• Structural Engineering and Mechanics
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• 제83권1호
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• pp.53-66
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• 2022

The main objective of the present research was investigating the effects of a floating wave barrier installed in front of an offshore jacket structure on the wave height, base shear, and overturning moment. A jacket model with the height of 4.55 m was fabricated and tested in the 402 m-long wave flume of NIMALA marine laboratory. The jacket was tested at the water depth of 4 m subjected to the random waves with a JONSWAP energy spectrum. Three input wave heights were chosen for the tests: 20 cm, 23 cm, and 28 cm. Two different cross sections with the same area were selected for the wave barrier: square and rhombus. Results showed that the average decrease in the jacket's base shear due to the presence of a floating wave barrier with square and rhombus cross section was 24.67% and 34.29%, respectively. The use of wave barriers with square and rhombus cross sections also resulted in 19.78% and 33.11% decrease in the jacket's overturning moment, respectively. Hence, it can be concluded that a floating wave barrier can significantly reduce the base shear and overturning moment in an offshore jacket structure; and a rhombus cross section is more effective than an equivalent square section.

• Journal of Magnetics
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• 제10권4호
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• pp.137-141
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• 2005

We confirmed that the improvement in properties of magnetic tunnel junctions prepared by radical oxidation after thermal treatment was mostly resulted from the redistribution of oxygen at the $AIOx/Co_{90}Fe_{10}$ interface. The as-deposited Al oxide barrier was oxygen-deficient but most of it re-oxidized into $Al_2O_3$, the thermodynamically stable stoichiometric phase, through thermal treatment. As a result, the effective barrier height was increased from 1.52 eV to 2.27 eV. On the other hand, the effective barrier width was decreased from 8.2 ${\AA}$ to 7.5 ${\AA}$. X-ray absorption spectra of Fe and Co clearly showed that the oxygen in the CoFe layer diffused back into the Al barrier and thereby enriched the barrier to close to a stoichiometirc $Al_2O_3$ phase. The oxygen bonded with Co and Fe diffused back by 6.8 ${\AA}$ and 4.5 ${\AA}$ after thermal treatment, respectively. Our results confirm that controlling the chemical structures of the interface is important to improve the properties of magnetic tunnel junctions.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.241-245
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• 2022

In this study, we measured and comparatively analyzed the characteristics of MPS (Merged Pin Schottky) diodes in 4H-SiC by changing the areal ratio between the Schottky and PN junction region. Increasing the temperature from 298 K to 473 K resulted in the threshold voltage shifting from 0.8 V to 0.5 V. A wider Schottky region indicates a lower on-resistance and a faster turn-on. The effective barrier height was smaller for a wider Schottky region. Additionally, the depletion layer became smaller under the influence of the reduced effective barrier height. The wider Schottky region resulted in the ideality factor being reduced from 1.37 to 1.01, which is closer to an ideal device. The leakage saturation current increased with the widening Schottky region, resulting in a 1.38 times to 2.09 times larger leakage current.

• ETRI Journal
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• 제39권2호
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• pp.284-291
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• 2017

Drain-induced barrier lowering (DIBL) is one of the main parameters employed to indicate the short-channel effect for nano metal-oxide semiconductor field-effect transistors (MOSFETs). We propose a new physical model of the DIBL effect under two-dimensional approximations based on the energy-conservation equation for channel electrons in FETs, which is different from the former field-penetration model. The DIBL is caused by lowering of the effective potential barrier height seen by the channel electrons because a lateral channel electric field results in an increase in the average kinetic energy of the channel electrons. The channel length, temperature, and doping concentration-dependent DIBL effects predicted by the proposed physical model agree well with the experimental data and simulation results reported in Nature and other journals.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.910-912
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• 2006

Barrier ribs in plasma display panels (PDPs) function to maintain the discharge space between the glass plates as well as to prevent optical cross-talking. The barrier ribs currently employed are typically $300{\mu}m$ pitch, $110{\sim}120{\mu}m$ in height, with upper and lower widths of $50{\mu}m$ and $80{\mu}m$, respectively. It has been reported that barrier ribs can be fabricated by screen-printing, sand blasting, etching and photolithographic processes. In this study, photosensitive barrier rib pastes were formulated and systematically evaluated in terms of photolithographic process variables such as printing, drying, UV exposure, development and sintering. It was found that the use of UV absorbent, polymerization inhibitor and surfactant were very effective in controlling the width uniformity of barrier ribs in the photolithographic method of barrier rib patterning.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.279-282
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• 2001

The IBE(ion beam etching)-induced Schottky barrier variation which depends on various etching history related with ion energy, incident angle and etching time has been investigated using voltage-current, capacitance-voltage characteristics of metal-etched silicon contact and morphology of etched surface were studied using AFM(atomic force microscope). For ion beam etched n-type silicons, Schottky barrier is reduced according to ion beam energy. It can be seen that amount of donor-like positive charge created in the damaged layer is proportional to the ion energy. By contrary, for ion beam etched p-type silicons, the Schottky barrier and specific contact resistance are both increased. Not only etching time but also incident angle of ion beam has an effect on barrier height. Taping-mode AFM analysis shows increased roughness RMS(Root-Mean-Square) and depth distribution due to ion bombardment. Annealing in an N$_2$ ambient for 30 min was found to be effective in improving the diode characteristics of the etched samples and minimum annealing temperatures to recover IBE-induced barrier variation were related to ion beam energy.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권3호
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• pp.203-212
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• 2010

In this paper, we present an analytical model for the first eigen energy level ($E_0$) of the carriers in the inversion layer in present generation MOSFETs, having ultrathin gate oxides and high substrate doping concentrations. Commonly used approaches to evaluate $E_0$ make either or both of the following two assumptions: one is that the barrier height at the oxide-semiconductor interface is infinite (with the consequence that the wave function at this interface is forced to zero), while the other is the triangular potential well approximation within the semiconductor (resulting in a constant electric field throughout the semiconductor, equal to the surface electric field). Obviously, both these assumptions are wrong, however, in order to correctly account for these two effects, one needs to solve Schrodinger and Poisson equations simultaneously, with the approach turning numerical and computationally intensive. In this work, we have derived a closed-form analytical expression for $E_0$, with due considerations for both the assumptions mentioned above. In order to account for the finite barrier height at the oxide-semiconductor interface, we have used the asymptotic approximations of the Airy function integrals to find the wave functions at the oxide and the semiconductor. Then, by applying the boundary condition at the oxide-semiconductor interface, we developed the model for $E_0$. With regard to the second assumption, we proposed the inclusion of a fitting parameter in the wellknown effective electric field model. The results matched very well with those obtained from Li's model. Another unique contribution of this work is to explicitly account for the finite oxide-semiconductor barrier height, which none of the reported works considered.

• 한국자기학회지
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• 제12권3호
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• pp.99-102
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• 2002

기존 절연막보다 균일한 AlO 절연막을 형성하기 위해 플라즈마 산화법을 이용하여 이중 연속 절연막을 형성한 TMR소자를 제작하였다. 10 $\AA$의 Al 하부 절연막의 산화시간을 10sec로 우선 완성하고 그 위에 13 $\AA$의 Al을 성막하고 50, 80, 120sec간 산화시켜 완성한 절연막의 특성을 알아본 결과 산화시간이 증가할수록 전기저항은 500 $\Omega$에서 2000 $\Omega$까지 크게 변화하며 80sec 에서 가장 작았고, MR비는 27~31 %로 큰 변화가 없었으나, 단일산화 절연막을 가진 시편(24%)보다는 모두 높은 자기저항비를 보였다. I-V측정을 통해 간접적으로 유효 장벽 높이와 장벽 폭을 계산한 결과 장벽 높이는 1.3~1.8eV로 터널링 장벽으로서 충분한 크기를 보였으며 장벽 폭의 경우에는 15.0 $\AA$ 이하로 실제 물리적으로 측정한 값보다 작음을 알 수 있었다. 이는 Al금속이 완전히 안정한 A1$_2$O$_3$로 산화되지 않았기 때문으로 생각되었으며, 그럼에도 불구하고 단일 AlO 절연막 시편보다는 균일하고 치밀한 절연막을 형성하였음을 확인하였다. 이러한 결과는 이중절연층 산화공정이 기존 공정보다 절연장벽을 우수하게 하여 MR비를 향상시키고 기준저항을 조절하는데 유리한 공정임을 의미하였다.

• Wind and Structures
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• 제34권3호
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• pp.275-290
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• 2022

Mobile sand barriers are a new type sand-retaining structure that can be moved and arranged according to the engineering demands of sand control. When only used for sand trapping, mobile sand barriers could be arranged in single row. For the dual purposes of sand trapping and sand stabilization, four rows of mobile sand barriers can be arranged in a staggered form. To reveal the effect of plane layout, the included angle between sand barrier direction and wind direction on the characteristics of flow fields and the sand control laws of mobile sand barriers, numerical computations and wind tunnel tests were conducted. The results showed that inflows deflected after passing through staggered arrangement sand barriers due to changes in included angle, and the sand barrier combination exerted successive wind resistance and group blocking effects. An analysis of wind resistance efficiency revealed that the effective protection length of staggered arrangement sand barriers approximately ranged from the sand barrier to 10H on the leeward side (H is sand barrier height), and that the effective protection length of single row sand barriers roughly ranged from 1H on the windward side to 20H on the leeward side. The distribution of sand deposit indicated that the sand interception increased with increasing included angle in staggered arrangement. The wind-breaking and sand-trapping effects were optimal when included angle between sand barrier direction and wind direction is 60°-90°.

• 농업과학연구
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• 제38권2호
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• pp.235-241
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• 2011

Recently, as people have become more interested in health issues, their demand on forest trails for bush walking exercise has increased. The purpose of the study is to select barrier factors into forest trail for disabled using wheelchairs. As a result this, it has selected 31 barrier factors through the Delphi method. Of all the these factors, the information board of forest trails, showing the location of the trails, has indicated the highest score of importance at 4.50. Next, securing hiker' walking safety space has indicated an importance level of 4.44; both the slope of forest trails and the height of obstacles have indicated an importance level of 4.38; and the effective width of forest trails has indicated the highest score of importance level of 4.33. From these indicated levels of importance, the respondents of the Delphi method consider the safety of users of forest trail' as the most important factor while the physically disables are hiking. That is why these factors have resulted in acquiring relatively higher values.