• Journal of Environmental Science International
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• v.7 no.6
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• pp.845-851
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• 1998

In order to manage the water quality from the flowing streams in Cheju Island, the characteristics of water quality was investigated from August, 1996 to May, 1997 and the pollutant loadings for future were estimated from the watershed at each stream. Comparing the mean concentrations of each water quality with the criterion of water quality in river, it was under I class except for Changgo Stream, for DO, under I class at the whole station for SS and under II class for BOD. As the pollutant loadings at each stream in 2020 is compared with those in 1996, the estimated results are as follows : 1) for BOD, 59% at Donghong Stream, 24% at Yeonoe Stream, 44% at Ohngpo Stream and 57% at Changgo Stream. 2) for T-N, 91% at Donghong Stream, 76% at Yeonoe Stream, 63% at Ohngpo Stream and 89% at Changgo Stream. 3) for T-P, 69% at Donghong Stream, 42% at Yeonoe Stream, 45% at Ohngpo Stream and 73% at Changgo Stream. The point source loadings discharged through combined sewer could be treated at sewage treatment plant. However, the expected slow decreasing rate of BOD, T-N, and T-P loadings is due to the part of untreated nonpoint source loadings. Nonpoint source loading overflow typically occurs when the flow of stormwater combined with sewage exceeds the capacity of the interceptor sewers. Since most of the sewers used in Cheju Island are the combined sewers, the combined overflow sewage is bypassed into the receiving water area after a rainstorm. Therefore, a means to control nonpoint source loadings should be considered for the river and marine water quality management.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.2
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• pp.95-99
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• 2001

Soybean [Glycine max (L.) Merr.) is known to produce the highest total digestible mutrients (TDN) yield among summer grain legumes in Jeju area but little is known about the effects of cultural practices on forage yield and quality. A determinate soybean cv. Baegunkong was planted on 5 June, 20 June, and 3 July and grown at four plant densities (30, 50, 70 and 90 plants $m^{-2}$ in 1998 in Jeju to evaluate the effects of planting date and plant density on the yield and quality of soybean forage. Days to flowering decreased from 47 to 38 days, average plant height from 61 to 51cm and main stem diameter from 6.31 to 5.00mm as planting was delayed from 5 June to 3 July. Average plant height quadratically increased from 45 to 62cm as plant density increased from 30 to 90 plants $m^{-2}$. Planting date did not affect the average dry matter, crude protein, and TDN yields. The average dry matter and TDN yields displayed a quadratic response to plant density and the optimum plant density for both dry matter and TDN yields was estimated about 60 plants $m^{-2}$. Plant density had no effect on crude protein yield. Planting date did not significantly influence forage quality. The crude protein content was not significantly influenced by plant density. Increasing plant density slightly increased acid detergent fiber content but slightly decreased TDN content.

• Korean Journal of Environmental Agriculture
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• v.11 no.1
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• pp.26-40
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• 1992

Cheju Island formed by Quarternary volcanism provides highly permeable hydrogeological environment. To meet the increasing demand of water in the island, many groundwater wells have been developed. The environmental isotopes(oxygen-18, deuterium, tritium) and chemical analysis of water samples from the eastern part of the island were carried out to ascertain whether groundwater in the eastern part of the island was contaminated by sea water. The result of tritium analysis indicated fast infiltration of meteoric water into underground and rapid mixing process between rain water and groundwater. The results of oxygen-18 and deuterium analysis demonstrated that most of the wells in the eastern part of the island were influenced by sea water intrusion. Chemical analysis of water samples revealed that most groundwater in study area were classified into Na-Cl type and showed high chloride/bicarbonate ratios. Sea water intrusion in the northeastern part of the island has proceeded at least 3 km within the coastaline, and in the south eastern part about 700m.

• Korean Journal of Pharmacognosy
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• v.26 no.2
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• pp.116-121
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• 1995

To seek for a stable supply source of taxol as an anticancer agent urgently needed for the treatment of ovarian cancer, the concentrations of taxol and cephalomannine in bark and needles of 37 yew (Taxus cuspidata S. et Z.) trees grown in 6 locations of Cheju Island were analyzed by using HPLC. A considerable variation in the content was observed in plant part and the location. The average taxol content in the needles ($220.3{\;}{\pm}{\;}56{\;}{\mu}g$ per g dry wt) was ca. 4 times hgher than that in the bark, whereas the content of cephalomannine in the needles $(353{\;}{\pm}{\;}141{\;}{\mu}g)$ was ca. 5 times higher than that in the bark. Particularly, even within Cheju Island, needles from trees grown near the coast including Sogwipo area contained much higher taxol contents than needles from trees grown at mountain locations, indicating that taxane level is affected by environmental effects. Taxol in the needles was confirmed by electrospray mass spectrometry. These results suggest that the needles of yew trees growing in Cheju Island may provide a renewable source for taxol.

• Journal of the Korean Geosynthetics Society
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• v.7 no.1
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• pp.13-21
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• 2008

To investigate the engineering properties of basalt in Cheju Island, rock samples of Pyosenri basalt, trachy-basalt and scoria were taken from Seoguipo-Si Seongsan-Eup area. The laboratory tests such as absorption test, specific gravity test, permeability test, Schmidt hammer test, elastic wave test and uniaxial compressive testwere carried out for the collected rock samples. The absorption, the specific gravity, the permeability, the elastic wave velocity and uniaxial compressive strengthwere investigated and analyzed as the results of these tests. As the result of regression analysis for the relationship between the rebound values from Schmidt hammer test and the uniaxial compressive strengths from uniaxial compressive test, especially, estimation equations were proposed using the rebound values from Schmidt hammer test. Therefore, the simple method to estimate the uniaxial compressive strength was provided.

• Journal of the Korean association of regional geographers
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• v.7 no.3
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• pp.29-43
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• 2001

This paper examined characteristics of folk houses related to climate in Cheju island using climate data, documents and field survey data. Precipitation and humidity affect characteristics of folk houses in the southern parts of the island during summer while in winter, northern parts are mainly affected by wind. Chuck-gub has been shown through all over Cheju island due to the characteristics of precipitation. Jaechangmoon exists in southern parts of the island and these parts are experienced high humidity in summer The double-row room houses, the low eaves, gentle slop roof and stone wall are distributed through Cheju island and is related to wind. The double door is common in the northern parts because of strong winter monsoon, and Yimoonkan exists in the coastal area of the northern parts. Outer wall, Pung-Che and Gorangche are affected by winter monsoon and abundant precipitation. Gorangche has shown through both the northern parts and southeastern parts. Folk houses in the southern parts are more open than in northern parts. Folk houses in the northern parts are divided into the coastal type and the piedmont type. In the southern parts, they are subdivided the eastern type and the western type by the appearance of Gorangche.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.215-225
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• 2008

In order to investigate the influence factors to compressive and tensile strength of basalt in Cheju Island, rock samples of Pyosenri basalt, trachy-basalt and scoria were taken from Seoguipo-Si Seongsan-Eup area, and a series of uniaxial compressive strength test and Brazilian test were carried out. Especially, these tests were performed in consideration of the loading speed, the moisture content in rock sample, and the anisotropy of rock strength. The uniaxial compressive strength was increased gradually as the loading speed rose. The increasing quantity of uniaxial compressive strength had a difference in each rock types. Also, the strength was decreased with increasing the moisture contents in rock sample by pore water. As the result of test considering the anisotropy of rock strength, the compressive strength in condition of failure occurred parallel to stratified layer is decreased about 12-26% more than that in condition of failure occurred inclined to stratified layer.

• Journal of the Korean Solar Energy Society
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• v.26 no.2
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• pp.61-67
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• 2006

The use of the wind energy resource is a rapidly growing area world-wide. The number of installed units is continuously increasing, and therefore, it is important to respect and to deal with the impact of wind power generation system. From the view of an electric grid utility, there is a major problem with the impact of the wind system on the voltage of the electric grid, to which a turbine is connected. In this paper, it is investigated the voltage impact and transient state analysis on distribution line, with which wind power generation system is connected. Connections of wind power system usually occur to voltage drop due to reactive power absorption and sometime result in higher than nominal voltage.

• Journal of Environmental Science International
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• v.14 no.12
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• pp.1103-1112
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• 2005

Ozone measurements made from 4 sites in Jeju Island have been analyzed, including those from two urban and two rural locales. The data were analyzed in terms of the seasonal and diurnal trends. It should be clear that the surface ozone levels in Jeju area would be relatively sensitive to the external ozone supply originated from the region of Northeast Asia. It seems to be that due to the reactions of ozone with $NO_{x}$ and CO, the average ozone level in Jeju City appears lower than that in Seogwipo City although Jeju City is the largest city in Jeju Island.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.84-90
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• 2000

The importance of Virtual Manufacturing System is increasing in the area of developing new manufacturing processes, implementing automated workcells, designing plant facility layouts and workplace ergonomics. Virtual manufacturing system is a computer system that can generate the same information about manufacturing system structure, states, and behaviors as is observed in a real manufacturing. In this research, a virtual manufacturing system for flexible manufacturing cells (VFMC), (which is a useful tool for building Computer Integrated Manufacturing (CIM), has been developed using object-oriented paradigm, and implemented with software QUEST/IGRIP. Three object models used in the system are the product model, the facility model, and the process model. The concrete behaviors of a flexible manufacturing cell are re[presented by the task-oriented description diagram, TIC. An example simulation is executed to evaluate applicability of the developed models, and to prove the potential value of virtual manufacturing paradigm.