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허승오,한경화,전상호,장용선,강신우,정선옥,김학진,이경환,Hur, Seung-Oh,Han, Kyeong-Hwa,Jeon, Sang-Ho,Jang, Yong-Sun,Kang, Sin-Woo,Chung, Sun-Ok,Kim, Hak-Jin,Lee, Kyeong-Hwan Institute of Agricultural Science 2011 Korean Journal of Agricultural Science Vol.38 No.4
Protected crop production has been popular in Korea as well as in other countries. Intensive and continuous monitoring and control of the environment, which is labor- and time-consuming, is critical for stable crop productivity and profitability, otherwise damage could be happened due to unfavorable ambient and soil conditions. In the study, potential utilization of smartphone and remote access application in protected crop production environment was investigated. Tested available remote access applications provided functions of mouse click (left and right buttons), zooming in and out, and screen size and color resolution control. Wi-Fi data communication speeds were affected by signal intensity and user place. Data speeds at high (> -55 dBm), medium (-70~-56 dBm), and low (< -71 dBm) signal intensity levels were statistically different (${\alpha}=0.05$). Means of data communication speed were 6.642, 4.923, and 2.906 Mbps at hot spot, home, and office, respectively, and the differences were significant at a 0.05 level. Smart phone and remote access application were applied successfully to remote monitoring (inside temperature and humidity, and outside precipitation, temperature, and humidity) and control (window and light on/off) of green house environment. Response times for monitoring and control were less than 1 s at all places for high signal intensity (> -55 dBm), but they were increased to 1 ~ 10 s at home and office and to 10 ~ 30 s at hot spot for low signal intensity (< -71 dBm) for Wi-Fi. Results of the study would provide useful information for farmers to apply these techniques for their crop production.
허승오,류명진,류동기,정선옥,허윤근,최진용,Hur, Seung-Oh,Ryu, Myong-Jin,Ryu, Dong-Ki,Chung, Sun-Ok,Huh, Yun-Kun,Choi, Jin-Yong Institute of Agricultural Science 2011 Korean Journal of Agricultural Science Vol.38 No.4
Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.
사양토에서의 용적수분 함량 측정을 위한 TDR 및 FDR 센서의 검증
허승오(Seung-Oh Hur),하상건(Sang-Keun Ha),김정규(eong-Gyu Kim) 한국토양비료학회 2009 한국토양비료학회지 Vol.42 No.2
토양의 용적수분 함량을 현장에서 측정할 수 있어 토양 내 물 이동이나 관개관리에 효과적으로 이용할수 있는 6종의 토양수분 센서에 대한 검정을 실시했다. TDR형태의 센서가 2종으로 토양단면측정용인 TRIME과 탐침형태인 Mini-TRASE이었으며, 4종은 FDR 형태의 센서로 토양단면 측정용인 EasyAG, EnviroSCAN, PR-1과 탐침형태의 WET-1 센서였다. 코어로 측정한 용적수분함량과 비교한 결과 TRIME은 1차 선형식의 관계에서 코어측정값과 약 2.4%의 오차를 나타냈고, Mini-TRASE는 코어 용적수분함량과 약 1.4%의 오차를 나타냈으며, 이 오차는 실험에 사용했던 7종의 센서들 중에서 가장 작은 값이었다. EasyAG는 SF로 분석했을 때는 코어측정값과 약 2.6%의 오차를 나타냈고, 센서로 측정한 토양수분 함량을 코어수분함량과 직접적으로 비교했을 때도 역시 약 2.6%의 오차를 나타냈다. EnviroSCAN은 SF로 분석했을 때는 코어측정값과 약 2.8%의 오차를 나타냈고, 센서로 측정한 토양수분 함량을 코어수분 함량과 직접적으로 비교했을 때는 2.6%의 오차를 나타냈다. WET-1은 센서로 측정한 값과 코어로 실측한 값 사이에 약 2.0%의 오차가 있음을 보여주고 있으며, 이것은 검정에 사용했던 FDR 센서들 중에서는 가장 작은 값이었다. PR-1은 측정시 access 튜브 내에서 방향을 조금씩 바꿀 때마다 측정값이 달리 나오는 경우가 많아 수분함량 측정횟수가 많지 않았으나 실측값과 약 4.7%의 오차를 보였다. 결론적으로 센서의 정확성을 검정하기 위해 사용된 6종의 센서 중PR-1은 현장 측정에 문제가 있을 것으로 여겨진다. This study was to verify and calibrate seven kinds of soil water sensors for volumetric soil water content(VSWC) measurement under field. Types of sensors were TDR (Time Domain Reflectometry) and FDR(Frequency Domain Reflectometry). Two kinds of TDR were TRIME(profile type), and Mini-TRASE(rod type). Five kinds of FDR were EasyAG, EnviroSCAN, PR-1(profile type), and WET-1(rod type). VSWC by TRIME and Mini-TRASE compared with VSWC by soil core showed the standard error of about 2.4%, and 1.4% which is the smallest value among all the sensors used in the experiment, respectively. The errors of EasyAG and EnviroSCAN analyzed with scaled frequency(SF) were about 2.6%, and 2.8% and those by 1 versus 1 correspondence were about 2.6%, and 2.6%, respectively. WET-1 showed about 2.0% of error, which is the smallest value among errors by FDR sensors. PR-1 with the error of about 4.7% should be hard for application in field. Therefore, users on soil water sensors have to take into consideration the errors of sensors revealed after the calibration for the correct measurement of VSWC in field. The rest except for PR-1 among the sensors could be used for VSWC measurement with 1.4~2.6% error.
석회암 유래 토양에서의 물의 이동특성과 토양 입자 및 유기물과의 관계에 따른 Pedo-Transfer Function의 결정
허승오(Seung-Oh Hur),정강호(Kang-Ho Jung),손연규(Yeon-Kyu Sonn),하상건(Sang-Keun Ha),김정규(Jeong-Gyu Kim) 한국토양비료학회 2009 한국토양비료학회지 Vol.42 No.2
강원도 남부(영월)와 충북 제천, 단양 등지에 널리 분포하는 석회암에서 유래된 토양은 점토 및 철분함량이 많은 식질계 토양으로 세립(細粒)질로 구성이되어 있고 자갈이나 잔돌이 있는 토양으로 분류되므로 토양의 침투 및 투수속도가 화강암이나 화강편마암 유래 토양과는 다른 양상을 보인다. 본 연구는 석회암 유래 토양의 침투속도와 토양층위별 투수속도 측정결과인 현장 포화수리전도도(Kfs, field saturationhydraulic conductivity)에 토양의 입도 분포 및 유기물 함량이 미치는 영향을 파악하고자 그들 사이의 상호관계를 분석하였다. 실험을 위해 이용된 토양은 과림, 모산, 장성, 마지,안미, 평안의 6개 토양통이었고 장력 침투계(disctension infiltrometer)와 투수속도 측정계(Guelphpermeameter)로 침투 및 투수속도를 측정하고 입도분포와 유기물함량을 분석했다. 전체 측정대상 토양의 표토 및 층위별 Kfs와 그 토양들의 모래, 미사, 점토 및 유기물 함량과는 유의한 상관관계를 찾을 수없었다. 그것은 측정 토양이 농경지 토양 외에도 산림 토양이 포함되어 있고, 산림토양도 유기물 층이 존재 한다거나 다량의 자갈이나 잔돌 등의 함량이 존재하기 때문인 것으로 여겨진다. 이것은 포화수리 전도도가 토양의 입도분포나 유기물 함량과의 관계가 있다고 했던 다수의 연구와는 상반된 결과이므로 이를 더검토해볼 필요성이 있다. 이를 위해, 측정된 6개의 대상 토양 중에서 암쇄토인 모산통과 유기물 함량이9.2%로 일반토양보다 월등히 높은 과림통의 O충을 제외하고 토양 입도분포 및 유기물 함량과 침투 및 투수속도와의 관계를 살펴보았다. 분석결과 모래의 함량과 Kfs의 관계는 결정계수(R<SUP>2</SUP>)가 0.309로 비교적 낮게 나타나고 있지만 정의 직선 상관관계를 나타냈으며, 미사함량과는 관계가 없었고, 점토함량과는 결정계수가 0.3164로서 부의 직선 상관관계를 나타냈다. 유기물 함량과는 다른 토양 입도분포들보다 결정계수가 높으며(R<SUP>2</SUP>=0.4884<SUP>*</SUP>) 지수함수 관계를 나타내고 있다. 이러한 결과들을 종합하면 석회암 유래토양에서의 현장포화수리 전도도는 모래나 유기물 함량이 많으면 증가하고 점토 함량이 많으면 감소할 것이므로 이들을 조합한다면 현장 포화수리전도도를 예측하는 PTF(Pedo-Transfer Function)를 작성할 수 있다. 본연구에서는 이를 위해 모래, 점토, 유기물 함량을 고려해 PTF를 분석한 결과 점토는 다중 공선성 때문에 제외를 하고 모래와 유기물 함량만을 이용해 Kfs를 예측할 수 있는 PTF를 작성했다. Soils originated from limestone, located at the southern part of Kangwon province and Jecheon, Danyang of Chungbuk province are mainly composed of fine texture, have different properties from soils originated from granite and granite gneiss, especially for water movement. This study was conducted for making PTF(Pedo-Transfer Function) for Kfs(field saturaton hydraulic conductivity) estimation, and for investigating the relation between soil particle distribution and the infiltration and percolation rate in soils originated from limestone. Soils used for the experiment were 6 soils of Gwarim, Mosan, Jangseong, Maji, Anmi and Pyongan series. Infiltration and percolation rate for the soil were measured by a disc tension infiltrometer and a Guelph permeameter, respectively. The particle size distribution and organic matter content of the soils were analyzed. Kfs was not related with sand, silt, clay, and organic mattrer (OM) content because of forest soils which contained high gravel, pebble, and cobble content, and O layer with high OM content. After Mosan soil series and O layer of Gwarim series were excluded for the data analysis, Kfs was explained as a linear function with sand and clay content and a exponential function with OM content. As a result, the PTF equation was obtained as Kfs=-4.20558+0.479706*(S) +0.023187*exp(1.829*OM) (R<SUP>2</SUP>=0.6558<SUP>*</SUP>).
허승오(Seung-Oh Hur),류명진(Myong-Jin Ryu),류동기(Dong-Ki Ryu),정선옥(Sun-Ok Chung),허윤근(Yun-Kun Huh),최진용(Jin-Yong Choi) 충남대학교 농업과학연구소 2011 농업과학연구 Vol.38 No.4
Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, CO2, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.