# Presentation: 153680

## A technical Approach for the development of offshore-cage in Korean sea

- Fisheries Engineering Team, NFRDI
- Dr. -Ing. Seong-Jae Jeong
- Denkmal@momaf.go.kr

## Introduction
Korean fish-farming facilities
Fish-cage design
Model tests
Results and Discussion
Conclusions

- Korean fish-farming facilities
- Fish-cage design
- Model tests
- Results and Discussion
- Conclusions

- Index

## 1. Introduction

- Backgrounds
- 	_82% of total fish-cages are installed at inshore coast of southern sea_
- 	→ Water pollution, exploitation of
-           inshore aquaculture farm
-      → Annually damaged by typhoon
-      → Long-term strategy for
-           fish-farming & aquaculture in (at)
-           offshore

- West
- 10 %

- South
- 82 %

- East
- 8 %

## 1. Introduction

- Backgrounds
-   _Design Concept of Fish-cage at Korean sea_
- 	→ Higher Waves & ocean current up to 3kn
-     → Reasonable price for farm-fisher or cage-owner
-     → Norm, standardization & maintenance
-     → Budget for development?
-   → For inshore or offshore?
-     → What systems for Mooring?

## 2. Korean fish-farming facilities

- Fish-farming facilities at Korean inshore

## 2. Korean fish-farming facilities

- Damaged Fish-cages due to typhoon

## 3. Fish-cage design

- _Design Concept of Fish-cage_
-   → Higher Waves & ocean current up to 3kn
-     → Reasonable price for farm-fisher or cage-owner
-     → Robust cage-structure: steel or PE?
-     → Norm, standardization & maintenance
-     → Floating, submergible, submerged or hybrid?
-   → For inshore or offshore?
-     → Mooring system: Tension leg or catenary?

## 3. Fish-cage design

**Model of Fish-cage for Experiment **

| Type |  | Type3 | Type4 | Type5 |
| --- | --- | --- | --- | --- |
| Dim. (m) |  | Dia.:1.4 | 1x1x1 | 1x1x1 |
|  Height (m) |  | 0.7 | 1 | 1 |
|  Height from free surface
 (m) | s. subm. | 0.15 | 0.15 | 0.15 |
|  | Subm. | 0 | 0 | 0 |
|  Buoyancy (kgf) | s. subm. | 7.60  | 8.69  | 12.32  |
|  | Subm. | 8.14 | 9.23 | 12.86 |
| Initial tension
(kgf) | s. subm. | 5.31 | 6.14 | 8.50 |
|  | Subm. | 5.85 | 6.68 | 9.04 |
|  Initial tension
(kgf/mooring line) | s. subm. | 1.33 | 1.54 | 2.12 |
|  | Subm. | 1.46 | 1.67 | 2.26 |
| Weight (kgf) |  | 2.29 | 2.55 | 3.82 |
|  Add. buoyancy material
(4x1.4 kgf) |  | 5.6 | 5.6 | 5.6 |

## 4. Model tests

- 1

**1. View of 3D Towing Tank**
**2. Direction Spectrum Wave Maker**
**    ****Max. Wave Height : 0.5m**
**3. Main Carriage :**
**     ****9(L)X11.6(B)X3.5(H)m**
**    ****Max. Speed : 3.0m/s**
**    ****Max. Acceleration :  0.6 m/s****2**
**4. Sub-Carriage with Turn Table**

## 4. Model tests

- Measurement of motion for 2 floating models
- 	→ 2 cases (rectangular & circle form type) with Catenary mooring
- Measurement of motion according to mooring methods
- 	→ Tension leg vs. catenary mooring system with rectangular model
- Measurement of motion according to shape of fish-cage
- 	→ Rectangular with legs vs. hexahedron shape under regular & irregular
-           wave train
- Measurement of mooring forces
- 	→ 2x2x2[m] hexahedron shape under floating vs. submerged conditions

## 4. Model tests

- Analytical solution
- 	→ with potential theory using singularity method+tension-leg model
- Analysis by model test under...
- 	→ Regular wave train : H=0.2m, T=1.5s
-      → Irregular wave train with ISSC Spectrum : H1/3=0.2m, T=1.5s

## 4. Model tests

- Model tests

**Catenary mooring**

**Tension leg mooring**

## 5. Results & Discussion

- 1. Floating cage models

**Rectangular cage under regular wave**

**Cicular cage under regular wave**

## 5. Results & Discussion

**Mooring method under regular wave**

**Mooring method under irregular wave**

- 2. Mooring methods

## 5. Results & Discussion

**According to shape under regular wave**

**According to shape under irregular wave**

- 3. According to shape of models

## 5. Results & Discussion

- 4. Mooring force (floating)

- 4. Mooring force (submerged)

## 6. Conclusions

- A primitive concept of technical Approach for the development of offshore-cage at Korean sea is performed
- Surge, Heave & Pitch components of motions are very important, and analyzed by untouchable 6-degree measuring equipment
- Hexahedron shape with tension leg mooring system is the best choice with the model scale by model tests ... but real scale?
- Mooring forces of model cage are measured and can be applied for installation of mooring at real sea
- To be progress of construction of small scale offshore fish-cage for object of the test in real sea

## 4. Model tests

- Submergible cage model