• Fisheries and Aquatic Sciences
• /
• v.17 no.3
• /
• pp.361-367
• /
• 2014

Cuttlefish Sepia esculenta are commercially important in Korea. Assessments of their biomass currently depend on fishery-landings data, which may be biased. Towards fishery-independent acoustic surveys of cuttlefish, target strength (TS) measurements at 70 and 120 kHz were made of 23 live cuttlefish, in early May 2010. The fish were caught by traps in the inshore waters around Geojedo, Korea. The TS were measured using split-beam echosounders (Simrad ES60 and EY500, respectively). The cuttlefish mantle lengths (L) ranged from 15.6 to 23.5 cm (mean L=17.8 cm) and their masses (W) ranged from 335 to 1020 g (mean W=556.1 g). Their mean TS values at 70 and 120 kHz were -33.01 dB (std=1.39 dB) and -31.76 dB (std=2.15 dB), respectively. The mean TS at 70 kHz was 0.17 dB higher than the TS-length relationship resulting from a least-squares fit to the data ($TS=24.67{\log}_{10}L(cm)-64.03$, $r^2$ = 0.52, N=23). The mean TS at 120 kHz was 0.45 dB higher than the fitted TS-length relationship ($TS=40.59{\log}_{10}L(cm)-82.96$, $r^2$ = 0.58, N=23). The differences between the mean TS values and an equation regressed from all of the TS measurements at both frequencies ($TS=24.92{\log}_{10}L(cm)-4.92{\log}_{10}{\lambda}(m)-22.82$, $r^2$ = 0.86, N=46) was 0.22 dB at 70 kHz and 0.31 dB at 120 kHz, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.46 no.3
• /
• pp.239-247
• /
• 2010

Species of fish such as striped beakperch, bluefin searobin and konoshiro gizzard shad are commercially very important due to their high demand in the Korean market. When estimating acoustically the abundance of stocks for these species, it is of crucial importance to know the target strength (TS) to the length dependence. In relation to these needs, the TS experiments were conducted on three different species in an acrylic salt water tank using two split-beam echo sounders of 70 and 120 kHz. The TS for these three species under the controlled condition was simultaneously measured with the swimming movement by a DVR system and analyzed as a function of fish length (L) and frequency (or wavelength $\lambda$). The equation of the form TS=a log (L)+b log ($\lambda$)+c was derived for their TS-length dependence. The best fit regression of TS on fork length for striped beakperch was estimated as TS=35.67 log (L, m) -15.67 log ($\lambda$, m) -46.69 ($r^2$=0.78). Furthermore, the best fit regression of TS on fork length for konoshiro gizzard shad was shown to be TS=25.85 log (L, m) -5.85 log ($\lambda$, m) -32.22 ($r^2$=0.51). The averaged TS for 12 bluefin searobins with a mean length of 24.36cm at 70 kHz was analyzed to be -41.55dB. In addition, the averaged tilt angle obtained simultaneously by a DVR system with TS measurements for 27 konoshiro gizzard shads swimming within an acrylic salt water tank was estimated at $-2.7^{\circ}$.

• Fisheries and Aquatic Sciences
• /
• v.19 no.2
• /
• pp.8.1-8.11
• /
• 2016

To quantitatively estimate the influence of cuttlebone on the target strength (TS) of golden cuttlefish, the cuttlebone was carefully extracted from 19 live cuttlefish caught using traps in the inshore waters around Geojedo, Korea, in early May 2010 and the TS was measured using split-beam echosounders (Simrad ES60 and EY500). The TS-length relationships for the cuttlefish (before the extraction of cuttlebone, Fish Aquat Sci. 17:361-7, 2014) and the corresponding cuttlebone were compared. The cuttlebone length ($L_b$) ranged from 151 to 195 mm (mean $L_b$ = 168.3 mm) and the mass ($W_b$) ranged from 29.3 to 53.2 g (mean $W_b$ = 38.8 g). The mean TS values at 70 and 120 kHz were -33.60 dB (std = 1.12 dB) and -32.24 dB (std = 1.87 dB), respectively. The mean TS values of cuttlebone were 0.19 dB and 0.04 dB lower than those of cuttlefish at 70 and 120 kHz, respectively. For 70 and 120 kHz combined, the mean TS value of cuttlebone was -32.87 dB, 0.11 dB lower than that of cuttlefish (-32.76 dB). On the other hand, the mean TS value of cuttlebone predicted by the regression ($TS_b$ = 24.86 $log_{10}$ $L_b$ - 4.86 $log_{10}$ ${\lambda}$ - 22.58, $r^2$ = 0.85, N = 38, P < 0.01) was -33.10 dB, 0.04 dB lower than that of cuttlefish predicted by the regression ($TS_c$ = 24.62 $log_{10}$ $L_c$ - 4.62 $log_{10}$ ${\lambda}$ - 22.64, $r^2$ = 0.85, N = 38, P < 0.01). That is, the contribution of cuttlebone to the cuttlefish TS determined by the measured results was slightly greater than that by the predicted results. These results suggest that cuttlebone is responsible for the TS of cuttlefish, and the contribution is estimated to be at least 99 % of the total echo strength.

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.3016-3018
• /
• 2005

The PSD(Position Sensitive Detector) is a sensor for detecting the position of incident light. Because of its various advantages, it is used for position and angle sensing, optical range finders, laser displacement sensing, and etc. In the previous study of the position finding system, the laser tracking robot is developed. Small data rate and unidirectionality is the characteristics of data communication both DSP-based pan/tilt control board and the robot. If we can transmit data to the target using PSD sensor and laser diode module, there is no need for communication devices such as the bluetooth and wireless module. For this reason, this paper presents the new method for data transmission. Transmit data using RS-232 is modulated by a VTF(Voltage To Frequency) converter The laser diode module transmits the modulated data. And then the PSD sensor receive that data. Demodulation process is accomplished by the system which is consisted with trans-impedance amplifier, FTV(Frequency To Voltage) converter, and etc.

• Aerospace Engineering and Technology
• /
• v.7 no.1
• /
• pp.223-228
• /
• 2008

In order to acquire the images requested by users, it is very important to calculate mission schedule parameters such as imaging execution time and attitude tilt angle accurately. These parameters are based on orbit prediction. This paper describes the accuracy of orbit propagation for image planning. The orbit prediction data from PSS and MAPS has a certain discrepancy due to different orbit propagator. It is necessary for mission planner to confirm this value during mission planning phase. The pointing error which means the difference between target center and real image received is calculated and analyzed using KOMPSAT-2 image data.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.1
• /
• pp.663-668
• /
• 2023

Recently it is very important to collect information such as enemy positions and facilities. To this end, unmanned aerial vehicles such as multicopters have been actively developed, and various mission equipment mounted on unmanned aerial vehicles have also been developed. The coordinate-oriented algorithm refers to an algorithm that calculates a gaze angle so that the mission equipment can fix the gaze at a desired coordinate or position. Flight data and GPS data were collected and simulated using Matlab for coordinate-oriented algorithms. In the simulation using only the coordinate data, the average Pan axis angle was about 0.42°, the Tilt axis was 0.003°~0.43°, and the relatively wide error was about 0.15° on average. As a result of converting this into the distance in the NE direction, the error distance in the N direction was about 2.23m on average, and the error distance in the E direction was about -1.22m on average. The simulation applying the actual flight data showed a result of about 19m@CEP. Therefore, we conducted a study on the self-error of coordinate-oriented algorithms in monitoring and information collection, which is the main task of EOTS, and confirmed that the quantitative target of 500m is satisfied with 30m@CEP, and showed that the desired coordinates can be directed.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.3
• /
• pp.424-431
• /
• 2015

This study was focused on acoustic scattering characteristics of jack mackerel (Trachurus japonicus) at frequency 38, 70, and 120 kHz by Kirchhoff-ray mode (KRM) model. The body length (BL) of 16 individuals ranged in 12.2~22.0 cm ($mean{\pm}S.D.$: $17.8{\pm}3.2cm$) and the swimbladder length ranged in 4.2~8.6 cm ($mean{\pm}S.D.$: $6.6{\pm}1.6cm$) and the swimbladder cross section ranged in $1.7{\sim}6.6cm^2$ ($mean{\pm}S.D.$: $3.8{\pm}1.6cm^2$). This result shows that results correlate well between the BL and the length and cross section of swimbladder. The swimbladder angle ranged in $7{\sim}12^{\circ}$ and the maximum TS values ranged in $-16{\sim}-5^{\circ}$ at tilt angle. The averaged TS-to-BL relationship were $TS_{38kHz}=20{\log}_{10}BL-65.33$ ($R^2=0.66$), $TS_{70kHz}=20{\log}_{10}BL-65.90$ ($R^2=0.67$), and $TS_{120kHz}=20{\log}_{10}BL-66.65$ ($R^2=0.65$). These results can be used fundamental data in order to estimate distribution and biomass of jack mackerel by using hydro-acoustic method.

• Fisheries and Aquatic Sciences
• /
• v.12 no.2
• /
• pp.152-161
• /
• 2009

The largehead hairtail (Trichiurus lepturus) is one of the most common fisheries stocks in the East China Sea and the Yellow Sea. The species is caught using a variety of fishing tools, such as a stow net or a long line, as well as jigging and trawling. Scientific investigations have been conducted throughout the world to enable evidence-based estimations for the management and protection of the main fisheries biomass. For example, inshore and offshore hydro acoustic surveys are performed annually using bottom- and mid-water trawls around the Korean Peninsula. However, to date, no acoustic survey has been conducted to estimate fish size distribution, which is necessary to construct a data bank of target strength (TS) relative to fish species, length (L), and frequency. This study describes the frequency and length dependence of TS among fishes in Korean waters for the purpose of constructing such a TS data bank. TS measurements of the largehead hairtail were carried out in a water tank (L 5 m$\times$width 6 m$\times$ height 5 m) at frequencies of 50, 75, 120, and 200 kHz, using a tethering method. The average TS patterns were measured as a function of tilt angle, ranging from $-45^{\circ}$ (head down) to $+45^{\circ}$ (head up) every $0.2^{\circ}$. The length conversion constant ($b_{20}$) was estimated under the assumption that TS is proportional to the square of the length. In addition, in situ TS measurements on live largehead hairtails were performed using a split beam echo sounder.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.4
• /
• pp.219-228
• /
• 2013

The surveillance imaging equipments are functioning to observe the shape of the target in real time or to measure its location precisely. The roles of such equipments are becoming more important in today's weapon systems.The aforementioned imaging equipments can be classified based on the modes of operations such as fixed, installed on cars, or composite of those. Also, according to different concepts of sensor operation, a separate type uses independent housing for each sensor whereas in a composite type a set of multiple sensors are housed into a unit altogether. The sensors in general have magnetism, thereby introducing the possible negative effects, particularly in the composite types, in locating the reference position, which is carried out by the digital compass. The use of shielding material/housing could be an option but results in increased weight and reduced portability, restricting its use in composite type equipments. As such, the objective of this paper is to study on how to reduce such magnetic effects on the position location. To do so, in the absence of magnetic shielding, a variety of sensor positions were first modeled. By combing the result with the fact that the functions of PAN & Tilt are used in the equipments, a new position location algorithm is proposed. The use of the new algorithm can automate the position location process as compared to the manual process of the existing approach. In the algorithm developed, twelve locations are measured in connection with both the azimuth and elevation angles in comparison to the six locations alone around the azimuth angle. As a result, it turns out that the measurement range has been widened but the measurement time reduced. Also, note that the effect of errors the operators may make during measurement could be reduced.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.2
• /
• pp.119-128
• /
• 2002

This study investigates dorsal aspect target strength with fish size, tilt angle and frequency characteristics for the schlegel's black rockfish(Sebastes achlegeli) and the red seabream (Pagrus major). This study was carried out on free swimming fish in a cage in order to obtain acoustic data of the biomass estimation using the scientific echo sounder. The results obtained from this study are summarized as follows; 1 The coefficients of the schlegel's black rockfish and the red seabream using maximum TS with fish length were expressed -63.7dB and -62.6dB at a frequency of 38kHz, -64.4dB and -65.4dB at 120kHz, and -62.4dB and -65.0dB at 200kHz, respectively. 2. The coefficients of the schlegel\`s black rockfish and the red seabream using averaged TS with fish length were expressed -68.4dB and -67.9dB at a frequency of 38kHz, -73.4dB and -72.7dB at 120kHz, and -70.BdE and -73.4dB at 2001Hs, respectively. 3. The coefficients of the schlegel's black rockfish and the red seabream using maximum TS with body weight were expressed -52.0dB and -50.9dB at a frequency of 38kHz, -52.7dB and -53.7dB at 120kHz, and -50.7dB and -53.3dB at 200kHz, respectively. 4. The coefficients of the schlegel's black rockfish and the red seabream using averaged TS with body weight were expressed -56.7dB and -56.2dB at a frequency of 38kHz, -61.7dB and -61.0dB at 120kHz, and -59.ldE and -61.6dB at 200kHz, respectively. 5. Varying the tiIt angle of the two red seabream from -26$^{\circ}$to +25$^{\circ}$, the variation width of target strength expressed smaller at a frequency of 38kHz than at 120kHz and expressed about 3~6dB higher head up than head down at 120kHz.