용해된 소금의 고결화에 따른 탄성파 특성

엄용훈,변용훈,쭝꽝훙,이종섭 한국지반공학회 2009 한국지반공학회논문집 Vol.25 No.5

Salt, one of the most common soluble materials in engineering soil, may have an effect on mechanical behaviors of soils under its cementation process. In order to investigate this natural phenomenon, non-soluble material by using glass beads is mixed with salt electrolyte and cemented by using oven to evaporate water. Three different sizes of glass bead particles, 0.26, 0.5, and 1.29 mm, with different salt concentration, 0, 0.1, 0.2, 0.5, 1.0, and 2.0M, are explored by using P- and S-waves, excited by bender elements and piezo disk elemets, respectively. The velocities of the P-wave and S-wave of the particulate medium cemented by salt show three stages with the degree of saturation: 1) S-wave velocities increase while P-wave velocities reduce with degree of saturation changing from 100% to 90%; 2) Both velocities are stable with degree of saturation varying from 90% to 10%; 3) The velocities change enormously when the specimens are nearly dry with degree of saturation from 10% to 0%. Besides, the resonance frequencies of S-wave show similar stages to the S-wave velocities. This study demonstrates meaningful trends of elastic wave characteristics of geo-materials according to the cementation of dissolved salt.

POTABLE WATER 저장 탱크의 토목설계 및 시공

엄용훈,Eom, Yong-Hun 한국플랜트학회 2018 플랜트 저널 Vol.14 No.3

지반 소실 혼합재의 용해과정 모니터링

쭝꽝홍,엄용훈,심영종,변용훈,이종섭 한국지반공학회 2009 한국지반공학회논문집 Vol.25 No.10

Dissolution of some of geo-materials may yield the loss of the soil strength and the settlement of earth structures. The goal of this study is to monitor the several physical behaviors of soluble mixtures during dissolution. Sand-salt mixtures are used to monitor the meso to macro response including the settlements and shear waves. The mixtures of photoelastic and ice disks are used to monitor micro to meso behavior of soluble mixture including the void ratio, force chain, coordination number and horizontal force changes. In the sand-salt mixtures, shear waves are measured by using bender elements in conventional oedometer cells. In the photoelastic disk - ice disk mixtures, micro to meso response are measured by digital images and load cells. The shear wave velocity decreases at the initial stage of the dissolution, and then increases and approaches to asymptotic value. The larger dissoluble particle and the more random packing produces the severe horizontal fore change. After dissolution, the void increases and the coordination number decreases. This study demonstrates that the particle level behavior such as the changes of the force chain, void ratio, and coordination number affects the global behavior such as the change of the shear wave velocity and horizontal force of the system.

지반 소실 혼합재의 압축성 및 강성 특성

쭝광홍,엄용훈,윤형구,이종섭 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.12

Soils naturally contain grains of different minerals which may be dissolved under chemical or physical processes. The dissolution leads changes in microstructure of particulate media, such as an increase in local void or permeability, which affects the strength and deformation of soils. This study focuses on the small strain stiffness characteristics of vanishing mixtures, which consist of sand and salt particles at different volume fractions. Experiments are carried out in a conventional oedometer cell (Ko-loading) integrated with bender elements for the measurement of shear waves. Dissolutions of particles are implemented by saturating the mixtures at various confining stresses. Axial deformation and shear waves are recorded after each loading stage and during dissolution process. Experimental results show that after dissolution, the vertical strain and the void ratio increase, while the shear wave velocity and small strain shear modulus decrease. The decrease of the velocity results from the void ratio increase and particle contact decrease. The process monitoring during dissolution of the particles shows that the vertical strain dramatically increases at the beginning of the saturation process and converges after vanishing process finishes, and that the shear wave velocity decreases at the beginning and increases due to the particle reorientation. Specimens prepared by sand and salt particles are proved to be able to provide a valuable insight in macro structural behaviors of the vanishings mixtures.

연약지반 평가를 위한 블레이드 타입 현장 전단파 속도 프로브

윤형구,이창호,엄용훈,이종섭 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.12

The assessment of shear wave velocity (VS) in soft soils is extremely difficult due to the soil disturbances during sampling and field access. After a ring type field VS probe (FVP) has been developed, it has been applied at the southern coastal area of the Korean peninsular. This study presents the upgraded FVP “blade type FVP”, which minimizes soil disturbance during penetration. Design concerns of the blade type FVP include the tip shape, soil disturbance, transducers, protection of the cables, and the electromagnetic coupling between transducers and cables. The cross-talking between cables is removed by grouping and extra grounding of the cables. The shear wave velocity of the FVP is simply calculated by using the travel distance and the first arrival time. The large calibration chamber tests are carried out to investigate the disturbance effect due to the penetration of FVP blade and the validity of the shear waves measured by the FVP. The blade type FVP is tested in soils up to 30m in depth. The shear wave velocity is measured every 10cm. This study suggests that the upgraded blade type FVP may be an effective device for measuring the shear wave velocity with minimized soil disturbance in the field.

소금의 고결화 현상에서 모세관 효과

쭝꽝훙,변용훈,엄용훈,이종섭 한국지반공학회 2010 한국지반공학회논문집 Vol.26 No.4

Salt cementation, a typical naturally-cemented phenomenon, may occur due to water evaporation under the change of climate. Capillary force may influence the distribution of cement in granular soils. This study addresses the effect of capillary force on salt cementation using five different techniques: cone penetration test, electrical conductivity measurement, photographic imaging technique, nondestructive imaging technique, and process monitoring by elastic wave. Glass beads modeling a particulate media was mixed with salt water and then dried in an oven to create the cementation condition. Experimental results show that salt cementation highly concentrates at the top of the small particle size specimens and at the middle or the bottom of the large particle specimens. The predicted capillary heights are similar to the locations of high salt concentration in the cemented specimens. Five suggested methods show that the behavior of salt-cemented granular media heavily depends on the capillary force.

Delay Analysis for Segmented Short Message Broadcast over Wireless Cellular Networks

Jun Ha(하준),Yong Hoon Uhm(엄용훈),Cheon Won Choi(최천원) 한국통신학회 2001 한국통신학회 학술대회 및 강연회 Vol.2001 No.4

초음파 반사법을 적용한 기초 지반조사

윤형구 ( Yoon Hyung-koo ),쭝광훙 ( Truong Q. Hung ),엄용훈 ( Eom Yong-hun ),변용훈 ( Byun Yong-hoon ),이종섭 ( Lee Jong-sub ) 한국구조물진단유지관리공학회 2009 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.13 No.2

This study presents the application of ultrasonic reflection method to investigate soil in underwater pile. This method uses the multiple reflection waves captured at interface. Measurement system consists of pulser, filter-amplifier, oscilloscope and computer(NI-5112). Experiment is carried out by traveling transducer horizontally. Experimental result shows the discontinuity is well detected in underwater ground. Application discussed in this paper show that ultrasonic reflection method can be an very effective tool for the investigation of the discontinuity in underwater ground.

초음파 반사법을 적용한 기초 지반조사

윤형구(Yoon, Hyung-Koo),쭝꽝훙(Truong, Q. Hung),엄용훈(Eom, Yong-Hun),변용훈(Byun, Yong-Hoon),이종섭(Lee, Jong-Sub) 한국구조물진단유지관리학회 2009 한국구조물진단학회 학술발표회논문집 Vol.2009 No.2

현장에서의 수중 이물질탐사 및 불연속면 탐사를 위한 예비 실험의 일환으로 현장실험을 실시하였다. 실험 장소는 목포고하대교 건설현장이며, 실험위치는 우물통기초 위에서 실시하였다. This study presents the application of ultrasonic reflection method to investigate soil in underwater pile. This method uses the multiple reflection waves captured at interface. Measurement system consists of pulser, filter-amplifier, oscilloscope and computer(NI-5112). Experiment is carried out by traveling transducer horizontally. Experimental result shows the discontinuity is well detected in underwater ground. Application discussed in this paper show that ultrasonic reflection method can be an very effective tool for the investigation of the discontinuity in underwater ground.