• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4551-4562
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• 2024

This paper elucidates a comprehensive derivation of the variational formulation pertaining to the static and spatial kinetics self-adjoint angular flux (SAAF) neutron transport equation. The methodology employed for discretization of the spatial variable is the finite element method, while the energy group discretization is executed via the group method, and the directional discretization is conducted using the discrete ordinates method. Analytic expressions for the discretization to variable separation under both vacuum and reflective boundary conditions are furnished. Constructed upon the MOOSE framework, a code designated as SAAFCGSN has been developed for the resolution of the SAAF neutron transport equation. The zero-order scattering matrix within this computational framework is managed through an innovative "decoupling" method, thereby enhancing the computational efficiency significantly. The functionality and robustness of the SAAFCGSN code are corroborated through meticulous evaluation involving seven distinct steady-state scenarios as well as two transient states. Empirical outcomes verify the compatibility of the SAAFCGSN code with both structured and unstructured mesh, inclusive of their amalgamations, thus facilitating maintenance and ensuring elevated computational accuracy. In addition, a performance analysis benchmarked against IAEA standards reveals that the adoption of the scattering matrix "decoupling" method propels a computational speed increase exceeding 30 %, signifying a notable advancement in calculation efficiency.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.3
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• pp.244-253
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• 1990

For the purpose of the investigation on the selective action of trawl net, a series of fishing experiments carryed out in M. S. Pusan 402 during the years of 1986~1987, by using a set of trawl net with a few pocket nets in each part of the bagnet. The author analyzed these experimental data and derived the following results. 1. 58 species of aquatic animals were caught in totally 43 times of trawl operation and 33 species of them did not escape at all through the barrier of netting in the bagnet. 2. Sardinops melanosticta, Harengula zunasi, Thrisa kamalensis, Englausis japonicus, little size of Tracurus japonicus, Sphyraena pinguis, Trichirus lepturus, and Psenopsis anomala escaped easily through the barrier of netting after being caught inside of the codend. Especially, Englusis japonicus escaped well not only through the netting of the codend but also through the netting of the square and the baiting. 3. In the case of mesh size of 60mm in the codend, Pampus argentus, Doderleinia bercoides and Tracurus japonicus were caught all in the size of less than 10cm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.3
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• pp.241-248
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• 1986

New Paint, Stapol N-6200D, products from Song Woun Industrial Co. Ltd., was tested on its chemical effect on fouling organisms attached to fishing nets. Two kinds of fishing nets with different mesh size, 5 mm (cage culture net) and 33 mm (set net) were painted and attached to $1m^2$ PVC quadrates. The quadrates with painted or non-painted fishing nets were placed at the surface water layer of southern coast of Korea. Monthly species composition and abundance of fouling organisms were analysed as well as total weight of fouling organisms including mud on fishing nets. On the other hand, anti-fouling effect of the organisms and mud on different color paints was studied and the durability of chemical effect of painted fishing net on fouling organisms was also estimated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.2
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• pp.129-139
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• 2002

Fish distribution characteristics are essential to assess and estimate fisheries resources in a particular area. The primary goal of this study is to determine the distribution characteristics by the bottom trawling in the Yellow Sea west of South Korea. The surveys were carried out between 33$^{\circ}$00'N~37$^{\circ}$00'N latitude and 124$^{\circ}$00'E~126$^{\circ}$00'E longitude at EEZ(Exclusive Economic Zone) of Korea in Yellow Sea on May and August, 1999 and April, 2000. The ships used in this survey were the R/V Chung-kyeong(G/T 300) and R/V Dong-baek(G/T 1,050) of Yeosu National University. The results obtained can be summarized as follows 1. From the trawl data the fisheries resources are seriously decreasing through most of the species(about more 50%) have been appeared only one time at the bottom trawl on April, 2000. The total fish species caught by the trawl net during the 3 times survey were 106 species and a few species(dominant species) of these occupied 50~90% of the quantity of the total quantity by number or by weight. Among the dominant species the tanaka's snailfish was recorded to be the most dominant species in the survey area. The fish species in the Yellow Sea were clustered according to the regions. They clustered in two or three partes to the south-north direction in the spring season and clustered in two parts to the on-off shore direction of the shore in the summer season. Most of the fish caught at the the trawl net with cover-net(30.3mm) were small sized. They were shorter than 15 cm in length and the extruding rate of the cod-end which was 60mm mesh size ranges about 90%. 2. The densities of the number and weight per unit volume derived from the total catches sampled in April, 2000 survey were $1532.2{\times}10^{-6}fish/m^3$ and $39.55{\times}10^{-6}kg/m^3$, respectively. 3. The density variation of fish population between 1999 and 2000 showed a slight tendency to increase.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.3
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• pp.241-258
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• 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 Korean Society of Forest Science
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• v.75 no.1
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• pp.32-37
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• 1986

In order to get the fundamental information that could be useful to judge the potentiality of occurrence of rapid shallow landslide in the objective slope, factors selected on Jinhae regions in Korea, where many landslides were caused by heavy rainfall of daily 465 mm and hourly 52mm in August 1979, was carried out through the multiple statistics of quantification method (II) by the electronic computer. The net system with $2{\times}2cm$ unit mesh was overlayed with the contour map of scale 1:5000. 74 meshes of landslides and 119 meshes of non-landslide were sampled out to survey the state of vegetative cover and geomorphological conditions, those were divided into 6 items arid 27 categories. As a result, main factors that would lead to landslide were shown in order of vegetation, slope type, slope position, slope, aspect and numbers of stream. Particularly, coniferous forest of 10 years old, concave slope and foot of mountain were main factors making slope instability. On the contrary, coniferous forest of 20-30 years old, deciduous forest, convex slope and summit contributed to the stable against Landslide. The boundary value between two groups of existence and none of landslides was -0.123, and its prediction was 72%. It was well predicted to divide into two groups of them.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.11-19
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• 2016

Field observation for oceanic conditions and paralarvae of the common squid, Todarodes pacificus in Korean waters were sampled with the Bongo net (diameter: 60 cm, mesh size: $333{\mu}m$) by using oblique tow method with the oceanographic research vessel (Tamgu 12 and Tamgu 20) around Korean waters (middle of the Yellow Sea, northern part of the East China Sea, East Sea) in 2013 and 2014 was carried out. The observation in the Yellow Sea and the northern part of the East China Sea was done in August, 2013 and in the East Sea it was repeated at seven times from June, 2013 to September, 2014. The paralarvae in August of 2013 was not found in the Yellow Sea and one paralarvae was found in the northern part of the East China Sea. In the East Sea, 39 paralarvae during whole observation period were found, mantle length of paralarvae was from 1.7 to 13.5 mm. Surface water temperature in the Yellow Sea was $30^{\circ}C$, and cold water mass lower than $10^{\circ}C$ was occupied in the deep layer than 30 m. In the northern part of the East China Sea, surface water temperature was $31^{\circ}C$, and higher water temperature above $20^{\circ}C$ was found in deeper than 50 m. In the East Sea, optimum temperature for survival, $15-24^{\circ}C$, was existed shallower than 75 m.

• 한국해양학회지
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• v.24 no.4
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• pp.165-171
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• 1989

To examine the sample variability of zooplankton, samples were collected at two stations in the nearshore off Anhung (Chungnam, Korea), using a NORPAC net (76 Cm diameter, 0.333 mm mesh size) for two days, April 5 and 6, 1989. The net was towed vertically to eliminate the source of variation due to vertical migration. During the period of 6 hours, triplicate sampling was done every one or two hour at each station. Species composition and abundances at two stations were not so different, but the abundances at each station varied greatly with respect to sampling time. Greater abundance at one sampling time ranged 2.3-8.7 times of smaller abundance at another sampling time. At the level of ${\alpha}=0.05$, however, mean abundances of different sampling time did not differ significantly from each other due to the large variance. It was believed that the large variance was caused by the time dependent effect of patchiness of which parameters were varied with time because of sea water movement. From the variation within the triplicate samples, it was considered that the abundance data obtained from single tow were not significantly different from the data in the range of 50-200% of those from single tow. From these results, the necessity for the replicate and time dependent sampling was indicated. In the nearshore like the sampling site of this study, it seemed to be better to reduce the number of stations for the replicate and time dependent sampling though the proper sampling scheme was to be decided based on the goal of the study.

• Ocean and Polar Research
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• v.24 no.4
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• pp.407-417
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• 2002

Species composition and abundance of zooplankton were investigated around Dokdo in the East/Japan Sea in autumn 1999 and spring 2000. Vertical and horizontal hauls of a bongo net ($300{\mu}m$ mesh size, 60cm diameter) were made to collect zooplankton sample. Surface temperature and salinity ranged from $24.2^{\circ}C\;to\;25.1^{\circ}C$, and from 32.9psu to 33.2psu in September 1999, respectively. In May 2000, surface temperatures were $13.9^{\circ}C\;and\;14.2^{\circ}C$ at stations of A1 and A8, and salinity was 34.5psu at both stations. Zooplankton community was dominated by copepods which comprised 61% (September) and 60% (May) of total numerical abundance, respectively. The next dominant groups were appendicularians (11%) and chaetognaths (9%) in September 1999, and other crustaceans (27%) and appendicularians (4%) in May 2000. The 15.7% (September) and 23.2% (May) of copepods were in the juvenile stage of copepodites. The most dominant copepods were Oncaea media (10.4%) and Clausocalanus sp. (8.2%) which preferred warm water in September. In contrast, cold-water copepods such as Pseudocalanus minutus (9.4%) and Metridia pacifica (8.0%) were dominant in May. The results of cluster analysis based on Bray-Curtis index showed that zooplankton community were classified into two groups which represented different water mass. The average abundance of zooplankton in September was 2.1 times higher than that in May, and species number of them in September outnumbered that in May by 29 species. Zooplankton community varied in associated with a characteristic of warm waters which affected marine ecosystem differently in the study area depending on seasons.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.230-237
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• 2020

In this part, an implicit time dependent solution is presented for the Boltzmann transport equation discretized by the analytic coarse mesh finite difference method (ACMFD) over the spatial domain as well as the simplified P₃ (SP₃) for the angular variable. In the first part of this work we proposed a SP₃-ACMFD approach to solve the static eigenvalue equations which provide the initial conditions for temp dependent equations. Having solved the 3D multi-group SP₃-ACMFD static equations, an implicit approach is resorted to ensure stability of time steps. An exponential behavior is assumed in transverse integrated equations to establish a relationship between flux moments and currents. Also, analytic integration is benefited for the time-dependent solution of precursor concentration equations. Finally, a multi-channel one-phase thermal hydraulic model is coupled to the proposed methodology. Transient equations are then solved at each step using the GMRES technique. To show the sufficiency of proposed transient SP₃-ACMFD approximation for a full core analysis, a comparison is made using transport peers as the reference. To further demonstrate superiority, results are compared with a 3D multi-group transient diffusion solver developed as a byproduct of this work. Outcomes confirm that the idea can be considered as an economic interim approach which is superior to the diffusion approximation, and comparable with transport in results.