• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.9
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• pp.1131-1138
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• 2019

The importance of coatings has been increasing for different purposes such as prevention of static electricity of auto parts or products, improvement of abrasion and corrosion resistance, and enhancement of esthetics. As a method for measuring the thickness of a coating film, a contact method with probe is commonly used. However, it is problematic that accuracy of the sensor is degraded due to sensor output distortion or load phenomenon, which is caused by a change in magnetic permeability of the core. In this study, we propose a method to reduce the measurement error of the coating film by applying the optimized circuit design and the thickness measurement algorithm to the problems caused by the nonlinear characteristics. The tests result which have been taken with different thickness coating samples show that the measurement accuracy is within ${\pm}2%$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1375-1380
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• 2021

Korea's security response to application service app is still insufficient due to the initial opening of the public safety network. Therefore, preemptive security measures are essential. In this study, we proposed to establish a 'public safety network app security system' to prevent potential vulnerabilities to the app store that distributes app in public safety network and android operating system that operate app on dedicated terminal devices. In order for an application service app to be listed on the public safety network mobile app store, a dataset of malicious and normal app is first established to extract characteristics and select the most effective AI model to perform static and dynamic analysis. According to the analysis results, 'Safety App Certificate' is certified for non-malicious app to secure reliability for listed apps. Ultimately, it minimizes the security blind spots of public safety network app. In addition, the safety of the network can be secured by supporting public safety application service of certified apps.

• Earthquakes and Structures
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• v.20 no.2
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• pp.133-148
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• 2021

The paper presents a simplified force-based seismic design procedure for the preliminary design of steel haunch retrofitting for the seismic upgrade of deficient RC frames. The procedure involved constructing a site-specific seismic design spectrum for the site, which is transformed into seismic base shear coefficient demand, using an applicable response modification factor, that defines base shear force for seismic analysis of the structure. Recent experimental campaign; involving shake table testing of ten (10), and quasi-static cyclic testing of two (02), 1:3 reduced scale RC frame models, carried out for the seismic performance assessment of both deficient and retrofitted structures has provided the basis to calculate retrofit-specific response modification factor Rretrofitted. The haunch retrofitting technique enhanced the structural stiffness, strength, and ductility, hence, increased the structural response modification factor, which is mainly dependent on the applied retrofit scheme. An additional retrofit effectiveness factor (ΩR) is proposed for the deficient structure's response modification factor Rdeficient, representing the retrofit effectiveness (ΩR=Rretrofitted /Rdeficient), to calculate components' moment and shear demands for the retrofitted structure. The experimental campaign revealed that regardless of the deficient structures' characteristics, the ΩR factor remains fairly the unchanged, which is encouraging to generalize the design procedure. Haunch configuration is finalized that avoid brittle hinging of beam-column joints and ensure ductile beam yielding. Example case study for the seismic retrofit designs of RC frames are presented, which were validated through equivalent lateral load analysis using elastic model and response history analysis of finite-element based inelastic model, showing reasonable performance of the proposed design procedure. The proposed design has the advantage to provide a seismic zone-specific design solution, and also, to suggest if any additional measure is required to enhance the strength/deformability of beams and columns.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.585-591
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• 2021

Objective : Filum transection is one of the most commonly performed operative procedure in pediatric neurosurgery. However, the clinical and pathological features as well as the surgical indication are not well-established. This study aimed to analyze the characteristics of patients who underwent transection of the filum during the last 10 years in a single institute. Methods : A total of 82 patients underwent transection of the filum during the period. As a general rule, we performed the transection in patients who are symptomatic or have abnormality in the urologic or neuromuscular evaluations. There were exceptions as asymptomatic patients who only fit the definition of thickened filum (width greater than 2.0 mm or conus level below L3 vertebral body) were operated by parent's wish or surgeon's preference according to radiological findings, etc. Results : Seventy-six out of 82 patients had fibrous tissue in the pathologic specimen of filum. Interestingly, patients who had glial cells were more correlated with no preoperative syrinx, and no progression of syrinx even for those who did have syrinx initially. Also, larger percentage of symptomatic patients had peripheral nerve twigs than asymptomatic patients. No difference in conus level or thickness of filum was found between patients with or without preoperative syrinx. Significantly more patients with syrinx (56%) were chosen to be operated without any symptom or abnormality in study i.e., solely based on radiological findings than those without syrinx (21%). The surgical outcome for syrinx was favorable, as all but one patient had either improved or static syrinx. The exceptional case had increase in size due to the upward displacement of the proximal end of the cut filum. Conclusion : This study evaluated the pathological, clinical, radiological features of patients who underwent transection of the filum. Interesting correlations between pathological findings and clinical features were found. Excellent outcome regarding preoperative syrinx was also shown.

• Journal of the Korean GEO-environmental Society
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• v.12 no.11
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• pp.65-70
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• 2011

It is well known all much information for evaluation on possibility of liquefaction and lateral flow for sand over the world. Recently, it is started to be known that liquefaction happens on non-plastic silt, too. But cyclic and post-cyclic characteristics for non-plastic silt is a few familiar to the world. Specially, it is not aware of the estimating method for lateral flow on non-plastic silt. The main purpose in this paper is to propose the evaluation for liquefaction and lateral flow on non-plastic silt. The method used in this research is that possibility for liquefaction on non-plastic silt was evaluated with cyclic direct simple shear test, and then residental strength was estimated with static shear test. Through the test results liquefaction on non-plastic silt is well not happened but strength decreases rapidly with increasing shear stress. With the proposed method it can be evaluated possibility of liquefaction and propose lateral flow.

• Korean Journal of Metals and Materials
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• v.50 no.12
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• pp.873-882
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• 2012

Dual Phase (DP) steel which has a soft ferrite phase and a hard martensite phase reveals both high strength and high ductility and has received increased attention for use in automotive applications. To conduct structural analysis to verify vehicle safety, highly credible experimental results are required. In this study, tensile tests were performed in a strain rate range from $10^{-4}/s$ to 300/s for Sink Roll-Less (SRL) hot-dip metal coated sheets. Collision properties were estimated through simulation by LS-DYNA using the stress-strain curve obtained from the tensile test. The simulation results were compared with the actual crash test results to confirm the credibility of the simulation. In addition, a tensile test and a crash test with 2% prestrain and a baking (PB) specimen were evaluated identically because automotive steel is used after forming and painting. The mechanical behaviors were improved with an increasing strain rate regardless of the PB treatment. Thus, plastic deformation with an appropriate strain rate is expected to result in better formability and crash characteristics than plastic deformation with a static strain rate. The ultimate tensile strength (UTS) and absorbed energy up to 10% strain were improved even though the total elongation decreased after PB treatment, The results of the experimental crash test and computer simulation were slightly different but generally, a similar propensity was seen.

• Atmosphere
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• v.31 no.1
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• pp.85-100
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• 2021

The necessity of accurate high-resolution meteorological forecasts becomes increasing in socio-economical applications and disaster risk management. The Korea Meteorological Administration Post-Processing (KMAPP) system has been operated to provide high-resolution meteorological forecasts of 100 m over the South Korea region. This study evaluates and improves the KMAPP performance in simulating wind speeds over complex terrain areas using the ICE-POP 2018 field campaign measurements. The mountainous measurements give a unique opportunity to evaluate the operational wind speed forecasts over the complex terrain area. The one-month wintertime forecasts revealed that the operational Local Data Assimilation and Prediction System (LDAPS) has systematic errors over the complex mountainous area, especially in deep valley areas, due to the orographic smoothing effect. The KMAPP reproduced the orographic height variation over the complex terrain area but failed to reduce the wind speed forecast errors of the LDAPS model. It even showed unreasonable values (~0.1 m s-1) for deep valley sites due to topographic overcorrection. The model's static parameters have been revised and applied to the KMAPP-Wind system, developed newly in this study, to represent the local topographic characteristics better over the region. Besides, sensitivity tests were conducted to investigate the effects of the model's physical correction methods. The KMAPP-Wind system showed better performance in predicting near-surface wind speed during the ICE-POP period than the original KMAPP version, reducing the forecast error by 21.2%. It suggests that a realistic representation of the topographic parameters is a prerequisite for the physical downscaling of near-ground wind speed over complex terrain areas.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.3
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• pp.412-418
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• 2021

This study aims to investigate the influence of emotional engineering factors on brand preference and loyalty in smartphone product design. The emotional engineering factor was divided into color, performance, usability, value, and reliability, and the relationship between brand preference and loyalty was empirically analyzed. As a result of the analysis, the emotional engineering factor in the smartphone product design has a positive effect on the brand preference, and the factors having the greatest influence are the performance and color factors. In smartphone product design, the emotional engineering factor has a static effect on loyalty, and the factors that have the greatest influence are reliability and performance factors. The higher the brand preference in product design, the greater the affect on loyalty. It is necessary to approach product design that fits the characteristics of consumers by identifying the influential factors among the product design emotional engineering factors.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.41-47
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• 2020

This study aims to develop eco-friendly propellant that reduce the generation of harmful gases such as HCl gas and increase the emmision of nitrogen gas emissions. For this purpose, GUDN(N-Guanylurea dinitramide) and BTATz(3,6-bis(1H-1,2,3,4-tetrazol-5-ylamino)-1,2,4,5-tetrazine), which are low carbon high nitrogen materials, were used instead of AP(Ammonium Perchlorate) and Al(Aluminium), which are gernerally used in solid propellant. The prepared propellants were analyzed for mechanical properties and combustion characteristics, performance and AGARD smoke classification. Compared with AP/Al propellant, GUDN/BTATz propellant tended to decrease mechanical and combustion rate. Also, as a result of the static test after the production of the 4-inch motor, the performance of combustion of the GUDN/BTATz propellant decreased, but it was confirmed that the secondary smoke was improved by reducing harmful gases such as HCl gas.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.499-511
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• 2022

The purpose of this study is to verify the moderating effect of the social support (emotional support, informational support, material support, and appraisal support) on the effect of depression of middle-aged women on internet addiction. The 509 samples were selected through an online survey, and the collected data were conducted using the SPSS WIN26.0 program for frequency analysis, descriptive statistics, correlation analysis, and hierarchical regression analysis. As a result of the analysis, depression had a static effect on Internet addiction. Informational support and material support, among the four sub-factors of social support served as a moderator variable in the relationship between depression and Internet addiction. Based on the results, the followings were proposed; It emphasizes differentiated welfare services and interdisciplinary convergence research that are suitable for middle-aged women's characteristics, and suggests the necessity of internet addiction prevention education such as proper usage habits for internet use.