• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.10
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• pp.896-908
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• 2014

The electrical medical device market have been expanded since the public interest in healthy living that has deepened together with the global health trend of the aging population. The external hand-held ultrasonic probe is a frequently approved medical device and it is commonly used in the clinical field. However, there is no obvious standard or a guideline in Korea on regarding evaluation of performance of such external hand-held ultrasonic probe for approval and quality management. In this study, local and foreign reference standards were reviewed to propose performance test standards and methods after conducting characteristic of probe, market, and permission status. In addition, such proposed test items were validated to develop a draft guideline that is internationally harmonized for performance evaluation. This study is expected not only improve the quality and performance of the external hand-held ultrasonic probe but also contribute to securing consistency of permission and evaluation works for approval.

• Korean Journal of Construction Engineering and Management
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• v.15 no.5
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• pp.31-39
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• 2014

It has been a long time since cars had become important means of transportation in human life. Since 1970s, cars have been increasing steadily because of rising individual income and changing lifestyle toward leisure and convenience. The number of cars is just 1.8 per thousand populations in 1970s, however, in 2012, it has increased to 291.15. Forecasting the demand for cars would be useful to plan, construction or management in the field of motor industry, road building and establishing facilities. Our study predicts the demand of cars through estimating the growth curve model. Especially, we include ageing variables to forecasting identifying the effect of ageing on the demand of cars. The main findings are as follows. In 2045, the number of cars is expected to reach 486.8 per thousand populations with passing a primary saturation point at early 2020s. Also, due to effect of ageing, the predicted demand of cars is about 10% lower than in case of which if ageing effect not exist.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.6
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• pp.662-669
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• 2015

There has been an increased interest in the mitigation of wax deposition because wax, which usually accumulates in subsea oil-production systems, interrupts stable oil production and significantly increases the cost. To guarantee a required oil flow by mitigating wax deposition, we need to obtain a reliable estimation of the wax deposition. In this research, we perform simulations to understand the major mechanisms that lead to wax deposition, namely molecular diffusion, shear stripping reduction, and aging. While the model variables (shear reduction multiplier, wax porosity, wax thermal conductivity, and molecular diffusion multiplier) can be measured experimentally, they have high uncertainty. We perform an analysis of these variables and the amount of water and gas in the multiphase flow to determine these effects on the behavior of wax deposition. Based on the results obtained during this study for a higher wax porosity and molecular diffusion multiplier, we were able to confirm the presence of thicker wax deposits. As the shear reduction multiplier decreased, the thickness of the wax deposits increased. As the amount of water increased, there was also an increase in the amount of wax deposits until 40% water cut and decreased. As the amount of gas increased, the amount of wax deposits increased because of the loss of the light hydrocarbon component in the liquid phase. The results of this study can be utilized to estimate the wax deposition behavior by comparing the experiment (or field) and simulation data.

• Smart Media Journal
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• v.6 no.4
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• pp.58-64
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• 2017

Modern society is characterized by rapid increase in world population, aging of the rural population, decrease of cultivation area due to industrialization. The food problem is becoming an important issue with the farmers and becomes rural. Recently, the researches about the field of the smart farm are actively carried out to increase the profit of the rural area. The existing smart farm researches mainly monitor the cultivation environment of the crops in the greenhouse, another way like in the case of poor quality t is being studied that the system to control cultivation environmental factors is automatically activated to keep the cultivation environment of crops in optimum conditions. The researches focus on the crops cultivated indoors, and there are not many studies applied to the cultivation environment of crops grown outside. In this paper, we propose a method to improve the harvestability of poor areas by monitoring the areas with bad harvests by using big data analysis, by precisely predicting the harvest timing of fruit trees growing in orchards. Factors besides for harvesting include fruit color information and fruit weight information We suggest that a harvest correlation factor data collected in real time. It is analyzed using the Apache Spark engine. The Apache Spark engine has excellent performance in real-time data analysis as well as high capacity batch data analysis. User device receiving service supports PC user and smartphone users. A sensing data receiving device purpose Arduino, because it requires only simple processing to receive a sensed data and transmit it to the server. It regulates a harvest time of fruit which produces a good quality fruit, it is needful to determine a poor harvest area or concentrate a bad area. In this paper, we also present an architectural model to determine the bad areas of fruit harvest using strong data analysis.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.334-339
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• 2008

Construction that over 70% of the structure consists of concrete gets bigger and higher gradually and the demand of that is increasing as well. However, it's not easy to supply young and skilled persons on construction site because of social avoidance phenomena about 3D occupation, so it causes serious problems like aging and shortage of technicians. To solve the problems, executives related to the construction field make a management effort in various ways such as construction period shortening, labor productivity improvement and good quality but recently, they have an increasing interest in the necessity of the modularization of the high-rise building and the automation of the engineering development for the strengthening of international competitive power as more active and long-term alternatives. Therefore, this study is to propose the roadmap in order to make lots of efforts in developing construction technologies of high-rise buildings by performing a foundation study, the strategy for 4-step research development, on modularized construction system of concrete structure of high-rise buildings through domestic and foreign preceding research analyses associated with optimal design modularization technique, module factory automation and assembly automation of modularized objects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.233-238
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• 2020

Although the interest in NBR has been increasing due to the recent developments of the aerospace sector, there are few reports on HNBR's aeronautical oil, particularly evaluations of the accelerated life of harsh factors. In this study, the tensile strength was adopted as a performance evaluation factor to evaluate the accelerated life of HNBR used in the aviation field. The accelerated stress factor affecting the performance-aging characteristics was defined as temperature. The acceleration stress factor was determined to be temperature, and the result of measuring the tensile strength change over time. The sample for the acceleration condition was taken out of the oven for a certain period and left at room temperature for 24 hours. The dumbbell type 3 specimens were manufactured according to the standard specified in KS M 6518 and were measured the tensile strength, a factor in accelerated life evaluations. The activation energy was 0.895, and the shape parameter was 1.152 using the Arrhenius model. The characteristic life obtained from the tensile strength of the HNBR specimen immersed in aviation oil at 20℃ was 272,256 hours; the average life was 258,965 hours, and the B10 life was 38,624 hours.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.5
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• pp.1-12
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• 2017

The purpose of this study is to investigate the trends of the start-up research in Korea. To accomplish this, meta-analysis was carried out using text mining methodology by dividing the entrepreneur-related master's and doctoral theses registered in RISS into the first term of entrepreneurship research by 2009 and the second term of entrepreneurship research from 2010. As a result of this study, it can be seen from the three different analysis that the entrepreneurship education and government policy and support are the subject of continuous research topics in the whole period and that the researches on small business start-ups have been studied continuously and conducted more in the second half. In addition, empirical analysis is strengthened in the latter stage of entrepreneurial research. The TF-IDF analysis reveals that many researches on veterans have been carried out in the field of entrepreneurship research, and in the latter period, it was found that many studies related to the elderly were conducted with cultural contents and aging society. In addition, research on brand-related research has been carried out throughout the entire period, and research on venture-related research, characteristics of entrepreneurs, entrepreneurship motivation and start-up strategy have been conducted a lot and female entrepreneurship was also studied. In the latter period, we have emphasized entrepreneurial achievements and found that research on start-ups such as industry-academia cooperation, start-up investment, and social enterprise diversified. This study is meaningful to apply the method which is becoming a recent issue such as text mining and topic analysis to the meta-analysis related to start-up. Future research will need to be undertaken on a variety of more detailed topics related to entrepreneurship.

• The Journal of Engineering Geology
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• v.28 no.3
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• pp.501-512
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• 2018

The acid leachate derived from the sulfide mineral such as pyrite can cause problems such as aging of infrastructure and environment contamination around the civil construction site. The purpose of this study is to assess the environmental effect of an acid leachate derived from pyrite in the Miryang area under road construction. In this study, 13 samples of situ core were used for the net acid generation (NAG) experiment. The chemical composition including pH, oxidation and reduction potential (ORP) and electrical conductance of water samples produced from the NAG test was analyzed. In additional, five polished thin sections of rock cores were made for electro microprobe analyses. In the results of the NAG tests, 7 samples showed lower values than pH 3.5. It strongly indicated that these areas are under the environmental and infrastructure damage by the acid leachate. The chemical type of the 7 samples was classified as the $Fe(Ca)-SO_4$ type, which is totally a different type compared to general groundwater. The concentration of total sulfur ranges from 0.004% to 12.5%. 6 rock samples are plotted on a potentially acid forming zone in the relation diagram between the total sulfide and NAG-pH. In conclusion, it is suggested that a protection method against an environmental demage and an infrastructure corrosions by the acid leachate should be prepared in all of areas under a road construction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.675-684
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• 2020

To prevent safety accidents caused by aging pipe infrastructure and to maintain water quality, construction projects for water and sewage pipes are actively conducted across Korea. This study analyzed the criteria situations, site survey details, and regulation revisions related to the calculation of construction cost standards for pipe laying and joining work. The analysis showed that the major causes for revision are the unclear construction scope, limitations in implementing some pipe materials due to installation facility types, workforce focused on ordinary labor, limitations of manual laying work, and the lack of tool hire cost and machine expense-calculation criteria. Field studies were conducted to categorize the pipes according to their features, in addition to identifying the use of lifting heavy equipment and light equipment. In addition, excavation and testing work conducted in connection to pipe laying, as well as the use of skilled labor, were investigated. The current study clarified the work scope through new common items, provides an organization based on the pipe material, adjusted the workforce ratio to focus more on skilled labor, and developed grounds for calculating machine expenses. These revisions were estimated to save approximately 1.28% of the construction costs in each project according to an analysis of the construction cost impact study. truction costs in each project, according to an analysis of construction cost impact study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.355-362
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• 2016

The pipe material is selected according to the physical and chemical properties of the fluid flowing within it. Because the fluid used in fire extinguish systems is water, the various foreign substances dissolved in it cause scale to form on the pipe wall and accelerate the corrosion and aging of the pipe itself. This results in an increase in the friction loss and eventually degrades the efficiency of the pump. The use of CPVC (Chlorinated Poly-Vinyl Chloride) pipes was confirmed to reduce the friction loss compared to conventional steel pipes in the design and construction stages. The friction loss was found to be 76.64MPa with a C-value of 120 for the steel pipe and 50.72 MPa with a C-value of 150 for the CPVC pipe in an actual apartment construction environment. It was confirmed that the friction loss was improved by about 34% when using the CPVC pipe. When the steel and CPVC pipes were employed in the construction, the construction costs were 1,585,158 and 931,842 won, respectively. Therefore, it was shown that the construction cost was reduced by about 41%. We investigated the safety of the fire extinguishing system and the improvement in the economic performance due to the reduction in the total installed capacity by studying practical applications in the field.