• Geomechanics and Engineering
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• 제7권1호
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• pp.87-103
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• 2014

This study investigated the effect of soil-structure interaction (SSI) on the response of base-isolated buildings. Seismic isolation can significantly reduce the induced seismic loads on a relatively stiff building by introducing flexibility at its base and avoiding resonance with the predominant frequencies of common earthquakes. To provide a better understanding of the movement behavior of multi-story structures during earthquakes, this study analyzed the dynamic behavior of multi-story structures with high damping rubber bearing (HDRB) behavior base isolation systems that were built on soft soil. Various models were developed, both with and without consideration of SSI. Both the superstructure and soil were modeled linearly, but HDRB was modeled non-linearly. The behavior of the specified models under dynamic loads was analyzed using SAP2000 computer software. Erzincan, Marmara and Duzce Earthquakes were chosen as the ground motions. Following the analysis, the displacements, base shear forces, top story accelerations, base level accelerations, periods and maximum internal forces were compared in isolated and fixed-base structures with and without SSI. The results indicate that soil-structure interaction is an important factor (in terms of earthquakes) to consider in the selection of an appropriate isolator for base-isolated structures on soft soils.

• 한국전자파학회논문지
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• 제12권1호
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• pp.125-135
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• 2001

본 논문에서는 SAR(Synthertic Aperture Radar) 시스템에 적합한 이중편하 하중 지지형 마이크로스트림 8$\times$4 배열 안테나를 설계, 제작하여, 그 측정 결과를 시뮬레이션 결과와 비교하였다. 안테나 설계 시 운용 주파수와 대역폭, polarization putity, -3 dB 빔 폭 등과 같은 전기적 특성뿐만 아니라, 구조적 안정성, 강도, 강성 등의 기계적 특성을 함께 고려하였다. 본 안테나는 SSFIP 형 구조에 허니콤과 Shielding plane을 첨가한 형태이며, 이중편파는 서로 수직으로 위치한 두 개의 dog-bone shape 슬롯으로 구현하였다. 각 실험 결과로부터 제안한 안테나 중심 주파수 5.3 GHz를 중심으로 약 80GHz 의 대역폭을 지니고, -20 dB 이하의 cross-polarization level, 약 40dB 정도의 포트간 고립도 특성을 타나내며 구조적으로도 안정됨을 알 수 있었다.

• The Korean Journal of Physiology and Pharmacology
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• 제19권1호
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• pp.35-42
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• 2015

In cardiovascular disorders, understanding of endothelial cell (EC) function is essential to elucidate the disease mechanism. Although the mouse model has many advantages for in vivo and in vitro research, efficient procedures for the isolation and propagation of primary mouse EC have been problematic. We describe a high yield process for isolation and in vitro culture of primary EC from mouse arteries (aorta, braches of superior mesenteric artery, and cerebral arteries from the circle of Willis). Mouse arteries were carefully dissected without damage under a light microscope, and small pieces of the vessels were transferred on/in a Matrigel matrix enriched with endothelial growth supplement. Primary cells that proliferated in Matrigel were propagated in advanced DMEM with fetal calf serum or platelet-derived serum, EC growth supplement, and heparin. To improve the purity of the cell culture, we applied shearing stress and anti-fibroblast antibody. EC were characterized by a monolayer cobble stone appearance, positive staining with acetylated low density lipoprotein labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate, RT-PCR using primers for von-Willebrand factor, and determination of the protein level endothelial nitric oxide synthase. Our simple, efficient method would facilitate in vitro functional investigations of EC from mouse vessels.

• 한국군사과학기술학회지
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• 제22권6호
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• pp.824-831
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• 2019

For effective development in consideration of the maintainability of the weapon system, it is necessary to understand whether the maintainability design requirements are satisfied at the early phase of development. This requires the application of an early design phase maintainability prediction process to provide opportunities for improvement. By defining the ambiguity group definition, fault isolation level, fault isolation probability, and countermeasures for faults, it was possible to predict early phase development. The MTTR of the initial design phase applying Procedure V to the artillery system was 3.46H, which is about 16 % higher than 2.98H, the MTTR using Procedure II. This is a result of system design ambiguity that has not been specified in the early phase of development.

• Smart Structures and Systems
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• 제24권5호
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• pp.641-648
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• 2019

The authors investigate the feasibility of applying a vision-based displacement-measurement technique in the characterization of a SMA damper recently introduced in the literature. The experimental campaign tests a steel frame on a uni-axial shaking table driven by sinusoidal signals in the frequency range from 1Hz to 5Hz. Three different cameras are used to collect the images, namely an industrial camera and two commercial smartphones. The achieved results are compared. The camera showing the better performance is then used to test the same frame after its base isolation. U-shaped, shape-memory-alloy (SMA) elements are installed as dampers at the isolation level. The accelerations of the shaking table and those of the frame basement are measured by accelerometers. A system of markers is glued on these system components, as well as along the U-shaped elements serving as dampers. The different phases of the test are discussed, in the attempt to obtain as much possible information on the behavior of the SMA elements. Several tests were carried out until the thinner U-shaped element went to failure.

• Earthquakes and Structures
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• 제25권3호
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• pp.161-175
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• 2023

High-damping rubber bearings (HDRB) are commonly used as seismic isolation devices to protect civil engineering structures from earthquakes. However, the nonlinear hysteresis characteristics of the HDRB, such as their dependence on material properties and hardening phenomena, make predicting their behavior during earthquakes difficult. This study proposes a hysteretic model that can accurately predicts the behavior of shear deformation considering the nonlinearity when designing the seismic isolation structures using HDR bearings. To model the hysteretic characteristics of the HDR, dynamic loading tests were performed by applying sinusoidal and random waves on scaled-down specimens. The test results show that the nonlinear characteristics of the HDR strongly correlate with the shear strain experienced in the past. Furthermore, when shear deformation occurred above a certain level, the hardening phenomenon, wherein the stiffness increased rapidly, was confirmed. Based on the experimental results, the dynamic characteristics of the HDR, equivalent stiffness, equivalent damping ratio, and strain energy were quantitatively evaluated and analyzed. In this study, an improved bilinear HDR model that can reproduce the dependence on shear deformation and hardening phenomena was developed. Additionally, by proposing an objective parameter-setting procedure based on the experimental results, the model was devised such that similar parameters could be set by anyone. Further, an actual dynamic analysis could be performed by modeling with minimal parameters. The proposed model corresponded with the experimental results and successfully reproduced the mechanical characteristics evaluated from experimental results within an error margin of 10%.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제29권2호
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• pp.49-60
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• 2023

Purpose: This study aims to establish detailed spatial planning by identifying the needs for a seclusion module for emergency psychiatric patients. Methods: The necessity of medical space with seclusion function was analyzed from spatial, medical, and social perspectives. The needs for a space capable of performing three medical functions: protection, isolation, and treatment, was analyzed. Among various types of mobile medical facilities, seclusion space was considered suitable for utilizing modular construction methods, as it is the most rational method that can satisfy the environmental level of fixed healthcare facilities' space. Therefore, seclusion modules based on modular construction were planned, consisting of two protective units for stabilizing patients with psychiatric illness, one for treatment unit that can accommodate both internal and external treatment, and another one for an infectious disease isolation unit equipped with negative pressure equipment. Implications: This study analyzed the necessary medical functions of the interior space of the mobile stabilization module based on the spatial analysis of existing medical facilities, and proposed alternative spatial configurations according to treatment, seclusion, isolation functions.

• Structural Engineering and Mechanics
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• 제89권2호
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• pp.121-133
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• 2024

In this paper, the performance of under-foundation isolators against generally annoying train-induced vibrations was examined experimentally. The effect of foundation type on the efficacy of such isolators was investigated for the first time. To this end, laboratory models including a soil container, soil, building with three types of foundation (i.e., single, strip, and mat), and isolator layer were employed. Through various dynamic tests, the effects of foundation type, isolation frequency, and the dominant frequency of train load on the isolator's performance were studied. The results demonstrated that the vibration level in the unisolated building with the strip and mat foundation was, respectively, 29 and 38% lower than in the building with the single foundation. However, the efficacy of the isolator in the building with the single foundation was, respectively, 21 and 40% higher than in the building with the strip and mat foundation. Furthermore, a lower isolation frequency and a higher excitation frequency resulted in greater isolator efficacy. The best vibration suppression occurred when the excitation frequency was close to the floor's natural frequency.

• Food Science and Biotechnology
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• 제17권1호
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• pp.123-129
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• 2008

To isolate Bacillus cereus presenting at a level of 5 log CFU/g in kochujang, a primary dilution ($10^{-1}$) of kochujang was heated at $85^{\circ}C$ for 5 min. Two isolated strains Voges-Proskauer positive colony (KBC) and a negative colony (KBM) were identified as B. cereus and Bacillus mycoides, respectively, by biochemical test and 16S rDNA sequencing. $D_{100^{\circ}C}$-Values of KBC and KBM strains was 8.37 and 7.08 min, respectively. When spores of KBC strain were inoculated to kochujang at the level of 4-5 log spores/g, the number of spores was no significant difference (p<0.05) for each sample from 1 up to 60 day of aging. When kochujang was inoculated with 4 log spores/g and heated at $85^{\circ}C$ for 15 min, the number of spores was similar to that of unheated kochujang. Therefore, we estimated that B. cereus isolated from kochujang resistant on the heat treatment ($85^{\circ}C$, 15 min) and its heat resistance characteristics could be used to count the number in kochtjang.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.869-874
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• 2001

In order that precision equipment using high precision industrial operate normally. vibration criteria of expected area that equipment be set up is micrometer level. that method is a trust design for apply to in field, when there attend to quantifiable method. Hence, semi -empirical method that using on the basis of experimental data about undefined information (properities of vibration source, dynamic properities of structure, etc.,) for prediction of vibration response make the use of dynamic structure design of semiconductor ＆ TFT-LCD in the inside and outside country. Like this, for doing an optimal design of dynamic about structure, it is best important to get trust data that apply to semi-empirical method that is method of prediction vibration level. In this paper, on the basis of experimental data which was offered by a manufacturing company Of precisin equipment that plan to set up in semiconductor factory, we predicted vibration response on expected area that equipment be set up.