• 한국항해학회지
• /
• 제17권1호
• /
• pp.37-48
• /
• 1993

When the vessel is running at the very low Froude numbers, the free-surface is difficult to be disturbed, wave-making is negligible, and the double -model velocity potential gives a very good approximation for calculating the velocity distribution just outside the boundary layer. If the speed of incident flow is gradually increased, the most perceptible change is the rise of the flow surface at stem. With further increase in speed, the nature of the flow at the bow changes completely, The flow ahead of the bow becomes more distrubed, the rise at the stem to stagnation height disappear, and the first wave crest, of less than the stagnation height, appears a small distance downstream from the stem. The present study is concerned with a small region of this flow, mainly in the bow region. The present investigation is primarily an experimental study of the flow in the bow region of s ship model, and it is undertaken in order to investigated systematically, the effect of bow geometry on this flow. The long-range objective is to use these results to guide the development of a mathematical model for predicting the flow about a ship's bow.

• 한국기계가공학회지
• /
• 제18권5호
• /
• pp.103-109
• /
• 2019

The pressure reducing valve for water is controlled by the load of the compression spring and the force of the fluid acting on the diaphragm of the stem. Repeated upward and downward reciprocation of the pressure-reducing valve stem damages the diaphragm, resulting in leakage. In this study, we designed a stem without a diaphragm and adjusted the stiffness of the compressing spring. In order to select the spring stiffness, springs offering a stiffness of -20%, -10%, 0%, and 10% with respect to the stiffness of the compression spring attached to the existing pressure reducing valve stiffness. A prototype for the pressure reducing valve was fabricated and the pressure change was evaluated for the target static pressure (6 bar) by testing the pressure characteristics after mounting the modified stem and each compression spring. Evaluation of the pressure characteristics was carried out using ASSE 1003 and KS B 6153. In addition, the flow rates were compared by internal flow analysis of the conventional pressure reducing valve and the pressure reducing valve using the modified stems, and the flow analysis was performed using Solidworks flow simulation 2018. The spring stiffness was constantly discharged at the target static pressure of 3.793 kgf/mm, and the flow rate was increased by about 15% compared with the conventional pressure reducing valve.

• 생물환경조절학회지
• /
• 제14권4호
• /
• pp.298-301
• /
• 2005

Potato (Solamum tuberosum 'Dejima') plantlets were investigated on culture type and initial quantity of inoculation in bioreactor and survival rate by hydroponics for mass production. rode stems (1 to 1.5cm in length) of potato plantlets multiplied in vitro were grown for 3 weeks in liquid Murashige and Skoog (MS) medium with sucrose $30 g\; L^{-1}$. When plantlets (80-node inoculation) were raised in 10L balloon type bubble (BB) bioreactor, the healthiest growth of plantlets was obtained from explants cultured in ebb & flow culture with medium supplied periodically 12 times per day. The suitable inoculation quantity of 20L BB bioreactor was 120 pieces of stem segments (mean 2.2g fresh weight) in ebb & flow culture. Number of nodal shoot was eight on the average. In controlled culture room, survival rate of plantlets at 7 days after stem cutting was above $70\%$ when they were acclimatized by hydroponics grown in deep flow and solid medium culture. The highest survival rate of the stem cutting plantlets was in nutrient solution adjusted to EC $1.4dS{\cdot}m^{-1}$. Stem cutting plantlets through one culture could be obtained $670\~900$, when plantlets were grown in ebb & flow culture during 3 weeks using a 20L bioreactor with initial 120 pieces of nodal segments. 11 is possible In do mass production of seedlings cultured in bioreactor and hydroponics.

• 대한수의학회지
• /
• 제58권1호
• /
• pp.33-37
• /
• 2018

Various trials have been conducted to develop therapies for serious untreatable diseases. Among these, those using stem cells have shown great promise, and adipose-derived mesenchymal stem cells (ADMSCs) are easier to obtain than other types of stem cells. Prior to clinical trials, characterization of ADMSCs with monoclonal antibodies should be performed. However, it is difficult to use species-specific antibodies for veterinarians. This study was conducted to confirm the panel of human antibodies applicable for use in immunophenotypic characterization of canine adipose-derived stem cells and feline ADMSCs extracted from subcutaneous adipose tissue collected during ovariohysterectomy. For flow cytometric immunophenotyping, the third passages of canine ADMSC and feline ADMSC and human CD31, CD34, CD42, CD44, CD62 and CD133 antibodies were used. Of these, CD133 reacted with canine cells (3.74%) and feline cells (1.34%). CD133 is known as a marker related with more primitive stem cell phenotype than other CD series. Because this human CD133 was not a species-specific antibody, accurate percentages of immunoreactivity were not confirmed. Nevertheless, the results of this study confirmed human CD133 as a meaningful marker in canine and feline ADMSCs.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2002년도 추계학술대회 논문집
• /
• pp.113-116
• /
• 2002

The shock wave discharged from an annular duct leads to very complicated flow features, such as Mach stem, spherical waves, and vortex rings. In the current study, the merging phenomenon and propagation characteristics of the shock wave are numerically investigated using a CFD method. The Harten-Yee's total variation diminishing (TVD) scheme is used to the unsteady, axisymmetric, two-dimensional, compressible Euler equations. The Mach number of incident shock wave $M_s$ is varied in the range below 2.0. The computational results are visualized to observe the major features of the annular shock waves discharged from the tube. On the symmetric axis, the peak pressure produced by the shock wave and its location depend upon strongly the radius of the annular tubes. A Mach stem is generated along the symmetric axis of the annular tubes.

• 대한소아치과학회지
• /
• 제46권3호
• /
• pp.337-342
• /
• 2019

이 연구의 목적은 발치한 매복 과잉치에서 얻은 치수 유래 세포의 줄기세포 특성을 유세포 분석을 통해 알아보는 것이다. 15명의 환자로부터 채취한 정중 과잉치의 치수 세포를 계대 배양하였고, 3계대와 10계대 세포들을 유세포 분석을 이용하여 분석하였다. 간엽성 줄기세포 표지자 관찰에 사용된 항체 표지자(CD)는 양성 표지자로는 CD 73, CD 90, 그리고STRO-1 와 음성 표지자로는 CD 34, CD 45 이었다. 3계대에서 CD 73, CD 90은 각각 94.82%, 98.86%의 양성반응을, CD 34, CD 45는 각각 2.25%, 2.52%로 음성 반응을 보였으며, STRO-1은 20.93%를 나타냈다. 10계대에서는 CD 73, CD 90은 각각 96.62%, 98.61%의 발현을 보였지만, CD 34, CD 45는 각각 3.86%, 4.14%를 나타냈다. STRO-1은 35.62%로 발현되었다. 이상의 결과에서 과잉치 치수 유래 세포는 간엽성 줄기세포의 특성을 가지며, 3계대와 10계대 모두에서 간엽성 줄기세포의 특성을 유지하고 있다고 사료된다. 이에 빠른 성장 속도와 늦은 계대까지 유지되는 줄기세포능을 고려할 때, 치아 유래 줄기세포의 공여부로서 매복 과잉치의 충분한 활용 가능성을 확인하였다.

• 한국산림과학회지
• /
• 제95권2호
• /
• pp.168-173
• /
• 2006

Stem respiration rate ($R_{stem}$) was examined using an open flow system on black locust (Robinia pseudoacacia L.). $R_{stem}$ exponentially increased with increasing air and stem temperature during measurement period and was most closely correlated with stem temperature. It was more closely correlated with stem temperature observed 0.5-2.0 hrs earlier than with current stem temperature, that is, there was time lag between the increase of stem temperature and the efflux of $CO_2$ from stem. $R_{stem}$ gradually increased from spring to summer, and then decreased during autumn. $R_{stem}$ ranged from 0.13 to $4.44{\mu}mol$ $CO_2m^{-2}s^{-1}$. $Q_{10}$ decreased with increasing stem temperature, and varied along position (or diameter) within trees during the same period, especially during the growing season. On the other hand, time lag was shortened with increasing temperature.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제34권4호
• /
• pp.412-418
• /
• 2008

Bone morphogenetic proteins (BMPs) in combination with stem cells gain more significance for their use in bone tissue engineering. The mesenchymal stem cell can be differentiated into osteoblast by the treatment of BMP. The aim of this study is to characterize the osteogenic differentiation process of adult stem cells derived from buccal fat pad according to BMP-2 within culture media and decide the appropriate concentration of BMP-2 to facilitate osteogenesis. The authors procured the stem cell from buccal fat pad and analyzed for presence of stem cell by flow cytomety against CD-34, CD-105 and STRO-1. The buccal fat derived stem cells (BFDC) were treated by application of the different concentration with BMP-2 of 0, 10, 50, 100 and 200ng/ml, respectively. And their ability to differentiate into osteogenic pathway were checked by alkaline phosphatase(ALP) staining, Alizarin red staining and RT-PCR for osteocalcin(OC) gene expression at 7, 14 and 21day of culture. Flow cytometric analysis and biochemical assays demonstrated that BFDC might be a distinguished stem cells, and mineralization was accompanied in proportion to BMP-2 concentration. However, with 100ng/ml concentration of BMP-2, the BFDC demonstrated most efficient staining pattern of ALP and Alizarin red. The feasibility of the osteogenic differentiation in the group of both 50ng/ml and 200ng/ml of BMP-2 showed similar activity and relatively weaker than that of 100ng/ml. These results suggest that the BMP-2 stimulate osteogenesis by BFDC effectively and that bone induction might be controlled through negative regulatory feedback in higher concentration.

• 대한임상검사과학회지
• /
• 제40권2호
• /
• pp.106-112
• /
• 2008

Bone marrow derived mesenchymal stem cells (BMSCs) are largely studied for their potential clinical use. But it is hard to get enough number of those cells for clinical trials and give serious pain to the patients. Adipose tissue is derived from the embryonic mesenchyme and contains a stroma that is easily isolated with large amount. This cell population (adipose derived stem cells: ADSCs) can be isolated from human lipoaspirates and like MSCs, differentiate toward the osteogenic, adipogenic, myogenic and chondrogenic lineages. To confirm whether adipose tissue contains stem cells, the ADSCs extracted from omental or subcutaneous fat tissue were expanded during third to fifth passages. The phenotype of the ADSCs was identified by the conventional cell surface markers using flow cytometry: positive for CD29 and CD44, but negative for CD34, CD45, CD117 and HLA-DR that similar to those observed on BMSCs. The ADSCs were able to differentiate into the osteoblast or adipocytes with induction media. Finally, ADACs expressed multiple CD marker antigens similar to those observed on BMSCs and differentiated into osteoblast, adipocyte. With this, human adipotissue contains multipotent cells and may represent an alternative stem cell source to bone marrow-derived MSCs.

• 한국농림기상학회지
• /
• 제9권3호
• /
• pp.203-208
• /
• 2007

본 연구에서는 동시에 여러 지점을 측정할 수 있는 open flow 시스템을 이용하여 소나무 줄기에서 발생하는 호흡을 겨울과 여름 두 시기에 측정하였다. 연구결과, 줄기의 목부조직에서 호흡속도($R_{stem}$)는 겨울에 $0.25-0.55{\mu}mol\;m^{-2}s^{-1}$, 여름에 $1.25-1.63{\mu}mol\;m^{-2}s^{-1}$의 범위를 나타냈다. 시기별 측정된 수목(15개체)간 $R_{stem}$의 변화성은 변동계수로 나타낼 수 있으며, 그 결과 여름과 겨울이 모두 23%로 시기에 따른 차이를 보이지 않았다. 이러한 변동계수 값에 근거하면 $R_{stem}$ 이 95% 신뢰수준에서 실제 값과의 차이가 10%와 20%보다 적기 위해서는 샘플링 수가 각각 최소 24개와 6개가 필요한 것으로 확인되었다. 또한 겨울과 여름의 온도와 개체간 평균 $R_{stem}$의 상관관계에서, $Q_{10}$ 값은 겨울이 1.49, 여름이 1.45로 계절간에 큰 차이를 나타내지 않았다. 그러나 $R_{20}$(줄기 온도 $20^{\circ}C$일 때의 $R_{stem}$)은 겨울($0.61{\mu}mol\;m^{-2}s^{-1}$)보다 여름($1.23{\mu}mol\;m^{-2}s^{-1}$)이 두 배 정도 컸다.