• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.1675-1680
• /
• 2000

Recently the uncertainty has been made rapid progress in various fields of industry but the uncertainty measurement method of acoustical test (i.e. Insertion loss, Absorption ratio, Transmission loss etc,) hasn't been established. In this study, the uncertainty of measurement method for ducted silencers is carried out according to ISO 7235. The standard uncertainty factors are composed of sound pressure level, microphone sensitivity and pistonphone calibration in this measurement. Sound pressure level is type A evaluation of uncertainty, microphone sensitivity and pistonphone calibration are type B evaluation of uncertainty. The combined standard uncertainty is calculated by two type evaluation. The expanded uncertainty is expressed by the combined standard uncertainty multiply k value which is yield the effective degree of freedom.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2017년도 9th Asian Crop Science Association conference
• /
• pp.197-197
• /
• 2017

In order to reduce the loss of perilla seeds at harvesting stage, different seeding methods and harvesting time had been applied to upland soil in NICS (National Institute of Crop Science), RDA, Milyang, Korea. The seeding methods were divided into hill and drill seeding, and harvesting time were 40%, 60%, 80%, and 100% color-changing of top cluster perilla (cv Deulsaem) seeds. Higher plant height and lowest flower cluster, thinner culm thickness was observed in drill seeding treated plot than hill seeding treated plot. However, field lodging occurred lower at drill seeding treatment (lodging degree 3) than hill seeding plot (lodging degree 5). Harvesting time affected the loss of perilla seeds and the loss rate of perilla seeds were investigated at different color-changing of top flower cluster. When seeds were harvested at 40%, 60%, 80%, and 100% color-changing of top cluster perilla seeds, the loss rate of hill and drill seeding showed no significant differences however the loss rated of 40, 60, 80, and 100 % color-changing of top flower cluster were 1.9% to 3.0%, 3.8% to 3.9%, 8.0% to 10.2%, and 16.1% to 22.7%, respectively. The harvesting time had no significant effects on the yield of perilla seeds. These results suggest that optimum harvesting time of perilla could be recommend at the 60% color-changing of top cluster to reduce the loss of perilla seeds.

• 대한토목학회논문집
• /
• 제35권1호
• /
• pp.111-117
• /
• 2015

본 연구에서는 강우의 공간분포에 따른 토사유출의 특성을 토조 실험을 통해 탐구하였다. 강우의 공간분포는 강우 집중위치를 사면의 중앙부와 상류부로 각각 설정함으로 조정하였다. 토사유출의 시간적 변동성을 충분히 포착하기 위해 장시간(8 시간)의 실험시간 동안 높은 시간해상도(10 분)로 직접유출량, 지하수유출량, 토사유출량을 측정하였다. 그 결과, 강우를 토조의 상류부에 위치시킬수록 토사유출량곡선의 첨둣값은 감소하고 누적토사유출량은 증가하였다. 누적토사유출량은 시간에 따라 선형적으로 증가하였으나, 그 증가율이 2 시간을 기준으로 급격히 감소하였다. 이러한 점은 현재 총량 위주로 기록되어있는 토사유출 실측자료를 사용함에 있어 고려해야 할 사항이라고 결론지을 수 있다. 본 연구 결과는 또한, 향후의 토사유출량 실측은 높은 시간해상도로 측정될 필요가 있음을 시사한다.

• 한국작물학회지
• /
• 제44권4호
• /
• pp.330-338
• /
• 1999

Extensive research has been conducted on effects of drought stress on growth and development of soybean but information is rather restricted on the limited-irrigation system by way of precaution against a long-term drought condition in the future. The experiment for limited-irrigation was conducted in transparent vinyl shelter at Asian Vegetable Research and Development Center (AVRDC), Taiwan in 1997. Two soybean varieties, Hwangkeum and AGS292, improved in Korea and AVRDC, respectively were used for this experiment. The relationships between normalized transpiration rate (NTR) and fraction of transpirable soil water (FTSW) in both varieties were similar that the NTR was unchanged until FTSW dropped to about 0.5 or 0.6. At FTSW less than those values, NTR declined rapidly. Days required to harvest in both varieties were significantly prolonged at IR6 treatment compared to any other treatments. Daily mean transpiration rate was significantly higher at IR5 treatment, as averaged over varieties. Similarly, water use efficiency was also high at 1R5 treatment. In both varieties, seed yield was the greatest at the IR5 treatment, as compared to any other limited-irrigation treatments, due to the increased seed number and high transpirational water use efficiency. The indices of input water and seed yield for the different limited-irrigation treatments against control indicated that Hwangkeum produced 59.6% or 60.7% of seed yield using 36.1% or 44.9% of input water, as compared to control, by irrigation at only R5 or R6 stages, respectively. The AGS292 produced 56.1% of seed yield with 35.4% of input water of control, when irrigated at R5 stage. The results of this study have elucidated that the limited irrigation at R5 stage in soybean can be minimized yield loss with such small quantity of water under the environment of long-term drought stress and the expected shortage of agricultural water in the future.

• 식물병연구
• /
• 제13권1호
• /
• pp.20-23
• /
• 2007

2002년부터 2005년까지 4년간 벼 흰잎마름병 초발병 조사결과 2002년보다 초발병일이 20$\sim$30일 이상 빨라지고 있음을 확인하였다. 벼 흰잎마름병 발병시기 및 병반면적율에 따라 수량이 감소하였는데 병반면적률이 10% 이하에서는 피해가 적었으나, 병반적율이 증가함에 따라서 수량감소가 점점 많아졌고, 25% 이상일 때부터 수량감소 및 현미천립중 등에서 현저히 낮아지고 병반면적율이 50% 이상이고 유수형성기 발병시 수량 29%, 현미천립중 2.3g, 현미완전립률 18%까지 감소되었다. 밥맛의 기준이 되는 식미치인 점도에서도 병반면적율이 증가함에 따라 낮은 식미치를 보였다.

• 농업과학연구
• /
• 제13권1호
• /
• pp.33-43
• /
• 1986

다년간(多年間) 동일(同一) 비료(肥料)를 시용(施用)한 논에서 시비조건(施肥條件)의 차이(差異)가 토양(土壤)의 특성(特性)에 미치는 영향(影響)을 구명(究明)함과 아울러 수도(水稻)의 반응(反應)올 형태(形態), 생리(生理), 생육면(生育面)으로 분석검토(分析檢討)하였던 바 다음과 같은 결과(結果)를 얻었다. 1. 무비구(無肥區)와 무질소구(無窒素區)에서는 엽면적(葉面積)과 평균(平均) 생장속도(生長速度)의 감소(減少), 출수지연(出穗遲延), 수수(穗數)와 단위영화수(單位潁花數)의 감소(減少)로 3 요소구(要素區)에 비(比)하여 수량(收量)이 각각(各各) 43%와 53%정도(程度) 감소(減少)되었다. 2. 무인산구(無燐酸區)에서는 토양(土壤) 및 도체(稻體)의 인산함량(燐酸含量)이 낮았으나 그 결핍증상(缺乏症狀)이 나타날 정도(程度)는 아니었으며 수량(收量) 감수(減收)도 적었다. 3. 무가리구(無加里區)에서는 토양(土壤) 및 도체(稻體)의 가리함량(加里含量이 크게 떨어졌으며 1 수영화수(穗潁花數)의 감소(減少)로 삼요소구(三要素區)에 비(比)하여 약(約) 9%의 수량(收量) 감수(減收)가 있었다. 4. 삼요소(三要素)+퇴비시용구(堆肥施用區)에서는 토양중(土樓中)의 유효인산(有效燐酸), 치환성가리(置換性加里) 및 규산함량(珪酸含量)이 높았으며 도체내질소(稻體內窒素), 인산(燐酸), 가리(加里) 및 규산(珪酸)의 흡수량(吸收量)이 증대(增大)되고 단위영화수(單位潁花數)와 수수(穗數) 증가(增加)로 삼요소(三要素) 시용구(施用區)보다 6~9% 증수(增收)되었다. 5. 퇴비시용구(堆肥施用區)는 질소(窒素), 인산(燐酸)의 흡수량(吸收量) 감소(減少)와 영양생장부진(營養生長不振), 수수(穗數) 및 영화수(潁花數) 감소(減少)로 과실(結實)의 양호(良好)에도 불구(不拘)하고 삼요소구(三要素區)보다 수량(收量)이 약(約) 30% 감소(減少)되었으나 무비료(無肥料)보다는 28%의 증수효과(增收效果)가 인정(認定)되었다.

• 한국물환경학회지
• /
• 제23권4호
• /
• pp.518-526
• /
• 2007

There have been serious soil erosion and water pollution problems caused by highland agriculture practices at Doam-dam watershed. Especially agricultural activities, chemical and organic fertilizer and pesticide applications, soil reconditioning to maintain soil fertility are known as primary causes of soil erosion and water qaulity degradation in the receiving water bodies. Among these, soil reconditioning can accelerate soil erosion rates. To develop soil erosion prevention practices, it is necessary to estimate the soil erosion from the watershed. Thus, the Universal Soil Loss Equation (USLE) model has been developed and utilized to assess soil erosion. However, the USLE model cannot be used at watershed scale because it does not consider sediment delivery ratio (SDR) for watershed application. For this reason, the Sediment Assessment Tool for Effective Erosion Control (SA TEEC) was developed to assess the sediment yield at any point in the watershed. The USLE-based SA TEEC system can estimate the SDR using area-based SDR and slope-based SDR module. In this study, the SATEEC system was used to estimate soil erosion and sediment yield at the Doam-dam watershed using the soil properties from reconditioned agricultural fields. Based on the soil sampling and analysis, the US LE K factor was calculated and used in the SA TEEC system to analyze the possible errors of previous USLE application studies using soil properties from the digital soil map, and compared with that using soil properties obtained in this study. The estimated soil erosion at the Doam-dam watershed without using soil properties obtained in the soil sampling and analysis is 1,791,400 ton/year (123 ton/ha/year), while the soil erosion amount is 2,429,900 ton/year (166.8 ton/ha/year) with the use of soil properties from the soil sampling and analysis. There is 35 % increase in estimated soil erosion and sediment yield with the use of soil properties from soil reconditioned agricultural fields. Since significant amount of soil erosion are known to be occurring from the agricultural fields, the soil erosion and sediment yield from only agricultural fields was assessed. The soil erosion rate is 45.9 ton/ha/year without considering soil properties from soil reconditioned agricultural fields, while 105.3 ton/ha/year after considering soil properties obtained in this study, increased in 129%. This study shows that it is very important to use correct soil properties to assess soil erosion and sediment yield simulation. It is recommended that further studies are needed to develop environment friendly soil reconditioning method should be developed and implemented to decrease the speed of soil erosion rates and water quality degradation.

• Weed & Turfgrass Science
• /
• 제1권4호
• /
• pp.31-37
• /
• 2012

담수직파재배에서 사마귀풀과 자귀풀 경합밀도에 따른 벼 수량감소 정도를 예측하고 제초제 사용여부 결정을 위한 경제적 방제수준을 설정하여 저투입, 친환경적인 정밀 잡초관리 체계를 확립하고자 시험을 수행하여 얻어진 결과는 다음과 같다. 쌀수량 감소정도는 사마귀풀의 경우 경합밀도가 $m^2$당 8본일 때 8%, 96본일 때 45% 이었고 자귀풀의 경우 $m^2$당 8본일 때 20%, 96본일 때 77% 이었다. 벼와 잡초의 경합에 따른 쌀수량 예측모델은 사마귀풀의 경우 Y=553.2 kg/(1+0.00913X) $R^2$=0.912 이었고 자귀풀의 경우 Y=567.9 kg/(1+0.04434X) $R^2$=0.961 이었다. 초종별 경제적 방제수준은 사마귀풀의 경우 $m^2$당 3.0본 이었고, 자귀풀의 경우 $m^2$당 0.6본 이었다.

• 신재생에너지
• /
• 제7권3호
• /
• pp.6-16
• /
• 2011

In order to study the utilization of seaweeds as an alternative renewable feedstock for bioethanol production, their properties of hydrolysis and fermentation were investigated. The seaweeds were well hydrolyzed with diluted sulfuric acid. The weight loss of seaweeds reached 75-90%, but only 12-51% of them was converted into reducing sugars after the acid-hydrolysis at $130^{\circ}C$ for 4-6h. The yield of reducing sugars increased with increasing the hydrolysis time up to 4h and then decreased thereafter. In contrast, the ethanol yield from the hydrolysates increased with hydrolysis time except for green seaweeds maximizing at 4h. Optimal fermentation time by Saccharomyces cerevisiae (ATCC 24858) varied with seaweeds; 48h for green seaweeds, 96h for brown and red seaweeds. The ethanol yield from the hydrolysate reached 138${\pm}$37mg/g-dry for green seaweeds, 258${\pm}$29mg/g-dry for brown seaweeds, and 343${\pm}$53mg/g-dry for red seaweeds, which correspond to approximately 1.5-4.0 times more than the theoretical yield from total reducing sugars in the hydrolysates. The results obtained indicate clearly that the non-reducing sugars or oligosaccharides dissolved in the hydrolysate played an important role in producing bioethanol. Considering the productivity and production cost of each seaweed, brown seaweeds such as Laminaria japonica and Undaria pinnatifida seem to be a promissing feedstock for bioethanol production.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2009년도 학술발표회 초록집
• /
• pp.693-697
• /
• 2009

Physically-based WEPP watershed version was applied to a watershed, located at Jawoon-ri, Gangwon with very detailed rainfall data, rather than daily rainfall data. Then it was validated with measured sediment data collected at the sediment settling ponds and through overland flow. The $R^2$ and the EI for runoff comparisons were 0.88 and 0.91, respectively. For sediment comparisons, the $R^2$ and the EI values were 0.95 and 0.91. Since the WEPP provides higher accuracies in predicting runoff and sediment yield from the study watershed, various slope scenarios (2%, 3%, 5.5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%) were made and simulated sediment yield values were analyzed to develop appropriate soil erosion management practices. It was found that soil erosion increase linearly with increase in slope of the field in the watershed. However, the soil erosion increases dramatically with the slope of 20% or higher. Therefore special care should be taken for the agricultural field with higher slope of 20% or higher. As shown in this study, the WEPP watershed version is suitable model to predict soil erosion where torrential rainfall events are causing significant amount of soil loss from the field and it can also be used to develop site-specific best management practices.