• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.1-10
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• 2003

In this paper, the laboratory test results with middle-sired ,soil box test in modeling the in-situ installing of horizontal drains are discussed the estimation of the optimum negative pressure. The test was carried out in the different vacuum pressure conditions together with the measurement for the settlement and volume change of drained water by the installed drains during the consolidation process. After the test, the water content was measured to both directions of lateral distance from the drain and depth of the soil, to find out the distribution of ground improvement and strength enhancement. From the analysis on the distribution of water content, the gradual application of vacuum pressure to higher level by pre-determined stages starting from low vacuum pressure is found to be effective and desirable. In the comparison of the degrees of consolidation with elapsed time, the calculated value by the prediction method based on the Barren's conventional theory showed a good agreement with the measured value. With this, It is positively considered that the applicability of the prediction method based on Barren's theory to the practical design of horizontal drains can be justified such as in the calculation of drain spacing and consolidation period.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.78-81
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• 2015

Pure ZnO and ZnO nanowires doped with 3 wt.% Ga (‘3GZO’) were grown by pulsed laser deposition in a furnace system. The doping of Ga in ZnO nanowires was analyzed by observing the optical and chemical properties of the doped nanowires. The diameter and length of nanowires were under 200 nm and several ${\mu}m$, respectively. Changes of significant resistance were observed and the sensitivities of ZnO and 3GZO nanowires were compared. The sensitivities of ZnO and 3GZO nanowire sensors measured at 300℃ for 1 ppm of ethanol gas were 97% and 48%, respectively.

• Steel and Composite Structures
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• v.13 no.1
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• pp.1-13
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• 2012

In this study, a new structural bracing system named 'Hat Knee Bracing' (HKB) is presented. In this structural system, a special form of diagonal braces, which is connected to the knee elements instead of beam-column joints, is investigated. The diagonal elements provide lateral stiffness during moderate earthquakes. However the knee elements, which is a fuse-like component, is designed to have one plastic joint in the knee elements for dissipation of the energy caused by strong earthquake. First, a suitable shape for brace and knee elements is proposed through elastic studying of the system and several practical parameters are established. Afterward, by developing applicable and highly accurate models in Drain-2DX, the inelastic behavior of the system is carefully considered. In addition, with inelastic study of the new bracing system and comparison with the prevalent Knee Bracing Frame system (KBF model) in nonlinear static and dynamic analysis, the seismic behavior of the new bracing system is reasonably evaluated.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1515-1517
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• 2001

In this work the electrical characteristics of organic TFTs with the semiconductor-insulator interfaces have been interested. Pentacene is used as an active semiconducting layer. The semiconductor layer of pentacene was thermally evaporated in vacuum at a pressure of about $2{\times}10^{-6}$ Torr and at a deposition rate of 0.3$\AA$/sec. Aluminium and gold were used for gate and source/drain electrodes. before pentacene is deposited on the insulator, the gate dielectric surfaces of two samples were rubbed with lateral and perpendicular to direction of the channel length respectively.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.301-302
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• 2006

초고주파 전력 증폭기의 바이어스 전압을 조절하여 온도 변화에 따른 드레인(Drain) 전류의 변화를 억제하기 위한 저가의 능동 바이어스 모듈을 개발한다. 능동 바이어스 모듈을 5 W급 초고주파 전력증폭기에 적용하였을 경우, $0{\sim}60^{\circ}C$까지의 온도변화에 대하여 소모전류 변화량은 0.1 A 이하로 되어야 한다. 본 기술 개발 대상인 능동 바이어스 모듈의 성능 시험을 위한 대상 전력증폭기는 $2.11{\sim}2.17GHz$ 주파수 대역에서 32 dB 이상의 이득과 ${\pm}0.1\;dB$ 이하의 이득 평탄도, -15 dB 이하의 입.출력 반사손실을 가진다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.5
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• pp.80-90
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• 1998

The EPS construction method-one kind of the load reducing methods-utilizes the EPS blocks, ultra-light materials whose unit weight is about 1/100 of soils and has been applied to many soft ground sites. It needed 3,000 days to get the 90% degree of the consolidation for the case of 12m high soil embankments on the 30m thick soft clayey foundations. The N value of SPT at this deposit was less than 5. The pack drain was installed to promote the radial consolidations. Although staged embankments were planned, designers failed to get a sufficient stability of the foundation ground. Therefore, the EPS fill method was selected to reduce the load and the construction period. EPS blocks(D-20 model) replaced the upper part of the soil embankments. These complex embankments reduced the ground settlement and the construction period. The possibility of lateral movements of the bridge abutments was checked and the design scheme was reviewed.

• Journal of Magnetics
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• v.7 no.1
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• pp.4-8
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• 2002

The magnetoresistance (MR) and the magnetization reversal of a lateral spin-injection device based on a spin-polarized field effect transistor (spin FET) have been investigated. The device consists of a two-dimensional electron gas (2DEG) system in an InAs single quantum well (SQW) and two ferromagnetic $(Ni_{80}Fe_{20})$ contacts: all injector (source) and a detector (drain). Spin-polarized electrons are injected from the first contact and, after propagating through the InAs SQW are collected by the second contact. By engineering the shape of the permalloy contacts, we were able to observe distinct switching fields $(H_c)$ from the injector and the collector by using scanning Kerr microscopy and MR measurements. Magneto-optic Kerr effect (MOKE) hysteresis loops demonstrate that there is a range of magnetic field (20~60 Oe), at room temperature, over which the magnetization in one contact is aligned antiparallel to that in the other. The MOKE results are consistent with the variation of the magnetoresistance in the spin-injection device.

• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.317-321
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• 2011

Objective : External ventricular drain (EVD) is commonly performed with a freehand technique using surface anatomical landmarks at two different cranial sites, Kocher's point and the forehead. The aim of this study was to evaluate and compare the accuracy and safety of these percutaneous ventriculostomies. Methods : A retrospectively review of medical records and head computed tomography scans were examined in 227 patients who underwent 250 freehand pass ventriculostomy catheter placements using two different methods at two institutions, between 2003 and 2009. Eighty-one patients underwent 101 ventriculostomies using Kocher's point (group 1), whereas 146 patients underwent 149 forehead ventriculostomies (group 2). Results : In group 1, the catheter tip was optimally placed in either the ipsilateral frontal horn or the third ventricle, through the foramen of Monro (grade 1) in 82 (81.1%) procedures, in the contralateral lateral ventricle (grade 2) in 4 (3.9%), and into eloquent structures or non-target cerebrospinal space (grade 3) in 15 (14.8%). Intracerebral hemorrhage (ICH) >1 mL developed in 5 (5.0%) procedures. Significantly higher incidences of optimal catheter placements were observed in group 2. ICH>1 mL developed in 11 (7.4 %) procedures in group 2, showing no significant difference between groups. In addition, the mean interval from the EVD to ventriculoperitoneal shunt was shorter in group 2 than in group 1, and the incidence of EVD-related infection was decreased in group 2. Conclusion : Accurate and safe ventriculostomies were achieved using both cranial sites, Kocher's point and the forehead. However, the forehead ventriculostomies provided more accurate ventricular punctures.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.281-292
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• 2008

Prefabricated Board Drains (PBDs) recently become more widely used than conventional sand drains in improving soft ground because the PBD is more time and cost effective. The performance of PBDs is affected by disturbance in the adjacent soil formation during inserting mandrels, the intrusion of fine particles into filter fabric, and necking of the drain by excessive lateral pressure especially occurring in very deep clay formation such as the Busan New Port site. In this study, the PBD with double-core is introduced, which seems to overcome the shortcomings of usual single-core PBDs. An in-situ test program was established in the Busan New Port site, in which a set of the double-core PBDs and the single-core PBDs was installed to compare the efficiency of each of the drains. The discharge capacity of the double-core and the single-core PBDs was compared for various confining pressures in the modified Delft test and the chamber test. A series of CRS consolidation tests was performed in order to obtain profiles of void ratio-effective stress and void ratio-permeability relationships in the Busan New Port site that are used as input date in performing a numerical program ILLICON. The numerically simulated settlements of ground surface in the test site are in good agreement with those of in-situ measurements. In addition, the performance of the double-core and single-core PBDs has been experimentally and numerically compared in this paper.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.15-27
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• 2013

A vacuum pressure method has been developed to solve many problems in the conventional surcharge method such as embankments, and its application has increased in the country. Recently, to control target settlements in the field, there have been many studies on the comparison of settlements between vacuum pressure method and surcharge load method in the same conditions. In this study, the settlement characteristics of soil subjected to vacuum pressure and surcharge pressure are discussed. The results indicate that if vacuum pressure is applied to the improvement of soft ground, there will be inward lateral displacement and the vacuum pressure will induce generally less settlement than a surcharge load of the same magnitude. The range of settlement reduction ratio is 0.54~0.67 based on Hooke's law, 0.91 based on field cases, 0.81 based on laboratory oedometer tests, 0.75 based on the theory of elasticity and coefficient of volumetric compressibility and 0.77~0.93 in its recent applications to the thick soft ground.