• 한국기계가공학회지
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• 제18권9호
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• pp.17-22
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• 2019

A ship's propulsion system is a device to move the ship by means of the power transmitted from the ship's engine to the propeller. In this study, three propeller models, a, b, and c, are designed and their flows are analyzed. Same flows with the same material are applied to all three models. Flow analysis results differ according to the shape of flow model though these models are the same material. In all respects, model C is considered to be more rigid and efficient than models A and B. A propeller model optimized for the driving force and stability can be developed through this study result.

• 한국가시화정보학회지
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• 제20권2호
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• pp.63-69
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• 2022

In this study, we numerically simulate the condensational growth of micron-sized particles traveling through a pipe filled with humidified air. Using the finite volume method and Lagrangian particle tracking technique, the mixture of particle-laden flow with moist air in a T-juction pipe is simulated. The condensational growth of particles is calculated by considering the mass transfer of vapor in the air onto the particle surface. The results indicate that the growth rate of the particles increases as the relative humidity of air is higher. Furthermore, the placement of a porous media with low permeability in the pipe could enhance the degree of condensational growth.

• 한국융합학회논문지
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• 제10권6호
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• pp.185-190
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• 2019

본 연구에서는 다양한 물탱크의 형상에 따른 입출구의 유동 조건들에 따른 물탱크 내부에서 발생하는 유동특성을 전산 유체 역학 프로그램인 ANSYS CFX를 이용하여 분석하였다. 또한 다양한 물탱크의 형상에 따른 입, 출구의 유동 조건들에 변화를 주어 어떤 모델이 가장 효율적인지를 알아보았다. 모델 A, B, C에 같은 재질을 적용하였다. 유동해석 결과로서는 모델 B가 가장 좋은 유동의 속도를 보이고, 모델 C는 유동에 가해지는 압력이 가장 높은 것으로 나타났다. 이로써 물탱크가 제품의 형상에 따라 같은 재질을 가지더라도 그 유동 속도와 압력은 달라졌다. 따라서 본 유동해석 결과를 통하여 제품의 형상에 따라 유동의 흐름에 좋은 탱크를 개발 할 수 있다고 사료된다. 본 연구 결과를 토대로 유체 탱크의 형상에 따른 유동의 해석 데이터를 실생활에 융합하여 그 미적 감각을 나타낼 수 있다.

• 대한환경공학회지
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• 제39권4호
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• pp.180-185
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• 2017

안료 페인트 생산 업체 7개를 방문하여 제품 21개(안료 17개, 페인트 4개)를 시료채취 하였으며, 대형 온라인 판매상을 통하여 50개 제품을 구매하였다. 총 71개 제품에 대하여 EPA 7473 방법으로 수은 함량분석을 하였고, 물질흐름 분석을 위한 폐기물 내 수은함량은 타 연구(2010)의 안료 페인트 제조 업체에서 발생되는 분진 슬러지 폐페인트 38건의 수은 함량 자료를 사용하였다. 물질흐름분석은 제품 또는 특정 화학물질을 대상으로 하는 Micro 수준의 물질흐름 추적방식을 이용하여 흐름도를 작성하였다. 수은분석 결과, 71개 제품에서 0~0.25 mg-Hg/kg, 38개 폐기물에서 0.23~0.69 mg-Hg/kg으로 나타났다. 물질흐름을 살펴보면 유통단계의 수은흐름량이 연간 10.06 kg인데 반해 폐기되는 수은의 양은 25.27 kg으로 유통량 보다 폐기량이 더 높게 나타났다. 이는 제품과 폐기물의 시료채취 시기가 달라 발생된 현상으로 제품은 2014년도 제품, 폐기물은 2010년 분석된 자료를 사용하여 RoHS 등과 같은 규제의 영향으로 수은 함유 페인트 제품이 감소됨에 따른 것으로 판단된다. 현재 생산되는 제품 중 수은의 농도는 매우 낮고 페인트에 의한 수은의 유출은 미미한 것으로 판단된다.

• Design & Manufacturing
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• 제11권3호
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• pp.46-50
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• 2017

Press processing is one of the best machining methods capable of mass production, satisfying dimensional, shape and quality among the methods of processing a metal plate. Among them, Fine blanking is a method of obtaining a precise cross-section such as machining of the shear surface shape. In this research, Using SCP-1 and SHP-1 materials. The deformation behaviors of the material flow affecting the die height of the shear section in accordance with the position of the V-ring in the Fine blanking were compared and analyzed. Result of interpretation, It was confirmed that the force acts on the position where the material flow direction accurately forms the die roll that the material of SCP-1 is at a position of 1.5 mm and the material of SHP-1 is at 2.0 mm. As a result, it was confirmed that the state of fo1111ing the shear surface by the V-ring was excellent. Using analysis results, In the experiment, the height of the die roll was considered by applying The position of the V-ring was 1.5 mm in SCP-1 and 2.0 mm in SHP-1. As a result of comparing the height of the die rolls, the height values of the die rolls were different from each other, It has been considered that the tendency of the die rolls to coincide with each other. It is considered that the difference of the die roll height is caused by the pressure input of the V-ring. In this study, the deformation behavior of the material(In addition to the position of the V-ring, the flow direction of the material depends on the shape of the V-ring and the Indentation amount) is considered to be an important factor in determining die roll height.

• 콘크리트학회논문집
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• 제20권3호
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• pp.317-323
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• 2008

본 연구에서는 굳지 않은 콘크리트 및 유동 콘크리트의 흐름 거동에 관한 해석 시뮬레이션 모델의 개발에 관한 것으로, 입자법의 일종인 MPS법 (moving particle semi-implicit method)을 적용하였다. 콘크리트의 유동 현상을 점소성의 흐름 문제로 고려하였으며, 콘크리트 입자의 운동에 관한 지배방정식은 라그랑지 정식화의 Navier-Stokes 방정식과 질량보존의 법칙에 기초하도록 하였다. 굳지 않은 콘크리트의 점소성 흐름 구성관계의 정식화를 위하여 콘크리트는 부동 상태인 경우 고점성체의 유체로, 유동상태인 경우 항복응력 이후 점소성체의 유체로 모델링하였다. 개발된 모델을 이용하여 L-형 박스의 콘크리트 유동 시험에 대해 시뮬레이션 하였으며, 그 결과 예측된 흐름량은 실험의 흐름량과 잘 일치하는 것으로 나타났다. 개발된 입자법의 해석 모델은 점소성 유체의 운동현상에 기초하여 정식화 되어 콘크리트 입자의 유동 및 운동 현상을 잘 묘사해 주는 것으로 평가된다.

• 한국시뮬레이션학회논문지
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• 제7권2호
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• pp.17-32
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• 1998

The flow fields in Gas Bubble Driven Circulation Systems were numerically analyzed. In various gas flow rate and bubble size, the flow characteristics were predicted. Eulerian-Eulerian approach was used for the formulation of both the continuous and dispersed phases. The modification of the general purpose computer program PHOENICS code was employed to predict the mean flow fields, turbulent characteristics, gas dispersion, volume fraction. The predicted shows very satisfactory agreement with experimental results for all regions of ladle. The results are of interest in the design and operation of wide variety of material processing.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.311-316
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• 2002

The following results are achieved from a mortar flow test depending on stainless steel slag fineness, rate of replacement, and a research on material age compressive strength, strength activity index. 1. Flow is proportional to the stainless steel slag fineness. 2. Mixing stainless steel slag decreases compressive strength 3. Material age compressive strength has the maximum value when stainless steel slag fineness is 6000$cm^2$/g. 4. Material age 7day strength activity index satisfies KSCE 95-01 at all conditions except the case of fineness 8000$cm^2$/gㆍstainless steel slag rate of replacement 30%. 5. Material age 28day strength activity index satisfies KSCE 95-01 in case of stainless steel slag fineness 4000$cm^2$/gㆍrate of replacement 10%, fineness 6000$cm^2$/gㆍ10%, or 20%.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.324-328
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• 2003

The Magnetoeheological fluid has the properties that it's viscosity has dramastic changed under some magnetic fields therefore, Magnetorhlogical fluids has been used for micro polishing of the micro part( for example, a aspherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorhological finshing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fulid ate brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate f3r glass polishing lends support the validity of the approach.

• 한국안전학회지
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• 제8권4호
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• pp.120-126
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• 1993

This work was carried out to investigate the effects of solid mass flow rate, mean particle diameter and mesh number of screen packing material on minimum carrying velocity, which defined as the superficial gas velocity of the upper limit of chocking phenomenon. Vertical pneumatic conveying was studied on a 4.6cm 1. D. pipe, 180cm in length. Experiments were performed in both the empty and the screen-packed pipe. It was also examined the effect of superficial gas velocity, solid mass flow, mean particle diameter, and mesh number of packing material on pressure drop. Minimum carrying velocity in screen packed-pipe was lower than that in an empty pipe. besides minimum carrying velocity was decreased with increase in mesh number of screen packing material. The pressure drop In vortical packed-pipe was Increased with superficial gas velocity, mean particle diameter, and mesh number of screen packing material.