• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.351-357
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• 2019

This research was performed to propose domestic standard for design and management of flexible hose by analyzing chlorine leak caused by breakage of the hose in Ulsan, 2018. The leak had multiple causes but this paper focuses on analyzing the cause of breakage of flexible hose, the direct cause. According to the analysis, flexible hose that the company of the accident used for chlorine transfer was inappropriate in several aspects including material and wall thickness. And even pressure test had been conducted below operating pressure. Upon investigation on five companies that handle chlorine in Ulsan, four companies were using inappropriate flexible hose for chlorine transfer. Since there is no domestic standard for the design of flexible hose for chlorine transfer at present, it is hard to examine its design adequacy. Design standard of flexible hose used in chlorine transfer that is applicable domestically is proposed based on this research. It will contribute to the reduction in risk of breakage of the hose if the proposed standard could be applied in design and examination of flexible hose.

• Journal of the Korea Safety Management & Science
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• v.23 no.4
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• pp.55-60
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• 2021

This study is to check waterproof by number of twists of fire hose and measure the first waterproof time to analyze the relationship between twists of fire hose and first waterproof time and waterproof by position of twists so as to suggest the efficient plan to prevent twists of fire hose. Ordinary fire hose did not make waterproof in case that position of twists was near the nozzle with twists 5 times or more, while anti-twist fire hose had no problem for waterproof only with delayed time. Like ordinary fire hose, anti-twist fire hose also showed the tendency to increase the waterproof time in proportion to the number of twists. In case that the position of twists was near waterproof port even with 10 times of twists in anti-twist fire hose, the first waterproof time was increase by 0.63 seconds on average without any problem for waterproof, which was somewhat faster than that in ordinary fire hose. With respect to the position of twists, waterproof of anti-twist fire hose was affected more as the number of twists was increased more near the nozzle rather than near the waterproof port, like ordinary fire hose. In summary, anti-twist fire hose equipped with anti-twist tool at the middle connection port and the nozzle showed a good waterproof performance with delayed waterproof time regardless of number of twists, as a solution for the twist problem of ordinary fire hose.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.559-570
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• 2007

In this paper, we define a Hose-NSIS-QoSM, which reserves and manages resources according to the hose based resource provisioning mechanisms for supporting the VPN QoS(Quality of Service) using the NSIS(Next Step in Signaling) signaling protocol. Specifically, we specify the NSIS message objects, the structures of QoS NSLP(NSIS Signaling Layer Protocol)/NTLP(NSIS Transport Layer Protocol)/RMF(Resource Management Function) state tables and the processing of the signaling messages in NSIS nodes. Also, we compare the Hose-NSIS-QoSM with the Hose-RSVP-TE-QoSM that supports the hose based VPN QoS in the MPLS networks using the extended RSVP-TE mechanism.

• Journal of the Korea Safety Management & Science
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• v.23 no.4
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• pp.49-53
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• 2021

The objective of this study was to understand which type of fire hose should be placed in indoor fireplug box upon analyzing the preparation time between rack-type fire hose and reel-type one. With respect to the type of hose, rack-type stacking method was used and hose preparation time was measured with 5 times of repeat test, separating men and women. Study results reveal that preparation time of reel-type fire hose took longer than that of rack-type one in both men and women. For both rack-type hose and reel-type hose, preparation time by two persons took shorter than that by one man. Also, preparation time by three persons took shorted than that by two women. Preparation time for both rack-type hose and reel-type one by men took shorter than that by women. In summary, it was confirmed that rack-type hose could be prepared within shorter time than reel-type one. Since the size of drum set in the reel-type fire hose is relatively small, it had some difficulty in preparation of fire hose timely.

• 연구논문집
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• s.34
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• pp.79-85
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• 2004

There are several types of life test method for hose assemblies. The two major tests used for hose assemblies are impulse test and burst test. And magnification adjustment of impulse pressure, heating of testing oil and repetitive motions of bending and straightening of testing hose are also performed for accelerating the life. According to the manufacture process of hose and swaging process of fitting, there is a difference in the life of hose assemblies from minimum 7 times to maximum 40 times during the life test in the same functioning condition. Like this, the life test of hose which has a wide scope of life distribution gives a problem that observation should take a long time to find out the existence of the bursting from the beginning of the test to the completion of bursting of hose assemblies. Therefore, this research proposes a process of concentrating on the defective section of hose assemblies and maximizing the life acceleration by giving 'Knockdown stress' to hose assemblies just until before the hose assemblies get out of order.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.54-60
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• 2010

The automotive air conditioning hose is used for connecting the components of air conditioner in a vehicle. The hose is usually manufactured by the swaging process to connect the rubber hose with the metal fitting at the end of the hose. The swaging process leads to various stress and strain configurations in the hose, which give a critical effect on the hose performance. In this paper, the deformation characteristics of an air-conditioning hose during the swaging process were analyzed using the nonlinear finite element method. Especially the rubber layers, which are contacted with the metal fittings, were divided with finer mesh density than the reinforcement braids to increase the solution accuracy. The material properties were obtained from experimental data, and the contact conditions were used in consideration of the real manufacturing process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.96-101
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• 2013

Automotive brake system is an essential element for the safety. The system is powered by the circulation of brake oil. A braker hose is used for the circulation of the oil in this system. Layout of the hose changes according to the steering and stress occur in the hose. A lot of the durability tests are performed in order to prevent serious problems such as hose bursting by the accumulation of the stress before setting an optimized hose layout on automobile. The test is conducted for the layout which is same such as set in automobile. In the test, brake hose layout shall exercise the same mode of thousands of times under the high temperature and periodic pressure condition and then the damage of the tested hose is inspected. This test, however, has a disadvantage of heavy consumption of time and money. In order to compensate for these drawbacks, the finite element method(FEM) study was performed to predict the changes in the layout of the brake hose. In this study, the FEM results and the test results were compared and the validity was verified. The radius of curvature of the FEM and test at the same positions were especially investigated for the validation. Also, this study will be used as the basis of research on the life prediction of brake hose.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.535-539
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• 2022

This study analyzed the efficient hose loading method for indoor fire hydrants, and the experimental results are as follows. An effective fire hose loading method is to be derived through an experiment comparing the fire hose loading method of an indoor fire hydrant and the speed of fire suppression. When the fire hose was loaded by folding, it took an average of 33 seconds to load the fire hose, and for the hangyeopsal, it took an average of 69 seconds to load the fire hose, showing a significant difference. First, in the folding hose deployment experiment, subjects A, C, D, and E showed similar values from 34 seconds to 37 seconds, respectively. The reason seems to be the result of the fact that the fire hose was not twisted when unfolding, and that it was possible to deploy the hose smoothly. Subject B showed the lowest deployment time at 25 seconds, which seems to be the result of B's experience in deploying the fire hose. Second, in the hose unfolding experiment, subjects A, B, C, and E had a similar time period of 44 to 76 seconds, respectively. However, the test subject D was significantly higher at 110 seconds. The reason is that the attempt to prevent hose kinking when deploying the fire hose and the unstable psychological state through tension are judged to increase the fire hose deployment time.

• Journal of the Korea Safety Management & Science
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• v.23 no.3
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• pp.115-122
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• 2021

In this study, the purpose of this study was to examine the effect of twisting in the preparation of waterproofing in the process of unfolded donut-type staking method fire hoses in indoor hydrant system. The central pull-out method caused more twisting than the rolling method, and there was no significant difference in the number of twists according to the pull-out method in the case of male and female students. It was found that the time it took to untwist and prepare waterproofing was much shorter for male students. The angle valve and hose are connected, and the time to untwist and prepare for waterproofing after withdrawing the fire hose with the hose and nozzle connected was shorter than the unconnected state. In the rolling method, when a hose connected with two 15 m fire hoses was used and the angle valve-hose was connected, but the hose-nozzle was not connected, the least kinking occurred. The time to untwist and prepare for waterproofing was also the shortest. As a result, in the withdrawal method of the donut-type loaded fire hose in the indoor hydrant system, it is a rolling method rather than a central withdrawal method. With the angle valve and hose connected, unfold the fire hose with the hose and nozzle connected, if a large number of people unwind the twisted hose, the time to prepare for waterproofing can be shortened.

• Steel and Composite Structures
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• v.25 no.4
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• pp.403-413
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• 2017

The fabric braided braking hose that delivers the driver's braking force to brake cylinder undergoes the large deformation cyclic motion according to the steering and bump/rebound motions of vehicle. The cyclic large deformation of braking hose may give rise to two critical problems: the interference with other adjacent vehicle parts and the micro cracking stemming from the fatigue damage accumulation. Hence, both the hose deformation and the fatigue damage become the critical issue in the design of braking hose. In this context, this paper introduces a multi-objective optimization method for minimizing the both quantities. The total length of hose and the helix angles of fabric braided composite layers are chosen for the design variables, and the maximum hose deformation and the critical fatigue life cycle are defined by the individual single objective functions. The trade-off between two single objective functions is made by introducing the weighting factors. The proposed optimization method is validated and the improvement of initial hose design is examined through the benchmark simulation. Furthermore, the dependence of optimum solutions on the weighting factors is also investigated.