• 한국소음진동공학회논문집
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• 제14권12호
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• pp.1295-1303
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• 2004

In this Paper a dynamic behavior of a cracked cantilever pipe conveying fluid with the moving mass is presented. It has the results focused on the response characteristics. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The cracked section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. When the fluid velocity is constant, the influences of the crack severity, the position of the crack, the moving mass and its velocity, and the coupling of these factors on the tip-displacement of the cantilever pipe are depicted.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2216-2224
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• 2004

In this paper we studied about the effect of the open crack and the moving mass on the dynamic behavior of simply supported pipe conveying fluid. The equation of motion is derived by using Lagrange's equation and analyzed by numerical method. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments i.e. the crack is modeled as a rotational spring. The influences of the crack severity, the position of the crack, the moving mass and its velocity, the velocity of fluid, and the coupling of these factors on the vibration mode, the frequency, and the mid-span displacement of the simply supported pipe are depicted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1625-1630
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• 2003

An iterative modal analysis approach is developed to determine the effect of the transverse open cracks and the moving mass on the dynamic behavior of simply supported pipe conveying fluid. The equation of motion is derived by using Lagrange's equation. The influences of the velocity of moving mass, the velocity of fluid flow and a crack have been studied on the dynamic behavior of a simply supported pipe system by numerical method. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. that is, the crack is modelled as a rotational spring. Totally, as the velocity of fluid flow is increased, the mid-span deflection of simply supported pipe conveying fluid is increased. The position of the crack is middle point of the pipe, the mid-span deflection of simply supported pipe presents maximum deflection.

• 한국소음진동공학회논문집
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• 제13권9호
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• pp.720-729
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• 2003

An iterative modal analysis approach is developed to determine the effect of transverse open cracks on the dynamic behavior of simply supported Euler-Bernoulli beam with the moving mass. The influences of the depth and the position of the crack in the beam have been studied on the dynamic behavior of the simply supported beam system by numerical method. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modelled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. As the depth of the crack is increased the frequency of the simply supported beam with the moving mass is increased.

• 천문학회보
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• 제36권2호
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• pp.77.1-77.1
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• 2011

The sizes of galaxies are correlated with their masses or luminosities, which is known as the 'mass-size relation' or 'luminosity-size relation'. Those relations show scatters in the sense that the sizes of galaxies range somewhat widely at given mass or luminosity, which is largely affected by the morphologies or colors of the sample galaxies. However, the scatters of the relations are still large even when the galaxy sample is limited to red early-type galaxies: at fixed mass or luminosity, the largest red early-type galaxies are larger than the smallest red early-type galaxies by a factor of 4 - 5. This is a progress report of a study on what determines the sizes of red early-type galaxies. We investigate how the sizes of red early-type galaxies depend on several quantities of them, such as color, color gradient, axis ratio, local number density and mass-to-light ratio. The physical implication of those preliminary results is discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1442-1446
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• 2004

The heat (mass) transfer characteristics on the blade surface of a first-stage turbine rotor cascade has been investigated by employing the naphthalene sublimation technique. A four-axis profile measurement system is employed for the measurements of the local heat (mass) transfer coefficient on the curved blade surface. The experiments are carried out for two free-stream turbulence intensities of 1.2% and 14.7%. The high free-stream turbulence results in more uniform distributions of heat load on the both pressure and suction surfaces and in an early boundary-layer separation on the suction surface. The heat (mass) transfer enhancement on the suction surface due to the endwall vortices is found to be relatively small under the high free-stream turbulence.

• 대한기계학회논문집A
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• 제28권4호
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• pp.419-426
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• 2004

In this paper, studied about the effect of open crack and the moving mass on the dynamic behavior of simply supported pipe conveying fluid. The equation of motion is derived by using Lagrange's equation. The influences of the velocity of moving mass, the velocity of fluid flow and a crack have been studied on the dynamic behavior of a simply supported pipe system by numerical method. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. Therefore, the crack is modelled as a rotational spring. Totally, as the velocity of fluid flow is increased, the mid-span deflection of simply supported pipe conveying fluid is increased. The position of the crack is located in the middle point of the pipe, the mid-span deflection of simply supported pipe presents maximum deflection.

• 대한가정학회지
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• 제43권11호
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• pp.49-58
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• 2005

This study investigated the recognition and preference of native local foods in area by students living in Jeonju. Statistical data analysis was completed using the SPSS 10.0 program. The recognition of native local foods was generally poor: Among 56 kinds of native foods only Jeonjubibimbab, Jeonjukongnamulkukbob and Sunsoonsabockbunjasul were highly recognized, whereas the other native foods (such as Pungchyunjangaguvi. Namwonchuatang, Jeonjukongnamulkukbob, Sunsoonsabockbunjasul, Pungchyunjangaguyi, Namwonchuatang, Minmulgokiajuk etc.) were very poorly recognized by students. About $48.6\%$ of the students acquired the knowledge on cooking the native local foods from their mother or grandmother. About half of the students had eaten the native local foods in a restaurant, but not at home. The reasons to eat the native local foods were 'curiosity', 'favorite' and 'consider about health and nutrition'. The most common frequency of consumption of the native foods by the students was once a month($24.0\%$). However $74.9\%$ of the students did not eat local foods because they did not have a opportunity to eat them. About $49.1\%$ of the students responded that the 'unknown cooking method' was an important problem for the further development for native local foods. Most of the students($97.3\%$) responded, somewhat hypocritically, that native local foods were a very important part of our culture, so they must be maintained. In conclusion, the further development of native local foods was dependent on the cooperation with different institutions (e.g. marketing of local mass media, local events, family education).

• 한국추진공학회지
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• 제16권1호
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• pp.9-15
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• 2012

하이브리드 연소실의 국부 압력과 속도변화를 고려하는 비정상 내탄도 해석모델을 제안하고 이를 바탕으로 연소실 내 국부영역에서 내탄도 특성인자의 변화를 도출하였다. 해석 모델 검증을 위하여 연소실 전후단의 압력을 측정한 실험결과와 해석결과를 비교하여 실험과 해석결과가 유사함을 확인하고 연소 효율을 평가 하였다. 하류방향으로 산화제 유량이 변화하므로 이에 따른 연소실 국부영역의 압력, 온도, 연료의 후퇴율 및 연소가스의 유속 변화를 정량적으로 고찰하였다.

• 천문학회보
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• 제45권1호
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• pp.65.3-66
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• 2020

We use the IllustrisTNG cosmological hydrodynamical simulation to study the evolution of star formation rate (SFR)-density relation over cosmic time. We construct several samples of galaxies at different redshifts from z=2.0 to z=0.0, which have the same comoving number density. The SFR of galaxies decreases with local density at z=0.0, but its dependence on local density becomes weaker with redshift. At z≳1.0, the SFR of galaxies increases with local density (reversal of the SFR-density relation), and its dependence becomes stronger with redshift. This change of SFR-density relation with redshift still remains even when fixing the stellar masses of galaxies. The dependence of SFR on the distance to a galaxy cluster also shows a change with redshift in a way similar to the case based on local density, but the reversal happens at a higher redshift, z~1.5, in clusters. On the other hand, the molecular gas fraction always decreases with local density regardless of redshift at z=0.0-2.0 even though the dependence becomes weaker when we fix the stellar mass. Our study demonstrates that the observed reversal of the SFR-density relation at z≳1.0 can be successfully reproduced in cosmological simulations. Our results are consistent with the idea that massive, star-forming galaxies are strongly clustered at high redshifts, forming larger structures. These galaxies then consume their gas faster than those in low-density regions through frequent interactions with other galaxies, ending up being quiescent in the local universe.