• 대한가정학회지
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• 제36권4호
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• pp.199-215
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• 1998

The purposes of the study were to investingate selected living conditions of the elderly I Inchon and to examine if they can be disaggregated according to their socio-demographic characteristics in terms of living conditions. Four living areas were examined in the study : health and food habit, housing, economic status, and family relationships. Data were collected by questionaires. The sample consisted of 202 elderly. It was found in general that the living conditions were relatively poor for the elderly who were female, older and less educated, and had higher household income and no spouse.

• 대한치과보철학회지
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• 제36권2호
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• pp.355-365
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• 1998

The purpose of this study is to evaluate the accuracy of four elastomeric interocclusal recording materials and the weight change according to different storage period (24 hours, 48hours, 7days) and different conditions (dry, wet). The techniques for establishing the intercuspal position were centic occlusion interocclusal record with four elastomeric interocclusal recording materials (Ramitec, Stat-BR, Blu-Mousse, Regisil) (experimental groups) and location of the cast in a position of maximum in-terdigitation using tactile and visual method(control group). To evaluate the accuracy of four elastomeric interocclusal recording materials, the quality of contacts between the mounted casts was compared with the results of an occlusal examination of the same subjects. The results were as follows : 1. The most accurate method of articulating study casts at the intercuspal position was by hand articulation and no significant differences in accuracy were observerd among the experimental groups. 2. In case of interocclusal records storaged in dry sealed plastic box, no significant differences in accuracy were observed among the experimental groups. 3. In case of interocclusal records storaged in water, there was significant inaccuracy in Ramitec group. 4. The biggest weight change was observed in Ramitec group in all storage conditions

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.28-36
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• 1997

Several thick board and dimension lumbers of Japanese larch(Larix leptolepis), Dahurian larch(Larix gmelini) and radiata pine(Pinus radiata) air-dried in four different seasons to compare air-drying process. Patterns of air-drying curves were influenced by climatological conditions and limber thickness. The initial drying rates of summer were the highest, followed those of fall, spring and winter. The drying times to equilibrium moisture contents for four seasons were nearly the same except for winter. However, the drying time for winter required twice more time than the other seasons. The drying time of dimension lumbers required 1.3 times more than boards. The final moisture contents were lowest during spring, highest during winter and similar between summer and fall.

• Communications for Statistical Applications and Methods
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• 제28권6호
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• pp.595-610
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• 2021

Recently a few articles have derived robust first-order rotatable and D-optimal designs for the lifetime response having distributions gamma, lognormal, Weibull, exponential assuming errors that are correlated with different correlation structures such as autocorrelated, intra-class, inter-class, tri-diagonal, compound symmetry. Practically, a first-order model is an adequate approximation to the true surface in a small region of the explanatory variables. A second-order model is always appropriate for an unknown region, or if there is any curvature in the system. The current article aims to extend the ideas of these articles for second-order models. Invariant (free of the above four distributions) robust (free of correlation parameter values) second-order rotatable designs have been derived for the intra-class and inter-class correlated error structures. Second-order rotatability conditions have been derived herein assuming the response follows non-normal distribution (any one of the above four distributions) and errors have a general correlated error structure. These conditions are further simplified under intra-class and inter-class correlated error structures, and second-order rotatable designs are developed under these two structures for the response having anyone of the above four distributions. It is derived herein that robust second-order rotatable designs depend on the respective error variance covariance structure but they are independent of the correlation parameter values, as well as the considered four response lifetime distributions.

• Steel and Composite Structures
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• 제33권2호
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• pp.195-208
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• 2019

Based on a four-variable shear deformation shell theory, the free vibration analysis of functionally graded graphene platelet-reinforced composite (FGGPRC) doubly-curved shallow shells with different boundary conditions is investigated in this work. The doubly-curved shells are composed of multi nanocomposite layers that are reinforced with graphene platelets. The graphene platelets are uniformly distributed in each individual layer. While, the volume faction of the graphene is graded from layer to other in accordance with a novel distribution law. Based on the suggested distribution law, four types of FGGPRC doubly-curved shells are studied. The present shells are assumed to be rested on elastic foundations. The material properties of each layer are calculated using a micromechanical model. Four equations of motion are deduced utilizing Hamilton's principle and then converted to an eigenvalue problem employing an analytical method. The obtained results are checked by introducing some comparison examples. A detailed parametric investigation is performed to illustrate the influences of the distribution type of volume fraction, shell curvatures, elastic foundation stiffness and boundary conditions on the vibration of FGGPRC doubly-curved shells.

• 한국임상수의학회지
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• 제40권4호
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• pp.268-275
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• 2023

In this paper, we designed 3D-printed orthopedic splint models for patient-specific external coaptation on fracture healing and analyzed the stability of the models through finite element method (FEM) analysis under compressive load conditions. Polylactic acid (PLA) and acrylonitrile-butadiene-styrene (ABS) based 3D splint models of the thicknesses 1, 3, 5 and 7 mm were designed, and Peak von Mises stress (PVMS) and maximum displacement (MD) of the models were analyzed by FEM under compressive loads of 50, 100, 150, and 200 N. The FEM results indicated that PVMS and MD values, regardless of material, had a negative correlation with the thickness of the models and a positive correlation with the compressive load. There was a risk of splint deformation under conditions more extreme than 100 N with 5 mm thickness. For successful clinical application of 3D-printed orthopedic splints in veterinary medicine, it is recommended that the splint should be produced not less than 5 mm thickness. Also, it is expected to be stable when the splint is applied to situations with a compressive load of 100 N or less. There is an advantage of overcoming the limitations of the existing bandage method through 3D-printing technology as well as verifying the stability through 3D modeling before application. Such 3D printing technology will be widely used in veterinary medicine and various fields as well as orthopedics.

• 충청수학회지
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• 제13권2호
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• pp.61-70
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• 2001

Certain elliptic interacting system involving symbiotic is considered. The sufficient conditions for the existence of positive solutions of system is provided for four different types of interaction among three species by using the method of decomposing operator.

• The Journal of Korean Physical Therapy
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• 제22권5호
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• pp.33-38
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• 2010

Purpose: This study examined the activation of the rectus abdominis (RA), external abdominal oblique (EO), transversus abdominis, internal abdominal oblique (TrA/IO), and Multifidus (MF) muscles while stabilization exercise was performed in a four-point kneeling position. Methods: Experiments were conducted on 21 healthy male adults (mean age=25.29 years) who voluntarily agreed to participate in the study. Each subject was instructed regarding maximal voluntary contractions (MVC) and stabilization exercise in four-point kneeling. While MVC and stabilization exercise of individual muscles were being performed, activation of the muscles was measured using surface electromyography (EMG). Activation of the muscles while performing stabilization exercise in four-point kneeling was normalized to a percentages of the MVC. Results: Left RA, right TrA/IO, right and left MF muscles showed significant differences among the positions. Conclusion: Selecting an optimal position can aid subjects on physical conditions while performing stabilization exercises in the four-point kneeling position.

• 설비공학논문집
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• 제15권1호
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• pp.73-85
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• 2003

Four different methods of reducing the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two different heat and mass transfer models and two different fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the data with the reduction methods revealed that the single potential heat and mass transfer model yielded the humidity independent heat transfer coefficients. Two different fin efficiency models - enthalpy model and humidity model - yielded approximately the same fin efficiencies and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

• Structural Engineering and Mechanics
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• 제90권5호
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• pp.517-530
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• 2024

This paper presents a new four-unknown equivalent single layer (ESL) refined plate theory for the buckling analysis of functionally graded (FG) rectangular plates with all simply supported edges and subjected to in-plane mechanical loading conditions. The present model accounts for a parabolic variation of transverse shear stress over the thickness, and accommodates correctly the zero shear stress conditions on the top and bottom surfaces of the plate. The material properties are supposed to vary smoothly in the thickness direction through the rules of mixture named power-law gradation. The governing equilibrium equations are formulated based on the total potential energy principle and solved for simply supported boundary conditions by implementing the Navier's method. A numerical result on elastic buckling using the current theory was computed and compared with those published in the literature to examine the accuracy of the proposed analytical solution. The effects of changing power-law exponent, aspect ratio, thickness ratio and modulus ratio on the critical buckling load of FG plates under different in-plane loading conditions are investigated in detail. Moreover, it was found that the geometric parameters and power-law exponent play significant influences on the buckling behavior of the FG plates.