• 전기학회논문지
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• 제60권1호
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• pp.201-204
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• 2011

For efficient noise reduction in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrum, a new algorithm was proposed. The suggested algorithm reduces white and electrical noise, and it improves signal-to-noise ratio. This algorithm has been optimized to reduce the noise more efficiently using the traces of signal level. The algorithm has been efficiently combined with derivative window to improve the resolution as well S/N. Time domain data was corrected for DC voltage interference. $t^n$ window was applied in time domain data to improved the resolution. However, $t^n$ window can improve the signal resolution, it will also increase the noise level in frequency domain. Therefore, newly developed noise reduction algorithm will be applied to make a balance between resolving power and S/N ratio for magnitude mode. The trace algorithm can determine the current data point with several data points (mean, past data, calculated past data). In the current calculations, we assumed data points with S/N ratio more than 3 were considered as signal data points. After the windowing and noise reduction, both resolution and signal-to-noise ratio were improved. This algorithm is applicable more efficiently to frequency dependent noise and large size data.

• 한국초전도ㆍ저온공학회논문지
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• 제8권1호
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• pp.59-64
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• 2006

A closed-loop cryogenic cooling system for high field magnets is presented. This design is motivated by our recent development of cooling system for 21 tesla Fourier Transform ion Cyclotron Resonance (FT-ICR) superconducting magnets without any replenishment of cryogen. The low temperature superconducting magnets are immersed in a subcooled 1.8 K bath, which is connected hydraulically to the 4.2 K reservoir through a narrow channel. Saturated liquid helium is cooled by Joule-Thomson heat exchanger and flows through the JT valve, isenthalpically dropping its pressure to approximately 1 6 kPa, corresponding saturation temperature of 1.8 K. Helium gas exhausted from pump is now recondensed by two-stage cryocooler located after vapor purify system. The amount of cryogenic Heat loads and required mass flow rate through closed-loop are estimated by a relevant heat transfer analysis, from which dimensions of JT heat exchanger and He II heat exchanger are determined. The detailed design of cryocooler heat exchanger for helium recondensing is performed. The effect of cryogenic loads, especially superfluid heat leak through the gap of weight load relief valve, on the dimensions of cryogenic system is also investigated.

• 한국초전도ㆍ저온공학회논문지
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• 제8권4호
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• pp.30-33
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• 2006

Several crucial issues are discussed in the design of cryogenic cooling system for high field magnets. This study is mainly motivated by our ongoing program to develop a 21 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS). The magnets of this system will be built horizontally to accomplish the requirement of user friendliness and reliability, and the replenishment of cryogen will not be necessary by a closed-loop cooling concept. The initial cool-down and safety are basically considered in this paper. The effects of the helium II volume and the gap distance of the weight load relief valve (or safety valve) on the cool-down time and temperature rising during an off-normal state are discussed. The total amount of cryogenic cooling loads and the required helium flow rate during cool-down are also estimated by a relevant heat transfer analysis. The temperatures of cryogen-free radiation shield are finally determined from the refrigeration power of a cryocooler and the total cryogenic loads.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2057-2064
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• 2014

Thermochemical sulfate reduction (TSR) was conducted in autoclave on the system of crude oil and $MgSO_4$ at different temperatures. Gas chromatography pulsed flame photometric detector (GC-PFPD) was used to detected the composition of organic sulfur compounds in oil phase products. The results of the analysis indicate that with increased temperature, the contents of organic sulfur compounds with high molecular weight and thermal stability, such as benzothiophenes and dibenzothiophenes, gradually became dominated. In order to gain greater insight into the formation and distribution of organic sulphur compounds from TSR, positive ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used in detecting the detailed elemental composition and distribution of them. The mass spectra showed that the mass range of sulfur compounds was 200-550 Da. Four sulfur class species, $S_1$, $N_1S_1$, $O_1S_1$ and $O_2S_1$, were assigned in the positive-ion spectrum. Among the identified sulfur compounds, the $S_1$ class species was dominant. The most abundant $S_1$ class species increase associated with the DBE value and carbon number increasing which also indicates the evolution of organic sulfur compounds in TSR is from the labile series to the stable one. In pure blank pyrolysis experiments with crude oil cracking without TSR, different composition and distribution of organic sulfur compounds in oil phase products were seen from mass spectra in order to evaluate their pyrolysis behaviors without $MgSO_4$. FT-IR and XRD were used in analyzing the products of solid phases. Two distinct crystallographic phases MgO and $MgSO_4$ are found to coexist in the products which demonstrated the transformation of inorganic sulfur compounds into organosulfur compounds exist in TSR.

• 한국진공학회지
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• 제10권1호
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• pp.119-126
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• 2001

ECR-PECVD 방법으로 ECR 플라즈마 소스 power, $CH_4/H_2$ 가스 혼합비와 유량, 증착시간 및 기판 bias 전압을 변화시켜 가면서 수소가 함유된 비정질 탄소 박막을 증착하고, 증착조건에 따라서 박막 내부에 함유되어 있는 수소함량 변화를 2.5 MeV 헬륨 이온빔을 사용하는 ERDa로 측정하였다. ERDA의 결과와 hES 및 RBS에 의한 성분분석으로부터 본 실첨에서 증착된 박막은 탄소와 수소만으로 구성 되어있음을 확인할 수 있었고, FTIR의 결과로부터 박막 증착조건에 따라서 박막 내부에 함유되어 있는 수소함량이 변화함을 알 수 있었다. 기판 bias 전압을 증가시킬수록 이온충돌 현상이 두드러져 탄소와 결합하고 있던 수소원자들이 떨어져 나가는 탈수소화 현상으로 수소함량이 크게 감소됨을 알 수 있었다. 그 밖의 조건에서는 박막증착 초기에는 수소보다 탄소량이 좀 더 많다가 점차적으로 수소함량이 증가되었고, 이때 박막 내부에 함유되어 있는 수소함량은 45~55% 범위 내에 있음을 확인할 수 있었다.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.192-199
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• 2021

Alpine glaciers harbor a large quantity of bio-labile dissolved organic matter (DOM), which plays a pivotal role in global carbon cycling as glacial-fed streams are headwaters of numerous large rivers. To understand the complexity, origin, and fate of DOM in glaciers and downstream-linked streams and lakes, we elucidated the molecular composition of DOM in two different Tibetan Plateau glaciers, eight glacial-fed streams and five lakes, using an ultrahigh-resolution 15 Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The compositional changes of the DOM samples revealed that glacier DOM mostly exhibited sulfur-containing organic compounds (CHOS species). We also found that aliphatic formulae contributed more than 50% of the total abundance of assigned molecules in glacier samples, and those compounds were significantly related to CHOS species. The CHO proportions of glacial-fed streams and lakes samples increased with increasing distance from glacial terminals. The relative contribution of terrestrial-derived organics (i.e., lignins and tannins) declined while microbial-originated organics (aliphatics) increased with increasing elevation. This suggested the gradual input of allochthonous materials from non-glacial environment and the degradation of microbe-derived compounds along lower elevations. Alpine glaciers are retreating as a result of climate change and they nourished numerous streams, rivers, and downstream-linked lakes. Therefore, the interpretations of the detailed molecular changes in glacier ice, glacial-fed streams, and alpine lakes on the Tibetan Plateau could provide broad insights for understanding the biogeochemical cycling of glacial DOM and assessing how the nature of DOM impacts fluvial ecosystems.

• 한국작물학회지
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• 제67권4호
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• pp.211-221
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• 2022

논 토양 조건에서 팥의 생육기 중 초기 생육 단계에 해당되는 유묘기에 과습 스트레스 처리 후 생육특성 변화 및 팥잎의 단백질 발현 양상을 조사한 결과는 다음과 같다. 1. 아라리(밀양 8호)를 공시 품종으로 과습 스트레스 실험을 진행하였다. 3일간 과습 처리하는 동안 팥의 초장과 생체중(잎, 줄기)은 통계적으로 유의하지는 않았으나 생체중(뿌리)와 SPAD value 값은 통계적으로 유의한 결과가 나왔다. 2. 과습 처리 3일 후 잎의 단백질 발현 양상을 확인한 결과 21개의 차별 발현된 단백질 중 과습 스트레스 처리에 의해 9개의 단백질들이 up-regulated 되었고, 12개의 단백질들이 down-regulated 되었다. 단백질을 기능별로 분류한 결과 Biological Process에서 carbohydrate metabolic process와 관련된 단백질들이 가장 많이 나왔고 Cellular Component에서는 Chloroplast에서 가장 많이 존재하였다. 3. Regulatory protein과 관련된 Maturase K 단백질은 처리구에서 대조구보다 발현양이 증가한 것으로 나타났다. 4. Carbohydrate metabolic process와 관련된 Malate dehydrogenase 단백질과 Glyceraldehyde-3-phosphate dehydrogenase 단백질은 과습 스트레스를 받았을 경우 단백질 발현양이 증가하였다. 5. Photosynthesis와 관련된 Carbonic anhydrase (CA)는 처리구보다 대조구에서 단백질 발현량이 더 증가한 것을 확인할 수 있었다. 스트레스와 관련된 단백질 Superoxide dismutase는 처리구에서 대조구보다 단백질 발현양이 증가한 것을 확인할 수 있었다.