• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.173-178
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• 2016

Background: In situ gamma spectrometry has been used to measure environmental radiation, assumptions are usually made about the depth distribution of the radionuclides of interest in the soil. The main limitation of in situ gamma spectrometry lies in determining the depth distribution of radionuclides. The objective of this study is to develop a method for subsurface characterization by in situ measurement. Materials and Methods: The peak to valley method based on the ratio of counting rate between the photoelectric peak and Compton region was applied to identify the depth distribution. The peak to valley method could be applied to establish the relation between the spectrally derived coefficients (Q) with relaxation mass per unit area (${\beta}$) for various depth distribution in soil. The in situ measurement results were verified by MCNP simulation and calculated correlation equation. In order to compare the depth distributions and contamination levels in decommissioning KRR site, in situ measurement and sampling results were compared. Results and Discussion: The in situ measurement results and MCNP simulation results show a good correlation for laboratory measurement. The simulation relationship between Q and source burial for the source layers have exponential relationship for a variety depth distributions. We applied the peak to valley method to contaminated decommissioning KRR site to determine a depth distribution and initial activity without sampling. The observed results has a good correlation, relative error between in situ measurement with sampling result is around 7% for depth distribution and 4% for initial activity. Conclusion: In this study, the vertical activity distribution and initial activity of $^{137}Cs$ could be identifying directly through in situ measurement. Therefore, the peak to valley method demonstrated good potential for assessment of the residual radioactivity for site remediation in decommissioning and contaminated site.

• 터널과지하공간
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• 제7권4호
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• pp.323-333
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• 1997

A rock mass is usually classified by the results of geological survey and laboratory tests on rock specimens in order to obtain the adequate properties for the numerical analysis. For these purposes a rock mass strength is estimated based on the empirical criterion proposed by Hoek and Brown and a modulus of deformation is taken with the empirical relations developed by Bieniawski, Serafim and Pereira. In addition, the $K_o$ value which is the ratio of the horizontal stress to the vertical stress is one of the most important input data in the numerical analysis. Its role on a tunnel stability analysis could be verified with the numerical results taken by a finite difference code or a distinct element code. However, a deduced value used to be applied for the $K_o$ value in most of tunnel designs, even though the patterns of stress tensor are variable with regions and depths. Thus in situ stresses were measured by a hydraulic fracturing technique on several tunnel sites and applied directly to the tunnel design for the enhancement of its precision. With those informations on in situ stresses, the safe design should be obtained economically on the road or subway tunnels.

• 화약ㆍ발파
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• 제28권2호
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• pp.133-147
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• 2010

본 연구에서는 암반분류를 현장에서 바로 실시할 수 있는 암반분류법을 도출하고 도출된 분류법과 기존분류법간의 상관관계를 고찰하는데 그 목적이 있다. 암반 묘사를 위한 분류인자를 먼저 암반강도와 암반구조로 나누었으며, 암반강도는 점하중강도와 절리상태, 암반구조는 RQD와 절리간격을 통하여 평가하였다. 변수의 평가를 위한 지표는 기존의 분류법에서 획득하여 이용하였으며, 이를 통하여 암반의 강도 특성과 구조적 특성을 모두 나타내었다. 도출된 각 각의 변수에는 25점의 배점을 할당하였다. $RMR_{basic}$과 본 연구와의 상관관계는 $RMR_{basic}$ = 0.86(X-Method)+14.47, 수정 RMR과 본 연구와의 상관관계는 $RMR^*$ = 0.87(X-Method)+9.20로 나타났다. 결정계수는 각각 $R^2$=0.841, $R^2$=0.846으로 나타났다.

• Geomechanics and Engineering
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• 제19권2호
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• pp.141-151
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• 2019

A novel theoretical solution is presented for created (zero initial radius) cavity expansion problem based on CamClay model and considers the effect of initial anisotropic in-situ stress and drained conditions. Here the strain of this theoretical solution is small deformation in elastic region and large deformation in plastic region. The works for cylindrical and spherical cavities expanding in drained condition from zero initial radius are investigated. Most of the conventional solutions were based on the isotropic and undrained condition, however, the initial stress state of natural soil mass is anisotropy by soil deposition history, and drained cavity expansion calculation is closer to actual engineering in permeable soil mass. Finally, the parametric study is presented in order to the engineering significance of this work.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.27-31
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• 2021

VI probe, which is one of various in-situ plasma monitoring sensor, is frequently used for in-situ process monitoring in mass production environment. In this paper, we correlated the plasma etch results with VI probe data with the small amount of gas flow rate changes to propose usefulness of the VI probe in real-time process monitoring. Several different sized contact holes were employed for the etch experiment, and the etched profiles were measured by scanning electron microscope (SEM). Although the shape of etched hole did not show satisfactory relationship with VI probe data, the chamber status changed along the incremental/decremental modification of the amount of gas flow was successfully observed in terms of impedance monitoring.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.967-973
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• 2004

Rock socketed drilled shafts transfer significant portion of structural loads at the socketed part. Therefore, a proper design of side and base resistances of a shaft at the socket is a major concern for the geotechnical engineers. In this study, we modified the Hoek-Brown criterion to estimate side resistance of rock socketed drilled shafts. Earlier method to compute side resistance of a shaft is linear or power functions of intact rock masses. However, side resistance is mobilized like shearing which influenced by the mechanical properties of concrete and rock masses, adhesion of rock/concrete interface, roughness of rock socket. Therefore, a single coefficient or power of uniaxial compressive strength of intact rock cannot provide accurate values of side resistance in a wide range of the uniaxial compressive strength. A new approach proposed in this study can consider in situ rock mass condition (frequency or discontinuities, weathering condition), and rock types thus, it has a wider applicability than the earlier models.

• 천문학회보
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• 제40권1호
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• pp.46.3-46.3
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• 2015

As theoretical and empirical studies have pointed out, galaxy mergers play a pivotal role in galaxy mass assembly histories. Its contribution is considered to be more significant in more massive galaxies. In order to quantitatively understand the origin of stellar components in galaxies, we investigated stellar mass assembly histories as a function of galaxy and halo mass using semi-analytic approaches. In this study, we found that the most massive galaxies (log $M/M_{\odot}$ ~ 11.75 at z = 0), which are mostly the brightest cluster galaxies, obtain roughly 70% of their stellar components via mergers. The role of mergers monotonically declines with galaxy mass: less than 20% for log $M/M_{\odot}$ = 10.75 at z = 0. The contribution of galaxy mergers to stellar mass growth decays more slowly than that of in-situ star formation. Therefore, merger accretion becomes a dominant channel for stellar mass growth of the most massive group since z~2. However, when it comes to central galaxies in haloes less massive than $10^{13}_{\odot}$, star formation is always dominant.

• 한국터널지하공간학회 논문집
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• 제6권4호
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• pp.303-314
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• 2004

본 연구에서는 터널을 굴착할 때 절리가 있는 암반의 역학적 거동특성을 실험적으로 규명하고자 하였다. 절리와 터널의 이격거리, 측압계수를 변화시키며 실험을 수행하였다. 터널주변에 수직절리가 있는 경우 천단부와 수직절리 반대편의 어깨부에서 가장 큰 영향이 발생되며 측압이 작을 경우에는 천단부 보다 절리 반대편 측벽부에서 접선 방향의 응력이 크게 증가된다. 반면 $45^{\circ}$의 경사절리가 있는 경우 발생하는 압축응력은 절리면 방향의 터널 좌측부가 무절리 상태의 3배정도로 터널의 안정성에 큰 영향을 미치는 것으로 나타났다.

• 터널과지하공간
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• 제21권3호
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• pp.205-215
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• 2011

본 논문은 국내 여러 지역에서 수행된 도로, 철도 및 기타 토목공사를 위한 설계과정에서 이루어진 현지조사 및 시추공을 이용한 현장시험과 실내시험 및 암반평가가 이루어진 화강암의 자료들을 대상으로 물성 및 암반분류방법간의 상관관계에 대해 분석을 실시하였다. 실험실과 현지에서 측정된 화강암의 물성 중에 단위중량, 압축강도, 인장강도, 탄성파속도, 점착력 및 마찰각 그리고 탄성계수 및 변형계수에 대해 분석을 실시하였다. 이들 물성 중에서 압축강도와 각 요소들 사이의 상관관계에 대해서도 검토하였다. 국내 화강암을 대상으로 조사된 RQD, RMR 과 Q 시스템의 암반분류법간의 상관관계에 대해서도 분석을 실시하였고, 기존의 암반분류법간의 상관관계를 보다 간편화하여 상관관계식을 유도하였다. 그리고 현장에서 시추코어를 대상으로 측정된 RQD와 압축강도 값으로부터 RMR 값을 유도하였으며 또한 RMR값을 이용하여 현지암반 탄성계수를 유추하였다.

• Molecules and Cells
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• 제45권7호
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• pp.502-511
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• 2022

Bacterial volatile compounds (BVCs) exert beneficial effects on plant protection both directly and indirectly. Although BVCs have been detected in vitro, their detection in situ remains challenging. The purpose of this study was to investigate the possibility of BVCs detection under in situ condition and estimate the potentials of in situ BVC to plants at below detection limit. We developed a method for detecting BVCs released by the soil bacteria Bacillus velezensis strain GB03 and Streptomyces griseus strain S4-7 in situ using solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS). Additionally, we evaluated the BVC detection limit in the rhizosphere and induction of systemic immune response in tomato plants grown in the greenhouse. Two signature BVCs, 2-nonanone and caryolan-1-ol, of GB03 and S4-7 respectively were successfully detected using the soil-vial system. However, these BVCs could not be detected in the rhizosphere pretreated with strains GB03 and S4-7. The detection limit of 2-nonanone in the tomato rhizosphere was 1 µM. Unexpectedly, drench application of 2-nonanone at 10 nM concentration, which is below its detection limit, protected tomato seedlings against Pseudomonas syringae pv. tomato. Our finding highlights that BVCs, including 2-nonanone, released by a soil bacterium are functional even when present at a concentration below the detection limit of SPME-GC-MS.