• Journal of Biosystems Engineering
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• 제29권5호
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• pp.419-424
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• 2004

In this study, a series of soil bin experiment was carried out to investigate experimentally the effect of the tire inflation pressure and axle load of tire on the steering torque for the off-road condition. The experiment was performed at the three levels of off-road conditions(ground I, ground II and ground III) and on-road condition(ground IV), four levels of tire inflation pressure(120 kPa, 170 kPa, 220 kPa and 270 kPa), and four levels of axle load(1470N, 1960N, 2450N and 2940N). The results of this study are summarized as follows: 1. Steering torque at the off-road conditions were higher than that on the on-road conditions for all levels of tire inflation pressure and axle load. 2. As the axle load increased, steering torque also increased f3r all experimental ground conditions. 3. For the axle load of 1470N the biggest steering torque was measured on the ground condition I, but as the axle load increased to the value of 2940N the biggest steering torque was measured on the ground condition III. From the above results, it was found that for the low axle load, steering torque gets higher on the soft ground condition, but for the high axle load, steering torque gets higher on hard ground condition for whole range of experimental conditions. 4. As the tire inflation pressure decreased, steering torque increased on the on-road condition, but no specific trend was not found at the off-road conditions.

• 펄프종이기술
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• 제37권3호
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• pp.41-49
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• 2005

Styrofoam as shock-absorbing materials for packaging has been regarded as one of non-biodegradable products leading to soil contamination at a landfill and release of dioxine during its incineration. For avoiding severe burdens on our environments by styrofoam, it must be replaced by environment-friendly materials. In order to evaluate availability of pulp fibers as a substitute for styrofoam, various extrusion processes were applied for making optimal biodegradable products. Then thermomechanical pulp fibers made of Pinus radiata and Pinus rigida were uniformly mixed with other additives such as starch and polyvinyl alcohol prior to expansion. The physical properties of the final products were examined by measuring expansion efficiency, compression strength, and elastic modulus. Wheat starch played a key role to maintain optimal flowing conditions within the barrel of the extruder irrespective of addition of soluble starch and polyvinyl alcohol. However, as the amounts of wheat starch in raw-materials increased, the elastic modulus of the expanded materials greatly increased. High elastic modulus is not suitable as shock-absorbing products for packaging. Thus the wheat starch must be added at a minimum if possible, that is, below 20% based on oven-dried weight of pulp fibers. the elastic modulus of the expanded products was decreased as their moisture contents increased. For the products containing 20% wheat starch, the lowest elastic modulus, 844.64 kPa was obtained under 10% of the moisture content. This was similar to that of styrofoam.

• Journal of Microbiology and Biotechnology
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• 제12권3호
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• pp.476-482
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• 2002

Methanol dehydrogenase (MDH) and c-type cytochromes from marine methanol-oxidizing bacterium, Methylophaga sp. MP, were purified and characterized. The native MDH had a molecular mass of 148 kDa and its isoelectric point was 5.5. Two c-type cytochromes, $c_L\;and\;c_H$, were found, and their isoelectric points were 3.4 and 8.0, respectively. The purified MDH had higher thermal stability than that of the other soil methylotrophic bacteria. The electron flow rate from MDH to cytochrome $c_L$was higher than that from MDH to cytochrome $c_H$, indicating that the physiological primary electron acceptor for MDH is cytochrome $c_L$. The electron transfer from MDH to phenazine ethosulfate (PES, artificial electron acceptor) in the two dye (PES/DCPIP)-linked assay system was not inhibited by NaCl, whereas the electron flow from MDH to cytochrome $c_L$ in the cytochrome/DCPIP-linked assay system was suppressed significantly by NaCl. Metal chelating agents such as EDTA showed the same effects on the MDH activity.

• 대한환경공학회지
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• 제30권1호
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• pp.37-44
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• 2008

본 연구에서는 퍼클로레이트 분석에 주로 사용되고 있는 IC와 LC/MS를 사용해 퍼클로레이트 분석법을 정립하고 각 분석법의 장단점 및 효율을 파악해 수질 및 토양 시료에서의 퍼클로레이트를 모니터링 하고자 하였다. 각 분석기기를 사용한 최적분석 방법을 정립한 결과 IC에서의 MDL은 1 ppb였으며 LC-MS에서의 MDL은 0.005 ppb였다. 정립된 분석방법으로 부산시 내의 지하수 및 약수터, 하수처리장과 토양 시료를 대상으로 하여 퍼클로레이트 모니터링을 실시하여 퍼클로레이트에 대한 노출정도를 평가하였다. 평균 퍼클로레이트 농도는 약수터에서는 0.013 $\pm$ 0.014 ppb, 지하수 0.031 $\pm$ 0.011 ppb로 나타났고 하수처리장 폐수에서는 0.007$\sim$0.380 ppb의 범위로 퍼클로레이트가 검출되었다. 모든 시료에서의 퍼클로레이트 농도는 EPA 기준인 24.5 ppb 이하로 나타났다.

• Journal of Forest and Environmental Science
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• 제17권1호
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• pp.62-73
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• 2001

본 연구는 지면끌기집재에 사용되는 기계에 의해 견인되는 견인목의 견인저항을 예측하기 위해 견인목의 중량, 견인저항계수, 지면의 경사 등의 함수로 표현된 수학적 모델들을 개발하였다. 또한 만능재료시험기와 토양조를 이용한 실험실조건에서 4개 수종(잣나무, 일본잎갈나무, 신갈나무, 굴참나무)의 견인저항계수를 산출하였다. 산출한 견인저항계수와 가상 조건을 이용하여 개발된 3가지의 수학적 견인저항 모델에 적용하였다. 그 결과 견인목 중량에 대한 견인저항력의 비(T/Wt)는 지면의 경사가 증가할수록 전형적으로 증가하였으며, 반지면끌기집재가 지면끌기집재보다 견인저항력이 더 작게 나타났다. 본 연구의 결과는 집재작업기계의 선정과 집재윈치의 동력요구량 산정엔 기본적인 자료로 활용할 수 있을 것이다.

• 농업과학연구
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• 제46권4호
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• pp.781-790
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• 2019

Changes in the physical and chemical properties of soil materials during the nursing process have a great influence on the quality of containerized seedlings and on growth and survival after planting. In this study, the effect of biomaterials and their mixed ratios on the growth of Zelkova serrata seedlings in a containerized seedling production system was investigated. Mushroom sawdust, pine bark, and carbonized rice husk were used as biomaterials. The mixed ratios were 10% and 20% volume ratio of the growing medium volume, including the untreated controls. There was no significant difference in the height growth of the Zelkova serrata seedlings according to the biomaterials. The root collar diameter was the highest with the 20% carbonized rice husk and the lowest with the mushroom sawdust. The difference between the highest quality index and the lowest quality index was 30% in the order of the carbonized rice husk, pine bark, control, and mushroom sawdust, but there was no statistical significance. In this study, if the growing medium mixed with biomaterials does not reduce the seedling growth compared with the control, it is considered that the biomaterial can replace a part of the growing media. Therefore, the results show that some of the growing media can be replaced with carbonized rice husk or pine bark when producing Zelkova serrata seedlings.

• Journal of Plant Biotechnology
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• 제43권2호
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• pp.240-247
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• 2016

In this study, routinely used transformation method, which includes transferring explants onto co-cultivation medium after inoculating them with bacterial solution for a while, was compared with 3 different inoculation methods. In every 3 methods, hypocotyl explants excised from 7-day-old sterile flax seedlings having cotyledon leaves and no root system dried under air flow in sterile cabin for 35 min were inoculated with different volumes of bacterial solution at different inoculation periods. GV2260 line of Agrobacterium tumefaciens having 'pBIN 19' plasmid containing npt II (neomycin phosphotransferase II) gene and GUS reporter gene was used in transformation studies. After inoculation, hypocotyl segments of seedlings (0.5 cm in length) - were excised and left to co-cultivation for 2 days. Then, explants were transferred to regeneration medium supplemented with different antibiotics. The presence of npt-II and GUS genes in transformants was confirmed by PCR and GUS analysis. The highest results in all characters examined in all cultivars were obtained from the 2 inoculation method in which hypocotyls excised from seedlings inoculated with $500{\mu}l$ of bacterial solution after drying in sterile cabin for 35 min were used.

• Ecology and Resilient Infrastructure
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• 제3권2호
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• pp.92-99
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• 2016

본 연구는 최근 많은 관심을 받고 있는 그린인프라 및 저영향개발 (GI & LID) 기술에 대한 물순환 및 물환경 효율성 측정을 위한 실내 외 검증, 인증 시스템을 개발하였다. 기술의 검증 및 인증을 위한 실외시험시설은 건축형, 도로형, 주차장형, 빗물정원형, 생태공원형 등 크게 5구역으로 나누어 기술종류에 따라 시험이 가능하도록 시스템을 개발하였다. 또한, 실내실험으로는 수리/수문분야, 토질/지반분야, 환경분야 등 다양한 시험이 가능하도록 시험장비의 개발 및 구축을 하였다. 본 연구에서 개발한 GI & LID 검 인증시스템 구축을 위한 실내 및 실외 시험시설의 개발은 GI & LID 기술의 적용을 위한 객관적이고 신뢰성 있는 데이터 제공에 대한 기반을 마련함과 동시에 관련 사업의 활성화에 기여할 것으로 판단된다.

• Geomechanics and Engineering
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• 제23권1호
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• pp.85-92
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• 2020

This study adopted soil test and laboratory physical model experiments to simulate the tailings impoundment accumulation process according to the principle of similarity. Relying on the practical engineering, it analyzed the tailings deposition characteristics on dry beach surface during the damming process, as well as the variation rules of dam saturation line. Results suggested that, the tailings particles gradually became finer along the dry beach surface to inside the impoundment. The particle size suddenly changed at the junction between the deposited beach and the water surface, which displayed an obvious coarsening phenomenon. Besides, the deposited beach exhibited the vertical feature of coarse upward and fine downward on the whole. Additionally, in the physical model, the saturation line elevated with the increase in dam height, and its amplitude was relatively obvious within the range of 1.0-4.5 m away from the initial dam. Under flood condition, the saturation line height was higher than that under normal condition on the whole, with the maximum height difference of 4 cm. This study could provide an important theoretical basis for further studies on dam failure experiments and the evolution rules of leaked tailings flow.

• Journal of Biosystems Engineering
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• 제30권2호
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• pp.69-74
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• 2005

This study was carried out to investigate experimentally the effect of the ground condition and tire inflation pressure on rolling characteristics of towed wheel, including the deformation, sinkage, effective rolling radius and motion resistance of tire. The experiment was performed at soil bin for the three levels of off-road conditions(ground-I, ground-II and ground-III) and a on-road condition(ground-IV), and for the four levels of tire inflation pressure which were 80 kPa, 160 kPa, 240 kPa and 320 kPa. The results of this study are summarized as follows: 1. As the tire inflation pressure of towed wheel increased, the tire deformation decreased exponentially, but the tire sinkage increased exponentially. This trend was getting bigger as ground condition was getting softer. 2. The increase of tire inflation pressure increased the effective rolling radius of towed wheel, and this kind of trend occurred greatly as ground condition was soft. As a result, the effective rolling radius for the off-road condition was always larger than that for on-road condition. 3. For the on-road condition, as the tire inflation pressure of towed wheel increased, the motion resistance decreased, but for the off-road condition, augmentation of tire inflation pressure increased the motion resistance. Also, the effect of inflation pressure on motion resistance appeared great as ground condition was soft. Therefore, in order to improve the tire performance by the control of inflation pressure, it is desirable to reduce the tire inflation pressure for off-road condition and to increase the tire inflation pressure for on-road condition.