• Journal of Environmental Impact Assessment
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• v.18 no.6
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• pp.367-376
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• 2009

This paper proposes an application methodology of AHP(Analytic Hierarchy Process) based decision making theory for improvement priority by assessment of various risk factors affecting on deterioration of water supply systems, as major social infrastructure. AHP method is organized with three level of hierarchy which is introduced for multi-criteria decision making in this study. In the first level, assessment outputs are calculated by AHP for each affecting factor. In the second level, criteria are estimated by using assessment results with respect to structural and environmental factors. Consequently, ranking decision is performed in the third level. In order to present the effectiveness, a proposed method is compared with FCP(Fuzzy Composite Programming) for decision making. Since the results of the proposed method show better performance with consistent results, it can be applied as an efficient information for the determination for improvement priority of the study infrastructure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.82-92
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• 2012

This study proposed a new non-destructive evaluation method for concrete bridge deck deterioration using ground penetrating radar (GPR). To calculate dielectric constant of the concrete bridge deck, an extended common mid-point (XCMP) method was developed for a two-layered structure using an air-coupled GPR antenna setup. The deterioration conditions of the concrete bridge deck such as deterioration depth was evaluated based on the dielectric constant and surface-to-average dielectric constant ratio of the concrete bridge deck. A GPR field test was conducted on an old concrete bridge with asphalt concrete surfacing to validate the new evaluation method. The test results showed that the newly proposed method estimated pavement thickness and deterioration depth of the concrete deck in a reasonable level.

• Korean Journal of Agricultural Science
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• v.49 no.2
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• pp.367-377
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• 2022

The purpose of this study was to analyze the deterioration of trail conditions and to obtain information for desirable maintenance and restoration of a trail in Deogyusan National Park. The physical characteristics of a trail were surveyed at a total of 412 sites over 79.8 km length. The average trail degree and width were found to be 14.31° and 1.60 m, respectively, while the average bare trail width was 1.40 m and the average maxim trail depth was 5.66 cm. Major deterioration types of trail were trail deepening (36.6%), rock exposure (33.9%), and root exposure (12.5%) in order of frequency. Deterioration classes of the trail were 0.626 km (0.8%), 3.110 km (3.9%) and 8.935 km (11.2%) for heavily, moderately, and lightly deteriorated, respectively, with a deterioration rate of 12.671 km (15.9%). Compared to other national parks, the ratio damaged trail to the total trail was 15.9%, which is slightly higher than other, including Jirisan National Park 9.6% (2019), Bukhansan National Park 13.6% (2019), Sokrisan National Park 11.7% (2019), Chiaksan National Park 12.3% (2015), and Woraksan National Park 10.5% (2015). The section of trail in Deokyusan National Park where the damage grade is analyzed as "Heavy" should therefore be restored in consideration of the field conditions. In particular, the damage status of the trail is expected to be greatly improved when the trail surface maintenance level is restored.

• Journal of the Korean housing association
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• v.13 no.6
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• pp.121-131
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• 2002

The rebuilding method for old apartment housing blocks has merits of providing new buildings and larger private living spaces. However, it causes many serious urban problems, such as shortage of infrastructure capacity, traffic congestion, reduction of building life, and deterioration of open space quality. Nowadays, remodeling is accepted as a way of overcoming such negative effects of the rebuilding method. This study focuses on the various techniques of remodeling. The results of this research are as follows; First, old apartment blocks provide poor level of service in general, so they have problems of bad accessibility, deterioration of facilities, and degraded landscape. In many cases, there is a hindrance from walking freely and security problem due to illegal privatization of public spaces. Second, various remodeling techniques are required to meet residents' different needs. The residents of apartment housing value private space above public space, and show low level of willingness to pay cost for remodeling. Third, based on these findings, some remodeling techniques are suggested - integration of a space to another, expansion of spaces, connection of spaces, reuses of roofs and walls, relocation and renovation of paths between buildings, and so on.

• Journal of Korean Society for Quality Management
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• v.26 no.4
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• pp.51-64
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• 1998

Mean shifts may be found in tool wear in machining, drawing, stamping and moulding operations, which make the process quality level deteriorate over time. In such situations, it is necessary to reset or readjust the manufacturing process at regular time basis or by inspection to prevent defective items produced. Although the deterioration rate may be assumed to be linear in a production cycle, there are many cases where the rate varies after resetting due to the variation of tool characteristics or by using the resharpened tools. In such cases, the deterioration rate should not be assumed to be a deterministic constant but a random variable. This paper is to find an optimal resetting period and quality level for such production processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3482-3486
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• 2013

In the case of the Pilot Symbol Assisted Modulation (PSAM) method predicting and compensating amplitude and phases caused on fading channels, there can be severe performance deterioration by Doppler spread on fast fading channels. In this paper, the fading compensation method suggested so as to improve occurring problems as well as analyze them. Doppler spread is the major cause of the bit error rate(BER) performance deterioration. Compared to the existing PSAM method, the more performance deterioration occurs, the larger Doppler spread appears but performance shows well its less $10^{-2}BER$ performance than the existing PSAM method in the suggested method whereas the existing PSAM method has about $10^{-1}BER$ its considerable performance deterioration that caused by Doppler spread within a symbol cycle with the level of delay wave interference.

• International Journal of Advanced Culture Technology
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• v.8 no.3
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• pp.300-306
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• 2020

This study analyzes the distributor's inventory model in a two-stage supply chain consisting of the supplier, the distributor and the end customer. The supplier will allow a credit period before the distributor settles the account with him in order to stimulate the demand for the product he produces. It is also assumed that the distributor pays the shipping cost for the order and hence, the distributor's ordering cost consists of a fixed ordering cost and the shipping cost that depend on the order quantity. The availability of the delay in payments from the supplier enables discount of the distributor's selling price from a wider range of the price option in anticipation of increased customer's demand. As a result, the availability of a credit transaction leads to an increase in inventory levels. On the other hand, in the case of deteriorating products in which the utility of the product perish over time, the deterioration rate with time plays a role in reducing inventory levels. In this regard, we analyze the effect of the length of the credit period and the degree of product deterioration on the distributor's inventory level. For the analysis, we formulate the distributor's annual net profit and analyze the effect of the length of credit period and deterioration rate of the product on inventory policy numerically.

• Geomechanics and Engineering
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• v.32 no.2
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• pp.233-244
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• 2023

With the increasing amount of resources required by the society development, mining operations go deeper, which raises the requirements of studying the effects of temperature on the physical and mechanical properties of coal and adjacent rock. For now, these effects are yet to be fully revealed. In this paper, a mechanical-electromagnetic radiation (EMR) test system was established to understand the mechanical deterioration characteristics of coal by the effect of thermal treatment and its deformation and fracture characteristics under thermo-mechanical coupling conditions. The mechanical properties of high-temperature-treated coal were analyzed and recorded, based on which, reasons of coal mechanical deterioration as well as the damage parameters were obtained. Changes of the EMR time series under unconstrained conditions were further analyzed before characteristics of EMR signals under different damage conditions were obtained. The evolution process of thermal damage and deformation of coal was then analyzed through the frequency spectrum of EMR. In the end, based on the time-frequency variation characteristics of EMR, a method of determining combustion zones within the underground gasification area and combustion zones' stability level was proposed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.229-239
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• 2015

In light of the significant increase in the quantities of goods transported and the development of the shipping industry, the frequency of usage of port structures has increased; yet, the government's budget for the shipping & port of SOC has been reduced. Port structures require systematically effective maintenance and management trends that address their growing frequency of usage. In order to construct a productive maintenance system, it is essential to develop deterioration models of port structures that consider various characteristics, such as location, type, use, constructed level, and state of maintenance. Processes for developing such deterioration models include examining factors that cause the structures to deteriorate, collecting data on deteriorating structures, and deciding methods of estimation. The techniques used for developing the deterioration models are multiple regression analysis and Markov chain theory. Multiple regression analysis can reflect changes over time and Markov chain theory can apply status changes based on a probabilistic method. Along with these processes, the deterioration models of open-type and gravity-type wharfs were suggested.

• Journal of Conservation Science
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• v.28 no.4
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• pp.321-328
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• 2012

A $SO_2$ gas acceleration test was carried out on four textile groups (silk, cotton, ramie cloth, hemp cloth) which were categoried in five categories by the dyeing materials (undyed, red, yellow, blue, black) and the relation between the concentration of $SO_2$ and deterioration rate was evaluated. The textiles were exposed to 0.01, 0.12, 1, 10, 100, 1000, and 5000 ppm of $SO_2$ for 24 hours and the optical, physical, and chemical deterioration rates were studied. An optical change was identified as the color difference and grey scale rating (colorfastness) enhanced with the increase of gas concentration while there was little physical change. Chemical damage was caused by the acidification of the textile material due to the trapped sulfate ion concentration. The result of optical, physical, and chemical deterioration rates shows that 1 ppm/day $SO_2$ is a critical level of deterioration of traditional textiles.