• 전기전자학회논문지
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• 제25권4호
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• pp.735-740
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• 2021

본 논문에서는 기존의 LTDDSCR의 구조를 개선하여 기생 NPN BJT의 낮은 전류이득으로 높은 홀딩전압을 갖는 새로운 ESD 보호 소자를 제안한다. 제안된 보호 소자는 Synopsys사의 TCAD simulation을 이용하여 HBM simulation으로 전기적 특성을 분석하였고 current flow와 impact ionization 및 recombination Simulation으로 추가된 BJT가 동작하는 것을 확인하였다. 또한, 설계변수 D1, D2로 홀딩전압 특성을 최적화하였다. Simulation 수행결과, 새로운 ESD 보호 소자는 기존의 LTDDSCR과 비교하여 높은 홀딩전압을 갖는 것이 검증되었고 대칭적인 양방향 특성을 갖는 것이 확인되었다. 따라서 제안된 ESD 보호 소자는 IC에 적용될시 높은 면적 효율성을 가지며 IC의 신뢰성을 향상시킬 것으로 기대된다.

• Bulletin of the Korean Chemical Society
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• 제13권5호
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• pp.482-486
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• 1992

Ion-molecule reactions of acetylene and mixed acetylene-ammonia cluster ions are studied using an electron impact time-of-flight mass spectrometer. The present results clearly demonstrate that $(C_2H_2)_n^+$ cluster ion distribution represents a distinct magic number of n=3. The mass spectroscopic evidence for the enhanced structural stabilities of $[C_6H_4{\cdot}(NH_3)_m]^+$ (m=0-8) ions is also found along with the detection of mixed cluster $[(C_2H_2)_n{\cdot}(NH_3)_m]^+$ ions, which gives insight into the feasible structure of solvated ions. This is rationalized on the basis of the structural stability for acetylene clusters and the dissociation dynamics of the complex ion under the presence of solvent molecules.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.470-473
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• 2000

지난 10여 년 동안 MOSFET는 전력감소, 도핑농도 증가, 캐리어 속도 증가를 위해서 많은 변화를 가져왔다. 이러한 변화를 받아들이기 위해서, 채널의 길이와 공급되어지는 전압이 감소해야만했으며, 그것으로 인해 소자가 더욱 작아지게 되었다. 그러므로 본 논문은 이러한 변화를 위해 채널의 길이와 전압에 의한 MOSFET 구조에서의 변화를 관찰하고, 드레인과 게이트 사이에서의 임팩트 이온화의 변화를 관찰하였다. 본 논문은 세 가지의 모델 즉, conventional MOSFET와 LDD(lightly doped drain) MOSFET, EPI MOSFET을 제시하였다. 게이트 길이는 0.15um, 0.075um을 사용하였고, 스케일링계수는 λ = 2를 사용하였다 스케일링방법은 Constant-Voltage 스케일링으로 하였고, TCAD를 사용하여, 스케일링에 의한 MOSFET의 특성과 임팩트 이온화, 전계를 비교 분석하였으며, 최적의 채널과 도필 농도에 대하여 분석하였다.

• 전기학회논문지
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• 제61권7호
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• pp.1001-1006
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• 2012

This paper presents a carbon nanotube (CNT) triode-structure field emitter as an ion source in a micro time-of-flight mass spectrometer(TOF-MS). In the ion source by field emission, the electrons emitted from cathodes under an electric field accelerated to the anode and ionize gas molecules by impact before arriving the anode. The generated positive ions are to be accelerated to the ion collector. Whereas most of ions are drawn to the cathodes in diode field emitters, a grid in the triode field emitter prevents the ions from being drawn to the cathodes. The triode field emitter is fabricated by micromachining. The cathode is composed of six CNT cylinders. The total size of the fabricated device is $8.0{\times}7.3{\times}1.9mm^3$. The anode and the grid current of the fabricated CNT field emitter were measured for various anode and grid voltages. When the anode and the grid voltages are 1000 V and 990 V, respectively, the emission current passing through the ionization region is 8.6 ${\mu}A$, which is a sufficient emission current for ionization and mass spectrometry.

• 분석과학
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• 제17권4호
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• pp.322-336
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• 2004

항암치료제인 tamoxifen을 복용한 후 체내에서 분비되는 tamoxifen과 그 대사체를 trifluoroacetic anhydride (TFAA), pentafluoropropionic anhydride (PFPA), 및 heptafluorobutyric anhydride (HFBA) 유도체화 시약으로 이들이 함유하고 있는 히드록시기를 아실화반응시킴으로써 기체크로마토그래피와 질량분석기로 분석 가능하게 하고, 검출한계 등을 개선한 새로운 방법에 대해 연구하였다. 한편 질량 분석기로 검출하기 위한 이온화 방법의 하나인 전자 충격 이온화법과 화학 이온화법을 비교하여 보다 개선된 분석법을 연구하고, 이 방법을 실제 인체 뇨시료에 적용한 tamoxifen 대사체 검출을 위한 최적 조건을 연구하였다. Acylation 방법에 있어서의 최적 반응조건은 반응 온도 $50^{\circ}C$와 반응 시간 30 min 이었으며, 뇨시료에 있어서 tamoxifen 대사체 추출에 대한 최적 pH는 7.0, 추출 용매는 디에틸에테르가 적절함을 알 수 있었다. TFAA, PFPA, HFBA로 유도체 시킨 후 CI법과 EI법을 비교 분석한 결과, NCI법에서는 주로 $[M-HF]^-$ 또는 $[M-2HF]^-$이온이 주요 이온으로 나타났으며 NCI에서 감도가 뛰어난 할로겐원소가 함유된 유도체 시약을 사용하였기 때문에 생체시료 내에 미량 존재하는 약물을 보다 용이하게 검출 및 확인 할 수 있었다. 한편 GC/MS로 tamoxifen대사체를 분석한 결과 tamoxifen이 간에서 대사 될 때 주 대사체로 알려져 있는 4-hydroxytamoxifen은 검출 되지 않았고 hydroxymethoxytamoxifen이 주 대사체로 검출되었다. Acylation 유도체화 과정을 거친 hydroxymethoxytamoxifen은 NCI에서의 토막 이온을 조사한 결과 아미노 그룹의 ${\beta}$-cleavage가 일어난 m/z 491이온, acylation 유도체 한 분자가 쪼개진 m/z 344이온이 비교적 높게 검출되었다.

• Journal of Power Electronics
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• 제12권1호
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• pp.19-23
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• 2012

This paper presents a practical methodology for realistic simulation on reverse characteristics of Wide Bandgap (WBG) SiC and GaN p-n junctions. The adjustment on certain physic-based model parameters, such as the trap density and photo-generation for SiC junction, and impact ionization coefficients and critical field for GaN junction are described. The adjusted parameters were used in Synopsys Medici simulation to obtain a realistic p-n junction avalanche breakdown voltage. The simulation results were verified through benchmarking against independent data reported by others.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2003년도 International Meeting of the Microbiological Society of Korea
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• pp.77-79
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• 2003

Current therapeutic strategies far anthrax have had no significant impact on anthrax mortality over the last several decades. This study used a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) discovery platform to generate protein expression profiles in search of overexpressed proteins in murine macrophage cells (RAW264.7) which infected with Bacillus anthracis spores as potentially novel molecular targets. Two differentially expressed proteins were identified in infected murine macrophage cells as Syndapin and CDC46, respectively. Syndapins are potential links between the cortical actin cytoskeleton and endocytosis. Other two proteins were identified from murine macrophage cells infected with avirulent spores as ITBG-2 (CD18) and HSPA5, respectively. These data demonstrate the feasibility of using a MALDI-TOF platform to generate protein expression profiles and identify potential molecular targets for anthrax therapeutics.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.17-20
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• 2002

This study has been investigated that traps generated inside of the oxide and at the oxide interfaces by the stress bias voltage. The traps are charged near the cathode with negative charge and charged near the anode with positive charge. The charge state of the traps can easily be changed by application of low voltages after the stress high voltage. These trap generation involve either electron impact ionization processes or high field generation processes. It determined to the relative traps locations inside the oxides ranges from 113.4A to 814A with capacitor areas of 10$^{-3}$ $\textrm{cm}^2$ The oxide charge state of traps generated by the stress high voltage contain either a positive or negative charge.

• 천문학회지
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• 제29권spc1호
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• pp.295-298
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• 1996

Non-LTE calculations, with the non-thermal ionization effects included, indicated that for electron bombardment, the H$\alpha$ line is widely broadened and shows a strong central reversal. Significant enhancements at the line wings of Ly$\alpha$ and Ly$\beta$ are also predicted at the beginning of the impulsive phase of flares. For the proton bombardment, no strong broadening and no large central reversal are expected. However, due to proton-hydrogen charge exchange, the enhancements at the red wings of Ly$\alpha$ and Ly$\beta$ lines at the early impulsive phase of flares are significant. Our results show that the electron beam can also in some cases generate visible and UV continuum emission in white-light flares. However, at the onset phase, a negative flare may appear within several seconds, due to the increase of the H- opacity. Another spectroscopic signature of energetic particles, i.e. the impact polarization of atomic lines, is also mentioned.

• 전자공학회논문지A
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• 제32A권4호
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• pp.47-56
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• 1995

In this paper the model of the MQE-IMD-based neural trigger circuit is improved, where MQW-IMD is a new semiconductor device proposed and experimentally demonstrated by the author for the hardware implementation of the neural networks. The electron energy of AlXGa1-XAsbarrier is calculated by Ensemble Monte Carlo simulation according to the variation of Al mole fraction x and the applied electric field, whtich had been roughly estimated in the previous paper because of the difficulty to get the data. And in the consideration of the tunneling of the confined electrons within the quantum well the accuracy of the impact ionization rate is enhaned. Finally, the dependance of the frequency of pulse-train on the number of quantum wells can be calculated by modelling the effect of the distance of the induced positive charge from the cathode on the electric field at the cathode.