• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.15-18
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• 2003

The present study addresses an experimental investigations of the near field flow structures of supersonic, dual, coaxial, swirl jet. The swirl stream is discharged from the secondary annular nozzle and the primary inner nozzle provides the sonic and supersonic free jets. The interactions between the secondary swirl and inner soni $c^ersonic jets are quantified by a fine pilot impact and static pressure measurements and are visualized by using a shadowgraph optical method. The pressure ratios of the secondary swirl and primary soni $c^ersonic jets are varied below 7.0. Experiments are conducted to investigate the effects of the secondary swirl stream on the primary sonic and supersonic jets, compared with the secondary stream of no swirl. The results show that the presence of annular swirl stream causes the Mach disk to move more downstream, with the increased diameter, and remarkably reduces the fluctuations of the impact pressures in the supersonic dual coaxial jet, compared with the case of the secondary annular stream of no swirl.swirl.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.E
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• pp.45-59
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• 1992

At downstream part of the hydraulic structures such as spiliway or drainage gate, jet flow can occur by gate opening. If stream bed is not hard or bed protection is not sufficient, scour hole will be formed due to high shear stress of the jet flow. We call this primary scour. Once the scour hole is formed, a vortex occurs in it and this vortex causes additional scour. We call this secondary scour. The primary scour proceeds to downstream together with flow direction but the secondary one proceeds to upstream direction opposite to it. If the secondary one continues and reaches to the hydraulic structure, it can undermine the bottom of hydraulic structure and this will lead to failure of structure itself. Thus, it is necessary to know the physical features of the vortex structure in a scour hole, which is the main mechanism of the secondary scour. This study deals with the characteristics of the vortex structure and its shear stress which causes the secondary scour.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.280-282
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• 2005

A ribonucleic acid (RNA) is one of the two types of nucleic acids found in living organisms. An RNA molecule represents a long chain of monomers called nucleotides. The sequence of nucleotides of an RNA molecule constitutes its primary structure, and the pattern of pairing between nucleotides determines the secondary structure of an RNA. Non-coding RNA genes produce transcripts that exert their function without ever producing proteins. Predicting the secondary structure of non-coding RNAs is very important for understanding their functions. We focus on Nussinov's algorithm as useful techniques for predicting RNA secondary structures. We introduce a new traceback matrix and scoring table to improve above algorithm. And the improved algorithm provides better levels of performance than the originals.

• Natural Product Sciences
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• v.26 no.1
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• pp.10-27
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• 2020

Endophytes are defined as microorganisms that spend part of lifetime interior of plant tissues without causing negative effects. They have been used for agricultural purpose, biofuel production, bioremediation, medication, etc. In particular, endophytes have been emerged as a good source for bioactive secondary metabolites. A large number of secondary metabolites are currently being reported. In this report, we focus on the secondary metabolites that were originated from endophytic fungi inhabiting medicinal plants. They were classified into several groups such as nitrogenous compounds, steroids, sulfide-containing metabolites, terpenoids, polyketides, and miscellaneous for discussion of chemical structures and biological activities.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1649-1654
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• 2004

The near field structures of an under-expanded, dual, coaxial, jets issuing from the coaxial nozzles with four different geometries are visualized by using a shadowgraph optical method. Experiments are conducted to investigate the effects of the nozzle-lip thickness, secondary stream thickness, the nozzle pressure ratio and the secondary swirl stream on the characteristics of under-expanded jets. The results show that the presence of secondary annular swirling stream causes the Mach disk to move further downstream and increases its diameter, which decreases with a decrease in the nozzle-lip thickness. The secondary stream thickness has an influence on the location of an annular shock wave.

• 한국전기화학회:학술대회논문집
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• 1998.10a
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• pp.83-83
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• 1998

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.2
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• pp.133-148
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• 2005

Since understanding of similarities and differences among protein structures is very important for the study of the relationship between structure and function, many protein structure comparison systems have been developed. Hut, unfortunately, these systems introduce their own protein data derived from the PDB(Protein Data Bank), which are needed in their algorithms for comparing protein structures. In addition, according to the rapid increase in the size of PDB, these systems require much more computation to search for common substructures in their databases. In this paper, we introduce a protein structure comparison system named WS4E(A Web-Based Searching Substructures of Secondary Structure Elements) based on a PSAML database which stores PSAML documents using the eXist open XML DBMS. PSAML(Protein Structure Abstraction Markup Language) is an XML representation of protein data, describing a protein structure as the secondary structures of the protein and their relationships. Using the PSAML database, the WS4E provides web services searching for common substructures among proteins represented in PSAML. In addition, to reduce the number of candidate protein structures to be compared in the PSAML database, we used topology strings which contain the spatial information of secondary structures in a protein.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.581-586
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• 2003

3%C-18%Cr-1%Mo-2%Ni-1%Mn high chromium cast iron was casted and destabilized at temperatures of 900, 1000 and $1100^{\circ}C$ for 1, 2, 4 and 8hr under $N_2$atmosphere to observe the effect of destabilization temperature and time on the carbide and matrix structures. In as-cast condition, the microstructure consisted of $M_{ 7}$$C_3$ carbides and matrix structures which were composed of 91.50% austenite and 8.50% martensite. Numerous fine secondary carbides were observed in the specimens destabilized at $900^{\circ}C$ for 1, 2, 4 and 8hr. But, the number of secondary carbides were much reduced with the increased destabilization temperature. More austenite was formed in the matrix with the higher destabilization temperature. The amounts of austenite in the matrix were 4.23% at $900^{\circ}C$, 29.68% at $1000^{\circ}C$ and 66.51% at$ 1100^{\circ}C$, respectively. However, the effect of destabilization time on the secondary carbide and matrix was very weak compared with that of destabilization temperature. The ranges of the amount of austenite in the matrix from 1hr to 8hr destabilization heat treatment were: 3.95%-4.35% at $900^{\circ}C$, 28.89%-30.15% at $1000^{\circ}C$ and 65.13%-67.12% at $1100^{\circ}C$, respectively. The variation ranges were very narrow. The equilibrium concentration of C and Cr in austenite was already reached within 1hr during destabilization heat treatment. After an attainment of the equilibrium concentration of C and Cr in austenite, no more secondary carbide was precipitated from the matrix.

• Journal of the Korean Society of Safety
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• v.31 no.2
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• pp.26-32
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• 2016

In previous studies on LPG siting in Korea, the scope have not included the probability of the secondary events of adjacent LPG tanks or structures from an explosion source. Therefore, it is essential to first identify the phenomenon which can be caused by BLEVE and then, properly assess their effects to each target including secondary event. In this study, we calculated the effects from a potential BLEVE of 15 ton LPG tank causing damages of storage tanks (LPG), structures and human using Phast ver. 6.7 and then suggested three risk zones (Zone I, II, III) assuming the consequences such as overpressure, heat radiation and missile effect by fragments. Zone I and II are divided at the line of 50% occurrence of the secondary event. Zone II and III are divided by Individual Risk(IR). The zone approach in this study can be used for more effective and safer Land Use Planning (LUP) for the future.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.481-487
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• 2010

The equivalent circuits intended to analyze the characteristics of IPT systems can be shown in structures similar to those of existing transformers. IPT systems are composed of combinations of the primary and secondary coils based on magnetic coupling, and the performances are determined by the lengths or the degrees of magnetic coupling of current collecting conductors(secondary) and feeding rails (primary) and system performances become the maximum when they are coupled under the optimum condition. To maximize the output currents of the secondary side, the shapes of iron cores and the structures of coils etc should be considered. To this end, three types of IPT system simulation models were selected and they were analyzed using an electromagnetic field analyzing program. To compare the types with each other, the sizes of the IPT systems and the primary side voltages etc were made to be the same. The electromagnetic fields were analyzed while changing the thicknesses of the cores and the lengths of the air gap etc and the results were analyzed in order to derive the optimum specifications.