• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.465-467
• /
• 2015

This paper implements a dual-mode power strip controller (PSCtrl) with environmental sensors which cooperates with Android-based smartphones. According to the statistics on fires in housing facilities, unidentified electrical fires account for 23.4%. In order to reduce these fire accidents caused by user carelessness and protect life and property, smart power control techniques with improved user convenience are required. For this reason, the implemented dual-mode PSCtrl controls ON-OFF operations of a power strip in two ways (e.g. manual and automatic modes) by cooperating with Android-based smartphones provided with environmental data from light, temperature, and humidity sensors. In manual mode, users check environmental data displayed on Android-based smartphones, forcibly controlling the ON-OFF operations through the dual-mode PSCtrl, and in automatic mode, when environmental data exceeds the threshold set by users in advance, the dual-mode PSCtrl automatically controls the ON-OFF operations. Some experimental tests verify successful dual-mode operations of the implemented dual-mode PSCtrl.

• Journal of Bio-Environment Control
• /
• v.13 no.4
• /
• pp.209-216
• /
• 2004

This study was aimed to assess the effects of microclimate factors on lettuce chlorophyll fluorescent responses and to develop an environment control system for plant growth by adopting a simple genetic algorithm. The photosynthetic responses measurements were repeated by changing one factor among six climatic factors at a time. The maximum Fv'/Fm' resulted when the ambient temperature was $21^{\circ}C,\;CO_2$ concentration range of 1,200 to 1,400 ppm, relative humidity of $68\%$, air current speed of $1.4m{\cdot}s^{-1}$, and the temperature of nutrient solution of $20^{\circ}C$. In PPF greater than $140{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, Fv'/Fm' values were decreased. To estimate the effects of combined microclimate factors on plant growth, a photosynthesis efficiency model was developed using principle component analysis for six microclimate factors. Predicted Fv'/Fm' values showed a good agreement to measured ones with an average error of $2.5\%$. In this study, a simple genetic algorithm was applied to the photosynthesis efficiency model for optimal environmental condition for lettuce growth. Air emperature of $22^{\circ}C$, root zone temperature of $19^{\circ}C,\;CO_2$ concentration of 1,400 ppm, air current speed of $1.0m{\cdot}s^{-1}$, PPF of $430{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and relative humidity of $65\%$ were obtained. It is feasible to control plant environment optimally in response to microclimate changes by using photosynthesis efficiency model combined with genetic algorithm.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2020.07a
• /
• pp.575-576
• /
• 2020

본 논문은 근래에 식용곤충 식품에 대한 수요 및 국민적 관심이 증가하여 관련 산업이 급격히 성장하고 있는 가운데, 건강기능성 효과가 널리 알려진 흰점박이꽃무지 유충의 안정적인 생산량 확보를 위한 스마트 사육사를 제작하고 그 성능을 평가한 결과이다. 사육사는 L6m×W3m×H2.8m 크기로 제작하였으며, 안정적인 사육환경을 위하여 사육실과 공조실을 분리하여 설계하였다. 공시재료는 생후 15일이 경과된 흰점박이꽃 무지 유충 1령이며, 스마트 사육사 내 사육환경은 온도 25±2℃, 습도 65±5%로 제어하였다. 사육조사는 매주 1회, 유충의 체중, 길이, 두께를 측정하였으며, 스마트 사육사의 성능평가를 위해 일반 사육농가(전북 소재)와 비교·분석하였다. 사육 4주 후 조사 결과, 스마트 사육사에서 사육한 유충의 체중과 길이는 각각 평균 1.97g/마리와 3.75cm로, 일반농가의 1.58g/마리와 3.55cm에 비해 비교적 높은 것으로 나타났다. 하지만, 두께의 경우 2주 차까지 일반농가에서 대체로 높은 것으로 나타났으며, 이후 3~4주 차에서는 큰 차이를 보이지 않았다. 따라서 본 연구를 통해 개발한 흰점박이꽃무지 유충 스마트 사육사는 일반농가와 비교해 사육이 비교적 빠르고 생산량을 더 많이 확보할 수 있는 시스템으로 농가소득 증대에 유용할 것으로 판단되며, 장소 및 시간에 상관없이 생육환경 제어가 가능하여 개발된 시제품의 보급 확대가 필요하다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.287-287
• /
• 2009

연료전지는 전기에너지와 열에너지를 동시에 사용 할 수 있기 때문에 에너지 효율이 높고 유해 배기물이 거의 없으므로 친환경적이다. 따라서 환경문제가 대두되고 있는 오늘날, 고효율 친환경의 연료 전지는 차세대 에너지원으로 각광받고 있다. 보일러와 계통선에서 열과 전기를 공급받는 기존방식에 비해 연료전지 코제너레이션 시스템의 경우 20%이상 에너지 절감율을 향상시킬 수 있다. 기존 10kW이하의 소용량 발전설비의 경우 대형 발전소와 같은 수준인 30%이상의 전기 효율을 기대할 수 없으나 고분자 전해질 연료전지를 적용할 경우 1kW급에서도 35%의 전기 효율을 기대할 수 있으며 열회수까지 고려할 경우 80%에 가까운 열효율을 달성할 수 있다.(4)연료전지 시스템은 연료전지 스택 이외에, 연료변환장치, 급기설비, 열 및 물관리 설비, 전력변환장치 그리고 제어 장치 등으로 구성된다. 연료전지 시스템 성능은 연료전지 스택의 성능에 가장 의존적인데 연료전지 스택의 성능은 같은 스택이라도 운전 및 제어 방법에 따라서 다양하게 변할 수 있다. 실제로 연료전지 스택 자체의 전기 변환 효율은 최대 40% 까지로 매우 높으나, 다양한 운전 조건에 따라 효율이 30~40% 수준에서 변화는 것이 현실이다. 때문에 시스템을 설계할 때에는 종합화된 시스템 측면에서의 운전까지 고려한 설계와 성능 해석이 필요하다. 그간 연료전지를 활용한 가정용 열병합 발전분야에서는 시스템 설계를 위한 시뮬레이션 기반 성능 해석에 관한 연구가 활발히 진행되어왔다. 하지만 연료전지 스택의 경우 간이화된 성능 모델식을 사용하여 이로 인한 성능 예측모델의 오차가 크게 발생하여 전체 시스템 최적화의 저해요인으로 작용하여왔다. 따라서 본 연구에서는 가정용 연료전지 열병합 발전 시스템을 자체적으로 설계 개발하였으며 이 중 연료전지 스택의 성능모델을 실험기반으로 구축하였다. 먼저 가정용 연료전지 열병합 발전 시스템의 설계는 크게 네 단계로 구분되며 이는 1) 시스템 개념 설계, 2) 연료전지 스택 설계, 3) 주변장치 설계, 4) 제어시스템 설계로 이뤄진다. 연료전지 스택의 성능 모델은 고분자연료전지의 성능에 가장 민감하게 영향을 미치는 온도 및 습도의 변화에 따른 다양한 스택 성능을 예측 가능하도록 개발하였으며 이는 간단한 이론 모델의 구조에 실험 데이터를 기반으로 모델 파라미터를 도출하는 기법으로 이뤄졌다.

• Journal of the Korean Solar Energy Society
• /
• v.36 no.5
• /
• pp.31-50
• /
• 2016

To develope a greenhouse fog cooling system to control the temperature and relative humidity simultaneously to the target value, a theoretical analysis and experiments were done. The control process includes the measuring of environmental variables, setting and coding of the water and heat balance equations to maintain the target temperature and relative humidity in greenhouse, calculating of the open level of the greenhouse roof window that governs the natural ventilation and spray water quantity, and operating of the motor to open/close the roof window and pump to spray for water. The study results were shown to be very good because the average air temperature in the greenhouse was kept to be about $28.2^{\circ}C$ with the standard deviation of about $0.37^{\circ}C$ compared to the target temperature of $28^{\circ}C$ and the average relative humidity was about 75.2% compared to the target relative humidity was 75% during the experiments. The average outside relative humidity was about 41.0% and the average outside temperature was $27.2^{\circ}C$ with the standard deviation of about $0.54^{\circ}C$. The average solar intensity in the greenhouse was 712.9 W. The wind velocity of outside greenhouse was 0.558 m/s with the standard deviation of 0.46 m/s.

• Journal of Bio-Environment Control
• /
• v.8 no.4
• /
• pp.281-287
• /
• 1999

In order to take a good look at effectiveness of cooling of Fog system and Pad-Fan system, we chose 49 farm households which were installed evaporative cooling system and 2 farm households which were installed Pad-Fan system and Fog system for a test. We execute the test on 29 households out of 49.6 households, which were installed Pad-Fan system, were able to use; however, 6 household out of 9 which were installed Fog system couldn't use it. The main reason was the clogged on nozzle. The cooling efficiency on Pad-Fan system was 77.4%, but it was very poor on Fog system. Since there are many problems on Fog system, we need more research on size of fog, the location of nozzle, control of Fog systems.

• Korean Journal of Food Science and Technology
• /
• v.21 no.5
• /
• pp.655-661
• /
• 1989

Optimal drying conditions consisting of air temperature and relative humidity were searched by the simulation-optimization technique for minimizing quality changes in red pepper drying. Optimized drying conditions were analysed in the viewpoint of quality change kinetics and effects of control variables on the state variables. Optimal drying conditions were nearly same in both cases for carotenoid maximization and browning minimization. In two staged optimized drying, relative humidity took a lower search limit of about 10%, and air temperature in the first stage was near the lower limit of $50^{\circ}C$ and in second stage increased to a higher temperature varying with total drying time and stage changing time. Response surface analysis of time invariable drying confirmed the location of the optimal point lying on the vertex of lower limit humidity and a lowest drying temperature which ensures to attain target moisture of 0.2g water/g dry solid. Two stage drying can attain the higher objective function of quality by 3-5% than time invariable drying for shorter total drying times.

• Journal of Bio-Environment Control
• /
• v.30 no.4
• /
• pp.383-392
• /
• 2021

It has been known that oyster mushrooms cultivated in facilities with thermal insulation have been strongly affected by inner environments. Forced air-circulation fans exert much direct influence on disturbing air inside the facility so the matter is of particular interest. This study is carried out to investigate the measured levels of air uniformity in a cultivation facility for oyster mushroom in the various cases that reversibly controlled air-circulation fans which drove the flow in the upward and reverse direction by turn and unidirectional fans by which the wind blew upwards only were operated from July 1 to 10. The actual survey for the selection of ongoing operation cases presented that farmers, even though there were some discrepancies, have made use of fans in a way that it paused for 5-30min after running for 5-15min by turn. The level of air uniformity in the case of adopting reversible fans revealed a slight difference of 1.4-1.8℃ (Temp.) and 7.8-8.7% (R.H.) under the condition of not using a cooler during the investigation period. By contrast, unidirectional fans showed a noticeable difference of 3.2-3.7℃ and 14.0-15.4%, which meant that air uniformity driven by reversible fans much more increased compared to that for unidirectional fans. Among the twenty operational applications considered for reversible fans, the circumstance that the wind blew upwards for 10-15min and ceased for 5-10min and blew again in the reverse direction for 10-15min in succession gave minor improvements at the level of air uniformity, but at present there was somewhat difficult to make decision on which cases were optimally best. It seems necessary that the effects of reversible fans on air uniformity as well as qualities of oyster mushrooms have to be appraised in the cultivation period and the flow visualization needs to be done to ascertain the performance of air mixture.

• Journal of Energy Engineering
• /
• v.25 no.3
• /
• pp.27-33
• /
• 2016

The heat recovery system that was applied in this study, is the energy-saving type that can produce the maximum cooling capacity less power in use. In order to have a more precise control function the temperature and humidity of the constant temperature and humidity machine, control algorithm is applied to designed a fuzzy PID controller, and the outside air compensation device (air-cooled) demonstrated excellent ability to dehumidify the moisture, $-20^{\circ}C$ in winter. High efficiency and the low-noise type sirocco fan operate quitely and designed to fit the bottom-up and top-down in accordance with the characteristics of equipment. as a result of experiment data, the conversion efficiency is 95% or more, power recovery time is within 5sec, stop delay time is within 30sec, pump down time is 10sec, pump delay time is 5sec, heating delay time is 5sec, temperature deviation is ${\pm}2^{\circ}C$ (cooling deviation: $2^{\circ}C$, Heating deviation : $2^{\circ}C$), humidity deviation is a ${\pm}5%$ (humidification deviation 3.0%, dehumidification deviation 3.0%). Recently, ubiquitous technology is important. so, the constant temperature and humidity machine designed to be able to remotely control to via the mobile phone, and more scalable to support MMI software and automatic interface. Further, the life of the parts and equipment is extended by the failure.

• Journal of Food Hygiene and Safety
• /
• v.31 no.6
• /
• pp.451-457
• /
• 2016

The purpose of this study was to determine the antimicrobial effects of $ClO_2$ gas on pathogenic E. coli and Salmonella spp. colonizing on the fruit surface of strawberries for export. Factorial design was employed to treat strawberries inoculated with pathogenic E. coli or Salmonella spp. with a combination of $ClO_2$ gas concentrations (10, 20, 30, 40, and 50 ppmv), RH (50, 70, and 90%), and treatment time (0, 5, 10, 20, and 30 min). Interaction between the factors was observed to note that the reduced levels of microbial population were the highest when RH is set at 90% with gas concentration- and treatment time-dependent manner. With RH and gas concentration fixed at 90% and 50 ppmv, the populations of E. coli and Salmonella spp. decreased by 2.07 and 2.28 log CFU/g when treated for 20 min whereas population reduction by 0.5 and 0.7 log CFU/g were observed when treated for 5 min, respectively. The results help establish most effective conditions for $ClO_2$ gas treatment to enhance microbial safety of strawberries for export.