• ALGAE
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• v.30 no.1
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• pp.59-66
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• 2015

The growth and hole formation of Ulva australis were examined at seven coastal areas of Korea between July and August, 2013. Animal species and weight growing on the Ulva fronds were estimated at Haseom, Pohang, and Woedo. The effects of wave exposure on the morphological features and residential animals of Ulva fronds were investigated at wave-exposed and sheltered sites of Seongsan on October 19, 2013. U. australis had different frond areas ($82-665cm^2$), hole areas ($2.5-6.3cm^2$), and hole numbers (9.8-41.3 holes) at the seven sites. Within $0.1m^2$ of Ulva frond, hole areas ranged from 0.37 to $5.94cm^2$, and between 4.9 and 36.2 holes were observed. Fourteen residential animal species were observed at the three evaluated sites, 75.0 (Haseom) to 408.7 individuals $100g^{-1}$ Ulva (Pohang) per site. The dominant residential species at each site differed with Amphithoe sp. at Haseom, Monodonta spp. at Pohang, and Pagurus sp. at Woedo. The growth (frond area, wet weight) and hole number of Ulva fronds, and the number of residential animals were significantly greater in samples collected from the sheltered shore than the wave-exposed shore of Seongsan. The present results showed U. australis grew well at sheltered shores and had more holes on the fronds due to abundance of residential animals. The dominant residential animals (crabs, gammaridea, and snails) were similar in the Ulva populations of sheltered and wave-exposed shores, but greater species diversity was observed at the exposed shore (18 species ver. 11 species). In conclusion, U. australis is a keystone species providing habitat to various invertebrates and frond holes are positively correlated to the number of residential animals.

• Korean Journal of Food Science and Technology
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• v.4 no.4
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• pp.285-290
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• 1972

Oranges (Citrus unshiu var.) from local orchards at Seogwi, Daejeong, Hanrim, Cheju and Seongsan where are in the southern, southwestern, northwestern, northern and eastern parts of Cheju island respectively were stored in a semi-underground room and an air-circulating refrigerated store. To compare the storage qualities between the growing districts, changes in freshness, acidity and sugar content of oranges were investigated during storage. 1) Oranges from Seogwi and Cheju districts showed remarkably lower Percentage of rot fruits with no relation of storage temperature than those of Hanrim, Daejeong and Seongsan. 2) Browning of oil gland was severe on oranges of northern and southern districts while it was little developed in case of the other districts. 3) Water soluble total sugar content was gradually increased and titratable acidity and reducing sugar content of pulp tissues was decreased during storage. 4) Oranges from the western part showed the higher ratio of sugar content to acidity and better taste as compared with the east oranges.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.439-446
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• 2023

Mangroves are distributed in intertidal zones of coastal environments or estuarine margins, playing a critical role in the global carbon cycle. However, understanding of the carbon cycle role of mangrove associates in the Republic of Korea is still limited. This research measured soil respiration and leaf gas exchange in three habitats of Hibiscus hamabo(Gimnyeong, Seongsan, and Wimi) and analyzed the impacts on sites and months. Soil respiration was measured once a month from June to October 2022 and leaf gas exchange was measured monthly from June to September 2022. Soil respiration in August(5.7±0.8 μmol CO₂ m^-2 s^-1) was significantly higher than that in other months (p<0.001) and soil respiration increased as air temperature increased (p<0.001). In Seongsan, net photosynthesis in July(9.0±0.9μmol m^-2 s^-1) was significantly higher than that in other months (p<0.001). Net photosynthesis increased as stomatal conductance and transpiration rate increased during the entire period(p<0.001). Furthermore, a weak positive linear relationship was observed between soil respiration and net photosynthesis (r²=0.12; p<0.01). The results indicated that soil respiration was influenced not only by air temperature and season but also by net photosynthesis. This study is expected to provide basic information on the carbon dynamics of mangrove associates.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.247-257
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• 2016

To predict annual energy production (AEP) accurately in the wind farm where located in Seongsan, Jeju Island, Equivalent wind speed (EQ) which can consider vertical wind shear well than Hub height wind speed (HB) is calculated. AEP is produced by CFD model WindSim from National wind resource map. EQ shows a tendency to be underestimated about 2.7% (0.21 m/s) than HB. The difference becomes to be large at nighttime when wind shear is large. EQ can be also affected by atmospheric stability so that is classified by wind shear exponent (${\alpha}$). AEP is increased by 11% when atmosphere becomes to be stabilized (${\alpha}$ > 0.2) than it is convective (${\alpha}$ < 0.1). However, it is found that extreme wind shear (${\alpha}$ > 0.3) is hazardous for power generation. This results represent that AEP calculated by EQ can provide improved accuracy to short-term wind power forecast and wind resource assessment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.129-134
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• 1992

This paper presents the relation between risk and safety factor for optimal storm sewer design in urban area. For reliability analysis of the storm sewer, uncertainty of the various parameters of constituting equation determining the capacity and load of storm" sewer is considered and risk is determined. In this study, reliability analysis method is applied to Seongsan detention reservoir basin which area is $381,000m^2$ Darcy-Weisbach equation is used for determining capacity of the storm sewer and rational formula is used for determining load. Safety factor representing ratio of the sewer capacity and design flowrate is calculated, and relating with risk. Then risk and safety factor with return period is obtained and it is used for optimal design of storm sewer.

• Hwankyungkyoyuk
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• v.25 no.2
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• pp.161-179
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• 2012

The aims of this study are to investigate the environmental perception of elementary school students through picture drawing and associated words about environment, and analyze whether there are differences in the environmental perception according to living places and grades. The drawing of 230 students are analysed and categorized into the criteria. The results are as follows: a number of students realized as images associated with natural environment for words related to environment. In the pictures of the 'positive environment', expression frequencies of natural environment and living things were higher than ones of artificial environment and non-living things. On the other hand, there were many pictures expressed as pollutions of waste, air and water in the pictures of the 'negative environment'. Comparison of environmental perception between rural and urban students showed a significant difference all in the two criteria. There was, however, no difference in the environmental perception between grades. Therefore, it is suggested that student's minds about the sentimental situation can be studied and they can be guided in positive directions to lead their future life in environment-friendly education rather than pollution education.

• School Mathematics
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• v.13 no.4
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• pp.563-580
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• 2011

This study is centered on the application of metaphor theory to math education from the cognitive-linguistic view. This study, at first, introduced what metaphor is, and looked into it from the math-educational view. Furthermore, on the basis of that, this study examined the significance of metaphor to math education, and dealt with its relevance to math education, focusing on the functions that metaphor has. This study says that metaphor has the function of explanation, elaboration and representation. In addition, this study examplifies that using metaphor can be an effective math learning strategy for mathematical concept explanation, mathematical connection and mathematical representation learning.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.137-143
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• 2014

An investigation on lightning characteristics and damage to wind turbines was performed on Jeju and Gangwon regions. The lightning data from January 2010 to September 2013 detected by IMPACT ESP were collected and analyzed in detail. Hangyeong and Seongsan wind farms of Jeju province and Taebaek, Changjuk, Taegisan and Gangwon wind farms of Gangwon province were selected for this study. Lightning rates and lightning damage events at the six wind farms were compared with each other. Lightning maps for the two regions were drawn using lightning frequency data. As a result, lightning frequency of Gangwon region was higher than that of Jeju region, while lightning strength of Gangwon was weaker than that of Jeju. Lightning rates were assessed to be good for all of the six wind farms. No lightning damage to wind turbines occurred at the two wind farms of Jeju, while some lightning damage to wind turbines took place at the four wind farms of Gangwon.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1180-1181
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• 2008

불확실한 출력 변화 특성을 갖는 풍력발전 설비가 제주지역에 크게 증가하고 있다. 이러한 증가는 풍력발전 설비가 연계된 선로에 전력의 품질을 떨어뜨릴 수 있는 가능성이 커진다. 성산 풍력발전단지는 2008년도 현재 기준으로 총 67[MW]의 풍력발전 용량이 180[KVA]의 설비용량을 갖는 성산변전소 22.9[kV] 배전선로에 접속된다. 이로 인하여 풍력발전의 출력변화에 따른 성산변전소의 배전선로에 나타나는 전력품질의 변화를 사전에 예측하고 검토할 필요가 있다. 이에 본 논문에서는 전력전자와 전력계통의 여러 가지 모델을 쉽게 해석 할 수 있는 PSCAD/EMTDC 프로그램을 이용하여 제주지역의 전 계통을 모델링하고 제주계통 부하용량이 320[MW] 기저 부하시 급격한 풍력발전 출력변화에 따른 성산변전소의 배전선로에 나타나는 전압과 주파수 변화에 대한 전력품질 특성을 시뮬레이션 결과를 통하여 나타내고자 한다.

• Journal of the Korean Chemical Society
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• v.8 no.4
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• pp.169-178
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• 1964

Various ceramic raw minerals occuring in Korea were investigated laying emphasis on mineralogical identifications of them. Data of chemical analysis, differential thermal analysis, powder patterns of x-ray diffraction and particle size distribution were obtained for the present study. Hadong kaolin was confirmed as halloysite, and it was found that main constituent of some commercial pyrophyllite is mineralogically not pyrophyllite; Seongsan and Ockmaesan pyrophyllite consist of mainly kaolin group mineral, Tongnae pyrophyllite consists of muscovite, however Milyang and Jindo pyrophyllite is mineralogically pyrophyllite.