• 한국지반환경공학회 논문집
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• 제3권4호
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• pp.59-66
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• 2002

낙석방지울타리의 설계는 지반의 종류 및 사면경사 그리고 상부 및 하부지반조건을 고려하여 실시된다. 도로절개면에 설치되는 낙석방지울타리는 사면으로부터 발생한 낙석을 적절히 지지하여 도로로의 유입을 차단하기 위해 설치한다. 낙석방지울타리의 구조적 규격은 가정된 낙석에너지에 의해 산정되며, 낙석방지울타리의 흡수가능에너지는 구성요소인 철망, 지주 및 와이어로프 각각의 흡수가능에너지 합으로 규정하고 있다. 그러나 현장시험결과 적은 낙석에너지로도 경우에 따라서 낙석방지울타리가 지지하지 못하는 경우도 있었다. 따라서 본 논문에서는 현행 낙석방지울타리에 대한 설계기준의 문제점을 파악하고 이를 보완하기 위한 방법을 제안하고자 하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.527-532
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• 2010

Soil-cement has been broadly used for eco friendly pavement, slope protection and soft soil improvement since it used for the increase of soil strength with cement. Recently, additional agents are mixed with existing soil-cement so as to improve specific properties or functions such as strength, color and permeability of it. This study aims at figuring out the physical and mechanical properties of a soil-cement mixed with crashed oyster shell and loess. The study is specially focused on the applicability of oyster shell as an alternative material for sands. To have his objective achieved a series of uniaxial compression tests were conducted. As a result, it appears that usage of oyster shell may have effect on strength improvement of mixed soils.

• 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.

• 건설안전기술
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• 통권50호
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• pp.84-96
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• 2009

Road is typically constructed along ridge area of mountain because of topographical and economic reasons. Therefore, road may face lots of open cut slope which can easily cause rock falling. This study evaluates the structural safety of newly developed falling rock protection system which has a roof deck plate. The structural performance under self-weight, snow load and load from failing rock was investigated using a finite element numerical analysis method. From the analysis results, the H-beam space was limited not to exceed 2.2m. The deck plate was also safe under the examined loading condition. A hinge and connection in the system were investigated through detailed modelling and analysis. The results showed that the hinge was safe enough and that the connection should strengthened with appropriate stiffeners.

• 수산해양기술연구
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• 제28권2호
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• pp.216-227
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• 1992

The corrosion rate, behavior of corrosion fatigue and characteristic of cathodic protection for SB41 were investigated by corrosion and corrosion control tests in seawater at laboratory and coast. The main result obtained are as the following; 1) The corrosion rate of base metal (BM) is about 28-37 mg/dm super(2) day in seawater of coast. 2) The correlation between the stress intensity factor range $\Delta$K and crack propagation rate da/dN for weldment follows paris' rule in seawater : da/dN=C($\Delta$K) super(m) where m is the slope of the correlation, and is 2.02 for BM and 1.75 for heat affected zone (HAZ) respectively. 3) The corrosion sensitivity of HAZ is more sensitive than that of BM under the low region of $\Delta$K. 4) With increase of bared surace area of cathode, cathodic protection potential is increased sharply.

• 한국안전학회지
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• 제24권3호
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• pp.47-53
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• 2009

Road is typically constructed along ridge area of mountain because of topographical and economic reasons. Therefore, road may face lots of open cut slope which can easily cause rock falling. This study evaluates the structural safety of newly developed falling rock protection system which has a roof deck plate. The structural performance under self-weight, snow load and load from falling rock was investigated using a finite element numerical analysis method. From the analysis results, the H-beam space was limited not to exceed 2.2m. The deck plate was also safe under the examined loading condition. A hinge and connection in the system were investigated through detailed numerical modelling and analysis. The results showed that the hinge was safe enough and that the connection should strengthened with appropriate stiffeners.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.126-128
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• 2003

As a systematic approach to waste disposal site screening for groundwater pollution protection, the DRASTIC system developed by the US Environmental Protection Agency (USEPA) was introduced at Younggwang County in Korea. Hydrogeologic spatial databases for the system include info rmation on depth to water, net recharge, aquifer media, soil media, topographic slope, hydraulic conductivity and lineament. Using the databases, the DRASTIC system and a GIS, the regional groundwater pollution vulnerability of the study area was assessed. The fracture density extracted from lineament maps was added to the DRASTIC system to take into account the preferential migration of contaminants through fractures. From the results of the study, a degree of groundwater pollution vulnerability through the study area was easily interpreted, and waste disposal sites could be screened for groundwater protection.

• 한국환경복원기술학회지
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• 제9권1호
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• pp.112-120
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• 2006

It is possible to divide the historical changes of slope revegetation in Japan into five periods as follows; 1) The early period after creation(1927-1948), 2) The spreading period of modern revegetation work with manpower(1947-1958), 3) The spreading period of rapid revegetation technique using exotic grasses with machineries(1959-1985${\dots}$), 4) The spreading period of rapid reforestation technique by fast growing species mainly using leguminous shrub species(1986-1995${\dots}$), 5) The developing period of nature restoration technique using endemic arborous species(1996-). Recently main purpose of slope revegetation has been developing from the erosion protection to the nature restoration in the current of the 5th period. It is said that the role of the Japanese Society of Revegetation Technology(JSRT) is critical to the history of slope revegetation in Japan. 'The tentative guidelines of slope nature restoration' was announced by JSRT in 2004. In the guidelines, it was proposed that the planning techniques of using suitable seeds/plants based on the preservation level at the each construction sites. Moreover, the use of soil seed bank is the new and important study theme in the field of nature restoration. Consequently, at present the importance of advanced monitoring methods for vegetation maintenance and plant sociologic survey to evaluate the plant succession is increasing. Finally, some critical concepts are necessary to develop the field of restoration in Korea as follows; 1) monitoring of constructed sites, 2) ensuring of biodiversity, 3) recognition of slow revegetation and mosaic arrangement in revegetation, 4) reuse and recycle on the construction sites, and 5) promotion of specialist.

• Geomechanics and Engineering
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• 제12권4호
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• pp.723-738
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• 2017

Rock is a heterogeneous material, which introduces complexity in the analysis of rock slopes, since both the existing discontinuities within the rock mass and the intact rock contribute to the degradation of strength. Rock failure is often catastrophic due to the brittle nature of the material, involving the sliding along structural planes and the fracturing of rock bridge. This paper proposes an advanced discretization method of rock mass based on block theory. An in-house software, GeoSMA-3D, has been developed to generate the discrete fracture network (DFN) model, considering both measured and artificial joints. Measured joints are obtained from the photogrammetry analysis on the excavation face. Statistical tools then facilitate to derive artificial joints within the rock mass. Key blocks are searched to provide guidance on potential reinforcement measures. The discretized blocky system is subsequently implemented into a discontinuous deformation analysis (DDA) code. Strength reduction technique is employed to analyze the stability of the slope, where the factor of safety can be obtained once excessive deformation of slope profile is observed. The combined analysis approach also provides the failure mode, which can be used to guide the choice of strengthening strategy if needed. Finally, an illustrated example is presented for the analysis of a rock slope of 20 m height inclined at $60^{\circ}$ using combined GeoSMA-3D and DDA calculation.

• 한국환경복원기술학회지
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• 제2권3호
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• pp.83-92
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• 1999

To investigate the influence of forest road characteristics and site conditions on the stability of forest-road in granite area, four forest roads had been selected in Kyongbuk regions. The total of 13 road characteristic variables were evaluated by the discriminant analysis. The factors influencing the stability of forest road were bed rock, slope length, coverage, hardness, side-ditch erosion and road width. But aspect and soil texture were not significant for the stability in this area. In the correlation between forest environment and road structure, hardness and bed rock was highly significant in stability group, and coverage and side-ditch erosion was highly significant in instability group. 75 of 175 segments were instable whereas the others were stable. The centroids value by discriminant function in the stability and instability were estimated to 3.0585 and -1.9116, respectively. The stability criterion of forest road was discriminated from the centroids value of the each group. The main factors contributing the stability of forest road were significant in order of side-ditch erosion, coverage, soil texture, elevation, gradient, slope length and construction year. The prediction rate of discriminant function for stability evaluation of forest road was as high as 97.44%. In conclusion, the forest road structure factors such as length, coverage and slope gradient were controlled by construction techniques. If the factors like those should be considered in design, construction and forest road management, the stability of forest road may increase more. And also, it is necessary to take slope protection measures like small terraces and retaining walls for stability of cut slope.