• Journal of Aerospace System Engineering
• /
• v.16 no.6
• /
• pp.106-113
• /
• 2022

The structural safety of the basic design model of the linear actuator for the individual blade pitch control of eVTOL personal aircraft was investigated. Stress analysis based on the finite element method was conducted, and the margin of safety was calculated to examine the structural safety under stall load conditions. Additionally, fatigue analysis was conducted to evaluate the fatigue life of the linear actuators under operating conditions. The load history with the blade pitch angle was calculated using multi-body dynamics analysis, and the static load analysis was used to obtain the stress distribution for the rated load. As a result, it was confirmed that the safety margins exceeded zero, and the fatigue lives of all linear actuator components exceeded 107 cycles, indicating a safe structural range.

• Management & Information Systems Review
• /
• v.38 no.1
• /
• pp.63-81
• /
• 2019

In order to overcome the disadvantages of banner ad, pop-up ad, interstitial ad, which are existing web advertisement forms, native ad is actively utilized. Native advertising is considered to be a useful advertising technique in that it can reduce users' rejection and attract attention. However, in recent years, there have been a lot of fake news and fake contents that have turned articles or video contents into advertisements. The purpose of this study is to understand how firms can coordinate and control native advertisements in a rational way. For this analysis, we conducted a survey of 308 social media users using quota sampling method. As a result of the verification, it was found that the more negative the perception of the evaluation of the advertisement, the less the level of persuasion about the advertisement and the negative impact on the website where the advertisement is exposed. In addition, this study examined the influence of the negative stimulus factors on the qualitative performance of the firm. As a result, it was found that source non-expert had the highest effect on skepticism on ad. Also, platform overflow has a direct effect on the evaluation of the website as well as the negative evaluation of the advertisement. Moreover, this study provides concrete implications for the subdivision market by verifying the differences between the paths according to the level of website involvement.

• Corrosion Science and Technology
• /
• v.8 no.2
• /
• pp.53-61
• /
• 2009

In this study, both evaluations by visual imaging for exterior view of coating and by EIS were executed for epoxy primer coated specimens deteriorated by accelerated test, and comparison and analysis were carried out for 2 evaluation methods. In the comparison between total damaged area ratio acquired by image processing method and deterioration point, higher deterioration points were appeared for rusted specimens than for non-rusted specimens. It is attributed that deterioration point per unit area ratio given for rust is higher than for peeling. In the comparison between total damaged area ratio and EIS result, impedance of coating was largely decreased as about TEX>$10^4{\Omega}{\cdot}cm^2$ or less when rust area ratio is more than about 0.1%, and blistering area ratio is more than about 3%. Charge transfer resistance ($R_{ct}$) and double layer capacitance ($C_{dl}$) values were appeared for all specimens except 2 ones, which shows that water is accumulated and steel substrate is corroded at coated film-steel interface. In the comparison between deterioration point and EIS result, more than 10 points as deterioration point were given for specimens of below $10^6{\Omega}{\cdot}cm^2$ of impedance at low frequency. For specimens deteriorated by NORSOK cyclic test, impedance was lowest of all, though deterioration point was not high. It is thought to be attributed that coating system and accelerated deterioration condition of cyclic tested specimens were different from those of main specimens. From the result, it is thought that coating resistance can be relatively more decreased than deterioration degree estimated from exterior view under more severe corrosion environment or in the present of more complex deterioration factors.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.6
• /
• pp.132-140
• /
• 2019

In this study, a specimen composed of columns, walls, beams, and slabs was fabricated to investigate the estimated reliability using nondestructive test method for the location of structural members of reinforced concrete single layer structures. And for accurate analysis in the comparison process with the existing estimation formula, we try to analyze the reliability through statistical approach by using error rate comparison and Confidence interval estimation. As a result, The average error rate of the core test was 18.8% compared with the result of estimating the compressive strength using the ultrasonic pulse velocity method. The average error rate of the core test results compared with the result of estimating the compressive strength using the rebound hardness method was 20.1%, confirming the field applicability. it is judged that the reliability of the compressive strength estimation can be derived from the wall member to make a quick and efficient structure safety diagnosis using the ultrasonic pulse velocity method. In addition, it is judged that the reliability of the compressive strength estimation can be derived from the beam member to make a quick and efficient structure safety diagnosis using the rebound hardness method.

• The Journal of the Korea Contents Association
• /
• v.8 no.1
• /
• pp.48-58
• /
• 2008

This study intends to figure out the image evaluation properties of internet shopping malls and suggest a strategic direction for positioning through establishing a perceptual map on how the actual customers remember them and which image expression would make the most effective marketing. According to the result of analysis, the images of internet shopping malls were drawn as elements such as product information service, customer service after purchase, atmosphere, convenience, safety, and fame. And according to the result of making a perceptual map, it showed that there was a meaningful difference in the customers' perception on competitive shopping malls. The most discriminative property among the images of shopping malls was product information service, and the least discriminative property was convenience. In addition, there showed a meaningful difference in the customers' preference and ideal point on internet shopping malls between the subdivided groups of customers. It was verified that in this internet shopping mall market where competition is getting severe, the result of this study can be a useful foundational data in establishing a marketing strategy of market segmentation.

• Journal of Korean Society on Water Environment
• /
• v.26 no.6
• /
• pp.895-902
• /
• 2010

The effect of seasonality on water quality variation is very significant. Generally, it reduce the power of the trend extraction. A parametric time-series model was used for detecting trends in historic constituent concentration data. The effect of seasonality is able to remove from time series decomposition technique. According to such statistic methode, long-term water quality trend analysis system (NTrend 1.0) was developed by Nakdong River Water Environmental Research Center. The trend analysis of BOD variation was conducted with NTrend 1.0 at Goreong and Moolkum site in Nakdong river to show the effect of water quality management action plan. Power test of trend extraction was tried each case of 'deseasonalized and deannulized' data and 'deseasonalized' data. Analysis period was from 1989 to 2006, and it's period was divided again three times, 1989~1993, 1994~1999 and 2000~2006 according to action plan period. The BOD trend was downward in Goreong site during three times and it's trend slope was very steep, and upward in Moolkum during 1989~1993, but it was turned downward during 1994~1999 and 2000~2006. It was revealed that it's very effective to reduce the concentration of BOD by water quality management action plan in that watershed. The result of power test was shown that it is high for trend extraction power in case of 'deseasonalized' data.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.833-841
• /
• 2008

Recently, the upheaval generation in the road which is under service had been reported. Due to the upheaval generation, total 4 lanes were forced to curtail to 3 lanes, and traffic was delayed. In normal situation of cut-slopes in korea, that condition is hard to detect since most cut-slopes contain discontinuous material, that is rock. Common collapses in rock-slopes is wedge failure, plane failure and toppling failure which is all individual mechanism of discontinuous rock mass. In contrast, such upheaval in the road in front of cut-slope can be generated only when circular movement is triggered within the cut-slope. In this sense, rock-slopes barely show any kind of movement in the road locates at the front of them. Numerical analysis is general method in simulation of slope displacement and evaluation of safety. However, numerical analysis programs which are related with rock-slopes are not able to simulate such upheaval movement because that programs are based on discontinuous modeling mechanism. In addition, although numerical analysis programs which are based on FEM/FDM and thus utilize continuous modeling mechanism are able to simulate circular movement and upheaval situation, they have weakness in reflecting discontinuities of rock-slope itself. In this study, detailed in-site investigation and numerical analysis based on in-site condition were performed in order to expect upheaval movement in the road. In this procedure, the FLAC program which uses continuous modeling method was utilized, and new approach reflecting discontinuity developed toward the road with a ubiquitous joint model was tried to derive reliable analysis result.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.1316-1323
• /
• 2005

Most tunnel lining material which has been used in the domestic is a concrete. But many problems as the construction period, the cost, and the crack occurrence for the design, construction, and management were happened in the concrete lining. For this reason, many research institutes like the Korea Highway Corporation recognize the necessity of an alternate material development and grow on the interest for that. So in this study, the behaviour characteristics for the application of the Corrugated Steel Plate Lining in cut-and-cover tunnel are evaluated as several conditions for the backfill height, the cutting slope, and the relative density of backfill soil are changed. In addition, through using that conditions, CHBDC(2000, Canadian Highway Bridge Design Code) is evaluated if it could be applied to the design by comparing with the numerical analysis results. As the behaviour characteristics of the Corrugated Steel Plate Lining by CHBDC and the static numerical analysis are analyzed, both the methods show the same linear increases of the compressive stress according to the increase of the backfill height. The CHBDC of the dead load condition has very similar tendency by comparing with the result of the static numerical analysis.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.34 no.6
• /
• pp.299-308
• /
• 2020

This study aimed to evaluate the effects of Chuna therapy for Sciatica. We searched the following 16 online databases without a language restriction (Pubmed, Cochrane, Embase, CINAHL, Ovid, Kmbase, RISS, NDSL, OASIS, KISS, KNAL, KTKP, DBpia, CNKI, Wangfang, J-stage) to find randomized controlled clinical trials that used Chuna therapy for Sciatica. The methodological quality of randomized controlled clinical trials (RCTs) were assessed using the Cochrane risk of bias tool and meta-analysis were performed. Among 496 articles that were searched, 15 RCTs were finally selected for systematic review. 14 studies showed that Chuna therapy has positive effect on sciatica. Two studies noted that there were side effects, and the difference between the intervention group and the control group was statistically insignificant. One study noted no side effects and the rest of the study, there was no mention of side effects. Meta-analysis showed positive results for Chuna single therapy in terms of efficiency rate compared to painkiller, herb medicine excepting acupuncture. When comparing Chuna therapy plus acupuncture and acupuncture, Chuna therapy plus acupuncture had a more positive result than acupuncture in terms of efficiency rate. Cochrane Risk of Bias (RoB)evaluation method, most of the studies's selection, performance, detection and reporting bias were unclear. The studies showed that Chuna therapy can significantly effective on sciatica. However, most of the studies's Risk of Bias included in the analysis were not low enough. In the future, to prove the level of evidence of Chuna therapy, more high-quality studies will be needed.

• Journal of Convergence for Information Technology
• /
• v.12 no.4
• /
• pp.231-238
• /
• 2022

This study aims to investigate the effect of college students' major satisfaction on career decision-making self-efficacy and job confidence. The research method was used for analysis by surveying 335 two-year college students majoring in beauty in Seoul and Gyeonggi-do. The collected data were analyzed for frequency analysis, factor analysis, reliability analysis, and correlation between career decision-making self-efficacy and job confidence using SPSS 26.0, and multiple regression analysis was conducted to confirm the effect between each variable. As a result of the study, first, a statistically significant positive (+) correlation between college students' major satisfaction was confirmed between career decision-making self-efficacy and job confidence. Second, as the effect of major satisfaction on self-efficacy, statistically significant effects were confirmed in self-evaluation, problem-solving, and goal selection. Fifth, it was confirmed that major satisfaction had a statistically significant effect on job confidence. Fourth, it was confirmed that career decision-making self-efficacy had a statistically significant effect on job confidence.