• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1023-1023
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• 2004

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.278-281
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• 2009

Selective laser sintering(SLS), a kind of rapid prototyping technology, can provide a process to form many types of coatings. Coated layers by selective laser melting are highly influenced by substrate, powder and laser parameters such as laser power, scan rate, fill spacing and layer thickness. Therefore an attempt to fabricate Fe-Ni-Cr coating on AISI H13 tool steel has been performed by selective laser sintering. In this study, Fe-Ni-Cr coating was produced by experimental facilities consisting of a 200W fiber laser which can be focused to 0.08mm and atmospheric chamber which can control atmospheric pressure with Ar. With power increase or energy density decrease, line width was decreased and line surface quality was improved with energy density increase. Surface quality of coating layer was improved with fill spacing optimization or layer thickness decrease.

• 한국기계가공학회지
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• 제17권5호
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• pp.117-122
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• 2018

3D printing technology and its applications have grown rapidly in academia and industry. We consider a 3D printing system designed for the selective laser sintering (SLS) method, which is one of the powder bed fusion (PBF) techniques to build up the final product by layering sintered powder slices. Thermal distortion of printing products is a critical challenge in 3D printing. This study investigates temperature-dependent conformational behaviors of 3D printed samples of sintered poly-ether-ether-ketone (PEEK) powders using molecular dynamics simulations. The wear and chemical resistance properties of PEEK are understood, as it is a well-known biocompatible material used for implants. However, studies on physical phenomena at nanoscale in PEEK are rarely published in public. We simulate dissipative particle dynamics to elucidate how a cavity regime forms in PEEK at different system temperatures. We demonstrate how PEEK structures deform subject to the system temperature distribution.

• 한국진공학회지
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• 제18권2호
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• pp.108-115
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• 2009

150 주기의 InAs/GaSb (8/8-ML) 제2형 응력초격자 (SLS)를 활성층에 탑재한 초격자 적외선검출소자 (SLIP) 구조를 MBE 방법으로 성장하고, 직경 $200{\mu}m$의 개구면을 가지는 SLIP 개별소자를 시험 제작하였다 고분해능 투과전자현미경 (TEM) 이미지의 휘도분포와 X선회절 (XRD) 곡선의 위성피크의 분석 결과는 SLS 활성층은 균일한 층두께와 주기적 응력변형을 유지하는 급격한 계면의 초격자임을 입증하였다. 흑체복사 적외선 광원을 이용하여 측정한 입사파장 및 인가전압에 따른 반응도 (R)와 검출률 ($D^*$)로부터, 차단파장은 ${\sim}5{\mu}m$이고 최대 R과 $D^*$ ($\lambda=3.25{\mu}m$)는 각각 ${\sim}10^3mA/W$ (-0.6 V/13 K)와 ${\sim}10^9cm.Hz^{1/2}/W$ (0 V/13 K)임을 보였다. 반응도의 온도의존성으로부터 분석한 활성화에너지 275 meV는 광반응 과정에 개입되어 있는 가전대 및 전도대 부준위 사이의 에너지 간격 (HH1-C)과 잘 일치하였다.

• 한국기계가공학회지
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• 제14권4호
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• pp.62-72
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• 2015

Interest in three-dimensional (3D) printing processes has grown significantly, and several types have been developed. These 3D printing processes are classified as Selective Laser Sintering (SLS), Stereo-Lithography Apparatus (SLA), and Fused Deposition Modeling (FDM). SLS can be applied to many materials, but because it uses a laser-based material removal process, it is expensive. SLA enables fast and precise manufacturing, but available materials are limited. FDM printing's benefits are its reasonable price and easy accessibility. However, metal printing using FDM can involve technical problems, such as suitable component supply or the thermal expansion of the heating part. Thus, FDM printing primarily uses materials with low melting points, such as acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) resin. In this study, an FDM process for enabling metal printing is suggested. Particularly, the nozzle and heatsink for this process are focused for stable printing. To design the nozzle and heatsink, multi-physical phenomena, including thermal expansion and heat transfer, had to be considered. Therefore, COMSOL Multiphysics, an FEM analysis program, was used to analyze the maximum temperature, thermal expansion, and principal stress. Finally, its performance was confirmed through an experiment.

• Journal of Magnetics
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• 제21권1호
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• pp.35-39
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• 2016

$Cr_{100-x}Ti_x$ amorphous texture-inducing layers (TIL) were investigated to realize highly (002) oriented $L1_0$ FePt-C granular films through hetero-epitaxial growth on the (002) textured bcc-$Cr_{80}Mn_{20}$ seed layer (bcc-SL). As-deposited TILs showed the amorphous phase in Ti content of $30{\leq}x(at%){\leq}75$. Particularly, films with $40{\leq}x{\leq}60$ kept the amorphous phase against the heat treatment over $600^{\circ}C$. It was found that preference of the crystallographic texture for bcc-SLs is directly affected by the structural phase of TILs. (002) crystallographic texture was realized in bcc-SLs deposited on the amorphous TILs ($40{\leq}x{\leq}70$), whereas (110) texture was formed in bcc-SLs overlying on crystalline TILs (x < 30 and x > 70). Correlation between the angular distribution of (002) crystal orientation of bcc-SL evaluated by full width at half maximum of (002) diffraction (FWHM) and a grain diameter of bcc-SL indicated that while the development of the lateral growth for bcc-SL grain reduces FWHM, crystallization of amorphous TILs hinders FWHM. $L1_0$ FePt-C granular films were fabricated under the substrate heating process over $600^{\circ}C$ with having different FWHM of bcc-SL. Hysteresis loops showed that squareness ($M_r/M_s$) of the films increased from 0.87 to 0.95 when FWHM of bcc-SL decreased from $13.7^{\circ}$ to $3.8^{\circ}$. It is suggested that the reduction of (002) FWHM affects to the overlying MgO film as well as FePt-C granular film by means of the hetero-epitaxial growth.

• 한국응용과학기술학회지
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• 제12권1호
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• pp.47-54
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• 1995

각종 세정제의 난용 및 과대 사용으로 인한 수질오염이 날로 심각해지고 있으며 이 때 수질오염의 원인은 주로 계면활성제에 의해 발생한다. 본 연구는 이미 다졸린으로부터 유도된 9종의 양쪽성계면활성제와 석유 화학물질로부터 제조하여 대량 사용하고 있는 sodium lauryl sulfate(SLS)에 대한 세정성을 비교하여 보다 우수한 계면활성제를 선정하고자 한다. 또한 세정성의 비교는 세정력의 측정과 세정에 관한 물리화학적 측면에서 그 원인을 규명하고자 한다. 1-(2-hydroxyethyl)-1-(3-sulfonatedropy)-2-undecyl-2-imidazolinum [IV]는 세정성 및 다른 기초적 물성이 우수하여 세정제에 응용할 경우 세정성이 우수한 계면활성제 일수록 오염 부착에 필요한 일이 적게 나타나 오염이 쉽게 제거될 수 있음을 증명하였으며 그로 인한 공업적 응용성에 기대가 크다.

• 사회복지연구
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• 제41권3호
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• pp.213-239
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• 2010

본 연구의 목적은 국가복지가 확대되는 우리 현실에서, 복지국가의 발전방식(제도 보편성)에 대한 선호에 영향을 미치는 요인이 무엇인지를 파악하는 것이다. 특히, 주관적 인식과 선호의 인과구조를 밝히는 과정에서 발생할 수 있는 내생성(endogeneity) 문제를 고려해, 도구변수를 활용한 2SLS 회귀분석을 시도하였다. 분석결과는 다음과 같다. 첫째, 국가복지의 확대에 반대할 것으로 예상되는 집단(고소득자, 저위험자, 그리고 고용주/자영업자 등)들이 보편적 복지는 선호하는 것으로 나타났다. 둘째, 주관적 인식의 경우 복지제도 및 수혜자에 대한 부정적 인식은 보편적 복지를 반대하는 쪽으로 영향을 미쳤다. 추가로 부정적 인식은 산업화 시대를 오래 경험한 세대들에서 더 강한 것으로 나타났다. 셋째, 태도로 태도를 설명하고자 할 경우에 발생할 수 있는 내생성 문제가 본 연구에서도 확인되었다. 이것은 실제로 추정회귀계수를 왜곡시키고 있었다. 따라서 관련 후속연구들은 분석과정에서 이를 유념해야 할 것으로 보인다.

• 산업경영시스템학회지
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• 제33권4호
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• pp.159-166
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• 2010

The speed at which products are developed and released to market is tightly linked to profitability and market share. Hence, many companies are still in a desperate need of real Rapid Tooling (RT) technologies which can really help to expedite their prototype tooling and pre -production tooling for injection molding. Many other companies that have been very skeptical of RT technologies developed so far are working on Hybrid Tooling (HT) that can really meet the market standards. With the conviction that HT can be a reliable alternative for current RT technologies, this paper describes the experimentation how HT process has been being successfully established and effectively applied with typical case studies. Through the experimentation, Ceramic-filled SLA tooling was found to be aptly suited for the low grade mold, and Metal SLS tooling was found to be aptly suited for the medium volume mold both in terms of the lead time, dimensional accuracy, and tooling cost.

• 한국대기환경학회지
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• 제16권4호
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• pp.381-388
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• 2000

Ceramic foam prepared with cordierite as a starting material by foam method was tested to evaluate the feasibility as a filter for the dust collection in hot gas. Two different types of agents Benzethonium chloride (BZTC, C27H42NO2Cl) and Sodium Lauryl Sulfate(SLS, CH3(CH2)11OSO3Na) were used as foaming agents in foaming process. Porosityof ceramic foam was about 80% and mean pore size were 100${\mu}{\textrm}{m}$ for SLS agent and 200 ${\mu}{\textrm}{m}$ for BZTC. It was observed that ceramic foam was composed of continuous macro-pore structure with opening windows interconnecting macro-pores. The surface of ceramic foam support of was coated with cordierite particles ranged from 20${\mu}{\textrm}{m}$ to 50${\mu}{\textrm}{m}$ Meso-pore size in the coating layer on ceramic foam was below 10${\mu}{\textrm}{m}$. While air permeability of the support increased with increasing macro-pore size coated ceramic filters showed a constant permeability without regard to the macro-pore size of the support. The permeabuilities of support varied in the range of 600$\times$10-13m2 to 1000$\times$10-13m2. For the case of coated ceramic filter it was about 200$\times$10-13m2. As a result of particle trapping test by using fly ash the particle removal efficiency was over the 99.9%.