• 산업기술연구
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• 제30권A호
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• pp.17-23
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• 2010

Recently, a large number of open-pit mines are planning to change their mining method to underground types because the environmental concerns and legal regulations are increased with a rise in the standard of living. The K silica mine, which is one of them and located in Kyunggi province, is planning the establishment of a vertical shaft which will be used for ore-pass channel in their new glory hole mining method. This vertical shaft will be designed to join with a horizontal gangway excavated from the ground level. In this new mining system, the excavated ore particles will be stored inside a shaft and transported out with a help of a conveyor belt. Therefore the hang-up of ore particles in a shaft, the control of gate at the bottom of a shaft, the installation of dog-leg at the gate should be investigated identically. In this study, the PFC-2D code which is one of the discrete element numerical methods has been applied to simulate the particle flow mechanism in a shaft, and the optimum mine design has been proposed to maximize the productivity and to minimize the system damage.

• 산업기술연구
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• 제27권A호
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• pp.31-38
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• 2007

Recently produced concrete has a tendency to overcome environmental defects. Porous and planting Eco-concrete requires the neutralization process and enough void in concrete to contain water, to pass air freely, and provides necessary nutrients to vegetation roots. The biological environment in concrete is not suitable for planting because the concrete possesses strong alkali constituent of pH 11-13. This study evaluated the strength and serviceability of concrete as well as the chemical characteristics of concrete mixed by low-grade iron ore left in the abandoned mine and treated by Ammonium monohydrogen phosphate, $(NH_4)_2HPO_4$. Test variables include two kinds of coarse aggregates such as crushed stones and low-grade iron ore, the duration time and the period for neutralization treatment by Ammonium monohydrogen phosphate, $(NH_4)_2HPO_4$, and the proportion ratio of cement, blast furnace slag and silica fume.

• 한국항해학회지
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• 제25권4호
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• pp.407-415
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• 2001

In the present study, irregular disturbances to ship dynamics is proposed, where irregular disturbances implying irregular wave and the fluctuating component of wind for the evaluation of automatic steering system of ship in following seas. Prediction method based on the principle of linear superposition. Irregular wave disturbances in following seas is calculated by frequency variation method. The mathematical model of each element of an automatic steering system is derived, which takes account of a few non-linear mechanisms. PD(Proportional-Derivative) controller and low-pass filter with a weather adjustment are adopted to modelling the characteristics of an autopilot. Performance index is introduced from the viewpoint of energy saving, which derived from the concept of energy loss on ship propulsion. Finally, the present methods are applied to two typical types of ship ; an ore carrier and a fishing boat. The various effects of control constants of autopilot on propulsive energy loss are investigated

• 한국철도학회논문집
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• 제8권6호
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• pp.581-585
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• 2005

In this study, the environmental impacts of a bogie in the electric motor unit(EMU) were evaluated quantitatively using simplified life cycle assessment(S_LCA). Target was the bogie and life cycle inventory(LCI) database for the bogie was established. The software used for simplified LCA was PASS. Environmental impacts with the parts of the bogie were dependent on their weight significantly. Among impact categories, abiotic resource depletion(ARD) and global warming(GW) were shown dominantly. Global warming was occurred mainly due to the emission of CO₂released from energy consumption and abiotic resource depletion was caused mostly by the consumption of iron ore for the manufacturing of steel. Therefore, the environmental impacts of the bogie could be reduced by the light-weighting of EMU and the improvement of energy efficiency.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2009년도 공동학술대회
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• pp.535-537
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• 2009

대형원료 운반선(원유선, 광탄선 등)의 해양오염사고를 줄이기 위하여 주요항로 및 통항로 상의 천수구역, 긴급 위험물 및 위험지역에 기존 AIS Base Station을 활용한 가상항로표지(Virtual AtoN AIS)를 설치하여 일반선박(소형)의 통항에는 장애물로 작용하지 않고 대형선의 AIS, ECDIS 및 레이더상에 위험요소임을 알려준다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1996년도 The Korean Institute of Navigation 1996년도 춘계학술발표회 논문집
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• pp.77-92
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• 1996

When an automatic course-keeping is concerned as is quite popular in modern navigation the closed-loop steering system consists of autopilot device power unit (or telemotor unit) steering gear magnetic or gyro compass and ship dynamics. The consideration of irregular disturbances to ship dyanmics and a few non-linear mechanisms involved in the system inevitably or artificially are known to be very important in properly evaluating or analyzing the automatic steering system. In the present study the mathematical model of each element of an automatic steering system is derived which takes account of a fex non-linear mechanisms. PD(Proportional-Derivative) controller and low-pass filter with a weather adjustment are adopted to modelling the characteristics of an autopilot. The calculation method of imposing irregular disturbances to ship dynamics is proposed where irregular disturbances implying irregular wave and the fluctuating component of wind. For he evaluation of automatic steering system of ships in the open seas an important term "performance index" is introduced from the viewpoint of energy saving which derived from the concept of energy loss on ship propulsion. Finally the present methods are applied to two typical types of ship ; an ore carrier and a fishing boat. The various effects of linear and/or non-linear control constants of autopilot on propulsive energy loss are investigated to validate and clarify the present smulation technique.

• 한국정보처리학회논문지
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• 제3권4호
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• pp.992-1001
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• 1996

레딕스 정렬 방식은 알고리즘이 단순하며 하드웨어 구현이 비교적 용이하다는 장점이 있으나, 정렬할 데이터를 2회의 탐색과정을 통해 논리 정보 0과 1을 구분 저장 한다는 단점이 있다. 본 논문은 레딕스 정렬에 있어 2회의 탐색을 1회로 줄이고 논리 0의 정보는 하위 주소로 부터 오름차순으로, 논리 1의 정보는 하위 주소로부터 내림차 순으로 저장하도록 하여 분류 소도를 높이는 새로운 알고리즘을 개발하고 이를 하드 웨어로 구현 한 후 그 실험 결과에 대하여 설명한다. 구현된 하드웨어는 별도의 메모리, 레지스터, 카운터, 비교기 등으로 구성된다. 본 논문의 시뮬레이션에서 소프 트웨어 방법은 8비트 데이터 만개를 정렬하는데 54.9ms가 소모되고, 하드웨어 방법은 5.3ms의 시간이 소모되었다.