• 한국해양학회지
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• v.12 no.2
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• pp.57-66
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• 1977

Chlorophyll concentrations of phytoplankton were determined by 5 meters interval from surface to bottom layers in Yeongil Bay water of Korea, late October 1973. The contents of phytoplankton chlorophyll decreased outward from the inner part to the entrance of the Bay. It seemed to be caused by incoming land waters which are rich in nutrients. And vertical distribution pattern of the chlorophyll showed three layer zones in the middle and outer parts, and two layers in the inner part of the Bay. These phenomena suggest that there are two different water masses, the one is bottom cold water originated from offshore, the other is surface warm water. And they are mixed together in the middle layer The correlationship between the contents of chlorophyll a and chlorophyll c represented perfect positive relation with coefficient of r 0.999 from the extracted data. In general, chlorophyll a percent-content of total chlorophyll varied in the range of 14.64∼19.83% (mean value; 18.74%) and chlorophyll c content was about as much as four times compared with chlorophyll a content.

• Journal of Conservation Science
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• v.23
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• pp.67-72
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• 2008

This study was conducted to examineboth the type of wood decay and the degree of degradation for the waterlogged woods (Alnus spp. and Fraxinus spp., about 5,700~5,900 year old), which were excavated at Higokri, Pyungteak in the west-coastal region of Korea. The transmission electron microscope (TEM) observation indicated the degradations by soft rot and bacteria were common in both woods. Erosion bacteria attacked gradually and irregularly from the secondary layer to compound middle lamella and often produced the cavity which was similar to soft-rot cavity but much smaller ones. Tunneling bacteria decomposed mainly $S_2$ layer. Though of highly degraded walls, the cells almost kept the original form with intact lignin-rich middle lamella, which were saturated by water. No marine borer's trace indicated that the sealine rise in the western coast of Korean peninsula during the climate optimum period in the holocene might not be high enough to submerge the Higokri area which locates about 2 km from the present sealine.

• Journal of the Korean Institute of Landscape Architecture
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• v.14 no.3
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• pp.33-45
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• 1987

The Seonjeong royal tomb is one of many historic sites in and around Seoul city and its natural environment and landscape have born damaged seriously by heavy use. So conservation planning with an estimation of reasonable carrying capacity shall be required In aspect of not only historic site conservation, but also urban forest and nature park management. Eight sites were sampled with clumped sampling method during July of 1986 and five quadrats were examined in each site. Environmental factors, actual vegetation, and environmental impact grade were investigated in field and vegetational structure was analyzed by estimation of importance value, species diversity, similarity index, DBH class distribution, etc. The result of this study can be summarized as follows. 1. Damage on soil and vegetation of middle and lower layer increased according to amount of users'impact. 2. Semi - natural vegetation covered 63% of the total area(22.2 ha) and its major species were Pinus densiflora, Quercus aliena, Q mongolica, Sorbus alnifolia, etc. Pinus densiflora was a dominant species in heavy impact area. 3. Environmental impact grade 3, 4 and 5 area covered 51% of the seminatural vegetation, Especially, the area of impact grade 4 and 5 should be restored because self-refair seemed to be impossible. 4. The semi-natural vegetation was classified with four plant communities; two P.densiflora comm., Q. mongolica-P. densiflora comm. and Q. aliena comm. One of the P. densifolra comm. was destroyed seriously with no younger trees in middle and lower layer by overuse impact and would be bareland soon. But Q. aliena comm.in light impact area showed just completion of plant succession from P. densiflora comm.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.261-270
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• 2002

The artificial aeration in the middle and the small scale reservoirs is widely used to destroy the stratified layer and algal boom. This study has been conducted at the Youncho reservoir located in Keoje island since Jan. 2000 to suggest the most suitable control strategy of the artificial aeration and reduce the side effect. The main results obtained from this research are as follows. The starting time of aeration for destratification was adjusted from the end of March to the beginning of April when the natural stratification is started. In order to prevent an anoxic condition the artificial mixing should be started by the middle of April when the DO in hypolimnion is dropped to less than $5mg/{\ell}$. The decrease DO, caused by the increase in water temperature, spreads rapidly from hypolimnion to themocline. Thermal stratification disappeared after the onset of artificial aeration within 7 days in the Yuncho reservoir. The air diffusers decrease water temperature in the layer of epilimnion and thermocline, but rise it in hypolimnion. The continuous operation of air diffuser prevent the stratification and anoxic condition in hypolimnion despite of the rising of water temperature and algal abundance. The algal abundance is not observed in effective zone by aeration. The turbidity rising problem induced from the aeration is avoided by keeping an air diffuser about 1.5m high from the bottom of lake. During the summer season, ceasing the aeration should be decided carefully. And also, it is necessary to operate the system it considering weather and temperature, and depending on the number and the position of aerators.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.1
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• pp.67-75
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• 1993

This study is to analyze both root growth and soil moisture extraction pattern during the growing period of upland crops with respect to soybean, redpepper, sesame. Field and lysimeter tests were conducted under 12 treatments of soil moisture level by the San Cristobal experimental design(1981) and 3 soil type(sand, sandy loam, silty loam) for 4 years('87-'90) at the experimental plot of Rural Development Administration located in Suwon. The results of this study are summarized as follows : 1.For soybean, redpepper and sesame, root growth in dry soil was better than that in wet soil and it could be expressed as a sin function in terms of time. Maximum root depth was about 55cm, 44cm, 40cm respectively. 2.The average soil moisture extraction pattern for soybean, redpepper and sesame were 61.4%, 62.8%, 79.5% for zone l(0-l5cm). 25.5%, 27.1%, 18.3%, for zone 2(15-30cm).11.4%, 9.8%, 2.3% for zone 3(30-45cm), 1.7%, 0.3%, 0.04% for zone 4(45-60cm) respectively. This means that Zone 1 would be the dominant zone in irrigation scheduling. 3.With respect to soybean, the soil moisture extraction pattern(SMEP) was varied somewhat according to the erent maintenance of soil moisture level. The average SMEP for high maintenance of soil moisture was 46%, 29%, 17%, 8%, for middle maintenance of soil moisture was 43%, 29%, 17%, 11 % and for low maintenance of soil moisture was 40%, 28%, 20%, 12%, respectively. 4.With respect to soybean, the soil moisture in the upper layer was distinctly consumed more than that in the lower layer for clay loam soil and the soil moisture of all layers was consumed evenly for sand soil. The SMEP for sandy loam soil showed a middle result compared with the above 2 soil types.

• 한국해양학회지
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• v.24 no.3
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• pp.121-131
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• 1989

Cold water observed at sea surface near the southeastern coast of Korea in summers 1982 and 1983 was studied by using data of hydrography, sea level, wind and satellite image. In summer season when water column shows 3-layered structure a "full" upwelling occurs by southwesterly transient wind continuing for several days. During upwelling event, surface water of high temperature moved offshore, middle water of low temperature outcropped to the sea surface, and sea level was lowered, however, equilibrium depth of surface layer was not changed. It may be concluded that cold water at the surface originates from middle layer and strong surface front is a result of surfacing of seasonal thermocline. In order to see the relationship between position of surface front and wind input, a model of Csanady (1982) was applied in a rigid lid approximation. The results show that frontal position can be determined by wind input and water structure near the southeastern coast of Korea. Cold water in summer can appear at the sea surface only when there is wind larger than a minimum wind impulse of order $10m^2/sec$.

• Journal of the Korea Furniture Society
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• v.11 no.2
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• pp.7-12
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• 2000

This paper describes the bending strength properties of laminated woods which had three kinds of specimens according to finger length-12, 4.5 mm and butt joint and the acoustic emissions (AEs) generated during the test. 3-ply laminated wood beams were tension side layers (lower layers) composed of one middle lamina and two side-jointed laminae, with one butt joint ($_1BJ$), one finger joint (12mm, $_1FJ_{12}$) or one finger joint (4.5mm, $_1FJ_{4.5}$) in the middle lamina of tension side layer. And 3-ply laminated wood beams were tension side layers (lower layers) also composed of one lamina, with one butt joint (BJ), one finger joint (12mm, $FJ_{12}$) or one finger joint (4.5mm, $FJ_{4.5}$/) in tension side layer. Cryptomelia pieces were cut for butt and two finger types and glued with resorcinol-phenol resin adhesive. The results were as follows It was not effective in the bending modulus of elasicity (MOE) with IFJL type and had no difference from finger length. The bending modulus of rupture (MOR) of laminated wood beams including finger joint was the same values as that including butt feint and had no difference from finger length. It was effective in MOE with FJL type and had no difference from finger length. The effect of finger joint on MOR was much higher than that of butt joint but had no difference from finger length. The AE generation time of IFJL type was earlier than that of the control wood and the number of AE count was much more than that of the control wood. However, the AE generation time of FJL type was earlier than that of the control wood and the number of U count was much fewer than that of the control wood.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.335-343
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• 1996

The dipole-dipol electrical resistivity survey was conducted to investigate the probable contamination of the Han river by leachate from the near-by Nanjido Landfill. The survey line of 3 km was set along the unpaved road toward the Han river. For the convenience of the field work, the survey line was divided into four segments. The complete two-dimensional resistivity section was constructed by connecting the inversion result of each segment. Gravity survey was also carried out along the profile parallel to the resistivity line. Near surface resistivity generally appeared to be of very low value in most part of the survey area and the boundary between the alluvium layer and underlying basement rocks is well discriminated on the resistivity section. These results agree well with those of the preceding Schlumberger depth sounding made at adjacent area by Lee and fun (1995). The variation of thickness of the alluvium layer delineated by gravity anomaly profile also correlates well with the result of the resistivity survey on the qualitative basis. The problem of contamination by leachate from the Nanjido Landfill, where various waste materials have been dumped without any proper treatment facilities, has been remains unsolved yet. Therefore, we present the most probable passages of leachate flow based on the survey results and have briefly discussed about measure for contamination control. Considering the thickness of alluvium and the possible existence of fractured zone, the middle point between 1st and 2nd landfill and the midst of 1st landfill are the most hazardous regions to make leachates flow into the Han river. Since large amounts of leachates are observed from the test wells located on the lines extending from the border between the 1st and 2nd landfill and the middle of the lst landfill, contamination protection barriers are strongly recommended near these regions.

• Journal of Digital Contents Society
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• v.19 no.6
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• pp.1185-1195
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• 2018

Industrial Control System (ICS) is a system that carry out monitoring and controls of industrial control process and is applied in infrastructure such as water, power, and gas. Recently, cyber attacks such as Brutal Kangaroo, Emotional Simian, and Stuxnet 3.0 have been continuously increasing in ICS, and these security risks cause damage of human life and massive financial losses. Attacks on the control layer among the attack methods for ICS can malfunction devices of the field device layer by manipulating control commands. Therefore, in this paper, we propose a mechanism that apply the SDN between the control layer and the field device layer in the industrial control system and to determine whether the control command is legitimate or not and we show simulation results on a simply composed control system.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.5
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• pp.47-56
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• 2004

This study was carried out to analyze forest vegetation of the Jangtaesan, Haetaesan, Ahnpyoungsan and Gubongsan in Daejeon. Employing the releve method of Braun-Blanquet, 76 plots were sampled. The communities were classified into Quercus mongolica community, Quercus variabilis community, and Pinus densiflora community. Average coverage rate was 85% in tree layer, 44% in subtree layer, 37% in shrub layer, 25% in herb layer, respectively. The importance values were 58.76 in Pinus densiftora, 44.86 in Quercus monegolica, 44.06 in Quercus variabilis, 33.00 in Quercus serrata, 18.73 in Rhus trichocarpa, 18.07 in Prunus sargentii. DBH range of most Pinus densiflora, Quercus mongolica and Quercus variabilis was between 5cm and 20cm. Therefore, Pinus densiflora, Quercus mongolica and Quercus variabilis will be dominant species in the study area for several more decades. Quercus mongolica community was distributed mainly on the north and east slope in a high-altitude and relative good nutrition condition. Querucus variabilis community was distributed mainly on the south slope in a middle-altitude and medium nutrition condition. Pinus densiflora community was distributed mainly in a low-altitude and poor nutrition condition.