• Nuclear Engineering and Technology
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• 제47권6호
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• pp.766-775
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• 2015

The integrity assessment of reactor vessel internals should be conducted in the design process to secure the safety of nuclear power plants. Various loads such as self-weight, seismic load, flow-induced load, and preload are applied to the internals. Therefore, the American Society of Mechanical Engineers (ASME) Code, Section III, defines the stress limit for reactor vessel internals. The present study focused on structural response analyses of the upper guide structure upper flange. The distributions of the stress intensity in the flange body were analyzed under various design load cases during normal operation. The allowable stress intensities along the expected sections of stress concentration were derived from the results of the finite element analysis for evaluating the structural integrity of the flange design. Furthermore, seismic analyses of the upper flange were performed to identify dynamic behavior with respect to the seismic and impact input. The mode superposition and full transient methods were used to perform time-history analyses, and the displacement at the lower end of the flange was obtained. The effect of the damping ratio on the response of the flange was also evaluated, and the acceleration was obtained. The results of elastic and seismic analyses in this study will be used as basic information to judge whether a flange design meets the acceptance criteria.

• Journal of the Korean Wood Science and Technology
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• 제51권3호
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• pp.197-206
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• 2023

A truss is a structure in which the members are connected and arranged such that they are primarily subjected to axial loading. A truss has the advantage that it can be used for a longer span because the structure distributes the applied force to its members well, and the load is transmitted only in the axial direction of the members. Trusses manufactured using timber have more advantages than those made of other materials. In this study, the properties of parallel chord trusses composed of timber chord and steel-web members were evaluated. We constructed truss specimens with various lengths by using upper and lower chords of 2 × 4 inch spruce-pine-fir lumber and steel-web members manufactured by S and P companies. The specimens were tested in accordance with KS F 2150. The test results showed that the load at the deflection limit and the deflection limit itself increased from L/180 to L/360 regardless of the length of the specimens. For specimens of the same length, the load at the deflection limit increased as the height of the parallel timber chord truss specimens increased from 200 to 300 mm. Successive installations of the steel-web members (SST) showed almost 2 times the load at each deflection limit compared to that of SAT specimens (alternate installation of the steel-web members). When comparing the three load-deflection limits in terms of the manufacturer of the steel-web members, the load at each deflection limit for SST specimens was higher than that for PST specimens.

• Structural Engineering and Mechanics
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• 제89권3호
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• pp.253-263
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• 2024

Slope stability is generally paid more attention to in slope protection works, especially for slope containing weak layers. Two indexes of safety factor and failure model are selected to perform slope stability. Moreover, the finite element limit analysis method comprehensively combines the advantage of the limit analysis method and the finite element method obtaining the upper and lower bounds of the safety factor and the failure mode under the slope stability limit state. In this study, taking a waste dump containing a weak layer as an engineering background, the finite element limit analysis method is adopted to explore the potential failure mode. Meanwhile, the sensitivity analysis of slope stability is performed on geometrical and geotechnical parameters of the waste dump. The results show that the failure mode of the waste dump slope is two wedges if the weak layer is located on the ground surface (Model A), while the slope can be observed as three wedges failure if the weak layer is below the ground surface (Model B). In addition, both failure modes are highly sensitive to the friction angle of the weak layer and the shear strength of waste disposal, and moderately sensitive to the heap height, the dip angle and cohesion of the weak layer, while the toe cutting has limited effect on the slope stability. Moreover, the sensitivity to the excavation of the ground depends on the location of the weak layer and failure mode.

• 보건행정학회지
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• 제22권3호
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• pp.451-465
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• 2012

In order to strengthen assurance of National Health Insurance, co-payment should be reduced. This can happen with collaborative efforts of patients, medical institutes, and government altogether at the same time. This research applied Dutton(1986)'s medical service research model with high R-square, and analyzed 2008 Korea Health Panel Data (Beta Version 1), that was examined by Korea Institute for Health and Social Affairs and National Health Insurance, in order to figure out influential variables on co-payment. In result of Multiple Linear Regression Analysis, R-square was 46.7%, the older the age, the patients who had surgery, the longer days of hospital treatment are, the higher gross income of a household is, the more hospitalized in upper grade general hospitals, and the more upper grade rooms and selecting a doctor are used. The results have statistical significance. When conducting research applying medical service research model, there is a need to apply Dutton(1986)'s medical service research model with high R-square. In order to strengthen assurance of National Health Insurance, first conditions should be that patients are hospitalized in upper grade general hospital, and at the same time, are patients who had surgery with long stay of hospitalization. In addition, if proven that patients used upper grade rooms and selecting a doctor due to lack of regular treatment and rooms, for certain number of days of such hospitalization, it is suggested to be provided with health care insurance in upper grade rooms and selecting a doctor in calculating co-payment limit.

• 한국인터넷방송통신학회논문지
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• 제19권3호
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• pp.115-120
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• 2019

뇌졸중 후 편마비(Hemiplegic) 환자들의 상지기능 저하는 손을 많이 쓰는 일상생활 수행에 있어서 신체적 동작뿐만 아니라 심리적인 불편함이 매우 크다. 본 논문에서는 편마비 환자들의 상지기능 개선을 위하여 자체 제작한 상지 재활 보조장치를 이용하였다. 이 장치는 팔이 움직일 수 있는 관절가동범위(Range Of Motion)와 손의 악력 크기를 사용하여 훈련 콘텐츠를 수행할 수 있다. 이 장치를 이용한 훈련 콘텐츠는 환자의 흥미와 능동적인 참여를 유도하기 위해 VR(Virtual Reality)로 구현되었으며, 환자 혼자서 훈련하는 심리적 부담을 덜어주기 위해 멀티플레이 환경으로 구성하여 환자의 재활훈련에 간병인이 함께 참여할 수 있도록 하였다. 본 연구에서 제작된 장치와 훈련 콘텐츠를 사용하여 손의 악력 크기와 팔의 관절가동범위의 변화를 정량적으로 측정하고 시각적으로 보여줌으로써 환자나 간병인이 쉽게 상지기능 개선정도를 확인할 수 있는 장점이 있다.

• 비파괴검사학회지
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• 제12권1호
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• pp.9-15
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• 1992

Ultrasonic spectroscopy is likely to become a very powerful NDE method for detection of microfects and thickness measurement of thin film below the limit of ultrasonic distance resolution in the opaque materials, provides a useful information that cannot be obtained by a conventional ultrasonic measuring system. In this paper, we considered a thin film below the limit of ultrasonic distance resolution sandwitched between two substances as acoustical analysis model, demonstrated the usefulness of ultrasonic spectroscopic analysis technique using information of ultrasonic frequency for measurements of thin film thickness, regardless of interference phenomenon and phase reversion of ultrasonic waveform. By using frequency intervals(${\triangle}f$) of periodic minima from the ratio of reference power spectrum of reflective waveform obtained a sample to power spectrum of multiple reflective waves obtained interference phenomenon caused by ultrasonic waves reflected at the upper and lower surfaces of a thin layer, can measured even dimensions of interest are smaller than the ultrasonic wave length with simplicity and accuracy.

• 한국전산응용수학회:학술대회논문집
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• 한국전산응용수학회 2003년도 KSCAM 학술발표회 프로그램 및 초록집
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• pp.7-7
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• 2003

We studied closed set-valued Choquet integrals in two papers(1997, 2000) and convergence theorems under some sufficient conditions in two papers(2003), for examples : (i) convergence theorems for monotone convergent sequences of Choquet integrably bounded closed set-valued functions, (ii) covergence theorems for the upper limit and the lower limit of a sequence of Choquet integrably bounded closed set-valued functions. In this presentation, we consider fuzzy number-valued functions and define Choquet integrals of fuzzy number-valued functions. But these concepts of fuzzy number-valued Choquet inetgrals are all based on the corresponding results of interval-valued Choquet integrals. We also discuss their properties which are positively homogeneous and monotonicity of fuzzy number-valued Choquet integrals. Furthermore, we will prove convergence theorems for fuzzy number-valued Choquet integrals. They will be used in the following applications : (1) Subjectively probability and expectation utility without additivity associated with fuzzy events as in Choquet integrable fuzzy number-valued functions, (2) Capacity measure which are presented by comonotonically additive fuzzy number-valued functionals, and (3) Ambiguity measure related with fuzzy number-valued fuzzy inference.

• 대한기계학회논문집
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• 제6권2호
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• pp.101-106
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• 1982

This study was undertaken to determine tensile properties and low-cycle fatigue behavior of 0.6%C high carbon steel used of structural purposes at temperatures up to 500.deg.C. In the low-cycle fatigue test the upper limit was decided by elongation(i.e. the total strain range), while the lower limit was defined by the load (i.e. zero load). The following results were obtained. Both, the ultimate tensile strength and low-cycle fatigue resistance attain the maximum values near 250.deg.C. Above this temperature the values decrease rapidly as the temperature increases. The low-cycle fatigue resistance decreases whenever there is an increase of the total strain range. Because the hardness of cycle fatigued specimen correlates cyclic hardening and cyclic softening, therefore the hardness of cycle fatigued specimen is smaller than that of the nonfatigued specimen at room temperature and 500.deg.C but much larger than the hardness of the nonfatigued specimen near 250.deg.C.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.579-584
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• 2002

In press forming of sheet metals, the material sheet is usually subjected to very large plastic strain under in-plane stressing. Moreover, the sheet also very often is subjected to out-of-plane compressive force between tools such as the upper and lower dies, the blank holder and the die, and so forth. In this paper, it is clearly demonstrated theoretically that out-of-plane stress may notably raise the forming limit strain and thus it cm be effectively utilized to avoid earlier fracture of the sheet in press forming.

• 소음진동
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• 제11권3호
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• pp.443-448
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• 2001

The subjective unwantedness felt from the noise sources in living environment has been evaluated by investigating the limit of perceptual loudness of the noise. The noise limits were selected by the subjects. And the noises were analyzed to find out whether there is any correlation with Zwicker parameters and ACF/IACF factors. It seemed that the loudness of noise from vacuum cleaner does not affect its perceives noisiness. Traffic noise also seems to be less influential in annoyance rating. It was resealed that floor impact noise generated by bang machine is the most irritating noise that can be heard in residential buildings.