• Geomechanics and Engineering
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• 제30권5호
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• pp.423-435
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• 2022

Ground vibration generated repeatedly in blasting tunnel excavation sites is known to be one of the major hazards induced by blasting operations. Various studies have been conducted to minimize these hazards, both theoretical and empirical methods using electronic detonator, the deck charge method, the center-cut method among others Among these various existing methods for controlling the ground vibration, in this study, we investigated the cut method. In particular, we analyzed and compared the V-cut method, which is commonly used in tunnel blasting, to the double-drilled parallel method, which has recently been introduced in tunnel excavation site. To understand the rock fragmentation efficiency as well as the ground vibration controllability of the two methods, we performed in-situ field blasting tests with both cut methods at a tunnel excavation site. Additionally, numerical analysis by FLAC3D has been executed for a better understanding of fracture propagation pattern and ground vibration generation by each cut method. Ground vibration levels, by PPVs measured in field blasting tests and PPVs estimated in numerical simulations, showed a lower value in the double-drilled parallel compared with the V-cut method, although the exact values are quite different in field measurement and numerical estimation.

• 한국터널지하공간학회 논문집
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• 제4권4호
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• pp.287-300
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• 2002

터널굴착 발파기술로 새로 개발된 Composition Presplitting Angle Cut (COPA)은 기존 공법과는 달리 심발부에 먼저 인장파괴를 통하여 선균열 (사전절단)을 형성시킨다. 본 연구에서는 선균열 효과를 검증하기 위하여 굴진효율과 소음 진동의 발생크기를 측정하는 현장시험을 실시하였다. 그리고 이 공법의 경제성 및 작업성 (시공성)을 비교하기 위하여 동일한 조건에서 기존의 발파공법을 동시에 시험하여 그 결과를 비교하였다. 시험 결과 COPA - Cut 발파공법이 기존 발파공법보다 굴진효율이 증가하고 소음 진동이 감소되었다. 또한 경제성, 시공성 및 품질관리 측면에서 우수하다는 것을 확인 되었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.518-522
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• 2011

Cartesian grid system has mainly been used in the casting simulation even though it does not nicely represent sloped and curved surfaces. These distorted boundaries cause several problems. A special treatment is necessary to clear these problems. A cut cell method on Cartesian grids has been developed to simulate three-dimensional mold filling Cut cells at a cast-mold interface are generated on Cartesian grids. Governing equations were computed using volume and areas of cast at cut cells. In this paper, we propose a new method that can consider the cutting cells which are cut by casting and mold based on the patial cell treatment (PCT). This method provides a better representation of geometry surface and will be used in the computation of velocities that are defined on the cell boundaries in the Cartesian gird system. Various test examples for several casting process were computed and validated. The analysis results of more accurate fluid flow pattern and less momentum loss owing to the stepped boundaries in the Cartesian grid system were confirmed. We can know the momentum energy at the cut cell is conserved by using the cut cell method. By using the cut cell method. performance of computation gets better because of reducing the whole number of meshes.

• 화약ㆍ발파
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• 제25권1호
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• pp.31-43
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• 2007

현재 대부분의 국내 터널은 천공발파 기법을 이용하여 굴착되고 있다. 심발발파는 터널굴착면의 1 자유면 상태에서 가장 먼저 발파가 이루어지므로 터널발파에서 가장 중요한 단계이며 전체의 굴진효율과 진동 및 소음을 결정하는 역할을 한다. 여기서는 기존의 V-Cut 공법의 시공 편의성을 최대한 활용하면서 굴진효율을 개선시킨 새로운 심발발파 방법인 SAV-Cut (Stage Advance V-Cut) 공법을 소개한다. SAV-Cut 공법은 건설교통부에서 지정하는 건설 신기술(제518호)으로서 중앙공을 천공 및 선기폭하여 암반을 약화시킨 다음 경사공을 단계별로 기폭하는 것을 주요 특징으로 하고 있다. SAV-Cut 발파공법의 메커니즘을 수치해석과 여러 현장에 실제 적용을 통하여 검증하였고, 발파효율의 증대와 진동저감 효과를 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 사면안정학술발표회
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• pp.33-42
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• 2003

Since the cut slope has been big concern due to frequent failures, the government decided to include cut slopes in the“Act for Safety Control of Public Structures”. Based on the Act, the cut slope whose height is over 50m and length is over 200m should be inspected on the regular basis. According to the Act, KISTEC developed the objective evaluation method for the condition of cut slope. The evaluation method is divided into two categories: evaluation for damaged condition and evaluation for failure affecting factor. Based on the evaluation results, the cut slope is graded from A to E. In this study, the process to evaluate the cut slope condition and the evaluation criteria to divide the grade of cut slope are introduced.

• 터널과지하공간
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• 제4권3호
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• pp.237-249
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• 1994

A new type of cut method, called SK-cut, was developed in order to overcome the shortcomings of the conventional V-cut and Burn-cut blasting methods. Total 190 times of test blasts were performed for the evaluation of the efficiency of new blasting method. V-cut, Burn cut and SK-cut were compared by applying them to the excavation of main gallery and construction tunnel of underground oil storage cavern. Test results showed that excavation efficiency of the new method was increased by 5.9~9.8% and that specific charge was reduced to 71~92%.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1522-1529
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• 2009

When a shaft is excavated in Korea, the mechanized method such as RBM(Raise Boring Machine) or RC(Raise Climber) is used independently of depth. But usually, the mechanized method is useful for the deep depth. On the contrary, when the depth of shaft is short, the cost of excavation increase. So in the case of shaft constructon less than 100m, we need to consider more suitable method of shaft construction such as Stage-cut which is one of blasting methods. Stage-Cut is widely used in the field of shaft construction in Japan as a tool of rock excavation. The main purpose of this study is to provide technical guidance for design and construction of shafts in rock, using Stage-cut method which is suitable for 20m~80m depth shaft. In this study, Blasting tests was performed in field, according to rock classification. Finally, the stage-cut method which is suitable for the geology of Korea was developed.

• 복식문화연구
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• 제20권4호
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• pp.594-603
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• 2012

This study aimed to investigate a bias pattern making method with geometrical approach. The bias-cut dress has soft silhouette of drape in the garment. However, the bias cut dress has problem of satisfying the intended garment size spec. This problem occurs from various sources. The main reason is that the bias-cut fabric tends to stretch on longitudinal direction and to shrink horizontal direction when it was hung on the body. The goal of this study was to develop a bias-cut dress pattern making method satisfying the intended garment size spec. The researchers developed the geometrical method of measuring dimensional change by calculating the compensation ratio of the fabric in true bias direction. The compensation ratio was calculated by applying draping ratio of the fabric. Three types of fabrics were used in the experiment. The warp and weft crossing angle of fabric was ranged from $78^{\circ}$ to $82^{\circ}$. The fabrics stretched longitudinally 6.9~9.9% and shrank horizontally 7.2~11.0%. The compensation ratio of the bias-cut pattern for sample dress was calculated for each fabric type. Two types of experimental bias-cut dress patterns were developed for each fabric. One pattern was made with applying full compensation ratio and the other one made with applying partial ratio of the fabric. Experimental dresses were made with these patterns. The results of the evaluation showed that the bias-cut dress pattern applying the partial compensation ratio was more appropriate than the pattern applying the full compensation ratio.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.245-248
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• 2005

During manufacturing thick composite cylinders, large thermal residual stresses are developed and induce catastrophic interlaminar failures. Since the residual stresses are dependent on many process parameters, such as temperature distribution during cure, cure shrinkage, winding tension, and migration of fibers, calculation of the residual stresses is very difficult. Therefore a radial-cut method have been used to measure the residual stresses in the composite cylinders. But the conventional radial-cut method needs to know numerous material properties which are not only troublesome to obtain but also vary with change of fiber arrangement during consolidation. In this paper, a new radial-cut method with cut-cylinder-bending test was proposed and the measured residual stresses were compared with calculated thermal residual stresses. It was found that the new radial-cut method which does not need to know any of material properties gave better estimation of residual stresses regardless of radial variation of material properties. Additionally, interlaminar tensile strength could be obtained by the cut-cylinder-bending test.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.45-54
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• 2013

In this paper, a theoretical weight-reduction method was suggested to substitute an underframe material of a box-type bodyshell having cut-outs with an alternative light-weight material. To utilize the material substitution method previously developed for a box-type hybrid bodyshell not having cut-outs, we derived a box-type baseline model without cut-outs which is similar to the stiffness condition of a box-type bodyshell having cut-outs. To do this, the thicknesses of roof and walls of the baseline model were determined such that the deflection of the baseline model under a distributed vertical load condition is equal to the sum of the theoretical section deflections of the original box model with cut-outs. Next, to derive a hybrid bodyshell by under-frame material substitution, the material substitution method for a box-type hybrid bodyshell without cut-outs was applied to the box-type baseline model. Finally, we compared the FE simulation results of the derived hybrid bodyshells having cut-outs for various materials with the theoretical results of the suggested method, and we obtained their good correlations.