• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.44-51
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• 2023

Nitrogen fertilizer is an essential macronutrient that requires repeated input for crop cultivation. Excessive use of nitrogen fertilizers can adversely affect the environment by discharging NH₃, NO, and N₂O into the air and leaching into surrounding water systems through rainfall runoff. Therefore, it is necessary to develop a technology that reduces the amount of nitrogen fertilizer used without compromising crop yields. Fertilizer deep placement could be a technology employed to increase the efficiency of nitrogen fertilizer use. In this study, a deep fertilization device that can be coupled to a tractor and used to inject fertilizer into the soil was developed. The deep fertilization device consisted of a tractor attachment part, fertilizer amount control and supply part, and an underground fertilizer input part. The fertilization depth was designed to be adjustable from the soil surface down to a depth of 40 cm in the soil. This device injected fertilizer at a speed of 2,000 m²/hr to a depth of 25 to 30 cm through an underground fertilizer injection pipe while being attached to and towed by a 62-horsepower agricultural tractor. Furthermore, it had no difficulty in employing various fertilizers currently utilized in agricultural fields, and it operated well. It could also perform fertilization and plowing work, thereby further simplifying agricultural labor. In this study, a newly developed device was used to investigate the effects of deep fertilizer placement (FDP) compared to those with urea surface broadcasting, in terms of rice and soybean grain yields. FDP increased the number of rice grains, resulting in an average improvement of 9% in rice yields across three regions. It also increased the number of soybean pods, resulting in an average increase of 23% in soybean yields across the three regions. The results of this study suggest that the newly developed deep fertilization device can efficiently and rapidly inject fertilizer into the soil at depths of 25 to 30 cm. This fertilizer deep placement strategy will be an effective fertilizer application method used to increase rice and soybean yields, in addition to reducing nitrogen fertilizer use, under conventional rice and soybean cultivation conditions.

• Journal of Korean Elementary Science Education
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• v.42 no.1
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• pp.178-193
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• 2023

The aim of this study was to investigate differences in the achievement standards from the 2015 to the 2022 revised national science curriculum and to present the implications for science teaching under the revised curriculum. Achievement standards relevant to primary science education were therefore extracted from the national curriculum documents; conceptual domains in the two curricula were analyzed for differences; various kinds of centrality were computed; and the Louvain algorithm was used to identify clusters. These methods revealed that, in the revised compared with the preceding curriculum, the total number of nodes and links had increased, while the number of achievement standards had decreased by 10 percent. In the revised curriculum, keywords relevant to procedural skills and behavior received more emphasis and were connected to collaborative learning and digital literacy. Observation, survey, and explanation remained important, but varied in application across the fields of science. Clustering revealed that the number of categories in each field of science remained mostly unchanged in the revised compared with the previous curriculum, but that each category highlighted different skills or behaviors. Based on those findings, some implications for science instruction in the classroom are discussed.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.93-100
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• 2006

The lateral soil movement in soft grounds undergoing improvement with application of vertical drains is analyzed on the basis of monitoring data at three fields, in which fifty six monitoring sites are located. Based on the investigations, the criterions are suggested to predict the lateral soil movement. In order to predict the lateral soil movement in the improved soft grounds by using the dimensionless parameter R suggested by Marche & Chapuis (1974), it is desirable that the maximum lateral displacement in the soft ground below the toe of embankment should be applied to calculate R instead of the lateral displacement at the toe of embankment. The lateral soil movement may increase rapidly, if the safety factor of slope is less than 1.4 in case of high ratio of H/B (Thickness of soft ground/Embankment width) such as 1.15 or is less than 1.2 in case of low ratio of H/B such as 0.05. Also, the graph suggested by Tschebotarioff (1973), which illustrates the relationship between the maximum height of embankments and the undrained shear strength of soft grounds, can be applied to the evaluation for the possibility of the lateral soil movement due to embankments on soft grounds.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.15-24
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• 2006

The evaluation of shear modulus is very important in various fields of civil engineering. Non-destructive seismic methods can be used to determine shear wave velocity ($V_s$) profile. Non-destructive seismic methods geneally consist of three steps: field testing, evaluation of dispersion curve, and determination of Vs profile by inversion process. Non-destructive seismic methods can be divided into two categories according to the number of receivers used for data reduction: two-channel tests and multi-channel tests. Two channel tests use apparent velocity dispersion curve and multi-channel tests use mode dispersion curves. Multi-channel tests using mode dispersion curve can reduce calculation time to determine soil profile and uncertainties in inversion process. So far, only multi-channel tests can determine mode dispersion curves but multi-channel test needs many receivers to determine reasonable mode dispersion curves. In this paper, HWAW (Harmonic Wavelet Analysis of Wave) method is applied to determine mode dispersion curves. HWAW method uses short test setup which consists of two receivers with a spacing of 1 to 3 m. Through numerical simulations and field application, it is shown that HWAW can determine resonable mode disperson curves.

• Conservation Science in Museum
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• v.29
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• pp.99-110
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• 2023

The stone fragments that are missing from the stone cultural heritage have limited use beyond being directly fitted to identify their original position, as they are relatively heavy and bulky, and there is the further risk of secondary physical damage during manual work. Therefore, in this study, morphological relationships between the missing parts and the stone fragments were identified through digital restoration, and a three-dimensional (3D) printed replica was created for use at the exhibition for Stone Buddhas in Four Directions in Hwajeon-ri, Yesan, where 72 stone fragments had been excavated together. First, for the digital restoration, stone fragments of similar shapes were selected after the coordinates of the 3D scanning model were aligned in virtual space. In addition, the stone fragments were printed using a 3D printer to check whether they were physically related to the missing parts. Thus, the original positions of a total of nine stone fragments were identified. To utilize these research results in the exhibition, a 1:1 replica of the Stone Buddhas in Four Directions was produced using 3D printing technology, and the nine stone fragments were also restored to their original positions. The digital technology used in this study is of great importance in that it not only made up for the limitations of the direct manual method but also suggested the possibility of expanding its application to the fields of documentation, restoration, and replication of similar cultural heritage.

• Journal of Convergence for Information Technology
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• v.12 no.3
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• pp.286-293
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• 2022

Recently, the importance of elemental technologies constituting smart factories is increasing due to the 4th Industrial Revolution, and simulation is widely used as a tool to learn these technologies. In particular, PID control is an automatic control technique used in various fields, and most of them analyze mathematical models in certain situations or research on application development with built-in controllers. In actual educational environment requires PID simulator training as well as PID control principles. In this paper, we propose a model that enables education and practice of various PID controls through 3D simulation. The proposed model implemented virtual balls and Fan and implemented PID control by configuring a system so that the force can be lifted by the air pressure generated in the Fan. At this time, the height of the ball was expressed in a graph according to each gain value of the PID controller and then compared with the actual system, and through this, satisfactory results sufficiently applicable to the actual class were confirmed. Through the proposed model, it is expected that the rapidly increasing elemental technology of smart factories can be used in various ways in a remote classroom environment.

• Journal of the Korean Society of Floral Art and Design
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• no.41
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• pp.93-114
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• 2019

The purpose of this study is to analyze the characteristics and problems of the content of flower design education videos on YouTube and to search for improvement direction. The subjects of analysis were 129 pieces of videos uploaded in the last one year including 'craftman floral design' as a search term. The result shows that contents covered were practical lectures, theory lectures, test related tips, job and character introduction, test work, educational guidance and publicity. The production format could be divided into studio lecture, classroom lecture, video feature, interview, Vlog, and television program. The hub-type programming strategy that periodically uploads the videos satisfying the target audiences' interests is mostly applied. The type of lecture covered 'practical skill test' got a good response from the users. Overall, content diversity, interaction between creators and users, and harmonious programming strategies are lacking. In order to improve this, it is necessary for emotional and expressive creators to pioneer differentiated fields and practice based on actual field. The introduction of interactive elements such as games and quizzes and the application of new media technologies such as VR and AR are worth trying. Three strategic types of 'hero', 'hub', and 'how to' should be applied complementary. As the demand for education content related to flower design is expected to expand in the future, it is required to develop content that can be used in various platforms, foster professional creators, and develop associated business models.

• Korea Science and Art Forum
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• v.30
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• pp.453-464
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• 2017

With the development of IT technology, various smart products and services have been spread in our daily life, providing users with convenience and emotional satisfaction. Particularly, input and output technologies, sensor technologies, and intelligent system technologies have offered new opportunities for diverse interaction patterns and new user experiences. This research started from the interest in the idea generation of product designers who need to combine various technological aspects with users' needs. The goal of this research is to propose an interaction design framework which can be used in an idea generation stage. To do so, first, the concept and characteristics of smart products were studied through literature reviews, and the interaction technologies, including input/output modality and context-aware technologies, were also investigated. Then, the frameworks that have been proposed in the deisgn fields were reviewed. This paper finally proposed the interaction design framework and explained its application to the idea generation, using several case studies. The proposed framework consists of four categories: product components, context-awareness elements, information input elements, and feedback output elements. Each of these are divided into several sub-categories, focused on users' needs. Sub-categories includes some elements of interaction, and each of the elements is explained with an existing smart product/system. The paper also describes how the proposed framework would be used in the idea generation process, using some design ideation examples. In the future study, more various concept ideas will be proposed through some elaborated case studies, and the framework is expected to be verified in terms of its possibility as an idea generation tool.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.34 no.2
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• pp.233-249
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• 2023

This study aimed to understand the application and types of Creative Commons Licenses (CCL) in Korean journals and to increase understanding of the state of open access in South Korea. The study collected and analyzed CCL-related information from the websites of 2,097 KCI journals and compared the findings with DOAJ journals and previous research. The results of the study are summarized as follows. Firstly, 18% (377 journals) of the KCI journals adopted CCL, and among them, approximately 90% (337 journals) were in the field of STEM. There were few academic journals applying CCL in humanities and social sciences fields. Secondly, the types of CCL adopted by KCI journals were NC licenses (90%), with CC BY-NC (85%) being the most common. This is a significant difference from DOAJ journals, where 52% of academic journals applied CC BY or CC BY-SA. However, fewer journals applied licenses of the ND licenses than DOAJ journals and Spanish journals. Thirdly, 44% (167) of the 377 academic journals that applied CCL were simultaneously for free in public databases and sold for a fee in commercial databases. 33% (125) were publicly available for free in public databases, and 9% (33) were sold in commercial databases.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.135-143
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• 2009

Integrating the Global Positioning System (GPS) and Inertial Navigation System (INS) sensor technologies using the precise GPS Carrier phase measurements is a methodology that has been widely applied in those application fields requiring accurate and reliable positioning and attitude determination; ranging from 'kinematic geodesy', to mobile mapping and imaging, to precise navigation. However, such integrated system may not fulfil the demanding performance requirements when the baseline length between reference and mobil user GPS receiver is grater than a few tens of kilometers. This is because their positioning/attitude determination is still very dependent on the errors of the GPS observations, so-called "baseline dependent errors". This limitation can be remedied by the integration of GPS and INS sensors, using multiple reference stations. Hence, in order to derive the GPS distance dependent errors, this research proposes measurement processing algorithms for multiple reference stations, such as a reference station ambiguity resolution procedure using linear combination techniques, a error estimation based on Kalman filter and a error interpolation. In addition, all the algorithms are evaluated by processing real observations and results are summarized in this paper.