• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1827-1829
• /
• 1999

반도체 소자가 고집적화 되고 미세화 될수록 좁은 면적에 여러 기능을 가진 우물을 형성시켜야하나 기존의 우물로는 고온 장시간 열처리로 인하여 측면 확산이 깊게 되고, 불순물 농도 분포는 표면으로부터 농도가 점차 낮아진다. 따라서 기존 우물의 불순물 분포로는 기생 트랜지스터에 의한 렛치-엎과 알파 입자에 의한 SER의 감소를 위하여 필요한 벌크에서의 고농도 분포를 유지하기가 곤란하다. 이러한 문제는 차세대 반도체 개발을 위해서는 반드시 해결해야 할 것이며 이것을 해결할 수 있는 공정으로는 고 에너지 이온 주입과 저온, 단시간 열처리이다. 고 에너지 이온 주입 시의 불순물 분포를 어떻게 제어할 것인가에 대한 것과 여기서 부수적으로 나타나는 격자 손상과 그 회복 및 잔류결함의 성질을 어떻게 알고 이를 게터링 등에 이용할 것이냐에 대한 것이다. 실리콘 기판 내로 가속된 이온은 실리콘 격자와 충돌하면서 많은 1차 결함이 생기고. 이들은 후속 열처리 과정에서 활성화되면서 대부분은 실리콘 격자의 위치에 들어가 활성화되고. 그 나머지는 실리콘내의 격자간 산소, 격자간 실리콘. 격자 빈자리와 상호 작용을 하여 2차 결함을 형성한다. 에피택셜 웨이퍼와 p-type웨이퍼에 비소 이온을 고에너지로 주입후 2단계 열처리에 의한 농도분포변화와 핵생성과 결함성장에 관해 실험하였고, 핵생성온도는 $600^{\circ}C$이하이고, 성장에 필요한 온도는 $700^{\circ}C$이상이다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.6
• /
• pp.1409-1413
• /
• 2013

This paper analyzed the change of subthreshold current for channel doping concentration of double gate(DG) MOSFET. Poisson's equation had been used to analyze the potential distribution in channel, and Gaussian function had been used as carrier distribution. The potential distribution was obtained as the analytical function of channel dimension, using the boundary condition. The subthreshold current had been analyzed for channel doping concentration, and projected range and standard projected deviation of Gaussian function. Since this analytical potential model was verified in the previous papers, we used this model to analyze the subthreshold current. As a result, we know the subthreshold current was influenced on parameters of Gaussian function and channel doping concentration for DGMOSFET.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.58.2-58.2
• /
• 2009

금속 와이어를 전기폭발법에 의해 증기 상태로 만든 후 응축시킬 때 제조되는 금속나노분말의 크기특성을 파악하기 위하여 제조장치에 샘플링 포트를 삽입하여 실시간 입자 측정기(Scanning Mobility Particle Sizer; SMPS) 로 14~615 nm 범위의 크기분포를 측정하였다. SMPS는 입자의 크기에 따라 전기적 이동도가 달라지는 원리를 이용하여 공기 중에 부유된 나노입자의 크기분포를 수 분내에 측정하는 실시간 입자 측정기이다. 금속나노분말 제조장치 내부는 약 0.5 bar 수준으로 불활성가스로 채워져 있어서 대기압보다 높은 고압조건이므로 SMPS 전단에 작은 노즐이 삽입된 pressure reducer를 부착하여 적정한 압력 수준으로 낮춘 후 SMPS로 나노분말의 크기분포를 실시간으로 측정하였다. 제조공정이 진행되면서 전기폭발이 주기적으로 발생하는 동안에 SMPS로 측정한 14~615 nm 범위 입자의 총 수농도는 약 $10^7$ 개/$cm^3$ 수준으로 매우 높았고, 약 100 nm와 200 nm에서 고농도 피크를 나타내는 bimodal 분포를 나타냈다. 반면 전기폭발이 잠시 중단되는 경우 입자의 총 수 농도는 약 $10^4$ 개/$cm^3$ 수준으로 낮아지고, 약 20 nm 이하의 입자가 대부분을 차지하면서 입자의 크기가 커질수록 농도가 낮아지는 형태의 크기분포로 바뀌었다. 본 연구를 통해 얻어진 제조장치 내부의 나노분말 크기분포 자료는 고품질 제품을 생산하기 위해 나노분말의 크기분포를 제어하는 분급장치 개발에 활용될 수 있을 것으로 기대된다.

• Economic and Environmental Geology
• /
• v.57 no.2
• /
• pp.233-241
• /
• 2024

This study was conducted to investigate the geological distribution characteristics of fluorine in rocks, which can be a major resource of forest aggregates in Korea. Samples of forest aggregates were collected from 224 sites in 22 cities and counties for this study. The national background concentration was 344 mg/kg, which was significantly lower than the average fluorine concentration of crustal, which was 625 mg/kg, and slightly higher than the average fluorine concentration of world soil, which was 321 mg/kg. In terms of region and tectonic structure, fluorine concentrations were investigated to be highest in Gyeonggi-do(394 mg/kg) and Gyeonggi massif(396 mg/kg), respectively. The concentration distribution by the origin of the parent rock was in the order of metamorphic rock(362 mg/kg) > sedimentary rock(354 mg/kg) > igneous rock(328 mg/kg), and the concentration distribution by geologic ages was the highest in the Paleozoic at 394 mg/kg. The concentration distribution by rock types was in the order of diorite(515 mg/kg) > gneisses(377 mg/kg) > schists(344 mg/kg) > phyllite(306 mg/kg) > granites(305 mg/kg) > quartz porphyry(298 mg/kg). Consequently, it is speculated that gneisses and schists, Precambrian metamorphic rocks in the Gyeonggi massif that forms the crust of Gyeonggi-do, contain high fluorine concentrations.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.23 no.6
• /
• pp.417-424
• /
• 1990

Effect of physical processes on the surface distributions of chlorophyll-a and nutrients was investigated in the southern sea of Korea during summer season. The northwestern area of Cheju Island had higher concentrations of the chlorophyll-a and nutrients than its southeastern area. A nutrient-rich patch was observed in the western area of Cheju Island and the northern area of $34^{\circ}N$ respectively. It seems that the patch in the western area of Cheju Island is formed by horizontal extension of the low-saline Coastal Water of China Contiental(CWCC), while the patch in the northern area of $34^{\circ}N$ by vertical mixing. Also, the high chlorophyll-a in the vicinity of Cheju Island appears to be ascribed to sufficient supply of nutrient from bottom water by coastal upwelling.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.10
• /
• pp.1053-1060
• /
• 2011

This study is performed to determine the drug concentration profiles of drug-eluting stents (DES) for an ideal circular ring stent and intertwined stent models for various Reynolds numbers (Re = 200, 400, and 800). The Navier.Stokes equations coupled with the advection-diffusion equation are solved numerically in order to determine how the flow patterns and drug deposition are affected in the in-stent and post-stent regions where flow separation and recirculation occur. The presence of DES within the arterial segment affects the local drug distribution in the flow field. As a result, the drug concentration for the intertwined stent is higher over the in-stent region in comparison with the ideal stents. For a given stent geometry, the local drug concentration in the in-stent region decreases with Reynolds number, while for a given Reynolds number, the local drug concentration is relatively insensitive to the stent geometry. The results show that drug concentration along the arterial wall is significantly higher within the in-stent and post-stent regions for the intertwined stent geometry than for the ideal stent geometries.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.1
• /
• pp.149-157
• /
• 2000

This paper presents the first results of dissolved arsenic in the Kangnung Namdae stream. The distribution of As concentrations measured in 28 August (high water flow) and in 21 November 1997 (low water flow) differs from those of other metals measured during the same period; The concentrations of Doam-dam are lower than those of Obong-dam and accumulation in the downstream in the period of low water flow is not pronounced. The As concentration in the downstream under the low water flow is lower than under high water flow, reciprocally to other metals. Freshwater concentrations are comparable with those measured in pristine river and lower than the world average and the diffrence of concentrations measured during two period is minute. Therefore, the As concentrations in the Namdae stream are background level and the source of As contamination does not exist. In the mixing zone between the freshwater and Donghae seawater, As behave conservatively, indicating the absence of any significant removal or mobilization processes. A first estimation of total dissolved As input from Namdae stream to Donghae coastal sea shows 65.12 kg/yr.

• Journal of Wetlands Research
• /
• v.8 no.4
• /
• pp.49-58
• /
• 2006

The extent and degree of contaminated sediments on lake Paldang were analyzed at 40 sites for organic matters, nutrients and heavy metals. COD, T-N and T-P were fairly correlated with the grain size of sediments, and the sites which were most distributed with sand were less contaminated with the sites covered with silt and clay. Phosphorus species were in the range of 7-58 for adsorbed-P, $13{\sim}411{\mu}g/g$ for NAI-P, $52{\sim}482{\mu}g/g$ for Apatite-P and $75{\sim}894{\mu}g/g$ for residual-P, respectively. Although heavy metals of sediments were detected at the range of $0.2-4.2{\mu}g/g$(Cr), $1.6{\sim}20.7{\mu}g/g$(Cu), 1.4~78.0ng/g(Hg), $2.1{\sim}18.9{\mu}g/g$(Pb), $1.8{\sim}99.5{\mu}g/g$(Zn), further survey over the long period were required for more monitoring data. The release rate of nutrients were found no relationship in this study.

• Analytical Science and Technology
• /
• v.21 no.5
• /
• pp.375-382
• /
• 2008

Bisphenol A (BPA) and di-2-ethyhexyl phthalate (DEHP) is the considerably hazardous materials, endocrine disrupting chemicals (EDCs), which is accumulated to the human's fat and tissue. We studied the relationship between the concentrations of BPA and DEHP in the precocious puberty and the normal controls using GC/MSD. BPA concentrations of the precocious puberty are lower than that of normal controls. But DEHP concentrations of the precocious puberty are higher than that of normal controls. From these results, BPA is not related to the precocious puberty. Otherwise, DEHP is somewhat related to the precocious puberty and the concentrations of the precocious puberty are approximately 45% higher than that of normal controls.

• Journal of the KSME
• /
• v.33 no.12
• /
• pp.1043-1051
• /
• 1993

Nd:Yag 레이저의 제2고조파와 광대역 모드 없는 레이저를 광원으로 사용하고 이중회절발분광 기에 설치된 다채널광검출기로 분광된 CARS 스펙트럼을 레이저 펄스마다 측정 할 수 있는 광 대역 CARS 분광기를 제작하였다. CARS 온도측정 불확정도는 300K에서 1300K까지는 1.5% 이내였다. CARS 기술을 이용하여 분젠버너의 화염면에서의 온도 분포를 측정하였으며, 대향류 버너의 화염내부의 온도 분포 및 CO 농도분포를 측정하였다. 이러한 CARS 기술은 정상상태의 연소진단에 응용할 수 있을 뿐만 아니라 레이저 펄스마다 측정되는 온도의 분포함수를 조사하면 앞으로 난류연소의 진단에도 응용이 가능하며, 내연기관 등과 같이 연속폭발연소 상태의 기체의 온도나 농도 측정이 가능하다. 본 연구에서 연구된 CARS 기술의 온도 측정정확도는 약 2% 이 내이고 농도 측정은 측정기체의 농도가 상온에서는 약 0.1% 이상, 1500K 이상의 고온에서는 0.3%이상이면 가능하다.