• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1227-1233
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• 2010

In the hot section of a gas turbine, the turbine blades were protected from high temperature by providing a thermal barrier coating (TBC) as well as by cooling air flowing through internal passages within the blades. The cooling air then passed through discrete holes on the blade surface, creating a film of cooling air that further protects the surface from the hot mainstream flow. The holes are subjected to stresses resulting from the lateral growth of thermally grown oxide, the thermal expansion misfit between the constituent layers, and the centrifugal force due to high-speed revolution; these stresses often result in cracking. In this study, the deformation and cracks occurring near a hole on a heat-resistant alloy subjected to thermo-mechanical cycling were investigated. The experiment showed that cracks formed around the hole depending on the applied stress level and the number of cycles. These results could be explained by our analytic solution.

• The Korean Journal of Quaternary Research
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• v.15 no.2
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• pp.63-73
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• 2001

In total, 29 $^{14}C$ dates were obtained from Paleolithic sites in the Korean peninsula. If not the dates from the Sorori peat layers, the number will be less than 20. Low boundary of Upper Paleolithic could be estimated by some early of the dates from Blade stone industries. Couple of $^{14}C$ dates indicate that beginning of Upper Paleolithic industries could approach to 40 K BP, but it is premature to establish fine chronology of Upper Paleolithic. Some of the $^{14}C$ dates of microlithic industries probably represent too earlier age than generally thought. Tentatively, the beginning of microlithic industries may go back to an age of slightly older than 20 K BP, as indicated in Janghungri, Sokchangni, Noeundong etc. The obtained $^{14}C$ dates at present are very important for construction of Paleolithic chronology. but it is necessary to accumulate for more $^{14}C$ dates in future along with results from other dating techniques and to reconstruct site formation processes for obtaining objective age of stone industries.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.15
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• pp.61-67
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• 1974

Field experiment was conducted to disclose some effects of leaf defoliation in heading time and the application of different combinations of nitrogen, phosphorus and potassium on the maturity and yield of paddy rice. The results obtained are as follows; 1.All were components considered were increased as the amounts of nitrogen, phospgorus and potassium applied were increased, except the maturity rate had the tendancy to be decreased with the increase of the above fertilizer applications. 2.As the rate of cutting leaves went higher, the weight of rough rice, the maturity rate and the weight of 1, 000 kernels of perferct brown rice were decreased, and there were significant differences among the treatments of leaf blade cutting. 3. The contribution of each leaf to yield through the maturity, number of spikelets per panicle and 1, 000 kernel weight were 61.87-66.18-65.61% respectively for the flag leaf, 17.50-20.65-23.41%for the 2nd leaf, 12-71-12.73-10.11%for the 3rd lead and 7.93-6.44-0.87%for the 4th leaf respectively. This simply indicared that the effects of the leaves to the yield were decreased as their position went down. This tendency was specially emphasized in the case of the weight of 1, 000 kernels of perfect brown rice.

• Korean Journal of Plant Taxonomy
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• v.34 no.2
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• pp.75-85
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• 2004

Here we described and illustrated two new taxa of Allium (Alliaceae) from southern part of Korea. One new species, A koreanum H. J. Choi et B. U. Oh was clearly distinguished from A. splendens of sect. Reticulato-bulbosa by larger and stellately spreading pale pink perianth, apparently exsert filaments, and conical stigma as well as chromosome number. Another new variety, A. thunbergii var. teretifolium H.J. Choi et B.U. Oh was also easily distinguished from its relatives, var. thunbergii and var. deltoides by terete and hollow leaf blade. Keys to the two species of Allium sect. Reticulato-bulbosa and the three varieties of A. thunbergii (sect. Sacculiferum) in Korea were described.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.5
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• pp.343-352
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• 2016

In this study, a pre-swirl duct for the 180,000 DWT bulk carrier has been designed from a propulsion standpoint using CFD. The stern duct - designed by NMRI - was selected as the initial duct. The objective function is to minimize the value of delivered power in model scale. Design variables of the duct include duct angle, diameter, chord length, and vertical and horizontal displacements from the center. Design variables of the stators are blade number, arrangement angle, chord length, and pitch angle. A parametric design was carried out with the objective function obtained using CFD. Reynolds averaged Navier-Stokes equations have been solved; and the Reynolds stress model applied for the turbulent closure. A double body model is used for the treatment of free-surface. MRF and sliding mesh models have been applied to simulate the actuating propeller. A self-propulsion point has been obtained from the results of towing and self-propelled computations, i.e., form factor obtained from towing computation and towing forces obtained from self-propelled computations of two propeller rotating speeds. The reduction rate of the delivered power of the improved stern duct is 2.9%, whereas that of the initial stern duct is 1.3%. The pre-swirl duct with one inner stator in upper starboard and three outer stators in portside has been designed. The delivered power due to the designed pre-swirl duct is reduced by 5.8%.

• KSBB Journal
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• v.5 no.2
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• pp.175-182
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• 1990

Protoplasts, isolated from leaf of N. tabacum NR-/SR+ and N. glottnosa were electrofused and divided with a plating efficiency of 30∼35% in AAPI 9M medium. Green callus lines were selected in protoplast-derived colonies on MSNO3 selection medium with 1.2mg/ml streptomycin sulfate on the basis of nitrate reductase proficiency and streptomycin resistance. Four putative hybrid plant lines regenerated from the green callus lines had intermediate morphology between that of parents with respect to floral shape, corolla length and ovate leaf blade. Zymograms of leaf peroxidase and esterase from these putative hybrid plant lines showed isozyme profiles derived from both parents and also, they exhibited additional and lost bands. Cytological analysis of two putative hybrid plant lines gave chromosome counts of 2n=66 in L22 and 2n=54 in L44 which were less than the expected number of N. tabacum(2n=48) and N. glutinosa(2n=24).

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.146-158
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• 1991

The flow around a two-dimensional foil section Is measured by a LDV(Laser Doppler Velocimetry) system which is capable of measuring the datailed flow field without interfering the original flow field. A 2-color 3-beam LDV system, which is capable of mea,;tiring 2 velocity components simultaneously and uses 2W Ar-Ion laser source, is used to measure the flow field around an NACA0012 foil section. The measured flow velocities are analysed iii order to study the boundary layer characteristics, flow separation and the detail structure of the flow near the trailing edge of the foil. The boundary layer characteristics are compared with the results by the head's momentum integral method. For the case of small angle of attack at relatively higher Reynolds number, both results show good agreements. The measured data of the velocity field around an NACA0012 foil section would be valuable data to validate the CFD(Computational Fluid Dynamic) calculation results. The developed experimental technique to evaluate the characteristics of two-dimensional foil sections is essential tool to develope new blade sections which have good lift characteristics and better cavitation performances.

• Journal of Digital Contents Society
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• v.16 no.5
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• pp.691-697
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• 2015

Supercomputers are used for many different areas including new product design of industries as well as state-of-the-art science and technology for large amount of computational needs. Tachyon is a 4th supercomputer built at KISTI that is a high-performance parallel computing system with 3,200 computing nodes and infrastructures. This system is currently about 10,000 users and over 170 organizations are used, the number of jobs they are performing work in batch type form through a scheduler. Also, this system logs lots of job scripts, execution environment, library, job status from the job submit to end. In this paper, we analyzed batch jobs information from Sun Grid Engine, that use as a scheduler in Tachyon system, and job executed information in Tachyon System. In particular, we distinguished the fail jobs from the all tasks that users perform and we analyzed the cause of failure. Among them, we can extracted some of jobs that can be regarded as normal jobs through the improvement in those works logged as all of fail jobs.

• Asian Journal of Turfgrass Science
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• v.18 no.4
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• pp.201-209
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• 2004

This study was carried out to develope new zoysiagrass cultivar 'Senock' (Patent registration: 10-2003-0072018). Artificial crossing between collected lines of Z. sinica and Z. matrella (collected in South Korea) was conducted to develope F1 plant (CSM) which was cultivated at field for open self-pollination. Among the open pollinated progenies, CSM8 (Senock) showed superior performance in color and density rating. 'Senock' showed genetically dark green color, with medium leaf width ($3.1\pm0.17mm$), low plant height ($14\pm5.67cm$), and wide leaf angle ($67.3\pm11.1degree$). Height to the lowest leaf blade of this cultivar was $2.0\pm0.14cm$, which may allow low mowing height. Specific bands with primer number OPB7 by RAPD analysis can be used for cultivar identification.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.6
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• pp.690-699
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• 2014

Jet engine modulation(JEM) is a technique used to identify the jet engine type from the radar target signature modulated by periodic rotation of the jet engine mounted on the aircraft target. As a new approach of JEM, this paper proposes an automatic algorithm for extracting the jet engine information. First, the rotation period of the jet engine is yielded from auto-correlation of the JEM signal preprocessed by complex empirical mode decomposition(CEMD). Then, the final blade number is estimated by introducing the DM(Divisor-Multiplier) rule and the 'Scoring' concept into JEM spectral analysis. Application results of the simulated and measured JEM signals demonstrated that the proposed algorithm is effective in accurate and automatic extraction of the jet engine information.