• Korean Journal of Plant Taxonomy
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• v.40 no.1
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• pp.50-58
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• 2010

The nutlet morphology and pericarp structure of 14 taxa (4 taxa of the genus Glechoma and related taxa) were studied by light and scanning electron microscopy, and a detailed description of nutlet morphological features for all examined taxa is provided. The shape of the nutlet is ovate to elliptic. Its size is 1.36-3.83 mm in length and 0.80-2.65 mm in width. The largest one was found in Marmoritis rotundifolia, while the smallest one was in Agastache nepetoides. Three different surface types were recognized in the studied taxa based on differences in cell outline and cell boundary relief (rectangular, pitted, and ridged negative reticulate-cell). Three types of trichome (uni-cellular non-glandular trichome, multi-cellular non-glandular trichome, and peltate glandular trichome) were distributed in the nutlets. The pericarp is formed in three layers (i.e., exocarp, mesocarp, and endocarp including sclenchyma tissue), and the pericarp in the studied species is $39.0-237.5{\mu}m$ thick. The morphological and anatomical features (the nutlet shape, surface type, and trichome distribution) in the genus Glechoma and related taxa are described and discussed.

• Journal of Plant Biology
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• v.28 no.2
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• pp.165-175
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• 1985

The natural forest vegetation of the Piagol, Mt. Chiri, was classified into five major communities, i.e. Quercus mongolica, Carpinus laxiflora, C. tschonoskii, Q. serrata and Fraxinus mandshurica community. C. tschonoskii, C. laxiflora and Q. mongolica characteristically were dominated in the range of 500∼700 m, 700∼900 m and 900∼1,400 m in altitude, respectively. Abies nephrolepis and Rhododendron schlippenbachii in the ridge of Nogodan-Nalnaribong, and F. mandshurica and Q. serrata in the Yongsuam ravine were found as the dominant species. The transition between C. tschonoskii and C. laxiflora communities was relatively wide. The boundary between F. mandshurica, in the conglomerated zone, and the other communities surrounding its community was fairly abrupt. In Q. mongolica community, the canopy was relatively opened and the oak young tree of undergrowth was fairly dense. In the community of C. laxiflora and C. tschonoskii, the species composed of their understory was rich while their coverage was lower than that of Q. mongolica community. Shannon's diversity index was decreased in order of C. tschonoskii, C. laxiflora and Q. mongolica community, while their Simpson's dominance index increased conversely. Judging by the DBH-class distribution showing the negative exponential curve, these communities were considered as the climax forest. In Polar Ordination used samples (quadrats), the vegetation of the Piagol was divided into five groups, which was coincided with five communities classified by Braun-Blanquet system. In the ordination, the first axis and the second axis may be considered soil conditions and thermal conditions, respectively. It seems that two different methods, phytosociological method in macro level and ordination techniques in micro level, are useful for the vegetation classification.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.313-325
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• 2011

Finite element grid system using h-refinement on the Yellow Sea was constructed based on previous study (Suh, 1999b) from 14 K to 210 K and special attention was concentrated on refining the coastal zone. In grid generation, depth change between adjacent points and non-dimensional tidal wave length ratio were considered. As a result approximately a quarter of the total nodes are located nearby 5 m of shallow area. Accurate bathymetry data using 30's and ETOPO1 with open boundary conditions of 8 major tidal constituents extracted automatically from FES2004 have been applied. In tidal simulation a 3-dimensional nonlinear harmonic model was setup and tidal amplification due to changes in vertical turbulent and bottom friction were simulated. In this study not only 8 major tidal constituents but also nonlinear shallow tides $M_4,$, $MS_4$ and long period $M_f,$, $M_{sf}$ were reproduced. It is found that implication of spatial variation of friction coefficient plays a very important role in reproduction of astronomical and shallow tides which are computed by iterative computation of nonlinear terms. Also it should be considered differently with respect to tidal periods. To understand the distribution of tidal asymmetry, amplitude ratio of $M_4/M_2$ and phase differences $2g(M_2)-g(M_4)$ were calculated. Tidal distortion ratio marks up to 0.2 on the west coast showing shallow coastal characteristics and somewhat wide range of ebb-dominances in front of Mokpo area are reproduced.

• 한국지구물리탐사학회:학술대회논문집
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• 2002.09a
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• pp.46-66
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• 2002

High-resolution multichannel seismic data were collected in the coastal area near the Gori nuclear power plant to investigate Quaternary fault pattern and timing. A 12 channel streamer, a sparker, and a portable recorder were used for data acquisition. Because the group interval of the streamer was 6.25 m and the sparker can generate acoustic waves with the frequency content of up to 500 Hz, the data show a significant improvement both in horizontal and vertical resolution. The area surveyed is covered with 30-40 m thick Holocene sediments that constitute the mud belt along the southeastern coast of Korea. The survey area is characterized by the well discriminated Pleistocene and Holocene boundary and shallow gas-charged zones. A number of Quaternary faults were found in the sediment column, that are nearly vertical and extend north-south. The Quaternary faults, arranged at a spacing of a few hundred meters, suggest that they were formed in response to compression, although some of them reveal extensional characteristics. Locally, faults disrupt Incised-channel fills that are interpreted to have formed in the early stage of transgression after the beginning of the Holocene. Seismic sections suggest that shallow gas in the mud belt sediments made its way upward through the fractured fault planes. The tectonism responsible for the opening of the East Sea has not persisted since the late Miocene, but vigorous Quaternary faulting activity in the vicinity of the southeastern Korean Peninsula indicates that tectonic stability has yet to be achieved in this region underlain by the hotter than normal mantle.

• Journal of Conservation Science
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• v.6 no.1 s.7
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• pp.61-70
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• 1997

An integrated geophysical survey was conducted to study a construction method of the Sonsanri tombs including the Muryong royal tomb. With the distribution of soil resistivity and self potential values, the boundary between original ground and the construction site was delineated clearly. The original ground has relatively high resistivity of $1,000\~1,500$ ohm-m and low self-potential values of $0{\pm}3mV/m$, while the construction site has low resistivity less than 200 ohm-m and quite high self-potential values of $-20\~30mV/m$. It is interpreted that the open site for construction of subsurface tomb has the size of about 35 m in the north-south direction. Big difference in characteristics of ground between the tomb site and the original site gives a clue for the construction method of tombs in Baekje dynasty. The site was opened about 35 meters in the north-south direction and then a mold structure was constructed with a brick frame outside. The brick frame consists of bricks cemented each other and structually combined. The mold structure was removed from inside after refill of the opened construction site with some cemented rock debris and soil.

• Journal of Environmental Impact Assessment
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• v.28 no.6
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• pp.507-524
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• 2019

The purpose of this study was to validate the EFDC model for the weir pool of Gangjeong-Goryong Weir located in Nakdong River, and evaluate the effect of flow control and phosphate loading reduction on the water quality and algae biomass by group (Diatom, Green, Cyanobacteria). As a result of model validation using 2018 experimental data,the time series of water level and vertical distribution of water temperature, DO, organic matter, nitrogen, and phosphorus time series were properly simulated. Seasonal fluctuations of algae biomass by group were adequately reproduced, but the deviations between measured and simulated values were significant in some periods. As a result of scenario simulations to control the water level and flow rate, the thermal stratification was resolved as the water level was lowered and the flow rate increased. The flow velocity at which the water temperature stratification was resolved was about 0.1 m/s, which is consistent with the previous study results of Baekje Weir in Geum River. Simulations of the 2Q flow scenario showed that Chl-a decreased by 8.7% and the cell density of diatom and green algae declined. The cell density of cyanobacteria increased, however, because the high concentrations of cyanobacteria in the upstream boundary conditions directly affected downstream due to increased flow velocity. In the scenario simulation of reducing the influent phosphate load concentration (average 0.056 mg/L) to 50%, Chl-a decreased by 13.6%.The results suggest that the upstream algae concentration and phosphorus load reduction should be considered simultaneously with hydraulic control to prevent algal overgrowth of Gangjeong-Goryong Weir.

• Journal of the Korean Geographical Society
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• v.41 no.4 s.115
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• pp.391-403
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• 2006

The Hanon volcano located in the southern pan of Cheju Island, Korea has a wetland in its crater being used as a farmland. Previous researchers presumed this wetland was a maar lake in the past. Based on the seismic refraction method, the wetland sediment layer was estimated between 5 to 14 m deep, which is mostly in accordance with previous researches. However, this shows only the depths at some sites, not representing the whole spatial distribution. This study is an attempt to reconstruct the volcanic lake in Hanon crater by applying the spatial statistical techniques based on the depth information from the seismic survey and known data. The procedure of reconstruction is as follows: First, the depth information from the seismic survey and known data were collected and it was interpolated by IDW and Ordinary Kriging method. Next, with the interpolation map and the present DEM the paleo DEM was constructed. Finally, using the paleo lake level on core data, the boundary of volcanic lake was extracted from the paleo DEM. The reconstructed lake resembles a half-moon in the north of the central scoria cone. It is estimated that the lake was 5 m deep on average and 13 m deep at the deepest point. Although there are slight differences according to the interpolation techniques, it is calculated that the area of the lake was between 184,000 and $190000m^2,$ and its volume approximately $869,760m^3$. Because of the continuous deposition processes after the crater formation, the reconstructed volcanic lake would not indicate an actual lake at a specific time. Nevertheless, it offers a significant clue regarding the inner morphology and evolution of the crater.

• Tunnel and Underground Space
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• v.17 no.2 s.67
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• pp.128-138
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• 2007

At low in-situ stress, the continuity and distribution of natural fractures in rock mass predominantly control the failure processes. However at high in-situ stress, the failure process are affected and eventually dominated by stress-induced fractures preferentially growing parallel to the excavation boundary. This fracturing is often observed in brittle type of failure such as slabbing or spatting. Recent studies on the stress- or excavation-induced damage of rock revealed its importance especially in a highly stressed regime. In order to evaluate the brittle failure around a deep underground opening, physical model experiments were carried out. For the experiments a new tue triaxial testing system was made. According to visual observation and acoustic emission detection, brittle failure grades were classified under three categories. The test results indicate that where higher horizontal stress, acting perpendicular $(S_{H2})$ and parallel $(S_{H1})$ to the axis of the tunnel respectively, were applied, the failure grade at a constant vertical stress level (Sy) was lowered. The failure initiation stress was also increased with the increasing $S_{H1}\;and\;S_{H2}$. From the multi-variable regression on failure initiation stress and true triaxial stress conditions, $f(S_v,\;S_{H1},\;S_{H2})$ was proposed.

• Membrane Journal
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• v.25 no.5
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• pp.373-384
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• 2015

In the past few decades, polymeric membrane has played an important role in gas separation applications. For the separation of $CO_2$, one of greenhouse gases, high permselectivity, long-term stability and scale-up are needed. However, conventional polymeric membranes have shown a trade-off relation between permeability and selectivity while inorganic materials are highly permeable but expensive. Mixed matrix membranes (MMMs) combining the advantages of both polymeric and inorganic materials have become a possible breakthrough for the next-generation gas separation membranes. The MMMs could be either symmetric or asymmetric but the latter is more preferred to improve the permeance. Important factors influencing the MMM fabrication include homogeneous distribution of inorganic particles and good interfacial contact between inorganic filler and organic matrix. Recently, metal organic frameworks (MOFs) have received much attention as a new class of porous crystalline materials and a potential candidate for $CO_2$ separation. Zeolitic imidazolate frameworks (ZIFs), a sub-branch of MOFs, are the most widely used in MMMs due to small particle size and appropriate pore size for $CO_2$ separation. One of the major issues associated with the incorporation of porous particles in a polymeric membrane is to control the microstructure of the porous particle materials such as particle size, orientation, and boundary conditions etc. In this review, major challenges surrounding MMMs and the strategies to tackle these challenges are given in detail.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.71-78
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• 2013

An exceptional case of inhabitation of a Sphagnum sp. was firstly confirmed at abandoned paddy terrace (APT) wetland in Ansan. Water sampling for analyzing of physicochemical conditions including nutrients such as NP, $Ca^{2+}$ and $Mg^{2+}$ was performed and the vegetation map for distribution of Sphagnum sp., topographical map, and flora list for companion species were made at field in June 2011. From the results, the Sphagnum sp. in the study site was identified as S. palustre and it covered about 8% of the wetland cover of 3,200 $m^2$. Most distributions of S. palustre were observed at tussock structures as micro-topography by sedges and grasses within a wetland (74%) and the shaded slope area under Pinus densiflora's canopy in wetland boundary (26%). Despite that APT in Ansan is relatively lower wetland in altitude than high moors, the contents of calcium ($0.45{\pm}0.2$) and magnesium ($1.48{\pm}0.6$) ion which are critical limiting factors for Sphagnum spp. were very low levels as well as NP ($PO_4$-P, $0.02{\pm}0.0$; $NO_3$-N, $0.25{\pm}0.3$; $NH_4$-N, $0.06{\pm}0.1$) and it could enable the inhabitation of S. palustre in lower APT.