• Journal of the Korean Society of Safety
• /
• v.25 no.6
• /
• pp.115-122
• /
• 2010

The importance of the life cycle cost (LCC) analysis for bridges has been recognized over the last decade. However, it is difficult to predict LCC precisely since the costs occurring throughout the service life of the bridge depend on various parameters such as design, construction, maintenance, and environmental conditions. This paper presents a methodology for the optimal life cycle cost design of a bridge. Total LCC for the service life is calculated as the sum of initial cost, damage cost, maintenance cost, repair and rehabilitation cost, user cost, and disposal cost. The optimization method is applied to design of a bridge structure with minimal cost, in which the objective function is set to LCC and constraints are formulated on the basis of Korean Bridge Design Code. Initial cost is calculated based on standard costs of the Korea Construction Price Index and damage cost on damage probabilities to consider the uncertainty of load and resistance. Repair and rehabilitation cost is determined using load carrying capacity curves and user cost includes traffic operation costs and time delay costs. The optimal life cycle cost design of a bridge is performed and the effects of parameters are investigated.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.10 no.5
• /
• pp.16-20
• /
• 1973

The most important thing in locating disturbances in optimal rapid traffic singnal control is to collect information cocerning toraffit flow by means of a detection method. In order to set up an optimal traffic singnal period, the analysis of a delay time phenomena in the signal period must also be considered. In fact, each of the distributed traffic quantities on the road are not similar factors in view of speeds and distances of succeeding cars. The causing factors are analyzed by the method of control engineering analysis, and they are coincident with disturbance. Thus distubances cause errors. Distubances are fuctions of time, and are classified into three conditions: Natural road state and weather are the first. The second is structures and function of vehicles, and the third is inducedbydrivers. This thesis deals with the last two cases except the first one for maximum utilization of the existing road state and weather conditions. The first condition remains constant, and then there exist some relations between vehicles and drivers. In the long run, it can be shown that the scheme for minimizing whole errors in the optimal traffic signal time setting is definitely presented.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.2B
• /
• pp.44-52
• /
• 2005

This paper proposes a neural network prediction model to improve the valid packet transmission rate for the QoS(Quality of Service) of multimedia transmission. The Round Trip Time(RTT) and Packet Loss Rate(PLR) are predicted using a neural network and then the transmission rate is decided based on the predicted RTT and the PLR. The suggested method will improve the transmission rate since it uses the rate control factors corresponding to time of data is being transmitted, while the conventional one uses the transmission rate determined based on the past informations. An experimental set-up has been established using a Linux PC system, and the multimedia data are transmitted using UDP protocol in real time. The valid transmitted packets are about 5% higher than the one in the conventional TCP-Friendly congestion control method when the suggested algorithm was applied.

• Journal of Wetlands Research
• /
• v.23 no.2
• /
• pp.144-153
• /
• 2021

In recently, the green algae bloom is one of the most severe challenges. The seven days prior prediction is in operation to issues the water quality warning, but it also needs a longer time of prediction to take preemptive measures. The objective of the study is to establish a method to conduct a 3-month prior prediction of Chl-a concentration in the Daechong Lake and tested its applicability as a supplementary of current water quality warning. The historical record of water quality in the Daechong Lake and seasonal forecasting of ECMWF were obtained, and its time-series characteristics were analyzed. The Chl-a forecasting model was established using a correlation between Chl-a concentration and meteorological factor and NARX model, and its efficiency was compared.

• Journal of Yeungnam Medical Science
• /
• v.24 no.1
• /
• pp.41-54
• /
• 2007

Background : The causes of chest pain vary but the leading cause of chest pain is ischemic heart disease. Mortality from ischemic chest pain has increased more than two fold over the last ten years. The purpose of this study was to determine the data necessary for rapid treatment of patients with signs and symptoms of ischemic chest pain in the emergency department (ED). Materials and Methods : We interviewed 170 patients who had ischemic chest pain in the emergency department of Yeungnam University Hospital over 6 months with a protocol developed for the evaluation. The protocol used included gender, age, arriving time, prior hospital visits, methods of transportation to the hospital, past medical history, final diagnosis, and outcome information from follow up. Results : Among 170 patients, there were 118 men (69.4%) and the mean age was 63 years. The patients diagnosed with acute myocardial infarction (AMI) were 106 (62.4%) and with angina pectoris (AP) were 64 (37.6%). The patients who had visited another hospital were 68.8%, twice the number that came directly to this hospital (p<0.05). The ratio of patients who visited another hospital were higher for the AMI (75.5%) than the AP (59.4%) patients (p<0.05). The median time spent deciding whether to go to hospital was 521 minutes and for transportation was 40 minutes. With regard to patients that visited another hospital first, the median time spent at the other hospital was 40 minutes. The total median time spent before arriving at our hospital was 600 minutes (p>0.05). The patients who had a total time delay of over 6 hours was similar 54.8% in the AMI group and 57.9% in the AP group (p>0.05). As a result, only 12.2% of the patients with an AMI received thrombolytics, and 48.8% of them had a simultaneous percutaneous coronary intervention (PCI). In the emergency department 8.5% of the patients with an AMI died. Conclusion : Timing is an extremely important factor for the treatment of ischemic heart disease. Most patients arrive at the hospital after a long time lapse from the onset of chest pain. In addition, most patients present to a different hospital before they arrive at the final hospital for treatment. Therefore, important time is lost and opportunities for treatment with thrombolytics and/or PCI are diminished leading to poor outcomes for many patients in the ED. The emergency room treatment must improve for the identification and treatment of ischemic heart disease so that patients can present earlier and treatment can be started as soon as they present to an emergency room.

• Journal of Life Science
• /
• v.34 no.7
• /
• pp.509-519
• /
• 2024

A previous study showed that krill oil improved recognition and memory through anti-oxidative effects in an amyloid β model, but the authors noted that further investigations are necessary of alterations to neurotransmitters' states and of serum lipid profile improvements related to serum lipid peroxidation. Accordingly, in this study, ICR mice were pre-treated intraperitoneally with scopolamine prior to induced neurotransmission impairment, and the effects of krill oil provision on their capabilities of cognition were tested by performing a passive avoidance test (PAT), water maze test (WMT), and novel object recognition test. Then, parameters including the acetylcholine (ACh) concentration, acetylcholinesterase activity (AChE), lipid peroxidation, serum lipid levels, and nerve cell proliferation were investigated. The results showed that krill oil improved the mice's abilities in recognition and memory as the times taken to complete the PAT and WMT were reduced compared to the mice in a comparison scopolamine-treated group. Krill oil produced an increased concentration of Ach, and this was accompanied by a decrease in AChE. As shown in a scopolamine-treated SH-SY5Y cell line, krill oil reduced the activity of AChE. Moreover, the suppression of lipid peroxidation-reflected in the finding that malondialdehyde was decreased with krill oil provision-is speculated to affect the recorded serum triglyceride and cholesterol decreases and LDL cholesterol increase. The intake of krill oil was also found to produce an improvement in brain-derived neurotrophic factor expression by stimulating the activation of cyclic AMP response element binding protein in the brain tissue. Overall, the current results imply that the provision of krill oil raises the cognition and memory by elevating neurotransmitters and by improving the serum lipid profile and nerve cell proliferation, which occur as lipid peroxidation is suppressed in the brain tissue.

• The korean journal of orthodontics
• /
• v.27 no.6 s.65
• /
• pp.955-961
• /
• 1997

Nicotine is one of the major components of cigarette smoking which causes various systemic and local diseases to human body. Mitogenic effects of nicotine to systemic disease are interesting factors in the results of cellular Proliferation especially to vascular and pulmonary tissue or cells. The study of local effects concerns with destruction of tissue and delayed healing rate after various surgical treatment. Platelet-Derived Growth factor(PDGF) and Insulin-like growth factor(IGF) are blown as major mitogens to human PDL cells. The purpose of this study was to investgate the mitogenic effects of nicotine to human PDL cells. We studied the expression of PDGF-$\alpha$ receptor, PDGF-$\beta$receptor, and IGF-l receptor mRNA from the nicotine treated human PDL cells by northern analysis. The experimental groups were divided into different serum($1\%,\;10\%$) and nicotine (100ng/m1,1000ng/m1) concentrations and each group was studied by time course. The results of this study showed upregulation of PDGF-${\alpha},\;{\beta}$ receptor and IGF-l receptor mRNA at 100ng/ml nicotine concentration and $10\%$ serum group to the time course. These results suggest that physiologically attainable nicotine concentrations may stimulate the mitogenic gene synthesis to human PDL cells in vitro.

• Fire Science and Engineering
• /
• v.25 no.6
• /
• pp.89-97
• /
• 2011

This study is for evaluating the fire resistance performance (1~2 h) of the RC Structure void slab using the Lightweight Hollow Sphere, which can reduce the unnecessary dynamic part of removing the central concrete. For this experiment, we set up depth of concrete cover, live load, and span length as the factors. The result comes out with all the slabs under those conditions can ensure the goal fire resistance performance (120 min). And among these factors, the resisting capability changes more sensitively with the live load rather than the thickness of cover. And the shorter span length could assure the better the fire resistance performance. The result observing the character in high temperature of the Lightweight Hollow Sphere which does not used as existing RC structure slab, a delay section in temperature change is occurred due to the Glass Transition in $100^{\circ}C$. And heat transfer by conduction does not occur at lightweight hollow sphere because the polystyrene in EPS (Expanded Polystyrene) melts point in $185^{\circ}C$. Therefore temperature at lightweight hollow sphere is lower than the concrete and rebar.

• Resources Recycling
• /
• v.29 no.3
• /
• pp.11-23
• /
• 2020

This study aims to investigate breakage and liberation characteristics of iron ore from Shinyemi mine, Jeongseon by ball mill. Parameters of breakage functions for three grade samples of iron ore were obtained using single-sized-feed breakage test and back-calculation based on nonlinear programming. The results showed that with the increase in the grade of iron ore, the breakage rate factor decrease whereas the particle size sensitivity decreases. This results from retardation of microcrack-propagation by magnetite grain in the ore. Breakage distribution analysis showed that the breakage mechanism appear to be impact fracture dominant with the increase of grade owing to the stress distribution effect by magnetite grain. Degree of liberation (DOL) increased with the increase in grade and decrease in particle size, respectively. Using the breakage function and size-DOL relationship, a model that can predict time-dependent-DOL is established. When scale-up factors from operating condition are available, the model is expected to be capable of predicting size and DOL with time in actual mining process.

• Clinical and Experimental Pediatrics
• /
• v.48 no.7
• /
• pp.711-715
• /
• 2005

Purpose : With the recent improved survival of extremely low birth weight infants(ELBWI), enteral feeding has become a major issue. This study investigates the effects of early enteral feeding in ELBWI on their morbidity, duration of hospitalization, and mortality. Methods : ELBWI admitted to the neonatal intensive care unit at Samsung Medical Center from November 1994 to April 2004 who survived more than 14 days were enrolled. ELBWI were divided into two groups : an early feeding group(EF), in which enteral feeding was started within 3 days after birth; and a late feeding group(LF), in which enteral feeding was started beyond 3 days after birth. 80 ELBWI came under EF, and 131 ELBWI under LF. Results : Birth weight and gestational age did not differ between the two groups. In EF, the time to achieve full enteral feeding and the duration of parenteral nutrition were significantly shorter than in LF. The incidence of bronchopulmonary dysplasia was significantly lower in EF, but the incidences of sepsis, necrotizing enterocolitis, and cholestasis were not different between the two groups. There was no difference in the survival rate between the two groups, but the duration of hospitalization was significantly shorter in EF. Conclusion : Early enteral feeding in ELBWI did not increase the incidence of necrotizing enterocolitis and sepsis, but rather decreased the incidence of bronchopulmonary dysplasia and shortened the duration of hospitalization.