• Proceedings of the Korean Magnestics Society Conference
• /
• 2002.12a
• /
• pp.158-159
• /
• 2002

스핀 밸브에서는 NiFe, CoFe, Cu등 주요 금속들이 면심입방체(111)로 배향이 용이하지만, 자기 터널 접합 소자에서는 $Al_2$O$_3$ 장벽층이 비정질로서 상부 강자성 전극이 충분히 (111) 배향을 할 수 없기 때문에 top bias 방식의 사용이 거의 불가능하며, bottom bias의 경우에도 교환 바이어스의 크기는 상대적으로 작다[1]. 이를 극복하기 위해 인공 초격자를 이용한 인공 반강자성층(synthetic antiferromagnet - SAF)을 이용하여 높은 교환 바이어스 효과를 구현하고자 하였다. (중략)

• Proceedings of the Korean Magnestics Society Conference
• /
• 2002.12a
• /
• pp.240-241
• /
• 2002

Tetragonal 구조를 갖는 정량적 Nd$_2$/Fe$_{14}$B (~Nd$_{12}$Fe$_{82}$B$_{6}$) 화합물에서의 Nd 양보다 적은 양의 Nd를 함유하는 Nd-Fe-B 합금에서는, 일반적으로 입자크기가 큰 연자성 $\alpha$-Fe가 과다하게 존재하면서 외부에서 가해주는 자장에 대해 강자성 Nd$_2$/Fe$_{14}$B와 별개의 자기적 거동을 보여주기 때문에, 보자력이 아주 적어 실용성이 없다. 그러나 이러한 합금을 급랭응고하여 미세 결정화하거나, 비정질화한 후 적절히 열처리 해주면 a-Fe와 Nd$_2$/Fe$_{14}$B 입자가 나노화하면서 이들 사이에 상호교환작용이 일어나 등방성 상태에서도 M$_{s}$ /2 보다 큰 잔류자화와 함께 적절한 크기의 보자력도 얻을 수 있다. (중략중략

• Journal of Powder Materials
• /
• v.10 no.4
• /
• pp.288-293
• /
• 2003

Mechanical alloying (MA) by high energy ball mill of Pure chromium Powders was carried out under the nitrogen gas atmosphere. Cr-N amorphous alloy powders have been produced through the solid-gas reaction subjected to MA. The atomic structure during amorphization process was observed by X-ray and neutron diffractions. An advantage of the neutron diffraction technique allows us to observe the local atomic structure surrounding a nitrogen atom. The coordination number of metal atoms around a N atom turns out to be 5.5 atoms. This implies that a nitrogen atom is located at both of centers of the tetrahedron and octahedron formed by metal atoms to stabilize an amorphous Cr-N structure. Also, we have revealed that a Cr-N amorphous alloy may produced from a mixture of pure Cr and Cr nitrides powders by solid-solid reaction during mechanical alloying.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.303-303
• /
• 2010

비정질 실리콘 박막 태양전지의 수광부인 i-layer는 비정질의 특성 상 많은 defect을 함유하고 있다. 이러한 defect들은 빛에 의하여 생성된 전자정공 재결합에 있어서 주도적으로 작용하게 된다. $H_2$는 이러한 defect들의 생성을 줄여주어 박막의 특성을 향상시켜주는 것으로 알려져 있다. 본 논문에서는 비정질 박막 태양전지의 수광부로 사용되어지는 i-layer의 $H_2$ gas flow rate의 변화에 따른 태양전지의 특성을 simulation해 보았다. $H_2$는 1:0에 1:5까지 변화시켰고 그에 따른 태양전지의 QE, LIV, DIV 곡선을 통하여 특성을 알아보았다. 또한 추가적으로 i-layer의 두께에 따른 효율의 변화도 simulation해 보았다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.9-9
• /
• 2016

많은 연구들에서 단변량 수문 변량들에 대한 불확실성 분석이 이루어지고 있지만, 다변량에 대한 불확실성에 관한 연구는 아직까지 정확하게 이루어지고 있지 않은 실정이다. 이에 본 연구에서는 갈수기(12월~4월)의 강수, 온도와 남방진동(El Ni?o-Southern Oscillation, ENSO)과 같은 수문기상학적 변량들 사이의 시간에 따른 변동 구조를 조사하고, 식별된 패턴을 이용한 강우와 온도의 예측 향상 가능성을 살펴보았다. 수문기상학적 변수간의 시변성 구조를 이해하기 위해서 각각의 단변량 매개변수와 시간에 따라 변화하는 Copula 매개변수를 동시에 추정할 수 있는 Copula 함수 기반의 새로운 다변량 비정상성 모델을 개발하고자 한다. 강우와 온도의 비정상정 단변량 분포를 생성하기 위해 ENSO 지표 또는 시계열 예측인자와 함께 시변성 모델을 적용할 수 있다. 최종적으로, 확인된 시간 변동적인 구조와 연관된 종관 패턴을 나타내고 논의하고자 한다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
• /
• 2003.05a
• /
• pp.1-3
• /
• 2003

평판형 안테나를 채택한 TCP (Transformer Coupled Plasma) 형태의 CVD 장비를 이용하여 비정질의 실리콘 박막을 증착 하였다. 비정질 실리콘 박막은 태양전지 및 TFT-LCD 등의 디스플레이 제품 등에 다양하게 적용되고 있는데, 일반적으로 CCP(Capacitor Coupled Plasma) 형태의 CVD 장비에서 증착되어 왔다. TCP-CVD 장비는 CCP-CVD에 비해 플라즈마 내의 높은 이온밀도 및 저압, 저온에서 공정이 가능할 뿐만 아니라, 기판 바이어스 전압을 독립적으로 조절할 수 있어 이은에 의한 증착막의 결함을 낮출 수 있는 장점이 있다. 본 발표에서는 자체 기술로 제작된 TCP-CVD의 소개와 증착된 비정질 실리콘 박막의 특성평가를 위한 라만 분석 및 dark conductivity 데이타를 다루었다. 또한 비정질 실리콘 박막의 반도체 소자의 응용성을 보기 위하여 3족 및 5족의 불순물을 도핑하여 전기전도도의 변화를 측정하였다.

• The Journal of Korean Society for Radiation Therapy
• /
• v.25 no.1
• /
• pp.25-31
• /
• 2013

Purpose: The aim of this study is to evaluate the dosimetric properties of robust planning strategy for plain intensity-modulated proton therapy (IMPT) taking into account of the uncertainties of effective proton range and set up error as compared to photon intensity-modulated radiation therapy (photon-IMRT) in prostate cancer treatment. Materials and Methods: The photon-IMRT (7 beams, step & shoot), plain-IMPT (2, 4, and 7 portals), and robust- IMPT plans, which was recalculated the plain-IMPT based on the uncertainties of range error (${\pm}5%$) and set up error (0.5 cm), were evaluated for five prostate cancer patients prescribed by 70 Gy/35 fractions. To quantitatively evaluate the dose distributions, several parameters such as maximum dose, minimum dose, mean dose, conformity index (CI), and homogeneity index (HI) for PTV as well as dose-volume index of VxGy for OARs were calculated from dose-volume histograms. Results: Robust-IMPT showed superior dose distributios in the PTV and OARs as compared to plain-IMPT and photon-IMRT. Like plain-IMPT, robust-IMPT were resulted in dose fluctuation around OARs, while better homogeneity and conformity in PTVs and lower mean dose in OARs as compared to photon-IMRT. Conclusion: In consideration with the effective range correction and set up movement using robustness in IMPT plan, the dosimetric uncertainties from plain-IMPT could substantially reduce and suggest more effective solutions than photon-IMRT in prostate cancer treatment.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.35 no.3
• /
• pp.32-40
• /
• 2017

The introduction of neo-Confucianism as the ideological foundation of Joseon, and its root Confucianism have become the origin of the life, scholarship and ideology of the Korean people. Additionally, it was considered the best to follow the teachings of the discipline's advocates including Confucius (孔子), Mencius (孟子), Zisi (子思), ZhuXi (朱子). Among these teachers, ZhuXi was the one who overtly presented the way of self-discipline, of which goal lies in attaining the character by the manifestation of vitality (氣 ki) and rationality (理 i) and contemplating on them. As he regarded natural places with mountains and waters as stages and tools for practicing toward the enlightenment, Confucian scholars in Joseon also followed his example in the spirit of honoring and studying ZhuXi (尊朱子, 學朱子), which became the basic thoughts and practical philosophy among them. Ryu, Junggyo, the neo-Confucian dogmatist, was no exception to applaud the nature, as he designated and ruled Okgye Gugok. On the basis of these backgrounds, this study aims to estimate the geographic places of Okgye Gugok, which was set by Ryu, Junggyo, a Confucian scholar in late-Joseon period, by collecting and analyzing the basic data, starting from Gareung-gun Okgye Sansugi(嘉陵郡玉溪山水記) which is the primary text authored by Seongjae Ryu, Junggyo. The literature study is followed by ten field trips to the estimated locations of Okgye Gugok, and verification of the estimations by three locals who were born and raised in Okgye Gugok. Coordinates and photographs were obtained as spatial data for each location of nine Gok(曲) estimated through this study. They will serve as a primary and critical data for story-telling and tourism resource in Okgye Gugok. The significance of this study is that it provides the primary data for designating the locations of Gok(曲) in Okgyeo Gugok.

• Journal of the Korean Electrochemical Society
• /
• v.9 no.4
• /
• pp.141-150
• /
• 2006

Nanocrystalline CoW thin/thick film alloys were electodeposited from citrate baths to investigate the influences of metal ion concentration, current density and solution pH on chemical composition, current efficiency, residual stress, surface morphology, and microstructure of the film. Deposit W (tungsten) content in CoW thin/thick film increased with increasing W ion concentration, current density, and solution pH in the plating bath. It was observed that residual stress in CoW thin/thick film decreased with increasing W ion concentration and solution pH. CoW thin film exhibited mixed phases of hop Co [(100) and (002)] and hcp $Co_3W$ [(002) and (201)] at W ion concentration with 0.02 to 0.08 M. The microstructure of CoW thin film at W ion concentration of 0.1 to 0.2 M was close to amorphous phase. The dominant phases were found to be hop Co (002) and hop $Co_3W$ [(200), (002) and (201)] at the current densities of 5, 10, 25, and $100mA{\cdot}cm^{-2}$ CoW thin film at the current densities of 50 and $75mA{\cdot}cm^{-2}$ was close to amorphous phase. At solution pH 8.7, CoW thin film exhibited hcp Co (002) and hop $Co_3W$ [(200), (002) and (201)]. Below solution pH 8.7, CoW thin film exhibited amorphous microstructure. The optimum electrodeposition conditions for CoW thin/thick film were found to be W ion concentration of 0.08 M, current density of $10mA{\cdot}cm^{-2}$, and solution pH 8.7.

• The Journal of Korean Society for Radiation Therapy
• /
• v.29 no.1
• /
• pp.19-26
• /
• 2017

Purpose: The application of density override is very important to minimize dose calculation errors by fiducial markers of metal material in proton treatment plan. However, density override with actual material of the fiducial marker could make problem such as inaccurate target contouring and compensator fabrication. Therefore, we perform density override with surrounding material instead of actual material and we intend to evaluate the usefulness of density override with surrounding material of the fiducial marker by analyzing the dose distribution according to the position, material of the fiducial marker and number of beams. Materials and Method: We supposed that the fiducial marker of gold, steel, titanium is located in 1.5, 2.5, 4.0, 6.0 cm from the proton beam's end of range using water phantom. Treatment plans were created by applying density override with the surrounding material and actual material of the fiducial marker. Also, a liver cancer patient who received proton therapy was selected. We located the fiducial marker of gold, steel, titanium in 0, 1.5, 3.5 cm from the proton beam's end of range and the treatment plans were created by same method with water phantom. Homogeneity Index(HI), Conformity Index(CI) and maximum dose of Organ At Risk(OAR) in Planning Target Volume(PTV) as the evaluation index were compared according to the material, position of the fiducial marker and number of beam. Results: The HI value was more decreased when density override with surrounding material of the fiducial marker was performed comparing with density override with actual material. Especially the HI value was increased when the fiducial marker was located farther from the proton beam's end of the range for a single beam and the fiducial marker's position was closer to isocenter for two or more beams. The CI value was close to 1 and OAR maximum dose was greatly reduced when density override with surrounding material of the fiducial marker was performed comparing with density override with actual material. Conclusion: Density override with surrounding material can be expected to achieve more precise proton therapy than density override with actual material of the fiducial marker and could increase the dose uniformity and target coverage and reduce the dose to surrounding normal tissues for the small fiducial markers used in clinical practice. Most of all, it is desirable to plan the treatment by avoiding the fiducial marker of metal material as much as possible. However, if the fiducial marker have on the beam path, density override of the surrounding material can be expected to achieve more precise proton therapy.