• Macromolecular Research
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• 제16권7호
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• pp.575-585
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• 2008

There are two beamlines (BLs), 4C1 and 4C2, at the Pohang Accelerator Laboratory that are dedicated to small angle X-ray scattering (SAXS). The 4C1 BL was constructed in early 2000 and is open to public users, including both domestic and foreign researchers. In 2003, construction of the second SAXS BL, 4C2, was complete and commissioning and user support were started. The 4C2 BL uses the same bending magnet as its light source as the 4C1 BL. The 4C1 BL uses a synthetic double multilayer monochromator, whereas the 4C2 BL uses a Si(111) double crystal monochromator for both small angle and wide angle X-ray scattering. In the 4C2 BL, the collimating mirror is positioned behind the monochromator in order to enhance the beam flux and energy resolution. A toroidal focusing mirror is positioned in front of the monochromator to increase the beam flux and eliminate higher harmonics. The 4C2 BL also contains a digital cooled charge coupled detector, which has a wide dynamic range and good sensitivity to weak scattering, thereby making it suitable for a range of SAXS and wide angle X-ray scattering experiments. The general performance of the 4C2 BL was initially tested using standard samples and further confirmed by the experience of users during three years of operation. In addition, several grazing incidence X-ray scattering measurements were carried out at the 4C2 BL.

• 한국전기전자재료학회논문지
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• 제17권11호
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• pp.1218-1223
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• 2004

Porous silicon materials have been shown to have bright prospects for applications in light emitting, solar cell, as well as light- and chemical-sensing devices. In this report, structures of porous silicon prepared by anodic etching in HF-based solution with various etching times were studied in detail by Atomic Force Microscopy and Small Angle X -ray Scattering technique using the high energy beam line at Pohang Light Source in Korea. The results showed the coexistence of the various pores with nanometer and submicrometer scales. For nanameter size pores, the mixed ones with two different shapes were identified: the larger ones in cylindrical shape and the smaller ones in spherical shape. Volume fractions of the cylindrical and the spherical pores were about equal and remained unchanged at all etching times investigated. On the whole uniform values of the specific surface area and of the size parameters of the pores were observed except for the larger specific surface area for the sample with the short etching time. The results implies that etching process causes the inner surfaces to become smoother while new pores are being generated. In all SAXS data at large Q vectors, Porod slope of -4 was observed, which supports the fact that the pores have smooth surfaces.

• 한국진공학회지
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• 제17권1호
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• pp.1-8
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• 2008

포항가속기연구소 저장링에 설치된 방사광 차단용 진공부품에서 냉각수가 누설되었을 때의 진공도 분포, 압력 변화, 잔류 기체의 변화 등을 측정하여 그 특성을 분석하였다. 냉각수 누설 시에 압력 상승은 국부적으로 나타났으며 잔류 기체의 변화 양상은 누설 위치로부터 잔류기체 분석기까지 거리와 이온펌프 및 전자빔의 On/Off에 따라서 크게 달랐으며 특정 기체의 선택적 상승도 나타났다. 냉각수 누설의 발견은 전압변화 측정으로 가능하였으며 잔류기체 분석기로는 물분자를 직접 측정하기보다는 $CH_4$, CO, NO 등 특성 기체의 증가를 분석함으로 누설 여부를 판단할 수 있었다.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1744-1749
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• 2018

This study investigated the feasibility of synthesizing GNPs using synchrotron radiation X-ray for use as a radiosensitizer in radiotherapy, and examined the morphology of the GNPs. Different concentration ratios of 4-mM gold precursor aqueous solution and 4-mM $NaHCO_3$ were mixed. This gold precursor aqueous solution was continuously irradiated with synchrotron radiation in the 4B X-ray microdiffraction beamline of Pohang Light Source (PLS)-II in Korea. The SEM, EDS, TEM, and XRD spectra of the GNPs synthesized using the synchrotron radiation were investigated. The GNPs synthesized using the synchrotron radiation were nanocrystals predominantly in the (111) direction of the face-centered cubic structure. We found that the shape of the gold nanoparticles was icosahedron at the molar concentrations of 0.25 mM:0.25 mM and 0.5 mM:0.5 mM mixed with 4 mM $HAuCl_4{\cdot}3H_2O$ and 4 mM $NaHCO_3$ solutions.

• 한국군사과학기술학회지
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• 제20권1호
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• pp.72-80
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• 2017

Gamma-ray has some advantages as a weapon: it has the ability to transmutate matter, high penetrability through materials, and it is very harmful to living things. So it is worth to study the features of gamma-ray weapon in order to utilize it. Such abilities were simulated on the basis of Monte Carlo simulation program GEANT4. For the simulation conceptual design of gamma-ray weapon was conducted. High energy electrons, which were necessary for the high energy gamma-rays, were produced by linear electron accelerator, of which the parameters were derived from the Pohang Light Source(PLS-II). Gamma-rays were get by bremsstrahlung mechanism. The spectra of gamma-rays, that were measured at distances of 500 m, 1000 m, 1500 m and 2000 m, were gained by GEANT4.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.86-86
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• 2016

최근 포항가속기연구소 10A 빔라인에 Scanning Transmission X-ray Microscopy (STXM)가 완성되어 운영 중이다. Soft x-ray imaging 장치로서 기술적으로 Sample scanning 기법이 활용된다. 이는 Zone plate를 통해 집속된 빔이 샘플에 조사되고 검출되는 방식이다. 이러한 Scanning 기법을 활용하고 있는 10A STXM은 기본적으로 흡수분광기법 (x-ray absorption spectroscopy)을 이용하고 있다. 특히, 10A 빔라인 STXM은 최고 20 nm까지 공간분해능이 가능하다는 장점이 있다. 따라서 수십에서 수백 나노미터 크기의 시료들 또는 나노구조에 대한 물리화학적 상태 분석이 쉽게 이루어지고 있다. 주로 시료를 투과하면서 흡수되는 X-선 세기 대비를 맵핑하는 형식의 이미지 데이터와 더불어 X-선의 에너지를 조정함으로써 각 에너지에 해당하는 이미지스택을 결과로 얻게 된다. 이러한 이미지 결과로부터 시료의 나노크기에서 오는 물리화학적 상태를 분석하고 물리에서 바이오까지 다양한 분야의 실험 활용이 가능한 상태다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.291-298
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• 2004

The observations of rapid motion of bubbles under water for approximately 50 ms or less in high-magnetic fields of 10 T have been carried out successfully for the first time. The observation system constructed is composed of a high-speed video camera, a telescope, a cryostat with a split-type superconducting magnet, a light source, a mirror and a transparent sample cell. Using this system, the influence of magnetic field on the path and shape of single bubbles of O$_2$ (paramagnetism) and N$_2$ (diamagnetism) has been examined carefully. Experimental values describing the path are in good agreement with theoretical values calculated on the basis of the magneto-Archimedes effect, despite the effect of magnetism on the bubble. However, no effect of magnetism on the shape of the bubble is observed. In addition, the influence of magnetic field on drag coefficient of the bubble is discussed.

• KSBB Journal
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• 제15권1호
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• pp.84-87
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• 2000

포항 선형 가속기로부터 얻은 ultrasoft X-선이 대장균의 돌연변이 유도와 plasmid DNA 변이에 주는 영향을 알아보았다. 빔을 조사함에 따라 supercoil 형태의 plasmid DNA가 relaxed 형태로 변하고, 그후 선형으로 변해 감을 확인하였다. 빔을 조사한 plasmid DNA를 E. coli에 형질전환하여 $\beta$-galactosidase의 돌연변이 균을 분리하였고, 빔을 직접 조한 E. coli균으로부터도 $\beta$-galactosidase의 돌연변이 균을 얻었다. 변이된 plasmid DNA와 변이 대장균들의 plasmid DNA의 염기 부분을 변화를 확인하였으며 이 빔에 의해 주로 변이가 일어나는 부분이 있음을 알았다.

• 대한기계학회논문집A
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• 제27권6호
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• pp.997-1006
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• 2003

LICA technique evolved as a basic fabrication process fur micro-structure. The present report deals with the basic technological features in the sequence of the LIGA technique such as deep x-ray lithography(DXRL), electroplating, and moulding processes at Pohang Light Source (PLS). We designed 3-D structured master for fabrication of polymeric optical wavegude and manufactured polymeric optical wavegude with the same using hot embossing process. Polymeric optical waveguide could be produced with ${\pm}$ 1 $\mu\textrm{m}$ accuracy and good surface roughness.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1011-1015
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• 2005

Fully digital controlled 20-bit magnet power supplies have been developed and successfully tested for closed orbit correction of PLS(Pohang Light Source). The new digital power supply has used fiber optics for 25kHz switching of IGBT drivers, and implemented DSP, ADC, Interlock, DCCT cards in a compact 3U-sized 19" chassis. Input/Output low-pass filters suppress harmonics of 60Hz line frequency and switching frequency noise effectively. Overall performance of the power supplies have been demonstrated as +/- 2ppm short-term stability(<1 min), and +/- 10ppm long-term stability(<36 hours). All the existing 12-bit 70 power supplies for vertical correction magnets will be replaced with new digital power supplies during 2005 summer shutdown period. In this paper, we will describe the hardware structure and control method of the digital power supply and the experimental results will be shown.