• 자원리싸이클링
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• 제7권4호
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• pp.27-34
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• 1998

본 연구에서는 NiCuZn Ferrite(NCZF) 제조공정의 제어에 대하여 연구하였다. $700^{\circ}C$, 3시간 하소한 NCZF를 약 60시간 볼밀링하여 약 $0.5\mu\;extrm{m}$ 입자크기로 분쇄한 후 분무 건조하여 과립화하였다. NCZF의 충전율에 따른 겉보기 고화속도 및 초기투자율에 미치는 영향을 조사한 결과 다음과 같은 결과를 얻었다. 1. 성형압력 유지시간 1분에서 성형압력을 약 20~170 ㎫로 변화시켜 제조한 NCZF 토로이달 상의 출발시편은 성형압이 증가하면서 입자의 충전율은 48.6%에서 56.8%로 증가하였다. 2. 일정 소성온도에서 NCZF의 충전율이 높아질수록 고화속도가 높아지고, 일정 성형압력에서 소성온도가 높아질수록 NCZF의 겉보기 고화속도는 빨라졌다. NCZF의 충전율과 소성온도가 높고, 소성시간이 길어지면 bulk density는 증가하였다. 3. 고정된 조성에서 소성온도($875~925^{\circ}C$)와 소성시간(0~5시간)의 조합에 의해 제조된 NCZF의 초기투자율은 bulk density와 semi-log상에서 직선적인 비례관계를 가지며 NCZF입자의 충전율에 크게 의존하였다. NCZF입자의 충전율과 이들을 소성하였을 때의 bulk density를 알면 초기투자율을 예측할 수 있었다. log $\mu$i=$G1{\times}BD$+$G2{\times}충전율$+b(0), G1;0.8394, G2;-3.6233, (b);0.7053.

• 공업화학
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• 제18권6호
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• pp.636-642
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• 2007

다양한 크기를 가진 다성분 입자의 충전분율을 정확하게 예측할 수 있는 소프트웨어 프로그램을 개발하였다. 이를 위하여 다양한 크기의 염소산암모늄(Ammonium perchlorate, AP)과 알루미늄(Aluminum, Al) 입자와 혼합물에 대한 충전분율 측정실험을 수행하였다. 실험에 의해 얻어진 충전분율은 개발된 프로그램에 의해 예측된 값과 비교하였다. 크기가 다른 2종류 입자의 혼합 충전의 경우 상대오차가 0.25~13.13%, 3종류 입자의 혼합 충전의 경우 0.13~10.01%로 나타나 실험값과 잘 일치하였다. 목표 충전분율을 얻기 위한 각 구성입자의 질량분율 contour를 프로그램을 통하여 구할 수 있으며 이를 통하여 충전시스템을 최적화 할 수 있다.

• 센서학회지
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• 제24권6호
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• pp.385-391
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• 2015

In this paper, we propose a new method to infiltrate $Fe_3O_4$-nanoparticles into a porous silicon film and a monitoring technique to detect packing density of nanoparticles within the film. Recently, research to use porous silicon as a drug carrier or a new functional sensor material by infiltrating $Fe_3O_4$-nanoparticles has been extensively performed. However, it is still necessary to enhance the packing density and to develop a monitoring technique to detect the packing density in real time. In this light, we forcibly injected a nanoparticle solution into a rugate-structured free-standing porous silicon (FPS) film by applying a pressure difference between the two sides of the film. We found that the packing density by the pressure-infiltration method proposed in this paper is enhanced, relative to that by the previous diffusion method. Moreover, a continuous shift in wavelength of the rugate reflectance peak measured from the film surface was observed while the nanoparticle solution was being injected. By exploiting this phenomenon, we could qualitatively monitor the packing density of $Fe_3O_4$-nanoparticles within the FPS film with the injection volume of the nanoparticle solution.

• 한국연초학회지
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• 제14권1호
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• pp.57-65
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• 1992

The quality of cut tobacco will be deteriorated due to weather conditions such as temperature and relative humidity, when shipping and long term storaging. The change of equilibrium moisture contents in cut tobacco were under influence of relative humidity and temperature but not humectants. Therefore internal packing materials are necessary for cut tobacco to maintain initial quality, including taste, flavour and musty smell during shipping or storaging. When packing cut tobacco for shipping or long term storaging, desiralbe packing density was 200/$m^2$, For the long term storage under R.H 90% and 3$0^{\circ}C$, polyethylene film thickness suitable for packing material are above 100$\mu$, which resulted in 42days of shelf life.

• 한국세라믹학회지
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• 제30권4호
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• pp.309-315
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• 1993

Gas pressure sintering is a promising process in various densification methods of high strength Si3N4 ceramics. Environmental influences on gas pressure sintering of Si3N4 was investigated with the variationof packing powder, specimen container and N2 gas pressure. The specimens had higher density, larger weight loss and inhomogeneous color in graphite specimen container than in SN26 crucible. The variations of sintering densities in various packing powders (Si3N4, SN26, AlN, BN) were very small but SiC powder was synthesised in graphite crucible with Si3N4 packing powder, aluminium oxynitride compounds were synthesised in SN26 crucible with AlN packing power. Also N2 gas pressure over 20kg/$\textrm{cm}^2$ reduced the densification of Si3N4 in one step-gas pressure sintering. As the result of two step-gas pressure sintering at 700kg/$\textrm{cm}^2$ for 15min., relative density of 99.9% and 3-point bending strength of 1090MPa and dense microstructure of 3~4${\mu}{\textrm}{m}$ grain size were obtained.

• 한국수소및신에너지학회논문집
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• 제21권2호
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• pp.111-116
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• 2010

In this study, the structural analysis was performed to optimize the membrane humidifier with hollow fiber membrane for polymer electrolyte membrane fuel cell system. The main design factors were considered by evaluating the humidifying performance according to various structural parameters such as packing density and length. The effects of operation conditions of membrane humidifier were also elucidated experimentally. Results imply that there are optimum points for the packing density and length of humidifier. It was also found that among operation conditions, relative humidity of wet exhaust gas and temperature of dry inlet gas have major effects on the humidifying performance.

• 한국세라믹학회지
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• 제33권12호
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• pp.1414-1420
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• 1996

평균 입경 8${\mu}{\textrm}{m}$ Si 분말을 사용하여 무가압 분말 충전 성형볍에 의해 Si 성형체를 제조하였다. 이 Si 성형체를 1350,140$0^{\circ}C$의 온도에서 3~35시간동안 N2/H2 분위기에서 반응 소결한 후 미세구조를 관찰하였다. 반응 소결체는 90% 이상의 질화율과 88%의 상대밀도를 보였다. 반응 소결체의 가스압 소결을 위해 소결조제로서 MgO를 Mgnitrate 수용액 형태로 Si 성형체에 5wt% 첨가한 후140$0^{\circ}C$에서 15시간동안 반응 소결하였다. 이후 반응 소결체를 1800, 1900, 200$0^{\circ}C$에서 각각 150, 300분 동안 가스압 소결을 행하여 95%의 상대밀도와 598 MPa의 꺾임강도, 6 MPa.m1/2의 파괴인성을 나타내는 질화규소 소결체를 제조하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.471.2-471.2
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• 2014

We demonstrate here that an improvement in precursor film density (green density) leads to a great enhancement in the photovoltaic performance of CuInSe2 (CISe) thin film solar cells fabricated with Cu-In nanoparticle precursor films via chemical solution deposition. A cold-isostatic pressing (CIP) technique was applied to uniformly compress the precursor film over the entire surface (measuring 3~4 cm2) and was found to increase its relative density (particle packing density) by ca. 20%, which resulted in an appreciable improvement in the microstructural features of the sintered CISe film in terms of lower porosity, reduced grain boundaries, and a more uniform surface morphology. The low-bandgap (Eg=1.0 eV) CISe PV devices with the CIP-treated film exhibited greatly enhanced open-circuit voltage (VOC, from 0.265 V to 0.413 V) and fill factor (FF, from 0.34 to 0.55), as compared to the control devices. As a consequence, an almost 3-fold increase in the average power conversion efficiency, 3.0 to 8.2% (with the highest value of 9.02%), was realized without an anti-reflection coating. A diode analysis revealed that the enhanced VOC and FF were essentially attributed to the reduced reverse saturation current density (j0) and diode ideality factor (n). This is associated with the suppressed recombination, likely due to the reduction in recombination sites such as grain/air surfaces (pores), inter-granular interfaces, and defective CISe/CdS junctions in the CIP-treated device. From the temperature dependences of VOC, it was confirmed that the CIP-treated devices suffer less from interface recombination.

• 한국재료학회지
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• 제5권7호
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• pp.829-834
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• 1995

지르코니아 분말 합성 시 500ppm의 Polyvinyl Alcohort(PVA) 첨가에 의해 입자가 균질하게 분산된 안정된 지르코니아 현탁액을 제조하였다. 이러한 현탁액으로부터 원심분리에 의해 제조된 충진체는 PVA를 첨가하지 않은 시편의 충진체에 비해 기공의 크기가 작은 고밀도의 균질한 충진체였다. 이 충진체를 사용하여 소결한 결과, 지르코니아 소결에 있어서는 비교적 낮은 온도인 125$0^{\circ}C$에서도 상대밀도가 98%인 고밀도의 단사성 지르코니아 소결체를 제조할 수 있었다.

• 한국세라믹학회지
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• 제34권4호
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• pp.343-350
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• 1997

To fabricate the ceramic/metal(SiC/ Al alloy) composite, SiC preform was prepared by Pressureless Powder Packing Forming Method and 6061 Al alloy was infiltrated into the preform. Uniform compact having an average pore size of 10 ${\mu}{\textrm}{m}$ and narrow pore size distribution was prepared. Phenolic resin solution(40 wt%) was penetrated into the SiC compact, and then the compact was preheated at the temperature of 120$0^{\circ}C$. The pore size distribution and the microstructure of the preform were not changed by preheating. An uniform microstructure without any crack in the preform was obtained in SiC-Al alloy composite. The infiltration of 6061. Al alloy into the preform began at the temperature of 130$0^{\circ}C$ and the amount of infiltration increased in proportion to the infiltration temperature and the soaking time. The increasement rate of the infiltration amount decreased after 3 h. As a result of the infiltration at 140$0^{\circ}C$ for 4 h, Al alloy was well distributed in the interparticle channels and the relative density of the composite was above 98%. The strength and the fracture toughness of the composite were 303 MPa and 21.65 MPam1/2, respectively.