• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.11
• /
• pp.950-957
• /
• 1989

We have shown how unstructured modeling was used to derive a general stability condition in Part 1. In Part 2, we focus on the particular dynamics (structured modiling) of the robot manipulator and environment. Using rigid body dynamics, the stability condition for the direct drive robots has been achieved in terms of the Jacobian and robot tracking controller. Combining the structured and unstructured modeling, a stability condition for a particular application can be obtained. This approach has been used to analyze compliant motion on the University of Minnesota robot using a feedforward torque controller. We have obtained a stability condition for this application. Through both simulation and experiment, the sufficiency of this condition has been demonstrated. For a sufficient stability condition, recall that if the condition is satified, then the stability is guaranteed` however, if the condition is violated, no conclusion can be made.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.51 no.5
• /
• pp.401-407
• /
• 2006

This study was conducted to investigate the effect of onion cultivation under paddy and upland condition on the yield and storage of onion bulbs. In comparison of soil conditions, nitrogen, phosphate, potassium content and average temperature in upland condition were higher than those of paddy condition, but calcium, magnesium, sodium and water content in paddy condition were higher than those of upland condition. The growth of aerial part was better in upland cultivated condition. It showed that bulb formation in paddy cultivated condition was faster during in early growth stage, but was slower during in late growth stage. Average bulb size and weight were higher in upland cultivated condition, but dry weight per 100 g fresh weight and bulb hardness were higher in paddy cultivated condition. Sugar contents, inorganic compounds, nitrogen, phosphate and potassium content of onion were higher in upland cultivated condition, but calcium, magnesium and sodium content of onion were higher in paddy cultivated condition. In distribution of onion bulb size, most of large sized onions were produced in upland cultivated condition. Average bulb production for seed harvesting were $63{\sim}70%$ higher in paddy cultivated condition than that of upland cultivated condition. The rotted rate of onion was about $27.2{\sim}34.6%$ in paddy, $37.5{\sim}51.4%$ in upland cultivated condition respectively, showed favorable result as the difference of $8.7{\sim}24.2%$ in paddy cultivated condition.

• Journal of Power System Engineering
• /
• v.16 no.2
• /
• pp.43-48
• /
• 2012

Generally accelerated life test is well known as one method to reduce reliability qualification test period. This test is conducted under the higher stress condition than normal condition. So it can save the test time by calculating the acceleration factor from the relationship between the worst stress condition and normal condition. This paper investigates the worst stress condition for the accelerated life test to increase the acceleration factor. Especially, we focused on the method to obtain effective acceleration factors under the worst stress condition. Moreover, we considered how to decide the worst stress condition by looking for the operating limit of this system. The acceleration factor can be estimated from the ratio of the kinematic viscosity in the normal condition and the worst stress condition, the lowest temperature, by using Arrhenius relationship. Through some experiments for a refrigerator's compressor, we were able to confirm how to increase acceleration factors and how to reduce the reliability qualification test period with minimum samples.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.1
• /
• pp.70-77
• /
• 2015

This paper develops and evaluates a mechanical machining process which involves drilling on PVS material. According to the material, two treatment experiments were conducted, one involving drilling in a wet condition or using a lubricant and one involving drilling in a dry condition with no lubricant. Drilling in a dry condition showed better performance in terms of the cutting time than in the wet condition. Otherwise, the wet condition has several advantages. The lubricant influenced the burr diameter size and minimized the temperature on the surface of the work piece. During the wet condition drilling process, a smaller burr diameter size was noted as compared to the dry condition. The temperature showed a linear correlation with the drill bit size, where a least-square analysis provided an $R^2$valuewhichexceeded 0.95. The wet condition required more cutting time than the dry condition. In this condition, the water provides a lubrication effect. A thin layer between the cutting edges and the surface of the work piece is formed. The chip formation is affected by the drilling depth. The color on the tips of the chips was darker than in the initial condition. No correlation between the drilling depth and the bore roughness was noted, but the variation of the cutting speed or the RPM influenced the roughness of the bore. The optimum cutting speed ranged from 40 RPM to 45 RPM in the condition which provided the finest roughness surface.

• Journal of agriculture & life science
• /
• v.45 no.2
• /
• pp.1-7
• /
• 2011

Three evergreen ground-cover species were tested and evaluated for cold acclimation with different lights in central Korea to enrich the varieties of ground cover plants for over-wintering. Nandina domestica which recently started to be planted in central Korea had high chlorophyll unit with shade condition in both locations, Banpo and Gwacheon during winter. Light condition had no influence on chlorophyll unit in Banpo after April, meanwhile full sun condition decreased chlorophyll unit significantly in Gwacheon, which is exposed to cold wind from north. Ophiopogon japonicas had more than double chlorophyll unit in shade condition compared to that in full light condition in both investigation areas in February. In addition, higher value of L and b in shade condition had been maintained than in full sun condition throughout investigation period. However, leaves in Gwacheon were de-colorized in full sun condition after over-wintering. Pachysandra terminalis had more higher chlorophyll unit in shade condition compared to in full sun condition in both investigation areas in February. But light conditions had not effect the difference of chlorophyll unit of Gwacheon in April. Therefore, The present results suggest that evergreen ground covers with shade condition would be used as landscape materials in the capital area.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.42
• /
• pp.109-132
• /
• 2009

The purpose of the introduction of this article is as follows. It was frequent to put a condition on the letter of credit without stating corresponding document. But these attempts are very dangerous to the letter of credit operation. That is, if these types of conditions would be permitted in letter of credit, the independence principle must be collapsed. So these conditions must be disregarded in order to safeguard the independence principle. It is why UCP600 article 14(h) writes that if a Credit contains a condition without stating the document(s) to be presented in compliance therewith, banks will deem such conditions as not stated and will disregard it. But scope of this article 14 should not be limited by the conditions which do not state the document to be presented in compliance therewith. That is, the purpose of this article is to preserve the independence principle, so, if it is impossible to ascertain satisfaction with a condition, it should be disregarded as the non-documentary condition, even if the condition is included in the letter of credit together with document to be presented. Conclusively, whether or not a condition would be regarded as the non documentary condition depends on whether compliance of such condition is ascertained by presented documents stipulated in the letter of credit.

• Journal of computational fluids engineering
• /
• v.21 no.1
• /
• pp.10-18
• /
• 2016

Numerical boundary conditions are as important as the governing equations when analyzing the fluid flows numerically. An explicit boundary condition method updates the solutions at the boundaries with extrapolation from the interior of the computational domain, while the implicit boundary condition method in conjunction with an implicit time integration method solves the solutions of the entire computational domain including the boundaries simultaneously. The implicit boundary condition method, therefore, is more robust than the explicit boundary condition method. In this paper, steady compressible 2-Dimensional Navier-Stokes solver is developed. We present the implicit boundary condition method coupled with LU-SGS(Lower Upper Symmetric Gauss Seidel) method. Also, the explicit boundary condition method is implemented for comparison. The preconditioning Navier-Stokes equations are solved on unstructured meshes. The numerical computations for a number of flows show that the implicit boundary condition method can give accurate solutions.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.7 s.196
• /
• pp.106-111
• /
• 2007

In this paper, the transient brake time was studied on the van type vehicle with accelerometer. Experiments were carried out on the asphalt(new and polished), unpacked road(earth and gravel) and on wet or dry road conditions. The transient brake time is not effected bzy the vehicle speed. The transient brake time is about 0.41$\sim$0.43second on the asphalt road surface and the error range is within 0.1$\sim$0.16second. For the asphalt road condition, the transient brake time is not effected by both new asphalt road surface and the polished asphalt road surface. With compared by dry and wet road surface condition, the transient brake time of wet condition is longer than dry road condition and compared with unpacked road condition and packed road condition, unpacked road condition is shorter than packed road condition. It is considered that the transient brake time is effected by the road surface fraction coefficient. In other words, the transients brake time increases as friction coefficient decreases.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.31 no.2
• /
• pp.50-57
• /
• 1999

This study was carried out to compare a conventional alkaline flotation deinking conditions with neutral deinking conditions with and without enzyme addition with respect to the ink removal efficiency and theflotation deinking filtrate quality such as chemical oxygen demand, cationic demand, suspended solids. Based on ink removal rate the neutral deinking condition without enzyme was better than the alkaline deinking condition, and the neutral deinking with enzyme addition turned out to be the best. The brightness of the deinked pulp was found to be the same trend as the ink removal rate. Flotation reject rate for the neutral deinking condition without enzyme was higher than that of the alkaline deinking condition, but that of the neutral deinking condition with enzyme was lower than that of the alkaline and the neutral deinking condition without enzyme. On the freeness of the deinked pulp, the neutral deinking condition with enzyme had the highest value and the alkaline deinking condition had the lowest value among the conditions tested. On the filtrate of the flotation stage, the cationic polymer demand of the neutral deinking condition with enzyme was much lower than the other conditions. Suspended solids and chemical exygen demand for the neutral flotation deinking filtrate was lower than those of the alkaline flotation deinking filtrate.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.7
• /
• pp.937-944
• /
• 2002

An experimental study has been conducted to investigate the heat/mass transfer characteristics within a square film cooling hole with asymmetric inlet now condition. The asymmetric inlet now condition is achieved by making distances between side walls of the secondary now duct and the film cooling hole different; one side wall is $2D_h$ apart from the center of the film cooling hole, while the other side wall is $1.5D_h$ apart from the center of the film cooling hole. The heat/mass transfer experiments for this study have been performed using a naphthalene sublimation method and the now field has been analyzed by numerical calculation using a commercial code. Swirl now is generated at the inlet region and the heat/mass transfer pattem with the asymmetric inlet now condition is changed significantly from that with the symmetric condition. In the exit region, the effect of mainstream on the inside hole now is reduced with the asymmetric condition. The average heat/mass transfer coefficient is higher than that with the symmetric condition due to the swirl now generated by the asymmetric inlet condition.