• Journal of the Society of Naval Architects of Korea
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• v.57 no.2
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• pp.70-79
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• 2020

The offshore installation units may be subjected to various accidental loads such as collision from supply vessels, impact from dropped objects, blast load from gas explosion and thermal load from fire. This paper deals with the design and strength evaluation method of the stiffened plate structures in response to a blast load caused by a gas explosion accident. It is a comprehensive review of various items used in actual project such as the size and type of the explosive loads, general design procedure/concept and analysis method. The structural analyses using simple analysis methods based on SDOF model and nonlinear finite element analysis are applied to the particular FPSO project. Also validation studies on the design guidance given by simple analysis method based on SDOF model have also considered several items such as backpressure effects, material behavior and duration time of the overpressure. A good correlation between the prediction made by simple analysis method based on SDOF model and nonlinear finite element analysis can be generally obtained up to the elastic limit.

• Animal cells and systems
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• v.2 no.4
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• pp.463-469
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• 1998

Hyla japonica males were observed to produce two distinctively different types of mating calls: advertisement call to attract conspecific females and encounter call to keep off potential competitor males. Whereas advertisement calls were organized in bouts of calls or notes, encounter calls were usually produced as separate calls. Encounter calls were much longer and had more pulses per call than advertisement calls. However dominant frequencies or pitches of the two calls did not differ significantly. Hyla Japonica males exhibited considerable plasticity in their calling behavior. They altered both qualitative and quantitative properties of their calls in response to other calling males. Sometimes, they even switched from producing advertisement calls to encounter calls. Advertisement calls produced by chorusing males were shorter in duration and thus move calls per bout than those produced by lone males. Males also produced much lower-pitched calls when calling together with other males. Considering that low pitch calls are often Highly correlated with body size, it is possible that H. japonica males may try to generate deceptive calls to indicate the size greater than the actual.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.300-307
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• 2002

Bridge foundation failure considering the effect of local scour around pier foundations under hi-directional seismic excitations is examined in probabilistic perspectives. The seismic responses of bridges with deep foundations are evaluated with a simplified mechanical model, which can consider the local scour effect around the deep foundation in addition to many other components. The probabilistic characteristics of local scour depths are estimated by using the Monte Carlo simulation. The probabilistic characteristics of basic random variables used in the Monte Carlo simulation are determined from the actual hydraulic data collected in middle size streams in Korea. The failure condition of deep foundation is assumed as bearing capacity failure of the ground below the foundation base. The probability of foundation failure of a simply supported bridge with various scour conditions and hi-directional seismic excitations are examined. It is found that the local scour and the recovery duration are critical factors in evaluating the probability of foundation failure. Moreover, the probability of foundation failure under hi-directional seismic excitations is much higher than under uni-directional seismic excitations. Therefore, it is reasonable to consider hi-directional seismic excitations in evaluating the seismic safety of bridge systems scoured by a flood.

• Korean Journal of Human Ecology
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• v.20 no.2
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• pp.353-364
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• 2011

The purpose of this study was to examine different child care curricula according to teacher's teaching method types. The subjects of the study were three hundred and fifty-six teachers, who were divided into four groups according to their teaching method: mixed method(type A), child oriented method(type B), teacher oriented method(type C), and beliefless method(type D). The data on the duration of free play and outdoor play time, activities frequently practiced in class, and outside one the playground were collected. The dimensions of child care programs were measured using Moore(1994)'s "The Early Childhood Dimensions of Education Rating Scale". The results of this study were as follows: first, teachers who used child oriented teaching methods gave more free play time than teachers using teacher oriented or mixed teaching methods. Second, teachers using teacher oriented methods showed the closeness and teachers using child oriented methods showed the openness in child care programs. Last, the activities teachers thought were the most important differed according to the teachers' methods even though in actual practice, there was no difference shown.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.19-25
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• 2007

This experimental study was carried out to obtain both low emissions and high thermal efficiency by rapid bulk combustion. Two kinds of experiments were conducted to obtain fundamental data on the operation of a RI engine by a radical ignition method. First, the basic experiments were conducted to confirm rapid bulk combustion by using a radical ignition method in a constant volume chamber (CVC). In this experiment, the combustion velocity was much higher than that of a conventional method. Next, to investigate the desirable condition of engine operation using radical ignition, an applied experiment was conducted in an actual engine based on the basic experiment results obtained from CVC condition. A sub-chamber-type diesel engine was reconstructed using a SPI type engine with controlled injection duration and spark timing, and finally, converted to a RI engine. In this study, the operation characteristics of the RI engine were examined according to the sub-chamber's specifications such as the sub-chamber volume and the diameter and number of passage holes. These experimental results showed that the RI engine operated successfully and was affected by the ratio of the passage hole area to the sub-chamber volume.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.311-318
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• 2001

The application of a pulsed power system is being extended to a environmental and industrial fields. The non-dissolution waste water pollutants from industrial plants can be processed by applying high voltage pulses with a fast rising time (a few nanoseconds) and short duration (nano to microseconds) in a pulsed corona discharge reactor. The nano-pulse generator with a magnetic switch has been developed. Its corona current in load can be adjusted by pulse width and repetition rate. we investigated the performance of the nano-pulse generator using the dummy load which is composed of resistor and capacitor equivalent to the actual reactor. This paper descibes the electrical characteristics of the nano-pulse generator that produces a 300 ns pulse at maximum repetition rate of 400 pps with a voltage of 40 kV across a $640{\Omega}$ load. In this paper we briefly discuss a configuration of system and test results.

• Transactions of Materials Processing
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• v.26 no.4
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• pp.210-215
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• 2017

In this paper, utilizing the theory of ductile fracture a chevron crack in a 4-stage open cold extrusion process is predicted by the finite element methods and then compared with previous experiments. The normalized Cockcroft-Latham damage model is employed and the material is identified using a tensile test based material identification technique that gives fracture information as well as flow stress at large strain. A large difference between the predicted cracks and actual experiments is observed, specifically narrower width and greater maximum height of the crack. This reveals the limitation of this approach based on the conventional theory of ductile fracture. Based on the observations and the related criticisms, a new approach for predicting the chevron crack is proposed, suggesting that either the critical damage should not be a fixed material constant, or that the conventional fracture theory should be considered with the effects of embrittlement due to accumulated plastic deformation while the duration of crack generation and plastic deformation should be reduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.879-885
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• 2006

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

• The Journal of Internal Korean Medicine
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• v.10 no.1
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• pp.39-52
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• 1989

The present investigation was undertaken to confirm of clinical effects of Sagnating. So, experimental studies were done, especially, to ascertain whether Sagantang had pharmacological effect of analgesia, antipyresis, diuresis and decreasing blood pressure and so on. The results of the studies were obtained as follows: 1. The analgesic effects of Sagantang were obtained in mice. 2. Sagantang prolonged the duration of hypnosis which is induced thiopental-Na in mice, but it was not effective in rotor rod method. 3. Antipyretic effect of Sagantang was known on the typhoid vaccine induced fever in rats. 4. Sagantang inhibited automatic movement on the isolated ileum of mice, and antiacetylcholine effect and antibarium chloride effect of Sangantang were known on that. 5. Sangantang decreased blood pressure due to vasodilatation in anesthetized mice. 6. The effect of diuresis were noted in mice. According to the above results, clinical effects of Sagantang on oriental medical references were similar to the actual experimental results.

• The Korean Journal of Health Service Management
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• v.10 no.4
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• pp.51-59
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• 2016

Objectives : The purpose of this study was to examine the health service utilization of elderly patients who visited an emergency medical center in the Gyeongbuk region and to provide basic information for the effective management of emergency medical centers. Methods : This study analyzed the characteristics of the hospital visits and the actual situation for the use of emergency medical care of 10,264 elderly patients that visited an emergency medical center in the Gyeongbuk region from January, 2014 to December, 2014. Frequency analysis and chi-square test were done in this study. Results : This study showed that there is a difference in the characteristics of health service utilization which included hospital visits, duration of hospital visits and mode of arrival to the emergency medical center according to age, gender and other characteristics. Conclusions : Providing efficient emergency services is necessary as well as establishing an emergency medical center management plan that takes into consideration the difference in health service utilization of elderly patients.