The brittleness of rock is known to be an important property that affects the fragmentation characteristics in mechanized cutting. As interaction between cutting tool and (i.e., cutter forces, efficiency, s/p ratio, abrasivity) during mechanical strongly influenced by fragmentation, tools disc pick cutter) experience different behaviors depending on brittleness. In this study, relationships abrasivity rock, efficiency a Tunnel Boring Machine (TBM) were investigated for Korean types. was...

Pore-scale modeling with a reconstructed rock microstructure has become dominant technique for fluid flow characterization in thanks to technological improvements X-ray computed tomography (CT) imaging. A new method the construction of pore channel model from micro-CT image analysis is suggested improve computational efficiency by simplifying highly complex structure. Ternary segmentation was applied through matching volume experimentally measured mercury intrusion porosimetry CT voxel...

Vacuum laser beam welding (VLBW) exhibits better characteristics, e.g., deep penetration, less pore, and spatter generation, compared with the conventional technique under atmospheric pressure. Low ambient pressure affects vaporization temperature of base material interaction between plasma plume, which behaviors laser-induced keyhole, weld pool flow. This review introduces improvements in characteristics such as penetration depth, generation VLBW process. The effect on was reviewed,...

In this study, a new digital technique for the analysis of mechanical aperture and contact area rock fractures under various normal stresses is proposed. The requires point cloud data upper lower fracture surfaces, pressure film image fracture, deformation as input data. Three steps algorithms were constructed using these data: (1) primary matching algorithm that considers shape surfaces; (2) secondary uses images; (3) translation fracture. applicability proposed was investigated natural...

Vacuum laser beam welding enables deeper penetration depth and stability than atmospheric pressure welding. However, contaminated coupling glass caused by fumes in the vacuum space reduces transmittance, leading to inconsistent depth. Therefore, a well-designed protective system is indispensable. Before designing system, contamination phenomenon was quantified represented index, based on transmittance. The index behavior were determined be inversely proportional. A cylindrical with shielding...

암석 절리면의 거칠기는 대부분 2차원 프로파일의 기하학적 특징에 초점을 맞추어 기술되어 왔다. 그러나 거칠기를 합리적으로 평가하기 위해서는 수직 및 전단하중하에서 실제 접촉 상태에 놓여 발현되는 유효 거칠기 특성을 적절히 반영할 수 있어야 한다. 본 연구에서는 편마암 인장 절리의 복제 시험편에 직접전단시험을 수행하고 전단 방향에 따른 강도 고찰하였다. 이 과정에서 3차원 형상을 삼각형 요소의 집합으로 재구성하고, 각 활성, 비활성 미세거�s각을 이용하여 정의하였다. 수치적 알고리즘을 최대전단강도 발현 시 접촉면의 위치와 면적을 예측한 결과, 분포는 미세 거�s각의 분포와 밀접한 관계를 보였으며, 활성거�s각을 갖는 요소만이 거동에 주도적인 역할을 수행하였다. 따라서 활성거�s각의 분포 모사할 있는 확률밀도함수를 제시하고, 얻어지는 활성거칠 기계수 <TEX>$C_r$</TEX>을 새로운 정량화 계수로 제안하였다. 대한 전단방향에 <TEX>$C_r$</TEX>과 실험 결과를...

Vacuum laser beam welding utilises the advantages of both and electron welding. In this study, a numerical model was developed to simulate fume particle behaviour contamination coupling glass through which irradiates vacuum chamber. Supplying proper flow rate shielding gas suppresses infiltration particles into protective system prevents rising fumes inside system. The high momentum supplied could discharge out horizontally deflect away. showed good agreement with experimental results,...

Rock masses characterized by low permeability (e.g. crystalline rocks) have been considered as natural barriers in the deep geological disposal of high-level radioactive waste. Therefore, groundwater flows within are typically governed spatial distribution fractures rock mass. This study focuses on introducing an experimental system designed to evaluate hydro-mechanical properties barriers. allows experiments fracture specimens employing fluid injection under true triaxial compression...

Cleaning effect is well known mechanism of oxide layer removal in DCEP polarity. It also that DCEN has higher heat input efficiency than GTAW process. Based on these two renowned arc theories, conventional variable polarity for aluminum welding was set up to have minimum and maximum duty ratio achieve the highest weldability increase. However, recent several GTA research papers reported unexpected result proportional relationship between input. The authors observed same then suggested...

In vacuum laser welding, a beam is irradiated into chamber through coupling glass exposed to contamination. A conical protective system for the suggested, and contamination analysed via simulation experiments based on component height gas flow rate. Stable descending key suppressing contamination, which affects particle ascending velocity, horizontal deflection of particles number residual particles. The transmission area can be protected using rate 1.0 L min−1 or cone 90 mm component....

The importance of emotional quality car is getting higher in these days. Noise takes great portion because it detectable problem with just a few rides. sources noise during operation are various and the related technical issues vast. Sometimes weldments auto body referred as source suspicious weldment shows unsatisfactory welding most cases. In this research, cases making investigated to figure out solution for improvement. They categorized into several groups according inferred types error...