• International Journal of High-Rise Buildings
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• v.1 no.2
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• pp.131-148
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• 2012

This paper attempts to summarize recent debates on tall buildings. It first explains the driving forces of constructing tall buildings including population increase, rural-to-urban migration, demographic change, agglomeration, and human aspiration. Next, it discusses disadvantages and challenging factors that are frequently raised in making a case against tall buildings including economics, environmental factors, historic context, public safety, and psychological issues. The paper concludes by affirming that tall buildings will persist in the $21^{st}$ century due to strong commitment to urban sustainability and significant population increase worldwide.

• Ocean Science Journal
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• v.40 no.1
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• pp.11-16
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• 2005

Correction factors based on the catch ratios of egg and larval densities in the southern waters of Korea were estimated for anchovy Engraulis japonica. This was undertaken in order to adjust ichthyoplankton data from different sampling methods, gear types and time. Samples were collected during ichthyop1ankton surveys in Korean waters from 1983 to 1994. The ratios for egg densities obtained in vertical tows with a NORPAC net (ring $\Phi$, 45 cm) compared to those obtained in oblique tows with a KOB net (ring $\Phi$, 80 cm) were 0.86 (CV = 0.65), 1.22 (CV = 0.36), and 0.93 (CV = 0.42) for early, middle, and later developmental stages, respectively. The ratios for larval densities for vertical and oblique tows varied depending on size. For yolk-sac and small larvae (< 4 mm), the ratios were 3.08 (CV = 0.45) and 1.98 (CV = 1.34), while those of 4-6 mm, 6-8 mm, and 8-10 mm larvae were 0.44 (CV = 1.31), 0.45 (CV = 1.70), and 0.56 (CV = 2.50), respectively. Ratios of day/night densities for larvae of 4-10 mm lengths were lower (0.01-0.06) in offshore catches than values obtained in coastal areas (0.440.46) and similar values (0.16-0.04) for vertical and oblique tows. Our results indicated that vertical towing is more efficient for sampling early life stages (from eggs to larvae less than 4 mm long), while oblique towing is more efficient for larvae longer than 4 mm due to depth preferences for each developmental stage (e.g., changes in egg buoyancy and vertical migration oflarvae).

• Journal of the Korean Geotechnical Society
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• v.35 no.8
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• pp.5-15
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• 2019

This study was conducted to propose a reasonable requirement regulation of cutoff barriers composed of bottom layer and vertical barrier of offshore landfill for the prevention of contaminant leakage. The bottom layer was composed of impermeable clay layer; vertical walls were composed of double walls; outer wall was composed of steel sheet pile which registed against outer force; cutoff vertical barrier took the role of inner wall. Seepage-advection-dispersion numerical analysis was conducted using SEEP/W and CTRAN/W programs under steady and unsteady flows. The results showed that the values calculated under steady flow showed higher migration of pollutant than those of unsteady flow. The values calculated under steady flow are more valid from a design point of view. Under steady flow and the bottom clay layer and when the vertical barrier are homogeneous and completely well installed, respectively, the minimum required cutoff regulations for hydraulic conductivity, thickness, and embedded depth of the bottom clay layer and vertical barrier were suggested.

• Fisheries and Aquatic Sciences
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• v.27 no.2
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• pp.76-86
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• 2024

The bio-logging method could be a valuable approach to studying the underwater movement of marine fish. We investigated the horizontal and vertical movement patterns of two yellowtails Seriola quinqueradiata weighing 8.7 kg and 9.5 kg with a popup satellite archival tag from October 2020 to January 2021 in the East Sea of Korea. Our results showed that a yellowtail migrated northward in October and November, and then shifted southward in mid-December. The average swimming depth and temperature of the fish monitored over 82 days were 24.9 ± 9.3 m (average ± SD) and 16.5 ± 1.9℃, respectively, and the total traveled distance was 1,172.4 km. The fish swam significantly deeper during the daytime (33.70 ± 14.80 m) than at nighttime (20.65 ± 8.44 m) from November to December (p < 0.05). These results suggest that the horizontal migratory route of yellowtails in accordance with the East Korea Warm Current which is the main branch of Tsushima Warm Current in the fall and early winter seasons, and showed significant diel vertical movement patterns from November to December.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.381-386
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• 2010

We have cultured the bluefin tuna in Yokjido, Tongyeong with floating cage which was vulnerable to harmful dinoflagellate, Cochiodinium polykrikoides. This study inspected a vertical migration of phytoplankton and Chl-a for reasonable sinking depth in floating cage. Furthermore, we analyzed the fluctuation of the phytoplankton including harmful dinoflagellates occurring in Yokgido for 6 years. Total cell density showed a significant monthly variation and the flora was predominated with diatoms. Gymnodinium sp. occurred 19 times, the greatest number of occurrence in all kinds of dinoflagellates during summer. In particular, the total number of occurrence at C. polykrikoides was 8, and harmful dinoflagellates such as Karenia brevis/Fibrcapsa japonica occurred. The relationship between Chl-a concentration/total cell number and sunset/sunrise was significant and reasonable sinking depth in floating cage was found to be at least 3m from the water surface, which was associated with massive fish kills caused by C. polykrikoides.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.87-94
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• 1983

The successful oil storage in the underground cavern is dependent on how to keep the water-tightness around the cavern by the groundwater. If the water-tightness is not secured, gas bubles will leak out and oil migrate to the adjacent empty cavern. An electrical analogy method was employed in studying the influences of the position of horizontal and vertical water curtains, the head of water curtain and the intervals of the cavern spacings and boreholes on the gas leakage and the oil migration into the adjacent empty cavern. The result shows that if the cavern spacing is narrow, the vertical water curtain should be established and if the cavern spacing is more than twice the cavern height, its establishment is not necessary. All the detailed factors required to prevent the oil migration are shown on graphs.

• 한국해양학회지
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• v.21 no.3
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• pp.146-155
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• 1986

Zooplankton samples of upper 50m layer in May, 1985 and of various depth intervals depending on thermal structure in October, 1985 were analyzed. Standing stock represents mean of 538inds/㎥ in spring and 267 inds/㎥ and 508inds/㎥ of whole column mean and surface layer in fall, respectively. A total of 55 and 104taxa is identified in each season and accumulated data list at least 123 species inhabiting in the study area. Copepods dominate in the zooplankton community, followed by protozoans and appendicularians in both seasons. In surface layer, distribution of subtropical species and standing stock seems to illuminate the effects of the Tsushima Current and the North Korean Cold Watermass in cold season, whereas only standing stock shows discernable variation in warm season. Concerning whole water column, depth of permanent thermocline bottom, at about 120m in fall 1985, plays significant role as a barrier to the distribution of mesopelagic cold water species. Serial sampling in October, 1985 does not reveal any perceivable diel vertical migration, which is considered to confirm the earlier suggest that owing to the lack of true abyssal species zooplankton biomass of deeper gayer is very poor, so that diel vertical migration of the East Sea is weak.

• Korean journal of applied entomology
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• v.38 no.1
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• pp.47-52
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• 1999

Effects of organic matter content in soil on activity. vertical migration. and persistence of two nernaticides. carbofuran and ethoprophos. to root-knot nematode, Mrloitlog!~iei ~lcognita.w ere investigated. As the organic matter content increased. activity of the nernaticides tended to be reduced. Both nematicides exhibited control values of more than 80'k' to M. iix.o,yilit~iln 0-2 cm depth soil layer from the surface. regi~rdless of organic matter content in soil. In 2-4 cm depth soil layer. however. the control value of the neniaticides varied with the organic niatter content in soil. The control value of carbofuran in the soil layer was ranged from I0 to 30'2,. depending on the soil organic niatter content. In contrast. ethoprophos had no control value against M. i/ic.o,ytlitcr in the \oil layer, except that the nematicide had a control value of 30% when the organic matter content was 0.4%. Furthermore. ethoprophos had no effect on controlling M. i/ic.o,gtiitrr in soil layer of below 4cm. whereas control values of carbofuran were approximately from 5 to 20% in all test soils having different organic matter contents. These results indicate that carbofuran has more vertical migration effect than ethoprophos. Persistence of the two neniaticides was also decreased with increasing soil organic matter content. Half life of carbofuran was 2-3 weeks in soil containing 0.4% organic matter, whereas it was found to be I week in soils containning 0.8 ant1 1.6% of organic matter. On the other hand. activity of ethoprophos was reduced to half in 3-3 weeks and in 2-3 weeks in soil containing 0.4 and 0.8%, and 1.6%) of organic matter, respectively. However, no activity of the both nernaticides was found in soil containing 3.2% of organic matter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.355-361
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• 2007

A giant jellyfish (Nemopilema nomurai), which is presumed developing in the East China Sea, is recently one of major issues in the Northeast Asia region due to its fatal damage to the fishery. The biomass estimates have generally been conducted by trawl sampling and sighting survey methods. The biological research is also needed to clarify such environmental origin or diurnal migration patterns. While trawl sampling or sighting survey methods are effective to investigate its density estimates in its distributed community of near bottom or surface, they have a problem in investigation on the vertical distribution of jellyfishes. In this case, an echo sounding detection would have an advantage to survey it more extensively and effectively. This trial was conducted to observe the vertical distribution of giant jellyfish, where thermocline strongly formed, during mooring at each station of the East China Sea and southern coastal area using acoustical and optical methods. By the results, they were observed to exit and move at the water column under the thermocline using the optical camera and echo sounder system, and the information was analyzed to find out the acoustical sound scattering characteristics relatives to 120kHz frequency. These results can be utilized effectively to estimate the vertical distribution and biomass of Giant jellyfish with comparing results from trawl sampling and sighting survey methods, hereafter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.2
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• pp.221-227
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• 2023

The vertical distribution of snow crab Chionoecetes spp. larvae in the East Sea were investigated in April 2021 using the Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS). The water temperature ranged from 0.86 to 17.2℃, and salinity from 34.0 to 34.7 psu. Zoea I and II occurred range from 29 to 1,982 inds.10³ m^-3 at 10 stations, and range from 4 to 11 inds.10³ m^-3 at 3 stations, separately. Therefore, Zoea I occurred in wider area and higher density than Zoea II at all stations. In the vertical distribution of larvae, all zoeal stages were mainly distributed in the 30-40 m strata, and the larvae showed nocturnal vertical migration similar to that of most zooplankton. Zoea I appeared in the range from 13.7 to 15.8℃ and occurred at the highest density of 1982 inds.10³ m^-3 at 14℃. And Zoea II appeared range from 13.4 to 14.5℃ and occurred in the highest density of 11 inds.10³ m^-3 at 13.4℃. In conclusion, the early larval stage (zoea I) occurred at a higher range of sea surface temperature than later larval stage (zoea II).