• Journal of environmental and Sanitary engineering
• /
• v.18 no.4
• /
• pp.24-35
• /
• 2003

Recent epidemiologic studies revealed that the concentration of air pollutants and fine particulated matter have some effects on health status and are associated with increased mortality and morbidity. The purpose of this study was to characterize background mass concentration of fine particle (PM2.5) and metallic composition from September 2001 to August 2002 in comparison with a medium city, Asan and metropolitan city, Seoul. Conclusively, proper management for fine particles was required in a medium city, Asan, considering the concentrations of metallic elements in fine particles in Asan were relatively higher than those in Seoul. The results were as followed. 1. Average mass concentrations of fine particles in Asan and Seoul were 37.70(${\pm}18.41{\;}{\mu}g/\textrm{m}^3$) and 5.83(${\pm}38.50$) ${\mu}g/\textrm{m}^3$, respectively. When the weather conditions were classified as normal and yellow-sand, measured average mass concentrations of fine particles in yellow-sand weather condition was significantly higher than those of normal weather condition in both cities (p<0.05). 2. Depending on seasons, measured average mass concentrations of fine particles in Asan and Seoul in spring were 47.76(${\pm}19.07$) ${\mu}g/\textrm{m}^3$m and 61.53 (${\pm}4.37$) ${\mu}g/\textrm{m}^3$, respectively. In summer, the average mass concentrations of fine particles in Asan and Seoul were 29.44(${\pm}9.85$) ${\mu}g/\textrm{m}^3$ and 25.42(${\pm}8.10$) ${\mu}g/\textrm{m}^3$, respectively. Especially, the concentration was the highest in spring and the lowest in summer among four seasons. 3. Average concentrations of manganese(Mn), iron(Fe), chromium(Cr), cadmium(Cd), lead(Pb) and silicon(Si) in fine particles in Asan were significantly higher in Seoul (p<0.05). Average concentration of Si in fine particle in Asan was statistically higher than that of Seoul during yellow -sand condition (p<0.05). 4. Considering the characterization of four seasons, average Pb concentration of fine particle in Asan is significantly higher than that of Seoul in spring(p<0.01). In summer, average Mn and Cr concentrations of fine particle in Asan is higher than those of Seoul (p<0.05). Average Mn, Fe. Cr and Si concentrations in fall (p<0.05), and average Mn, Fe, Cr, Pb, and Si concentrations in winter (p<0.05) in Asan were higher than those of Seoul, respectively. 5. Mass concentrations of each Mn, Fe, Cd and Si in fine particles were significantly correlated with both cities. In normal weather condition, Mn, Cu and Si concentrations are statistically significant in Asan, while Mn, Fe, Cu and Si concentrations are statistically significant in Seoul. Mn, Fe and Si concentrations in both cities were statistically significant during yellow-sand weather.

• Nuclear Engineering and Technology
• /
• v.5 no.1
• /
• pp.38-43
• /
• 1973

The spin-rotation constants of the proton and tile fluorine nucleus in C $H_4$, Si $H_4$, Ge $H_4$, C $F_4$, Si $F_4$ and Ge $F_4$ were determined experimentally by the molecular beam magnetic resonance method. From the Hamiltonian and the high field approximation, the quantized energy level is given by the following equation. W $m_{I}$ $m_{J}$=- $g_{I}$ $m_{I}$H- $g_{J}$ $m_{J}$H- $C_{av}$ $m_{I}$ $m_{J}$, where $c_{av}$ is one third of the trace of the C tensor. In the nuclear resonance experiment, the proton and the fluorine nuclear resonance curves consist of many unresolved lines given by v=- $g_{J}$H- $C_{av}$ $m_{I}$, and a Gaussian approximation is made to correlate $c_{av}$ to the experimentally obtained half-width of the resonance curve. In the rotational resonance experiment, the five resonance peaks as predicted by v=- $g_{I}$H- $c_{av}$ $m_{I}$, $m_{I}$=0, $\pm$1 and $\pm$2, were all observed. The magnitude of car was determined by measuring the frequency distance between two adjacent peaks. The sign of $c_{av}$ was determined by the side peak suppression technique. The technique is described, and the sign and magnitude of the spin-rotation constant cav are summarized as following: for C $H_4$ -10.3$\pm$0.4tHz(from the rotational resonance), for SiH +3.71$\pm$0.08kHz(from the nuclear resonance), for Ge $H_4$+3.79$\pm$0.13kHz(from the nuclear resonance), for C $F_4$, -6.81$\pm$0.08kHz(from the rotational resonance), for Si $F_4$, -2.46$\pm$0.06kHz(from the rotational resonance), and finally for Ge $F_4$-1.84$\pm$0.04kHz(from the rotational resonance).onal resonance).esonance).

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1431-1433
• /
• 1995

This paper describes the characteristics of Si Hall sensors fabricated on a SOI(Si-on-insulator} structure, in which the SOI structure was forrmed by SDB(Si-wafer direct bonding) technology. The Hall voltage and the sensitivity of implemented Si Hall devices show good linearity with respect to the applied magnetic flux density and supplied current. The product sensitivity of the SDB SOI Hall device is average $600V/A{\cdot}T$. In the temperature range of 25 to $300^{\circ}C$, the shifts of TCO(Temperature Coefficient of the Offset Voltage) and TCS(Temperature Coefficient of the product Sensitivity) are less than ${\pm}6.7{\times}10^{-3}/^{\circ}C$ and ${\pm}8.2{\times}10^{-4}/^{\circ}C$, respectively. From these results, Si Hall sensors using the SOI structure presented here are very suitable for high-temperature operation.

• The Journal of Korean Society for Radiation Therapy
• /
• v.29 no.2
• /
• pp.75-81
• /
• 2017

Purpose: To evaluate the reproducibility of image-guided radiotherapy using ultrasonography which is non-invasive, without radiation exposure for prostate cancer patients. Materials and Methods: We analyzed the setup variation of 1,105 images for 26 prostate cancer patients and the mean, standard deviation and 3D-error in AP, RL and SI directions. Setup variations were classified 0-1 mm, 1-3 mm, 3-5 mm, 5 mm and more. Results: The mean and standard deviation of setup variation in AP, RL and SI directions was $1.87{\pm}1.36mm$, $1.73{\pm}1.22mm$ and $2.01{\pm}1.40mm$. The 3D-error in AP, RL and SI directions was $3.63{\pm}1.63mm$. The frequency of setup variation in AP direction was 29 % in the range from 0 mm to 1 mm, 50.2 % in the range from 1 mm to 3 mm, 19.6 % in the range from 3 mm to 5 mm and 1.3 % in the range of 5 mm or more. In RL direction, the frequency was 31.3 % in the range from 0 mm to 1 mm, 52.5 % in the range from 1 mm to 3 mm, 15.8 % in the range from 3 mm to 5 mm and 0.5 % in the range of 5 mm or more. SI direction, the frequency of errors in the range from 0 mm to 1 mm was 26.3 %, 50.2 % in the range from 1 mm to 3 mm, 22.4 % in the range from 3 mm to 5 mm, and 1.1 % in the range of 5 mm or more. Conclusion: The setup error was highest in the SI direction of $2.01{\pm}1.40mm$. The frequency in each direction was the highest in more than 50 % in the range from 1 mm to 3 mm. $Clarity^{TM}$ Auto scan is possible to monitoring the motion of the prostate during the treatment and to repositioning the patient. In conclusion real-time image-guided radiotherapy using ultrasonography will be increase the reproducibility of radiation therapy.

• Korean Journal of Materials Research
• /
• v.4 no.5
• /
• pp.493-501
• /
• 1994

DSC와 XRD를 사용하여 Zr/Si 다층박막의 고상반응에 의한 비정질상과 결정상 생성 및 상전이를 확인하고 이를 유효구동력 개념과 유효생성열 개념 및 phase determining factor(PDF)모델을 이용하여 예측한 결과와 비교하였다. Zr/Si 다층박막은 비정질호 반응이 잘 일어났으며 이는 유효구동력 개념으로 예측한 바와 일치하였다. Zr/Si 계에서 생성되는 최초의 결정상은 ZrSi 였으며 유효생성열과 PDF모델로부터 예측된 최초의 결정상은 PDF 모델의 예측 결과와 일치하였다. Zr/Si 다층박막의 원자조성비가 1대 1일경우와 1대 2일 경우의상전이는 ZrSi$\longrightarrow$$ZrSi_{2}$로 되었으며 이러한 상전이 과정은 유효생성열 다이아그램으로 해석되었다. ZrSi의 생성기구는 핵생성이 율속임을 규명하였고 ZrSi와 $ZrSi_{2}$의 생성에 필요한 활성화에너지는 1.64$\pm$0.19eV와 2.28$\pm$0.36eV이었다.

• Journal of the Korean Society of Radiology
• /
• v.17 no.7
• /
• pp.1139-1147
• /
• 2023

The purpose of this paper is to present and evaluate the performance of a method for controlling the dose for optimal image acquisition while minimizing patient exposure by applying a small-sized Photomultiplier(SiPM) sensor inside a portable detector. Portable detectors have the advantage of being able to quickly access the patient's location for rapid diagnosis, but this mobility comes with the challenge of dose control. This paper presents a method to identify the dose that can have the DQE and optimal image quality of the detector through image evaluation based on IEC62220-1-1, an international standard for X-ray imaging devices, and to identify the optimal dose by matching the ADU of the image and the output of the SiPM Sensor. The Skull AP image was acquired by implementing the detector manufacturer's reference dose. The optimal dose was 342.8 µGy, and the optimal controlled dose was 148.3 µGy, which is 57 % of the manufacturer's reference dose. The Chest AP image was 81.9 µGy and the optimal controlled dose was 27.9 µGy, which is a high dose reduction effect of 66 %. In addition, the two images were analyzed by five radiologists and found to have no clinically significant difference in anatomical delineation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.2
• /
• pp.101-105
• /
• 2007

We have synthesized silicon nanowires by using RFCVD(Radio Frequency Chemical Vapor Deposition) system on Au deposited p-type Si(100) wafers, and investigated their physical and electrical properties. The silicon nanowires had been grown in the atmospheres of $H_{2},\;N_{2}\;and\;SiH_{4}$ at 10 Torr at the substrate temperatures of $700{\pm}5^{\circ}C\;and\;810{\pm}5^{\circ}C$ respectively. FE-SEM analysis revealed that diameters of the silicon nanowires are $50{\sim}60nm$ with the length of several ${\mu}m$. XRD analysis showed that the growth direction of the nanowires is Si[111]. Field emission characteristics showed that the turn-of voltages at the current of $0.01\;mA/cm^{2}$ are $10\;V/{\mu}m\;and\;8.5\;V/{\mu}m$ for the wires grown at $700{\pm}5^{\circ}C\;and\;810{\pm}5^{\circ}C$, respectively.

• Nuclear Engineering and Technology
• /
• v.55 no.10
• /
• pp.3844-3853
• /
• 2023

Although radiation and chemotherapy methods for cancer therapy have advanced significantly, surgical resection is still recommended for most cancers. Therefore, intraoperative imaging studies have emerged as a surgical tool for identifying tumor margins. Intraoperative imaging has been examined using conventional imaging devices, such as optical near-infrared probes, gamma probes, and ultrasound devices. However, each modality has its limitations, such as depth penetration and spatial resolution. To overcome these limitations, hybrid imaging modalities and tracer studies are being developed. In a previous study, a multi-modal laparoscope with silicon photo-multiplier (SiPM)-based gamma detection acquired a 1 s interval gamma image. However, improvements in the near-infrared fluorophore (NIRF) signal intensity and gamma image central defects are needed to further evaluate the usefulness of multi-modal systems. In this study, an attempt was made to change the NIRF image acquisition method and the SiPM-based gamma detector to improve the source detection ability and reduce the image acquisition time. The performance of the multi-modal system using a complementary metal oxide semiconductor and modified SiPM gamma detector was evaluated in a phantom test. In future studies, a multi-modal system will be further optimized for pilot preclinical studies.

• Journal of the Mineralogical Society of Korea
• /
• v.21 no.3
• /
• pp.321-329
• /
• 2008

Amorphous silica nanoparticles are among the most fundamental $SiO_2$ compounds, having implications in diverse geological processes and technological applications. Here, we explore structural details of amorphous silica nanoparticles with varying particle sizes (7 and 14 nm) using $^{29}Si$ and $^{1}H$ MAS NMR spectroscopy together with quantum chemical calculations to have better prospect for their size-dependent atomic structures. $^{29}Si$ MAS NMR spectra at 9.4 T resolve $Q^2,\;Q^3$ and $Q^4$ species at -93 ppm, -101 ppm, -110 ppm, respectively. The fractions of $Q^2,\;Q^3,\;O^4$ species are $7{\pm}1%,\;27{\pm}2%$, and $66{\pm}2%$ for 7 nm amorphous silica nanoparticles and $6{\pm}1%,\;21{\pm}2%$, and $73{\pm}2%$ for 14 nm amorphous silica nanoparticles. Whereas it has been suggested that $Q^2$ and $Q^3$ species exist on particles surfaces, the difference in $Q^{2}\;+\;Q^{3}$ fraction in both 7 and 14 nm particles is not significant, suggesting that $Q^2$ and $Q^3$ species could exist inside particles. $^{1}H$ MAS NMR spectra at 11.7 T shows diverse hydrogen environments, including physisorbed water, hydrogen bonded silanol, and non-hydrogen bonded silanol with varying hydrogen bond strength. The hydrogen contents in the 7nm silica nanoparticles (including water and hydroxyl groups) are about 3 times of that of 14 nm particles. The larger chemical shills for proton environments in the former suggest stronger hydrogen bond strength. The fractions of non-hydrogen bonded silanols in the 14 nm amorphous silica nanoparticles are larger than those in 7 nm amorphous silica nanoparticles. This observation suggests closer proximity among hydrogen atoms in the nanoparticles with smaller diameter. The current results with high-resolution solid-state NMR reveal previously unknown structural details in amorphous silica nanoparticles with particle size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.05a
• /
• pp.227-229
• /
• 1995

Using thermal oxide SiO$_2$ as a dielectrical isolation layer, SOI Hall sensors without pn junction isolation have been fabricated on Si/SiO$_2$/Si structures. The SOI structure was formed by SDB (Si- wafer direct bonding) technology. The Hall voltage and the sensitivity of Si Hall devices implemented on the SDB SOI structure show good linearity with respect to the appled magnetic flux density and supplied current. The product sensitivity of the SDB SOI Hall device is average 600V/V.T. In the trmperature range of 25 to 300$^{\circ}C$, the shifts of TCO(Temperature Coefficient of the Offset Voltage) and TCS(Temperature Coefficient of the Product Sensitivity) are less than ${\pm}$ 6.7x10$\^$-3/ C and ${\pm}$8.2x10$\^$04/$^{\circ}C$, respectively. These results indicate that the SDB SOI structure has potential for the development of Hall sensors with a high-sensitivity and high-temperature operation.