• 한국식품영양과학회지
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• 제32권2호
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• pp.155-160
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• 2003

Monascus anka KCTC 6121을 이용하여 백미에 의한 고체 배양을 통한 실험균의 적색 색소의 생산을 위한 배양조건의 최적화에 관한 연구 결과는 다음과 같이 요약된다. 실험균주가 생산하는 적색색소 생산의 최적 배양조건은 초기 수분함량 25%, 2.5$\times$$10^{6}$/mL의 실험균주의 포자, 배양온도3$0^{\circ}C$, 배양습도 90%에서 배양 12일째가 가장 양호했다. 생산된 적 색 색소의 추출은 80% 에탄올에서 2일간 추출이 가장 양호했으며 2일 이후의 색소 추출은 색소 추출량에 거의 변화가 없음을 알 수 있었다. 실험균주로부터 추출한 색소의 빛에 대한 안정성은 반 직사광선에서 색소의 색상이 30일간 8% 미만으로 감소하여 햇빛에 대한 안정성은 비교적 높았다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3719-3726
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• 2012

Formation of Z-DNA, a left-handed double helix, from B-DNA, the canonical right-handed double helix, occurs during important biological processes such as gene expression and DNA transcription. Such B-Z transitions can also be induced by high salt concentration in vitro, but the changes in the relative stability of B-DNA and Z-DNA with salt concentration have not been fully explained despite numerous attempts. For example, electrostatic effects alone could not account for salt-induced B-Z transitions in previous studies. In this paper, we propose that the B-Z transition can be explained if counterion entropy is considered along with the electrostatic interactions. This can be achieved by conducting all-atom, explicit-solvent MD simulations followed by MM-PBSA and molecular DFT calculations. Our MD simulations show that counterions tend to bind at specific sites in B-DNA and Z-DNA, and that more ions cluster near Z-DNA than near B-DNA. Moreover, the difference in counterion ordering near B-DNA and Z-DNA is larger at a low salt concentration than at a high concentration. The results imply that the exclusion of counterions by Z-DNA-binding proteins may facilitate Z-DNA formation under physiological conditions.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.100-104
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• 2011

The structures of the conformers for 1,3-di-t-butyl-2,4-dinitro-tetramethoxysulfonylcalix[4]arene (1) and 1,2-di-t-butyl-3,4-dinitro-tetramethoxysulfonylcalix[4]arene (2) were optimized using DFT BLYP and mPW1PW91/6-31G(d,p) (hybrid HF-DF) calculation methods. We have analyzed the total electronic and Gibbs free energies and the differences between the various conformations (cone, partial-cone (PC), 1,2-alternate, and 1,3-alternate) of 1 and 2. For both compounds, the 1,3-alternate (1,3-A) conformers were calculated to be the most stable, which correlate very well with the experimental results. The orderings of the relative stability of 1 and 2 that resulted from the mPW1PW91/6-31G(d,p) calculations are the following: 1: 1,3-A (syn) > PC (syn) > PC (anti) > 1,2-A (anti) > CONE (syn); 2: 1,3-A (anti) > PC (anti) > PC (syn) > 1,2-A (anti) > 1,2-A (syn) > CONE (syn). The BLYP/6-31G(d) calculated IR spectra of the most stable 1,3-A conformers of 1 and 2 are compared.

• 천문학회보
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• 제38권1호
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• pp.46.2-46.2
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• 2013

The neutral component of the interstellar medium (ISM) is segregated into the cold neutral medium (CNM) and warm neutral medium (WNM) as a result of thermal instability. It was found that the CNM--WNM evaporation interface, across which the CNM undergoes thermal expansion, is linearly unstable to corrugational disturbances, in complete analogy with the Darrieus-Landau instability (DLI) in terrestrial flames. To explore dynamical consequences of the DLI in the ISM, we perform a linear stability analysis of the DLI including the effect of thermal conduction as well as nonlinear hydrodynamic simulations. We find that the DLI is suppressed at short length scales via heat transport. The linear growth time of the fastest growing mode is proportional to the square of the evaporation flow speed of the CNM relative to the interface and is typically >10 Myr. In the nonlinear stage, perturbations grow into cusp-like structure protruding toward the WNM, and soon reach a steady state where the evaporation rate is increased by a factor of 2 compared to the initial state. We demonstrate that the amplitude of the interface distortion and enhancement in evaporation rate are determined primarily by the density ratio between the CNM and WNM. Given quite a long growth time and highly subsonic velocities at saturation, the DLI is unlikely to play an important role in the ISM dynamics.

• BMB Reports
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• 제38권3호
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• pp.343-349
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• 2005

Gamma-glutamyltransferase (GGT, EC 2.3.2.2) which hydrolyzes glutathione (GSH), is required for the maintenance of normal intracellular GSH concentration. GGT is a membrane enzyme present in leukocytes and platelets. Its activity has also been observed in human neutrophils. In this study, GGT was purified from Triton X-100 solubilized neutrophils and its kinetic parameters were determined. For kinetic analyses of transpeptidation reaction, $\gamma$-glutamyl p-nitroanilide was used as the substrate and glycylglycine as the acceptor. Apparent $K_m$ values were determined as 1.8 mM for $\gamma$-glutamyl p-nitroanilide and 16.9 mM for glycylglycine. The optimum pH of GGT activity was 8.2 and the optimum temperature was $37^{\circ}C$. It had thermal stability with 58% relative activity at $56^{\circ}C$ for 30 min incubation. L-serine, in the presence of borate, was detected as the competetive inhibitor. Bromcresol green inhibited neutrophil GGT activity as a noncompetetive inhibitor. The neutrophils seem to contain only the isoenzyme that is present in platelets. We characterized the kinetic properties and compared the type of the isoenzyme of neutrophil GGT with platelet GGT via polyacrylamide gel electrophoresis (PAGE) under a standart set of conditions.

• Structural Engineering and Mechanics
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• 제56권5호
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• pp.871-897
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• 2015

This paper presents a novel method based on sensitivity of structural response for identifying both the system parameters and input excitation force of a bridge. This method, referred to as "Adjoint Variable Method", is a sensitivity-based finite element model updating method. The computational cost of sensitivity analyses is the main concern associated with damage detection by these methods. The main advantage of proposed method is inclusion of an analytical method to augment the accuracy and speed of the solution. The reliable performance of the method to precisely indentify the location and intensity of all types of predetermined single, multiple and random damages over the whole domain of moving vehicle speed is shown. A comparison study is also carried out to demonstrate the relative effectiveness and upgraded performance of the proposed method in comparison to the similar ordinary sensitivity analysis methods. Moreover, various sources of error including the effects of noise and primary errors on the numerical stability of the proposed method are discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2828-2833
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• 2008

Water management is one of many operating parameters, which influences the performance and stability of a proton exchange membrane fuel cell (PEMFC). Local humidity condition including liquid water saturation has profound impacts on the distributions of overpotentials, current density, and membrane water content. Computational fluid dynamics simulations were conducted to investigate the effect of the inlet humidity variation on the performance of a PEMFC of $9\;cm^2$ active cell area with serpentine flow fields. The results showed that the performance of the simulated PEMFC remained at an almost same level when the cathode inlet humidity was changed from 100% to 60%, while reaching its maximum at air humidity of 80%. However, further decrease in the cathode inlet humidity below 40% started to significantly deteriorate the performance of the PEMFC. The variations of overpotentials, membrane water content, etc. due to the change in the cathode inlet humidity were also discussed.

• 한국추진공학회지
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• 제2권3호
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• pp.62-69
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• 1998

Polycaprolactone (PCP)과 coupling agent로 silane 유도체를 polyethylene glycol(PEG)/cyclo-tetramethylene tetranitramine(HMX) 추진제에 첨가하였을 때 추진제의 기계적 특성 변화를 연구하였다. PEG의 일부를 Polycaprolactone(PCP)으로 대체 사용하면 추진제의 기계적 성질은 증가하였으며, PCP/HMX 추진제는 PEG/HMX보다 최대 인장 강도가 17%, 최대 응력하의 신율은 59% 증가하였다. 그러나 PCP함량이 증가할수록 수분에 대한 안정성은 저하됨을 $40^{\cire}C$의 온도와 90% 상대 습도 분위기에서 보관된 추진제의 경도 변화와 PEG/PCP바인더의 부피 팽윤 실험에 의해 알 수 있었다. 또한 PEG/PCP/HMX 추진제를 $60^{\cire}C$에서 가속 노화시키면 triethoxysilyl propionitrile(TESPN)과dinitrosalicylic acid((DNSA) 함량이 증가할수록 추진제의 경도가 감소하는 것으로 나타났다.

• Elastomers and Composites
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• 제45권3호
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• pp.156-164
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• 2010

열가소성 탄성체(TPE)는 사용 온도 범위에서 일반 열경화성 고무와 같은 고무 탄성을 지니면서 용융 가공이 가능한 친환경 소재로써 산업 전반에 걸쳐 활용도가 꾸준히 증가하고 있다. 폴리아미드계 TPE (TPAE)는 하드세그멘트가 엔지니어링 플라스틱인 폴리아미드로 이루어져 있고, 소프트 세그먼트가 유리전이온도가 낮은 폴리에테르로 이루어진 다중 블록 공중합체로써 우수한 기계적 물성, 내화학성, 내열성 및 가공성을 나타낸다. 이러한 폴리아미드계 TPE는 하드 세그먼트와 소프트 세그먼트의 구조 및 상대적 조성에 따라 탄성체에서부터 연질 폴리아미드까지의 광범위한 특성이 발현되며, 또한, 다양한 무기 입자와의 하이브리드화를 통한 기능성 소재로의 활용이 기대되는 소재이다. 본 보문에서는 이러한 TPAE를 합성 할 수 있는 중합 방법과 특성 및 응용 분야에 대해 정리하였다.

• 대한기계학회논문집
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• 제11권3호
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• pp.437-443
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• 1987

본 연구에서는 승차감을 향상시키기 위해 원전석의 진동을 고려한 평면 5자 유도 모델을 사용하여 확정적 노면과 무작위 노면에 대한 시간영역, 주파수영역 해석 과 이에 따른 최적설계를 수행하였다. 최적설계시 목적함수는 주파수영역에서의 운 전석의 가속도 PSD를 구하여 여진동력(absorbed power)을 계산한 다음, 이를 최소화하 면서 차체의 안정성을 제한조건으로 하였다. 또 최적설계의 결과인 운전석의 가속도 rms값과 ISO경계값을 비교하였다. 시간영역에서는 결과를 해당된 운전석의 최대절대 가속도 및 상대변위에 대한 한계치와 비교하였다. 한편으로는 실제 노면 형상을 컴 퓨터로 시뮬레이션하고, 속도에 따른 최적치들 중에서 전체최적치 결정법을 제시하였 다.