• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.212-220
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• 2011

These days, many cable-stayed bridges were constructed in accordance with the trend in Korea. At the moment, construction technology of cable-stayed bridges has been remarkably developed but design technology still relies upon foreign technology very much. The cable anchor system that is one of key technologies of cable-stayed bridge brings powerful cable tension to produce local stress concentration and to disturb stress seriously, so for safety must be designed by a local detailed analysis is required. But without a clear design standard or design theory relying on F.E.M, and engineers don't understand theoretical basic mechanism of cable anchor system. As a result, engineers can be lose their judgement. Accordingly, this study examined theoretical design flow of fixing pipe in guide pipe-anchor system and additional considerations, in accordance with design standards at home and abroad to keep them in order and to suggest supplementary design flow.

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.74-80
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• 2009

In this study, the static and modal analyses to find the characteristic of eigenvalues for a towed cable were with a free boundary condition at the bottom end carried out with numerical study. The resulting numerical code with finite element method was used to study sample problems for a cable with towing speeds. After tracing the equilibrium state with a towing speed through the static analysis, modal analysis on the basis of static results was performed. The static top tension for a critical towing speed is nearly 50 percent of what it was for a free hanging pipe. From static analyses, it is found that towing speed has a noticeable effect on top tension of a towed pipe. At a high towing speed, differences between the first and second periods become larger. Compared to the fundamental period for a free hanging pipe, that for a towed pipe with a critical towing speed is approximately 1.4 times larger. This result is very important point in that the lock in condition and tension of the towed cable system with top excitation can be predicted. The corrected close form solution to solve natural periods for a towed cable was presented in this study. The code is validated by comparison of the results of theoretical and numerical studies. Two results were in very good agreement. This study can contribute to predicting the lock-in condition and tension for a towed cable or pipe with top excitation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.4
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• pp.263-276
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• 1992

The transmission current in a power cable is determined under the condition of separate pipe cooling. To this end, the thermal analysis is conducted with the standard condition of separate pipe cooling system, which constitutes one of the underground power transmission system. The changes of transmission current in a power cable with respect to the variation of temperatures and flow rates of inlet cooling water as well as the cooling spans are also determined. As a consequnce, the corresponding transmission current is shown to vary within allowable limit, resulting in the linear variation of the current for most of the cable routes. The abrupt changes of current, however, for the given flow rate of inlet cooling water in some cooling span lead to the adverse effects on the smooth current transmission within the underground power transmission system. In practice, it is expected that the desinging of the separate pipe cooling system in conjunction with the evaluation of system capacity should take into account the effects of design condition on the inlet cooling flow rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2355-2362
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• 2014

Electric railway induces interference voltage on wayside communication cable which brings about communication errors, malfunction of devices, and safety problem. The magnitude of the induced voltage depends on the electromagnetic field coupling which is affected by metallic installations such as rail and track structures. This paper provides an experimental analysis of the screening effect of metallic pipe on the inductive voltage caused on communication cable. The measurements at a high-speed rail site show that the screening effect of metallic pipe is about 20% when the separation distance between the pipe and communication cable is 1~2 m. The screening effects is less than 1% and can be neglected when the separation distance is more than 4 m. These results are useful to evaluate the screening effects of the metallic installations such as water pipe, gas pipe, and reinforcing bar.

• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.58-60
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• 2007

This paper introduces the IN-FLEX system using aluminum clad flex cable, which is expected to alternate the conventional wiring method, such as, a steel pipe wiring method, and a synthetic resin pipe wiring method. The aluminum clad flex cable has a superior operation characteristics in heat dissipation property, in installation and maintenance facility, flammability, and appearance. Moreover, the IN-FLEX system adopted an easy connection mechanism which enable to reduce the time, hands and expense for the installation and maintenance of the system. Certification tests verifying the superior operation characteristics and reliability of the system using aluminum clad flex cable were carried with standard method in KOLAS certification institute.

• 전기의세계
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• v.20 no.4
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• pp.31-36
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• 1971

This is intending to introducdine the pipe type 161KV underground cable system in Capital City of Seoul which will be constructed in 1972 or 1973 by Korea Electric Co using the AID loan and Won currency. In order to make readers to have an easy understanding and a clear view of underground cable transmission line, the first part will be for the introduction of the description on future underground cable system by Mr. E.H.F inch appeared on 1969 Sept. Consulatant Engineer. the second part will introduce our 161KV underground cable system in Seoul and it's feasibility study, and the third part will mention calculation methods of electrical properties of pipe type cable and the results of calculation of our own system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.101-106
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• 2014

Although anti-freezing heating cable has been widely installed in most residential boiler pipe, there were excessive energy consumption and fire risk due to inadequate temperature control. In this paper, a new energy saving fire risk-free controller was developed by using microprocessing operation which include detection of not only boiler room temperature but also pipe surface one. Its actual effect has been verified to save more than a half of the energy consumption comparing to conventional controller through temperature and humidity chamber experiment.

• Smart Structures and Systems
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• v.26 no.5
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• pp.575-589
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• 2020

For vibration control of stay cables in cable-stayed bridges, viscous dampers are frequently used, and they are regularly installed between the cable and the bridge deck. In practice, neoprene rubber bushings (or of other types) are also widely installed inside the cable guide pipe, mainly for reducing the bending stresses of the cable near its anchorages. Therefore, it is important to understand the effect of the bushings on the performance of the external damper. Besides, for long cables, external dampers installed at a single position near a cable end can no longer provide enough damping due to the sag effect and the limited installation distance. It is thus of interest to improve cable damping by additionally installing dampers inside the guide pipe. This paper hence studies the combined effects of an external damper and an internal damper (which can also model the bushings) on a stay cable. The internal damper is assumed to be a High Damping Rubber (HDR) damper, and the external damper is considered to be a viscous damper with intrinsic stiffness, and the cable sag is also considered. Both the cases when the two dampers are installed close to one cable end and respectively close to the two cable ends are studied. Asymptotic design formulas are derived for both cases considering that the dampers are close to the cable ends. It is shown that when the two dampers are placed close to different cable ends, their combined damping effects are approximately the sum of their separate contributions, regardless of small cable sag and damper intrinsic stiffness. When the two dampers are installed close to the same end, maximum damping that can be achieved by the external damper is generally degraded, regardless of properties of the HDR damper. Field tests on an existing cable-stayed bridge have further validated the influence of the internal damper on the performance of the external damper. The results suggest that the HDR is optimally placed in the guide pipe of the cable-pylon anchorage when installing viscous dampers at one position is insufficient. When an HDR damper or the bushing has to be installed near the external damper, their combined damping effects need to be evaluated using the presented methods.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.116-119
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• 2004

The existing monitoring and control systems of utility-pipe conduit (power tunnel, cable tunnel etc) have established communication lines using optical fiber, leaky coaxial cable (LCX), and several kinds of control cable. Due to the properties of the used media, the cost of equipment is considerably high and the maintenance of the system is difficult. Also, the term of carrying out is long so that the extension of the system is in difficulty. Now it is desirable to adopt Power Line Communication (hereinafter, PLC) technology in the monitoring and control systems and use the existing low-voltage power-line for lamplight as communication line. This will lead the reduction of the construction cost and the easy maintenance of the system. In this paper, we research the characteristics of PLC in conduit, design and manufacture the field test system, and analyze the performance of the system by field test. Then, we introduce the reliable monitoring and control system of utility-pipe conduit using PLC.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.158-165
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• 2005

KOGAS(Korea Gas Corporation) has about a hundred of local stations to supply natural gas to the city gas companies and the power stations. As some severe flow fluctuation phenomena are observed in several governor stations, the investigation about the reasons and factors which are relating to flow fluctuation has been started. Some field surveys hav been carried out and experimental studies have been performed to find the fluctuation mechanism. As a result, it is found that the flow fluctuation is related with the length of straight pipe in front of the meter, the size of the header pipe and the variation of demand at the city gas company and the power station. Furthermore. it is also proved that both the length of the transmitter cable and the status of the coating of signal transmission cable do not affect flow fluctuation, but the measurement range of the differential pressure transmitter influences flow fluctuation. On the other hand, as the averaging the flow fluctuation is converged to less than 0.1 % in almost all of the cases, it is concluded that the quantity of flow fluctuation do not relates to metering accuracy directly.