• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.167-175
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• 2019

To effectively deal with the fire in tunnel which is mostly the vehicle fire, it's more important to suppress the fire at early stage. In urban tunnel, however, accessibility to the scene of fire by the fire fighter is very limited due to severe traffic congestion which causes the difficulty with firefighting activity in timely manner and such a problem would be further worsened in underground road (double-deck tunnel) which has been increasingly extended and deepened. In preparation for the disaster in Korea, the range of life safety facilities for installation is defined based on category of the extension and fire protection referring to risk hazard index which is determined depending on tunnel length and conditions, and particularly to directly deal with the tunnel fire, fire extinguisher, indoor hydrant and sprinkler are designated as the mandatory facilities depending on category. But such fire extinguishing installations are found inappropriate functionally and technically and thus the measure to improve the system needs to be taken. Particularly in a double-deck tunnel which accommodates the traffic in both directions within a single tunnel of which section is divided by intermediate slab, the facility or the system which functions more rapidly and effectively is more than important. This study, thus, is intended to supplement the problems with existing tunnel life safety system (fire extinguishing) and develop the remote-controlled automatic fire extinguishing system which is optimized for a double-deck tunnel. Consequently, the system considering low floor height and extended length as well as indoor hydrant for a wide range of use have been developed together with the performance verification and the process for commercialization before applying to the tunnel is underway now.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.2
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• pp.1-7
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• 2001

To protect combustion chamber from high temperature combustion gas, regenerative cooling is used for most liquid rocket engine. Although regenerative cooling is the most effective way to protect the chamber from high heat flux, realization of this system requires detail analysis, manufacturing technique and high cost. To demonstrate the possibility of applying regenerative cooling to a real rocket engine, the hot fire test has been carried out for the sub-scale liquid rocket with the water cooling system. The main purpose of the test is to identify the problem area of design, safety and cost effective manufacturing technique. The coolant passage was 3 mm in width and wall thickness was 1 mm with stainless steel. Maximum combustion time and pressure were 60 seconds and 400 psi, respectively. The flow rate of coolant was reduced gradually from 2 kg/s to 0.12 kg/s throughout firing test, combustion chamber was visually examined and no dwfect was observed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.249-254
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• 2017

The paper presents a new short-term dynamic displacement estimation method based on an acceleration and a geophone sensor. The proposed method combines acceleration and velocity measurements through a real time data fusion algorithm based on Kalman filter. The proposed method can estimate the displacement of a structure without displacement sensors, which is typically difficult to be applied to earthquake or fire sites due to their requirement of a fixed rigid support. The proposed method double-integrates the acceleration measurement recursively, and corrects an accumulated integration error based on the velocity measurement, The performance of the proposed method was verified by a lab-scale test, in which displacement estimated by the proposed method are compared to a reference displacement measured by laser doppler vibrometer (LDV).

• The Journal of the Society of Stroke on Korean Medicine
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• v.10 no.1
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• pp.47-53
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• 2009

Objectives : This study was aim to investigate the relationship between NIHSS and distribution of pattern identification in stroke patients. Methods : 1471 participants from the patients hospitalized for stroke within 4 weeks from April 2007 to August 2009 were included. They were grouped according to the NIHSS score; group 1 for the participants whose NIHSS were less than six, group 2 for seven to fifteen, and group 3 for over than sixteen. And the patients were re-divided into two groups according to their post-onset interval. The difference of distribution of five pattern identification for each group were investigated. And five pattern identification were re-analyzed according to the deficiency-excess pattern identification. K-W test was used for statistical synthesis, and the result was regarded as significant one, if its p-value was below 0.05. Results : Dampness-phelegm pattern was the most frequent out of five patterns in total participants as well as all the subgroups. In group 3 with more serious neurological deficit, larger proportion of patients in early acute stage was diagnosed as excess pattern including Fire-Heat pattern. On the other side the proportion of Deficiency of Qi and Yin was larger in late convalescent stage of group 3 than in other groups. But nothing was statistically significant. Conclusions : Further study including patients with more variant classification with follow-up evaluation is needed to reflect the real characteristics of stroke population.