• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.271-278
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• 2006

In design of groyne series, groyne spacing is a important factor and have an effect on not only the characteristics of backward and recirculation flow in groyne zone but also flow field in main channel. It is necessary study about flow pattern of recirculation zone and main channel that is a cause of bad change, local scour and bank erosion by groyne spacing. In this study, flow variation of groyne zone and main chanel for spacing of groynes were analyzed from the experiment results in order to offer a fundamental data that can be used to decide the proper groyne spacing. Experiments were conducted 12 cases for groyne spacing(L) by groyne length(l) rate and the velocity profile was measured using LSPIV and ADV. From the results, two vortex flows developed in recirculation zone for L/l=3~9 and three vortex flows developed over L/l=10. The velocity of backward flow in recirculation zone was decreased up to 20% over L/l=4. The velocity of main channel flow was increased from 1.3 to 2.0 times by groyne spacing and the rate of velocity increased by increasing groyne spacing. The maximum velocity occurred in 0.7~0.8 times of groyne spacing downstream of upper groyne.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.5-14
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• 2001

This paper describes a simplified design method of stabilizing piles based on an experimental tests and an analytical study which can take into account the safety factor of slope and pile spacing. The nonlinear characteristics of the soil-pile interaction for stabilizing piles are modeled by using load transfer method. The interaction factors due to pile spacing and cap rigidity were estimated by using a three dimensional nonlinear finite element approach and laboratory tests. Based on the results obtained, the interaction factors are proposed quantitatively for one-row pile groups with spacing-to-diameter ratios varying far 2.5 to 7.0. The Bishop's simplified method of slope stability analysis is extended to incorporate the soil-pile interaction and determine the safety factor of the reinforced slope. Through the comparative study, it is found that the prediction by present approach is in relatively good agreement with the results of centrifuge tests and field tests and three dimensional finite element analyses.

• Korean Journal of Cognitive Science
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• v.10 no.4
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• pp.27-39
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• 1999

This study examined the relative importance and the most preferred level of factors which were identified through the readability researchs. For this. subjects were given a text constructed in usual letter width with square form letter or non-square form and then. ranked the preference between the text factors. In experiment 1 where a text was printed in square letters. letter size was rated as the most important factor followed by line spacing letter width, line length, letter spacing, line justification, and letter form. But when non-square letters were used in experiment 2. the second most important factor was the letter spacing although letter size still topped the list. These findings indicate the differences in letter designing principles for various types and the unfamiliarity to non-square letter forms for general public. Unlike inYi and Jin(1998) where letter width turned out to be the most sensitive factor, the highest priority should be given to letter size when publishing with usual letter width.

• IMMUNE NETWORK
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• v.2 no.3
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• pp.150-157
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• 2002

Background: Although Tat plays a role as a potent transactivator in the viral gene expression from the Human Immunodeficiency Virus type 1 long terminal repeat (HIV-1 LTR), it does not function efficiently in rodent cells implying the absence of a human specific factor essential for Tat-medicated transactivation in rodent cells. In previous experiments, we demonstrated that one of chimeric forms of TAR (transacting responsive element) of HIV-1 LTR compensated the restriction in rodent cells. Methods: To characterize the nature of the compensation, we tested the effects of several upstream binding factors of HIV-1 LTR by simple substitution, and also examined the role of the configuration of the upstream binding factor(s) indirectly by constructing spacing mutants that contained insertions between Sp1 and TATA box on Tat-mediated transactivation. Results: Human Sp1 had no effect whereas its associated factors displayed differential effects in human and rodent cells. In addition, none of the spacing mutants tested overcame the restriction in rodent cells. Rather, when the secondary structure of the chimeric HIV-1 TAR construct was destroyed, the compensation in rodent cells was disappeared. Interestingly, the proper interaction between Sp1 and TATA box binding proteins, which is essential for Tat-dependent transcription, was dispensable in rodent cells. Conclusion: This result suggests that the human-specific Tat cofactor acts to allow Tat to interact effectively in a ribonucleoprotein complex that includes Tat, cellular factors, and TAR RNA, rather than be associated with the HIV-1 LTR upstream DNA binding factors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.912-915
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• 2004

Inductors material utilized in the downsizing passive devices and Rf components requires the physical and electrical properties at given area such as inductors thickness reduction, inductance and q-factor increase, low leakage current and thermal stability. In this study, Spiral inductors on the $SiO_2/Si$(100) substrate were fabricated by the magnetron sputtering method. Cu thin film with the thickness of $2{\mu}m$ was deposited on the substrate. Also we fabricated square inductors through the wet chemical etching technique. The inductors are completely specified by the turn width and the spacing between spirals. Both the width and spacing between spirals were varied from 10 to $60{\mu}m$ and from 20 to $70{\mu}m$, respectively. Inductance and Q factor dependent on the RF frequency were investigated to analyze performance of inductor arrays

• Structural Engineering and Mechanics
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• v.15 no.1
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• pp.21-38
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• 2003

The formulation of a new bridge-vehicle system using shell with eccentric beam elements has been introduced in a companion paper (Part I). The new system takes into account of the contribution of the twisting and pitching modes of vehicles to the bridge responses. It can also be used to study the dynamic transverse load distribution of a bridge. This paper presents a parametric study on the impact induced by one vehicle or multi-vehicle running across a bridge using the proposed model. Several parameters were considered as variables including the mass ratio, the speed parameter, the frequency ratio and the axle spacing parameter to investigate their effects on the impact factor. A total number of 189 cases were carried out in this parametric study. Within the realistic range of vehicle considered, the maximum impact factors could be 2.24, 1.78 and 1.49 for bridges with spans 10 m, 20 m and 30 m respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.6
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• pp.529-535
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• 2005

This study experimentally examines the air-side performance of spiral finned tube heat exchangers. The effects of fin spacing, fin height, and tube alignment were investigated. Reduction of fin spacing decreased the Colburn j factor. However, the effect of fin height on the Colburn j factor was negligible. An increase of tube row decreased the Nusselt number for both staggered and in-line tube alignments. However, the decrease of the Nusselt number for the in-line tube alignment was much more significant than that of the staggered tube alignment. The average Nusselt number of the staggered tube alignment was larger than that of the in-line tube alignment by $10\%$ when the Reynolds number ranged from 300 to 1700. An empirical correlation of the Nusselt number was developed by using geometric parameters of heat exchanger and correction factors. The correction factor considered the effects of tube alignment and number of tube rows on the heat transfer. The proposed correlation yielded a mean deviation of $4\%$ from the present data.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.225-229
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• 2009

The front metal contact is one of the most important element influences in efficiency in the silicon solar cell. First of all selective of the material and formation method is important in metal contacts. Commercial solar cells with screen-printed contacts formed by using Ag paste process is simple relatively and mass production is easy. But it suffer from a low fill factor and a high shading loss because of high contact resistance. Besides Ag paste too expensive. because of depends income. This paper applied for Ni/Cu metallization replace for paste of screen printing front metal contact. Low cost Ni and Cu metal contacts have been formed by using electroless plating and electroplating techniques to replace the screen-printed Ag contacts. Ni has been proposed as a suitable silicide for the salicidation process and is expected to replace conventional silicides. Copper is a promising material for the electrical contacts in solar cells in terms of conductivity and cost. In experiments Ni/Cu metal contact applied same grid formation of screen-printed solar cell. And it has variation of different grid spacing. It was verified that the wide spacing of grid finger could increase the series resistance also the narrow spacing of grid finger also implies a grid with a higher density of grid fingers. Through different grid spacing found alteration of efficiency.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.741-750
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• 2004

Air voids in hardened concrete have an important influence on concrete durability such as freeze-thaw resistance, surface scaling resistance, and water permeability, and they have been characterized by spacing factor Linear traverse and point count methods in ASTM standard have been used in estimating an air void system in hardened concrete. However, these methods require lots of time and efforts, further they are not repeatable. Image analysis method could be utilized In estimating an air void systems in hardened concrete with a developments of microscope, digital camera and computer program. The purpose of this study was to develope image analysis method and provide a guideline by comparing the results from ASTM method and image analysis method. The concerns were at air void content and diameter distribution, air voids system as well as spacing factors. The experimental variables included air content by air entrained agent (0, 0.01, $0.03\%$) and depth of specimen (top, middle, bottom). The result showed that it was possible to calculate spacing factor using image analysis technique, as well as air content, air diameter distribution, and air structure. This study also contributed in developing an reasonable and repeatable image analysis method.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.5-10
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• 1991

This study was performed to find out the effect about the spacing factor and durability factor to evaluate the durability of concrete in high-strength concrete with freezing and thawing as following each condition, 1) unit cement content : 500kg/$\textrm{m}^3$, 550kg/$\textrm{m}^3$ 2) water/cement ratio : 25%, 30%, 35% 3) air content : below 1.5%, 1.6~3.5%, 4~6%, over 7% From the results tested, a variation of air content was more effective to the durability of concrete than that of water/cement ratio and unit cement content.