• The Korean Journal of Rheology
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• v.5 no.1
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• pp.49-64
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• 1993

사출성형충전공정에서 금형구조가 단섬유배향에 미치는 영향을 예측하기 위하여 수 치모사 프로그램을 개발하였다. 유한요소 /관찰 부피 방법에 복잡한 금형에서의 유동을 해 석하고 섬유와 섬유간의 상호작용을 고려한 섬유배향텐서 변화식을 이용하여 입자 추적법으 로 섬유배향분포를 구하였다. 수치모사 결과 금형 옆벽면과 내부 방해체의 주위에 있는 섬 유들이 전단변형의 영향으로 그들주위를 따라서 정렬되려는 경향을 보였다, 두 유동이 내부 방해체를 지나 접하면서 생성된 웰드라인을 따라서 단섬유들이 정렬되려는 경향을 나타내엇 다. 그리고 수축유동에서는 흐름방향으로 정렬되나 확장유동에서는 흐름방향에 수직으로 배 열되려는 경향을 확인하였다. 위아래 벽에 의한 전단변형의 영향으로 서로 다른두 배향구조 를 보여주는 skin-core 구조를 두께방향의 속도구배를 고려한 수치모사를 통하여 예측할 수 있었다. skin구조에서는 섬유들이 흐름방향으로 정렬되고 core 구조에서는 흐름방향에 수직 으로 배향되는 것을 확인하였으며 섬유상호계수값이 커질수록 임의 배향화하는 경향을 보였다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1997.10a
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• pp.93-98
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• 1997

도시폐기물의 효율적인 소각 처리를 위해서 폐기물 처리량 50 ton/day의 화격자 소각로를 대상으로 화학반응을 고려하여 연소실 내부의 열유동 현상을 전산모사하였다. 수치해석 프로그램으로 상용코드인 PHOENICS를 사용하여 3차원 모사를 하여 실험으로 파악할 수 없는 연소실 내부의 유동 및 폐기물과 산화제와의 반응을 계산하였다. 건조부, 주연소부, 후연소부에 1차연소용공기, 연료의 분포 및 폐기물의 발열량이 노내 열유동 현상에 미치는 영향을 조사하였다. 1차연소용 공기의 분포에 따라 노내 유동장의 형태에 변화가 있었으며, 벽면에서의 복사열전달을 고려한 경우 2차연소실과 출구근처에서 온도분포가 파일롯트 플랜트 실험결과와 잘 일치하는 r서으로 나타났다.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.130-140
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• 1997

원형주상체 주위의 유동을 규명하기 위해 회류수조에서 원주방향으로 24개의 위치에 대하여 압력을 계측하였으며, laser sheet을 이용하여 유동을 가시화 하였다. Reynolds수가 4800에서 40000인 범위에 대하여 실험을 수행하였다. 또한, 원형단면체 주위의 비정상 층류유동에 대한 Navier-Stokes방정식의 해를 구하는 수치해석기법을 개발하였다. 효과적인 격자배치를 위하여 H와 O-type의 중첩격자를 사용하였고, 이산화 방법으로는 정규격자시스템에서 유한차분법을 적용하였다. 실험과 수치해석결과에서 뚜렷한 와류박리현상을 볼 수 있었으며, 압력계수 (C$_{p}$ ), 항력계수(C$_{D}$), 스트로얼수(St)를 정량적으로 비교하였을 때, 비교적 잘 일치하는 것을 확인하였다.다.

• Resources Recycling
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• v.6 no.1
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• pp.17-22
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• 1997

An electromagnetic fluidized bed was proposed for the continuous separation of magnetic particles from the fine a admixtures with nonHmagnetic particles. The effects of operating variables on the magnetic fraction in the separated p particles were examined, including superficial gas velocity, mixing fraction of magnetic particles (= 100-mixing fraction of n non-magnetic particles) in the admixture, and electric current supplied to the electwmagnet. It was found that the s separation was possible when a magnetic force formed by the electromagnets works on the magnetic particles over the hydrodynamic force caused by a gas stream for fluidizing the fine admixture.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.303-304
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• 2022

파이프는 기계, 전자, 전기, 플랜트 등 많은 산업 분야에서 응용기기로 널리 사용되고 있으며, 소방, 화학 등 안전 관련 분야에서도 널리 사용되고 있다. 제품의 다양화에 따라 배관 분야에서도 기술의 중요성이 높아지고 있다. 특히 기존 동관을 스테인리스강으로 변경하는 경우 구조해석이나 유동 해석을 통해 안전성과 유동특성을 평가할 필요가 있다. 자체 개발한 일체형 인서트형 커넥터인 6.35 소켓 모델의 유동 안전성은 CFD 해석을 이용하여 유동유발진동(FIV)평가 과정의 4단계를 통해 진행하였다. 배관계 벽면에 작용하는 압력변동의 진폭은 3,780Pa이하의 수준으로 형성되며, 이는 냉매 배관의 운전압력이나 설계응력과 비교했을 때 매우 작은 수준의 압력으로, 난류에 의한 진동이 배관의 구조안전성에 미치는 영향은 미미한 수준인 것으로 나타났다.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.58-65
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• 2017

Fluidized bed gasification is technically and economically proven technology, which shows the high possibility of realization and commercialization. However, in Korea, development of FBG to the commercial scale for power generation and industry is mainly blocked by the fact that there is no experience of design, troubleshooting and operation of even pilot scale fluidized bed gasifier. In this study, a $3MW_{th}$ circulating fluidized bed(CFB) was newly developed for biomass gasification. The fluidized bed was mainly composed of circulating and bubbling fluidized reactors integrating in-situ tar removal step in the system. For cleaning of the tar and acid gas in the product gas, the sequential gas cleaning process comprised of a ceramic filter, rapid quencher and wet scrubber was adopted. Effect of equivalence ratio was investigated to find the optimal operating conditions for the $3MW_{th}$ integrated system of fluidized bed gasification.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.35-45
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• 2018

Imaging technologies are applied at various geological scales including pore scale, core scale and intermediate scale in order to characterize pore space of rocks as well as to map the fluid distribution in porous media. This technical report presents experimental results using core-flooding apparatus suited with imaging technology. Three different core samples, that are homogeneous, fractured and heterogeneous cores, were used to assess the two-phase fluid migration behavior as $CO_2$ displaces resident brine. We show that imaging technology can be effective in characterizing salt-precipitation, capillary pressure and spatio-temporal variation of trapping mechanisms.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.495-501
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• 2013

This paper describes a flexible wireless telemetering system using a mesoscale cantilever sensor, which is microfabricated with a patterned thin Ni-Cu foil on a resin substrate. The dynamic validation of the sensor has been conducted in a flow. The wireless telemetry is used to obtain data regarding the oscillating flows. It is shown that the sensor is nearly independent of the environmental temperature and is suitable for application to primary healthcare and diagnostic devices. It can be easily integrated with other modules for measuring physiological parameters, e.g., blood pressure, oxygen saturation, and heart rate, to increase the convenience and reliability of diagnosis. The precision and reliability of the sensor are also dependent on the design of the analog front-end and noise reduction techniques. It is shown that the present system's minimum interval between packet transmissions is ~16 ms.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.846-853
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• 2017

Cold bed and $30kW_{th}$ pilot bed tests using circulating fluidized bed (CFB) were conducted to apply oxy-fuel technology for waste sludge combustion as a carbon capture and storage technology. In cold bed test, the minimum fluidization velocity ($u_{mf}$) and superficial velocity for fast fluidization was determined as 0.120 m/s and 2.5 m/s, respectively. In the pilot test, air and oxy-fuel combustion experiments for waste sludge were conducted using CFB unit. The flue-gas temperature in 21~25% oxy-fuel combustion was higher than that of air and up to 30% oxy-fuel combustion. In addition, the concentration of carbon dioxide was more than 80% with the oxygen injection range from 21% to 25% in oxy-fuel CFB waste sludge combustion.

• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.329-336
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• 1980

A domestic phosphogypsum was calcined in a batch type fluidized bed reactor at various reaction temperatures ranging 90∼180$^{\circ}$ without and with an alkaline additive amounting up to 5% of gypsum, and physical properties of the resultant products were compared following their characterization by X-ray diffraction pattern and DTA. It has been found that dehydration reactions were uniformly carried out in the fluidized bed reactor and only hemihydrate was obtained at 90$^{\circ}$ whereas at higher temperatures dehydration reaction progressed further. When gypsum was charged to the reactor preheated at over 140$^{\circ}$, a considerable degree of dehydration occurred before the reactant reached the initially set reactor temperature and in particular, at over 160$^{\circ}$ most of dehydration reaction was performed prior to the present reactor temperature. However, it has been found that gypsum mostly transforms into hemihydrate around the reactant temperature of 140$^{\circ}$ while transformation into anhydrite mostly occurs around $160^{\circ}C.$ When calcium hydroxide was added to gypsum in the reactor, the optimum physical properties of the calcined product were obtained at the weight ratio of $Ca(OH_2)/P_2O_5$ = 3.2.