• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.628-631
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• 2004

A tetrafluoromethane$(CF_4)$ is most useful gas in plasma dry etching, because it has a electron attachment cross-section. therefor it is important to calculate transport coefficients like electron drift velocity, ionization coefficient, attachment coefficient, effective ionization coefficient. and critical E/N. The aim of this study is to get these transport coefficients for information of the insulation strength and efficiency of etching process. Electron transport coefficients in $CF_4+Ar$ gas mixture are simulated in range of E/N values from 1 to 250 [Td] at 300[K} and 1 [Torr] by using Boltzmann equation method. The results of this method can be important data to present characteristic of gas for plasma etching and insulation, specially critical E/N is a data to evaluate insulation strength of a gas. and is presented in this paper for various mixture ratios of $CF_4+Ar$ gas mixture.

• Journal of Radiation Protection and Research
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• 제31권3호
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• pp.149-153
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• 2006

An ionization chamber is still widely used in many fields by virtue of its' simple operational characteristics and the possibility of its' various shapes. A parallel type of an ionization chamber for a steel sheet thickness measurement was designed and fabricated. High pure xenon gas, which was pressurized up to 6 atm, was chosen as a filling gas to increase the current response and sensitivity for a radiation. A high pressure gas system was also constructed. The active volume and the incident window size of the fabricated ionization chamber were $30\;cm^3\;and\;12\;cm^2$, respectively. Preliminary tests with a 25 mCi $^{241}Am$ gamma-ray source and evaluation tests in a standard X-ray field were performed. The optimal operation voltage was set from the results of the collection efficiency calculation by using an experimental two-voltage method. Linearity for a variation of the steel sheet thickness, which is the most important factor for an application during a steel sheet thickness measurement, was 0.989 in this study.

• 한국환경과학회지
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• 제21권9호
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• pp.1163-1169
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• 2012

Destruction and removal efficiency (DRE) of $SF_6$ was tested with low degrees of ionization. The applied dose of ionization energy varied from 63.70 to 212.34 kGy. The initial concentration and flow rate of $SF_6$ gas were 1,000 ppm and 50L/min, respectively. In order to increase the DRE, injection of conditioning agent ($H_2$) were conducted. The DRE of $SF_6$ increased about 2 times with injection of $H_2$ gas.

• Journal of Radiation Protection and Research
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• 제9권1호
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• pp.11-18
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• 1984

Well type 전리함과 미세전류 측정희로를 사용하여 표준 감마선 전리함 장치를 개발하였다. 미세전류는 automatic Townsend balance with stepwise compensation방법을 사용하여 측정하였다. $^{226}Ra$을 기준 선원으로 택하여 감마 방출핵종인 $^{241}Am,\;^{133}Ba,\;^{60}Co,\;^{134}Cs,\;^{137}Cs^{22}Na$에 대한 비교 교정인자를 산출하였으며, 감마에너지의 함수로서 검출 효율 곡선을 구하였다.

• Mass Spectrometry Letters
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• 제15권1호
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• pp.26-39
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• 2024

Gold nanostructures (Au NSs) are useful and interesting matrices for mass spectrometric analysis of various biomolecules based on organic matrix-free laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF-MS). Au NSs provide high efficiency and versatility in LDI-TOF-MS analysis based on their well-established synthesis and surface functionalization, large surface area, high laser absorption capacity, and photothermal conversion efficiency. Therefore, Au NSs based LDI-TOF-MS can be a facile, functional, and efficient analytical method for important small biomolecules owing to its simple preparation, rapid analysis, salt-tolerance, signal reproducibility, and quantitative analysis. This review chronologically summarizes the important advance of Au NSs-based LDI-TOF-MS platforms in terms of in-depth mechanism, signal enhancement, quantitative analysis, and disease diagnosis.

• Molecules and Cells
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• 제23권3호
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• pp.340-348
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• 2007

Although considerable effort has been devoted in the mass spectrometric analysis of phosphorylated peptides, successful identification of multi-phosphorylated peptides in enzymatically digested protein samples still remains challenging. The ionization behavior of multi-phosphorylated peptides appears to be somewhat different from that of mono- or di-phosphorylated peptides. In this study, we demonstrate increased sensitivity of detection of multi-phosphorylated peptides of beta casein without using phosphopeptide enrichment techniques. Proteinase K digestion alone increased the detection limit of beta casein multi-phosphorylated peptides in the LC-MS analysis almost 500 fold, compared to conventional trypsin digestion (~50 pmol). In order to understand this effect, various factors affecting the ionization of phosphopeptides were investigated. Unlike ionizations of phosphopeptides with minor modifications, those of multi-phosphorylated peptides appeared to be subject to effects such as selectively suppressed ionization by more ionizable peptides and decreased ionization efficiency by multi-phosphorylation. The enhanced detection limit of multi-phosphorylated peptides resulting from proteinase K digestion was validated using a complex protein sample, namely a lysate of HEK 293 cells. Compared to trypsin digestion, the numbers of phosphopeptides identified and modification sites per peptide were noticeably increased by proteinase K digestion. Non-specific proteases such as proteinase K and elastase have been used in the past to increase detection of phosphorylation sites but the effectiveness of proteinase K digestion for multi-phosphorylated peptides has not been reported.

• Tribology and Lubricants
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• 제37권6호
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• pp.208-212
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• 2021

Chemical mechanical polishing (CMP) is a key technology used for the global planarization of thin films in semiconductor production and smoothing the surface of substrate materials. CMP is a type of hybrid process using a material removal mechanism that forms a chemically reacted layer on the surface of a material owing to chemical elements included in a slurry and mechanically removes the chemically reacted layer using abrasive particles. Sapphire is known as a material that requires considerable time to remove materials through CMP owing to its high hardness and chemical stability. This study introduces a technology using electrolytic ionization and ultraviolet (UV) light in sapphire CMP and compares it with the existing CMP method from the perspective of the material removal rate (MRR). The technology proposed in the study experimentally confirms that the MRR of sapphire CMP can be increased by approximately 29.9, which is judged as a result of the generation of hydroxyl radicals (·OH) in the slurry. In the future, studies from various perspectives, such as the material removal mechanism and surface chemical reaction analysis of CMP technology using electrolytic ionization and UV, are required, and a tribological approach is also required to understand the mechanical removal of chemically reacted layers.

• 한국의학물리학회지:의학물리
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• 제25권1호
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• pp.46-52
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• 2014

액체 전리함은 공동 전리함과 달리 감응매질이 물 등가물질로 이루어져 있어서, 감도가 매우 높아서 충분히 작게 만들 수 있기 때문에 기준 조사면 뿐만 아니라 소조사면의 선량 평가에 유용하다는 장점이 있지만, 이온 재결합 손실 계산에 있어 초기 재결합과 일반 재결합을 모두 고려해야 하므로, 사용상에 어려움이 따른다. 본 연구에서는 연속 빔인 코발트 60 빔에서 PTW사의 microLion 액체 전리함을 이용하여 Greening 이론식과 이선량률법 및 다른 실험을 이용하여 수집효율을 구하고, 비교하는 연구를 수행하였다. 이는 코발트 장비인 Theratron 780과 물팬톰을 이용하여 수행하였으며, 선량률에 따른 microLion 전리함의 전하량을 측정하기 위해 0.6 cc 공동 전리함을 같은 조건에서 동시에 측정하였다. 이때 선량률의 범위는 0.125~0.746 Gy/min이였으며, 각 선량률에서 +400, +600 및 +800 전압에 대하여 액체 전리함을 이용하여 전하량을 측정하였다. 측정된 데이터를 이용하여 세 가지 방법에 따라 계산된 수집효율은 대체로 1% 이내로 일치하였다. 특히 본 연구에서 실험을 통해 구한 수집효율은 가장 낮은 두 선량률을 제외하고는 0.3% 이내로 잘 일치함을 보였다. 이선량률법의 경우 Greening 이론식과 비교하여 대체로 1% 이내의 차이를 보였지만, 두 선량률의 차이가 적을 때 대략 4% 가까운 차이를 보임을 확인하였다. TRS-398 물흡수선량 프로토콜에서 권고하는 표면과 선원간의 거리가 80 cm이고, 깊이 5 cm에서 Greening 이론법과 이선량률법, 본 연구에서 실험을 통해 얻은 방법에 의한 이온 재결합 보정계수는 각각 1.0233, 1.0239, 1.0316으로, 이 조건에서 대략 3%의 이온 재결합에 의한 손실이 발생함을 확인하였다. 본 연구에서 실험을 통해 이온 재결합 손실을 계산하는 방법은 다른 두 선량률에서 액체 전리함의 보정된 전하량을 이용하여 손쉽게 결정할 수 있기 때문에 연속 빔에서 선량 평가 시에 매우 유용하게 사용될 수 있으리라 판단된다.

• Journal of Microbiology and Biotechnology
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• 제25권5호
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• pp.704-708
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• 2015

For the analysis of multiple-reaction intermediates for long-chain dicarboxylic acid biotransformation, simple and reproducible methods of extraction and derivatization were developed on the basis of gas chromatography with flame ionization detector (GC-FID) instead of mass spectrometry. In the derivatization step, change of the ratio of pyridine to MSTFA from 1:3 to 9:1 resulted in higher peak intensity (p = 0.021) and reproducibility (0.6%CV) when analyzing 32 g/l ricinoleic acid (RA). Extraction of RA and ω-hydroxyundec-9-enoic acid with water containing 100 mM Tween 80 showed 90.4-99.9% relative extraction efficiency and 2-7%CV compared with those with hydrophobic ethyl acetate. In conclusion, reduction of the pyridine content and change of the extraction solvent to water with Tween 80 provided compatible derivatization and extraction methods to GC-FID-based analysis of longchain carboxylic acids.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3417-3422
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• 2023

Recently, as the clinically positive biological effects of ultra-high dose rate (UHDR) radiation beams have been revealed, interest in flash radiation therapy has increased. Generally, FLASH preclinical experiments are performed using UHDR electron beams generated by linear accelerators. Real-time monitoring of UHDR beams is required to deliver the correct dose to a sample. However, it is difficult to use typical transmission-type ionization chambers for primary beam monitoring because there is no suitable electrometer capable of reading high pulsed currents, and collection efficiency is drastically reduced in pulsed radiation beams with ultra-high doses. In this study, a monitoring method using bremsstrahlung photons generated by irradiation devices and a water phantom was proposed. Charges collected in an ionization chamber located at the back of a water phantom were analyzed using the bremsstrahlung tail on electron depth dose curves obtained using radiochromic films. The dose conversion factor for converting a monitored charge into a delivered dose was determined analytically for the Advanced Markus® chamber and compared with experimentally determined values. It is anticipated that the method proposed in this study can be useful for monitoring sample doses in UHDR electron beam irradiation.