• 제어로봇시스템학회논문지
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• 제20권4호
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• pp.389-394
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• 2014

This paper presents the effect of a reflective force computed from a first-order-hold method on the stability of a haptic system. A haptic system is composed of a haptic device with a mass and a damper, a virtual spring, a sampler and a sample-and-hold. The boundary condition of the maximum virtual stiffness is analytically derived by using the Routh-Hurwitz criterion and the condition shows that the maximum virtual stiffness is proportional to the square root of the mass and the damper of a haptic device and also is inversely proportional to the sampling time to the power of three over two. The effectiveness of the derived condition is evaluated by the simulation. When the reflective forces are computed by using the first-order-hold method, the maximum available stiffness to guarantee the stability is increased several hundred times as large as when the zero-order-hold method is applied.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.15-16
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• 2006

The thermal stability of nickel silicide with compressively and tensilely stressed nitride capping layer has been investigated in this study. The Ni (10 nm) and Ni/Co/TiN (7/3/25 nm) structures were deposited on the p-type Si substrate. The stressed capping layer was deposited using plasma enhanced chemical vapor deposition (PECVD) after silicide formation by one-step rapid thermal process (RTP) at $500^{\circ}C$ for 30 sec. It was found that the thermal stability of nickel silicide depends on the stress induced by the nitride capping layer. In the case of Ni (10 nm) structure, the high compressive sample shows the best thermal stability, whereas in the case of Ni/Co/TiN (7/3/25 nm) structure, the high compressive sample shows the worst thermal stability.

• 한국산업보건학회지
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• 제33권4호
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• pp.455-463
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• 2023

Objectives: The aim of this study was to develop an air sampling and analytical method for estimating worker exposure to linear carbonate solvents and to evaluate the method. Methods: The target substances were three linear carbonates: DMC, DEC, EMC. GC/FID was used for sample analysis. Laboratory experiments were conducted to determine desorption solvents and sample capacity, and to evaluate storage stability, accuracy, and precision. Results: Coconut Shell Charcoal (CSC, 100/50 mg) was used as the air sampling media, and a desorption solvent of 5% methanol/95% dichloromethane was selected. Recommended sampling capacities were 1~11 ℓ for DMC, 1~18 ℓ for DEC, and 1~24 ℓ for EMC. The stability of three linear carbonates was demonstrated over 30 days in a refrigerator (4℃). Detection limits were determined as follows: DMC 0.26 ㎍/sample, DEC 0.24 ㎍/sample, and EMC 0.25 ㎍/sample. The total coefficient of variation was calculated as DMC 0.064, DEC 0.079, and EMC 0.07. Conclusions: This sampling and analysis method is suitable for estimating personal exposure to linear carbonates in the workplace.

• Elastomers and Composites
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• 제50권1호
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• pp.30-34
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• 2015

Thermo-mechanical treatment process of a compressed open-cell rigid polyurethane foam (OC-RPUF), which was fabricated for the vacuum insulation panel (VIP), was studied to obtain an optimum condition for the dimensional stability by the relaxation of compressive stress. Thermo-mechanical deformation of the sample OC-RPUF was shown to occur from about $120^{\circ}C$. Yield stress of 0.36 MPa was shown at about 10% yield strain. And, densification of the foam started to occur from 75% compressive strain and could be continued up to max. 90%. Compression set of the sample restored after initial compression to 90% at room temperature was ca. 82%. Though the expansion occurred to about twice of the originally compressed thickness in case of temperature rise to $130^{\circ}C$, it could be overcome and the dimensional stability could be maintained if the constant load of 0.3 MPa was applied. As the result, a thermo-mechanical treatment process, i.e, annealing process at temperature of $130{\sim}140^{\circ}C$ for about 20 min as is the maximum compressed state at room temperature, should be required for dimensional stability as an optimum condition for the use of VIP core material.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.288-289
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• 2005

As high temperature superconductor applications became a reality due to increase in coated conductor performance, it is important to understand their stability behavior to design safe electrical power systems. We have experimentally studied the dependence of quench and recovery characteristics of coated conductors on the amplitude of current and duration time. The sample used in the present study is stabilized with stainless steel. Stability tests of 3 cm long sample were performed in a liquid nitrogen bath cooling condition by applying a short period over current pulses for 50 and 100 ms, with amplitude up to ~ 6 times of the critical current. The transport current that follows before and after the current pulse was fixed about ~85% the critical current. We analyzed the quench recovery using the current voltage characteristic.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.253-258
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• 1994

Recently, computer technique for the analysis of slope stability enable to reduce a considerable time and efforts. And also, stability problems can be approached by using stablility chart which was basically developed to handle the problems under simple conditions only. Most of the conventional slope stability computer programs and stability chart are still based on the general limit equilibrium method. 16 types of sample slopes and 2 types of failure slope were compared and analysed by stability charts and programs. This research work intend to apply 4 types of conventional computer programs based on the same theoretical backgroung and 7 types of stability charts for solving the same stability problems and the results and compared and analysed in order to justify their reliability.

• 한국해양공학회지
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• 제34권2호
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• pp.55-65
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• 2020

A review of the 2nd generation of intact stability by the International Maritime Organization is performed. The main issues with the new stability criteria are reviewed. In particular, the physical background and related mathematical formulations of the pure loss of stability and parametric roll are summarized. Based on a literature review, benchmark calculation results for 17 different types of ships are discussed, and the final results are in excellent agreement with our physical expectations. Some relatively serious design problems are found in the application of the new stability criteria to sample ships built in Korea, and possible technical solutions are proposed, which have to be improved in the coming years.

• 한국식품조리과학회지
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• 제26권5호
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• pp.537-544
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• 2010

This study was conducted to find an efficient use for mulberry fruit powder (MFP). MFP was added to salad dressing products at concentrations of 0.25, 0.5, 0.75, 1%, and pH, total acidity, viscosity, color, and emulsion stability were measured and sensory evaluation was conducted. There were no significant differences among salad dressing samples regarding pH, total acidity and moisture content. Salad dressing made with 0.5% MFP showed significantly higher viscosity during storage and made the most stable emulsion. For color, the control sample had the highest L and b values, and these values decreased significantly as the amount of MFP in the sample increased. The control salad dressing had the lowest a value of -3.26, and this value increased significantly as the amount of MFP in the sample increased. Sensory evaluation of salad dressing was performed by a trained consumer panel. The flavor intensity increased as the amount of MFP increased in the salad dressing samples. Sweetness was rated significantly higher as the amount of MFP increased in the samples. The control sample had the lowest sourness and off-flavor, but there was no significant difference compared to the samples containing MFP.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.107-113
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• 2008

본 실험은 구동 온도와 방전관의 길이에 따라 변화하는 ICP 광원의 전기 광학적 특성에 대해서 알아보았다. 광원의 전기 광학적 특성이 정상상태에 놓이는 구동 조건을 확인하기 위하여 시간에 따른 전력 소모와 광속의 변화를 측정하였다. 전력소모와 광속의 시간에 따른 변화를 측정한 결과를 통해서 볼 때 최초구동에서 70분이 경과한 이후부터 전력소모는 초기값에 대해 1.45[%], 광속은 0.36[%]의 안정성을 나타냈다. 항온챔버 내에서 온도를 5구간으로 나뉘어 변화하면서 구동 온도에 따른 ICP 광원의 광학적 특성을 알아보았다. 휘도는 온도의 상승과 비례적으로 증가하였으나 $46.7[^{\circ}C]$ 이상에서는 오히려 감소하는 결과를 얻을 수 있었다. 파센법칙과 함께 보일-샤를의 법칙을 통해 0.02[Torr]의 압력이 변화함에 따라 더 높은 방전전압이 요구되지만 충분한 전압이 안정기에서 공급되지 못하기 때문이라 판단된다. 이와 더불어 방전관 길이에 따라 광원에 인가되는 전력과 전류을 측정하였다.

• 대한전기학회논문지
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• 제43권6호
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• pp.869-876
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• 1994

This paper presents an efficient method to calculate voltage collapse point and to avoid voltage instability. To evaluate voltage stability in power systems, it is necessary to get critical loading points. For this purpose, this paper uses linear programming to calculate efficiently voltage collapse point. Also, if index value becomes larger than given threshold value, voltage stability is improved by compensation of reactive power at selected bus. This algorithm is verified by simulation on the IEEE 14-bus sample system.