• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.348-351
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• 2012

4대강 살리기 사업 등 대형 사업의 건설 및 시행에 의한 환경적 영향에 대한 예측과 적절한 수질관리 대안을 마련하기 위해서는 적절한 수문 수질모델을 이용하는 것이 필수적이며, 국내 대형 국책 사업 또는 중요 환경영향평가에서는 계속적으로 수질모델이 사용되고 그 적용 범위는 더욱 증가 될 전망이다. 따라서 이들 수질 모델의 사용에 있어서 예측의 정확도 및 신뢰도를 제고하는 것은 매우 중요한 일이라 할 수 있을 것이다. 특히 4대강 살리기 사업에 의해 다수의 보가 하천 내에 건설되고 준설이 실시됨에 따라 하천 내의 수리 동역학적 특성 및 수질특성이 변화할 것으로 예상되며, 적절한 수질관리 대책을 수립하기 위해서는 사업에 의한 수리 및 수질 특성 변화를 예측하고 시나리오를 분석할 있는 모델링 시스템을 구축하는 것이 필수적이다. 따라서 본 논문에서는 보 건설에 따른 다양한 수리 및 수질 특성 변화를 예측하기 위해 모의 가능 모형들을 조사하고, 국 내외 적용사례 분석을 통해서 현재 가장 많이 적용되고 있는 모형들을 선별하였다. 이를 토대로 모형 별 성능을 비교 분석하여 모형별 적용성을 검토하였다. 검토결과 신설보 설치에 따른 하천 수리 특성의 변화, 부유물질 및 동반 오염물질에 의한 수질 변화 등의 고려가 가능하며, 동적상태 모형으로 하천에서의 불연속적인 흐름에 따른 모의, 수심방향으로의 모의가 가능한 EFDC 모형이 보 설치에 따른 국부적인 영향을 자세하게 파악하는데 가장 적절한 모형으로 파악되었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.311-319
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• 2003

This paper aims at investigating the exact dynamic response of the system undergoing a exponential impact force from the viewpoints of conservations of momentum and energy. The midpoint method applied in the Newmark's family algorithm is found to be identical to the case of the application of the trapezoidal method which provides conservations of momentum and energy. For the linear impact force the mid point, the trapezoidal and the (n+1) point method exactly meet the conservation characteristics independent of the size of integration interval. On the other hand, constants for the dynamic motion resulting from the nonlinear impact are underestimated or overestimated by these method mentioned above. To overcome this indispensible error, the Simpson 1/3 method as one of multi step methods whose advantages is to use longer time interval with the same number of evaluation functions is adopted for the exact conservations of momentum and energy. Moreover, the suggested method is expected to expand the similar algorithm for the general dynamic motion including finite rotations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5C
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• pp.562-567
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• 2006

This paper extends Diameter AAA Protocol to provide secure communication channels between Mobile RFID Service Components and distinct service based on user's QoS level authorization. This paper supposes 900MHz, which is the target RF for Mobile RFID Forum and supposes RFID phone, which equitted with RFID reader. By using extended Diameter AAA server, user is authenticated, authorized and provided dynamic security associations between Mobile RFID Service components. The types of security associations are as followings:between RFID tag and RFID reader, between RFID reader(phone) and MobileRFID Service Agent, between phone and OIS, between phone and OTS and between phone and Accounting/Financial server.

• The Journal of the Acoustical Society of Korea
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• v.16 no.6
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• pp.94-99
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• 1997

This paper describes a technique of probabilistic spectral subtraction which uses the knowledge of both noise and speech so as to reduce automatic speech recognition errors in noisy environments. Spectral subtraction method estimates a noise prototype in non-speech intervals and the spectrum of clean speech is obtained from the spectrum of noisy speech by subtracting this noise prototype. Thus noise can not be suppressed effectively using a single noise prototype in case the characteristics of the noise prototype are different from those of the noise contained in input noisy speech. To modify such a drawback, multiple noise prototypes are used in probabilistic subtraction method. In this paper, the probabilistic characteristics of noise and the knowledge of speech which is embedded in hidden Markov models trained in clean environments are used to suppress noise. Futhermore, dynamic feature parameters are considered as well as static feature parameters for effective noise suppression. The proposed method reduced error rates in the recognition of 50 Korean words. The recognition rate was 86.25% with the probabilistic subtraction, 72.75% without any noise suppression method and 80.25% with spectral subtraction at SNR(Signal-to-Noise Ratio) 10 dB.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.171-179
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• 2013

The primary function of navigation system is to provide route search and road guidance for safe driving for drivers. However, the existing route search system provides a simple service that looks up the shortest route using a safe driving DB without considering different road characteristics for the safety of the drivers. In order to maintain the safe driving, rather than searching the shortest path, a navigation system, in which the danger areas and/or the dangerous time zones have been considered, is required. Therefore, in this paper we propose a strategy of searching a navigation path to avoid danger areas for safe driving by using the A* algorithm. In the strategy, when evaluating the path-specific fitness of the navigation nodes, different heuristic weights were assigned to different types of risk areas. In particular, we considered three kinds of danger areas, such as accident-prone sections where accidents occur frequently, school zones, and intersection regions, as well as the time slots when the probability of danger is high. From computer simulation, the results demonstrate that the proposed scheme can provide the way to avoid danger areas on the route searching and confirm the possibility of providing the actual service.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.77-83
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• 2004

In this paper, the Classification of Energy Labeling has been proposed. Energy parameters of input signal which are extracted from each phoneme are labelled. And groups of labelling according to detected energies of input signals are detected. Next. DTW processes in a selected group of labeling. This leads to DTW processing faster than a previous algorithm. In this Method, because an accurate detection of parameters is necessary on the assumption in steps of a detection of speeching duration and a detection of energy parameters, variable windows which are decided by pitch period are used. A pitch period is detected firstly : next window scale is decided between 200 frames and 300 frames. The proposed method makes it possible to cancel an influence of windows and reduces the computational complexity by $25\%$.

• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.37-46
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• 2010

In an IPTV system, the rights of the content and service provider can be protected by using Conditional Access System (CAS) and Digital Right Management (DRM). In case of the CAS, only the authorized user who has structured authentication keys can decrypt the encrypted content. However, since the CAS establishes a secure channel only between content provider and Smart Card (SC), it cannot protect the system against McCormac Hack attack which eavesdrops on unsecure channel between SC and Set-Top Box (STB) and SC cloning attack. In this paper, we propose a robust multi-STB assisted SC / STB authentication protocol which can protect the IPTV system against not only McCormac Hack attack, but also SC cloning attack. The previous works which bind a STB and a SC during the SC registration phase against the SC cloning attack does not support multi-STB environments. The proposed system which dynamically updates the STB information in subscriber management system using the bi-directional channel characteristic of IPTV system can support the user's multi-STB device effectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8A
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• pp.712-722
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• 2011

Wireless body area network(WBAN) provide communication service in the vicinity of the body. Since WBANs utilize both MICS frequency band for implant medical applications and ISM frequency band for medical and consumer electronics(CE) applications. Therefore, MAC protocols in WBAN should be designed considering flexibility between medical and CE applications. In this paper, we identify the requirements of WBAN MAC protocols and propose a WBAN MAC protocol which satisfies the requirements. In other to provide transmission flexibility for various applications. we present the dynamic CFP allocation and opportunity period. Extensive simulation result show that the proposed protocol achieves improved throughput and latency in WEAN environment cimpared with IEEE 802.15.4.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.385-390
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• 2011

The purpose of this research is to determine the dynamic Magnus effect data of a spinning projectile in wind-tunnel testing. In the present work, the high-speed wind-tunnel tests for the Magnus effect measurements were conducted on a 155-mm spin-stabilized projectile model in the Agency for Defense Development's Tri-Sonic Wind Tunnel at spin rates about 12,000 rpm. The test Mach numbers ranged from 0.7 to 2.0, and the angles of attack ranged from -4 to +10 deg. The validity of the wind-tunnel measurement techniques was evaluated by comparing them with the previous test results on the same configuration. The experimental results show that fair to good agreement is obtained with resonable accuracy.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.41-49
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• 2007

Ethernet passive optical network(EPON) is the next-generation technology for supporting services of high-quality at low-cost. In the EPON, all optical network units(ONUs) have to share a limited uplink channel for upstream data. In order to satisfy bandwidth demands of users on high-capacity local access networks(LANs), the optical line terminal(OLT) efficiently divides and allocates time slots of uplink channel to all ONUs. We discuss previous schemes for dynamic bandwidth allocation(DBA), such as interleaved polling with adaptive cycle time(IPACT) and sliding cycle time(SLICT). In this paper, dynamic right sizing of maximum-windows(DRSM), as a novel bandwidth allocation service, is proposed for more effective and efficient time slot allocation of the uplink channel. DRSM which is based on past information of bandwidth allocated by OLT calculates maximum available bandwidth and dynamically alters the maximum window size for the next ONU. This scheme does not only exert every effort to meet bandwidth demands of ONUs with the possible scope, it also seeks fairness of bandwidth allocation among ONUs.