• Journal of the Korean GEO-environmental Society
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• v.3 no.1
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• pp.67-77
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• 2002

Volume change of the dredged soils is composed of the volume loss of soil particle flowing over an outflow weir with water and settlement due to both the self-weight consolidation in reclaimed layer and the desiccation at the surface of reclaimed layer. In order to estimate the amount of soil particles flowing over an outflow weir with water, the evaluation procedure of loss ratio of the dredged soils is proposed in the present study based on the Marsal's modified breakage theory and the results of hydrometer analyses. To verify a validity of the proposed procedure, evaluated loss ratio is compared with results from the other existing methods. The model test results and those of field test were compared and analyzed. Also, the variation of soil loss ratio was examined through the model test in the lab.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.57-63
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• 2000

Volume change of the dredged soils is composed of loss amount of the soil particles flowing over an outflow weir with water and settlements due to both the self-weight consolidation in reclaimed layer and the desiccation at the surface of reclaimed layer. In order to estimate the amount of soil particles flowing over an outflow weir with water, the breakage theory and the results of hydrometer analyses. To verify a validity of the proposed procedure, evaluated loss ratio is compared with various estimates from the other existing methods.

• Journal of the KSME
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• v.22 no.3
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• pp.191-195
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• 1982

소결 금속(sintered metal)은 기공(pore)의 존재로 성형에 있어서 체적변화를 유발하므로 이제까지 사용되어오던 체적변화를 유발하므로 이제까지 사용되어오던 일반 소성이론(conventional plasticity theory)은 적용할 수 없기 때문에 소결금속에 대한 소성이론을 정립해 오고 있다. 그 발달 과정을 보면 미국과 일본에서 각각 독자적인 방법으로 진행되었는데 미국에서는 Kuhn씨가 포아숀 비(.nu.)를 정의하여 실험적으로 구하고 이것을 기초로 하여 항복조건을 정립하고 응력과 변형도율과의 관계를 유도해 냄과 동시에 알루미늄 분말 소결원판 단조에 적용하여 그 실용성을 예시하였다. 한편 일본에서는 교오토오 대학의 Shima, Oyane등이 연구 정립한 것으로서 다공정 금속과 그 본금속의 항복 응력비와 정수압의 항복 응력에 대한 영향도를 정의하여 실험을 통하여 결정한 다음 항복조건을 만들고 이로부터 응력과 변형율과의 관계, 등가 변형율을 유도하였고 이를 폐금형 압축시험에 적용하였다.

• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.487-494
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• 2005

In order to estimated a reason of soil slope failure new measurement technology is demanded to measure a variation of volumetric water content which is a key physical parameter for understanding the slope failure in the field. In this study a laboratory soil tank test were conducted to use RDB and ADR measurement probes for measuring the variation of volumetric water content. These experiments were compared with two physical parameters as volumetric water content and pressure water head which are estimated to the compacted weathered granite soil under the artificial rainfall, 7.5mm/hour, in the whole of two stages. From the results the variation of volumetric water content and pressure water head is represented to nearly similar travel time.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.2
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• pp.41-47
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• 1993

Electrical and electromagnetic wave absorbing properties of MnZn ferrite-rubber composites have been examined for varying the volume fraction of ferrite powder from 0.1 to 0.4 in the frequency range between 1-10 GHz. As the volume fraction of MnZn ferrite increased, the complex permittivity and permeability of composite increased. The peak of reflection loss at the frequency corresponding to 1/4 wavelength shifts to lower frequency, and shifts to lower frequency as the thickness of absorber increased. We show that for the ferrite-rubber composites the volume fraction of ferrite should be controled to obtain the absorbing properties required in given frequency range.

• Journal of the Society of Disaster Information
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• v.16 no.2
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• pp.267-275
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• 2020

Purpose: In this study, GPR exploration equipment, spray vehicles and flow meters, core drill, borehole image processing system(BIPS), 3D cavity imagery equipment, and cavity formatting equipment were used to identify this cavity growth process. Method: A certain amount of water was injected in proportion to the mass of the cavity, and the cavity was observed to expand as the injected water was drained out. The cavity rating change was evaluated by quantitatively evaluating the expansion factors and the speed of growth. Results: According to the results of examining the volume change through injection time - injection flow rate - volume increase for the four experimenters, the volume increase decreased as the injection time increased, and there was no further increase in volume if injected for one hour or so. Conclusion: In addition, the injection test analyzed the volumetric variation to determine whether the cause of the cavity occurrence was the effect of the underground burial in the vicinity of the cavity. Therefore, it was found that the cavity expansion is caused by the repetition of the relaxation soil collapse due to the groundwater flow and the loss of the collapsed soil below the cavity.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.57-66
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• 2017

Self-weight consolidation test and soil property of dredged soil at Incheon habour route were analyzed to determine the initial dredging reclamation amount, reclamation depth, and estimating the required time of self-weight consolidation with calculation of the final planned height of dredging reclamation site. The moisture content, void ratio and ratio of volume change with elapsed time after throwing were estimated through Yano's empirical equation. As a result, there was a less variation in elements when fine-grained soil content was low as similarly to the behavior of coefficient of sedimentation-consolidation, Cs and the highest variation was shown at the fine-grained soil content of 50%. The retention ratio according to the fine grained soil content that could reinforce the comprehensive aspect of retention ratio for each particle size presented in the standard of estimate for reclamation construction work was calculated and presented using the calculated ratio of volume change.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.4
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• pp.331-355
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• 1997

본 연구에서는 에어챔버가 설치된 펌프관로계에서 수격현상에 대한 현장실험을 실시하고, 에어챔버의 입력변수 및 설계인자가 수격현상에 어떠한 영향을 미치는지 수치계산과 실험을 통하여 조사한 후 다음과 같은 결론을 얻었다. (1) 수치계산에 사용된 입력변수중 폴리트로프지수, 오리피스 유량계수, 압력파 전파속도순으로 수격현상에 대한 영향이 크게 나타났으며, 수치계산은 이 변수값이 각각 1.3, 0.7, 1,050m/s일 때 측정된 압력변동 및 공기체적변화를 가장 잘 모사하였다. (2) 에어챔버내 초기공기체적이 증가하면 압축공기의 압력변화율이 작아지기 때문에 수격현상의 주기는 길어지고, 관로내 압력변화는 감소하였다. 측관에 설치한 오리피스 내경을 줄임으로써 상승압은 상당히 완화되었으며, 시간이 지남에 따라 수격작용도 보다 빨리 감쇄되었다. 수치계산결과는 수격현상의 1-2주기까지 측정값과 비교적 잘 일치하였으며, 펌프관로계에 작용하는 최대.최소압력 및 그 발생시간도 합리적으로 예측되었다. (3) 수치계산은 측정된 과도특성 값들을 약 5%이내의 오차로 예측하였으며, 개발된 전산프로그램은 실제 펌프관로계에 대한 수격완화장치를 설계하는데 매우 유용하게 사용될 것으로 판단된다.

• Journal of Power System Engineering
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• v.14 no.2
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• pp.22-27
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• 2010

본 논문은 유한체적법에 근거한 CFD 분석기법을 이용하여 증기 이젝터의 성능에 대하여 구동노즐의 기하학적 형상에 따른 영향을 조사하였다. 구동노즐의 직경비를 변화시키고 또한 직경비를 일정하게하고 구동 노즐의 위치를 변화시키면서 최적의 조건을 조사하였다. 연구 결과 이젝터의 성능은 구동노즐의 직경과 노즐의 출구 위치에 의해 좌우됨을 확인하였다. 일정 노즐 면적비에 대하여 노즐 목 직경이 감소함에 따라 혼입율이 증가하는 것을 확인하였고 일정 노즐 목 직경에 대하여 면적비의 증가는 혼입율의 감소의 원인이 된다는 것을 확인할 수 있었다. 또한 혼입율은 노즐의 출구 위치에 따라 영향을 받는다는 것도 확인하였다. 혼입율은 노즐 출구의 위치가 이젝터의 상류로 이동할수록 증가하고 그 위치는 이젝터의 일정단면적부 직경(D)에 대하여 0.4D일 때 최적의 성능을 보였다.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.281-288
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• 2005

To evaluate a property of moisture distribution and volumetric water content on bentonite media the responses of complex dielectric constant were used which are measured by Frequency Domain Reflectometry with Vector Network Analyzer (FDR-V) system. The bentonite is widely used a barrier liner system in the waste disposal site, recently. In case of barrier liner system, generally, the coefficient of permeability should have to less than 10-7cm/sec. According to the results, the complex dielectric constants are increasing with increase the volumetric water content and temperature together. Also the variation of complex dielectric constant due to temperature gradient is confirmed that the moisture movements are increasing with the variations of temperature from high range to low range, which is represented the property of moisture distribution in the bentonite.