• Journal of Bio-Environment Control
• /
• v.9 no.4
• /
• pp.201-206
• /
• 2000

A certain system to overcome high temperature should be introduced for the stable year-round cultivation in greenhouses. There are efficient methods to overcome high temperature such as ventilation system with shading screen, fan and pad system with screen, and fog system with screen. This study was carried out to find a means to determine the capacity of such system. Heat balance equations for each system were established and verified by experimental results. The calculated ventilation rates from heat balance equations showed a good agreement with the measured ones. The evapotranspiration coefficient was the most important parameter affecting the ventilation requirement among input parameter affecting the ventilation requirement among input parameters except weather data. When the evaportanspiration coefficient increased 1%, the ventilation requirement decreased 1.3%. Therefore the data of evapotranspiration coefficient should be accumulated by various experiments, and then design standards and selection guidelines should be provided. The simulation results for same design conditions shown that air exchanges requirement and evaporating water of fan and pad system were 5.1∼7.7% and 6.8∼9.3% larger than those of fog system, respectively.

• Journal of KIISE
• /
• v.43 no.6
• /
• pp.710-717
• /
• 2016

Recently, several research studies on things abstraction framework have been proposed in order to implement the multi-service Internet of Things (IoT) system, where various IoT services share the thing devices. Distributed things abstraction has an IoT service duplication problem, which aggravates power consumption of mobile devices and network traffic. On the other hand, cloud server-centric things abstraction cannot cover real-time interactions due to long network delay. Fog server-centric things abstraction has limits in insufficient IoT interfaces. In this paper, we propose Smart Fog which is a fog server-centric things abstraction framework to resolve the problems of the existing things abstraction frameworks. Smart Fog consists of software modules to operate the Smart Gateway and three interfaces. Smart Fog is implemented based on IoTivity framework and OIC standard. We construct a smart home prototype on an embedded board Odroid-XU3 using Smart Fog. We evaluate the network performance and energy efficiency of Smart Fog. The experimental results indicate that the Smart Fog shows short network latency, which can perform real-time interaction. The results also show that the proposed framework has reduction in the network traffic of 74% and power consumption of 21% in mobile device, compared to distributed things abstraction.

• Radiation Oncology Journal
• /
• v.20 no.4
• /
• pp.375-380
• /
• 2002

Purpose : To develop a practical film dosimetry system for routine Quality Assurance (QA). Materials and Methods :An One Click Film (OCF) Dosimetry system was designed to perform swift routine QA with functions including automatic fog value elimination, angle adjustment, automatic symmetry calculation, and realtime profile generation with the ability to display realtime three-dimensional dose distributions. Results : The most frequently used functions for routine QA, such as the elimination of the fog value, conversion into an H&D curve, symmetry, and isodose distribution, can be achieved with only one click. Conclusion : Reliable results were achieved with the OCF dosimetry with simpler steps than other commercially available film dosimetry systems for routine QA. More research on the refined user interface will make this system be clinically useful.

• Journal of Korea Multimedia Society
• /
• v.20 no.8
• /
• pp.1369-1378
• /
• 2017

Pub/Sub (Publish/Subscribe) paradigm is a simple and easy to use model for interconnecting applications in a distributed environment. In general, subscribers register their interests in a topic or a pattern of events and then asynchronously receive events matching their interest, regardless of the events' publisher. In order to build a low latency lightweight pub/sub system for Internet of Things (IoT) services, we propose a GQSFPS (Group Quorum System-based Fog Pub/Sub) system that is a core component in the event-driven service oriented architecture framework for IoT services. The GQSFPS organizes multiple installed pub/sub brokers in the fog servers into a group quorum based P2P (peer-to-peer) topology for the efficient searching and the low latency accessing of events. Therefore, the events of IoT are cached on the basis of group quorum, and the delay-sensitive IoT applications of edge devices can effectively access the cached events from group quorum fog servers in low latency. The performance of the proposed GQSFPS is evaluated through an analytical model, and is compared to the GQPS (grid quorum-based pud/sub system).

• Journal of Korea Multimedia Society
• /
• v.20 no.12
• /
• pp.1928-1939
• /
• 2017

Fog computing is another paradigm of the cloud computing, which extends the ubiquitous services to applications on many connected devices in the IoT (Internet of Things). In general, if we access a lot of IoT devices with existing cloud, we waste a huge amount of bandwidth and work efficiency becomes low. So we apply the paradigm called fog between IoT devices and cloud. The network architecture based on cloud and fog computing discloses the security and privacy issues according to mixed paradigm. There are so many security issues in many aspects. Moreover many IoT devices are connected at fog and they generate much data, therefore light and efficient security mechanism is needed. For example, with inappropriate encryption or authentication algorithm, it causes a huge bandwidth loss. In this paper, we consider issues related with data encryption and authentication mechanism in the network architecture for cloud and fog-based M2M (Machine to Machine) IoT services. This includes trusted encryption and authentication algorithm, and key generation method. The contribution of this paper is to provide efficient security mechanisms for the proposed service architecture. We implemented the envisaged conceptual security check mechanisms and verified their performance.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.41 no.1
• /
• pp.60-71
• /
• 1999

This study was performed to improve underirable warm greenhouse environment by fog cooling system in summer season. The resultsof droplet size analysis and cooling effects for fog cooling system are summarized as follows ; 1. At the pump pressure of 70kgf/$\textrm{cm}^2$ , the mean (SMD) drop size was 22.6${\mu}{\textrm}{m}$ and the maximum and minimum drop size was 45.68${\mu}{\textrm}{m}$ and 1.73${\mu}{\textrm}{m}$ , respectively, and almost all of the drop size was less than 40${\mu}{\textrm}{m}$. 2. The temperature of fog cooling greenhouse with 60% shading was dropped more than 2$^{\circ}C$ below the ambient temperature , while the greenhouse temperature without shading was 1$^{\circ}C$ higher than the ambient temperature. 3. It was found that fog spraying intervals were significantly influential on cooling effect. 4. When the greenhouse was ventilated sufficiently by natural vent system, green house temperature could be maintained by 2.5$^{\circ}C$ lower than the ambient temperature, while it was difficult to drop the greenhouse temperature below ambient temeperature without sufficient ventilation. 5. It was found that the temperature of experimental greenhouse could be maintained 3$^{\circ}C$ to 14$^{\circ}C$ lower that of control greenhouse though there were variations depending on experimental and weather conditions.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.5
• /
• pp.49-55
• /
• 2012

In order to derive the efficient utilization of low pressure compressed air fogging system, cooling efficiencies with control types were analyzed through cooling experiments in tomato greenhouses. The control types were set up with temperature control, humidity control, temperature and humidity control, and time control. It showed that the cooling effects were 0.7 to $3.3^{\circ}C$ on average and maximum of 4.3 to $7.0^{\circ}C$, the humidification effects were 3.5 to 13.5 % on average and maximum of 14.3 to 24.4 %. Both the cooling and humidification effect were the highest in the time control method. The cooling efficiency of the air fogging system was not high with 8.3 to 27.3 % on average. However, the cooling efficiency of 24.6 to 27.3 % which appears from the time control is similar to the cooling efficiency of high pressure fogging system experimented in Japan. The air fogging system is operated by low pressure, but its efficiency is similar to high pressure. We think because it uses compressed air. From this point of view, we suggest that the air fogging system can get the cooling efficiency of similar levels to that of high pressure fogging system and it will have an advantage from clogging problem of nozzle etc.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2018.10a
• /
• pp.212-215
• /
• 2018

현재 자동차 사고 보험에서는 보험사기 문제가 해결되지 못하고 있다. 매년 자동차 보험 회사의 보험사기로 인한 금전적 손해는 증가하고 있다. 또한 보험사기를 막기 위해 적용되는 필수적인 보험 회사 직원의 현장 방문은 비효율적이고 보험금을 받을 때까지 많은 시간을 소모한다. 이를 해결하기 위해 자동차 보험에 블록체인을 적용한 go2solution은 기존 보험 처리 과정을 단축시켰지만 보험청구자의 사진만으로 사고 발생을 판단하기 때문에 사고를 입증하는데 증거가 부족하고 이를 이용한 보험 사기가 가능하다. 따라서 사고 발생 여부의 신뢰도를 측정하여 보험사기를 방지할 수 있도록 블록체인 기반 자동차 보험 신뢰모델을 제안한다. 포그 컴퓨팅을 적용하여 차량, 보험회사, RSU의 정보 공유를 원활하게 한다. 또한 목격자들이 신뢰요소로 적용될 수 있도록 블록체인 컨소시엄을 통한 인센티브 시스템을 적용하여 목격자들은 적극적으로 사고정보를 제공한다. 이렇게 수집된 다양한 신뢰요소 데이터를 분석하여 신뢰점수와 등급을 정한다. 이때 회귀분석을 적용하여 각각의 신뢰요소의 중요도에 따라 다른 가중치를 적용하여 정확한 신뢰점수를 책정한다. 결과적으로 보험회사는 보험사기 피해액을 절감하고 보험청구자는 인센티브를 사용하여 적은 보험료를 지불한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2018.05a
• /
• pp.145-148
• /
• 2018

클라우드 컴퓨팅 기반 사물인터넷 환경은 급격히 증가하는 통신량, 기종 간 이질성, 지연 시간과 같은 문제점으로 인해 어려움을 겪고 있다. 이를 해결하기 위한 대표적인 방법 중 하나는 분산 모델을 통해 클라우드 컴퓨팅 환경에 집중된 네트워크 또는 컴퓨팅 파워를 분산시키는 포그 컴퓨팅 (Fog Computing) 또는 에지 컴퓨팅 (Edge Computing)을 활용하는 것이다. 그러나 이 분산형 네트워크의 단점을 보완하기 위해 사물인터넷 (IoT, Internet of Things)과 가장 가까이 존재하는 네트워크 모델로써 미스트 컴퓨팅 (Mist Computing)이 탄생하였다. 그러나 다양한 프로토콜에 의해 통신이 이루어지는 사물인터넷 환경에는 수천 가지 제로데이 공격이 존재한다. 이 공격들의 대부분은 이전에 알려진 공격의 작은 변형체이다. 이러한 공격을 효과적으로 막기 위해 사물인터넷 환경에서의 침입 탐지 시스템은 지능적이어야 한다. 따라서 본 논문에서는, 미스트 컴퓨팅 환경에서 새로운 또는 지속적으로 변화하는 사물인터넷 대상 공격을 효과적으로 방어하기 위한 인공지능 기반 침입 탐지 시스템을 제안한다.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.6_2
• /
• pp.1075-1080
• /
• 2020

The control on temperature and humidity on the cow-house is essential to assure production efficiency and the control on disease of cows. Fog system and screen fence are typical methods to drop the temperature inside of cow-house during the summer season. This study focused on the change in temperature and humidity under the condition of application of those methods. The results indicate that the installation of atomizer and insulation curtain cause decrease in temperature and increase in humidity. However, Using both of methods at the same time doesn't make any additional meaningful effects on temperature and humidity.