• Smart Structures and Systems
• /
• v.23 no.6
• /
• pp.627-639
• /
• 2019

Passive control may not provide enough damping for a stay cable since the control devices are often restricted to a low location level. In order to enhance control performance of conventional passive dampers, a new type of damper integrated with a rotary electromagnetic damper providing variable damping force and a flywheel serving as an inertial mass, called the rotary electromagnetic inertial mass damper (REIMD), is presented for suppressing the cable vibrations in this paper. The mechanical model of the REIMD is theoretically derived according to generation mechanisms of the damping force and the inertial force, and further validated by performance tests. General dynamic characteristics of an idealized taut cable with a REIMD installed close to the cable end are theoretically investigated, and parametric analysis are then conducted to investigate the effects of inertial mass and damping coefficient on vibration control performance. Finally, vibration control tests on a scaled cable model with a REIMD are performed to further verify mitigation performance through the first two modal additional damping ratios of the cable. Both the theoretical and experimental results show that control performance of the cable with the REIMD are much better than those of conventional passive viscous dampers, which mainly attributes to the increment of the damper displacement due to the inertial mass induced negative stiffness effects of the REIMD. Moreover, it is concluded that both inertial mass and damping coefficient of an optimum REIMD will decrease with the increase of the mode order of the cable, and oversize inertial mass may lead to negative effect on the control performance.

• Structural Engineering and Mechanics
• /
• v.83 no.5
• /
• pp.655-669
• /
• 2022

Passive vibration control devices like tuned liquid column dampers (TLCD) not only significantly reduce buildings' vibrations but also can serve as a water storage facility. The recently introduced modified form of TLCD known as tuned liquid column ball damper (TLCBD) suppressed external vibration efficiently compared to traditional TLCD. For excellent performance, the mass ratio of TLCBD should be in the range of 5% to 7%, which does not include the mass of the ball. This additional mass of the ball increases the overall structure mass. Therefore, in this paper, an effort is made to reduce the mass of TLCBD. For this purpose, a new modified version of TLCBD known as tuned liquid column hollow ball damper (TLCHBD) is proposed. The existing mathematical modeling of TLCBD is used for this new damper by updating the numerical values of the mass and mass moment of the ball. Analytically the optimal design parameters are obtained. Numerically the TLCHBD is investigated with a single degree of freedom structure under harmonic and seismic loadings. It is found that TLCHBD performance is similar to TLCBD in both loadings' cases. To validate the numerical results, an experimental study is conducted. The mass of the ball of TLCHBD is reduced by 50% compared to the ball of TLCBD. Both the arrangements are studied with a multi-degree of freedom structure under harmonic and seismic loadings using a shake table. The results of the experimental study confirm the numerical findings. It is found that the performance behavior of both the dampers is almost similar under harmonic and seismic loadings. In short, the TLCHBD is lighter in weight than TLCBD but has a similar vibration suppression ability.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.11
• /
• pp.3228-3232
• /
• 2010

Malachite green (MG) has been used world-widely in aquaculture as a parasiticide or fungicide. Although MG performed successfully, it has not been permitted for use in aquaculture from European Union, USA, and Canada because of its carcinogenicity and mutagenicity. We developed a sensitive and specific method to determine MG and its principal metabolite, leucomalachite green (LMG), respectively by isotope dilution liquid chromatography mass spectrometry (ID-LC/MS). To enhance the extraction recovery of MG and LMG from fish tissue, an additional step, saponification, was introduced in sample preparation process to remove fat in sample extract, which hampered the performance of SPE columns. The residue of MG and LMG in fish was analyzed using liquid chromatography mass spectrometry in the selected ion monitoring (SIM) mode by monitoring at m/z 329 and 334 for MG and $d_5$-MG and at m/z 331 and 337 for LMG and $^{13}C_6$-LMG, respectively. This method was validated by comparing with the value of the reference material provided by Laboratory Government Chemistry (LGC). The results agreed within the measurement uncertainty and the accuracy was much improved than the provided reference value by LGC.

• Preventive Nutrition and Food Science
• /
• v.3 no.2
• /
• pp.111-118
• /
• 1998

To develop a simple, rapid and simultaneous analytical method of phenolic compounds using gas chromatography (GC) and gas chromatography/mass spectrophometer (GC/Ms), this experiment was carried out to search the retention times of capillary columns and the characteristics of fragment ions in electron impact mass spectra. Most of trimethylsilyl derivatives and underivatized phenolic compounds were separated very well on three kinds of capillary columns(HP-1), Ultra-2 and HP-35). Quantitiative determination of phenolic compounds was achieved by internal standards (p-hydroxybenzoic acid iopropyl ester, p-hydroxybenzoic acid ethyl ester). Calibration plts were linear in the investigated range, and the limits of detection were about 5 ng at split mode method. When analyzed by three columns, theseparation times were fairly constant on two nonpolar columns, but a few compounds showed slightly different separation order by the itnermediate polar HP-35 column. The important characteristic patterns of TMS derivatives of phenolic compounds on the EI/MS spectrra appeared at the base peak of [M-15]+ ion and presented at high abundance in most TMS derivatives of phenoloc compounds. [M]+, [M-CH3-COO]+, [M-Si(CH3)4]+ and [M-Si(CH3)4 -CH3]+ also observed in mass spectra of these compounds . Although several compounds have the same retention times on GC column, it might be possible to identify these compounds by the different patternsof mass frgement ions. The TMS derivatives, thus , provide additional information for identification of phenolic compounds in biological systems.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.63.3-63.3
• /
• 2019

Nearby young moving groups (NYMGs hereafter) are gravitationally unbound loose young stellar associations located within 100 pc of the Sun. Since NYMGs are crucial laboratories for studying low-mass stars and planets, intensive searches for NYMG members have been performed. For identification of NYMG members, various strategies and methods have been applied. As a result, the reliability of the members in terms of membership is not uniform, which means that a careful membership re-assessment is required. In this study, I developed a NYMG membership probability calculation tool based on Bayesian inference (Bayesian Assessment of Moving Groups: BAMG). For the development of the BAMG tool, I constructed ellipsoidal models for nine NYMGs via iterative and self-consistent processes. Using BAMG, memberships of claimed members in the literature (N~2000) were evaluated, and 35 per cent of members were confirmed as bona fide members of NYMGs. Based on the deficiency of low-mass members appeared in mass function using these bona fide members, low mass members from Gaia DR2 are identified. About 2000 new M dwarf and brown dwarf candidate members were identified. Memberships of ~70 members with RV from Gaia were confirmed, and the additional ~20 members were confirmed via spectroscopic observation. Not relying on previous knowledge about the existence of nine NYMGs, unsupervised machine learning analyses were applied to NYMG members. K-means and Agglomerative Clustering algorithms result in similar trends of grouping. As a result, six previously known groups (TWA, beta-Pic, Carina, Argus, AB Doradus, and Volans-Carina) were rediscovered. Three the other known groups are recognized as well; however, they are combined into two new separate groups (ThOr+Columba and TucHor+Columba).

• The Journal of Pediatrics of Korean Medicine
• /
• v.30 no.2
• /
• pp.72-81
• /
• 2016

Objectives The purpose of this study is to understand the correlation between spleen deficiency syndrome, body mass index (BMI) and eating habit in children and adolescents and to provide foundation of preventive care and treatment. Methods A survey was conducted with 115 children and adolescents, who were 4th, 5th and 6th grade of elementary school in Gwangju from March 2nd, 2016 to April 8th, 2016. Body mass index (BMI) was calculated using the measured height and weight. Spleen deficiency syndrome and eating habit in children and adolescents were investigated by using the Deficiency of the Spleen Questionnaire and Korean Children's Eating Behaviour Questionnaire (K-CEBQ). A data analysis was performed by using SPSS 23.0 program. Results 1. There was no statistically significant correlation between spleen deficiency syndrome and body mass index (BMI). 2. Children and adolescents with spleen deficiency syndrome were interested in food rather than avoided it. 3. There was a positive correlation between body mass index (BMI) and FR (Food responsiveness), "Food approach". The correlation between the healthy weight group and FR is statistically significant negative correlation. Conclusions Due to various limitations, it is difficult to generalize the correlation between spleen deficiency syndrome, body mass index (BMI) and eating habit in children and adolescents. Therefore additional research is necessary to confirm this study's findings.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.11 no.4
• /
• pp.302-306
• /
• 2001

Because face Images have many variations(expression, illumination, orientation of face, etc), there has been no popular method which has high recognition rate. To solve this difficulty, data fusion that fuses various information has been studied. But previous research for data fusion fused additional biological informationUingerplint, voice, del with face image. In this paper, cooperative results from several face image recognition modules are fused without using additional biological information. To fuse results from individual face image recognition modules, we use re-defined mass function based on Dempster-Shafer s fusion theory.Experimental results from fusing several face recognition modules are presented, to show that proposed fusion model has better performance than single face recognition module without using additional biological information.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.227-228
• /
• 2023

A floating floor generally consists of mortar bed separated from the structural RC slab by a continuous resilient layer. It is known that the floating floors are a type of vibration-isolation system to improve the impact sound insulation performance. However, some researchers have demonstrated that the amplification of vibration response at a specific range of frequencies results in an increase in the impact sound level. This study carried out the forced vibration tests to obtain the frequency response function (FRF) of a floating floor compared with a bare RC slab. Test results shows that the additional peak occur in vibrational spectrum of the floating floor except natural vibration modes of the bare RC slab. This is because the relatively flexible resilient material and mass of the mortar bed offer an additional degree of freedom in the structural system. Therefore, it could be efficient for reduction of floor impact vibration and noise to control the additional mode frequency and response of floating floors.

• Publications of The Korean Astronomical Society
• /
• v.14 no.1
• /
• pp.9-22
• /
• 1999

Current searches for gravitational microlensing events are being carried out only by a photometric method. In this review paper, we demonstrate that the nature of Galactic lenses can be significantly better constrained with the additional astrometric observations of microlensng events. First, by astromerically observing lensing events, one can resolve the lens parameter degeneracy, and thus the lens mass can be determined with improved precision. Second, by being free from the blending problem, astrometric observations of lensing events will allow one to improve the uncertainties in the determined Einstein time scales. Third, the lens brightness, which could not be measured photometrically, can be measured from the astrometric observations of lensing events, and thus the nature of lens matter can be better constrained. Finally, with the help of astrometric followup observations of a binary-lens event, one can uniquely determine the solution of lens parameters, allowing one to obtain important astronomical information about the source star and the lens itself.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.43 no.6
• /
• pp.154-162
• /
• 2001

This study was performed to examine the rice growth and nutrient change in paddy soil with reclaimed sewage irrigation. Total nitrogen and total phosphorus in the experimental system were analyzed before and after rice culture. The experiment lasted three consecutive years, and this paper presents results of the last year. Additional supply of nutrients to the rice culture by reclaimed sewage irrigation was significant and it increased the yield. Nutrient uptake by rice plant increased with more nutrient supplied, however. there was limit in plant uptake. Nutrient accumulation occurred in the soil and it was more apparent for the phosphorus where most of the remaining quantity was accumulated while substantial amount of nitrogen was lost during the growing season. This study suggested that additional nutrient supply by reclaimed sewage irrigation might be a supplemental benefit to the rice culture, and it can help the fertilization management. However, long term effects of continual reclaimed sewage irrigation should be assessed carefully including nutrient mass balance in the paddy rice culture system.