• Journal of Navigation and Port Research
• /
• v.43 no.2
• /
• pp.93-100
• /
• 2019

In 2001, about 20 years after the introduction of the standard buoys, the natural environment and maritime traffic flow changes in the waters near Korea and the necessity of improvement of the AtoN (Aids to Navigation) maintenance was suggested. The IALA provides guidelines for maintenance and management of AtoN, and Korea provides guidelines for the management and operation of standard buoys by means of the Enforcement on the AtoN laws. The objective of this study was to investigate the installation status and the repair status of the standard type buoys by sea area in order to improve the management and operation of the steel standard buoys. In addition, a survey was conducted on the improvement of the steel buoy fouling and the improvement of the lifting inspection cycle towards on the AtoN managers and producers of the representative authority by sea area. In the case of LL-26 (M) buoy type, the standard type buoy installation status of Korea in 2017 was 57.1%, and the LL-26 (M) type was 58.9% showing the highest repair rate. According to the results of the survey on buoys fouling, 51.2% were caused by the attachment of shellfish, and 43.2% were caused by bird feces. The results of the survey on the improvement of the regular buoy inspection cycle showed that the measures are to maintain the current inspection period of 2 years regardless of the characteristics of the sea area (water depth, inside and outside port, buoy size, etc.).

• Journal of Periodontal and Implant Science
• /
• v.51 no.2
• /
• pp.114-123
• /
• 2021

Purpose: This retrospective cohort study aimed to assess the effect of nonsurgical periodontal therapy on glycated hemoglobin (HbA1c) levels in patients with both type 2 diabetes and chronic periodontitis. Methods: The intervention cohort (IC) comprised 133 patients with type 2 diabetes who received nonsurgical periodontal treatment, while the matching cohort (MC) included 4787 patients with type 2 diabetes who visited the Department of Endocrinology and Metabolism of Asan Medical Center. The patients in each cohort were divided into 3 groups according to their baseline HbA1c level: subgroup 1, HbA1c <7%; subgroup 2, 7%≤ HbA1c <9%; and subgroup 3, HbA1c ≥9%. Changes in HbA1c levels from baseline to 6 and 12 months were analyzed. In addition, the association between changes in HbA1c levels and the number of periodontal maintenance visits was investigated. Results: There were no statistically significant changes in HbA1c levels in the IC and MC or their subgroups when evaluated with repeated-measures analysis of variance. However, the IC showed maintenance of baseline HbA1c levels, while the MC had a trend for HbA1c levels to steadily increase as shown by pairwise comparisons (baseline to 6 months and baseline to 12 months). IC subgroup 1 also maintained steady HbA1c levels from 6 months to 12 months, whereas MC subgroup 1 presented a steady increase during the same period. The number of periodontal maintenance visits had no association with changes in HbA1c levels during the 1-year study duration. Conclusions: For patients with both type 2 diabetes and periodontitis, nonsurgical periodontal treatment and periodontal maintenance may help to control HbA1c levels.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1650-1655
• /
• 2007

A lights-out detector, which helps the person in charge of maintenance make a quick judgment in the event of a failure of LED-type traffic lights, was explored/developed and installed/ tested, at Seoul Metro, after they developed a patented pilot product in 2005; and, a product improvement test was conducted to ensure reasonable maintenance of signaling facilities. Having better compatibility with existing circuit in use and displaying stable load current, the device makes the maintenance of lights-out detection and alert easier.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.2036-2037
• /
• 2008

An Emergency Diesel Generator (EDG) manufactured by a French company Wartsila SACM, is a tandem type engine, consisted of two 10 cylindered diesel engines on each side. Manual provided by the manufacturer states that engine bearing requires inspection every 15 years. However, it is difficult for an inspector to access through a manhole located in the lower compartment of engine. Furthermore, during a routine or scheduled maintenance, it is not possible to disassemble main engine bearing and crank shaft, and perform inspection. Two methodologies are suggested here to resolve the problem. One method is to lift the engine and partially perform the maintenance service, and the other method is to disassemble the engine completely and to perform maintenance service by the manufacturer. Pros and cons of two methodologies were thoroughly compared.

• Journal of the Korea Safety Management & Science
• /
• v.13 no.4
• /
• pp.53-60
• /
• 2011

Job stress weakens physical ability causing the diseases related to working condition, decreases a production level, and increases mistakes and accidents. This study examined the relationship between job stress and human error, and focused on the moderating effect of age and maintenance type on the relationship between job stress and human error. The study used a quantitative design based on the 450 questionnaires of maintenance personnel in the Air force. The results of multiple regression analysis showed that physiological and psychological stress responses have positively related with human error. In moderating effect test, age appeared to impact on the relationship between physiological/behavioral stress and human error.

• Proceedings of the KIEE Conference
• /
• 1998.11a
• /
• pp.332-334
• /
• 1998

Maintenance scheduling is one of mid-term scheduling problems of power systems. There have been many methods for this problem, but there is no effective way to treat all the generators simultaneously except evolutionary algorithms. In this paper, we apply GA to the maintenance scheduling problem. And we proposed new crossover operator(BOX type crossover) to improve searching ability of GA. Satisfactory results are obtained by GA with proposed crossover operator.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.7 no.1
• /
• pp.251-258
• /
• 2003

This study is to understand the characteristics of axial force behavior that operates to the part of continuous welded rail and to investigate the basic data for secure the structure's stability and retrofit of the track. To develop the FEM model that type of plate girder which is used in the domestic national railway among servicing railway type. It is to analyze the characteristics of axial force behavior according to equip of the expansion joint and support placing by using the axial force simulation in making the continuous welded rail. As the result of research on the parametric valuables through the analysis, it is investigated that 'FMFM type' is more efficient than the other support type. Also, it conclude that structures are having the expansion joint is the most safe condition.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.429-430
• /
• 2013

• Magazine of the Korea Institute for Structural Maintenance and Inspection
• /
• v.21 no.1
• /
• pp.31-37
• /
• 2017

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2009.11a
• /
• pp.284-287
• /
• 2009

This study is aim to analyze out Living Guide Book for residents in Housing and to have application to Long Life Housing as a precedent study based on Maintenance Guideline to make residents inhabitate, in case of suppling Wet type Short Life Housing with S(Support) and I(Infill), and Long Life Housing with devised SI, durability, alterability, available Remodeling and maintenance effect. Housing with large scale complex and brand-name offers Living Guide Book for residents that contains maintenance contents. Maintenance contents for residents in Housing are complex guide, use method of the each part, guide for repair of defect, repair and change of built -in items ended up life or damaged items. Maintenance contents for residents in Long Life Housing are important because the Manager takes charge of public area and public equipment in S, but the user takes charge of private area and private equipment. Therefore this study analyzes out Living Guide Book for residents in Housing as a precedent study based on Maintenance Guideline of Long Life Housing users.