• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.91-99
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• 2024

Piping systems are crucial facilities used in various industries, particularly in areas related to daily life and safety. Piping systems are fixed to the main structures of buildings and facilities but do not support external loads and serve as non-structural elements performing specific functions. Piping systems are affected by relative displacements owing to phase differences arising from different behaviors between two support points under seismic loads; this can cause damage owing to the displacement-dominant cyclic behavior. Fittings and joints in piping systems are representative elements that are vulnerable to seismic loads. To evaluate the seismic performance and limit states of fittings and joints in piping systems, a high-stroke actuator is required to simulate relative displacements. However, this is challenging because only few facilities can conduct these experiments. Therefore, element-level experiments are required to evaluate the seismic performance and limit states of piping systems connected by fittings and joints. This study proposed a method to evaluate the seismic performance of an elbow specimen that includes fittings and joints that are vulnerable to seismic loads in vertical piping systems. The elbow specimen was created by connecting straight pipes to both ends of a 90° pipe elbow using flexible groove joints. The seismic performance of the elbow specimen was evaluated using a cyclic loading protocol based on deformation angles. To determine the margin of the evaluated seismic performance, the limit states were assessed by applying cyclic loading with a constant amplitude.

• Fire Science and Engineering
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• v.26 no.5
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• pp.1-7
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• 2012

We have studied on equivalent length tables which are used to calculate the friction loss of pipe fittings and valves of water-based fire systems in Korea. Three kinds of equivalent length tables are mainly used and unfortunately, the most extensively used table is not ascertained the reliable source. When the three tables are compared, each table has different equivalent length up to 2.4 times in same item. We should use unified equivalent length table which is scientifically reasonable in order to act up to globalization as performing lots of over-sea projects. Therefore, we propose the reasonable equivalent length tables.

• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.321-333
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• 1998

In order to derive the UV color - effective temperature relation, we calculated the effective temperature and ultraviolet color index for about 118 IUE standard stars. Using differential correction method, the effective temperature was obtained by the best fittings of IUE low-dispersion spectra to the Kurucz model (1993), and the UV color index was calculated from the magnitude differences of the UV wavelength between 2750 $\AA$ and 2950 $\AA$. The temperature determined by the Kurucz model fittings was consistent with that obtained by other investigators (Malagnini & Morossi 1990, Malagnini et al. 1986), except for the low temperature stars. The relations between UV color - effective temperature also was similar to that in Kurucz model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1098-1103
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• 2014

This study deals with the development of an electrofusion welding machine that is capable of joining plastic pipes using a recently developed electrofusion fitting. This fitting has built-in conductive plastics that are used to weld the joint together as a heating element. In order to explain the mechanism of the new machine, 1) the resistance characteristics of the heating element were explained, 2) the method of electric welding that uses the electrofusion fitting was described, and 3) the method of power supply based on controlling the firing angle was explained. A control system for an intelligent electrofusion welding machine was proposed. This system has the ability to recognize the diameter of an electrofusion fitting using a lookup-table based on the difference of resistance curves according to fitting types, and it is able to weld the fittings regardless of the ambient temperature. A new algorithm was developed to control the power of electric welding through the recognition of feature points from the resistance curve of the heating element. In order to evaluate the performance of the developed welding machine, tests involving the welding of 16 mm- and 20 mm-type fittings were carried out. Examining the welding results, we concluded that the proposed welding machine will offer high productivity and reliability in the field of electrofusion welding.

• Wind and Structures
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• v.8 no.2
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• pp.89-106
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• 2005

For estimating the vortex excited vibrations of overhead transmission lines, the Energy Balance Principle (EBP) is well established for spans damped near the ends. Although it involves radical simplifications, the method is known to give useful estimates of the maximum vibration levels. For very long spans, there often is the need for a large number of in-span fittings, such as in-span Stockbridge dampers, aircraft warning spheres etc. This adds complexity to the problem and makes the energy balance principle in its original form unsuitable. In this paper, a modified version of EBP is described taking into account in-span damping and in particular also aircraft warning spheres. In the first step the complex transcendental eigenvalue problem is solved for the conductor with in-span fittings. With the thus determined complex eigenvalues and eigenfunctions a modified energy balance principle is then used for scaling the amplitudes of vibrations at each resonance frequency. Bending strains are then estimated at the critical points of the conductor. The approach has been used by the authors for studying the influence of in-span Stockbridge dampers and aircraft warning spheres; and for optimizing their positions in the span. The modeling of the aircraft warning sphere is also described in some detail.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.677-684
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• 2006

An ejector is a fluid transfer device to be used for mixing of fluids, maintaining vacuum, and overcoming a poor suction condition. To date, most ejectors have been made from the casting process. which is time-consuming and high-cost process. Therefore, a new production method of ejectors is desired if any. In this experimental study, we proposed a new type ejector manufactured from the commercial fitting materials and the welding process, which is equipped with an orifice type nozzle. The proposed ejector has a good integrity compared with the conventional ejector because the fittings have manufactured by forging and they have more strength than the casting materials. Furthermore we adopted a multi-opening orifice type nozzle for improving a suction capacity and compared with a single-opening orifice type nozzle. From the experimental results. we confirmed that the multi-opening nozzle had a food suction capacity than the single-opening nozzle and the proposed new type ejector showed higher vacuum than the conventional type ejector in non-load condition. These improved characteristics suggests that a new type ejector by using the commercial fittings opens the feasibility to be adopted in various industry fields and that the increased suction capacity can be achieved by altering the nozzle design of a conventional ejector.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.185-192
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• 2011

This study deals with a basic proposal to prove the safety for the exhausted fittings of the hydrogen fuel cell vehicle. First, this study was approached to numerical analysis solving to close the exact boundary condition (Axial, Bending, Lateral) and the second, this study produced the Lateral movement equipment for the vibration. For the numerical analysis, This study was considered with the exact solution of Lateral movement and the resonance effect for durability sample according to fitting positions. The second, This study was made for special equipment for displacement/gas leak and the frequency because the domestic samples were comparing with foreign fitting and foreign fitting for the hydrogen fuel cell vehicle. The result of this study was satisfied with domestic fittings for the basic reference but it need more test because of other situation for hydrogen fuel cell vehicle.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.820-830
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• 2016

Pipe wall thinning by flow-accelerated corrosion and various types of erosion is a significant and costly damage phenomenon in secondary piping systems of nuclear power plants (NPPs). Most NPPs have management programs to ensure pipe integrity due to wall thinning that includes periodic measurements for pipe wall thicknesses using nondestructive evaluation techniques. Numerous measurements using ultrasonic tests (UTs; one of the nondestructive evaluation technologies) have been performed during scheduled outages in NPPs. Using the thickness measurement data, wall thinning rates of each component are determined conservatively according to several evaluation methods developed by the United States Electric Power Research Institute. However, little is known about the conservativeness or reliability of the evaluation methods because of a lack of understanding of the measurement error. In this study, quantitative models for UT thickness measurement deviations of nuclear pipes and fittings were developed as the first step for establishing an optimized thinning evaluation procedure considering measurement error. In order to understand the characteristics of UT thickness measurement errors of nuclear pipes and fittings, round robin test results, which were obtained by previous researchers under laboratory conditions, were analyzed. Then, based on a large dataset of actual plant data from four NPPs, a quantitative model for UT thickness measurement deviation is proposed for plant conditions.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.2
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• pp.250-271
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• 2022

Traditional wedding dresses have had a high market demand in China in recent years. Traditional wedding dresses from the Tang dynasty occupy an important position among traditional Chinese dresses, and they are also favored by young women. This study was conducted to develop the rushan and qun patterns of traditional wedding dress styles from the Tang dynasty for women in their twenties in China. For this purpose, the rushan and qun patterns of Tang and Song dynasty dresses and modern traditional dresses were collected and analyzed. Additionally, the developed patterns were validated for suitability through appearance evaluations of virtual and real fittings. The following proportions of the developed patterns were proposed: H/3.3 for rushan length, H/33 for collar width, H/1.08 for total sleeve length, H/6 for sleeve width, H/8.5 for sleeve hem width, and H/1.55 for qun length. In addition, the developed patterns received high scores in the appearance evaluations of the virtual and real fittings. Therefore, the developed rushan and qun patterns are expected to have high utility in the current traditional wedding dress industry.

• Proceedings of the KIEE Conference
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• 2005.05b
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• pp.71-74
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• 2005

At the neutral sections, There are neutral sections inserted in overhead contact line between the substations to divide different phase current sections of AC electrified lines. except convention line, a large stress occurs in the contact wire near the fittings under passing pantographs. So, in order to raise the train speed over 150km/h, a new type section has been adopted.