• 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.

• 동력기계공학회지
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• 제17권3호
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• pp.35-43
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• 2013

Generally, the chassis of an indoor RAC is composed of a rear-guider and a stabilizer. The aerodynamic performance of a cross-flow fan is strongly influenced by the various design factors of the chassis of an indoor RAC. The purpose of this paper is to select the optimum design factors through the aerodynamic performance of a cross-flow fan. The design factors are the leading angle of a rear-guider (${\theta}_1$), a stabilizer setup angle(${\theta}_2$), a rear-guider clearance(${\epsilon}_1$), and a stabilizer clearance(${\epsilon}_2$), respectively. As a result, the optimum design factors of an indoor RAC can be presented as a combination of ${\theta}_1=33^{\circ}$, ${\theta}_2=55^{\circ}$, ${\epsilon}_1=6{\sim}8mm$, and ${\epsilon}_2=7mm$ through the analysis of a static pressure coefficient and a static pressure efficiency.

• Advances in aircraft and spacecraft science
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• 제3권4호
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• pp.367-378
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• 2016

Thrust Vectoring is a dynamic feature that offers many benefits in terms of maneuverability and control effectiveness. Thrust vectoring capabilities make the satisfaction of take-off and landing requirements easier. Moreover, it can be a valuable control effector at low dynamic pressures, where traditional aerodynamic controls are less effective. A numerical investigation of Fluidic Thrust Vectoring (FTV) is completed to evaluate the use of fluidic injection to manipulate flow separation and cause thrust vectoring of the primary jet thrust. The methodology presented is general and can be used to study different techniques of fluidic thrust vectoring like shock-vector control, sonic-plane skewing and counterflow methods. For validation purposes the method will focus on the dual-throat nozzle concept. Internal nozzle performances and thrust vector angles were computed for several range of nozzle pressure ratios and fluidic injection flow rate. The numerical results obtained are compared with the analogues experimental data reported in the scientific literature. The model is integrated using a finite volume discretization of the compressible URANS equations coupled with a Spalart-Allmaras turbulence model. Second order accuracy in space and time is achieved using an ENO scheme.

• 패션비즈니스
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• 제10권5호
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• pp.1-14
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• 2006

The purpose of this study is to examine the style of Marlene Dietrich who was a Hollywood legend in 1930s and has influenced on modern fashion. The characteristics of Dietrich style showed androgyny, sensualism and exoticism. Dietrich has been famous for wearing tailored pantsuit on and off-screen with mannish gesture and had great effect on women's wearing pants. Her confident, sexy mannish style represented her androgyny glamourously and proved she had a taste for a classic. Her sensualism focused on her famous legs because she understood the sex appeal of woman's legs. She showed her legs by wearing pants and decorative stockings, or matching colors of stockings and shoes to make her legs look longer and sexier by illusion. Her exoticism against a backdrop of black and white image, was presented with luxurious, sensual fabrics such as furs, feathers and velvet, along with dazzling accessaries. Also she didn't forget to manipulate angles of camera and lights for the engraving figure of her own. Her charisma directed her fashion image in detail and made herself a fashion icon in 1930s.

• International Journal of Concrete Structures and Materials
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• 제7권1호
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• pp.51-59
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• 2013

The use of light-gauge steel framing in low-rise commercial and industrial building construction has experienced a significant increase in recent years. In such construction, the wall framing is an assembly of cold-formed steel (CFS) studs held between top and bottom CFS tracks. Current construction methods utilize heavy hot-rolled steel sections, such as steel angles or hollow structural section tubes, to transfer the load from the end seats of the floor joist and/or from the load-bearing wall studs of the stories above to the supporting load-bearing wall below. The use of hot rolled steel elements results in significant increase in construction cost and time. Such heavy steel elements would be unnecessary if the concrete slab thickening on top of the CFS wall can be made to act compositely with the CFS track. Composite action can be achieved by attaching stand-off screws to the track and encapsulating the screw shank in the deck concrete. A series of experimental studies were performed on full-scale test specimens representing concrete/CFS flexural elements under gravity loads. The studies were designed to investigate the structural performance of concrete/CFS simple beams and concrete/CFS continuous headers. The results indicate that concrete/CFS composite flexural elements are feasible and their structural behavior can be modeled with reasonable accuracy.

• 천문학회보
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• 제40권2호
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• pp.56.4-57
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• 2015

We present the optical design and a sensitivity analysis for a wide field of view (FOV) instrument operating at UV and IR wavelengths. The ongoing investigation is performed in collaboration with Omnisys Instruments (Sweden) and focuses on a telluric-limb-viewing instrument that will fly in a low Earth orbit to study mesospheric wave structures over a wide range of horizontal scales in the altitude range 80 - 100 km. The instrument has six wavelength channels which consist of 4 channels of IR and 2 of UV. We are proposing an optical design based on three mirror aplanatic off-axis reflective system. The entrance pupil diameter and effective focal length are 45 mm and 270 mm, respectively. The FOV is $5.5^{\circ}{\times}1^{\circ}$ and the secondary mirror is set for stop. The optical specification is required to have an encircled energy of at least 80 % within a diameter of 21 um. We performed sensitivity analysis for the longest wavelength of 772 nm in consideration of the diffraction limit of system. The results show that tolerance limits for positions and angles of the mirrors are not very sensitive compared with typical error budgets of manufacturing and assembling process. The secondary mirror has the most sensitive tolerance for surface figure of 250 nm in root-mean-square.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.821-825
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• 2005

Tilt rotor aircraft was developed for satisfying VSTOL (vertical short take off and landing) capability and cruise performance. However the noise generated by tilt rotor system causes one of the most serious problems. In this paper, noise characteristics of tilt rotor system in hovering flight are predicted by using free wake method and Lowson's formula. The flow field of the tilt rotor is simulated by using time marching free wake method, and the free field acoustic pressure is calculated through Lowson's formula. The predicted results are compared with experimental data at various observing positions. In the near field, they show good agreement with experimental data regardless of rotating speed and collective pitch angles of 6, 8 and 10 degree, although there are some discrepancies between prediction and experiment in the far field and at the rotating axis in the near field. It seems that the reason of these discrepancies is difference of unsteady force fluctuation between experiment and calculation.

• 한국정밀공학회지
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• 제17권12호
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• pp.61-67
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• 2000

In switched reluctance motor(SRM) drive, it is necessary to synchronize the stator phase excitation with the rotor position. Therefore the rotor position information is an essential. Usually optical encoders or resolvers are used to provide the rotor position information. These sensors are expensive and are not suitable for high speed operation. In general, the accuracy of the switching angle is dependent upon the resolution of the encoder and the sampling period of the microprocessor. But the region of high speed, switching angles are fluctuated back and forth from the preset values, which are cause by the sampling period of the microprocessor. Therefore, the low cost linear encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using the simple digital logic circuit is also presented in this paper. It is verified from the experiments that the proposed encoder and logic controller can be a powerful candidate for the practical low cost SRM drive.

• BMB Reports
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• 제44권2호
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• pp.118-122
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• 2011

Most widely used secondary structure assignment methods such as DSSP identify structural elements based on N-H and C=O hydrogen bonding patterns from X-ray or NMR-determined coordinates. Secondary structure assignment algorithms using limited $C{\alpha}$ information have been under development as well, but their accuracy is only ~80% compared to DSSP. We have hereby developed SABA (Secondary Structure Assignment Program Based on only Alpha Carbons) with ~90% accuracy. SABA defines a novel geometrical parameter, termed a pseudo center, which is the midpoint of two continuous $C{\alpha}s$. SABA is capable of identifying $\alpha$-helices, $3_{10}$-helices, and $\beta$-strands with high accuracy by using cut-off criteria on distances and dihedral angles between two or more pseudo centers. In addition to assigning secondary structures to $C{\alpha}$-only structures, algorithms using limited $C{\alpha}$ information with high accuracy have the potential to enhance the speed of calculations for high capacity structure comparison.

• 한국음향학회지
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• 제20권4호
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• pp.81-86
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• 2001

126-kHz양상태 해수면 음파산란 측정을 강원도 삼척시 연안에서 수행하였다. 수평입사각을38％, 52％로 고정시킨 상태에서 트랜스듀서와 청음기의 거리를 변화시키면서 산란각의 변화에 따른 전방산란 신호의 변화를 관찰하였다. 해저면 산란신호와는 달리 해수면 산란신호는 해수면 유동성에 의해서 도달시간 변이와 진폭의 변이를 나타내었으며 신호간의 상관관계도 불규칙적인 경향을 나타내었다. 전방산란강도를 계산하여 Kirchhoff approximation (KA)과 small slope approximation (SSA)을 비교한 결과 두 모델 모두 실측치와 잘 일치하였다.