• Journal of Bio-Environment Control
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• v.24 no.1
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• pp.34-38
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• 2015

This research was conducted to establish efficient methods to overcome high temperature and low humidity with light selective shading agent and two-fluid fogging system in greenhouses in hot season. There were four experimental treatments; not treated (Non), fogging by two-fluid fogging system (Fog), spraying onto the greenhouse surface with shading coating agent (Coat), and using fogging and coating together (F&C). The amount of solar radiation entered into the greenhouses was higher in Non, and then Fog, Coat, and F&C in descending order. Fog was more efficient to lower the air temperature and also raise relative humidity than Coat treatment. The crop temperature was about $6^{\circ}C$ higher in Control than the other treatments. F&C revealed as the most efficient method to control the environment inside the greenhouse, but fogging system seemed to be more economic. In stand-alone greenhouses spraying coating agent may be the appropriate choice because of their structural limitations, mainly eave height.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2000.10b
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• pp.84-88
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• 2000

첨단유리온실의 건설이 증가하면서 여름철 온실내 환경의 적정화를 위하여 증발냉각시스템의 도입이 증가하고 있으며, 대표적인 증발냉각시스템은 패드-팬 시스템과 포그시스템 등이 있다. 포그시스템은 냉방효율이 높고 다른 시스템과 비교하여 저비용이며 온실내부공간의 활용면에서 우수한 장점이 있어 그 보급이 증가하고 있다. (중략)

• Journal of Bio-Environment Control
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• v.20 no.1
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• pp.1-7
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• 2011

The objective of the present study is to identify the applicability of a low pressure fogging system for cooling commercial tomato greenhouse. In particular, the cooling system in this experiment utilizes low pressure spray nozzles which were developed in Korea recently. The experimental result that the temperature in fog-cooled greenhouse was lower than the non-cooled greenhouse showed the cooling effect by the low pressure fogging system. But because the relative humidity in fog-cooled greenhouse was comparatively low, the satisfactory cooling effect could be acquired by narrowing the space of fog nozzles and extending fogging time to supply more fog spray quantity. The variation of temperature distribution in fog-cooled greenhouse along timelag was insignificant during short time, but that was great during long period of day. This result showed the variation of temperature along timelag was slight by fog cooling but great by other factors like radiation, ventilation, air flow, etc. The advanced operation technology of fog system was required to reduce the variation of temperature along time lag. We plan to suggest the advanced installation and operation technology of low pressure fogging system for cooling commercial tomato greenhouse by further experiments in near future.

• Journal of Bio-Environment Control
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• v.11 no.2
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• pp.93-100
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• 2002

This study was carried out not only to develop CFD model for numerically simulating fog cooling system but also to verify the validity of the developed model by data measured in fag cooling greenhouse. In addition the developed model was applied to investigate the effects of spraying water temperature, spraying water amount, spraying interval and evaporation percentage on the performance of the fog cooling system. According to the simulation results, the temperature differences between the measured and predicted temperatures at each measurement point were $0.1~1.4^{\circ}C$ in case of no shading and $0.2~2.3^{\circ}C$ in close of shading. The humidity differences were 0.3~6.0% and 0.7~10.6%, respectively in the cases of no shading and shading. Because the predicted data showed a good agreement with the measured ones, the developed model is supposed to be able to predict the cooling effect of the fog cooling system. The performance of fog cooling system was greatly influenced by spraying water amount, spraying interval and evaporation percentage, but it was not influenced by spraying water temperature.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.120-126
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• 2012

Two experiments were designed and executed to measure the effectiveness of the two-fluid fogging system in controlling whiteflies in tomato cultivation. The two-fluid fogging system that lowers temperature and raises humidity in greenhouses provides an eco-friendly method of preventing damages from whiteflies. The first experiment elucidated the effect of fogging treatment on the elimination of whiteflies and investigated the sectional distribution of whiteflies. The second experiment analyzed the vertical distribution, the motility of whiteflies and reduction of the number of whiteflies under the fogging system. The result of the experiments showed that the fogging system lowered the number of whiteflies and decreased their motility significantly. It affected the vertical distribution of whiteflies as well. Based on these experiments, we strongly recommend using the fogging system to prevent and control whiteflies in greenhouses, in addition to installing yellow sticky traps in the areas that have the highest density of whiteflies.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.563-564
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• 2018

최근 차량 네트워크에서 포그 컴퓨팅 기능을 적용하는 새로운 연구가 진행 중이다. 특히, 최근 개발 중인 차량 포그 컴퓨팅 기술은 교통 정보를 실시간으로 수집하여 빠른 처리가 가능하며 이를 장법을 통해 안정된 차량 및 교통 서비스를 제공할 수 있다. 이런 차량 포그 컴퓨팅 기술은 교통 정보 수집, 운전 정보 제공, 스마트 교통 통제 및 도로 안전 메시지 등의 정보를 차량에 빠르게 전달할 수 있다. 본 논문에서는 차량 포그 컴퓨팅 기술을 리뷰하고 교차로 환경에서 차량 포그 컴퓨팅 기반 안전 메시지 전달을 위한 교통 시스템을 제안한다. 특히, 제안하는 기법은 대기 시간에 민감한 안전 메시지를 빠르게 전송할 수 있는 장점을 가지고 있다.

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.265-276
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• 2020

This study was conducted to provide a basis for raising farm income by increasing the yield and extending the cultivation period by creating an environment where crops can be cultivated normally during high temperatures in summer. The maximum cooling load of the multi-span greenhouse with a floor area of 504 ㎡ was found to be 462,609 W, and keeping the greenhouse under 32℃ without shading the greenhouse at a high temperature, it was necessary to fog spray 471.6 L of water per hour. The automatic fog cooling control device was developed to effectively control the fog device, the flow fan, and the light blocking device constituting the fog cooling system. The fog cooling system showed that the temperature of the greenhouse could be lowered by 6℃ than the outside temperature. The relative humidity of the fog-cooled greenhouse was 40-80% during the day, about 20% higher than that of the control greenhouse, and this increase in relative humidity contributed to the growth of cucumbers. The relative humidity of the fog cooling greenhouse during the day was 40-80%, which was about 20% higher than that of the control greenhouse, and this increase in relative humidity contributed to the growth of cucumbers. The yield of cucumbers in the fog-cooled greenhouse was 1.8 times higher in the single-span greenhouse and two times higher in the multi-span greenhouse compared to the control greenhouse.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.147-152
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• 2015

In order to develop the cooling load estimation method in the greenhouse, the cooling load calculation formula based on the heat balance method was constructed and verified by the actual cooling load measured in the fog cooling greenhouse. To examine the ventilation heat transfer in the cooling load calculation formula, we measured ventilation rates in the experimental greenhouse which a cooling system was not operated. The ventilation heat transfer by a heat balance method showed a relatively good agreement. Evaporation efficiencies of the two-fluid fogging system were a range of 0.3 to 0.94, average 0.67, and it showed that they increased as the ventilation rate increased. We measured thermal environments in a fog cooling greenhouse, and calculated cooling load by heat balance equation. Also we calculated evaporative cooling energy by measuring the sprayed amount in the fogging system. And by comparing those two results, we could verify that the calculated and the measured cooling load showed a relatively similar trend. When the cooling load was low, the measured value was slightly larger than calculated, when the cooling load was high, it has been found to be smaller than calculated. In designing the greenhouse cooling system, the capacity of cooling equipment is determined by the maximum cooling load. We have to consider the safety factor when installed capacity is estimated, so a cooling load calculation method presented in this study could be applied to the greenhouse environmental design.

• Smart Media Journal
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• v.11 no.3
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• pp.39-53
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• 2022

Cloud of Things (CoT) can provide IoT applications with unlimited storage functions and processing power supported by cloud services. However, in a centralized cloud of things, it can create a single point of failure that can lead to bottleneck problems, outages of the CoT network. In this paper, to solve the problem of centralized cloud of things and interoperate between different service domains, we propose an IoT service interoperability system using distributed fog computing and blockchain technology. Distributed fog is used to provide real-time data processing and services in fog systems located at a geographically close distance to IoT devices, and to enable service interoperability between each fog using smart contracts and distributed ledgers of the blockchain. The proposed system provides services within a region close to the distributed fog entrusted with the service from the cloud, and it is possible to access the services of other fogs without going through the cloud even between fogs. In addition, by sharing a service right token issuance information between the cloud and fog nodes using a blockchain network, the integrity of the token can be guaranteed and reliable service interoperability between fog nodes can be performed.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.6
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• pp.60-71
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• 2019

As IoT systems such as smart farms and smart cities become popular, a large amount of data collected from many sensor nodes is sent to a server in the Internet, which causes network traffic explosion, delay in delivery, and increase of server's workload. To solve these problems, the concept of fog computing has been proposed to store data between IoT systems and servers. In this study, we implemented a software platform of the fog node and applied it to the prototype smart farm system in order to check whether the problems listed above can be solved when using the fog node. When the fog node is used, the time taken to control an IoT device is lower than the response time of the existing IoT device-server case. We confirmed that it can also solve the problem of the Internet traffic explosion and the workload increase in the server. We also showed that the intelligent control of IoT system is feasible by having the data visualization in the server and real time remote control, emergency notification in the fog node as well as data storage which is the basic capability of the fog node.