• 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 Geomorphological Association of Korea
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• v.15 no.2
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• pp.55-65
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• 2008

In order to examine the runoff characteristics of scoria cones in Jeju Island, hydrological observations were conducted in the experimental basin (5.1 ha) of Eoseungsaeng-oreum which has been predominantly covered with Carpinus laxiflora and Quercus serrata. Although runoff has continuously occurred during the observed period, the baseflow gradually increased from April and decreased from October. The peak flow approximately corresponded to every rainfall events except for the rainfall events which has slight total precipitation and no previous precipitation. The experimental basin shows flash runoff response and short lag time; the mean lag time is 35.8 minutes. Although the runoff ratio of quick flow is proportional to total precipitation, the increasing rate is low and the maximum runoff ratio is 24.7%. In addition, the runoff ratio is less than 1% in 68.3% of the rainfall events, suggesting that the portion of quick flow to total precipitation is low. The rainfall events with relatively long event time demonstrated a secondary peak generated by translatory flow. The runoff characteristics seem to be related to local impermeable beds in the experimental basin.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.576-578
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• 2010

현재 제주도의 주 수입원이 관광과 수자원이 되어감에 따라 용천수의 중요성이 부각되고 있다. 그러나 용천수의 관리에 문제가 발생하고 있어 이번 논문에서는 용천수 주변지역 원형 복원을 위한 송이 활용기법을 주제로 삼고 있으며 이번 실험을 통해 용천수 관리의 방안을 제시해 보고자 한다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.340-343
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• 2005

광촉매 효율을 높이기 위해 WO$_{3}$를 첨가하여 제주에 산재해 있는 스코리아를 지지체로 하여 TiO$_{2}$ 및 WO$_{3}$/TiO$_{2}$ 광촉매를 이용하여 humic acid를 분해시킬 경우 반응영향인자에 따른 분해효율을 구한 결과 다음과 같은 결론을 얻었다. Humic acid의 분해시 Ca$^{2+}$를 첨가하였을 때가 첨가하지 않았을 때 보다 효율이 증대한 것은 이온강도가 증가하여 반발력을 감소하여 분해효율이 증대된 것이다. HCO$_{3}\;^-$를 첨가시 분해효율이 감소하는 것은 HCO$_{3}\;^-$이온이 OH radical scavenger로 작용했기 때문이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.352-355
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• 2003

비자성이며 비전도성의 물리적 성질을 갖는 자연산 퀄쯔(quartz)와 용암석 스코리아를 대상으로 마그네타이징 처리를 하여 분석하였다. 마그네타이징 처리를 위하여 강력한 기계화학적 분쇄 반응을 시켰으며, 분쇄 반응시 알코올계의 솔벤트를 반응 용매로 사용하였다. 퀄쯔와 스코리아의 마그네타이징 처리에서 비교적 비중이 큰 퀄쯔의 경우와 비중이 작은 스코리아의 경우에도 분쇄된 분말이 물에 뜨는 것을 확인할 수 있으며, 친유성으로 기름에 대한 흡착 성질이 우수함을 확인하였다. 자연산 퀄쯔와 함께 스코리아를 바탕물질로 하여 기계-화학적 반응 기술로 고 분산성 흡착반응에 의한 고분자 물잘 생성을 유도하여 나노복합체를 제조하였다. 반응의 처리조건과 적용과정에 따라서 기계-화학적 반응을 통하여 얻어진 물질은 자기적 성질과 유전체 및 전기적 성질을 동시에 나타낸다. 부착성 융합 복합물질의 특징을 고려하여 시그니토마그네틱스(Segneto-magnetics)로 분류되는 합성분말은 특히 유류성분에 대하여 높은 흡착성을 가지며, 강한 자기적 성질을 띄는 10-50 nm 두께의 하나 또는 그 이상의 이질적 융합 화합물 층이 석영이나 수정체의 표면에 합성되어 특유의 자기, 전기적 성질을 나타낸다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1057-1062
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• 2008

In order to investigate a strength anisotrophy 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. The strengths were 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.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.5 no.4
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• pp.272-280
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• 1976

A natural ventilating type store was designed for the economic and effective storage of citrus fruits in Jejudo. The material used for the wall is scoria, widely distributed in Jejudo and known for high strength and insulation. Design condition was chosen for the period till March of a year and the dry bulb temperature was taken from TAC $5\%$ base. The temperature of the store can be maintained below the limiting temperature of $8^{\circ}C$ for the time length of $7\frac{1}{2}$ hours under the condition of the atmospheric temp, $15.3^{\circ}C$ and the solar insolation. The limiting temperature can he recovered to the initial temperature $(7^{\circ}C)$ by the natural ventilation for 8 hours in the night.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.251-255
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• 2008

This study was carried out in 2002 to determine the usefulness of Jeju scoria for a component of a growth medium and optimum planting density of 'Dejima' seed potatoes (Solanum tuberosum L.) grown in a wick hydroponic system. The minitubers ($7.0{\pm}0.2\;g$) produced in an aeroponics system were planted at five planting densities (3 to 15 tubers/box; 19 to $95\;tubers/m^2$) in polystyrene boxes (51 cm long $\times$ 31 cm wide $\times$ 20 cm high) containing two media (perlite + peatmoss and Jeju scoria + peatmoss 1:2, v/v mixtures). There were no significant interactions between medium and planting density for the growth and tuber yield traits. Shoot growth and the number of tubers per plant were not significantly affected by the media. However, tuber yield was higher in the perlite + peatmoss mixture than in the Jeju scoria + peatmoss mixture. The percentage of underdeveloped plants ranged from 8.3 to 14.7% at four lower planting densities (3 to 12 tubers/ box), and was 25.8% at the highest planting density (15 tubers/box). As planting density was increased from 3 to 15 tubers per box, seed potato (${\geq}5\;g$ tuber) number increased from 101 to 269 and yield from 6.3 to $11.6\;kg/m^2$. These results indicate that the perlite + peatmoss mixture might be more suitable for seed potato production in the wick hydroponic system, and considering the percentage of underdeveloped plants and tuber yield, optimum planting density would be 56 to $76\;tubers/m^2$ in the system depending on availability of seed potatoes.

• The Journal of Engineering Geology
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• v.19 no.2
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• pp.153-163
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• 2009

In this study, a series of triaxial tests on Jeju basalt were carried out and then rock strength parameters were estimated by the Mohr-Coulomb failure criterion and the Hoek-Brown failure criterion using the test results. The characteristics of both failure criterions were investigated through comparing the estimated rock strength parameters. As the result of the Mohr-Coulomb criterion, the cohesions and the internal friction angles are determined as 5.35 MPa and $50.25^{\circ}$ of Pyoseonri basalt, 16.99 MPa and $60.66^{\circ}$ of Trachy-basalt, and 2.33 MPa and $37.05^{\circ}$ of Scoria, respectively. The cohesions and internal friction angles were estimated by the Hoek-Brown failure criterion in the basis of the results of regression analysis. The cohesions and the internal friction angles are determined as 4.77 MPa and $52.47^{\circ}$ of Pyoseonri basalt, 14.69 MPa and $60.70^{\circ}$ of Trachy-basalt, and 2.22 MPa and $47.60^{\circ}$ of Scoria, respectively. As the result of comparison between the Mohr-Coulomb failure criterion and the failure envelope predicted by the Hoek-Brown criterion, the cohesion estimated by the Hoek-Brown criterion is usually lower than that obtained from the Mohr-Coulomb criterion, whereas the friction angle estimated by the Hoek-Brown criterion is higher than that obtained from the Mohr-Coulomb criterion.

• Economic and Environmental Geology
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• v.53 no.5
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• pp.553-564
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• 2020

Transition between explosive and effusive eruption in Ulleung Island is observed in the Nari Scoria Deposits and Albong Trachyandesite (lava dome) origined by dome-building eruption and may be related to factors such as magma influx, ascent rate and degassing. However, the interpretation of them has not been resolved yet because the interaction between these factors is not complex but also the resulting behaviour during eruption is unpredictable. This paper focuses on the explosive and effusive activity perceived during building the Albong lava dome in Nari caldera. Samples were collected along with time from the scoria deposits and lava dome, linked to eruption stage and style of activity. Textures of groundmass feldspar microlites from these samples are quantitatively analyzed, including measurements of areal number density, mean microlite size, crystal aspect ratio, groundmass crystallinity and crystal size. The microlite textures show that shallow pre- and syn-eruptive magmatic processes acted to govern the changing behaviour during the eruption. Transition between explosive and effusive eruption was driven by the dynamics of magma ascent in the conduit, with degassing and crystallisation acting via feedback mechanisms, resulting in a cycle of effusive and explosive eruption.