• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.269-275
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• 2020

RAM of elements to support weapon systems is conducted at the initial development phase and standard is suggested to accomplish strategy requirement performance from a design spec. Operational availability is a key point of the military's ability to ensure combat readiness and to win the battle. In the weapon system development phase, operational availability is used as a development standard. The military provides ALDT, operation and standby time, which are elements of operational availability. ALDT is a key element of operational availability that must be maintained for combat readiness, as it depends on the aging of a weapon system, maintenance policies and geographical conditions. Operational Availability to be set at the development phase has many differences from the operational availability that is analyzed in the actual operational phase because ALDT is applied as a simple assumption. In the paper, we analyzed ALDT applying the decision tree method through failure data acquired from initial operation. Through this study, we have devised the optimal ALDT setting method to achieve operational availability about operation when the weapons system is unstable.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.6
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• pp.619-627
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• 2016

Cells of a PV (photovoltaic) module can suffer defects due to various causes resulting in a loss of power output. As a malfunctioning cell has a higher temperature than adjacent normal cells, it can be easily detected with a thermal infrared sensor. A conventional method of PV cell inspection is to use a hand-held infrared sensor for visual inspection. The main disadvantages of this method, when applied to a large-scale PV power plant, are that it is time-consuming and costly. This paper presents an algorithm for automatically detecting defective PV panels using images captured with a thermal imaging camera from an UAV (unmanned aerial vehicle). The proposed algorithm uses statistical analysis of thermal intensity (surface temperature) characteristics of each PV module to verify the mean intensity and standard deviation of each panel as parameters for fault diagnosis. One of the characteristics of thermal infrared imaging is that the larger the distance between sensor and target, the lower the measured temperature of the object. Consequently, a global detection rule using the mean intensity of all panels in the fault detection algorithm is not applicable. Therefore, a local detection rule was applied to automatically detect defective panels using the mean intensity and standard deviation range of each panel by array. The performance of the proposed algorithm was tested on three sample images; this verified a detection accuracy of defective panels of 97% or higher. In addition, as the proposed algorithm can adjust the range of threshold values for judging malfunction at the array level, the local detection rule is considered better suited for highly sensitive fault detection compared to a global detection rule. In this study, we used a panel area extraction method that we previously developed; fault detection accuracy would be improved if panel area extraction from images was more precise. Furthermore, the proposed algorithm contributes to the development of a maintenance and repair system for large-scale PV power plants, in combination with a geo-referencing algorithm for accurate determination of panel locations using sensor-based orientation parameters and photogrammetry from ground control points.

• International Journal of Highway Engineering
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• v.4 no.3 s.13
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• pp.43-49
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• 2002

Asphalt pavements have to perform under the conditions of heavily-loaded vehicles due to the industrialization and large temperature variance between the summer and the winter. Due to these factors, a characteristics change of early permanent deformation becomes a big issue, and to remedy this problem many research to use modified asphalt are being widely conducted. However, most of the modified asphalt is being paved after milling the surface course and applying tackcoating, and it is being used mostly for the repair and maintenance purpose rather than pavement of new national road. The purpose of this investigation is to obtain some fundamental data for the evaluation of the performance and long-term performance of the construction material mixtures by the laboratory test and field experiments. For the field experiment, 200m of two-lanes national road, that is being paved for the new national road under the direction of Pusan Regional Construction Management Office, was paved with SBS PMA and PSMA asphalt mixtures, which are an modified asphalt mixtures used for the surface course, on top of the base course paved with other modified asphalt mixtures. The remaining section of the new national road was paved with dense grade mixture. The laboratory tests assessed and analyzed the mixture characteristics by Marshall's stability test, strength tests and wheel-tracking test. On the basis of the evaluation result of the temperature control and roughness of the newly constructed road at the field experiment site, it is desired to evaluate and identify the most economic modified asphalt mixtures by long-term performance evaluation and LCC(Life Cycle Cost) analysis in order to apply the test result to the design of new road construction in the future.

• Journal of Engineering Education Research
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• v.12 no.2
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• pp.24-35
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• 2009

This study was conducted to establish a principle on the fields of National Technical Qualification(NTQ), and aimed at developing criteria on requirements of the qualification that will be managed as the national technical qualification. In order to achieve the objective of the study, we examined the directions of setting the Jurisdiction of national technical qualification through role assignment between the state and private sectors. Also, we reviewed related documents, conducted Delphi survey, consulted the expert group and had an interview session for this study. There are five criteria of the jurisdiction of NTQ presented as follows. First is the field which disturbs social orders or has possibility of harming the good public morals; second, the field that requires high standards of ethics or is directly linked to life, health and safety of the public; third, the field which requires national attention for training of manpower as it is an area that is difficult for private sector to approach or it requires national management; fourth, the field which requires repair or maintenance of resources of traditional culture but is difficult for the private sector to have an access to and fifth, the field where it needs to protect the interest of the nation in the inter-nation relationships. The concrete and detailed standard on the five criteria is also presented in the study.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.71-76
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• 2012

Biofouling by marine organisms such as algae and barnacles causes lots of significant problems in marine systems such as a rise of the maintenance-repair cost for the ship and the marine structures. In this work, a fluoropolymer, perfluoropolyether (PFPE), was applied as an anti-biofouling coating material that prevents the adhesion of marine organisms and facilitates the removal of them. Water contact angles of various surfaces were tested to examine the hydrophobicity of the PFPE-modified surface. The PFPE-modified surface showed the water contact angle of $64.5^{\circ}$ which is a remarkable rise from $46.7^{\circ}$ of amine-treated surface. When the substrate was treated with PFPE, the adhesion on the of the barnacle and other marine organisms were repressed around 15% by the enhanced hydrophobicity. In addition, the removal the of the adhered marine organisms were better comparing to that of the surface prepared by PDMS. Surfaces of the substrate treated by PFPE were characterized through physical and chemical methods to analyze the biofouling results. Degree of biomolecular adhesion to the substrate was quantified by the measurement the fluorescence intensity of marine organisms dyed with green fluorescence. PFPE is expected to be applicable not only to anti-biofouling systems but also to medical devices where the prevention of protein adhesion is required.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.2
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• pp.193-213
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• 2016

This study has two goals. The First is to develop and apply a step-by-step program and the degree to which students' mathematical skills. The second is to analyze mathematical attitude change around the first grade students was done. The program for learning complement number is composed of series of 5 steps and 11 classes. Play for learning complement number, taking into account the difficulty of the learning steps 1-5 are organized. First step is composed of the classes which fragmented pieces of shapes to complete the entire geometry with fun activities for the entire part of the concept of learning and it maintenance concepts and can naturally learn by associating step. In second step, tools to take advantage of the real world and collecting the conservative concept. 3rd steps is to repair the mathematical concept of the parish in the learning stage of expansion. 4th step is halrigalri, number cards, making ten games etc. 5th step is to verify the concept of complement number and number operation ability. The concept of complement number through fun activities can improve students' mathematical skills, and mathematical attitude change. Early in the program, students use the finger to throw acid in the process. Simple addition and subtraction calculations may take a long time and error, but more and more we progress through the program using the fingers is eliminated and a more complex form calculations was not difficult to act out.

• Science of Emotion and Sensibility
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• v.20 no.1
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• pp.3-16
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• 2017

With the development and proliferation of three-dimensional(3D) printers, consumers in modern society can now print products of what they want three-dimensionally at home. However, consumers themselves would have to produce digital design maps that are compatible with 3D printers and to set up the optimum printing quality and temperature, as well as to pay for maintenance and repair of 3D printers and to respond to any possible lawsuits related to intellectual property right about designs in order to make possible consumer-tailored manufacturing through 3D printing. However, in reality, since it is very difficult for consumers to respond to these issues, it is necessary to develop services that perform 3D printing on behalf of consumers in the desired direction. Motivated by this objective, this study investigated user experiences on Shapeways(www.shapeways.com), which is a global online 3D printing product and sales companies, from many viewpoints in order to obtain insight into 3D printing services and modes which were preferred by consumers. The study result showed that quantitative evaluations on usability, search process, price adequacy, re-visit intention, diversity of design, and satisfaction of design was scored low overall. Furthermore, this study acquired insight about consumer-tailored 3D printing services through constructive suggestions on multi-language support, openness of manufacturing process, simultaneous operation of online and offline sites, design-oriented consumer-tailored manufacturing service, services that ensure delivery safety and product durability, and surface finishing services. This study is expected to provide a wide range of opinions not only on 3D printing service platform development but also on related industry and research.

• Journal of Korea Port Economic Association
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• v.27 no.3
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• pp.65-90
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• 2011

Private stevedoring companies are leasing and operating the container terminals of the Busan Port. The total amount of lease fees private stevedoring companies paid in 2010 reached 161 billion wons, an approximately 66 percent of the total revenue of the Busan Port Authority(BPA). In other words, lease fees are the most important revenue source for BPA. However, the lease fee assessment system of Busan container terminals goes against the principle of equity due to different assessment methods and criteria adopted by each container terminal. Therefore, the purpose of the study is to analyze the systematic problems of the lease fee assessment system that is used at Busan container terminals, and propose a new standardized scheme with a case study on the new system. In order to standardize the assessment system, the assessment methods need to be simplified by using the Discounted Cash Flow(DCF) method. In addition, the assessment criteria such as assessment duration, discount rates, price indexes, estimated container throughputs, sales unit price per TEU, operation costs, including labor costs, need to be standardized as well. The new standardized assessment system can be applied to estimate lease fees for new terminals. However, for existing terminals to run the new system, factors such as assessment duration, discount rates, price indexes, estimated container throughputs, investment and re-investment costs, and maintenance & repair costs of the new system should be changed slightly.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.110-118
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• 2003

Spacer dampers maintain the constant gaps between each conductor in a bundle conductor-transmission line, and are installed at proper intervals to keep a line from all sorts of damages derived from the vibration energy caused by mechanical or electrical external factors. It is most important to embody a technology which considers difficulties of maintenance and repair, and has optimum elements in order to prevent accidents such as destruction by fire or the snapping of a wire by the effect of vibration phenomenon coming from transmission lint In the resent thesis, therefore, the analysis of vibratory characteristics of spacer damper is set up by analytical methods such as the analysis of conductor motion's governing equation, the equation of spacer damper's motion, spacer damper-fastened wire's motion in a span and the numerical analysis of finite difference method. Furthermore, the installation distance between spacer dampers was scrutinized by simulations of various vibration phenomena which change at any time as actual conditions do, and hereafter difference method. Furthermore, the installation distance between spacer dampers was scrutinized by simulations of various vibration phenomena which change at any time as actual conditions do, and hereafter we will be able to analyze all kinds of vibration phenomena coming from a boltless spacer damper with 6 bundle conductor for 765kV transmission line based on new analytical methods.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.1
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• pp.81-91
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• 2012

The purpose of this study was to analyze judicial precedents related on landscape construction defects(JPLCD) and suggested the improvement plan for dealing with it. The results are as the following: 1. Landscape construction defects litigations have been increased so far since 2000 and the duration of original trial was approximately 603 days, while appeal trials took up to 550 days. Therefore, the analysis revealed that settlement of disputes were lengthy and wasteful to consumers and constructors. 2. Judgement's cost accepted by the judge was only 53.6% of appraisal's cost appraised by appraiser, therefore it revealed appraiser overestimated the repair cost of landscape construction defects. 3. According to work classification categorized by Landscape Construction Standard Specification(2008) of the Korean Institute of Landscape Architecture, landscape planting amounted to 75% of JPLCD and plaintiff(consumers)'s prevailing rate of it reached 77% to be a serious burden to constructors. 4. According to JPLCD categorized by the type of dispute, defects caused by consumer's negligence for maintenance amounted to 29% and defendant(constructors)'s prevailing rate of it reached 64% to be the main responsibility of consumers. Further study will be required to make the judge standard of landscape construction defects through legal and technical research.