• 대한수학회보
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• 제37권1호
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• pp.135-152
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• 2000

For a linear operator Q from $R^{d}\; into\; R^{d},\; {\alpha}\;>0\; and\ 0-semi-stability and the operater semi-stability of probability measures on $R^{d}$ are defined. Characterization of $(Q,b,{\alpha})$-semi-stable Gaussian distribution is obtained and the relationship between the class of $(Q,b,{\alpha})$-semi-stable non-Gaussian distributions and that of operator semistable distributions is discussed.

• 한국지반공학회지:지반
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• 제14권2호
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• pp.55-66
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• 1998

본 논문의 목적은 불연속면의 공학적 특성, 사면형상과 하중조건 등을 고려한 암반사면 전도 파괴에 대한 안정해석방법을 개발하고 적용하는테 있다. 암반사면의 전도파괴에 대한 안정은 경사각 $\alpha_s$ 와 H/t비에 주된 영향을 받는다. 설계적용을 위하여 매개변수에 따른 My띠와 $\alpha$서 함수로 표현되는 암반사면 전도파괴에 대한 안정도표를 작성하였다. 안정도표에서 $\alpha_s$와 Hy띠가 작아질수록 안정성이 증가하는 경향을 보인다. 안정도표에서 안정영역은 간극수압변화에 따라 가장 크게 감소한다. 파괴영역의 변화는 지진력과 단계각에 가장 민감하다.

• Korean Journal of Mathematics
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• 제8권2호
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• pp.111-119
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• 2000

For a linear operator Q from $R^d$ into $R^d$. ${\alpha}$ > 0 and 0 < $b$ < 1, the Gaussian (Q, $b$, ${\alpha}$)-semi-stability of probability measures on $R^d$ is investigated.

• 한국분말재료학회지
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• 제10권2호
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• pp.118-122
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• 2003

Alpha-SiAlON ceramics having various compositions and modifying cations were investigated with respect to their phase stability, transformation kinetics. and resulting microstructures. Each composition was heat treated at 150$0^{\circ}C$ for 1h and measured the $\alpha$-SiAlON transformation. The phase-boundary composition in the single-phase $\alpha$-SiAlON region showed sluggish transformation from $\alpha$-$Si_3N_4$ to $\alpha$-SiAlON compared to the phase-center composition in the diagram. Using the different rare earth modifying cations, dependence of transformation kinetics on the phase stability in a fixed composition was also explained. By changing size of the stable u-phase region with exchanging cations, systematic change in transformation was observed. Transformation rate of $\alpha$-SiAlON at low temperature has an important role on controlling the final microstructure. Less transformation gives more chances to develop elongated grain in the microstructure.

• Korean Chemical Engineering Research
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• 제57권3호
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• pp.368-371
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• 2019

Using first principles calculations we investigated the thermomechanical stability of spent nuclear fuels (SNF), especially how mechanical properties of $UO_2$, such as, bulk, shear and Young's moduli and Poisson's ratio vary through alpha-decay of U into Th with generation of He gas. Our results indicate that substitution of U by Th through alpha decay ($U_{1-x}Th_xO_2$) does not significantly affect the stability of the grain in a fuel matrix. In addition, we studied the transport properties of He in and boundaries of the $U_{1-x}Th_xO_2$ grain. Helium preferentially resides at the grain boundaries through diffusion. Our study can contribute to substantial reduction of environmentally risk and enhancement of our sustainability by safe control of radioactive materials.

• 한국식품과학회지
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• 제20권4호
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• pp.563-568
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• 1988

몇가지 산화방지제와 상승제를 첨가하여 가열한 팜유와 우지에 대한 산화방지 효과를 AOM시험에 의하여 비교 연구하였다. 팜유에 0.02% TBHQ를 첨가하였을때 같은 농도의 다른 산화방지제를 첨가하였을 때 보다 AOM 안정성이 가장 우수하였다. 우지에 0.02% TBHQ를 첨가하였을 때는 같은 농도의 BHA와 BHT 혼합제와 $DL-{\alpha}-T$을 첨가한 것 보다 AOM 안정성이 증가하였으나 같은 농도의 ${\delta}-T$와 MT을 첨가한것 보다 증가하지 않았다. 팜유와우지에 $DL-{\alpha}-T$을첨가하였을 때는 BHA와 BHT 혼합제를 첨가한 것 보다 AOM안정성이 증가하지 않았다. 그러나 팜유와 우지에 ${\delta}-T$와 MT를 첨가하였을 때는 $DL-{\alpha}-T$를 첨가하였을때 보다 AOM 안정성이 증가되었고 ${\delta}-T$와 MT 간에는 큰 차이가 없었다. $DL-{\alpha}-T$및 ${\delta}-T$에 대한 구연산의 상승효과는 팜유보다 우지에서, $DL-{\alpha}-T$에 대한 AP의 상승효과는 우지보다 팜유에서, ${\delta}-T$에 대한 AP의 상승효과는 팜유보다 우지에서 각각 더 효과적이었다. 가열중 tocopherol류의 손실량은 우지보다 팜유에서 더 적었다.

• 한국식품영양학회지
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• 제12권3호
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• pp.265-270
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• 1999

The stabilization of Aspergillus sp. $\alpha$-amylase was attained by modification with periodate-oxidized sol-uble starch. The pH stability of modified enzyme was increased at pH 3~4 and 9~11 in the presence of $\alpha$-cyclodextrin($\alpha$-CD) compared with that of native enzyme. Thermal stability of the modified enzyme was increased. After treatment at 6$0^{\circ}C$ for 30min the activity remained 20% for the enzyme modified at pH 9.7 in the presence of $\alpha$-CD and tested in the presence of $\alpha$-CD 10% for the enzyme modified at pH 9.7 in the presence of $\alpha$-CD 0% for the native enzyme. The native enzyme and modified enzyme showed one peak in HPLC. The substrate specificity of the modified enzyme was not changed in HPLC analysis of reaction product.

• KSBB Journal
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• 제6권1호
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• pp.9-14
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• 1991

We studied the production and excretion of alpha-interferon in recombinant Escherichia coli harboring plasmid pIF-III-B, which carries alpha-interferon gene under the control of lipoprotein and lacUV5 promoter, and lac operator. Basically, the effects of concentrations of ampicillin and an inducer, IPTG, for the expression of the cloned gene, on the productions of alpha-interferon and plasmid stability were studied. The highest production of alpha-interferon was observed at 50 mg/1 of ampicillin concentration and 0.5 mM of IPTG. The plasmid pIF-III-B was maintained very stably in medium with ampicillin but segregated rapidly in medium without ampicillin. Also, the plasmid was segregated more rapidly in medium with an inducer higher than 0.5 mM.

• 한국추진공학회지
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• 제17권5호
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• pp.27-36
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• 2013

본 연구에서는 고체로켓 모터의 연소 불안정성을 예측하고 분석 할 수 있는 해석도구의 개발을 위해 음향에너지의 분석과 선형 안정성 해석을 수행하였다. 음향 해석의 경우 상용 프로그램인 COMSOL을 이용하여 단면적이 일정한 실린더 형상의 연소실 음향 해석 및 모드 해를 도출하였다. Culick에 의해 정립된 고체추진 로켓의 선형 안정성 해석에 기초하여 연소 불안정성을 진단하였으며 압력결합, 노즐감쇠, 입자감쇠의 안정성 요소(stability alpha) 외에 유동방향변환(flow turning) 요소와 점성감쇠(viscous loss) 요소를 추가하여 연료 표면 근처의 유동 및 점성효과를 포함하는 연소 불안정의 경향을 파악하였다. 또한 입자의 크기에 따른 주파수 영역별 연소 불안정 감쇠 특성을 파악하였다.

• 한국해양학회지
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• 제12권1호
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• pp.7-12
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• 1977

Vertical mixing in the ocean affects the formation of water masses as well as the vertical distribution of nutrients and dissolved substances. this study is to investigate the effect of stability on the intensity of vertical transfer in the case of shallow and straitfied channel. It is found that the relation of the stability and vertical turbulent diffusion is given by K$\sub$z/ = -${\beta}$-(c+${\beta}$) / ${\alpha}$(E-1/${\alpha}$) where K$\sub$z/ and E denotes the vertical turbulent diffusion coefficient and stability, respectively. The empirical coefficients ${\alpha}$, ${\beta}$ and c depend on the magnitude of vertical components and stability, i.e., through thermocline intensity. The study indicates that the diffusivity of the surface mixed layer is (K$\sub$z/)=300∼1,200$\textrm{cm}^2$/sec, the thermocline layer is (K$\sub$z/)= 50∼200$\textrm{cm}^2$/sec and the cold layer is (K$\sub$z/)=200∼600$\textrm{cm}^2$/sec based on near- minimum least-squares error estimates from the regression analysis. An important result of our study comes out that the model is in accordance with the general trends of the effect of stability on the vertical turbulent diffusion coefficients in the case of shallow and strongly stratified channel.