• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1567-1572
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• 2009

Conformational change of ubiquitin variant with valine to alanine mutation at sequence position 26 was studied by varying solvent pH. Fluorescence emission spectra indicated that this variant ubiquitin has some residual structures in acidic and basic solution as compared to denaturant-induced unfolded state. Far-UV circular dichroic spectra indicated that the base-denatured state had more secondary structure than the acid-denatured state. Near-UV circular dichroic spectra indicated that the aromatic side-chains were in the relatively more rigid environment in the base-denatured state than those in the acid-denatured state. Although it appears that the more tertiary structure present in the base-denatured state, refolding reactions measured by stopped-flow fluorescence device suggest that both the acid- and base-denatured states occur before the major folding transition state. The acid- and base-denatured states are considered to reflect the early event of protein folding process.

• Journal of Welding and Joining
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• 제19권6호
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• pp.608-613
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• 2001

In this study, the rotary bending fatigue test was carried out with two kinds of base metal, martensite stainless steel STR3 and austenite stainless steel STR35 and the dissimilar friction welded material with them. To compare the fatigue fifes according to the notch positions, the small circular defect was worked on the bonded line, 1.0mm and 0.5mm distance form the bonded line. The fatigue limits of the STR3 and STR35 base metal were 429.0MPa and 409.4MPa respectably. In comparison with fatigue life at the same notch positions, the STR35 specimens showed about 190% for base metal, 82% for 1.0mm distance notched specimens higher than that of the STR3. But the fatigue life of the 0.5mm distance notched STR35 specimen showed about 35% lower than that of the STR3 specimen. And the bonded line notched specimen was much lower fatigue life than the other specimens because of separation of the bonded line.

• Journal of applied mathematics & informatics
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• 제22권1_2호
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• pp.67-82
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• 2006

In this paper, we present a finite difference method for the implementation of the rotation of a circular cylinder in the incompressible flow field by solving the two-dimensional unsteady Navier-Stokes equations. The approach is to use staggered grid method so that the accuracy and order of convergence of the associated algorithms can be maintained. The proposed method is easy to be implemented and is effective. A set of simulations for the flow dynamics is provided to show the computational results.

• Geomechanics and Engineering
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• 제18권4호
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• pp.391-406
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• 2019

The aim of this paper was to study the influence of the footing shape and the effect of the roughness of the foundation base on the bearing capacity of shallow foundations on rock masses. For this purpose the finite difference method was used to analyze the bearing capacity of various types and states of rock masses under the assumption of Hoek-Brown failure criterion, for both plane strain and axisymmetric model, and considering smooth and rough interface. The results were analyzed based on a sensitivity study of four varying parameters: foundation width, rock material constant (mo), uniaxial compressive strength and geological strength index. Knowing how each parameter influences the bearing capacity depending on the footing shape (circular vs strip footing) and the footing base interface roughness (smooth vs rough), two correlation factors were developed to estimate the percentage increase of the ultimate bearing capacity as a function of the footing shape and the roughness of the footing base interface.

• 한국강구조학회 논문집
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• 제16권4호통권71호
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• pp.471-478
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• 2004

이 연구의 목적은 노출형 원형강관 주각이 중심축압축력을 받을 때 그 역학적 거동을 실험적으로 조사하고 탄성수치해석을 통하여 실험결과를 검토하고자 함에 있다. 실험에 앞서 AISC의 제안식 및 기존 연구에 관한 문헌조사를 실시하였다. 실험으로 중심축압축가력을 실시하였으며 베이스 플레이트 두께를 변수로 하여 두께 9mm부터 35mm까지의 9개의 시험체를 제작하였다. 실험결과는 하중 - 베이스 플레이트 수직변위관계, 하중 - 베이스 플레이트 변형도관계 등으로 정리하였다. 실험결과를 검토하기 위하여 탄성수치해석을 실시하였으며 탄성수치해석 프로그램으로는 Ansys version 6.1을 사용하였다. 실험 및 해석결과는 향후 실시할 비탄성해석결과와 함께 설계식 제안에 사용될 것이다.

• 대한전자공학회논문지
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• 제3권3호
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• pp.14-21
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• 1966

원형방사상편향의 기록방식을 이용한 방사선계측장치로서 그 장치내용과 계측에의 응용례를 기술하였다. 장치의 전자관회로에 있어서 특수한 승산회로를 안출하므로써 원형시간축 뿐만 아니라 그 위에 나타난 펄스의 직선성도 잘 고려되었다. 논리회로에 의해서 1싸이클동안만 밝게하고 다음의 수사이클 동안을 어둡게 하므로써 방사선에 의한 랜돔 펄스를 원형시간축상에 나타내어 이것을 사진으로 기록할 수 있게 하였다. 본장치는 단수명핵종의 감리곡선과 그 파고분포곡선을 얻는데 적당한 것이다.

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.143-150
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• 1999

Multipurpose fisheries base was conceptually designed to establish marine ranching system in the coastal waters around Tongyoung, southern sea of Korea. Fisheries base for marine ranching system has integrated various facilities which were required for the process of spawning, rearing, training, releasing, monitoring and catching functions. This base has five steel piles for supporting upper structure and systems. Four steel piles are surrounded by circular net pen made by steel wire, they have the function of the protection against fouling for pile and scouring for bottom soil as well as secondary rearing and short stocking. We can use the last pile to moor a ship and access to the base. Principal structure with steel piles is designed by optimization technique considering design external forces in the coastal waters of return period of 50 years. Design optimization Problem is formulated for this base. Optimal design of multipurpose fisheries base is numerically investigated by sequential quadratic programming method.

• 대한기계학회논문집B
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• 제20권8호
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• pp.2637-2649
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• 1996

Flow characteristics and aerodynamic forces acting on an elliptic cylinder placed in a plane boundary layer were investigated experimentally. Four cylinder models with axis ratio(major axis to minor axis, AR=A/B) of 1, 2, 3, and 4 having the same equivalent diameter were used in this experiment. The Reynolds number based on the equivalent diameter $D_e$(=20mm) was 13,000. In the case of circular cylinder, regular vortex shedding occurs for the cylinder gaps larger than G/B=0.3 and is not almost related to the boundary layer thickness. But, for the elliptic cylinders, the vortex shedding frequency is increased with increasing the gap ratio (G/B) and the axis ratio (AR) of elliptic cylinders. The maximum drag coefficient acting on a circular cylinder is mainly affected by the boundary layer thickness. But, the elliptic cylinders(AR$\geq$2), except for the smaller gap G/B<0.2, show a nearly constant drag coefficient which is much smaller than that of a circular cylinder. The base pressure on the flat plate decreases with increasing the axis ratio(AR) of the elliptic cylinder. In the case of a circular cylinder, the base pressure has the minimum value at the gap ratio G/B=0.4, but it occurs at G/D=2 for elliptic cylinders. The mean velocity of the cylinder wake is quickly recovered at a small cylinder height ratio(H/$\delta$), but the turbulent intensity is rapidly recovered at a large cylinder height ratio(H/$\delta$). The effective wake region in the plane boundary layer is shrinkaged with increasing the axis ratio(AR) of elliptic cylinder. And the drag coefficient and streamwise turbulent intensity of the elliptic cylinder with AR=4 are less than half of those for the circular cylinder(AR=1).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.253-258
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• 2001

Control of drag force on a circular cylinder using a detached splitter plate is numerically studied for laminar flow. A splitter plate with the same length as the cylinder diameter(d) is placed horizontally in the wake region. Its position is described by the gap ratio(G/d), where G represents the gap between the cylinder base point and the leading edge of the plate. The drag varies with the gap ratio; it has the minimum value at a certain gap ratio for each Reynolds number. The drag sharply increases past the optimum gap ratio; this seems to be related to the sudden change in the bubble size in the wake region. This trend is consistent with the experimental observation currently available in case of turbulent flow. It is also found that the net drag coefficient significantly depends on the variation of base suction coefficient.

• 대한기계학회논문집A
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• 제30권2호
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• pp.171-178
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• 2006

Experimental and theoretical study of the non-planar response motions of a circular cantilever beam subject to base harmonic excitation has been presented in this paper work. Theoretical research is conducted using two non-linear coupled integral-differential equations of motion. These equations contain cubic linearities due do curvature term and inertial term. A combination of the Galerkin procedure and the method of multiple scales are used to construct a first-order uniform expansion for the case of one-to-one resonance. The results show that the non-linear geometric terms are very important for the low-frequency modes of the first and second mode. The non-linear inertia terms are also important for the high-frequency modes. We present the quantitative and qualitative results for non-planar motions of the dynamic behavior.