• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.179-184
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• 2008

Silt or clay alluvium fully saturated with water generally shows low resistivity. Sometimes it is believe that the low resistivity layer is considered as good aquifer but this makes problems in the development of groundwater. To overcome this problem, we adopted induced-polarization(IP) method with resistivity method. Laboratory experiments and resistivity/IP field surveys with non-polarization electrodes were conducted for the study. Laboratory experiments shows that the increase of clay contents in the sample mixed with sand and clay give low resistivity and high chargeability. We used this experiment results in the interpretation of resistivity/IP field data which were obtained in riverbank filtration. Finally, the layer which has low resistivity and chargeabilty would be regarded as a good aquifer for the development of groundwater intake.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.322-331
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• 2007

In this study, electrical resistivity tomography (ERT) were conducted to find the mineralized zone at the Geumpung mine in Dojeon-ri, Susan-myeon, Jecheon-si, Chungcheongbuk-do. The deviation of the inclined borehole was measured to obtain the exact positions of the electrodes for correcting apparent resistivity values from ERT. Geophysical loggings such as resistivity and natural gamma were conducted to obtain the properties of the material near the borehole. Measurements of the physical properties of the cores, such as porosity, water content, density, susceptibility, resistivity were performed to analyze the correlation between physical properties and resistivity. Grade analysis for core sample was also conducted to identify relationship between grade and resistivity. Rock property analysis shows that the resistivity is more dominated by susceptibility and grade than by porosity and water content in the mineralized zone. The results of ERT are well consistent with geophysical logging data and geologic column. So ERT is powerful method to identify conductive mineralized zone.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.401-401
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• 2011

태양전지 제작에 있어서 에미터층의 최적화를 위해 POCl 도핑시 에미터층의 면저항 가변에 중요한 파라미터인 온도와 가스비를 변화하여 실험을 진행하였다. 본 실험에 사용될 최초 기판은 두께가 200${\pm}$5 ${\mu}m$, 비저항이 0.5~0.3 ${\Omega}{\cdot}cm$의 P-type(100) 실리콘 기판을 사용하였으며 먼저 POCl3양과 deposition 시간 그리고 산소와 질소의 양을 고정시키고 온도에 따른 에미터 면저항 변화를 알아보았다. 온도는 830, 840, 850, 860, 870, 880$^{\circ}C$로 가변시켰으며 공정온도가 높아질수록 면저항 값이 낮아짐을 알 수 있었다. 균일도는 낮은 온도에서는 다소 좋지 않았지만 온도가 높아질수록 점차 좋아졌으며 870$^{\circ}C$ 이상에서는 거의 균일한 값을 얻을 수 있었다. 한편, 이번에는 공정온도를 고정하고 산소와 POCl3 가스량의 변화에 따른 면저항 특성과 균일도를 알아보았다. 가스비와 압력 그리고 위치별 면저항 특성에 대해서 알아보았고 부분압이 증가함으로 반응로 내의 O2의 양이 증가함을 알 수 있었다. 증가한 O2는 도핑과정에서 산화막을 더 두껍게 형성하게 하며 높은 면저항 값을 가져오게 하였다. 즉, 충분한 가스량의 주입으로 도핑시 균일도를 향상시킬 수 있었다. 이와 같이 부분압이 증가함에 따라 면저항의 증가와 균일도의 향상을 가져왔다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.44-44
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• 2011

Unipolar 구조의 양자점 발광소자는 소자에 주입되는 전자로 구동 가능하게 설계되어 bipolar 구조와 달리 직류뿐만 아니라 교류로도 구동이 가능하다. 소자의 구조는 패턴된 ITO 유리기판 위에 Radio frequency magnetron sputter로 성장시킨 투명한 금속산화층 사이에 콜로이드로 분산된 양자점이 포함되어 있다. 본 연구에서는, 전하 수송층으로 사용되는 Zinc Tin Oxide (ZTO)가 전압 인가 시 발생하는 과부하로 인해 낮은 전계발광(electroluminescence, EL)특성이 나타나는 문제점이 있다. 이를 해결하고자 ZTO층의 비저항과 EL특성 사이의 관계를 알아보고, ZTO의 비저항 값을 변화시키기 위해 sputter 공정 중 인가 전력과 작업압력, 산소 분압 등의 성장 조건을 변화시켰다. ZTO의 조성비에 따른 비저항 및 전기적 특성을 홀 측정 장비로 측정하였다. 인가전력이 낮고 작업압력이 낮을수록 비저항 값이 낮았으며, 그에 따라 소자의 동작전압이 낮아지고 EL특성 또한 우수하게 나타났다.

• Journal of the Korea Institute of Building Construction
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• v.23 no.5
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• pp.519-526
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• 2023

This research endeavors to explore the nuances in apparent resistivity readings in concrete specimens due to the proximity of embedded reinforcement. To systematically gauge this, concrete samples incorporating singular and paired rebars were meticulously crafted. These rebars were strategically positioned at intervals of 0.03m, 0.04m, and 0.05m from each specimen's midpoint. Subsequent resistivity assessments were conducted at 0.01m increments up to the predetermined rebar location for each sample. A consistent observation was the nadir in apparent resistivity manifesting at the rebar's epicenter. Notably, dual-rebar configurations registered lower resistivity values at this central juncture compared to their single-rebar counterparts. This metric underscores the palpable impact of surrounding reinforcement on resistivity readings. Further, as the spatial separation between rebars increased, the distinctness in their locational identification via resistivity became increasingly pronounced.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.65.1-65.1
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• 2011

결정질 실리콘 웨이퍼의 전면 재결합 속도, 비저항은 태양전지 특성에 영향을 끼치는 중요한 요소이다. 태양전지의 최종목표인 효율에 미치는 영향을 알아보기 위해 패시베이션 처리된 n-형 웨이퍼를 사용한 태양전지에서 웨이퍼의 비저항과 전면 재결합 속도를 조절하였고 그에 따른 변환 효율과 기본 파라미터 값의 변화를 확인하였다. PC1D를 사용하여 시뮬레이션을 수행하였으며 이론적으로 비저항 = $0.06557{\Omega}{\cdot}cm$, 전면 재결합 속도 = 100cm/s에서 18.46%의 효율을 얻을 수 있었다.

• Journal of the Korea Concrete Institute
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• v.29 no.4
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• pp.361-369
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• 2017

Setting time of cement-based materials can represent a developing strength in early-age mixture, and it can be used a significant parameter of high-performance concrete having various mix-proportions. Generally, initial and final setting time of concrete is measured by penetration resistance method that used a wet-sieving mortar mixture, therefore, it hardly represents the setting time of sound concrete including coarse aggregate. Recently, several nondestructive methods, such as ultrasonic velocity and impendence measurement, are proposed to evaluate the setting time of fresh concrete. This study attempts to measure an electrical resistivity using four-electrode method for evaluation of setting time in early-age cement-based materials. For this purpose, total 10 mixtures are prepared as different mix-proportions including chemical admixture. Based on the experimental results, two electrical parameters, such as initial electrical resistivity and rising time, are proposed to reflect a microstructure development by hydration of cement-based materials. As a result, proposed parameter is also discussed with the measured setting time by penetration resistance method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2C
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• pp.85-93
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• 2010

The shear stiffness has become an important design parameter to understand the soil behavior. In particular, the elastic moduli and void ratio has been considered as important parameters for the design of the geotechnical structures. The objective of this paper is the development of the penetration type Field Velocity and Resistivity Probe (FVRP) which is able to assess the elastic moduli and void ratio based on the elastic wave velocities and electrical resistivity. The elastic waves including the compressional and shear wave are measured by piezo disk elements and bender elements. And the electrical resistivity is measured by the resistivity probe, which is manufactured and installed at the tip of the FVRP. The penetration tests are carried out in calibration chamber and field. In the laboratory calibration chamber test, after the sand-clay slurry mixtures are prepared and consolidated. The FVRP is progressively penetrated and the data are measured at each 1 cm. The field experiment is also carried out in the southern part of Korea Peninsular. Data gathering is performed in the depth of 6~20 m at each 10 cm. The elastic moduli and void ratio are estimated based on the analytical and empirical solutions by using the elastic wave velocities and electrical resistivity measured in the chamber and field. The void ratios based on the elastic wave velocities and the electrical resistivity are similar to the volume based void ratio. This study suggests that the FVRP, which evaluates the elastic wave velocities and the electrical resistivity, may be a useful instrument for assessing the elastic moduli and void ratio in soft soils.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.503-516
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• 2012

Rock mass rating (RMR) is the key factor when designing the appropriate support pattern of tunnel projects. Borehole drilling is usually performed along the tunnel route in order to determine the rock mass rating to be used for tunnel design. The rock mass rating at the non-boring region between boreholes is usually assessed through geophysical surveys such as electrical prospecting, seismic prospecting, etc. Many studies were carried out to find out the correlation between electrical resistivity and rock mass rating. However, most researches were aimed at obtaining the relationship between the two parameters utilizing experimental results obtained from laboratory tests or electrical prospectings. In this paper, efforts were made to analyze and obtain relationships between the electrical resistivity obtained from in-situ electrical resistivity logging data and the rock mass rating. Correlation studies using field data showed that the electrical resistivity is highly correlated with the rock mass rating with the determination coefficient more than 90%. The correlation analysis was also carried out between RMR classification parameters and the electrical resistivity. It was shown that the correlation between the condition of discontinuities and the electrical resistivity was very high with the determination coefficient more than 80%; that between the groundwater condition and the electrical resistivity was very low with the determination coefficient less than 57%.

• Journal of the Korean earth science society
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• v.29 no.6
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• pp.447-453
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• 2008

Recently, the electrical DC survey has frequently been performed to assess the safety of embankment. This study showed that the damaged section of embankment could be appropriately detected by the survey only when the three dimensional effect was correctly considered. The shape of the three dimensional embankment was numerically implemented, and a proper modeling was performed to confirm the effect by analyzing the apparent and inverted true resistivity. Then, the field work was carried out. The three dimensional interpretation distinguished the erroneous weak zones from the geometrical artifact, and the embankment was ensured as safe both by the additional survey performed in rainy season and the partial excavation for direct observation.