• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.205-210
• /
• 2004

The pulse detonation engine (PDE) has recently expected as a new aerospace propulsion system. The PDE system has high thermal efficiency because of its constant-volume combustion and its simple tube structure. We measured thrust of single-tube pulse detonation rocket (PDR) by two methods using the PDR-Engineering Model (full scale model) for ground testing. The first involved measuring the displacement of the PDR-EM by laser displacement meter, and the second involved measuring the time-averaged thrust by combining a load cell and a spring-damper system. From these two measurements, we obtained 130.1 N of time-averaged thrust, which corresponds to 321.2 sec of effective specific impulse (ISP). As well, we measured the heat flux in the wall of PDE tubes. The heat flux was approximately 400 ㎾/$m^2$. We constructed the PDR-Flight Mode] (PDR-FM). In the vertical flight test in a laboratory, the PDR-FM was flying and keeping its altitude almost constant during 0.3 sec.

• Smart Structures and Systems
• /
• v.2 no.4
• /
• pp.321-328
• /
• 2006

The paper describes the testing facilities and the methodology on testing of laminated rubber bearings envisaged for application in the system of Dynamic Damper (DD) of seismic isolated buildings, as well as the obtained results. For the first time in Armenia laminated rubber bearings were tested simultaneously under the action of horizontal shear force and vertical tension force. The test results have proven the possibility of using rubber bearings as elements subjected to tension due to action of the mass of DD. Also it was confirmed that the suggested structural concept of DD for reducing the displacements and shear forces of seismic isolation systems will have reliable behavior during the design level earthquakes.

• Journal of the Korean Solar Energy Society
• /
• v.24 no.3
• /
• pp.1-7
• /
• 2004

Using WAsP, which is PC-program for the vertical and horizontal extrapolation of wind data, annual energy production as well as wind energy density has been predicted for Haengwon wind farm in Jeju island. The predicted results were compared with real data derived from wind turbines in Haengwon wind farm. As the results, in order to produce more electric power, new wind turbines should be located along coastal line, which has comparatively high wind energy density. Also, the roughness length should be inputted to the Map Editor program for better agreement with real annual energy production.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.3
• /
• pp.700-714
• /
• 2014

This study aims to identify the relations between seakeeping characteristics and hull form parameters for YTU Gulet series with cruiser stern. Seakeeping analyses are carried out by means of a computer software which is based on the strip theory and statistical short term response prediction method. Multiple regression analysis is used for numerical assessment through a computer software. RMS heave-pitch motions and absolute vertical accelerations on passenger saloon for Sea State 3 at head waves are investigated for this purpose. It is well known that while ship weight and the ratios of main dimensions are the primary factors on ship motions, other hull form parameters ($C_P$, $C_{WP}$, $C_{VP}$, etc.) are the secondary factors. In this study, to have an idea of geometric properties on ship motions of gulets three different regression models are developed. The obtained outcomes provide practical predictions of seakeeping behavior of gulets with a high level of accuracy that would be useful during the concept design stage.

• Journal of the Korean Society for Railway
• /
• v.7 no.4
• /
• pp.391-399
• /
• 2004

This paper investigated the dispersion characteristics of horizontal surface waves as means to apply conversional SASW techniques. To verify this proposal, 3D finite element analysis and Transfer matrix solution were performed. SH wave(Love waves) has the some advantages in comparison with Rayleigh wave. Representatively, Love wave has a characteristics not affected by compression wave. These characteristics have the robust applicability for the surface wave investigation techniques. In this study, for the purpose of employing Love wave in the SASW method, the dispersion characteristics of the Love wave was extensively investigated by the theoretical and numerical approaches. The 3-D finite element and transfer matrix analyses for the half space and two-layer systems were performed to determine the phase velocities from Love wave as well as from both the vertical and the horizontal components of Rayleigh wave. Preliminary, numerical simulations and theoretical solutions indicated that the dispersion characteristics of horizontal surface wave(Love waves) can be sufficiently sensitive and appliable to SASW techniques.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.109-112
• /
• 2006

In this study, an approach that installs seismic isolation bearings was proposed for the seismic retrofit of the existing bridges. The method that replaces all existing bearings with seismic isolators was proposed already. However, in this study, we recommend to utilize the existing bearings for the benefit of safety and cost. According to our proposal, the seismic isolators do not support vertical loads but they just function as the period shifter and the horizontal damper. To verify this approach experimentally, the real scale bearings and isolators for the real highway bridges were designed and fabricated. And the responses of this isolated bridges to the assumed earthquakes were determined by the pseudo dynamic test scheme. The test results were also compared to the responses computed by the well known structural analysis software to check the reliability of the test. From the test results, we found that the retrofitted bridges using the proposed method showed stable performances under earthquakes.

• Journal of Environmental Science International
• /
• v.8 no.5
• /
• pp.555-558
• /
• 1999

A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 km, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind filed should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.8B
• /
• pp.1159-1169
• /
• 2010

This paper introduces the mobility-adaptive QoE provisioning solution. The key is placed on the intelligent selection of access network depending on the QoE criteria classified by the user mobility and the bandwidth demand for service. We further focus on the network-based smart handover scheme using the mobility-adaptive handover decision and the enhanced MIH-FMIP framework. The concept is the network-based calm service and the balance in order to facilitate vertical and seamless handover. In result, it is figured out that our solution improves QoE performance by selecting appropriate access network, repressing handover occurrence, and reducing handover delay as well.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.5A
• /
• pp.487-493
• /
• 2008

In this paper, we consider coded layered space-time architecture in MIMO-OFDM channels. Vertical Bell Lab Layered Space-Time(V-BLAST) scheme employing ordered successive interference cancellation(OSIC) algorithm provides very high spectral efficiency with low computational complexity. However, the error propagation is a major drawback constraining the overall performance of the V-BLAST system significantly. Based on this problem, we derive an improved detector using soft bit log-likelihood ratio(LLR) value. Simulation results show that the proposed detector outperforms the conventional V-BLAST scheme under spatially uncorrelated as well as correlated fading channels.

• Restorative Dentistry and Endodontics
• /
• v.39 no.1
• /
• pp.56-62
• /
• 2014

A tooth with primary endodontic disease that demonstrates a periodontal defect might be extracted because of misdiagnosis as severe periodontal disease or a vertical root fracture. The aim of this case report was to demonstrate the long-term survival of endodontically treated teeth, which had been initially considered unsavable. With meticulous evaluation including the patient's dental history, clinical and radiographic examinations, teeth with primary endodontic lesions could be differentiated and saved after proper root canal treatment. Pain history, vitality test, and radiographic examinations, as well as a general periodontal condition check with periodontal probing on an affected tooth, might be the key methods to differentiate endodontic pathosis from that of periodontal disease.