• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 학술발표집 지반진동 영향평가
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• pp.83-116
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• 1993

본 고는 쓰레기 매립장에서 동다짐을 시행할 시 발생하는 진동을 측정하고, 그 결과를 분석하여 쓰레기 매립지반의 동다짐 진동 특성을 고찰하였다. 진동특성은 크게 쓰레기 매립지반의 일반적 진동특성과 동다짐 조건 변화에 의한 진동특성의 2가지 측면으로 검토되었다. 그 결과 연구대상 쓰레기 매립지반의 기본적인 진동특성으로 충격지점 주위에서의 전단계수 G 행 17496~58320 t/m2, 감쇠비 D=14~58%, 탁월진동수 f=6~14 Hz 등으로 나타났다. 동다짐 조건 차이에 의한 진동특성으로는 타격회수가 증가될수록 cross hole시험에 의한 전단파 및 압축파의 속도가 중가하였으며, 타격지점으로 부터의 거리와 최대입자속도는 vPP = 5.08 [D/E]-1.4의 관계를 가지며, 쓰레기층 바닥에서는 반사파의 영향으로 진동의 진폭이 커지는 것으로 나타났다. 또한 진동에 의하여 지반이 개량되는 범위는 타격지점으로 부터 반경 약 6~10 m정도인 것으로 나타났다.

• Geomechanics and Engineering
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• 제15권6호
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• pp.1143-1151
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• 2018

Loess often causes problems when used as a filling material in the construction of foundations. Therefore, the compaction technique, shear behavior, and bearing capacity of a filled foundation should be carefully considered. A series of tests was performed in this study to obtain effective compaction techniques and construction parameters. The results indicated that loess is strongly sensitive to water. Thus, the soil moisture content should be kept within 12%-14% when it is used as a filling material. The vibrating-dynamic combination compaction technique is effective and has fewer limitations than other methods. In addition, the shear strength of the compacted loess was found to increase linearly with the degree of compaction, and the soil's compressibility decreased rapidly with an increase in the degree of compaction when the degree of compaction was less than 95%. Finally, the characteristic value of the bearing capacity increased with an increase in the degree of compaction in a ladder-type way when the degree of compaction was within 92%-95%. Based on the test data, this paper could be used as a reference in the selection of construction designs in similar engineering projects.

• 한국재난정보학회 논문집
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• 제14권3호
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• pp.305-314
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• 2018

연구목적: 동치환공법은 유사한 동다짐공법에 비해 동치환 직경, 심도, 간격, 타격에너지(중추 무게와 낙하고), 지반강도 증대 효과, 지반 개량효율 등에 대한 연구 및 실증이 부족하다. 연구방법: 본 연구에서는 실트질 점토지반을 연구 대상 지반으로 선정하여 예비 동치환시공과 본시공 동치환의 2가지 경우로 나눠서 지반개량을 실시하고 효과를 분석하였으며, 결과를 바탕으로 적정 개량심도 결정 및 개량효과에 미치는 인자에 관하여 연구하였다. 연구결과: 실트질 점토 지반을 대상으로 동치환 적정 심도 결정, 지반개량효과에 끼치는 특성을 상세히 분석하여 동치환 시 적용할 수 있는 개량심도 ($D_R$) 관계식을 제안하였다. 결론: 동치환공법을 실트질 점토 지반에 적용한 경우, 동다짐공법의 낙하에너지보다 1.25~2.5배 증가시켜야 하는 것으로 나타났다.

• 한국지반공학회논문집
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• 제28권2호
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• pp.5-14
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• 2012

현장 다짐기에 가속도계를 이용한 연속다짐 평가장치를 부착하여 얻은 지반의 지지력 평가값 및 기존의 다짐도 평가장치의 결과 값들을 회귀분석하여 비교하였다. 회귀분석 평가 결과, 특정 성토재료에서 Geogauge와 동적콘관입시험은 기존 다짐도 평가(평판재하시험 및 다짐도시험) 결과와의 상관관계가 거의 없는 것으로 나타났다. 또한 CMV를 이용한 평가법이 기존 다짐도 평가를 대체할 수 있는지를 알아보기 위하여 여러 가지 다짐도 평가를 실시하였다. 그 결과 가속도계를 이용한 CMV는 다져진 지반의 강성 특성을 빠르고 편리하게 평가할 수 있을 것으로 판단된다.

• 지구물리
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• 제6권4호
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• pp.245-259
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• 2003

Two multichannel analysis of surface wave (MASW) surveys were conducted over a soil site in Tacoma Water's Green River Facility, Washington, where construction of a chemical treatment facility had been planned. The purpose of the surveys was to compare soil stiffness characterized by shear-velocity (Vs) distribution before and after Deep Dynamic Compaction (DDC) operation that was designed to improve the soil stiffness. Site soil consisted of very heterogeneous gravel and cobbles in a sand-and-silt matrix. Results from each survey are represented by two 2-D Vs maps delineating Vs variation of soil below the surveyed lines. One map was constructed from those dispersion curves that were analyzed with a significant amount of subjective judgment involved, whereas the other map was constructed from those dispersion curves analyzed with as much objective information as possible. Comparison of 2-D Vs maps indicates that Vs actually decreased after the DDC operations, possibly due to the loss (or reduction) of cohesive bonding between soil particles caused by the compaction operations.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.525-527
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• 2008

N-Type $SbI_3$-doped $95%{Bi_2}{Te_3}-5%{Bi_2}{Se_3}$ compounds were prepared by a gas atomization and Magnetic Pulsed Compaction process. The dynamic recrystallization and thermoelectric properties of the MPCed bulks with consolidation temperatures and times were investigated by a combination of microscopy, XRD and thermoelectric property testing. The microstructure of MPCed bulk shows homogeneous and fine distribution through consolidated bulks due to dynamic recrystallization during hot MPC. This research presented the challenges toward the successful consolidation of thermoelectric powder using magnetic pulsed compaction (MPC).

• 한국분말재료학회지
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• 제21권1호
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• pp.44-49
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• 2014

In this study, nanocrystalline nickel powders were cold compacted by a dynamic compaction method using a single-stage gas gun system. A bending test was conducted to measure the bonding strengths of the compacted regions and microstructures of the specimen were analyzed using a scanning electron microscopy. The specimen was separated into two parts by a horizontal crack after compaction. Density test shows that the powder compaction occurred only in the upper part of the specimen. Brittle fracture was occurred during the bending test of the compact sample. Dispersion of shock energy due to spalling highly affected the bonding status of the nanocrystalline nickel powder.

• Geomechanics and Engineering
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• 제20권4호
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• pp.313-322
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• 2020

This study focuses on a prediction approach of compaction compensation grouting efficiency in sandy soil. Based on Darcy's law, assuming that the grouting volume is equal to the volume of the compressed soil, a two-dimensional calculation model of the compaction compensation grouting efficiency was improved to three-dimensional, which established a dynamic relationship between the radius of the grout body and the grouting time. The effectiveness of this approach was verified by finite element analysis. The calculation results show that the grouting efficiency decreases with time and tends to be stable. Meanwhile, it also indicates that the decrease of grouting efficiency mainly occurs in the process of grouting and will continue to decline in a short time after the completion of grouting. The prediction three-dimensional model proposed in this paper effectively complements the dynamic relationship between grouting compaction radius and grouting time, which can more accurately evaluate the grouting efficiency. It is practically significant to ensure construction safety, control grouting process, and reduce the settlement induced by tunnel excavation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 가을 학술발표회 논문집
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• pp.81-88
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• 1997

현재 국내외에서 해안가에 수심이 낮은 지역을 중심으로 대규모 매립공사를 수행하여 주택단지, 항만시설, 공업단지 및 공항부지 등으로 사용하고 있다. 매립재를 양질의 모래로 사용하는 경우 매립방법에 따라 매립토의 조밀정도는 다르나 어떠한 경우든 상당히 느슨하거나 중간정도 느슨한 상태로 존재한다. 이런한 느슨한 사질토는 지진 시 액상화 현상에 민감하고, 낮은 지지력 및 큰 즉시침하를 야기시킨다. 따라서 매립된 느슨한 사질토는 향후 시설될 구조물의 중요도에 따라 개량할 필요가 있다. 본 현장의 준설 매립된 사질토의 지반 개량에 적용된 동다짐의 시험시공중 pounder에 accelerometer를 설치하고 적외선 beam을 이용, 충격시의 pounder의 deccleration과 impact velocity를 측정하였다. 여기에서는 이들 실측치를 근거로 중량물체(pounder)의 동적 거동 및 충격시 과잉간극수압 변화를 살펴보았다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.607-616
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• 2006

More strict construction control of railway roadbeds is demanded in high speed railway system because of heavier repeated dynamic loading than conventional railways. The aim of this study is to propose a compaction control methodology of crushed-rock-soil-fills including as large particles as $200\sim300mm$ in diameter, which are easily encountered in high speed railway roadbed. Field tensity evaluation and in turn compaction control of such crushed-rock-soil-fills are almost impossible by conventional methods such as in-situ density measurements or plate loading tests. The proposed method consists of shear wave measurements of compaction specimens in laboratory and in-situ measurements of fills. In other words, compaction control can be carried out by comparing laboratory and field shear wave velocities using as a compaction control parameter. The proposed method was implemented at a soil site in the beginning and will be expanded to crushed-rock-soil-fills in future. One interesting result is that similar relationship of shear wave velocity and water content was obtained as that of density and water content with the maximum value at the optimum moisture content.