With rising concerns about pesticide spray drift by aerial application, this study attempt to evaluate aerodynamic property and collection efficiency of spray drift according to the leaf area index (LAI) of crop for preventing undesirable pesticide contamination by the spray-drift tunnel experiment. The collection efficiency of the plant with ‘Low’ LAI was measured at 16.13% at a wind speed of 1 m·s-1. As the wind speed increased to 2 m·s-1, the collection efficiency of plant with the same LAI level increased 1.80 times higher to 29.06%. For the ‘Medium’ level LAI, the collection efficiency was 24.42% and 43.06% at wind speed of 1 m·s-1 and 2 m·s-1, respectively. For the ‘High’ level LAI, it also increased 1.24 times higher as the wind speed increased. The measured results indicated that the collection of spray droplets by leaves were increased with LAI and wind speed. This also implied that dense leaves would have more advantages for preventing the drift of airborne spray droplets. Aerodynamic properties also tended to increase as the LAI increased, and the regression analysis of quadric equation and power law equation showed high explanatory of 0.96－0.99.

한국의 전통 과자인 유과는 거의 모든 공정이 수작업으로 제조되기 때문에 공정 중 작업자 및 작업도구 등에 의한 교차오염으로 인한 안전문제가 제기되고 있다. 본 연구에서는 유과 제조 공정 중 찹쌀의 불림 단계에서 증가된 미생물을 제어하기 위하여 항균 활성이 있는 용액 9가지 용액(40% 자몽종자 추출물, 100% 계피 추출물, 70% 에탄올, 100% 식초, 0.2% 차아염소산나트륨, 40% 초산나트륨, 40% 탄산수소나트륨, 40% 사과산, 40% 구연산)을 이용하여 Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Bacillus cereus에 대해 항균 효과를 비교 확인하였다. Disk diffusion법을 통해 40% 사과산과 구연산에서 높은 항균 효과를 확인할 수 있었고, 추가로 항균용액의 농도, 처리방법 및 시간을 최적화한 결과 1% 사과산-구연산을 10분 동안 처리 시 세균 5종을 모두 사멸시켜 높은 항균효과를 확인할 수 있었다. 불림단계의 찹쌀에 1% 사과산-구연산으로 정치 및 교반하면서 10분 동안 세척하였을 때 일반세균과 대장균군의 수가 각각 4.0 Log CFU/g와 5.0 Log CFU/g씩 감소하였다. 이상의 결과로 볼 때 1% 사과산-구연산으로 불린 찹쌀에 대해 침지와 교반으로 10분 동안 처리함으로써 전통 유과 제조과정 중 쌀의 불림단계에서 증가된 미생물을 효과적으로 저감화 할 수 있음을 확인하였다.

PURPOSES : This study describes the experimental findings on the mechanical properties of calcium aluminate cement (CAC)-based repair mortars with or without natural cellulose fiber (NCF). Additionally, the effect of adding NCF to the reduction of fugitive dust in the CAC powder was examined. METHODS : To produce mortar, four different levels of NCF (0.0.5, 1.0, and 2.0% by binder weight) were adopted, and the water-binder ratio was fixed at 0.485. The flow, strength characteristics, absorption, and surface electrical resistivity of the mortars were measured at predetermined periods. Additionally, SEM observations were performed to examine the microstructural changes and hydrates formed on the 28 day-mortar samples. RESULTS : The addition of NCF led to a decrease in fugitive dust. Regarding the mechanical properties of the mortars, that with 0.5% NCF exhibited a better performance in terms of strength development and surface electric resistivity compared to those of other mortars. However, the addition of NCF was less effective in the enhancement of the absorption of mortars. Further, we discovered that the microstructures of the mortars with additional NCF were comparatively dense compared to those without NCF. CONCLUSIONS : The appropriate addition of NCF can enhance the performance of CAC-based repair materials. However, further studies on the durability of CAC with the addition of NCF are needed to determine the optimal mixture.

선박용 엔진에서 배출되는 배기가스에는 다량의 수분과 미세먼지를 포함하고 있다. 미세먼지에는 여과성 미세먼지와 배기 배 출 후 액상으로 변화하는 응축성 미세먼지가 포함되어 있으며 배출 전에 걸러지는 고체상 미세먼지보다 응축성 미세먼지가 더 많은 것으 로 보고되고 있다. 본 연구에서는 배기가스의 배기열과 수분을 회수하고 응축성 미세먼지를 제거하기 위한 실험장치를 실험실 내의 가스 보일러 배기가스를 이용하여 테스트 하였다. 배기가스는 1차적으로 냉각방식으로 수분과 응축성 미세먼지가 제거되고 2차적으로 흡수제 방식에 의해 추가적으로 수분이 제거되었다. 상대습도 측정에 의한 배기가스 수분 제거율을 계산하면 1단계 배기냉각 방식으로 73%, 2단 계 흡수제 방식으로 90% 제거되는 것으로 측정되었다. 이 과정에서 응축성 미세먼지는 80~90% 제거되는 것으로 측정되었다. 개발 시스템 에 의해 회수된 열은 공정열로 활용할 수 있으며, 회수된 물은 수처리 과정을 통해 공정수로 활용할 수 있다. 또한 현재 관리 규제가 되고 있지 않지만 미세먼지의 주요 원인인 응축성 미세먼지를 효과적으로 제거할 수 있을 것으로 기대된다.

선택적 촉매 환원법(SCR)은 질소산화물(NOx)을 저감하는 매우 효율적인 방법으로 알려져 있으며 발생된 질소산화물(NOx)을 질 소(N2)와 수증기(H2O)로 환원시키는데 촉매 작용을 한다. 질소산화물(NOx) 저감 성능을 결정하는 요소 중 하나인 촉매는 셀 밀도가 증가하 면 촉매효율이 증가하는 것으로 알려져 있다. 본 연구에서는 실습선 세계로호에 설치되어 있는 발전 기관의 배기가스 조건을 모사한 실 험장치를 통하여 100CPSI(60Cell)촉매의 부하에 따른 질소산화물(NOx) 저감 성능을 확인하고 세계로호에 설치되어 있는 25.8CPSI(30Cell) 촉 매의 기존 연구 자료와의 비교를 통해, 셀 밀도가 질소산화물(NOx)의 저감에 미치는 영향에 대하여 고찰하였다. 실험용 촉매는 셀 밀도만 변화를 주었고 형태는 벌집형(honeycomb), 조성물질은 V2O5-WO3-TiO2를 동일하게 사용하여 제작하였다. 실험결과 100CPSI(60Cell) 촉매의 질소산화물(NOx) 농도 저감율은 평균적으로 88.5%이며 IMO specific NOx 배출량은 0.99g/kwh로 IMO Tier III NOx 배출기준을 만족하였다. 25.8CPSI(30Cell) 촉매의 경우, 질소산화물(NOx) 농도 저감율은 78%, IMO specific NOx 배출량은 2.00g/kwh 이었다 두 촉매의 NOx 농도 저감 율과 IMO specific NOx 배출량을 비교하였을 때, 100CPSI(60Cell)촉매가 25.8CPSI(30Cell) 촉매보다, NOx 농도 저감율은 10.5% 높고 IMO specific NOx 배출량은 약 2배 적은 것을 확인하였다. 따라서 촉매의 셀 밀도를 높임으로써 효율적인 탈질효과를 기대할 수 있으며 향후 실선 테스트를 통하여 검증한다면 촉매의 부피 저감을 통한 제작 비용을 줄이고 협소한 선박 기관실을 효율적으로 사용하기 위한 실용적 인 자료로서 기대된다.

일반적으로 부유식 해상풍력발전 에너지의 수급성과 효율을 극대화하기 위해서는 하부구조물의 파랑 감쇠로 인한 운동을 저 감시키는 것이 중요하다. 선행 연구들에 따르면 파도 중 하부구조물에 설치된 감쇠판에 의해서 발생한 와류점성으로 인해 운동 응답이 감소되는 것으로 나타났다. 본 연구에서는 5MW급 반잠수식 OC5 플랫폼과 감쇠판이 부착된 두가지 플랫폼을 설계하고, 와류점성으로 인 한 운동저감효과를 확인하기 위해 자유감쇠실험과 수치계산을 수행하였다. 모형시험 결과로 낙하 높이를 30 mm, 40 mm, 50 mm에서의 상하 자유감쇠실험을 수행하였을 때 OC5 플랫폼 대비 두 가지의 형태의 감쇠판이 부착된 플랫폼이 상대적으로 운동감쇠성능이 향상되었다. 모형시험과 수치계산 결과에서 형상화한 감쇠판 모델(KSNU Plate 1, KSNU Plate 2)들이 각각 OC5 대비 상하운동 진폭이 1.1배, 1.3배 각각 감소했으며, KSNU Plate 2 플랫폼은 KSNU Plate 1 플랫폼보다 OC5 대비 약 2배 감쇠성능이 좋아진 것으로 나타났다. 본 연구에서는 감쇠 판의 면적과 와류점성이 상하동요의 감쇠율과 밀접한 관련을 보여준다.

The distance between livestock facilities and residential spaces is decreasing. Moreover, livestock odor complaints are increasing due to the large-scale and concentrated livestock breading industry. In order to reduce odor from livestock facilities, bio-curtain that are easy to install and inexpensive are commonly used in Korea. However, there is a lack of basic data on design standards and operation manuals for bio-curtains. The installation density of the bio-curtain material is an important factor that affects the odor reduction rate, increment of the load on the ventilation fans, and the structural stability of the curtain. There are limitations on deriving the design conditions of the bio-curtain by only field experiments targeting invisible air. Therefore, aerodynamic simulation such as CFD (computational fluid dynamics) can be used to obtain quantitative data according to various environmental conditions. Bio-curtain is a porous medium with a complex structure, and it is necessary to derive aerodynamic coefficients to analyze it. In this study, the wind speed and pressure difference according to the design density of the bio-curtain were monitored using the experimental chamber. Using the field results, a pressure resistance curve was created for each flow velocity and installation density. The viscosity and resistance coefficient of the bio-curtain were calculated through the derived resistance curve.

This study evaluated the odor mitigation effect of rice husk biochar addition to the bedded pack dairy barn floor using lab-scale reactors for five days. Rice husk biochar mixed with dairy manure and sawdust mixture at different ratios (5%-addition test unit: adding biochar by 5% of the total solid weight of the mixture, 10%-addition test unit: adding biochar by 10% of the total solid weight of the mixture). Cumulative NH3 and H2S emissions of 10%-addition test unit were reduced by 26% (p< 0.05) and 46% (p = 0.0655), respectively, compared with control. However, 5%-addition test unit did not show NH3 and H2S emission reduction. Further research is needed to determine the appropriate level of biochar addition between 5 and 10%, and to evaluate applicability in the field through economic analysis.

The present trial verified the effects of spraying microbial agents on odor reduction in commercial pig farms of different operating sizes and barn types. Farms without microbial agent spraying and those sprayed with microbial agents at two different intervals were compared. The treatments included spraying of water alone every day or a mixture of water plus microbial agent at 24 and 72 h intervals. The experimental farms were divided according to size into 1,000-, 3,000-, and 5,000-head farms and according to barn type into gestation, farrowing, nursery, and grower-finisher farms. To compare odor concentration within each housing barn, ammonia and hydrogen sulfide gas levels were measured. The average concentrations of ammonia (p<0.01) and hydrogen sulfide (p<0.05) gas were the lowest in all types of farms sprayed with the microbial agent at a 24 h interval. In farms sprayed with the microbial agent at a 24 h interval, the decrease in ammonia concentration according to barn type was in the following order: farrowing (p<0.01) (11.0 to 1.8 ppm), nursery (p<0.05) (17.0 to 9.2 ppm), grower-finisher (15.3 to 8.8 ppm), and gestation (9.7 to 6.4 ppm) farms. Moreover, spraying the microbial agent at a 24 h interval significantly (p<0.01) decreased ammonia concentration from 19.9 to 10.4 ppm, from 11.1 to 4.1 ppm, and from 8.8 to 5.1 ppm in 5,000-, 3,000-, and 1,000-head farms, respectively. Overall, spraying microbial agents every day may be the most effective method to reduce odor in commercial pig farms.

PURPOSES : Owing to industrial development, the occurrence of continuous environmental damage such as abnormal weather is accelerating because of a rapid increase in carbon emissions. Therefore, various efforts are expended worldwide to realize a low-carbon ecofriendly society. In the construction industry, various efforts have been realized to reduce environmental pollution such as greenhouse gas emissions, for example by introducing eco-friendly materials and reducing industrial waste. In this study, an asphalt pavement technology that can reduce production and construction temperatures by more than 60 °C is developed to reduce the amount of carbon generated in the asphalt industry. METHODS : The performance of a half-warm asphalt binder developed using thermoplastic elastomers and low-temperature additives was assessed. In addition, the change in the quality of a mixture due to the use of the half-warm asphalt binder was evaluated. RESULTS : As the amount of thermoplastic elastomer used increases, the performance grade of the asphalt binder increases as well. When 3% or more of the elastomer is incorporated, the target performance grade of the asphalt binder is satisfied. In addition, by incorporating the thermoplastic elastomer and a low-temperature additive, the overall moisture and rutting resistance increased even at relatively low production and compaction temperatures. CONCLUSIONS : Additional measures to stabilize quality and improve economic feasibility will present a new paradigm for investigations into eco-friendly asphalt concrete pavements.

PURPOSES : In this study, an eco-friendly mastic asphalt backfill material is developed to reduce production and construction temperatures by 40 ℃ compared with those recorded when using conventional hot-mix mastic asphalt backfill materials. METHODS : To reduce the production and construction temperatures, SIS polymer modifiers and gum rosin were selected, and gum rosin-modified SIS materials were applied to the mastic asphalt binder mix design. SIS is less viscous than SBS at high temperatures owing to its thermal characteristics, and incorporating gum rosin into SIS causes the latter to exhibit a loose and soft structure. To improve the performance of the mastic asphalt modified with SIS and gum rosin, three different filler mixes, i.e., 100% PMMA, 50% PMMA and 50% calcium carbonate, and 40% PMMA and 60% calcium carbonate were applied. RESULTS : The rosin-modified SIS reduces the viscosity of the developed mastic asphalt binders. In particular, incorporating 3.7% of gum rosin is beneficial to the mastic binder and does not degrade its low-temperature performance. Similarly, using 100% PMMA as a filler improves the performance but results in workability issues at high temperatures. CONCLUSIONS : Rosin-modified SIS and PMMA are promising alternatives for increasing the workability at high temperatures while maintaining the target performance of grade PG82-22 binders if the appropriate ratio of calcium carbonate is mixed with PMMA and an alternative filler comprising calcium carbonate is used.

PURPOSES : In this study, a system is investigated and developed to remove fog by injecting air onto a road using high-pressure air generated by turbo blowers installed on both edges of the road without using artificial chemicals. METHODS : A test device was constructed on a scaled road measuring 5 m long. A 225 kW class turbo blower was used to supply air. An air injection nozzle was installed to allow high-pressure air supplied from the turbo blower to be sprayed vertically from the edge of the road and horizontally from the surface of the road. Ten micro humidifiers were used to generate fog. RESULTS : Experimental results show that when ground fog occurs on the road, spraying air only in the vertical direction cannot effectively remove the fog. However, when vertical and horizontal nozzles are used simultaneously, both ground fog and flowing fog are removed effectively. CONCLUSIONS : A system for removing fog by spraying air jet is constructed, and fog is generated using a micro humidifier. Results from the fog removal performance test show that the system effectively removes fog.