• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.148-148
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• 1999

• Journal of Korean Neurosurgical Society
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• 제63권6호
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• pp.730-737
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• 2020

Objective : Spinal degeneration is a progressive disease, worsening over time. Lumbar degenerative disease (LDD) is a major spinal disease in elderly patients. Surgical treatment is considered for medically intractable patients with LDD and reoperation after primary surgery is not uncommon. The surgical outcome is occasionally unpredictable because of comorbidities. In the present study, the relationship between comorbidities and the incidence of reoperation for LDD over time was determined. Methods : The claims data of the health insurance national database were used to identify a cohort of patients who underwent spinal surgery for LDD in 2009. The patients were followed up until 2016. Medical comorbidity was assessed according to the Charlson comorbidity index (CCI). Cox proportional hazard regression modeling was used to identify significant differences in sex, surgery, age, causative disease, and comorbidity. Results : The study cohort included 78241 patients; 10328 patients (13.2%) underwent reoperation during the observation period. The reoperation rate was statistically higher (p<0.01) in males, patients 55-74 years and 65-74 years of age, and patients with decompression or discectomy. Significant association was found between increasing reoperation rate and CCI score (p<0.01). Based on multivariate analysis of comorbidities, the significantly higher reoperation rates were observed in patients with peripheral vascular disease, pulmonary lung disease, peptic ulcer, diabetes, and diabetes complications (p<0.01). Conclusion : The study results indicate the reoperation rate for LDD is associated with patient comorbidities. The comorbidities identified in this study could be helpful in future LDD studies.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.311-316
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• 2001

소자의 고집적을 위한 특성분석 기술은 빠른 변화를 보이고 있다. 이에 따라 고집적 소자의 특성을 시뮬레이션을 통하여 이해하고 이에 맞게 제작하는 기술을 매우 중요한 과제 중의 하나가 되었다. 소자가 마이크론급에서 나노급 이하로 작아지면서 그에 맞는 소자개발을 위해 여러 가지 구조가 제시되고 있는데 본 논문에서는 TCAD를 이용하여 여러 가지 구조 중에서 고농도로 도핑된 ground plane 위에 적층하여 만든 EFI MOSFET와 LDD구조의 단점을 개선한 newEPI MOSFET에 대해 조사하였다. 이 구조의 특성과 임팩트이온화와 전계 그리고 I-V 특성 곡선을 저 농도로 도핑된 드레인(LDD) MOSFET와 비교 분석하였다. 또한 TCAD의 유용성을 조사하여 시뮬레이터로서 적합함과 나노구조 소자에서의 스켈링이론의 적합함을 보았다.

• Journal of Semiconductor Engineering
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• 제3권2호
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• pp.161-167
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• 2022

Electrical characteristics of LDMOS power device with LDD(Lightly Doped Drain) structure is studied with variation of the region of channel and LDD. The channel in LDMOSFET encloses a junction-type source and is believed to be an important parameter for determining the circuit operation of CMOS inverter. Two-dimensional TCAD MEDICI simulation is used to study hot-carrier effect, on-resistance Ron, breakdown voltage, and transient switching characteristic. The voltage-transfer characteristics and on-off switching properties are studied as a function of the channel length and doping levels. The digital logic levels of the output and input voltages are analyzed from the transfer curves and circuit operation. Study indicates that drain current significantly depends on the channel length rather than the LDD region, while the switching transient time is almost independent of the channel length. The high and low logic levels of the input voltage showed a strong dependency on the channel length, while the lateral substrate resistance from a latch-up path in the CMOS inverter was comparable to that of a typical CMOS inverter with a guard ring.

• Journal of Periodontal and Implant Science
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• 제27권4호
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• pp.701-722
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• 1997

It was reported that low dose doxycycline(LDD) regimen could inhibit pathologically elevated collagenase activity in the gingival crevicular fluid of petients with adult periodontitis without producing typical antibiotic side effects. The purpose of this study was to evaluate the effects of LDD regimen(20mg) administered during non-surgical therapy on clinical index and gingival crevicular fluid enzyme activity in diabetics who are at high risk for periodontal disease. Forty-nine subjects having at least two sites with probing pocket depths greater than 4mm were selected. In this double-blind, placebo-controlled study, the patients were administered 20 mg doxycycline capsule or placebo capsule b.i.d. for 2 weeks. Clinical parameters of dental plaque, gingival inflammation, probing pocket depth and probing attachment level were assessed at week 0, 2, 4, and 8. Gingival crevicular fluid samples were collected at the same time to evaluate the activities of collagenase and elastase. Clinical parameters and elastase activity were significantly reduced in all groups compared to the baseline value after treatment. Significantly greater reduction in pocket depth and gain in attachment level was shown in the LDD-administered group compared to placebo group in both adult periodontitis and diabetic patients. Total collagenase activity was also reduced significantly in all groups after treatment, but the greater reduction was seen in the LDD-administered diabetics group compared to relevant placebo group(at 4, 8week). Significantly greater reduction in active collagenase activity was also seen in the LDD-administered group compared to placebo group in diabetic patients(at 2, 4, 8week). These results indicated that use of low dose doxycycline could be aueseful adjunct to instrumentation therapy in the management of diabetic patient with periodontitis as well as adult periodontitis patient.

• 전기전자학회논문지
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• 제21권1호
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• pp.96-99
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• 2017

본 연구에서는 금속-산화막-반도체 전계효과 트랜지스터의 불순물 분포변동 효과에 미치는 halo 및 LDD 이온주입 공정의 영향을 3차원 소자 시뮬레이션을 통하여 확인하였다. 정확한 시뮬레이션 계산을 위해 kinetic monte carlo 모델을 적용하여 불순물 입자와 결함 낱낱의 거동을 계산하는 원자단위 시뮬레이션을 수행하였다. 문턱전압 및 on-current의 산포를 통해 확인한 결과 halo 이온주입 공정이 LDD 이온주입 공정보다 문턱전압 산포의 경우 약 6.45배 그리고 on-current 산포의 경우 2.46배 더 큰 영향을 미치는 특성을 확인하였다. 그리고 문턱전압과 on-current 산포를 히스토그램으로 나타내어 그 산포를 정규분포로 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.641-644
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• 2008

Traditional LTPS TFT needs additional LDD process to decrease leakage current. However the fabrication process is no suitable for PI substrate. Additional laser multi-irradiation will damage the poly-Si to cause the TFT electrical degrade. Therefore we propose the simplified process to activate the $N^+$ and $N^-$ at the same time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.875-878
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• 1999

In this paper, we measured and simulated the transconductance change of submicron LDD NMOSFETs due to back bias under various channel length, temperature and substrate doping conditions. As back bias is increased, the mobility will decrease and g$_{m}$ decreases according to a conventional model. But as the channel length is reduced, this phenomenon is inverted and g$_{m}$ increases in the submicron region. This can be explained by analyzing the electron quasi Fermi potential in the channel. And the empirical formulae which show the g$_{m}$ change were induced. These will be helpful to enhance the efficiency and precision of IC design.esign.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.918-921
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• 1999

The breakdown voltage in fully depleted SOI N-MOSFET’s have been studied over a wide range of film thicknesses, channel doping, and channel lengths. An asynmmetric Source/Drain SOI technology is proposed, which having the advantages of Normal LDD SOI(Silicon-On-Insulator) for breakdown voltage and gives a high drivability of LDD SOI without sacrificings hot carrier immunity The two-dimensional simulations have been used to investigate the breakdown behavior in these device. It is found that the breakdown voltage(BVds) is almost same with high current drivability as that in Normal LDD SOI device structure.

• 한국전기전자재료학회논문지
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• 제11권8호
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• pp.587-595
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• 1998

Transient thermal analysis simulations are carried out using a modeling program to understand the human body model HBM ESD. The devices were simulated a one-dimensional device subjected to ESD stress by solving Poison's equation, the continuity equation, and heat flow equation. A ramp rise with peak ESD voltage during rise time is applied to the device under test and then discharged exponentially through the device. LDD and NMOS structures were studied to evaluate ESD performance, snap back voltages, device heating. Junction heating results in the necessity for increased electron concentration in the space charge region to carry the current by the ESD HBM circuit. The doping profile adihacent to junction determines the amount of charge density and magnitude of the electric field, potential drop, and device heating. Shallow slopes of LDD tend to collect the negative charge and higher potential drops and device heating.