• Journal of Advanced Marine Engineering and Technology
• /
• 제27권2호
• /
• pp.289-298
• /
• 2003

Meshfree approximations exhibit significant Potential to solve partial differential equations. Meshfree methods have been successfully applied to various problems which the traditional finite element methods have difficulties to handle including the quasi-static and dynamic fracture, large deformation problems, contact problems, and strain localization problems. Reproducing Kernel Particle Method (RKPM) is used in this research fur to its built-in feature of multi-resolution. the sound mathematical foundation and good numerical performance. A formulation of RKPM is reviewed and numerical examples are given to verify the accuracy of the proposed meshfree method for largely deformed elasto-plastic material.

• 대한기계학회논문집A
• /
• 제30권6호
• /
• pp.622-630
• /
• 2006

This paper is about the magnetic suspension stage based on the Switched Reluctance propulsion principle. Because the previous studies on contact-free stage adopted the Lorentz force for main force generation mechanism they have suffered from thermal problem deteriorating the precision. Thus, the magnetic suspension stage adopting SR principle which can achieve high force density is proposed. The main operating principle and structure for achieving high resolution and long travel range are represented. The magnetic force analysis of each actuator, providing back data for dynamic modeling and controller design are carried out. By conducting basic experiments, the feasibility of the proposed system is shown. In addition the problems which should be improved and their solutions are represented.

• 대한기계학회논문집A
• /
• 제30권6호
• /
• pp.637-642
• /
• 2006

A plastic zone size is regarded as a measure of material resistance, and also it determines the fracture behavior. The importance of estimating or measuring the plastic zone size cannot be too emphasized. In this article, SDSP(Stereo Digital Speckle Photography) is examined as a new techniques to measure the plastic zone developed in a ductile metal. This technique is simple, vibration free and non-contact, and measures simultaneously in-plane displacements as well as out-of plane displacements like the side necking. Experimental results for a CT specimen are presented to demonstrate the accuracy in comparison with those obtained by recrystallization technique and finite element analysis.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.327-329
• /
• 2006

In this paper, the cutting qualities by laser dicing and fracture strength of a silicon die is investigated. Laser micromachining is the non-contact process using thermal ablation and evaporation mechanisms. By these mechanisms, debris is generated and stick on the surface of wafer, which is the problem to apply laser dicing to semiconductor manufacture process. Unlike mechanical sawing using diamond blade, chipping on the surface and crack on the back side of wafer isn't made by laser dicing. Die strength by laser dicing is measured via the three-point bend test and is compared with the die strength by mechanical sawing. As a results, die strength by laser dicing shows a decrease of 50% in compared with die strength by mechanical sawing.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2010년도 춘계학술발표대회
• /
• pp.38.2-38.2
• /
• 2010

We have studied mechanisms of back contact formation in Al evaporation and screen printed Al paste for Si solar cells by TEM analysis. We observed that Si diffuse into Al during heat up. The Si diffusion process made vacancies in Si wafer. The Al began to seep into the Si wafer (Al spike). During heat down, the Al spike were shrink which causes the doped region (BSF).

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.304-304
• /
• 2012

CIGS(CuInGaSe2) 태양전지의 후면전극(Back contact)으로 널리 사용되는 Mo 박막은 낮은 면저항, 높은 반사율, 광흡수층 Na-path 제공 등의 조건이 요구된다. 일반적으로 Mo 박막 제작은 DC 마그네트론 스퍼터링 방법이 가장 널리 사용되며, 제작조건에 따라 태양전지 효율에 강한 영향을 미치는 것으로 보고되고 있다. 본 연구에서는 DC 마그네트론 스퍼터링 시 기판에 이온빔(Ion-beam)을 동시 조사하는 이온 빔 스퍼터링 증착(Ion-beam sputter deposition)법으로 Mo 박막을 제작하였다. 제작된 박막의 전기적 및 광학적 특성은 4-point probe, UV-Vis-NIR spectrometer로 각각 조사하였으며 Na-path 제어를 위한 구조적 특성은 XRD, FE-SEM으로 분석하였다. 분석결과에 따르면 기존 DC 마그네트론 스퍼터링 방법보다 상대적으로 더 치밀한 구조와 높은 반사율을 가지는 박막이 제작됨을 알 수 있었다. Mo 박막의 최적조건은 DC power 300 W, Ion-gun power 50 W, Ar flow rate 20 sccm 였다.

• 한국가구학회지
• /
• 제13권1호
• /
• pp.42-47
• /
• 2002

The folding chairs are one of the most necessary furniture for satisfying the moderns' wants which is utilized for limited space rationally. These folding chairs are variously used in interior spaces such as offices, dining areas, and resting areas. They are very easy to move around, so that quiet useful in out door areas, too. Moreover, they play an important role in public spaces as supplementary furniture. The folding chairs have one or several axes, and they are classified according to type of axes like below. 1. Method of divide seating board into 2 and fold, 2. Method of folds seating board and lay on bottom of backboard, 3. Method of fold back board and lay on top of seating board, 4. Method of fold into contact with left and right, 5. Method of gathering legs into one and fold. The folding chairs have to be easy to operate, firm and safe, light for moving around easily, designed for able to change units whenever they have damaged. Change of residential spaces according to the trend towards the nuclear family maximized necessity of limited spaces' use. Therefore, this study provides insights for development of new methods' of folding chairs.

• 한국반도체및디스플레이장비학회:학술대회논문집
• /
• 한국반도체및디스플레이장비학회 2006년도 춘계학술대회
• /
• pp.251-254
• /
• 2006

In this paper, cutting qualifies and fracture strength of silicon dies by laser dicing are investigated. Laser micromachining is the non-contact process using thermal ablation and evaporation mechanisms. By these mechanisms, debris is generated and stick on the surface of wafer, which is the problem to apply laser dicing to semiconductor manufacture process. Unlike mechanical sawing using diamond blade, chipping on the surface and crack on the back side of wafer isn't made by laser dicing. Die strength by laser dicing is measured via the three-point bending test and is compared with the die strength by mechanical sawing. As a results, die strength by the laser dicing shows a decrease of 50% in compared with die strength by the mechanical sawing.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2001년도 사면안정 설계 및 시공 특별강연회
• /
• pp.19-30
• /
• 2001

This paper represents a case study to determine optimal rock properties and to analyse the safety of slopes excavated in faulted and severly weathered ground. The study site consists of two slopes with a length of 240m and a height of 30m in contact with a tunnel. Significant efforts have been exerted for determining the proper strength parameters such as cohesion and internal friction of rockmass by back analyses as well as laboratory and in-situ tests. Limit equilibrium analyses have also been conducted using these properties.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
• /
• pp.92-97
• /
• 2002

We establish a visible light emission from porous polycrystalline silicon nano structure(PPNS). The PPNS layer are formed on heavily doped n-type Si substrate. 2um thickness of undoped polycrystalline silicon deposited using LPCVD (Low Pressure Chemical Vapor Deposition) anodized in a HF: ethanol(=1:1) as functions of anodizing conditions. And then a PPNS layer thermally oxidized for 1 hr at $900 ^{\circ}C$. Subsequently, thin metal Au as a top electrode deposited onto the PPNS surface by E-beam evaporator and, in order to establish ohmic contact, an thermally evaporated Al was deposited on the back side of a Si-substrate. When the top electrode biased at +6V, the electron emission observed in a PPNS which caused by field-induces electron emission through the top metal. Among the PPNSs as functions of anodization conditions, the PPNS anodized at a current density of $10mA/cm^2$ for 20 sec has a lower turn-on voltage and a higher emission current. Furthermore, the behavior of electron emission is uniformly maintained.