• Structural Monitoring and Maintenance
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• v.4 no.1
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• pp.85-105
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• 2017

Monitoring is the most important part of the construction and operation of the embankment dams. Applied instruments in these dams should be determined based on dam requirements and specifications. Instruments selection considered as one of the most important steps of monitoring plan. Competent instruments selection for dams is very important, as inappropriate selection causes irreparable loss in critical condition. Lack of a systematic method for determining instruments has been considered as a problem for creating an efficient selection. Nowadays, decision making methods have been used widely in different sciences for optimal determination and selection. In this study, the Multi-Attribute Decision Making is applied by considering 9 criteria and categorisation of 8 groups of geotechnical instruments. Therefore, the Analytic Hierarchy Process and Multi-Criteria Optimisation and Compromise Solution methods are employed in order to determine the attributes' importance weights and to prioritise of instruments for embankment dams, respectively. This framework was applied for a rock fill with clay core dam. The results indicated that group decision making optimizes the selection and prioritisation of monitoring instruments for embankment dams, and selected instruments are reliable based on the dam specifications.

• Journal of Welding and Joining
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• v.19 no.1
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• pp.40-48
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• 2001

An ultrasonic test method, as a nondestructive test is applied to ensure the clad interface quality assessment. According to the reference codes and standards, not only korea Industrial Standard(KS) but also American Society for Testing and Materials (ASTM) Standard, ultrasonic examination procedures use the pulse-echo, A-scan, back reflection signal drop method and/or side drilled reference hole used to establish the acceptance criteria of clad material test. But the variety of bonding materials and sizes makes it difficult to produce the reference blocks, or thus the criteria. In order to overcome these practical difficulties, new ultrasonic testing criterion is suggested. In this new method, the theoretical interface reflection signal amplitude level is calculated and suggested as an acceptance criteria with the back reflection signal set to 100% FSH(Full Screen Height) which is based on acoustic impedance mismatch at the clad interface for the explosive clad ultrasonic inspection. Applicability of suggested criterion, for the explosive clad Fe-Naval Brass with different bonding quality is confirmed to the pre-existed KS and ASTM specifications and verified by using SEM (Seanning Electron Microscope) micrograph. The results obtained by the suggested method is more conservative than the results according to the KS B 0234 and ASTM A 578 specifications The suggested method could be applicable to any other combination of explosive clad ultrasonic inspection.

• Journal of the Korean Society for Railway
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• v.11 no.5
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• pp.489-498
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• 2008

In general, deflection limit criteria of bridge design specifications have been considered based on static serviceability and structural stability. Dynamic serviceability induced from bridge vibration actually has not been included in the criteria. Thus, it is necessary for deflection limit to be considered in order to check dynamic service- ability on bridge vibration. In this study, The allowable displacement of Korea Railway Bridge Design Specifications is compared to the frequency domain comfort limit and analyzed france code and japanese code. Korea Railway Bridge Design Specifications is regulated based on the train speed. Such is because the vibration time duration is partly considered. but this criteria is not satisfied with comfort limit. and, it is estimated to be capable to provide deflection limit considering dynamic serviceability. In order to evaluate the dynamic serviceability of various types of railway bridges in current public were selected and their dynamic signals were measured. and the result of the bridge-train interaction analysis according to the changes in bridge stiffness was compared to the comfort limit to suggest the stiff-ness limit to the dynamic serviceability, which should conveniently be applied at the field.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.26-35
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• 2004

The ASTP is the standard of the assessment ASRP that is monitoring the performance, reliability and safety characteristics of the ammunition items. The ASTP used in domestic now has applied to US Army's grade system and grading criteria so that it cause some problems. To resolve these problems of ASTP, we surveyed both the quality level of production and the field management of ammunition, which compared with grade system and classification criteria. As a result of study, we changed grade system from four steps to three steps and applied the Korean Military Specifications and the Malfunction Criteria to the classification criteria of grades. We are looking forward to improving the reliability and effectiveness of ASRP assessment by simplifying grade system and generalizing grading criteria of ASTP.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.223-242
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• 2024

Single-shell tunnels, introduced to South Korea in the early 2000s, have not been adopted for the main tunnels of roads or railways over the past two decades despite several attempts starting with the Gwangju City Bypass. This reluctance likely arises from concerns about the long-term performance of supporting materials and the absence of relevant criteria and specifications. However, recent progress, including the incorporation of high-strength shotcrete standards and corrosion-resistant rock bolt specifications, alongside equipment and technique enhancements, necessitates a reassessment of single-shell tunnels. While the single-shell tunnel method offers advantages in environmental impact, construction cost and period compared to the conventional NATM, it is crucial to address the challenges, such as limited design and construction experience, incomplete detailed standards, and insufficient construction specifications, through further research and pilot projects. This paper reviewed the basic principles of single-shell tunnel, current application and research status, technical development trends, criteria and specifications, and remaining challenges. It aims to reignite discussions on the feasibility of applying single-shell tunnels in South Korea.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.226-239
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• 2007

The purpose of this study was to identify the problems related to the purchasing processes of school foodservices that should be corrected for the food service safety, by examining the purchasing processes and the status of supplier selection. A questionnaire was given to 300 dietitians working at self-operated food services. Ninety-eight responses, excluding incomplete answers, were used for the statistical analysis. The survey consisted of three parts: the general characteristics of the school foodservice and dietitian, purchasing processes and supplier selection, and the purchase specifications. We found that 84% of the contract was made by informal purchasing, and the contract period was 6 months or one year. For supplier selection, problems related to the document screening systems were the superficiality of the content(45.7%) and the absence or lack of clarity of the appraisal criteria(34.8%). The important factors for the facility and equipment standards of suppliers were included unclear evaluation methods for content(41.1%) and inappropriate appraisal lists(21.1%), while unclear evaluation methods for content(41.9%) and absence or lack of clarity of the appraisal criteria(20.4%) were the problems pertaining to the supplier evaluation checklist. When using the Food Labeling Standards to select suppliers, confirmation of the sell-by date and the storage method had the highest score at 3.85 out of 5. For supplier selection, only 25% of the contract was made by using the purchase specifications. The levels of satisfaction of with Kimchi and rice cakes suppliers were significantly different according to employment type and educational background, respectively. Depending on working experiences, satisfaction was significantly different for the use of document screening, as a standard for the selection and management of suppliers, and for the facility and equipment standards of suppliers, The use of purchase specifications was different by employment type, while the use of purchase specifications for contracts was different by working experience. These results imply that the specialization of suppliers is necessary to unsure food safety. Therefore, the objective methods to evaluate the suppliers should be developed by the government, and appropriate education programs for dietitians should be prepared to enhance the utilization of purchase specifications.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.177-179
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• 2011

The difference the guide specifications of between housing and land development has been caused many problems, since Korea Land Corporation and Korea Housing Corporation were merged into LH (Land and Housing Corporation) in 2009. Those are that specification criteria to establishing lower level specifications are disordered; duplicated investment on sites; management systems are conflicted site to site, which are based on different operation system from old land and housing corporations, etc. Thus, this paper aims to suggest a direction of integrated guide specification system of LH including improved and advanced classification hierarchy and specification.

• Steel and Composite Structures
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• v.19 no.4
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• pp.811-827
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• 2015

This paper presents a probabilistic investigation of American and European specifications (i.e., AISC and Eurocode 4) for square concrete-filled steel tubular (CFT) stub columns. The study is based on experimental results of 100 axially loaded square CFT stub columns from the literature. By comparing experimental results for ultimate loads with code-predicted column resistances, the uncertainty of resistance models is analyzed and it is found that the modeling uncertainty parameter can be described using random variables of lognormal distribution. Reliability analyses were then performed with/without considering the modeling uncertainty parameter and the safety level of the specifications is evaluated in terms of sufficient and uniform reliability criteria. Results show that: (1) The AISC design code provided slightly conservative results of square CFT stub columns with reliability indices larger than 3.25 and the uniformness of reliability indices is no better because of the quality of the resistance model; (2) The uniformness of reliability indices for the Eurocode 4 was better than that of AISC, but the reliability indices of columns designed following the Eurocode 4 were found to be quite below the target reliability level of Eurocode 4.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.67-74
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• 2008

The important dynamic specifications in the aluminum automobile body design are the vibrations and crashworthiness in the views of ride comforts and safety. Thus, considerable effort has been invested into improving the performance of mechanical structures comprised of the interactive multiple sub-structures. Most mechanical structures are complex and are essentially multi-criteria optimization problems with objective functions retained as constraints. Each weight factor can be defined according to the effects and priorities among objective functions, and a feasible Pareto-optimal solution exists for the criteria-defined constraints. In this paper, a multi-criteria design based on the Pareto-optimal sensitivity is applied to the vibration qualities and crushing characteristics of front structure in the automobile body design. The vibration qualities include the idle, wheel unbalance and road shake. The crushing characteristic of front structure is the axial maximum peak load.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.225-226
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• 2010

ISO 22266-1 issued in May 2009 provides guidelines for applying shaft torsional vibration criteria, under normal operating conditions, for the coupled shaft system and long blades of a turbine generator set. In case that a turbine generator vendor do not meet the separation margin of torsional natural frequencies in the technical specifications of the purchaser, this standard can present the reasonable and objective criteria about torsional vibration which both purchaser and supplier can agree on, while ensuring the integrity of turbine generator. This paper describes the application case of ISO 22266-1 for the establishment of torsinal vibration criteria under retrofitting the turbine generator of 'U' nuclear power plant.