• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.368-373
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• 1998

As device dimensions approach submicrometer size in ULSI, the demand for interlayer dielectric materials with very low dielectric constant is increased to solve problems of RC delay caused by increase in parasitic resistance and capacitance in multilevel interconnectins. Fluorinated amorphous carbon in one of the promising materials in ULSI for the interlayer dielectric films with low dielectric constant. However, poor thermal stability and adhesion with Si substrates have inhibited its use. Recently, amorphous hydrogenated carbon (a-C:H) film as a buffer layer between the Si substrate and a-C:F has been introduced because it improves the adhesion with Si substrate. In this study, therfore, a-C:F/a-C:H films were deposited on p-type Si(100) by ECRCVD from $C_2F_6, CH_4$and $H_2$gas source and investigated the effect of forward power and composition on the thickness, chemical bonding state, dielectric constant, surface morphology and roughness of a-C:F films as an interlayer dielectric for ULSI. SEM, FT-IR, XPS, C-V meter and AFM were used for determination of each properties. The dielectric constant in the a-C:F/a-C:H films were found to decrease with increasing fluorine content. However, the dielectric constant increased after furnace annealing in $N_2$atomosphere at $400^{\circ}C$ for 1hour due to decreasing of flurorine content. However, the dielectric constant increased after furnace annealing in $N_2$atmosphere at $400^{\circ}C$ for 1hour due to decreasing of fluorine concentration.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.111-120
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• 2006

In this paper, a node architecture of WDM metro network for connecting broadband access networks to converge wire/wireless networks. In consideration of the proposed node architecture and network requirements we proposed and evaluated medium access control protocols. We review WDM related technologies of sub-carrier multiplexing and optical components in order to resolve the bottleneck between optical backbone networks md access networks, and a access node architecture sharing common wavelength is introduced. Source-stripping (SS) MAC protocol Is evaluated under the proposed functional node architecture. DS+IS (Destination-Stripping and Source-Stripping) and DS+IS (Destination-Stripping and Intermediate-Stripping) MAC protocols are described to increase the slot-reuse factor which is low on SS MAC protocol. The key function of new MAC protocols regards the optical switch module of proposed node architecture and helps intermediate or source access nodes for dropping slots to destinations of different wavelength group. Thus, slot-reuse factor increases as the MAC protocols reduce the unnecessary ring-rotation of transferred slots. We use a numerical analysis to expect bandwidth efficiency and maximum throughput by slot-reuse factor Throughput network simulation, the verification of throughput, queuing delay, and transmission fairness are compared among MAC protocols.

• The KIPS Transactions:PartA
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• v.11A no.2
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• pp.195-202
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• 2004

This paper introduces the design or parallel Pipeline high-speed analog-to-digital converter(ADC) for the high-resolution video applications which require very precise sampling. The overall architecture of the ADC consists of 4-channel parallel time-interleaved 10-bit pipeline ADC structure a]lowing 200MSample/s sampling speed which corresponds to 4-times improvement in sampling speed per channel. Key building blocks are composed of the front-end sample-and-hold amplifier(SHA), the dynamic comparator and the 2-stage full differential operational amplifier. The 1-bit DAC, comparator and gain-2 amplifier are used internally in each stage and they were integrated into single switched capacitor architecture allowing high speed operation as well as low power consumption. In this work, the gain of operational amplifier was enhanced significantly using negative resistance element. In the ADC, a delay line Is designed for each stage using D-flip flops to align the bit signals and minimize the timing error in the conversion. The converter has the power dissipation of 280㎽ at 3.3V power supply. Measured performance includes DNL and INL of +0.7/-0.6LSB, +0.9/-0.3LSB.

• Investigative Magnetic Resonance Imaging
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• v.13 no.1
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• pp.15-21
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• 2009

Purpose : A method to estimate a real k-space trajectory based on a circuit model of the gradient system is proposed for spiral imaging. The estimated k-space trajectory instead of the ideal trajectory is used in the reconstruction to improve the image quality in the spiral imaging. Materials and Methods : Since the gradient system has self resistance, capacitance, and inductance, as well as the mutual inductance between the magnet and the gradient coils, the generated gradient fields have delays and transient responses compared to the input waveform to the gradient system. The real gradient fields and their trajectory in k-space play an important role in the reconstruction. In this paper, the gradient system is modeled with R-L-C circuits, and real gradient fields are estimated from the input to the model. An experimental method to determine the model parameters (R, L, C values) is also suggested from the quality of the reconstructed image. Results : The gradient fields are estimated from the circuit model of the gradient system at 1.5 Tesla MRI system. The spiral trajectory obtained by the integration of the estimated gradient fields is used for the reconstruction. From experiments, the reconstructed images using the estimated trajectory show improved uniformity, reduced overshoots near the edges, and enhanced resolutions compared to those using the ideal trajectory without model. Conclusion : The gradient system was successfully modeled by the R-L-C circuits. Much improved reconstruction was achieved in the spiral imaging using the trajectory estimated by the proposed model.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.106-106
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• 1999

반도체 소자가 소브마이크론 이하로 집적화 되어감에 따라, RC 신호 지연 및 간섭 현상, 전력 소비의 증가 문제가 심각하게 대두되고 있다. 이러한 문제를 개선하기 위해서는, 현재 층간 절연막으로 상용화되어 있는 SiO2 박막을 대체할 저유전율 박막의 개발이 필수적이며, 많은 연구자들이 여러 가지 새로운 유기물질과 무기물질은 제안하고 있다. 반도체 공정상의 적합성을 고려할 때, 이들 여러물질 중에서 알킬기를 함유한 SiO2 박막(이하 'Si-O-C-H 박막'으로 표기)에 많은 관심이 집중되고 있다. Si-O-C-H 박막은 알킬기에 의해 형성된 나노 스케일의 기공에 의해 작은 유전율을 가지게 된다. 따라서, 박막내의 알킬기의 함유량이 많을수록 보다 작은 유전율을 얻을 수 있다. 그러나 과다한 알킬기의 함유는 Si-O-C-H 박막의 열적 특성을 열화시키는 부정적인 효과도 있다. 본 연구에서는 bis-trimethylsilylmethane(BTMSM, H9C3-Si-CH2-Si-C3H9) precursor를 이용하여 Si-O-C-H 박막을 증착하였다. BTMSM precursor의 중요한 특징중 하나는, 두 실리콘 원자 사이에 Si-CH2 결합이 존재한다는 사실이다. Si-CH2 결합은 양쪽의 Si에 의해 강하게 결합되어 있어서, BTMSM precursor를 사용하여 Si-O-C-H 박막은 유전상수도 작을 뿐 아니라, 열적으로도 안정된 특성이 얻어질 것으로 기대된다. Si-O-C-H 박막의 열적 안정성을 평가하기 위하여, 고온 열처리 전후의 FT-IR 스펙트럼 분석과 C-V(capacitance-voltage) 측정에 의한 유전상수 변화를 살펴보았다. 또한 증착된 박막의 미세구조 및 step coverage 특성 관찰을 위하여 SEM(scanning electron microscopy) 및 TEM(transmission electron micfroscopy) 분석을 하였다. 변화하였으며 이는 포토루미네슨스의 변화의 원인으로 판단된다. 연구하였다. CeO2 와 Si 사이의 계면을 TEM 측정에 의해 분석하였고, Ce와 O의 화학적 조성비를 RBS에 의해 측정하였다. Si(100) 기판위에 증착된 CeO2 는 $600^{\circ}C$ 낮은 증착률에서 seed layer를 하지 않은 조건에서 CeO2 (200) 방향으로 우선 성장하였으며, Si(111) 기판 위의 CeO2 박막은 40$0^{\circ}C$ 높은 증착률에서 seed layer를 2분이상 한 조건에서 CeO2 (111) 방향으로 우선 성장하였다. TEM 분석에서 CeO2 와 Si 기판사이에서 계면에서 얇은 SiO2층이 형성되었으며, TED 분석은 Si(100) 과 Si(111) 위에 증착한 CeO2 박막이 각각 우선 방향성을 가진 다결정임을 보여주었다. C-V 곡선에서 나타난 Hysteresis는 CeO2 박막과 Si 사이의 결함때문이라고 사료된다.phology 관찰결과 Ge 함량이 높은 박막의 입계가 다결정 Si의 입계에 비해 훨씬 큰 것으로 나타났으며 근 값도 증가하는 것으로 나타났다. 포유동물 세포에 유전자 발현벡터로써 사용할 수 있음으로 post-genomics시대에 다양한 종류의 단백질 기능연구에 맡은 도움이 되리라 기대한다.다양한 기능을 가진 신소재 제조에 있다. 또한 경제적인 측면에서도 고부가 가치의 제품 개발에 따른 새로운 수요 창출과 수익률 향상, 기존의 기능성 안료를 나노(nano)화하여 나노 입자를 제조, 기존의 기능성 안료에 대한 비용 절감 효과등을 유도 할 수 있다. 역시 기술적인 측면에서도 특수소재 개발에 있어 최적의 나노 입자 제어기술 개발 및 나노입자를 기능성 소재로 사용하여 새로운 제품의 제조와 고압 기상 분사기술의 최적화에 의한 기능성 나노 입자 제조 기술을 확립하고 2차 오염 발생원인 유기계 항균제를 무기계 항균제로 대

• Journal of fish pathology
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• v.23 no.3
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• pp.389-398
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• 2010

Effects of various concentration of yuzu Citrus junos Siebold ex Tanaka in the diets on growth, blood chemistry and disease resistance of olive flounder were determined. Fifteen hundred fish averaging 200~270g were fed on moist pellet containing yuzu at the concentrations of 0%(control), 2.5%, 5% and 7.5% for 3 months. After feeding trial, weight gain of fish fed 2.5% and 5.0% yuza diet was higher than those of fish fed 0% and 7.5% yuza diet but not significant(P>0.05). No differences in hematological and physiological indices of olive flounder were found among the experimental diets except for total cholesterol. Serum lysozyme activity was not significantly different among fish fed experimental diets but bactericidal activity of fish fed 7.5% yuza diet was significantly different from those of fish fed 0, 2.5 and 5% Yuza diets. Survival rates of fish fed 2.5% yuza diet at experimental infection with Edwardsiella tarda and Streptococcus sp. were higher than those of the other experimental groups but not significant. In conclusion, Dietary inclusion of 2.5~5% yuzu seems to have positive effects for fish health condition and disease resistance.