• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.2
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• pp.41-44
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• 1974

A calculation of the two dimensional added mass moment of inertia for the Kim's chine form sections is made with a special consideration of a location of a axis of rotation. The results are compared with those of Lewis form section equivalent to the above chine form sections calculated by Kumai.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.316-323
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• 2000

In railway train operations, a braking distance between two trains must be controlled on their speeds to avoid rear end collisions. The distance is decided by some parameters such that propulsion and braking performance of trains, gradient and etc. When determining this block distance, it is important to consider the two aspects that safety insurance at train running and increase of train running frequency. In this paper, we showed a methodologies of equiblock by consideration gradients and calculated optimal block speeds on the basis of the equivalent block distance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.259-269
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• 2013

In this paper, we propose an SIW(Substrate Integrated Waveguide) multi-section E-plane transformer using air-holes for an SIW system with variable thicknesses. Air-holes are inserted into a SIW E-plane quarter wavelength transformer for matching an E-plane impedance discontinuity. A PSIW(Punched Substrate Integrated Waveguide) consisted of air-holes has an SIW characteristic impedance tunability because of reducing a equivalent shunt capacitance of the SIW. And, a PSIW multi-section E-plane transformer is implemented for improving a matching bandwidth by using the Chebyshev polynomial. The measurement results of PSIW double-section E-plane transformer show that the insertion loss($S_{21}$) is $1.57{\pm}0.11$ dB and input return loss($S_{11}$) is more than 15 dB from 11.45 GHz to 13.6 GHz.

• The Korean Journal of Pain
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• v.9 no.1
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• pp.166-171
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• 1996

The purpose of this study is to compare the postoperative analgesic effect of morphine and meperidine, employing intravenous patient controlled analgesia after cesarean section. Among fifty nine parturients undergoing cesarean section with general anesthesia, 32 were administered morphine designated as 'morphine group', and 27 parturient administered meperidine as 'meperidine' group, during 48 hours after commencement of PCA. Doses administered, based on potency for this setting, were equivalent to 1 mg morphine or 10 mg meperidine. Loading dose was administered when parturient first complained of pain after cesarean section. This was followed with bolus dose, 1 mg for morphine group and 10 mg for meperidine group, with a lockout interval of 8 minutes between doses wherever parturient requested additional analgesia. Visual analog scale(VAS) pain scores during rest were significantly lower at only 1 and 2 hour for the meperidine group, than morphine group. Loading dose and cumulative dose at 1, 2 and 3 hours were significantly lower for meperidine group than the morphine group. There were no significant difference in total dose and hourly dose for 48 hours and cumulative dose at 6, 12, 24, and 48 hours between both groups. More than 90% of the parturients from both groups were satisfied with the analgesic effects of pain relief. Morphine group experienced side effects such as: pruritus, sedation and dizziness. Meperidine group had sedation, dizziness, nausea and local irritation. Neither group required any specific treatment for any of the above side effects. We conclude that meperidine had greater analgesic effect at early stage of post-operative period.

• Wind and Structures
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• v.28 no.4
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• pp.255-270
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• 2019

Aerodynamic configurations of bridge decks have significant effects on the aerostatic torsional divergence and flutter forsuper long-span bridges, which are onset for selection of suitable bridge decksfor those bridges. Based on a cable-stayed bridge with double main spans of 1500 m, considering typical twin-box, stiffening truss and closed-box section, which are the most commonly used form of bridge decks and assumed that the rigidity of those section is completely equivalent, are utilized to investigate the effects of aerodynamic configurations of bridge decks on aerodynamic instability performance comprised of the aerostatic torsional divergence and flutter, by means of wind tunnel tests and numerical calculations, including three-dimensional (3D) multimode flutter analysis and nonlinear aerostatic analysis. Regarding the aerostatic torsional divergence, the results obtained in this study show twin-box section is the best, closed-box section the second-best, and the stiffening truss section the worst. Regarding the flutter, the flutter stability of the twin-box section is far better than that of the stiffening truss and closed-box section. Furthermore, wind-resistance design depends on the torsional divergence for the twin-box and stiffening truss section. However, there are obvious competitive relationships between the aerostatic torsional divergence and flutter for the closed-box section. Flutter occur before aerostatic instability at initial attack angle of $+3^{\circ}$ and $0^{\circ}$, while the aerostatic torsional divergence occur before flutter at initial attack angle of $-3^{\circ}$. The twin-box section is the best in terms of both aerostatic and flutter stability among those bridge decks. Then mechanisms of aerostatic torsional divergence are revealed by tracking the cable forces synchronous with deformation of the bridge decksin the instability process. It was also found that the onset wind velocities of these bridge decks are very similar at attack angle of $-3^{\circ}$. This indicatesthat a stable triangular structure made up of the cable planes, the tower, and the bridge deck greatly improves the aerostatic stability of the structure, while the aerodynamic effects associated with the aerodynamic configurations of the bridge decks have little effects on the aerostatic stability at initial attack angle of $-3^{\circ}$. In addition, instability patterns of the bridge depend on both the initial attack angles and aerodynamic configurations of the bridge decks. This study is helpful in determining bridge decksfor super long-span bridges in future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1095-1103
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• 2014

WBAN has received great attention recently due to its versatile applicability. In this paper, antennas suitable for WBAN communication depending on the locations of mobile devices and the manufacturing of a human equivalent phantom are introduced. The effect of the body on the communication performance is largely dependent on the locations of devices. Specifically, the radiation and return loss characteristics of the antenna are greatly influenced by the characteristics of a medium existing in the near-field of an antenna. Thus, the proper WBAN antenna design is important in establishing a successful communication link between the transceivers. To consider the effect of the body on the antenna performance, the human equivalent phantom is also important factor in the WBAN antenna design and measurement. In introduction, categorization of the WBAN communication channel is introduced and antenna characteristics required for each communication channel are described. In the main subject section, several WBAN antenna design examples along with the implementation of the human equivalent phantom are discussed. In conclusion, the factors, which have to be considered in the design process, and future research are mentioned.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.781-790
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• 2011

This paper contains the experimental results on strengthening effect of RC beams strengthened with NSM CFRP reinforcement and various strengthening details. A total of 14 beams have been tested to analyze strengthening effects of NSMR with various reinforcement details. Variables were cross-sectional shape of CFRP reinforcements, strengthening areas, grooves the number and location etc. Test results revealed that failure modes of NSMR showed two types. One was bond failure at interface between concrete and filler and the other was CFRP rupture. Also, failure mode of specimens with two grooves occurred premature bond failure because of superposition of failure surfaces at concrete around grooves. failure mode of MI specimens considered the equivalent section have changed bond failure to CFRP rupture and CFRP efficiency has improved 83% to 100%.

• Journal of the Korean GEO-environmental Society
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• v.11 no.11
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• pp.5-18
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• 2010

In this paper, a 3-dimensional stiffened plate model for soil-metal box structures is proposed. 3-dimensional stiffened plate model is enable to model corrugated steel plates of soil metal box culverts considering section modulus and section properties of longitudinal and horizontal direction from a corrugated steel plate. Loading conditions which causes maximum displacement and maximum moment according to the step construction stages(a back filling to the top of the plate, a back filling to the maximum depth of cover, and loading of live loads) was applied and the behaviors of the soil metal box culverts was analyzed. Analysis results of 3-dimensional stiffened model were compared with those of 2-dimensional model, 3-dimensional equivalent plate model and 3-dimensional corrugated plate model. As results, the behaviors of 2-dimensional model and 3 dimensional equivalent model are different from 3-dimensional corrugated plate model but the result of 3-dimensional stiffened model has good agreement with that of 3-dimensional corrugated plate model.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.359-365
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• 2019

This paper is a basic study for the performance evaluation, durability improvement and optimal design of tractor transmission. The engine torque of the 78 kW agricultural tractor during rotary tillage was measured using CAN communication. It was calculated with equivalent torque and then analyzed. In order to develop a reliable tractor, it is important to convert measured torque in various agricultural operations into equivalent torque and analyze it. The equivalent torque was calculated using Palmgren-Miner's rule, which is a representative cumulative damage law. The equivalent torque of rotary tillage period and steering period are 229.2 and 136.7 Nm, respectively. The maximum and average torque during rotary tillage period are 336.0 and 234.4 Nm, respectively. The maximum and average torque of the steering period are 288.0 and 134.6 Nm, respectively. The engine torque in rotary tillage period is higher than in the steering period because of cultivation of soil through PTO. The maximum and rated torque of engine are 387.0 and 323.0 Nm, respectively, which are 183% and 136% higher than the equivalent torque during rotary tillage and of steering section. Because transmission of agricultural tractor in Korea companies is generally designed by the rated torque of engine, there is a difference from measured torque during agricultural operations. Therefore, it is necessary to consider it for optimal design.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3921-3930
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• 1975

This research was carried out to investigate several mechanical characteristics of pre-stressed steel beams. The configuration of specimens used for this study were as follows; a cover plate having permissible fiber stress of 4,000 kg/$\textrm{cm}^2$ was welded at bottom having the allowable bending stress 2500 kg/$\textrm{cm}^2$ steel beam, the section ratios of pre-stressed steel beam and cover plate were 0.5 and 0.6. Adopted pre-stresses were 0%, 50%, and 100% of an allowable fiber stress of a steel beam. The results obtained from the study may be summarized as follows; 1. The elastic range of a beam was increased by the application of pre-stress to the beam, which leads to a lighter section. 2. The permissible moment capacity of a pre-stressed steel beam was greated than that of a steel beam without pre-stressing. 3. The equivalent allowable stress induced by adopting the different section ratio of pre-stressed beam to cover plate were figured out 4. The optimum value of section ratio of beam and cover plate was 0.3 to 0.4 in case of a 1.5m span composite beam, a combination of an allowable stress 2,500kg/$\textrm{cm}^2$ steel beam and a permissible fiber stress 4,000 kg/$\textrm{cm}^2$ steel cover plate, was used. 5. The magnitude of the pre-stress was desirable to be same as the allowable stress of a steel beam. 6. It was concluded that if the construction techniques in the field are developed and improved, the practicing of pre-stress to the steel structure has a promising future.