• Journal of Ginseng Research
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• v.48 no.2
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• pp.229-235
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• 2024

Background: Plant health is directly related to the change in native microbial diversity and changes in soil health have been implicated as one of the main cause of root rot. However, scarce information is present regarding allelopathic relationship of Panax notoginseng root exudates and pathogenic fungi Fusarium oxysporum in a continuous cropping system. Methods: We analyzed P. notoginseng root exudate in the planting soil for three successive years to determine phenolic acid concentration using GC-MS and HPLC followed by effect on the microbial community assembly. Antioxidant enzymes were checked in the roots to confirm possible resistance in P. notoginseng. Results: Total 29 allelochemicals in the planting soil extract was found with highest concentration (10.54 %) of p-hydroxybenzoic acid. The HPLC showing a year-by-year decrease in p-hydroxybenzoic acid content in soil of different planting years, and an increase in population of F. oxysporum. Moreover, community analysis displayed negative correlation with 2.22 mmol. L^-1 of p-hydroxybenzoic acid correspond to an 18.1 % population of F. oxysporum. Furthermore, in vitro plate assay indicates that medium dose of p-hydroxybenzoic acid (2.5-5 mmol. L^-1) can stimulate the growth of F. oxysporum colonies and the production of macroconidia, as well as cell wall-degrading enzymes. We found that 2-3 mmol. L^-1 of p-hydroxybenzoic acid significantly increased the population of F. oxysporum. Conclusion: In conclusion, our study suggested that p-hydroxybenzoic acid have negative effect on the root system and modified the rhizosphere microbiome so that the host plant became more susceptible to root rot disease.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.637-642
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• 2007

The sum of each work duration are entire period in construction project. Each work occurs to be late, the total period of construction project will delays. Therefore, the total period of construction project will not be delayed if probability of working progress makes higher. Finding each work's constraints performs constraints analysis in process of construction for checking probability of working progress. Grasp work's constraints through the constraints analysis and removes. This research will show preventing delay of consruction project, through constraints analysis process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.777-778
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• 2012

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.416-417
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• 2005

• Journal of Digital Convergence
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• v.15 no.8
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• pp.69-83
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• 2017

This study aims to analyze the causes of a new product failure by using system safety methods, focusing on the case of Samsung Galaxy Note7. However, when analyzing the causes of a product failure, if only technical problems are too emphasized, it is likely to miss other more meaningful causes of a failure. Thus, we claim that the root causes of a product failure should be identified in a broad perspective of integrated systems that include non-technical as well as technical elements. With this viewpoint, we investigated the failure of Samsung Galaxy Note7, by using Root Cause Analysis(RCA) and Fault Tree Analysis (FTA). The results showed that it is necessary to address not only the technical issues but also other non-technical issues, such as a very impetuous launch of a new product due to a very tough competition in the market. Additionally, we also found that RCA and FTA could be a useful tool for analyzing the causes of a new product failure from the viewpoint of an integrated system comprising technical and management elements.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2017-2022
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• 2004

There are multistage preheaters in the power generation plan to improve the thermal efficiency of the plant and to prevent the components from the thermal shock. The energy source of these heaters comes from the extracted two phase fluid of working system. These two-phase fluid can cause the so-called Flow Accelerated Corrosion(FAC) in the extracting piping and the bubble plate of the heater for example, in case of point Beach Nuclear Power Plant and in the Wolsung Nuclear Power Plant. The FAC is due to the mass transport of the thin oxide layer by the convection. FAC is dependent on many parameters such as the operation temperature, void fraction, the fluid velocity and pH of fluid and so on. Therefore, in this paper velocity was calculated by FLUENT code in order to find out the root cause of the wall thinning of the feedwater heaters. It also includeed in the fluid mixing analysis model are around the number 5A feedwater heater shell including the extraction pipeline. To identify the relation between the local velocities and wall thinning, the local velocities according to the analysis results were compared with distribution of the shell wall thicknes by ultrasonic test.

• The korean journal of orthodontics
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• v.46 no.3
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• pp.155-162
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• 2016

Objective: The aim of this study was to investigate whether labial tooth inclination and alveolar bone loss affect the moment per unit of force ($M_t/F$) in controlled tipping and consequent stresses on the periodontal ligament (PDL). Methods: Three-dimensional models (n = 20) of maxillary central incisors were created with different labial inclinations ($5^{\circ}$, $10^{\circ}$, $15^{\circ}$, and $20^{\circ}$) and different amounts of alveolar bone loss (0, 2, 4, and 6 mm). The $M_t/F$ necessary for controlled tipping ($M_t/F_{cont}$) and the principal stresses on the PDL were calculated for each model separately in a finite element analysis. Results: As labial inclination increased, $M_t/F_{cont}$ and the length of the moment arm decreased. In contrast, increased alveolar bone loss caused increases in $M_t/F_{cont}$ and the length of the moment arm. When $M_t/F$ was near $M_t/F_{cont}$, increases in Mt/F caused compressive stresses to move from a predominantly labial apical region to a palatal apical position, and tensile stresses in the labial area moved from a cervical position to a mid-root position. Although controlled tipping was applied to the incisors, increases in alveolar bone loss and labial tooth inclination caused increases in maximum compressive and tensile stresses at the root apices. Conclusions: Increases in alveolar bone loss and labial tooth inclination caused increases in stresses that might cause root resorption at the root apex, despite the application of controlled tipping to the incisors.

• International Journal of Oral Biology
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• v.40 no.2
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• pp.93-101
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• 2015

The efficacy of air-polishing on subgingival debridement, as compared to scaling and root planning (SRP), was evaluated clinically and microbiologically. Fifteen patients diagnosed as chronic periodontitis, and having single-root tooth over 5 mm of pocket depth symmetrically in the left and right quadrant, were investigated. Subgingival debridement was performed by SRP and air-polishing. The results were evaluated and compared clinically and microbiologically. Probing pocket depth (PPD), bleeding on probing (BOP), relative attachment level (RAL) and change of gingival crevicular fluid (GCF) were assessed before treatment, and at 14 and 60 days after treatment. Microbial analysis was done pre-treatment, post-treatment, and at 14 and 60 days after treatment. Results of air polishing showed that post treatment, the PPD and BOP decreased, and attachment gain was observed. There was no clinical difference when compared to SRP. The volume of GCF decreased at 14 days, and increased again at 60 days. Compared to SRP, there was a statistical significance of the volume of GCF at 60 days in air-polishing. In the microbial analysis, high-risk bacteria that cause periodontal disease were remarkably reduced. They decreased immediately after treatment, but increased again with the passage of time. Thus, our results show that subgingival debridement by air-polishing was effective for decrease of pocket depth, attachment gain, decrease of GCF and inhibition of pathogens. Further studies are required to compare air-polishing and SRP, considering factors such as degree of pocket depth and calculus existence.

• Journal of the Korea Institute of Building Construction
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• v.23 no.4
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• pp.417-428
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• 2023

The demolition of domestic infrastructures mirrors other significant construction initiatives in presenting a markedly high accident rate. A comprehensive investigation into the origins of such accidents is crucial for the prevention of future incidents. Upon detailed inspection, the causes of demolition construction accidents are multifarious, encompassing unsafe worker behavior, hazardous conditions, psychological and physical states, and site management deficiencies. While statistics relating to demolition construction accidents are consistently collated and reported, there exists an exigent need for a more foundational cause categorization system based on accident type. Drawing from Heinrich's Domino Theory, this study classifies the origins of accidents(unsafe behavior, unsafe conditions) and human errors(human factors) as per the type of accidents experienced during demolition construction. In this study, a three-step model of QFD-FMEA(Quality Function Deployment - Failure Mode Effect Analysis) is employed to systematically categorize accident causes according to the types of accidents that occur during demolition construction. The QFD-FMEA method offers a technique for cause classification at each stage of the demolition process, including direct causes(unsafe behavior, unsafe environment), and human errors(human factors) through a tri-stage process. The results of this accident cause classification can serve as safety knowledge and reference checklists for accident prevention efforts.

• Journal of Auto-vehicle Safety Association
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• v.6 no.2
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• pp.67-71
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• 2014

Based on the analysis of the actual passenger vehicle fire cases for recent four years (2010~2013), the passenger vehicle fire is increasing annually. Main root cause was analyzed as an electric problem as a 39%. Vehicle fire case by electric problem was mainly caused by use of Non-genuine part. Vehicle fire case by mechanical problem was mainly caused by various oil system maintenance. Vehicle fire case by smoking material was mainly caused by cigarette and disposal lighter. And external fire transition issue and towing mistake fire cases was also confirmed.