• Korean Journal of Optics and Photonics
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• v.32 no.2
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• pp.49-54
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• 2021

In this paper, we design and construct the equipment to manufacture large-diameter optical fiber end caps, which are the core parts of high-power fiber lasers, and we fabricate large-diameter optical fiber end caps using the home-made equipment. This equipment consists of a CO2 laser as a fusion-splice heat source, a precision stage assembly for transferring the position of a large-diameter optical fiber and an end cap, and a vision system used for alignment when the fusion splice is interlocked with the stage assembly. The output of the laser source is interlocked with the stage assembly to control the output, and the equipment is manufactured to align the polarization axis of the large-diameter polarization-maintaining optical fiber with the vision system. Optical fiber end caps were manufactured by laser fusion splicing of a large-diameter polarization-maintaining optical fiber with a clad diameter of 400 ㎛ and an end cap of 10×5×2 ㎣ (W×D×H) using home-made equipment. Signal-light insertion loss, polarization extinction ratio, and beam quality M2 of the fabricated large-diameter optical fiber end caps were measured to be 0.6%, 16.7 dB, and 1.21, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.688-694
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• 2018

The mixture ratio of two-component liquid silicone is important for the inherent physical characteristics of the finished product. Therefore, it is necessary to uniformly control the ratio of the main material and the sub-material. In this paper, a mixing-ratio control system was designed, which consists of a digital flow meter and a flow control system to measure the flow rate of the raw materials and a pumping system to maintain constant pressure and transfer of the raw materials. In addition, a program was developed to control the organic interlocking and mixing ratio. For the verification of the developed system, we compared the actual weight of raw material with the value measured by the flow meter during pumping, and we measured the physical properties of the mixed material by making test samples with and without the application of the mixing-ratio improvement algorithm. The measured value was close to the reference value with a hardness range of 46-47 and tensile strength of 9.3-9.5 MPa. These results show that the mixing ratio of the liquid silicone is controlled within an error range of ${\pm}0.5%$.

• Clean Technology
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• v.25 no.2
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• pp.161-167
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• 2019

Several types of reactors have been used during the past decade to perform fast pyrolysis of biomass. Among the developed fast pyrolysis reactors, fluidized bed reactors have been widely used in the fast pyrolysis process. In recent years, experimental studies have been conducted on the characteristics of biomass fast pyrolysis in a spouted bed reactor. The fluidization characteristics of a spouted bed reactor are influenced by particle properties, fluid jet velocity, and the structure of the core and annulus. The geometry of the spouted bed reactor is the main factor determining the structure of the core and annulus. Accordingly, to optimize the design of a spouted bed reactor, it is necessary to study the pyrolysis characteristics of biomass. However, no detailed investigations have been made of the fast pyrolysis characteristics of biomass in accordance with the geometry of the spouted bed reactor. In this study, fast pyrolysis experiments using Jatropha curcas L. seed shell cake were conducted in a conical spouted bed reactor to study the effects of reaction temperature and reactor cone angle on the product yield and pyrolysis oil quality. The highest energy yield of pyrolysis oil obtained was 63.9% with a reaction temperature of $450^{\circ}C$ and reactor cone angle of $44^{\circ}$. The results showed that the reaction temperature and reactor cone angle affected the quality of the pyrolysis oil.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.757-763
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• 2018

It is very difficult to achieve sufficient data rate and required quality of service due to the time-varying nature of the radio channel and various jammers such as path loss, delay, Doppler, shadowing and interference. Especially, the propagation path between the transmitting antenna and the tracking antenna mounted on the fuselage during the test and evaluation of the projectile system considered in this paper is based on the rapid movement of the projectile, the interference due to multipath fading due to the terrain, The propagation path may be blocked. In order to effectively improve the multipath fading occurring in the wireless communication system, a diversity combiner technique is required. In this paper, to derive the design and improvement schemes for the space diversity combiner technique among the diversity combiner schemes, the BER performance of maximum ratio combining (MRC) and selection combining (SC) In an adaptive SC / MRC diversity combiner that operates with MRC when it is lower than the specified threshold criterion when comparing the SNR between two signals received from the channel and operates with SC at high and combines the two received signals The BER performance of the system was compared and analyzed.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.381-387
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• 2019

Since the development of NCS-based curriculum in field of game education is not well studied, so we carried out research on the curriculum development of game contents department of Kimpo University as the first study to link game education and NCS. In order to develop the NCS-based game education course, we analyzed the game industry environment and conducted a demand survey on the game industry officials to derive the vocational basic subjects required for game contents creation. In addition, we analyzed the types of manpower training by using on-site experts (SME). SME also designed the NCS curriculum by matching the manpower type comparing with NCS classification and capacity unit, analyzing the usefulness of each Capacity unit, and finally, by arranging each NCS and non-NCS subjects by semester. This research is meaningful as the first study linking NCS and game content creation, and it will be a reference for other education institutions planning game education course based on NCS. It also can be used as a basic material for researching game education quality management (CQI) as well as improvement methods for future game education courses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.1-8
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• 2019

Steel elevator pit was developed for the purpose of minimizing the excavation, simplifying the construction of the frame and economical efficiency by improving the problems that occurred in the existing reinforced concrete. It is common to apply conventional RC method through excavation to underground structures such as underground floor collector well and elevator pit. In recent years, the use of steel collector well and steel elevator pits to reduce construction costs by minimizing the materials of steel and concrete has been continuously increasing. The steel elevator pit is an underground structure and then the performance of the welding part and the structure system is important. Specimen with only steel plate and concrete without studs could support the load more than 3 times than the specimen with deck only. Therefore, even if there is no stud, the deck (steel plate) rib is formed and the effect of restraining the steel plate and the concrete during the bending action can be expected. However, since sudden fracture in the elevator pit may occur, stud bolt arrangement is necessary for the composite effect of steel plate and concrete. It is expected that the bending strength can be expected to increase by about 15% or more depending with and without stud bolts.

• Journal of the Korean Society for information Management
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• v.36 no.1
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• pp.247-267
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• 2019

There has been low use of local information services that public libraries provide, and most of those services are limited only through in-house reading or checkout. Motivated by these issues, the study has developed a mobile application (app, hereafter) entitled as LibPass (a combination of Library and Pass) to propose new local information services that reflect the information needs of users. Regarding the design of LibPass, contents of LibPass are composed of the characteristics of local resources so that users can easily search for information about local culture and tour resources through mobile app. That is, it aims to provide efficient information services on local resources by providing information on accommodations, outdoor programs, and specialized libraries, as well as introducing tour resources. Above all, the services are provided with a single card issued by the National Library of Korea and is convenient to use anywhere in the country. It not only secures reliability and currency by utilizing various contents developed by public institutions, but also provides functions to facilitate specialized services for the local information of libraries. Based on the previous research, the present study derives the factors of quality evaluation of mobile tour information services; it constructs objects of LibPass application by analyzing existing applications and develops the prototype based on logical entity relationship model. This model can contribute to the increased use of local information services and, promotes the public's positive perception of the libraries through user-friendly applications.

• Smart Media Journal
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• v.8 no.1
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• pp.74-81
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• 2019

Recently, machine learning technology has had a significant impact on society, particularly in the medical, manufacturing, marketing, finance, broadcasting, and agricultural aspects of human lives. In this paper, we study how to apply machine learning techniques to foods, which have the greatest influence on the human survival. In the field of Smart Farm, which integrates the Internet of Things (IoT) technology into agriculture, we focus on optimizing the crop growth environment by monitoring the growth environment in real time. KT Smart Farm Solution 2.0 has adopted machine learning to optimize temperature and humidity in the greenhouse. Most existing smart farm businesses mainly focus on controlling the growth environment and improving productivity. On the other hand, in this study, we are studying how to apply machine learning with respect to harvest time so that we will be able to harvest fruits of the highest quality and ship them at an excellent cost. In order to apply machine learning techniques to the field of smart farms, it is important to acquire abundant voluminous data. Therefore, to apply accurate machine learning technology, it is necessary to continuously collect large data. Therefore, the color, value, internal temperature, and moisture of greenhouse-grown fruits are collected and secured in real time using color, weight, and temperature/humidity sensors. The proposed FPSML provides an architecture that can be used repeatedly for a similar fruit crop. It allows for a more accurate harvest time as massive data is accumulated continuously.

• Food Engineering Progress
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• v.21 no.2
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• pp.132-137
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• 2017

The purpose of this study was to optimize dough properties using response surface methodology (RSM) and to demonstrate the performances of dough prepared under optimized conditions. Dough mixed with yeast, margarine, salt, sugar and wheat flour was prepared by fermentation process. Hardness, cohesiveness and springiness of dough were selected as critical quality attributes. The critical formulations (yeast and water) and process (fermentation time) variables were selected as critical input variables based on preliminary experiment. Box-Behnken design (BBD) was used as RSM. As a result, the quardratic, the squared and the linear model respectively provided the most appropriate fit ($R^2$>90) and had no significant lack of fit (p>0.05) on critical quality attributes (hardness, cohesiveness and springiness). The accurate prediction of dough characteristics was possible from the selected models. It was confirmed by validation that a good correlation was obtained between the actual and predicted values. In conclusion, the methodologies using RSM in this study might be applicable to the optimization of fermented foods containing various wheat flour and yeast.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.969-976
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• 2020

Urban Air Mobility is attracting attention as a future innovation industry around the world, and leading industries are considering the application of composite materials for structural robustness and lightening in the designing and manufacturing new concept eVTOL aircraft. To apply composite materials to the new concept of eVTO aircraft, this paper was analyzed about composite material qualification system of FAA & EASA and institutionalized by Korea Government, including the procedures and methods, the organization to carry out the material verification for domestic conditions. The domestic composite material qualification system will not only make it easier for manufacturers of eVTOL aircraft with a new concept to apply composite materials to domestic aircraft through pre-material qualification, but also reduce the burden of material qualification within the period of type certification. In addition, domestic manufacturers of composite materials with qualified material quality and performance will be easy to enter for domestic aircraft applications and composite material manufacturers with experience in applying to aircraft will have a positive impact on overseas exports. This system will be able to promote the development eVTOL aircraft industry of a new concept and enhance international credibility of made aircraft in Korea.