• Journal of the Korea institute for structural maintenance and inspection
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• 제27권3호
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• pp.71-79
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• 2023

It is not efficient to install a maintenance system that measures seismic acceleration and displacement on all bridges and buildings to evaluate the safety of structures after an earthquake occurs. In order to maintain this, an on-site investigation is conducted. Therefore, it takes a lot of time when the scope of the investigation is wide. As a result, secondary damage may occur, so it is necessary to predict the safety of individual structures quickly. The method of estimating earthquake damage of a structure includes a finite element analysis method using approved seismic information and a structural analysis model. Therefore, it is necessary to predict the seismic information generated at arbitrary location in order to quickly determine structure damage. In this study, methods to predict the ground response spectrum and acceleration time history at arbitrary location using linear estimation methods, and artificial neural network learning methods based on seismic observation data were proposed and their applicability was evaluated. In the case of the linear estimation method, the error was small when the locations of nearby observatories were gathered, but the error increased significantly when it was spread. In the case of the artificial neural network learning method, it could be estimated with a lower level of error under the same conditions.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제40권4호
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• pp.164-170
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• 2017

The CNC machine tool field is showing a growing trend with the recent rapid development of manufacturing industries such as semiconductors, automobiles, medical devices, various inspection and test equipment, mechanical metal processing equipment, aircraft, shipbuilding and electronic equipment. However, small and medium-sized machining companies that use CNC machine tools are experiencing difficulties in increasingly intense competition. Especially, small companies which are receiving orders from 3rd or 4th venders are very difficult in business management. In recent years, company S experienced difficulty to make product quality and delivery time due to the ignorance of the processing method when manufacturing cooling plate jig made of SUS304 material used for cell phone liquid crystal glass processing. In order to solve these problems, we redesigned the process according to the size of our company and tried to manage all processes with quantified data. In the meantime, we have found that there is a need to improve the cutter process, which accounts for most of the machining process. Therefore, we have investigated the correlation between RPM and FEED of three cutters that have been used in the past. As a result, we found that it is the most urgent problem to solve the roughing process during the cutter operation which occupies more than 70% of the total machining. In order to shorten the machining time and improve the quality in machining of SUS304 cooling plate jig, we select the main factors such as price, tool life, maintenance cost, productivity, quality, RPM, and FEED and use AHP to find the most suitable milling cutter. We also tried to solve the problem of delivery, quality and production capacity which was a big problem of S company through experiment operation with selected cutter tool. As a result, the following conclusions were drawn. First, the most efficient of the three cutters currently available in the machining center has proven to be an M-cutter. Second, although one additional facility was required, it was possible to produce the existing facilities without additional investment by supplementing the lack of production capacity due to productivity improvement. Third, the Company's difficulties in delivery and capacity shortfalls have been resolved. Fourth, annual sales increased by KRW 109 million and profits increased by KRW 32 million annually. Fifth, it can confirm the usefulness of AHP method in corporate decision making and it can be utilized in various facility investment and process improvement in the future.

• Journal of Intelligence and Information Systems
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• 제29권3호
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• pp.79-101
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• 2023

The current status of local road pavement management in Jeollabuk-do only relies on the accomplishments of the site construction company's pavement repair and is only managed through Microsoft Excel and word documents. Furthermore, the budget is irregular each year. Accordingly, a systematic maintenance plan for local roads is necessary. In this paper, data related to road damage and road environment were collected and processed to derive possible areas which could suffer from road damage. The effectiveness of the methodology was reviewed through the on-site inspection of the area. According to the Ministry of Land, Infrastructure and Transport, in 2018, the number of damages on general national roads were about 47,000. In 2019, it reached around 38,000. Furthermore, the number of lawsuits regarding the road damages were about 93 in 2018 and it increased to 119 in 2019. In the case of national roads, the number of damages decreased compared to 2018 due to pavement repairs. To measure the priorities in maintenance of local roads at Jeollabuk-do, data on maintenance history, local port hole occurrence site, overlapping business section, and emergency maintenance section were transformed into data. Eventually, it led to improvements in maintenance of local roads. Furthermore, spatial data were constructed using various current status data related to roads, and finally the data was processed into a new form that could be utilized in machine learning and predictions. Using the spatial data, areas requiring maintenance on pavement were predicted and the results were used to establish new budgets and policies on road management.

• Journal of the Korea Society of Computer and Information
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• 제28권4호
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• pp.105-112
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• 2023

In this paper, we propose a new method for displaying colored defects by measuring the relative density with the wide-area and local densities of X-ray. The relative density of one pixel represents a relative difference from the surrounding pixels, and we also suggest a colorization of X-ray images representing these pixels as normal and defective. The traditional method mainly inspects materials such as plastics and metals, which have large differences in transmittance to the object. Our proposed method can be used to detect defects such as sprouts or holes in images obtained by an inspection machine that detects X-rays. In the experiment, the products that could not be seen with the naked eye were colored with pests or sprouts in a specific color so that they could be used in the agricultural product selection system. Products that are uniformly filled with a single ingredient inside, such as potatoes, carrots, and apples, can be detected effectively. However, it does not work well with bumpy products, such as peppers and paprika. The advantage of this method is that, unlike machine learning, it doesn't require large amounts of data. The proposed method could be applied to a screening system using X-rays and used not only in agricultural product screening systems but also in manufacturing processes such as processed food and parts manufacturing, so that it can be actively used to select defective products.

• 보존과학연구
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• 통권22호
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• pp.115-132
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• 2001

No. 3 Tomb of Bogam-ri, in Naju City, Chollanam-do Province, was a site excavated and inspected from 1996 to 1998 and had a various grave forms, including jar-coffins, stone-chambers and stone-cists. Although most of the metal artifacts excavated from it were severely corroded, we could implement microstructure investigation by collecting samples from the iron axes, iron coffin-nails and iron clamps in which the metal parts were remained. The metal structures were inspected by using metallographic microscope and SEM, and fine components analysis was implemented by ICP. To examine the hardness differences in accordance with the structure distribution, we measured the hardness by structures with Vickers hardness testing machine. As a result of the metal structure inspection, most of them were pure iron, ferrite, and also pearlite, cementite and widmannstaten structures were displayed. We could confirm carbonization was formed on the surface of the iron axes-B, iron coffin-nails-B, and iron clamps-A. There was no carbonization in the rest of the artifacts, and it is not certain that whether the carbonized parts were peeled off through extreme corrosion or they were not carbonized when they were made. In the particular part of a blade, the quality of the material was strengthened through processing. Due to the processing re-grain was caused and fine grain particles were formed. As a result of the ICP component analysis, there were no addition atoms because pure irons were used as materials. In the mean time, No. 17 jar-coffin where the iron axes-A are excavated, is chronologically ordered as from the late-fourth century to the mid-fifth century, and No. 1 and No. 2 stone chambers, where the rest of the artifacts were excavated, as the early-sixth century. It was difficult to relate the periodic differences with the manufacture technique artifacts which we inspected because there were no distinct characteristics of the manufacture technique of the metal structures and it is impossible to conclude the artifacts and sites are at the same period although their periods are different.

• Journal of Fashion Business
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• 제16권5호
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• pp.207-219
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• 2012

It is intended to study the colors of work environment and the working clothes colors between humans and environment with application of the arrangement of working clothes colors to domestic machinery companies that play pivotal roles in the industry of Korea. The purpose of this study is to provide the foundation of color plan for the integrated environmental harmonization and the safety of industrial sites by analyzing the photographs of working clothes in the sires in consideration of the functions of colors (clearness, attention-getting, and safety) using the Faber Birren's Color Harmony and by analyzing the result of a questionnaire survey. The study was conducted by the method to shoot a worksite using a digital camera after wearing 24 sets of uniforms, which were developed by the color plan established in a previous study, in the same worksite. The shooting place was an outdoor steel sheet inspection site of D company, a machinery company in Changwon-si, Gyeongnam, and the intensity of illumination was 2400lux. 24 pieces of images were printed in 5x7 inch size and a questionnaire survey was performed at 5-point scale. The questionnaire survey was performed for 13 subjects consisting of 6 field professionals having more than 30 years of experiences, 4 clothes color professionals, and 3 industrial engineering professionals. The result of the survey was statistically analyzed by the method of frequency analysis using IBM SPSS Statistics 20 Program. As the result of assessment of basic four colors (yellow green, sky blue, blue, and violet) of working clothes, yellow green, sky blue, and blue showed high mean values in (Tint)+(Shade)+(Tone)+(Gray) equation indicating that its is a harmonized equation.

• Geomechanics and Engineering
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• 제13권1호
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• pp.141-159
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• 2017

A pick cutter is a rock-cutting tool used in partial-face excavation machines such as roadheaders, and its quality is a key element influencing the excavation performance and efficiency of such machines. In this study, pick cutters with hardfacing deposits applied to a tungsten carbide insert were made with aim of increasing their durability and wear resistance. They were field-tested by being installed in a roadheader and compared with conventional pick cutters under the same excavation conditions for 24 hours. The hardfaced pick cutters showed much smaller weight loss after excavation, and therefore better excavation performance, than the conventional pick cutters. In particular, the damage to and detachment (loss) of tungsten carbide inserts was minimal in the hardfaced pick cutters. A detailed inspection using scanning electron microscope-energy dispersive X-ray spectrometry and three-dimensional X-ray computed tomography scanning revealed no macro- or micro-cracks in the pick cutters. The reason for the absence of cracks may be that the heads of pick cutters are mechanically worn after the tungsten carbide inserts have been worn and damaged. However, scanning revealed the presence of voids between tungsten carbide inserts and pick cutter heads. This discovery of voids indicates the need to improve production processes in order to guarantee a higher quality of pick cutters.

• Journal of Korea Game Society
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• 제15권1호
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• pp.145-154
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• 2015

The objective of this research is to evaluate the usability test of 'Paldokangsan3' which has been developed as a serious game for the elderly to improve their physical and mental health. This game machine has been installed in a silver house for one month that the elderly could play the game as they like in their convenient times. To promote their participations to practice the game, we set 3 contests with gifts for the high scores and collect their data through inspection, questionnaire and interviews by the researchers as well as in-game measurement for the play. Eight people volunteered to join the project. While the result analysis for the usability area of easiness of control, learnability of the game play, memorability and challenge didn't show the statistical confident t-value, most elderly players participated 2~3 times a day for a month even though most of them are suffering mild cognition impairment. They showed good subjective satisfactions in their interviews that we could go on the project further to expand its applications.

• Proceedings of KOSOMES biannual meeting
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• 해양환경안전학회 2006년도 춘계학술발표회
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• pp.213-216
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• 2006

In this paper a development of shaft power measuring system for a small vessel is discussed. It is important that the exact power measurement of marine engine which is used for ship's propulsion since the engine power is related to ship's usage and its shaft design. Two gearwheel and magnetic sensors are adopted to measure torsional angle on the shaft. High resolution encoder is also applied to compensate the output signal from gearwheel. The calculation of shaft power is executed using measured signal and angular velocity of rotating machine and the result is plotted on the monitoring screen.

• Journal of Power System Engineering
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• 제15권2호
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• pp.13-18
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• 2011

This thesis is about the result of conducting a specific experiment for the development of noncontact vibration displacement sensor for measuring the spindle vibration that is used for conditional monitoring of machinery. One should be careful when using the eddy current type displacement sensor because the sensitivity of it is different according to the quality of the material. While the probe used for nondestructive inspection adopts the effect of transmitting the material by using the high frequency domain, the eddy current type displacement sensor uses the lower frequency of around 1MHz. Also, while the nondestructive probe uses the method of enhancing output by using the resonance zone, the vibration displacement sensor utilizes the stable zone by avoiding the resonance zone. Since the oscillator of the converter uses the "L" element as Probe, its characteristic changes with the variation of a relevant impedance. In other words, if the length of Probe's Cable gets extended (Impedance increase), the sensitivity declines accordingly. The effect of surrounding temperature was small, but the influence of the quality of Sensor Coil used was high. Moreover, following an experimental demonstration of the phenomenon where the sensitivity decreases as the frequency of the tested material increases from a frequency response test, the maximum frequency that could be measured was approximately 1KHz. It was noted that the degree of precision could be maintained by using the gap of the probe in the linear zone at the installation site.