• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.8
• /
• pp.657-664
• /
• 2013

The flight loads analysis was carried out on the aircraft with high aspect ratio flexible wings by using commercial software MSC/NASTRAN. The aerodynamic model for flight loads analysis was corrected, compared with results of the wind tunnel test. And in-house program was developed for pre and post works. In-house program enabling management of much data automatically consists of three modules: 'Construction of the mass distributed model', 'Selection of critical load cases', 'Generation of external loads for structural design'. By utilizing these techniques and programs, the procedure of flight loads analysis was established for effective development of an aircraft.

• International Journal of Aeronautical and Space Sciences
• /
• v.12 no.1
• /
• pp.43-56
• /
• 2011

An integrated system composed of guidance, navigation and control (GNC) system for autonomous proximity operations and the docking of two spacecraft was developed. The position maneuvers were determined through the integration of the state-dependent Riccati equation formulated from nonlinear relative motion dynamics and relative navigation using rendezvous laser vision (Lidar) and a vision sensor system. In the vision sensor system, a switch between sensors was made along the approach phase in order to provide continuously effective navigation. As an extension of the rendezvous laser vision system, an automated terminal guidance scheme based on the Clohessy-Wiltshire state transition matrix was used to formulate a "V-bar hopping approach" reference trajectory. A proximity operations strategy was then adapted from the approach strategy used with the automated transfer vehicle. The attitude maneuvers, determined from a linear quadratic Gaussian-type control including quaternion based attitude estimation using star trackers or a vision sensor system, provided precise attitude control and robustness under uncertainties in the moments of inertia and external disturbances. These functions were then integrated into an autonomous GNC system that can perform proximity operations and meet all conditions for successful docking. A six-degree of freedom simulation was used to demonstrate the effectiveness of the integrated system.

• Wind and Structures
• /
• v.7 no.4
• /
• pp.265-280
• /
• 2004

This paper presents some fundamental results on the dynamics of the periodic Karman wake behind a circular cylinder. The wake is treated like a dynamical system. External forcing is then introduced and its effect investigated. The main result obtained is the following. Perturbation of the wake, by controlled cylinder oscillations in the flow direction at a frequency equal to the Karman vortex shedding frequency, leads to instability of the Karman vortex structure. The resulting wake structure oscillates at half the original Karman vortex shedding frequency. For higher frequency excitation the primary pattern involves symmetry breaking of the initially shed symmetric vortex pairs. The Karman shedding phenomenon can be modeled by a nonlinear oscillator. The symmetrical flow perturbations resulting from the periodic cylinder excitation can also be similarly represented by a nonlinear oscillator. The oscillators represent two flow modes. By considering these two nonlinear oscillators, one having inline shedding symmetry and the other having the Karman wake spatio-temporal symmetry, the possible symmetries of subsequent flow perturbations resulting from the modal interaction are determined. A theoretical analysis based on symmetry (group) theory is presented. The analysis confirms the occurrence of a period-doubling instability, which is responsible for the frequency halving phenomenon observed in the experiments. Finally it is remarked that the present findings have important implications for vortex shedding control. Perturbations in the inflow direction introduce 'control' of the Karman wake by inducing a bifurcation which forces the transfer of energy to a lower frequency which is far from the original Karman frequency.

• Smart Structures and Systems
• /
• v.3 no.3
• /
• pp.385-403
• /
• 2007

The effectiveness of the newly developed smart passive control system employing a magnetorheological (MR) damper and an electromagnetic induction (EMI) part for seismic protection of base isolated structures is numerically investigated. An EMI part in the system consists of a permanent magnet and a coil, which changes the kinetic energy of the deformation of an MR damper into the electric energy (i.e. the induced current) according to the Faraday's law of electromagnetic induction. In the smart passive control system, the damping characteristics of an MR damper are varied with the current input generated from an EMI part. Hence, it does not need any control system consisting of sensors, a controller and an external power source. This makes the system much simpler as well as more economic. To verify the efficacy of the smart passive control system, a series of numerical simulations are carried out by considering the benchmark base isolated structure control problems. The numerical simulation results show that the smart passive control system has the comparable control performance to the conventional MR damper-based semiactive control system. Therefore, the smart passive control system could be considered as one of the promising control devices for seismic protection of seismically excited base isolated structures.

• Wind and Structures
• /
• v.26 no.1
• /
• pp.1-9
• /
• 2018

This research studies the dynamic analysis of a concrete column reinforced with titanium dioxide ($TiO_2$) nanoparticles under earthquake load. The effect of nanoparticles accumulation in a region of concrete column is examined using Mori-Tanaka model. The structure is simulated mathematically based on the theory of sinusoidal shear deformation theory (SSDT). By calculating strain-displacement and stress-strain relations, the system energies include potential energy, kinetic energy, and external works are derived. Then, using the Hamilton's principle, the governing equations for the structure are extracted. Using these equations, the response of the concrete column under earthquake load is investigated using the numerical methods of differential quadrature (DQ) and Newark. The purpose of this study is to study the effects of percentage of nanoparticles, nanoparticles agglomeration, geometric parameters and boundary conditions on the dynamic response of the structure. The results indicate that by increasing the volume percent of $TiO_2$ nanoparticles, the maximum dynamic deflection of the structure decreases.

• Journal of the Korean Institute of Oriental Medical Informatics
• /
• v.17 no.1
• /
• pp.257-293
• /
• 2011

"Byun Jeung Rok(辨證錄)" written by Jinsatak(陳士鐸) is composed of 14 volumes. In relation to the contents, it is organized into 126 gates(門) and 770 remaining syndromes(餘證) where internal medicine, external medicine, pediatrics, gynecology(內科 外科 小兒 婦人), etc. are divided into sub-sections of cold damage, cold stroke, wind stroke(傷寒 中寒 中風), etc. He explained the symptom, cause of disease, method of treatment, prescription, construction of prescription, instruction of medicine and prognosis(症狀 病因 治法 處方 處方構成 服用法 預後) thoroughly. This study, as an inquiry of the sec 14 volume pediatrics(小兒), deals with febrile fit cacotrophy vomiting diarrhea(驚疳吐瀉), coprozoic parasite(便蟲), smallpox(痘瘡), eruption(疹症), eating mud(喫泥), fetal toxin(胎毒). It was written very logically so it is easy to understand. The analysis of the symptoms are brief and appropriate. Therefore, it is considered to have significant clinical value for future generations and is applied by them. Finally, this topic was studied in hopes of helping later pediatrics clinical treatment.

• Journal of Haehwa Medicine
• /
• v.22 no.1
• /
• pp.91-104
• /
• 2013

Objective : This study was designed to analyze the clinical studies on Tic disorder in traditional Korean medicine and traditional Chinese medicine. Methods : To figure out the Tic disorder, Korean medical studies from Oriental Medicine Advanced Searching Integrated System (OASIS) and Chinese Medical Journals from Wangfang data and China National Knowledge Infrastructure (CNKI) which published in 2008 to 2012 were analyzed. Results & Conclusions : 1. DSM-IV(7 studies), CCMD(3 studies) were frequently used in the diagnosis of tic disorder. 2. The herbs used for the treatment of tic disorder are Uncariae ramulus et Uncus(釣鉤藤), Paeoniae Radix Alba(白芍藥), Poria(白茯苓), Buthus martensi Karsch(全蝎) etc. 3. Acupuncture points frequently used were Paek'oe(GV20), Pungji(GB20), Naegwan(PC6), Sasinchong(EX-HN1), T'aech'ung(LR3), Joksamni(ST36), Hapgok(LI4) and so on. 4. The cause of Tic disorder is connected with liver, heart, spleen, kidney, gall bladder among the internal organs and Fire(火), Wind(風), Dampness(濕) of external causes.

• Journal of Korean Association for Spatial Structures
• /
• v.5 no.4 s.18
• /
• pp.79-90
• /
• 2005

The purpose of this study is development of a finite element algorithm to find out the stressed condition, slipped direction and slipped dimension when some elements of cable-membrane structures are slipped from it's initially designed coordinates by external loads as wind or non uniform load and so on. In order to search the slipped behaviors of cable-membrane structures, a Arbitrarily-Lagrangian-Eulerian(ALE) finite element formulation is introduced. In these procedures, a stiffness matrix related with ALE concept is formulated and a FE analysis program for cable-membrane structures with slipped elements is developed. Various examples for cable and membrane structures are presented to verify the program's validation. The results are shown good agreement with that of existed one.

• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.337-344
• /
• 2012

Today, the number of super tall buildings are under construction or being planed in Middle East and Asian Countries. For example the burj Khalifa, the tallest building in the world, is completed in 2008 and the height of that is about 800m. Also, Lotte World Tower is under construction in Korea. External environmental conditions such as wind speed, air temperature, humidity and solar radiation around the super tall building differs according to the building height due to the vertical micro climate change. However, the meteorological information used for AC design of building is obtained typically from standard surface meterological station data(~2m above the ground). In this paper the effect of the building envelope on heating and cooling load in super tall building considering the meteorological changes with height was analyzed with simulation method. As results of this research, the guideline to select the building envelop alternatives for super tall building will be suggested in this paper.

• Journal of the Semiconductor & Display Technology
• /
• v.9 no.1
• /
• pp.67-71
• /
• 2010

Head up display’s cooling system is auto-diagnosed resulting from the external environment. The quantity of heat depending on this Head up display’s cooling system layout determines the speed of FAN for system cooling. In other words, a system’s heat quantity is planned through the air density depending on altitude, the amount of wind in air depending on FAN control condition, and the algorithm that is proportional to delta temperature. To detect the altitude, we use the criteria of delta T, which is determined by the subtracted value of LED junction temperature, and atmospheric temperature that is recorded on the Head up display system. Depending on the classification of delta T value, the altitude section is determined. While we can use GPS as the tool to detect the altitude, we should predict the change of the air density as the altitude alters, and should not just measure the altitude. And the value of delta T is used as the criterion of detecting the altitude for increasing the cooling efficiency of the car’s inner Head up display system with reflecting the speed of the FAN dependent upon the air density. In our theory, altitude is depending on the value of delta T and stabilizing or maintaining the system’s temperature by changing FAN’s rpm depending on determined value of altitude.