• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1725-1731
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• 2013

Recently, as industrial society is developed as high digital information age, image processing is used in a variety of areas. However, image deterioration is still occurred by several noises in the data processing, and different kinds of researches are in progress for noise removal. Therefore, this paper limited the modified median filter by using standard deviation to removes impulse noise. The proposed algorithms divided into noise detection and noise removal, the noise free pixel is maintained, the noise pixel filtered. And it was compared with the existing methods for its objective judgment, using PSNR(peak signal to noise ratio) as standard criteria.

• Journal of Korea Water Resources Association
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• v.40 no.12
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• pp.969-983
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• 2007

This study developed a ten-step procedure of integrated watershed management (IWM) for sustainability to rehabilitate the distorted hydrologic cycle and identified spatial hazard ranking(step 2). Spatial hazard indices, Potential flood damage (PFD), potential streamflow depletion (PSD), potential water quality deterioration (PWQD), and watershed evaluation index (WEI) were developed using multi-criteria decision making (MCDM) techniques and sustainability evaluation concept(pressure-state-response model). The used MCDM techniques are composite programming, compromise programing, Regime method, and EVAMIX approach which are classified by data availability and objectives (prefeasibility and feasibility).

• Journal of Wetlands Research
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• v.22 no.1
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• pp.31-38
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• 2020

Weirs are to secure amount water of streams and drop structures are to enhance stabilization of stream bed and bridges are to connect isolated region, which are called stream crossing structures. In the stream design criteria, directions for minimum size of structures are suggested to secure stability of stream crossing structures. However the sizes of almost all existing weirs and drop structures are not satisfied with the stream design criteria and only 22 percent of the peirs of bridges are satisfied. To enhance hydraulic stability of existing weirs and drop structures, it is required that the ratio of bed protection to apron should be above 3.3. According to factual survey of structures in the sample streams, it has been shown that the longitudinal slope of rapid works with 1:20 is the most reasonable to design velocity if existing weirs and drop structures are rehabilitated into rapid works. It has been known that violating freeboard and span length of piers should make existing bridges reconstructed or removed. However, comprehensive review including deterioration level of bridges, special regulation for span length, etc. should be considered to determine rehabilitation plan of bridges. In this study, a procedure has been suggested to improve hydraulic stability of weirs, drop structures and piers of bridges. Sound environment of stream and reduction of natural disaster could be achieved by improving stability of cross structures, which could be obtained by governmental budget and active stream management including observance of design criteria.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.14-14
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• 2011

Groundwater in the Waikatoregion is a valuable resource for agriculture, water supply, forestry and industries. The 434,000 ha study area comprises the upper Waikato River catchment from the outflow of Lake Taupo (New Zealand's largest lake) through to Lake Karapiro (a man-made hydro lake with high recreational value) (Figure 1). Water quality in the area is naturally high. However, there are indications that this quality is deteriorating as a result of land use intensification and deforestation. Compounding this concern for decision makers is the lag time between land use changes and the realisation of effects on groundwater and surface water quality. It is expected that the effects of land use changes have not yet fully manifested, and additional intensification may take decadesto fully develop, further compounding the deterioration. Consequently, Environment Waikato (EW) have proposed a programme of work to develop a groundwater model to assist managing water quality and appropriate policy development within the catchment. One of the most important and critical decisions of any modelling exercise is the choice of the modelling platform to be used. It must not inhibit future decision making and scenario exploration and needs to allow as accurate representation of reality as feasible. With this in mind, EW requested that two modelling platforms, MODFLOW/MT3DMS and FEFLOW, be assessed for their ability to deliver the long-term modelling objectives for this project. The two platforms were compared alongside various selection criteria including complexity of model set-up and development, computational burden, ease and accuracy of representing surface water-groundwater interactions, precision in predictive scenarios and ease with which the model input and output files could be interrogated. This latter criteria is essential for the thorough assessment of predictive uncertainty with third-party software, such as PEST. This paper will focus on the attributes of each modelling platform and the comparison of the two approaches against the key criteria in the selection process. Primarily due to the ease of handling and developing input files and interrogating output files, MODFLOW/MT3DMS was selected as the preferred platform. Other advantages and disadvantages of the two modelling platforms were somewhat balanced. A preliminary regional groundwater numerical model of the study area was subsequently constructed. The model simulates steady state groundwater and surface water flows using MODFLOW and transient contaminant transport with MT3DMS, focussing on nitrate nitrogen (as a conservative solute). Geological information for this project was provided by GNS Science. Professional peer review was completed by Dr. Vince Bidwell (of Lincoln Environmental).

• Korean Journal of Heritage: History & Science
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• v.52 no.3
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• pp.188-199
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• 2019

In this study, research trends were investigated by examining important academic research on museum lighting that has been carried out in Korea over the past 30 years. The aim was to highlight important studies conducted in Korea on material deterioration caused by museum lighting and to examine the current status of research on LED light sources to provide direction for future research. The ultimate goal of studies on museum lighting is to improve the long-term conservation effects, and this study examined the latest light sources of each era. Prior to the 1990s, the effects of light sources on relics were assessed by investigating incandescent light bulbs and fluorescent lamps, the first museum exhibition lighting. Then in the 1990s, the introduction of halogen lamps and HID lamps led to the analysis of the characteristics of a light source itself and the introduction of illumination standards. In the 2000s, the lighting environment of museums was investigated based on the characteristics of the light sources that had been studied, and in terms of preservation, research was conducted not only to improve the conservation of relics but also to improve the sentiments of visitors. After 2010, LED lamps were introduced; therefore, material deterioration studies on LED lamps were expanded. During this period, enhancements to LED light sources were made, such as reducing the blue spike area and increasing color rendering. With the development of lighting used in museums and art galleries, the direction of the display preservation criteria has led to the need to prepare advanced standards, covering all aspects from the center of illumination to the consideration of the color of an object and the speed of radiation from the light source. Regular studies of museum lighting in a long-term perspective should be planned to standardize the more advanced conditions of material discoloration.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.128-135
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• 2016

In the current concrete structure of the highway is still the major problem most of concrete deterioration caused by the freeze-thaw and deicing salt, which is of issues that are not completely resolved. In particular, a single freezing event does not cause much harm, durability of concrete under multi-deterioration environment by repeated freeze-thaw and deicing salt is rapidly degraded and reduce its service life. In this study, the exposure environmental condition according the regional highway points were established. The damage condition and chloride content of the concrete at general and severe environmental exposure condition were also investigated. In addition, the experimental test of chloride ion permeability, scaling resistant and freeze-thaw resistance were carried out to improve the durability of the mechanical placing concrete of subsidiary structure. According to the results of this study, in observation of concrete surface condition, the concrete exposed by severe environmental condition showed broad ranges of damage with high chloride contents. Meanwhile, the water-binder(W/B) ratio and the less water content, and fly ash concrete than the specified existing mix proportion is significantly improved the durability. Also, the optimal mix proportion derived for test is satisfied the strength and air contents, water-binder ratio, and durability criteria of concrete specifications, as well as service life seems greatly improved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.77-85
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• 2020

Currently, life-cycle cost analysis methods are introduced to maintain large infrastructure facilities in Korea. However, there are not many cases in which maintenance models are applied that reflect conditions such as the location of a facility and its surroundings. In order to establish an appropriate maintenance strategy, a cost prediction, deterioration model, and a decision model reflecting uncertainty should be established. In this study, an economic analysis model was developed for long-term cost planning and management based on user decisions based on maintenance methods and judgment criteria for painting specifications applied to power generation structures. The performance of the paintwork was assessed through the paint deterioration test for the application of the economic analysis model, and the results of the economic analysis according to the applied paint specifications (Urethan, polysiloxane, fluorine) were verified by applying the proposed economic analysis model. In this study, it is believed that the selection of the repair cycle and evaluation methods applied with the development model rather than the performance of the painting can be expected to be used as basic data for the maintenance cycle, even if it is not limited to the painting.

• Journal of Korean Society of Steel Construction
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• v.15 no.4 s.65
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• pp.423-433
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• 2003

Many study have been performed to describe the elastic and inelastic behavior of H-shaped beams with web openings that generally concentrated on the monotonic loading condition and concentric web opening. The findings of the studies led Darwin to propose formulas for the design of beams with web openings considering local buckling. While the formulas are simple and useful in real situation, more studies arc needed on their cyclic loading condition. In this experimental study, 12 H-shaped beams with web openings under cyclic loading condition were investigated. The dimension criteria based on the formulas proposed by Darwin were examined. The suitability of existing design formulas and the effects of plastic hinges on beams with web openings and of local buckling around web openings on the beam strength under cyclic loading were also studied. This was done by observing their behavior with various dimensional openings, eccentric per cent, and stiffeners.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.55-61
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• 2023

In this study, a basic research was conducted to establish a maintenance plan considering the environmental factors and deterioration characteristics of port facilities. The precise safety diagnosis reports for Incheon and Busan port facilities were referenced to examine the extent of deterioration and damage. The relationship with the degradation environmental assessment presented in the current guidelines was also analyzed. The analysis of the damage level of Incheon and Busan port facilities revealed that Incheon Port exhibited approximately three times higher damage rate compared to Busan Port. In the case of Incheon Port, reinforcement corrosion and external damage showed similar proportions, while in Busan Port, reinforcement corrosion had a higher proportion compared to external damage. On the other hand, when comparing with the degradation environmental assessment presented in the guidelines, it was found that there were some limitations in performing quantitative evaluation based on the guidelines for assessing port facilities. Therefore, an analysis based on tidal range was conducted by referring to existing literature. The analysis of tidal range in Incheon and Busan regions showed that Incheon had approximately five times higher difference compared to Busan. It is considered that this can be utilized as a differentiated item from existing degradation environmental assessment criteria.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.4 s.107
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• pp.16-24
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• 2004

The reduction of paper machine water usage is precursor to the water system closure of any mills. This reduction in water consumption reduces the loss of solids; especially fine particulates and their surface adsorbed chemical additives, from mills, which causes an inevitable increase of fine materials in papermaking systems. Also the reduction of paper machine water usage causes substantial increase of organic and inorganic substances in process water. The deterioration of the papermaking process water quality accompanying the reduction of papermaking system closure can be a prime source of the aggravation of paper quality and process efficiency. It is of great importance for paper mills to investigate the influence of the level of papermaking system closure on the paper properties and process runnabililty before implementing process closure. To predict the changes in paper properties at different levels of system closure, highly cotaminated white water was prepared using reverse osmosis technology and used to prepare handsheets from fine paper and newsprint stocks. Results showed that the quality of process water affects the strength. Preparation of highly contaminated process water and handsheet forming with headbox stocks provided important criteria to determine the relationship between the qualities of process water and paper products.