• 대한전자공학회논문지
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• 제25권7호
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• pp.780-790
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• 1988

We have studied the hot-carrier-induced degradation caused by the high channel electric field due to the decrease of the gate length of MOSFET used in VLSI. Under DC stress, the condition in which maximum substrate current occures gave the worst degradation. Under AC dynamic stress, other conditions, the pulse shape and the falling rate, gave enormous effects on the degradation phenomena, especially at 77K. Threshold voltage, transconductance, channel conductance and gate current were measured and compared under various stress conditions. The threshold voltage was almost completely recovered by hot-injection stress as a reverse-stress. But, the transconductance was rapidly degraded under hot-hole injection and recovered by sequential hot-electron stress. The Si-SiO2 interface state density was analyzed by a charge pumping technique and the charge pumping current showed the same trend as the threshold voltage shift in degradation process.

• 한국통신학회논문지
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• 제22권1호
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• pp.81-88
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• 1997

Wavelength tunable, narrowbandwidth wvelength filters in compound semiconductor have been modeled, fabricated, and characterized. In order to obtain a narrow bandpass characteristics at 1.55.$\mu$m, a highly asymmertrical directional coupler structure composed of a strongly guided ridge waveguide and a weakly guided strip-loaded waveguide was used. The optimized filter structure modeling has been obtained by using the spectral index method, effective index method, and the coupled mode theory. Operation at a center wavelength a 1.537.mu.m with a bandwidth of 1.8nm and transfer efficiency of 50-70% is experimentally achieved. For the purpose of center wavelength tuning, the carrier injection in p-n diode structure has been theoretically investigated. It has been found that the tuning range of nanometer can be easily obtained by moderate amount carrier injection. We also found that the bandwidth becomes broad as the center wavelength tuning increases.

• Applied Science and Convergence Technology
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• 제23권3호
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• pp.139-144
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• 2014

GaN deposition equipment and processes for the fabrication of white LEDs (Light Emitting Diode) using MOCVD (Metal Organic Chemical Vapor Deposition) were numerically modeled to analyze the effects of a reactive gas introduction strategy. The source gases, TMGa and $NH_3$, were injected from a shower head at the top of the chamber; the carrier gases, $H_2$ or $N_2$, were introduced using two types of injection structures: vertical and horizontal. Wafers sat on the holder at a radial distance between 100 mm and 150 mm. The non-uniformity of the deposition rates for vertical and horizontal injection were 4.3% and 3.1%, respectively. In the case of using $H_2$ as a carrier gas instead of $N_2$, the uniform deposition zone was increased by 20%.

• 한국전기전자재료학회논문지
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• 제13권2호
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• pp.120-124
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• 2000

In this paper, the effects of trap distribution on switching characteristis of a lateral insulated gate bipolar transistor (LIGBT) are investigated. The simulations are performed in order to to analyze the effect of the positon, width and concentration of trap distribution model with a reduced minority carrier lifetime using 2D device simulator MEDICI. The turn off time for the proposed LIGBT model A with the trap injection is 0.8$mutextrm{s}$. These results indicate the improvement of about 2 times compared with the conventional LIGBT. It is shown that the trap distribution model is very effective to reduce the turn-off time with a little increasing of on-state voltage drop.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.357-361
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• 2016

Si와 InAs 두 가지 채널 물질을 가지고 3가지 수송 방향 <100>, <110>, <111>으로 변화시키며 각각의 Nanowire nMOSFETs을 가지고 ballistic quantum transport simulation을 진행하였다. 각각의 경우에 대해 E-k curve를 구한 다음에 band curvature로 캐리어의 유효질량을 계산하고, 이를 통해 MOSFET의 전류 세기를 결정짓는 DOS와 carrier injection velocity를 구하여 어떤 경우에 가장 높은 ON-current를 흐르게 하는지 확인해 보았다. 하지만 예상과 달리 나노와이어의 직경이 1.4nm으로 매우 작기 때문에 valley-splitting이 일어나 Si<110>의 경우에 가장 작은 캐리어 유효 질량을 갖고 있는 사실을 확인할 수 있었다. 결론적으로 Si<100>의 경우에 trade-off 관계에 있는 DOS와 carrier injection velocity가 6가지 경우 중 최적의 조합을 가짐으로써 가장 높은 ON-current를 흐르게 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권9호
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• pp.4502-4517
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• 2019

Tone Injection (TI) scheme significantly reduces the peak-to-average power ratio (PAPR) of Multicarrier Modulation (MCM). However, the computational complexity of the TI scheme rises exponentially with the extra freedom constellation number. Therefore, a novel immune evolutionary mechanism-based TI scheme is proposed in this paper to reduce the computational complexity. By restraining undesirable degeneracy during the processing, this IEM scheme can dramatically increase the population fitness. Monte Carlo results show that proposed IEM-based TI scheme can achieve a significant PAPR and BER improvement with a low complexity.

• 한국해양공학회지
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• 제32권5호
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• pp.372-379
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• 2018

High-pressure gas injection engines (HPGI) took center stage in LNG carrier propulsion systems after their advent. The HPGI engine system can be easily modified to include a re-liquefaction system by adding several devices, which can significantly increase the economic feasibility of the total system. This paper suggests the optimal operating conditions and capacity for a re-liquefaction system for an LNG carrier, which can minimize increases in the total annualized cost. The installation of a re-liquefaction system can save 0.23 million USD per year when the cost of LNG is 5 USD/Mscf. A sensitivity analysis with different LNG costs showed that the re-liquefaction system is profitable when the LNG cost is higher than 3.5 USD/Mscf.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.266-269
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• 1997

Hot carrier effects as a function of bias stress time and bias stress conditions were syste-matica1ly investigated in p-channel po1y-Si TFT's fabricated on the quartz substrate. The device degradation was observed for the negative bias stress. After positive bias stressing, Improvement of electrical characteristic except for subthreshold slope was observed. It was found that these results were related to the hot carrier injection into the gate oxide and interface states at the poly-Si/SiO$_2$interface rather than defects states generation under bias stress.

• 대한조선학회논문집
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• 제58권3호
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• pp.144-157
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• 2021

Brake Horse Power (BHP) reduction ratios by air injection to the underside of the hull surface in an actual ship are predicted using an unstructured finite-volume CFD solver and compared with the sea trial results. In addition, air lubrication system installed on the existing vessel is investigated to find a good solution for additional drag reduction. As a results, it is found that the thickness of the air layer should be minimized within a stable range while securing the area covered by the air layer as much as possible. Furthermore, the amount of frictional drag reduced by air injection is found to be independent of surface roughness and still effective on rough surface. Based on the results of this study, it is expected that systematic and reliable air lubrication system can be designed and evaluated using the proposed method.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2005년도 동계 학술대회 논문집
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• pp.387-391
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• 2005