• Title/Summary/Keyword: Additional Mass

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MOGA-Based Structural Design Method for Diagrid Structural Control System Subjected to Wind and Earthquake Loads

  • Kim, Hyun-Su;Kang, Joo-Won
    • International journal of steel structures
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    • v.18 no.5
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    • pp.1598-1606
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    • 2018
  • An integrated optimal structural design method for a diagrid structure and control device was developed. A multi-objective genetic algorithm was used and a 60-story diagrid building structure was developed as an example structure. Artificial wind and earthquake loads were generated to assess the wind-induced and seismic responses. A smart tuned mass damper (TMD) was used as a structural control system and an MR (magnetorheological) damper was employed to develop a smart TMD (STMD). The multi-objective genetic algorithm used five objectives including a reduction of the dynamic responses, additional stiffness and damping, mass of STMD, capacity of the MR damper for the integrated optimization of a diagrid structure and a STMD. From the proposed method, integrated optimal designs for the diagrid structure and STMD were obtained. The numerical simulation also showed that the STMD provided good control performance for reducing the wind-induced and seismic responses of a tall diagrid building structure.

On the Influence of the Moment of Inertia of Gas on the Galactic Rotation Curves

  • Portnov, Yuriy A.
    • Journal of Astronomy and Space Sciences
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    • v.39 no.3
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    • pp.99-108
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    • 2022
  • There are two models that explain the rotation curves of galaxies: dark matter, which gives the missing contribution to the gravitational potential of the standard theory of gravity, and modified theories of gravity, according to which the gravitational potential is created by ordinary visible mass. Both models have some disadvantages. The article offers a new look at the problem of galactic rotation curves. The author suggests that the moment of inertia creates an additional gravitational potential along with the mass. The numerical simulation carried out on the example of fourteen galaxies confirms the validity of such an assumption. This approach makes it possible to explain the constancy of gas velocities outside the galactic disk without involving the hypothesis of the existence of dark matter. At the same time, the proposed approach lacks the disadvantages of modified theories of gravity, where the gravitational potential is created only by the mass of visible matter.

Characterization of in vitro Metabolites of Methylenedioxy Designer Drugs

  • Jun Sang Yu;So Young Jo;Il-Ho Park;Hye Hyun Yoo
    • Mass Spectrometry Letters
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    • v.14 no.1
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    • pp.1-8
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    • 2023
  • Eutylone, dibutylone, and dimethylone are potential psychotropic designer drugs. The purpose of this study was to investigate the in vitro metabolic pathways of synthetic cathinones with methylenedioxy groups. The three methylenedioxy derivatives were incubated with human liver microsomes. The metabolites were characterized based on liquid chromatography and quadrupole-time-of-flight mass spectrometry. Eutylone, dibutylone, and dimethylone were metabolized to yield three, six, and four metabolites, respectively. Reduction and demethylenation were the major metabolic pathways for all three drugs tested. However, dibutylone and dimethylone showed an additional metabolite generated via N-oxidation. These results provide evidence for the in vivo metabolism of methylenedioxy synthetic cathinones, and could be applied to the analysis of synthetic cathinones and their relevant metabolites in biological samples.

Distant Quasars: Black hole mass growth and dust emission

  • Jun, Hyunsung D.
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.1
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    • pp.43.2-43.2
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    • 2015
  • The massive limit of black holes (BHs) is observed as present day ten billion solar masses. We search for observational signatures of BHs that become extremely massive (EMBHs, 1-10 billion solar masses). I will report on the evolution of active galactic nuclei (AGNs) through the growth of BH mass and their dust emission strength. First, we measured 26 EMBH masses of quasars at 1

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Optimum tuned mass damper design for preventing brittle fracture of RC buildings

  • Nigdeli, Sinan Melih;Bekdas, Gebrail
    • Smart Structures and Systems
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    • v.12 no.2
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    • pp.137-155
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    • 2013
  • Brittle fracture of structures excited by earthquakes can be prevented by adding a tuned mass damper (TMD). This TMD must be optimum and suitable to the physical conditions of the structure. Compressive strength of concrete is an important factor for brittle fracture. The application of a TMD to structures with low compressive strength of concrete may not be possible if the weight of the TMD is too much. A heavy TMD is dangerous for these structures because of insufficient axial force capacity of structure. For the preventing brittle fracture, the damping ratio of the TMD must be sufficient to reduce maximum shear forces below the values proposed in design regulations. Using the formulas for frequency and damping ratio related to a preselected mass, this objective can be only achieved by increasing the mass of the TMD. By using a metaheuristic method, the optimum parameters can be searched in a specific limit. In this study, Harmony Search (HS) is employed to find optimum TMD parameters for preventing brittle fracture by reducing shear force in additional to other time and frequency responses. The proposed method is feasible for the retrofit of weak structures with insufficient compressive strength of concrete.

Clinical Features and Outcomes of Primary Omental Lipoma in a Dog

  • Song, Doo-Won;Lee, Ga-Won;Kang, Min-Hee;Kim, Hwi-Yool;Eom, Ki-Dong;Park, Hee-Myung
    • Journal of Veterinary Clinics
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    • v.36 no.5
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    • pp.271-273
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    • 2019
  • A 12-year-old intact male Cocker spaniel dog was presented for evaluation of lethargy and abdominal distension. Clinical examination revealed a round, palpable mass in the middle of the abdomen. Abdominal computed tomography showed a round soft tissue mass ($width{\times}height{\times}length$, $25{\times}13{\times}15cm^3$) without regional invasion and distant metastasis. Cytologic evaluation of the mass revealed adipose tissue-derived cells having vacuolated cytoplasm, indistinct borders, large nucleus and ropy chromatin pattern with variable sized lipid droplets. Complete surgical resection of the mass was performed and the mass was histopathologically diagnosed as primary omental lipoma. The dog has been recovered well without any additional clinical signs, and there was no relapse over the 8 months follow-up period. The clinical features and prognosis of the dog with primary omental adipocytic tumors have been described in this report.

Anthropometric and Body Compositional Measurements and Pregnancy Outcomes (임신부의 체위와 체조성 및 임신의 결과)

  • 이종임;임현숙;조영숙
    • Journal of Nutrition and Health
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    • v.31 no.6
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    • pp.1057-1065
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    • 1998
  • Anthropometric and body compositional changes and the outcomes of the pregnancies of 90 healthy Korean women were investigated in a longitudinal study. Their weight increased from 51.3$\pm$5.9kg to 65.1$\pm$7.8kg during their pregnancies. The total weight gain was 13.8$\pm$4.5kg, and therefore, weekly weight gain was 340$\pm$110g during the entire period of the pregnancy. The weight gain was composed of approximately 50-60% fat mass and 40-50% fat-free mass. Skinfold thicknesses, both of triceps and subscapular, increased during the pregnancies. The fat mass calculated from skinfold thickness and that measured with bioelectrical impedance analysis went on increasing during the pregnancies. Although there was a considerable difference with respect to the fat mass observed using the three methods, fat mass gain was 5.0-6.1kg and fat-free mass gain was 4.0-5.3kg from the first trimester to the third trimester of pregnancies. There were significant correlations between maternal anthropometric parameters and indices of pregnancy outcomes. Especially, the infant's birth weight was associated with maternal pre-pregnancy weight and weight gains during the pregnancies. The infant's birth length was related to the maternal weight observed at term(p<0.05) and weight gain during the entire pregnancies (p<0.05) . Neither increase of fat mass nor fat-free mass affected the outcomes of pregnancy. These results show that maternal weight gain during pregnancy is led by increments of approximately above 50% fat mass. The fat mass increase seems to be larger in central areas than in subcutaneous areas. Maternal weight gain during pregnancy, especially during late pregnancy, is a factor affecting the birth weight and length of infant. On the basis of the body compositional changes, it can be predicted that the additional energy requirement for pregnancy in Korean women is more than 200-230 MJ (64,500-76,250kca1). (Korean J Nutrition 31(6) : 1057-1065, 1998)

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Clinical and Computed Tomography Evaluation of Plate and Screw on the Cervical Lateral Mass : A Modified Magerl's Technique

  • Lee, Dong-Chan;Yoon, Seung-Hwan;Park, Hyung-Chun;Park, Jong-Oon;Hyun, Dong-Keun;Park, Heon-Seon
    • Journal of Korean Neurosurgical Society
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    • v.39 no.4
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    • pp.251-255
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    • 2006
  • Objective : To determine the clinical and radiological safety of 15 consecutive patients managed with plate and screw fixation systems applied to the cervical lateral mass. Methods : 15 patients who underwent posterior cervical and T1 arthrodesis were reviewed from Jan 2002 to Dec 2004. Posterior cervical screw and plate fixation was applied on the lateral mass of the cervical spine. The authors have tried lateral mass screw fixation using a modified Magerl's technique [$20^{\circ}$ lateral and $20{\sim}30^{\circ}$ rostral screw trajectory] under preliminary radiological study. The average patient age was $39.73^{\circ}{\pm}11.00\;years$, and the average follow-up period was $9.73^{\circ}{\pm}6.77\;months$. Computed tomography scans taken after surgery were reviewed to confirm the attempted screw trajectory correct and safety. Results : Three of 93 lateral mass screws were malpositioned but clinical damage was not noted. Two of 8 pedicle screws on the T1 vertebrae were not placed on the correct pedicle area. Screw and plate loosening was observed in one case but was not subjected to an additional procedure because of maintained screw position observed during follow-up periods. Conclusion : The results of this study indicate that lateral mass screw fixation using the Modified Magerl's technique on the cervical lateral mass may provide safe and effective application on the patients. In addition, the chance of incorrectly placed screws was higher in T1 pedicle screw fixation than in lateral mass screw fixation of the cervical area.

External Fixation of Retaining Ligament in Correction of Facial Disfigurement in Type-1 Neurofibromatosis Patients (유지 인대의 외부 고정을 통한 제1형 신경섬유종증 환자의 안면부 변형 교정)

  • Myung, Yu-Jin;Lee, Yoon-Ho
    • Archives of Plastic Surgery
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    • v.38 no.3
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    • pp.257-262
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    • 2011
  • Purpose: In neurofibromatosis patients, complete surgical excision of the mass is almost impossible and surgical treatment usually consists of multiple serial excisions that only result in a debulking effect. Remnant tumor mass has a gravitational effect on facial soft tissues that leads to sagging of skin and soft tissue, and eventually, facial disfigurement and asymmetry. The purpose of our surgical method is to perform soft tissue lifting with longer lasting effect with less surgical risk of damaging facial nerve and vessels. With external fixation using K-wire or surgical screw, the procedure only called for a short incision length and had additional adhesive properties that enabled anchoring of soft tissue in a lifted position for a longer postoperative period. Methods: A total of 5 neurofibromatosis patients (NF-1) visited our clinic for mass reduction and face lifting. The age of patients ranged from 13 to 42 (mean 28.8 years), and most patients had a long history of multiple excisions in the past. Face lifting was performed in 2 different areas, the periorbital area in 3 patients, and the midface in 2 patients. The materials used in fixation of retaining ligament were K-wire (n=3) and titanium screw (n=2). Results: Follow up period was from 5 month to 3 years and 1 month (mean=2 years and 1 month). All patients conveyed satisfaction with the results and no major complications were reported. The lifting effect lasted for as long as 3 years, and there were no complaints of relapse of soft tissue depression or sagging within the operated area. 1 patient (M/13) needed secondary k-wire insertion and additional mass excision in 1 year and 10 months postoperatively due to tumor growth. In two patients with K-wire fixation, mild dimpling and tenderness were observed in the follow up period, but in about 2 months postoperatively, dimpling was relieved and there was no need for removal of fixating material. Conclusion: Surgical lifting in neurofibromatosis patients can be challenging, for mass excision cannot be done completely and gravitational effect by residual mass can be persistent. External fixation of the retaining ligament in patients with neurofibromatosis can give satisfactory results-for incision length is relatively shorter, and the lifting effect can last longer compared to other various face lifting techniques.

Comparison of semi-active and passive tuned mass damper systems for vibration control of a wind turbine

  • Lalonde, Eric R.;Dai, Kaoshan;Bitsuamlak, Girma;Lu, Wensheng;Zhao, Zhi
    • Wind and Structures
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    • v.30 no.6
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    • pp.663-678
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    • 2020
  • Robust semi-active vibration control of wind turbines using tuned mass dampers (TMDs) is a promising technique. This study investigates a 1.5 megawatt wind turbine controlled by eight different types of tuned mass damper systems of equal mass: a passive TMD, a semi-active varying-spring TMD, a semi-active varying-damper TMD, a semi-active varying-damper-and-spring TMD, as well as these four damper systems paired with an additional smaller passive TMD near the mid-point of the tower. The mechanism and controllers for each of these TMD systems are explained, such as employing magnetorheological dampers for the varying-damper TMD cases. The turbine is modelled as a lumped-mass 3D finite element model. The uncontrolled and controlled turbines are subjected to loading and operational cases including service wind loads on operational turbines, seismic loading with service wind on operational turbines, and high-intensity storm wind loads on parked turbines. The displacement and acceleration responses of the tower at the first and second mode shape maxima were used as the performance indicators. Ultimately, it was found that while all the semi-active TMD systems outperformed the passive systems, it was the semi-active varying-damper-and-spring system that was found to be the most effective overall - capable of controlling vibrations about as effectively with only half the mass as a passive TMD. It was also shown that by reducing the mass of the TMD and adding a second smaller TMD below, the vibrations near the mid-point could be greatly reduced at the cost of slightly increased vibrations at the tower top.