• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.204-216
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• 2019

To evaluate the biological integrity of aquatic ecosystems, we developed Korean multimetric diatom index (KMDI) using metrics that many researchers have been previously described, and compared to single-metric diatom index such as trophic diatom index (TDI) and diatom assemblage index to organic pollution (DAIpo). For the biological and environmental data, we investigated the epilithic diatoms, water quality and the land-use for 923 sites in Korean streams between 2013-2017, and estuaries between 2010-2017, respectively. Five appropriate metrics were selected according to the following steps; 1) extraction of 300 potential metrics (biological, chemical, physical, and geographical) based on previous references, of these, 2) 46 samples having high separation power were selected, 3) the selected metrics were each tested for variability, redundancy, and sensitivity to the environments, finally 4) construction of multi-metric diatom index comprising single type metrics such as TDI, DAIpo, % motile diatoms, % Achnanthes / (Achnanthes+Navicula), and % number of Gomphonema species. The biological integrity of the 233 sites from the Geum River basin were independently investigated using KMDI. Collectively, the new KMDI showed high sensitivity and explanatory power for environmental factors such as land-use, biochemical oxygen demand, total nitrogen, and electric conductivity. However, it had slightly higher biological integrity for the same sites as compared to single type diatom metrics. Finally, more data accumulation from all over Korea and the development of acceptable diatom metrics were required.

• Journal of Environmental Impact Assessment
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• v.29 no.4
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• pp.298-306
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• 2020

This study was conducted to examine the impact of the correlation between habitat suitability of the Saemangeum lake area for otters and spatial variables (watersides, wetlands, farmlands, urban areas, roads, etc.) on the inhabitation of otters. As a result of the habitat suitability analysis, it was found that 380grids of 1097 grids (34.6%) studied are most suitable and suitable, whereas 413 grids of 1097 grids (37.7%) of the total are marginal and unsuitable. Comparatively analyzing otter traces data against for each spatial variable in the Saemangeum area revealed that the distance to the road or man-made areas is directly proportional to the number of otter traces, while more traces of otters were found areas close to waters. Despite the impact from the internal construction of Saemangeum lake, there found 2 to 6 times more otter traces in the area farthest from the urban areas and roads compared to the area nearest to the urban areas and roads. Thus, when restoring habitats for otters, a minimum of 500(m) distance to roads or urban areas, which can be considered as a threat to the habitats, must be secured.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.105-115
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• 2010

Recently, High-rise building are irregular-shaped to be city landmarks and function as vertical cities to enable the efficient use of land. 3T (Twisted, Tilted & Tapered) designs are being suggested for irregular buildings and studies to develop new structural system have been actively made to satisfy slender shape ratio. In diagrid system, not only gravity load but also lateral load is delivered based on the triangular shape of diagrid, so most of columns are eliminated. Because shearing force is delivered by the axial behavior (tensile/compressive) of diagrid to minimize shearing deformation, the system is more applicable to irregular buildings than existing system where shearing force is delivered by the columns. In this study, the process of selecting connection details and the structural safety of the selected details are verified using the finite element analysis with focus given to the construction overview of the Cyclone Tower. However, the relersed methods of stress concentration are suggested and the performance of stress concentration relieves that it's suggested for the appropriate cap plate thickness and extended length.

• Journal of Science and Technology Studies
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• v.18 no.2
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• pp.181-232
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• 2018

To explore the history of Korean engineers, one must navigate the field answering to the question of who engineers are. This is not an easy task because, behind the English expression of engineer, there are various names and even histories pertaining to technology related actors in East Asian countries including South Korea, and the meaning and status of these names are different from one another. Thus, the process and method of answering to the question of who engineers are becomes the path to understanding the history of Korean engineers. This study, therefore, attempts to suggest research questions that should be raised to study Korean engineers and to find research methodology suited for addressing those questions. Until now, not enough efforts have been made to create and expand interdisciplinary discussions and contacts for this area of study. This study has some theoretical difficulties of having to combine concepts with different problematique. Nevertheless, it aims to discuss how to conduct research, what questions should be posed to analyze the construction of Korean engineers and what research methodologies are suitable for such research, based on previous researches conducted in the field of social science. Answers to the quest are sought through genealogy, conceptual history, actor-network theory, and the notion of techno-national formation.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.797-807
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• 2008

For this study, the semi-adiabatic temperature rising test is accomplished by using ternary system cement (OPC, BFS, FA) reducing temperature crack. Two tests are conducted; one is for the paste test, and the other is for the concrete test. As the results of paste tests, using fly ash is better to reduce hydration temperature than doing blast furnace slag. In the case of the paste mixed ternary system cement, the more fly ash is mixed and the less blast furnace slag is used, the lower the temperature is. The less the mixture ratio of blast furnace slag is and the more the mixture ratio of fly ash is, the later the temperature rising velocity and descending velocity are. Besides, the temperature is lower if water/binder ratio is high. The use of ternary system cement has the retardation effect of temperature rising because the time to reach the maximum temperature is in the order of OPC100, binary system cement, and ternary system cement. From the test, the maximum temperature of concrete used ternary system cement is $8{\sim}11^{\circ}C$ lower than that of concrete used OPC100. Moreover, temperatures rising velocity and descending velocity of ternary system cement range $47{\sim}51%$ and $37{\sim}42%$ compared with OPC100. The specimen of concrete shows remarkable low internal temperature and slow temperature rising velocity and descending velocity compared with the specimen of paste because it is that temperature loss of concrete is much more than paste specimen according to aggregates.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.191-200
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• 2003

This paper presents the rheological properties of bitumen for reducing negative skin friction. The bitumen has been widely used due to both the cost and construction effectiveness. Also, it is well known that the use of bitumen for reducing negative skin friction renders the best results among other available methods. Three different modified bitumens were used for the testing programs. The physical tests include the penetration, the softening point and penetration index. The rheological tests include phase angle, complex modulus, creep tests and flow tests. The tests were conducted at four different temperatures(15, 30, 45 and 6$0^{\circ}C$) in order to simulate the field condition. The test results were analyzed using the phase angle, G$^*$/sin $\delta$, creep compliance and shear viscosity. The result of tests showed that the phase angle increased and G$^*$/sin $\delta$ decreased with the increase of temperature. The creep compliance increased as the loading time increased. The difference of the creep compliance is detected as the time and temperature are varied, however, the difference of the shear viscosity is not significant among the samples tested in this study. The rheological properties of the bitumen also showed that the physical testing method and the temperature dependant testing method are somewhat limited to showing and expressing the full rheological properties of the modified bitumen. The introduction of the time and the temperature dependent testing method is necessary to find out the full rheological properties of the modified bitumen.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.135-147
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• 2013

Most of slope failures are triggered by heavy rainfall during rainy season. If the rain keeps on for the season, the water content of the ground increases and its matric suction decrease, and then the safety factor of soil slope gets lower. The change of water table level for soil slope stability dose not describe the behavior of the soil slope in real situation, hence it may be necessary to modify the design standard for slope stability in association with rain infiltration. For correct design, economical construction, and maintenance of a soil slope, unsaturated flow analysis is needed for estimation of slope instability regarding water infiltration and soil behavior on unsaturated soil slopes. The entire soil slope cannot be saturated by prolonged rainfall and wetting band depth (saturated zone) just deepens from slope surface, hence the cause of the shallow surface slide is the wetting band depth depending on rainfall duration and intensity. Therefore, the paper presents the differences between theoretical equation and numerical analysis for wetting band depth on soil surface and its safety factor, and compares the slope stability obtained from unsaturated flow analysis with that obtained from conventional slope stability analysis.

• Journal of Distribution Research
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• v.16 no.5
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• pp.43-61
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• 2011

In this research, we analyze about the effect of the traditional market supporting policy about 16 large unit self-governing bodies and effeciency through DEA analysis. The plan for supports of the traditional market were shown. Now, the object of the traditional market supporting policy was any more not improvement of facilities and the thing which is the attraction of customer activity for the sales increase of the traditional market could be confirmed. For the sales increase, supporting of the field like the client information center, source indicator, autonomic packing stand, and the broadcasting facility are effective more. In addition, for the visiting customer inducement activation, we could know that supporting of the field like client information center, broadcasting facility, broadcasting advertisement, and the premium event for gift certificate were required. The method including the customer distribution service operation, which is the various product development and cross sellings and client friendly based on data which it investigates the actual conditions the market merchant on the Incheon area and consumer with the concrete plan for support gift certificate activation, the market information system construction, and etc. was shown.

• Journal of the Korean Geosynthetics Society
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• v.16 no.1
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• pp.1-8
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• 2017

Displacement of dams by various instrumentations has been monitored for its safety management and analyzing the behavior after a dam collapse accident. However, unknown displacement of dam has frequently been occurred and it's difficult to analyze behavior of dams more accurately. In this study, improvement of reliabilities for displacement of dams measured by a total station was suggested by calibrating the monitoring system. The position of total station was initially measured through 2-3 given points and the coordinate of the total station was considered as an absolute value. Also, base horizontal and vertical angles had not been considered even if they are important factors when displacement was estimated. In this study, location of the total station and variations of base horizontal and vertical angles were investigated during measuring displacements of targeting points. From the results of this study, they are important factors which are affecting measurements of dam displacements. Before the calibrating, the displacement at 50 m from total station was ${\pm}20mm$. After the calibrating, the displacement was decreased by ${\pm}5mm$.

• Journal of Energy Engineering
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• v.21 no.3
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• pp.281-291
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• 2012

Recently, global economy has recovered and aspects of the renewable energy industry in the global competition is more fierce, the new growth engines of the major countries, including the United States and China, industry promotion policy as being deployed. Major advanced countries and Korea also invested a lot of money to wind power development as a part of renewable energy development and promoting the construction of wind power generation. The global wind power generation market is expected to further increase the scale to about 70 billion US dollars, thus, Korea as well as the installation of domestic wind power overseas actively considering. This study uses input-output analysis to estimate the role of wind power generation sector exports national economy. More specifically, this study shows what national economy effect of production-inducing effect, value-added inducing effect, and employment-inducing effect are explored with demand-driven moel. After define wind power generation sector what small sized of Input-Output table 168 sectors among 11 sectors, this study pays particular and close attention to wind power generation sector by taking the sector as exogenous specification and then investigating economic impacts of it. The wind power generation exportation case of overseas 100 billion won, production-inducing effect, value-added inducing effect, and employment-inducing effect are 205 billion won, 68 billion won and 1,054 persons, respectively. These quantitative information can be usefully utilized in the policy-making for the industrialization of wind power generation exports.