• 생태와환경
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• 제44권1호
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• pp.42-57
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• 2011

We described the above-ground plant species composition and measured a range of soil physico-chemical properties and the composition and size of the soil seed bank in the remnant natural vegetations on the flood plains of the Han River within Seoul, South Korea. We used analysis of variance and multivariate analyses to analyse the data and S${\o}$rensen's similarity index to compare the composition of the vegetation and seed banks. The soils were circum-neutral and composed of mainly sand and silt fractions with a very limited clay component; a gradient based on sand/clay proportions was identified. The soil seed banks varied markedly between- and within-sites and had much greater species diversity than the above-ground vegetation. Two of the major dominants in the vegetation (Miscanthus saccariflorus and Phragmites australis) were found at very low densities in the seed bank. The site differences appeared to be correlated with the sand-clay gradient, suggesting that the soil properties differentially affected seed inputs into the soil, or that the processes than controlled sediment deposition during floods was also important in differentially affecting seed deposition. Lastly, there was relatively little similarity between the vegetation, dominated mainly by perennials, and the seed bank which contained a relatively large proportion of annuals and biennials. This result suggests that after disturbance caused by flooding there is the potential for many other species to colonize. This may impinge on the regeneration potential of the sites and cause concern for the future conservation of these important remnants of natural vegetation.

• 한국재료학회지
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• 제14권3호
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• pp.203-210
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• 2004

Effects of various pretreatments on the adhesion of copper-coated polymer films were investigated. Copper-coated polymer films were prepared by an electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) coupled with a DC bias system at room temperature. PET(polyethylene terephthalate) film was employed as a substrate material and it was pretreated by industrially feasible methods such as chromic acid, sand-blasting, oxygen plasma and ion-implantation treatment. Surface characterization of the copper-coated polymer film was carried out by AFM(Atomic Force Microscopy) and FESEM(Field Emission Scanning Electron Microscopy). Surface energy was calculated by based on the value of the contact angle measured. The adhesion of copper/PET films was determined by a pull-off test according to ASTM D-5179. It was found that suitable pretreatment of the PET substrate was required for obtaining good adhesion property between copper films and the substrate. In this study the highest adhesion was observed in sand-blasting, and then followed by those of acid and oxygen plasma treatment. However, the effect of surface energy was insignificant in our experimental range. This is probably due to compensating the difference in surface energy from various pretreatments by exposing substrate to ECR plasma for 5 min or longer at the early stage of the copper deposition. Therefore, it can be concluded that surface roughness of the polymer substrate plays an important role to determine the adhesion of copper-coated polymer for the deposition of copper by ECR-MOCVD.

• 한국산림과학회지
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• 제96권5호
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• pp.503-509
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• 2007

The major objective of this study was to analyze the difference of the chemical characteristics of acid deposition in Quercus forests in Korea and Japan. The pH values of rainfall at the experimental forest of Kangwon National University (KS site) were higher than those at the Foresta Hills in Japan (JP site), and all chemical contents of throughfall and stemflow were much higher than those of rainfall in Quercus forest stands at the KS and JP site. The pH values, $Ca^{2+}$, $NO_3{^-}$ and $SO{_4}^{2-}$ concentration of throughfall and stemflow at the KS site showed seasonal variation. While at the JP site, the same pattern was shown in the pH values of throughfall and stemflow, however, did not show any difference among seasons. Also, the annual input of all nutrients in these two contrasting forests varied seasonally. These results can be used to predict the amounts of air pollutant that are washed off and leached by the rainfall and Yellow Sand (Asian dust), including NOx and SOx acid pollutants transported easterly from China in the spring. Therefore, it is necessary to quantify the inputs of dry and wet deposition throughout a full year to gain a more complete understanding of the effects of acid deposition on the nutrient cycles in these forest ecosystems.

• 분석과학
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• 제9권1호
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• pp.98-106
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• 1996

대기확산 모델 TCM(Texas Climatological Model)을 이용하여 $SO_2$ 오염도를 예측하였으며 강우분석에 의한 $SO_2$의 침적에 관하여 연구하였다. 원주시의 월별 $SO_2$ 실측치와 모델예측치의 상관계수는 높은 편이었으며 $SO_2$는 강우에 의해 세척되어 제거되는데, $SO_2$ 총배출량에 대한 제거율이 여름철이 가을, 겨울보다 높게 나타났으며, 이는 여름철에 강우량이 많기 때문이 고 강우량과 제거율과의 상관계수는 0.68로 나타났다. 강우량이 많은 달은 $SO_2$ 실측치가 모델예측치보다 상당히 낮아지는 경향을 보였다.

• 한국지형학회지
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• 제24권3호
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• pp.83-103
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• 2017

Sand deposit with shell units is exposed in Hasa-ri, Yeonggwang-gun, Jeonnam province. We investigated the characteristics of sand sediment topography in the Yeonggwang coastal area to collect evidence of the paleo-environmental change. We performed analysis on particle characteristics, chemical composition, and the age of deposition of sediments. The deposit comprise moderately well sorted medium and fine sand ($1.00{\sim}2.19{\varphi}$). Various sedimentary structures can be observed. Geochemical characteristics change by depth and the degree of variation with depth is small. The results obtained from OSL dating show that sand layers below shell units are deposited 0.32-0.43 ka. As the elevation of the shell unit far mean high water levels or highest high water level, the extensive shell layers could only have been deposited during storm surge conditions. Aeolian processes are discounted due to the size of clasts and the location at which they occur. Results of age dating of the surrounding deposits indicate shell deposits formed after around 300 years age. There is a distinct difference between sedimentary layers including dark brown-black layer. The sedimentary characters such as particle size and geochemistry show difference with depth. It is presumed that depositional environmental in Hasa-ri has changed several times before. This study is expected to contribute to finding an evidence about occurrence of storm surges.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1504-1511
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• 2005

The efficiency of the hydraulic transport of soil-water mixtures is an important factor in designing and operating a pump & pipeline system and is directly connected with dredging cost and working period. However, the hydraulic transport mechanism in the slurry flow inside the pipeline such as frictional losses, specific energy consumption, deposition velocity has not been well established. In this study a new dredging test loop system was designed and built. It is composed of a slurry pipeline with pipes of different diameters, a centrifugal slurry pump and a diesel engine connected with the slurry pump. and equipped with modern measuring facilities that enable to measure all important characteristics of a transportation system. The objective of this paper is to discuss the efficiency of the hydraulic transport of the Jumoonjin sand-water mixtures in the dredging test loop and to present simple equations induced from the test results of the loop that can express the transport product and the transport productivity.

• 동굴
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• 제66호
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• pp.45-57
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• 2005

This Paper is a study on the duality of speleothem that appeared in 'Hyeob Jae Cave' which is designated as the natural monumen. No.236. It is located at Hyeob Jae Ri, Hanrim Eub, Bug Je-ju Gun, Je-judo. The findings are as follows. 1. The distribution range of the shelly sand which has maximum thickness of $10m{\pm}$ and average of $3m{\pm}$ was $3.2m^2$. 2. The desert hollow acted to promote the speleothem deposits in the lava tunnel with lava mound formed by lavapilz and artificial breaksand wall. 3. The main component of the pseudo limestone cavern was carbonate Calcium from shelly sand. And the deposition of speleothem in the Cave was accelerated after the volcanic erupsion of Biyang island in 1002. A.D. 4. The secondary depositions of Calcite recognized as speleothem up to now it can be used for the pseudo karst in general. 5. It seems that the variety of the cave deposits is decided depending upon the geology, land form, climate, vegetations and the structural environmental factors. 6. It seems that the wondering development of accretionary deposits caused by encrusting has a close relation with intermittent seepage of ground water. 7. Finally, we can acknowledge the coexistent duality of speleothem by shelly sand along with the joint and the lava stalactites formed at the same time with the lava tunnel on the ceiling where there was no seepage.

• 한국주조공학회지
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• 제12권6호
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• pp.471-479
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• 1992

For the last 2 decades, the bonding materials for the foundry sand and the foundry equipments with high performance have been developed and employed in the foundry shops. In those periods, the furan resins hardened in higher temperature have been replaced with the self-hardened ones in the room temperature. Simultaneously the various reclamation methods of the self-hardened furan resin sand have been developed in order to get the clean working environments, the reduction of solid wastes and the lower of production cost in the foundry. In this experimental study, the combustion reclamation method using the fluidized bed among the various methods was studied in order to reduce the L.O.I. and /or $N_2$ gas due to the deposition of the furan resins and the hardeners. Comparing the results of this experimental combustion reclamation method with those of the employed pneumatic method, the Surface Stability Index of the specimen made by combustion method is 30% higher than that of the latter one and L.O.I. decreases about 30%. The reclamation temperature of 650$^{\circ}C$ in this experimental fluidized bed would be recommended in the viewpoints of the reclamation period, the fuel consumption and the residual quantity of the furan resin. The formula determining the minimum fluidizing velocities according to the temperatures in the fluidized bed has been obtained.

• 한국정밀공학회지
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• 제18권3호
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• pp.47-52
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• 2001

Rapid Prototyping(RP) has been widely applied in designing and developing process of new products. RP can reduce the lead time and expense required to bring a new product form initial concept to production. Among several RP process can dramatically reduce the total build time and be applied for fabrication of large-sized and free form object because it uses in LOM the paper thickness is 0.05∼0.38mm as deposition feature segment. In this study, mechanical properties of pattern with LOM system is studied for optimal design of sand mold casting. The main result is that tensile, compressive strength and pattern size are significantly affected by temperature of hot roll.

• 대한원격탐사학회지
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• 제38권6_1호
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• pp.1315-1328
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• 2022

신두리해빈 인근지역은 겨울철 북서풍의 영향으로 인하여 모래언덕을 이룬 전형적인 퇴적지형이다. 그 규모가 방대하고 잘 발달되어 있어 보존가치를 인정받아 현재 천연기념물 제431호로 지정되어 있으며 지형학적 가치 보존 측면에서 꾸준한 모니터링이 필요하다. 본 연구에서는 충청남도 태안군에 위치한 신두리 해안사구의 장기간 지형변화 관측을 위해 약 36년 동안의 항공영상, 드론영상 그리고 드론기반 LiDAR 자료를 사용하여 분석하였다. 이를 위해서 원 자료로부터 생성된 Digital Elevation Model (DEM)을 사용하여 래스터 연산기반의 DEM 차분 기법을 적용하여 각 기간별 표고 및 부피의 변화량을 산정하였다. 또한 각 자료원의 고유오차를 오차전파법칙을 이용하여 확률기반의 부피의 변화량도 산정하였다. 그 결과, 1986년부터 2022년까지 관심영역 A (면적: 17,960 m²)에서는 35,119 m³의 퇴적이 발생하였으며, 관심영역 B (면적: 17,686 m²)에서는 54,954 m³의 퇴적이 발생하였음을 알 수 있었다.