반응기판의 회전 속도에 따른 CVD 반응기 내의 유동 특성과 증착률에 관한 수치적 연구

백재상,부진효,한전건,김윤제 한국표면공학회 2007 한국표면공학회 학술발표회 초록집 Vol.2007 No.-

화학 기상 증착법 (Chemical Vapor Deposition)은 기체 원료의 화학반응을 이용하여 박막, 미립자, nano-tube 등 고체 재료를 합성하는 증착 방법이며, 현재 공업적으로 확산되어 반도체 공정과 같은 박막제조에 이용되고 있다. 박막제조에 있어서 중요한 관심사인 기판의 증착률은 기판의 회전 속도에 의하여 영향 받을 수 있다. 따라서 본 연구에서는 최적의 회전 속도를 찾아내기 위해 박막특성에 직접적으로 연관이 있는 CVD 반응기 내의 유동특성을 유한체적법 (Finite volume method)과 SIMPLE (Semi-Implicit Method for Pressure-Linked Equation) 알고리즘을 사용하여 수치모사 하였고 기판에서 화학 반응을 계산하기 위해 Arrhenius 모델을 사용하였다.

대기압 플라즈마 유동장에 삽입된 랑뮤어 프로브의 영향에 관한 수치적 연구

백재상(Jae-Sang Baek),황정훈(Jung-Hoon Hwang),이종철(Jong-Chul Lee),김윤제(Youn-Jea Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

Atmospheric arc plasmas have been applied to many kinds of industrial materials processing, including welding, cutting, heating and plasma-treatments. Measurements with Langmuir probes, which are the most often used procedures of the plasma diagnostics, interfere with plasma flows a little. In this study, the thermal and fluid dynamic disturbances caused by the insertion of a Langmuir probe into a flowing thermal plasma and the characteristics of atmospheric arc plasma in the absence of a probe are compared. And the main goal of this work is to investigate the influence of a Langmuir probe on the temperature and velocity fields of the arc through the comparison of two cases by computer simulation. Using a commercial code, PHOENICS which uses the conservation equations and current continuity equation have been solved for the temperature distribution within the solid electrodes with the temperature and velocity fields of the plasma flow, simultaneously.

노즐 형상변화에 따른 HVOF 용사총에서의 유동특성에 관한 수치적 연구

백재상(Jae-Sang Baik),김윤제(Youn-Jea Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

HVOF thermal spray guns are now being widely used to produce protective coatings, on the surfaces of engineering components. HVOF technology employs a combustion process to heat the gas flow and melt the coating materials which are particles of metals, alloys or cermets. Particle flow which is accelerated to high velocities and combustion gas stream are deposited on a substrate. In order to obtain good quality coatings, the analysis of torch design must be performed. The reason is that the design parameters of torch influence gas dynamic behaviors. In this study, numerical analysis is performed to predict the gas dynamic behaviors in a HVOF thermal spray gun with various torch shapes. The CFD model is used to deduce the effect of changes in nozzle geometry on gas dynamics. Using a commercial code, FLUENT which uses Finite Volume Method and SIMPLE algorithm, governing equations have been solved for the pressure, velocity and temperature distributions in the HVOF thermal spray torch.

마그네트론 스퍼터링 시스템의 방열 성능 향상에 관한 연구

백재상(Jae-Sang Baek),김태안(Tae-An Kim),김윤제(Youn-Jea Kim) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-

Magnetron Sputtering system is used extensively for thin-film deposition to a wide variety of commercial and scientific purposes, such as making ultra-thin semiconductors, metal films, etc. It plays important role in a coating system. One of the problems to improve the performance of magnetron sputtering system is the enhancement of heat transfer at the source target. High voltage and electric current are furnished to the source target in order to get the uniform deposition. That energy is converted to heat, which must be removed by the efficient cooling system. Otherwise, it may damage the target, magnets, and substrate as well. Therefore, in order to maintain the uniform deposition, the design of effective cooling system is important. The main parameters affecting the cooling performance are the flow path of cooling water, inlet size and flow rate, etc. In this study, the flow characteristics of inside cooling system with various flow paths of cooling water and flow rates are investigated and results are graphically depicted.

HVOF 용사총 노즐 설계에 따른 열유동 특성 연구

백재상(Jae-Sang Baik),김윤제(Youn-Jea Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

The high-velocity oxygen fuel (HVOF) thermal spray is used for a particulate deposition process in which micro-size particles are propelled and heated in a supersonic combusting gas stream. And it is characterized by high gas velocity and high density, is being used in an increasing variety of coating applications, such as ceramic and composite coatings, to improve wear and abrasion resistance. The particle temperature and velocity are two of the most important parameters in HVOF thermal spraying the influence the quality of the coatings. In order to understand the particle dynamics, first of all, it is necessary to study the thermal flow characteristic in the HVOF system. In this study, a numerical analysis is performed to predict the gas dynamic behaviors, and the effect of geometrical parameter is studied to optimize the nozzle design. Using a commercial code, FLUENT which uses FVM and SIMPLE algorithm, governing equations have been solved for the pressure, velocity and temperature.

비개착 지하굴착 공법인 OTR 공법

심재범,문준식,백재상,Sim, Jae-Beom,Mun, Jun-Sik,Baek, Jae-Sang 한국터널지하공간학회 2013 자연, 터널 그리고 지하공간 Vol.15 No.5

트윈제트를 이용한 터널 막장면 보강기법에 관한 연구

김재관,김용현,백재상 한국복합신소재구조학회 2017 복합신소재구조학회 학술발표회 Vol.2017 No.04

This paper is a case study to demonstrate the applicability of a new horizontal jet grouting construction technology to from a ring of improved ground around the tunnel periphery which will guarantee the stability and impermeability of the opening using dual-rod, called Twin-Jet. Normally, the soil-cement admixture after the mixing in a fluid state, which will flow out from the horizontal hole. For the purpose to solving this crucial problem, Twin-Jet technology was invented to solidify soft soil and fractured rock instantly. The fundamental principles of the Twin-Jet method are introduced and sodium silicate(water-glass) is selected as the binder to accelerate the hardening process of an admixture of grout and soil under high pressure of about 10 to 40MPa to create the instant solidification. A filed test was conducted in the tunnel at OOO in Pusan. Field and laboratory results showed that the admixture can be quick gelled within 10 to 20 seconds. The diameter of jet-grouted column reached 0.6 meter and the strength after 28 days reached 2.0MPa.

암반사면의 안정을 위한 신뢰성 해석에 관한 연구

심태섭,기완서,주승완,백재상 朝鮮大學校 建設技術硏究所 2000 建設技術硏究 Vol.20 No.1

The stability of rock slope is mainly controlled by the engineering properties of discontinuities in the rock mass. Design method for deciding the cutting angle of rock slope must involve the significance of the mechanical and hydraulic characteristics of discontinuities on the shear strength of the rock mass. However most methods consider only rock strength as a prime factor for slope design, which sometimes result in failure. The optimum design of rock slope based on the limit equilibrium theory can vary significantly according to the mechanical characteristics of the discontinuities. Therefore, unless the level of ground water and its seasonal variations are accurately investigated, the reinforcements of any kind must be installed, besides the lowering of cutting angle, to ensure the stability of rock slope. This study is analyzed the stability of rock slopes by computing limit equilibrium theory. By analyzing probability of failure in rock slope, this study is analyzed the probability.

기초 보강을 위한 파일-젯 공법 개발

김용현(Kim, Yong Hyun),김재관(Kim, Jae Kwan),백재상(Baek, Jae Sang),김기연(Kim, Ki Yeon) 대한토목학회 2017 대한토목학회 학술대회 Vol.2017 No.10

열처리 단백질-광물질 복합제제 첨가가 In Vitro 발효성상과 착유우의 유량 및 유성분에 미치는 영향

최낙진,배귀석,남경표,장문백,엄재상,고종렬,하종규 한국동물자원과학회 2002 한국축산학회지 Vol.44 No.5

본 연구의 in vitro 실험결과를 살펴보면, 배양액의 pH와 암모니아 생성량은 전 배양시간 동안 처리구간 통계적 유의차가 없었다. Total VFA, acetate, propionate, butyrate 생성량은 12 h에서 HPM을 0.2%, 1% 첨가한 시험구에서 대조구와 비교하여 증가하는 경향이 있었으나, 2% 첨가구에서는 오히려 감소되었고, 48 h 에서는 HPM 첨가한 세 처리구에서 대조구와 비교하여 모두 증가하는 경향을 보였다. 반면에, 다른 배양시간대에서는 처리구간 통계적 유의차는 발견되지 않았다. A/P ratio 경우에도 처리구간 유의차는 없었다. 총 gas 생성량은 배양시간 24 h과 48 h에 HPM 처리구에서 대조구와 비교하여 증가하였다 (P<0.05). 한편 사양실험은 열처리된 단백질 (대두박)과 광물질의 복합 제제 (HPM)가 젖소의 유생산량과 유성분에 끼치는 영향을 조사하기 위하여 수행되었는데 그 결과를 요약하면, 유생산량은 대조구와 비교하여 HPM 시험구에서 하루에 약 1㎏ 정도 더 높았고 (27. 7 vs 28.8 ㎏/d, P<0.001), 4% FCM 생성량 또한 대조구와 비교하여 볼 때 HPM 시험구에서 1.3㎏/d 이 더 높았다 (P<0.001). 유단백 (P<0.05)과 SNF (P<0.05)도 대조구와 비교하여 HPM 시험구에서 그 생산량이 증가되었다. 반면에, 유지방, MUN과 체세포수는 처리구간 통계적 유의차가 발견되지 않았다. 이상의 결과로 보아, HPM 첨가에 의한 반추위 발효 저해현상은 없었으며, HPM 내 함유되어 있는 열처리된 단백질과 광물질의 결합체와 잔여 광물질이 반추위 내 단백질과 결합하여 단백질 분해 속도를 지연시킴으로써, 단백질의 by-pass율을 증가시켜, 유생산량 증가와 유질을 개선 (유단백질, SNF 함량 증가 등) 하는 등 젖소의 생산성을 향상시킨 것으로 요약할 수 있다. This study, consisting of two experiments, was conducted to determine the effects of feeding heat treated protein and mineral complex (HPM) on milk production and composition, and ruminal fermentation of Holstein dairy cows. In in vitro experiment, HPM levels were 0, 0.2, 1 and 2%, and Timothy hay, which was substrate, was milled as 1 ㎜ size, and the effect of HPM on pH and ammonia and VFA were analyzed after incubation times of 0, 6, 12, 24 and 48 h, respectively. The pH and ammonia production were not significantly different between treatments during the incubation. In addition, generally, total VFA and individual VFA were not affected by HPM on 0, 6 and 24 h. While, total VFA and individual VFA were increased in 0.2% and 1% of HPM supplemented treatments, but decreased in 2% of HPM treatment compared with control on 12 h. On 48 h, total VFA and individual VFA were increased in HMP treatment compared to control(P<0.05). However, A/P ratio was not affected by HPM supplementation. Gas production was higher in HPM treatment compared to control on 24 h (P<0.05) and 48 h (P<0.05). In lactating experiment, fourteen lactating Holstein cows were used for 4 months in a cross over experimental design. There were two treatment; no added HPM as a control and 0.2% of HPM added as a test treatment. Daily milk yield (P<0.001), 4% FCM (P<0.001), milk protein (P<0.05) and SNF (solid not fat; P<0.05) were increased in HPM treatment compared to control. While, milk fat, MUN (milk urea nitrogen) and SCC (somatic cell count) were not significantly different between treatments.