• Transactions of the Korean hydrogen and new energy society
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• v.9 no.2
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• pp.53-64
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• 1998

Thermal analysis on a Linde-Hampson hydrogen liquefaction system using cryogenic refrigerators as precooling has been carried out. Three commercially available models of cryogenic refrigerators, such as CTI l020CP, CVI CGR009 and CVI CGR011, are considered in the performance analysis. The effect of ortho-para conversion process during hydrogen liquefaction is also studied in detail. The results obtained indicate that the optimal hydrogen mass flow rate and the optimal compressed pressure exist for the maximum hydrogen liquefaction rate. The optimal compressed pressure is increased in the range of 80 - 120 bar with an increase in the hydrogen mass flow rate. It is also found that better performance could be obtained with a cryogenic refrigerator, which produces high cooling capacity at precooling temperature in the range of 80 - 100 K.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.36-36
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• 2002

To Establish of standard technique of length measurent in 2D plane, we develope AFM system. The XY scanner scans the sample only in XY plane, while the Z scanner scans the specimen only in Z-direction. Cantilever tip is controlled to has constant height relative to speciman surface by feedback of PSPD signal. To acquire high accuracy, Z-axis measuring sensor will be added.(COXI or others). In this paper we design XYZ stage suitable for this AEM system. For XY stage, single module parallel-kinnematic flexure stage is used which has high orthogonality and minimum out-of-plane motion. To obtain best performance optimal design is performed. For XY stage, to be robust about parasitic motion optimal design of maximizing Z and tilt stiffness is performed under the constraint of motion range and stage size. And for Z stage, optimal design of maximizing 1st resonant frequency is performed. Because if resonant frequency is get higher, scan speed is improved. So it makes reduce the error by sensor drift. Resultly XYZ stage each have 1st natural frequency of 115㎐, 201㎐, 2.66㎑ and range 109㎛, 110㎛, 12㎛.

• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.456-460
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• 1996

Recombinant Pseudomonas lipase was used to study protein aggregation and adsorption upon in vitro refolding. Protein adsorption as well as aggregation was responsible for major side reactions upon in vitro refolding as a function of protein concentration. The optimal range of protein concentration was determined by the relative contribution of protein aggregation and adsorption. Above the optimal range, the yield of active lipase inversely correlated with protein aggregation, showing a competition between folding and aggregation. However, adsorption of protein rather than protein aggregation is thought to contribute as a major side reaction of the refolding process at sub-optimal concentrations at which the formation of aggregates should be more reduced. Protein aggregation was influenced by the amount of guanidine hydrochloride in the refolding solvent. The refolding temperature was a critical factor determining the extent of protein aggregation. The refolding yield was also affected by the dilution fold and dilution mode, which suggests that the refolding process might kinetically compete with the rate of mixing.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.768-777
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• 2005

This paper shows that the performance of a nonlinear fluid engine mount can be improved by an optimal design process. The property of a hydraulic mount with inertia track and decoupler differs according to the disturbance frequency range. Since the excitation amplitude is large at low excitation frequency range and is small at high excitation frequency range, mathematical model of the mount can be divided into two linear models. One is a low frequency model and the other is a high frequency model. The combination of the two models is very useful in the analysis of the mount and is used for the first time in the optimization of an engine mount in this paper. Normally, the design of a fluid mount is based on a trial and error approach in industry because there are many design parameters. In this study, a nonlinear mount was optimized to minimize the transmissibilities of the mount at the notch and the resonance frequencies for low and high-frequency models by a popular optimization technique of sequential quadratic programming (SQP) supported by $MATLAB^{(R)}$subroutine. The results show that the performance of the mount can be greatly improved for the low and high frequencies ranges by the optimization method.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.259-276
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• 2016

Lead-rubber bearings (LRBs) have been used worldwide in seismic design of buildings and bridges owing to their stable mechanical properties and good isolation effect. We have investigated the effectiveness of LRBs in framed underground structures on controlling structural seismic responses. Nonlinear dynamic time history analyses were carried out on the well-documented Daikai Station, which collapsed during the 1995 Hyogoken-Nanbu earthquake. Influences of strength ratio (ratio of yield strength of LRBs to yield strength of central column) and shear modulus of rubber on structural seismic responses were studied. As a displacement-based passive energy dissipation device, LRBs reduce dynamic internal forces of framed underground structures and improve their seismic performance. An optimal range of strength ratios was proposed for the case presented. Within this range, LRBs can dissipate maximum input earthquake energy. The maximum shear and moment of the central column can achieve more than 50% reduction, whereas the maximum shear displacement of LRBs is acceptable.

• Earthquakes and Structures
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• v.15 no.4
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• pp.443-452
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• 2018

In this paper the new intensity measures (IMs) for probabilistic seismic analysis of RC high-rise buildings with core wall structural system are proposed. The existing IMs are analysed and the new optimal ones are presented. The newly proposed IMs are based on the existing ones which: 1) comprise a wider range of frequency velocity spectrum content and 2) are defined as the integral along the velocity spectrum. In analysis characteristics of optimal IMs such as: efficiency, practicality, proficiency and sufficiency are considered. As prototype buildings, RC high-rise buildings with core wall structural system and with characteristic heights: 20-storey, 30-storey and 40-storey, are selected. The non-linear 3D models of the prototype buildings are constructed. 720 non-linear time-history analyses are conducted for 60 ground motion records with a wide range of magnitudes, distances to source and various soil types. Statistical processing of results and detailed regression analysis are performed and appropriate demand models which relate IMs to demand measures (DMs), are obtained. The conducted analysis has shown that the newly proposed IMs can efficiently predict the DMs with minimum dispersion and satisfactory practicality as compared to the other commonly used IMs (e.g., PGA and $S_a(T_1)$). The newly proposed IMs overcome difficulties in calculating of integral along the velocity spectrum and present adequate replacement for IMs which comprise a wider range of frequency velocity spectrum content.

• Journal of the East Asian Society of Dietary Life
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• v.19 no.1
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• pp.38-44
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• 2009

The principal objective of this study was to determine the optimal mixing ratios of three different quantities of spirulina, salt and water for the preparation of Korean rice cake (Dukbokiduk) via response surface methodology on the basis of color, texture, and sensory test. The spirulina levels were tested in a range of $1{\sim}3%$, the water levels in a range of $15{\sim}25%$, and salt levels were tested a range of $0.5{\sim}1%$ by weight of rice powder. Taste was influenced most profoundly by the amount of added spirulina. Optimal taste was achieved with 1% of spirulina, 0.75% of salt and 20% water. Thus, the optimal mixing ratios of spirulina, salt, and water for Dukbokiduk were 1.0%, 0.57%, and 19.46%, respectively.

• The Korean Journal of Ecology
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• v.8 no.3
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• pp.147-152
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• 1985

The forest vegetation of natural reserve area (175ha) at north-eastern slope of Solibong (537m), Gwangneung, was studied by plant sociological method and two dimensional ordination technique. In the area dominated by Carpinus laxiflora, from the lower site to peak of Solibong, a zonal distribution of C. laxiflora-Quercus mongolic forest, C. laxiflora-C. cordata forest, C. laxiflora-Q. serrata forest, C. laxiflora forest and C. laxiflora-Rhododendron schlippenbachii forest were recognized by the plant sociological survey. It is seem that the optimal range of Carpinus laxiflora forest occur in mesic-warm site by two dimensiional ordination with thermal condition and soil moisture condition. The optimal range (over 100 in importance value) was the range of 76~89。C.month in warmth index and 18~45% in soil water content.

• The Journal of the Korean Society for Microbiology
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• v.21 no.2
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• pp.227-231
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• 1986

The hemagglutination activities of Hantaan virus and Seoul virus were demonstrated. The hemagglutinins were prepared by sucrose-acetone extraction method from suckling mouse brains infectecd with Hantaan and Seoul viruses. Hemagglutination of goose erythrocytes by these viral hemagglutinins was pH dependent in phosphate buffer system. Hantaan and Seoul viruses were distinguished by pH range of hemagglutination. 76/118 and 79/90 strains of Hantaan virus showed hemagglutination at the range of pH 5.75-6.4 and the optimal pH was 5.75 with the titer of 1:512 in 76/118 and 1:256 in 79/90. In contrast, KSNUSD 84/34 strain of Seoul virus revealed hemagglutination at the range of pH 6.2-6.4 and the optimal pH was 6.4 with the titer of 1 : 64.

• Journal of Ocean Engineering and Technology
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• v.18 no.1
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• pp.1-6
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• 2004

In this paper, the performance of a wave absorbing system using an inclined punching plate, was investigated. Using the multi-domain boundary element method (BEM), the reflection coefficients of an inclined punching plate were tested with various design parameters, such as inclined angle, porosity, and wave frequencies. To confirm the numerical solutions, the systematic model test was conducted at 2-D tank and square tank. The numerical results were in good agreement with the experimental results within the entire frequency range. It was found that an inclined punching plate had an excellent wave absorbing efficiency, compared to a horizontal one. Also, the optimal range of an inclined angle had an excellent wave absorbing efficiency, compared to a horizontal one the optimal range of the inclined angle is 10°<β<20°. The developed wave absorber was installed at KRISO's square basin, and is working effectively for various model tests.