• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.709-717
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• 2016

In this study, the convenience and efficiency of vision-based displacement measurement (VBDM) to estimate the cable tension of cable-stayed bridges and the requirements for its effective application were examined. To demonstrate its convenience and efficiency, it was confirmed that VBDM can be accomplished with a minimum amount of equipment using a commercial camcorder. In this case, it was found that the accuracy of estimation of the natural frequencies is sufficient, even though magnitude errors can occur when conducting high-speed recording at the low resolution afforded by the minimal equipment employed. It was also confirmed that the most important factor in detecting the precise natural frequencies is the use of the appropriate frequency range in the tension estimation using vibration. Based on these results, a study was carried out on the accuracy variation of the estimated tension according to the frame rate of a commercial camcorder. For this purpose, an experiment was performed to estimate the cable tension in a cable-stayed bridge model. Through this experiment, the detectable tensions of cables with various natural frequencies as a function of the frame rate were summarized. As a result, it was shown that the frame rate should be determined based on the natural frequency which is estimated to be located within the appropriate frequency range (approximately 10~75% of theoretical range) considering the aliasing and low-frequency distortion due to excitations.

• Journal of Nutrition and Health
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• v.51 no.1
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• pp.73-86
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• 2018

Purpose: The aim of this study was to design optimized food intake patterns that meet the nutritional recommendations with minimal changes from the current food intake patterns among Korean adults using linear programming. Methods: Data of a one day 24-hour dietary recall from the 2010 ~ 2014 Korea National Health and Nutrition Survey were used to quantify the food items that Korean adults usually consumed. These food items were categorized into seven groups and 24 subgroups. The mean intakes and intake distributions of the food groups and the food subgroups were calculated for eight age (19 ~ 29, 30 ~ 49, 50 ~ 64, and over 65 years old) and gender (male and female) groups. A linear programming model was constructed to minimize the difference between the optimized and mean intakes of the food subgroups while meeting the Dietary Reference Intakes for Koreans (KDRIs) for energy and 13 nutrients, and not exceeding the typical quantities of each food subgroup consumed by the respective age and gender groups. Results: The optimized food intake patterns, which were a set of quantities of 24 food subgroups, were obtained mathematically for eight age and gender groups. Overall, major modifications of current diet were required to increase the intake of vegetables and milk/dairy products and decrease the Kimchi intake. The optimized intake of seasonings, including salt, was calculated to be 0 g for all the age and gender groups. Conclusion: The optimized food intake patterns designed using linear programming in this study lack feasibility because they suggest a seasoning consumption of 0 g. Modification of intake goal for sodium is needed to obtain optimized food intake patterns with improved feasibility.

• Journal of agriculture & life science
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• v.46 no.1
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• pp.195-206
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• 2012

This study is about an analysis of surplus solar energy by important greenhouse types as well as setting temperature different by using Typical Meteorological Year data which was secured in order to provide basic data for designing an optimum thermal storage system to accumulate surplus solar energy generating in greenhouses during the daytime. Depending on the setting temperatures of $15{\sim}19^{\circ}C$ for greenhouse heating during day and night, surplus heat amounts were varied at the rate of about $0.2{\sim}6.9%/4^{\circ}C$ with some variations according to the greenhouse types and regions. On the other hand, the variations of supplemental heat requirements were about $29.7{\sim}50.0%/4^{\circ}C$. Depending on the setting temperatures for greenhouse ventilations(low $25{\sim}29^{\circ}C$ and high $27{\sim}31^{\circ}C$), surplus heat amounts were varied at the rate of about $-9.9{\sim}-35.6%/4^{\circ}C$ in auto-type greenhouse. But in single-type greenhouses, they were about $-5.1{\sim}-13.4%/4^{\circ}C$. There were not significant changes in supplemental heat amounts depending on setting temperatures of ventilation for both greenhouse types and regions.

• Korean Journal of Remote Sensing
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• v.15 no.2
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• pp.147-158
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• 1999

Remote sensing technique has offered better understanding of our environment for the decades by providing useful level of information on the landcover. In many applications using the remotely sensed data, digital image processing methodology has been usefully employed to characterize the features in the data and develop the models. Random field models, especially Markov Random Field (MRF) models exploiting spatial relationships, are successfully utilized in many problems such as texture modeling, region labeling and so on. Usually, remotely sensed imagery are very large in nature and the data increase greatly in the problem requiring temporal data over time period. The time required to process increasing larger images is not linear. In this study, the methodology to reduce the computational cost is investigated in the utilization of the Markov Random Field. For this, multiresolution framework is explored which provides convenient and efficient structures for the transition between the local and global features. The computational requirements for parameter estimation of the MRF model also become excessive as image size increases. A Bayesian approach is investigated as an alternative estimation method to reduce the computational burden in estimation of the parameters of large images.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.525-538
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• 2022

In Korea, safety accidents are continuously occurring due to the aging of underground facilities and lack of systematic management. Moreover, although the underground space is continuously being developed, the current status information is not clearly recorded and managed, so there is a limit to the systematic management of underground facilities. Therefore, this study developed an augmented reality-based system that can effectively maintain and manage underground facilities that are difficult to manage because they are located underground. In order to develop an augmented reality-based underground facility management system, three essential requirements, 'precise localization', 'use of BIM information', and 'ensure usability' were derived and reflected in the system. By utilizing Broadcast-RTK, the positional precision was secured to cm level, and the configuration and attribute information of the BIM was converted into the IFC format to construct a system that could be implemented in augmented reality. It developed an application that can optimize usability. Finally, through simulation, the configuration and attribute information of structures and mechanical systems constituting underground facilities were implemented in augmented reality. In addition, it was confirmed that the accurate and highly consistent augmented reality system works even in harsh environment (near high-rise building).

• Journal of Korea Trade
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• v.25 no.8
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• pp.1-24
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• 2021

Purpose - This study categorizes factors that influence the utilization of preferential tariffs based on the characteristics of rules of origin (RoO) and identifies and analyzes the influence of these characteristics on the utilization of preferential tariffs and the trade performance of companies. Design/methodology - In this study, we categorized factors that have an influence on the utilization of preferential tariffs based on the characteristics of RoO and investigated and tested the influence of these characteristics on the utilization of preferential tariffs and the trade performance of companies. For empirical analysis, we categorized the characteristics of RoO into restrictiveness, complexity, and uncertainty. We then developed a research model and formulated hypotheses based on previous studies, and tested the hypotheses using statistical software-(SPSS 25.0 and AMOS 18.0.) Findings - Previous studies suggested that each characteristic of RoO is determined by unique features of a Regional Trade Agreement (RTA). This study conducted an empirical analysis on the influence of the characteristics of RoO on the utilization of preferential tariffs and trade performance. The results confirmed that, overall, the characteristics of preferential rules of origin (PRoO) are related to and influence Korean companies' utilization of preferential tariffs and trade performance. As for the degree of the influence, the characteristics were in the order of uncertainty> restrictiveness> complexity. Nevertheless, complexity turned out not to have an influence large enough to change a company's decision on the utilization of preferential tariffs. Based on these results, this study identified unique features of PRoO and related problems for Korean companies that want to utilize preferential tariffs and suggested countermeasures for their effective utilization of preferential tariffs in the future. Originality/value - Companies that want to use preferential tariffs in international trade have to satisfy PRoO. The issue of origin can be regarded as an essential part of an RTA and RoO, are a crucial criterion in using preferential tariffs. The rules are requirements to claim benefits of preferential trade agreements and are the primary reasons companies have trouble in utilizing preferential tariffs. In this sense, this study categorized the characteristics of RoO, which are a key part of an RTA, and surveyed working-level professionals in charge of international trade at Korean companies to investigate the relationship between these characteristics and the utilizations of preferential tariffs and trade performance of the companies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.396-402
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• 2021

A cross section in RC flexural members must be designed to satisfy flexural strength and ductility requirements simultaneously. In design provisions, ductile behavior is ensured by a sufficient reinforcement ratio or depth of the neutral axis. If the reinforcement ratio is less than the balanced reinforcement ratio, ductile behavior is secured, and this value is theoretically the maximum reinforcement ratio. But for a cross section with less steel, brittle failure can occur regardless of ductile behavior because of unqualifying a cracking moment. Recently, designs with a minimum steel ratio have been increasing along with the use of high-strength material, so in design provisions, a minimum amount of reinforcement is suggested. In the KCI(2012) standard, a minimum amount of reinforcement was suggested in terms of strength of steel and concrete. But in the revised KCI(2017) standard, a minimum amount of reinforcement was suggested by a relationship between the design flexural strength and cracking moment indirectly. This code can reflect the effect of cover thickness, but a material model must be defined. Therefore, the minimum amount of reinforcement in KCI(2012) and KCI(2017) was examined, and a rational review method was studied by parametric analysis.

• The Korean Journal of Archival Studies
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• no.15
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• pp.141-183
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• 2007

It is not an overstatement that nowadays electronic mails are communicated more frequently as well as conveniently than phones and facsimiles, not only in routine life hot also in business transactions. Also, it is evident that emails will be used more and more as a communication method between internal and external organizations. If the information transferred and received via emails takes a role of business records, it is no wonder that emails should be uniformly managed as public records. Currently, however, specific policies or guidelines for the management of email records are not available, nor do most of public employees realize that emails are the actual records of the organization. In fact, the three research methods have been used for this study in the purpose of the establishment of email records management scheme. First of all, bibliographic research has been conducted in an effort to describes the definition and types of email records indicated in the guidelines of each nation, as well as the differences from the transitory email messages. Secondly, email management guidelines and policies of public institutions of England, The United States, Australia, and Canada, so-called the advanced countries of the records management, have been analyzed to examine the advanced examples of email management. In order to manage email records effectively, the functional requirements - capture, classification, storage, access, tracking, disposition, and role and responsibility were categorized in this thesis, based on the ISO 15489. As the designs of these foreign guidelines vary one another, common factors of them were extracted to be included in the realm of the seven stages. Lastly, this thesis has analyzed characteristics of the email system within the Electronic Document Management System of existing administrative institutions. Also, it has examined the overall environment of the email records management of public institutions and sought out its improvement. In essence, focused on the crucial factors on email management drawn out from the email management guidelines of foreign nations and the analysis of the policies, this thesis proposes an email records management scheme for Korean public intuitions, as well as an email management model suitable for forthcoming e-government era.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.23-31
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• 2019

The design requirements of modern satellites vary depending on the purpose of operation. Like conventional medium and large-scale satellites, small satellites which operate on low orbit may also serve military purposes. As a result, there is increased demand for high-resolution photos and videos and multi-target observation becomes important. The most important design parameter for multi-target observation is the satellites' maneuverability. For increased maneuverability, the miniaturization is required to increase the stiffness of the satellite as this decreases the mass moment of inertia of the satellite. In the case of a solar panel having relatively low stiffness compared to the satellites' body, vibrations are generated when the attitude maneuver is performed, which greatly influences the image acquisition. For verification of such vibrational characteristics, the satellites is modeled as a reduced model, and experimental zig for simulating attitude maneuver is introduced. A rigidity simulator for simulating the stiffness of the satellite is also proposed. Additionally, the objective of the experimental method is to simulate the maneuvering angle of the satellite based on the winding length of the wire using a step motor, and to experimentally verify the vibration characteristics of the satellite body and the solar panel generated during the maneuvering test.

• Journal of Bio-Environment Control
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• v.28 no.1
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• pp.16-27
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• 2019

Using virtual reality technology, users can learn and experience many interactions in virtual space like the actual physical space. This study was conducted to develop air flow simulator that allows farmers and consultants to consult air flow through VR devices by creating a greenhouse or pigpen model. It can help educate farmers about the importance of ventilation effects for agricultural facilities. We proposed CFD visualization system by building a virtual reality environment and constructing database of CFD and structure of agricultural facilities. After consultants can set up situations according to environmental conditions, the users experience the visualized air flow of agricultural facility according to the ventilation effects. Also it can provide a quantified environmental distribution in the agricultural facility. Currently, the CFD data in agricultural facilities are established during winter and summer. In order to experience various environmental conditions in the developed system, The experts need to run CFD data under various environmental conditions and register them in the system requirements.