• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.921-938
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• 2015

Realistic prediction of concrete creep is of crucial importance for durability and long-term serviceability of concrete structures. To date, research about the behaviour of self-compacting concrete (SCC) members, especially concerning the long-term performance, is rather limited. SCC is quite different from conventional concrete (CC) in mixture proportions and applied materials, particularly in the presence of aggregate which is limited. Hence, the realistic prediction of creep strains in SCC is an important requirement for the design process of this type of concrete structures. This study reviews the accuracy of the conventional concrete (CC) creep prediction models proposed by the international codes of practice, including: CEB-FIP (1990), ACI 209R (1997), Eurocode 2 (2001), JSCE (2002), AASHTO (2004), AASHTO (2007), AS 3600 (2009). Also, SCC creep prediction models proposed by Poppe and De Schutter (2005), Larson (2007) and Cordoba (2007) are reviewed. Further, new creep prediction model based on the comprehensive analysis on both of the available models i.e. the CC and the SCC is proposed. The predicted creep strains are compared with the actual measured creep strains in 55 mixtures of SCC and 16 mixtures of CC.

• Computers and Concrete
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• v.19 no.1
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• pp.69-78
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• 2017

This study aimed at exploring the effect of presoaking degree of lightweight aggregate (LWA) on the fresh and hardened properties of concrete. Two series (i.e., Series A and Series B) of concrete mixes that were made of LWA with different moisture states were prepared. The presoaking degree of LWA was divided into three types: oven dry state, 1 hour prewetted and 24 hours prewetted. For the Series A, the water content of the lightweight aggregate concrete (LWAC) mixes was adjusted in accordance with the moisture condition of the LWA. Whereas the amount of water added in the Series B mixes was deliberately not adjusted for the moisture condition of the LWA. Slump test, mechanical tests, interfacial transition zone microscopical tests and thermal conductivity test were carried out on the specimens of different concretes and compared with control normal-weight aggregate concretes. The test results showed that the effect of mixing water absorption by LWA with different moisture states was reflected in the fresh concrete as the loss of mixture workability, while in the hardened concrete as the increase of its strength. With the use of oven-dried LWA, the effect of reduction of water-cement ratio was more significant, and thus the microstructure of the ITZ was more compact.

• 모자간호학회지
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• v.3 no.2
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• pp.95-101
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• 1993

The purpose of this study is to define the effect of radiation hours on the physiologic jaundice infants. Since there in no full explanation of the way of phototherapy. Data was collected from February, 1993 through August, 1993 at E University Hospital. The subjects consisting of 179 normal newborn who is to receive phototherapy due to bilirubinemia in the early postnatal period. Six groups compared the effectiveness of phototherapy based on hours of radiation ; 6hrs, 9hrs, 12hrs, 15hrs, 18hrs, 21hrs. The results were as follows 1) Effectiveness of phototherapy which means serum total bilirubin decrements were significantly different in groups (F=9.812 p=.000). And follow up study was showed the subset in less than 15hrs groups and more than 15hrs groups. 2) There was no significant difference on the effect of phototherapy between aged after birth. 3) An hours of radiation and the number of stools was not revealed the relationship. The results obtained from this study suggest that 15hrs radiation per day is effective in phototherapy. In the furture, more replication of this study will be contribute for neonatal nursing care.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.4
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• pp.471-474
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• 1994

Five experimental groups with five adult male rats in each, were exposed to 20, 35, 40 and $45^{\circ}C$ air temperature for 50-70 minutes, and to $50^{\circ}C$ for 30-50 minutes, respectively. Food and drinking water were not permitted during the exposure. Blood samples were obtained by heart puncture immediately after the thermal treatment. All the rats were hyperthermic (p<0.01) as compared to the controls ($20^{\circ}C$). Hyperthermia was associated with hypoglycemia which was significant (p<0.01) at 45 and $50^{\circ}C$ exposures. Plasma levels of GOT and GPT declined at 35 and $40^{\circ}C$ reaching the lowest (p<0.05) level at $45^{\circ}C$, while at $50^{\circ}C$ GOT level was elevated by 45% but GPT was normal as compared to the controls. Differences between groups were significant (p<0.01) for GOT and insignificant for GPT. Hematocrit value increased significantly (p<0.01) at 45 and $50^{\circ}C$, indicating hemoconcentration. It could be concluded that severe heat stress (45 and $50^{\circ}C$) resulted in critical hyperthermia, hypoglycemia, disturbed liver function, body dehydration, and hemoconcentration leading to death.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.519-526
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• 2006

For investigating the effect of fuel stratification on flame propagation, initial flame development and propagation were visualized under different axially stratified states in a port injection SI engine. Stratification was controlled by the combination of the port swirl ratio and injection timing. Experiments were performed in an optical single cylinder engine modified from a production engine and images were captured through the quartz window mounted in the piston by an intensified CCD camera. Firstly in this paper, the characteristics under no port-generated swirl condition, i.e. normal conventional case was studied. Under various stratified conditions, flame images were captured at the pre-set crank angles. These were averaged and processed to characterize the flames propagation. The flame stability was estimated by the weighted average of flame area and luminosity. The stability was also evaluated through the standard deviation of flame area and propagation distance, and mean absolute deviation of propagating direction. Results show that stratification state according to injection timing do not affect on the direction of flame propagation. The flame development and the initial flame stability are strongly dependent on the stratified conditions and the initial flame stability is closely related to the engine stability and lean misfire limit.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.314-318
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• 2006

The interest on the detonation in small tubes, which can be applied to the ignition devices of propulsion system, is increasing. However, the propagation dynamics of detonation waves in small tubes has not been investigated clearly yet. In the present experiments, propagations of detonation waves in stoichiometric propane-oxygen mixture through transparent tubes were recorded using a high speed camera and average velocities were measured as well. In terms of average velocity, there exists a transition regime where the waves show smooth transition from the normal Chapman-Jouguet(CJ) detonation to the low velocity detonation$(\sim0.5V_{CJ})$ along the decreasing initial pressure. In this transition regime, the detonation waves are highly unstable and show cyclic or intermittent longitudinal velocity fluctuation.

• Structural Engineering and Mechanics
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• v.34 no.3
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• pp.351-366
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• 2010

A novel system identification and structural health assessment procedure of steel framed structures with semi-rigid connections is presented in this paper. It is capable of detecting damages at the local element level under normal operating conditions; i.e., serviceability limit state. The procedure is a linear time-domain system identification technique in which the structure responses are required, whereas the dynamic excitation force is not required to identify the structural parameters. The procedure tracks changes in the stiffness properties of all the elements in a structure. It can identify damage-free and damaged structural elements very accurately when excited by different types of dynamic loadings. The method is elaborated with the help of several numerical examples. The results indicate that the proposed algorithm identified the structures correctly and detected the pre-imposed damages in the frames when excited by earthquake, impact, and harmonic loadings. The algorithm can potentially be used for structural health assessment and monitoring of existing structures with minimum disruption of operations. Since the procedure requires only a few time points of response information, it is expected to be economic and efficient.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2775-2780
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• 2012

In recent years there has been a substantial increase in the use of functional foods for disease control. Fruits and vegetables produce phytochemicals such as flavonoids and antioxidants which can lower oxidative stress and reduce the risk of chronic ailments like cancer. The aim of the present study was to investigate the antioxidant capacity and the possible protective effects of Amaranthus paniculatus leaves on the antioxidant defense system in Ehrlich's ascites carcinoma (EAC)-treated mice. Oral administration of the leaf extract at different doses caused a significant decrease in tumor volume, viable cell count and tumor weight and elevated the life span of EAC bearing mice. It also showed an improved antioxidant potential as evidenced by a significant increase in the cellular antioxidant defense system such as catalase, superoxide dismutase and reduced glutathione and also significantly reduced the levels of TBARS. The levels of RBC, hemoglobin and lymphocyte count were altered in EAC bearing mice and were reverted back to near normal levels after the treatment with the leaf extracts. Their adequate content of total phenolics and flavonoids, DPPH scavenging activity which further suggests that the extracts exert a significant protection against oxidative stress conditions.

• The Journal of the Korea Contents Association
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• v.8 no.1
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• pp.169-176
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• 2008

In this paper, we develop radio resource management queueing model in IEEE 802.IS networks considering both connection and packet level. In the upper level connection, we model connection admission control depending on availability of bandwidth and priority queue in each service class. In the lower level packet, we model dynamic bandwidth allocation considering threshold and availability of bandwidth in each service class simultaneously. Hierarchical model is built using an extended Petri Nets, SRN (Stochastic Reward Nets). Bandwidth utilization and normal throughput as performance index for all service classes of traffic are calculated and numerical results are obtained.

• Journal of the Korea Safety Management & Science
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• v.18 no.1
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• pp.83-88
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• 2016

Currently many geriatric hospitals have been built in Korea because increasing aging rapidly. However the increasing geriatric hospitals make the increasing safety accidents. Therefore this study is conducted by survey and face-to-face talk with the fire safety managers for analyzing safety problem of geriatric hospitals which number is twelve among 15 geriatric hospitals in the north of Chung-buk area. The result of this study is that geriatric hospitals are very old. Fire safety managers holding the fire safety license are a level 2 issued by the Korea Fire Safety Association(KFSA). And the fire safety inspection ability of them is normal (58%). Furthermore a fire safety budget ratio is 83% (A little) in the company yearly budget. And ratio having the fire inspection equipment in the building is 42% (A little) and 33% (Nothing). Satisfaction ratio of their duty is 66% and they also get stress from heavy duty and heavy responsibility. In conclusion, CEO needs to invest and interest the improvement of job performance, satisfaction ratio and fire safety facility. Also government needs the improvement of system to support and supervise the fire safety of geriatric hospitals consistently.