• 설비공학논문집
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• 제12권8호
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• pp.763-770
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• 2000

In tunnel ventilation, the Purpose of ventilation control is to keep the required pollution level with minimum consumption of energy But tunnel ventilation has large disturbances caused by discharge of pollutants, traffic forces especially strong for longitudinal ventilation. Hence in this paper, the tunnel ventilation control logic applying fuzzy control theories is proposed and the simulation program of tunnel ventilation control is developed. The characteristics of longitudinal ventilation with jet fans are estimated and the effect of the proposed tunnel ventilation control is verified by the simulation program.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.255-262
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• 2003

In present Korea Highway Bridge Standards the lap splice of longitudinal bars in a potential plastic hinge region is allowed so that large amount of transverse rebar specified in high seismicity regions Is required to prevent brittle bond failure If the brittle failure effects can be completely removed from the conventional designed piers, the amount of transverse rebar will be reduced drastically. In this study scaled models with solid and hollow rectangular sections were tested to investigate the seismic behavior of RC piers with 50％ of lap-spliced longitudinal bars in plastic hinge regions. In the tests the typical flexural failure conducting a ductile behavior were observed in both models. It is shown that the 50％ of lap-spliced bars can be considered as a good alternative of seismic detailing for longitudinal bars.

• 한국가구학회지
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• 제28권3호
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• pp.248-258
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• 2017

A study was carried out to observe the 1% aqueous safranine solution flow speed in longitudinal and radial directions of softwood Thuja orientalis L., diffuse-porous wood Gmelina arborea Roxb., and ring-porous wood Phellodendron amurense Rupr., Longitudinal flow was considered from bottom to top while the radial flow was considered from bark to pith directions. In radial direction, ray cells and in longitudinal direction tracheids, vessel and wood fiber were considered for the measurement of liquid penetration speed at less than 12% moisture contents(MC). The variation of penetration speed for different species was observed and the reasons behind for this variation were explored. The highest radial penetration depth was found in ray parenchyma of T. orientalis but the lowest one was found in ray parenchyma of P. amurense. The average liquid penetration depth in longitudinal trachied of T. orientalis was found the highest among all the other cells. The penetration depth in fiber of G. arborea was found the lowest among the other longitudinal cells. It was found that cell dimension and also meniscus angle of safranine solution with cell walls were the prime factors for the variation of liquid flow speed in wood. Vessel was found to facilitate prime role in longitudinal penetration for hardwood species. The penetration depth in vessel of G. arborea was found highest among all vessels. Anatomical features like ray parenchyma cell length and diameter, end-wall pits number were found also responsible fluid flow differences. Initially liquid penetration speed was high and the nit gradually decreased in an uneven rate. Liquid flow was captured via video and the penetration depths in those cells were measured. It was found that even in presence of abundant rays in hardwood species, penetration depth of liquid in radial direction of softwood species was found high. Herein the ray length, lumen area, end wall pit diameter determined the radial permeability. On the other hand, vessel and fiber structure affected the longitudinal flow of liquids. Following a go-stop-go cycle, the penetration speed of a liquid decreased over time.

• 아동학회지
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• 제30권4호
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• pp.47-56
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• 2009

This longitudinal study examined picture book reading practices with very young children and its influence on early intellectual development. The home picture book reading activities of 322 infants and their mothers were assessed by questionnaire every 6 months from 18 months till 42 months of age. Infants' IQ was measured with Korean-Wechsler Preschool and Primary Scale of Intelligence(Park et al., 1996) at 42 months. Results showed that monthly book expense (r=.28, p<.01) and infants' asking for reading (r=.14, p<.05) at 18 months were positively correlated with IQ at 42 months. Reading time between 24 and 42 months correlated positively with IQ(r=.17~.34, p<.01). These results reveal the importance of early book environment and actual reading time in the intellectual development of very young children.

• 아동학회지
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• 제31권1호
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• pp.1-17
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• 2010

This study explored the differences in gender, developmental period and parents in terms of parenting, the cross-sectional and longitudinal relationships in parenting by gender, and the cross-sectional and longitudinal relationships between participant roles in bullying situations and parenting by gender. The subjects were 498 4-5th grade children and the instruments utilized in this study were the Parental Bonding Instrument (Bowers, Smith, & Binney, 1994) and the Participant Roles Scale (Sutton & Smith, 1999). The subjects were contacted again one year after the first contact. Results showed that the relationships between parents were longitudinally quite stable. Girls whose fathers had higher levels of accurate monitoring were more likely to be defenders cross-sectionally. Girls whose parents had more accurate monitoring were less likely to be victims longitudinally. The results underscore the importance of examining both gender and participant roles in bullying situations.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1157-1162
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• 2000

Transverse stress and longitudinal crack which are induced by temperature difference in box-girder sections and slab of which box-girder is composed have an important effect on endurance and economical efficiency of bridges. The study on longitudinal behavior of bridges which are subject to thermal load is reflected on the design of bridges. But, the study on transverse behavior of bridges has been performed just recently in foreign countries of finding the cause of longitudinal crack and in Korea, has not been tried in spite of large temperature variance due to geographical condition. This study examines temperature distribution feature in box-girder sections and bridge behavior due to thermal load, with measuring temperature distribution and stress of PSC box-girder bridge which is being constructed actually, and investigates appropriateness of design thermal load of highway bridge design code.

• Korean Journal of Hydrosciences
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• 제8권
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• pp.19-30
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• 1997

The hydraulics of flow within the covered reach of urban streams is very complicated due to the accumulation and interference effect of eddies around the multipli piers supporting the covering slab. An extensive experimental study is done to quantitatively estimate the backwater rise effect caused by various arrays of multiple piers. The factors governing the backwater rise are found out to be the contraction ratio due to the piers. Foude number of the flow, longitudinal pier spacing, and the length of the covered reach. For a single section of lateral pier arralyzed and a multiple regression equation derived. The effect of multiple piers, arrayed in both lateral and longitudinal directions. on the backwater rise is analyzed in terms of the contraction ratio. Froude number, longitudinal pier spacing and the total length of the covered reach. A multiple regression equation for the backwater rise estimation is proposed based on the experimental data collected in this study.

• 소성∙가공
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• 제23권6호
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• pp.369-375
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• 2014

Flexible roll forming allows profiles to have variable cross-sections. However, the profile may have some shape errors, such as, warping which is a major defect. The shape error is induced by geometrical deviations in both the concave zone and the convex zone. In the current study, flexible roll forming was modeled with FE simulations to analyze the shape error and the longitudinal strain distribution along the flange section over the profile. A distribution of analytically calculated longitudinal strains was used to develop relationships between the shape error and the longitudinal strain distribution as a function of the defined shape parameters for the profile. The FE simulations showed that the shape error is primarily affected by the deviations between the distribution of analytically calculated longitudinal strain and the longitudinal strain distribution of the profile. The results show that the shape error can be controlled by designing the shape parameters to control the geometrical deviations at the flange section in the transition zones.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.816-825
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• 2002

During the manufacture of a ship, longitudinal deformation is produced by fillet welding on the BuiltUp beam used to improve the longitudinal strength of a ship. This deformation needs a correcting process separate from a manufacture process and decreases productivity and quality. This deformation is caused by welding moment, which is the value multiplied the shrinking force due to welding by the distance from the neutral axis on a cross section of Built-Up beam. This deformation can be offset by generating a moment which is the same magnitude with and is located in an opposite direction to the welding moment on web plate by induction heating. Accordingly, this study clarifies the creation mechanism of the longitudinal deformation on Built-Up beam with FEM analysis and presents the preventative method of this deformation by induction heating basing the mechanism and verifies its validity through analysis and experiments. The induction heating used here is performed by deciding its location and quantity with experiments and simple equations and by applying them to areal structure.

• 한국해양공학회지
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• 제24권4호
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• pp.32-37
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• 2010

This study presents the attenuation characteristics of the first guided longitudinal wave mode propagating in water-filled, buried steel pipes in order to investigate the effects of soil saturation and compaction on the attenuation patterns. For numerical calculation of attenuation, 10 different combinations of S-wave velocity, P-wave velocity, and soil densities were considered. From the attenuation dispersion curves, which were obtained using Disperse software, we determined that the attenuation decreases as saturation increases, whereas it increases as compaction increases. Over the frequency range from 0.2 to 0.4 MHz, the first longitudinal wave mode has attenuations that are relatively lower than for other ranges, is faster than the first flexural wave mode, and is sensitive to defects aligned in the axial direction. Hence, the first longitudinal wave mode over the mentioned frequency range would be the proper choice for long-range buried pipelines that transport water.