• Journal of Fisheries and Marine Sciences Education
• /
• v.29 no.3
• /
• pp.627-635
• /
• 2017

Sea level rise caused by climate change has become a global issue. Sea level rise seems to be an important factor of the research for coastal areas as it affects topography and vegetation of coasts and especially for the plan of coastal wetlands restoration which needs to be carried out for a long term, it has to be considered sufficiently. The coastal wetlands in Korea was damaged by the land reclamation project but recent concerns on the restoration have increased as its value is evaluated highly. Suncheon Bay had also reclaimed from wetlands to rice field once however this site is very active for restoration nowadays. This study estimated an effect according to sea level rise by 2100, reappearing the none dike condition of Suncheon Bay so that it can be taken account of a future plan of wetland restoration. The Sea Level Affecting Marshes Model(SLAMM) was selected as predicting model. The input data such as DEM(Digital Elevation Model), slope, wetlands category, sea level rise senario, tidal range and accretion rate was applied for the simulation. The results showed a decrease in tidal flat, an increase in sea area and a change of the rice field to transitional salt marsh consistently by 2100. These results of this study could be used as baseline data in the future plan of ecological restoration in Suncheon Bay.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.28 no.1
• /
• pp.13-26
• /
• 2016

Sea water level variations are generally influenced by a variety of factors such as tides, meteorological forces, water temperature, salinity, wave, and topography, etc. Among non-tidal conditions, atmospheric pressure is one of the major factors causing water level changes. In the East Sea, due to small tidal range which is opposite to large tidal range of the Yellow Sea, it is difficult to predict water level changes using a numerical model, which consider tidal forcing only. This study focuses on the effects of atmospheric pressure variations on sea level predictions along the eastern coast of Korea. Telemac-2D model is simulated with the Inverted Barometer Effect(IBE), and then its results are analyzed. In comparison between observed data and predictions, the correlation of prediction with IBE and tide is better than that of tide-only case. Therefore, IBE is strongly suggested to be considered for the numerical simulations of sea level changes in the East Sea.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.40 no.5
• /
• pp.43-51
• /
• 1998

In design and management of sea0dikes, engineers need to study various transient seepage conditions through dikes not only for the sea water infiltration into dikes due to cyclic rises of sea water level also for the seepage flow out from dikes toward the sea due to cyclic drawdown of sea water level. Characteristics of seepage flow toward the sea from dikes are more complicated than as known and remained unclearly. The case of such seepage flow may be explained by figuring out seepage characteristics in filter as a part of sea-dikes. Filters in most sea-dikes in Korea are inevitably placed with reversely inclined shape due to field construction conditions. Most computer programs for seepage analysis based on the various numerical methods give practically acceptable results, but for the case of reversely inclined section of filters any verification to apply them might be needed. In this study, large scaled model tests were executed to verify and understand seepage flow through earth-filled sea-dikes. The results from numerical analysis and model tests show some remarkable differences in pore pressure distribution under cyclic changes of see level, and some of the results need to be considered in design and construction practices with further study.

• Journal of Climate Change Research
• /
• v.9 no.4
• /
• pp.369-376
• /
• 2018

Korea is surrounded by the West Sea, the South Sea, and the East Sea. There are various points at which large and small rivers flow into the sea, and areas where these rivers meet the coast are vulnerable to disasters. Thus, it is necessary to study disaster prevention techniques based on coastal characteristics and the pattern of disasters. In this study, we analyzed the risk factors of disaster districts analyzed in comprehensive plans for the reduction of damage to coastal cities from storms and floods. As a result of standardization, four factors (tide level, intensive rainfall & typhoon, wave, and tsunami) were identified. Intensive rainfall & typhoon occurred along the West Sea, the South Sea, and the East Sea coast. Factors that should be considered to influence disasters are tide level for the West Sea, tsunami and tide level for the South Sea, and wave in the East Sea. In addition, disaster prevention techniques to address these factors are presented, focusing on domestic and overseas cases.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.10a
• /
• pp.339-342
• /
• 2003

Sea level variations and sea surface circulations inthe Korean seas were observed by Topex/Poseidon altimeter data from 1993 through 1997. In sea level variations, the West and South Sea showed relatively high variations with comparison to the East Sea. Then, the northern and southern area in the West Sea showed the range of 20-30cm and 18-24cm, and the northern west of Jeju island and the southern west of Tsushima island in the South Sea showed the range of 15-20cm and 10-15cm, respectively. High variations in the West Sea was results to the inflow in sea surface of Yellow Sea Warm Current (YSWC) and bottom topography. Sea level variations in the South Sea was due to two branch currents (Jeju Warm Current and East Korea Warm Current) originated from Kuroshio Current (KC). In sea surface circulations, there existed remarkably three eddies circulations in the East Sea that are mainly connected with North Korea Cold Current (NKCC), East Korea Warm Current (EKWC) and Tushima Warm Current (TWC). Their eddies are caused basically to the influence of currents in sea surface circulations; Cyclone (0.03 cm/sec) in the Wonsan bay on shore with NKCC, and anticyclone (0.06 cm/sec) in the southwestern area of Ulleung island with EKWC, and cyclone (0.01 cm/set) in the northeastern area of Tushima island with TWC, respectively.

• Journal of the korean society of oceanography
• /
• v.33 no.4
• /
• pp.212-218
• /
• 1998

Three different outflow boundary conditions are considered in modeling the East Sea circulation. The first one is that of the conventional constant volume transport (CT). The second one is the Orlanski radiation boundary condition (OR). The third one is that of the constant sea level just outside the outflow boundary (SL). In the third condition, the outflow current is set to be driven by the sea level differences across the outflow open-boundary lines, based on the recent knowledge that the Tsushima Current is driven by the sea level differences across the inflow and outflow boundaries. In case of OR it takes too much time to reach the steady state, resulting in a large increase of Tsushima Current Water in the basin and low level of kinetic energy. Both CT and SL reach the steady state in a relatively short time. However, SL is more recommendable, because it is based on physical background and generates less numerical noises than CT.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.699-705
• /
• 2013

This paper presents vibration testing, control, and finite element analysis of a piping system, which is subjected to the changes in fluid levels. Nuclear power plants typically employ a cooling system that uses sea water. These systems are subjected to dynamic characteristic changes caused by sea-level variations, which introduces failures of cooling system components. Therefore in this study, analytical and experimental studies were performed to understand the effect of sea-level changes on the dynamic characteristics of piping systems. It was shown that, as the sea-level increases, pipe's natural frequencies decreases in relation to its mode shape. A 1/14 scale model was also built to compare the results obtained by the analytical study. A good agreement between experiment and analytical studies were observed. Finally, an on-line resonant frequency identification system was proposed and developed, which utilizes piezoelectric transducers as sensors and actuators, in order to avoid catastrophic failure of piping systems.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.4 no.2
• /
• pp.93-100
• /
• 1999

Analyzing the tide data taken at Kunsan inner and Outer ports, non-tidal and mean sea level and harmonic constants of major constituents are investigated to examine the effects of the dyke gate operation on the sea level change in Keum River estuary. Non-tidal and annual mean sea levels decrease at Kunsan Inner and Outer ports after the dyke gate operation, especially showing an abrupt drop of non-tidal sea level at Kunsan Inner port. This non-tidal sea level drop results in the mean sea level gradient change between the inner and outer port, which can be mainly explained in terms of the decrease of river discharge from the dyke. Amplitudes of the $M_2$ and $S_2$ tides at the Inner port increase after the dyke gate operation, showing an abrupt jump, and phases of both tides slightly decrease. Amplitude and phase of the $K_1$ and $O_1$ tides show slight changes after the dyke gate operation. This significant change of semi diurnal tide amplitude is believed as a result of superposition of incident tidal wave and reflected tidal wave from the dyke.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.27 no.2
• /
• pp.350-358
• /
• 1998

The antimutagenic and anticancer activities of glycoprotein(GP) and chondroitin sulfate(CS) from sea cucumbers were studied using Ames mutagenicity test and human cancer cells culture test. The GP's inhibitory effect toward aflatoxin B1(AFB1) and 3, 2'-dimethyl-4-amino-biphenyl(DMAB) increased with the higher added concentrations up to 5% level(w/w) regardless fractionation methods. The GP from sea cucumbers through DEAE-cellulose column chromatography showed an inhibitory effect ranged from 84 to 98%, and the maximum antimutagenicities resulted in red sea cucumber with 98% (AFB1) and 95% (DMAB). But 5% level of CS from various sea cucumbers had an inhibitory effect toward those both indirect mutagens ranged from 79% to 85%. However, in case of direct mutagens(N-methyl-N'-nitro-N-nitrosoguanidine, MNNG and 4-nitroquinoline-1-oxide, 4-NQO), the GP's inhibitory effect was 55∼78% and the CS had a low inhibitory effect(58∼70%) at the added level of 5%. The GP from sea cucumbers exhibited the strong inhibitory effects with 89∼95% and 82∼92% on the growth of HT-29 human crcinoma cells and AZ-521 human gastric cancer cells (at 5% level).

• 한국해양학회지
• /
• v.29 no.1
• /
• pp.42-49
• /
• 1994

A series of radiocarbon dating from intertidal, subtidal, and inner continental shelf deposits investigated along the west coast of Korea as well as from its offshore sea floor (namely, the eastern Yellow Sea Basin) how (1) the Holocene sea level rise, i.e., the ecstatic sea-level history during the oxygen isotope stage 1, and (2) pre-Holocene sea-level fluctuations during the oxygen isotope stages 2 and 3. Marine geophysical investigations in the Yellow Sea reported a possible development of desert and loses deposits due to dieselization under the cold and dry climate during the Last Glacial Maximum. The Kanweoldo deposit overlain unconformably by the Holocene intertidal deposits, which is mainly exposed along the tidal channels and intertidal flats in the Cheonsu Bay, the west coast of Korea, shows the characteristic cryogenic structure (cryoturbation). Such cryoturbation structure of the Kanweoldo deposit appears to indicate the cold and dry climate under the ecstatic sea-level paleoshoreline standing before and after of the pre-Holocene interstitial period (about 30000 y BP is suggested and its shoreline curve is constructed.