• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.377-385
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• 2018

For the investigation of dopant profiles in implanted $Si_{1-x}Ge_x$, the implanted B and As profiles are measured using SIMS (secondary ion mass spectrometry). The fundamental ion-solid interactions of implantation in $Si_{1-x}Ge_x$ are discussed and explained using SRIM, UT-marlowe, and T-dyn programs. The annealed simulation profiles are also analyzed and compared with experimental data. In comparison with the SIMS data, the boron simulation results show 8% deviations of $R_p$ and 1.8% deviations of ${\Delta}R_p$ owing to relatively small lattice strain and relaxation on the sample surface. In comparison with the SIMS data, the simulation results show 4.7% deviations of $R_p$ and 8.1% deviations of ${\Delta}R_p$ in the arsenic implanted $Si_{0.2}Ge_{0.8}$ layer and 8.5% deviations of $R_p$ and 38% deviations of ${\Delta}R_p$ in the $Si_{0.5}Ge_{0.5}$ layer. An analytical method for obtaining the dopant profile is proposed and also compared with experimental and simulation data herein. For the high-speed CMOSFET (complementary metal oxide semiconductor field effect transistor) and HBT (heterojunction bipolar transistor), the study of dopant profiles in the $Si_{1-x}Ge_x$ layer becomes more important for accurate device scaling and fabrication technologies.

• 센서학회지
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• 제8권5호
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• pp.400-406
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• 1999

(100), n/$n^+$/n 3층 실리콘 웨이퍼를 이용하여 4가지 형태의 미소 빔 구조를 가지는 압저항형 유체센서를 제작하고, 그 특성을 조사하였다. Boron 확산을 통하여 압저항을 형성하였으며 형성된 압저항의 저항 값은 $1\;k{\Omega}$ 정도였다. 다공질 실리콘 마이크로머시닝을 이용하여 3차원의 실리콘 미소 빔 구조체를 제작하였으며, 실리콘과 금속의 열팽창계수 차이를 이용하여 빔을 위로 휘게 하여 원하는 형상으로 제조하였다. 제조된 센서의 출력 특성은 half-bridge를 구성하여 조사하였다. 같은 유속에서는 빔의 길이에 비례하여 출력 전압이 증가함을 보였고, 반면에 빔의 길이가 짧을수록 측정 가능 구간이 넓게 나타났다. 제조된 센서의 출력전압은 유량의 3.2승에 비례하여 증가하였으며, 이는 유속에 따른 빔이 받는 응력이 비 선형 특성을 나타내기 때문이다.

• 한국표면공학회지
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• 제49권1호
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• pp.54-61
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• 2016

Screen printing of commercially available Ag paste is the most widely used method for the front side metallization of Si solar cells. However, the metallization using Ag paste is expensive and needs high temperature annealing for reliable contact. Among many metallization schemes, Ni/Cu/Sn plating is one of the most promising methods due to low contact resistance and mass production, resulting in high efficiency and low production cost. Ni layer serves as a barrier which would prevent copper atoms from diffusion into the silicon substrate. However, Ni based schemes by electroless deposition usually have low thermal stability, and require high annealing process due to phosphorus content in the Ni based films. These problems can be resolved by adding W element in Ni-based film. In this study, Ni-W-P alloys were formed by electroless plating and properties of it such as sheet resistance, resistivity, specific contact resistivity, crystallinity, and morphology were investigated before and after annealing process by means of transmission line method (TLM), 4-point probe, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM).

• Nuclear Engineering and Technology
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• 제35권4호
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• pp.356-368
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• 2003

Material properties such as coolant specific heat, film heat transfer coefficient, cladding thermal conductivity, surface diffusion coefficient of the multi-bubble are improved in MACSIS-Mod1. The axial power and flux profile module was also incorporated with irradiation history. The performance and feasibility of the updated driver fuel pin have been analyzed for nominal parameters based on the conceptual design for the KALIMER breakeven core by MACSIS-MOD1 code. The fuel slug centerline temperature takes the maximum at 700mm from the bottom of the slug in spite of the nearly symmetric axial power distribution. The cladding mid-wall and coolant temperatures take the maximum at the top of the pin. Temperature of the fuel slug surface over the entire irradiation life is much lower than the fuel-clad eutectic reaction temperature. The fission gas release of the driver fuel pin at the end of life is predicted to be $68.61\%$ and plenum pressure is too low to cause cladding yielding. The probability that the fuel pin would fail is estimated to be much less than that allowed in the design criteria. The maximum radial deformation of the fuel pin is $1.93\%$, satisfying the preliminary design criterion ($3\%$) for fuel pin deformation. Therefore the conceptual design parameters of the driver fuel pin for the KALIMER breakeven core are expected to satisfy the preliminary criteria on temperature, fluence limit, deformation limit etc.

• 대한기계학회논문집
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• 제11권2호
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• pp.253-261
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• 1987

본 논문에서는 이러한 점들을 보완하여 Fig.1에 도시한 Rijke 관에서 나선형 가열기에 의한 음향력의 발생량을 계산하고 기주진동을 일으키는데 필요한 가열량을 계산하고 기주진동을 일으키는데 필요한 가열량을 구하였다. 이론을 뒷받침하기 위 하여 실험을 하고 결과를 비교 검토하였다.

• 한국화재소방학회논문지
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• 제32권3호
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• pp.14-18
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• 2018

건축 재료로 사용되는 목재의 내화성능에 관한 기존 연구들은 목재에 난연 또는 방염 처리하였을 경우 연소특성을 확인하는 것에 집중되어 졌다. 본 논문에서는 화염에 노출된 목재의 열분해와 밀접한 관련이 있는 내부 온도 변화를 확인하기 위하여 건축용 구조재로 널리 사용되는 미송(Douglas-fir)에 방염액 및 방염도료를 처리 후 표준 가열 온도 곡선에 따라 수평가열로에서 가열실험을 실시하였다. 실험결과 방염액을 처리하였을 때 목재내부의 열확산이 현저히 감소하는 것을 확인할 수 있었으며 방염도료를 처리한 시료의 경우 고온에 노출 되었을 때 도막이 박리되어 방염효과를 기대할 수 없었다. 따라서 두꺼운 목재에 방염효과를 높이기 위해서는 목재표면에 도막을 형성시키는 방염도료보다는 목재내부로 침투하는 방염액을 사용하는 것이 방화효과가 클 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.276-279
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• 2004

Plasma enhanced chemical vapor deposition (PECVD) of silicon nitride (SiN) is a proven technique for obtaining layers that meet the needs of surface passivation and anti-reflection coating. In addition, the deposition process appears to provoke bulk passivation as well due to diffusion of atomic hydrogen. This bulk passivation is an important advantage of PECVD deposition when compared to the conventional CVD techniques. A further advantage of PECVD is that the process takes place at a relatively low temperature of 300t, keeping the total thermal budget of the cell processing to a minimum. In this work SiN deposition was performed using a horizontal PECVD reactor system consisting of a long horizontal quartz tube that was radiantly heated. Special and long rectangular graphite plates served as both the electrodes to establish the plasma and holders of the wafers. The electrode configuration was designed to provide a uniform plasma environment for each wafer and to ensure the film uniformity. These horizontally oriented graphite electrodes were stacked parallel to one another, side by side, with alternating plates serving as power and ground electrodes for the RF power supply. The plasma was formed in the space between each pair of plates. Also this paper deals with the fabrication of multicrystalline silicon solar cells with PECVD SiN layers combined with high-throughput screen printing and RTP firing. Using this sequence we were able to obtain solar cells with an efficiency of 14% for polished multi crystalline Si wafers of size 125 m square.

• Advances in environmental research
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• 제5권1호
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• pp.1-18
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• 2016

Magnetic nano-based sorbents have been synthesized for the recovery of two rare earth elements (REE: Nd(III) and Yb(III)). The magnetic nano-based particles are synthesized by a one-pot hydrothermal procedure involving co-precipitation under thermal conditions of Fe(III) and Fe(II) salts in the presence of chitosan. The composite magnetic/chitosan material is crosslinked with epichlorohydrin and modified by grafting alanine and serine amine-acids. These materials are tested for the binding of Nd(III) (light REE) and Yb(III) (heavy REE) through the study of pH effect, sorption isotherms, uptake kinetics, metal desorption and sorbent recycling. Sorption isotherms are well fitted by the Langmuir equation: the maximum sorption capacities range between 9 and 18 mg REE $g^{-1}$ (at pH 5). The sorption mechanism is endothermic (positive value of ${\Delta}H^{\circ}$) and contributes to increase the randomness of the system (positive value of ${\Delta}S^{\circ}$). The fast uptake kinetics can be described by the pseudo-second order rate equation: the equilibrium is reached within 4 hours of contact. The sub-micron size of sorbent particles strongly reduces the contribution of resistance to intraparticle diffusion in the control of uptake kinetics. Metal desorption using acidified thiourea solutions allows maintaining sorption efficiency for at least four successive cycles with limited loss in sorption capacity.

• 설비공학논문집
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• 제16권12호
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• pp.1204-1211
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• 2004

It is difficult to apply a conventional selection guide for diffusers when the diffuser is installed in a perimeter zone, because the air diffusion performance index (ADPI) vs. throw/length (T/L) ratio curve listed in conventional guide does not consider the perimetric heating load through the walls. The objective of this study is to evaluate the effect of the perimetric heating load on the ADPI and propose a selection guide for a proper line diffuser when perimetric heating load exists. The velocity and temperature distributions and the ADPI values are obtained numerically with various heat load ratios and air flow rates. The velocity and temperature distributions and the ADPI values are analyzed by CFD in case of various heat load ratios and air flow rates. Also, ADPI was calculated by those results. The ADPI values by numerical results are compared with an existing experimental data to verify the method for the evaluation of ADPI proposed in a present study. In case of a line diffuser installed at the high side wall, the ADPI decreases according to the increases of the flow rate on every heat load ratio of the present study except 0.75. The ADPI vs. T/L ratio curves have been proposed for the heat load ratios of 0.25, 0.5, 0.75 to guarantee the comport thermal environment when diffusers are installed in perimeter zone.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.185-190
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• 1996

RFSP is a computer program to do fuel management calculations for CANDU reactors. Its main function is to calculate neutron flux and power distributions using two-energy-group, three dimensional neutron diffusion theory. However, up to now the treatment has not been true two-group but actually "one-and-half groups". In other words, the previous (1.5-group) version of RFSP lumps the fast fission term into the thermal fission term. This is based on the POWDERPUFS-V Westcott convention. Also, there is no up-scattering term or bundle power over cell flux (H1 factor) for the fast group. While POWDERPUFS-V provides only 1.5 group properties, true two-group cross sections for the design and analysis of CAUDU reactors can be obtained from WIMS-AECL. To treat the full two-group properties, the previous RFSP version was modified by adding the fast fission, up-scatter terms, and H1 factor. This two-group version of RFSP is a convenient tool to accept lattice properties from any advanced lattice code (e.g. WIMS-AECL DRAGON, HELIOS...) and to apply to advanced fuel cycles. In this study, the modification to implement the true two-group treatment was performed only in the subroutines of the ＊SIMULATE module of RFSP. This module is the appropriate one to modify first, since it is used for the tracking of reactor operating histories. The modified two-group RFSP was evaluated with true two-group cross sections from WIMS-AECL. Some tests were performed to verify the modified two-group RFSP and to evaluate the effects of fast fission and up-scatter for three core conditions and four cases corresponding to each condition. The comparisons show that the two-group results are quite reasonable and serve as a verification of the modifications made to RFSP. To assess the long-term impact of the full 2-group treatment, it is necessary to simulate a long period (several months) of reactor history. It will also be necessary to implement the full two-group treatment of reactivity devices and assess the reactivity-device worths.ce worths.