• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.39 no.3
• /
• pp.197-210
• /
• 2003

The non-float midwater pair trawl was effective in the mouth opening and control of the working depth in midwater and bottom. In contrast, we confirmed that it was difficult to keep the net at surface above 30 m of the depth by means of the full scale experiment in the field and the model test in the circulation water channel. To solve this problem, the kites were attached to the head rope of the non-float midwater pair trawl. In this study, four kinds of the model experiments were carried out with the purpose of applying the kite to the korean midwater pair trawl. The results obtained can be summarized as follows: 1. The working depth of the non-float midwater pair trawl with the kite was shallower than that of the proto type and non-float type. The working depth of the kite type was approximately 20m with 2 kites and about 5m with 4 kites under 4.0 knot. The working depth was almost constant but the depth of the head rope sank approximately 15m and 10m according to the increase in the front weight and the wing-end weight, respectively. The changing aspect of the working depth was constant, but the depth of the head rope sank approximately 22m according to the increase in the lower warp length (dL). 2. The hydrodynamic resistance of the kite type was almost increased in a linear form in accordance with the flow speed increase from 2.0 to 5.0 knot. The increasing grate of the hydrodynamic resistance tended to increase in accordance with the increase in flow speed. The hydrodynamic resistance of the kite type was larger approximately 5～10 ton larger than that of the non-float type and the proto type. The hydrodynamic resistance of the kite type increased approximately 3ton with the changing of the front weight from 1.40 to 3.50 ton and approximately 4 ton with the changing of the wing-end weight from 0 to 1.11 ton and approximately 5.5 ton with the changing lower warp length (dL) from 0 to 40 m, respectively. 3. The net height of the kite type was increased approximately 10 m with the change in the kite area from $2,270mm^2$ to 4,540 $\textrm{mm}^2$. The net height of the kite type was aproximately 50 m and 30 m larger than that of the proto type and the non-float type, respectively. The changed aspect of the net width was approximately 5m with the variation of the flow speed from 2.0 to 5.0 knot. 4. The filtering volume of the kite type was larger than that of the proto type and the non-float type by 28%, 34% at 2.0 knot of the flow speed and 42%, 41% at 3.0 knot, and 62%, 45% at 4.0 knot, and 74%, 54% at 5.0knot, respectively. The optimal towing speed was approximately 3.0 knot for the proto type and was over 4.0 knot for the non-float type, and the optimal towing speed reached 5.0 knot for the kite type. 5. The opening efficiency of the kite type was approximately 50% and 25% larger than that of the proto type and the non-float type, respectively.

• Korean Journal of Ichthyology
• /
• v.17 no.4
• /
• pp.279-286
• /
• 2005

The fish species composition and its seasonal variation of the middle East Sea of Korea were investigated from May 2004 to January 2005 using gill and set nets. A total of 59 species of fishes belonging to 31 families in 11 orders were identified in the gill and set nets; 33 species in 15 families and 6 orders were collected by the gill net, and 36 species in 26 families and 10 orders were collected by the set net. Among the fishes collected by gill net, the order Scorpaeniformes was dominant; the number of species as well as individuals was highest in summer; the biomass was highest in winter. However, in fishes collected by set net, the order Perciformes was dominant, the number of species was highest in autumn, the number of individuals was highest in spring, and the biomass was highest in winter. The fish composition of the middle East Sea differed considerably from that of the south East Sea, especially in the species composition of the order Scorpaeniformes and Pleuronectiformes. Principal component analyses for each net showed that the fish species composition depends on the kind of net used, even though the investigation was carried out in the same area and at the same time.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.8 no.3
• /
• pp.307-316
• /
• 2003

Fish assemblage structure in a sheltered shallow water in the Southern Coast of Korea was examined monthly. Sampling was conducted in Doam Bay using a beam trawl between March 2001 and February 2001. A total of 53 fish species from 33 families were caught. Pinkgray goby (Chaeturichthys hexanema), ponyfish (Leiognathus nuchalis) and yellowfin goby (Acanthogobius favimanus) were the most frequent species, comprised 67.4％ of the total numbers captured. Snailfish (Liparis tanakai), yellowfin goby (Acanthogobius flavimanus) and pinkgray goby (Chaeturichthys hexanema) represented 50.8％ of the total biomass. While total abundance (number of individuals) and biomass were high in autumn and winter, species richness (number of species) and diversity were high in spring. Cluster analysis, based on monthly abundance data of the 14 most frequent species, showed that the species were separated into three different groups. Group A composed of pinkgray goby, yellowfin goby, robust tonguefish (Cynoglossus robustus) and scaly hairfin anchovy (Setipinna taty), which were year-round residents, and devil flathead (Onigocia spinosa), Red dragonet (Repomucenus lunatus) and ponyfish, which were abundant in autumn, group B surmullet (Upeneus japonicus), hairtail (Trichiurus lepturus) and gaff-topsail goby (Cryptocentrus filifer), which were abundant in summer, and group C grassfish (Liparis tanakai), spotted velvefish (Erisphex pottii), chameleon goby (Tridentiger trigonocephalus) and Richardson dragonet (Repomucenus richardsonii), which were abundant in winter and spring. A seasonal homogeneity of fish assemblage indicates that overall fish assemblage in Dom Bay is largely controlled by year-round residents.

• The Korean Journal of Malacology
• /
• v.30 no.1
• /
• pp.25-32
• /
• 2014

The age and growth of Neptunea (Barbitonia) arthritica cumingii sampled from the West Sea of Korea were determined from 1,062 operculums from October 2007 to September 2008. Age of Neptunea (Barbitonia) arthritica cumingii was determined from the rings on the operculum. The relationship between shell height (SH; mm) and shell width (SW; mm) was expressed by the following equation : SW = 0.5757 SH + 0.222 ($R^2$ = 0.8723), and shell height (SH; mm) and total weight (TW; g) was highly correlated by the equation : TW = 0.0002 $SH^{2.8162}$ ($R^2$ = 0.9121). The main spawning periods was estimated June to July through fatness index analysis. The relationship between shell height and ring radius of operculum in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variations in the marginal index (MI) of the operculum, it is assumed that the ring of this species was formed once a year during the period of July to August. Growth curves for shell height (SH) and total weight (TW) fitted to the von Bertalanffy's equation were expressed as follows : $$SH_t=173.964(1-e^{-0.164(t+1.173)})$$ $$TW_t=407.952(1-e^{-0.164(t+1.173)})^{2.8162}$$

• The Korean Journal of Malacology
• /
• v.25 no.3
• /
• pp.189-196
• /
• 2009

Based on 1,260 samples, the age and growth of purple whelk, Rapana venosa (Valenciennes) (Gastropoda:Muricidae) have been investigated. The samples were collected monthly during one year time (from February, 2004 to January, 2005) from the West Sea of Korea. The age of R. venosa was determined by the ring of the operculum analysis. The relationship between whelk's shell height and ring radius in each ring group was expressed as an equation of linear regression and later a correspondence in each ring formation was determined. Based on the monthly variations in the marginal index (MI) of the operculum, it was assumed that the ring of this species has been formed once a year during the period from July to August. The relationship between shell height and shell width was expressed by the equation SW = 0.7867 SH - 6.3988 ($R^2$=0.8604); and between shell height and total weight by the equation $TW=0.0000626{\times}SH^{3.206}$ ($R^2$=0.8324). The purple whelk's spawning period was estimated through the fatness analysis and has occurred during the period from May to July. Obtained results suggests that the ring formation occurs once a year (in July) and the length of time period since the first ring has been formed on the operculum is approximately 13 months (1.08 year). The purple whelk's growth curves for shell height and total weight fitted to the von Bertalanffy's equation and were expressed as follows: $SH_t=199.653(1-e^{-0.104(t+2.478)}$ $TW_t=1484.105(1-e^{0.104(t+2.478)})^{3.206}$.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.41 no.1
• /
• pp.1-8
• /
• 2005

In order to find out the environmental factors influencing movement of common grey mullet, Mugil cephalus in funnel net fishing ground of the Dolsan-do, Yeosu southern sea area, the oceanographic factor such as the water temperature, isobath and tidal current were observed respectively, the water temperature was compared with the amount of common grey mullet caught by funnel net. Also, to investigate the movement direction of common grey mullet in same sea area, 160 common grey mullets of body length 22 to 51cm caught at funnel nets of the Dolsan-do southern sea area were marked and then released at 5 positions in 5 times. The results obtained are summarized as follows : 1. The water temperature at the funnel net fishing ground of Dolsan-do in 2002 was ranged from 6.9 to 27.4$^{\circ}C$. The water temperature was displayed a maximum value in August to increase from March and a minimum value in February of the ensuing year to decrease from September. The catches of gray mullet caught by funnel net were generally abundant from March to September, but decreased sharply from October. The optimum range of water temperature for the funnel nets fishing was situated between 15.0 to 25.0$^{\circ}C$. 2. The isobath from 6m to 13m in coast sea set up funnel nets were densely distributed and the depth more than 14m of isobath were widely spreaded to the open sea at Dolsan-do southern sea area. 3. The tidal current of the coast sea set up funnel nets flowed southward and northward along the coast ato ebb and flood tide respectively. The direction of tidal current to the open sea was southeast at ebb tide with the mean speed 43cm/sec, but northwest at flood with the mean speed 25cm/sec. 4. The recapture rate through the experiment duration showed 9.4%. The recapture rate in Gyedong area was very high value with 33.3% as compared with others. The movement of common grey mullet in Dolsan-do southern sea area trended toward a inner bay and north bound mainly.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.34 no.3
• /
• pp.241-258
• /
• 1998

The experimental demersal trawl surveys to provide the essential information for the assessment, management and utilization of commercially important fish stocks 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. The biological sampling was conducted by using the trawl net with a cover net of 36 mm in mesh size at 64 planned trawl stations during daylight to identify the biological characteristics of fish. Each catch was standardized into catch per unit of time and the catches at each trawl station were sorted, weighed and counted by species. The changes in catches of each fish species and the shifts in dominant species by seasions and sampling regions in the research area were analyzed, and the abundance of fish was estimated from the relationship between the trawl catches and the volume of the water column sampled by demersal trawls. The results obtained can be summarized as follows : 1. During the 64 demersal trawls conducted in the southern waters of Korea, 129 species including 112 species of fishes, 8 species of Cephalopoda and 7 species of Crustacea, were identified Also, during the 1996 and 1997 trawl surveys in the reseach area, a large number of commercially important species with small differences in proportion was found. me proportion of Japanese horse mackerel which comprised 19.8% of the total catch by weight was highest, followed by chub mackerel(15.0%), swordtip squid(9.0%), redwing searobin(6.2%), konoshiro gizzard shad(6.1%), Japanese flying squid(5.8%), silver pomfet(5.1%), blackmouth goosefish(5.1%), etc. Swordtip squid, Japanese flying squid, blackmouth goosefish and blackthroat seaperch were among the dominant species in all seasons with a relatively high and stab1e proportion(3.6~9.0%), and were widely distributed in the entire southern water of Korea. 2. The catch rates by cover net varied at 0.7~91.9% by weight of the total trawl catch by codend and cover net at 64 planned trawl stations and the mean catch rate was 44.4%. Species comprising a major portion of the catches by cover net mainly were swordtip squid, konoshiro gizzard shad, the juveniles of Japanese horse mackerel, blackthroat seaperch and chub mackerel, etc. 3. The distribution density of fish in terms of biomass per unit volume which derived from the catch data by 63 bottom trawl hauls in the southern waters of Korea ranged from 17.9 $\times$ 10-6 to 1,440.9 $\times$ 10-6kg/m3 with the mean value of 153.8 $\times$ 10-6 kg/m3. These fish densities varied between seasons, location of sampling stations and sea conditions. From these results, it is worth noting that the catch composition of multispecies and the increased occurrence of small fish in the southern waters of Korea may also result in new problems in determining the total allowable catch(TAC) levels for economically important species.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.41 no.1
• /
• pp.35-45
• /
• 2005

The experiment was conducted to investigate the species composition of catches collected by the bottom trawl on June 24 to 26, 2004 in the southern waters of Korea using a trawler "DONGBAEK" belongs to Yosu National University. The investigation was carried out at the 5 stations and the towing speed was 3.4${\sim}$3.7k't. The catches were composed of 46 species from 37 families, 10 orders and 2 classes for fishes and 2 species, 2 families and 2 orders for Chondrichthyes and 44 species, 35 familes, 8 orders for Osteichthyes. The catches of Perciforms were the highest as 24 species and 18 families for fishes. The catches of Spear squid, Loli해 bleekeri and Red banded lobster, Metanephrops thomsoni were also the highest for mollusca and crustacea as 1 class, 3 species, 3 families, 2 orders, 1 class and 7 species, 5 families, 1 order, 1 class respectively. In the 5 stations, number of individuals and biomass were 1,144 and 376.0kg at ST-1, 908 and 240.3kg at ST-2, 666 and 90.1kg at ST-3, 2,050 and 300..4kg at ST-4 and 561 and 24.7kg at ST-5. The diversity index of each stations ranged between 1.49 and it showed the richness index of 2.13${\sim}$3.48, the evenness index of 0.48${\sim}$0.77 and the dominance index of 0.43${\sim}$0.8. Body length distributio of the dominant specise were 9${\sim}$32cm(fork length) for Japanese horse mackerel, Trachurus japonicus, 7${\sim}$23cm(mantle length) for Common squid, Todarodes pacificus, 9${\sim}$43cm(mantle length) for Spear squid, Loli해 bleekeri, 23${\sim}$36cm(total length) for File fish, Thamnaconus modestus, 10${\sim}$28cm(fork length) for Yellow porgy, Dentex tumifrons, 10${\sim}$36cm(fork length) for Target dory, Zeus faber and 8${\sim}$35cm(fork length) for Red seabream, Pagrus major.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.13 no.2
• /
• pp.2262-2275
• /
• 1971

Fourteenes rervoirs maintained by the local land improvement associations in the province of Chullabuk-Do and 20 reservoir maintained by thos in the province of Chullanam-Do, were surveyed in connection with a correction between storage capacity and sediment deposit. In addition to this survey, 3,347 of small reservoir, that lie scattered around in the above-mentioned two provinces were investigated by using existing two provinces were investigated by using existing records pertaining to storage capacity in the office of City and country, respectively. According to this investigation the following comclusions are derived. 1. A sediment deposition rate is high, being about $10.63m^3/ha$ of drainage area, and resulting in the average decreasc of storage capaity by 27.5%. This high rate of deposition coule be mainly attributed to the serve denudation of forests due to disorderly cuttings of trees. Easpecially, in small reservoir, an original average design storage depth of 197mm in irrigation water depth is decreased to about 140mm. 2. An average unit storage depth of 325.6mm as the time of initial construction is decreased to 226mm at present. This phenomena causes a greater shortage irrigation water, since it was assumed that original storage quantity was already in short. 3. Generally speaking, seepage rates through dam abutment intakepipe, etc, are high due to insufficient maintenance and management of reservoir. 4. It is recommended that sediment deposit should be dredged when a reservoir is dry in drought. 5. Farmers usually waste excessive irrigation water. 6. Water saving methods should be practiced by applying only necessary water for growing stage of rice. 7. In are as where water defficiency for irrigation is severe, a soil moisture content should be kept at about 70% by applying water once in several days. 8. Tube wells should be provided so as to exploit ground water and subsurface current below stream bed as much as possible. 9. If an intake weir was constructed, a water collection well should be built for the use in drought. 10. Water conservation should be forced by converting devastated forests contained in the drainage area of reservoir to protected forests so as to take priority of yrefor estation, gully control, the prohibition of disorderly cutting of trees, etc. 11. Collective rice nurseries should be adopted, and it should be recommended that irrigation water for rice nurseries is supplied by farmer themselves. 12. Sediment desposit in reservoir should be thoroughly dreged so as to secure a original design storage capacity. 13. The structure of overflow weir should be automatic so as to freely control flood level and not to increase dam height.

• Sijohaknonchong
• /
• v.21
• /
• pp.47-76
• /
• 2004

Newly discovered ${\lceil}Gogeummyeongjakga{\rfloor}$ is a copy collection of the old poetry SI-JO, which is specified in the book of yellow Gojeongji. {$\lceil}Gogeummyeongjakga{\rfloor}$ is guessed to be copied before the 17th year of King Yeongjo's reign(1740) and thus it's the early collection in the history of the Korean verse, Shijo. According to our research, there are 78poems in the collection and nine out of them hasn't been yet reported to the Korean Academy. The characteristics of Shijo in the book are followed. First. The collection is different from other books since the book was written in Korean instead of Chinese characters, which shows the uniqueness of the Korean literature in the late 17th and the early 18th century. Secondly, there are different versions of a poem in the collection, which is quite unusual in the other collections. There are different words or phrases used in different versions and even the whole verse is modified in some cases. Thirdly. two out of newly discovered nine short lyric songs is transformed from and that are kind of Chinese Ak-Bu. By the way, the compiler of ${\lceil}Gogeummyeongjakga{\rfloor}$ seemed to understand the co-relation between Ak-Bu and Shijo. and that's why he chose transformed Shijo from Ak-Bu not Chinese poetry. Among nine poems, <9> and <10> are newly discovered responding songs unknown up till now.