• 임산에너지
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• 제17권1호
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• pp.56-70
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• 1998

This study was carried out to investigate the structural characteristics of kraft lignin and the wood degrading characteristics, the productivity of ligninolytic enzymes and the enzymatic degradation of kraft lignin by white-rot fungi. To purify kraft lignin, precipitation of kraft pulping black liquors of pitch pine meal was done by titration with lN $H_{2}SO_{4}$ reaching to pH 2, and isolation of the precipitates done by centrifugation. The isolated precipitates from pitch pine were redissloved in lN NaOH, reprecipitated by titration with lN $H_{2}SO_{4}$, washed with deionized water, and kept ofr analysis after freeze drying. Fractionation of the precipitates in solution by successive extraction with $CH_{2}Cl_{2}$ and MeOH, and the fractionates were named SwKL, SwKL I, SwKL II, and SwKL III for pitch pine kraft lignin. The more molecular weights of kraft lignin increased, the less phenolic hydroxyl groups and the more aliphatic hydroxyl groups. Because as the molecular weights increased, the ratio of etherified guaiayl/syringyl(G/S ratio) and the percentage were increased. The spectra obtained by 13C NMR and FTIR assigned by comparing the chemical shifts of various signals with shifts of signals from autherized ones reported. The optimal growth temperature and pH of white-rot fungi in medium were $28^{\circ}C$ and 4.5-5.0, respectively. Especially, in temperature and pH range, and mycelial growth, the best white-rot fungus selected was Phanerochaete chrysosporium for biodegradation. For the degradation pathways, the ligninolytic fungus jcultivated with stationary culture using medium of 1% kraft lignin as a substrate for 3 weeks at $28^{\circ}C$. The weight loss of pitch pine kraft lignin was 15.8%. The degraded products extracted successively methoanol, 90% dioxane and diethyl ether. The ether solubles were analyzed by HPLC. Kraft lignin degradation was initiated in $\beta$-O-4 bonds of lignin by the laccase from Phanerochaete chrysosporium and the degraded compounds were produced from the cleavage of $C\alpha$-$C\beta$ linkages at the side chains by oxidation process. After $C\alpha$-$C\beta$ cleavage, $C\alpha$-Carbon was oxidized and changed into aldehyde and acidic compounds such as syringic acid, syringic aldehyde and vanilline. And the other compound as quinonemethide, coumarin, was analyzed. The structural characteristics of kraft lignin were composed of guaiacyl group substituted functional OHs, methoxyl, and carbonyl at C-3, -4, and -5 and these groups were combinated with $\alpha$ aryl ether, $\beta$ aryl ether and biphenyl. Kraft lignin degradation pathways by Phanerochaete chrysosporium were initially accomplished cleavage of $C\alpha$-$C\beta$ linkages and $C\alpha$ oxidation at the propyl side chains and finally cleavage of aromatic ring and oxidation of OHs.

• 분석과학
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• 제29권1호
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• pp.49-55
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• 2016

케톤체는 생체 에너지 생산과정이 탄수화물보다는 지방산의 의존도가 높을 때 생성되며, 과도한 분비는 당뇨병성 케토시스나 선천성 유전성 대사이상질환을 의심할 수 있는 근거가 된다. 따라서 이의 신속 정확한 분석법의 개발이 필요하다. 본 연구에서는 혈장을 제단백한 후 hydroxylamine을 가하여 60 ℃에서 30 분간 반응시켜 oximation 후 BSTFA를 가한 후 trimethylsilylation 유도체화하여 혈장 중에서 케톤체를 신속하게 정량할 수 있는 GC-MS/SIM 분석법을 개발하였다. 케톤체의 직선성의 범위는 0.001-250 μg/mL 이었고, 혈장에서의 검출한계는 0.1 pg 이었다. 직선성을 가지는 범위에서의 상관계수(R2)는 0.998-0.999이었고, 회수율은 1 μg/mL의 표준품을 첨가하였을 때 88.2-92.3 %, 10 μg/mL의 농도를 첨가하였을 때 89.5-94.8 % 였으며 RSD는 6.3-9.4 %였다. 이 분석법을 정상인과 케토시스 환자의 검체에 적용하여 벨리데이션 하였으며, 본 분석방법은 어린이나 성인의 당뇨성 케토시스나 여러 유전성대사질환 환자 중 케토시스를 보이는 환자의 혈장 중 β-hydroxybutyric acid/acetoacetic acid의 비를 계산하여 케톤체를 신속하고 효율적으로 임상검체 분석에 응용할 수 있음을 보여주었다.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.14-20
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• 2018

전기자동차는 가솔린 자동차와는 달리 배출가스가 없어 친환경 차량을 대표하지만, 장착된 축전지에 충전된 전기로 구동되기 때문에, 1회 충전으로 갈 수 있는 거리가 전지의 에너지 밀도에 의해 좌우된다. 따라서 높은 에너지 밀도를 갖는 리튬이온 전지가 전기자동차용 전지로 유력한 후보이다. 리튬이온 전지의 효율을 지배하는 중요한 구성품은 전극이므로 전극 제조공정은 리튬이온 전지 전체 생산 공정에서 중요한 역할을 한다. 특히 전극의 제조 공정 중 코팅 공정은 성능에 큰 영향을 미치는 매우 중요한 공정이다. 본 논문에서는 전극 제조에서 코팅 공법의 효율성 및 생산성 증대를 위한 혁신적인 공정을 제안하고, 장비 설계 방법 및 개발 결과에 대하여 기술하였다. 구체적으로, 극판 핵심 코팅 품질 25% Upgrade 기술, 제품 고출력/고용량화 에 따른 조립 마진 감소 대응 가능 기술, 그리고 제품 용량 품질 및 조립 공정 수율 향상 기술들에 대한 설계 절차 및 개발방법을 제시하였다. 결과로 리튬이온 배터리의 셀의 제품 수명 개선 효과를 확보 하였다. 기존의 코팅 공정과 비교할 때 양극 용량 유지 위해 Target Loading Level 유지, 산포를 향상시켰다(${\pm}0.4{\rightarrow}{\pm}0.3mg/cm^2r$감소).

• Journal of Pharmaceutical Investigation
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• 제27권4호
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• pp.253-263
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• 1997

To investigate the interaction of omeprazole (OMP) and meglumine (MEG), a complex was prepared by freeze-drying method in ammoniacal aqueous medium at room temperature and subjected to IR, DSC, and 1H NMR analysis. In addition, the stability of the complex was tested by accelerated stability analysis, and the dissolution rate of both powder and enteric coated was determined pellet by paddle method. The results are as follows; i) IR, DSC, and $^{1}H$ NMR studies indicate the formation of inclusion complex between OMP and MEG probably by electrostatic forces as $[OMP]\;[MEGH]^+$ form in a stoichiometric ratio (1:1) of OMP : MEG. ii) The dissolution rate of enteric coated OMP-MEG complex pellet in simulated enteric fluid was 90.6% in 10 minutes, which may satisfy the requirement for the regulation of dissolution. iii) OMP-MEG complex were decomposed according to pseudo 1st order kinetics: while the decomposition of OMP showed a rate constant $(k_{25^{\circ}C})$ of $5.13{\times}10^{-4}{\cdot}\;day^{-1}$, a half-life$(t_{1/2})$ of 1,350 days, a shelf-life$(T_{90%})$ 205 days and an activation energy of 23.53 kcal/mole. OMP-MEG complex inhibited a rate $(k_{25})$ of $2.92{\times}10^{-4}{\cdot}\;day^{-1}$, a half-life$(t_{1/2})$ of 2,373 days, a shelf-life $(T_{90%})$ of 306 days and an activation energy of 20.18 kcal/mole. iv) OMP was stabilized markedly by the formation of OMP-MEG complex between OMP and MEG, and the humidity increased the stability of OMP-MEG complex by decreasing the decomposition rate$(k_{50^{\circ}C})$ from $1.27{\times}10^{-2}{\cdot}\;day^{-1}$ at 31% R.H. to $2.54{\times}10^{-2}{\cdot}\;day^{-1}$ at 90% R.H.

• Korean Chemical Engineering Research
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• 제49권6호
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• pp.804-809
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• 2011

$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ 조성의 관형 분리막을 압출 성형 방법으로 제조하였다. 압출성형 직후 분리막의 TGA 분석결과 3단계의 무게감소로 첨가제와 탄산염이 분해되었고, 건조 수축율은 68 h 경과 후 변화가 없었으며 외경이 큰 분리막에서 높게 나타났다. 소결 후 분리막의 XRD 및 SEM 분석결과, 분리막은 단일상의 페롭스카이트 구조를 갖는 치밀한 막을 보였고, EDS 분석을 통해 $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$와 유사한 성분함량을 가짐을 확인하였다. 두께 0.95 mm $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ 관형 분리막의 압환강도(radial crushing strength)는 5.7 kgf/$mm^2$이였으며, $950^{\circ}C$에서 산소투과량은 146.85 mL/min($Jo_2$=2.33 mL/$min{\cdot}cm^2$)를 나타냈었다. 투과 측의 진공펌프 사용이 쓸개 가스를 활용한 것보다 산소 투과량 증진에 효과가 있음을 알 수 있었다.

• 청정기술
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• 제18권4호
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• pp.432-439
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• 2012

백금(Pt)과 루테늄(Ru)의 조성비가 일산화탄소(CO) 산화반응에 미치는 영향을 조사하고자 탄소를 지지체(support)로 사용한 20 wt% 백금과 백금-루테늄 시리즈 촉매(Pt : Ru = 7 : 3, 5 : 5, 3 : 7)를 콜로이드 방법(colloidal method)으로 합성하였다. 다양한 물리 화학적 분석장비인 투과전자현미경(transmission electron microscopy, TEM)과 X-선 회절(X-ray diffraction, XRD), 에너지 분산형 X-선 분석기(energy dispersive X-ray spectroscopy, EDS)를 이용하여 구조 화학적 특성을 분석하고, X-선 광전자 분광법(X-ray photoelectron spectroscopy, XPS)을 통해 전자적 특성 변화를 확인하였다. 더불어 일산화탄소 벗김 전압전류실험(CO stripping voltammetry)을 이용하여 전기화학적 거동을 분석하였다. 합성된 촉매들 중 $Pt_5Ru_5/C$가 가장 낮은 개시 전위(vs. Ag/AgCl)와 가장 큰 일산화탄소의 전기화학적 활성화 표면적(CO EAS) 값을 나타냈으며 이를 통해 $Pt_5Ru_5/C$이 일산화탄소의 전기화학적 산화반응에 있어 가장 효과적인 촉매임을 확인하였다. $Pt_5Ru_5/C$의 격자상수 변화를 통한 구조적 특성변화 및 백금 d-밴드의 페르미 레벨 변화를 통한 전자적 특성변화 그리고 이작용기(bifunctional)의 효과가 일산화탄소의 전기화학적 산화반응에 대한 활성을 증진시켰다고 사료된다.

• 청정기술
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• 제24권1호
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• pp.1-8
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• 2018

환경 오염에 대한 사회적 요구가 증가하고 염색 공정 폐수 배출에 대한 규제가 강화되면서 기존 수계 염색에서 발생하는 다량의 폐수와 에너지 낭비를 근본적으로 해결하기 위한 대안으로 초임계 염색 공정이 주목 받고 있다. 초임계 염색 공정에서는 기존 수계 염색에서 염색 용매인 물 대신 이산화탄소만을 사용하기 때문에 발생하는 폐수가 전혀 없고 미 고착 염료와 이산화탄소를 재사용 할 수 있다는 점에서 친환경적이다. 또한 염색 이후 추가적인 건조공정 없이 건조된 섬유를 얻을 수 있어 에너지 소비를 줄일 수 있다. 본 논문에서는 먼저 초임계 염색 공정의 발전배경과 현재 우리나라에서의 연구를 정리하였으며 초임계 염색의 원리와 기존 수계염색과의 장단점을 비교 설명하였다. 원리를 보다 자세히 설명하기 위해 초임계 이산화탄소와 염료 사이의 용해도를 비롯해 초임계 이산화탄소와 섬유에서 염료의 분배계수 및 물질전달 연구를 정리하였고, 현재 연구의 한계점과 연구방향을 제시하였다. 또한 초임계 염색 설비 내에서의 염료의 동적거동에 대하여 토의하였으며 전 세계적으로 개발된 초임계 염색 설비를 정리하였다. 마지막으로 현재 초임계 염색 공정의 최적화와 폴리에스터를 제외한 다른 합성섬유와 천연섬유에 적용하기 위해 필요한 연구개발 방향을 제시하였다.

• 한국수소및신에너지학회논문집
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• 제24권1호
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• pp.44-49
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• 2013

Hydrogen penetration into a metal leads to damages and mechanical degradations and its content measurement is of importance. For a precise measurement, a sample preparation procedure must be optimized through a series of studies on sample washing and drying. In this study, two-step washing with organic solvents and thermal soaking in inert gas were tried with a rod-shaped, API X65 steel sample. The samples were machined from a steel plate and then washed in acetone and etyl-alcohol for 5 minute each and dried with compressed air. After then, the samples were thermally soaked in a home-made nitrogen gas chamber during 10 minute at different heat gun temperatures from 100 to $400^{\circ}C$ and corresponding temperature range in the soaking chamber was from 77 to $266^{\circ}C$ according to the temperature calibration. Hydrogen residue in the samples was measured with a hot extraction system after each soaking step; hydrogen residue of $0.70{\pm}0.12$ wppm after the thermal soaking at $77^{\circ}C$ decayed with increase of the soaking temperature. By adopting the heat transfer model, decay behavior of the hydrogen residue was fitted into an exponential decay function of the soaking temperature. Saturated value or lower bound of the hydrogen residue was 0.36 wppm and chamber temperature required to lower the hydrogen residue about 95% of the lower bound was $360^{\circ}C$. Furthermore, a thermal desorption spectroscopy was done for the fully soaked samples at $360^{\circ}C$. Weak hydrogen peak was observed for whole temperature range and it means that hydrogen-related contaminants of the sample surface are steadily removed by heating. In addition, a broad peak found around $400^{\circ}C$ means that parts of the hydrogen residue are irreversibly trapped in the steel microstructure.

• 한국지반공학회논문집
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• 제24권1호
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• pp.37-49
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• 2008

지열 냉난방 시스템은 친환경적이며 비고갈성인 지열 에너지를 이용함으로서 에너지 자원이 부족한 우리나라에 유용한 대체 에너지 시스템이다. 본 연구에서는 지중 열교환기의 뒤채움재로 사용되는 그라우트 재료의 열전달 및 점도 특성을 파악하고자, 국내 시공 현장에서 사용 중인 벤토나이트계 그라우트 9종과 충남 보령의 해성점토, 그리고 미국 등 선진국에서 사용 중인 시멘트계 그라우트를 선택하여 열전도도 실험과 점도실험을 수행하였다. 벤토나이트계 그라우트는 벤토나이트의 무게비가 증가 하거나 첨가제(천연규사)의 비율이 증가 할 때 열전도도와 점도가 증가하는 경향이 나타났다. 또한, 첨가제 사용 시 그라우트의 점도가 낮을 경우 그라우트와 첨가제의 재료분리 현상이 나타났다. 해성점토에 대한 실험에서는 해성점토가 벤토나이트에 비해 팽윤성이 낮아 그라우트 재료로는 부적합 하다는 결론을 내렸다. 시멘트계 그라우트의 열전도도 실험에서 습윤 상태의 시멘트계 그라우트가 벤토나이트계 그라우트 보다 높은 열전도도를 가지는 것으로 나타났으며 건조 상태로 변할 때 벤토나이트계에 비해 열전도도 감소폭이 작은 것으로 나타났다. 본 연구를 통해 그라우트의 함수비 유지가 지중 열교환기의 열전달 효율에 중요한 역할을 하는 것을 알 수 있었다.

• 농업과학연구
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• 제14권1호
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• pp.98-133
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• 1987

The mechanical and rheological properties of agricultural materials are important for engineering design and analysis of their mechanical harvesting, handling, transporting and processing systems. Agricultural materials, which composed of structural members and fluids do not react in a purely elastic manner, and their response when subjected to stress and strain is a combination of elastic and viscous behavior so called viscoelastic behavior. Many researchers have conducted studies on the mechanical and rheological properties of the various agricultural products, but a few researcher has studied those properties of rice plant, and also those data are available only for foreign varieties of rice plant. This study are conducted to experimentally determine the mechanical and the rheological properties such as axial compressive strength, tensile strength, bending and shear strength, stress relaxation and creep behavior of rice stems, and grain detachment strength. The rheological models for the rice stem were developed from the test data. The shearing characteristics were examined at some different levels of portion, cross-sectional area, moisture content of rice stem and shearing angle. The results obtained from this study were summarized as follows 1. The mechanical properties of the stems of the J aponica types were greater than those of the Indica ${\times}$ Japonica hybrid in compression, tension, bendingand shearing. 2. The mean value of the compressive force was 80.5 N in the Japonica types and 55.5 N in the Indica ${\times}$ Japonica hybrid which was about 70 percent to that of the Japonica types, and then the value increased progressively at the lower portion of the stems generally. 3. The average tensile force was about 226.6 N in the Japonica types and 123.6 N in the Indica ${\times}$ Japonica hybrid which was about 55 percent to that of the Japonica types. 4. The bending moment was $0.19N{\cdot}m$ in the Japonica types and $0.13N{\cdot}m$ in the Indica ${\times}$ Japonica hybrid which was 68 percent to that of the Japonica types and the bending strength was 7.7 MPa in the Japonica types and 6.5 MPa in the Indica ${\times}$ Japonica hybrid respectively. 5. The shearing force was 141.1 N in Jinju, the Japonica type and 101.4 N in Taebaeg, the Indica ${\times}$ Japonica hybrid which was 72 percent to that of Jinju, and the shearing strength of Taebaeg was 63 percent to that of Jinju. 6. The shearing force and the shearing energy along the stem portion in Jinju increased progressively together at the lower portions, meanwhile in Taebaeg the shearing force showed the maximum value at the intermediate portion and the shearing energy was the greatest at the portion of 21 cm from the ground level, and also the shearing strength and the shearing energy per unit cross-sectional area of the stem were the greater values at the intermediate portion than at any other portions. 7. The shearing force and the shearing energy increased with increase of the cross-sectional area of the rice stem and with decrease of the shearing angie from $90^{\circ}$ to $50^{\circ}$. 8. The shearing forces showed the minimum values of 110 N at Jinju and of 60 N at Taebaeg, the shearing energy at the moisture content decreased about 15 percent point from initial moisture content showed value of 50 mJ in Jinju and of 30 mJ in Taebaeg, respectively. 9. The stress relaxation behavior could be described by the generalized Maxwell model and also the compression creep behavior by Burger's model, respectively in the rice stem. 10. With increase of loading rate, the stress relaxation intensity increased, meanwhile the relaxation time and residual stress decreased. 11. In the compression creep test, the logarithmic creep occured at the stress less than 2.0 MPa and the steady-state creep at the stress larger than 2.0 MPa. 12. The stress level had not a significant effect on the relaxation time, while the relaxation intensity and residual stress increased with increase of the stress level. 13. In the compression creep test of the rice stem, the instantaneous elastic modulus of Burger's model showed the range of 60 to 80 MPa and the viscosities of the free dashpot were very large numerical value which was well explained that the rice stem was viscoelastic material. 14. The tensile detachment forces were about 1.7 to 2.3 N in the Japonica types while about 1.0 to 1.3 N in Indica ${\times}$ Japonica hybrid corresponding to 58 percent of Japonica types, and the bending detachment forces were about 0.6 to 1.1 N corresponding to 30 to 50 percent of the tensile detachment forces, and the bending detachment of the Indica ${\times}$ Japonica hybrid was 0.1 to 0.3 N which was 7 to 21 percent of Japonica types. 15. The detachment force of the lower portion was little bigger than that of the upper portion in a penicle and was not significantly affected by the harvesting period from September 28 to October 20. 16. The tensile and bending detachment forces decreased with decrease of the moisture content from 23 to 13 percent (w.b.) by the natural drying, and the decreasing rate of detachment forces along the moisture content was the greater in the bending detachment force than the tensile detachment force.