• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.437-443
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• 2014

Engine is one of the most important parts in a rocket for completing its mission successfully. In this paper, we provide a methodology for estimating reliability and development cost of a liquid rocket engine newly developed. To estimate reliability, a baseline engine is selected considering factors whose effects on reliability are unquantifiable. Then reliability of a baseline engine is adjusted to reflect the effect of factors that can be modeled quantitatively. Using the previous Transcost engine cost expressed in terms of mass and the number of hot firing tests, the engine development cost is reexpressed in reliability and thrust requirements. Finally, a numerical example is given to illustrate the application of the methodology to a turbopump rocket engine using staged combustion cycle with LOX/LH2 propellant.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.5
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• pp.108-122
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• 2001

As bridge design is advancing toward the performance-based design. it becomes increasingly important to monitor and re-evaluate the long-term structural performance of bridges. Such information is essential in developing performance criteria for design. In this research. sensor systems for long-term structural performance monitoring have been installed on two highway bridges. Pre1iminary vibration measurement and data analysis have been performed on these instrumented bridges. On one bridge, ambient vibration data have been collected. based on which natural frequencies and mode shapes have been extracted using various methods and compared with those obtained by the preliminary finite element analysis. On the other bridge, braking and bumping vibration tests have been carried out using a water truck In addition to ambient vibration tests. Natural frequencies and mode shapes have been derived and the results by the breaking and bumping vibration tests have been compared. For the development of a three dimensional baseline finite element model, the new methodology using a neural network is proposed. The proposed one have been verified and applied to develop the baseline model of the bridge.

• Communications for Statistical Applications and Methods
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• v.27 no.2
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• pp.201-210
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• 2020

Baseline-category logit random effects models have been used to analyze longitudinal nominal data. The models account for subject-specific variations using random effects. However, the random effects covariance matrix in the models needs to explain subject-specific variations as well as serial correlations for nominal outcomes. In order to satisfy them, the covariance matrix must be heterogeneous and high-dimensional. However, it is difficult to estimate the random effects covariance matrix due to its high dimensionality and positive-definiteness. In this paper, we exploit the modified Cholesky decomposition to estimate the high-dimensional heterogeneous random effects covariance matrix. Bayesian methodology is proposed to estimate parameters of interest. The proposed methods are illustrated with real data from the McKinney Homeless Research Project.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.976-979
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• 2000

This paper describes a Life Cycle Engineering approach which is able to optimize a product under technical, ecological and economical requirements. The methodology of Life Cycle Engineering comes with a holistic approach for the analysis of processes, products, systems or services. The Life Cycle Engineering approach is combining environmental and economical parameters and using the technical requirements for setting the baseline for the studies. This paper also describes the approach method for ？ㄴ composed in large numbers sub-parts.

• Journal of computational fluids engineering
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• v.19 no.3
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• pp.62-68
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• 2014

The aerodynamic and noise calculations were performed through the CFD-CSD loose coupling methodology. In the loose coupling process, the trimmed rotor airloads were predicted by the in-house CFD code based on unstructured overset meshes, and the trim of the rotorcraft and the aeroelastic deformation of rotor blades were accounted with the CAMRAD II rotorcraft comprehensive code. The set of codes was used to analyze the HART-II baseline test condition. The effect of grid resolution and time step was examined and the loose coupling approach was found to be stable and convergent for the case. Comparison of the resulting sectional airloads, structural deformations, the noise carpets and the wake geometry with experimentally measured data was presented and showed the good agreement.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.2
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• pp.206-216
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• 2006

The primary purpose of this study is firstly, to ascertain the suitability of the IT BSC (balanced scorecard) methodology for the performance analysis of EGIS(environment geographic information system), secondly, to analyze the outcome of EGIS using the methodology, and finally to present guidelines for effectively managing the performance of EGIS. This study has rebuilt the IT BSC methodology based on the previous study on the performance analysis of GIS and EGIS whose performance over the past five years has been evaluated. According to the analysis, the integrated performance is estimated at 105.3 points. This figure indicates that the cumulative performance of EGIS is more than the baseline of goal, 100.0 points. The feature of this study is to develop a new methodology suitable for the EGIS performance analysis and to evaluate and quantify the total performance of EGIS objectively through the application of the new methodology.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.155-161
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• 2015

Dike lines are important features for describing the detailed shapes of dikes and for detecting topographic changes on dike surfaces. Historically, dike lines have been generated using only the LiDAR data. This paper proposes a new methodology for selecting an appropriate dike line on various dike surfaces using the topographic LiDAR data and multispectral orthoimages taken in the Nakdong River basins. The fi rst baselines were generated from the given LiDAR data using the modified convex hull algorithm and smoothing spline function, and the second baselines were generated from the given orthoimages by the Canny operator. Next, one baseline was selected among the two baselines at 10m intervals by comparing their elevations, and the selected baseline at 10m interval was defined as the dike line segment. Finally, the selected dike line segments were connected to construct the 3D dike lines. The statistical results show that the dike lines generated using both the LiDAR data and multispectral orthoimages had the improved horizontal and vertical accuracies than the dike lines generated only using the LiDAR data on the various dike surfaces.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.4
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• pp.141-146
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• 2020

The International Civil Aviation Organization (ICAO) developed Doc 9995 "Manual of Evidence-based Training," with the intention of providing guidance by establishing a new methodology for the development and conduct of a recurrent training and assessment program. The airline pilot training regulations were largely based on the evidence of hull losses from early generation jets, and in order to mitigate a risk, simply repeating an event in a training program was sufficient. At the time, studies concluded that it was time to change the paradigm of training and assessment program for pilots. One airline alone implemented Evidence-Based Training (EBT) program in their flight crew training and assessment program while another airline partially implemented the EBT program. In the regulatory framework of MOLIT, specific EBT regulations have not been established yet. Therefore, it is recommended to develop rules and standards that comply with ICAO SARPs as soon as possible. In this study we review the key steps in the implementation of the baseline EBT, approval process of baseline EBT program, and policy options regarding the implementation of EBT. It will provide guidance to operators, Approved Training Organizations (ATO), and stakeholders.

• CELLMED
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• v.13 no.14
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• pp.19.1-19.16
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• 2023

Objectives: To compare the efficacy of polyherbal Unani formulations in heavy menstrual bleeding due to endometrial hyperplasia. Methodology: A prospective, randomized comparative trial was conducted at Govt. Nizamia Tibbi College. Group A (n=20) received Itrifal Aftimoon 5g orally BID from menstruation day 3 to day 21 plus suprapubic Marham Dakhilyun application and per vaginally Marham Dakhilyun (5g) and Roghan Gul (10ml) application from menstruation day 5 to day 14. Group B (n=20) received Gulnar Farsi (2g), Phitakri Biryan (0.25g), Dammul Aqwain (0.25g), and Geru (2g), 2.5g powder orally BID, menstruation day 3 for 20 days plus Douche Bargh Sambhalu then Ḥamūl of Safuf Mazu (2g), Kalijiri (2g) and Roghan Gul (10ml) from menstruation day 3 to day 12 for 3 consecutive cycles. The primary outcome was pelvic ultrasound findings of endometrial thickness. The secondary outcome measures were improvement in haemoglobin percentage, change in menstrual flow and menstrual pattern. The level of significance was 5%. Results and conclusion: The intragroup comparison showed that the mean endometrial thickness at baseline and after treatment in groups A and B was extremely significantly different (P<0.0001). The intragroup comparison showed the mean haemoglobin percent at baseline and after treatment in group, A was significantly different (P<0.0001). After treatment, 50% and 60% of participants had normal duration and menstrual blood loss after treatment from baseline in Groups A and B respectively. However, further, phase II and III randomized standard controlled trials in larger samples are recommended to assess the efficacy of these group medicines.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.79-91
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• 2006

A new methodology of guided wave based nondestructive testing (NDT) is developed to detect crack damage in civil infrastructures such as steel bridges without using prior baseline data. In conventional guided wave based techniques, damage is often identified by comparing the "current" data obtained from a potentially damaged condition of a structure with the "past" baseline data collected at the pristine condition of the structure. However, it has been reported that this type of pattern comparison with the baseline data can lead to increased false alarms due to its susceptibility to varying operational and environmental conditions of the structure. To develop a more robust damage diagnosis technique, a new concept of NDT is conceived so that cracks can be detected without direct comparison with previously obtained baseline data. The proposed NDT technique utilizes the polarization characteristics of the piezoelectric wafers attached on the both sides of the thin metal structure. Crack formation creates Lamb wave mode conversion due to a sudden change in the thickness of the structure. Then, the proposed technique instantly detects the appearance of the crack by extracting this mode conversion from the measured Lamb waves even at the presence of changing operational and environmental conditions. Numerical and experimental results are presented to demonstrate the applicability of the proposed technique to crack detection.