기술의 발전에 따라 전 세계적으로 교량은 대형화되고 있으며, 또한 노후 교량의 수도 급격히 증가하고 있다. 이들 대형, 노후 교량 에 대한 구조건전성 모니터링은 대형 사고 예방을 위해 필수적이다. 본 연구에서는 LoRa LPWAN 기반 무선계측시스템의 적용에 대 한 연구를 수행하였으며, 전남 신안군에 위치한 천사대교의 사장교 구간에 LoRa 무선계측시스템을 구축하였다. 교량의 주탑, 케이블, 보강거더에 대하여 계측시스템을 구축하여 기구축되어 운영 중인 유선기반 모니터링 시스템과 성능 및 경제성을 비교하여 LoRa LPWAN 기반 무선 모니터링 시스템의 대형 교량에서의 적용성을 검토하였다.

The IoT-based sensor network is one of the methods that can be efficiently applied to maintain the facilities, such as bridges, at a low cost. In this study, based on LoRa LPWAN, one of the IoT communications, sensor board for cable tension monitoring, data acquisition board for constructing sensor network along with existing measurement sensors, are developed to create bridge structural health monitoring system. In addition, we designed and manufactured a smart sensor node for LoRa communication and established a sensor network for monitoring. Further, we constructed a test bed at the Yeonggwang Bridge to verify the performance of the system. The test bed verification results suggested that the LoRa LPWAN-based sensor network can be applied as one of the technologies for monitoring the bridge structure soundness; this is excellent in terms of data rate, accuracy, and economy.

국내 고도성장기 이후 본격 건설되기 시작한 사회 기반 시설물은 노후화가 빠르게 진행되고 있다. 특히 사고 발생 시 대량 인명 피해로 직결될 수 있는 교량, 터널 등의 대형 구조물에 대한 안전성 평가가 필요하다. 하지만 기존의 유선 센서 기반의 Structural Health Monitoring(SHM)을 개선한 무선 스마트 센서 네트워크는 짧은 신호 도달거리로 인해 경제적이고 효율적인 시스템 구축이 힘들다. 따라서 LoRa LPWAN 시스템은 사물인터넷의 확산과 더불어 저전력 장거리 통신이 각광을 받고 있으며, 이를 구조 건전성 모니터링에 응용함으로써 경제적이면서도 효율적인 모니터링 시스템 구축이 가능하다. 본 연구에서는 LoRa LPWAN 기반의 무선 계측센서 기술 동향을 조사하였으며, LoRa LPWAN 기반의 무선 계측센서 설치 및 유지관리 방안을 제안한다.

PURPOSES: The objective of this study is to develop an external lighting traffic sign system for better visibility. METHODS: To develop an external lighting traffic sign system, we selected an installation location and an appropriate angle of view for the luminaire. Using these parameters, we developed an external traffic sign system based on field installation results on the lighting and reflector. The economic benefit is then compared with the cost, an analysis that is necessary for both internal and external lighting traffic signs. RESULTS: Through experiments on the number of luminaires necessary to improve illuminance deviation and visibility, it was confirmed that the illuminance was improved roughly 2 to 3 times by the use of two luminaires. The protruding height (H) of the luminaire is 1.0 m, in consideration of the differences in brightness and driver visibility between the top and bottom, and the angle of view of the luminaire is applied at 120 degrees of high-brightness and low-brightness difference. The lower illuminance is lowered because of the diffusion of light according to the angle of view of the luminaire, due to the longer protruding length of the external lighting type traffic sign. To improve from this problem, the experiment was performed with the application of the reflecting plate, the lower illuminance of the sign was lowered, and the upper and lower illuminance ratio was improved. This solution was confirmed to be effective. As a result of reviewing the economic feasibility of the external illuminated traffic sign system, the cost reduction effect was determined to be about 39.8%. CONCLUSIONS: The results of this study were used to develop a balanced combination of the optimum housing and lighting installation angle for external lighting traffic signs. The use of this technology requires further research under various site conditions.

국내 고도성장기 이후 본격 건설되기 시작한 사회 기반 시설물은 노후화가 빠르게 진행되고 있다. 특히 사고 발생 시 대량 인명 피해로 직결될 수 있는 교량, 터널 등의 대형 구조물들에 대한 안전성 평가가 필요하다. 하지만, 기존의 유선 센서 기반의 SHM을 개선한 무선 스마트 센서네트워크는 짧은 신호도달거리로 인해 경제적이고 효율적인 시스템 구축이 힘들다. 따라서 LoRa LPWAN시스템은 사물인터넷의 확산과 더불어 저전력 장거리통신이 각광을 받고 있으며, 이를 구조건전성 모니터링에 응용함으로써 경제적이면서도 효율적인 SHM 구축이 가능하다. 본 연구에서는 LoRa LPWAN의 구조건전성 모니터링에 적용 가능성을 검토하고 비면허 통신 대역을 사용함으로 인해 발생하는 채널간의 충돌을 해결하면서 대역폭을 효율적으로 활용할 수 있는 채널 기반의 LoRa 네트워크 운영방법을 제안한다.

LoRa LPWAN 네트워크 시스템은 비면허 무선통신을 이용하고, Mems 기반 통합센서를 통하여 Data 계측 및 기존 계측센서의 무선통신을 구현한 시스템이다. 본 시스템은 기존의 무선계측시스템 대비 장거리 통신과 기존망을 활용한 기술적/경제적인 우수성을 갖고 있으며, 유선계측시스템 대비 시스템 구축장비의 최소화로 경제성을 확보하였다. 경제성 검토항목에서 기존 유선계측 시스템 대비 약 41%의 경제적인 절감효과가 가능하다는 것을 확인하였다. 또한 유지관리 및 운영적인 측면에서도 우수하기 때문에 향후 국내에서도 많은 교량에 설치가 된다면, 교량의 유지관리 분야의 우수한 시스템으로 발전되고, 재난(지진 산사태 등), 환경(오염물 측정 및 관리 등), 플랜트 분야(화재 안전 등)에도 폭넓게 사용되길 기대한다.

최근 도심지와 산간지역에 설치되는 도로터널의 경우 터널개소의 증가와 장대화로 화재 사고가 점차 증가되고 있어 터널의 방재시설 강화가 요구되고 있다. 하지만 터널화재 발생시 대규모 인명피해가 발생될 수 있는 연기질식사 방지를 위한 연구는 부족한 실정이다. 본 연구에서는 화재발생시 연기확산을 차단하여 질식사 최소화 및 대피시간을 확보 할 수 있는 에어커튼 시스템을 개발하였다. 에어커튼 시스템은 방재설계 사례를 기준으로 시뮬레이션(CFD)을 통한 최적화 방안(분사각도, 분사량 등)을 도출하였으며, 실내 Lab Test 및 실제 도로터널서 화재실험을 실시한 결과 차연성능을 발휘하였다. 이론적/실험적 검증을 통한 에어커튼 시스템 도입을 통하여 도로터널의 인명피해를 최소화 할 수 있는 새로운 방재시설로 발전되길 기대한다.

Coming with the well-being era, consumer’s demand for safe agricultural products is increasing. It is urgent to develop an environment-friendly pear production system. Accordingly, this study was conducted to develop an environment-friendly pear production system by using several environment-friendly agricultural materials which is known to be effective in agricultural production. In the effects of environment-friendly agricultural materials on the soil chemical characteristics in pear orchard, the content of total carbon, organic matter, Ca and Mg increased a little respectively compared with those of 2008, and 2nd treatment showed the highest EC and Mg content in the soil among treatments. The content of leaf N, P and Ca in 2009 decreased compared with those of 2008, while Mg content showed no difference between 2008 and 2009 years. Average pear weight in 2009 was 31g higher than that of 2008 (682g) and 2nd treatment showed the highest pear weight (738g) among treatments. The average sugar content was higher in 2009 (12.6°Bx) compared with that of 2008 (12.2°Bx) and the plot of 2nd treatment highest sugar content (12.6°Bx) among treatments. There were no difference in hunter value of L among treatments, but hunter value of a showed higher 1.62 in 2009 than that of 2008 (3.73). The highest of gumminess and cohesiveness of fruits were obtained from 1st treatment and adhesiveness and chewiness of fruits were obtained from 3rd and 1st treatment respectively. Firmness of fruit increased a little in 2009 compared with that of 2008, while the highest firmness was obtained from 3rd treatment with 1.63㎏/5㎜∮ among treatments. Phosphate content in the peel of ‘Niitaka’ pear of fruit skin in 2009 (0.97g/㎏) showed 0.06g/㎏ more content than that of 2008 (0.91g/㎏), while the highest content was obtained from 3rd treatment (1.15g/㎏). Potassium content in the peel of ‘Niitaka’ pear in 2009 was 8.20g/㎏, which is 0.06g/㎏ more content than that of 2008 (7.82g/㎏) and the highest content was obtained from 1st treatment (8.34g/㎏) among treatments. The highest nitrogen content in the flesh of ‘Niitaka’ pear was obtained from 3rd treatment (4.32㎎/g), while it was the lowest in control plot (3.10㎎/g). Phosphate content in the flesh of ‘Niitaka’ pear in 2009 (8.20g/㎏) showed 0.06g/㎏ more content than that of 2008 (7.82g/㎏), while the highest content was obtained from 1st treatment (8.34g/㎏). There were no difference of the potassium content in the fruit peel of ‘Niitaka’ pear between years, but 1st treatment showed the highest content (11.81g/㎏) among treatments, while the lowest was obtained from the control plot (10.83g/㎏).

Coming with the well-being era, consumer’s demand for safe agricultural products is increasing. So, it is urgent to develop an environment-friendly rice production system. Accordingly, this study was conducted to develop an environment-friendly rice production system by using Amo known as EM(effective microorganisms) and also known as being effective in environment-friendly rice production with several other environment-friendly agricultural materials. The highest number of tillers per hill was obtained from level 2 of EM treatment (48.8 tillers per hill), while the lowest was obtained from the control plot (41.0 tillers per hill). Leaf area per hill at heading stage was the highest in level 3 of EM treatment (3228.5㎠), while control was the lowest leaf area (2264.7㎠), which is 70.2% compared to the level 3 of EM treatment. The highest effective tillers was obtained from the control (63.7%), while the lowest effective tillers was obtained from the level 3 of EM treatment (55.4%), which were treated with higher amounts of environment-friendly agricultural materials. Level 3 of EM treatment showed the highest number of panicles per hill (20.9), while the control showed the lowest number of panicles per hill (19.3). In the spikelets per panicle, level 2 of EM treatment showed the highest number of spikelets (85.2), while the control showed the lowest number of spikelets (81.9) and there was a statistically significant difference among the three levels and control. The highest grain filling ratio was obtained from the control (85.0%), while level 3 of EM treatment was the lowest grain filling ratio and there were no great difference between treatment levels. Regarding the 1000 grain weight, the control showed the highest 1000 grain weight (21.7g), which is heavier by about 1g compared to treatment levels. Level 2 of EM treatment showed the highest rough rice yield per 10a, while level 3 of EM treatment was the lowest and they also showed a statistically significant difference among treatment levels.