• Membrane Journal
• /
• v.32 no.3
• /
• pp.191-197
• /
• 2022

Ammonia nitrogen can be effectively recovered from livestock manure waste, etc. by using the gas permeable membrane technology. In this case, ammonia gas in the waste passes through the pores in one-side of membrane, impregnated in waste, and then reach the opposite side of the membrane. The permeated ammonia gas molecules are captured and recovered by acid (such as sulfuric acid) in the solution existing on the opposite side of the membrane. In order to improve ammonia nitrogen removals in the inlet part, high pH should be maintained in the feed waste including ammonia nitrogen to recover, which requires the cost of the chemical. To resolve this issue, previous studies tested various methods, for example, utilization of cheap calcium hydroxide or aeration together with inhibition of unwanted nitrification. The gas permeable membranes used for the recovery of ammonia nitrogen may be characterized, not only by proper heat and chemical resistance, but also by hydrophobicity, allowing selective ammonia gas permeation through the hydrophobic membrane pores. Future research should consider the relevant pilot or upscale processes using on-site wastes with various properties, and identify the optimal design/operation conditions as well as economic feasibility improvement plans.

• Membrane Journal
• /
• v.32 no.6
• /
• pp.475-485
• /
• 2022

The continuous excessive consumption of fossil fuels is causing global warming, climate, and environmental crisis. Accordingly, hydrogen energy attracts attention among alternative energies of fossil fuels, because it has the advantage of not emitting pollutants and not having resource restrictions. Therefore, various studies are being conducted on a water electrolysis system for producing hydrogen and a fuel cell system for producing electricity by using hydrogen energy as a fuel. In this study, 3D ionomer models were produced by reflecting the excessive water condition of an anion-conductive ionomer material, which is one of the core materials of water electrolysis systems and fuel cells. Finally, by analyzing the structural stability and performance of the ionomer under an excessively hydrated condition, we suggested a performance improvement factor in the design of an anion conductive ionomer, a key material for water electrolysis systems and fuel cells.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2008.11a
• /
• pp.603-606
• /
• 2008

최근 들어 분자생물학의 급속한 발전과 2001년 인간유전체사업의 완료로 인해 전세계적으로 엄청난 양의 유전정보가 공개되었다. 유전자 서열정보는 그 양이 방대하고 다양하기에 데이터베이스 구축 및 분석을 위하여 고성능 컴퓨터 및 정보기술 기법이 필요하다. 그래서 컴퓨터를 활용하여 생물학적 데이터를 수집, 관리, 저장, 평가, 분석하는 연구분야인 생명정보학(바이오인포매틱스)이라는 학문이 지속적으로 발전하고 있다. 이런 생명정보학 발전에 발맞추어 한국과학기술정보연구원(KISTI)에서는 정보기술을 기반으로 한 생명정보 인프라를 구축하여 생명과학 연구자들에게 제공하고 있다. 본 논문에서는 생명정보 데이터베이스중에서 연구자들이 가장 많이 이용하는 유전자 데이터베이스인 Genbank를 활용 및 분석하여 KISTI에서 운영하는 학술논문 제공 사이트인 NDSL(http://scholar.ndsl.kr)과 연계 가능한 서비스 모델을 개발하기 위하여 1) NCBI FTP 사이트에서 Genbank 데이터를 수집하고, 2) Genbank 텍스트 파일을 유전자 기본정보와 참고 데이터베이스로 재구축하며, 3) Genbank refrence 필드에서 논문 및 특허 정보 추출을 통한 새로운 테이블을 생성하여 NDSL과 연계 가능한 서비스 모델을 제안하였다.

• Korean Journal of Microbiology
• /
• v.36 no.4
• /
• pp.273-278
• /
• 2000

The aacCl, aacC2, aacC3, and aacC4 genes, which encode aminoglycoside acetyltransferase AAC(3)-I, AA(3)-II, AAC(3)-III, and AAC(3)-IV, respectively, and aerolysin genes in water samples from Juam lake were surveyed by polymerase chain reaction. Surface water was collected from January 1996 to December 1998, and then bacterial DNA was extracted from the water. Twelve samples were tested by PCR to servey the genes for aminoglycoside acetyltransferase and aerolysin in the lake water. The aacC2 gene was detected in 9 of 12 DNA samples. Among 9 samples showing aacC2 positive, 7 samples were associated with Tn3 sequence. However, none of the twelve samples amplified the expected DNA fragment for aacC1, aacC3, and aacC4 genes. PCR primer to detect the aerolysin gene was designed using the conserved region of the genes for aerolysin and hemolysin of Aeromonas spp. This primer set successfully amplified the expected 414 bp PCR product with the DNA samples from the lake water. The aerolysin gene was detected in 7 of 12 DNA samples. When Southern hybridization of the gel with probe was performed, the aerolysin gene was detected in 10 of 12 DNA samples. However, the seasonal fluctuation of these genes was not found.

• Korean Chemical Engineering Research
• /
• v.50 no.3
• /
• pp.527-534
• /
• 2012

The adsorption dynamics of activated carbon (AC) and carbon molecular sieve (CMS) beds were studied to recover ethylene from FCC fuel gas. In this study, the FCC fuel gas used consisted of six-component mixture ($CH_4/C_2H_4/C_2H_6/C_3H_6/N_2/H_2$,32:15:14:2:12:25 vol.%). And the breakthrough experiments of adsorption and desorption were carried out. The breakthrough sequence in the AC bed was $H_2$ < $N_2$ < $CH_4$ < $C_2H_4$ < $C_2H_6$ while the sequence in the CMS bed was $H_2$ < $CH_4$ < $N_2$ < $C_2H_6$ < $C_2H_4$. The separation performance of the CMS bed during the adsorption step was lower than that of the AC bed. However, due to the characteristics of kinetic separation, the CMS bed could remove $CH_4/N_2$ as well asthe molecules that are larger than $C_2H_6$, which was not easy to be done by the AC bed. Since it was hard to regenerate the adsorption bed by simple depressurization, vacuum regeneration should be adopted. As a result, the pressure vacuum swing adsorption (PVSA) process, consisting of CMS pretreatment process and AC main process, was suggested to recover ethylene efficiently.

• Polymer(Korea)
• /
• v.29 no.5
• /
• pp.451-456
• /
• 2005

In the field of designing of nano-fillers of polyimide nanocomposites, the two strategic points are the heat-resistance and compatibility with polyimide, a matrix polymer. In this study, we designed oligo(amic acid) having alkyl side chains and terminal amine groups to satisfy previous requirements and studied the modification of surface of layered silicates. Oligo(amic acid)s were prepared by the reaction of diamine monomers and PMDA and their molecular weight was controlled in about 2000g/mol. After that, acidification and ion exchange reaction led to the high-temperature organophilic layered silicate (OLS). XRD pauerns of OLS showed the more increased gallery spacing by $4{\AA}$ than that of the pristine layered silicate and the initial decomposition temperatures of OLS were in above $280^{\circ}C$. The polyimide nanocomposite films based on heat resistant OLS showed that the OLSs were well dispersed through the matrix and their CTEs showed a decrease of $26\%$ compared with pristine polyimide films.

• Korean Journal of Food Science and Technology
• /
• v.50 no.4
• /
• pp.420-429
• /
• 2018

Skin ageing is associated with compromised performance of its fundamental barrier functions, with undesirable changes in appearance. Since this may introduce a detrimental impact on the quality of life, significant effort to discover effective ingredients against ageing is being invested. Recently, collagen hydrolysates containing tripeptides such as GlyPro-Hyp (GPH) have been developed with anticipation of improved effects compared to that of existing collagen hydrolysate-products. To evaluate the cutaneous hydration effect of collagen tripeptides (CTP), meaningful biomarkers in human dermal fibroblasts (HDF) and NC/Nga Tnd mice were analyzed in this study. Increased levels of ceramide kinase, hyaluronic acid, collagen 1A, and hyaluronan synthase-2 (HAS2), and decreased levels of hyaluronidase-1 (HYAL1) and CD44 in HDF cells were demonstrated. Furthermore, significant reduction of transepidermal water loss (TEWL), scratching behavior, HYAL1, $TNF-{\alpha}$ and IL-6 and increased water content and HAS2 were verified by in vivo tests. These results strongly suggest the potential of CTP as a skin hydration agent.

• The Korean Journal of Pesticide Science
• /
• v.14 no.4
• /
• pp.319-325
• /
• 2010

To understand the influences of the substituents ($R_1{\sim}R_4$) on insecticidal activity of N'-phenyl-N-methylformamidine analogues (1~22) against two spotted spider mite (Tetranychus urticae), comparative molecular field analysis (CoMFA) model and comparative molecular similarity indices analysis (CoMSIA) model as three dimensional quantitative structure-activity relationships (3D-QSARs) model were derived and discussed quantitatively. From the results, the correlativity and predictability ($r^2{_{cv.}}=0.575$ and $r^2{_{ncv.}}=0.945$) of the CoMFA 1 model were higher than those of the rest models. The the CoMFA 1 and CoMSIA 1 model with the sensitivity of the perturbation and the prediction produced ($d_q{^{2'}}/dr^2{_{yy}}=1.071{\sim}1.146$ & $q^2=0.545{\sim}0.626$) by a progressive scrambling analysis were not dependent on chance correlation. The insecticidal activities from the optimized CoMFA 1 model were depend upon the steric field (62.5%), electrostatic field (28.9%), and hydrophobic field (8.6%) of N'-phenyl-N-methylformamidine analogues. Therefore, the inhibitory activities with optimized CoMFA 1 model were dependent upon steric factor. From the contour maps of the optimized models, it is predicted that the structural distinctions that contribute to the insecticidal activity will be able to applied new potent insecticides design.

• Clean Technology
• /
• v.30 no.2
• /
• pp.123-133
• /
• 2024

Zeolite template carbon (ZTC) was synthesized as an adsorbent to remove low-concentration CH₄ from the atmosphere. The synthesis of ZTC was performed using CH₄ and C₂H₂ as carbon precursors and their impact on adsorption was investigated. ZTC was also synthesized using Y zeolite ion-exchanged with CaCl₂ and LiCl as templates to investigate the effect of using metals in ion exchange. The comparison of the carbon precursors revealed that C₂H₂ had a higher carbon yield than CH₄. The synthesized ZTC exhibited developed micropores due to carbon deposition deep inside the micropores of the zeolite template. The kinetic diameter of C₂H₂ (0.33 nm) is smaller than that of CH₄ (0.38 nm), which allowed for its deposition. The study compared metal precursors used for ion exchange and confirmed that the CaCl₂-based ZTC developed more micropores compared to the LiCl-based ZTC. The ion-exchanged Ca inhibited pore blocking by the carbon precursor, allowing it to enter the pores. The ability of synthesized ZTC to adsorb N₂ and CH₄ at 298 K was investigated. The results showed that CH₄ had a higher overall adsorption amount than N₂. The sample synthesized using C₂H₂ and CaY exhibited the highest N₂ and CH₄ adsorption capacity. However, the sample synthesized with CH₄ had the highest CH₄/N₂ gas uptake ratio, which is a crucial factor in designing an adsorption process. The observed difference was likely caused by the underdevelopment of ultrafine pores that are associated with N₂ adsorption. This resulted in a reduction of N₂ adsorption, leading to an increase in CH₄/N₂ separation.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.170.1-170.1
• /
• 2015

안티모니 (Sb)를 기반으로 한 제2형 초격자 (Type II superlattice, T2SL)구조 적외선 검출기 연구는 2000년대 들어 Sb 계열의 화합물 반도체 성장 기술이 발전함에 따라 HgCdTe (MCT), InSb, 양자우물 적외선 검출기 (QWIP)를 대체할 수 있는 고성능의 양자형 적외선 검출 소재로 부상하였으며, 현재 전 세계적으로 활발한 연구가 진행되고 있다. 특히, 기존의 양자형 적외선 검출소자에 비해 전자의 유효질량이 상대적으로 커서 밴드 간의 투과전류가 줄어들 뿐만 아니라, 전자와 정공이 서로 다른 물질 영역에 분포하여 Auger 재결합률을 효과적으로 줄일 수 있어 상온 동작이 가능한 소재로 주목을 받고 있다. 또한, T2SL 구조는 초격자를 구성하는 물질의 두께나 조성 변화를 통한 밴드갭 변조가 용이하여 단파장에서 장파장 적외선에 이르는 광범위한 파장 대역에서 동작이 가능할 뿐만 아니라 구조적 변화를 통해 이중 대역을 동시에 검출 할 수 있는 차세대 적외선 열영상 소자로 알려져 있다. 본 연구에서는 분자선 에피택시(MBE)법을 이용하여 300 주기의 InAs/GaSb (10/10 ML) 제2형 초격자 구조를 성장하여 적외선 검출소자를 제작하였다. 제2형 초격자 구조를 구성하는 물질계에 p-type dopant인 Be을 이용하여 각각 도핑 농도가 다른 시료를 성장하였다. 이때 p-type 도핑 농도는 각각 $1/5/10{\times}10^{15}cm^{-3}$로 변화를 주었다. 성장된 시료의 구조적 특성 분석을 위해 고분해능 X선 회절 (High resolution X-ray diffraction, HRXRD)법을 이용하였으며, 초격자 한 주기의 두께가 6.2~6.4 nm 로 설계된 구조와 동일하게 성장됨을 확인 하였으며, 1차 위성피크의 반치폭은 30~80 arcsec로 우수한 결정성을 가짐을 확인하였다. 적외선 검출을 위한 $410{\times}410{\mu}m^2$ 크기의 단위 소자 공정을 진행하였으며 이때 적외선의 전면 입사를 위해 소자 위에 $300{\mu}m$의 윈도우 창을 제작하였다. 단위 소자의 측벽에는 표면 누설 전류가 흐르는데 이를 방지하기 위해서 표면보호막을 증착하였다. 적외선 검출 소자의 전기적 특성 평가를 위해 각각의 시료의 암전류 (dark current)와 파장별 반응 (spectral response)을 온도별로 측정하여 비교 및 분석하였다.