• 한국환경복원기술학회지
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• 제20권2호
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• pp.79-91
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• 2017

This study was conducted to find out the physical properties and soil shearing strength reinforcement effect of herbaceous plants for the slope revegetation works. Two native plants(Pennisetum alopecuroides and Miscanthus sinensis) were used for this experiment, because they have excellent seed germination rates without preconditioning, and grow naturally around rivers. To identify the physical properties, the partial dry weight of plants were investigated. To identify the soil shearing strength reinforcement effect, the respective soil shearing strengths of the control soils, Pennisetum alopecuroides, Miscanthus sinensis samples were measured. Also, we did a correlation analysis to examine the relation of shearing strength to plant features. The results are summarized as follows: 1. The average dry weight of Pennisetum alopecuroides samples consists of 52.36% above ground and 47.64% at root. And in dry weight, 78.24% of it's root distributes within 10 cm in soil depth. Meanwhile the average dry weight of Miscanthus sinensis samples consists of 52.91% above ground and 47.09% at root. And in dry weight, 82.95% of it's root distributes within 10 cm in soil depth. 2. The results of correlation analysis showed that for both Pennisetum alopecuroides and Miscanthus sinensis, it could not be said that there was any correlation between shearing strength and plant characteristics, and statistically they were not meaningful. 3. In the shearing strength test with control soils, Pennisetum alopecuroides, Miscanthus sinensis as subjects, the differences in shearing strength measurement results were modest, and the order was shown as control soils < Pennisetum alopecuroides < Miscanthus sinensis, so the soil shearing strength reinforcement effect by the Pennisetum alopecuroides and the Miscanthus sinensis on loamy sand at river banks surface was confirmed.

• 한국농공학회지
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• 제31권3호
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• pp.41-56
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• 1989

The purpose of this study is to find out the basic data for irrigation plans of garlic and cucumber during the growing period, such as total amount of evapotranspiration, coefficients of evapotranspiration at each growth stage, the peak stage of evapotranspiration and the maximum evapotranspiraton, optimum irrigation point, total readily available moisture, and intervals of irrigation date. The plots of experiment were arranged with split plot design which were composed of two factors, irrigation point for main plot and soil texture for split plot, and three levels ; irrigation points with pP 1.7-2.1, pP 2.2-2.5, pP 2.6-2.8, for garlic and those with pP 1.9, pF 2.3, pP 2.7, for cucumber, soil textures of silty clay, sandy loam and sandy soil for both garlic and cucumber, with two replications. The results obtained are summarized as follows 1.There was the highest significant correlation between the avapotranspiration of garlic and cucumber and the pan evaporation, beyond all other meteorological factors considered, as mentioned in the previous paper. Therefore, the pan evaporation is enough to be used as a meteorological index measuring the quantity of evapotranspiration. 2.1/10 probability values of maximum total pan evaporation during growing period for garlic and cucumber were shown as 495.8mm and 406.8mm, respectively, and those of maximum ten day pan evaporation for garlic and cucumber, 63.8mm and 69.7mm, respectively. 3.The time that annual maximum of ten day pan evaporation can be occurred, exists at any stage between the middle of May and the late of June(harvest period) for garlic, and at any stage of growing period for cucumber. 4.The magnitude of evapotranspiration and of its coefficient for garlic and cucumber was occurred in the order of pF 1.7-2.1>pF 2.2-2.5>pF 2.6-2.8 and of pF 1.9>pF 2.3>pF2.7 respectively in aspect of irrigation point and of sandy loam>silty clay>sandy soil in aspect of soil texture for both garlic and cucumber. 5.The magnitude of leaf area index was shown in the order of pF 2.2-2.5>pF 1.7-2.1>pF 2.6-2.8 for garlic and of pF 1.9>pF 2.3>pF 2.7 for cucumber in aspect of irrigation point, and of sandy loam>sandy soil>silty clay in aspect of soil texture for both garlic and cucumber. 6.1/10 probability value of evapotranspiration and its coefficient during the growing period for garlic were shown as 391.7mm and 0.79 respectively, while those of cucumber, 423.lmm and 1.04 respectively. 7.The time the maximum evapotranspiration of garlic can be occurred is at the date of thirtieth before harvest period and the time for cucumber is presumed to be at the date of sixtieth to seventieth after transplanting, At that time, 1/10 probability value of ten day evapotranspiration and its coefficient for garlic is presumed to be 65.lmm and 1.02 respectively, while those of cucumber, 94.8mm and 1.36 respectively. 8.In aspect of irrigation point, the weight of raw garlic and cucumber were increased in the order of pF 2.2-2.5>pF 1.7-2.1>pF 2.6-2.8 and of pF 1.9>pF 2.3>pF 2.7 respectively. Therefore, optimum irrigation point for garlic and cucumber is presumed to be pF 2.2-2.5 and pF 1.9 respectively, when the significance of yield between the different irrigation treatments is considered. 9.Except the mulching period of garlic that soil moisture extraction patterns were about the same, those of garlic and cucumber have shown that maximum extraction rate exists at 7cm deep layer at the beginning stage after removing mulching for garlic and at the beginning stage of growth for cucumber and that extraction rates of 21cm to 35cm deep layer are increased as getting closer to the late stage of growth. 10.Total readily available moisture of garlic in silty clay, sandy loam, sandy soil become to be 18.71-24.96mm, 19.08-25.43mm, 10.35- 13.80mm respctively on the basis of the optimum irrigation point with pF 2.2-2.5, while that of cucumber, 11.8lmm, 12.03mm, 6.39mm respectively on the basis of the optimum irrigation point with pF 1.9. 11.The intervals of irrigation date of garlic and cucumber at the growth stage of maximum consumptive use become to be about three and a half days and one and a half days respectively, on the basis of each optimum irrgation point.

• Asian-Australasian Journal of Animal Sciences
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• 제19권1호
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• pp.31-34
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• 2006

The experiment was conducted to determine the effects of cutting interval and cutting height on the yield and nutrient composition of hedge lucerne (Desmanthus virgatus) when grown on a sandy soil in the Northeast of Thailand. The cutting intervals compared were 30, 40 and 50 days between harvests and the cutting heights 30, 40 and 50 cm above ground level. The experiment was a $3{\times}3$ factorial layout in a randomized complete block design with 4 replications-giving a total of 36 plots each $3{\times}3m^2$. Harvested plant material was weighed, dried and the ground subsamples taken for analyses of crude protein (CP), crude fiber (CF), ash, ether extract (EE) and nitrogen-free extract (NFE). At the last harvest the hedge lucerne samples were separated to determine leaf to stem ratios and then analyzed for nutrient composition in the leaf and stem. Results showed that increasing the cutting interval (i.e. advancing age of maturity) increased dry matter and nutrient yields significantly. In terms of nutrient content, it also increased the crude fiber, ash, ether extract and nitrogen free extract percent in the plant. However, crude protein percent was markedly decreased as the cutting interval increased. Increasing cutting height had no effect on dry matter yield and yields of nutrients, but in terms of nutrient content, it increased crude protein and ash content, but decreased crude fiber content. The percent EE and NFE in the plant was unaffected by cutting height. From the results presented it is clear that cutting a stand of hedge lucerne every 40 to 50 days will achieve greater dry matter and nutrient yields than cutting more frequently, at 30 days. The cutting height at harvest, whether 30, 40 or 50 cm above ground level had no effect on dry matter or nutrient yields of hedge Lucerne. Hedge lucerne therefore offers the Thai poultry farmer a useful alternative protein supplement for poultry diets rather than relying on the more expensive soybean meal. As it can be readily and successfully grown on a range of soil types and climates throughout Thailand, hedge lucerne also offers the Thai farmer a valuable additional source of income.

• 한국토양비료학회지
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• 제33권3호
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• pp.182-192
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• 2000

본 연구는 밭토양에서 종류가 상이한 퇴비시용 시 퇴비시용 한계량을 구명하기 위하여 수행하였다. 공시토양은 양토와 사양토를 사용하였고, 시험에 사용한 퇴비의 종류는 계분퇴비, 우분퇴비, 분뇨잔사 및 식품오니퇴비 이었다. 퇴비 시용량은 0, 40, $80Mg\;ha^{-1}$ 수준이었고, 공시작물은 콩과 옥수수로서 1994년부터 1997년도까지 4년간 연작을 하였으며 주요 연구결과를 요약하면 다음과 같다. 옥수수의 건물생산량은 퇴비 시용량이 증가될수록 증가되었으나 콩은 퇴비 $60Mg\;ha^{-1}$ 시용까지는 증가되다가 그 이상은 감소되었다. 질소와 인산 이용율은 옥수수가 콩보다 많았으며, 질소 이용율은 옥수수가 21~31%, 콩은 8~19%였고, 인산 이용율은 옥수수와 콩이 각각 5~7%. 1~2%로 낮은 편이었다. Biomass기준 계분퇴비 시용 한계량은 옥수수재배시는 $39{\sim}47Mg\;ha^{-1}$ 콩 재배시는 $8{\sim}13Mg\;ha^{-1}$범위 이었다. 작물의 질소 요구량을 기준으로 하였을 경우는 옥수수 $123Mg\;ha^{-1}$, 콩은 $87Mg\;ha^{-1}$였고, 인산기준으로는 옥수수 $29Mg\;ha^{-1}$ 콩은 $14Mg\;ha^{-1}$범위였다. 토양의 염기포화도 80%를 한계수준으로 평가한 토성별 퇴비시용 한계량은 옥수수재배시 양토는 $69{\sim}93Mg\;ha^{-1}$, 사양토는 $49{\sim}69Mg\;ha^{-1}$범위이었다.

• 지질공학
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• 제31권3호
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• pp.333-342
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• 2021

본 연구에서는 기존의 전통적인 다짐관리방법의 문제점을 보완하고자 TDR(Time Domain Reflectometry)을 이용하여 지반의 함수비와 건조단위중량을 측정하는 연구를 수행하였다. Flat TDR 시스템은 지반의 교란을 일으키기 않는 장비로써 측정값을 검증하기 위하여 주문진표준사 외 7개소의 현장대상 지반의 시료에 대하여 건조밀도와 함수비를 측정하였다. 함수비구간은 3, 6, 9, 12, 15, 18%의 6개 구간으로 나누어 측정을 하였으며 실험결과는 통일분류법에 따라 확인하였다. 실내실험 결과, 함수비는 SP시료의 경우 약 0.7%, SM시료의 경우 약 1.3%의 오차를 보였다. 또한 건조단위중량은 SP시료의 경우 약 7%, SM시료의 경우 약 5%의 오차를 확인하였다. 이는 점토나 자갈을 제외한 모래 또는 실트질 모래 지반에서는 안정적인 값을 도출함을 확인할 수 있었다. 실험 결과를 통하여 Flat TDR 시스템의 측정값이 기존의 전통적인 다짐관리방법과 유사한 값을 도출하는 것을 확인할 수 있었고 이는 빠른 시공성과 경제성을 필요로하는 건설현장에서 Flat TDR 장비가 적합하다는 것을 판단할 수 있었다.

• 한국패류학회지
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• 제29권4호
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• pp.291-301
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• 2013

This study researched and compared the sedimentation environment and photosynthetic pigments at Gomso (GS) -bay, Yoja (YJ) -bay and KangJin (KJ) -bay in May, 2012. It was shown that KJ-bay consist of C (clay) and M (mud), and GS-bay consists of Zs (silty sand) and Sz (sandy silt). Averagely, IL of YJ-bay was 4.98%, KJ-bay 6.10%, and GS-bay 1.45%. As for COD concentration, there were no places that exceeded Japanese sediment contamination standard 20 mg/g-dry. As for AVS concentration, in case of KJ-bay, two places exceeded Japanese sediment contamination standard 0.2 mg/g-dry. If we look into the average C/N ratio of bays, YJ-bay showed 8.50, KJ-bay 6.60, and GS-bay 5.52, thus all of them showed the characteristic of oceanic origin. As for the plankton make-up classified by photosynthetic pigments, diatom was dominant, and both ratios of pigment and C/chlorophyll. a showed the relatively lower distribution at GS-bay than at KJ-bay and YJ-bay. It is judged that this is related to the characteristic of flow-in, and it implies that predation process and decomposition by organic matters actively occurs at YJ-bay and KJ-bay.

• 한국제4기학회지
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• 제19권2호
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• pp.55-58
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• 2005

A 120-cm core recovered from Lake Hovsgol, the northern Mongolia provides evidence for climate variability since the Marine Isotope Stage 3, representing a sharp lithological change. The lowermost part of the core consists of diatom-barren calcareous silty clay without coarse sands, framboidal pyrite, and biogenic components deposited during the MIS 3. Following the last glacial maximum, in-situ moss is included in the sediments, as lake-level was retreated by cold and dry environment with low precipitation. The AMS radiocarbon ages of the plant fragments match a marked lithologic boundary between 14,060 and 14,325 $^{14}C$ yr BP. The contents of coarse sands abruptly increase, indicating probably wind-derived sandy dust or coarse grains contributed from floating icebergs. And abundant framboidal pyrite grains were deposited in an anoxic environment, as reflected by high accumulation of organic matters at a low lake stand. During the deglaciation, quantities of coarse sands, ostracod, shell fragments, framboidal pyrite, and diatom markedly varies by regional and global scale climate regimes. Some allochthonous coarse sands were probably ice-rafted debris derived from floating icebergs. A rapid increase in diatom productivity probably marked the onset of Bolling-Allerod warming. Subsequent high concentration of framboidal pyrite probably represents a dry and cold condition, such as Younger Drays events. Consistent warm period with high precipitation at Holocene is documented by diatomaceous clayey ooze without framboidal pyrite, coarse sands, and ostracod.

• 한국환경농학회지
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• 제5권2호
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• pp.135-140
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• 1986

K-bentonite를 K포화용액에서 이온교환법에 의해 제조했다. 모래땅, 황토, 산흙에서 K-bentonite 완효성의 효과를 비교 시험했는데, 특히 모래땅에서 그 효과가 컸다. 알타리무우 및 상치를 이용한 모래땅 재배에서 KCl시용구. 보다 K-bentonite구는 상치의 지상부의 생육과 알타리무우의 근부신장을 월등히 촉진 시켰다. 그러나 적정량을 관수하면서 모래, 산흙, 황토를 이용한 온실내 pot시험에서는 생육차를 발견할 수 없었다. K-bentonite는 무우 및 상치의 Vitamin C, Nitrate, Thiocyanate, Dry wt 등의 함량변화에 영향을 미치지 않았다. K-bentonite 실제 생산에 있어 문제점에 대해 논의하였다.

• 한국제4기학회:학술대회논문집
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• 한국제4기학회 2005년도 추계학술대회
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• pp.34-39
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• 2005

A 120-cm core recovered from Lake Hovsgol, the northern Mongolia provides evidence for climate variability since the Marine Isotope Stage 3, representing a sharp lithological change. The lowermost part of the core consists of diatom-barren calcareous silty clay without coarse sands, framboidal pyrite, and biogenic components deposited during the MIS 3. Following the last glacial maximum, in-situ moss is included in the sediments, as lake-level was retreated by cold and dry environment with low precipitation. The AMS radiocarbon ages of the plant fragments match a marked lithologic boundary between 14,060 and 14,325 $^{14}C$ yr BP. The contents of coarse sands abruptly increase, indicating probably wind-derived sandy dust or coarse grains contributed from floating icebergs. And abundant framboidal pyrite grains were deposited in an anoxic environment, as reflected by high accumulation of organic matters at a low lake stand. During the deglaciation, quantities of coarse sands, ostracod, shell fragments, framboidal pyrite, and diatom markedly varies by regional and global scale climate regimes. Some allochthonous coarse sands were probably ice-rafted debris derived from floating icebergs. A rapid increase in diatom productivity probably marked the onset of Bolling-Allerodwarming. Subsequent high concentration of framboidal pyrite probably represents a dry and cold condition, such as Younger Drays events. Consistent warm period with high precipitation at Holocene is documented by diatomaceous clayey ooze without framboidal pyrite, coarse sands, and ostracod.

• 한국기계가공학회지
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• 제18권6호
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• pp.9-18
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• 2019

This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of $4.14{\times}10^{-5}$. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.