• Macromolecular Research
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• v.17 no.10
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• pp.797-806
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• 2009

The mechanical and thermal behaviors of polyamide-6/clay nanocomposites were studied using the continuum-based, micromechanical models such as Mori-Tanaka, Halpin-Tsai and shear lag. Mechanic-based model prediction provides a better understanding regarding the dependence of the nanocomposites' reinforcement efficiency on conventional filler structural parameters such as filler aspect ratio ($\alpha$), filler orientation (S), filler weight fraction (${\Psi}_f$), and filler/matrix stiffness ratio ($E_f/E_m$). For an intercalated and exfoliated nanocomposite, an effective, filler-based, micromechanical model that includes effective filler structural parameters, the number of platelets per stack (n) and the silicate inter-layer spacing ($d_{001}$), is proposed to describe the mesoscopic intercalated filler and the nanoscopic exfoliated filler. The proposed model nicely captures the experimental modulus behaviors for both intercalated and exfoliated nanocomposites. In addition, the model prediction of the heat distortion temperature is examined for nanocomposites with different filler aspect ratio. The predicted heat distortion temperature appears to be reasonable compared to the heat distortion temperature obtained by experimental tests. Based on both the experimental results and model prediction, the reinforcement efficiency and heat resistance of the polyamide-6/clay nanocomposites definitely depend on both conventional (${\alpha},\;S,\;{\Psi}_f,\;E_f/E_m$) and effective (n, $d_{001}$) filler structural parameters.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1281-1283
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• 2007

In this paper, the properties of n-channel poly-Si TFTs with different channel widths are reported. Poly-Si fabricated using ELA on glass substrates has high quality as a material for applications such as TFT-LCDs. The fabricated n-channel TFTs have a double stack structure of oxide-nitride which acts as an insulator layer. The results show that the small channel TFTs exhibited a lower $V_{TH}$ and the wide channel TFTs had a higher $I_{DSAT}$. The nchannel poly-Si TFTs with an $I_{ON}/I_{OFF}$ value of more than $10^4$ can be reliable switching devices for AMOLED displays.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.3
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• pp.248-252
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• 2005

The effects of electric field strength and mechanical compressive stress on the displacement of multilayered ceramic actuator, stacked alternatively 0.2 (PbM $n_{1}$3/N $b_{2}$3/ $O_3$)-0.8(PbZ $r_{0.475}$ $Ti_{0.525}$ $O_3$) ceramic thin films and 70Ag-30Pd electrodes were investigated. Because the actuators were designed to stack ceramic layer and electrode layer alternatively, the ceramic-electrode interfaces may act as a resistance to motion of domain wall. so the polarization and strain were affected by the amount of 180$^{\circ}$domain, electric field strength and mechanical compressive stress. Consequently, the change of polarization, displacement with respect to field strength, and mechanical compressive stress were likely to be caused by readiness of the domain wall movement around the ceramic-electrode interfaces.ces.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.67-78
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• 1984

EAROM device is an n-channel MOS transistor with a control gate stack ed on the floating gate. On account of channel injection type, channel lengths are designed 4-8 $\mu$m and chinnel widths 5-14 $\mu$m. These devices which have fourstructures of different type control gate are designed by NMOS 5 $\mu$m design rule and fabricated by double polysilicon gate NMOS Process. Double ion implantation is applied to increase punchthrough voltage and gate-controlled channel breakdown voltage. The drain and gate voltage for programming was 13-17V and 20-25V, respectively. EPROM cell fabricated could be erased not by optical method but by electrical method. The result of charge retention test showed decrease in stored charges by 4% after 200 hours at 1$25^{\circ}C$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1302-1308
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• 2010

In this study, Zigbee Sensor Node to transmit harmful gases CO and $CO_2$ information using wireless communication within the ground and underground structures were developed. Wireless communication protocol was used Zigbee Stack included IEEE 802. 15.4 MAC protocol. For wireless transmission of detected harmful gas signal from ADC of MCU was implemented Zigbee Sensor Node that was developed protocol using Serial-Port-Profile(SPP) here. The proposed Zigbee Sensor Node was verified transmission distance from experiments. Transmission distance was into 90m in experiments. Distance experiments were measured at 10m intervals using sine & pulse wave input signal at indoors. The proposed Route Sensor Node was applied mesh routing protocol. When built up USN(Ubiquitous Sensor Network)using Route Sensor Node, transmission distance was not limited. On the experimental results, harmful gas values between direct measurements and USN measurements were consistent. The semiconductor CO sensor and N-DIR $CO_2$ sensor module as a harmful sensor was used. Therefore, the proposed Zigbee Sensor Node was verified about reliability and validity to build USN for transmission of harmful gas information.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1722-1724
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• 2005

The focus of this paper is to develop a mathematical model for investigating the dynamic performance of a polymer electrolyte membrane fuel cell. The model in this work is based on physical laws having clear significance in replicating the fuel cell system and can easily be used to set up different operational strategies. Simulation results display the transient behavior of the voltage within each single cell, and also within a number of such single cells combined into a fuel cell stack system. A linear as well as a nonlinear analysis of the polymer electrolyte membrane fuel cell system(PEMFC) has been discussed in order to present a complete and comprehensive view of this kind of modeling. Also, a comparison of the two kinds of analysis has been performed. Finally, the various characteristics of the fuel cell system are plotted in order to help us understand its dynamic behavior. Results indicate that there is a considerable amount of error in the modeling process if we use a linear model of the fuel cell. Thus, the nonlinearities present in the fuel cell system should be taken into account in order to obtain a better understanding of the dynamic behavior of the fuel cell system.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.187-187
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• 2010

In this study, we investigated the effect of electrodes on resistance switching of TaOx film. Pt, Ni, TiN, Ti and Al metal electrodes having the different oxidation degree were deposited on TaOx/Pt stack. Unipolar resistance switching behavior in Pt or Ni/TaOx/Pt MIM stacks was investigated, but bipolar resistance switching behavior in TiN, Ti or Al /TaOx/Pt MIM stacks was shown. We investigated that the voltage dependence of capacitance was decreased with higher oxidation degree of metal electrodes. Through the C-V results, we expected that linearity ($\alpha$) and quadratic ($\beta$) coefficient was reduced with an increase of interface layer between top electrode and Tantalum oxide. Transmission Electron Microscope (TEM) images depicted the thickness of interface layer formed with different oxidation degree of top electrode. Unipolar resistance switching behavior shown in lower oxidation degree of top electrode was expected to be generated by the formation of the conducting path in TaOx film. But redox reaction in interface between top electrode and Tantalum oxide may play an important role on bipolar resistance switching behavior exhibited in higher oxidation degree of top electrode. We expected that the resistance switching characteristics were determined by oxidation degree of metal electrodes.

• Convergence Security Journal
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• v.20 no.4
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• pp.177-186
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• 2020

In current public blockchain, any node can see every blocks, so that public blockchain provider transparent property. However, some application requires the confidential information to be stored in the block. Therefore, this paper proposes a multi-layer blockchain that have the public block layer and the private block for confidential information. This paper suggests the requirement for encryption of private block. Also, this paper shows the t-of-n threshold cryptosystem without dealer who is trusted third party. Moreover, the delegated node who has key information can be withdraw the delegated node group or a new delegated node can join in the delegated node group. Therefore, the paper proposes an efficient key information resharing scheme for withdraw and join. Finally proposed scheme satisfies the requirements for encryption and fairness.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.494-497
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• 2011

함수 복귀 예측은 이론적으로 오버플로가 발생하지 않는 한도 내에서 100%의 정확도를 보여야 한다. 하지만, 투기적 실행을 지원하는 현대 마이크로프로세서 환경 하에서는 잘못된 실행 경로로의 수행 결과를 무효화 할 때 RAS의 오염이 발생하며, 이는 함수 복귀 주소의 예측 실패로 이어진다. 본 논문에서는 이러한 RAS의 오염을 방지하기 위하여 RAS 재명명 기법을 제안한다. RAS 재명명 기법은 RAS의 스택을 소프트 스택과 하드 스택으로 나누어 관리한다. 소프트 스택은 투기적 실행에 의한 데이터의 변경을 복구할 수 있는 항목을 관리하고, 하드 스택은 소프트 스택의 크기 제한으로 겹쳐쓰기가 일어나는 데이터 가운데 이후에 재사용될 데이터를 관리하는 구조로 구성된다. 제안된 기법을 모의실험 한 결과, RAS 오염방지 기법이 적용되지 않은 시스템과 비교하여 함수 복귀 예측 실패를 약 1/90로 감소시켰으며, 최대 6.95%의 IPC 향상을 가져왔다.

• Journal of Korean Library and Information Science Society
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• v.9
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• pp.213-240
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• 1982

Today, one of the major pressures that libraries have been facing is the rapid growth of publications. Due to the rapid growth of publications, libraries have been faced the shortage of stack as well as quality deterioration of library collections. Naturally, these disa n.0, ppointed the users and made the present library activities weak and inadequate. One of the desirable actions in remedying these problems is to weed library collections properly and regularly. Weeding methods used in libraries are derived from the judgement by subject specialists, from the examining the imprint date and the past use patterns of a volume. Among these methods, the past use patterns are highly predictive of the future use, and can be used to create meaningful weeding criteria. Since the libraries in Korea have emphasized on numbers of library collection in the past, the libraries have neglected weeding library collections. Now, we must turn our concern toward the weeding library collections, and the attitude of the library services to the users must change from passive to active.