• The Journal of the Acoustical Society of Korea
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• v.24 no.3E
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• pp.87-89
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• 2005

The acoustical sources of intake and exhaust systems in fluid machines are often characterized by the source impedance and strength using linear frequency-domain modeling. In the case of the sources which are nonlinear and time-variant, however, the source parameters were sometimes incorrectly obtained. In this paper, the source model and direct measurement technique are modified in order to evaluate the effect due to nonlinear and periodically time-varying source character as well as the linear property of the reflectivity of in-duct fluid machine source. With a priori known kinematical information of the source, the types of nonlinear time-variant terms can be presumed by a simple physical model, in which there is practically no restriction on the form of the model. The concept of source impedance can be extendable by introducing the linear frequency response function for each nonlinear or time-variant input. Extending the conventional method and adapting the reverse MISO technique, it is possible to develop a direct method that can deal with the nonlinear time-variant source parameters. The proposed direct method has a novel feature that there is no restriction on the probability or spectral natures of the excited sound pressure data. The present method is verified by the simulated measurements for simplified fluid machines. It is thought that the proposed method would be useful in predicting the insertion loss or the radiated sound level from intake or exhaust systems.

• Journal of the Korean Chemical Society
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• v.10 no.3
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• pp.119-128
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• 1966

The glass electrode was empirically calibrated in methanol-and 2-propanol-water mixed solvents, by means of which the pH-meter reading could be converted to stoichiometric hydrogen ion concentration. The thermodynamic dissociation constants of hydrogen cupferrate in methanol-and 2-propanol-water solution were potentiometrically determined with the changes in composition of organic solvents at 0.01 and 0.05 of the ionic strength and 25$^{\circ}C$. The empirical formula of the constants with mole fraction (n) of the organic solvent are as follow: methanol-water solution $pK_a$= 2.24n + 4.29 at ${\mu}$ = 0.01 n = 0.0476∼0.642 $pK_a$ = 2.35n + 4.38 at ${\mu}$ = 0.05 n= 0.0446~0.642 2-propanol-water solution $pK_a$= 5.50n + 4.48 at ${\mu}$ = 0.05 n = 0.0253~0.259 The relationships between $pK_a$ of acetic acid, propionic acid and HCup and dielectric constant of some mixed solvents were discussed. It would be considered that the factors effecting $pK_a$ value of weak acid in mixed-solvent are not only dielectric constants but acid-base character and solvation effect of the solvent, etc.

• Computers and Concrete
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• v.4 no.1
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• pp.1-18
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• 2007

Over the past decades, an enormous amount of effort has been expended in laboratory and field studies on concrete durability estimation. The results of this research are still either widely scattered in the journal literature or mentioned briefly in the standard textbooks. Moreover, the theoretical approaches of deterioration mechanisms with a predictive character are limited to some complicated mathematical models not widespread in practice. A significant step forward could be the development of appropriate software for computer-based estimation of concrete service life, including reliable mathematical models and adequate experimental data. In the present work, the basis for the development of a computer estimation of the concrete service life is presented. After the definition of concrete mix design and structure characteristics, as well as the consideration regarding the environmental conditions where the structure will be found, the concrete service life can be reliably predicted using fundamental mathematical models that simulate the deterioration mechanisms. The prediction is focused on the basic deterioration phenomena of reinforced concrete, such as carbonation and chloride penetration, that initiate the reinforcing bars corrosion. Aspects on concrete strength and the production cost are also considered. Field observations and data collection from existing structures are compared with predictions of service life using the above model. A first attempt to develop a database of service lives of different types of reinforced concrete structure exposed to varying environments is finally included.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.37-42
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• 2006

The voltage drop in electrical circuits causes a heat accumulation of wiring. This heat could change the specific character of an insulator and deteriorate the dielectric strength so that it could affect an electric leakage, an electric ant a power failure and a fire caused by the short circuit. Therefore optimal design for voltage drop in electrical wiring became an important factor to ensure the safety and economical efficiency of electrical facilities. So in this paper, I analyzed consequences that voltage drop affects in electrical wiring in multi-distributed system used for low electrical system such as road lights, Building, subway station which needs securities for the public society. And I proposed voltage drops computation program and optimal design to ensure the safety and economical efficiency.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.410-414
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• 2011

This study was carried out to evaluate the microstructures and mechanical properties of a friction stir welded Ni based alloy. Inconel 600 (single phase type) alloy was selected as an experimental material. For this material, friction stir welding (FSW) was performed at a constant tool rotation speed of 400 rpm and a welding speed of 150~200 mm/min by a FSW machine, and argon shielding gas was utilized to prevent surface oxidation of the weld material. At all conditions, sound friction stir welds without any weld defects were obtained. The electron back-scattered diffraction (EBSD) method was used to analyze the grain boundary character distributions (GBCDs) of the welds. As a result, dynamic recrystallization was observed at all conditions. In addition, grain refinement was achieved in the stir zone, gradually accelerating from 19 ${\mu}m$ in average grain size of the base material to 5.5 ${\mu}m$ (150 mm/min) and 4.1 ${\mu}m$ (200 mm/min) in the stir zone with increasing welding speed. Grain refinement also led to enhancement of the mechanical properties: the 200 mm/min friction stir welded zone showed 25% higher microhardness and 15% higher tensile strength relative to the base material.

• Korean Journal of Hospice Care
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• v.5 no.2
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• pp.54-63
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• 2005

The purpose of this study is to examine the requirement for child life support specialist and fetal education for children with cancer. This research presented was composed with three chapters : First chapter, I presented the purpose, scope and definitions of this research. Second chapter, I defined about hospice care service for children with cancer and kind of pediatric cancer. And general characteristics of children with cancer, a understanding character of death and dietary therapy. Lastly, I defined and investigated about spiritual care. Third chapter, I concluded with some of findings and final suggestions based on the results. According to the developmental stages children with cancer are disability of communication competence and more dependence on their parents, therefore parents' decision making were more difficulty. And parents with a child who suffers from a cancer needs a counseling in order to discover the meaning of life. Parents' psychological experience about the caring for their child suffering from pediatric cancer was equal to broken hearts due to shadow of the child's death from time to time. In other words a parents with a child who suffers from a cancer needs comprehensive services such as hospice, consultor as well as wide experienced pediatrician and nurse. Child life support specialist can help them recover and improve their o주 potential strength in behalf of overcoming their difficulties. And pastoral counseling can help them reduce the fear and anxiety about unknown world and death. The systematically developed a school-based counseling program would help children adjust to the difficulties after a perfect cure because of children adjusted to school well when they have good peer relationships.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.25-37
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• 1993

This paper describes the use of the J-integral, a one parameter of the non-linear fracture mechanics(NLFM), as a means to measure toughness of steel fiber reinforced concrete. This parameter can be conveniently evaluated from experimentally determined load-deflection curves from flexural tests when a maximum-load failure criterion is employed. And, for high strength concrete which was reinforced steel fiber, with two different fiber length in the form of notched beams, were tested under 3-point bending, and $J_{IC}$, as well as the linear elastic fracture mechanics(LEFM) parameters $K_{IC}$ and $G_{IC}$ were evaluated. The results suggest that $J_{IC}$ is a promising fracture criterion for all of these. while $K_{IC}$(or $G_{IC}$) almost certainly are not. Also it was found that a fiber addition of less than 0.5% did not improve the fracture toughness of the high strength concrete. However, at more than 1.0% in fiber contents, $J_{IC}$ showed significant increases. reflecting the changed character of the concrete; $K_{IC}$ and $G_{IC}$ did not.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.83-94
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• 2000

Applicability of PMT in domestic area, test procedure, and methods determining the shear strength parameters $(cu,\phi)$and deformation character (E) using PMT results were studied. At six test boreholes of three construction sites in Pusan, PMT using Elastometer-200 type was performed. The problems occurring during tests were investigated and the test results were analysed.In-situ total horizontal stress could be obtained by observation from pressuremeter curve and limit pressure, ｐ could be determined by $ｐ-log(\Deltav/v)$ method. Shear strength parameters$(cu,\phi)$ and deformation modulus(G, E) could be determined from the PMT results. But effective friction angle and undrained cohesion determined from PMT results were greater than those obtained from laboratory test.Using PMT results, marine soil in Pusan could be classified approximately. Net limite pressure values were in the range of 6.4~22.5 $kg/cm^2$, in clay, 2.2~30.$kg/cm^2$, in sand, 13.0~58.0$kg/cm^2$, in weathered soil and 47.0~190.0 $kg/cm^2$, in weathered rock. Also, Em/ｐ values were in the range of 2.4~7.0 in clay, 2.6~12.1 in sand, 6.8~17.1 in weathered soil and 7.2~29.6 in weathered rock.

• Journal of the Korean GEO-environmental Society
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• v.3 no.2
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• pp.35-47
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• 2002

Soil and rock were yielded during construction of subway in Taegu. Produced rock is a kind of a sedimentary rock with low strength and low durability of shrinkage. So it is difficult using for resources engineering. But in our country, it is very important to use material resources due to lack of natural resources. In this study, after cracking sedimentary rock like black shale and red shale, they are compared with granite which usually used road constriction field to investigate property of use for road construction. Consequently, the engineering character of origin rock is satisfactory, but the soundness test, black shale and red shale are less than KS 12.9%, 37.5% respectively. The result of concrete freezing-thawing test shows that the strength among three materials is not a wide difference but red shale has relatively low strength. The result of asphalt freezing-thawing test with 50 cycles indicates that the stability of red shale in lower than KS 484~561kg on base course, 336~375kg on surface course respectively. A further research should be needed for propriety to the material of shale.

• Journal of Korean Medicine Rehabilitation
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• v.26 no.2
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• pp.123-132
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• 2016

Objectives The aim of this study done as pilot study is to analyze the current state of patients who have low back pain through registry. Methods This study is done under approval of Gil Oriental Medical Hospital of Gachon University, Oriental Medical Hospital of Sangji University, Jecheon Oriental Medical Hospital of Se-Myung University IRB. Among subjects who signed the consent form by their own will, we decided whom to register as subjects of this study by the standard of selection and exception. We collected the sociological investigation, character of low pack pain, degree of symptom which they felt before and after the hospitalization from registered subjects. Results 1. The number of the subjects is 16. The average age is 41.0. 9 of them are female, 7 of them are male. Most of the subjects have history illness which has connection with low pack pain. 2. According to the patient's free description of the back pain, 6 of them suffered throbbing pain. And 8 of the patients have chronic pain, 6 of them have intermittent pain of back pain analysing the character of the low back pain. They answered the pain lasted for 47.6 minutes on average. 3. About the change on the average R.O.M. of L-spine, R.O.M. of Lateral bending, Extension, Flexion, Rotation has increased after leaving the hospital compared with before hospitalization. 4. The amount of discomfort or strength of pain, which was checked by VAS on the day of leaving the hospital, has decreased than they were before the hospitalization. And there was the improvement on the dysfunction score and EQ-5D. Conclusions Through this study, we specifically analyzed the symptoms of the low back pain by accumulating the analysis about the symptoms using several indicators and description which is freely spoken by patients about their symptoms. Further research is expected to complete multi-center registry by building registry and by using it, to get various epidemiologic informations about low back pain.