• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.5
• /
• pp.543-550
• /
• 2011

The development of railway vehicles such as new mechanism of railway vehicle or design parameters of suspension have been used the application of scaled roller rig to the study of railway vehicle dynamics. In this paper, the critical speed was compared between full scale and 1:5 scale of numerical model. And to verify the simulation results, the critical speed was confirmed using the 1:5 scaled roller rig. According to the results, we expect that the developed roller rig will be used in the study for the dynamic characteristics of railway vehicle.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.1
• /
• pp.1-6
• /
• 2008

Performance test of the 30-ton class liquid rocket engine turbopump turbine has been conducted using high pressure cold air. Overall performance of the two kinds of turbine rotors - rotor with knife-edged L.E blades and with rounded L.E blades - has been measured for various rotational speed and turbine pressure ratio. The effect of rotational speed and turbine pressure ratio on the turbine axial force behavior also has been measured in parallel. Test results have revealed that the efficiency of knife edged L.E. turbine is a little bit higher than that of rounded L.E. turbine. The axial force of the turbine varied linearly with respect to rotational speed and its magnitude largely depended on turbine pressure ratio.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.2
• /
• pp.5-12
• /
• 2023

In this study, the amount of heaving soil and the heave characteristics of the heaving soil generated at the actual site were quantitatively analyzed through DCM laboratory test construction. By reproducing a series of construction processes of the DCM method in a large-scale soil tank close to the actual site, the amount of heaving soil was predicted and the elevation characteristics such as elevation, diffusion range, diffusion angle and amount of elevation of the heaving soil were evaluated. As a result of the laboratory test construction, the actual elevation in terms of similarity within the DCM improvement section is 0~8.18m, and an average of 3.50m is observed. The actual diffusion range of the heaving soil converted to the similarity ratio is distributed from 28.0 to 38.0m on the left and right sides of the improvement section. The total amount of heaving soil calculated by the SUFFER program based on the results of the laboratory test construction is 19,901m³. Compared with the injected slurry amount of 16,992m³, the amount of heave compared to the injected amount is analyzed as 85.4%. The diffusion angle of DCM heaving soil, which analyzed the results of DCM laboratory test construction with the SUFFER program, is measured to be 30.0~38.0° at a depth of 50.0m, and is evaluated as an average of 34.0°. On the other hand, based on the DCM laboratory test construction and the analysis results using the program performed in this study, the amount of heaving soil at the DCM depths of 40.0m and 60.0m is predicted.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2018.04a
• /
• pp.82-82
• /
• 2018

본 연구는 국내에 자생하는 자원식물들의 살초활성을 조사하여 식물생장억제물질을 활용한 환경친화형 제초제 개발에 요구되는 기초 자료를 확보하기 위해 수행되었다. 국내 자생 식물 101종을 식물체 부위별로 나누어 MeOH로 추출하여 획득된 시료 129점에 대해 돌피(Echinocholoa crus-galli P.B. var. formosensis Ohwi)를 이용한 살초활성 검정을 실시하였다. 시료를 소량의 methanol로 녹여 직경 5.5cm petri dish 상의 Whatman No. 2 여지에 균일하게 흡착시킨 후, fume hood 내에서 용매를 제거하고 1mL의 증류수를 첨가하였다. 돌피 종자를 15립씩 3반복으로 파종하여 $28^{\circ}C$, 5,000lux의 growth chamber에 치상하고, 7일 후 시험구 당 균일하게 자란 10개의 유묘를 선발해 초장 및 근장을 조사하였으며, 살초활성 평가를 위해 대조구 개체의 초장과 근장에 대한 생장억제율을 산출하였다. $1,000{\mu}g/mL$ 농도에서 101종 129점 MeOH 추출물들의 돌피 유묘 뿌리 생장에 대한 억제율을 조사한 결과, 80% 이상을 나타낸 식물 시료는 가죽나무 줄기, 누린내풀 지상부, 단풍취 뿌리, 두릅나무 지상부, 백양꽃 전초, 백양꽃 지하부, 병조희풀 경엽부, 산사나무 잎 가지, 삽주 뿌리, 상사화 전초, 상사화 지하부, 석산 뿌리, 애기송이풀 전초 등 17점이었다. 이들 중 90% 이상 고활성을 나타낸 단풍취 뿌리, 두릅나무 지상부, 백양꽃 전초, 상사화 지하부, 석산 뿌리 유래의 추출물에는 새로운 환경친화형 제초제 개발소재로써 활용할 수 있는 살초활성물질들이 함유되어 있는 것으로 생각된다.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.5 no.3
• /
• pp.29-36
• /
• 2001

Same as-built drawings in national roadway bridges in Korea were examined. As a result, many bridge piers were found whose aspect ratios are in the vicinity of 2.5. These columns are expected to do shear-flexure behaviour, but the previous research works considered flexure behaviour columns only. In the study, therefore, a shear-flexure behaviour column was selected as the model pier, and quasi static test on the full and 1/2 scale models was carried out. From the test results, the scale effect on the seismic performance evaluation was analyzed, and the seismic performance of the model bridge pier without seismic details was evaluated by the capacity spectrum method.

• Journal of Industrial Technology
• /
• v.27 no.A
• /
• pp.111-120
• /
• 2007

This paper is results of experimental research on the effect of application of similarity related to permeability of soil on the consolidation behavior as centrifuge modeling of consolidation is performed with the centrifuge model facility. In this research, the permeability of soil was controlled by changing the viscosity of porewater as the mixed water with glycerin was used during the centrifuge model experiments. The effect of drainage path on consolidation was investigated by installing the vertical drains. A serise of centrifuge model tests with conditions of single vertical and radial horizontal drainage were carried out. Kaolinite and Jumunjin standard sand were used as soft clay and surcharges respectively during tests. For testing condition of single vertical drainage considering similarity of permeability, it was found that consolidation with mixed porewater with glycerin was delayed in comparisons sons with test results with water only. For conditions of horizontal drainage with vertical drains, a low permeability by changing the viscosity of pore water resulted in delayed degree of consolidation at an initial stage of consolidation. But, it predicted not much differences in settlement as long as the consolidation time was sufficiently long enough to finish consolidation. Consequently, it was found that similarity in permeability should be considered to be critical for the case of centrifuge model experiments related to consolidation with long drainage path.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.13 no.4
• /
• pp.55-62
• /
• 2009

Fracture behavior of ceramic dome port cover on air breathing engine using liquid and solid fuel propulsion system was carried out in this study. Fracture characteristics was tested and estimated using scaled model of ceramic dome port cover by Shock tube. Fracture behavior was obtained by the fracture pressure from pressure sensor and observed the scattering phenomena of fracture specimen using high speed camera. Results obtained from this study can be used in the base data of dome port cover design for an air breathing engine.

• Nuclear Engineering and Technology
• /
• v.23 no.3
• /
• pp.340-351
• /
• 1991

Experimental studies were conducted on a l/5.03 scale reactor flow model of the Yong-gwang Nuclear Units 3 and 4. The purpose of the flow model test was to estimate the hydraulic effect in the reactor vessel due to the relative size difference between the ABB-CE's System 80 and the YGN 3&4 reactors. The flow model was designed according to the principle of similarity. Obtained from the test were the core inlet flow distribution, the core exit pressure deviations, and the segmental and overall pressure losses across the flow path from the reactor vessel inlet to outlet nozzle. These data will be used to provide input data for the core thermal margin analysis and to verify the analytical hydraulic design method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.77-80
• /
• 2010

A series of hydraulic tests of a Lox pump are performed using water at a room temperature. According to the test results, the Lox pump satisfies its design requirement but both the head and the efficiency do not fully follow the conventional similarity rule. The deviation of the head from the rule is assumed to be due to the increased volute loss at high rotational speed. Furthermore, it is found that when the pump rotates with the flow ratio less then the design requirement the leakage flowrate seems to be increased.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.25 no.4
• /
• pp.7-12
• /
• 1988

The Resistance Committee of Korea Towing Tank Conference extended the Cooperative Experimental Study Program(1985)[1] to perform the geosim tests by exchanging the five different scaled Series 60, $C_B=0.60$ models between the participating organizations and 13 sets of resistance data have been obtained. The test results are compared among the participating towing tanks and also with the results given in the report of the Resistance and Flow Com-identify the mittee of 18th ITTC. The form factor of each model is derived by Prohaska's method to investigate its dependency on $R_n$. On the other hand, at each $F_n$, form factors are also derived by Telfer's method to relation between $F_n$ and form factor. For this hull form, form factors show relatively weak dependency on $R_n$ and strong dependency on $F_n$. And it is also found that dependencies on both have a cross relation. It seems that further study should be continued to understand more clearly the physical phenomena involved in this problem.