• Nuclear Engineering and Technology
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• 제54권2호
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• pp.437-441
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• 2022

In this study, we developed a neutron time-of-flight (nTOF) measurement system for a 1.7-MV tandem proton accelerator with a target covered with 300-nm-thick lithium (Li) layer. With implementation of beam chopping module after its ion source, the accelerator is configured to operate in pulsed-beam mode with a pulse width <50 ns at 20-kHz repetition rate. This enables the gamma flash-type nTOF measurement system to identify the neutron generated with 3-MeV proton beam energy. The nTOF system consists of a 30" cylindrical NaI(Tl) and four stilbene scintillation detectors. The NaI(Tl) scintillator is placed 50 cm from the Li target to measure the time of beam irradiation on the target, and the stilbene detectors are placed 2 and 2.4 m away to measure nTOF at each location. The nTOF system successfully measured the generated neutron energy at irradiated proton energies of 2.6 and 3.0 MeV with an average energy resolution of 15%.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.164-164
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• 2000

Since Au-Pt alloys have various atomic structures depending upon composition and annealing temperature, it is very interesting to investigate the electronic structures of alloys. We studied the changes of the electronic structure I the Au-Pt alloys by x-ray absorption near edge spectroscopy (XANES). Two kinds of Au-Pt alloy samples were prepared by arc melting methods and ion-beam-mixing technique. The Pt L2, 3-edge and Au L2, 3-edge X-ray absorption spectra (XPS) were measured with the electron yield mode detector at the 3C1 beam line of the Pohang Light Source (PLS). It was found that there was a substantial decrease in the area of the Pt L2, 3 white lines compared with that of pure Pt. The observed decrease in white line area was attributed to an increase in the number of pure Pt. The observed decrease in white line area was attributed to an increase in the number of 5d-electrons at the Pt site upon alloy formation. However, the Au L2, 3 edge spectra for Au-Pt alloys are all similar to that of pure Au. This implies that the 5d hole count of Au is not changed by alloy formation with Pt.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.44-45
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• 2010

We are currently conducting studies on culturing and biocompatibility assessment of various cells such as neural stem cells and induced pluripotent stem cells(IPS cells) on carbon nanotube (CNT), on nerve regeneration electrodes, and on silicon wafers with a focus on developing nerve integrated CNT based bio devices for interfacing with living organisms, in order to develop brain-machine interfaces (BMI). In addition, we are carried out the chemical modification of carbon nanotube (mainly SWCNTs)-based bio-nanosensors by the plasma ion irradiation (plasma activation) method, and provide a characteristic evaluation of a bio-nanosensor using bovine serum albumin (BSA)/anti-BSA binding and oligonucleotide hybridization. On the other hand, the researches in the case of "novel plasma" have been widely conducted in the fields of chemistry, solid physics, and nanomaterial science. From the above-mentioned background, we are conducting basic experiments on direct irradiation of body tissues and cells using a micro-spot atmospheric pressure plasma source. The device is a coaxial structure having a tungsten wire installed inside a glass capillary, and a grounded ring electrode wrapped on the outside. The conditions of plasma generation are as follows: applied voltage: 5-9 kV, frequency: 1-3 kHz, helium (He) gas flow: 1-1.5 L/min, and plasma irradiation time: 1-300 sec. The experiment was conducted by preparing a culture medium containing mouse fibroblasts (NIH3T3) on a culture dish. A culture dish irradiated with plasma was introduced into a $CO_2$-incubator. The small animals used in the experiment involving plasma irradiation into living tissue were rat, rabbit, and pick and are deeply anesthetized with the gas anesthesia. According to the dependency of cell numbers against the plasma irradiation time, when only He gas was flowed, the growth of cells was inhibited as the floatation of cells caused by gas agitation inside the culture was promoted. On the other hand, there was no floatation of cells and healthy growth was observed when plasma was irradiated. Furthermore, in an experiment testing the effects of plasma irradiation on rats that were artificially given burn wounds, no evidence of electric shock injuries was found in the irradiated areas. In fact, the observed evidence of healing and improvements of the burn wounds suggested the presence of healing effects due to the growth factors in the tissues. Therefore, it appears that the interaction due to ion/radicalcollisions causes a substantial effect on the proliferation of growth factors such as epidermal growth factor (EGF), nerve growth factor (NGF), and transforming growth factor (TGF) that are present in the cells.

• Mass Spectrometry Letters
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• 제5권2호
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• pp.42-48
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• 2014

A specific and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method (LC-ESI-MS/MS) was developed and validated for the simultaneous quantification of porphyrins (coproporphyrin, pentacarboxylporphyrin, hexacarboxylporphyrin, heptacarboxylporphyrin, and uroporphyrin) in human plasma and urine. Acidified plasma samples and urine samples were prepared by using liquid-liquid extraction using ethyl acetate and protein precipitation with acetonitrile, respectively. The separation was achieved onto a Synergi Fusion RP column ($150mm{\times}2.0mm$, $4{\mu}m$) with a gradient elution of mobile phase A (0.1% formic acid in 2 mmol/L ammonium acetate, v/v) and mobile phase B (20% methanol in acetonitrile, v/v) at a flow rate of $450{\mu}L$/min. Porphyrins and the internal standard (IS), coproporphyrin I-$^{15}N_4$, were detected by a tandem mass spectrometer equipped with an electrospray ion source operating in positive ion mode. Multiple reaction monitoring (MRM) transitions of the protonated precursor ions and the related product ions were optimized to increase selectivity and sensitivity. The proposed method was validated by assessing selectivity, linearity, limit of quantification (LOQ), precision, accuracy, recovery, and stability. The calibration curves were obtained in the range of 0.1-100 nmol/L and the LOQs were estimated as 0.1 nmol/L for all porphyrins. Results obtained from the validation study of porphyrins showed good accuracy, precision, recovery, and stability. Finally, the proposed method was successfully applied to clinical studies on the autism spectrum disorder (ASD) diagnosis of 203 Korean children.

• 한국환경농학회지
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• 제5권1호
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• pp.11-23
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• 1986

전주시(全州市) 공단폐수(工團廢水) 및 도시하수(都市下水)의 영향(影響)을 받는 지역(地域)의 토양(土壤)과 수도(水稻)를 대상(對象)으로 Cd, Cu, Pb, 및 Zn등 중김속함량(重金屬含量)을 조사분석(調査分析)한 결과(結果)를 요약(要約)하면 다음과 같다. 1) 토양중(土壤中)의 중김속함량(重金屬含量)은 표토(表土)와 심토(心土)의 차(差)가 거의 없었다. 2) 토양중(土壤中)의 Cd, Cu, Pb, 및 Zn의 전함량(全含量)은 오염원(汚染源)으로부터 거리(距離)가 멀어질수록 부(負)의 상관(相關)을 나타냈다. 3) 표토중(表土中) Cd, Pb, Zn 함량(含量)과 0.1N-HCL 및 $N-CH_3COONH_4$에 의한 용출량간(溶出量間)에 정(正)의 상관(相關)을 나타냈다. 4) 토양중(土壤中) 점토(粘土), 유기물함량(有機物含量) 및 양(陽) ion치환용량(置換容量)과 중김속함량간(重金屬含量間)에는 정(正)의 유의성(有意性) 있는 상관(相關)을 나타냈다. 5) 공단폐수(工團廢水) 및 도시하수(都市下水)에 의해서 오염(汚染)된 답토양(畓土壤)에서 생산(生産)된 현미중(玄米中) 중김속함량(重金屬含量)은 Cd은 $0.15{\sim}0.91$ Cu은 $1.13{\sim}5.68$, Pb은 $0.22{\sim}7.16$, Zn.은 $11.74{\sim}38.66ppm$이었다. 6) 현미중(玄米中) 중김속(重金屬)의 함량(含量)은 오염원(汚染源)으로부터 멀어질수록 감소(減少)하는 부(負)의 상관(相關)을 나타냈다. 7) 지상부(地上部) 수도(水稻)의 경엽중(莖葉中) Cd, Cu, 및 Zn의 함량(含量)은 현미중(玄米中) 이들의 함량(含量)과 유의성(有意性) 있는 정(正)의 상관(相關)을 나타냈다.

• 한국광물학회:학술대회논문집
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• 한국광물학회.한국암석학회 2003년도 공동학술발표회 논문집
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• pp.54-54
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• 2003

The metasedimentary rocks together with various granitoids are the main constituents in Taebaeksan gneiss complex, northern Yeongnam Massif. Chemical compositions of sedimentary rocks may reflect the nature of the provenance and could be crucial for understanding the evolution of early continental crust. Previous workers have suggested that the provenance and tectonic studies based on the geochemistry of sediments are applicable to the Precambrian samples. In this study we analyzed the major, trace and REE elements of metasedimentary rocks to understand their provenance and tectonic setting during sedimentation. The overall geochemical characteristics of metasedimentary rocks are similar to those of average shale of the post-Archean. Major element chemistry indicates mature and sorted nature of the sediments. The degree of weathering in the source rocks the is not uniform, as inferred from a large scatter in chemical indices of weathering (CIW). The immobile trace elements such as Th, Sc, and REE can be used to discriminate various sedimentary processes. The Th/sc ratios (0.9 - 4.4) are larger than those of the upper crust and average shale, suggesting that the felsic source predominates. The contents of Ni and Cr and the variations in the ratio of compatible to incompatible elements are similar to the average post-Archean shale. Uniform chondrite-normalized REE pattern with the LREE enrichment (LaN/SmN = 4.9 ${\pm}$ 0.4) and slight negative Eu anomalies (Eu/Eu$\^$*/ = 0.7 ${\pm}$ 0.1) also support this observation. The presence of negative Eu anomaly indicates that intracrustal igneous processes involving plagioclase separation have affected the provenance rocks. The LREE enrichment implies the major role of felsic rocks in source rocks. The eNd (1.9 Ga) values of metasediment rocks vary from 9.4 to 6.7, corresponding to TDM of 2.9 - 2.7 Ga. On the other hand, the 147Sm/144Nd ratios are 0.1079 - 0.1101, corresponding to typical tettigenous sediments. The geochemical features of metasedimentary rocks such as high abundances of large ion lithophile elements, high ratios of Th/Sc and La/Sm, commonly high Th/U ratios, negative Eu anomalies, and negative eNd, suggest a provenance consisting virtually entirely of recycled upper continental crust in passive margin environment. Tectonic discrimination diagrams based upon major element compositions also support this suggestion. In conjunction with igneous activity and metamorphism in the convergent margin setting at 1.8 - 1. 9 Ga, the transition from passive margin to active margin characterize the Paleoproterozoic crustal evolution in northern Yeongnam Massif.

• 한국토양비료학회지
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• 제18권4호
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• pp.336-347
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• 1985

장항제련소(長項製鍊所)의 배연(排煙)에 영향(影響)을 받는 지역(地域)의 토양(土壤)과 수도(水稻)를 대상(對象)으로 Cd, Cu, Pb 및 Zn등 중금속함량(重金屬含量)을 조사분석(調査分析)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 제연소(製鍊所)의 배기(排氣)에 의(依)한 오염(汚染)은 동(東)쪽 방향(方向)에서 가장 심(甚)하였고 Pb의 천연부존량(天然賦存量)을 기준(基準)으로 하였을 때 오염거리(汚染距離)는 5km이었으며 표토(表土)에 많이 축적(蓄積)되고 있었다. 2. 토양중(土壤中) 중금속전함량(重金屬全含量)에 대(對)한 0.1N-HCl 및 $N-NH_4Ac$에 의한 용출율(溶出率)은 표토(表土)에서 고도(高度)의 유의성(有意性)있는 상관(相關)을 나타냈다. 3. 토양중(土壤中) 유기물함량(有機物含量) 및 양(陽)ion치환용량(置換容量)과 중금속전함량간(重金屬全含量間)에는 유의성(有意性)있는 상관(相關)을 나타냈다. 4. 제연소주변(製鍊所周邊) 토양(土壤)에서 생산(生産)된 현미중(玄米中)의 중금속함량(重金屬含量)은 Cd가 0.23~1.33, Cu은 2.39~6.25, Pb은 0.95~8.32, Zn은 14.60~27.31ppm이었다. 5. 지상부(地上部) 식물체중(植物體中)의 Cd, Cu 및 Zn의 함량(含量)은 현미중(玄米中) 이들의 함량(含量)과 유의성(有意性) 있는 정(正)의 상관(相關)을 나타내었다. 6. 현미중(玄米中) Cd, Cu, Pb 및 Zn의 함량(含量)은 오염원(汚染源)으로부터 멀리 떨어질수록 감소(減少)하였다.

• 생명과학회지
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• 제17권10호
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• pp.1321-1329
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• 2007

사슴뿔은 동물세계에서 가장 빨리 성장하는 조직이다. 따라서 성장중인 사슴뿔은 뼈 성장을 촉진하는 인자가 풍부하게 포함된 것으로 생각된다. 이들 성장인자들 중 IGF-1은 뼈를 자라게 하는 조골세포의 대사에 중요한 역할을 한다고 알려져 있어 이를 정제하고자 하였다. IGF-1의 정제는 상대라고 불리는 신선한 사슴뿔을 유안침전, DEAE-Sepharose CL-6B 이온교환수지, CM-Sepharose CL-6B 양이온교환수지, Sephadex G-50의 순차적인 방법으로 할 수 있었다. 각 과정마다 IGF-1의 거동을 HPLC, SDS-PAGE, Dot blot, 그리고 western blot으로 분석하였다. IGF-1의 정량은 ELISA기술로 재조합 인간 IGF-1을 이용하여 계산되었으며, 최종 분별 액은 두 개의 단백질을 보였으나, Western-blot에서 작은 분자량인 12 kDa으로 최종 판명할 수 있었다. 정제된 단백질은 HPLC에서 retention 시간 8분만에 검출되었으며, 총 농도는 2910 ng/ml 이고 중량은 0.291 g 이었다.

• 방사성폐기물학회지
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• 제3권4호
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• pp.309-317
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• 2005

방사성 폐기물 핵종 재고량 평가에 필요한 핵종분석을 위하여 다양한 매질의 방사성 폐기물 시료로부터 $^{99}Tc,\;^{94}Ng,\;^{55}Fe,\;^{90}Sr$ 및 $^{59/63}Ni$의 분리에 관한 연구가 수행되고 있다. Ni은 음이온교환 수지와 Sr-Spec 추출 크로마토그래피 수지로 Re($^{99}Tc$의 대용물), Nb, Fe 및 Sr을 차례로 분리하는 과정에서 Ca, Mg, Al, Cr, Ti, Mn, Ce, Na, K 및 Cu와 함께 회수되었다. 본 연구에서는 Ni의 선택적 분리기술을 확립하기 위하여 Ni-Spec 추출 크로마토그래피 및 양이온교환수지법으로 이들의 분리거동을 비교하였다. 또한 Ni의 정제와 기체비례계수법으로 방사능을 측정하기에 적합한 계측시료 준비를 위하여 ammonium $citrate/ethanol-H_2O$ 및 tartaric $acid/acetone-H_2O$에서 dimethylglyoxime(DMG)에 의한 Ni의 침전거동을 조사하였다 원자력발전소로부터 채취한 폐이온교환수지 시료 용해용액의 화학조성을 모사하여 만든 모의 폐이온교환수지 용액을 사용하여 Re, Nb, Fe 및 Sr 분리과정을 거쳐 최종적으로 분리한 Ni의 회수율은 $92.1\%\;(RSD:\;0.9\%)$이었다. 또한 tartaric $acid/acetone-H_2O$에서 DMG에 의한 Ni의 회수율은 $85.6\%\;(RSD:\;1.9\%)$이었다.

• 생명과학회지
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• 제18권1호
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• pp.103-108
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• 2008

Agar로부터 oligosaccharides를 제조하기 위하여 효소(agarase)를 이용한 분해법이 시도되면서 agarase의 균주의 분리 및 유전자에 대한 많은 연구가 수행되고 있다. 본 연구에서는 해양으로부터 agarase를 생성하는 균주를 분리 동정하고 균주의 특성을 조사하였다. 분리된 균주는 VITEK 2 compact version 분석 결과 Sphingomonas paucimobilis AS-1로 동정되었다. 정제된 효소의 최적 활성 조건 및 agar 분해산물의 항산화활성을 조사하였다. 분리된 균주의 최적배양조건은 marine broth 2216에서 온도 $27^{\circ}C$, pH 7일 때 가장 균주의 생육이 높았다. Agarase 효소는 salt침전, ion exchange와 gel filtration chromatography에 의해 114.4 units/mg으로 104배 정제되었다. 정제된 agarase의 SDS-PACE 결과 분자량이 약 80 kDa의 band를 얻었다. 최적 효소활성은 온도 $40^{\circ}C$, pH 7일 때 나타났다. Agar 첨가한 배지에 agar 분해균을 접종한 후 분해산물의 시간에 따른 항산화활성은 12시간 배양 후 72%의 가장 높은 전자소거능(EDA)을 나타내었다. Agar 분해산물은 식중독균의 생육은 저해하는 것으로 나타났으며 젖산균의 생육은 약간 촉진하는 경향을 나타냈다.