• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.57-62
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• 1998

We have synthesized a 17-residue peptide with the amino acid sequence RQMKEDAKGKSEEELAD corresponding to residues 84-100 of chicken skeletal troponin C. This stretch of the protein sequence is in the middle one-third of the 32-residue 9-turn α-helix that connects the two globular domains of the dumbell-shaped molecule and includes the D/E linker helix. We describe here the solution conformation of the helix linker as studied by circular dichroism (CD) and two-dimensional nuclear magnetic resonance (2-D NMR) spectroscopy. The NOE connectivities together with the vicinal $^3J_{N{\alpha}}$ coupling constants suggest that the peptide exists in a fast conformational equilibrium among several secondary structure: a nascent helix near the N-terminus, a helix, and a substational population of extended and random coil forms. In addition, two interresidue α-α NOEs are observed suggesting a bent structure with a bend that includes the single glycine in position 92. These results are consistent with the ideas that in neutral solution the D/E linker region of the central helix in troponin C can adopt a helical conformation and the central helix may have a segmental flexibility around Gly 92.

• Animal Systematics, Evolution and Diversity
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• v.33 no.2
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• pp.136-139
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• 2017

The genus Iksookimia (Actinopterygii: Cypriniformes: Cobitidae) is a bottom-dwelling freshwater loaches, which are well-known as their endemism and high geographic variation. However, population genetic relationships among Iksookimia spp. have remained unclear due to a shortage of genetic markers that can be applied generally in the genus. Here, we developed high-resolving microsatellite markers using I. koreensis and I. longicorpa as representatives of Iksookimia species because of their wide distribution range and phylogenetic position. Ten of polymorphic microsatellite loci were isolated from Iksookimia koreensis and were successfully cross-amplified in I. longicorpa. The mean number of observed alleles per locus was about 10.4 (range, 2-17) for I. koreensis and about 13.2 (range, 2-24) for I. longicorpa. The loci, IK03 and IK08, deviated from the Hardy-Weinberg equilibrium in I. koreensis, after applying the Bonferroni correction. The microsatellite markers obtained in the present study will be useful to evaluate population genetic structure and to establish conservation strategies for I. koreensis and related Iksookimia species.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.627-635
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• 2021

The speed of rail vehicles become higher and higher over two decades, and China has unveiled a prototype high-speed train in October 2020 that has been able to reach 400 km/h. At such high speeds, wheel-rail force items that had previously been ignored in common computational model should be reevaluated and reconsidered. Aiming at this problem, a new model for investigating the vehicle-bridge interaction at high moving speed is proposed. Comparing with the common model, the new model was more accurate and applicable, because it additionally considers the second-order pseudo-inertia forces effect and its modeling equilibrium position was based on the initial deformed curve of bridge, which could include the influences of temperature, pre-camber, shrinkage and creep deformation, and pier uneven settlement, etc. Taking 5 km/h as the speed interval, the dynamic responses of the classical vehicle-bridge system in the speed range of 5 km/h to 400 km/h are studied. The results show that ignoring the second-order pseudo-inertia force will underestimate the dynamic response of vehicle-bridge system and make the high-speed railway bridge structure design unsafe.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.3
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• pp.1-13
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• 2021

Effects of the nozzle wall angles on the supersonic flow field in a thrust optimized nozzle were numerically investigated. The combustor and operating condition of 30-tonf rocket engine was selected to study the optimum nozzle shape. The nozzle flow of combustion products was realized by the shifting equilibrium calculation for the propellant of kerosene-LOx. The change of nozzle wall angles induced different developing patterns of the internal and secondary shock wave. The optimum nozzle was obtained when the internal shock was in a specific position at the nozzle outlet. The nozzle wall angles of the optimum nozzle were very similar to those of the optimum nozzle which does not consider the shock wave.

• Journal of the Korean Society of Radiology
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• v.11 no.3
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• pp.171-175
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• 2017

In the non-destructive inspection field, we invest a lot of time and resources in developing the radiation source system to ensure the safety of the workers. However, the probability of accidents is still high. In order to prevent potential radiation accidents in advance, it is necessary to directly verify the position of the radiation source, but the research is still insufficient. In this study, we developed a monitoring system that can detect the position of the radiation source in the source guide tube in the gamma-ray irradiator. The characteristics of the radiation detector are estimated by monte carlo simulation. As a result, the radiation detector for Ir-192 gamma-ray energy was analyzed to have secondary electron equilibrium at $150{\mu}m$ regardless of the semiconductor material. Also, it is expected that the gamma ray response characteristic is the best in $HgI_2$. These results are expected to be used as a basis for determining the optimal thickness of the radiation detector located in the detection part of the future monitoring system. In addition, when developing a monitoring system based on this, radiation workers can easily recognize the danger and secure safety, as well as prevent and preemptively respond to potential radiation accidents.

• Geotechnical Engineering
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• v.13 no.4
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• pp.37-54
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• 1997

This paper is to investigate the bearing capacity and the failure mechanism of slope subjected to strip surcharges adjassent to embankment slope of sandy soil. Parametric model tests under plain strain condition were performed by changing width of footing, relative density of slope materials, and position of footing from the crest of slopes. For model tests, Jumunjin standard sand was used as the slope material and its relative density was 45% and 70%, respectively. The angle of slope was formed with 1 : 1.5 and 1 2. Rigid model footings, made of aluminuu were used with their widths of 4, 7, 10 and 12cm. For the position of model footing, position ratios, distance of model footing from the crest of slope divided by footing width, were 0, 0.5, 1, 2, 3, 4, 5. Failure mechanism was observed by using ink colored sands and markers inserted in model slopes. Ultimate bearing capacity obtained from tests was analyzed and compared with limit equilibrium method, limit analysis method and empirical equation. Characteristics of load-settlement curves and failure mechanism were also analyzed and compared with the existing theories. Thus, their effects on ultimate bearing capacity of model footing adjacent to slope were assessed.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1795-1802
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• 2005

Potential energy curves and internuclear (M-X) distance variations for dissociation reactions of $[MX_4]^{2-}$ into ($[MX_3]^-$ + $X^-$) have been calculated using ab initio Hartree-Fock (HF), second order M$\ddot{o}$ller-Plesset perturbation (MP2), and Density Functional Theory (DFT) methods with a triple zeta plus polarization (TZP) basis set. The equilibrium geometrical structures of $[MX_4]^{2-}$ are optimized to tetrahedral geometry for $[NiX_4]^{2-}$ and square planar geometry for ($[PdX_4]^{2-}$ and $[PtX_4]^{2-}$). The bond (M-X) distances of $[NiCl_4]^{2-}$, $[NiBr_4]^{2-}$, $[PdCl_4]^{2-}$, $[PdBr_4]^{2-}$, $[PtCl_4]^{2-}$, and $[PtBr_4]^{2-}$ at the DFT level are 2.258, 2.332, 2.351, 2.476, 2.367, and 2.493 $\AA$, respectively. The dissociation energies for the bond dissociation of ($[MX_3]^-$${\cdot}{\cdot}{\cdot}$$X^-$) at the DFT level are found to be 4.73 eV for $[NiCl_4]^{2-}$, 4.89 eV for $[NiBr_4]^{2-}$, 4.93 eV for $[PdCl_4]^{2-}$, 5.57 eV for $[PdBr_4]^{2-}$, 5.44 eV for $[PtCl_4]^{2-}$, and 5.87 eV for $[PtBr_4]^{2-}$. As the (M${\cdot}{\cdot}{\cdot}$X) distance of ($[MX_3]^-$${\cdot}{\cdot}{\cdot}$$X^-$) increases, the distance variation (Rt) of trans (M-X) bond at the trans-position is shorter than those (Rc) of two cis (M-X) bonds at the cisposition. Simultaneously the atomic charge variation of trans-X atom is more positive than those of equilibrium $[MX_4]^{2-}$ structures, while the variation of leaving X group is more positive.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.5-13
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• 2008

Purpose: This review article was written to investigate what kind of forces are acting on the contact lens fitted on the cornea and its subsequent motion. Methods: A capillary action-induced force develops in the tear layer between the lens and cornea, which leads to the restoring force due to difference in layer thickness according to lens rotation. The characteristics of the lens movement can be determined by the various factors such as friction between eyelid and lens, acceleration force based on blinking and the restoring force incorporated with the viscous damping force. A mathematical model which consists of the differential equations and their numerical solution was proposed to analyze the damped motion of lenses. The model predicts the time dependence of lenses during and after the blink varying the BC, blink period and eyelid pressure. Results: It was found that both the blink period and lid pressure increases the movement increases because of the enhanced lid friction. As the BC increases the viscous damping reduces due to the lacrimal layer's increase which resulted in the enhanced lens motion. After blink the lens illustrates the damped oscillation because of the restoring force by the increased lacrimal layer thickness and reduced viscous resistance. The time for the lens to return to the equilibrium shortens as the BC increase because of the resistance reduction. Conclusions: The movement of the contact lens is governed by the characteristics of the lacrimal layer between the lens and cornea as well as the lid blink.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.3
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• pp.51-61
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• 1989

Recently, the growth in the propulsion power and propeller size of typical energy saving ships has resulted in severe damages of the oil-lubricated stern tube bearing. Consequently, a more rational analytical method for the design of the shafting system is required. In this paper an analytical method applicable to the design of the oil-lubricated stern tube bearing and shafting system is presented. The method consists of the finite element analysis of the shafting system and the oil film hydrodynamics. The shafting system is modeled as a three-dimensional problem using beam elements taking account for the steady components of thrust, lateral forces and moments of the propeller as well as the elastic foundation effects. The oil film hydrodynamics is modeled as a two-dimensional problem. Equal and retangular elements employing hourglass control method are used for the construction of the oil film fluidity matrix. To search the quasi-static equilibrium position between the propeller shaft and the oil film, an optimization technique is employed. Some numerical results based on the proposed method are compared with some measured and numerical data available. They show acceptable agreements with the data.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.4
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• pp.525-535
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• 1999

In this study, a new method of fabricated concrete deck bridge construction is proposed. This paper details the method in which concrete multi-girders and fabricated concrete decks are rested on the upper flange of the girder and the female to female type sheat-key is formed to connect girder and deck. The finite element analysis is performed to verify the accuracy of the structural behaviors of the fabricated concrete deck bridge by comparing with experimental results. The first task performed is the analysis of the equilibrium of the member force occurring between the deck and the girder. After verifying equilibrium of the member force determined by the finite element analysis, this process is applied to the analysis of maximum member force as the position of design load. This task is utilized to determine the safety of each member according to the same scale finite element model. The final process in this study is to compare the deflection of girders used in experiment with that of the same scale finite element model to verify the strength of fabricated cincrete deck bridge. By this comparison, it is shown that the behavior of the fabricated concrete deck bridge is almost same as the finite element analysis. The second task is to analyze the load distribution effect according to the number of diaphragms and the composite effect due to the cinnection of the deck and girder by the finite element analysis. From the results of second task, it is found that the load distribution effect is not related to the number of diaphragms in case of the central loading, but is related to the number of diaphragms for eccentric loading. Analysis of the load distribution indicates that the effective number of diaphragm is three. It is also shown that the maximum deflection is decreased to almost one half due to the composite action of the deck and girder.