• KIPS Transactions on Software and Data Engineering
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• v.2 no.11
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• pp.765-778
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• 2013

This paper proposes a test case generation method for Stateflow model using the extended RRT method. The RRT method which has been popularly used for planning paths for complex systems also shows a good performance for test case generation. However, it does not consider the test coverage which is important for test case generation. The proposed extension method hires the concept of test goal achievement to increase test coverage and drives RRT extension in the direction that increases the goal achievement. Considering the concept, a RRT distance metric, random node generation method and modified RRT extension algorithm are proposed. The effectiveness of proposed algorithm is compared with that of the typical RRT algorithm through the experiment using the practical automotive ECUs.

• The Korean Journal of Applied Statistics
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• v.24 no.3
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• pp.477-484
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• 2011

When an event of target variable is rare, a widespread strategy is to build a model on the sample that disproportionally over-represents the events, that is over-sampled. Using the data over-sampled from the original data set, the predicted values would be biased; however, it can be easily corrected to represent the population. In this study, we investigate into the relationship between the proportion of rare event on a data-mart and the model performance using real world data of a Korean credit card company. Also, we use the methods for adjusting of posterior probability for over-sampled data of the offset method and the weighted method. Finally, we compare the performance of the methods using real data sets.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.83-91
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• 2001

This paper proposes the Focused beamforming to estimate the location of target residing near to the observation platform in the underwater environment. The Focused beamforming technique provides the location of target by the coherent summation of a series of incident spherical waveforms considering distinct propagation delay times at the sensor array. But due to the movement of the observation platform and the variation of the underwater environment, the shape of the sensor array is no longer to be linear but it becomes distorted as the platform moves. Thus the Focused beamforming should be peformed regarding to the geometric shape variation at each time. To estimate the target location, the artificial image plane comprised of cells is constructed, and the delays are calculated from each cell where the target could be proximity to sensors for the coherent summation. After the coherent combining, the beam pattern can be obtained through the Focused beamforming on the image plane. Futhermore to compensate the variation of the shape of the sensor array, the paper utilizes the Nth-order polynomial approximation to estimate the shape of the sensor array obeying the water pulley modeling. Simulation results show the performance of the Focused beamforming for different frequency bands of the radiated signal.

• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.764-775
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• 2003

Previous works for the assured service in the Diffserv network have no sufficient consideration on the fairness of bandwidth share based on RTTs and the target rates of TCP flows. In this paper, in order to solve these problems, we propose a TRA3CM(Target rate and RTT Aware 3 Color Marking) mechanism. The TRA3CM mechanism provides three color marking and fair transmission rates among aggregate flows by considering RTT and target rate simultaneously. In case of higher target rate than bottleneck bandwidth, the TRA3CM mechanism is able to mitigate the RTT effect and provides fair transmission rates. In the results of comparing the performance among existing mechanisms and the TRA3CM, the TRA3CM mechanism was able to mitigate the RTT effect better than the former. The TRA3CM is shown to provide good performance for transmission rates proportional to various target rates.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.419-424
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• 2019

In this paper, we proposed an algorithm to estimate the desired target in wideband jamming signal environment. In order to suppress the jamming signal, we use the spatial time adaptive algorithm and QR decomposition to obtain the optimal weight. The spatial time adaptive algorithm of adaptive array antenna system multiplies the tap delay signal by a complex weight to obtain a weight. In order to minimize the power consumption because of the inverse matrix, optimal weight is obtained by using QR decomposition. Through simulation, we compare and analyze the performance of the proposed algorithm and the existing algorithm. In the target estimation of [-40o,0o,+40o], the proposed algorithm estimated all three targets, but the existing algorithm estimated only [0o] due to of the jamming signal. We prove that the proposed algorithm improves performance by removing the jamming signal and estimating the target accurately.

• Journal of the Korean GEO-environmental Society
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• v.18 no.12
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• pp.13-23
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• 2017

This paper discusses about the reinforcement materials and construction method in order to cope with roadbed settlement in operating railway. In Korea, concrete tracks have been introduced to urban railways, high-speed railways, and general railways, but some recently constructed concrete tracks have experienced roadbed settlements. Reinforcement of the railway roadbed is urgent task for safe operation of railway, but it is difficult to reinforce the roadbed and there are no case history of reinforcing railway roadbed under an operating railroad track. Therefore, in this study, the target performance level for roadbed reinforcement was determined, and infiltration and solidity injection efficiency were investigated for selected reinforcement materials. As a result of the study, it was found that the generally used reinforcement materials and methods for geotechnical works need to be improved for applying in railway roadbed reinforcement.

• The KIPS Transactions:PartD
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• v.12D no.3 s.99
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• pp.417-428
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• 2005

Today, IT organizations perform projects with vision related to marketing and financial profit. The objective of realizing the vision is to improve the project performing ability in terms of QCD. Organizations have made a lot of efforts to achieve this objective through process improvement. Large companies such as IBM, Ford, and GE have made over $80\%$ of success through business process re-engineering using information technology instead of business improvement effect by computers. It is important to collect, analyze and manage the data on performed projects to achieve the objective, but quantitative measurement is difficult as software is invisible and the effect and efficiency caused by process change are not visibly identified. Therefore, it is not easy to extract the strategy of improvement. This paper measures and analyzes the project performance, focusing on organizations' external effectiveness and internal efficiency (Qualify, Delivery, Cycle time, and Waste). Based on the measured project performance scores, an OT (Opportunity Tree) model was designed for optimizing the project performance. The process of design is as follows. First, meta data are derived from projects and analyzed by quantitative GQM(Goal-Question-Metric) questionnaire. Then, the project performance model is designed with the data obtained from the quantitative GQM questionnaire and organization's performance score for each area is calculated. The value is revised by integrating the measured scores by area vision weights from all stakeholders (CEO, middle-class managers, developer, investor, and custom). Through this, routes for improvement are presented and an optimized improvement method is suggested. Existing methods to improve software process have been highly effective in division of processes' but somewhat unsatisfactory in structural function to develop and systemically manage strategies by applying the processes to Projects. The proposed OT model provides a solution to this problem. The OT model is useful to provide an optimal improvement method in line with organization's goals and can reduce risks which may occur in the course of improving process if it is applied with proposed methods. In addition, satisfaction about the improvement strategy can be improved by obtaining input about vision weight from all stakeholders through the qualitative questionnaire and by reflecting it to the calculation. The OT is also useful to optimize the expansion of market and financial performance by controlling the ability of Quality, Delivery, Cycle time, and Waste.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.928-931
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• 2003

본 논문에서는 고속 광대역의 정보신호를 효율적으로 전송하기 위한 무선 LAN 채널환경에서 OFDM 전송방식을 사용할 때 반송파의 주파수 오프셋이 발생하는 동기 오차가 수신시스템에 미치는 영향으로 인한 수신 성능을 분석하였다. 성능개선 기법으로 Convolution Coding 기법을 적용함으로써 반송파 주파수 오프셋에 따른 성능 열화를 보상하였다. 성능 해석 결과, OFDM 시스템에서 주파수 오프셋이 커짐에 따라 성능이 열화됨을 알 수 있었고, (BER=$10^{-3}$)를 목표로 하는 경우 OFDM 시스템에 Convolution Coding 기법을 적용함으로써 성능 개선이 나타났지만 64QAM방식인 경우 주파수 오프셋 0.05, 0.1에서 주파수 오프셋에 의한 캐리어간 간섭의 영향이 지배적임을 알 수 있다.

• Proceedings of The KACE
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• 2018.01a
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• pp.49-52
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• 2018

스카이라인 질의는 데이터들 사이의 비교 연산을 통해 지배되지 않은 데이터들의 최소 집합을 스카이라인으로 탐색하며 이때 지배되지 않고 스카이라인으로 선택된 데이터들은 지배된 데이터들을 대표하게 된다. 이러한 특징은 금융, 네트워크, 웹서비스 등 다양한 분야에서 스카이라인의 활용을 이끌어냈다. 하지만 스카이라인 질의는 데이터의 양이나 차원의 수가 증가하는 경우 전체적인 성능이 크게 감소하는 문제를 야기하기 때문에 이를 해결하기 위한 다양한 기법들이 연구 및 제안되고 있다. 하지만 실제 스카이라인 질의를 활용하기 위해서는 객관적 성능 평가를 통해 주어진 상황에서 최적의 성능을 보일 수 있는 기법을 선택해야할 필요가 있지만 기존의 연구들은 성능 평가에 있어 각 기법이 목표한 문제들에 대한 단편적인 실험을 진행하고 있기 때문에 이들을 객관적으로 평가하기 위해서는 새로운 스카이라인 성능 평가 방법이 필요한 실정이다. 본 논문에서는 이러한 문제를 해결하기에 앞서 스카이라인 질의 기법의 객관적 성능 평가를 위한 품질 요소 선택 기준을 선택하기 위해 기존 연구들에 대한 조사와 분석을 진행한다.

• Journal of Software Engineering Society
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• v.13 no.3
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• pp.92-97
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• 2000

양질의 소프트웨어제품과 서비스를 생산하는 방법은 우수한 선례를 답습하거나, 성공한 선례를 해당 응용업무에 맞도록 발전시키는 것이다. 즉 프로세스들의 모임인 소프트웨어 프로세스를 각각의 소프트웨어 서비스와 시스템의 개발목적에 부합하도록 정의하는 것이다. 프로세스 모임은 정보화사업의 포괄적 관리가 가능하게하며, 사업제기부서가 소프트웨어 시스템에 대한 전반적인 의무와 책임을 갖게 하며, 정보화사업 감리에 있어서 감리 목표 정립과 감리의 시행을 명확하게 한다. 소프트웨어 서비스 및 시스템 개발에 있어서 적합한 프로세스의 모임을 목표프로세스 프로파일(Target Process Profile) 이라고 명명하였다. TPP을 정의함에 있어서는 정의할 대상시스템의 성능과 시스템의 효과성이 어느 정도 가시화되는 여건에서, 소프트웨어 서비스 및 시스템의 수명주기 목표, 수명주기 아키텍쳐 및 수명주기 계획을 도출한다. 즉 아키텍쳐 접근방법, 소프트웨어프로세스의 정착, 및 국제표준의 프로세스에서의 프로세스 모임규칙을 근간으로 하여 TPP의 프레임워크(Framework)을 시안을 작성하였다. 소프트웨어공학의 발전과정에서 프로세스 능력의 성숙도 기준으로 프로세스 모임을 이룬것에 추가하여, 논자는 ISO/IEC 15504 TR 프로세스간의 전후관계에서 TPP을 위한 작업산출물 도출방법을 정의하였다. TPP에 의한 정보화추진은 정보화시대에서 소프트웨어 품질 및 가격에서 경쟁력을 가져오는 요인이 될 것이다.