• 한국미생물·생명공학회지
• /
• 제19권1호
• /
• pp.100-108
• /
• 1991

Molecular characteristics and improving methods for thermal stability of enzyme have been considered. Intrinsic and extrinsic stabilizing mechanisms are two governing principles for enhanced thermal stability of enzyme in molecular basis. Factors contributing to the former and the latter mechanisms may be involved in the enhanced thermal stability of enzyme complementarily. Also, the methods for improving thermal stability of enzyme which comprise reaction in organic solvent system, chemical modification, immobilization, sequential unfolding and refolding, gene manipulation techniques and enzyme-antibody complexing are reviewed.

• 가정과삶의질연구
• /
• 제20권4호
• /
• pp.197-206
• /
• 2002

The purpose of this study was to examine the effect of marital characteristics on the marital stability among the elderly couples. Each participant was measured using a scale for the concept of marriage, a scale for marital coherence, a marital stress scale, a coping behavior scale and a marital stability scale. Elderly people who have a living spouse and who are living In Seoul were recruited. The data from two hundred and forty participants over 60-years-old were used in the final analyses. Major findings are as follows First, demographic factors such as educational level, health, economic status, the main source of income, and employment status appeared to significantly predict the elderly folks'marital stability Second, gender seems to be a factor In elderly couples'experience of marital stability. Husbands perceived marital stability to be higher than wives did. Third, the perception of marital stress, positive coping behavior and marital coherence influence the marital stability of the elderly couples. That is, the less elderly couples perceived marital stress and the less they relied on negative coping behaviors, the higher they perceived marital stability. These results imply that a healthful coping behavior to marital stress is important in enhancing marital stability for elderly couples.

• 대한기계학회논문집A
• /
• 제24권3호
• /
• pp.543-549
• /
• 2000

Results of theoretical investigations of the stability characteristics of an actively controlled externally pressurized air journal bearing are presented. Proportional control and derivative control are used for the control algorithm of active air bearing. The stability characteristics of the actively controlled bearing operating at zero steady-state eccentricity is investigated with the step jump method. The speed at onset of instability is raised for both proportional control and derivative control of bearing. Proportional control increased the stability threshold without affecting the whirl ratio. But for derivative control of bearing, stability threshold increase is accompanied by a parallel reduction of the whirl ratio. Results show active control of bearing can be adopted for the stability improvement of air journal bearing.

• Tribology and Lubricants
• /
• 제15권4호
• /
• pp.314-320
• /
• 1999

Friction and wear characteristics of phenolic resin-based friction materials reinforced with aramid pulp and potassium titanate were investigated using a pad-on-disk type friction tester. Friction characteristics such as friction stability, thermal stability, and wear rate varied according to the type of phenolic resins and the relative amount of aramid pulp and potassium titanate. The modified novolac resin-based friction materials showed better heat resistance and friction stability than those with the unmodified(straight) novolac resin. Compared with friction materials filled with potassium titanate or aramid pulp only, the friction materials reinforced with both aramid pulp and potassium titanate showed good friction stability and wear resistance. Increment of aramid pulp from 10 to 20 vol.% however, showed little difference in friction stability.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
• /
• pp.256-261
• /
• 1986

The sensitiveness of the stability characteristics of the aircraft with respect to changes in the stability parameters as predicted by the linear analysis is applied for the two aerodynamic models proposed. The results give the detailed information for an aircraft dynamic behavior especially at complicated flight envelope.

• 폴리머
• /
• 제27권5호
• /
• pp.484-492
• /
• 2003

러빙에 의해 유도된 네마틱 액정의 배향 특성과 그 안정성이 액정-폴리이미드 계면 특성과 어떠한 관계가 있는지를 조사하였다. 합성된 5 종류의 폴리이미드 특성을 분석하고 폴리이미드 배향막에서의 액정 배향의 균일성, 선경사각, 정착 에너지, 그리고 열 안정성을 측정 조사하였다. 러빙된 폴리이미드는 강한 정착의 액정 배향을 유도하고 액정 배향의 특성과 안정성은 배향막 표면에서의 액정과 폴리이미드 간의 분자 차원의 상호작용에 의해 결정된다는 것을 확인하였다. 폴리이미드의 유연성의 증가는 이미드화를 촉진시키며 액정의 선경사각과 배향 안정성을 증대시킨다. 반면에, 폴리이미드의 플루오르화는 액정의 배향성 및 배향 안정성을 감소시키는 것으로 나타났다. 폴리이미드의 방향족과 지방족 고리 이무수물 구조에 따른 액정 배향의 특성과 안정성에는 뚜렷한 차이가 나타나지 않았다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제9권4호
• /
• pp.382-389
• /
• 2017

We are developing a prototype underwater glider for subsea payload delivery. The idea is to use a glider to deliver payloads for subsea installations. In this type of application, the hydrodynamic forces and dynamic stability of the glider is of particular importance, as it has implications on the glider's endurance and operation. In this work, the effect of two different wing forms, rectangular and tapered, on the hydrodynamic characteristics and dynamic stability of the glider were investigated, to determine the optimal wing form. To determine the hydrodynamic characteristics, tow tank resistance tests were carried out using a model fitted alternately with a rectangular wing and tapered wing. Steady-state CFD analysis was conducted using the hydrodynamic coefficients obtained from the tests, to obtain the lift, drag and hydrodynamic derivatives at different angular velocities. The results show that the rectangular wing provides larger lift forces but with a reduced stability envelope. Conversely, the tapered wing exhibits lower lift force but improved dynamic stability.

• 한국식품영양학회지
• /
• 제30권5호
• /
• pp.960-972
• /
• 2017

The objectives of this study was to investigate the properties and stability of the wet noodles added to nanoemulsion as a industrial model system, and in so doing, survey practical applicability in the food industry. In order to test out these objectives, the characteristics and stability of the wet noodles added to nanoemulsion were investigated and their cooking characteristics and capsaicinoids loss were examined. As a result, the test results showed that the findings indicated that the post-cooking loss of capsaicinoids in the wet noodles added to double-layer nanoemulsion covered with chitosan was less than the losses in the wet noodles added to any other noodles. More especially, this demonstrates that the noodle added to double-layer nanoemulsion covered with chitosan scored significantly higher than the others with reference to their cooking properties, color, texture, stability for storage stability, and sensory evaluation. These results show that the findings of this study demonstrated that the noodles added to nanoemulsions could be produced as a food-grade merchandise because they could provide enhanced encapsulation capacity of capsaicinoids and higher acceptability.

• 대한기계학회논문집B
• /
• 제27권8호
• /
• pp.1122-1133
• /
• 2003

Numerical characteristics of implicit upwind schemes, such as upwind ADI, line Gauss-Seidel (LGS) and point Gauss-Seidel (LU) algorithms, for Navier-Stokes equations have been investigated. Time-derivative preconditioning method was applied for efficient convergence at low Mach/Reynolds number regime as well as at large grid aspect ratios. All the algorithms were expressed in approximate factorization form and von Neumann stability analysis was performed to identify stability characteristics of the above algorithms in the presence of high grid aspect ratios. Stability analysis showed that for high aspect ratio computations, the ADI and LGS algorithms showed efficient damping effect up to moderate aspect ratio if we adopt viscous preconditioning based on min-CFL/max-VNN time-step definition. The LU algorithm, on the other hand, showed serious deterioration in stability characteristics as the grid aspect ratio increases. Computations for several practical applications also verified these results.

• 한국군사과학기술학회지
• /
• 제23권4호
• /
• pp.355-362
• /
• 2020

EFP composed of explosive, charge and liner generally penetrates standoff a target by Monroe effect. Its performance highly depends on penetrator characteristics and flight stability. Penetration ability can be dramatically reduced when the penetrator reaches the target with AOA, even if the penetrator has high kinetic energy and L/D ratio. Therefore, it is important to research not only penetrator characteristics and but also flight stability. In this work, the effect of liner shape on penetrator characteristics was examined using free flight test and numerical tools. It was found that tip velocity of penetrator was increased with decreasing liner thickness. It was also found that thicker liner had higher static margin leading to better flight status.