• 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 Korean Geotechnical Society
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• v.15 no.1
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• pp.185-196
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• 1999

A laboratory experiment was performed to examine the relationship between resistivity and ionic components in the pore water of a sand by using soil resistivity test box and STING-Rl. The resistivity measurement was performed with the concentration changes of ionic components. Also, the resistivity change was evaluated for multiple components. The results showed that the resistivity of Arsenic was less than other heavy metals. In the case of complex components, resistivity ranges depended on the resistivity of components existed in the pore water.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.97-106
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• 1994

The dependence of the electrical resistivity on the eutectic composition and growth rates was investigated in the unidirectionally solidified Sb-InSb and Sn-Bi eutectic alloy systems, which were generally classified into the groups of f-f and nf-f eutectic system. Sb-InSb alloys containing 26-34wt.% In and Sn-Bi alloys containing 53-65wt.%Bi were prepared in vacuum sealed in a silica tube, and then these were unidirectionally solidified. Electrical resistivity of the specimens prepared by cutting the crystal section in parallel with the transverse direction and by cutting in longitudinal direction was measured. As the growth rate increased, the Sb-InSb and Sn-Bi eutectic alloys showed that the resistivity of longitudinal to the growth direction was increased but that of transverse to the growth direction was decreased. In the case of Sb-InSb eutectic alloy, increas~ng the phase boundary area and decreasing the fiber directionallity caused to increase the $p \; \parallel$ , while increasing the phase boundary area increased the $p \; \\perp$ As expected, the eutectic microstructure could be analysed well in terms of electrical resistivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.42-43
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• 2009

본 연구에서는 고주파 마그네트론 스퍼터링방법을 사용하여 ITO박막을 대체할 수 있는 새로운 TCO박막으로서 $TiO_2$가 도핑된 ZnO(TZO) 박막을 성막하였다. 이때, $TiO_2$의 도핑량을 1wt.%에서 5wt.%까지 변화를 주었으며 제작된 TZO 박막에 대해서 전기적 특성과 광학적 특성들의 조성비와 박막두께의 할수로서 조사하였다. 그 결과, $TiO_2$가 2wt.% 도핑된 박막에서 가장 낮은 $1\times10^{-3}\Omega{\cdot}cm$의 비저항이 얻어졌으며, $TiO_2$의 도핑량이 증가함에 따라 비저항은 점점 증가하는 것으로 나타났다. 이와같은 비저항의 변화는 $TiO_2$도핑량이 다른 TZO박막의 홀이동도(Hall mobility)에 비례하며, 이동도는 결국 TZO박막을 형성하고 있는 결정립의 크기에 의존하는 것이 X선 회절 패턴으로부터 확인되었다. XRD 패턴에서 ZnO(002) 방향의 결정성이 가장 큰 것으로 나타났으며, 도핑량이 증가할수록(002)피크의 크기가 점점 감소하는 것을 볼 수 있다. 이는 결정성의 크기가 2wt.%일 때 가장 크며 도핑량이 증가할수록 결정성의 크기가 감소하는 것으로 나타났다. 결정립의 크기변화는 TZO박막의 전기적 이동도에 영향을 주는 것으로 나타난다. 즉, 2wt.%일 때 이동도가 가장 크며 도핑량이 증가할수록, 이동도가 감소하였으며 이결과는 TZO박막의 Hall effect 측정으로부터 확인된다. 따라서, $TiO_2$도핑량에 따른 TZO 박막의 비저항을 도핑량이 2wt.%일 때 가장 낮으며 이는 TZO 박막의 결정성이 가장 우수하였으며 그결과 이동도가 증가했기 때문인 것으로 확인되었다.

• Geophysics and Geophysical Exploration
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• v.9 no.2
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• pp.155-162
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• 2006

An abnormal seepage flow, which is mainly caused by the piping, is one of the major reasons for embankment dam failure. A leakage detection is therefore a vital part of an embankment dam's monitoring. Resistivity method, which is an efficient tool to detect leakage zones, has been used all over the world for an embankment dam's monitoring. Although the resistivity method gives us very useful information about the leakage problem, there is no more quantitative interpretation than the low resistivity zones in the 2-dimensional resistivity section are regraded simply as the anomalous seepage zones. Recently, resistivity monitoring technique is applied for the detection of leakage zones. However, its interpretation still remains in the stage of presenting the resistivity ratio itself. An increased seepage flow increases a porosity and an increasing porosity decreases the dam's stability. Therefore, the porosity is one of the major factors for an embankment dam's stability. Based on Archie's experimental formula, we try to evaluate a porosity distribution from the resistivity data which is obtained on the dam's crest. We also attempt to represent a procedure to evaluate a safety index of the embankment dam from the resistivity monitoring data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1C
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• pp.45-51
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• 2010

In urban area, design and construction of civil engineering structures such as subway tunnel, underground space and deep excavation is impeded by unreliable site investigation. Variety of embedded objects, electric noises and traffic vibrations degrades the quality of site investigation, whatever the site-investigation technique would be. In this research, a preliminary research was performed to develop a dedicated site investigation technique for urban geotechnical sites, which can overcome the limitations of urban sites. HiRAS (Hybrid Integration of Surface Waves and Resistivity) technique which is the first outcome of the preliminary research was proposed in this paper. The technique combines surface wave as well as electrical resistivity. CapSASW method for surface-wave technique and PDC-R technique for electrical resistivity survey were incorporated to develop HiRAS technique. CapSASW method is a good method for evaluating material stiffness and PDC-R technique is a reliable method for determination of underground stratification even in a site with electrical noise. For the inversion analysis of HiRAS techniuqe, a site-specific relationship between stress-wave velocity and resistivity was employed. As for outgrowth of this research, the 2-D distribution of Poisson's ratio could be also determined.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.115-115
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• 2007

PRAM (Phase Change Random Access Memory)은 상변화 물질의 비저항 차이를 이용한 메모리 소자로 차세대 비휘발성 메모리로 주목받고 있다. 현재 상변화 물질로 사용되고 있는 $Ge_2Sb_2Te_5$ 박막은 결정질 상태에서 저항이 낮아 RESET 동작에서 많은 전력이 소비되고 메모리의 고집적의 어려움이 있다. 이러한 문제를 해결하기 위해 상변화 물질의 개선과 소자 구조의 개선 등의 새로운 접근이 시도되고 있다. 본 연구에서는 $Ge_2Sb_2Te_5$ 박막의 전기적 특성을 개선하기 위해서 이종 원소인 질소를 첨가한 N-doped $Ge_2Sb_2Te_5$ 박막에 대한 특성을 살펴 보았다. $SiO_2$/Si 기판 위에 100 nm 두께의 박막을 D.C. magnetron sputter 방법으로 증착하여, 질소 분위기 $100^{\circ}C{\sim}300^{\circ}C$온도 구간에서 열처리하였다. 열처리에 따른 박막 특성을 관찰하기 위해 면저항 측정, XRD, TEM 분석을 통해 박막 특성을 관찰하였다. 면저항 측정과 XRD peak 분석을 통해 $Ge_2Sb_2Te_5$ 시스템에 비하여 N-doped $Ge_2Sb_2Te_5$ 시스템의 결정화 온도가 상승하였음을 확인하였다. 면저항은 첨가된 질소의 조성이 증가할수록 증가하였고, FCC 상에서 HCP 상으로의 상변화 온도 역시 증가하였다. 첨가된 질소가 $Ge_2Sb_2Te_5$, 박막의 결정 성장을 억제하였고, 상대적으로 높은 저항을 가지고 안정한 FCC상을 고온 열처리 이후에도 유지하였다. 질소 첨가를 이용한 상변화 물질의 열안정성 향상과 저소비전력 구동을 통해 향후 고집적 상변화 메모리에의 적용이 가능하다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4C
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• pp.117-125
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• 2011

The practical use of the electrical resistivity, which can makes the acquirement of the high resolution data in specific area, is increased in order to obtain a reasonable data for a ground investigation. The objective of this study is development of TRPF(Temperature-compensated Resistivity Probe for Field test), and an application in the field test for obtaining a reliable electrical resistivity value about considering the temperature effects. Temperature sensor is attached at 15mm, 30mm, 90mm below from the cone tip in consideration with the results of temperature transient process of cone probe and safety, and the angle of cone tip is $60^{\circ}$ for geometrical reason and minimizing the disturbance during the penetration test. Diameter of the cone probe is equally 35.7mm and penetration rate is 2 cm/sec for a comparison with standard cones such as CPT and SPT, and others. The temperature change is instantly observed around $4^{\circ}C$ when touching the ground, and the comparing results among the other cones indicates that the temperature compensation should be conducted in the ground survey using the electrical resistivity. This study shows that the necessity of temperature effects compensation during penetration test through the development and field verification of TRPF (Temperature-compensated Resistivity Probe for Field test).

• The Journal of Engineering Geology
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• v.7 no.2
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• pp.113-126
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• 1997

Electrical resistivity methods of dipole - dipole array profiling and Schiumberger array sounding were tested on a segment of the Woraksan granitic batholith for the research into the imaging of irregular attitudes of fracture zones in the crystaaline rock in terms of processing and interpretation schemes. By the dipole - dipole array method, inhomogeneities such as small scale of fracture zones were properly delineated down at some depth even within hard rock environment. Fracture zones were interpreted to be at the boundaries between the high amplitude zone and very low amplitude zone in the resistivity plot and they were also successfully outlined in two - dimensional layer and pseudo - three - dimensional volume constructed by the incorporation of vertical sounding data. The surface location of the fracture zones was correlated by the zero - crossing point in the VLF(very low frequency) electromagnetic data. Pseudo - three - dimensional attitudes of fracture zones were efficiently illuminated by optimum projection angle. The mean of bulk resistivity for the Woraksan granite and the near fracture zones is estimated to be approximately of 4,000 ohm - m which is much higher than the value of 700 ohm - m for the Rwachunri limesilicate environment. This difference is due to both the rock type, i.e., biotite granite vs limesilicate, and the occurrence of secondary openings of fold and fault associated with the intrusion of granite. In this study statistical analyses on the resistivity color plot were performed in terms of three representative statistical moments, i.e., standard deviation, skewness, and kurtosis. The fracture zones in the standard deviation plot were characterized by the higher value, compared to the value of homogeneous portion. The upper boundary of the high resistivity zone was also successfully delineated in the skewness and kurtosis plots.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.169-169
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• 2009

ZnO varistor에서 희토류 산화물의 첨가는 비선형계 높게 만든다. 회토류 금속의 첨가로 높아진 비저항을 낮추기 위하여 3족 원소인 Al, Ga을 첨가하여 첨가 함량에 따른 ZnO-$Pr_6O_{11}$ varistor의 비저항을 낮추고자 한다. 따라서 본 연구에서는 Al과 Ga 첨가에 따른 ZnO-$Pr_6O_{11}$을 일반적인 세라믹 공정에 따라 제조하여, Al과 Ga 첨가에 따른 ZnO-$Pr_6O_{11}$ varistor의 특성을 미세구조 조직, 밀도, I-V 특성, 비저항 측정하였다. ZnO의 bulk 및 grain boundary 특성 변화를 각종 유전함수($Z^*$, $Y^*$, $M^*$, $\varepsilon^*$, $tan{\delta}$)를 이용하여 고찰하였다.