1,129 research outputs found
IMPACT OF HEALTH INFORMATION ON DEMAND FOR FATS AND OILS IN JAPAN: COINTEGRATION AND A COMPLETE DEMAND SYSTEM APPROACH
No full textThis paper deals with the structural change for fats and oils in Japan focusing on the possible influence of health information. The newly developed fat and cholesterol information index appears to reflect the changing health information on fat and cholesterol much better than the ad-hoc cumulative index.Food Consumption/Nutrition/Food Safety,
의 열적 안정성 및 전기 화학적 특성에 대한 고찰
No full text학위논문(박사) - 한국과학기술원 : 재료공학과, 2002.8, [ xiii, 143 p. ]The lithium nickelate is the possible candidate, which can replace the commercially available lithium cobaltate, and have a greater discharging capacity with the problems like the lithium deficiency during synthesis and thermal instability at charged state. These problems hinder the commercialization of lithium nickelate as the positive electrode for the lithium ion battery. To solve these matters, many researches have been done in the fields like oxygen flowing environment during the synthesis and the substitution in lithium or nickel site. However, more importantly, the strong nickel reducibility, which is originated from the electron affinity of nickel, is the key role in both perspectives. During the synthesis of lithium nickelate, the lithium deficiency is induced by the nickel reduction, and for the charging stage, the reduction of nickel lead to the thermal decomposition to rock salt structure at above ambient temperature. Therefore, in this study, to limit the nickel reducibility, there are two ways of approaches. The one is involving with the precursors. Generally, the oxidation state of the available nickel precursor for the many different synthesis routes is . There’s no commercially available precursor because of instability and hard to be synthesized. If the lithium nickelate is prepared by using precursor with heavy oxidation scheme, the nickel reducibility to state cannot be sustained. Then, the more stable precursor is synthesized in this study, and used in several synthesis routes. For the proper precursor, β- NiOOH is chosen, because that the structure is same as lithium nickelate, , and great tendency to interchange ion between hydrogen and alkali earth metals, i.e. lithium. The β-NiOOH is prepared from , which is one of the precursor, at 125℃ for 24 hours with 300ml/min of flowing oxygen. The pre-oxidized powder is determined as desirable phase, NiOOH...한국과학기술원 : 재료공학과
Fabrication and performance of a soft X-ray microscope using a high-order harmonic X-ray source
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2009.2, [ viii, 88 p. ]광학현미경은 생물학적 샘플 및 미세 구조를 분석하는데 매우 유용한 도구로 자리잡았으며, 현미경의 기술이 발전함에 따라 광학현미경의 분해능은 회절한계에 도달하였다. 현미경의 분해능은 광원의 파장에 의해 제한되므로, 더 미세한 구조를 확인하기 위해서는 극자외선 및 엑스선 영역의 광원이 필요하게 되었다. 전자현미경의 개발은 원자 수준의 분해능을 얻을 수 있게 되었으며, 생물학 및 재료과학 등의 연구분야에 많은 기여를 하였다. 하지만 전자의 특성으로 인해 전자현미경은 샘플의 표면 및 매우 얇은 두께의 샘플에 국한되었다. 엑스선은 높은 투과성을 가지고 있어 샘플을 손상시키지 않고 관측할 수 있다는 장점으로 연구자들에게 매력적인 것이었다. 방사광 및 구역판이 개발됨에 따라 엑스선 현미경이 제작되어 생물학 및 재료과학 등 여러 분야의 연구에 널리 사용되고 있으며, 현재 대부분의 엑스선 현미경은 방사광을 광원으로 제작되고 있다. 하지만 방사광은 큰 시설 규모로 인해 연구자들의 낮은 접근가능성으로 실험실 수준의 엑스선 광원 개발에 많은 연구가 이루어졌으며, 그 결과 엑스선 레이저, 레이저-플라즈마 엑스선 광원 및 고차조화파 등의 엑스선 광원이 개발되었다. 이렇게 개발된 광원으로 제작된 엑스선 현미경은 방사광을 이용한 현미경과 유사한 성과를 보여주고 있다. 고차조화파는 고출력 펨토초 레이저와 기체원자의 상호작용에 의해 발생하는 것으로, 간단한 발생장치, 높은 결맞음성, 낮은 발산각 등의 장점을 가지고 있으며, 극자외선부터 연엑스선 영역의 스펙트럼을 가지고 있다. 따라서 고차조화파는 나노미터의 분해능을 가진 현미경, 간섭측정, 홀로그래피 등에 매우 유용하게 사용될 수 있다. 또한 펨토초 또는 아토초 영역의 펄스폭을 가져 원자 및 분자의 초고속 현상을 연구하는데 큰 기여를 할 수 있다.
본 연구는 고차조화파를 광원으로 연엑스선 투과 현미경을 제작하여 성능 평가에 관한 것이다. 고출력 펨토초 레이저를 네온기체에 집속하여 발생한 고차조화파 중에서 Mo/Si 다중박막거울을 사용하여 61차(13 nm) 조화파를 선택하여 광원으로 사용하였으며, 집광효율을 향상시키기 위해 집광기로 Mo/Si 다중박막 구면거울을 사용하였으며, 결상광학계로는 프레넬 구역판을 사용하였다. 제작한 현미경으로 미세구조를 관측한 결과, 대략 130 nm의 분해능을 얻었다. 본 연구는 고차조화파가 나노미터 수준의 분해능을 가진 현미경 및 간섭계에 응용될 수 있음을 보였으며, 극자외선 리토그래피에 사용되는 광학소자의 표면 검사 등 여러 분야에 활용될 수 있다.한국과학기술원 : 물리학과
라미네이션 공정으로 제조된 멀티칩모듈 기판의 열적-기계적 응력 해석
No full text학위논문(박사) - 한국과학기술원 : 재료공학과, 2000.2, [ vii, 121 p. ]The thermo-mechanical behavior of multilayer structures is a subject of perennial interest. A vast literature exists on this topic. While some useful closed-form expressions have been developed under certain sets of assumptions and using different approximations, most of them are rarely supported by experimental investigation. Among various multi-layer structures, this dissertation provided a thorough investigation on the lamination-based thick-film multilayer substrates, or the multichip module (MCM) substrates. As an increasing number of layers were laminated, the thermo-mechanical behavior was measured layer-by-layer using a laser profilometry during thermal cycling.
One of the key thermo-mechanical issues during the MCM-D substrate fabrication is substrate bowing, and another important con-cern is the thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). The thermal stress causes mechanical failure of films, such as adhesion reduction, contact peel-off, and variations in electrical properties, and the substrate bowing makes the fabrication process difficult, for example, vacuum mounting for handling and substrate sawing after fabrication. It also causes a stress concentration problem in internal structures such as via, and flip chip bump failure due to repeated thermal loading. Consequently, precise descriptions of the thermo-mechanical behavior of the thick-film multilayer substrates were necessarily required to realize high-density, high-yield, high-reliability, and low-cost MCM-D substrates.
In Chapter 1, while the majority of reports in the literature have focused on single-layer analysis using the well-known Stoney````s formula, this chapter examined the extended usage of Stoney````s formula for the multilayer analysis. A simple model, the multilayer-modified Stoney````s formula, which predicts a stress contribution from each individual layer was proposed and verified through the numerical analysis and experiments using...한국과학기술원 : 재료공학과
Characteristics of double pass liquid amplifier and :glass laser oscillator with a stimulated brillouin scattering mirror
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 1998.2, [ iv, 134 p. ]한국과학기술원 : 물리학과
Third-harmonic generation by direct and cascaded processes in (CLBO) crystals
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2002.2, [ ix, 117 p. ]한국과학기술원 : 물리학과
구역벽이 없는 SU(9) 통일장 모델
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 1985.8, [ iii, 63 p. ]The domain wall problem in grand unified theories due to the unbroken symmetries are in contradiction with the modern cosmology based on the big bang theory. We construct a SU(9) grand unified model without the domain walls and study the symmetry breaking patterns, the intermediate mass scale and the fermion contents of the model. First, we give some constraints which the fermion representations of the SU(N) groups should satisfy. Then we find that there are two kinds of fermion representations according to the assignment of the hypercharges. One is the representation which allows the trivial charge assignment and the other is the one which allow the nontrivial charge assignment. Next, we search for the possible grand unified model without the domain walls. For the representations with the trivial charge assignment, we find only one model in SU(9) which contains the three generations and for the representations with the nontrivial charge assignment, we find a unique model in SU(9). Hence the study of the details of the SU(9) becomes important. Then we give the possible symmetry breaking patterns and the corresponding projection matrices which can be used to find the fermion contents of the low energy symmetry. Also we discuss the grand unification mass scale for some typical symmetry breaking patterns. Finally, we give a formula to determine the intermediate mass scale of the SU(N) group. Using the limit on the proton life time and the cosmological requirements on the intermediate mass scale, we determine the symmetry breaking patterns and the value of the nontrivial charge assignment by applying the formula stated above.한국과학기술원 : 물리학과
Author Correction: Immune cell composition in normal human kidneys (Scientific Reports, (2020), 10, 1, (15678), 10.1038/s41598-020-72821-x)
No full text© 2021, The Author(s).This Article contains an error in Figure 6a, where the data shown does not correlate with the Article. The correct Figure 6a appears below as Figure 1. (Figure presented.).N
무기물의 나노 구조 패터닝을 위한 실리콘 함유와 실리콘 처리 블록 공중합체에 관한 연구
No full text학위논문(박사) - 한국과학기술원 : 화학과, 2010.2, [ xii, 93 p. ]\Bf{ Silicon-Treated Block Copolymers for SiO_2 Nanostructures}
Surfaces patterned with regularly sized and spaced features at the nanoscopic level have attracted much interest over the last decade. The inherent variety of block copolymers makes their self-assembly an attractive means of creating such surfaces and they have been used as effective and versatile templates for many inorganic materials. Silicon oxide () in particular has demonstrated tremendous promise in applications ranging from microelectronics to photonic devices.
First, highly dense nanodot arrays were fabricated via a selective chemical reaction with a functionalized block copolymer template. Polystyrene-\It{b}-poly(acrylic acid/acrylic anhydride) (PS-\It{b}-PAA/AN) thin films on an SU-8 photoresist, generated from polystyrene-\It{b}-poly(\It{tert}-butylacrylate) (PS-\It{b}-PtBA) by acid-catalyzed thermal deprotection, were used as templates. Due to the presence of PAA/AN nanodomains with carboxylic acids cross-linked by anhydride linkages, these templates acted as robust and versatile scaffolds with excellent solvent and thermal resistance. Hexamethyldisilazane (HMDS) was spin-sprayed uniformly over the entire surface of the self-assembled PS-\It{b}-PAA/AN film and reacted selectively with carboxylic acids in the spherical domains of PAA/AN. RIE in an atmosphere removed all organic components, resulting in arrays of free-standing silica nanostructures over a wide area of the substrate.
Secondly, the self-assembly of an amine-terminated polydimethylsiloxane (PDMS) via the noncovelent interactions onto the functionalized block copolymer template was used to silicon oxide nanodot arrays. This method could make a possible not only to increase contents of silicon but also to simplify a whole process. PS-$\It{b}-PAA/AN thin films on an SU-8 photoresist were dipped on the amine-terminated PDMS solution and PDMS was self-assembled selectively onto the spheric...한국과학기술원 : 화학과
Corneal keloid: four case reports of clinicopathological features and surgical outcome
No full textThis article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.Abstract
Background
Surgical outcome of corneal keloid is largely variable depending on reports, although surgical management is inevitable in visually significant cases. We here report clinical features, histopathological findings, and surgical outcome of four cases of corneal keloid.
Case presentation
Four Korean male patients without a history of corneal trauma or disease were clinically and histologically evaluated for a slowly-growing, white opacity in the cornea. On slit lamp examination, corneal lesions appeared as a solitary, pearly white, well-circumscribed nodule with a smooth and glistening surface. Because the lesions involved the visual axis deteriorating the visual acuity, the nodules were surgically removed by superficial keratectomy in all patients. Amniotic membrane transplantation was combined in three patients, and an intraoperative mitomycin C application in two patients. Hematoxylin-eosin staining of the excised nodules revealed epithelial hyperplasia, Bowmans layer disruption, thick and irregularly-arranged collagen fibers in the stroma, and accumulation of prominent fibroblasts, which are consistent with the diagnosis of corneal keloid. The corneal keloids recurred in all patients within 10months of surgical excision and outgrew the boundary of the excised area.
Conclusion
A diagnosis of corneal keloid should be suspected in patients presenting with an enlarging, white, glistening corneal nodule, even in the absence of a history of corneal trauma or disease. The recurrence is common after surgical excision, and the lesion can be exacerbated by surgery
- …
