• Geotechnical Engineering
• /
• v.2 no.3
• /
• pp.15-26
• /
• 1986

A great number of different pile-driving formulas are widely used to determine the load-carr-ying capacity during driving. However, engineers have been unable to agree on any particular pile.driving formula because the mechanisms of pile driving action which involves many complications such as hammer-pile-soil interaction could not be solved completely in any practical manner. This paper is presented for the purpose of giving field engineers a reliable analytical procedures for the prediction of pile.driving resistance without resort to electronic computers based on the theory of longitudinal wave transmission in conjunction with the wave equation and on the consideration of the effect of residual stresses induced by reversed friction in pile.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.03a
• /
• pp.201-208
• /
• 1999

Pile driving technique has been regarded as the most reliable way of constructing deep foundations. Engineers have long believed that the quality of the installed piles is a simple function of the set values which can easily be obtained from the field pile driving records. Consequently most of the local building codes are based on the dynamic formula. However it has been proven that the quality of the driven pile is influenced not only by the set values but also by various factors, such as hammer performance, helmet characteristics, time dependent geotechnical characteristics of the site, etc., from the results of various researches made during the last two decades. In this paper an appropriate quality control scheme has been proposed by taking various influencing factors into consideration.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1774-1781
• /
• 2007

In this study, Matsuda's formula, which has been used to evaluate the acting load on the concrete pillar in 2-Arch tunnels, is investigated and a load reduction factor $({\alpha})$, which has been estimated from numerical parametric studies, is proposed for a better design of 2-Arch tunnels in the future. Numerical parametric studies show that the concrete pillar is subjected to a stress concentration on the excavation side during the first tunnel driving and when tunnel excavation is completed, the induced stress on the pillar in a poor quality of ground condition is 1.5 to 1.8 times the stress developed during the first tunnel driving. In addition, the numerical studies indicate that the acting load on the pillar is in the range of $14{\sim}83%$ of the load estimated by Matsuda's formula. From these results, a load reduction factor $({\alpha})$ is determined and it would make 2-Arch tunnel design more economically.

• Proceedings of the IEEK Conference
• /
• 2003.07c
• /
• pp.2847-2850
• /
• 2003

A input voltage conversion dimming control formula and a PMW dimming control formula which have been used for dimming control of CCFL driving inverter in TFT-LCD backlight, are the existing facilities so far, however, in this thesis the circuit is designed by applying The rover inverter that are able to measure output brightness according to changing of duty ratio at PWM and voltage. consequently, it's able to be confirmed that we can have dimming control more detailed than before.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.5
• /
• pp.157-164
• /
• 2001

말뚝의 항타공식(또는 동적공식)은 간단하고 품질관리를 수행할 수 있는 실용적인 방법으로 이용되어 왔지만 신뢰도는 가정조건의 문제점으로 인해 매우 낮은 것으로 평가되고 있다. 실제적으로 동적공식은 항타시스템 및 항타과정 측면에서 보면 근본적으로 문제가 있는데, 그간의 많은 연구들은 이러한 사실을 고려하지 않은 상태에서 이루어 졌다. 본 연구에서는 동적공식의 문제점에 대해 평가해 보고 이를 바탕으로 새로운 동적공식을 제안하였다. 그리고 현장에서 항타분석기로 실측된 항타시 및 항타후 시험자료를 이용하여 새로운 동적공식의 신뢰도와 적용성을 평가하였으며 그 결과 새로운 동적공식의 실용성을 확인할 수 있었다.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03a
• /
• pp.51-63
• /
• 2000

Because of simplicity and easiness, dynamic pile driving formulae have long been used by most of the field engineers for pile quality control purposes. Yet their reliability have been repeatedly reported unsuitable and the results can lead to significant errors. According to the research results by the authors, the two most important sources of unreliability of dynamic pile driving formulae are uncertainty in the estimation of hammer efficiency and time dependent characteristics of pile bearing capacity. Based on this finding a new method is proposed. By using the actual value of hammer efficiency the pile bearing capacity at the time of driving could be reasonably estimated. By performing restrike test sometime after pile installation, time effect coefficient could be determined. The effectiveness of the proposed method was proven in the actual construction project.

• Journal of Power System Engineering
• /
• v.21 no.4
• /
• pp.57-61
• /
• 2017

The vehicle label fuel economy is used as an energy management indicator nationwide. It induces technology development of automobile manufacturers and plays a role of providing information when purchasing a consumer vehicle. However, consumers who purchase a new vehicle continued to complain that the label fuel economy is different from the mandatory fuel economy rate. The domestic fuel economy measurement method is the same as the North American measurement method. The results of the two test modes (urban (FTP-75 mode), highway (HWFET mode)) are calculated in five test modes reflecting various environmental conditions and driving patterns 5-cycle correction formula is used which is equivalent to the fuel efficiency value. In this study, to solve the consumers' curiosity about the fuel economy of new vehicle, we use domestic fuel economy measurement method to measure the new car condition within 150 km of driving distance and the cumulative driving distance condition of domestic label fuel economy test vehicle. A comparative evaluation of fuel economy was carried out for a durability vehicle of $6,500{\pm}1,000km$. A result, mean value of the fuel economy of the four gasoline vehicles increased by 2.7 % in the city center mode and by 2.5 % in the highway mode in the durable vehicle compared new vehicle. And in the case of the diesel vehicle it increased by 2.5 % and 3.9 % respectively. The harmful exhaust gas emitted from the vehicle also resulted in more emissions of both gasoline and diesel vehicles in new vehicles. It is considered that the increase of the frictional force of the vehicle driving system and the lubricating oil system would have an effect on the reduction of the fuel economy of the new vehicle, and it was found that the fuel economy and the exhaust gas were improved by proper cumulative distance (domesticate) to the new vehicle.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.1
• /
• pp.112-118
• /
• 2013

Formula race car is generally recognized as a vehicle which is optimally designed for on-road race track with the regulations of race host bodies. Especially, the uprights of suspension system decisively have effects on the performance of cornering and stability of race car's driving performance, which are very important factors in the design of race car. This paper is a study of optimal upright design of F1800 grade formula race car which are normally used in professional race circuit in Korea. To design optimally the front upright of F1800 formula race car, Taguchi's orthogonal array, which is known for more useful method than full factorial design experimental method in cost and time, is used with CAE method such as FEM analysis. And the result of this paper shows that Taguchi's orthogonal array employed for this optimal design is very useful for designing the front upright of race car by minimizing its weight as well as keeping its safety factor as enough as designer wants in the view of quality, cost and delivery at the early design step.

• International Journal of Highway Engineering
• /
• v.15 no.3
• /
• pp.103-115
• /
• 2013

PURPOSES: The purpose of this study is to develop a method for distribution between superelevation and side friction factor by increasing design speed. METHODS: First of all, a method for distribution between superelevation and side friction factor and a theory for the functional formula of side friction factor in compliance with horizontal radius applied in South Korea and the United States are considered. Especially, design speed of 140km/h and numerical value of design elements are applied to the theory for the functional formula of side friction factor in AASHTO's methods. Also, the anxiety EEG upon running speed is measured to reflect ergonomic characteristics through field experiments at seven curve sections of the West Coast Freeway, and this data is applied to graph for the functional formula of side friction factor. RESULTS : Matching side friction factor against the anxiety EEG, the results that a critical points of driver's anxiety EEG sharply increase locate under existing parabola are figured out. CONCLUSIONS : Therefore, we could get a new type of the functional formula that driver's driving comfortability is guaranteed if the existing the functional formula of side friction factor goes down under boundary of the critical points of the anxiety EEG.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.22 no.2
• /
• pp.40-45
• /
• 1986

In this paper, the I-resistance curve of low-carbon steel with 3 mm thickness was investigated for various crack ratios. The experiments were carried out for the center cracked tension (CCT) specimen with about 50 mm width on an instron machine. The plane stress fracture toughness obtained by the Simpson's formula was Ii. = 24.96 kgffmm. Simpson's formula which considers crack growth in obtaining J integral showed more conservative lin than Rice's and Sumpter's. For materials that may be approximated by the Ramberg and Osgood stress strain law, the relevant crack parameters like the J integral, load line displacement are approximately normalized. Crack driving forces in terms of the I integral are computed for low-carbon steel CCT specimen using the above estimation scheme. Comparison of the prediction with actual experimental measurements by Simpson's formula showed good agreement for several different sized specimen.