• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.99-99
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• 2010

최근 집속이온빔을 이용한 미세회로 교정, MEMS 공정 및 이온 도핑 등에 대한 연구개발이 활발히 이루어지고 있다. 기존에 널리 사용되었던 액체 금속 이온 소스의 경우 비교적 큰 angular divergence 및 Ga 이온 소스에 의한 오염이 문제시 되고 있어 이를 대체할 수 있는 가스 이온 소스에 대한 연구를 진행하였다. 본 연구에서 사용된 가스 이온 소스는 2 turn 안테나(1/4 inch Cu tube)가 감긴 반경 4 cm 석영관 내부에 Ar 가스를 주입 후 RF(13.56MHz)-ICP 타입 방전을 이용하였다. 운전 압력은 $10^{-5}\;Torr$ 범위이며 인가된 RF 전력은 최대 150 W이다. 석영관 내 발생된 플라즈마로부터 Ar 이온을 인출하기 위해 2단 인출 전극 구조가 사용되었으며 상단 전극에 고전압이 인가되고 하단 전극이 접지되는 형태이다. 2단 인출 전극의 최대 인출 전압은 10 kV, 상단 및 하단 전극의 구멍 크기는 각각 0.3 mm, 2 mm이다. 이온빔의 퍼짐을 최소화하기 위해 전극 간 공간 내 이온 거동 전산모사를 통해 전극 구조를 설계하였으며 이를 통해 최대 $30\;mA/cm^2$의 이온 전류 밀도 값을 얻을 수 있었다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.155-160
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• 2024

The polarization-selective beam splitter grating can be widely used in numerous optical information processing systems. In this paper, to design a high-efficiency plasma polarization beam splitter (PBS), the structure composed of an Ag metal layer in Littrow mounting is implemented. To achieve high diffraction efficiency in the transmitted 0th-order TE polarization and the reflected 0th-order TM polarization, the grating depth and grating ratio of presented PBS is optimized by using rigorous Modal Transmission-Line Theory. From the optimized results, PBS has advantages of wide band properties for incident wavelength and angle, and the efficiency is higher than 95% for both TE and TM polarization. Therefore, this highly efficient PBS wideband grating with high extinction ratio can be used as an excellent optical diffraction device.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.71-78
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• 2014

There is a big risk of bullet impact because military rotorcraft is run in the battle environment. Due to the bullet impact, the rapid increase of the internal pressure can cause the internal explosion or fire of fuel cell. It can be a deadly damage on the survivability of crews. Then, fuel cell of military rotorcraft should be designed taking into account the extreme situation. As the design factor of fuel cell, the internal fluid pressure, structural stress and bullet kinetic energy can be considered. The verification test by real object is the best way to obtain these design data. But, it is a big burden due to huge cost and long-term preparation efforts and the failure of verification test can result in serious delay of a entire development plan. Thus, at the early design stage, the various numerical simulations test is needed to reduce the risk of trial-and-error together with prediction of the design data. In the present study, the bullet impact numerical simulation based on SPH(smoothed particle hydrodynamic) is conducted with the commercial package, LS-DYNA. Then, the resulting equivalent stress, internal pressure and bullet's kinetic energy are evaluated in detail to examine the possibility to obtain the configuration design data of the fuel cell.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.128-133
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• 2013

In this paper, octagonal inductors for RFIC designs was fabricated with 90nm CMOS Technology to compare its quality factor and the effective inductance as functions of radius and number of turn. The quality factor decreases as the inner radius and the number of metal turned increase. However, the effective inductance increases with the increasing the inner radius and the number of metal turned. Therefore, the inductor structure should be decided according to the relative importance of Q-factor and inductance.

• Composites Research
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• v.21 no.1
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• pp.1-7
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• 2008

Composite vessels for high pressure gas storage are commonly used these days because of their competitive weight reduction ability maintaining strong mechanical properties. To supplement permeability of composite under high pressure, it is usually lined by metal, which is called a Type 3 vessel. However, it has many difficulties to design the Type 3 vessel because of its complex geometry, fabrication process variables, etc. In this study, therefore, GUI (graphic user interface) optimal design code for Type 3 vessels was developed based on semi-geodesic algorithm in which various factors of geometry and fabrication variables are considered and genetic algorithm for optimization. In addition, hydrogen vessels for 350/700 bar that can be applied to FCVs(fuel cell vehicles) were designed using this code for verification.

• Korean Journal of Optics and Photonics
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• v.33 no.4
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• pp.177-186
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• 2022

The performance of a surface plasmon resonance sensor is evaluated based on the sensitivity (nm/RIU) and sharpness from the full width at half maximum (FWHM) and the peak depth of a resonance peak. These factors are determined by the materials and conformational properties of the sensing structure. In this paper, we investigated an optimized insulator-metal-insulator (IMI) multilayer-based surface plasmon resonance sensor structure to simultaneously achieve high sensitivity, narrow FWHM, and deep peak depth while using gold for the metallic film layer which occurs peak broadening. By adopting the optimized structure, sensitivity of 8,390 nm/RIU, FWHM of 11.92 nm, and a resonance peak depth of 93.1% were achieved for 1.45-1.46 refractive index variation of the sensing layer. With the suggested structure conformation, high sensitivity and resolution of sensing performance can be achieved.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.7
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• pp.589-594
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• 2014

Recently, higher capacity and energy density of lithium ion batteries are increasingly demanded for enhancing their performance in view of the rise in the commercial distribution of electric and hybrid vehicles. Computational analysis of a porous structure of vanadium pentoxide cathode was performed, employing a phase field model. The incipient model was designed as a spherical structure with cylindrical-shaped pores. Modifying the diameters and lengths of the pore cylinder and the number of pores, we considered different conditions for the porous vanadium pentoxide cathodes for analyzing their effect on the amount of lithium ion intercalated to them. Subsequently, we optimized the porous structure to contain the largest amount of intercalated lithium ion during discharge.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.4
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• pp.299-314
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• 2014

A lifting device is used to deal with transport cask for the transportation of spent fuels from nuclear power plants. This study performed theoretical analysis and numerical simulation to evaluate the structural integrity of the lifting device based on Nuclear Safety and Security Commission(NSSC) Notice No.2013-27 and US 10CFR Part 71 ${\S}71.45$. The results of theoretical analysis showed that the maximum stresses of all components were below the allowable values. This result confirmed that the lifting device was structurally safe during operation. The results of finite element analysis also showed that it was evaluated to satisfy the design criteria bothyielding and ultimate condition. All components have been shown to ensure the structural safety due to sufficient safety margins. In other words, the safety factor was 3 or more for the yielding condition and was 5 or more for the ultimate condition.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.347-351
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• 2020

A material changes its physical and chemical properties through the interaction with radiation and also the neutrons, which is electronically neutral so that the penetration depth is relatively deeper than that of other radioactive way including alpha or beta ray. Therefore, the radiation damage by neutron irradiation has been intensively investigated for a long time with respect to the safety of nuclear power plants. The damage induced by neutron irradiation begins with the creation of point defects in atomic scale in the unit of picoseconds, and their progress pattern can be characterized by microstructural defects, such as dislocation loops and voids. Their morphological characteristics affect the properties of neutron-irradiated materials, therefore, it is very important to predict the microstructure at a given neutron irradiation condition. This paper briefly reviews the evolution of radiation damage induced by neutron irradiation and introduces a phase-field model that can be widely used in predicting the microstructure evolution of irradiated materials.

• Polymer(Korea)
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• v.35 no.3
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• pp.260-264
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• 2011

Biodegradable polymeric stents have been issued to replace the existing non-degradable metal stents due to relatively improved biocompatibility and low side effects. Fundamentally, all the stents must possess the desired mechanism strength, especially, compression or radial force to maintain the diameters of expanded vessels. Therefore, this study suggests a helical structure and focused on the relation between the lateral compression and structural factors, Unlike a cylindrical model, the radial force of the helical model is proportional to the thickness and the length to the power of one, whereas the diameter to the power of 1.6. The function obtained from these results might provide the fundamental information to design and prepare the stem for clinical applications.