• Journal of KSNVE
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• v.10 no.2
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• pp.229-239
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• 2000

To reduce the drag rise on the advancing helicopter rotor blade tips, the tip of the blade is modified to have sweep, anhedral and pretwist. The equations of motion of rotor blade with these tip angles were derived using Hamilton principle, programmed using FORTRAN and named as ARMDAS(Advanced Rotorcraft Multidisplinary Design and Analysis System). Rotating frequency analysis of rotor blades with swept tipe was performed that is necessary in conceptual and preliminary design phases of the helicopter design. Vibration analysis of non-rotating blades was also accomplished and compared with MSC/NASTRAN resutls for the basis of comparison with the vibration test data. The rotating frequency analysis of blades with an actual rotor blade data was also performed to verify coded program and to check the possibility of a resonance of an actual rotor blade at the specific rotating speed.

• Journal of Conservation Science
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• v.30 no.4
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• pp.365-372
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• 2014

The purpose of the present study is to determine the species of red and green pigments used on paintings of Korean temples and also to compare the two pigments according to the particle characteristics. The component analysis shows that the red pigment consists of cinnabar, hematite, and minium and the green pigment are composed of atacamite, celadonite, and malachite. The result suggests that mixture of various pigments were applied to the painting. When it comes to the particle characteristics, there are various hedral or anhedral shapes such as sharp, long, angular, and platy shapes even in the same cinnabar. In addition, the green pigment also shows a similar pattern with those of the red pigment. Up to now, an identification of minerals has been relied on examination of component and crystal shape. However, it is notable that using form related characteristics can be a better and useful method not only for categorization of pigments which are similar in terms of color and species but also specific index.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.43-53
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• 2006

Aerodynamic shape design of the Mid-sized Aerostat was performed with computational fluid dynamics. Design procedure included determination of hull volume and length, hull shape, tailfin configuration with anhedral and location, tailfin section. For aerodynamic analysis, three dimensional Navier-Stokes equations were applied with Spalart-Allmaras turbulence model. During design procedure, static moment derivatives were mainly considered for the stability of aerostat and structural limitations were also considered for practical application of the designed shape. Aerodynamic analysis of the designed aerostat was carried out and aerodynamic characteristics were compared with those of the TCOM 71m aerostat, one of the most successful commercial aerostats. It was found that the designed KARI Mid-sized Aerostat had better stability characteristics compared to the TCOM 71m aerostat.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.295-310
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• 2015

In the present study, an unstructured mixed mesh flow solver was used to conduct a numerical prediction of the aerodynamic performance of the S-76 rotor in hover. For the present mixed mesh methodology, the near-body flow domain was modeled by using body-fitted prismatic/tetrahedral cells while Cartesian mesh cells were filled in the off-body region. A high-order accurate weighted essentially non-oscillatory (WENO) scheme was employed to better resolve the flow characteristics in the off-body flow region. An overset mesh technique was adopted to transfer the flow variables between the two different mesh regions, and computations were carried out for three different blade configurations including swept-taper, rectangular, and swept-taper-anhedral tip shapes. The results of the simulation were compared against experimental data, and the computations were also made to investigate the effect of the blade tip Mach number. The detailed flow characteristics were also examined, including the tip-vortex trajectory, vortex core size, and first-passing tip vortex position that depended on the tip shape.

• Economic and Environmental Geology
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• v.32 no.4
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• pp.339-351
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• 1999

Petrographic and palaeomagnetic studies have been conducted to understand the origin of dark-colored enclaves occurring in the hornblende biotite granite within the Wondong caldera. The enclaves are commonly elongted and rounded in shape. They are finer-grained and darker-colored than enclosing granite, but they have simliar mineral assemblage to that of granite. Under the microscope the enclaves show microstructures reflecting an igneius origin. The microstructures of igneous origin include elongate grain shapes of plagioclase, hornblende, apatite, poikilitic anhedral quartz and zoning of plagiclase. All above features indicate that the enclaves belong to the 'microgranitoid enclaves' of Vernon (1984). a total of 91 orirnted samples were drilled from 4 sites, and their AMS (anisotropy of magnetic susceptibility) axis directions and remance components were analyzed. The result shows thar both enclave and host granite have same AMS priniciple axis direction and same remanence magnetic direction in each site. The result of this study suggests that the anclaves were derived from the globules of magma, which were formed by pillowing of synpltonic dike of magma that is more mafic than the host granite magma.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.2
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• pp.93-114
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• 2011

The current status of Canadian research on rotor-based actively controlled technologies for helicopters is reviewed in this paper. First, worldwide research in this field is overviewed to put Canadian research into context. Then, the unique hybrid control concept of Carleton University is described, along with its key element, the "stiffness control" concept. Next, the smart hybrid active rotor control system (SHARCS) projected's history and organization is presented, which aims to demonstrate the hybrid control concept in a wind tunnel test campaign. To support the activities of SHARCS, unique computational tools, novel experimental facilities and new know-how had to be developed in Canada, among them the state-of-the-art Carleton Whirl Tower facility or the ability to design and manufacture aeroelastically scaled helicopter rotors for wind tunnel testing. In the second half of the paper, details are provided on the current status of development on the three subsystems of SHARCS, i.e. that of the actively controlled tip, the actively controlled flap and the unique stiffness-control device, the active pitch link.

• Economic and Environmental Geology
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• v.28 no.5
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• pp.513-518
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• 1995

A granite drilling core (-1200 m) obtained near the Majang cave in east part of the Cheju island. The rock is pinksh in color and has miarolitic cavities. It is coarse-grained rock and consists of quartz, plagioclase, alkali feldspar, biotite and magnetite. The rock shows characteristically micrographic texture. The alkali feldspar is subhedral to anhedral and generally interstitial grains and fonns micrographic texture. K/Ar age of alkali feldspar in the core specimen is $58.14{\pm}1.4Ma $ (early Tertiary). The age, rock features and whole rock chemistry of the rock has strong resemblance to micrographic granites, so called "masanite", in southeastern part of the Korean peninsular. The granitic fragments from drilling core (- 920 m) obtained in Jungmun area in south part of the Cheju island consist of quartz, plagioclase, alkali feldspar and biotite. The fragments in the Jungmun area are similar to granitic xenolith near the Cheju city for the absence of micrographic texture and different alkali feldspar.

• Economic and Environmental Geology
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• v.19 no.spc
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• pp.121-130
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• 1986

In the Janggun mine, stannite occurs as anhedral grains, up to 500 micrometer in long dimension, closely associated with sphalerite, chalcopyrite, arsenopyrite, pyrrhotite, galena and rhodochrosite in the periphery of the South ore body. In reflected light, stannite is grayish yellow green in color and exhibits moderate bireflectance and strong anisotropism without any intenal reflections. Reflection; Rmax. =29.0, Rmin. =27.8 percent at a wavelength of 560nm, and VHN; 219~244kg/mm at a 50g load. The chemical composition on the average from 35 spot analyses by electron microprobe is, Cu 28.0, Fe 12.7, Zn 2.9, Mn 0.2, Sn 25.8, S 30.3, sum 99.9 (all in weight percent); the corresponding chemical formula as calculated on the basis of total atoms=8 is, Cu 1.88 Fe 0.97 Zn 0.19 Mn 0.02 Sn 0.93 S 4.01, which fulfills approximately the ideal formula of $Cu_2FeSnS_4$. The strongest reflections on the X-ray diffraction patterns are; $3.10{\AA}$ (10) (112), $2.72{\AA}$ (5) (020, 004), $1.922{\AA}$ (5) (024), $1.642{\AA}$ (3) (132), $1.244{\AA}$ (3) (143, 136, 235), $1.111{\AA}$(3) (244), $0.958{\AA}$ (1) (048, 422), the patterns are identical with those of literature. From the textural evidence of the microscopic observation, the mineral is considered to have been formed at the middle stage of hydrothermal lead-zinc-silver mineralization.

• Economic and Environmental Geology
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• v.19 no.2
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• pp.133-146
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• 1986

Primary uraninite and secondary uranium minerals such as torbernite, metatorbernite, tyuyamunite, metatyuyamunite, autunite and metaautunite have been identified from various types of uranium ores. Uranium minerals occur as accessory minerals in both the primary and secondary ores. Low·grade uranium ores consist of various kinds of primary and secondary minerals. Major constituent minerals of primary uranium ores are graphite. quartz. Ba-feldspar and sericite/muscovite, and accessories are calcite, chlorite, fluorapatite, barite, diopside, sphene, rutile, biotite, laumontite, heulandite, pyrite, sphalerite and chalcopyrite, and secondary minerals consist of kaolinite, gypsum and goethite. Uraninite grains occur as microscopic very fine-grained anhedral to euhedral disseminated particles in the graphitic matrix, showing well·stratified or zonal distribution of uranium on auto-radiographs of low-grade uranium ores. Some uraninite grains are closely associated with very fine-grained pyrite aggregates, showing an elliptical form parallel to the schistosity. Some uraninite grains include extremely fine-grained pyrite particle. Sphalerite and pyrite are often associated with uraninite in graphite-fluorapatite nodule. The size of uraninite is $2{\mu}m$ to $20{\mu}m$ in diameter. Low-grade uranium ores are classified into 5 types on the basis of geometrical pattern of mineralization. They are massive, banded, nodular, quartz or sulfide veinlet-rich and cavity filling types. Well-developed alternation of uranium-rich and uranium-poor layers, concentric distribution of uranium in graphite-fluorapatite nodule and geopetal fabrics due to the load cast of the nodule suggest that the uranium was originally deposited syngenetically. Uraninite crystals might have been formed from organo-uranium complex during diagenesis and recrystallized by metamorphism. Secondary uranium minerals such as torbernite, tyuyamunite and autunite have been formed by supergene leaching of primary ores and subsequent crystallization in cavities.

• Journal of the Mineralogical Society of Korea
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• v.2 no.1
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• pp.26-36
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• 1989

Clinopyroxene in the Geodo mine belongs to diopside-hedenbergite series. It is widely distributed throughout the mine area together with garnet and is also closely related with Fe-mineralization. Clinopyroxenes in the Geodo mine including two samples from the sangdong and Ulchin Mines are studied using polarized microscope, EPMA, XRD, and IR spectroscopy for occurrence, chemistry, structure, and crystal chemistry. Especially, variations in unit-cell parameters are examined in relation with the substitution scheme between Fe and Mg cations. Clinopyroxenes in the Geodo mine occur in both endoskarn and exoskarn zone. It is mostly anhedral to subhedral with fine- to medium-grained in texture, but some have bigger crystals of short prismatic or columnar habits. Clinopyroxene occurs as monomineralic or is associated with mostly garnet and sometimes with actinolite, magnetite, epidote, and chlorite. Chemical analysis reveals that the Geodo clinopyroxene is diopsidic in composition (Di: 65-96%). This fact is in good contrast with garnet chemistry showing mostly andraditic (An: 41-82%). Especially, clinopyroxene coexisting with magnetite belongs to nearly end member diopside (Di: 97-99%). Thus, diopside-andradite pair indicates that Geodo skarns were formed under the reduced environment. X-ray diffraction analysis shows unit-cell parameters vary with increase of Fe contents: a = 9.765-9.838$\AA$, b = 8.943-9.020$\AA$, c= 5.240-5.253$\AA$.$\beta$ = 105.70-104.83$^{\circ}$, and V =440.64-448.19$\AA$3. It is noted from the least square regression that a, b and V increase linearly with increase of Fe content, while $\beta$ slightly decreases and c remains nearly unchanged as change in Fe content. These trends are to difference between synthetic and natural clinopyroxenes. This fact is also recognized in IR spectra which show a slight shift of several absorption bands toward lower wavenumber region with increasing Fe content.