• 한국소음진동공학회논문집
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• 제13권12호
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• pp.930-937
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• 2003

This research deals with how to select connection positions of two substructures to be synthesized. The goal of this research is to find optimal connection positions in order to maximize the fundamental natural frequency of the synthesized structure. The natural frequencies of a connected structure are obtained by modal-force equations. Optimal connection positions can be selected through optimization process. In the optimization process, the natural frequencies of a connected structure are set to object function value and connection positions become design variables. The method described above is applied to synthesis problems of plates, which is initially conducted for FE models and verified through experiments. Especially in experiments. FRF(frequency response function) s are obtained by means of the Modal Testing technique to be used in modal-force equations for synthesizing. Once the substructures are synthesized. the Modal Testing technique is again applied to spot-welded structure using the result from the optimization procedure. It is found that the fundamental natural frequency of the synthesized structure with the optimized result gives higher value than those with the initially given connection positions.

• 한방안이비인후피부과학회지
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• 제9권1호
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• pp.159-165
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• 1996

The study was clinically performed with the 128 out patients of dermatic disease who had visited the Dept. of dermatology, Dongzhimen Hospital, Beijing traditional medical college from May 2nd to February 14th 1996. The results were as follows. 1. The dermatologic findings which showed higher incidence in this study were Acne of Melasma 27 cases($21.0\%$), Psoriasis 25($19.5\%$), Eczema including Contact dermatitis 21($16.4\%$), Seborrheic dermatitis including Alopecia of hair 12($9.3\%$) and Urticaria 11($8.5\%$). 2. The sex ratio of male to female was 4.5 : 5.5. The peak incidence of age group was 30-39($21.8\%$). 3. In the duration of disease, 37 cases($28.9\%$) were between 1 year and 5 years. 27($21.1\%$) were over 10 years. 4. About the single herb drugs, they are Angelicas gigantis Radix, Paeoniae Radix and Salviae Radix in order of frequencies. In the case of pill type, Danggui gosam hwan. Chunggan hwan. Whaeo hwan and Shinnongjiyang hwan are most frequently used. In the case of topica, Whangyeongo, Juachanggo and Soeungo are used in high frequencies. 5. For the test and surgical treatment KOH surgical treatment of Molluscum contagiosum in 8 cases and the bloody treatment of Chronic psoriasis in 3 cases.

• 대한조선학회논문집
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• 제28권1호
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• pp.83-91
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• 1991

본 연구에서는 병진 및 회전 스프링을 포함하는 탄성지반 위에 놓여 있는 다지지보의 동적 해석이 수행되었다. 특히 중간 지지점이 있는 경우에 대한 영향도 조사하였다. 문제의 해석방법으로서 우선 기하학적 및 동적 경계조건을 동시에 만족하는 직교 다항식 함수를 구하였으며, Galerkin 방법을 이용하여 시스템의 고유진동수틀 구하였다. 본 연구에서 제시한 방법으로 구한 고차 직교 다항식 함수를 사용하면 정확한 해를 얻을 수 있다는 것을 여러가지 경우에 대한 수치 계산 결과로부터 알 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.65-71
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• 2003

This research deals with how to select connection positions of two substructures to be synthesized. The goal of this research is to find optimal connection positions in order to maximize the fundamental natural frequency of the synthesized structure. The natural frequencies of a connected structure are obtained by modal-force equations. Optimal connection positions can be selected through optimization process. In the optimization process, the natural frequencies of a connected structure are set to object function value and connection positions become design variables. The method described above is applied to synthesis problems of plates, which is initially conducted for FE models and verified through experiments. Especially in experiments, FRE(frequency Response function)s are obtained by means of the Modal Testing technique to be used in modal-force equations for synthesizing. Once the substructures are synthesized, the Modal Testing technique is again applied to spot-welded structure using the result from the optimization procedure. It is found that the fundamental natural frequency of the synthesized structure with the optimized result gives higher value than those with the initially given connection positions.

• Smart Structures and Systems
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• 제25권6호
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• pp.693-705
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• 2020

In the current investigation, large amplitude free vibration behavior of shallow curved pipes (tubes) made of functionally graded materials is investigated. Properties of the tube are distributed across the radius of the tube and are obtained by means of a power law function. It is also assumed that all thermo-mechanical properties are temperature dependent. The governing equations of the tube are obtained using a higher order shear deformation tube theory, where the traction free boundary conditions are satisfied on the top and bottom surfaces of the tube. The von Kármán type of geometrical non-linearity is included into the formulation to consider the large displacements and small strains. Uniform temperature elevation of the tube is also included into the formulation. For the case of tubes which are simply supported in flexure and axially immovable, the governing equations are solved using the two-step perturbation technique. Closed form expressions are provided to obtain the small and large amplitude fundamental natural frequencies of the FGM shallow curved tubes in thermal environment. Numerical results are given to explore the effects of thermal environment, radius ratio, and length to thickness ratio of the tube on the fundamental linear and non-linear frequencies.

• 한국식생활문화학회지
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• 제11권5호
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• pp.569-579
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• 1996

The purpose of the present study is to collect information in terms of the frequency and amounts in frequently consumed foods. We conducted the secondary analysis from '93 Korean National Nutrition Survey. Mainly informations about 2-day food records were used to investigate food intakes and to compare different food patterns by area. Amounts and frequencies of food intakes are on the list by the order of contributing amounts and frequencies. Amounts of total daily intake of food per capita are 1,054g in nationwide, 1,076g in large city, 1,049g in small city, 1,017g in rural. The major foods consumed in large quantities were rice, kimchi, milk, in nationwide, large city, and small city and rice, kimchi, Korean radish in rural. The intake frequency of kimchi, rice, and basic seasonings as garlic, green onion, salts, soy sauce et al, were higher than other foods in all area. However, there are need for further researches to investigate individual dietary intake and seasonal variation of intakes. Also, food consumption patterns for different groups considering age, sex, area should be studied.

• Journal of Power Electronics
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• 제19권4호
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• pp.980-988
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• 2019

When compared with traditional power frequency generators, the frequency of a super high-speed permanent magnet generator (SHSPMG) is a lot higher. In order to study the influence of frequency on the electromagnetic field of SHSPMGs, a 60000rpm, 117kW SHSPMG was taken as a research object. The two-dimensional finite element model of the generator was established, and the two-dimensional transient field of the generator was simulated. In addition, a test platform of the generator was set up and tested. The reliability of the simulation was verified by comparing the experiment data with that of the simulation. Then the generator electromagnetic field under different frequencies was studied, and the influence mechanism of frequency on the generator electromagnetic field was revealed. The generator loss, voltage regulation rate, torque and torque ripple were analyzed under the rated active power load and different frequencies. The influences of frequency on the eddy current density, loss, voltage regulation rate and torque ripple of the generator were obtained. These conclusions can provide some reference for the design and optimization of SHSPMGs.

• Smart Structures and Systems
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• 제24권2호
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• pp.267-292
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• 2019

The present article addresses the coupled free vibration problem of skew magneto-electro-elastic plates (SMEE) considering the temperature-moisture dependent material properties. The plate kinematics follows Reddy's higher order shear deformation theory. With the aid of finite element methods, the governing equations of motion are derived considering the Hamilton's principle and solved by adopting condensation technique. The influence of different temperature and moisture dependent empirical constants on the frequency response of SMEE plate has been assessed. In addition, the natural frequencies corresponding to various fields are evaluated and the effect of empirical constants on these coupled frequencies is determined. A detailed parametric study has been carried out to assess the individual effects of temperature and moisture dependent empirical constants along with their combined effect, aspect ratio, length-to-width ratio, stacking sequence and boundary conditions. The results reveal that the external environment as well as the geometrical skewness has a significant influence on the stiffness of the SMEE plates.

• Advances in materials Research
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• 제7권2호
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• pp.119-136
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• 2018

In this paper, static and vibration analysis for anti-symmetric cross-ply and angle- ply carbon/glass hybrid laminates rectangular composite plate are presented. In this analysis, the equations of motion for simply supported thick laminated hybrid rectangular plates are derived and obtained through the use of Hamilton's principle. The closed-form solutions of anti-symmetric cross-ply and angle- ply laminates are obtained using Navier solution. The effects of side-to-thickness ratio, aspect ratio, and lamination schemes on the fundamental frequencies loads are investigated. The study concludes that shear deformation laminate theories accurately predict the behavior of composite laminates, whereas the classical laminate theory over predicts natural frequencies. The excellent accuracy of the present analytical solution is confirmed by making some comparisons of the present results with those available in the literature. It can be concluded that the proposed theory is accurate and simple in solving the free vibration behaviors of anti-symmetric cross-ply and angle- ply hybrid laminated composite plates.

• Steel and Composite Structures
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• 제46권4호
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• pp.553-563
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• 2023

In the current research, the nonlinear free vibrations of curved pipes made of functionally graded (FG) carbon nanotube reinforced composite (CNTRC) materials are investigated. It is assumed that the FG-CNTRC curved pipe is supported on a three-parameter nonlinear elastic foundation and is subjected to a uniform temperature rise. Properties of the curved nanocomposite pipe are distributed across the radius of the pipe and are given by means of a refined rule of mixtures approach. It is also assumed that all thermomechanical properties of the nanocomposite pipe are temperature-dependent. The governing equations of the curved pipe are obtained using a higher order shear deformation theory, where the traction free boundary conditions are satisfied on the top and bottom surfaces of the pipe. The von Kármán type of geometrical non-linearity is included into the formulation to consider the large deflection in the curved nanocomposite pipe. For the case of nanocomposite curved pipes which are simply supported in flexure and axially immovable, the motion equations are solved using the two-step perturbation technique. The closed-form expressions are provided to obtain the small- and large-amplitude frequencies of FG-CNTRC curved pipes rested on a nonlinear elastic foundation in thermal environment. Numerical results are given to explore the effects of CNT distribution pattern, the CNT volume fraction, thermal environment, nonlinear foundation stiffness, and geometrical parameters on the fundamental linear and nonlinear frequencies of the curved nanocomposite pipe.