• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.4
• /
• pp.383-391
• /
• 2009

The detonation wave characteristics of JP-7 and oxygen mixture is investigated by one-step induction parameter model (IPM) obtained from a detailed chemistry mechanism. A general procedure of obtaining reliable one-step kinetics IPM for hydrocarbon mixture from the fully detailed chemistry is described in this study. The IPM is obtained by the reconstruction of the induction time database obtained from a detailed kinetics library. The IPM was confirmed by the comparison of the induction time calculations with that from detailed kinetics. The IPM is later implemented to a fluid dynamics code and applied for the numerical simulation of detonation wave propagation. The numerical results show the detailed characteristics of the detonation wave propagation in JP-7 and oxygen mixture at affordable computing time, which is not be possible by the direct application of the detailed chemical kinetics mechanism of hydrocarbon fuel combustion.

• Journal of the Korean Institute of Gas
• /
• v.20 no.3
• /
• pp.52-58
• /
• 2016

In this study, evaluation method for LNG plant FEED is suggested and its validity is confirmed using a well-known decision making technique of Analytic Hierarchy Process (AHP). It is a pairwise comparison technique which can be used when multiple options must be considered for a single decision making problem. In order to develop an objective decision methodology, various decision parameters, sub-parameters as well as the concept of scale of assessment were introduced, and its consistency among these parameters was also checked by calculating the consistency index (C.I.). The methodology suggested in this article will contribute in evaluation of LNG plant FEED with less bias and subjectivity associated with the decision making procedure.

• Journal of Korea Water Resources Association
• /
• v.46 no.6
• /
• pp.585-596
• /
• 2013

The objective of this study is to evaluate the hybrid downscaling method combined Step-Wise Scaling (SWS) method with Regional Climate Model (RCM) simulation data for climate change impact study on hydrology area. The SWS method is divided by 3 categories (extreme event, dry event and the others). The extreme events, wet-dry days and the others are corrected by using regression method, quantile mapping method, mean & variance scaling method. The application and evaluation of SWS method with 3 existing and popular statistical techniques (linear scaling method, quantile mapping method and weather generator method) were performed at the 61 weather stations. At the results, the accuracy of corrected simulation data by using SWS are higher than existing 3 statistical techniques. It is expected that the usability of SWS method will grow up on climate change study when the use of RCM simulation data are increasing.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.15 no.3
• /
• pp.57-64
• /
• 2011

In this study, a seismic performance evaluation of unreinforced masonry buildings was conducted based on a revised draft of the outline of the seismic performance evaluation of existing buildings. The procedure of the performance evaluation is composed of three-steps, which are a preliminary evaluation, a first-level detailed evaluation, and a second-level detailed evaluation, where evaluation is conservatively conducted in the beginning and then more detailed evaluations are gradually conducted. For the study, ten two-story unreinforced masonry buildings were selected and evaluated using the three-step evaluation. The result showed that the performance levels between the preliminary and the first-level detailed evaluations were reversed, which is different from the intent of the procedure. Therefore, in the near future, the problems in each evaluation step that are presented in the results of this study need to be refined.

• Journal of the Korea Computer Graphics Society
• /
• v.17 no.2
• /
• pp.1-9
• /
• 2011

In recent researches, several LOD techniques are used for real-time visualization of large sized terrain data. However, during mesh simplification, geometry popping may occur in consecutive frames, because of the geometric error. We propose an efficient method for reducing the geometry popping using roughness map and bias map. A roughness map and a bias map are used to move vertices of the terrain mesh to appropriate position where they minimize the geometry errors. A roughness map and a bias map are represented as a texture suitable for GPU processing. Moving vertices using bias map is processed on the GPU, so the high-speed visualization can be possible.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.6
• /
• pp.2840-2850
• /
• 2011

Programmers can use the Hardware-Software Co-Designing, in which they design a hardware system and software system simultaneously and then unify them, to design an embedded system. This study analyzes the problems of designing an embedded system and suggests applying the system-level design technique, which uses SpecC technology, as a solution to the problems. Also, it suggests systematic and concrete stepwise refinement by applying Refactoring technology in software engineering as a way to make the use of system-level stepwise refinement.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.43 no.1 s.307
• /
• pp.53-66
• /
• 2006

This paper proposes the combined image retrieval system that gives the same relevance as exhaustive search method while its performance can be considerably improved. This system is combined with two different retrieval methods and each gives the same results that full exhaustive search method does. Both of them are two-stage method. One uses condensation of feature vectors, and the other uses binary-tree clustering. These two methods extract the candidate images that always include correct answers at the first stage, and then filter out the incorrect images at the second stage. Inasmuch as these methods use equal algorithm, they can get the same result as full exhaustive search. The first method condenses the dimension of feature vectors, and it uses these condensed feature vectors to compute similarity of query and images in database. It can be found that there is an optimal condensation ratio which minimizes the overall retrieval time. The optimal ratio is applied to first stage of this method. Binary-tree clustering method, searching with recursive 2-means clustering, classifies each cluster dynamically with the same radius. For preserving relevance, its range of query has to be compensated at first stage. After candidate clusters were selected, final results are retrieved by computing similarities again at second stage. The proposed method is combined with above two methods. Because they are not dependent on each other, combined retrieval system can make a remarkable progress in performance.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2017.07a
• /
• pp.350-351
• /
• 2017

스마트폰과 같은 모바일 기기의 발달과 함께 사용자의 위치에 기반한 다양한 서비스가 출현하고 있다. 그중 사용자의 위치를 기준으로하는 길안내 서비스가 가장 대표적이다. GPS에 기반한 실외 중심의 길안내는 다양한 비콘과 WiFi 등의 기술과 함께 실내에서도 길안내 서비스가 가능하도록 해주고 있다. 하지만, 상기의 사용자 위치에 대한 길안내 서비스는 거리에 대한 인식 단계가 세밀하지 못하기에 해당거리별 상세 서비스가 어려운 것이 현실이다. 이에 본 논문에서는 기존 BLE 비콘의 Immediate, Near, Far의 3단계 거리인식을 6단계까지 확장하여 보다 상세한 안내가 가능한 실내 길안내 서비스를 제안한다. 또한 편의적 기능을 위해 목적지 입력 및 길안내가 음성에 기반하여 구동될 수 있도록 구현하였다.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.41 no.6
• /
• pp.13-22
• /
• 2004

This study proposes a risk analysis methodology for information system security management in which the complexity on the procedure that the existing risk analysis methodology is reduced to the least. The proposed risk analysis methodology is composed of 3 phases as follows: beforehand processing phase, counter measure setting phase, post processing phase. The basic risk analysis phase is a basic security management phase in which fixed items are checked when the information security system is not yet established or a means for the minimum security control is necessary for a short period of time. In the detailed risk analysis phase, elements of asset a vulnerability, and threat are analysed, and using a risk degree production table produced from these elements, the risk degree is classified into 13 cases. In regard to the risk, the 13 types of risk degree will execute physical, administrative, and technical measures through ways such as accepting, rejecting, reducing, and transferring. Also, an evaluation on a remaining risk of information system is performed through a penetration test, and security policy set up and post management phase is to be carried out.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.857-862
• /
• 2011

3 dimensional turbine exhaust gas flow was simplified to an axisymmetrical flow and calculated with detailed chemistry models. GRI 35 species-217 reaction step model and simplified 11 species 15 reaction model was applied to the secondary reaction of the turbine exhaust gas and compared. All the model captured the secondary combustion on the base region, and the temperature was 600K higher than that without turbine exhaust gas. This means the local temperature of the base can be higher in the case of real 3 dimensional flow. The simplified model show the similar results to the GRI detailed chemistry model although the former affected the engine plume structure slightly.