• 한국자동차공학회논문집
• /
• 제8권2호
• /
• pp.120-128
• /
• 2000

At the initial design stage of a new vehicle, the chassis layout has the most important influence on the overall vehicle performance. Most chassis designers have achieved the target performances by trial and error method as well as individual knowhow. Accordingly, a general procedure for determining the optimum location of suspension hard points with respect to the kinematic characteristics needs to be developed. In this paper, a method to optimize the toe angle in the double wishbone type front suspension of the four-wheel-drive vehicle is presented using the design of experiment, multibody dynamic simulation, and optimum design program. The handling performances of two full vehicle models having the initial and optimized toe angle are compared through the single lane change simulation. The sensitive design variables with respect to the kinematic characteristics are selected through the experimental design sensitivity analysis using the perturbation method. An object function is defined in terms of the toe angle among those kinematic characteristics. By the design of experiment and regression analysis, the regression model function of toe angle is obtained. The design variables which make the toe angle optimized ae extracted using the optimum design program DOT. The single lane change simulation and test of the full vehicle model are carried out to survey the handling performances of vehicle with toe angle optimized. The results of the single lane change simulation show that the optimized vehicle has the more improved understeer tendency than the initial vehicle.

• Structural Engineering and Mechanics
• /
• 제71권6호
• /
• pp.603-625
• /
• 2019

Main cable configurations under final dead load and in the unloaded state and critical construction parameters (e.g. unstrained cable length, unstrained hanger lengths, and pre-offsets for tower saddles and splay saddles) are the core considerations in the design and construction control of a suspension bridge. For the purpose of accurate calculations, it is necessary to take into account the effects of cable strands over the anchor spans, arc-shaped saddle top, and tower top pre-uplift. In this paper, a method for calculating the cable configuration under final dead load over a main span, two side spans, and two anchor spans, coordinates of tangent points, and unstrained cable length are firstly developed using conditions for mechanical equilibrium and geometric relationships. Hanger tensile forces and unstrained hanger lengths are calculated by iteratively solving the equations governing hanger tensile forces and the cable configuration, which gives careful consideration to the effect of hanger weight. Next, equations for calculating the cable configuration in the unloaded state and pre-offsets of saddles are derived from the cable configuration under final dead load and the conditions for unstrained cable length to be conserved. The equations for the main span, two side spans and two anchor spans are then solved simultaneously. In the proposed methods, coupled nonlinear equations are solved by turning them into an unconstrained optimization problem, making the procedure simplified. The feasibility and validity of the proposed methods are demonstrated through a numerical example.

• 대한환경공학회지
• /
• 제29권1호
• /
• pp.74-81
• /
• 2007

본 연구에서는 케이크 여과 장치의 설계와 케이크 여과 이론의 전개에 가장 큰 역할을 하는 평균 비저항값을 새로운 여과 실험방법인 "여과-투과(filtration-permeation) 실험방법"에 의해 측정하였다. 과거부터 사용되어온 전형적인 여과 실험방법에 의해 측정 되는 평균 비저항값을 여과 평균 비저항 $\alpha_{avf}$이라 하고, 이미 형성된케이크에 입자 제거수를 첨가하여 측정한 평균 비저항값을 투과 평균 비저항 $\alpha_{avf}$이라 하였다. 서로 다른 세 가지 현탁액(입자 현탁액, 응집 현탁액, 고분자 현탁액)에 대해서 "여과-투과 실험방법"으로 케이크 여과를 수행하여 여과기간의 평균 비저항값과 투과기간의 평균 비저항값을 계산하였다. 또한 투과기간의 평균 비저항 값을 기준으로 이론적인 여과과정이 연구되었다. 이 연구결과 입자 여과 조작에서 침전의 영향이 무시될 수 없다는 것이 밝혀졌다. 통상적으로는 침전을 무시하고 있다. 또한 입자 여과과정에서 일정하다고 간주되고 있는 현탁액의 고체분율 5도 변화한다. 통상적인 플럭의 여과과정에서는 케이크 내의 고체분율, $S_c$의 값을 정확히 알기 어렵다는 것을 보였다. 이런 중요한 여러 문제점이 "여과-투과 실험방법"을 통해서는 모두 해결 된다는 것을 보였다.

• 대한토목학회논문집
• /
• 제26권1A호
• /
• pp.11-19
• /
• 2006

본 연구에서는 현수교의 선박충돌해석을 위한 설계선박을 결정하기 위하여 선박충돌위험도해석을 수행한다. 선박충돌에 대한 설계선박을 결정하기 위하여 AASHTO 설계기준에서 제시한 3개의 선박충돌 설계방법 중 확률기반 해석방법인 Method II를 사용한다. 선박충돌 위험에 노출된 각각의 교각에 대해 선박충돌위험도 평가를 하여 교각의 충돌설계수평강도를 결정한다. 해석과정은 반복적인 것으로 교량부재의 충돌저항강도를 가정하고 연간파괴빈도를 계산하여 허용기준이 만족하도록 설계 변수를 수정한다. 허용기준은 예상연간파괴빈도에 근거한 가중치를 이용하여 교각에 할당한다. 해석결과에서 안전성과 경제성을 얻기 위해 이 할당방법을 주탑집중 할당방법과 비교한다. 비록 주탑집중 할당방법이 주탑에 비해 과대평가되는 교각의 설계수평강도를 적절히 수정할 경우 보다 경제적인 결과를 가져오지만, 가중치에 의한 할당방법이 설계인자의 특성을 정량적으로 고려하기 때문에 더 합리적인 것으로 보인다. 그리고 선박충돌위험도 평가로부터 얻어지는 충돌설계수평강도에 상응하는 각각의 교각에 대한 설계선박이 결정된다. 같은 교량에 대해서도 충돌설계수평강도가 수로 및 교량의 특성과 선박통행량에 따라 상당히 변화한다. 따라서 허용기준의 할당과 설계선박 선정에 대한 많은 연구가 요구된다.

• Journal of Microbiology and Biotechnology
• /
• 제9권4호
• /
• pp.386-392
• /
• 1999

A large-scale culture of hepatitis A virus in human diploid MRC-5 cells was conducted. In a roller bottle culture, the virus was grown to a maximum titer in 3 weeks after infection. Over 95％ of the cell-associated virus was excreted after culturing the infected cells in suspension media without fetal bovine serum for 3 days. The cultured virus was inactivated with formalin, concentrated by ultrafiltration, and partially purified by ultracentrifugation in a non-ionic gradient medium of Renocal. Two separate peak fractions showing high anti-HAY ELISA titer were pooled and about 40％ of HAV antigen was recovered by this purification procedure. Of the partially purified vaccine, the protein pattern in SDS-PAGE and immunogenicity in mice were compared with a commercial HAV vaccine. In SDS-PAGE, the purified vaccine in this study and the commercial vaccine showed almost the same protein pattern. The seroconversion rate of the purified vaccine in mice was not different from that of the commercial vaccine. Therefore, we could prepare a good grade of HAV vaccine by a simple purification procedure although the purification itself was not completed.

• 한국자동차공학회논문집
• /
• 제6권4호
• /
• pp.76-85
• /
• 1998

Recently, Genetic Algorithm(GA) is widely adopted into a search procedure for structural optimization, which is a stochastic direct search strategy that mimics the process of genetic evolution. This methods consist of three genetics operations maned selection, crossover and mutation. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GA, being zero-order method, is very simple. So, they can be easily applicable to wide area of design optimization problems. Also, owing to multi-point search procedure, they have higher probability of converge to global optimum compared to traditional techniques which take one-point search method. In this study, a method of finding the optimum values of suspension parameters is proposed by using the GA. And vehicle is modelled as planar vehicle having 5 degree-of-freedom. The generalized coordinates are vertical motion of passenger seat, sprung mass and front and rear unsprung mass and rotate(pitch) motion of sprung mass. For rapid converge and precluding local optimum, share function which distribute chromosomes over design bound is introduced. Elitist survival model, remainder stochastic sampling without replacement method, multi-point crossover method are adopted. In the sight of the improvement of ride comfort, good result can be obtained in 5-D.O.F. vehicle model by using GA.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제5권5호
• /
• pp.372-378
• /
• 2000

The cell culture of Angelica gigas Nakai producing decursin derivatives and immunostimulating polysaccharides was preserved in liquid nitrogen after pre-freezing in a deep freezer at -70$^{\circ}C$ for 480 min. The effects of the cryoprotectant and pretreatment before cooling were investigated to obtain the optimal procedure for cyropreservation. When compared to mannitol, sorbitol, or NaCl with a similar osmotic pressure, 0.7 M sucrose was found to be the best osmoticum for the cryopreservation of A. gigas cells. In the pre-culture medium, the cells in the exponential growth phase showed phase showed the best post-freezing survival after cryopreservation. A mixture of sucrose, glycerol, and DMSO was found to be an effective cryoprotectant and a higher concentration of the cryoprotectant provided better cell viability. When compared with the vitrification, the optimum cryopreservation method proposed in this study would seem to be more effective for the long-term storage of suspension cells. The highest relative cell viability established with the procedure was 89%.

• Mycobiology
• /
• 제47권3호
• /
• pp.350-354
• /
• 2019

In the post-genomic era, gene function analysis has attracted much attention. Transformation is often needed to investigate gene function. In this study, an easy, rapid, reliable, and cost-effective colony polymerase chain reaction (PCR) method for screening mushroom transformants was developed: picking up a suitable amount of transformant's tissue ($1-10{\mu}g$) to $20{\mu}l$ 0.25% Lywallzyme solution, and vortexing for 10 s followed by incubation at $34^{\circ}C$ for 15 min. Finally, $2{\mu}l$ of the suspension was used as templates to perform PCR and single target bands were successfully amplified from respective transformants of Tremella fuciformis, Pleurotus ostreatus, and Pleurotus tuber-regium. This procedure could be widely employed for screening transformants in mushroom transformation experiments.

• The Plant Pathology Journal
• /
• 제39권2호
• /
• pp.228-233
• /
• 2023

Two pear cultivars with different degrees of resistance to Venturia nashicola were evaluated on the basis of a disease severity rating for pear scab resistance under controlled environmental condition. Two inoculation techniques were tested: the procedure for inoculation by dropping conidia suspension of V. nashicola; the procedure by deposition of agar plug on the abaxial surface of pear leaves. All tested cultivars resulted in blight symptoms on the inoculated leaves and became spread to uninoculated region or other leaves. Although both methods provide satisfactory infection of V. nashicola on pear leaves, the mycelial plug method of inoculation was more reliable than the spray inoculation method for the evaluation of pear scab disease resistance. The incubation period of V. nashicola in the resistant pear cultivar, Greensis was longer than that in the susceptible cultivar, Hwasan.

• 분석과학
• /
• 제13권5호
• /
• pp.608-615
• /
• 2000

물 시료에 존재하는 극 미량의 니켈과 코발트를 착물로 형성시켜 이온 교환수지 서스펜션에 흡착시켜 분리 농축하여 정량하는 방법을 연구하였다. 리간드로 APDC (ammonium pyrrolidine dithiocarbamnate)를 사용하여 극 미량 이온들을 착물로 형성시켜 농축한 다음, 전열 원자흡수 분광광도법으로 정량하였다. 이때 착물 형성을 위한 수용액의 pH와 착화제인 APDC의 양, 흡착을 위한 이온교환 수지의 종류 및 저어주는 시간, 역 분산에 사용하는 산의 종류 및 농도, 초음파 진동시간 등의 실험조건들을 최적화 하였다. 시료용액의 pH를 5로 조절하고 APDC의 양을 몰 비로 분석원소 전체의 430배 이상 첨가하여 코발트와 니켈을 정량적으로 착물을 형성시켰다. 이온교환 수지는 음이온 형태의 Dowex 2-X8이 우수하였다. pH를 조절한 시료용액, 리간드 및 수지 서스펜션을 혼합하고 1분간 저어주어 흡착을 완전하게 하였다. 역 분산을 위해서는 0.1 M 염산이 가장 좋았고, 이때 막 필터로 거른 교환 수지를 초음파 진동기에서 7분간 진동하면 충분하였다. 팔라듐을 염산과 함께 사용하면 매트릭스를 개선하여 재현성과 감도가 개선되었다. 바탕흡수 신호표준편차의 세배에 해당하는 검출한계는 Co 0.36 ng/mL, Ni 0.27 ng/mL로 극미량 검출이 가능하였고 시료에 일정량 첨가한 분석원소의 회수율은 각각 99-102%와 100-105% 이었다.