• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.759-770
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• 1997

The general flow patterns in the Cheju Strait have been investicated by analyzing the current observations measured in $1986\~1989$ by current meter mooring in 3 north-south sections in the Cheju Strait and at 4 observation points around Cheju Harbour, and measured in $1981\~1987$ by drogue tracking. 1. In the Cheju Strait, there are eastward or northeastward residual currents, which implies that sea waters flow into through the whole western section and flow out through the whole eastern section in the Cheju Strait. The velocity of residual currents are $5.2\~30\;cm/sec$ in 10 m layer and $1.3\~24cm/sec$ in mid-bottom layer. Generally, the flow is strong along the deepest through and the northern part, and weak in the shallow areas near Chuja Islands and Bogil Island. 2. In the western entrance of the Cheju Strait, the observed mean residual velocity is 6.93 cm/sec and the volume transport is 0.384 Sv. There are a big discrepancy between the observed residual currents and the geostrophic currents. 3. Near the frontal areas northwest to Chuja Islands, warm and saline offshore waters, flow northward about 5 miles into the southern coastal areas of the Korean Peninsula in flood, and flow back rather eastward or southeastward than southward in ebb. So, warm and saline waters flow along coastal areas, being mixed with coastal waters. As a result, the northwestern area of Chuja Islands plays a role of the entrance of influx of warm and saline offshore water to the southwestern coastal areas of the Korean Peninsula. It should be stressed that this flow pattern is not due to the residual flows, but to the temporal (tidal) flows.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.3
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• pp.132-139
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• 1997

CTD and current observation were taken to investigate the structure of the cold water in the Western Channel of the Korea Strait in October 1993. Thickness of the cold water in the deep trough of the strait changes from 20 m to 70 m according to the water depth. Thermocline between the Tsushima Warm Water and the cold water deepens from north to south with 0.00057 in slope. Temporal variation of the thickness appears to be related with the tidal current. The maximum variation is 20 m for 48 hours. Mean velocity of the cold water for 72 hours is 17 cm/sec southward. A simple model was used to understand dynamically the southward flow of the cold water and the return flow at the upper part in the lower layer. Calculated maximum southward flow and eddy viscosity coefficient are 7 cm/sec and 0.038 $m^2$/sec respectively in the model. Southward transport is $0.032$\times$10^6㎥/sec$ at the northern part in the trough and decreases from north to south due to the presence of the return flow. Southward transport increases with the increase in the upper layer transport but is not affected by the density of the upper layer or the interface slope.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.2
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• pp.211-225
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• 1998

A field experiment was carried out for fishes on entering time to a set-net, swimming speed, current speed and direction at the Dongbok-Ri coast on Cheju Island. The results of the experiment are as follows : 1. The observation results from 07:00 to 18:00 showed that coral fish, flying fish, horse mackerel, drub mackerel and striped mullet enter the set-net from 07:00 to 14:00 mainly. 2. From the result of analyzing relationships between entering time and tide, coral fish and horse mackerel tend to enter the set-net on turn of tidal current and ebb respectively. 3. The leaving rates of coral fish, flying fish, drub mackerel, and striped mullet from the set-net were 13%, 45%, 50%, and 100%, respectively but all horse mackerel remained in the net. 4. The swimming speed of coral fish, flying fish, horse mackerel and drub mackerel are 5~25cm/sec, 20~50cm/sec, 15~45cm/sec and 10~30cm/sec, respectively and their dominant speeds are 10~15cm/sec(55%), 30~35cm/sec(30%), 30~40cm/sec(60%), and 15~20cm/sec(60%), respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.1
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• pp.13-29
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• 2021

A 3-D hydrodynamic model is applied in the Han River Estuary system, Gyeonggi Bay, to understand the mechanisms of salt transport. The model run is conducted for 245 days (January 20 to September 20, 2020), including dry and wet seasons. The reproducibility of the model about variation of current velocity and salinity is validated by comparing model results with observation data. The salt transport (FS) is calculated for the northern and southern part of Yeomha channel where salt exchange is active. To analyze the mechanisms of salt transport, FS is decomposed into three components, i.e. advective salt transport derived from river flow (QfS0), diffusive salt transport due to lateral and vertical shear velocity (FE), and tidal oscillatory salt transport due to phase lag between current velocity and salinity (FT). According to the monthly average salt transport, the salt in both dry and wet seasons enters through the southern channel of Ganghwa-do by FT. On the other hand, the salt exits through the eastern channel of Yeongjong-do by QfS0. The salt at Han River Estuary enters towards the upper Han River by FT in dry season, whereas that exits to the open sea by QfS0 in wet season. As a result, mechanisms of salt transport in the Han River Estuary depend on the interaction between QfS0 causing transport to open sea and FT causing transport to the upper Han River.

• Tuberculosis and Respiratory Diseases
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• v.40 no.6
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• pp.683-693
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• 1993

Background: During movement the major inputs to nervous system come from firstly the muscle and joint to maintain posture and motion and secondly the chemoreceptors and baroreceptors to adjust the cardiovascular and respiratory function. Their complex relationships are generally studied for many years but the direct relation between the joint and respiratory system is not studied thoroughly until now. So this experiment was performed to determine whether the natural movement of knee joint can cause the enhancement of respiratory function by observation of the changes of respiratory rate, phrenic nerve activity and inspiratory neuron activity during the stimulation of knee joint in cat anesthetized with $\alpha$-chloralose. Method: Twenty six male adult cats were used and the extracelluar recording using bipolar platinum electrode and carbon filament electrode was done to record the changes in the activities of phrenic nerve and inspiratory neuron movement of knee joint, injection of chemicals into the joint cavity and electrical stimulation of articular nerve were done. Results: The 60 Hz. could not but 120 Hz. flexion-extension movement of knee joint increased respiratory rate(R.R.), tidal neural activity(TNA) and minute neural activity(MNA). Intra-articular injection of lactate could not increase R.R. but significantly increase TNA and MNA which represented the enhanced respiratory function. Injection of potassium chloride showed similar effects with the case of lactate but the duration of effect was shorter. The electrical stimulation of medial articular nerve with IV strength which could activate only group I and II afferents showed increased TNA and MNA during stimulation but 20 V stimulation which could activate all the afferents increased all the respiratory parameters. The changes of inspiratory neuron activity by knee joint stimulation was similar to that of phrenic nerve. Conclusion: The respiratory center could be directly stimulated by the activation of group I and II articular afferents and it seemed that the magnitude of the respiratory center enhancement is proportional to the amount of sensory information from the knee joint. These facts might suggest that the respiratory function could be enhanced even by the normal movement of knee joint.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.629-636
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• 1999

Gonadal development, gametogenesis, reproductive cycle, egg-diameter and composition, condition factor, and the first sexual maturity of the clam, Potamocorbula amurensis were investigated by histological observation. Samples were collected monthly from the tidal flat of Moonpo, Puan-gun, Chollabuk-do, west coast of Korea from November 1996 to October 1997. P. amurensis is dioecious and oviparous. The gonads were composed of a number of gametogenic follicles. The oogonia and fully ripe oocytes were $9\~12\mu$m and $50\~60\mu$m in diameter, respectively. Each of the spermatogenic follicle formed stratified layers composed of spermatogonia, spermatocytes spermatids, and spermatozoa in groups on the follicular wall. The reproductive cycle of P. amurensis could be classified into five successive stages: early active, late active, ripe, partially spawned, and recovery. Spawning occurred twice a year from May to July and from September to October, the main spawning seasons also appeared twice a year between May and June, and in October when the water temperatures reached above $18^{\circ}C$. The monthly changes in the condition factor were closely related with the reproductive cycle. Minimum size for the sexual maturation of female and male were 8.1 mm in shell length. There were two patterns for the gametogenesis: 1. After spawning, the undischarged ripe oocytes and spermatozoa in the follicles were degenerated and absorbed, but in part, the existing follicles were not contracted significantly and then they took part in new gametogenesis within one or two months (especially, in summer). 2. After spawning, each follicle was contracted, thereafter gametogenesis again occurred in newly formed follicles.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.1
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• pp.1-12
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• 2021

To investigate the effect of freshwater discharge on the seawater circulation in the semi-closed harbor, a 3-D hydrodynamic model was applied to the International Ferry Terminal (IFT). The model run is conducted for 45 days (from May 15 to June 30, 2020), and the reproducibility of the model for time-spatial variability of current velocity and salinity was verified by comparison with model results and observation data. There are two sources of freshwater towards inside of the IFT: Han River and water reservoir located in the eastern part of IFT. In residual current velocity results, the two-layer circulation (the seaward flow near surface and the landward flow near bottom)derived from the horizontal salinity gradient in only considering the discharge from a Han River is more developed than that considering both the Han River and water reservoir. This suggests that the impact of freshwater from the reservoir is greater in the IFT areas than that from a Han River. Additionally, the two-layer circulation is stronger in the IFT located in southern part than Incheon South Port located in northern part. This process is formed by the interaction between tidal current propagating into the port and freshwater discharge from a water reservoir, and flow with a low salinity (near 0 psu) is delivered into the IFT. This low salinity distribution reinforces the horizontal stratification in front of the IFT, and maintains a two-layer circulation. Therefore, local sources of freshwater input are considered to estimate for mass transport process associated with the seawater circulation within the harbor and It is necessary to perform a numerical model according to the real-time freshwater flow rate discharged.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.3
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• pp.220-237
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• 2021

Since the functional importance of marine phytoplankton was firstly advocated from early 1880s massive data on the species composition and abundance were produced by classical microscopic observation and the advanced auto-imaging technologies. Recently, pigment composition resulted from direct chemical analysis of phytoplankton samples or indirect remote sensing could be used for the group-specific quantification, which leads us to more diversified data production methods and for more improved spatiotemporal accessibilities to the target data-gathering points. In quite a few cases of many long-term marine ecosystem monitoring programs the phytoplankton species composition and abundance was included as a basic monitoring item. The phytoplankton data could be utilized as a crucial evidence for the long-term change in phytoplankton community structure and ecological functioning at the monitoring stations. Usability of the phytoplankton data sometimes is restricted by the differences in data producers throughout the whole monitoring period. Methods for sample treatments, analyses, and species identification of the phytoplankton species could be inconsistent among the different data producers and the monitoring years. In-depth study to determine the precise quantitative values of the phytoplankton species composition and abundance might be begun by Victor Hensen in late 1880s. International discussion on the quality assurance of the marine phytoplankton data began in 1969 by the SCOR Working Group 33 of ICSU. Final report of the Working group in 1974 (UNESCO Technical Papers in Marine Science 18) was later revised and published as the UNESCO Monographs on oceanographic methodology 6. The BEQUALM project, the former body of IPI (International Phytoplankton Intercomparison) for marine phytoplankton data QA/QC under ISO standard, was initiated in late 1990. The IPI is promoting international collaboration for all the participating countries to apply the QA/QC standard established from the 20 years long experience and practices. In Korea, however, such a QA/QC standard for marine phytoplankton species composition and abundance data is not well established by law, whereas that for marine chemical data from measurements and analysis has been already set up and managed. The first priority might be to establish a QA/QC standard system for species composition and abundance data of marine phytoplankton, then to be extended to other functional groups at the higher consumer level of marine food webs.

• Journal of the Korean earth science society
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• v.45 no.3
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• pp.203-213
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• 2024

This study aimed to investigate the seasonal patterns of multiple bar formation in summer and flattening in winter on the macrotidal Sinduri beach in Taean, and to understand the processes their formation and subsequent flattening. Beach profiling has been conducted regularly over the last four years using a VRS-GPS system. Surface sediment samples were collected seasonally along the transectline, and grain size analyses were performed. Tidal current data were acquired using a TIDOS current observation system during both winter and summer. The Sinduri macrotidal beach consists of two geomorphic units: an upper high-gradient beach face and a lower gentler sloped intertidal zone. High berms and beach cusps did not develop on this beach face. The approximately 400-m-wide intertidal zone comprises distinct 2-5 lines of multiple bars. Mean grain sizes of sand bars range from 2.0 to 2.75 phi, corresponding to fine sands. Mean sizes show shoreward coarsening trend. Regular beach-profiling survey revealed that the summer profile has a multi-barred morphology with a maximum of five bar lines, whereas, the winter profile has a non-barred, flat morphology. The non-barred winter profiles likely result from flattening by scour-and-fill processes during winter. The growth of multiple bars in summer is interpreted to be formed by a break-point mechanism associated with moderate waves and the translation of tide levels, rather than the standing wave hypothesis, which is stationary at high tide. The break-point hypothesis for multi-bars is supported by the presence of the largest bar at mean sea-level, shorter bar spacing toward the shore, irregular bar spacing, strong asymmetry of bars, and the 10-30 m shoreward migration of multi-bars.