• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.3
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• pp.259-273
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• 1998

The hydroacoustic surveys to provide the essential information for the assessment, management and utilization of fishery resources in the southern waters of Korea were carried out during five research cruises between October 1996 and October 1997 by the training ship KAYA of Pukyong National University. These hydroacoustic investigations were designed to obtain more precise estimates of the geographic distribution, absolute abundance and biological characteristics of the fishery resources, and the vertically integrated densities of fish in terms of volume backscattering strength(SV) by survey region and depth bins, such as the entire water column and the 0~ 10 m from bottom fraction, were measured separately. Hydroacoustic data were collected by using a Simrad EK 500 Scientific echo sounder operating at two frequencies of 38kHz and 120kHz and the data stored in field were later processed on a HP PC using a Simrad EP 500 echo integration and target strength analysis system. The biological compositions of echo signal were identified and sampled using a demersal trawl during daylight hours. The mean target strength to scale the echo integration data for hydroacoustic surveys was derived from the relationship between the SV and the weight of trawl catch per unit volume of the water column sampled by demersal trawls. The results obtained can be summarized as follow : 1. The mean volume backscattering strength for the entire water column in the southern waters of Korea between 1996 and 1997 were -67.2 dB and -70.9 dB at two frequencies of 38 kHz and 120 kHz , respectively, and for the bottom layer of the 0-10 m from bottom friction were -68.8 dB, -70.2 dB, respectively. That is, the volume backscattering strength for the entire water column at low frequency was higher than that at high frequency. 2. The relationship between the mean backscattering strength (〈SV〉, dB) for the depth strata of trawl hauls and the weight (C, kg/m3) per cubic meter of the catch sampled by bottom trawling in the southern waters of Korea in January and July 1997 were expressed by the following equations: 38 kHz : 〈SV〉= -28.2 + 10 log(C), 120 kHz : 〈SV〉= -32.4 + 10 log(C). The mean weight -normalized target strengths derived from these equitions were -28.2 dB/ kg, -32.4 dB/ kg at 38 kHz and 120 kHz , respectively. That is, the mean weight -normalized target strength at 38 kHz was 4.2 dB higher than that at 120 kHz. 3. The distribution density of fish in terms of biomass per unit volume in the southern waters of Korea were estimated to be 125.9 $\times$ 10-6 kg/m3 and 141.3 $\times$ 10-6 kg/m3 at 38 kHz and 120 kHz , respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.629-636
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• 1996

The developments of mariculture fisheries depend on both the natural environmental inputs such as sun, rain, wind, tide and the economic inputs such as ships, fuels, facilities, labor. for the enhancement of mariculture productivity in Deukryang Bay, a new attempt has been made to connect the environmental resources and the economic activity within one system. This study applies EMERGY analysis that evaluates environmental energies, fuels, goods and services in terms of solar emjoelus. In total EMERGY use $(69.65\times10^{20}\;sej/yr)$ the natural environment inputs is $78\%\;(54.60\times10^{20}\;sej/yr)$. This means that the mariculture in Deukryang Bay depends on mainly environmental resources. Net EMERGY yield ratio was 4.63 which indicated high value as a resource, EMERGY investment ratio was 0.28 that means to gain 3.6 times energy from the natural environment than those of economy. If the fisherie's products are made by renewable EMERGY input to Deukryang Bay, the calculated carrying capacity of fishes, crustaceans, shellfish and seaweeds were 1,140, 110, 1,553 and 9,074 ton/yr, respectively. If the quantity of renewable EMERGY input to mariculture grounds in Deukrysng Bay was calculated-based on only shellfish product, shellfish products was estimated as about 1,195 ton/yr.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.30-37
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• 2012

This paper assessed environmental impact of tidal power plant construction in the western sea of Korea, and diagnosed problems of the related assessment. We also proposed key assessment items (scoping) and system improvement for environmental impact assessment (EIA). The establishment of a broad consensus of the appropriateness and a clear purpose for business is an important aspect of the aptness of using the waters, and the aggressive collecting of opinions of the stakeholder and institutions will have to be fulfilled. In addition, we presented the following scoping plan in order to minimize the negative effects of the marine ecosystem and the conflict between the people who work in the fishing industry which result due to the construction of the tidal power plants. (1) the change in seawater exchange rates and the aspect of erosion/sedimentation which result from the change in the velocity of running fluid, (2) the destruction of spawns/habitats of fish due to the damage of tidal flats, (3) fishery resources, impacts of fishing grounds, and the spread of suspended sediments, etc. will have to be applied to the key assessment items(scoping). In addition, every citizen will have work hard for an establishment of an active plan which achieves the harmony and balance of environmental preservation and for the policy to be applied through changing their consciousness of environmental preservation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.133-139
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• 2001

In order to obtain fundamental data for estimation of fisheries resource by echo sounder, we carried out the measuring of dorsal aspect Target strengths for rock bream and dusky spinefoot fishes that were caught much around the Jeju Island and in South Sea of Korea. The appropriate equations share the common form. TS=A+20 log L, where TS is the average dorsal aspect target strength in decibels, L is the fish total length in centimeters, and the coefficient A is determined by a least mean squares regression analysis. For rock bream, the result is TS=-72.97+20 log L and, for dusky spinefoot it is TS=-63.16+20 log L And, we have investigated the bearing range of maximum dorsal aspect target strength for all of rock bream and dusky spinefoot by the echo sounder with transducer of which frequency is 200kHz. They are $-12^\circ$-$-21^\circ$and $-1^\circ$--8 espectively, when the fishes is swimming down to the bottom. The maximum dorsal target strengths are -41.50dB at -18 or rock bream and -30.69dB at $-6^\circ$for dusky spinefoot.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.261-265
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• 1994

To detect naturally occurring bioactive compounds in unused marine resources such as marine by-products and algae, the screening test for the antimicrobial compounds containing in Asterina pectinifera, Halocynthia rotetzi skin, Nototodarus sloani ink. Anthocidaris crassispina skin, and four algae(Sargassum horneri, Agarum cribrosum, Odonthalia corymbifera and Desmarestia ligulata) was carried out. The minimum inhibitory concentrations(MIC, ${\mu}g/disk$) of ether and methanol fractions extracted from Sargassum horneri against Bacillus subtilis were 80 and 70 ${\mu}g/disk$, respectively. The MICs of the ether, acetone and methanol fractions extracted from Sargassum horneri against Staphylococcus aureus were 160, 180 and 70 ${\mu}g/disk$, respectively. In addition, the MICs of ether and acetone fractions extracted from Odonthalia corymbifera against Staphylococcus aureus were 50 and 170 ${\mu}g/disk$, respectively. These nonpolar fractions showed the strongest antimicrobial effect among several fractions extracted from tested marine resources.

• Economic and Environmental Geology
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• v.35 no.1
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• pp.55-66
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• 2002

There are several abandoned coal mines around Donghae mine area in the Taebaek coal field. Two major creeks, Soro and Sanae, are contaminated with the colored precipitates formed from the coal mine drainages. Bed rocks of the study area consist of limestone, shale, and sandstone. Limestone consisted mainly of calcite and dolomite, and shale of quartz, pyropyllite and chlorite, and sandstone of quatz and illite. Coal coal spoil dumps composed mainly of pyrite and chlorite. The oxidative dissolution of sulfide minerals leads to acid mine drainage and adds the metal ions in the stream water. The ion concentrations of Fe, Ca, Mg, Al, Si, SO$_{4}$in the stream polluted by AMD are generally higher than those in the unpolluted stream water. High concentrations of Ca and Mg, Al and Si can be resulted from dissolution of carbonate minerals such as calcite, dolomite and aluminosilicates such as chlorite, pyrophyllite. Although the Fe, Al, Si, SO$_{4}$ contents are considerbly high in the acid water released from the mine adits, they become decreased downstream due to dilution of unpolluted water and precipitation of oxide/hydroxide and sulfate minerals on the bottom of stream.

• Resources Recycling
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• v.12 no.1
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• pp.33-40
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• 2003

Mn was extracted by using a nitric acid from the reduced ferromanganese dust and the basic experiments were taken to refine the manganese nitrate solution by means of precipitation of Ca, Mg oxalate. The dust was generated in AOD process producing a medium-low carbon ferromanganese and collected in the bag filter. Manganese oxide content in the dust was about 90% and its phase was confirmed as $Mn_3$$O_4$. $Mn_3$$O_4$ in the dust was reduced to MnO by roasting with activated charcoal. The main impurities in the extracted solution prepared by leaching the reduced dust with nitric acid were Na, K, Fe, Si, Ca, Mg etc. Among them, Fe was removed by controlling pH of the solution more than 4 and precipitating $Fe(OH)_3$, simultaneously silicious material solved in the solution was removed by co-precipitation with the ferric hydroxide. Addition of 150 g reduced dust into 4N HNO3 solution 1$\ell$ was appropriate to control the pH of the solution to pH 4. To differ greatly the solubilities of manganese oxalate and calcium or magnesium oxalate in a solution containing a high concentration of Mn, pH of 4 or less and addition of ($NH_4$)$_2$$C_2$$O_4$ in equivalent with Ca and Mg are recommended. At this time, the higher temperature was the shorter the precipitation reaction time was needed.

• Resources Recycling
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• v.22 no.5
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• pp.13-19
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• 2013

The effect of pH on the citrate leaching behavior of heavy metal ion was investigated to develop an eco-friendly process for removing heavy metals from soil contaminated with copper, zinc, and lead. The leaching tests were performed using citrate solution with pH adjusted by mixing citric acid and sodium citrate under the following leaching conditions: particle size, under $75{\mu}m$; temperature, $50^{\circ}C$; citrate concentration, $1kmol/m^3$; pulp density, 5%; shaking speed, 100 rpm; leaching time, 1 hour. The difference of pH before and after the leaching test was not observed, and this result indicates the direct effect of hydrogen ion concentration on the leaching of metals was insignificant. The removal ratios of copper, zinc, and lead from the contaminated soil decreased with increasing pH. The thermodynamic calculation suggests that the leaching behaviors of metal ions were determined by two reactions; one is the reaction to form complex ions between heavy metal ions and citrate ion species, and the other is the reaction to form metal hydroxide between heavy metal ions and hydroxide ion.

• Resources Recycling
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• v.22 no.3
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• pp.28-35
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• 2013

The recycling of the Si/SiC mixture sludge obtained from solar cell industry is very significant, environmentally and economically. The sintering characteristics of Si/SiC mixture sludge was studied for the purpose of recycling. In this study, to understand sintering behavior, SiC content in the Si/SiC mixture was controlled using an air separator. Various Si/SiC mixtures having different SiC contents were sintered using carbon black, clay and aluminum hydroxide as sintering aids. Physical properties of Si/SiC mixture and sintered bodies have been characterized using SEM, XRD, particle size analyzer and apparent density measurement. SEM and particle size analysis result confirmed that the fine particles less than 1 ${\mu}m$ decreased or removed more effectively through the air separator in the case of 95% SiC sample compared than the case of 75% SiC sample or original SiC sample. Further, with addition of the Aluminum Hydroxide, ${\beta}$-cristobalite phase gradually decreased while mullite phase gradually increased. The addition of the carbon black improved the sintering characteristics.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.3
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• pp.247-255
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• 1995

This paper describes a personal computer(PC) based color fish finder to improve some problem of the commercial one. The commercial fish finder has no function of the echo data logging and replaying. The authors developed two types of the PC based color fish finder. One is a master type composed of a PC, a digital input-output board, and analog to digital converting (A/D) board and an ultrasonic transceiver unit, the other is a slave type composed of a PC and an A/D board. To test the performances of the master type experiments were carried out in air and in a water tank. It is found that the designed master type fish finder displays very well an eight-colored echogram by one dot resolution to the left side of the PC monitor. Also, the depth of echo signal was corresponds very well to the range from the transducer to a target. The sampling interval of echo signal is about 0.1m and the time of A/D conversion is 30 $\mu$sec. On the other hand, to test the performances of the slave type a raw data of echo signals from a data logger was supplied directly or via RF transceivers to the slave type one. From this experiment, it is confirmed the slave type is useful to replay the echo signal from the data logger or a telesounder.