• 한국의류학회지
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• 제28권3_4호
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• pp.414-421
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• 2004

To reduce farmer's stress from solar radiation and ultraviolet radiation(UV), the sunshade hat with a large brim and special structure for ventilation was developed and tested with manikin heads outdoors at previous study(Kim and Choi, 2002). To evaluate the protection efficiency of the sunshade hat, human trial test was performed at outdoors. The results were as follows; Skin temperatures(7 sites), heart rate, temperature inside the hats, temperature and relative humidity inside clothing on the back in wearing developed sunshade hat were significantly lower than those in wearing the controlled hat. In subjective sensation, subjects answered to feel significantly hotter, more humid and more uncomfortable in wearing the controlled hat. But relative humidity inside the hats was significantly higher in wearing developed hat. In rectal temperature, there were no significant differences between two hats.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.161-165
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• 2013

In this paper, possibility of controlling motion of a floating structure using a tuned liquid damper (TLD) is numerically investigated. A TLD is a tank partially filled with liquid. Sloshing phenomena of liquid inside a tank can suppress movement of the tank subject to external excitations at specific frequency. The effects of sloshing phenomena inside a rectangular floating body on its sway motion are investigated by varying excitation frequency. First, a grid-refinement study is carried out to ensure validity of grid independent numerical solutions using present numerical techniques. Then, sway motion of the floating body subjected to wave with five different frequencies are simulated. The normalized amplitudes of sway motion of the target floating body are compared over the frequency, for cases with and without water inside the floating body. It is shown that the motion of the floating body can be minimized by matching the sloshing natural frequency to excitation frequency.

• Journal of Biosystems Engineering
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• 제20권2호
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• pp.127-132
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• 1995

In the first part of this paper, an analysis of the cab noise of a selected agricultural tractor was presented. In this study, using the results of the previous analysis, two passive noise control measures of the sound insulation and absorption were conducted to reduce the noise level inside the cab. These measures of noise control reduced the total noise level by 6.2㏈(A) at the operator position inside the cab. In order to further reduce the cab noise, particularly, of lower frequencies than 630Hz, stiffness and damping of the floor panel should be enforced. It was also suggested that a proper suspension for the cab mounting is necessary to reduce the level of structure-born noises.

• International Journal of Industrial Entomology and Biomaterials
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• 제38권1호
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• pp.18-23
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• 2019

Bombyx mori silkworm has many silkworm varieties and the structure and properties of silk can be varied depending on the silkworm variety. Therefore, the choice of proper silkworm variety can be an effective way to control and improve the performance of silk materials in biomedical and cosmetic applications. As a preliminary study, in the present study, thirty nine Bombyx mori silkworm cocoons were prepared and their molecular conformation and crystallinity were examined. Molecular conformation and the crystallinity of silkworm cocoons were different depending on the silkworm variety. Interestingly, the crystallinity index of outside of cocoon was different from that of inside of cocoon and the difference between the crystallinities of outside and inside of cocoon was varied depending on the silkworm variety. In this study, the silkworm variety cocoons were classified into three groups (Group 1, Group 2, and Group 3) based on the difference of crystallinities between outside and inside.

• Structural Engineering and Mechanics
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• 제61권2호
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• pp.231-244
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• 2017

The aim of this study is to develop a semi-analytical method to investigate fluid-structure coupling of concentric double shells with different lengths and elastic behaviours. Co-axial shells constitute a cylindrical circular container and a baffle submerged inside the stored fluid. The container shell is made of functionally graded materials with mechanical properties changing through its thickness continuously. The baffle made of steel is fixed along its top edge and submerged inside fluid such that its lower edge freely moves. The developed approach is verified using a commercial finite element computer code. Although the model is presented for a specific case in the present work, it can be generalized to investigate coupling of shell-plate structures via fluid. It is shown that the coupling between concentric shells occurs only when they vibrate in a same circumferential mode number, n. It is also revealed that the normalized vibration amplitude of the inner shell is about the same as that of the outer shell, for narrower radial gaps. Moreover, the natural frequencies of the fluid-coupled system gradually decrease and converge to the certain values as the gradient index increases.

• Structural Engineering and Mechanics
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• 제68권1호
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• pp.1-15
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• 2018

In ocean industry, free surface type ART (Anti Roll tank) system has been widely used to suppress the roll motion of floating structures. In those, various obstacles have been devised to obtain the sufficient damping and to enhance the controllability of freely rushing water inside the tank. Most of previous researches have paid on the development of simple mathematical formula for coupled ship-ARTs analysis although other numerical and experimental approaches exist. Little attention has been focused on the use of 3D panel method for preliminary design of free surface type ART despite its advantages in computational time and general capacity for hydrodynamic damping estimation. This study aims at developing a potential theory based hydrodynamic code for the analysis of floating structure with baffled ARTs. The sloshing in baffled tanks is modeled through the linear potential theory with FE discretization and it coupled with hydrodynamic equations of floating structures discretized by BEM and FEM, resulting in direct coupled FE-BE formulation. The general capacity of proposed formulation is emphasized through the coupled hydrodynamic analysis of floating structure and sloshing inside baffled ARTs. In addition, the numerical methods for natural sloshing frequency tuning and estimation of hydrodynamic damping ratio of liquid sloshing in baffled tanks undergoing wave exiting loads are developed through the proposed formulation. In numerical examples, effects of natural frequency tuning and baffle ratios on the maximum and significant roll motions are investigated.

• Structural Engineering and Mechanics
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• 제33권5호
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• pp.635-647
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• 2009

For the calculation of foundation settlement it is recommended to take into account so called influence zone inside the subsoil bellow the foundation structure. Influence zone inside the subsoil is the region where the load has a substantial influence on the deformation of the soil skeleton. The soil skeleton is pre-consolidated or over consolidated due to the original geostatic stress state. An excavation changes the original geostatic stress state and it creates the space for the load transferred from upper structure. The theory of elastic layer in Westergard manner is selected for the vertical stress calculation. The depth of influence zone is calculated from the equality of the original geostatic stress and the new geostatic stress due to excavation combined with the vertical stress from the upper structure. Two close formulas are presented for the influence zone calculation. Using ADINA code we carried out several numerical examples to verify the proposed analytical formulas and to enhance their use in civil engineering practice. Otherwise, the FEM code accuracy can be control.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.290-293
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• 2006

From the hydraulic experiment, it was concluded that upwelling could be enhanced when the relative structure height (the ratio of structure height to water depth) was 0.3 and stratification parameter was 3.0. In addition, the optimum size of rubbers was determined that the effect of the mean horizontal length of block was affected incident velocity than size of block. In the numerical experiment, the relation between the shape of rubber and stratification parameter was verified, ana the hydraulic characteristics of 3-D flow field around the artificial structures were investigated. Phenomena of flow field around the artificial upwelling structures corresponded with the results of hydraulic experiment. The position with maximum velocity in artificial upwelling structure was the center of top of its front side and the slip stream occurred at the inside and behind-bottom of artificial upwelling structures. The velocity of slip stream and early amplitude of velocity were higher in the inside than the behind-bottom.

• 한국건축시공학회지
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• 제4권2호
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• pp.113-118
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• 2004

This study is a basic experiment on quality management of the compression strength of high strength concrete, aiming. at quality management of high strength mass concrete by giving the temperature hysteresis of the mass test pieces to managerial test pieces. Different from ordinary concrete, high strength concrete generally shows the temperature high rising caused by hydration heat inside the concrete. It is known that, in mass concrete, thermal stress occurs due to the difference in temperature between the inside and the outside, which causes a significant difference in compression strength between structure beams and managerial test pieces. It is also reported that there is a large difference between the compression strength of cylindrical managerial test pieces of standard underwater curing and the strength of structure beam concrete. Thus, this study made concrete test pieces in an optimal mix ratio for each strength level, and also created thermal insulation curing box and managerial test pieces. Then it carried out comparative analysis in relation to core strength and suggested equipment and a technique that can control the strength of high strength concrete mass more conveniently and accurately.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.401-405
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• 2017

연속가변 추력기는 비행체의 위치 또는 자세 변경 및 연소실 내부의 압력 조절을 위하여 정밀 추력 조절이 요구된다. 이를 위하여 연소실 내부의 노즐 목 근처에 설치된 핀틀 구조물을 앞/뒤로 움직여 추력을 조절하고, 핀틀 구조물을 움직이기 위하여 구동장치를 사용한다. 본 논문에서는 연속가변 추력기용 구동장치를 개발하였으며, 운용조건에서의 부하를 모사하기 위한 부하시험장비를 개발하였다. 또한, 개발된 부하시험장비를 이용하여 구동장치의 성능 시험을 수행하였다.