• Fire Science and Engineering
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• v.17 no.2
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• pp.10-16
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• 2003

The main purpose of this study is to raise the point at issue and to propose reform direction about the current performance criteria of fire resistance through the examination of the fire resistance required for each use of compartment by using performance-based fire safety design method. To examine the performance criteria of fire resistance, this study compared the equivalent time of fire exposure which was calculated by using time-equivalent formulae with the required fire resistance time determined by existing prescriptive code, and surveyed factors such as the fire load energy density, ventilation factor, fire compartment materials and fire compartment geometry in order to calculate the equivalent time of fire exposure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.1
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• pp.35-41
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• 1983

The purpose of this study is to provide a method of estimating the frequency of flood magnitudes in ungauged station. Six major station are selected for this study in the Geum River system. For each gauging station in the basin, T-year flood is determined by Weibull plotting position. The derivation of the flood frequency formulae is performed on the basis of estimating method of floods with using the hydrological and geomorphical factors developed by U.S. Geological Survey. It is found that the model in this study can be applied to flood flow estimation of ungauged station in the Geum River basin because the mean characteristics of flood flow is used for the basin.

• Steel and Composite Structures
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• v.42 no.4
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• pp.489-499
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• 2022

This paper proposes a numerical optimization method to design the mesoscale architecture of textile composite for simultaneously enhancing mechanical and thermal properties, which compete with each other making it difficult to design intuitively. The base cell of the periodic warp and fill yarn system is served as the design space, and optimal fibre yarn geometries are found by solving the optimization problem through the proposed method. With the help of homogenization method, analytical formulae for the effective material properties as functions of the geometry parameters of plain-woven textile composites were derived, and they are used to form the inverse homogenization method to establish the design problem. These modules are then put together to form a multiobjective optimization problem, which is formulated in such a way that the optimal design depends on the weight factors predetermined by the user based on the stiffness and thermal terms in the objective function. Numerical examples illustrate that the developed method can achieve reasonable designs in terms of fibre yarn paths and geometries.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.3
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• pp.19-27
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• 1991

In this paper, fracture tests were carried out in order to investigate the fracture behavior of SFRC (Steel Fiber Reinforced Concrete) structures. Thirty six SFRC beams were used in this test. The relationships between loadings, strains, and mid-span deflections of the beams were observed under the three point loading system. From the test results, the effects of percentage of fiber by volume, the fiber aspect ratio and the initial crack depth ratio on the concrete fracture behavior were studied, and the stress intensity factors, the thoughness index, and the flexural strength of SFRC beams were calculated. According to the regression technique, some empirical formulae for predicting the flexural strength of SFRC beams were also suggested.

• Progress in Superconductivity and Cryogenics
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• v.13 no.1
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• pp.27-30
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• 2011

A sub-cooled liquid nitrogen cooling system is known as a most promising method to develop large scale superconducting apparatuses such as superconducting fault current limiters and superconducting cables [1]. Gaseous helium (GHe), gaseous nitrogen ($GN_2$) and sulfur hexafluoride ($SF_6$) are commonly used for designing an high voltage applied superconducting device as an injection gaseous medium [2, 3]. In this paper, the analysis on the dielectric characteristics of GHe, $GN_2$ and $SF_6$ are conducted by designing and manufacturing sphere-to-plane electrode systems. The AC withstand voltage experiments on the various gaseous insulation media are carried out and the results are analyzed by using finite element method (FEM) considering field utilization factors (${\xi}$). It is found that the electric field intensity at sparkover ($E_{MAX}$) of insulation media exponentially decreases according to ${\xi}$ increases. Also, the empirical expressions of the functional relations between $E_{MAX}$ and ${\xi}$ of insulation media are deduced by dielectric experiments and computational analyses. It is expected that the electrical insulation design of applied superconducting devices could be performed by using the deduced empirical formulae without dielectric experiments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.33-42
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• 1981

Current standard code for R.C. design consists of two conventional design parts, so called WSD and USD, which are based on ACI 318-63 and 318-71 code provisions. The safety factors of our WSD and USD design criteria which are taken primarily from ACI 318-63 code are considered to be not appropriate compared to out country's design and construction practices. Furthermore, even the ACI safety factors are not determined from probabilistic study but merely from experiences and practices. This study investigates the safety level of R.C. flexural members designed by the current WSD safety provisions based on Second Moment Reliability theory, and proposes a rational but efficient way of determining the nominal safety factors and the associated flexural allowable stresses of steel bars and concretes in order to provide a consistent level of target reliability. Cornell's Mean First-Order Second Moment Method formulae by a log normal transformation of resistance and load output variables are adopted as the reliability analysis method for this study. The compressive allowable stress formulae are derived by a unique approach in which the balanced steel ratios of the resulting design are chosen to be the corresponding under-reinforced sections designed by strength design method with an optimum reinforcing ratio. The target reliability index for the safety provisions are considered to be ${\beta}=4$ that is well suited for our level of construction and design practices. From a series of numerical applications to investigate the safety and reliability of R.C. flexural members designed by current WSD code, it has been found that the design based on WSD provision results in uneconomical design because of unusual and inconsistent reliability. A rational set of reliability based safety factors and allowable stress of steel bars and concrete for flexural members is proposed by providing the appropriate target reliability ${\beta}=4$.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.23 no.6
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• pp.567-576
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• 2020

Purpose: Not enough attention has been paid to defecation habits in Japan. This study aimed to emphasize the importance of defecation habits on health and function in Japanese pupils. Methods: Using multiple regression analysis, 2,722 questionnaires obtained from pupils in grades 5 to 12 were analyzed to determine lifestyle habits associated with defecation frequency. Results: Significant regression formulae for defecation scores were obtained for all school types: elementary school (ES) (adjusted R²=0.08, p<0.001), junior high school (JHS) (0.09, p<0.001), and senior high school (SHS) (0.15, p<0.001). The following factors were associated with poorer defecation scores, according to school type: female gender (all 3 school types), breakfast skipping (elementary and JHSs), lower physical activity (JHSs and SHSs), and longer school-day screen time (elementary and SHSs). In addition, poorer self-reported academic performance scores in ES, less standardized body mass index (BMI) in JHS, and shorter non-school- day screen time scores in SHS, were associated with poorer defecation scores. Conclusion: Poor defecation frequency showed significant associations with various lifestyle habits, such as breakfast skipping, physical activity, and screen time, among pupils. Academic performance and standardized BMI were also associated with defecation frequency. More attention should be paid to defecation frequency to sustain health and function in pupils.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.12
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• pp.55-67
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• 2010

The electrical properties of a back drilled via-hole (BDH) without the open-stub and the plated through via-hole (PTH) with the open-stub, which is called the conventional structure, in a high-count multi~layered (HCML) printed circuit board (PCB) were investigated for a high-speed digital system, and a selected inner layer to transmit a high-speed signal was farthest away from the side to mount the component. Within 10 GHz of the broadband frequency, a design of experiment (DOE) methodology was carried out with three cause factors of each via-hole structure, which were the distance between the via-holes, the dimensions of drilling pad and the anti-pad in the ground plane, and then the relation between cause and result factors which were the maximum return loss, the half-power frequency, and the minimum insertion loss was analyzed. Subsequently, the empirical formulae resulting in a macro model were extracted and compared with the experiment results. Even, out of the cause range, the calculated results obtained from the macro model can be also matched with the measured results within 5 % of the error.

• Geotechnical Engineering
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• v.9 no.4
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• pp.37-44
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• 1993

Model pile tests in calibration chamber are performed in order to study the two factors that the pile bearing capacity is significantly influenced by. Those factors are the critical depth concept and the scale effect caused by pile diameters. Firstly, the predicted values of end bearing capacity from the various static formulae were compared with the measured ones from model pile tests. Secondly, the critical depth concept and the scale effect were investigated by using two different soil conditions in a series of calibration chamber tests : the one is uniform sand : and the other is weathered granites overlayered by sand. Main results obtained from the model tests can be summarized as follows : (1) The end bearing capacity was increased with pile penetration depth up to penetration ratio of 7 to 8 when the cell pressure is high, and the critical depth was observed in the current chamber tests with uniform sand layer , (2) The predicted end bearing capacities were mostly lager than the measured, and it was found that the differences between the predicted and the measured values became smaller as the pile penetration ratio was increased : (3) The end bearing capacity of the small diameter pile in weathered granites layer was mostly less than that of the larger pile, while in uniform sand layer it was vice.

• Journal of the Korean Institute of Oriental Medical Informatics
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• v.21 no.2
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• pp.11-23
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• 2015

Objectives : Through a comparative study between Sasang constitutional medicine and Syndrome identification and treatment medicine about the theory of diagnosis, the theory of herbal medicine, the theory of prescription, the theory of acupuncture and constitutional medicine to put forward a complementary perfect solution which has good clinical utility. Methods : We compared and sorted out the textbook of Korean Sasang constitutional medicine which named Sasang medicine, and also the textbook of Chinese TCM which was including Basic theory of TCM, Diagnostics of TCM, Science of Chinese materia medica, Pharmacology of traditional Chinese medical formulae, Science of acupuncture and moxibustion, Constitution of TCM, and also related papers. Results : (1) Through a comparative study between Sasang constitutional medicine and Syndrome identification and treatment medicine about diagnosis, herbal medicine, prescription and acupuncture, Sasang constitutional medicine is a medical system which gives priority to balance of organs, when Syndrome identification and treatment medicine is a medical system that gives priority to improve symptom. (2) The prescriptions of Sasang constitutional medicine are used for the treatment of basic pathogenesis in the chronic stage of the disease, which can recover vital qi, when Syndrome identification and treatment medicine are used for the treatment of stage pathogenesis in the acute stage of the disease, which can get rid of pathogenic factors. (3) There are two kind of complementary perfect solution between Sasang constitutional medicine and Syndrome identification and treatment medicine. One perfect complementary medicine is that Sasang constitutional medicine plays a major role when Syndrome identification and treatment medicine plays a supporting role. The other one is that Syndrome identification and treatment medicine plays a major role when Sasang constitutional medicine plays a supporting role. It determined by the usual symptoms and the symptoms now, vital qi and pathogenic factors, symptom and the root cause, acute stage and chronic stage, and the state of pathogenesis. Conclusion : A new perfect complementary medicine can be created which is based on the setting that Sasang constitutional medicine primarily treat the usual symptoms, vital qi, the root cause, chronic stage and basic pathogenesis when Syndrome identification and treatment medicine primarily treat the symptoms now, pathogenic factors, symptom, acute stage and stage pathogenesis.