• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.10-20
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• 2013

To evaluate the safety of a beam structure, strains are measured as an indicator of structural states. However, unless strain sensors are installed exactly on where maximum or other representative strains occur, the techniques by which rational assessment through measured strains is accomplished are required. Thus, this study suggests a process to estimate strain distribution on the steel beam from discrete strains measured by sensors. In the presented technique, the targeted beam is regarded to be subjected to unknown loads so that applicability is enhanced. Final strain distribution is given as form of a function after regression analysis. To verify the performance of estimation, a bending test for steel beam on which distributed and concentrated loads simultaneously act is conducted. From the comparison between estimated and directly measured strains in the test, the curve of strain distribution and the strain at arbitrary location could be predicted within maximum relative error 3.32% and maximum absolute error of $2.32{\mu}{\varepsilon}$, respectively. Thus reliable and practical monitoring is expected to apply effectively for the steel beam structure.

• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.44-49
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• 2020

In this paper, a measuring circuit is designed through analyzing manufacture specification of the sensor based on MOS. And the best input-output polynomial are induced that really gas sensors are used in gas safety management industrial fields. Response characteristics of a MOS gas sensor is analysed by through sensor's output voltages are measured after standard gases with six kinds of concentrations are manufactured and are injected to the sensor. A lookup table is created by relations of sensor's output voltages by injecting gases with other concentrations. Because data of the formed lookup table are equal interval, a polynomial can be induced of method of approximation function. So the 5th polynomial of input-output for a sensor is defined, coefficients are calculated by using least squares method, and the 5th polynomial is completed for representing characteristics of the sensor. If the proposed polynomial is applied to gas leak detectors, an inverse transformation of polynomial and programing of array codes are recreated. In this research, polynomial is implemented with array types that intervals of values of a lookup table are one-fifth sampled and interpolated. The performance of proposed 5th calibration equation is verified that errors are reduced than a linear expression when tests are performed by measurement of concentrations against injection of standard gases.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.335-343
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• 2010

Steel corrosion in reinforced concrete (RC) structures is a critical problem to structural safety and many researches are being actively conducted on developing methods to maintain the required performance of the RC structures during their intended service lives. In this study, concrete mixture proportioning technique through genetic algorithm (GA) for RC structures under carbonation, which is considered to be serious in underground site and big cities, is investigated. For this, mixture proportions and diffusion coefficients of $CO_2$ from the previous researches were analyzed and fitness function for $CO_2$ diffusion coefficient was derived through regression analysis. This function based on the 12 experimental results consisted of 5 variables including water-cement ratio (W/C), cement content, sand percentage, coarse aggregate content per unit volume of concrete in unit, and relative humidity. Through genetic algorithm (GA) technique, simulated mixture proportions were proposed for 3 cases of verification and they showed reasonable results with less than relative error of 10%. Finally, assuming intended service life, different exposure conditions, design parameters, intended $CO_2$ diffusion coefficients, and cement contents were determined and related mixture proportions were simulated. This proposed technique is capable of suggesting reasonable mix proportions and can be modified based on experimental data which consider various mixing components like mineral admixtures.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.421-432
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• 2020

This paper proposes a 2-kW solid-state power amplifier (SSPA) developed by employing power amplifier pallets designed using gallium-nitride high electron mobility transistors, which is used in S-band military radars and to replace existing traveling-wave tube amplifier (TWTA). The SSPA consists of a high-power amplifier module, which combines eight power amplifier pallets, a drive amplifier module, a digital control module, and a power supply unit. First, the amplifier module and component were integrated into a small package to account for space limitations; next, an on-board harmonic filter was fabricated to reject spurious components; and finally, an auto gain control system was designed for various duty ratios because recent military radar systems are all active phase radars using the pulse operation mode. The developed SSPA exhibited a max gain of 48 dB and an output power ranging between 63-63.6 dBm at a frequency band of 3.1 to 3.5 GHz. The auto gain control function showed that the output power is regulated around 63 dBm despite the fluctuation of the input power from 15-20 dBm. Finally, reliability of the developed system was verified through a temperature environment test for nine hours at high (55 ℃) / low (-40℃) temperature profile in accordance with military standard 810. The developed SSPA show better performance such as light weight, high output, high gain, various safety function, low repair cost and short repair time than existing TWTA.

• Archives of design research
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• v.13 no.2
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• pp.73-80
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• 2000

In this study design information was separately defined form general product information and thus factors reflected in product design ion the basis of values and roles were extracted. The following is a classification of 5 different types of design factors divided according to their disposition. ·Innovation factor - element which previously did not exist or element related with explicit reformation ·Open factor - active element which not only improves current performance but also induces new functions through understanding of usage situations and new possibilities. ·Anterior factor - element which prolongs and develops the early development requirements of products through C.I. and P.I. related elements and characteristics of previous models and design strategy. Self-evidence factor - element related with function visualization through product structure which may make possible the consolidation of shape and function. Rigid factor - element, based on the human factors engineering, related with the safety and efficiency of users. This classification was obtained by defining major characteristics of products considering the target consumer and market characteristics. In this classification factor structuring design process which efficiently deducted a differentiated final product by synthesizing factors of higher importance as dominant factors was proposed. With this kind of factor structuring process, product differentiation may be achieved by bestowing individual characteristics to each product by combining design dominant factors associated with the product for a specific purpose from the stages of product concept development. Moreover, this may be used as an approach to actively correspond to the various and specific demands of the comsumer.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.14
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• pp.5951-5957
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• 2014

Background: Traditional Chinese Medicine (TCM) possesses several advantages for treating patients with hepatocellular carcinoma (HCC). The theory of 'Jianpi Huayu Therapy' rooted from 'Jin Kui Yao Lue'is one of the most important therapies in this respect. This study was conducted to investigate the clinical effect and safety of hepatectomy combining with 'Jianpi Huayu Therapy' in the treatment of HCC. Materials and Methods: One hundred and twenty patients with HCC were randomized allocated into hepatectomy combined with 'Jianpi Huayu Therapy' group (treatment group, n=60) and hepatectomy alone group (control group, n=60). Disease- free survival (DFS) and overall survival (OS) were the primary end-points. Liver function at the end of one week after surgery, complications, average days of hospitalization as well as performance status (PS) at the end of one month post operation were also compared. Results: No significant differences existed between two groups on baseline analysis (p>0.05). No treatment related mortality occurred in either group. Post-operative complications were detected among 14 patients (23.3%) in the treatment group, and 12 (20.0%) in the control group (p=0.658). Alanine aminotransferase (ALT) at the end of one week after operation was lower in the treatment than control groups (p=0.042). No significant differences in other indexes of liver function were discovered between two groups. Average days of hospitalization reduced by 0.9 day in treatment group than in control (p=0.034). During follow-up, 104 patients (86.6%) developed recurrence. The rates of 1-, 3-, and 5-year DFS and median DFS for all patients were 77.4%, 26.3%, 9.0% and 25.6 months (range, 6.0~68.0), respectively (78.2%, 29.2%, 14.3% and 28.7 months for the 48 patients in the treatment group and 75.0%, 23.3%, 6.4%, and 22.6 months for the 56 patients in the control group (p=0.045)). 101 patients had died at the time of censor, with 1-, 3-, and 5-year overall survival rates and median survival for all patients of 97.5%, 76.4%, 40.5% and 51.2 months (range, 10.0~72.0), respectively (98.3%, 78.0%, 43.6% and 52.6 months, for treatment and 96.7%, 74.7%, 37.4%, and 49.8 months, for controls, respectively (p=0.048)). Conclusions: Hepatectomy combined with 'Jianpi Huayu therapy'was effective in the treatment of HCC, and reduced post-operative recurrence and metastasis and improved DFS and OS of HCC patients.

• Journal of the Korea Institute of Building Construction
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• v.21 no.5
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• pp.433-443
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• 2021

Value Engineering(VE) is an organized effort to create the most value through a functional analysis and creation of alternatives. Depending on the VE job plan, a VE Workshop must be performed in a certain place within a certain period of time. A VE Workshop, which is an organized activity that aims to create the best value through functional analysis and creation of alternatives, should be held in a certain place and at a scheduled time according to the VE job plan. In the Pre-Study, VE Study and Post-Study phases of VE, functional assessments, performance evaluations and idea evaluations are driven by variable management techniques and analysis methods, respectively. Generally, VE is executed for about 3 to 5 days in a particular place to create value. However, there are many problems associated with limiting all VE processes to a specific place and schedule. Moreover, in Korea, VE teams are required to finish all VE processes in a limited time because of the short duration of VE workshops, the necessity of which has been overlooked. Therefore, an efficient VE support system is required to resolve the problem of time and space limitations. In this study, a VE support system based on the Mobile environment was developed to support the VE Workshop process. This VE support system enables participants to review design documents, drawing sheets and all VE-related documents using mobile devices. After the Workshop, participants can conveniently rearrange the result(evaluation of function and ideas) at the workshop. Not only can the members of VE team can review the design documents, drawing sheet and all VE-related documents in the step before the workshop, but also the result(evaluation of function and ideas) of the workshop can be easily rearranged in the phase after the workshop under the developed supporting system using mobile devices.

• 한국노년학
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• v.38 no.1
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• pp.225-241
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• 2018

Self-driving is meaningful activity for older persons because it enlarges the range of activity and provides opportunities for social participation. Driving is a complex activity that requires integration of physical, cognitive and sensory functions and is influenced by human and psychological factors. Age related functional deterioration affects the driving ability of older drivers. The purpose of this study is to investigate the factors affecting the risk of accidents and driving cessation of elderly drivers through systematic literature review. MEDLINE, EMBASE, Cochrane Library, KoreaMed, Pubmed were used for searching articles published from 2007 to 2017. 'aged', 'aging', 'automobile driving', 'age factors' were used as search terms and 18 articles were finally selected for analysis among 1,458 articles. In result of the study, the most significant effect showed in the physical domain, the driving habit and the performance function. The most frequent used tools evaluated driving habit and the cognitive function. In demographic characteristics, there was a correlation with the driving discontinue according to sex and age. This study emphasizes the necessity of preparing measures for safety driving with elderly. In addition, it suggests the necessity of systematically services such as individual education programs based on various driving cessation related factors of the elderly.

• Fire Science and Engineering
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• v.33 no.2
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• pp.145-154
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• 2019

The purpose of this study is to analyze the self-status of fire service personnel to identify their effect on self-efficacy and job satisfaction, and to improve the performance of their tasks in the field and perform their tasks efficiently. A survey of 177 current firefighters in the southern city of Gyeonggi Province conducted a correlation analysis and regression analysis through SPSS 22.0. The first study found that in relation to the self-status factor and the self-efficacy factor of firefighting services, the self-efficacy is rather high and the self-regulating effect is very high. Second, the effects of the self-status factor on the self-efficacy were significant in order of type Adult (A), type Free Child (FC), and type Adapted Child (AC). Third, analysis of correlation between self-status factors and job satisfaction factors showed inadequate correlation in all job satisfaction factors for Critical Parent (CP) types, and static correlation in all job satisfaction for Nurturing Parent (NP) types. Type Adapted Child (AC) was less satisfying to itself, to itself, to pay, to promote, to co-workers. Thus, the current strategic approach based on rationality needs to be strengthened by lowering the authority of the Critical Parent (CP) function in terms of self-status factors and enhancing the Adapted Child (AC) function in the lower satisfaction level of the parent.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.2
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• pp.104-108
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• 2023

Because of recent expansion of the electric car market. it is highly growing that should be supplemented its performance and safely issue. The EMI problem due to the interlocking of electrical components that causes various safety problems such as fire in electric vehicles is emerging every time. We strive to achieve optimal charging efficiency by combining various technologies and reduce radioactive noise among the EMI noise of a weirless charging control module, one of the important parts of an electric vehicle was designed and tested. In order to analyze the EMI problems occurring in the wireless charging control module, the optimized wireless charging control module by applying the optimization design technology by learning the accumulated test data for critical factors by utilizing the Python-based script function in the Ansys simulation tool. It showed an EMI noise improvement effect of 25 dBu V/m compared to the charge control module. These results not only contribute to the development of a more stable and reliable weirless charging function in electric vehicles, but also increase the usability and efficiency of electric vehicles. This allows electric vehicles to be more usable and efficient, making them an environmentally friendly alternative.