Seong-Jae Jeong

Vision-based Automatic System for Non-contact Measurement of Morphometric Characteristics of Flatfish

This paper introduces a vision-based automatic system (VAMS) for non-contact measurement of morphometric characteristics of flatfish, such as total length (TL), body width (BW), height (H), and weight (W). The H and W are simply measured by a laser displacement and a load cell, respectively. The TL and BW are measured by a proposed morphological image processing algorithm. The proposed algorithm cans measurement, when the tail of flatfish is deformed, and when it is randomly oriented. In the experiment, the average and maximum measurement errors were recorded, and standard deviations and coefficients of variation (CVs) for the measurements were calculated. From those results, when flatfish the TL measurements had an average of 266.844 mm, a standard deviation of 0.351 mm, a CV of 0.131%, and a maximum error of 0.87 mm with straightened flatfish (TL A : 267 mm, BW A : 141 mm), and when flatfish of different sizes were measured, the errors in the TL and BW measurements were both about 0.2 %. Using a single conveyor, the VAMS can process up to 900 fishes per hour. Moreover, it can measure morphometric characteristics of flatfish with a TL of up to 500 mm.

Measurement of size and swimming speed of Bluefin tuna (Thunnus thynnus ) using by a stereo vision method

This study was performed to develop a video based system which can be used to measure the averaged fish size in a non-intrusive fashion. The design was based on principles of simple stereo geometry, incorporated fish dimensions weight relationships and took into consideration fish movement to lower system costs. As the fish size is an important factor that impacts the economy of an aquaculture enterprise. Size measurements, including fork length, width or height, girth, thickness and mass, can be used to determine fish condition in the fish farm, so the averaged fish size of fish cage needs to consistently monitor in open ocean aquaculture cage. A precision of for replicate length measurements of a 60cm bar is obtained at distances between 2.0 and 6.0m, and the mean fork length and mean swimming speed of bluefin tuna were estimated to 48.8cm and 0.78FL/s, respectively.

A Study on Performance Analysis of a Fish Cage using Air Chamber Structure

Recently as a result of excessive development. pollution of the coast and occurrence of a typhoon year after year, fishermen suffer heavy losses in fish farming which is the one of the most important earnings ways. For solution of these problems, we need to go out into the open sea from an inland sea. In this study we suggested new fish cage which makes up for the structural weakness of existing wooden fish cages. It can farm fishes in the open sea of high wave and current with no damages from a typhoon. We substituted TPU(Thermoplastic Polyurethane) air chamber for existing styrofoam flotage which was harmful to the environment and impermanent. We used PE(Polyethylene) pipes for the maintenance of formation and the prevention of buoyancy loss caused by a breakdown of flotage. PE b rackets were designed to combine PE pipes with TPU air-chamber flotage. It has good strength and light weight. As a result of modeling test. it is great in buoyancy, strength and flexibility against wave. Because it can control buoyancy arbitrarily, moreover, we expect that it will reduce damages of a red water by applying it as semi-submerged fish cages.

Maneuvering character of hull form renovated tuna purse seiner

In an attempt to improve the maneuvering character of hull form renovated tuna purse seiner. A renovation was carried out on the 3 tuna purse seiner fishing vessel. To grasp the progress of maneuvering and resistance on ship B (730 ton class), new bulbous bow was only attached. The ship A (740 ton class) and C (600 ton class) were modified for new bulbous bow, enlarged slipway and rudder. And then the zigzag and the turning test were carried out. According to the turning test, the advance and the tactical diameter were improved very much for the modified ship. The sea trial was carried out for the original and modified ship A. It is showed that the results of sea trial corresponded with that of the tank test on the whole. In the result of the zigzag test on ship B, the turning ability was improved very much, but the yaw checking ability was deteriorated in just some degree. In the result of the zigzag test on ship C, the turning ability and yaw checking ability were remarkably improved. Ship C was greatly improved among the three ships for the maneuvering character of modified hull form.

Analysis of submerging characteristics and stability of the model submersible fish cage operated by buoyancy control

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 : 2 s, wave height : 0.1, 0.2, 0.3 m). As a result , in the still water condition the model cage kept horizontal balance and inclination degree of the upper frame was about 1。 . 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 。 . When the model cage reached at a depth of 1m, the upand-down motion of the cage was decreased by 12% compared with that of at the surface (period 2s, height 0.3 m). 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 .

Construction of a System for the Generation and Analysis of Design Waves using the Genetic Algorithms

In this study, an optimization routine with genetic algorithms is coupled for the selection of free variables for the production of a control signal for the motion of wave board in the numerical wave tank. An excitation function for the controlling of the wave board is formulated on basis of amplitude modulation for the generation of nonlinear wave packets. The found variables by the optimization serve for the determination of wave board motion both with the computation and with the experiment. The breaking criterion of the water waves is implemented as boundary condition for the optimization procedure. With the analysis of the time registration on the local position in the wave tank the optimization routine is accomplished until the given design wave with defined surface elevation is found. Water surface elevation and associated fields of velocity and pressure are numerically computed.

Analysis on underwater stability of the octagonal pillar type fish cage and mooring system

어업에 의해 어획되는 수산 자원의 감소 및 인구의 증 가에 따른 식량문제 해결을 위한 대안으로 수산 양식에 대한 관심이 집중되고 있으나, 기존의 내만 양식은 이미 포화상태이며, 잉여사료나 양식어류 배설물 등으로 인 한 양식장의 오염이 심각한 상태이다. 이와 함께 국내 수산양식은 저가 양식 어류의 수입, 사료비 및 유류비의 폭등, 소비의 다변화 미비, 양식어종의 단순화 등으로 대외 경쟁력은 점차 저하되고 있으며, 이러한 문제점을 해결하기 위하여 외해 양식기술 확립, 유전육종 연구, 사료 기술개발 등 다양한 시도를 하고 있으나, 현재까지 두드러지는 가시적인 성과는 미흡한 실정이다. 따라서, 양식경쟁력 확보를 위하여 내만 양식장의 외 해 이전, 양식품종의 다양화, 사료비 절감을 위한 사료연 구 등과 같은 다양한 방법으로 양식 경쟁력 확보를 위해 노력하고 있다. 이러한 다양한 방법들 가운데 하나로 참 다랑어를 주 대상어종으로 하여 외해에서 완전 양식기 술을 개발하기 위하여 노력하고 있으며, 외해라는 지리 적, 환경적 요인을 극복하기 위해 국내·외 연구기관에 서는 외해 양식 시설물 개발을 위한 노력이 현재까지 지 속적으로 진행되고 있다 (Huang et al., 2008; Suhey et al., 2005). 그러나 외해에 설치되는 가두리 같은 경우에는 내 만에 비해 자연적인 외력, 즉 조류이나 파고에 크게 노출 되어 있어 양식시설물을 설치할 경우 해상에서 발생할

Power supply performance photovoltaic (PV) system for 3-ton class fishing vessel

This study describes the result on PV system for evaluating the performance of small fishing boats. Photovoltaic system with 200 watts power generation facilities on the 3-ton fishing boat was carried. Load test was performed on the condition that the work lamps lit during night operations. As a result the performance can be used for more than two hours at 60 watt work lamps. The load test was performed on the condition that fishing vessels are on the cruising condition at sea. The solar power systems have been investigated as a power generation efficiency of about 36.55%. Additional tests show that the power generation efficiency is difficult to expect a maximum of 50% or more.Fuel consumption of fishing boats by installing a solar power system is reduced. Also the PV system is useful for the verification of their availability for fishing vessels as well as the satisfaction of the fishermen. The results for the durability of the photovoltaic device is acceptable, including a solar panel, controller and the performance exhibited no breakage in the harsh marine environment or failure so far. The installed PV system was confirmed that the durability with at least 2 years.Keywords: Photovoltaic energy, PV power system, Fishing vessel, Independent power system, Energy saving device

Longitudinal motion characteristics of a ship according to the location

In head sea , a ship has mainly the longitudinal motion such as vertical acceleration and pitch . In that case ,the motion characteristics of a ship will have changed as the location different from each of place verticallyand horizontally on board . The author carried out an experiment about the ship ’s vertical acceleration andpitch according to the location for the head sea , and analyzed the data with the aid of the statistical andspectral analyzing method to get the motion characteristics of the vessels . The response of verticalacceleration and pitch not deeply depend on the decks vertically , but displayed the relative big differentvalue horizontally even if same deck . The biggest response of vertical acceleration and pitch among theaccommodations was shown at scientist room , but the value of it not reached to the minimum requirement ofISO 2631-1 for working on board .Keywords: Head sea , Longitudinal motion , Vertical Acceleration , Pitch , Motion characteristics .

Generation of Freak Waves in a Numerical Wave Tank and Its Validation in Wave Flume

AbstractThe freak wave, also known as New-Year-Wave in the north Atlantic, is relatively large and spontaneous ocean surface wave that can sink even large shi ps and destroy maritime structures. To understand oceanic conditions that develop freak waves, we simulated and generated two versions of scale-downed waves (1:64 and 1:42) in a numerical wave tank and compared the results with the experiment in wave flume. Both of the breaking and non-breaking waves were generated in the simulation. The numerical simulation was implemented based on the finite volume method and a genetic opt imization algorithm. Random values were assigned as the initial values for the parameter in the control function, which produced signals representing the motion of wave-maker. T he same signal obtained from the optimization process was used for both of the simulati on and the experiment. By varying the object function and restrictions of the simulation, a best profile of design wave was selected based on the characteristics, height and period of simulated waves. Results showed that the simulation and experiment with the scale of 1:4 2 agreed better with freak waves in the natural condition. The presented simulation method will contribute to saving the time and cost for conducting subsequent response analyses o f motion under freak waves in the course of the model test for ship and maritime structure.