• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 춘계학술대회 논문집
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• pp.321-327
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• 1991

High power laser beams are used in a wide variety of materials processing applications such as cutting, welding, drilling and surface treatment. The CO$\sub$2/ laser is increasingly used in laser beam welding because of the highly potential advantages. High power laser welding is a high energy density, no filler metals and low heat input process to join metals. As the comparison with the conventiona welding, precision work and good fit-up to join the metals are required and maintenance is expensive at present. The principal variables of laser beam welding are the laser beam power, travel speed and bean spot size. The penetration depth during laser beam welding is directly related to the power density of the laser beam. Generally, for a constant beam size, the penetration depth increases with increasing laser beam power.

• 대한조선학회지
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• 제13권2호
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• pp.13-43
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• 1976

A potential flow approach is used to develop a method and an associated computer program for floating marine structures of general configuration in wave of all water depths with arbitrary heading. It computes the total force distributions and six degrees-of-freedom motion. The hydrodynamic-force equations and derived become identical under certain assumptions to the equations commonly used by the offshore industry, and the two methods are compared in detail. The computed motions of all six degree agree quite well with model-scale and full-scale experimental data for two typical semisubmersible drilling rigs in finite-depth water. Also the presented motion computations are more accurate than a previous work by the second approach. The present computations use experimentally validated or determined values of frequency-dependent hydrodynamic coefficients with the effects of the free surface and both finite and infinite water depths. The present method generates sufficient computation accuracy to use for practical design applications.

• 해양환경안전학회지
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• 제25권1호
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• pp.102-110
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• 2019

우리나라의 조선해양플랜트 산업은 2011~2015년 기간에 우리나라 품목별 수출기여도에서 1~4위를 차지할 정도로 대한민국 경제성장을 견인하는 중요한 산업이다. 이 연구는 과거 건조에만 치중했던 우리나라 해양플랜트 시추설비의 산업구조에서 통합시운전의 서비스 공급이 가능한 비즈니스 모델을 검토함으로써 시추설비 시장에서 우리나라 조선소의 국가경쟁력을 향상시킬 수 있는 방안을 제안하고자 하였다. 2014년에 시도된 주작-1 폐공을 활용한 시운전 서비스 모델과 이의 한계 사항을 극복하고 사업을 활성화하기 위한 새로운 제안 비즈니스모델인 수심 150미터급 시운전 전용 모델의 경제성을 검토하였다. 경제성 평가 결과, 수심 150미터급 모델이 경제적으로 더 효과적인 것으로 나타났다. 그리고 통합시추설비의 시운전이 연간 2회에서 3,4,5회로 늘어남에 따라 NPV와 IRR 및 B/C 비율이 모두 증가하였으며, 1회당 사용료는 감소하는 것으로 나타났다. 따라서 해양시추설비의 통합시운전 사업은 우리나라에서 건조되어 인도되는 설비를 대상으로 시추 시운전을 적극적으로 유치하는 노력이 필요하다.

• 기술사
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• 제17권3호
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• pp.32-49
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• 1984

The East gate station area is 205M long and 24m deep which is located 13 meter in front of cultural treasure east gate. The area to be excavated by blasting is composed of granite rocks from 10M depth to 25M. Surface earth extends to up 10M depth. This job site has in involves heavy traffic congestion such as over 10,000 cars passing in rush hour where clossing No 1 lint of subway running 3 minitues head way. This east gate station construction is to be executed for the provent of the setting down of underground level and blasting vibration effects to cultural treasure east gate. Therefore, the caltural treasure committee approved this execution subject to the following condition. 1. Subway gelogical foundation and measured natural frequency 2. Execution of water tight wall 3. Sellection and test of damping material for wall and under rail 4. Measurement of monitoring system during the execution 5. Measurement of histogram system The above two projects was carried out by Dr. Kwang team in KAIST and prof, Han in Hanyang University under accadamic study contract. In the blasting work, for the pourpose of reduced vibration and low explosion velocity such as CCR, Kovex slurry. The 2nd, used electrical caps shall be delay cap and M/S caps in multi delay. The 3rd, drilling pattern is bench cut in open cut and applied control blasting in tunnelling and also shall drill anti-vibration holes as line drilling.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2006년도 춘계학술발표회 논문집
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• pp.217-236
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• 2006

본 연구에서는 TBM의 면판 설계와 굴진성능 평가를 위한 기초 연구로 우리나라의 대표 암종인 황등 화강암에 대하여 LCM 시험기를 사용한 일련의 시험을 실시하였다. LCM 시험을 통하여 최적의 절삭 조건을 구하고 절삭 깊이와 커터 간격 등의 TBM 면판 설계인자가 굴진성능에 미치는 영향을 평가하고자 하였다 정확한 TBM 성능을 예측하기 위하여 기존 연구들에서 적용된 방법에서 탈피하여 3차원적인 절삭 부피를 정량적으로 측정하고자 하였다. 이를 위해 실시간 처리가 가능하고 정밀도와 정확도가 확보된 디지털 사진계측기법을 LCM 시험에 적용하였다. 또한 TBM 디스크 커터에 의한 암석의 절삭과정을 모사하기 위한 수치해석 기법의 적용성을 검토하기 위해 AUTODYN 2D를 적용하였다.

• 자원환경지질
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• 제5권3호
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• pp.133-144
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• 1972

The mine of our present concern is situated at Shim-ri, Gusan-myon, Changwon-gun, Kyongsang-namdo, with lattitude $128^{\circ}35^{\prime}{\sim}36^{\prime}N$ and longitude $35^{\circ}03^{\prime}{\sim}04^{\prime}E$. This mine has not been noticed until the intermittent geological survey for the ore deposits were initiated from September, 1967 till 1970. The main mineralized zones, No.1 and No.2 zones, were studied by the diamond drilling of 9 holes down to the total depth of 1,140m, and found to have ore reserves of Cu 1.99% ore, estimated to reach around $358,000{\frac{M}{T}}$ (proved $117,000{\frac{M}{T}}$, indicated $241,000{\frac{M}{T}}$), which triggered the new exploitation of this mine. Geological composition of the district near the mine is mainly from the andesite belonging to the Silla Series of Kyongsang System and the distribution is broadly spread. Ore deposits are the hydrothermal one, filling the shear zone formed alongside the andesite main joint. There are two stripes of copper bearing mineralized zone which are about 40~70 meters apart and parallel to each other, in addition to which two others are expected. The strike of the main mineralized zone lies at $N15^{\circ}{\sim}20^{\circ}W$, the dip at $60^{\circ}{\sim}70^{\circ}NE$. The principal components of the ore mineral are chalcopyrite, bornite and as secondary, cuprite, tenorite, azurite and malachite. Pyrite, magnetite, specular hematite, very little of galena, sphalerite, quartz, epidote, zoisite, chlorite and calcite are found as gangue mineral. Confirmed by the drilling, the main mineralized zone, No.1 zone, has the length of 320m, average width of 1.62m, Ag 26g/t, Cu 1.84% and the average width of the ore zone except the narrow barren andesite horse interposed in the mineralized zone is 1.32m with Ag 32g/t and Cu 2.26%. The mineralized zone No.2 is 340m long, 1.00m wide with Ag 30g/t and Cu 2.15%. Neglecting the barren andesite horse the width is 0.73m with Ag 42g/t and Cu 2.94%.

• Geomechanics and Engineering
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• 제31권3호
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• pp.249-263
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• 2022

The specially-shaped Polycrystalline Diamond Compact (PDC) cutter is widely used in drill bit design due to its advantages of high rock cutting efficiency, strong impact resistance and long service life in hard and abrasive formation drilling. A detailed understanding of rock cutting behavior of worn specially-shaped PDC cutter is essential to improve the drilling efficiency and decrease the drilling costs. In this paper, the theoretical models of two new principles (loading performance (LP) and cutting performance (CP)) are derived for evaluating the cutting process of worn specially-shaped cutter, the theoretical models consider the factors, such as cutter geometry, aggressiveness, stress state, working life, and rock cutting efficiency. Besides, the numerical model of heterogeneous granite is developed using finite element method combined with Voronoi tessellation, the LP and CP of 12 kinds of worn specially-shaped PDC (SPDC) cutters are analyzed. The results found that the mechanical specific energy (MSE) of worn cutters first increase and then decrease with increasing the cutting depth, and the MSE increase with the increase of back rake angle except for Conical cutter and Wedge-shaped cutter. From the perspective of CP, the worn PDC cutters are more suitable for the smaller cutting depths, and the back rake angle has little effect on the CP of the specially-shaped worn PDC cutters. Conical cutter, Saddle-shaped cutter and Ellipse-shaped cutter have the highest CP value, while Rhombus-shaped cutter, Convex cutter and Wedge-shaped cutter have the lowest value in selecting cutters. This research leads to an enhanced understanding of rock-breaking mechanisms of worn SPDC cutters, and provides the basis to select of specially-shaped PDC cutters for the specific target formation.

• 한국기계가공학회지
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• 제2권4호
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• pp.33-39
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• 2003

The stiffness of multi-articulated industrial robots is very weak, because their structure is an articulated type with some links and joints. Thus it is known that cutting processes for metals are not accepted in machine shop well, but they have a lot of merits for cutting processes, for example, drilling, tapping, and engraving etc, because of the characteristics of their high degree of freedom. The temptation of cutting aluminium was carried out to investigate the feasibility and the limitations or constraints for cutting metals on them. First the mode shapes of 6 degree of freedom welding robot were taken and analysed, and next the cutting processes were practically carried out on it. The results of study were found out to show the feasibility of cutting processes at drilling under 6mm of tool diameter, as well as to have some limitations and constraints, for examples, feed rate, depth of cut and cutting force etc.

• 한국정밀공학회지
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• 제26권10호
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• pp.108-115
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• 2009

Although nanosecond pulsed laser drilling and milling are rapid and non-wear processes in micromachining, the quality cannot meet the precision standard due to the recast layer and heat affected zone. On the other hand, electrical discharge machining (EDM) is a well-known high precision machining process in micro scale; however, the low material removal rate (MRR) and tool wear remain as drawbacks. In this paper, hybrid process of laser beam machining (LBM) using nanosecond pulsed laser and micro EDM was studied for micro drilling and milling. While the quality of the micro structure fabricated by this hybrid process remains as high as direct EDM, the machining time and tool wear can be reduced. In addition, variable depth of layer was introduced as an effective method improving efficiency of hybrid milling.

• 자원환경지질
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• 제20권4호
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• pp.261-271
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• 1987

Muguk gold deposits are composed of quartz veins emplaced along faults in Mesozoic granodiorite. General strikes and dips of the veins are $N15{\sim}20^{\circ}W$ and $70{\sim}80^{\circ}NE$. Associated ore minerals are pyrite, arsenopyrite, sphalerite, galena, chalcopyrite, pyrrhotite, native silver, argentite, tetrahedrite and electrum. Vein mineral paragenesis is complicated by repeated fracturing, but five distinct depositional stages can be recognized. Electrum grains are associated mainly with sulfide bands formed along both margins of pale pink quartz of stage 3, and with patches of pyrite aggregate of stage 4. Before the close down in 1972, Muguk gold mine yielded more than 8 tons of gold of which major portion was produced from the No.2 vein. No.2 vein, extending about 1,500m laterally, was exploited to a depth of about 750m. In 1984, Young-poong mining company acquired the mining property and began geologic mapping, geochemical and geophysical exploration, diamond drilling and exploration tunnelling around the mine area to seek for other rich gold-bearing quartz veins. As the Samhyungje vein was disclosed to be the most rich vein, exploration works were focussed on the Samhyungje vein. As of August 1987, 22,338m of diamond drilling and 9,652m of exploration tunnelling have been undertaken. Owing to the successful result of exploration, the Muguk mine commenced normal operation on January 1987, treating 5,500 tons of ore per month.