• 천문학회보
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• 제41권1호
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• pp.72.4-73
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• 2016

For the development of magneto rotational instability, which drives mass accretion in protoplanetary disks, sufficient ionization degree is needed. Cosmic rays are believed to be one of the dominant ionization sources for protoplanetary disk gas. In previous studies, ionization rates are computed by considering the effect of attenuation of the cosmic ray (CR) intensity as a function of column density in an unmagnetized cloud. However, in reality particles should sweep up larger column density to reach at the midplane of disk due to their gyromotion. In this study, we investigate the propagation of CR protons in a protoplanetary disk by solving transport and energy loss equations. We discuss the change in CR intensity due to magnetic field in a protoplanetary disk.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1040-1044
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• 1999

A micro porous PTFE membrane desolvator (MMD) was built and evaluated for the on-line removal of organic solvents to facilitate the determination of trace metal contaminants in the solvents by ICP-AES. Three organic solvents, isopropyl alcohol (IPA), methanol, and dimethy sulfoxide (DMSO) were studied. The MMD reduced organic solvent concentration in the sample aerosol stream by 82% to 89%, as indicated by monitoring C(I) emission. Net signal intensity of Fe, Al, and Cu was increasing with higher organic solvent concentration, with the rate of increase being solvent dependent. The signal intensities for Mg and Pb followed the trend with the C(I) signal. Changing the sweep gas flow rate affected the optimum signal intensity. Wine samples were analyzed by the method of standard addition. The concentrations of B, Al, and Mg were determined with a relative precision of less than 2.3%.

• 마이크로전자및패키징학회지
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• 제18권1호
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• pp.29-33
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• 2011

전류밀도는 전기도급법에서 생산성과 직접적인 연관이 있고, 생산성의 증가를 위해선 고전류밀도가 필요하다. 회전전극(RDE)의 회전 속도를 증가시키면 고유속을 얻을 수 있다. 유속 조절을 위해 회전전극과 원통형 회전 전극을 사용하였고, 전압과 전류의 관계를 알아보기 위해 정전류, 정전압 실험과 linear sweep voltammetry 실시하였다. 회전 전극의 회전 속도가 400 rpm이상 조건에서, 수소가 발생하지 않고 1000 A/$m^2$이상의 최대전류멸도가 가능하였다. $25^{\circ}C$와 $62^{\circ}C$ 조건에서 구리의 확산계수는 각각 $5.5{\times}10^6\;cm^2\;s^{-1}$와 $10.5{\times}10^6\;cm^2\;s^{-1}$로 계산되었다. 수소가 발생하지 않으면서 안정적으로 구리를 전착할 수 있는 조건은 -0.05 V (vs Ag/AgCl)이었다. 첨가제인 glue와 thiourea-를 넣음으로써 구리의 침상성장을 막을 수 있었다. 표면 거칠기는 UV-Vis Spectrophotometer를 아용하여 분석되었다. 600 nm 영역에서 반사도는 측정 되었고 표면 거철기가 개선될수록 표면 반사도가 증가하였다.

• 멤브레인
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• 제34권2호
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• pp.146-153
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• 2024

본 실험에서는 Ti를 기반으로 한 평판 수소 분리막을 설계하여 제조하였다. 새로운 조성의 Ti를 베이스로 한 수소 분리막을 찾기 위하여 여러 합금들의 물리화학적 특성과 수소투과도 사이의 상관관계에 대해 조사하였다. 이를 바탕으로 신조성의 합금막 2종(Ti_14.2Zr_66.4Ni_12.6Cu_6.8 (70 ㎛), Ti_17.3Zr_62.7Ni₂₀ (80 ㎛))을 설계 및 제조하였다. 제조된 평판 수소 분리막은 300~500℃, 1~4 bar의 조건에서 혼합 가스(H₂, N₂), sweep 가스(Ar)를 이용하여 수소 투과 실험을 진행하였다. Ti_14.2Zr_66.4Ni_12.6Cu_6.8 합금막은 500℃, 4bar에서 최대 16.35 mL/cm² min의 flux를 가지며, Ti_17.3Zr_62.7Ni₂₀ 합금막은 450℃, 4 bar에서 최대 10.28 mL/cm² min의 flux를 가진다.

• 공업화학
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• 제16권5호
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• pp.641-647
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• 2005

메탄의 부분산화반응은 수소 제조의 중요한 반응 중의 하나이다. 무전해 도금방법에 의해 제조된 팔라듐-은 막을 막반응기(membrane reactor)로서 메탄의 부분산화반응에 적용하여 반응온도, $O_2/CH_4$ 몰비, $CH_4$ 공급속도, $N_2$ 운반 가스 흐름속도 등의 변화에 따라 실험을 수행하였다. 막반응기의 메탄 전환율은 알루미나에 담지된 니켈 촉매를 사용하는 반응조건하에서 $350{\sim}730^{\circ}C$의 반응온도에 따라 증가하는 경향을 보였으며, 특히 $730^{\circ}C$와 $O_2/CH_4$ 몰비 0.5에서 메탄 전환율과 CO 선택도가 가장 높았다. 막반응기의 메탄 전환율은 전통적인 관형반응기와 비교한 결과 반응조건에 따라 10~40% 정도 높았다.

• Korean Membrane Journal
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• 제5권1호
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• pp.68-74
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• 2003

Methane steam reforming (MSR) reaction for hydrogen production was studied in a membrane reactor (MR) using two tubular membranes, one Pd-based and one of porous alumina. A higher methane conversion than the thermodynamic equilibrium for a traditional reactor (TR) was achieved using MRs. The experimental temperature range was 350-500$^{\circ}C$; no sweep-gas was employed during reaction tests to avoid its back-permeation through the membrane and the steam/methane molar feed ratio (m) varied in the range 3.5-5.9. The best results (the difference between the MR conversion and the thermodynamic equilibrium was of about 7%) were achieved with the alumina membrane, working with the highest steam/methane ratio and at 450$^{\circ}C$. Silica membranes prepared at KRICT laboratories were characterized with permeation tests on single gases (N$_2$, H$_2$ and CH$_4$). These membranes are suited for H$_2$ separation at high temperature.

• 설비공학논문집
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• 제28권2호
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• pp.75-80
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• 2016

There are three types of dehumidification systems : refrigeration dehumidification method, desiccant dehumidification method and hybrid dehumidification method. The first method involves removing moisture by condensation below the dew point, the second method involves absorption by a desiccant material and the last is an integration method. However, the refrigeration dehumidification system consumes too much power and controlling the humidity ratio is difficult. The desiccant dehumidification system uses less power but it has problems of environmental pollution. The hybrid dehumidification system has the disadvantage of a high initial cost. On the other hand, the energy consumption of the membrane based dehumidification system is lower than for the refrigeration dehumidification system. Also, it is an environmentally friendly technology. In this study, the performance parameters are evaluated for the dehumidification system using a hollow fiber membrane. Available area, duct side dry-bulb temperature, sweep gas flux (flow rate) and LMPD (Log Mean Pressure Difference) were used as the performance parameters.

• 한국가스학회지
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• 제24권3호
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• pp.47-53
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• 2020

본 연구에서는 엔진발전기에 사용되는 냉각팬 형상을 단방향 유동-구조 연성해석을 통하여 냉각팬의 성능과 내구성을 분석하여 최적화 설계자료를 제시하였다. 이를 위해, 냉각팬 내부 유동장에 대해 정상상태 해석을 수행하고, 정상상태 계산 결과를 구조해석을 위한 입력 데이터로 사용함으로써 내구성을 분석하였다. 냉각팬의 블레이드와 스윕 각도를 변경하는 작업을 통해 6가지 type을 모델링하여 유동해석을 진행하였으며, 질량유량과 토오크의 비는 A type이 가장 우수하지만, 질량유량이 상대적으로 큰 B type이 유동성능이 가장 좋은 냉각팬의 형상이라고 판단하였다. 유동해석을 통해 선정된 B type의 블레이드 두께를 4가지로 설정하여 구조해석을 검토한 결과, 피로안전계수까지 고려하였을 때 B Type-3가 가장 적합하다고 판단되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.254.2-254.2
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• 2014

The Transmission Fourier Transform Infrared spectroscopy (FTIR) of SiOx charge storage layer with the richest silicon content showed an assignment at peaks around 2000~2300 cm-1. It indicated that the existence of many silicon phases and defect sources in the matrix of the SiOx films. The total hysteresis width is the sum of the flat band voltage shift (${\Delta}VFB$) due to electron and hole charging. At the range voltage sweep of ${\pm}15V$, the ${\Delta}VFB$ values increase of 0.57 V, 1.71 V, and 13.56 V with 1/2, 2/1, and 6/1 samples, respectively. When we increase the gas ratio of SiH4/N2O, a lot of defects appeared in charge storage layer, more electrons and holes are charged and the memory window also increases. The best retention are obtained at sample with the ratio SiH4/N2O=6/1 with 82.31% (3.49V) after 103s and 70.75% after 10 years. The high charge storage in 6/1 device could arise from the large amount of silicon phases and defect sources in the storage material with SiOx material. Therefore, in the programming/erasing (P/E) process, the Si-rich SiOx charge-trapping layer with SiH4/N2O gas flow ratio=6/1 easily grasps electrons and holds them, and hence, increases the P/E speed and the memory window. This is very useful for a trapping layer, especially in the low-voltage operation of non-volatile memory devices.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.941-950
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• 2013

The Korean Nuclear-Hydrogen Technology Development (NHTD) Plan will be performing irradiation testing of coated particle fuel at HANARO to support the development of VHTR in Korea. This testing will be carried out to demonstrate and qualify TRISO-coated particle fuel for use in VHTR. The testing will be irradiated in an inert gas atmosphere without on-line temperature monitoring and control combined with on-line fission product monitoring of the sweep gas. The irradiation device contains two test rods, one has nine fuel compacts and the other five compacts and eight graphite specimens. Each compact contains about 260 TRISO-coated particles. The irradiation device is being loaded and irradiated into the OR5 hole of the in HANARO core from August 2013. The device will be operated for about 150 effective full-power days at a peak temperature of about $1030^{\circ}C$ in BOC (Beginning of Cycle) during irradiation testing. After a peak burn-up of about 4 atomic percentage and a peak fast neutron fluence of about $1.7{\times}10^{21}\;n/cm^2$, PIE (Post-Irradiation Examination) of the irradiated coated particle fuel will be performed at IMEF (Irradiated Material Examination Facility). This paper reviews the design of test rod and irradiation device for coated particle fuel, and discusses the technical results for irradiation testing at HANARO.