• Journal of the Korean Solar Energy Society
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• v.32 no.2
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• pp.11-18
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• 2012

Diesel fuel is expensive because transportation to remote areas adds extra cost, and it causes air pollution by engine exhaust. Providing a feasible economical and environmental solution to diesel generators is important. A hybrid system of renewable plants and diesel generators can benefit islands or other isolated communities and increase fuel savings. Renewable energy is, however, a natural source that produces a fluctuating power output. In this paper, hybrid power system of the marado lighthouse is proposed to supply stable power in the stand-alone hybrid power system. The proposed hybrid power system consists of the diesel generator, wind turbine, photovoltaic, fuel cell, and battery bank. To decrease the carbon emissions and find the optimization, the cost analysis of hybrid system is simulated using HOMER program and the optimized hybrid power system is designed.

• Journal of architectural history
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• v.32 no.1
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• pp.35-45
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• 2023

Bongsu(Beacon Fire Station) is a facility that sends signals with fire and smoke and has been used in Korea since the Three Kingdoms period. This facility was installed to know the north and south crises. This trend continues until the Joseon Dynasty, and it has been somewhat completed in the 17th century. In previous studies, beacon fire was identified mainly from the border area to Hanyang. Based on this, it was classified into Gyeongbongsu, Yeonbyeonbongsu, and Naejibongsu. However, it is difficult to define the characteristics of beacon fire in coastal areas only with this classification. In the case of beacon fire in island areas, there was a tendency to value communication connection within the region rather than connection with the capital. As a case analysis for this, an academic review was conducted with the cases of Ganghwa Island and Jeju Island. As a result, it was confirmed that the role and character of the beacon vary depending on the defense system and the physical distance from the land, even if it has the topographical commonality of the same island.

• The Korean Journal of Malacology
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• v.17 no.1
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• pp.63-70
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• 2001

The distribution and seasonal changes of the intertidal macrobenthos community was performed on five intertidal rocky stations of Hwasoon at Jeju Islands September 1999 to August 2000. The macrobenthos was composed of six phyla, 13 classes, 24 orders, 49 families, and 97 species. The dominant species of the upper zones were Nodilittorina exigua, Notoacmea schrenckii, Liolophura japonica and Patelloida saccharina. Those of the middle zones were Monodonta labio, Chthamalus challengeri, Siphonalia japonica and Liolophura japonica. Those of the lower zones were Siphonalia sirius, Patelloida saccharina, Chthamalus challengeri, and Liolophura japonica. The community dominance indices of the upper zones were much higher than those of the middle and lower zones. Species diversity and evenness in all investigated zones were highest in station 1 and lowest in staton 3. But, species richness was highest in station 1 and lowest in station 4.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.231-240
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• 2006

This study conducts a questionnaire survey of 492 middle school students in Jeju islands about the rate of using glasses/contact lens, the place and time of visual acuity test, the period of changing the glasses, the purchase price, the mason to change the glasses, the interrelationship between wearing spectacles and residential district, etc. The results are as follows: 1. 45.33% of the object of investigation use the glasses or contact lens to correct their visual acuity. Among them, the student who wears only glasses is 93.27%, the student who wears glasses and contact lens together is 5.83%, the student who wears only contact lens is 0.90%. 2. As for the period of changing his(her) glasses, below 6 month is 20.18%, from 6 month to one year is 52.02%, from one year to two years is 20.18% and more than two years is 7.62%. 3. As for the purchase price to change his(her) glasses, below 30,000won is 13.45%, from 30,000won to 50,000won is 43.50%, from 50,000won to 70,000won is 23.77%, from 70,000won to 100,000won is 15.25% and more than 100,000won is 4.03%. 4. As for the reason of changing his(her) glasses, cause of change of visual acuity is 55.16%, by broken frame and lens is 27.35%, as want to just change his(her) spectacles is 14.80% and as the others is 2.69%. 5. As for the relative importance in purchasing glasses, the student who thinks more frame is 16.59%, the student who thinks more lens is 67% and the student who thinks both frame and lens is 58.74%. 6. As for the frist time of visual acuity test, 1 grade of elementary school is 37.2%, 3 grade of elementary school is 12.56%, 4 grade of elementary school is 11.66% and 6 grade of elementary school is 11.66%. 7. As for the place of visual acuity test to determine the Dptr. of glasses which wear now, opitican's shop is 57.85% and ophthalmic clinic is 42.15%. 8. As for the frist time of wearing the glasses or contact lens for correct his(her) visual acuity, the most of answer(21.97%) is at 6 grade of elementary school. 9. As for the reason why does not wear the glasses or contact lens though his(her) naked binocular vision is below 0.8, as does not feel any difficulty in daily life is 62.5%, as know that the more wear, the more decrease his(her) visual acuity is 15.65%, by economical circumstance is 6.24% and as not good externally is 15.63%, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.394-410
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• 2007

Anchovy spawn from the end of May to mid-October, when the water temperature is $14.8-27.2\;^{\circ}C$ and the salinity is 26.0-33.6 psu. The main spawning season is between July to August, when the water temperature is $21.7-27.2\;^{\circ}C$ and the salinity is between 26.0-32.2 psu. The main spawning grounds of anchovy are coastal areas shallower than 50 m around the islands located in the Jeju Strait. Anchovy larvae are distributed near the fronts between Chuja-do, Jangsu-do, Yeoseo-do, and the open sea rather than in the spawning grounds. Anchovy eggs and larvae density increased in accordance with the high level of $Chlorophyll-{\alpha}$ during the summer season (July-August). In terms of the suspended sediment (SS) levels along the northern coast of the Jeju Strait, high densities of anchovy eggs (12.0-18.0 mg/L) were observed, mainly in the area affected by the coastal waters of the southern sea with high SS levels, while larvae (10.0-19.0 mg/L) tended to be distributed over a wide area with high SS levels, including the open sea. In terms of the dissolved oxygen (DO) content, eggs (5.4-6.8 mg/L) were observed in coastal areas with a high DO content, while larvae (4.2-6.4 mg/L) were distributed widely in areas with a relatively low DO content, from the southern coast to the open sea.

• Journal of The Geomorphological Association of Korea
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• v.18 no.4
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• pp.79-96
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• 2011

Volcanic landforms are classified into the volcanic edifice produced through constructive processes of eruption and the crater generated by destructive processes of eruption. Both landforms are distributed around Korean Peninsula including attaching islands. However, only a few regions such as Mt. Baekdu, Jeju Island, Ulleung Island, and Chugaryeong, which are closely related with the volcanic eruption occurred during the Quaternary, could be considered as a volcanic landform. It results in categorizing the volcanic landform as an unusual topography in Korea. The study of Korean researchers on the volcanic landform were regularized in 1970s on Jeju Island, in 1980s on Ulleung Island, and in 1990s on Mt. Baekdu, respectively. Oreums and lava tubes in Jeju Island have been also examined since 1980s. Compared with other fields of geomorphology, researches as well as researchers on the volcanic landform are very few in Korea. Geomorphologists are expected to perform an active research in that the volcanic landform of Korea have diverse values.

• Structural Engineering and Mechanics
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• v.88 no.4
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• pp.323-334
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• 2023

The submerged floating tunnel (SFT) infrastructure has been regarded as an emerging technology that efficiently and safely connects land and islands. The SFT route problem is an essential part of the SFT planning and design phase, with significant impacts on the surrounding environment. This study aims to develop an optimization model considering transportation and structure factors. The SFT routing problem was optimized based on two objective functions, i.e., minimizing total travel time and cumulative strains, using NSGA-II. The proposed model was applied to the section from Mokpo to Jeju Island using road network and wave observation data. As a result of the proposed model, a Pareto optimum curve was obtained, showing a negative correlation between the total travel time and cumulative strain. Based on the inflection points on the Pareto optimum curve, four optimal SFT routes were selected and compared to identify the pros and cons. The travel time savings of the four selected alternatives were estimated to range from 9.9% to 10.5% compared to the non-implemented scenario. In terms of demand, there was a substantial shift in the number of travel and freight trips from airways to railways and roadways. Cumulative strain, calculated based on SFT distance, support structure, and wave energy, was found to be low when the route passed through small islands. The proposed model helps decision-making in the planning and design phases of SFT projects, ultimately contributing to the progress of a safe, efficient, and sustainable SFT infrastructure.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.142-150
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• 2024

Improving transportation accessibility on islands is closely related to regional development. Currently, the government is constructing Ulleung Airport as part of the 6th Airport Mid- to Long-term Development Plan. Similar to the case of Jeju Airport in 2016, severe congestion occurs at passenger terminals upon flight resumption after cancellations at airports on islands. Therefore, considering the cancellation rate at island airports is important. This study investigates the conditions leading to increased cancellation rates at Ulleung Airport, with the research results predicting frequent cancellations during the winter season. The research methodology involved examining airport construction plans, aircraft performance, airport de-icing capabilities, and also included consideration of weather conditions. Ulleung Island is a representative snowfall area, and sufficient snow removal capacity must be secured. However, the current plan's snow removal capacity is insufficient, leading to anticipated high cancellation rates. Therefore, measures to mitigate passenger inconvenience caused by increased cancellations and methods to reduce the cancellation rate are explored. With Ulleung Airport scheduled to open in 2027, there is ample time to implement supplementary measures to reduce the cancellation rate and minimize passenger inconvenience.

• Ocean and Polar Research
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• v.43 no.4
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• pp.205-217
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• 2021

A shallow channel between Jeju and Udo Islands, which is located in the northeastern Jeju Island, is influenced by storm- or typhoon-induced currents and surface waves as well as strong tidal currents. This study examines the typhoon-induced current and wave patterns in the channel, using Acoustic Doppler Current Meter (ADCP) measurements and an ocean-wave coupled modeling experiment. Three typhoons were chosen - Chaba (2016), Soulik (2018), and Lingling (2019) - to investigate the responses of currents and waves in their pathways. During the pre-typhoon periods, dominant northward flow and wave propagation were observed in the channel due to the southeasterly winds before the three typhoons. After the passage of Chaba, which passed over the eastern side of Jeju Island, the northward flow and wave propagation were totally reversed to the opposite direction, which was attributed to the strong northerly winds on the left side of the typhoon. In contrast, in the cases of Soulik and Lingling, which passed over the western side of Jeju Island, strong southerly winds on the right side of the typhoons continuously intensified the northward current and wave propagation in the channel. The model-simulated current and wave fields reasonably coincided with observational data, showing southward/northward flow and wave propagation in response to the right/left side of the typhoon pathways. Typhoon-induced downwind flows, and surface waves could enhance up to 2m/s and 3m due to the strong winds that lasted for more than 12 hours. This suggests that the flow and wave patterns in the Udo channel are highly sensitive to the pathway of typhoons and accompanying winds; thus, this may be a crucial factor with regard to the movement of seabed sediments and subsequent coastal erosion.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.187-195
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• 2017

We have studied the efficient operation of the radar and the appropriateness of the installation location, when constructing the VTS system. As the Civil-Military Complex Harbour (Kangjeong Port) is completed in 2016, we set the control area within 10 nautical miles centering on Kangjeong Port, and found out and removed the operational radar blind area of VTS system to provide safe navigation information for vessels that navigating this area. Assuming that two international cruise ships entering at the same time, we performed the radar simulation and compared the images by considering the three sites of Kangjeong Port, Miaksan and Seoguipo Port. Simulation results for a single radar installed at Kangjung Port indicate that the blind area was largely affected by two large cruise ships and the surrounding islands. The blind area due to Kogunsan was considerably large when installed in Miaksan, but the blind area due to the influences of Beomseom, Moonseom and Seopseom was negligibly large. It seems that additional radar installation is necessary as a complementary solution to solve this blind area. When two radars were installed at Miaksan and Kangjeong Port, the residual blind area due to the Seopseom was $0.25km^2$ at 0.1~0.33 nautical miles in the southeast direction from Seopseom. In addition, the remaining blind area with two cruise ships mutually influenced was $0.18km^2$, which did not occur with a single cruise ship.