• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.51.2-51.2
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• 2015

Gravitational lensed quasar systems are usually explained by a source quasar lensed by a galaxy that can be approximated by an isothermal sphere. But most galaxies have a supermassive black hole (SMBH) at its center. We study the lensing by an isothermal sphere with a central SMBH. The additional lensing effects of a SMBH on the number, position, and magnification of lensed images are investigated. We apply the analysis to observed lens systems including Q0957+561. We also study the lensing by an elliptical mass distribution with a SMBH.

• Journal of Chest Surgery
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• v.25 no.10
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• pp.1116-1120
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• 1992

Posterior mediastinal goiter extending to carotid sheath posteriorly is rare repoted case. Recently we experienced huge posterior mediastinal goiter with compressin of trachea in 57-year old male, The patient that complained of dyspnea referred to our hospital for further evaluation of mediasitnal tumor. We confirmed huge secondary posterior mediastinal intrathoracic goiter with diagnostic methods following by chest X-ray, thyroid scan, chest CT, and CT guided fine needle aspiration biopsy in this patient, and performed operation for excision Exision of posterior mediasitnal goiter performed through initial transeverse cervical incision and additional median sternotomy, and the mass removed completely without any complications. The postoperative course were uneventful.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.292-299
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• 1999

In order to investigate dynamic behaviors of marine cables under wave and earthquake forces a geometric nonlinear. F, E formulation of marine cables is presented and tangent stiffness and mass matrices for the isoparametric cable element are derived, The initial equilibrium state of cables subjected to self -weights and current forces is determined and free vibration and dynamic nonlinear analysis of cable structures under additional environmental loads are performed based on the initial configuration Challenging examples are presented and discussed in order to demonstrate the feasibility of the present finite element method and investigate dynamic nonlinear behaviors of marine cables.

• Journal of Korean Medicine for Obesity Research
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• v.16 no.1
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• pp.50-63
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• 2016

Objectives: The aim of this study is to analyze methods and outcomes about fasting for obesity in korea medicine research. Methods: We searched the studies with key words of 'obesity' and 'fasting or starvation' in Korean database (Korean traditional knowledge portal, OASIS, KISS, KMBASE, DBPIA, RISS). Studies were analyzed for contents, evaluation methods and adverse effects. Results: Twenty-one studies were reviewed. Studies were published in 1983~2015. 1. Studies can be classified into three types: comparative study on before and after, comparative study between groups, case study on other disease occurred during the fasting therapy period. 2. The most common step of fasting were 3 steps: reducing food intakes period (3~5 days), fasting period (7~10 days) and refeeding period (3~5 days) and additional period-diet period (28 days). 3. The most common evaluation methods were body weight (BW), body fat mass (BFM), muscle weight (MW), fat free mass, body mass index, body fat percentage, etc. 4. BW, BFM, MW were reduced largely in fasting period. 5. The most common adverse effects were fatigue, nausea, headache, vomiting, insomnia, etc. Conclusions: As a result of the review papers, fasting therapy have positive effects for obesity. To verify the effectiveness of the fasting, more studies are needed such as randomized controlled trial.

• Korean Journal of Head & Neck Oncology
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• v.12 no.1
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• pp.43-46
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• 1996

An unusual case of nodal metastases from thyroid neoplasm known as parapharyngeal space mass is likely to be overlooked. And identification of the primary lesion by excisional biopsy calls for a secondary operation. Therefore, it is important to be aware of the possible lymphatic spread of the thyroid neoplasm to the parapharyngeal space. In this case, completion thyroidectomy should be considered. Here, we present a case of thyroid papillary carcinoma masquerading as a parapharyngeal space tumor. The mass was removed by transcervical approach and pathologically diagnosed as a metastatic thyroid papillary carcinoma. Successful results were obtained after additional completion thyroidectomy.

• Earthquakes and Structures
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• v.9 no.1
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• pp.145-171
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• 2015

Due to earthquakes, many structures suffered extensive damages that were attributed to the torsional effect caused by mass, stiffness or strength eccentricity. Due to this type of asymmetry torsional moments are generated that are imposed by means of additional shear forces developed at the vertical resisting structural elements of the buildings. Although the torsional effect on the response of reinforced concrete buildings was the subject of extensive research over the last decades, a quantitative index measuring the amplification of the shear forces developed at the vertical resisting elements due to lateral-torsional coupling valid for both elastic and elastoplastic response states is still missing. In this study a reliable index capable of assessing the torsional effect is proposed. The performance of the proposed index is evaluated and its correlation with structural response quantities like displacements, interstorey drift, base torque, shear forces and upper diaphragm's rotation is presented. Torsionally stiff, mass eccentric single-story and multistory structures, subjected to bidirectional excitation, are considered and nonlinear dynamic analyses are performed using natural records selected for three hazard levels. It was found that the proposed index provides reliable prediction of the magnitude of torsional effect for all test examples considered.

• Smart Structures and Systems
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• v.15 no.6
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• pp.1625-1642
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• 2015

We propose an electrically self-reliant structural health monitoring (SHM) system that is able to wirelessly transmit sensing data using electrical power generated by vibration without the need for additional external power sources. The provision of reliable electricity to wireless SHM systems is a highly important issue that has often been ignored, and to expand the applicability of various wireless SHM innovations, it will be necessary to develop comprehensive wireless SHM devices including stable electricity sources. In light of this need, we propose a new, highly efficient vibration-powered generator based on a tuned-mass-damper (TMD) mechanism that is quite suitable for vibration-based SHM. The charging time of the TMD generator is shorter than that of conventional generators based on the impedance matching method, and the proposed TMD generator can harvest 16 times the amount of energy that a conventional generator can. The charging time of an SHM wireless transmitter is quantitatively formulated. We conduct wireless monitoring experiments to validate a wireless SHM system composed of a self-reliant SHM and a vibration-powered TMD generator.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.15-23
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• 2010

To reduce the vibration levels, additional dissipation elements such as dry friction dampers are sometimes integrated into bladed disk assembly. In this study, forced response analysis systems for a tuned bladed disk with friction dampers were developed and verified. For the efficient nonlinear vibration analysis, multi-harmonic balanced method and cyclic boundary condition were used. Also, mode shapes obtained using fictitious mass method were used to describe the motion of the structures with the concentrated structural nonlinearity, friction damper. The relative convergence of fictitious mass and traditional unconstrained modes were compared.

• Mass Spectrometry Letters
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• v.5 no.4
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• pp.120-123
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• 2014

The interference of water vapor on the chemical ionization (CI) of hydroxyl radicals (OH) by sulfur hexafluoride ion ($SF_6{^-}$) was investigated using a flow tube system coupled to a high-pressure CI mass spectrometer. Water vapor, which is required to study heterogeneous reactions of OH under real tropospheric conditions, transforms the reagent ion $SF_6{^-}$ into $SF_4O^-$ and $F^-(HF)_n$, resulting in a substantial loss in CI sensitivity. Therefore, under humid conditions, peaks corresponding to OH are drastically diminished, while those corresponding to OH-water complex ions ($[OH(H_2O)_n]^-$) are enhanced. $[OH(H_2O)_3]^-$ was observed as the major OH species. The obsercation of $[OH(H_2O)_n]^-$ by isolating humid conditions to the CI region and preliminary ab initio calculations suggested that $[OH(H_2O)_n]^-$ ions were produced from reactions between OH ions ($OH^-$) and water molecules. An additional helium buffer flow introduced into the CI region reduced loss of the reagent ion and resulted in a partial recovery of OH peak intensities under humid conditions.

• International Journal of Aeronautical and Space Sciences
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• v.5 no.2
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• pp.54-61
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• 2004

In this paper we carried out a design study for an unmanned Mars missionsuitable for Republic of Korea. The mission will use a KSLV series launch system,which is to place a one tonne payload into the LEO. We calculated the velocityincrements(AV) required for departure from Earth and insertion into the orbitaround Mars based on the mission opportunity data provided by NASA. Two typesof Mars modules - entry type and orbiter type - were considered in this studyWe calculated the mass of TPS(therma1 protection system) for the entry tvpe Marsmodule based on the heat transfer rate and heat load from the Mars atmosphere tothe surface of the TPS. The heat transfer rate and heat load were obtained throughan entry trajectory calculation. For the orbiter type Mars module, we calcuIated themass breakdown of the additional spacecraft which is to insert the Mars moduleinto the orbit around Mars. Other mass items were determined by proportioningfrom the existing Mars modules. This paper finally proposes the payload capacitiesfor each types of Mars modules.