• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.903-910
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• 1998

Ti:LiNbO$_3$ optical waveguides have been fabricated by Ti-diffusion in wet oxygen atmosphere. The fabrication conditions of furnace temperature, diffusion time and bubbler temperature were 105$0^{\circ}C$, 8 hours and 9$0^{\circ}C$, respectively and Ti thickness was varied from 700$\AA$ to 1500$\AA$. In this paper, the nearfield patterns, mode sizes (hirizontal/vertical) and insertion loss of waveguides were discussed at wavelength 1550 nm ad function of Ti thickness. With the planar waveguide, the effective index change and diffusion depth were calculated at 632.8nm using the prism coupling method. From these results, the best Ti thickness in our conditions seems like to by 1200$\AA$~1300$\AA$.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.560-568
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• 1998

Recently to develop an automobile with better properities many researches and investments have been executed. In this paper we intend to improve the automobile properties by reducing the weight of the engine without changing the dynamic characteristics. At first the vibration analysis by the Substructure Synthesis Mehtod and the exciting test of the engine model performed to confirm the reliability of the analyzing tools. And the weight minimiza-tion is performed by the Sensitivity Analysis and the Optimum Structural Modificationl. To decrease the engine weight ideally the weight of the parts with the low sensitivity is to cut mainly and the changing quantity of the natural frequency by the cut is to be recovered by the weight modification of the parts with the high sensitivity. As actually the mathematical unique solution for the homogeneous problem(i. e. 0 object func-tion problem)does not exist we redesign the engine block with much thinner initial thickness and recover the natural frequencies and natural modes of original structure by the sensitivity analy-sis and then observe the Frequency Response Function(FRF) for the interesting points. In this analysis the original thickness of the engine model is 8mm and the redesigned initial thicknesses are 5mm and 6mm, And the number of the interesting natural frequencies are 1, 2, 3, 4 and 5 respectively.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.2
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• pp.74-83
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• 2001

The purpose of this study was investigate to the influence of forest roads characteristics and environment factors on the soil erosion, stability and vegetation survival of cut slope in forest roads. The results obtained could be summarized as follows; 1. The correlated factors between slope erosion and variables in cut slope were altitude, convex, degree of slope, length of slope and soil depth. In the stepwise regression analysis, length of slope and soil hardness was a high significant and its regression equation was given by -89.6136 + 15.0667X14 + 16.6713X15($R^2$ = 0.6712). 2. The main factors influencing the stability of cut slope were significant in order of coverage, middle, convex, length of slope and north, and its discriminant equation was given by -1.019 + 0.064X22 - 0.808X8 - 0.622X24 + 0.742X11 - 0.172X14 - 0.545X6 ($R^2$ = 0.793). 3. The centroids value of discriminant function in the stability and unstability estimated to 1.244 and -1.348, respectively. The boundary value between two groups related to slope stability was -0.1038. The prediction rate of discriminant function for stability evaluation of was as high as 91.3%. 4. The dominant species of invasion vegetation on the cut slope consist with Carex humilis, Agropyron tsukushiense var. transiens, Calamagrostis arundinacea, Miscanthus sinensis var. purpurascens, and Ixeris dentata in survey area. The rate of vegetation invasion more increased by time passed. 5. The life form of invasion vegetation in cut slop showed to $H-D_1-R_{2,3}-e$ type of the hemicryptophyte of dormancy form, dissem inated widely by wind and water of dissminule type, moderate extent and narrowest extent of radicoid type, erect form of growth form. 6. The correlated factors between forest enviroment and coverage appeared north, passage years and middle position of slope at 5% level. The forest environment factors influencing the invasion plants in survey area were shown in order to altitude, passage years, rock(none), forest type(mixed) and stone amount. The regression equation was given by 17.5228 - 0.0911X3 + 3.6189X28 15.8493X22 19.8544X25 + 0.3558X26 ($R^2$ = 0.4026).

• Horticultural Science & Technology
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• v.29 no.2
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• pp.110-115
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• 2011

To examine the availability of onggi (earthenware) as a floral vase, we compared the vase life of cut gerberas (Gerbera jamesonii) with generally used vases made of glass and porcelain. After holding cut gerbera 'Honeymoon' and 'Golden Time' in vases made of glass, porcelain, and onggi containing holding solution (tap water or preservative solution), vase life, fresh weight, and water uptake of cut flowers, and total number of microbes in holding solution were collected. In onggi vase, vase life of both the cultivars was longer than the other vases and floral preservative prolonged vase life compared with tap water. Cut gerberas applied with preservative solution in onggi vase maintained their ornamental value for more than 14 days. Cumulative water uptake by cut gerberas was greatest in onggi vase, where 'Honeymoon' and 'Golden Time' absorbed water by 19.2 and 15.8 mL, respectively, for 10 days. Fresh weight of cut flowers in onggi vase was greater than those of the others, and the preservative solution delayed the reduction of fresh weight compared with tap water. Especially, onggi vase with preservative solution maintained 89% of the initial fresh weight at the 8th day of the treatments due to smooth water uptake with comparison with 71% in porcelain. Total number of microbes in the holding solution was smallest in onggi vase. At the 8th day, microbes number in onggi vase was 435 cfu/mL, that was 20-30% level of those of glass and porcelain vases. In conclusion, onggi vase inhibited microbial proliferation in holding solution, maintained water uptake by cut flower, and delayed bending of flower stalks due to vascular blockage, and then prolonged vase life in gerbera. Therefore, onggi with numerous micropores will be a good material for flower vase and preservative solution can improve its function.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.22
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• pp.79-85
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• 1990

An important problem to be carried into a plan on the occasion for introduction of TQC is to establish the clear-cut policy and workable system on QC. In connection with escalation the product liability in recent days, especially, a point to he considered in relation the real state of enterprise, it seems likely to be difficult an effective performance without distribution of the definite duality function to each departments in the company, and to define the quality function, it should be educed and coordinated under agreement organization wide participation and conciliation. In this paper, we have tried to have a more effective graft the European style QC on the oriental enterprise, by means of presenting a model that manages synthetically a way of deployment the fundamental factors affecting quality, and establishing the control subject in each function unit.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1467-1475
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• 2007

This paper investigates the modal acoustic power by a cascade of flat-plate airfoils interacting with homogeneous, isotropic turbulence. Basic formulation for the acoustic power upstream and downstream is based on the analytical theory of Smith and its generalization due to Cheong et al. The acoustic power spectrum has been expressed as the sum of cut-on acoustic modes, whose modal power is the product of three terms: a turbulence series, an upstream or downstream power factor and an upstream or downstream acoustic response function. The effect of these terms in the modal acoustic power has been examined. For isotropic turbulence gust, the turbulent series are only reducing factor of the modal acoustic power. The power factor tends to reduce the modal acoustic power in the upstream direction, although the power factor is liable to increase the modal acoustic power in the downstream direction. The modes close to cut-off are decreasing strongly, especially in the downstream direction. Therefore the modes close to cut-off don't contribute highly to the radiated acoustic power in the downstream direction, although the modal acoustic pressure is high for these modes.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.222-229
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• 1999

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ration using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to cutting torque acting on a single tooth at the swept angle of cut and can be acquired form cutting torque signals. Average cutting torque per revolution can also be calculate form cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.4
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• pp.91-98
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• 2000

In this paper , presented is a method of on-line estimation of the radial immersion ratio and cutting force ratio using cutting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. These force drops are equal to the cutting forces that act on a single tooth at the swept angle of cut and can be obtained from cutting force signals in feed and crossfeed directions. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting forces, the radial immersion ratio is estimated along with the cutting force ratio at that immersion angle. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tangential direction cutting force can be estimated by the proposed method very well.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.239-244
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• 1999

Radial immersion ratio is an important factor to determine the threshold in face milling and should be estimated in process for automatic force regulation. In this paper, presented is a method of on-line estimation of radial immersion ratio using cutting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. These force drops are equal to the cutting forces that act on a single tooth at the swept angle of cut and can be acquired from cutting force signals in feed and cross-feed directions. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting forces and predetermined ratio, the redial immersion ratio is estimated. various experiments show that the radial immersion ratio can be estimated by the proposed method very well.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.23-28
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• 2010

Resistance trimming and cutting processes of printed circuit board by making use of high power UV laser with nano-second pulse width have been proposed and investigated experimentally. Also laser-based application system with high flexibility and complex has been designed and adopted power controller, auto beam size control, auto-focusing and control program developed for ourselves. The function of each module shows that they can be reliable for industrial equipments. Resistance trimming method used a plunge and double cut process with $20{\mu}m$ spot size beam. Results show that double cut process is more effective to control resistance trimming in precision than plunge cut process.