• 한국방사선학회논문지
• /
• 제14권7호
• /
• pp.849-856
• /
• 2020

감마선 에너지 스펙트럼 연구에서 에너지 분석을 통한 핵종 분석은 매우 중요하다. 감마선 에너지 측정에 일반적으로 사용되는 고순도 Ge 검출기는 높은 에너지 분해능과 상대적으로 높은 검출 효율 때문에 일반적으로 사용된다. 그러나 반도체 검출기는 높은 에너지 분해능을 유지하기 위해 주변 환경에서 발생하는 노이즈를 효과적으로 차단하지 않으면 원래의 성능을 유지하기 어렵고 고가의 장치의 효과를 얻지 못하는 문제점이 있. 따라서 본 연구에서는 검출기에서 발생하는 전기적 노이즈를 제거하기 위해 접지 루프 아이솔레이터 (NEXT-001HDGL)를 사용했다. 에너지 분해능 향상 효과를 테스트하기 위해 양성자 가속기 KOMAC에 새로 설치된 HPGe 검출 장치를 사용했다. 감마선 에너지 2614 keV의 경우 에너지 분해능이 (0.16 ± 0.02) %에서 (0.11 ± 0.01) %로 개선되었고, 감마선 에너지 662 keV의 경우 에너지 분해능이 (0.72 ± 0.07) %에서 0.27 ± 0.03 %로 향상되었다. 이 결과는 KOMAC (Korea Multi-Purpose Accelerator Complex)의 HPGe 검출 장비를 이용한 감마선 스펙트럼 연구에 매우 유용한 것으로 판단된다.

• EDISON SW 활용 경진대회 논문집
• /
• 제3회(2014년)
• /
• pp.457-458
• /
• 2014

In this paper, quantum mechanical simulations of the double-gate ultra-thin body (DG-UTB) MOSFETs are performed according to the International Technology Roadmap of Semiconductors (ITRS) specifications planned for 2020, to devise the way for on-current ($I_{on}$) improvement. We have employed non-equilibrium Green's function (NEGF) approach and solved the self-consistent equations based on the parabolic effective mass theory [1]. Our study shows that the [100]/<001> Ge and GaSb channel devices have higher $I_{on}$ than Si channel devices under the body thickness ($T_{bd}$) <5nm condition.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2002년도 제23회 학술발표회 초록집
• /
• pp.162-162
• /
• 2002

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2007년도 제33회 하계학술대회 초록집
• /
• pp.299-299
• /
• 2007

• Korean Journal of Radiology
• /
• 제25권9호
• /
• pp.833-842
• /
• 2024

Objective: To assess the effect of a new lung enhancement filter combined with deep learning image reconstruction (DLIR) algorithm on image quality and ground-glass nodule (GGN) sharpness compared to hybrid iterative reconstruction or DLIR alone. Materials and Methods: Five artificial spherical GGNs with various densities (-250, -350, -450, -550, and -630 Hounsfield units) and 10 mm in diameter were placed in a thorax anthropomorphic phantom. Four scans at four different radiation dose levels were performed using a 256-slice CT (Revolution Apex CT, GE Healthcare). Each scan was reconstructed using three different reconstruction algorithms: adaptive statistical iterative reconstruction-V at a level of 50% (AR50), Truefidelity (TF), which is a DLIR method, and TF with a lung enhancement filter (TF + Lu). Thus, 12 sets of reconstructed images were obtained and analyzed. Image noise, signal-to-noise ratio, and contrast-to-noise ratio were compared among the three reconstruction algorithms. Nodule sharpness was compared among the three reconstruction algorithms using the full-width at half-maximum value. Furthermore, subjective image quality analysis was performed. Results: AR50 demonstrated the highest level of noise, which was decreased by using TF + Lu and TF alone (P = 0.001). TF + Lu significantly improved nodule sharpness at all radiation doses compared to TF alone (P = 0.001). The nodule sharpness of TF + Lu was similar to that of AR50. Using TF alone resulted in the lowest nodule sharpness. Conclusion: Adding a lung enhancement filter to DLIR (TF + Lu) significantly improved the nodule sharpness compared to DLIR alone (TF). TF + Lu can be an effective reconstruction technique to enhance image quality and GGN evaluation in ultralow-dose chest CT scans.

• Journal of Korean Vacuum Science & Technology
• /
• 제2권2호
• /
• pp.107-117
• /
• 1998

Epitaxial undoped and Sb-doped si films have been grown on Si(001) substrates at temperatures T between 80 and 750$^{\circ}C$ using energetic Si in ultra-high-vacuum Kr+-ion-beam sputter deposition(IBSD). Critical epitaxial thicknesses te, The average thickness of epitaxial layers, in undoped films were found to range from 8nm at Ts=80$^{\circ}C$ to > 1.2 ${\mu}$m at Ts=300$^{\circ}C$ while Sb incorporation probabilities $\sigma$sb varied from unity at Ts 550$^{\circ}C$ to 0.1 at 750$^{\circ}C$. These te and $\sigma$Sb values are approximately one and one-to-three orders of magnitude, respectively, higher than reported results achieved with molecular-beam epitaxy. Plan-view and cross-sectional transmission electron microscopy, high-resolution x-ray diffraction, channeling and axial angular-yield profiles by Rutherford back scattering spectroscopy for epitaxial Si1-x Gex(001) alloy films (0.15$\leq$x$\leq$0.30) demonstrated that the films are of extremely high crystalline quality. critical layer thicknesses hc the film thickness where strain relaxation starts, I these alloys wre found to increase rapidly with decreasing growth temperature. For Si0.70 Ge0.30, hc ranged from 35nm at Ts=550$^{\circ}C$ to 650nm at 350$^{\circ}C$ compared to an equilibrium value of 8nm.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제16권6호
• /
• pp.1-9
• /
• 2011

A bibliographical review of Gy sampling theory for particulate materials was conducted to provide readers with useful means to reduce errors in soil contamination investigation. According to the Gy theory, the errors caused by the heterogeneous nature of soil include; the fundamental error (FE) caused by physical and chemical constitutional heterogeneity, the grouping and segregation error (GE) aroused from gravitational force, long-range heterogeneous fluctuation error ($CE_2$), the periodic heterogeneity fluctuation error ($CE_3$), and the materialization error (ME) generated during physical process of sample treatment. However, the accurate estimation of $CE_2$ and $CE_3$ cannot be estimated easily and only increasing sampling locations can reduce the magnitude of the errors. In addition, incremental sampling is the only method to reduce GE while grab sampling should be avoided as it introduces uncertainty and errors to the sampling process. Correct preparation and operation of sampling tools are important factors in reducing the incremental delimitation error (DE) and extraction error (EE) which are resulted from physical processes in the sampling. Therefore, Gy sampling theory can be used efficiently in planning a strategy for soil investigations of non-volatile and non-reactive samples.

• Asian-Australasian Journal of Animal Sciences
• /
• 제29권2호
• /
• pp.204-210
• /
• 2016

This study examined the effect of supplementing exogenous cellulase on nutrient and energy utilization. Twelve desexed Boer crossbred goats were used in a replicated $3{\times}3$ Latin square design with 23-d periods. Dietary treatments were basal diet (control, no cellulase), basal diet plus 2 g unitary cellulase/kg of total mixed ration dry matter (DM), and basal diet plus 2 g compound cellulase/kg of total mixed ration DM. Three stages of feeding trials were used corresponding to the three treatments, each comprised 23 d, with the first 14 d as the preliminary period and the following 9 d as formal trial period for metabolism trial. Total collection of feces and urine were conducted from the 4th d of the formal trial, and gas exchange measures were determined in indirect respiratory chambers in the last 3 d of the formal trial. Results showed that cellulase addition had no effect (p>0.05) on nutrient digestibility. Dietary supplementation of cellulase did not affect (p>0.05) N intake and retention in goats. Gross energy (GE) intake, fecal energy and urinary energy excretion, heat production were not affected (p>0.05) by the cellulase supplementation. Total methane emission (g/d), $CH_4$ emission as a proportion of live weight or feed intake (DM, organic matter [OM], digestible DM or digestible OM), or $CH_4$ energy output ($CH_4$-E) as a proportion of energy intake (GE, digestible energy, or metabolizable energy), were similar (p>0.05) among treatments. There was a significant (p<0.001) relationship between $CH_4$ and live weight (y = 0.645x+0.2, $R^2$ = 0.54), $CH_4$ and DM intake (y = 16.7x+1.4, $R^2$ = 0.51), $CH_4$ and OM intake (y = 18.8x+1.3, $R^2$ = 0.51) and $CH_4$-E and GE intake. Results from this study revealed that dietary supplementation of cellulase may have no effect on nutrient digestibility, nitrogen retention, energy metabolism, and methane emission in goat.

• 한국연소학회지
• /
• 제18권1호
• /
• pp.1-6
• /
• 2013

Authors' previous works on thermoacoustic(TA) model development showed good results in predicting combustion instability characteristics in a gas turbine combustor. However, they also suggested there were some limitations in growth rate estimation, which might be related with over-simplification of flame structure. As a first trial for improving the model accuracy, the current paper introduces the modified TA model considering the actual flame location in the combustor. The combustor is divided into the unburned and the burned area before and after the flame location, and then acoustic equations are re-organized. The modified TA model results show a better accuracy in predicting the growth rate of instabilities comparing with the previous results. However, obtained results still overestimate the conditions where the combustor goes unstable. Further researches considering heat release distribution through flames are required.

• 마이크로전자및패키징학회지
• /
• 제27권1호
• /
• pp.1-7
• /
• 2020

The backside metallization process is typically used to attach a chip to a lead frame for semiconductor packaging because it has excellent bond-line and good electrical and thermal conduction. In particular, the backside metal with the Ag/Sn/Ag sandwich structure has a low-temperature bonding process and high remelting temperature because the interfacial structure composed of intermetallic compounds with higher melting temperatures than pure metal layers after die attach process. Here, we introduce a die attach process with the Ag/Sn/Ag sandwich structure to apply commercial semiconductor packages. After the die attachment, we investigated the evolution of the interfacial structures and evaluated the shear strength of the Ag/Sn/Ag sandwich structure and compared to those of a commercial backside metal (Au-12Ge).