• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.3
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• pp.423-431
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• 2020

This study was conducted to investigate in vivo and in vitro digestibility in juvenile Atlantic Bluefin tuna Thunnus thynnus. In vivo digestibility was compared between four experimental diets to determine the optimum dietary inclusion level of an enzyme-treated sardine fish meal (EFM) and sardine fish meal (FM). The experimental diets were as follows; EFM75 (75% EFM), EFM60 (60% EFM and 15% FM), FM75 (75% FM) and SL (frozen sand lance) as a raw fish feed. Feces of Bluefin tuna (90.3 g) were collected both by siphoning from a 700 L cage and by dissection in 69 ton concrete rearing tanks. For the siphoning method, protein digestibility was higher in the tuna fed SL diet than that of other groups. The lowest protein digestibility was observed in FM75. For the dissection method, protein digestibility was higher in tuna fed EFM75 diet than that of other groups. The lowest protein digestibility was observed in the EFM60 group. In vitro digestibility was compared in six protein sources to find an alternative source of EFM for the tuna feed. The highest in vitro digestibility was observed in EFM (92%) followed by low temperature FM (72%), meat meal (65%), feather meal (60%), sardine fish meal (57%) and poultry by-product meal (55%).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.955-965
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• 2013

The joint tactical information distribution system (JTIDS) is used as the communication terminal of Link-16 by the United States armed forces, north atlantic treaty organization (NATO), and other allied forces. A portion of Link-16 frequencies may be shortly remapped to other systems owing to the growing demand for frequencies, especially in civil aviation, which is witnessing a constant increase in air traffic. This will affect the performance of Link-16. Therefore, in this paper, we analyze the effect of frequency band reduction on the performance of Link-16 waveform under partial-band noise jamming with Nakagami fading, via simulation and numerical analysis. The multi-net and anti-jamming performance of Link-16 with frequency remapping is compared with that of conventional Link-16 systems. The results show that the performance of Link-16 waveform is degraded with the reduction in frequencies. Nonetheless, Link-16 retains its jam resistance, and it can support multiple users in the same time slots.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.840-848
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• 2013

Airworthiness certification of military aircraft is a government's certification that it must have airworthiness and ability to demonstrate its requested function and performance. NATO released STANAG-4671 to establish the minimum airworthiness requirements for UAVs between 150kg and 20,000kg MTOW in 2009. Up to now, there are no clear airworthiness certification criteria and guideline for small UAV which is less than 150kg. STANAG-4671 is used for military UAV airworthiness certification in Korea as Other Airworthiness Certification Criteria. However, since STANAG-4671 requires the same Target Level of Safety without regard to MTOW, excessive Target Level of Safety or design requirements could be applied to relatively small-medium UAV. In this paper, classification and criteria of airworthiness certification for military UAV were investigated and a Target Level of Safety was analyzed based on MTOW using ground victim criteria.

• Journal of the Korean Geographical Society
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• v.43 no.5
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• pp.701-714
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• 2008

This study examines the prevailing synoptic-scale mechanisms favorable for long-lived summer Persistent Positive Temperature Anomalies (PPTAs) as well as winter PPTAs in the United States. Such long-lived PPTAs usually occur in the south-central region of the United States in summer, but in the southwestern part of the United States in winter. Composite analyses of surface and pressure level data demonstrate that the formation of both winter and summer PPTAs is closely related to the movement of subtropical high pressure systems in the Pacific Ocean and Atlantic Ocean, respectively. The occurrence of long-lived summer PPTAs usually coincides with an extremely stable atmospheric condition caused by persistent blocking by mid- to upper-tropospheric anticyclones. Significant surface forcing is also easily identified through relatively high Bowen ratios at the surface. Warm air advection is, however, weak and appears to be an insignificant element in the formation of long-lived summer PPTAs. On the other hand, synergistic warming effects associated with adiabatic heating under an anticyclonic blocking system as well as significant warm air advection characterize the favorable synoptic environments for long-lived winter PPTAs. However, the impact of surface forcing mechanisms on winter PPTAs is insignificant.

• Journal of the Korean earth science society
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• v.21 no.4
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• pp.488-501
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• 2000

'The Voyage of the Beagle' , one of the best record of scientific travels ever made, written by Charles Darwin (1809-82), the greatest naturalist ever born, is reviewed in the viewpoint of the Earth Sciences. Various observations and interpretations on the Earth Sciences are told in the Voyage. First of all, Darwin understood the geological time much more longer than accepted then as well as the geological phenomena and processes such as orogeny, uplifting, subsidence, erosion, and deposition. And he also provided a perfect interpretation on the formation of coral reefs and a good theory on the evolution of organisms. Reasonable paleoenvironmental reconstructions and interpretations based on the fossils were given in the Voyage. His observations on meteorological phenomena were from the dust composed of organisms collected on the 'Beagle' in the Atlantic Ocean, to the movement of air and extreme clear dry condition experienced on the crest of the Andes, and etc. He made several observations on the general oceanography such as the discoloration of the sea, the lights on the sea surface, conchoidal provinces noted on the Galapagos Archipelago, the trees and plants found in the remotely separated islands, and etc. However relatively scarce observation was carried out on astronomy probably due to his relatively much land travelling. Most of his interpretations and suggestions are accepted in this time.

• Economic and Environmental Geology
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• v.27 no.6
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• pp.571-577
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• 1994

It has been controversial whether the United States Atlantic margin, which developed during Mesozoic separation of Africa and North America, is a volcanic or non-volcanic rifted margin. To understand its nature, the basement images of multi-channel seismic profiles off the southeastern United States continental margin have been examined. One of prominent results is the presence of seaward-dipping reflector (SDR) wedges, the most diagnostic feature of volcanic rifted margins. Two sets of SDR wedges appear to exist here; one along the basement hinge zone ('the hinge SDR wedge') and another seaward of the East Coast magnetic anomaly ('the outer SDR wedge'). Seaward of the basement hinge zone, the lower crustal high-velocity body previously known as the 7.2 km/s layer and the underlying smooth Moho configuration are also observed. Based on the comparison of these basement images with the crustal structures of the well-known volcanic rifted margin, the southeastern United States Atlantic margin can now be characterized as a typical volcanic rifted margin.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.16-23
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• 2021

Domestic and foreign manufacturers are developing VTOL UASs in various shapes in line with demand for future technologies. UASs have been developed in a shape classified as fixed/rotary wing, and verified by appropriate certification standards. However, airworthiness certification of recent VTOL UASs is strict with the absence of VTOL-specific certification standards. In this paper, criteria applicable to VTOL UAS were presented through analysis of STANAG-4671 and STANAG-4702, which are certification standards for fixed/rotary wing UAS of the North Atlantic Treaty Organization (NATO) and the Special Condition for VTOL Aircraft (SC-VTOL) of European Aviation Safety Agency (EASA). For this, the categorization criteria of general/fixed-wing/VTOL characteristics were established for each standard item and utilized for analysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.1
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• pp.129-134
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• 2021

This study used the commercial fishing data of Korean high sea bottom longline vessels in the South West Atlantic Ocean from 2013 to 2019 to identify the distribution of fishing grounds of Korean longline vessels. We estimated the CPUE of the Patagonian toothfish Dissostichus eleginoides and the changes in its stock status. The fishing grounds of Korean longline vessels were observed to concentrate on the exclusive economic zone (EEZ) boundary between Argentina, Uruguay, and Falkland owing to the high seas of 41-55 °S in the south and 49-60 °W in the west. A high intensity of fishing was seen in the middle area, which was horizontal from the 3.1 subarea. In all the three subareas, CPUEs have had the tendency to decline since 2013. Although the CPUEs in the 3.2.1-2 subareas were the highest in each subarea, there was no significant difference in each subarea (P>0.05). It is believed that the establishment of a regional fisheries organization or the strengthening of the management of FAO is necessary for the management of Southwest Atlantic fisheries and sustainable fishing, because the portion and scope of Korean longline vessels are very low in the Southwest Atlantic; however, the CPUE is estimated to have declined.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.3
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• pp.194-204
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• 2021

The research was analyzed the catch data of the five years (2016-2020) for six joint venture company tuna purse seiners in the Atlantic Ocean, with the aim of suggesting improvement measures for responsible and sustainable fishing according to changes of recommendation by International Commission for the Conservation of Atlantic Tuna (ICCAT) on the tropical tunas. In the last five years, the average catch of six tuna purse seiner gradually increased to 7,745 tons, 8,364 tons and 9,053 tons from 2016 to 2018, but decreased to 7,761 tons in 2019 and 6,214 tons in 2020. The reason for the decrease in fishing volume in 2019 and 2020 was the fluctuation of the formation of the cold water zone (22-23℃), and the total ICCAT convention area of FAD closure in January and February due to the expansion of the FAD closure area and poor free school catching during two months period, respectively. The analysis on fishing area showed that the percentage of fishing in the high sea was about 85% although the FAD closure area included the EEZ zone in coastal countries; the rise of the fishing license in coastal countries is also believed to be a factor. In order to overcome such situations and improve catching volume, it will be possible if excellent manpower is secured, school fishing is expanded, and the production of high value-added catch (purse seine special: PS).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.934-941
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• 2020

The spatial and temporal catch variations of Argentine shortfin squid Illex argentinus in the Southwest Atlantic Ocean (SWA) were analyzed using Korean squid-jigging fishery data collected through electronic reporting system (ERS) from 2016 to 2020. The ERS linked with GPS has been implemented for collecting fishing data from all Korean fishing vessels operating in international waters since November 2015. The fishing period of the Korean squid-jigging fishery in the SWA runs from early summer to autumn (December to June) in the Southern Hemisphere. The fishing ground was extended from 42°S to 48°S along the Patagonian continental shelf and slope, and the main fishing ground was formed around the Falkland Islands. The yearly catch per unit effort (CPUE) of I. argentinus fluctuated between 1.69 and 7.53 tons/day. In this study, during the fishing season, a south and westward shift on the fishing ground was observed indicating the feeding migration of the south Patagonian stock. The shift in monthly fishing centroids differed according to fishing season. The gradual southward shifts of fishing centroids were observed in the catch years (2017 and 2018), whereas unapparent shifts in fishing centroids were observed in the low catch years (2016 and 2019).