• Fisheries and Aquatic Sciences
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• v.1 no.1
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• pp.113-121
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• 1998

A relationship between sea level variations in the Korea Strait (the western and the eastern channels) and the Tokara Strait in the Kuroshio region is examined using daily-mean sea level data from 1966 to 1986. The seasonal variation of the sea level difference (SLD) between Izuhara and Pusan (the western channel) is most periodic: the positive anomalies appear from summer to autumn, and the negative anomalies from winter to spring year to year, whereas SLDs neither between Hakata and Izuhara (the eastern channel) nor between Naze and Nishinoomote (the Tokara Strait) show such a periodic variation. Much similarity has been found between SLDs in the eastern channel and the Tokara Strait, and in particular they were closely correlated in a special event of the Kuroshio region, such as a large meander of the Kuroshio. This paper shows that the periodic seasonal variation of the SLDs in the western channel should be less related to the Kuroshio region. This result also implies that the variation of SLD in the western channel is largely influenced by local factors, such as the bottom cold water in the western channel in summer, rather than from the Kuroshio region.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.6
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• pp.437-449
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• 1991

Time series of barometrically adjusted sea level at Pusan, Izuhara and Hakada are analyzed to study the fluctuations of the Tsushima Current through the Korea Strait. Variability of sea levels and their differences is divided into two parts with respect to the frequency of 0.01 or 0.02 cycles per day(cpd) At lower frequency, both of sea levels and sea level difference(SLD) are coherent and in phase to each other. Pusan has smaller seasonal variations in sea level than other two stations because the effects of geostrophic current and prevailing wind have a negative influence on the seasonal thermosteric contribution to sea level change. Low frequency variability of SLD thus of the Tsushima Current is much greater in the western channel. For higher frequency parts, SLD in the eastern channel has larger variability and is not coherent with that of the western channel. Sea levels at Pusan and Izuhara are $180^{\circ}$ out of phase with SLD in the western and eastern channel respectively, whereas the Hakada level is in phase. This result indicates that eastern channel has a normal response to the along-channel winds and cross-channel geostrophy because Izuhara faces the eastern channel.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.69-74
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• 2016

Bathymetric changes were studied in the southern sea off the Jinwoo-do Island, which is one of the deltaic barrier islands surrounding the Nakddong river estuary. In this study, 16 bathymetry data sets were obtained from June 2006 to April 2015. Two narrow channels, the one lying between Jinwoo-do and Shinja-do, and the other one lying between Nulcha-do and Jinwoo-do extended into the eastern and western parts of the study area, respectively. The eastern extension of the channel contained a passage of mixed estuarine waters of seawater and river water discharged from the Nakdong river barrier and the west Nakdong River. The western channel connected the Nakdong River estuary with the Busan New Port via a connecting pier. Total volumetric changes of sediments in study area and discharge flow of the Nakdong river barrier were analyzed. Bottom topographical changes occurred mainly in the eastern extension of the channel. These changes were initially characterized by gradual erosion or deposition followed by rapid restoration. The total volume of sediment gradually increased from June 2006 to March 2013, but experienced a sudden decrease in October 2013 because of typhoon Danas. Few fluctuations were observed from October 2013 to April 2015. Analysis of the cross-sectional bathymetry of the north-south direction showed that the deepest point of the eastern channel moved 100-130 m westward and 200 m northward between June 2006 and April 2015.

• International Journal of Contents
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• v.8 no.2
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• pp.19-22
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• 2012

New and handoff calls control mechanisms are the key point to wireless cellular networks. In this paper, we present an adaptive algorithm for dynamic channel allocation scheme with guard channels and also with handoff calls waiting queue ensuring that handoff calls take priority over new calls. Our goal is to find better tradeoff between handoffs and new calls blocking probabilities in order to achieve more efficient channel utilization. Simpy is a Python based discrete event simulation system. We use Simpy to build our simulation models to get analytical data.

• Journal of Contemporary Eastern Asia
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• v.19 no.1
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• pp.123-143
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• 2020

This study examines the interplay between the reactions of YouTube users and North Korean propaganda. Interesting enough, the study has noticed changes in the strict media environment under young leader Kim. Messages delivered by the communist regime to the outside world appeared to resemble those of 'normal' countries. Although North Korean YouTube was led mainly by the account operator, visitors from different nations do comment on the channel, which suggests the possibility of building international communities for propaganda purposes. Overall, the study observed a sparsely connected social network among ordinary commenters. However, the operator did not exercise tight control over peer-to-peer communication but merely answered questions and tried to facilitate mass participation. In contrast to the many news clips, the documentary content on North Korea's YouTube channel did not explicitly advocate for North Korea's current political positions.

• Journal of the Korean Institute of Navigation
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• v.8 no.1
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• pp.49-70
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• 1984

Spatial and temporal variations of hydrography and currents are investigated in the Southeastern Sea of Korea during October 1982. The distribution of the water mass of high salinity (>34.40${\textperthousand}$) and low dissolved oxygen concentration (<5.0ml/l) indicates that the Tsushima current flows northward as it passes the Western Channel of the Korea Strait. The cold water (<$6.0^{\circ}c$) with low salinity (<$34.20{\textperthousand}$) and high dissolved oxygen concentration (>6.0ml/l) reaches the bottom of the western channel of the Korea Strait after flowing southward leaning against the slope rather than following the deepest part of the Channel. Repeated sections in the Korea Strait show a remarkable change of hydrographic structure over a period of 4 days ; both warn and cold waters are intensified, particularly in the eastern part of the strait toward the Tsushima Island.

• 한국해양학회지
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• v.22 no.4
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• pp.217-227
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• 1987

The heat budget of the south eastern region (33$^{\circ}$N-36$^{\circ}$N, 120$^{\circ}$E-125$^{\circ}$E) of the Yellow Sea was calculated by using the meteorological and oceanographical data. The sensibly heat, the evaporation heat and the long wave back radiation have annual variation and increases toward south with strong gradient along the Cheju channel in winter, but they all show tendency to decrease toward eastern coastal area in summer. The area is roughly divided into three parts, the central part, the coastal part and the southern part, according to the characteristics ovariation and distribution patterns of the exchanged heats. The amplitude of the annual variation of total heat exchange in the southern part is very large compare to those of the central and coastal part. The studied area is appeared to be heated mainly by the evaporation heat and the sensoble heat, based on the results of this study.

• Economic and Environmental Geology
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• v.33 no.3
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• pp.239-246
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• 2000

The 3.5kHz sub-bottom profiling was carried out over both Gwangyang Bay and the Yeo Sound . High -resolution digital images of uppermost sediment layers are obtained from the field data which were originally recorded in analog mode. Most prominent feature along the acoustic profiles is the chaotic reflections which imply the presence of shallow gas within the silty sediments. In the western part of Gwangyang Bay, the gas-charged sediments are assoicated with the acoustic turbidity of the blanket type. Across the Seomjin Delta in the eastern part of Gwangyang Bay, the gas-charged seismic facies are observed just beneath the sea bottom. In the western Yeoul Sound , the gassy seiments occur widely , whereas it is rare in the eastern counterpart with the <30-m-deep channel. We postulate that this gas was biogenetically produced within the organic-rich deposits.

• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.257-263
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• 2016

Mombasa is the principle port of Kenya, serving inland countries in Eastern and central Africa. Mombasa port has undergone a massive infrastructure upgrade and dredging works with an expectation that more vessels and large post Panamax ships will be able to enter Mombasa port. Therefore, it is vital to carry out a marine traffic risk assessment in order to quantify the degree of navigation safety needed in the Mombasa approach channel and also to evaluate the navigation risk imposed on transit traffic by local ferry traffic. In this paper, a marine traffic risk assessment is carried out using the IWRAP mk2, Environmental Stress (ES) model, and the PARK model. Risk assessment results show that Likoni area has an unacceptable stress/risk ranking at 20.7% by the ES model and 38.89% by the PARK model. The IWRAP mk2 model shows that the crossing area has the highest risk of crossing collision and the area at the entrance to the inner channel has a high risk of grounding. The conclusions derived from this study will provide the basis for proposing the most effective countermeasure to improve navigation safety in the Mombasa approach channel.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.81-84
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• 2016

Mombasa is the principle port of Kenya, serving hinter countries in Eastern and central Africa. Mombasa port has undergone a massive infrastructure upgrade and dredging works with an expectation that more vessels and large post Panamax ships will be able to call at Mombasa port. Therefore, it is vital to carry out a marine traffic risk assessment so as to quantify the degree of navigation safety on Mombasa approach channel and also to evaluate navigation risk imposed on transit traffic by local ferry traffic. In this paper marine traffic risk assessment is carried out using IWRAP mk2, Environmental Stress model, and PARK model. Risk assessment results show that Likoni area has unacceptable stress/ risk ranking at 20.7% on ES model and 38.89% by PARK model. IWRAP mk2 model shows that crossing area has the highest risk of crossing collision and the area at the entrance to inner channel has a high risk of grounding. The conclusions derived from this study will provide the basis for proposing the most effective countermeasure so as to improve navigation safety in Mombasa approach channel.