• 한국수학교육학회지시리즈B:순수및응용수학
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• 제21권4호
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• pp.271-279
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• 2014

Let $T_l$ be a transformation on the interval [-1, 1] defined by Chebyshev polynomial of degree $l(l{\geq}2)$, i.e., $T_l(cos{\theta})=cos(l{\theta})$. In this paper, we consider $T_l$ as a measure preserving transformation on [-1, 1] with an invariant measure $\frac{1}{\sqrt[\pi]{1-x^2}}dx$. We show that If f(x) is a nonconstant step function with finite k-discontinuity points with k < l-1, then it satisfies the Central Limit Theorem. We also give an explicit method how to check whether it satisfies the Central Limit Theorem or not in the cases of general step functions with finite discontinuity points.

• 대한수학회지
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• 제35권3호
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• pp.583-611
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• 1998

We consider a general class of real-valued Levy processes {X(t), $t\geq0$}, and obtain suitable large deviation results for the empiricals L(t, A) defined by $t^{-1}{\int^t}_01_A$(X(s)ds for t > 0 and a Borel subset A of R. These results are used to obtain the asymptotic behavior of P{Z(t) < a}, where Z(t) = $sup_{u\leqt}\midx(u)\mid$ as $t\longrightarrow\infty$, in terms of the rate function in the large deviation principle. A subclass of these processes is the Feller class: there exist nonrandom functions b(t) and a(t) > 0 such that {(X(t) - b(t))/a(t) : t > 0} is stochastically compact, i.e., each sequence has a weakly convergent subsequence with a nondegenerate limit. The stable processes are in this class, but it is much larger. We consider processes in this class for which b(t) may be taken to be zero. For any t > 0, we consider the renormalized process ${X(u\psi(t))/a(\psi(t)),u\geq0}$, where $\psi$(t) = $t(log log t)^{-1}$, and obtain large deviation probability estimates for $L_{t}(A)$ := $(log log t)^{-1}$${\int_{0}}^{loglogt}1_A$$(X(u\psi(t))/a(\psi(t)))dv$. It turns out that the upper and lower bounds are sharp and depend on the entire compact set of limit laws of {X(t)/a(t)}. The results extend to random walks in the Feller class as well. Earlier results of this nature were obtained by Donsker and Varadhan for symmetric stable processes and by Jain for random walks in the domain of attraction of a stable law.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.386-389
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• 2008

Forming limit diagram is created by graphical illustration indicating major and minor strain. In order to provide the criterion for forming safety, FLC(forming limit curve) need to be fitted to the diagram. However, the standard method for the strain measurement and FLC plotting are not fixed yet, which results in inconvenience in digitalized analysis. In this study, new construction method for FLC was suggested in order to minimize operator dependency. For this purpose, major and minor strain were measured automatically and analyzed. Then, a second order equation is adopted to fit the FLC. Optimized by response surface method was performed to ensure particular characteristics of the FLC.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.648-653
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• 2003

In order to predict stress intensity limit of high-temperature creep structures, creep work-time equation, defined as $W_ct^P=B$, was used, and the results of the equation were compared with isochronous stress-strain curve (ISSC) ones of ASME BPV NH Code. For this purpose, the creep strain tests with. time variations for commercial type 316 stainless steel were conducted with different stresses; 160 MPa, 150 MPa, 145 MPa, 140 MPa and 135 MPa at $593^{\circ}C$. The results of log $W_c$ and log t plots showed a good linear relation up to $10^5$ hr. The constants p, B and stress intensity limit values showed comparatively good agreement to those of ASME NH ISSC. It is believed that the relation can be simply obtained with only several short-term 1% strain data without ISSC which can be obtained by long-term creep data.

• 한국생산제조학회지
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• 제4권4호
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• pp.42-49
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• 1995

It is not clearly known how defects or inclusions of a low carbon steel affect a fatigue strength. We study this issue using SM15C materials. The investigation is carried out by a quantitative evaluation, and experimental findings are: (1) a fatigue limit of A series smooth specimen is 205MPa, and that of B, C, D series is 245MPa, 304MPa and 245MPa, respectively. (2) the fatigue limit varies with respects to the stress distribution I the vicinity of a defects and crack. (3) the micro hole creates a half-circular shape crack, while the hole depth is not critical to the fatigue strength, (4) considering the fatigue strength, the hole diameter is more significant than the hole depth, and (5) Fatigue limit of artificially defected specimen is lower than that of a flawless one (5-10%), however, there exist allowance size and depth of defect which don't get to influence at fatigue limit.

• Earthquakes and Structures
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• 제18권6호
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• pp.677-689
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• 2020

A building structural system of moment resisting frame (MRF) with concrete filled steel tubular (CFST) columns and wide flange H beams, is one of the most conveniently constructed structural systems. However, there were few studies on evaluating seismic performance of full-scale CFST columns under high axial compression. In addition, some existing famous design codes propose various limits of width-to-thickness ratio (B/t) for steel tubes of the ductile CFST composite members. This study was intended to investigate the seismic behavior of CFST columns under high axial load compression. Four full-scale square CFST column specimens with a B/t of 42 were carried out that were subjected to horizontal cyclic-reversal loads combined with constantly light, medium and high axial loads and with a linearly varied axial load, respectively. Test results revealed that shear strength and deformation capacity of the columns significantly decreased when the axial compression exceeded 0.35 times the nominal compression strength of a CFST column, P₀. It was obvious that the higher the axial compression, the lower both the shear strength and deformation capacities were, and the earlier and faster the shear strength degradation occurred. It was found as well that higher axial compressions resulted in larger initial lateral stiffness and faster degradation of post-yield lateral stiffness. Meanwhile, the lower axial compressions led to better energy dissipation capacities with larger cumulative energy. Moreover, the study implied that under axial compressions greater than 0.35P₀, the CFST column specimens with B/t limits recommended by AISC 360 (2016), ACI 318 (2014), AIJ (2008) and EC4 (2004) codes do not provide ultimate interstory drift ratio of more than 3% radian, and only the limit in ACI 318 (2014) code satisfies this requirement when axial compression does not exceed 0.35P₀.

• Geomechanics and Engineering
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• 제5권4호
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• pp.299-312
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• 2013

The horizontal pullout capacity of a group of two vertical strip plate anchors, placed along the same vertical plane, in a fully cohesive soil has been computed by using the lower bound finite element limit analysis. The effect of spacing between the plate anchors on the magnitude of total group failure load ($P_{uT}$) has been evaluated. An increase of soil cohesion with depth has also been incorporated in the analysis. For a weightless medium, the total pullout resistance of the group becomes maximum corresponding to a certain optimum spacing between the anchor plates which has been found to vary generally between 0.5B and B; where B is the width of the anchor plate. As compared to a single plate anchor, the increase in the pullout resistance for a group of two anchors becomes greater at a higher embedment ratio. The effect of soil unit weight has also been analyzed. It is noted that the interference effect on the pullout resistance increases further with an increase in the unit weight of soil mass.

• Korea-Australia Rheology Journal
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• 제16권2호
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• pp.91-99
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• 2004

For the Rouse chain composed of infinite number of beads (continuous limit), conformational changes during the creep and creep recovery processes was recently analyzed to reveal the interplay among all Rouse eigenmodes under the constant stress condition (Watanabe and Inoue, Rheol. Acta, 2004). For completeness of the analysis of the Rouse model, this paper analyzes the conformational changes of the discrete Rouse chain having a finite number of beads (N = 3 and 4). The analysis demonstrates that the chain of finite N exhibits the affine deformation on imposition/removal of the stress and this deformation gives the instantaneous component of the recoverable compliance, $J_{R}$(0) = 1/(N-l)v $k_{B}$T with v and $k_{B}$ being the chain number density and Boltzmann constant, respectively. (This component vanishes for N\longrightarrow$\infty$.) For N = 2, it is known that the chain has only one internal eigenmode so that the affinely deformed conformation at the onset of the creep process does not change with time t and $J_{R}$(t) coincides with $J_{R}$(0) at any t (no transient increase of $J_{R}$(t)). However, for N$\geq$3, the chain has N-l eigenmodes (N-l$\geq$2), and this coincidence vanishes. For this case, the chain conformation changes with t to the non-affine conformation under steady flow, and this change is governed by the interplay of the Rouse eigenmodes (under the constant stress condition). This conformational change gives the non-instantaneous increase of $J_{R}$(t) with t, as also noted in the continuous limit (N\longrightarrow$\infty$).X>).TEX>).X>).

• 기본간호학회지
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• 제3권1호
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• pp.68-80
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• 1996

Long-term hemodialysis(HD) patients manifest various signs of protein and caloric malutrition due to poor intake of nutrients and other causes. Poor nutritional status increases the mortality and morbidity rates in HD patients. Thus, mataintnance of adequate nutritional status has been a major task in taking care of patients receiving HD. This study was to evaluate the nutritional status of HD patients and to clarify the degree of nutritional deficit based on usual dietary intake, anthropometric and biochemical indicators. Sixty HD patients comprised a HD group, while the control group consisted of 60 healthy adults whose age and sex matched those of the HD group. Nutritional status was evaluated by dietrary intake using instant nutritional scale, anthropometric measures, serum protein concentrations and the number of lymphocytes. The data were analyzed by using Chi-square test and unpaired t-test. The results are as follows. 1. Regarding usual dietary intake of HD group. 1) Estimated caloric intake was significantly lower than the recommended daily allowance(RDA) and among them, 35% were taking calories less than 85% of the RDA. 2) Estimated protein intake was significantly higher than the RDA and among them 40% were taking protein more than 115% of the RDA. 3) Estimated fat intake was lower than the RDA. 4) Vitamin A, B, $B_1,\;B_2$, C and niacin in take was lower than the RDA respectively. 5) Estimated ferrous intake was within the normal limit the RDA while estimated calcium intake was higher than the RDA. 6) Both calorie and protein intake were higher for the 10 patients who had been under continuous ambulatory peritoneal dialysis than for the patients under HD from the beginning. 2. Regarding anthropometric measures : 1) Body mass index(BMI), midarm circumference(MAC), and triceps skinfold thickness(TSF) were lower in the HD group than in the control group. 2) Among HD group, 47.1% were within the normal limit of BMI, while 86.7% were within the same limit in the control group. 3) Among HD group, 35.0% were within the normal limit of MAC, while 83.3% were within the same limit in the control group. 4) Among HD group, only 8.3% were normal, 30.3% were mild deficit status of TSF, while 50% were normal and 48.3% were mild deficit status in the control group. 3. Regarding biochemical laboratory tests 1) Albumin, transferrin concentrations and the number of lymphocytes were lower in HD group than in the control group. 2) Among HD group, 98.3% were within the normal limit of albumin concentration and all were within the same limit in the control group. 3) Among HD group, only 11.7% were within the normal limit of transferrin concentration, while 81.7% were within the same limit in the control group. 4) Among HD group, 25% were within the normal limit, while 93.3% were within the same limit in the control group. The above findings suggest that HD patients were in nutritional deficit status. Adequate diet therapy and periodical evaluation of the nutritional status in HD patients are needed. Accordingly, it turned out that anthropometric measures were very reliable parameters and easy to use to evaluate nutritional status. So nurses are encouraged to adopt anthropometric measures to examine nutritional deficit status of HD patients.

• Structural Engineering and Mechanics
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• 제21권4호
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• pp.407-422
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• 2005

Plate elements in fully profiled sandwich panels are generally subjected to local buckling failure modes and this behaviour is treated in design by using the conventional effective width method for plates with a width to thickness (b/t) ratio less than 100. If the plate elements are very slender (b/t > 1000), the panel failure is governed by wrinkling instead of local buckling and the strength is determined by the flexural wrinkling formula. The plate elements in fully profiled sandwich panels do not fail by wrinkling as their b/t ratio is generally in the range of 100 to 600. For this plate slenderness region, it was found that the current effective width formula overestimates the strength of the fully profiled sandwich panels whereas the wrinkling formula underestimates it. Hence a new effective width design equation has been developed for practical plate slenderness values. However, no guidelines exist to identify the plate slenderness (b/t) limits defining the local buckling, wrinkling and the intermediate regions so that appropriate design rules can be used based on plate slenderness ratios. A research study was therefore conducted using experimental and numerical studies to investigate the effect of plate slenderness ratio on the ultimate strength behaviour of foam supported steel plate elements. This paper presents the details of the study and the results.