• 한국연소학회지
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• 제10권3호
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• pp.25-33
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• 2005

Fast-time instability is investigated for diffusion flames with Lewis numbers greater than unity by employing the numerical technique called the Evans function method. Since the time and length scales are those of the inner reactive-diffusive layer, the problem is equivalent to the instability problem for the $Li\tilde{n}\acute{a}n#s$ diffusion flame regime. The instability is primarily oscillatory, as seen from complex solution branches and can emerge prior to reaching the upper turning point of the S-curve, known as the $Li\tilde{n}\acute{a}n#s$ extinction condition. Depending on the Lewis number, the instability characteristics is found to be somewhat different. Below the critical Lewis number, $L_C$, the instability possesses primarily a pulsating nature in that the two real solution branches, existing for small wave numbers, merges at a finite wave number, at which a pair of complex conjugate solution branches bifurcate. For Lewis numbers greater than $L_C$, the solution branch for small reactant leakage is found to be purely complex with the maximum growth rate found at a finite wave number, thereby exhibiting a traveling nature. As the reactant leakage parameter is further increased, the instability characteristics turns into a pulsating type, similar to that for L < $L_C$.

• 대한기계학회논문집B
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• 제28권9호
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• pp.1015-1021
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• 2004

Micro-resolution Particle Image Velocimetry(Micro-PIV) was used to measure the flow in a micro-branch(Micro-Bypass). In this paper, effects of particle lump at the tip of a Micro-branch and difficulties of Micro-PIV measurements for microfluidics with branch passage were described. Micro-bypass was composed of a straight channel(200(100)${\mu}$m width ${\times}$ 80${\mu}$m height) and two branches which has 100(50)${\mu}$m width ${\times}$ 80${\mu}$m height. One of branches was straight and the other was curved. Experiments were performed at three regions along streamwise direction(entrance, middle and exit of branch) and five planes along vertical direction (0, ${\pm}$10, ${\pm}$20 ${\mu}$m) for the range of Re=0.24, 1.2, 2.4. Numerical simulation was done to compare with the measurements and understand the effects of particle lump at the tip of branch. And another fluid(3% poly vinyl Alcohol aqueous solution) were adapted for this study, so there were no particle sticking. In this case, we could get velocity difference between straight and curved branches.

• 대한전기학회논문지:전력기술부문A
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• 제49권6호
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• pp.259-265
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• 2000

The purpose of this paper is to detect and identify topological errors in order to maintain a reliable database for the state estimator. In this paper, a two stage estimation procedure is used to identify the topology errors. At the first stage, the WSAV state estimator which has characteristics to remove bad data during the estimation procedure is run for finding out the suspected branches at which topology errors take place. The resulting residuals are normalized and the measurements with significant normalized residuals are selected. A set of suspected branches is formed based on these selected measurements; if the selected measurement is a line flow, the corresponding branch is suspected; if it is an injection, then all the branches connecting the injection bus to its immediate neighbors are suspected. A new WLAV state estimator adding the branch flow errors in the state vector is developed to identify the branch topology errors. Sample cases of single topology error and topology error with a measurement error are applied to IEEE 14 bus test system.

• 한국작물학회지
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• 제44권2호
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• pp.117-121
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• 1999

Spikelet and vascular bundle development in rice panicles is considered to be the important elements in determining the genotype's yield capacity and translocation ability of assimilates into grains, respectively. This study was conducted to clarify the varietal differences of the spikelet and vascular bundle formations among three rice cultivars; Iksan 435 (japonica), Dongjinbyeo (japonica) and Namcheonbyeo (Tongl-type). Iksan 435 had more primary rachis branches (PRBs), secondary rachis branches (SRBs) and spikelets per panicle than Dongjinbyeo, but less than Namcheonbyeo. Among three cultivars, Namcheonbyeo showed the highest spikelet number per panicle which were differentiated SRBs mainly on PRBs of lower rachis nodes. And Namchenbyeo showed the highest number of large vascular bundle (LVB) as well as small vascular bundle (SVB) and it displayed the largest diameter of LVB. Between the two japonica cultivars, the numbers of LVBs end SVBs were significantly higher in Iksan 435 than those in Dongjinbyeo. The PRBs to LVBs ratio of Namcheonbyeo was twice as large as those of Dongjinbyeo and Iksan 435. These results indicate that the newly bred cultivar, Iksan 435, has improved yield capacity by increasing the number of especially rachis branches and spikelets formation as well as 1,000 grain weight, compared to other former japonicas.

• 패션비즈니스
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• 제5권3호
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• pp.63-71
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• 2001

The symbol of the sacred tree represents the world tree. They were influenced by Tree worship in Northern mounted nomadic groups, and the first is quite obvious, that the sacred tree is a palm tree. The Assyrian sacred tree possesses characteristics, making the tree iconographic and rather artificial. The tree typically has a thin trunk arranged in two or three tiers. Each tier is separated by horizontal plates or bands. The top of the tree is crowned with a palmette form. Wavy streamers emanate from the tree abd terminate in palmettes in a criss cross fashion. The central trunk is topped with a palmette and surrounded the trunk with palmettes emphasizing a link to date trees. The number of branches on the tree is limited, and there are usually seven, fifteen or thirty branches. The connection of these numbers with those of the week, and of the lunar wax and wane is so obvious. The branches on the tree may have indeed represented a calender of some sort. Mainly based on the excavated tomb articles of the three kingdoms and referred to Chinese and Japanese ones, Sacred Tree pattern showed that was lightly influenced by the times and area, but was slowly changed and developed to different types through those each ages generally. The Sacred Tree type was three part in according to the wavy streamers emanate from the tree abd, Sacred tree type I, Sacred tree type II, Sacred tree type III[the Mountain(; 山)-typed piled up Sacred Tree].

• Anatomy and Cell Biology
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• 제56권2호
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• pp.205-210
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• 2023

Left coronary artery divides into anterior interventricular branch and circumflex branch. As both the arteries run in their corresponding grooves, an arteriovenous trigone is formed between conus arteriosus and left auricle called triangle of Brocq and Mouchet. The triangle base is formed by great cardiac vein. This study aims to describe the frequency of triangle and its type and relationship between various boundaries and content of triangle and to supplement the existing knowledge of clinicians. This observational and descriptive study was conducted on 40 formalin fixed cadaveric hearts in department of anatomy, Kalpana chawla government medical college. The triangle was found in 92.5% of specimen with most common type being closed (51.3%) which is followed by inferiorly open in 35.1%, superiorly open in 8.1% and completely open in 5.4% hearts. Most frequent content of triangle was median artery followed by diagonal branches of anterior interventricular and circumflex branches. The mean area of the triangle was 246.3 mm². Relationship of vein with two arterial branches was either superficial or deep. The knowledge of different patterns of existence will be required for angiographic procedures. Further the triangle is a potential epicardial access route to left fibrous ring. Thus detailed knowledge of variations will help cardiologist to achieve better outcome in interventional procedures with minimal complications.

• ALGAE
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• 제18권2호
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• pp.107-119
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• 2003

Neosiphonia is separated from the traditionally well known genus Polysiphonia (Rhodomelaceae, Rhodophyta) and 12 species includes in Korea. In this study, the vegetative and reproductive developments of two Neosiphonia species, N. decumbens (Segi) M.S. Kim et I.K. Lee and N. harlandii (Harvey) M.S. Kim et I.K. Lee, are reinvestigated. N. decumbens is diagnosed by following combination of the characters: plants 1-3 cm high, dwarf, decumbent, main axes indistinct, irregularly branched in dichotomous manner, and alternately or secundly ramified with wide angles above. N. harlandii is distinguished by the features: plants 4-8 cm high, usually solitary and saxicolous, erect, densely corticated at base of distinct main axes, rather irregularly alternate in branch, and with cicatrigenous branchlets developed numerously on every part of frond. The two species share typical characteristics of the genus Neosiphonia, such as a base attached by unicellular rhizoids, cut off by cross wall, pericentral cells in 4, trichoblasts moderately developed near the apex of branches, leaving persistent scar-cells, tetrasporangia arranged in a spiral series, procarps with 3-celled carpogonial branch, and spermatangial branches arising as a primary branch of trichoblast. Taxonomy of the two Neosiphonia in regard to Polysiphonia is discussed.

• Structural Engineering and Mechanics
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• 제11권2호
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• pp.199-210
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• 2001

Axially compressed circular cylinders repeat symmetry-breaking bifurcation in the postbuckling region. There exist stable equilibria with all symmetry broken in the buckled configuration, and the minimum postbuckling strength is attained at the deep bottom of closely spaced equilibrium branches. The load level corresponding to such postbuckling stable solutions is usually much lower than the initial buckling load and may serve as a strength limit in shell stability design. The primary concern in the present paper is to compute these possible postbuckling stable solutions at the deep bottom of the postbuckling region. Two computational approaches are used for this purpose. One is the application of individual procedures in computational bifurcation theory. Path-tracing, pinpointing bifurcation points and (local) branch-switching are all applied to follow carefully the postbuckling branches with the decreasing load in order to attain the target at the bottom of the postbuckling region. The buckled shell configuration loses its symmetry stepwise after each (local) branch-switching procedure. The other is to introduce the idea of path jumping (namely, generalized global branch-switching) with static imperfection. The static response of the cylinder under two-parameter loading is computed to enable a direct access to postbuckling equilibria from the prebuckling state. In the numerical example of an elastic perfect circular cylinder, stable postbuckling solutions are computed in these two approaches. It is demonstrated that a direct path jump from the undeformed state to postbuckling stable equilibria is possible for an appropriate choice of static perturbations.

• Smart Structures and Systems
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• 제23권6호
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• pp.669-682
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• 2019

Vibration mitigation of cables or hangers is one of the crucial problems for cable supported bridges. Previous research focused on the behaviors of cable with dampers or crossties, which could help engineering community apply these mitigation devices more efficiently. However, less studies are available for hybrid applied cross-ties and dampers, especially lack of both analytical and experimental verifications. This paper studied damping and frequency of two parallel identical cables with a connection cross-tie and an attached damper. The characteristic equation of system was derived based on transfer matrix method. The complex characteristic equation was numerically solved to find the solutions. Effects of non-dimensional spring stiffness and location on the maximum cable damping, the corresponding optimum damper constant and the corresponding frequency of lower vibration mode were further addressed. System with twin small-scale cables with a cross-link and a viscous damper were tested. The damping and frequency from the test were very close to the analytical ones. The two branches of solutions: in-phase modes and the out-of-phase modes, were identified; and the two branches of solutions were different for damping and frequency behaviors.

• 한국산림과학회지
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• 제99권3호
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• pp.277-284
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• 2010

회화나무 녹병균(Uromyces truncicola)은 기주식물의 줄기와 가지 그리고 잎에 감염하고 회화나무의 감염률은 78%였다. 이 녹병균의 겨울포자는 밤갈색으로 원형~난형이었으며, $29-37{\times}24-27\;{\mu}m$ 크기였고, 여름포자는 황갈색으로 타원형~난형이며 포자 표면에 가시모양의 돌기가 있고 $28-39{\times}19-22\;{\mu}m$ 크기였다. 이 병으로 감염된 가지에서는 코르크층이 비후되었고, 방사유조직은 비틀어지고 갈라지거나 합쳐졌으며 유세포가 증가하였다. 건강한 회화나무 가지의 방사유조직은 1열에서 2열인 반면에, 감염 가지의 방사유조직은 3열 이상의 유세포들이 방추형을 형성하고 있었다. 감염 가지에서는 도관들이 다양한 형태로 비틀어져 있었고, 내수피 부분과 일부 목부조직의 세포간극에는 황색물질이 형성되어 있었다. 병 발생이 적은 개체에서는 가지의 털은 밀생하고 길었으며, 잎의 상표피 두께는 평균 23.3 ${\mu}m$인데 비하여, 병 발생이 심한 개체에서는 가지의 털이 상대적으로 덜 밀생하고 짧았으며, 상표피의 두께는 평균 17.4 ${\mu}m$였으므로, 저항성 개체가 존재하는 것으로 생각되었다.