• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.347-359
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• 1996

This study was carried out to find the plant succession stage on highway cut-slopes. In order to analyze succession stage, plant survey with belt transect method was carried out in 1989 and 1995 at Joongbu-highway cut-slopes. The results could be summarized as follows ; The mean plant coverage of cut-slope was 78.3%. Plant coverage of Lower part area was higher than that of upper part area. Pioneer herb species on cut-slope were Miscanthus spp., Arundinella spp., Artemisia spp. etc., and pioneer woody species were Rubus crataegifolius, Robinia pseudoacacia, Pueraria thunbergiana, Pinus spp. etc. Also, among the introduced turf grasses, Eragrostis curvula is the pioneer species. Due to short of maintenance works, Zoysia japonica which has been planted by sodding work was found to decrease or diminish gradually. The ratio of pioneer stage plants, domestic and introduced herb species, seems to decrease, while the ratio of woody species which are advanced stage plants seems to increase. Maintenance works are needed to management and monitoring of plant succession on cut-slope, and use of herb and woody species will be effective.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.401-406
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• 2003

Electric power industries in several countries are currently undergoing major changes, mainly represented by the privatizations of the power plants and distribution systems. Reliable operations of the power plants directly contribute to the revenue increases of the generation companies in such competitive environments. Strategic optimizations should be performed between the levels of the reliabilities to be maintained and the various preventive maintenance costs, which require the accurate estimations of the power plant reliabilities. However, accurate estimations of the power plant reliabilities are often limited by the lack of accurate power plant failure data. A power plant is not supposed to be failed that often. And if it fails, its impact upon the power system stability is quite substantial in most cases, setting aside the significant revenue losses and lowered company images. Reliability assessment is also important for Independent System Operators(ISO) or Market Operators to properly assess the level of needed compensations for the installed capacity based on the availability of the generation plants. In this paper, we present a power plant reliability estimation technique that can be applied when the failure data is insufficient. Median rank and Weibull distribution are used to accommodate such insufficiency. The Median rank is utilized to derive the cumulative failure probability for each ordered failure. The Weibull distribution is used because of its flexibility of accommodating several different distribution types based on the shape parameter values. The proposed method is applied to small size failure data and its application potential is demonstrated.

• Journal of the Korea Safety Management & Science
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• v.19 no.3
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• pp.35-42
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• 2017

Process Hazard Analysis(PHA) have been performed for a risk management of process (petrochemical) industry for nearly 50 years. There are many PHA methods for application in the process industry, Hazop Study method has been recognized as a good method used typically in most of phase of process plant. And also there was inconvenient opinion that Hazop Study is too resource (man power, time etc.) consuming comparing its result performance (a quality of recommendations) for a good operating and existing plant. In this study, two types of PHA method - checklist and K-PSR - were performed respectively for a new para-xylene(PX)plant and 30 year old PX plant. Past history and experience of incident, operation, maintenance and so on are very important in PHA by those two methods. The higher effectiveness were realized in PHA by a checklist and K-PSR Method than prior Hazop study. And also some suggestions including PHA cycle determination, RBPS application, Follow-up plan of PHA result etc. were proposed about PHA improvement measures for a best risk management.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.180-185
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• 2012

Tidal power is one of new and renewable energy sources. The seawater is stored inside a tidal embankment built at the mouth of a river or bay, where tides ebb and flow. The water turbine-generators produce power by exploiting the gap in the water level between the water outside and inside the embankment. Tidal power plant is a large plant that is installed on the sea. And then, the facility's operations and a separate control system for monitoring and maintenance is required. However, this plant predictive control of building systems and technologies have been avoided the transfer of technology from advanced global companies. Accordingly, the control system for core technology development and localization is urgently needed. This paper presents modeling and simulation using by PSS/E about generator, governor, exciter, and power system stabilizer for control system in Sihwa tidal power plant to improve the efficiency and develope of core technology. And the dynamic characteristics of governor and exciter were analyzed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.5
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• pp.1-9
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• 2005

This study was conducted to investigate the effect of aquatic plant as a botanical air purification on the indoor air pollution by formaldehyde. Three aquatic plants such as Eichhornia crassipes, Cyperus alternifolius, Echinodorus cordifolius, were selected for this study and they were placed in the artificially contaminated chamber under laboratory condition. The results showed that all three plants could remove the formaldehyde from the contaminated air system effectively. Reduction in the formaldehyde levels by Eichhornia crassipes, which is the floating plant, might be associated with the factors of plant and water. Reduction in the formaldehyde levels by Cyperus helferi and Echinodorus cordifolius, which were emergent plant, was due to the complex effect of plant, soil medium and water. In aquatic plant system, dissolution, microbial degradation in rhizosphere, uptake through root and shoot, sorption to soil and shoot, hydrolysis are known as the main mechanisms of water soluble pollutants in the given system. The advantages of indoor air quality control system using aquatic plants can be; 1) various purifying mechanisms than foliage plants, 2) effective for decontamination of water soluble pollutants; 3) easy for maintenance; 4) diverse application potential. Therefore it was suggested from the results that indoor air control system of aquatic plants should be more effective for reduction of indoor air pollutants.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.1 no.2
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• pp.144-153
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• 1991

This study was conducted to evaluate worker exposure to airborne asbestos fibers by industry, and to evaluate polarized-light microscopy for determining airborne asbestos fibers. A total of 11 plants including asbestos textile, brake-lining manufacturing, slate manufacturing, and automobile maintenance shops were investigated. Rsults of the study are summarized as follows. 1. Worker exposure levels to airborne asbestos fibers were the highest in asbestos textile industry, followed by brake-lining manufacturing, slate manufacturing, and automobile maintenance shops, in order. In asbestos textile industry, large variation of asbestos levels was found by plants. The worst plant indicated airborne fiber concentrations in excess of 10 fibers/cc, however, the best plant showed concentrations within 0.50 fibers/cc. 2. Characterization of airborne fibers by industry indicated that fibers from asbestos textile industry were the longest with the largest aspect ratio. Fibers from automobile maintenance shops were the shortest with the smallest aspect ratio. Based on characteristics of fibers and the highest levels of concentrations, it is concluded that workers in the asbestos textile industry are exposed to the highest risk of producing asbestosis, lung cancer, and mesothelioma. 3. Result s obtained using polarized-light microscopy were $43.7{\pm}12.3%$ of the results obtained using phase contrast microscopy. This may be resulted from the worse resolution of polarized-light microscopy than that of phase contrast microscopy. Based on the results, it is recommended that polarized-light microscopy be used for mainly bulk sample analyses and further study be performed to improve the method for determining airborne samples. However, polarized-light microscopy can be used for determining thick fibers.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.4
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• pp.75-86
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• 2018

This research was thereby made to study and analysis ecological, landscape, and stability qualities of roadside cut Slopes in expressways and national highways that went through revegetation works. Also, evaluation items and framework for integrated assessment of plant structure and restored state for the maintenance were suggested. Following is the summary of the result. firstly, for stabilization of introduced native plant species on roadside cut slops, assessment on the post-project environmental management through long-term monitoring and maintenance works must be made. It signifies a form of authentic recovery and restoration by the native plants. second, current evaluation framework on the test beds is well managed with clear evaluation standards and table while its method of assessing the post management with only test bed results lacks conformity with this study site. Newly developed evaluation framework on the post construction sites is estimated to be used as assessment standards on any roadside construction sites. Third, after site investigation distinction was observed among different revegetating construction types in the long-term perspective. Due to the different duration time of vegetation state between seed-spray measures(degraded in time) and layer-spray measure(maintained), the use of coarse straw-mat mulching work or Coir net was suggested in long term maintenance of cut slopes. forth, segmentation of post environmental assessment is organized into three large categories of "ecological", "stabile", and "landscape" qualities regarding post restoration quality and stability of slope through native plants with which categories marks 50, 30, 20 points of rates. fifth, components of the post environmental assessment were segmented in twelve categories driving results from former experimental construction and newly focused items on site. In the future, it is possible to propose a customized assessment method considering the location and location of construction work if the research on the application of post-environment assessment methods for road construction surface recording is conducted systematically.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.219-224
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• 2019

The number of solar power installation companies including domestic small scale (50kW or less) is increasing rapidly, but the efficient operation system and management are insufficient. Therefore, a new type of operating system is needed as a maintenance management aspect to maximize the generation amount in the current state rather than the additional function which causes the increase of the generation cost. In this paper, we utilize Big Data and sensor network to maximize the operating efficiency of solar power plant and analyze the expert system to develop power generation prediction technology, module unit fault detection technology, life prediction of inverter components and report technology, maintenance optimization And to develop a smart monitoring system that enables optimal operation of photovoltaic power plants such as development of algorithms and economic analysis.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.5
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• pp.53-67
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• 2011

The major objective of this study was to quantify the effects of substrate depth and substrate composition on the development of sedum etc., in a sloped rooftop (6 : 12 pitch) environment during a 4-year period. The experiment was conducted from 2006 October to 2010 December under several conditions without soil erosion control : two substrate depth (5cm, 10cm), four substrate composition (A5N3C2, A3N3C4, A6C4, G5L3C2: A: artificial lightweight soil, N : natural soil, G : granite decomposed soil, C : leave composite, L : loess), four sloped roof direction ($E40^{\circ}W$, $W40^{\circ}N$, $S40^{\circ}W$, $N40^{\circ}E$). In this experiment 4 sedum etc., were used: Sedum sarmentosum, Sedum kamtschaticum, Sedum rupestre, Sedum telephium, flowering herbs (mixed seed : Taraxacum platycarpum, Lotus corniculatus, Aster yomena, Aster koraiensis), western grasses (mixed seed : Tall fescue, Creeping redfescue, Bermuda grass, Perennial ryegrass). The establishment factor had two levels : succulent shoot establishment (sedum), seeding (flowering herbs, western grasses). 1. Enkamat, as it bring about top soil exfoliation, was unsuitable material for soil erosion control. 2. Sedum species exhibited greater growth at a substrate depth of 10cm relative to 5cm. All flowering herbs and western grasses established only at a substrate depth of 5cm were died. A substrate depth of 5cm was not suited in sloped rooftop greening without maintenance. If additional soil erosion control will be supplemented, a substrate depth of 10cm in sloped rooftop greening without maintenance was considered suitable. 3. For all substrate depth and composition, the most abundant species was Sedum kamtschaticum. The percentage of surviving Sedum kamtschaticum was 73.4% at a substrate depth of 10cm in autumn 2007 one year after the roof vegetation had been established. But the percentage of surviving other sedum were 33.3%~51.9%, therefor mulching for soil erosion control was essential after rooftop establishment in extensive sloped roof greening was proved. To raise the ratio of plant survival, complete establishment of plant root at substrate was considered essential before rooftop establishment. 4. There was a significant interaction between biomass and substrate moisture content. There were also a significant difference of substrate moisture and erosion among substrate composition. The moisture content of A6C4 was highest, the resistance to erosion of A5N3C2 was highest among substrate composition. The biomass of plants were not significantly higher in A5N3C2 and A6C4 relative to A3N3C4 and G5L3C2, For substrate moisture and erosion resistance, A5N3C2 and A6C4 were considered suitable in sloped rooftop greening without maintenance. 5. There were significant difference among roof slope direction on the substrate moisture. Especially, the substrate moisture content of $S40^{\circ}W$ was lower relative to that of $N40^{\circ}E$, that guessed by solar radiation and erosion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.788-796
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• 2001

VR(Virtual reality) technologies have given engineers the ability to design, test, and evaluate engineering systems in a virtual environment. The virtual plant is the highlight of the application of the VR technology to plant engineering. Plant design, maintenance, control, management, operation are integrated in the virtual plant. The VR monitoring system including the concept of the virtual plant is developed to replace a current control room that has number of gages and warning lamps in two-dimensional panels which shows the operating status of a plant. The operating status of the plant is displayed in the VR monitoring system through the realistic computer graphics. Sophisticated, realistic and prompt control becomes possible. The VR monitoring system consists of advanced visualization, walk-through simulation and navigation. In the virtual environment, a user can navigate and interact with each component of a plant. In addition, the user can access the information by just clicking interesting component. The VR monitoring system is operated with various modules, such as (1) virtual plant constructed with Graphic Management System (GMS), (2) Touch & Tell System, and (3) Equipment DB System of Part. In order to confirm the usefulness of the VR monitoring system, a pilot gas plant which is currently being used for plant operator training is taken as application. The end of the paper gives an outlook on the future work and a brief conclusion.