• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.900-906
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• 2004

Solid oxide fuel cells have a limitation in their low-temperature application due to the low ionic conductivity of electrolyte materials and difficulties in thin film formation on porous gas diffusion layer. These problems can be solved by improvement of ionic conductivity through controlled nanostructure of electrolyte and adopting nanoporous electrodes as substrates which have homogeneous submicron pore size and highly flattened surface. In this study, ultra-thin oxide films having submicron thickness without gas leakage are deposited on nanoporous substrates. By oxidation of metal thin films deposited onto nanoporous anodic alumina substrates with pore size of $20nm{\sim}200nm$ using dc-magnetron sputtering at room temperature, ultra-thin and dense ionic conducting oxide films with submicron thickness are realized. The specific material properties of the thin films including gas permeation, grain/gran boundaries formation, change of crystalline structure/microstructure by phase transition are investigated for optimization of ultra thin film deposition process.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.81-85
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• 2002

전기 전자 제품에 사용되는 반도체 칩이나 부품들은 작동시 발열을 하게 되며 이러한 열은 적절히 제거되지 않은 경우 전기 전자 제품의 오작동을 유발시키는 요인이 된다. 발열부품이 작동할 때 발생되는 열을 제거하기 위해서 히트싱크나 냉각팬과 같은 구조를 발열 부품 장착시 같이 설치하는 방법이 일반적으로 사용되는 냉각구조 형태지만 이와 같은 냉각 구조는 최근의 전기 전가 제품의 소형화 추세에 부응하는데는 한계가 있다. 따라서 이러한 냉각 구조의 한계를 보완하기 위한 방안으로써 소형화한 히트싱크, 즉 두께와 방열의 중요 요인이 되는 히트싱크의 방열핀의 크기를 나노미터 단위에서 밀리미터 단위로 제조한 마이크로 히트 싱크를 제조하여 그 효용성에 대해 연구하고자 하였다. 마이크로 히트싱크의 제조는 균일한 포어를 포함한 폴리머 멤브레인에 열전도성이 뛰어난 금속을 무전해 도금하는 방법으로 제조하였으며 주사현미경으로써 관찰하였다.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.321-322
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• 2007

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• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.260-260
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• 2009

탄소나노튜브 (carbon nanotube, CNT)는 우수한 전기적, 화학적, 기계적 성질과 큰 비표면적인 구조적인 특성에 기인하여 전자방출원 수직 소자에서의 interconnection, 에너지 저장 소자에서의 전극재료 및 고감도센서 등 다양한 분야로의 응용이 예상되고 있다 [1]. 본 연구에서는 이러한 응용을 위한 계면제어 측면제어 측면에서, 고전도성을 확보하기 위하여 금속 기판 위에 수직배향 탄소나노튜브(VCNT)를 직접 성장시키고자 하였다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2001.11a
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• pp.242-247
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• 2001

Foam Plastics, cellular plastics, expanded plastics, plastic foam 등 여러 가지 이름으로 불리우고 있는 발포플라스틱은 plastic matrix 내에 무수한 cell이 open 형태 혹은 closed 형태로 존재하는 플라스틱 재료이며/sup 1)/ 원료플라스틱 보다 경량성, 열전도성, 충격흡수성 등 제반물성이 우수하여 포장재료, 보온재, 완충재 및 각종 구조재료로써 널리 사용되고 있으며 소재 plastic의 특성에 따라 PE, PP, PVC, PS, ABS 등 다양하게 개발되어 있다.(중략)

• Journal of Korean Association for Spatial Structures
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• v.16 no.3
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• pp.89-97
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• 2016

With the recent trend to construct high-rise and large buildings, the steel structure system is widely used, but there are not enough studies on the vibration characteristics of the iFLASH system on the buildings. Therefore, in this study, we performed a vibration measurement of the natural frequency and damping ratio in the stage of iFLASH panel, composit, frame completion and cladding completion. The result findings suggest that the damping ratio after the cladding completion has a greater effect on the reduction of the damping ratio, than the stage after the frame completion.

• Progress in Superconductivity
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• v.14 no.1
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• pp.11-16
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• 2012

Based on fully self-consistent dynamical mean field theory (DMFT) method, we investigate electronic structure and Fermi surface nesting property of LiFeAs and NaFeAs, focusing on the correlation effect of iron 3d orbital. For LiFeAs, good nesting property by density functional theory (DFT) method is much suppressed by DFT+DMFT method due to the orbital-dependent renormalization magnitude. NaFeAs shows a similar behavior, but a better nesting is obtained than LiFeAs from DFT+DMFT Fermi surfaces. Our result is consistent with the observed superconducting (spin density wave) ground state of LiFeAs (NaFeAs).

• Journal of Korean Society of Forest Science
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• v.88 no.1
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• pp.38-46
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• 1999

Canopy structure conductances of a Norway spruce forest in the Solling Hills(Central Germany) and Central Forest Biosphere Reserve(320km to the north-west from Moscow) were derived from LE(latent heat flux) and H(sensible heat flux) fluxes measured(by Eddy correlation technique and energy balance method) and modelled(by one dimensional non-steady-state) SVAT(soil-vegetation-atmosphere-transfer) model(SLODSVAT) using a rearranged Penman-Monteith equation("Big-leaf" approximation) during June 1996. They were compared with canopy stomatal conductances estimated by consecutive intergrating the stomatal conductance of individual needles over the whole canopy("bottom-up" approach) using SLODSVAT model. The result indicate a significant difference between the canopy surface conductances derived from measured and modelled fluxes("top-down" approach) and the stomatal conductances modelled by the SLODSVAT("bottom-up" approach). This difference was influenced by some nonphysiological factors within the forest canopy(e.g. aerodynamic and boundary layer resistances, radiation budget, evapotranspiration from the forest understorey). In general, canopy surface conductances derived from measured and modelled fluxes exceeded canopy stomatal conductance during the whole modelled period, The contribution of the understorey's evapotranspiration to the total forest evapotranspiration was small (up to 5-9% of the total LE flux) and was not depended on total radiation balance of forest canopy. Ignoring contribution of the understorey's evapotranspiration resulted in an overestimation of the canopy surface conductance for a spruce forest up to 2mm/s(about 10-15%).

• Korean Journal of Heritage: History & Science
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• v.57 no.2
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• pp.28-50
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• 2024

A fact-finding survey of the Demilitarized Zone can be said to be a very meaningful academic survey linked to previous index surveys of protected military areas and municipal and excavation surveys of ruins and military sites on Mount Dora. Not a few ruins were first discovered in this survey, and the locations, structures, and restoration artifacts of the previously investigated ruins were confirmed differently, raising the need for a detailed investigation. In particular, it is noteworthy that various relics from the Paleolithic Age to the Joseon Dynasty were recovered from relics dispersion sites such as Josan-ri and Cheorwon Gangseo-ri in Paju, and Hoengsan-ri Temple Site is also a Buddhist relic in the Demilitarized Zone. However, in the case of some graveyards and relics sites in the Paju region, it was an opportunity to understand the reality that they are not safe from cultivation and development, and the ruins of Cheorwon Capital Castle, Seongsanseong Fortress, Jorangjin Bastion, and Gangseo-ri Bastion were damaged during the construction of military facilities, and an urgent investigation is needed. Also, farmland and hilly areas around the ruins of Jangdan, Gunnae-myeon, and Gangsan-ri have not been properly investigated for buried cultural assets due to small-scale development. Therefore, it is an important time for the relevant authorities and agencies to cooperate more closely to establish special management and medium- to long-term investigation measures for the cultural heritage in the Demilitarized Zone based on the results of this fact-finding investigation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.6
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• pp.541-548
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• 2015

We study the structural and functional characteristics of zinc oxide (ZnO) nanostructures that are grown on carbon nanotube (CNT) constructs via step-wise chemical vapor deposition (CVD). First, we optimize the CVD process to directly grow ZnO nanostructures on CNTs by controlling the growth temperature below $600^{\circ}C$, where CNTs can be sustained in a ZnO-growing oxidative atmosphere. We then investigate how the morphology and areal density of ZnO nanostructures evolve depending on process parameters, such as pressure, temperature, and gas feeding composition, while focusing on the effect of underlying CNT topology on ZnO nucleation and growth. Because various types of ZnO nanostructures, including nanowires, nanorods, nanoplates, and polycrystalline nanocrystals, can be conformally formed on highly conductive CNT platforms, this electrically addressable three-dimensional hybrid nanoarchitecture may better meet a wide range of nanoelectronic application-specific needs.