• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.181-192
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• 2022

Active vibration control system(AVCS) for helicopter enables to control the vibration generated from the main rotor and has the superb vibration reduction performance with low weight compared passive vibration reduction device. In this paper, FxLMS algorithm-based vibration control software of the light civil helicopter tansmits the control command calculated using the signals of the tachometer and accelerometers to the circular force generator(CFG) is developed and verified. According to the RTCA DO-178C/DO-331, the vibration control software is developed through the model based design technique, and real-time operation performance is evaluated in PILS(processor in-the loop simulation) and HILS(hardware in-the loop simulation) environments. In particular, the reliability of the software is improved through the LDRA-based verification coverage in the PIL environments. In order to AVCS to light civil helicopter(LCH), the dynamic response characteristic model is obtained through the ground/flight tests. AVCS configuration which exhibits the optimal performance is determined using system optimization analysis and flight test and obtain STC certification.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.6
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• pp.645-654
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• 2021

In this paper, we proposed a protocol to convert 2W telephone analog signals to Ethernet data in a private PSTN 2W tactical voice system. There are several kinds of operational problems in the tactical telephone network where 2W telephone copper lines are installed hundreds of meters away from the PBX in a headquarter site. The reason is that it is difficult to install and maintain the 2W telephone copper cable in severe operational fields and to meet safety and stability operational requirements of the telephone line under lighting and electromagnetic environments. In order to solve these challenging demands, we proposed an efficient method that the 2W analog interface signals between a private PBX system and a 2W telephone is converted to Ethernet messages using the optical Ethernet data communication network already deployed in the tactical weapon system. Thus, it is not necessary to install an additional optic cable for the ethernet telephone line and to maintain the private PSTN 2W telephone network. Also it provides safe and secure telecommunication operation under lightning and electromagnetic environments. This paper presents the conversion protocol from 2W telephone signals over Ethernet interface between PBX systems and 2W telephones, the mutual exchange protocol of ethernet messages between two converters, and the rule to process analog signal interface. Finally, we demonstrate that the proposed technique can provide a feasible solution in the tactical weapon system by analyzing its performance and experimental results such as the bandwidth of 2W telephone ethernet network and the transmission latency of voice signal, and the stability of optic ethernet voice network along with the ethernet data network.

• Journal of Internet of Things and Convergence
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• v.8 no.5
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• pp.85-91
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• 2022

In the IOT social environment, which emphasizes the convergence of science and technology and emotion, this study aims to explore the experience and meaning of the experience while participating in the design convergence class based on the operation of the Learning community of Chinese graduate students majoring in design. To this end, an implementation study was conducted by visualizing various research problems using a design-based inquiry method for 12 graduate students attending T University. The design-oriented convergence class was conducted in a small group with content that was deepened into a visual strategy by the expression technique given by the external environment and the learner's own inner motivation. In order to express the perspective and intention of the research problem in the research, the convergence design research expressed using various visual strategies such as metaphorical use and analysis of visual data in the research process and sensory approach to the research problem was presented in a form that expresses the creative thinking process. As a way of exploration, the teaching method of presenting results based on various experiences suggests changes in new teaching formats, practical knowledge sharing by instructors, and community participation by learning participants.

• Journal of the Korean Orthopaedic Association
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• v.56 no.1
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• pp.14-25
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• 2021

Several factors need to be considered for a successful anterior cruciate ligament (ACL) reconstruction, such as preoperative planning, operation technique, and postoperative rehabilitation. Graft choice, fixation, preparation method, maturation, incorporation to host bone, and graft tension should also be considered to achieve a good outcome after an ACL reconstruction. Factors to consider when selecting a graft are the graft strength, graft fixation, fixation site healing, and donor site morbidity, as well as the effects of initial strength, size, surface area, and origin of the graft on its potential for weakening during healing. There are two types of graft for an ACL reconstruction, autograft or allograft. Several autografts have been introduced, including the bone-patellar tendon-bone, hamstring tendon, and quadriceps tendon-bone. On the other hand, each has its advantages and disadvantages. The recent increased use of allografts for an ACL reconstruction is the lack of donor site morbidity, decreased surgical time, diminished postoperative pain, and good availability of source. Despite this, there are no reports suggesting that an allograft may have a better long-term outcome than an autograft. Allografts have inherent disadvantages, including a longer and less complete course of incorporation, remodeling, biomechanically inferiority to autograft, the potential risk of an immunogenic reaction and disease transmission. Higher long-term failure rates and poorer graft maturation scores were reported for allografts compared to autografts. An autograft in an ACL reconstruction should remain the gold standard, although the allograft is a reasonable alternative. If adequate length and diameter of autograft can be obtained for an ACL reconstruction, an autograft with adequate graft fixation and postoperative rehabilitation should be chosen instead of an allograft to achieve better results.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.11
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• pp.297-304
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• 2021

Commercial obfuscation tools (protectors) aim to create difficulties in analyzing the operation process of software by applying obfuscation techniques and Anti-reversing techniques that delay and interrupt the analysis of programs in software reverse engineering process. In particular, in case of virtualization detection and anti-debugging functions, the analysis tool exits the normal execution flow and terminates the program. In this paper, we analyze Anti-reversing techniques of executables with Debugger Detection and Viralization Tools Detection options through VMProtect 3.5.0, one of the commercial obfuscation tools (protector), and address bypass methods using Pin. In addition, we predicted the location of the applied obfuscation technique by finding out a specific program termination routine through API analysis since there is a problem that the program is terminated by the Anti-VM technology and the Anti-DBI technology and drew up the algorithm flowchart for bypassing the Anti-reversing techniques. Considering compatibility problems and changes in techniques from differences in versions of the software used in experiment, it was confirmed that the bypass was successful by writing the pin automation bypass code in the latest version of the software (VMProtect, Windows, Pin) and conducting the experiment. By improving the proposed analysis method, it is possible to analyze the Anti-reversing method of the obfuscation tool for which the method is not presented so far and find a bypass method.

• Journal of the Korean Society for Library and Information Science
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• v.56 no.2
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• pp.133-155
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• 2022

The purpose of this study was to develop the indicatives for the analysis of the effects of Gyeonggi-do Book Sharing Project on pre-schoolers of supporter' reading care and thereby, suggest some data useful to the establishment of a reading culture promotion policy in Gyeonggi-do. Preceding studies and cases were reviewed to analyze the effects of the book-sharing project on pre-schoolers of supporter' reading care and thereby, develop some measurement indicatives, and thus, the indicatives were verified by professionals using the Delphi technique. Then, supporter of 3~5 year-old pre-schoolers were sampled from 7 cities and counties in Gyeonggi-do (Pocheon-si, Yangpyeong-gun, Yeoju-si, Dongducheon-si, Gapyeong-gun, Yeoncheon-gun and Yangju-si) to be divided into control and test groups and thereby, their reading care effect indicatives were compared before and after the test. The theoretical background is theory of family literacy, emergent literacy and parenting efficacy. As a result of developing the indicatives for analysis of pre-schoolers of supporter's reading care effects and comparing them for the sample pre-schoolers of supporter, before and after the test, the book-sharing project was found effective in improving reading care. The most difficult problem in pre-schoolers' earlier reading education involves acquisition of reading habit. So, it is deemed necessary to operate a regular book sharing project involving public organization and homes. As a result of developing the indicatives and analyzing the effects of the book-sharing project, it was confirmed that the project would serve to improve pre-schoolers of support's reading care and therefore, this study seems to provide some ground for the operation of a sustainable book-sharing project to narrow the education divide and promote a book reading culture in Gyeonggi-do.

• Journal of Navigation and Port Research
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• v.46 no.4
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• pp.367-374
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• 2022

The purpose of this study was to propose a deep learning algorithm that applies to the fault diagnosis of fuel pumps and purifiers of autonomous ships. A deep learning algorithm reflecting the time dependence of the measured signal was configured, and the failure pattern was trained using the vibration signal, measured in the equipment's regular operation and failure state. Considering the sequential time-dependence of deterioration implied in the vibration signal, this study adopts Conv1D with sliding window computation for fault detection. The time dependence was also reflected, by transferring the measured signal from two-dimensional to three-dimensional. Additionally, the optimal values of the hyper-parameters of the Conv1D model were determined, using the grid search technique. Finally, the results show that the proposed data preprocessing method as well as the Conv1D model, can reflect the sequential dependency between the fault and its effect on the measured signal, and appropriately perform anomaly as well as failure detection, of the equipment chosen for application.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.62-69
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• 2022

EHA (Electro-Hydrostatic Actuator) is more energy efficiency than a centralized hydraulic system. In particular, the EHA used for aircraft has a redundant design in preparation for failure scenario. Also, due to the aircraft's internal space limitation, the actuator's length must be optimized. Therefore, a series configuration of double rod and single rod cylinder is advantageous. However, due to the asymmetry of the cross-sectional area of the piston, the force fighting phenomenon between the two cylinder areas occurs during redundant operation with a general control system. In this paper, the force fighting phenomenon of redundant EHA was simulated. A controller with load compensation and a force control-based position controller as a method to suppress its stimulation

• Journal of Service Research and Studies
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• v.10 no.4
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• pp.101-125
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• 2020

This study was conducted to derive a management technology model based on the new management framework established in previous studies. The management technology sector, which occupies most of the existing business administration, is defined as a technical division in new management. In this study, the theory of management technology based on the service philosophy of the service economy era was presented. The structure of new business, which is the basis of new management technology, is presented first, the service philosophy of the service economy era where management is performed, and then the management technology model based on service philosophy is presented. The management technology model was derived on the basis of immutable axioms. After presenting new management axioms based on common human ideology and nature and human nature, a management technology model was presented based on axioms. On the basis of the axioms, a new dialectical development model was developed as a model for the dialectical development that maintains a tight balance and a fierce interaction between two opposing parties based on the structure and operation model of service philosophy. In addition to the overall organizational management model, a management function model and a management expansion model were presented. Each detailed technique is presented as a model for dialectical development of opposing confrontations. Management technology is a dynamic technology that is constantly changing, and is an overall technology that takes into account various situations and viewpoints. This study has significance as a basic study to overcome the limitations of the existing static management technology and develop dynamic management technology. Future research requires empirical analytical studies on new management technology models.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.2
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• pp.77-82
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• 2023

The Ministry of Agriculture, Food and Rural Affairs established the FarmMap, an digital map of agricultural land. In this study, using deep learning, we suggest the application of farm map reading to farmland such as paddy fields, fields, ginseng, fruit trees, facilities, and uncultivated land. The farm map is used as spatial information for planting status and drone operation by digitizing agricultural land in the real world using aerial and satellite images. A reading manual has been prepared and updated every year by demarcating the boundaries of agricultural land and reading the attributes. Human reading of agricultural land differs depending on reading ability and experience, and reading errors are difficult to verify in reality because of budget limitations. The farmmap has location information and class information of the corresponding object in the image of 5 types of farmland properties, so the suitable AI technique was tested with ResNet50, an instance segmentation model. The results of attribute reading of agricultural land using deep learning and attribute reading by humans were compared. If technology is developed by focusing on attribute reading that shows different results in the future, it is expected that it will play a big role in reducing attribute errors and improving the accuracy of digital map of agricultural land.