Linear wave reflection by trench with various shapes     

Tae-Hwa Jung  Kyung-Duck Suh  Seung Oh Lee  Yong-Sik Cho 《Ocean Engineering》2008,35(11-12):1226-1234

Two types of analytical solutions for waves propagating over an asymmetric trench are derived. One is a long-wave solution and the other is a mild-slope solution, which is applicable to deeper water. The water depth inside the trench varies in proportion to a power of the distance from the center of the trench (which is the deepest water depth point and the origin of x-coordinate in this study). The mild-slope equation is transformed into a second-order ordinary differential equation with variable coefficients based on the longwave assumption [Hunt's, 1979. Direct solution of wave dispersion equation. Journal of Waterway, Port, Coast. and Ocean Engineering 105, 457–459] as approximate solution for wave dispersion. The analytical solutions are then obtained by using the power series technique. The analytical solutions are compared with the numerical solution of the hyperbolic mild-slope equations. After obtaining the analytical solutions under various conditions, the results are analyzed.  相似文献   

Regional geochemical baseline concentration of potentially toxic trace metals in the mineralized Lom Basin,East Cameroon: a tool for contamination assessment     

Mumbfu Ernestine Mimba  Takeshi Ohba  Salomon César Nguemhe Fils  Melvin Tamnta Nforba  Nozomi Numanami  Tasin Godlove Bafon  Festus Tongwa Aka  Cheo Emmanuel Suh 《Geochemical transactions》2018,19(1):11

The distribution of trace metals in active stream sediments from the mineralized Lom Basin has been evaluated. Fifty-five bottom sediments were collected and the mineralogical composition of six pulverized samples determined by XRD. The fine fraction (<?150 µm) was subjected to total digestion (HClO₄?+?HF?+?HCl) and analyzed for trace metals using a combination of ICP-MS and AAS analytical methods. Results show that the mineralogy of stream sediments is dominated by quartz (39–86%), phyllosilicates (0–45%) and feldspars (0–27%). Mean concentrations of the analyzed metals are low (e.g. As?=?99.40 µg/kg, Zn?=?573.24 µg/kg, V?=?963.14 µg/kg and Cr?=?763.93 µg/kg). Iron and Mn have significant average concentrations of 28.325 and 442 mg/kg, respectively. Background and threshold values of the trace metals were computed statistically to determine geochemical anomalies of geologic or anthropogenic origin, particularly mining activity. Factor analysis, applied on normalized data, identified three associations: Ni–Cr–V–Co–As–Se–pH, Cu–Zn–Hg–Pb–Cd–Sc and Fe–Mn. The first association is controlled by source geology and the neutral pH, the second by sulphide mineralization and the last by chemical weathering of ferromagnesian minerals. Spatial analysis reveals similar distribution trends for Co–Cr–V–Ni and Cu–Zn–Pb–Sc reflecting the lithology and sulphide mineralization in the basin. Relatively high levels of As were concordant with reported gold occurrences in the area while Fe and Mn distribution are consistent with their source from the Fe-bearing metamorphic rocks. These findings provide baseline geochemical values for common and parallel geological domains in the eastern region of Cameroon. Although this study shows that the stream sediments are not polluted, the evaluation of metal composition in environmental samples from abandoned and active mine sites for comparison and environmental health risk assessment is highly recommended.  相似文献   

An analytic solution to the mild slope equation for waves propagating over an axi-symmetric pit     

Tae-Hwa Jung  Kyung-Duck Suh   《Coastal Engineering》2007,54(12):865-877

An analytic solution to the mild slope equation is derived for waves propagating over an axi-symmetric pit located in an otherwise constant depth region. The water depth inside the pit decreases in proportion to an integer power of radial distance from the pit center. The mild slope equation in cylindrical coordinates is transformed into ordinary differential equations by using the method of separation of variables, and the coefficients of the equation in radial direction are transformed into explicit forms by using the direct solution for the wave dispersion equation by Hunt (Hunt, J.N., 1979. Direct solution of wave dispersion equation. J. Waterw., Port, Coast., Ocean Div., Proc. ASCE, 105, 457–459). Finally, the Frobenius series is used to obtain the analytic solution. Due to the feature of the Hunt's solution, the present analytic solution is accurate in shallow and deep waters, while it is less accurate in intermediate depth waters. The validity of the analytic solution is demonstrated by comparison with numerical solutions of the hyperbolic mild slope equations. The analytic solution is also used to examine the effects of the pit geometry and relative depth on wave transformation. Finally, wave attenuation in the region over the pit is discussed.  相似文献   

Assessing and prioritizing environmental hazards associated with abandoned mines in Gangwon-do,South Korea: the Total Mine Hazards Index     

Sung-Min Kim  Jangwon Suh  Sungchan Oh  Jin Son  Chang-Uk Hyun  Hyeong-Dong Park  Seung-Han Shin  Yosoon Choi 《Environmental Earth Sciences》2016,75(5):369

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Evaluation of climatological tropical cyclone activity over the western North Pacific in the CORDEX-East Asia multi-RCM simulations     

Chun-Sil Jin  Dong-Hyun Cha  Dong-Kyou Lee  Myoung-Seok Suh  Song-You Hong  Hyun-Suk Kang  Chang-Hoi Ho 《Climate Dynamics》2016,46(3-4):765-778

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Changes in spatial variations of sap flow in Korean pine trees due to environmental factors and their effects on estimates of stand transpiration     

Minkyu Moon  Taekyu Kim  Juhan Park  Sungsik Cho  Daun Ryu  Sanguk Suh  Hyun Seok Kim 《山地科学学报》2016,13(6):1024-1034

It is difficult to scale up measurements of the sap flux density (Js) for the characterization of tree or stand transpiration (E) due to spatial variations in JS and their temporal changes. To assess spatial variations in the sap flux density of Korean pine (Pinus koraiensis) and their effects on E estimates, we measured the Js using Granier-type sensors. Within trees, the Js decreased exponentially with the radial depth, and the Js of the east aspects were higher than those of the west aspects. Among trees, there was a positive relationship between Js and the tree diameter at breast height, and this positive relationship became stronger as the transpiration demand increased. The spatial variations that caused large errors in E estimates (i.e., up to 110.8 % when radial variation was ignored) had varied systematically with environmental factors systematic characteristics in relation to environmental factors. However, changes in these variations did not generate substantial errors in the E estimates. For our study periods, the differences in the daily E (E _D) calculated by ignoring radial, azimuthal and tree-to-tree variations and the measured E _D were fairly constant, especially when the daily vapor pressure deficit (D__D) was higher than 0.6 kPa. These results imply that the effect of spatial variations changes on sap flow can be a minor source of error compared with spatial variations (radial, azimuthal and tree-to-tree variations) when considering E estimates.  相似文献   

Weathering and deterioration of rock properties of the Dabotap pagoda (World Cultural Heritage), Republic of Korea     

Chan Hee Lee  Myeong Seong Lee  Mancheol Suh  Seok-Won Choi 《Environmental Geology》2005,47(4):547-557

The Bulkugsa Dabotap pagoda was built in AD 761, and designated as World Cultural Heritage by UNESCO in 1995. The ca. 270 blocks used in the construction of the pagoda consist mainly of white grey alkali granite with medium-grained equi-granular texture and small mialolitic cavities. Small quantities of biotite granite, granodiorite, gabbroic and tuffaceous rocks were also used. Some overlapping blocks are very damp. The pagoda body is inclined toward the northeast owing to differential loading. Fractures and artificial deterioration of the pagoda are not serious, but the surfaces of blocks show exfoliations that indicate granular decomposition of minerals. The supporting rocks and the round handrail of the octagonal second floor are too weathered to be treated and are being replaced. The roof stones on the first and second floor are seriously damaged because there is no drainage route for rainwater. The joints between blocks have fractures that cross each other; they have been further damaged by inserting concrete, cement mortar, rock fragments and iron plates. This has accelerated discoloration and fractures. Widespread colonization by algae, fungi, lichens and bryophytes has occurred on the margins and surfaces roof stones of the pagoda. Chemical treatment will be necessary to remove the vegetation cover.  相似文献   

Natural deterioration and conservation treatment of the granite standing Buddha of Daejosa Temple, Republic of Korea     

C. H. Lee  S. W. Choi  M. Suh 《Geotechnical and Geological Engineering》2003,21(1):63-77

The Daejosa Buddha is formed of highly weathered coarse grained biotite granite. The main body is dark green due to a covering of lichens. The main body of the Buddha has developed nearly vertical, horizontal and oblique joint systems. Results of physical properties for the rock samples from the Daejosa Buddha are lower than for normal fresh granite as the primary minerals of the host rocks have been altered to clay and iron hydroxide minerals. Spore and mycelium of green algaes and some plants cover the surface of the standing Buddha and fill the pore space of the surrounding rocks. Considering the weathering and state of deterioration, the Buddha statue requires conservation treatment. Restoration may be largely divided into the head part, upper and lower parts, and the back side of the Buddha. The head and the cap rock were joined and restored with unslaked lime filling. The head and stone crown of the Buddha were fitted and restored using an epoxy type resin with high viscosity that was mixed with granite powder and talc as petro-fillers. For the back side, resin was applied for reinforcement. Araldite and hardener of low viscosity that were used with the addition of glass fibers. Finally, texture and color matching treatments were carried out.  相似文献   

Separation of incident and reflected waves in wave–current flumes     

Kyung Doug Suh  Woo Sun Park  Beom Seok Park 《Coastal Engineering》2001,43(3-4)

A technique is developed to separate the incident and reflected waves propagating on a known current in a laboratory wave–current flume by analyzing wave records measured at two or more locations using a least squares method. It can be applied to both regular and irregular waves. To examine its performance, numerical tests are made for waves propagating on quiescent or flowing water. In some cases, to represent the signal noise and measurement error, white noise is superimposed on the numerically generated wave signal. For all the cases, good agreement is observed between target and estimation.  相似文献   

Wave reflection from perforated-wall caisson breakwaters [Coastal Eng., 26 (1995) 177–193]     

K. D. Suh  W. S. Park 《Coastal Engineering》1997,30(3-4)

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