• Journal of Korean Society of Rural Planning
• /
• v.17 no.2
• /
• pp.23-32
• /
• 2011

The purpose of this study is to produce basic planning criteria required in ecological restoration and improvement works of streams in rural area through the application of stream assessment methods (water quality, soil environment, and ecological function assessment) at 6 study sites of Han River basin. The investigation results were as followings; 1) There were the evaluation items like a manure use, salt degree, river peripheral tree, which did not fitted to apply to domestic streams, in the SVAP (Stream Visual Assessment Protocol) and NRCS Riparian Assessment that were evaluation models developed in USDA. The area inhabitants with a little knowledge and education personally seems to utilize the evaluation methods through improvement partly with an aspect that evaluation is slightly easy. 2) From the stream assessment results, the construction of diverse pools, large woody debris and isolated backwater pool are needed to improve a few of problems observed at the mostly study sites. The result of NRCS Riparian Assessment showed that the improvement of stream bank vegetative communities is needed by planting tree with deep-binding root masses, and managing of noxious weeds and exotic undesirable plants. 3) Summing up, the assessment results showed that the assessment scores were higher at upstream than downstream, the stream with totally maintenance than that with partly maintenance, the stream with slope bank than that with vertical bank, and the stream with a flood plain than that without a flood plain. So, the direction of stream maintenance projects must be set by consideration of those results.

• Journal of Biomedical Engineering Research
• /
• v.16 no.4
• /
• pp.543-554
• /
• 1995

This paper describes the improvement of driving stability and the control system for INMEL-VII which is motorized manual wheelchair to satisfy requirements of the disabled The INMEL-VI was based on high maneuverability of the omnidirection drive and safety But the results of field tests about two years showed some problems to the disabled in daily life such as driving stability, Pm switching noise, and rotation of motor without driving command on negative slope. To solve the problems due to an increased DC motor power and applied to direct connection method in INMEL- VII. It improved the driving circuits and set switching frequency to 5KHz to eliminate the switching noise caused by PWM control of DC motor, As compare with the INMEL-VI, INMEL-VII is improved in driving stability by transfer the weight center to forward. The results of field testing proved the improvement of the driving stability and software algorithm It has been estimated to have a hlgh practical use for powered walking aids to the disabled's daily life.

• Proceedings of the KOR-KST Conference
• /
• 1997.12b
• /
• pp.35-72
• /
• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were when derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement alternatives for utility pole accidents when a predetermined performance level is specified.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.7
• /
• pp.935-943
• /
• 1993

In this paper, robust recognition system for tilted facial image was developed. At first, standard facial image and lilted facial image are captured by CCTV camera and then transformed into binary image. The binary image is processed in order to obtain contour image by Laplacian edge operator. We trace and delete outermost edge line and use inner contour lines. We label four inner contour lines in order among the inner lines, and then we extract left and right eye with known distance relationship and with two eyes coordinates, and calculate slope information. At last, we rotate the tilted image in accordance with slope information and then calculate the ten distance features between element and element. In order to make the system invariant to image scale, we normalize these features with distance between left and righ eye. Experimental results show 88% recognition rate for twenty five face images when tilted degree is considered and 60% recognition rate when tilted degree is not considered.

• Journal of the Korean Geosynthetics Society
• /
• v.9 no.4
• /
• pp.27-37
• /
• 2010

Woven geotextiles (polyester mats) reinforcement is generally used to improve traffic ability, bearing capacity, and slope stability for embankment construction on soft ground. Cases of two high-strength woven geotextiles reinforcement layers are introduced in the present paper, which has been successfully constructed for rail road embankment on soft ground. According to the case results based on the limit equilibrium analyses of slope stability, the two high-strength woven geotextiles reinforcement layers on the soft ground can substantially increase the stability of the embankment by about 25%, improve the safety factor from 0.91 to 1.14, and significantly reduce the embankment construction duration at least 2 months. Therefore, the application of high-strength woven geotextiles is found to be useful for in-situ cases having the lack of construction duration and stability, as a soft ground improvement.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.5
• /
• pp.1383-1393
• /
• 2014

Recently, with rapid improvement in computer hardware and theoretical development in the field of computational fluid dynamics, high-order accurate schemes also have been applied in the realm of computational hydraulics. In this study, numerical solutions of 1D shallow water equations are presented with TVD Runge-Kutta discontinuous Galerkin (RKDG) finite element method. The transcritical flows such as dam-break flows due to instant dam failure and transcritical flow with bottom elevation change were studied. As a formulation of approximate Riemann solver, the local Lax-Friedrichs (LLF), Roe, HLL flux schemes were employed and MUSCL slope limiter was used to eliminate unnecessary numerical oscillations. The developed model was applied to 1D dam break and transcritical flow. The results were compared to the exact solutions and experimental data.

• Journal of the Korean Institute of Telematics and Electronics T
• /
• v.35T no.2
• /
• pp.6-12
• /
• 1998

Thin film SOI(Silicon-on-insulator) device offer unique advantages such as reduction in short channel effects, improvement of subthreshold slope, higher mobility, latch-up free nature, and so on. But these devices exhibit floating-body effet such as current kink which inhibits the proper device operation. In this paper, the SOI NMOSFET with a T-type gate structure is proposed to solve the above problem. To simulate the proposed device with TSUPREM-4, the part of gate oxide was considered to be 30nm thicker than the normal gate oxide. The I-V characteristics were simulated with 2D MEDICI. Since part of gate oxide has different oxide thickness, the gate electric field strength is not same throughout the gate and hence the impact ionization current is reduced. The current kink effect will be reduced as the impact ionization current drop. The reduction of current kink effect for the proposed device structure were shown using MEDICI by the simulation of impact ionization current, I-V characteristics, and hole current distribution.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.8 no.4
• /
• pp.43-51
• /
• 2005

Due to rapid and reckless economic development, natural resources of the national land have been damaged and polluted. Accordingly, the necessity for environment-friendly development has been on the rise and many have made efforts to assess the environmental value of the national land. This study divides the conservation areas by means of using relative elevation, slope, and development of housing land based on environmental evaluation of the national land. The relative elevation is obtained by the difference of altitude at the edge of the forest patch extracted from the land cover classification map based on the ridgeline, and the slope is obtained by environment-oriented land suitability analysis. The development of housing land is classified in accordance with the progress of each project. Twenty-six evaluation criteria are divided into five different grades using the minimal indicator approach and then sub-divided into ten grades by means of using the following two scenarios. The first one uses the weight of input materials while the second one relies on the size of patches that are emphasized in landscape ecology. Consequently, such a study demonstrated the following results. The method relying on the weight of input materials revealed the limitation of emphasizing input materials excessively, whereas the method of considering the size of patches resulted in the division of conservation areas that embody regional characteristics. This study is meaningful in that it classifies the conservation areas by reflecting the regional characteristics and the ecological values of animals and plants.

• Journal of Biosystems Engineering
• /
• v.5 no.2
• /
• pp.26-39
• /
• 1980

A study was investigated to find out the mechanical optimum conditions of power tiller-plow system on both paddy field and upland. Mathematical model was developed for the theoretical analysis of this system and the experimentation on the field was carried out with two different sizes of 5PS and 8PS power tiller equipped with rubber tire. 1) The relationship between the plowing depth and draft resistance of the power tiller-plow system was a quadratic function. 2) The minimum point of the specific draft resistance of the 5 PS plow was found at the smaller plowing depth than that of 8 PS plow, therefore we can find that the curved surface of 5PS plow bottom should be improved for the effective plowing operation. 3) As the improvement of the mechanical balance by the desirable change of the curved surface of plow bottom, the relative position of hitch point and dimension of plow beam would be realized, the 5 PS power tiller could be used to plow deeply (about 16-17cm). 4) The virtual acting point of the total draft resistance on the plow bottom approached to the land side as the plowing depth increased. 5) The resultant of vertical reaction force $R_2$ on the landside was increased with the plowing depth, while the vertical reaction force $R_1$ on the wheel was decreased as the slope angle of the body of power tiller increased. 6) For the effective plowing operations ; a) The slope angle of the body should be as small as possible. b) The diameter of the wheel should be as small possible. c) The horizontal and vertical distances $l_2, h_1$ between the wheel axis and plow bottom should be as large as possible. 7) To use the 5PS power tiller as the major unit of agricultural machinery, the curved surface of the 5 PS plower bottom and the mechanism of attachment between the power tiller and the plow should be changed as the indications of this study, and in addition to these, the new operation method of the field work should be developed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.2
• /
• pp.105-118
• /
• 2008

The newly developed analysis method for nanoindentation load-displacement curves are focused on not only obtaining elastic modulus and hardness values but also other mechanical properties, such as yield strength and strain hardening properties. Dao et al. developed a forward and reverse algorithm to extract the elasto-plastic properties of materials from the load-displacement curves obtained in nanoindentation test. These algorithms were only applicable for engineering metals (Poisson#s ratio 0.3) using the equivalent conical indenter of the Berkovich. However, the applicable metals are substantially limited because range of used in the finite element analysis is narrow. This study is designed to expand range of the applicable metals in the reverse algorithms established by Dao et al. and to improve the accuracy of that for extracting the elasto-plastic properties of materials. In this study, a representative strain was assumed to vary according to specific range of $E^*/{\sigma}_r$ and was defined as function of $E^*/{\sigma}_r$. Also, an initial unloading slope in reverse algorithms improved in this study was not considered as independent parameters of the load-displacement curves. The mechanical properties of materials for finite element analysis were modeled with the elastic modulus, E, the yield strength, ${\sigma}_y$, and the strain hardening exponents, n. We showed that the representative strain (0.033) suggested by Dao et al. was no longer applicable above the $E^*/{\sigma}_r$ of 400 and depended on values of $E^*/{\sigma}_r$. From these results, we constructed the dimensionless functions, in where the initial unloading slope was not included, for engineering metals up to $E^*/{\sigma}_r$ of 1500. These functions allow us to determine the mechanical properties with greater accuracy than Dao#s study.