures, bond between prestressing steel and concrete is an essential component to ensure the integrity of a pretensioned member. The anchorage and development of the prestressing force depend exclusively on bond. The purpose of this study is to investigate the characteristics of bond and development length between pretensioned steel and concrete. To resolve the controversy over the adequacy of the current code provision on development length of prestressing strands, a comprehensive test program has been scheduled and twenty four rectangular prestressed concrete beams have been tested to determine development length. Major test variables include diameter of strands (12.7mm, 15.2mm) and concrete covers (3cm, 4cm, 5cm). The test results indicate that the development length based on the bond stress-slip relation. The proposed model can evaluate realistically the development length of pretensioned prestressed concrete members and can be the good basis for the future basis of code equations on development length of PSC members.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.173-179
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• 2013

Population characteristics of Zacco koreanus were investigated at 4 stations in three National Parks of Korea from April to October 2012. Total length ranged 47mm~160 mm and weight ranged 0.50~41.50 g. Parameter b values in length-weight relationships ranged 2.883~3.497, which represent favorable conditions for habitation. Condition factor (K) had the range from 0.689 to 1.012. In relationships with sympatric fishes, the length-weight relationship (b) revealed inverse proportion to the number of species and populations. It is suggested that these differences resulted from the various factors including sympatric fishes, water temperature, seasonal changes, and surveyed stations.

• Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.30-36
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• 2007

We present age and growth data for Ilisha elongata, based on 363 specimens caught in 1999 and 2000 around Jeju Island and the southwest coast of Korea. Scale and ring radii of each ring group showed a direct one-to-one relationship, with ring radius increasing as scale radius increased. The relationship between fork length and scale radius was FL=39.553SR+60.935 for females, FL=39.474SR+54.026 for males, and FL=39.608SR+57.547 for both sexes. Monthly changes in the marginal index indicated that a new ring appears once each year (in July). Maximum age, mean age and mean fork length of fish were 10 years, 5.0 years, and 349mm, respectively. Von Bertalanffy's growth equations were $FL_t=495.4{\times}[1-\exp(-0.2586(t+0.6487))]$ for fork length (mm) and $W_t=1,112.5{\times}[1-\exp(-0.2586(t+0.6487))]^{2.874}$ for body weight (g) for both sexes. Monthly changes in the gonadosomatic index (GSI) indicated that the spawning period was in June and July, which corresponded closely with ring formation time. Differences in monthly GSI changes in 1999 and 2000 may be related to water temperature variation. Fecundity ranged from 5,664 to 176,290 eggs per individual (n=43, fork length 264-470mm). The relationship between fecundity(F) and fork length was $F=7.7{\times}10^{-7}{\times}FL^{4.9269}$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.66-73
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• 2002

Fin effectiveness and efficiency of a thermally asymmetric triangular fin are represented as a function of the ratio of fin lower surface Biot number to upper surface Biot number and the non-dimensional fin length. For this analysis, two dimensional separation of variables method is used. When fin effectiveness is 2 and efficiency is 90%, the relationship between the non-dimensional fin length and the ratio of fin lower stir(ace Biot number to upper surface Biot number is shown. The relationship between the non-dimensional fin length and the upper surface Biot number for the same condition is also presented.

• Journal of the Korea Furniture Society
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• v.12 no.1
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• pp.21-26
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• 2001

This study was carried out to get some basic information on mechanical properties of Platanus orientalis L. for the rational utilization of this wood. Relationship of anatomical characteristics with compression strength parallel to grain was analyzed using stepwise regression technique. All possible combination of 8 independent variables were regressed on compression strength parallel to grain. The summarized results in this study were as follows: 1. The compression strength parallel to grain increased with the increase of wood fiber length and wood fiber width. The strength, however, decreased with increase of number of pore per $\textrm{mm}^2$ and tangential diameter of pore. 2. The major factors affecting compression strength parallel to grain in heartwood were length of wood fiber and number of pore $per{\;}{\textrm{mm}^2}$ but width of wood fiber and length of vessel element were the important factors in sapwood.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.1
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• pp.55-62
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• 2004

Although the previous researches evaluated the fatigue behavior of glass fiber/epoxy laminates using the traditional fracture mechanism, their researches were not sufficient to do it: the damage zone of glass fiber/epoxy laminates was occurred at the delamination zone instead of the crack-metallic damages. Thus, previous researches were not applicable to the fatigue behavior of glass fiber/epoxy laminates. The major purpose of this study was to evaluate delamination behavior using the relationship between crack length and delamination width in hybrid composite material such as Al/GFRP laminate. The details of investigation were as follows : 1) Relationship between crack length and delamination width, 2) Relationship between delamination aspect ratio and delamination area rate, 3) Variation of delamination growth rate is attendant on delamination shape factors. The test results indicated that the delamination growth rate depends on delamination width delamination aspect ratio and delamination shape factors.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.109-116
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• 2017

Objective: This study aimed to investigate the relationship between leg stiffness and kinematic variables according to load while running. Method: Participants included eight healthy men (mean age, $22.75{\pm}1.16years$; mean height: $1.73{\pm}0.01m$; mean body weight, $71.37{\pm}5.50kg$) who ran with no load or a backpack loaded with 14.08% or 28.17% of their body weight. The analyzed variables included leg stiffness, ground contact time, center of gravity (COG) displacement and Y-axis velocity, lower-extremity joint angle (hip, knee, ankle), peak vertical force (PVF), and change in stance phase leg length. Results: Dimensionless leg stiffness increased significantly with increasing load during running, which was the result of increased PVF and contact time due to decreased leg lengths and COG displacement and velocity. Leg length and leg stiffness showed a negative correlation (r = -.902, $R^2=0.814$). COG velocity showed a similar correlation with COG displacement (r = .408, $R^2=.166$) and contact time (r = -.455, $R^2=.207$). Conclusion: Dimensionless leg stiffness increased during running with a load. In this investigation, leg stiffness due to load increased was most closely related to the PVF, knee joint angle, and change in stance phase leg length. However, leg stiffness was unaffected by change in contact time, COG velocity, and COG displacement.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.719-724
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• 2019

This study is an extension of our previous model for a size-based fish stock assessment. In the previous model, we applied an allometric length-weight relationship (W=α·L^β) to convert lengths of fish to weights, and estimated those parameters α and β, using data about lengths and weights aggregated over years. In this study, we focused on whether consideration of temporal (e.g., year-to-year) variability in those estimates (i.e., ${\hat{\alpha}}$ and ${\hat{\beta}}$) would contributive. After calculating year-specific estimates (i.e., year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$) by applying data about lengths and weights separated by year, we evaluated the contribution of those year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$ to the performance of the size-based stock assessment model. The model with such year-to-year variability being considered (lower AIC) outperformed that with the variability being ignored (higher AIC). We illustrated this study using data on Korean chub mackerel Scomber japonicus from 2005-2017.

• Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.224-233
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• 2023

This research was conducted at Langgur City, Southeast Maluku Regency, Maluku Province, Eastern Indonesia from November 2020 to February 2021 to study biological aspects of roundscads (Decapterus spp.) which consist of species composition, sex ratio, gonad maturation level, size distribution, length-weight relationship and condition factor. Samples were collected at traditional fish market in Langgur City. Fish samples collected at the market were put into cool box and then brought to the laboratory for further examination. Fish samples were identified, separated based on species, dissected to determine their sex and gonad maturation stage and then measured. Totally, there were 290 specimen collected which consist of five species namely Decapterus kurroides, D. macarellus, D. macrosoma, D. muroadsi and D. russelli. Sex ratio between male and female for all species showed 1:1. Gonad maturation level showed that stage I and II have higher percentage than stage III and IV indicates immature fish more dominant compare to mature one. Among five species found, D. macarellus has larger size while the smaller belongs to D. muroadsi. Results of length-weight relationship analysis showed that roundscads inhabiting Southeast Maluku waters have isometric and negative allometric growth pattern with relative condition factor around 1.00.