• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.299-304
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• 2016

2차원 반도체 소재의 경우 물질종류마다 내포하고 있는 고유결함에 의해서 Fermi-Level Pinning 이 발생하여 이로 인한 Schottky Barrier transistor로 동작을 하게 되며, 이는 접합부에 Carrier Injection 정도와 Schottky Barrier을 통과하는 Tunneling 정도에 의해서 소자의 특성이 결정 된다. 본 연구에서는 시뮬레이션을 통하여 2차원 반도체인 $MoS_2$소자를 설계하고, S/D Doping에 따라 접촉 저항 개선 효과와 소자의 동작특성이 어떠한 영향을 미치는지 연구하여 최대 $250cm^2/V{\cdot}sec$의 field effect mobility 의 결과를 얻었다. 또한 S/D doping 에 따라 각 저항 성분의 영향을 분석하였으며 면저항 및 접촉 저항 둘 다 doping 농도가 증가함에 따라 감소하는 결과를 나타내며, S/D doping의 영향은 접촉저항에서 더 크게 나타났다. 더불어 2차원 반도체의 Resistance network model 을 제안하여 subthreshold 영역에서는 $R_{ic}$, saturation 영역에서는 $R_{ish}$ 가 전체저항에서 주요한 변수로 전체저항식에 포함되어야 한다는 것을 시뮬레이션을 통해서 검증하였다.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.927-929
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• 2003

The rib in synchronous reluctance motor(SynRM), which has segment type rotor, is mechanical weak Point. To make up for the weak point, a web has inserted in the flux barrier. However, the inductance in the q-axis is increased and then the motor performance has been decreased because of the inserted web. This paper presents a model, which has permanent magnets on the both side of the web, to decrease the inductance in the q-axis. The finite element method is applied to analyze the characteristics.

• Journal of Drive and Control
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• v.14 no.4
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• pp.61-70
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• 2017

In this study, an extended-state-observer (ESO) based non-linear servo control is introduced for an electro-hydrostatic actuator (EHA). Almost hydraulic systems not only are highly non-linear system that has mismatched uncertainties and external disturbances, but also can not measure some states. ESO that only use an output signal can be used to compensate these uncertainties and estimate unmeasurable states. To improve the position tracking performance, the barrier Lyapunov function (BLF) that can guarantee an output tolerance is introduced for the position tracking error signal of back stepping control procedures. Finally, the proposed servo control is compared with the proportional-integral (PI) control.

• Journal of the Korean Wood Science and Technology
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• v.32 no.6
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• pp.50-56
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• 2004

This study was conducted to investigate the performance of sound absorption type-noise barriers manufactured with a combination of wood particles used for particleboard, recycled waste newspaper, and cement. An average density of wood-combined cement board was in the range from 0.83 to 0.96 g/cm³, showing relatively low-density board. Regardless of types of cement bonded board or wooden board, the board with concave holes(凹)-formed surfaces showed greater sound absorption coefficient compared to those of flat surface boards. The board density was not related with those coefficients. Accordingly, it was concluded that concave or deep corrugated surface structure has played an important role in sound absorption for the application of sound absorption type-noise barrier.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1191-1198
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• 2023

Bentonite buffer material is a critical component in an engineered barrier system (EBS) for disposing high-level radioactive waste (HLW). The bentonite buffer material protects the disposal canister from groundwater penetration and releases decay heat to the surrounding rock mass; thus, it should possess high thermal conductivity, low hydraulic conductivity, and moderate swelling pressure to safely dispose the HLWs. Bentonite clay is a suitable buffer material because it satisfies the safety criteria. Several additives have been suggested as mixtures with bentonite to increase the thermal-hydraulic-mechanical-chemical (THMC) properties of bentonite buffer materials. Therefore, this study investigated the geotechnical, mineralogical, and THMC properties of several candidate additives such as sand, graphite, granite, and SiC powders. Datasets obtained in this study can be used to select adequate additives to improve the THMC properties of the buffer material.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2
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• pp.133-141
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• 2020

A geological repository comprises a natural barrier and an engineered barrier system. Its design components consist of canisters, buffers, backfill, and near-field rock. Among the engineered barrier system components, bentonite buffers minimize the groundwater flow from near-field rock and prevent the release of nuclide. Investigation of the hydraulic conductivity of the buffer to groundwater flow is an important factor in the performance evaluation of the stability and integrity of the engineered barrier of the repository. In this study, saturated hydraulic conductivity tests were performed using Gyeongju bentonite at various dry densities and temperatures, and a hydraulic conductivity prediction model was developed through multiple regression analysis using the 120 result sets of hydraulic conductivity. The test results showed that the hydraulic conductivity tends to decrease as the dry density increases. In addition, the hydraulic conductivity increased with increasing temperature. The multiple regression analysis results showed that the coefficient of determination (R²) of the hydraulic conductivity prediction equation was as high as 0.93. The hydraulic conductivity prediction equation presented in this study could be used for the design of engineered barrier systems.

• Membrane Journal
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• v.33 no.6
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• pp.447-453
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• 2023

The performance of computer systems and the development of various computer simulation programs have made it possible to analyze chemical systems composed of more complex elements, and accordingly, research using molecular dynamics simulation is being actively conducted. Research on calculating the gas permeation characteristics of polymer membranes by molecular dynamics, which was previously conducted mainly through experiments, is receiving attention for gas barrier membranes used in food packaging and pharmaceuticals. Recently, there has been a report that a gas barrier effect appears when a coating film is made using silk fibroin, and in this study, a study was conducted using molecular dynamics simulation to confirm whether an oxygen barrier effect appears when a composite film is made using silk fibroin. We built a single model, calculated the gas permeation characteristics, and compared it with the experimental value to confirm that the model reflects the actual experimental results. Actual composite membrane models were then built and the gas movement path within the polymer was analyzed. As a result, oxygen molecules were found that they could not pass through and was blocked in the fibroin region. Therefore, the composite membrane with silk fibroin has excellent oxygen barrier property and is expected to be useful in food packaging, etc.

• Journal of Broadcast Engineering
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• v.17 no.5
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• pp.817-826
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• 2012

This paper presents a robust viewpoint estimation algorithm for Moving Parallax Barrier mobile 3D display in sudden illumination changes. We analyze the previous viewpoint estimation algorithm that consists of the Viola-Jones face detector and the feature tracking by the Optical-Flow. The sudden changes in illumination decreases the performance of the Optical-flow feature tracker. In order to solve the problem, we define a novel performance measure for the Optical-Flow tracker. The overall performance can be increased by the selective adoption of the Viola-Jones detector and the Optical-flow tracker depending on the performance measure. Various experimental results show the effectiveness of the proposed method.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.147-152
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• 2002

In the preceding tests of Sub.(Ⅰ) engines, it was observed that the heat resistant capability of the engines was not enough, and the design of Sub.(Ⅰ) engines was modified to satisfy the mission requirement. Sub.(Ⅰ) Mod. engines have three major design parameters - the arrangement of main injectors, the impinging angle of main injectors and thermal barrier coating. More than 20 experiments were carried out to evaluate engine performance and heat resistance capability with respect to design parameters. Analysing the result of Sub.(Ⅰ) and Sub.(Ⅰ) Mod. engine tests, it is found that the decreased impinging angle, adopting the H-type arrangement(rather than radial type arrangement), and adopting the thermal barrier coating can increase heat resistance capacity substantially. The result show that the performance variation by design change is below 5 percents and the radial type arrangement of injectors has higher performance than H-type. However, the performance of 15°impinging angle engine is higher than that of 20°impinging angle engine, which is inconsistent to our expectation. High frequency instabilities may cause such phenomenon, which will be verified by a series of tests.

• Culinary science and hospitality research
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• v.17 no.5
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• pp.139-153
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• 2011

The study is a hotel firm's brand evidence on the switching and relational performance by identifying a causal relationship to the differentiated and competitive was to provide useful information. Units of samples for evidence of brand switching hotels in Seoul participated in surveys customers in 2011, from June 10 to 20 July 2011 for a total of 500 copies for distribution and the Department of dual 408 with SPSS 18.0 and AMOS 18.0 Using factor analysis and reliability verification carried out, and presented research in order to test the hypothesis covariance structure analysis was performed. Analysis, employee services switching barriers and switching costs showed no significant affect. Switching barriers and switching costs, brand name, image congruence transition castle wall and switching costs, alternative attractiveness showed no significant visible results. And perceived price on switching barriers to conversion rates showed was significant affect. Second, switching barriers, switching costs, alternative attractiveness and that the relationship, to help conversion of non-financial performance showed no significant affect. Third, the practitioner services, brand names, images, match the castle there, and non-financial performance of the transition showing a statistically significant result was found.