• 대한전자공학회논문지SP
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• 제39권4호
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• pp.442-454
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• 2002

물체 단위의 동영상 컨텐츠(contents) 저작 부호화를 가능하게 하는 SA-DCT (Shape-Adaptive Discrete Cosine Transform)는 기존의 블록 DCT와는 달리 수평과 수직 방향의 1차원 변환을 수행하는 순서에 따라 서로 다른 변환 결과를 보인다. 변환 대상 블록의 수평과 수직 방향 중 상관 관계가 크거나 변환시 화소의 이동이 작은 방향으로 먼저 1차원 변환을 수행함으로써 최종 2차원 변환된 계수들의 에너지 분포가 DC 계수를 중심으로 보다 집중화 됨을 알 수 있었다. 본 논문에서는 공간 상관도가 높은 방향으로 먼저 1차원 변환을 적용하므로써 보다 높은 에너지 집중화가 이루어짐을 실험적으로 확인한다. 그리고 1차원 변환 방향 순서를 매 블록별로 적응적으로 결정하기 위하여 두가지 방법을 제안한다. 하나의 방법은 주변 블록과 현재 블록의 DC 값들의 경사도를 이용하는 간접적 방법이며, 또다른 방법은 블록의 2차원 변환 데이터를 부호화하여 발생되는 비트수를 비교하는 직접적 방법이다. 제안 방법들을 MPEG-4 동영상 부호화기에 적용하여 모의 실험한 결과, 제안된 적응적 SA-DCT 방법이 기존의 SA-DCT에 비하여 경계 블록에서 최대 10.87%의 부호화 비트 감소 효과가 있음을 알 수 있었다.

• 한국정보시스템학회지:정보시스템연구
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• 제29권3호
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• pp.237-251
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• 2020

Purpose The research was studied the hierarchical Hangul emotion index by organizing all the emotions which SNS users are thinking. As a preliminary study by the researcher, the English-based Plutchick (1980)'s emotional standard was reinterpreted in Korean, and a hashtag with implicit meaning on SNS was studied. To build a multidimensional emotion dictionary and classify three-dimensional emotions, an emotion seed was selected for the composition of seven emotion sets, and an emotion word dictionary was constructed by collecting SNS hashtags derived from each emotion seed. We also want to explore the priority of each Hangul emotion index. Design/methodology/approach In the process of transforming the matrix through the vector process of words constituting the sentence, weights were extracted using TF-IDF (Term Frequency Inverse Document Frequency), and the dimension reduction technique of the matrix in the emotion set was NMF (Nonnegative Matrix Factorization) algorithm. The emotional dimension was solved by using the characteristic value of the emotional word. The cosine distance algorithm was used to measure the distance between vectors by measuring the similarity of emotion words in the emotion set. Findings Customer needs analysis is a force to read changes in emotions, and Korean emotion word research is the customer's needs. In addition, the ranking of the emotion words within the emotion set will be a special criterion for reading the depth of the emotion. The sentiment index study of this research believes that by providing companies with effective information for emotional marketing, new business opportunities will be expanded and valued. In addition, if the emotion dictionary is eventually connected to the emotional DNA of the product, it will be possible to define the "emotional DNA", which is a set of emotions that the product should have.

• 전자공학회논문지
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• 제52권3호
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• pp.105-115
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• 2015

반도체 식각 전산모사에서는 플라즈마 입자를 생성하는 소스의 모델링이 필요하다. 본 논문에서는 플라즈마 식각 공정에서 사용하는 소스를 확률분포함수로 모델링하고, 몬테칼를로 방법을 이용하여 특정 프로프일의 플럭스를 계산하는 실험을 하였다. 소스의 모델링 파라미터로 소스와 셀 사이의 거리, 소스에서 방사하는 입자수가 있고, 플럭스 계산에 미치는 추가적인 파라미터로 프로파일 상의 셀의 수(셀의 면적)이 있다. 방사하는 입자 분포는 사용하는 소스의 물성에 따라 가우시안 분포와 코사인 분포로 모델링 할 수 있는데, 본 논문은 이들 각각에 대하여 파라미터를 바꿔가며 전산모사를 한 결과를 보인다. 오차율은 가우지안(Incident Flux)과 코사인분포(Incident Neutral Flux)에서 모두 입자 수의 증가에 따라 상당부분 감소하였으나 처리시간은 이보다 더 증가하였다. 셀수와 거리의 증가는 오차율을 약간 증가시켰고 처리시간도 증가시켰다. 본 논문의 실험 결과를 통해 처리 시간을 고려하여 적합한 플럭스의 계산을 유추할 수 있다.

• 한국정보통신학회논문지
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• 제13권12호
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• pp.2677-2684
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• 2009

본 논문에서는 trellis 부호 및 엔트로피 마스킹을 이용한 정보부호화 기반 워터마킹 방법에 대하여 연구하였다. 영상을 $8{\times}8$ 블록으로 중복되지 않게 나누어 DCT 변환을 수행하고 각 블록으로부터 16개의 중간주파수 대역의 계수를 추출한다. 이를 trellis 부호화의 각 단계에서 평균이 0이고 분산이 1인 가우시안 난수와 비교하여 선형상관계수 및 왓슨거리의 선형결합이 최소인 벡터를 Viterbi 알고리즘으로 구하고 이를 원 영상에 삽입하여 워터마킹된 영상을 얻는다. 영상의 특성을 고려하기 위해 삽입벡터를 구할 때 엔트로피 마스킹 함수를 사용하여 선형상관계수와 왓슨거리의 가중치를 다르게 적용한다. 제안방법의 성능을 평가하기 위해 다수의 영상에 대한 평균비트오차율을 계산하여 성능을 비교하였으며, 평균비트오차율 측면에서 성능 개선이 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.323-327
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• 2002

In order to control the railway noise, the radiation characteristic of the noise during the train passage should be analyzed. Generally, the major noise sources for Korean Train Express are the rolling noise and power unit noise up to 300km/h. In this paper, we describe on a train model that is considered to be a row of point sources to calculate the radiation characteristic. The calculation results are compared with short distance measurement. It is shown that the radiation characteristic of the rolling noise is dipole type. The noise generated by the power unit is radiated as the cosine type. The noise level at an observer is increased in the direction of motion and reduced in the direction opposite to the motion with increasing of the train speed. The calculation results including the moving effect of the noise source at 300km/h show in good agreement.

• 한국멀티미디어학회논문지
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• 제21권8호
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• pp.952-959
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• 2018

Clustering is one of the most fundamental algorithms in machine learning. The performance of clustering is affected by the distribution of data, and when there are more data or more dimensions, the performance is degraded. For this reason, we use a stacked auto encoder, one of the deep learning algorithms, to reduce the dimension of data which generate a feature vector that best represents the input data. We use k-means, which is a famous algorithm, as a clustering. Sine the feature vector which reduced dimensions are also multi dimensional, we use the Euclidean distance as well as the cosine similarity to increase the performance which calculating the similarity between the center of the cluster and the data as a vector. A deep clustering networks combining a stacked auto encoder and k-means re-trains the networks when the k-means result changes. When re-training the networks, the loss function of the stacked auto encoder and the loss function of the k-means are combined to improve the performance and the stability of the network. Experiments of benchmark image ad document dataset empirically validated the power of the proposed algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.2785-2799
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• 2020

We propose a novel speaker adaptation method using acoustic model clustering. The similarity of different speakers is defined by the cosine distance between their i-vectors (intermediate vectors), and various efficient clustering algorithms are applied to obtain a number of speaker subsets with different characteristics. The speaker-independent model is then retrained with the training data of the individual speaker subsets grouped by the clustering results, and an unknown speech is recognized by the retrained model of the closest cluster. The proposed method is applied to a large-scale speech recognition system implemented by a hybrid hidden Markov model and deep neural network framework. An experiment was conducted to evaluate the word error rates using Resource Management database. When the proposed speaker adaptation method using i-vector based clustering was applied, the performance, as compared to that of the conventional speaker-independent speech recognition model, was improved relatively by as much as 12.2% for the conventional fully neural network, and by as much as 10.5% for the bidirectional long short-term memory.

• Bulletin of the Korean Chemical Society
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• 제20권8호
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• pp.897-904
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• 1999

We have presented the thermodynamic, structural and dynamic properties of liquid pentane isomers - normal pentane, isopentane, and neopentane - using an expanded collapsed atomic model. The thermodynamic properties show that the intermolecular interactions become weaker as the molecular shape becomes more nearly spherical and the surface area decreases with branching. The structural properties are well predicted from the site-site radial, the average end-to-end distance, and the root-mean-squared radius of gyration distribution func-tions. The dynamic properties are obtained from the time correlation functions - the mean square displacement (MSD), the velocity auto-correlation (VAC), the cosine (CAC), the stress (SAC), the pressure (PAC), and the heat flux auto-correlation (HFAC) functions - of liquid pentane isomers. Two self-diffusion coefficients of liquid pentane isomers calculated from the MSD's via the Einstein equation and the VAC's via the Green-Kubo relation show the same trend but do not coincide with the branching effect on self-diffusion. The rotational re-laxation time of liquid pentane isomers obtained from the CAC's decreases monotonously as branching increases. Two kinds of viscosities of liquid pentane isomers calculated from the SAC and PAC functions via the Green-Kubo relation have the same trend compared with the experimental results. The thermal conductivity calculated from the HFAC increases as branching increases.

• Journal of Information Processing Systems
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• 제15권4호
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• pp.737-747
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• 2019

Shape description is an important and fundamental issue in content-based image retrieval (CBIR), and a number of shape description methods have been reported in the literature. For shape description, both global information and local contour variations play important roles. In this paper a new included-angular ternary pattern (IATP) based shape descriptor is proposed for shape image retrieval. For each point on the shape contour, IATP is derived from its neighbor points, and IATP has good properties for shape description. IATP is intrinsically invariant to rotation, translation and scaling. To enhance the description capability, multiscale IATP histogram is presented to describe both local and global information of shape. Then multiscale IATP histogram is combined with included-angular histogram for efficient shape retrieval. In the matching stage, cosine distance is used to measure shape features' similarity. Image retrieval experiments are conducted on the standard MPEG-7 shape database and Swedish leaf database. And the shape image retrieval performance of the proposed method is compared with other shape descriptors using the standard evaluation method. The experimental results of shape retrieval indicate that the proposed method reaches higher precision at the same recall value compared with other description method.

• 한국정보시스템학회지:정보시스템연구
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• 제31권1호
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• pp.271-287
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• 2022

Purpose This research aims to study the changes in recruitment needed for the growth and survival of companies in the rapidly changing industry. In particular, we built a real company's worklist accounting for the rapidly advancing data-driven digital transformation, and presented the capabilities and conditions required for work. Design/methodology/approach we selected 37 jobs based on NCS to develop the employment search requirements by analyzing the business characteristics and work capabilities of the industry and company. The business specification indicators were converted into a matrix through the TF-IDF process, and the NMF algorithm is used to extract the features of each document. Also, the cosine distance measurement method is utilized to determine the similarity of the job specification conditions. Findings Companies tended to prefer "IT competency," which is a specification related to computer use and certification, and "experience competency," which is a specification for experience and internship. In addition, 'foreign language competency' was additionally preferred depending on the job. This analysis and development of job requirements would not only help companies to find the talents but also be useful for the jobseekers to easily decide the priority of their specification activities.