• Journal of Korean society of Dental Hygiene
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• v.7 no.2
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• pp.135-151
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• 2007

The purpose of this study was to examine the work environments of dental hygienists, to find out about what problems there were with their work environments and ultimately to help improve their work environments. It's basically intended to pave the way for furthering the welfare and interests of dental hygienists. The subjects in this study were dental hygienists who were selected by random sampling from among the members of Korean Dental Hygienists Association. Approximately 20 percent of the members each were selected from every region across the nation, and their work environments were investigated in consideration of the kind of their workplaces, service area, career and field of duties. As for the demographic characteristics of the dental hygienists investigated, there were differences between those who worked in the field of health care and the clinical workers. More of the former were older and married, and the former was ahead of the latter in career and education as well. Regarding working hours and leave of absence by kind of workplace, the number of regular average holidays was different according to their place of employment. Dental hospitals(6.66 days) and dental clinics(6.81 days) gave their employees less days off on the whole, whereas public dental clinics(19.29 days) granted the dental hygienists the longest leave of absence. Also, there was a broad gap in the number of regular average holidays among different regions in the nation. The dental hygienists who worked in Gangweon province enjoyed the longest holidays(10.88 days), while those on Jeju Island took the shortest vacation(4.46 days). Concerning monthly mean pay by place of employment, those who worked in public dental clinics were paid the best, and the dental hospital employees received the smallest pay. Their monthly mean pay significantly varied with the kind of their workplaces. As to connections between service area and pay level in the event of the dental hygienists with a four-year career, those who served in Seoul were paid the best(1,820,800 won), followed by Gyeonggi province(1,795,800 won), Gyeongsang province(1,604,200 won), metropolitan cities(1,424,800), Gangweon province(1,300,000 won) and Jeolla province(1,016,700 won). In regard to the starting pay in the different areas, the starting pay was largest in Seoul(1,501,800 won) and smallest in Jeolla province(904,000 won). Concerning work environments by place of employment, the dental hygienists in public dental clinics, general hospitals and university hospitals were far older than the others, and the career of the former was much larger than that of the latter. As to the number of regular leave of absence, public dental clinics, general hospitals and university hospitals were different from dental hospitals and clinics in that regard as well. Concerning monthly pay, public dental clinics paid their employees the best, and dental hospitals and clinics were ahead in terms of pay raise. But the reason seemed that public dental clinics and general hospitals increased the pay of their employees based on a fixed wage system and according to a fixed rate at the same time. As for relations between career and work environments, the pay of the dental hygienists differed with their career. The amount and rate of pay raise were largest for those whose career was between four years and less than six years, and smallest for those whose career was between seven years and less than nine years. The above-mentioned findings of the study suggested that in order to give dental hygienists better treatment, pay and welfare benefits should urgently be improved, and that it's required to take actions to boost their job satisfaction. Besides, they should be given more chances to receive education or to take training courses in pursuit of self-development, and how to narrow gaps in work environments among different regions or fields should carefully be considered.

• Journal of the Mineralogical Society of Korea
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• v.21 no.3
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• pp.289-295
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• 2008

We studied the difference between the clay mineral content in the bulk marine sediments (absolute clay mineral composition) and clay mineral content only in total clay minerals (relative clay mineral composition) of the Yellow Sea marine sediments, and correlated the relationship between their distribution patterns. We used 56 Yellow Sea Surface sediments collected at the second cruise in 2001 of KORDI, and determined the absolute mineral composition using the quantitative X-ray diffraction analysis. Yellow Sea surface sediments consist of primary rock forming minerals including quartz (average 44.7%), plagioclase (15.9%), alkali feldspar (10.0%), hornblende (2.8%) together with clay minerals (illite 15.3%, chlorite 2.6% and kaolinite 1%) and carbonates (calcite 1.7%, aragonite 0.6%). Absolute clay mineral contents are very high in the region extending from the southeast of Sandong Peninsula to the southwest of Jeju Island. In contrast, it is very low along the margin of the Yellow Sea. Such distribution patterns of absolute clay mineral content are very similar to those of fine-grained sediments in the study area. The average relative clay mineral composition of illite, chlorite, and kaolinite is respectively 80.3%, 14.9% and 4.8%. The distribution pattern of relative mineral composition shows very different phenomenon when compared with those of absolute mineral composition, and also do not exhibit any positive relationship with that of fine-grained sediments in which clay mineral composition is abundant. Therefore, we suggest that the relative clay mineral compositions and their distribution patterns must be used very carefully when interpreting the origin of sediment provenance.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.3
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• pp.70-78
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• 2018

Recently, the conservation of mountainous landscape and compensation for diverse demands for mountain areas such as leisure, recreation and welfare are under discussion. The purpose of this study is to investigation the perception of mountainous landscapes by those who view and recognize the landscapes and to estimate economic value by estimating the willingness to pay for the management of mountainous landscapes. This study will provide data for the management of mountainous landscapes. As a result of comparing the perception between the territorial landscape and the mountain landscape, the mountain scenery was 3.96, the management level satisfaction was 3.28, and the management necessity was 4.38, which was higher than the national landscape, while the national landscape was satisfactory but the management level was insufficient. Jeju Island (39.0%) and Gangwon (38.6%) were chosen as the most scenic areas with beautiful forest and mountainous landscape resources. The aesthetic characteristics of the vast skyline of mountain scenery, the background of the area, and the mountainous landscape that forms the landmark were evaluated highly. And, it is considered that consciousness of mountainous landscape management is heightened by 86.8% of respondents, who positively answered the Mountainous Landscape Visual Impact Assessment before the development project. The per capita payment amount for mountainous landscape management was calculated to be 3,742 won and, based on the number of visitors to the mountain National Parks in 2016, it is estimated to have an economic value of about 169.5 billion won. Policymakers have limitations in the mountainous landscape management policies of the administrative subject. Establishing a consensus on the importance and necessity of landscape management by diagnosing the status of public perception is expected to help create more effective policy direction and implement strategies for the management of these areas.

• Korean Journal of Organic Agriculture
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• v.24 no.1
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• pp.73-85
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• 2016

This study was carried out to allelopathic effects of aqueous extracts on Coronopus didymus in order to investigate the competitive dominant in plant ecosystem and possibility application in natural herbicide. Number of species and species diversity for close to patch of C. didymus was decreased gradually site #1 (7, 1.76), site #2 (5, 1.34) and site #3 (5, 1.25). It was generally decreased the relative germination ratio (r=-0.731, p<0.01), the mean germination time, the relative elongation ratio (r=-571, p<0.01, r=-0.730, p<0.01), the relative fresh weight (r=-0.743, p<0.01), development of root hairs of receptor plants by concentration of the aqueous extracts from C. didymu. But they were different from the growing regions, the kind of receptor plants and the treatment of the aqueous extracts. Especially, it was differently effected among growing regions that inhibited more radicle than shoot by the aqueous extracts concentration of C. didymus. Total phenolic compound in the aqueous extracts of C. didymus analyzed about $23.0{\pm}1.1mg/g$. Total phenolic compounds of soil in survey area was increased gradually site #1 ($0.072{\pm}0.002mg/g$), site #2 ($0.082{\pm}0.003mg/g$) and site #3 ($0.092{\pm}0.004 mg/g$). We think that the aqueous extracts of C. didymu showed allelopathic effects on other plants. Therefore, C. didymu hold the competitive dominant of plant ecosystem in Jeju Island and possibility application of natural herbicide.

• Korean Journal of Organic Agriculture
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• v.16 no.1
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• pp.127-142
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• 2008

This study was carried out to germination characteristics by temperature conditions and allelopathic effects of aqueous extracts on Amaranthus spinosus L. in order to investigate the competitive dominant in plant ecosystem and possibility application of natural herbicide. A. spinosus L. sprouted after 24 hour from seeding in $30{\sim}45^{\circ}C$ treatment. The germination ratio of A. spinosus L. was the highest estimated at 63.3(${\pm}2.9$)% in $40^{\circ}C$ treatment, followed by 33.3(${\pm}2.9$)% in $35^{\circ}C$, 1.7(${\pm}2.9$)% in $30^{\circ}C$ and 5.0(${\pm}0.0$)% in $45^{\circ}C$ treatment. It was generally decreased the Relative Germination Ratio(RGR), the Relative Elongation Ratio(RER), the Relative Fresh weight Ratio(RFR) of receptor plants by the aqueous extracts of concentration of A. spinosus L. but it was differently inhibited the kind of receptor plant species. And it was different effected among growing regions that aqueous extracts of concentration of A. spinosus L. inhibited more root than shoot. The total phenolic compounds content of A. spinosus L. was decreased gradually middle, first and last of growth stage, and gradually decreased to leaves, roots and stems. We think that A. spinosus L. appeared high germination ratio at a short period and showed allelopathic effects on other plants. Therefore A. spinosus. L. hold the competitive dominant of plant ecosystem in Jeju Island and possibility application of natural herbicide.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.135-151
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• 1977

The present paper summerizes the studies on clay mineralogical characteristics of Korean soil, relationship between potassium and clay minerals, potassium release pattern of clay minerals and utilization of clay minerals for soil conditioner and fertilizers, which have been carried out in this laboratory. 1. The red yellow podzolic soil is mostly abundant in the upland of Korea and mainly consists of halloysite and weathered intermediates of mica such as illite and vermiculite. 2. With regard to soil parent material, kaolin mineral occurs abundant in soils derived from granite and granite gneiss. Mica is dominant in basaltic soil. The main clay mineral of the soil, originated from the Tertiary, is found montmorillonite and the volcanic soil of Jeju Island has plenty of allophane as its main clay mineral. 3. It is confirmed that the soil fertility depends on the composition of clay minerals. The red yellow podzolic soil, containing lot of kaolin, shows low productivity while the montmorillonite soil has higher productivity. 4. The release rate of solid phase potassium (micas and fixed potassium) follows the 1st order reaction equation in the equilibrium solution of $IN-NH_4OAc$. The potassium release constant is positively correlated with the mica content of the clay but negatively correlated with the content of $14.5{\AA}$ minerals. On the other hand, the potassium release constant has very high correlation with the ratio(Kex/Kt) of exchangeable potassium(Kex) to total potassium(Kt). 5. It is also found that Kex/Kt has rather high correlation with the content of mica and $14.5{\AA}$ minerals existed in the clay as well as the mica content of the soil.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.1
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• pp.25-30
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• 1978

Field experiments were conducted on the cropping system soybean-barley-soybean to investigate the effect of phosphorus and wollastonite application, effective application methods of phosphrus, and their residual effect in a typical Jeju island volcanic ash soil when the fertilizers were applied to the first crop of the three crops sequence. The results are summarized as follows. 1. Response of phosphorus was higher for barley than for soybean. The maximum application rate of phosphate was extimated to be 10-20kg/l0a for cultivation of soybean first crop) and 100kg/l0a for barley (second crop). Barley yield under 100kg/l0a of phosphate was double as compared to the no phosphate plot. 2. With application of 100kg/10a phosphate at the sowing time of soybean, the available phosphate in the soil after harvesting of soybean was increased to 175ppm but decreased to 60 ppm by cultivation of barley (second crop.) On the other hand, the phosphate absorption coefficient was 1,146mg/100g after soybean harvest but increased to 1,764mg/100g after barley harvest. 3. High residual effect was found in the plot to which phosphate applied with compost in the sowing band. 4. Response to wollastonite under heavy application of phosphate was high and residual effect was also great. 5. Response of soybean to wollastonite was higher than that of barley. Application of wollastonite increased the yield of all three crops soybean (first crop) by 30%, barley (second crop) by 12% and soybean (third) by 20%, respectively. Highest yield was obtained from the 1,000kg/10a wollastonite treatment for soybean and 500kg/l0a for barley.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.384-395
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• 2018

This study was conducted to investigate the distribution and variation of the anion and cation number of aerosols in the A and B regions of Gyorae forests. Ions were measured using an ion number meter between 28 June and 13 July 2017. The total average number of anions and cations were $735ions/cm^3$ and $459.27ions/cm^3$, respectively, which were measured at five sites in A area at average temperature of $27.81^{\circ}C$, wind speed of 0.28 m/sec, and altitude of 455.7 m. The average number of anions and cations were $780ions/cm^3$ and $379.55ions/cm^3$, respectively, which were measured at all four sites in the B region at average temperature of $27.6^{\circ}C$, humidity of 80%, wind speed of 0.1 m/sec and altitude of 477 m. The number of anions and cations in the A and B regions was $757.5ions/cm^3$ and $419.41ions/cm^3$, respectively. The number of ions was highly variable for each measurement over time. The number of anions remained $275.73ions/cm^3$ higher than that of cations. The variance of the measured values of anions and cations between and within sites A and B was significant (p<.001) and there was a significant positive correlation between regional mean values of anions and cations. In conclusion, the temporal distribution and variation of the ion content in the Gyorae forests provide basic information regarding aerosol compositions and changes.

• The Journal of the Petrological Society of Korea
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• v.21 no.3
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• pp.309-333
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• 2012

Basalt having lots of feldspar phenocryst occurred at the northern and southern slope of the Mt. Halla, Jejudo. Among them, the Sioreum trachybasalt in southern slope consists of abundant phenocrysts of plagioclase in aphanitic groundmass. And the number of plagioclase grains are about 20 per $10cm^2$, and based on 667 grains the sizes are 13~0.7 mm (average 4.23 mm) in length and 8.6~0.5 mm (average 2.3 mm) in width. In according to modal analyses, Sioreum basaltic rock consists mainly of plagioclase (16~28%), olivine, clinopyroxene (1.5~6%) and opaque minerals (~0.1%) of magnetite and ilmenite as phenocryst and microphenocryst and groundmass (60~82%). The compositions of plagioclase, olivine and clinopyroxene are bytownite~andesine, chrysolite~hyalosiderite, augite respectively. Plagioclase phenocrysts show different type of zoning, namely, normal, reversal, patchy, oscillatory type. The An contents of zoned plagioclase mainly increase from core to rim. Those of oscillatory type from core to rim show variations of increase following decrease or decrease following increase, being more enriched in rim or almost same to core. Under the microscope, some plagioclase phenocrysts are especially melted in core part or marginal part, or found as only the remnant remain which resulted from reaction with melt. Some clinopyroxene are also corroded in margin part or found as irregular shape resulted from melting. The characteristics of petrography and compositional variation from core to rim of plagioclase and clinopyroxene, indicate that they are disequilibrium with melt and has been undergone geological environmental changes in magma batch during crystallization including magma mixing with replenishment of more mafic and high temperature melt.

• Journal of the Korean earth science society
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• v.26 no.1
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• pp.93-105
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• 2005

Climatological characteristics in the variation of soil temperatures in Korea were investigated using Korea Meterological Administration's observation data. And the impacts of soil moisture on the variation of soil temperature were examined using observed precipitation data. The climatological averages of soil temperatures are ranged from 14.4 to $15.0^{\circ}C$ regardless of depths. And they showed an latitudinal gradient with a warm temperature at the southern region and 'U' shape as in the air temperature with a high value along the coastal region. The relatively higher heat capacity and low conductivity of soil compared to those of the air resulted in the significant delay of the maximum and minimum date with depth. As a results, soil acts as a heat source during winter while a heat sink during summer. Global warming and urban heat island have increased the soil temperatures with an average rate $0.3\~0.5^{\circ}C/10-year$ as in the air temperature during last 30 years $(1973\~2002)$. However, the warming rate is maximized during spring contrary to the winter in the air temperature. The temporal variation of soil temperatures is strongly affected by that of soil moisture through an modification of the heat capacity and heat convection. In general, the increased soil moisture clearly decreased the temporal variations and increased the deep layer soil temperatures during cold season.