• Korean Journal of Plant Resources
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• v.25 no.1
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• pp.123-131
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• 2012

This study analyzed on the characteristics of community structure, species composition, population conditions and annual mean radial growth of Taxus cuspidata in the subalpine zone of the Seoraksan, Deokyusan, and Hallasan National Parks. Deokyusan and Hallasan sites had three layers of stratification structure without tree layer in it and four layer in Seoraksan site. The major dominant species in the order of importance value were as follows: T. cuspidata, Acer tschonoskii var. rubripes, Quercus mongolica, Abies koreana and Sorbus commixta. The trees (> 5 cm DBH) of T. cuspidata were extremely high with 986.0 individuals/ha at the Hallasan site. Average DBH class were 42.0 cm at the Hallasan site and mainly showed large class. The populations of seedlings and saplings with 357.3 individuals/ha, and juvenile with 128.6 individuals/ha, as a succession tree, were found to be the highest at the Hallasan site. In the size frequency distribution, the populations of T. cuspidata in Mt. Halla site showed a reverse J-shaped curve and it was estimated that T. cuspidata community of this site might be maintained continuously as a stable state like present state. Annual mean radial growth of T. cuspidata populations at Seoraksan, Deokyusan, and Hallasan sites showed up as 1.27 mm/year, 0.93 mm/year and 0.89 mm/year respectively.

• Journal of Life Science
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• v.24 no.9
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• pp.1012-1018
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• 2014

Sasa quelpaertensis Nakai (Korean name, Jeju-Joritdae) is one of the most abundant plants on Mt. Halla, Jeju Island, and it has long been used in traditional medicines. Recent studies have reported it as possessing various beneficial functions, including anti-inflammatory, anti-diabetic, anti-hypertension, anti-gastritis, anti-oxidant, and anti-cancer effects. However, the molecular mechanisms of its anti-cancer activity have not been clearly elucidated. In this study, we investigated the anti-cancer effects and mechanism of S. quelpaertensis on human colon cancer HT-29 cells. Cell growth inhibition by S. quelpaertensis was determined by MTT assay. Apoptosis was performed by DNA fragmentation, flow cytometry with propidium iodide staining (PI), and reverse transcription-polymerase chain reaction (RT-PCR) to confirm the anti-apoptotic factors, such as inhibitor of apoptosis (IAP) family members. $NO^{\bullet}$ production was determined by Griess assay. S. quelpaertensis treatment resulted in the time- and dose-dependent inhibition of the cell viability of HT-29 cells by inducing apoptosis, as evidenced by the accumulation of the sub-G1 cell population stained by PI, as well as the ladder-like DNA fragmentation in a dose-dependent manner. S. quelpaertensis-inducing apoptosis was accompanied by the induction of S cell cycle arrests, increasing $NO^{\bullet}$ concentrations, and the down-regulation of IAPs, including X-chromosome-linked IAP (XIAP), cellular IAP-1 (cIAP-1), cIAP-2, and survivin. Taken together, these findings have important implications for future clinical developments of S. quelpaertensis in colon cancer treatment.

• Journal of Environmental Science International
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• v.16 no.11
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• pp.1257-1269
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• 2007

This study was performed to get more knowledge on the flora and their life form spectrum in the Hallasan Natural Reserve. The vascular plants include 83 species 35 genera 12 families of pteridophytes, 5 varieties 5 species 3 families of gymnosperm, 100 taxa in 2 varieties 98 species 58 genera 8 families of monocotyledon and 362 taxa in 3 forma 10 varieties 349 species 186 genera 65 families of dicotyledon in Hallasan Natural Reserve. The total of vascular plants is 550 taxa in 3 forma 11 varieties 536 species 284 genera 88 families. Among these, 204 species in total including 19 species of pteridophytes, 2 species of conifers, 45 species of monocotyledon and 138 species of dicotyledon are found only in the Hallasan Natural Reserve. The pteridophyte-quotient is 4.52 and floristic richness is 1.94. In the analysis of life form spectrum, there are 190 species (34.5%) of hemicryptophytes and 122 species (22.2%) of geophytes so that two life forms take large portions, 312 species (56.7%) of the vegetation in Hallasan Natural Reserve. Megaphanerophytes and microphanerophytes take 14.5% including 80 species followed by 83 species (15.1%) of nanophanerophytes, 42 species (7.6%) of chamaephytes, 29 species (5.3%) of therophytes, 24 species (4.4%) of hydrophytes and 18 species (3.3%) of epiphytes. According to the life form spectrum hemicryptophytes dominated high portions, which suggests Hallasan Natural Reserve has hemicryptophytic climate and similar to middle parts in the Korean Peninsular. The differences, however, were noticed by that it has more chamaephytes and less therophytes than that of the Peninsular and partially shows the characteristics of artic or subalpine climate.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.1
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• pp.30-36
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• 2001

Schisandra nigra Max. has been cultivated far a medical use as well as food. It is an endemic species which has a unique habitat at the altitude of 600-1,400 m in Cheju island. In this study, three natural populations of S. nigra were investigated by using of starch-gel electrophoresis to determine the extent and distribution of genetic diversity. Except 2 monomorphic locus (Mdh-2 and Pgi-1), 4 of the 6 isozyme locus (Idh, Mdh-2, Mnr, and Pgi-2), verified from 4 isozymes, revealed polymorphism in the three populations of S. nigra. The mean number of allele per locus was 1.7 and the percentages of polymorphism loci were 38.9% at 95% level and 50% at 99% level respectively. The observed and estimated heterozygosities were 0.141 and 0.147 respectively. Although plants which were in the face of crisis and distributed in the restricted area, have been known to the very low degree of genetic variation, S. nigra showed higher genetic variation than others. Genetic variation was mostly allocated within population and individuals than that among populations. The result of Wright's F analysis estimates of $F_{IT}$ and $F_{IT}$ showed that S. nigra population revealed Hardy-Weinberg steady state.

• Journal of The Geomorphological Association of Korea
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• v.21 no.4
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• pp.149-164
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• 2014

The representative landscapes in Jeju Island called as Ten sceneries of Yeongju originates with Ten sceneries of Tamra which were organized in the late seventeenth century by Jeju governor Lee Iktae. In order to compose ten representative sceneries in Jeju Island, he selected four strongholds such as Jocheon, Byeolbang, Seogwi and Myeongwol and six places of scenic beauty such as Seongsan, Baekrokdam, Yeonggok, Cheonjiyeon, Sanbang and Chwibyeongdam, and made a painting named as Ten sceneries of Tamra. Since the scenes of strongholds also exhibit a lot of geomorphic landscapes, the painting could be considered a collection of representative landforms in Jeju Island. The painting depicts several types of landform such as volcano, crater, river, waterfall, pool, wetland, cavern, tor and rocky coast. The volcanic edifice appears most frequently in the painting, reflecting the particular emotion of Jeju people on Mt. Halla and oreums. However, another volcanic landform, a lava tube, was not highly evaluated due to its negative images. Three famous waterfalls in Jeju Island were included in Ten sceneries of Tamra, and it suggests that they are essentially outstanding landforms, and besides, there are few sites related with fresh water in Jeju Island. The ten sceneries were entirely organized in spite of the limitation of selecting places at that time. The landscape images of Jeju Island, which had been shared as collective representation by Jeju people, were firstly externalized through Lee Iktae's painting, and have long been passed down and established a kind of scenic stereotype.

• Journal of the Korea Convergence Society
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• v.12 no.6
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• pp.9-16
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• 2021

In the past, there have been various studies on predicting the stock market by machine learning techniques using stock price data and financial big data. As stock index ETFs that can be traded through HTS and MTS are created, research on predicting stock indices has recently attracted attention. In this paper, machine learning models for KOSPI's up and down predictions are implemented separately. These models are optimized through a grid search of their control parameters. In addition, a hybrid machine learning model that combines individual models is proposed to improve the precision and increase the ETF trading return. The performance of the predictiion models is evaluated by the accuracy and the precision that determines the ETF trading return. The accuracy and precision of the hybrid up prediction model are 72.1 % and 63.8 %, and those of the down prediction model are 79.8% and 64.3%. The precision of the hybrid down prediction model is improved by at least 14.3 % and at most 20.5 %. The hybrid up and down prediction models show an ETF trading return of 10.49%, and 25.91%, respectively. Trading inverse×2 and leverage ETF can increase the return by 1.5 to 2 times. Further research on a down prediction machine learning model is expected to increase the rate of return.

• Korean Journal of Ecology and Environment
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• v.49 no.1
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• pp.11-21
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• 2016

Cymbidium kanran Makino is being threatened in its own habitats due illegal collecting and habitat changes by vegetation growth along historical landuse change. In this study, we established habitat restoration model for conservation of C. kanran based on ecological diagnosis. Through exploration to Jeju Island in 2014 and 2015, we identified 27 unknown habitats of C. kanran and in there, abiotic variables and vegetation structure and composition were quantified. Altitudinal distribution of C. kanran was between 200 m~700 m a.s.l. and compared to distribution in 2004, Area of Occupation (AOO) decreased at 82%. Specific habitat affinity was not observed by evenly found in mountain slope and valley and summergreen and evergreen broadleaved forests, but likely more abundant in valley habitats with higher soil and ambient moisture. Total of 96 individual of C. kanran was observed with an average density of $942.6individuals\;ha^{-1}$. The plants showed relatively short leaf length (average=$10.7cm{\pm}1.1cm$) and small number of pseudo bulbs ($1.2{\pm}0.2$). Flowering and fruiting individuals were not observed in field. C. kanran was classified into endangered plant species as CR (Critically Endangered) category by IUCN criteria. Phenotypic plasticity of C. kanran was likely support to sustain in more shaded habitat environment and recent habatat changes to closed canopy and low light availability may exhibit negatively effects to C. kanran's life history. Restoring C. kanran habitat should create open environment as grassland and low woody species density.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.2
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• pp.86-94
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• 1991

Volcanic ash soils were classified as Andepts, a suborder of the Inceptisols in Soil Taxonomy. Increased knowledge on the volcanic ash soils necessitated and facilitated considerable improvement in this system. As a result, the new Order of Andisols was incorporated in the 1990 edition of the Keys to Soil Taxonomy. The central concept of an Andisol is that of a soil developing in volcanic ejecta, and/or in volcaniclastic materials, whose colloidal fractions are dominated by short-range-order minerals or Al-humus complexes. Andic propertis of volcanic ash soil in Cheju Island were investigated. For this study, soils of toposequence distributed along the southern slope of Mt. Halla, and the major soil groups such as dark brown soils, very dark brown soils, black soils, and brown forest soils were collected and analyzed for Al, Fe and Si extracted with solutions of pyrophosphate, dithionite-citrate. and oxalate respectively. Weolpyeong and Yongheung soils developed on the lower elevations contain only small amounts of allophane and Al-and Fe-humus complexes. For other soils, allophane content decrease with elevation and increaes with soil depth,whereas Al-humus complexes increase with elevation and decrease with soil depth. Substantial amount of allophane and ferrihydrite are found in all horizons of Ora and Ara soils developed on 150-300m elevations and of Noro and Jeogag soils developed on cinder cones. In the A horizons of Pyeongdae, Tosan and Heugag soils developed on the higher elevations, Al-humus complexes are dominant form of Al reflecting low pH and high organic matter content. However, lower horizons are dominated by allophane.

• Korean Journal of Remote Sensing
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• v.28 no.4
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• pp.393-407
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• 2012

This study focuses on the correction of topographic effects caused by a combination of solar elevation and azimuth, and topographic relief in single optical remote sensing imagery, and by a combination of changes in position of the sun and topographic relief in comparative analysis of multi-temporal imageries. For the Jeju Island, Republic of Korea, where Mt. Halla and various cinder cones are located, a Landsat 7 ETM+ imagery and ASTER GDEM data were used to normalize the topographic effects on the imagery, using two topographic normalization methods: cosine correction assuming a Lambertian condition and assuming a non-Lambertian c-correction, with kernel sizes of $3{\times}3$, $5{\times}5$, $7{\times}7$, and $9{\times}9$ pixels. The effects of each correction method and kernel size were then evaluated. The c-correction with a kernel size of $7{\times}7$ produced the best result in the case of a land area with various land-cover types. For a land-cover type of forest extracted from an unsupervised classification result using the ISODATA method, the c-correction with a kernel size of $9{\times}9$ produced the best result, and this topographic normalization for a single land cover type yielded better compensation for topographic effects than in the case of an area with various land-cover types. In applying the relative radiometric normalization to topographically normalized three multi-temporal imageries, more invariant spectral reflectance was obtained for infrared bands and the spectral reflectance patterns were preserved in visible bands, compared with un-normalized imageries. The results show that c-correction considering the remaining reflectance energy from adjacent topography or imperfect atmospheric correction yielded superior normalization results than cosine correction. The normalization results were also improved by increasing the kernel size to compensate for vertical and horizontal errors, and for displacement between satellite imagery and ASTER GDEM.

• Korean Journal of Environment and Ecology
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• v.34 no.5
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• pp.358-371
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• 2020

As climate change is expected to lead to a severe reduction of biodiversity, studies to investigate the reasons for habitat loss, growth decline, and death of Korean fir (Abies koreana Wilson), endangered alpine/subalpine species in Korea, have been conducted for years but found no clear answer yet. This study reviewed previous studies on Korean fir published in the journals in the past 40 years, 1980 through 2020, into 10-year units, examined the study trend by period, region, and subject with a focus on ecological studies, and analyzed the study results. The ecological studies were categorized into evolutionary ecology, physiological ecology, population ecology, and landscape ecology. Based on the results, we suggested the required research fields in the future. We found a total of 73 papers published in the past 40 years and 48 (65.8%) of them published in the past 10 years. In terms of region, Mt. Halla accounted for the most as 41 papers were on it. In terms of ecological subjects, the physiological ecology accounted for the most with 38, and the evolutionary ecology accounted for the least with 10. The review of the study results showed that many studies identified water stress caused by the water resource imbalance due to temperature increase and spring precipitation reduction following climate change as the main reason for the decline and habitat loss of Korean fir. However, recent studies suggested other factors, such as soil environment, disturbing organisms, and climatic events. The cause of the decline and death of the Korean fir not yet being clearly identified is that most of the studies dealt with the basic content, were carried out intermittently, and were concentrated in some regions. Therefore, we need long-term studies with advanced technology in each study subject at a local scale to find the cause of Korean fir decline and present sustainable management and conservation. Moreover, it is necessary to extend our study subjects to ecosystem ecology and systems ecology to integrate the results from various study subjects for a comprehensive understanding of the reason for Korean fir declines. The results of comprehensive studies could provide clearer answers for Korean fir's declines and the alternatives of conservation management and practices.