• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.443-447
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• 2004

In this study, we investigated the necessity of encapsulation layer to maximize flexibility of brittle indium-tin-oxide (ITO) on polymer substrates. And, Young's modulus (E) of encapsulation layer han a significant effect on external bending stress and the coefficient of thermal expansion (CTE) of that han a significant effect on internal thermal stress. To compare the magnitude of total mechanical stress including both bending stress and thermal stress, the mechanical stress of triple-layer structure (substrate / ITO / encapsulation layer or substrate / buffer layer / ITO) can be quantified and numerically analyzed through the farthest cracked island position. As a result, it should be noted that multi-layer structures with more elastic encapsulation material have small mechanical stress compared to that of buffer and encapsulation structure of large Young's modulus material when they were externally bent.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.155-160
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• 2002

Using measured data at Daegu by tethersonde for the period of 1984∼1987, we have investigated the lower atmospheric boundary layer structure including relationships between inversion layer and meteorological factors(wind and temperature), and the inversion strength and inversion height. The inversion layer was defined from the vertical temperature profile and its strength was analyzed with the wind shear as well as the vertical temperature gradient. From October to January, measured inversion layer isn't destroyed, however, in June, after sun rise, it is destroyed by surface heating and mixed layer is developed from surface. According to Pasquill stability classes, the moderately stable cases dominated. It's the larger vertical temperature gradient the lower SBL height. We have introduced B(bulk turbulence scale) which indicated SBL height. It's larger B, the higher SBL height and vice versa. It was noted that the bulk turbulence scale (B) is appropriate to determine the stable boundary layer height.

• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.41-45
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• 2018

Two-dimensional (2D) materials have been studied extensively due to their excellent physical, chemical, and electrical properties. Among them, we report the material and device characteristics of tin disulfide ($SnS_2$). To apply $SnS_2$ as a channel layer in a transistor, $SnS_2$ channels were formed by a stripping method and a transfer method. The limitation of this method is that it is difficult to produce uniform device characteristics over a large area. Therefore, we directly deposited $SnS_2$ by atomic layer deposition (ALD) and then performed lithography. This method was able to produce devices with repeatable characteristics over a large area. However, the $SnS_2$ film was damaged by the acetone used as a photoresist (PR) developer during the lithography process, with the electrical properties of mobility of $2.6{\times}10^{-4}cm^2/Vs$, S.S. of 58.1 V/decade, and on/off current ratio of $1.8{\times}10^2$. These results are not suitable for advanced electronic devices. In this study, we analyzed the effect of acetone on $SnS_2$ and studied the device process to prevent such damage. Using polyvinyl alcohol (PVA) as a passivation layer during the lithography process, the electrical characteristics of the $SnS_2$ transistor had $2.11{\times}10^{-3}cm^2/Vs$ of mobility, 11.3 V/decade of S.S, and $2.5{\times}10^3$ of the on/off current ratio, which were 10x improvements to the $SnS_2$ transistor fabricated by the conventional method.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1629-1631
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• 2007

Significant process in the performance and commercialization of full-color thin-film electroluminescent(EL) displays has been achieved. This is due to the remarkable progress made in the performance of exiting EL phosphors, development of new phosphor materials, and design of new EL phosphor structures. In this paper, we fabricated thinfilm EL devices with ZnS buffer and $BaTiO_3$ electric layer with on top and bottom of phosphor layer. The effect of ZnS and $BaTiO_3$ layer on the luminance of EL device were studied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.828-834
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• 2010

In this paper, an adaptive cross-layer resource allocation algorithm for the downlink multi-user OFDM system is proposed. The proposed algorithm does not only concern the wireless characteristics of physical (PHY) layer, but also pays attention to the user's quality of service (QoS) requirement, fairness, and packet queue state information of medium access control (MAC) layer. The algorithm is composed of two parts: one is to decide the priority of the user, and the other is to assign the radio resource according to its priority. Simulation results show that the proposed algorithm has both steady QoS and low computation complexity, even though the mobile users have different receiving signal to noise ratio (SNR).

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.253-255
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• 2009

박막태양전지에서 빛을 처음 받아들이는 p-layer는 전체적인 태양전지 특성에 큰 영향을 준다. 본 논문에서는 p-layer의 gas flow rate를 가변하여 증착한 P-I-N cell을 통해 DIV를 측정하고 분석하였다. 더불어 gas flow rate에 따른 p-layer의 특성변화를 토대로 시뮬레이션을 진행하여 실제 소자와 비교하여 보았다. simulation da와 experimental data를 비교해보면 전체적으로 유사한 경향성을 보이며 saturation current는 큰 차이를 보이지 않았으나 ideality factor와 series resistance에서 real device가 비교적 큰 값을 나타내는 것을 볼 수 있었다. 본 연구는 simulation data를 기반으로 real device를 제작하는데 큰 도움이 될 것이다.

• Journal of the Korean Wood Science and Technology
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• v.15 no.3
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• pp.44-55
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• 1987

In order to study the effect of sawdustboard combined with plastic chips, 0.5mm($T_1$), 1mm($T_2$), 1.4mm($T_3$) thick nylon fiber. polypropylene rope fiber(RP), and 0.23mm thick moth-proof polypropylene net fiber(NP) were cut into 0.5, 1, 2cm long plastic chips. Thereafter, sawdustboard combined with plastic chips prepared as the above and plastic non-combined sawdustboard(control) were manufactured into 3 types of one-, two-, and three layer with 5 or 10% combination level. By the discussions and results at this study, the significant conclusions of mechanical and physical properties were summarized as follows: 1. The MORs were shown in the order of 3 layer> 2 layer> 1 layer among plastic non-combined boards, and $T_3$ < $T_2$ < $T_1$ < RP (NP(5%) < NP(l0%) among plastic combined boards. In 2cm long plastic chip in 1 layer board, the highest strength through all the composition was recognized. 1 layer board showing the lower strength with 0.5cm plastic chip rendered to the bending strength improvement by 2 or 3 layer board composition. On the other hand, 2 or 3 layer combined with 1, 2cm long polypropylene net fiber chips incurred MOR's conspicuous decrease requiring optimum plastic chip combined level and consideration to combined type. 2. MOE in plastic non-combined 3 layer board exhibited sandwich construction effect by higher resin content application to surface layer in the order of 3layer>1layer>2layer with the highest stiffness of the board combined with polypropylene chip, while nylon chip-combined board had little difference from plastic non-combined board. In relevant to length and layer effect, 3 layer board combined with the 0.5cm long polypropylene net fiber chip in 5% and 10% combined level presented 34-43% and 44-76% stiffness increase against plastic non-combined board(control), respectively. Moreover, in 1 layer board, 30% stiffness increase with 10% against 5% combined level in the 1 and 2cm long polypropylene net fiber chip was obtained. 3. Stress at proportional limit(Spl) showing the fiber relationship (r: 0.81-0.97) between MOR presented in the order of 1 layer<2 layer<3 layer in plastic non-combined board. Correspondingly, combined effect by layer and plastic chip length was similar to MOR's. 4. Differently from previous properties(MOR, MOE, Spl). work to maximum load(Wml) of 2 layer board approached to that of 3 layer board. Conforming the above phenomenon. 2 layer combined with 0.5cm long polypropylene net fiber chip kept the greater work than 1 layer. The polypropylene combined board superior to nylon -and plastic non - combined board seemed to have greater anti - failing capacity. 5. Internal bond strength(IB), in contrast to MOR's tendency. showed in the order of T1

• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.229-232
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• 2005

Direct characterization of band alignment at chemical bath deposition $(CBD)-CdS/Cu_{0.93}(In_{1-x}Ga_x)Se_2$ has been carried out by photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). Ar ion beam etching at the condition of the low ion kinetic energy of 400 eV yields a removal of surface contamination as well as successful development of intrinsic feature of each layer and the interfaces. Especially interior regions of the wide gap CIGS layers with a band gap of $1.4\~1.6\;eV$ were successfully exposed. IPES spectra revealed that conduction band offset (CBO) at the interface region over the wide gap CIGS of x = 0.60 and 0.75 was negative, where the conduction band minimum of CdS was lower than that of CIGS. It was also observed that an energy spacing between conduction band minimum (CBM) of CdS layer and valance band maximum (VBM) of $Cu_{0.93}(In_{0.25}Ga_{0.75})Se_2$ layer at interface region was no wider than that of the interface over the $Cu_{0.93}(In_{0.60}Ga_{0.40})Se_2$ layer.

• Applied Microscopy
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• v.28 no.4
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• pp.491-502
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• 1998

The present study was conducted to investigate the structural changes in rat cornea. Sixty eyes from one-day-old uneyed rats, fourty eyes from 4-weeks-old rats, and foully eyes from 10-weeks-old adult rats were used. With the increase of age, the epithelial layer was thickened by the addition of new successive cellular layers. Then, the new-born rat's epithelial cells formed a pentagonal shape, and the quality of decidual cells showed a high electron-density, although the boundary between cells was distinctive. The newly produced cells showed a low electron-density so that there was the distinctive difference between light and darkness. In Bowman's layer, collagen fibrils demonstrate a regularly arranged structure along with the age. In stroma's layer, the density of keratocytes was decreased and thereby Progressively flattened during the development. The collagenous layer of the adult rats was more distinctive than that of the new-born rats in a form of parallel alignment running vertically and horizontally.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.127-130
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• 2003

We have carried out two-beam interference experiment to form holographic grating on amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ single-laver, $MgF_{2}/As_{40}Ge_{10}Se_{15}S_{35}$ muliti-layer. In this study holographic grating formed using He-Ne laser(632.8nm) under different polarization state(intensity, phase polarization holography). The diffraction efficiency was obtained by first order intensity. The maximum diffraction efficiency of $As_{40}Ge_{10}Se_{15}S_{35}$ single-laver was 0.8% and The maximum diffraction efficiency of $MgF_{2}/As_{40}Ge_{10}Se_{15}S_{35}$ multi-layer(multi-layer I, multi-layer II) were 1.4% and 3.1%.