• The Journal of the Acoustical Society of Korea
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• v.19 no.3
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• pp.35-44
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• 2000

In this paper, we propose a new trajectory model for characterizing segmental features and their interaction based upon a general framework of hidden Markov models. Each segment, a sequence of vectors, is represented by a trajectory of observed sequences. This trajectory is obtained by applying a new design matrix which includes transitional information on contiguous frames, and is characterized as a polynomial regression function. To apply the trajectory to the segmental HMM, the frame features are replaced with the trajectory of a given segment. We also propose the likelihood of a given segment and the estimation of trajectory parameters. The obervation probability of a given segment is represented as the relation between the segment likelihood and the estimation error of the trajectories. The estimation error of a trajectory is considered as the weight of the likelihood of a given segment in a state. This weight represents the probability of how well the corresponding trajectory characterize the segment. The proposed model can be regarded as a generalization of a conventional HMM and a parametric trajectory model. The experimental results are reported on the TIMIT corpus and performance is show to improve significantly over that of the conventional HMM.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.383-386
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• 2022

본 논문에서는 COVID-19와 같은 위급한 상황에서 바이러스 검사를 빠르게 진행하기 위한 K-d 트리 기반의 그래프 구축과 환자 이동 경로 시스템을 제안한다. 가상환경에서 활용되는 대표적인 길 찾기 알고리즘은 A^*나 NavMesh 자료구조는 정해진 정적 이동 경로만을 안내하려는 방법이기 때문에 가상환경에서 NPC를 제어할 때는 효율적이지만, 실제 환경에 적용하여 문제를 풀기에는 충분하지 않다. 특히, 빠른 바이러스 검사를 받기 위해서는 짧은 거리만을 이용하는 게 아닌, 실제 도로 교통상황, 병원의 크기, 환자 이동 수, 환자 처리 시간 등 고려해야 할 상황들이 많다. 본 논문에서는 위에서 언급한 다양한 속성들과 이를 이용한 최적화 함수를 모델링하여, 실제 도시 맵에서 바이러스 검사를 빠르고 효율적으로 제어할 수 있는 프레임워크를 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.851-860
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• 2020

With an increase in the aging population and a rising social interest in health and welfare, studies to improve healthcare in the elderly are being actively conducted. This study attempted to improve the current design and manufacture of elevating electric wheelchairs to enhance user safety and convenience. Seat design based on the user's body shape, convenience while boarding or alighting, caster turning radius and, safety and stability features that prevent shaking when the user gets up or sits down were improved. A driving experiment was conducted to evaluate the operation of the indoor electric wheelchair designed and manufactured with these additional functionalities. During the test, the performance parameters evaluated were continuous driving time, turning radius, maximum lifting and lowering load, maximum lifting height, noise level, minimum distance sensing by the driving auxiliary sensor, ability to interact with server and app programs, and the duty cycle maximum error rate. The test confirmed that this improved electric wheelchair successfully met target parameters. In a future study, we will evaluate this improved electric wheelchair from a user's perspective for its usability parameters, such as satisfaction, convenience and stability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2323-2329
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• 2009

Recent IPTV services still remain as simple broadcasting services that cannot make the most of interactive features together with various content-associated data. So, IPTV providers are making efforts to break from monopolistic style, so as increasing the user's participation m service. However there is an interoperability problem because no common solution is employed across different providers. To solve this problem, there needs to be a framework for a framework for generating, sharing and distributing package contents. In this paper, we propose user-centered package contents application framework for interactive IPTV services. We also design a package content authoring and consuming system which plays core parts in the proposed framework.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.95-100
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• 2009

This study was conducted to develop an imaging processing system of inoculation processing of a lily callus. The image processing system was composed of a camera, a image processing board, and etc. And the illuminance always decided by setting up 55W/3 wavelength lamp respectively on all aspects and the side was maintained by the lighting part. The image characteristic was examined according to each frame of RGB,therefore the culture vessel was able to be separated with B frame. The required time was 2.2 seconds in one cycle from the image acquisition to obtaining the result. The recognition rate of the container was 100%, and the result of image processing showed that the recognition success rate of lily callus was 93%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1085-1094
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• 1999

In the global system for the mobile communication (GSM) system, the class of training sequences used in a TDMA frame is a preamble sequence with a period of 16 bits for the channel impulse response measurement and the start up equalization during the training period. If the transmitted preamble sequence and the binary sequence in the receiver properly satisfy a condition, this training sequences used for fastly adjusting the tap coefficients and impulse response can be measured by calculating the crosscorrelation function. In this paper, it is used that training sequences have zero values of the autocorrelation at all delays except zero and middle shifts. A comparison of convergence rate, a mathematical approach for fast start-up equalization and correctly channel impulse response measurement are proposed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9C
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• pp.849-860
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• 2007

Because the H.264/AVC standard adopts the variable length coding algorithm, the rate of encoded video bitstream fluctuates a lot as time flows, though its compression efficiency is superior to that of existing standards. When a video is transmitted in real-time over networks with fixed low-bandwidth, it is necessary to control the bit rate which is generated from encoder. Many existing rate control algorithms have been adopting the quadratic rate-distortion model which determines the target bits for each frame. We propose a new rate control algorithm for H.264/AVC video transmission over networks with fixed bandwidth. The proposed algorithm predicts quantization parameter adaptively to reduce video distortion using the quadratic rate-distortion model, which uses the target bit rate and the mean absolute difference for current frame considering pixel difference between macroblocks in the previous and the current frame. On video samples with high motion and scene change cases, experimental results show that (1) the proposed algorithm adapts the encoded bitstream to limited channel capacity, while existing algorithms abruptly excess the limit bit rate; (2) the proposed algorithm improves picture quality with $0.4{\sim}0.9dB$ in average.

• Journal of KIISE:Databases
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• v.32 no.5
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• pp.473-486
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• 2005

The Hippocratic database model recently proposed by Agrawal et at. incorporates privacy protection capabilities into relational databases. The authors have subsequenty proposed the Hippocratic XML daかabase model[4], an extension of the Hippocratic database model for XML databases. In this paper, we propose a new concept that we cail the dynamic predicate(DP) for effective access control in the Hippocratic XML database model. A DP is a novel concept that represents a dynamically constructed rendition that tan be adapted for determining the accessibility of elements during query execution. DPs allow us to effectively integrate authorization checking into the query plan so that unauthorized elements are excluded in the process of query execution. Using synthetic and real data, we have performed extensive experiments comparing query processing time with those of existing access control mechanisms. The results show that the proposed access control mechanism improves the wall clock time by up to 219 times over the top-down access control strategy and by up to 499 times over the bottom-up access control strategy. The major contribution of our, paper is enabling effective integration of access control mechanisms with the query plan using the DP under the Hippocratic XML database model.

• Journal of Korean Society of Steel Construction
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• v.18 no.2
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• pp.225-237
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• 2006

Based on the study conducted by Kim et al. (205a, b), an improved stability design method for evaluating the effective buckling lengths of beam-column members is proposed herein, using system elastic/inelastic buckling analysis and second-order elastic analysis. For this purpose, the stress-strain relationship of a column is inversely formulated from the reference load-carrying capacity proposed in design codes, so as to derive the tangent modulus of a column as a function of the slenderness ratio. The tangent stiffness matrix of a beam-column element is formulated using the so-called "stability functions," and elastic/inelastic buckling analysis Effective buckling lengths are then evaluated by extending the basic concept of a single simply-supported column to the individual members as one component of a whole frame structure. Through numerical examples of several structural systems and loading conditions, the possibilities of enhancement in stability design for frame structures are addressed by comparing their numerical results obtained when the present design method is used with those obtained when conventional stability design methods are used.

• The Journal of the Acoustical Society of Korea
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• v.11 no.1E
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• pp.73-78
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• 1992

시벼형 신호인 음성 신호의 분석에 칼만필터를 이용하였다. 일반적인 음성 분석은 프레임단위의 처리방법인 선형 예측 부호화 기법을 주로 이용하지만 음성의 시변 특성을 파악하는데에는 적절하지 못 하다. 따라서 순차적인 추정기법으로 많이 이용되는 칼만 필터를 음성 분석에 적용하였다. 또한 음성과 같은 시변신호에서는 과거 신호의 잡음의 분산값에 적당한 가중치를 부가하므로써 과거의 신호에 의해 서 현재의 추정값에 미치는 영향을 줄였으며 이를 음성의 천이 구간에서의 파라메타 추정에 사용하였 다. 그리고 음성신호 모델에서 생기는 모델링 오차는 일반적으로 백색 가우시안 잡음으로 가정하고 있 으나 이는 자음과 같은 무성음에서 특징 파라메타 푸정에는 오차가 적지만 모음등의 유성음에서는 음성 발생시의 여기신호인 펄스열에 의해서 많은 모델링 오차를 생기게 한다. 따라서 모델링 오차신호는 Non-Gaussian 확률분포로 가정한 후 로버스트 칼만 필터를 사용하여 합성으멩 대해 특징 파라메터를 추출하였다.