• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.163-167
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• 2002

Improved optical switching property of electrochromic nickel hydroxide/nickel glass thin film is reported. Nickel metal film was deposited on glass by e-beam evaporation before following electrochemical redox cycling to form nickel hydroxide for electrochromic activation. Without ITO (indium tin oxide) layer as electrical conductor, this electrode showed more rapid coloration rate than nickel hydroxide film on ITO substrate in the change of the electric voltage and optical transmittance. XPS analysis confirmed the existence of ultra-thin nickel metal layer (${\sim}10{\AA}$) between electrochemically grown nickel hydroxide and the glass substrate. It is concluded that the remained nickel metal nano-layer attribute to the conduction layer and the enhanced response time.

• Journal of the Korean Society of Radiology
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• v.3 no.4
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• pp.23-28
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• 2009

Monochromatic X-ray can make a medical image of high contrast under a low radiation dose and can be easily generated by combining an X-ray tube and a multilayer mirror. A W/C multilayer mirror was optimally designed for a characteristic X-ray generated from a X-ray tube with Mo target. The d-spacing and the thickness ratio in design parameters were determined under the maximum-reflectivity condition. Tolerances for deposition and alignment of the W/C multilayer mirror were calculated. Within a deposition tolerance of 0.2nm and a alignment tolerance of ${\pm}0.01^{\circ}$, 85% of the theoretical peak reflectivity could be achieved. A multilayer mirror can be widely used for making medical images because of generating high fluence monochromatic X-ray.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.120-126
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• 2002

ZnS thin films were prepared on glass substrate at various deposition conditions by a HW apparatus and were systematically investigated the growth characteristics, in terms of deposition edges by a double beam spectro- photometer, and structural analysis by a x-ray diffraction rates were increased with incresing the cell temperature and vapor pressure of sulfur, but were decreased with increasing substrate temperature. The optical characteristics of thin films depends on the deposition rates. The band gap energies of 3.46∼3.52eV measured at room temperature are smaller than the theoretical value of 3.54eV, indicating that impurities exist in the crystal. All ZnS thin films are oriented in the (III) principal direction of a zincblende structure. By introducing the S vapor, optical and crystalline properties have been improved.

• Journal of the Korean Vacuum Society
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• v.14 no.3
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• pp.143-146
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• 2005

A new method of x-ray photon correlation spectroscopy (XPCS) using coherent x-rays is developed recently for probing the dynamics of surface height fluctuations as a function of lateral length scale. This emerging technique applies the principles of dynamic light scattering in the x-ray regime. The short wavelength and slow time scales characteristic of XPCS extend the phase space accessible to scattering studies beyond some restrictions by light and neutron. In this paper, we demonstrate XPCS to study the dynamics of surface fluctuations in thin supported polymer films. We present experimental verification of the theoretical predictions for the wave vector and temperature dependence of the capillary wave relaxation times for the supported polymer films at melt for the film thicknesses thicker than 4 times of the radius of gyration of polymer. We observed a deviation from the conventional capillary wave predictions in thinner films. The analysis will be discussed in terms of surface tension, viscosity and effective interactions with the substrate.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.11
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• pp.781-790
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• 2001

The effects of silicon substrate thickness on the performance of thin film PZT IR detectors are theoretically and experimentally investigated. Theoretical analyses show that the pyroelectric current responsivity of a detector without a silicon substrate is about two orders higher than that of a detector with a 450${\mu}{\textrm}{m}$ thick silicon substrate. At a fixed chopping frequency of 100Hz, the pyroelectric current responsivity decreases exponentially with increasing silicon substrate thickness up to 50${\mu}{\textrm}{m}$, and above 50${\mu}{\textrm}{m}$ the decreasing rate become slow. The thinner the silicon substrate is, the less the thermal loss by conduction is , and thus the higher responsivity is resulted. To verify the theoretical analyses, micromachined PZT thin film IR detectors with different silicon substrate thicknesses are fabricated and characterized. The theoretical and experimental results show the similar tendencies for all silicon substrates with varying thickness.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.677-677
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• 2013

최근 석유에너지의 고갈과 휴대용 전자기기의 사용의 증가로 고효율의 배터리의 개발이 요구되고 있다. 생체칩에서 부터 전기자동차, 에너지 저장체까지 광범위한 산업군에 걸처 배터리의 개발이 되고 있어 시장규모의 계속적인 성장이 있을 것으로 전망하고 있다. 현재 상용되고 있는 음극 재료는 카본재료(이론 용량 372 mAh/g)이다. 이 카본재료의 특징은 값이 싸고, 표준 환원전위가 낮아 비교적 높은 전압을 낼 수 있다. 그러나 낮은 에너지밀도를 갖으므로 높은 에너지를 필요로 하는 차세대 산업군인 전기자동차 등에는 적합하지 않은 것으로 평가되고 있다. 그래서 더 높은 에너지 밀도를 갖는 다른 재료들에 대한 연구들이 활발히 이루어지고 있다. 본 연구에서는 음극 재료로서 주석을 선택해서 연구를 하였다. 카본계열의 음극재료의 질량당 이론 에너지 밀도는 372 mAh/g임에 반해 주석같은 경우는 약 991 mAh/g 정도의 비교적 큰 이론용량을 갖고 있다. 하지만, 주석 등 금속, 혹은 금속 합금을 음극재료로 사용할 경우 많은 양의 리튬이 삽입/탈착되면서 약 300% 이상의 부피변화가 있게 된다. 그러한 과정에서 주석이 분쇄되어 떨어지거나 전자를 제공받는 집전체로부터 떨어지게 되고, 이 과정에서 심각한 에너지 밀도의 손실이 일어나게 된다. 이러한 문제점들을 극복하기 위해 다음과 같은 구조들을 고안하여 도금 공정을 사용하여 음극재료를 제작하여 실험을 진행하게 되었다. 도금법은 대면적을 싼 가격으로 할 수 있으며 원하는 두께 및 모폴로지까지 쉽게 조절할 수 있다. 부피팽창에 의한 스트레스를 최소화하기 위해 도금법을 사용하여 나노구조를 만들어 그에 따른 전기화학적 특성 변화를 측정하였다. 다공성 필름인 AAO 디스크의 한 면에 구리를 sputtering 공정을 사용하여 0.5 um 두께의 seed layer 구리 박막을 형성하고 형성된 구리 박막 위에 도금공정을 이용하여 두껍게 구리를 증착함으로 구리 음극 집전체를 형성한다. 그 후 AAO 구조 안에 주석을 도금하면 AAO의 구조를 따라 주석 나노와이어가 형성이 된다. 마지막으로 NaOH로 AAO를 제거해주면 직경 200 nm, 길이 2 um 정도의 주석 나노와이어를 구리 집전체위에 만들 수 있었다. 배터리의 용량을 측정한 결과 안정한 싸이클 특성과 약 400 mAh/g의 에너지 밀도를 갖는 것으로 나타났다.

• Journal of the Korean Chemical Society
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• v.44 no.1
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• pp.60-67
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• 2000

The wavelength of the surface plasmon absorption depends on the dielectric matrix. $TiO_2/SiO_2$ complex oxide films doped with Au nanoclusters were prepared by sol-gel spin-coating method using $Ti(OPr^i)_4$, $Si(OEt)_4$, and $HAuCl_4{\cdot}7H_2O$. The wavelength of the maximum absorption of Au nanoehrsters in the $TiO_2/SiO_2$ thin films was obtained with lineality from 540 nm to 615 nm depending on the molar ratio of $TiO_2$. The particle sizes and structures of these nanoclusters have been identified through a TEM and X-ray diffraction patterns. The dielectric constants of $TiO_2/SiO_2$ thin films were calculated from the experimental results.

• Korean Journal of Optics and Photonics
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• v.13 no.1
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• pp.9-14
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• 2002

A surface plasmon sensor has been fabricated for detection of concentration and refractive-index of a mixed solution. Based on the Kretschmann-Raether attenuated-total-reflection configuration, the sensor consists of 54 nm-thick Ag metal layer under a prism and a cell containing the mixed solution. We have observed a nonlinear refractive-index change as the ethanol-water concentration increased. The experimental results show us that the detection limit of the SPR sensor is 3$\times$10$^{-2}$ % in ethanol mass ratio. The concentration-to-index curve shows a linear increase in the range of ethanol concentration from 0% to 50%, but a nonlinearity is observed beyond 50%. We have modeled the nonlinearity and compared it with the experimental results.

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.221-225
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• 2005

Formation of a narrow magnetic domain wall is demonstrated by micromagnetics simulations. It is found that the domain wall width can be shrunk in a local exchange coupled system. The local exchange coupled system means that only a part of a ferromagnetic layer has an exchange coupling with another ferromagnetic layer. The system can be considered as two parts in the lateral dimensions: one is an exchange coupled region and another is a free region. Since the two regions have quite different local switching fields, the domain wall will be formed at the interface between the two regions at moderate field ranges.

• Journal of the Korea Convergence Society
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• v.11 no.3
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• pp.163-170
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• 2020

This research was to understand the current situation and trends of urban design using rapidly growing solar cells at home and abroad, and to understand the positive aspects and implications of urban design proposals using CIGS thin film solar cells, a research project to be conducted based on case analysis. The research method was conducted through a literature study and the case was investigated and analyzed after identifying the present situation and trends of urban design using solar cells from home and abroad. As a result, it was confirmed that urban design using solar cells was steadily increasing, and through visual changes such as harmony with the surrounding environment, indoor and outdoor visualization, and the use of color, urban aesthetic beauty creation was positive. Based on these implications, we will present the expected effects of CIGS thin film solar cells being utilized in urban design, and confirm the direction and significance of the urban design proposal using CIGS thin film solar cells in the future.