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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean society of Fisheries Technology
Journal Basic Information
Journal DOI :
The Korean Society of Fisheries Technology
Editor in Chief :
Volume & Issues
Volume 26, Issue 4 - Dec 1990
Volume 26, Issue 3 - Sep 1990
Volume 26, Issue 2 - Jun 1990
Volume 26, Issue 1 - Mar 1990
Selecting the target year
Detection and Analysis of Acoustic Emission Signal at the Epicenter on the Circular Glass Plate During Pencil Land Fracture
Lee, Jong-Gyu ; Jang, Ji-Won ; Park, Jeong-Man ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 1~7
Theoretical evaluations of the vertical displacement at the epicenter on the circular glass plate have been carried out in the case of the unit point loading(1 dyne force strength) with the Heaviside step-function time dependency. Acoustic emission signals generated during pencil lead(
=0.5mm, HB) fracture on the soda-lime glass(
=22cm, thickness=2.8cm) were observed by the optical Michelson interferometer with the stabilized circuit, and then the source function of the observed acoustic emission signals was analyzed by the deconvolution method. The source function of acoustic emission during pencil lead fracture had a 'dip' of~0.7
sec duration time at the front portion and a step function of~0.5
sec rise time with a force strength of~4.5N.
Study on TSD Characteristics of LiF ( Mg , Cu , P ) Single Crystal
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 8~13
The microscopic relaxation parameters for the single crystal were measured by using thermally stimulated depolarization (TSD). Initial rise method, various heating rate method and total glow peak method were used for the determination of the activation energy and Debye relaxation time from TSD glow curves. Activation energy, pre-exponential factor and relaxation time for impurity-vacancy dipole reorientation were 0.55eV, 1.97
10 super(-12) sec and 12.19sec in average, respectively. Dielectric dissipation factor for the crystal was calculated from the measured TSD glow curve, its value being about 3
동지나해의 초음파 산란층에 관한 연구 ( 1 ) ( Acoustic Scattering Layers in the East China Sea ( 1 ) )
Lee, Dae-Jae ; Shin, Hyeong-Il ; Park, Jung-Hee ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 14~19
This paper describes on the characteristics of the acoustic echoes from the scattering layers by the aggregation of marine organisms which was measured by using a 50kHz echo sounder on board of the training ship SAEBADA belong to National Fisheries University of Pusan during the summer, 1989 in the East China Sea. A data acquisition system was used to record digitally the envelope of the echoes and the frequency distribution of echo amplitudes on the whole water column was examined as a function of time during the sunrise and sunset periods. Acoustic data showed that the abundance distribution of marine organisms according to depth in the servery area changed with time and that the organisms were most active during the twilight of morning, and the echo strength on the water column or scattering layer was also strongest during this time. Additional results of this survey suggest that other interest, such as the relationship between environmental conditions and biomass depth distribution, could be also investigated in hydroacoustic method.
Acoustic Scattering Layers in the East China Sea ( 2 ) -Vertical Distribution of Volume Scattering Strength-
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 20~25
During the summer of 1989, the authors carried out the hydroacoustic surverys to investigate the vertical distribution of volume backscattering strength in the East China Sea and simultaneously the biological sampling of the scattering layers by bottom trawling. The echoes from the scattering layers was continuously measured by using a 50 kHz echo sounder during the day and night. A data acquisition system was used to record digitally the envelope of the echoes and the echo integration technique was used to determine the scattering strength proportional to biomass density in each layer. The vertical profiles of volume backscattering strength also were compared with the one of water temperature. The results obtained can be summarized as follows: 1. The vertical profiles of mean volume backscattering strength at day and night suggested that during the night the biggest fish concentrations appeared in the mixed layer above the thermocline and during the day near the bottom. In another profiles where the thermocline was not well developed, peaks in scattering appeared at midwater depths and near the bottom. 2. The maximum values of mean volume backscattering strengths varied from -49.3 dB to -48.0 dB on different regions and at different times of the day and night. 3. Trawl data indicated that the organisms consisting of the scattering layer near the bottom were squid and various species of demersal fishes.
The Mixing of Forced Plume In the Coastal Waters
Jang, Seon-Deok ; Seo, Jeong-Mun ; Lee, Jong-Seop ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 26~33
The behavior and mixing process of the forced plume are studied in the hydraulic laboratory. The dilution rate of discharged waste water from the port in various hydraulic condition was analized. The effect of densimetric Froude number and the discharge type on the dilution rate are discussed: In the vertical discharge, the forced plume of small densimetric Froude number mixes more actively than that of the large one. In the horizontal discharge, forced plume of large densimetric Froude number dilutes more rapidly than that of the small one. The mixing takes place more vigorously in the horizontal discharge than in the vertical one. The multi-port diffuser is more effective for the waste water discharge system than the single port diffuser in the tidal swinging coastal sea.
Target Strength for the Mugil Cephalus , Pleuronichthys Cornutus and Hexagrammos Otarii
Hwang, Du-Jin ; Sin, Hyeong-Il ; Lee, Dae-Jae ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 34~44
This paper describe on the target strengths for the dorsal and the side aspects of swimbladdered fishes, Mullet Mugil cephalus, Flounder Pleuronichthys cornutus and Rock trout Hexagrammos otakii two frequencies of 50KHz and 200KHz in the experimental water tank in order to improve the biomass estimation by the scientific fish finder. The results obtained are as follows: 1. The average of maximum target strength normalized by squared total length in cm unit are almost ranging from -70.9 dB to -66.8 dB regardless of species or frequencies. 2. The average of maximum target strength normalized by two-thirds squared body weight in g unit are almost ranging from -57.1 dB to -54.1 dB regardless of species or frequencies. 3. In comparison with target strength for 50KHz and 200KHz the former is more strong than the latter.
Mechanization of Fishing Operation on the Sea Eel Pots
Ha, Jeong-Sik ; Kim, Yong-Hae ; Jang, Chung-Sik ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 45~50
The basic investigation of the sea eel pots fisheries by questionnarie observation and dimension of the pots by fishing operation were carried out in order to develop for mechanical hauling system with 20~50 gross tonnage fishing boats from June to December, 1988. Number and weight of fish per pot between smaller diameter 11cm and larger 13cm of the pot have no significance so that the drag of the smaller pots can be decreased about 20% than the larger pots. The operating time by two men from opening to closing with screwing lock entrance was slightly faster than that by three men with knotting entrance even though the losses with two kinds of entrances while fishing operation were about the same. It was very reasonable that stone and lead sinker on the main line were substitute for two or three lead core P.P rope to make it smooth surface of the main line for mechanization of the continuous fishing operation
Acoustic Scattering Characteristics of the Sea Bottom ( 1 )
Lee, Dae-Jae ; Sin, Hyeong-Il ; Park, Jung-Hui ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 51~56
The authors carried out an experiment to investigate the echo fluctuations from ocean bottom due to ship's motion. The bottom echoes was continuously measured, by using a 50 kHz Echo sounder on board of the ship being at anchor under the sea condition of 15 knots in wind velocity and approximately 2 meters in wave height, to extract the information about the pulse stretching and the ship's motion from the first return and the second return. A data acquisition system was used to record digitally the envelope of the echoes, and the analysis was applied to the echo data collected from the continental shelf in the South China Sea. The results obtained can be summarized as follows: 1. The equivalent pulse width of the second return echoes from ocean bottom was 2.4 times longer than that of the first return echoes. 2. The echo peak values of the first return fluctuated markedly than that of the second return and was shown to be extremely sensitive to small change in ship's motion. 3. Energy target strength and peak target strength of the sandy-mud bottom were -13.4 dB and -14.6 dB, respectively.
Analysis on the Dynamic Response of Vertical Pumps Subjected to Arbitrary Foundation Excitation
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 57~64
It is important in design of vertical pumps to consider arbitrary foundation excitation in addition to rotor vibration due to unbalance. In this study, a model of a vertical pump was developed for the analysis of its dynamic response. The vertical pump was modeled with lumped masses and springs which represent mult-cylinderical and rotor structure. A dynamic simulation program was developed and numerical calculation on the above mentioned problems were carried out.
A Study on the Comparison of Injection Rate Measurement by the Bosch`s Method and the Zeuch`s Method
Ra, Jin-Hong ; Kim, Jun-Hyo ; An, Su-Gil ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 65~75
There have been many methods for measuring the injection rate of diesel engines, but the results of them are not always identical and the reason for the discordance is not clear. Besides, a single shot injection equipment has been used for the fuel spray and the combustion research of diesel engines, but the results of experiment using the equipment don't apply to a volleyed shot injection of real engines. This paper investigates the merits and faults of the Bosch's method and the Zeuch's method, at the same, this paper also compares the injection rates of single shot inject rates of single shot injection and a volleyed shot injected by the Bosch's method. the results are summarized as follows: (1) The measurement error of the Bosch's method is about
1%, therefore, its accuracy is reliable. (2) By the Bosch's method, as the speed and the load of fuel pump increase, the injection rate becomes higher, on the contrary, the injection period(ms) shortens as the speed increases and the load decreases. (3) In this experiment, the injection rate of a single shot injection is lower than that of a volleyed shot injection under the same conditions. (4) The bulk modulus of elasticity using the Zeuch's method increases in proportion to the back pressure. (5) The Zeuch's method is less accurate than the Bosch's method.
Control of DC-Servomotor Speed by Using Fuzzy Controller
Kang, Geun-Taek ; Kim, Young-Taek ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 76~80
DC-servomotor acts an important role in robots and manipulatirs. But the precise control of DC-motor is difficult by a using usual linear controller because of the nonlinear characteristics of DC-motor. This study suggests the use of fuzzy controller in the control of DC-servomotor speed. The fuzzy controller is designed from a fuzzy model which can represent nonlinear systems very well. Hence the fuzzy controller is very useful in the control of nonlinear systems such as DC-motor. We construct a fuzzy model of DC-servomotor, design a fuzzy controller from the fuzzy model, and compare that with a linear controller. When we use the fuzzy controller, the static ripples are reduced and the rise time is required 20% less than in using a linear controller.
Design of Servo Control System Using Bilinear Transformation Approach
Kim, Sang-Bong ; An, Hwi-Ung ; Ji, Seok-Geun ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 81~87
In this paper, a new design method in which transient response behavior of a servo~system can be improved, is proposed using a bilinear transformation method which assigns the poles of the closed-loop system in a specified region. The servo-system is a dynamic system which follows the given reference input automatically. In the above meaning, the design of a servo-system is similar to a regulator design problem for the extended system which is resulted from the given system and the reference input by the well known internal moel principle. In the design problem of servo control system, it is supposed that the proposed design method has more practical meaning in comparison to the other design methods, in the views of assigning the characteristic roots of the closed loop system in a specified region satisfying a design specification for the given transient response rather than in the exact positions of the poles. The applicability of the design method proposed in this paper was proved by the simulation results for the angle control problem of an electrical servo mechanism.
A Study on the Design of the Optimal Control System for Electric Driving Digital Governor
Kim, Seong-Hwan ; Ra, Jin-Hong ; Yang, Ju-Ho ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 88~100
Since sea state changes engine load instantaneously, the speed governing apparatus is essential for marine engine to maintain constant speed regardless of the load. As governing apparatuses, mechanical, pneumatic, and electric governors have been employed. But, recently, according to the introduction of low speed-ling stroke engines to increase thermal efficiency, the development of governor which has better response characteristics is requisite. In this paper, to design the governor that meets above requirement, author made a performance test for the existing PID control digital governor with the aid of computer simulation, and investigated digital governor applying the optimal control algorithm, then, executed computer simulation by the same way. As the result of simulations, found that the former let engine have large overshoot and long settling time at low speed, on the other hand, the latter made engine have better response. If we design and invent a good observer for delay time element so that the optimal control theory can be applied, better governor will be expected.
A Study for Improving the Computing Speed of FFT Using 16bit Microcomputer
Kim, Seok-Jae ; Ji, Seok-Geun ; Kim, Cheon-Deok ;
Journal of the Korean society of Fisheries Technology , volume 26, issue 1, 1990, Pages 101~108
The processing efficiency of the special purpose hardware which is designed and implemented for the FFT caculation was investigated in this paper. This hardware equipment was consisted of LSI chips of four high speed multiplier and adde
stractor, and was interfaced with the 16bit microcomputer(NEC PC-9801E). The FFT processing time by this hardware equipment was improved approximately 4.8 times by the co-processor(Intel C8087-3).3).