• 한국전기전자재료학회논문지
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• 제11권1호
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• pp.33-40
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• 1998

The composite SiO$_2$/Si$_3$N$_4$/SiO$_2$(ONO) film formed by oxidation on nitride film has been widely studied as DRAM stacked capacitor multi-dielectric films. Load lock(L/L) LPCVD system by HF cleaning is used to improve electrical capacitance and to scale down of effective thickness for memory device, but is brings a new problem. Nitride film deposited using HF cleaning shows selective deposition on poly silicon and oxide regions of capacitor. This problem is avoidable by carpeting chemical oxide using $H_2O$$_2$cleaning before nitride deposition. In this paper, we study the limit of nitride thickness for abnormal oxidation and the initial deposition time for nitride deposition dependent on underlayer materials. We proposed an advanced fabrication process for stacked capacitor in order to avoid selective deposition problem and show the usefulness of nitride deposition using L/L LPCVD system by $H_2O$$_2$cleaning. The natural oxide thickness on polysilicon monitor after HF and $H_2O$$_2$cleaning are measured 3~4$\AA$, respectively. Two substrate materials have the different initial nitride deposition times. The initial deposition time for polysilicon is nearly zero, but initial deposition time for oxide is about 60seconds. However the deposition rate is constant after initial deposition time. The limit of nitride thickness for abnormal oxidation under the HF and $H_2O$$_2$cleaning method are 60$\AA$, 48$\AA$, respectively. The results obtained in this study are useful for developing ultra thin nitride fabrication of ONO scaling and for avoiding abnormal oxidation in stacked capacitor application.

• 한국정보전자통신기술학회논문지
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• 제9권1호
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• pp.120-131
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• 2016

본 논문에서는 back-gate bias 전압인 VNN (Negative Voltage)을 이용하여 5V의 MV (Medium Voltage) 소자만 이용하여 FN (Fowler-Nordheim) tunneling 방식으로 write하는 MTP cell을 사용하여 512비트 MTP IP를 설계하였다. 사용된 MTP cell은 CG(Control Gate) capacitor, TG(Tunnel Gate) transistor와 select transistor로 구성되어 있다. MTP cell size를 줄이기 위해 TG transistor와 select transistor를 위한 PW(P-Well)과 CG capacitor를 위한 PW 2개만 사용하였으며, DNW(Deep N-Well)은 512bit MTP cell array에 하나만 사용하였다. 512비트 MTP IP 설계에서는 BGR을 이용한 voltage regulator에 의해 regulation된 V1V (=1V)의 전압을 이용하여 VPP와 VNN level detector를 설계하므로 PVT variation에 둔감한 ${\pm}8V$의 pumping 전압을 공급할 수 있는 VPP와 VNN 발생회로를 제안하였다.

• 센서학회지
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• 제24권2호
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• pp.131-136
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• 2015

This paper presents a wide dynamic range complementary metal oxide semiconductor (CMOS) image sensor with column capacitor and feedback structure. The designed circuit has been fabricated by using $0.18{\mu}m$ 1-poly 6-metal standard CMOS technology. This sensor has dual mode operation using combination of active pixel sensor (APS) and passive pixel sensor (PPS) structure. The proposed pixel operates in the APS mode for high-sensitivity in normal light intensity, while it operates in the PPS mode for low-sensitivity in high light intensity. The proposed PPS structure is consisted of a conventional PPS with column capacitor and feedback structure. The capacitance of column capacitor is changed by controlling the reference voltage using feedback structure. By using the proposed structure, it is possible to store more electric charge, which results in a wider dynamic range. The simulation and measurement results demonstrate wide dynamic range feature of the proposed PPS.

• 한국항공우주학회지
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• 제39권2호
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• pp.106-113
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• 2011

본 논문에서는 균일 열부가 하중을 받는 사각판의 자유 진동특성을 실험을 통하여 연구하였다. 사각판의 재질은 알루미늄, 강재 및 스테인레스 강이고 사각판의 재원은 0.1 $\times$ 0.1 $\times$ 0.002 m 이다. 열부가 하중을 위해 적외선 석영 램프를 사용하였고, 전력조절을 위해 PCS(Power Control System)을 사용하였으며, 주파수 함수를 얻기 위해 비접촉식 진동측정 장비를 사용하였다. 부가한 온도 조건은 상온에서부터 $300^{\circ}C$까지 $50^{\circ}C$간격으로 부가하였다. 경계조건은 번지코드를 사용하여 자유-자유 조건을 구현하였다. 사각판의 전면 전체를 균일하게 가열하였다.

• 자원리싸이클링
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• 제26권1호
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• pp.16-21
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• 2017

본 연구는 SiC 결정 성장을 위한 원료 분말 합성법에 관한 것이다. ${\beta}-SiC$ 분말들은 높은 온도 조건(>$1400^{\circ}C$)에서 실리콘 분말과 탄소 분말의 반응에 의해서 합성 된다. 이 반응은 진공 상태(또는 Ar 가스 분위기)에서 실리콘+탄소 혼합물이 반응하고 다결정의 SiC 분말을 형성하기 충분한 횟수를 거쳐 그라파이트 도가니 안에서 진행된다. 최종 결과물의 특성들은 X-ray 회절, SEM/EDS, 입도 분석 및 ICP-OES을 통해 분석되었다. 또한, 최종 결과물의 순도는 the Korean Standard KS L 1612에 의거해서 분석했다.

• 한국안전학회지
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• 제26권3호
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• pp.15-22
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• 2011

Explosion and fire cause about 30 reported industrial major accidents a year by ignition source which discharge of electrostatic generated to flammable gas, vapor, dust and mixtures. It brings economically and humanly very large loss that accident was caused by fire and explosion from electrostatic discharge. Thus, it is very important that electrostatic discharge energy is to be control below not to be igniting flammable mixtures. There are two kinds of analysis model for electrostatic discharge, human body model and machine model. Human body model is available the parameter of human's electrical equivalent that capacitance is 100 pF, resistance is $1.5k{\Omega}$. To simulate and visualize the electrostatic discharge from human body need a very expensive and high voltage simulator. In this paper, we measured the value of capacitance and resistance concerned with test materials and sizing of specimen and the value of charged voltage concerned with test specimen and distance to develop an electrostatic charge/discharge simulating tool for teaching with which concerned industrial employee and students. The result of experiments, we conformed that the minimum ignition energy of methane-oxygen mixtures meets well the equation $W=1/2CV^2$, and found out that the insulating material and sizing of equivalent value having human body mode are the poly ethylene of 200 mm and 300 mm of diameter. Developed electrostatic charge/discharge simulating tool has many merits; simple mechanism, low cost, no need of electric power and so on.

• 한국정보통신학회논문지
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• 제6권5호
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• pp.703-717
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• 2002

본 논문은 가변형 공유 버퍼 ATM 스위치의 구조 및 VLSI 구현에 관한 연구이다. 본 논문에서 설계한 단일 칩 공유 버퍼 ATM 스위치는 4ns접근속도의 가변형 파이프라인 방식 공유 버퍼를 내장하고 기존의 공유 버퍼 ATM 스위치들이 가지는 메모리 사이클 시간 제한을 해결한다. 내장 버퍼의 가변성을 이용하여 유연한 스위칭 성능을 지원하고 버퍼 메모리 제어와 주소 큐 제어의 독립성을 이용하여 포트 사이즈의 가변성을 제공한다. 제안된 ATM 스위치는 스위치 사이즈와 버퍼 사이즈의 가변성을 이용하여 복잡한 회로의 재설계 없이 용량 및 성능을 재구성할 수 있다. 0.6um CMOS 기술의 설계된 칩은 동작 주파수 800MHz, 640Mbps/port, 4 ${\times}$ 4 Switch Size를 지원한다.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.3653-3659
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• 2015

방향족 열방성 액정 고분자와 에틸렌-아크릴 산 공중합체 및 그 금속염 고분자간의 반응 상용화에 관하여 연구하였다. 블렌드는 배치 믹서에서 제조하였으며 액정 고분자의 에스터 그룹과 이오노머의 아크릴산 사이에 발생하는 acidolysis 반응으로 형성되는 그라프트 공중합체의 발생 유무를 평가하였다. 반응의 정도는 배치 믹서에서 시간에 따른 토크의 증가와 열분석 및 형태학 상 구조를 통해 평가하였다. poly(ethylene-co-acrylic acid) (EAA) 이오노머의 Na 염이 반응을 증진시키는데 특히 효과적임을 알 수 있었다. 반응의 진행 정도는 금속염의 종류 뿐 아니라 이오노머의 조성과 반응 시간에 따라 변하였다. 액정 고분자와 Na로 중화된 이오노머 간의 반응으로 생성된 그라프트 공중합체는 액정 고분자와 EAA 이오노머 블렌드의 반응상용화제로 효과가 높음을 미세 구조 분석을 통하여 알 수 있었다.

• Advances in nano research
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• 제4권1호
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• pp.15-29
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• 2016

A low cost environmentally benign surface coating binder is highly desirable in the field of material science. In this report, castor oil based hyperbranched polyester/bitumen modified fly ash nanocomposites were fabricated to achieve the desired performance. The hyperbranched polyester resin was synthesized by a three-step one pot condensation reaction using monoglyceride of castor oil based carboxyl terminated pre-polymer and 2,2-bis (hydroxymethyl) propionic acid. Also, the bulk fly ash of paper industry waste was converted to hydrophilic nano fly ash by ultrasonication followed by transforming it to an organonano fly ash by the modification with bitumen. The synthesized polyester resin and its nanocomposites were characterized by different analytical and spectroscopic tools. The nanocomposite obtained in presence of 20 wt% styrene (with respect to polyester) was found to be more homogeneous and stable compared to nanocomposite without styrene. The performance in terms of tensile strength, impact resistance, scratch hardness, chemical resistance and thermal stability was found to be improved significantly after formation of nanocomposite compared to the pristine system after curing with bisphenol-A based epoxy and poly(amido amine). The overall results of transmission electron microscopic (TEM) analysis and performance showed good exfoliation of the nano fly ash in the polyester matrix. Thus the studied nanocomposites would open up a new avenue on development of low cost high performing surface coating materials.

• International Journal of Air-Conditioning and Refrigeration
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• 제15권2호
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• pp.78-83
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• 2007

An experimental study has been carried out to analyze the thermal stability and to estimate the lifetime of refrigerating lubricants. PAG and POE oil are considered as test oils in this study. The viscosity of PAG and POE oil was measured by the vibration type viscometer while temperature is varied periodically in the range of $0^{\circ}C{\sim}100^{\circ}C$. In order to estimate lifetime of PAG and POE oil with temperature, the viscosity was measured while the test temperature of oils was maintained continuously at $180,\;200\;and\;220^{\circ}C$. The lifetime of oils is estimated as the decrease in viscosity change by 15%. The results indicate that the reduction rates of viscosity of PAG and POE oil are less than 5% after 510 temperature variation cycles. However, when the oils are kept at high temperature, it is found that the lifetimes of PAG oil is seen to be 244, 177 and 89 hours at the test temperature of $180,\;200\;and\;220^{\circ}C$, respectively, where as the lifetimes of POE oil are estimated to be 1,744, 1,007 and 334 hours at the temperature of $180,\;200\;and\;220^{\circ}C$, respectively. Thus, the lifetime of POE oil is found to be much longer than that of PAG oil. The lifetime correlations of PAG and POE oil are also obtained by Arrhenius's equation method in this paper.