• 대한방사선기술학회지:방사선기술과학
• /
• 제4권1호
• /
• pp.31-36
• /
• 1981

We studied radiation dose in mammography through 34-46 kv range using acryl phantom. The obtained results were as follows: 1. Incident radiation was maximum with high kvp and thin added filtration. 2. Transmitted radiation by acryl phantom and its thickness were in reciprocal relationship. 3. The acryl thickness to produce comparable film density with soft tissue of breast was 6 cm. 4. The X-ray exposure for comparable density radiographs increased mammographic film more than medical x-ray film and the amount of x-ray exposure was directly proportional to the added filtration of x-ray beam. 5. The surface dose of x-ray exposure needed to produce film density of 1.0 for 6cm acryl phantom was 1,084-1,575mR in mammographic film and 476-625 mR in medical x-ray film.

• 한국광학회:학술대회논문집
• /
• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
• /
• pp.134-135
• /
• 1999

• Journal of Astronomy and Space Sciences
• /
• 제24권4호
• /
• pp.309-314
• /
• 2007

오르트 구름을 출발하여 태양계 안쪽으로 들어오는 혜성 가운데 오르트 구름으로 되돌아가지 못하고, 태양에 매우 근접하여 태양에 충돌해 버리거나 강한 중력에 의해 쪼개져 사라지는 혜성을 sungrazing comet이라고 한다. 태양에 가까워지면서 태양열에 의해 혜성의 얼음이 승화되면서 그 존재를 확인하게 되는데, 태양풍의 고전리된 중원소이온과 충돌에 의한 전하교환의 상호 작용에 의해 혜성에서 발생하는 가스량과 X-선 방출량을 기존 모델(Mendis & Flammer 1984, Cravens 1997)을 적용하여 근사 계산한 결과, 혜성핵의 반지름이 1km 정도인 경우 태양으로부터 거리가 태양반경의 3배 이내인 거리에서 GOES 위성의 X-선 망원경으로 탐지가능한 것으로 보인다.

• 한국산림과학회지
• /
• 제80권4호
• /
• pp.351-359
• /
• 1991

Soft X-ray에 의한 연륜밀도해석법(年輪密度解析法)으로 대기오염지역(大氣汚染地域)에서 자란 해송(Pinus thunbergii) 성목(成木)의 연륜(年輪)에 대한 특징(特徵)을 알아본 결과, 연륜폭(年輪幅)과 대기밀도(最大密度), 최대밀도(最大密度)와 최소밀도(最小密度)의 차(差)(이하DD)는 공장이 가동된 이후 오염원(汚染源)의 주변지역에서는 감소하는 경향을 나타내었으며 특히 오염원(汚染源)에서 가장 가까운 지역(地域)에서 가장 뚜렷히 감소하고 있었고 추재율(秋材率)과 최소밀도(最小密度)는 오염(汚染)으로 인한 감소와 증가의 뚜렷한 특징을 나타내지 않았다. 또한 연륜폭(年輪幅) 및 최대밀도(最大密度), DD는 공장가동직후 5년동안보다도 5년이후부터 더욱 감소되고 있었으며 감소율(減少率) 역시 공장가동 5년이후 부터 증가되었고 연륜폭(年輪幅)의 감소율(減少率)이 가장 컸다. 이와같이 본조사를 통하여 본 해송의 연륜폭(年輪幅) 및 최대밀도(最大密度), DD는 오염으로 인한 생장저해(生長沮害)의 지표(指標)로서 이용할 수 있다고 추측되었다.

• 인터넷정보학회논문지
• /
• 제11권1호
• /
• pp.21-26
• /
• 2010

본 논문에서는 LCD TV용 필름의 균일성을 개선하고자, 소프트 엑스레이(soft X-ray)를 이용하여 볼트 연결기법과 컨벌루션(convolution) 함수기반의 영상처리를 결합한다. 필름의 프로파일에서 두께를 측정하는 라인 스캔과정에서 선원 변경 시 오프셋 오류가 발생한다. 이러한 선원의 오프셋 오류를 제거하고자, 인접한 3개 볼트의 영상에 대해 컨벌루션 함수를 적용함으로써 자동으로 두께 측정이 가능하고, 영상분석 성능을 향상한다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.379-391
• /
• 2010

In order to understand the mechanism of cementation of soft soils treated with bacteria, three types of specimens(untreated, normal bacteria concentration treated, and high bacteria concentration treated) were made. Scanning Electron Microscope(SEM), EDX and X-ray diffraction(XRD) analyses were performed on the soft silt and loose sand specimens. Compared with the untreated specimen, a clearer cementation between particles was observed in the high bacteria concentration treated specimen. Based on the scanning electron microscope(SEM) EDX analyses, more calcium carbonate was observed in the specimen treated with high bacteria concentration than other specimens. On the basis of the preliminary results, it appears that microbial cementation can occur in the soft soil. Further study on the cementation of soils using bacteria is necessary to validate this result.

• Current Applied Physics
• /
• 제18권11호
• /
• pp.1185-1189
• /
• 2018

Thickness-dependent magnetic domain structure of ultrathin Co wedge films (0.3 nm-1.0 nm) sandwiched by Pt layers was investigated by scanning transmission x-ray microscopy (STXM) employing X-ray magnetic circular dichroism (XMCD), utilizing elliptically polarized soft x-rays and electromagnetic fields, with a spatial resolution of 50 nm. The magnetic domain images measured at the Co $L_3$ edge showed the evolution of the magnetic domain structures from maze-like form to the bubble-like form as the perpendicular magnetic field was applied. The asymmetric domain expansion of a 500 nm-scale bubble domain was also measured when the in-plane and perpendicular external magnetic field were applied simultaneously.

• Applied Science and Convergence Technology
• /
• 제23권6호
• /
• pp.317-327
• /
• 2014

In order to develop nano-devices with much lower power consumption for beyond-CMOS applications, the fundamental understanding and precise control of the electronic properties of ultrathin transition metal oxide (TMO) films are strongly required. The metal-insulator transition (MIT) is not only an important issue in solid state physics, but also a useful phenomenon for device applications like switching or memory devices. For potential use in such application, the electronic structures of MIT, observed for TMO nano-structures, have been investigated using a synchrotron radiation angle-resolved photoelectron spectroscopy system combined with a laser molecular beam epitaxy chamber and a scanning photoelectron microscopy system with 70 nm spatial resolution. In this review article, electronic structures revealed by soft X-ray nano-spectroscopy are presented for i) polarity-dependent MIT and thickness-dependent MIT of TMO ultrathin films of $LaAlO_3/SrTiO_3$ and $SrVO_3/SrTiO_3$, respectively, and ii) electric field-induced MIT of TMO nano-structures showing resistance switching behaviors due to interfacial redox reactions and/or filamentary path formation. These electronic structures have been successfully correlated with the electrical properties of nano-structured films and nano-devices.

• Current Applied Physics
• /
• 제18권11호
• /
• pp.1205-1211
• /
• 2018

The frustrated magnet has been regarded as a system that could be a promising host material for the quantum spin liquid (QSL). However, it is difficult to determine the spin configuration and the corresponding mechanism in this system, because of its geometrical frustration (i.e., crystal structure and symmetry). Herein, we systematically investigate one of the geometrically frustrated magnets, the $TbB_4$ compound. Using resonant soft x-ray scattering (RSXS), we explored its spin configuration, as well as Tb's quadrupole. Comprehensive evaluations of the temperature and photon energy/polarization dependences of the RSXS signals reveal the mechanism of spin reorientation upon cooling down, which is the sophisticated interplay between the Tb spin and the crystal symmetry rather than its orbit (quadrupole). Our results and their implications would further shed a light on the search for possible realization of QSL.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.377-377
• /
• 2010

FINEMET type nanocrystalline materials synthesized by controlled crystallization of amorphous ribbons[1] exhibit excellent soft magnetic properties making them attractive for technological applications. Present work reports the electronic structure studies of Co-substituted FINEMET to get information on the effect of successive Co substitution on local environment around Fe and Co atom by using near edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) measurements. NEXAFS spectroscopy and XMCD measurements have been carried out at Fe $L_{3,2}$ and Co $L_{3,2}$-edges to investigate the chemical states and electronic structure of FINEMET [$(Fe_{100-x}Co_x)_{78}Si_9Nb_3Cu_1Ba$](0$L_{3,2}$-edge reveal that Fe is in 2+ state and in tetrahedral symmetry with other elements. The magnetic properties exhibiting soft magnetic behavior[2] are discussed on the basis of the electronic structure studied through XMCD.