원심모형시험에 의한 사석재의 내부마찰각 추정

유남재,박병수,정길수,이종호 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

This paper is an experimental work of estimating friction angle of very coarse grained soil such as rubble mound by performing laboratory experiments. Two crushed rocks of rubble mound were used for tests. Triaxial compression tests with drained conditions were performed to measure friction angles of soils prepared by mixing the crushed soil having an identical coefficient of uniformity with different maximum grain size distribution. Centrifuge model experiments with those soils were also performed to measure angle of repose and to estimate friction angle of soil from measuring the slope of slip line in the active stress state. Model tests were carried out by changing the G-levels of 1G and 50G. From triaxial compression tests, the measured value of friction angle of soil is in the range of 41∼57˚. The measured value of repose angle is in the range of 32∼35˚. The values of friction angle are found not so sensitive to the maximum grain size of soil as long as the coefficient of uniformity is identical. Estimated value of friction angle from measuring the slope of slip line in the active stress state is in the range of 30~46˚. Thus, the estimated angle of friction are found to be greater in the order of the measured angle of repose, the estimated value from the slope of active state, and triaxial compression test results. On the other hand, the measured values of friction angle from triaxial tests were compared with empirical equations, based on the relation between friction angle and void ratio. Equations proposed by Helenelund(1966) and Hansen(1967) found to be relatively reliable to estimate friction angles of soil.

모래다짐말뚝의 원심모델링

유남재,정길수,김상진,채승호 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

This paper is results of extensive centrifuge model experiments about design factors influencing the bearing capacity and the settlement behaviors of SCP (Sand Compaction Pile). Centrifuge model tests were carried out changing design factors for SCP method such as replacement area ratio (as= 20, 40, 70%), improvement ratio to footing width (W/B = 1, 2, 3), and amount of fines in sand pile (#200 = 5, 10, 15). Therefore, the effects of these design factors on the bearing capacity and the settlement behavior of SCP were investigated and changes of stress concentratio rato due to such an design factors were also investigated. Centrifuge model testing technique for preparing and installing centrifuge model of sand compaction pile, using freezing them, was also developed. As results of centrifuge model tests, more fines in sand compaction pile increases the bearing capacity of SCP. Optimum improvement ratio to footing width was found to be 2. Values of stress concentration ratio was in the ranges of 1.5 - 3.5. The depth of bulging in sand piles was found in the range of 2.0 - 2.5 times of pile diameter.

강제치환 거동특성에 관한 원심모형실험

이종호,박병수,정길수,유남재 강원대학교 산업기술연구소 2003 産業技術硏究 Vol.23 No.A

This thesis is results of centrifuge model experiments to investigate the behavior of replacement method in dredged and reclaimed ground For experimental works. centrifuge model tests were carried out to investigate the behavior of replacement method in soft clay ground. Basic soil property). tests were performed to find mechanical properties of clay soil sampled from the southern coast of Korea which was used for ground material in the centrifuge model tests Reconstituted clay ground of model was prepared by applying preconsolidation pressure in 1g condition with specially built model container. Centrifuge model tests were carried out under the artificially accelerated gravitational level of 50g Replacing material of leads having a certain degree of angularity was used and placed until the settlement of embankment of replacing material was reached to the equilibrium state. Vertical displacement of replacing material was monitored during tests. Depth and shape of replacement. especially the slope of penetrated replacing material and water contents of clay ground were measured after finishing tests Model tests of investigating the stability of embankment after backfilling were also performed to simulate the behavior of the dike treated with replacement and backfilled with sandy material. As a result of centrifuge model test. the behavior of replacement, the mechanism of the replacing material being penetrated into clay ground and depth of replacement were evaluated

Oyster-Zeolite 흡착탑을 이용한 하수의 유기물질과 질소제거

정병길,정유진,박성현,최호은,성낙창 東亞大學校 建設技術硏究所 2005 硏究論文集 Vol.29 No.1

The objective of this study is to investigated the removal possibility of organic matter and nitrogen contained final effluent of sewage treatment plant using oyster-zeolite adsorption column with waste oyster shell and natural zeolite. The raw water was collected the final effluent of Janglim sewage treatment plant in Busan city. The organic matter and T-N removal efficiency ranged from 2~60% and 38~97%, respectively. In conclusion, oyster-zeolite adsorption column could organic matter and nitrogen removal of final effluent of sewage treatment plant and its economical efficiency is enough because of using recycled waste oyster shell and a cheap natural zeolite.

수평배수재 배열의 진공압밀효과에 대한 수치해석

박병수,정길수,이종호,유남재 강원대학교 산업기술연구소 2003 産業技術硏究 Vol.23 No.A

This paper is results of numerical works of investigating effects of horizontal drain arrangements on vacuum consolidation. Extensive numerical analyses were carried out to find the appropriate arrangements of horizontal dram of vacuum consolidation. Commercially available program of CRISP. well know-n to be good to modelling the behavior of clay- material, was used Cam-clay model, based on the Critical State of Soil Mechanics(CSSM), was used to simulate the geotechnical engineering behavior of clay. Model test results carried out previously in the laboratory w-ere compared with numerically estimated results and it was found that results about consolidational settlement with times were in good agreements. Based on this confirmation. parametric numerical study was performed to investigate effects of horizontal drain arrangements on vacuum consolidation with changing the vertical and horizontal spacings between drains for the given soil properties and vacuum. The effect of distance of drain located in top layer from the surface of the ground on the settlement due to vacuum was also investigated. As a results of numerical analyses. appropriate arrangements of horizontal drain to maximize the consolidation settlement due to vacuum were found. The mechanism of vacuum consolidation about the vacuum pressures being transferred to the effective stresses around drains was also evaluated.

육상 100m 달리기 지도 및 기록향상을 위한 기술분석

이상철,오봉석,유호길 龍仁大學校 1998 용인대학교 논문집 Vol.16 No.-

This study was performed to analyze the technique of 100m sprint running and to offer profitable information related to sprint running to trainer and sprinter. To this purpose the technique of 100m sprint running was divided into four phase, that is, start phase, acceleration phase, maximum speed phase and finish phase. The following is summary. 1. In the 'set' position the most effective fore-leg and near-leg angle is 90 ˚, 120 ˚ respectively. Backbone angle is 27 ˚, shoulder position is on 10cm ahead of starting line. The head and neck are naturally as an extension of the trunk. The sprinter needs maximum concentration for the first action of the arms and legs. When the starting pistol fires the a straight line can be drawn from the toes of extended driving leg to the sprinter's head. 2. During the acceleration phase the body will gradually rise from a pronounced to a slight forward lean. The arms must be harmony with the legs. The hands are lifted not much higher than shoulder level. 3. During the maximum speed phase when the driving leg land below of gravity center the knee must be somewhat bended for reduction of the landing brake. Recovery leg heel moves to the buttocks to reduce the length of plumb and to increase the number of pitch. Arms must swing with 90 degrees at the elbow. 4. During the finish phase the sprinter must do the exact finishing techniques at exact timing. That is, it is disadvantageous for the sprinter to do the finish technique on excessive tension and to do jumping. A forward dip finish method during the last stride before the finish line is the most commonly used technique.

관동맥 우회로술 중 경식도 심초음파도로 관찰한 도부타민 투여후와 우회로술후의 좌심실 국소벽운동

김희열,김종진,윤호중,유기동,박지원,이길환,노태호,채장성,김재형,홍순조,최규보 대한순환기학회 1997 Korean Circulation Journal Vol.27 No.8

Measurement of Nitrous Oxide Emissions on the Cultivation of Soybean by No-Tillage and Conventional-Tillage in Upland Soil

Yoo, Gil-Ho,Kim, Deok-Hyun,Yoo, Jin,Yang, Jong-Ho,Kim, Sang-Woo,Park, Ki-Do,Kim, Min-Tae,Woo, Sun-Hee,Chung, Keun-Yook 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.6

The impact of 1 pound of nitrous oxide ($N_2O$) on warming the atmosphere is almost 310 times that of 1 pound of carbon dioxide. Agricultural soil management is the largest source of $N_2O$ emissions, accounting for about 73% of total $N_2O$ emissions. This study was conducted to evaluate the nitrous oxide emission in the cultivation of soybean during the first year of No-tillage (NT) and Conventional-tillage (CT) practices, under the various conditions such as different kinds of fertilizers, soil temperature, and moisture level. In the experiment, we set CT and NT treatments into 4 different groups - control treatments (no fertilization), green manure treatments, chemical fertilizer treatments and organic manure treatments. In the case of chemical fertilizer treatments, $N_2O$ emission of NT treatment was 7.78 to 22.59% lower than CT treatment. In organic manure treatment, $N_2O$ emission of NT treatment was 6.62% higher than CT treatment in August. But In July and September, $N_2O$ emission of NT treatment was 9.50% 28.38% lower than CT treatment, respectively. Soil temperature was correlated with $N_2O$ emission positively. In the future, continued long-term research on influence of various environmental factors on the generation of $N_2O$ and the economic value of no-till farming is required.

Effect of hybrid metal-composite gear on the reduction of dynamic transmission error

Ho-Gil Yoo,정우진,김범수,박영준,강마루,Hyun Ku Lee,Moo Suk Kim,Kyoung-Sang Lee 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

Gear whine noise has become one of the primary challenges facing noise, vibration, and harshness engineers; this is because the electrification of the powertrain has largely eliminated engine masking noise while increasing the working speed of the Epowertrain. In this study, a hybrid metal-composite gear was proposed to reduce gear whine noise, and its performance was evaluated by means of dynamic transmission error (DTE). The test results showed that the hybrid metal-composite gear produced an effectively lower DTE than that of alternatives, particularly when approaching resonance speeds. In addition, a reduction in resonance DTE was verified by acquiring and comparing the frequency response functions of a steel gear and a hybrid metal-composite gear. As DTE is the primary excitation source contributing to whine noise, the hybrid metal-composite gear is expected to be a significant candidate for the reduction in powertrain whine noise.

Measurement of Nitrous Oxide Emissions on the Cultivation of Soybean by No-Tillage and Conventional-Tillage in Upland Soil

Gil-Ho Yoo,Deok-Hyun Kim,Jin Yoo,Jong-Ho Yang,Sang-Woo Kim,Ki-Do Park,Min-Tae Kim,Sun-Hee Woo,Keun-Yook Chung 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.6

The impact of 1 pound of nitrous oxide (N₂O) on warming the atmosphere is almost 310 times that of 1 pound of carbon dioxide. Agricultural soil management is the largest source of N₂O emissions, accounting for about 73% of total N₂O emissions. This study was conducted to evaluate the nitrous oxide emission in the cultivation of soybean during the first year of No-tillage (NT) and Conventional-tillage (CT) practices, under the various conditions such as different kinds of fertilizers, soil temperature, and moisture level. In the experiment, we set CT and NT treatments into 4 different groups - control treatments (no fertilization), green manure treatments, chemical fertilizer treatments and organic manure treatments. In the case of chemical fertilizer treatments, N₂O emission of NT treatment was 7.78 to 22.59% lower than CT treatment. In organic manure treatment, N₂O emission of NT treatment was 6.62% higher than CT treatment in August. But In July and September, N₂O emission of NT treatment was 9.50% 28.38% lower than CT treatment, respectively. Soil temperature was correlated with N₂O emission positively. In the future, continued long-term research on influence of various environmental factors on the generation of N₂O and the economic value of no-till farming is required.