• The Journal of Fisheries Business Administration
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• v.52 no.2
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• pp.33-54
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• 2021

This study is aimed to analyze the economic feasibility of yellowtail culture using the copper alloy net cage in Gyeongsangbuk-do. First of all, in order to evaluate the copper alloy net cage on yellowtail culture, I review the trend on the yellowtail culture industry and research the concept of copper alloy net cage. The copper-alloy net cage is now recognized as an advantages of its system stability, recycling, antibiosis and food safety. The results were summarized as follows: first, there was significant meaning of the profit model of yellowtail culture by the price difference. Second, I analyzed in the economic feasibility of yellowtail culture using the copper alloy net cage, internal rate of return (IRR) was 51.58%, a benefit-cost ratio was shown to be 2.27 and net present value (NPV) was 1,087,337 thousand won, which indicates the economic feasibility of yellowtail culture using the copper alloy net cage is profitable. Finally, in order to improve the economic valuation, it is necessary to focus more on the developing of technology and cost reduction strategy on the copper alloy net cage.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.2
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• pp.84-91
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• 1993

The dynamic behaviors of a launcher under impulsive forces are analyzed. All the components of the system, ie ; chassis, turret, cage and suspension parts, are modeled as rigid. The dynamic analysis code, which is developed with the formulae describing the system equations of motion in terms of relative quantities, is used to carry out the analysis. The results show the dynamic responses of chassis and cage when the driving constraints are imposed on turret and cage.

• Journal of Drive and Control
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• v.14 no.3
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• pp.18-24
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• 2017

The purpose of this paper is to develop a new submersible fish cage operated by a pneumatic system for offshore aquaculture. Although some researchers have investigated modeling and control of fish cages, such cages consist of variable ballast tanks that with closed cylinders and thus present a maintenance issue. In solving the issue the new submersible fish cage investigated consists of bottom-opening cylinders. Accordingly, we designed a mathematical model of the concept and applied Sliding Mode Control for nonlinear angle control. Some experiments conducted under assumed conditions indicate that the angle of the system converges to zero under all conditions and the control has the stability to balance the fish cage.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.1
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• pp.44-53
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• 2006

The expansion of near shore aquaculture is feasibility of moving aquaculture facilities into the open ocean. Numerical modeling technique using finite element method was used to enable the optimum design and evaluation of submersible aquaculture cage system. The characteristics of mooring loads response in mooring lines under waves and current and their response amplitude operators were calculated for single and three point mooring configuration at the surface condition and submerged one. The static mooring loads without wave and current loading were similar for both the surface and submerged configuration. It was calculated that three point mooring was more adequate than single point mooring for the mooring configuration of submersible aquaculture cage system. The wave induced response amplitude operators for the single point mooring configuration with the influence of currents were identical to those without the influence of currents.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.10a
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• pp.30-36
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• 1995

This paper proposed on the effective cutting conditions of cage motor rotor by turning. If you want to introduce automatic manufacturing system into the cutting process of cage motor rotor, the selections of effective cutting conditions are necessary. The cutting process of cage motor rotor requires the precision and the out of roundness of cage motor rotor. The surface roughness of cutting face. it is very important factor with effect on the magnetic flux density of cage motor rotor. The purpose of this study is to find out the effects of cutting condition. upon adapting this results, we will improve the production rate in the cutting process of cage motor rotor. As a result, the selection of cutting conditions are important factors to production rate. And these are chosen by the investigations of cutting characters and surface roughness. The experimental result, showed that the increase of cutting speed caused the decrease of cutting force and the high surface integrity. The increase of feed rate and increase of depth of cut caused the increase of cutting force and surface roughness. Thus, the effective cutting conditions of cage motor rotor by turing are cutting speed 291m/min, feed rate 0.10mm/rev, depth of cut 0.05mm.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.1
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• pp.40-50
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• 2012

This study aims to analyze the performance of a submersible fish cage which was designed for developing an economical cage system can be applied in korean aquaculture environment easily. To analyze the performance of the designed cage a model test was carried out. In the test, inclination changes of the upper frame and mooring tensions of model cage were measured during the submerging and surfacing motion in still water and wave condition (period: 2s, wave height: 0.1, 0.2, 0.3m). As a result, in the still water condition the model cage kept horizontal balance and inclination degree of the upper frame was about $1^{\circ}$. In the wave condition, the model cage showed bilateral symmetric up-and-down motion but the average inclination degree of the upper frame was about $0^{\circ}$. When the model cage reached at a depth of 1m, the up-and-down motion of the cage was decreased by 12% compared with that of at the surface (period 2s, height 0.3m). In the same wave condition, the maximum and average line tension under the bottom position were about 8% and 11% respectively compared with that of at surface.

• Animal Bioscience
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• v.35 no.3
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• pp.444-452
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• 2022

Objective: An experiment was conducted to evaluate the effect of different levels of crude protein (CP) and two rearing systems (cage and floor), on blood parameters and digestive and reproductive organ development of brown laying hens. Methods: A total of 400 Hisex Brown laying hens between 30 and 45 weeks of age were distributed in a completely randomized design and a 2×4 factorial arrangement, with main effects including two rearing systems (cage and floor) and levels of CP (140, 150, 160, and 180 g/kg), in a total of eight treatments and five replicates of 10 birds each with initial body weight of 1,877 g (laying hen in cage) and 1,866 g (laying hens in floor). The parameters evaluated were plasma total protein, albumin, uric acid, total cholesterol, relative weights of oviduct, abdominal fat, liver, gizzard, crest and dewlap, length of small intestine and oviduct. Results: The blood parameters were similar in birds reared in cage and floor systems. The birds reared on the floor showed greater small intestine and oviduct weight (%) and lower liver and pancreas weight (%). A significant interaction was observed between factors for the relative gizzard, crest and dewlap weight, serum protein, uric acid, and total cholesterol (p<0.05). The diets with 140 g/kg CP resulted in lower serum protein and lower cholesterol in birds reared in floor system, while birds reared in cage system showed no effect of CP on both parameters. Birds reared in cage and fed with 140 and 150 g/kg CP presented lower uric acid. The group of birds reared in floor system fed 180 g/kg had greater uric acid. Conclusion: The dietary protein level can be reduced up to 140 g/kg for Hisex Brown hens (30 to 45 weeks of age) without an important effect on metabolic profile and organ development in both rearing systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.231-236
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• 2012

This paper presents the MPPT(Maximum Power Point Tracking)control method of the PMSG wind generation system using the turbine model with a squirrel cage induction motor. The torque of squirrel cage induction turbine model is controlled by mathematization of speed characteristics of real blade. In this paper, maintenance and cost issues into consideration, except for previous method using information of the velocity of the wind speed sensor, the algorithm is presented. The algorithm is controlled by tracking the optimal point, the generator speed and maximum grid power. The vector controls of the generator side converter and the grid side converter are controlled respectively to obtain maximum torque and regulate unity power factor. With Psim simulations and experiments, the efficiency of squirrel cage induction turbine model and the validity of control algorithm are verified.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.186-193
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• 2024

Most fishing nets used in fish cage aquaculture are made of synthetic fibers such as polyamide (PA) and polyethylene (PE). Therefore, it is challenging to maintain the internal volume of the fish cage due to biofouling, which can increase the load on the cage or reduce dissolved oxygen levels by impeding smooth current flow. To address this issue, research has been conducted to replace conventional synthetic fiber cage nets with brass nets, demonstrating certain benefits such as improved productivity and ease of fish cage management. However, given the need for a more thorough examination of brass fishing net weaving technology and performance, this study assessed the optimal weaving method for brass fishing nets to be used in fish cages. Additionally, it provided essential data for the practical application of brass fishing nets by evaluating their weight, tensile strength, elongation, fatigue resistance, and wear resistance. The study concluded that weaving brass fishing nets using the chain link method ensures durability, ease of installation, and compact storage in a scroll-like form. Moreover, due to their superior fatigue and wear resistance properties, brass nets can offer increased utility if appropriate net diameter and length are selected to compensate for their higher weight per unit area and relatively higher cost compared to existing fiber fishing nets.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.132-140
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• 1997

The basic experiment on the telemetry system of temperature and salinity, which is a study for the effective management of costal fishing-ground nowadays, was carried of 8 days from April 5, 6, 26, 27 , 1996 to May 31 and June 1, 21, 22, 1996 at the fish farm of Yooksam at Samyang-Myun, tongyongkun(34。45.02'N, 128。24.79'E). The results obtained were as follows : 1. The average temperature and salinity of STD of telemetry system was coincided with that of ICTD system calibration precisely. 2. A daily variation of temperature in fish cage which was measured by the telemetry system was influenced mainly by sunrise and sunset. 3. A daily variation of salinity in fish cage which was measured by the telemetry system was influenced mainly by tidal current. 4. The fish school in fish cage was distributed mainly 2~7 m layer during daylight and was arisen to the surface at sunset, was settled down to the bottom at sunrise.