• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.135-144
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• 2022

This study explores that how the logic of network power in the existing digital content distribution structure works against local media. The limitless citation of local media content, in particular, is becoming more common in order to profit from network traffic while not giving appropriate remuneration for local media content. This study tried to demonstrate how network media dominance alienates local media material by using YouTube network analysis of TV Maile Shinmun. According to the research result, it was found that major news media tends to take profits from the local media interview by not properly indicating the source video, or reporting the core content of the local media interview, making it unnecessary to look for the original video source. Despite the viewpoint that the digital environment presents opportunities for local media, the current network logic would not benefit local media, which calls for the need that the digital content distribution strategy of local media develops a new order such as NFT, one of blockchain-based monetary system.h the help of information technology.

• Journal of Bio-Environment Control
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• v.7 no.1
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• pp.71-77
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• 1998

The root-zone environment is an important factor to the plant growth and it is closely related to the thermal characteristics of the root media. In this study thermal characteristics of root media with ambient environmental conditions were analyzed. The temperatures of nutrient solution as well as inside air of culture bed were measured in Nutrient Film Technique(NFT) and Deep Flow Technique(DFT) systems, and also the temperatures of root media measured in aggregate culture systems , The temperature of nutrient solution of NFT system with as low as 3$\ell$/min of flow rate was 3$^{\circ}C$ higher than that with 5 $\ell$/min of flow rate in the daytime, and the temperature of inside air was 2$^{\circ}C$ higher at night. And the temperature of nutrient solution of DFT system with as low as 0.8 cm of water level was 1-2$^{\circ}C$ higher than that with 1 8 cm in the daytime, and the temperature of inside air was almost same at night. The root-zone temperatures in the perlite and rockwool granulate systems with film mulching were 3$^{\circ}C$ higher than those without film mulching in the daytime. However, the rockwool slab system with film mulching showed the same trend as rockwool granulate system, but relatively higher temperature than any other medium because of the exposure of media surface to the ambient air. Additionally the temperature below the plant was measured 3$^{\circ}C$ lower than that between plants.

• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.168-174
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• 2002

A new circulating hydroponic system was invented for oriental melons grown in the greenhouse. For developing nutrient solution management techniques, we examined the changes of nutrient contents of circulating solution in three different types of new hydroponic systems. The yield and fruit quality of oriental melons in Hydroponics were better than those in soil culture. The substrate culture was appropriate fer hydroponics of oriental melons, and NFT was turned to be the opposite due to the physiological disorder during hot seasons. Yamazaki's melon solution with EC 2.0dS.m$^{[-10]}$ was the most appropriate for oriental melons. The new circulating hydroponic system seemed to be appropriate for oriental melons because of the stable EC, pH and the macro- and micro-element contents. NO$_3$-N, Ca and Mg contents in the circulating solution kept a good balance in all types of hydroponics. However, p content, compared to other types, decreased by the degree of 1 me.L$^{[-10]}$ in perlite medium. K content showed irregular status in perlite but showed the stable status in cocopeat. Generally, microelements, except Mo, showed stable absorption in the substrate culture. However, in NET, most of the elements showed irregular absorption except B and Mn. Microelement absorption, especially Cu, Zn and Mo, decreased during hot seasons.

• Steel and Composite Structures
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• v.21 no.1
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• pp.73-91
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• 2016

The use of box columns has been increased due to the rigidity in rigid orthogonal moment resisting frames. On the other hand, the installation and welding of necessary horizontal continuity plates inside the columns are both labor-consuming and costly tasks. Accordingly, in this paper, a new beam-to-box column connection by trapezoidal external stiffeners and horizontal bar mats is presented to provide seismic parameters. The proposed connection consists of eight external stiffeners in the level of beam flanges and five horizontal bar mats in Concrete Filled Tube (CFT) columns. The new connection effectively alleviates the stress concentration and moves the plastic hinge away from the column face by horizontal external stiffeners. In addition, the result shows that proposed connection has provided the required strength and rigidity of connection, so that the increased strength, 8.08% and rigidity, 3.01% are compared to connection with internal continuity plates, also the results indicate that this connection can offer appropriate ductility and energy dissipation capacity for its potential application in moment resisting frames in seismic region. As a result, the proposed connection can be a good alternative for connection with continuity plates.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.53-57
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• 1993

This study was carried out to investigate the appropriate hydroponic system when cherry tomatoes were grown in summer. The base diameter of the trunk, leaf length, leaf width, and the length of cluster were good in deep flow culture(DFC), and not different between NFT and rockwool culture. The first time of flowering and the fruit coloring per cluster were not different among cultural systems, but the marketable yields were good in DFC. In DFC, ％ dry weight, firmness, the content of organic acid and sugar were low, and the ratio of sugar/organic acid and vitamin C were high. So DFC is recommended for the summer cultivation of cherry tomatoes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.328-330
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• 2022

Currently, the Metaverse is introduced in various fields, and a virtual convergence economy that uses NFTs for content or item transactions is expected to develop into a 'metaverse environment'. The 'metaverse environment' will lead the changes in our society in the future and it will be fused with AI, big data, cloud, IoT, block chain, and next-generation network technology. However, personal information, device information, and behavior information provided by Metaverse users to use the service are subject to major attacks. Therefore, in order to provide a safe environment for users to use and to expand the business base of related companies, building a public-private cooperation system and developing a security guide are the leading tasks. Therefore, in this study, we compare and analyze metaverse features and technologies, and examine possible security threats and countermeasures.

• Convergence Security Journal
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• v.23 no.4
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• pp.3-15
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• 2023

As remote services and remote work become commonplace, the use of the Metaverse has grown. This allows transactions like real estate and finance in virtual Second Life. However, conducting economic activities in the Metaverse presents unique security challenges compared to the physical world and conventional cyberspace. To address these, the paper proposes solutions centered on authentication and privacy. It suggests improving data preprocessing based on Metaverse data's uniqueness and introduces a new authentication service using NFTs while adhering to W3C's DID framework. The system is implemented using Hyperledger Indy blockchain, and its success is confirmed through implementation analysis.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.580-584
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• 2010

The effect of planting densities on the growth of $Sedum$ $samentosum$ (4 collections) was investigated using nutrient film technique (NFT) with Yamazaki' lettuce nutrient solution (1982) from September 5th to October 24th in non-heating plastic film house. At 40 days, the plant height of 4 collections showed the range of 15.0-18.9 cm, and mean plant height was high the order of $10{\times}10$, $2.5{\times}2.5$, and $5{\times}5cm$. The growth of 'Pohang' and 'Wando' collections was better compared to that of 'Gunsan' and 'Wanju' collections. Number of node, stem diameter, and fresh and dry weight per plant were decreased in higher planting density. Despite the lower fresh weight per plant obtained, the fresh yield per $m^2$ was significantly increased in higher planting density. The mean fresh yield was $14.9kg{\cdot}m^{-2}$ in $2.5{\times}2.5cm$, and 'Pohang' collection showed the highest fresh yield ($17.6kg{\cdot}m^{-2}$). The first optimized harvesting time base on plant height was 30-40 days after NFT culture during autumn season. In eating quality, compression force of stem and bitterness of shoot were decreased in higher planting density. However, the heavy labor demanding high density cutting needs to be improved for hydroponic culture of $S.$ $samentosum$.

• Horticultural Science & Technology
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• v.29 no.3
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• pp.195-200
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• 2011

The growth, yield and quality of Sedum sarmentosum between soil and hydroponic cultivation were compared to produce high-quality shoots in summer season. The plants were collected from four places in Korea and cultivated in a plastic film house with 50% shading. A 1:1:1 mixtures of sand, upland soil and substrate (N-P-K: 330-220-400 $mg{\cdot}L^{-1}$) was used for soil cultivation, and a nutrient film technique (NFT) with Yamazaki-lettuce nutrient solution used for hydroponics. After 30 days of cultivation, plant height ranged from 18.4 to 21.8 cm and showed no significant difference between soil and hydroponic cultivation. Number of shoot, leaf length, leaf width, number of leaf, fresh weight, and dry weight significantly increased in hydroponics compared to those in soil cultivation. Fresh and dry weights in hydroponics were greater in 'Gunsan' and 'Wando' collections than those in other collections. Stem diameter and compression-force significantly increased in soil cultivation rather than hydroponics with significant differences among collections. However there were no significant differences in shoot bitterness and vitamin C content between cultivation methods or among the collections. Most mineral contents except Fe in hydroponics were higher than those in soil cultivation. K, Na, Zn contents in hydroponics were over 2 times higher than those in soil cultivation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.1
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• pp.24-32
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• 2023

The current Private 5G use procedure goes through the step of application examination, use and usage inspection, and can be divided in to application, examination step as a procedure before frequency allocation, and use, usage inspection step as a procedure after frequency allocation. Various types of documents are required to apply for a Private 5G, and due to the document screening process and radio station inspection for using Private 5G frequencies, the procedure for Private 5G applicants to use Private 5G is complicated and takes a considerable amount of time. In this paper, we proposed Frequency Allocation Process for Private 5G using a blockchain platform, which is fast and simplified than the current procedure. Through the use of a blockchain platform and NFT (Non-Fungible Token), reliability and integrity of the data required in the frequency allocation process were secured, and security of frequency usage information was maintained and a reliable Private 5G frequency allocation process was established. Also by applying the RPA system that minimizes human intervention, fairness was secured in the process of allocating Private 5G. Finally, the frequency allocation process of Private 5G based on the Ethereum blockchain was performed though a simulation.