• 한국농공학회지
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• 제44권4호
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• pp.85-98
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• 2002

The purpose of this study is to develop a land use planning model (LUPM) which can be applied to development of rural villages considering their spatial expansion. The LUPM finds out and allocates the new built site required for the improvement of existing villages. in the development of LUPM, CA (cellular automata) and land suitability analysis methods were applied combinedly. The model uses basically numerical data of CIS based on grid data. Agglomerated settlement, as a type of village for simulation, was adopted. Probability of land use change for optimizing development area was calculated by the six criteria: slope. drainage characteristic, direction of slope, as absolute suitability of grid itself, distance from road. distance from stream and distance from the village center, as relative probability by neighborhood cells. Weighting values of these criteria were quantified by AHP (analytic hierarchy process) method, which is one of MCE(multi-criteria evaluation) method. The algorithm of the model was verified by three example villages: an isolation village, a village with horizontal road, and a village with nodal point of cross road

• 전기학회논문지P
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• 제53권2호
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• pp.43-50
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• 2004

Percentage differential characteristic relaying(PDR) has been recognized as the principal basis for power transformer protection. Second harmonic restraint PDR has been widely used for magnetizing inrush in practice. Nowadays, relaying signals can contain 2nd harmonic component to a large extent even in a normal state, and 2nd harmonic ratio indicates a tendency of relative reduction because of the advancement of material. Further, as the power system voltage becomes higher and more underground cables are used, larger 2nd harmonic component in the differential current under internal fault is observed. And then, conventional 2nd harmonic restraint PDR exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for performance improvement of conventional protective relaying. This paper proposes an advanced protective relaying algorithm by using voltage-current trend and flux-differential current slope characteristic. To evaluate the performance of the proposed algorithm, we have made comparative studies of PDR, fuzzy relaying and DWT relaying. The paper is constructed power system model including power transformer, utilizing the WatATP, and data collection is made through simulation of various internal faults and inrush. As the results of test, the new proposed algorithm was proven to be faster and more reliable.

• 한국안전학회지
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• 제23권6호
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• pp.131-137
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• 2008

SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.

• 한국지반환경공학회 논문집
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• 제2권2호
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• pp.41-50
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• 2001

본 연구에서는 수위상승, 호안구조물의 증고 및 배면 준설투기 등 외적조건에 따른 ${\bigcirc}{\bigcirc}$항 호안구조물의 활동 및 측방유동에 대한 안정성 검토를 실시하고 기초보강 방안을 제시하였다. 안정성 검토를 위해 지반조사, 기본물성시험, 역학실험 및 화학성분분석을 실시하였고, 지반물성치는 주상개량체의 경우 지반개량 개념을 적용하였으며, 구조물 배면 준설매립의 경우는 단계별매립에 의한 영향을 고려하여 결정하였다. 안정성 검토는 기시공된 상태로 증고하지 않고 매립하였을 경우와 기시공된 상태로 증고하여 매립하였을 경우로 구분하여 실시하였다. 해석 결과 두가지 경우 모두 활동과 측방유동에 대해 불안정한 것으로 판단되어 기시공공법과 동일한 방법인 심층몰탈파일에 의한 추가보강을 실시할 경우에 대하여 그 안정성을 검토한 결과 안정하였다. 따라서 본 현장에 대한 기초보강공법으로써 심층몰탈파일을 제시하였다.

• 한국환경복원기술학회지
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• 제9권6호
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• pp.143-151
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• 2006

Currently, there are researches about environment-friendly road construction plans led by the Ministry of Construction and Transportation in progress. Therefore, in order to create the revegetation techniques of thin layer-soil combination media hydroseeding measures by actively using native herbs and native woody plants instead of using imported foreign grasses as a concept of sustainable environment-friendly land development, this thesis is going to identify problems that can appear when applying the thin- layer-soil-media hydroseeding measures by the suggested in the "Slope revegetation design and guidelines" proposed by the Ministry of Construction and Transportation, and to propose improvement plans for the problems.To this aim, a seeding mixture selection test was conducted by the goal of slope restoration, and a test group for artificial slope was created. As for a test for June sowing, it was intended to identify appropriate combination quantity by conducting a test that differentiates the combination quantity, and as for a test for September sowing, an artificial slope test was conducted by creating an artificial bank for earth and soil and applying 1~2cm and 3~4cm thickness after differentiating the seed combination volume and slope aspects.

• 농업과학연구
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• 제38권3호
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• pp.493-504
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• 2011

This study was carried out to safety evaluation, the practical application and improvement of design method of the agricultural reservoir due to raising embankments. Also, it was to compare and analyze the pore water pressure (PWP), seepage (leakage) quantity and piping phenomenon according to high water table and rapid drawdown. The seepage analysis by finite element analysis was used for steady state and transient condition. The pore water pressure distribution for steady state and transient condition showed positive(+) PWP on the upstream slope, it was gradually changed negative(-) PWP on the downstream slope. The PWP in the core ranged from 100 ~ -33 kPa, the seepage line in the incline-type core suddenly decreased towards the lower levels from the higher levels. The PWP according to rapid drawdown is remained in the vicinity of the upstream slope, therefore, it is investigated to be in an unstable state by the slope stability analysis. The PWP after raising embankments showed smaller than in the before raising embankments. It was likely to be the piping phenomenon because the gradients in the before raising embankments showed largely at downstream slope, and the stability for piping in the after raising embankments increased stable state. The seepage quantity per 1 day and the leakage per 100m for the steady state and transient condition appeared to be safe against the piping. It reduced slightly regardless of the transient condition before the raising embankments and it decreased largely about 2.4 times in the early days after the raising embankments.

• 한국수자원학회논문집
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• 제51권8호
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• pp.687-701
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• 2018

수자원의 추가 확보와 홍수에 대한 선제적 대응을 목적으로 국내 4대강 주요 지점에 다기능보(multi-function weir)를 설치하였다. 다기능보는 흐름 통제 단면으로서 정밀한 유량 산정이 가능한 수리구조물로 하천의 일반적인 수위-유량 관계식보다 정밀하게 산정할 수 있으며, 향후 각 유역의 국가 표준 유량 기준점으로 활용할 수 있는 방안을 강구하는 것이 바람직하다. 이에 본 연구에서는 영산강의 승촌보를 대상으로 현재 취득되는 운영 자료를 분석하여 개선사항을 제시하고, 이를 보완하기 위하여 간접유량추정 방법인 경사-면적법(slope-area method)을 응용하여 정밀한 유량 산정이 가능할 수 있는 방법을 제안하고자 한다. 분석 결과, 현재 상태는 이론적인 유량계수 범위 초과와 급격한 변동, 상 하류부의 수위차를 연동하지 못하는 등 이에 대한 보완이 필요하였다. 응용한 경사-면적법은 앞서 제시한 한계점을 보완하고, 자연 하도의 검증된 수리학적 이론에 의해 수면경사와 마찰손실을 반복 계산을 통해 오차를 줄여나가는 상호 보완적인 방법으로 물리적으로 타당하여 적용가능성을 확인하였다. 향후, 다기능보의 최적 운영을 위하여 이를 적용한다면, 실제 운영에 도움이 될 것으로 기대된다.

• 한국환경복원기술학회지
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• 제13권1호
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• pp.93-102
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• 2010

Greening sometimes fails because its method is not suitable for various site conditions, therefore the trend of selecting a revegetation method in Korea today is through test construction. However, due to enlargement, complication and diversification of domestic construction businesses, the importance of VE is gradually increasing as effective efforts over a whole life-cycle to obtain goals such as quality improvement and cost reduction, and not only quality and economic efficiency but also substantiality need to be considered in comparing revegetation methods. For this study, Sungnam~Janghowon (area1), where comparatively various slope revegetation methods are used, was selected the investigation site. The site was divided into three areas:blasting rock, ripping rock and earth sand. The revegetation methods used were six in the blasting rock area, five in the ripping rock area, and two in the earth sand region. 2007 monitoring data was analyzed, and Value (V) was calculated with LCC related ratio, and compared and contrasted with the evaluation of prior revegetation methods. Therefore it is believed that this analysis enables selection of the most appropriate method, unbiased towards one particular characteristic such as quality, vegetation growth and economy. When aiming for a durable effect, it shall be more efficient to select the most appropriate method focusing on LCC analysis, which deals with the economic aspect, as well as the design function aspect.

• 한국환경복원기술학회지
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• 제21권5호
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• pp.97-110
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• 2018

The purpose of this study is to provide basic data and evidence for the habitat improvement of wild birds in urban stream by analyzing changes in habitat characteristics of wild birds by riparian forest construction in Yangjae stream in Seoul. In Gangnam-gu, the multi layered riparian forest consisting of landscape trees and shrubs was formed on the slope. In Seocho-gu, the vertical vegetation structure of woody and herbaceous wetland plants was good. In Gangnam-gu, the vegetation area of the slope increased and the vertical stratification structure affected the species diversity of the forest birds. The number of species and individuals of plovers, sandpipers and wagtails decreased due to the impact of bicycle roads and trails. The poor forests on the levee slope in Seocho-gu affected the habitat selection and migration of the forest birds. The willows and amur silver-grasses formed in the riverside have been developed into the riparian forest, thus stabilizing the habitat of water birds by blocking disturbances from the influence of the trails.

• 한국소음진동공학회논문집
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• 제15권11호
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• pp.1248-1254
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• 2005

L/UL(Load/unload) mechanism has been widely used in SFF(Small form factor) HDD because L/UL technology has many advantages such as an increase of areal density, reduction of power consumption and improvement of shock resistance. In this system, the most important design goal is no slider-disk contact and fast air-hearing breaking during L/UL process. To do so, we should consider many design parameters related to L/UL system. The ramp shape is the most dominant component among parameters which dramatically affect the L/UL performance. This paper makes an advanced ramp model using ANSYS/LS-DYNA. Through this FE model, this paper investigates the effect of initial ramp slope and location of air-bearing breaking. From the experiment for three different ramps, we also verify that experimental results agree with simulation results. We conclude that the ramp design should have small ramp slope at the moment which a suspension tap contacts with ramp and large ramp slope after air-bearing breaking in order to improve L/UL Performance.