초 고차원 표현법 기반의 이미지 검색을 위한 코드워드 중요성 학습 방법

학위논문(석사) - 한국과학기술원 : 전기및전자공학과, 2013.2, [ ix, 58 p. ]In this thesis, we address three problems of the tf-idf weighting, the hierarchical scoring and intra-class key-words in the image retrieval using very large dimensional Bag-of-Words (BoW) representation. The tf-idf weighting method, which is a commonly used codebook weighting scheme, is usually understood to improve retrieval performance however its degree is not too significant. Rather, it sometimes brings a problem of worsening precision. The hierarchical scoring, which is commonly used in hierarchical codebook, the precision improvement differs depending on the dataset as the number of levels that are considered in scoring gets larger. Intra-class key-words, which represent their class most well, have not taken into consideration in BoW representation based image retrieval because of its too high dimensionality. Despite different classes have different key-word, only a same weight or standard is applied to every image classes. To overcome these three different problems, we suggest a new codewords weighting method preserving the independence model of BoWs representation that codewords occur independently in one image. In the problems of tf-idf weighting and the hierarchical scoring, the proposed method only focuses on improving the algorithms without using any extra cue besides two types of signature, document frequency used for tf-idf weighting and the level for hierarchical scoring. Since the document frequency and the level are related with inter-class discriminability, we define the two values as key-signatures. In the problem of considering intra-class key-words, the proposed method gives relevant weight to codewords according to its statistical appearance within a class. Since an intra-class variance of frequencies of a codeword is related with its intra-class importance, we define that kind of value as another key-signature. We also define a function, called Weight Mapping Function (WMF), that maps a weight value from a key-signature. In order to obt...한국과학기술원 : 전기및전자공학과

Per-class key feature weighting method for image retrieval

대용량 이미지 검색을 위한 가중치를 설정하기 위하여, 이미지에 대한 시각 단어 별로 이미지 구별성에 영향을 미치는 키 값을 정의한다. 이미지의 클래스간 구별성을 높이기 위한 비용 함수를 결정하고, 최적화를 통해 가중치 매핑 함수를 결정하며, 질의 이미지에 대해 가중치 없이 서브셋을 만들어 클래스별 가중치를 적용한 후 재 나열하여 대용량 이미지 검색을 수행한다

Seismic indicators of gas hydrate and associated gas in the Ulleun Basin, East Sea (Sea of Japan)

Seismic indicators of gas hydrate in the Ulleung Basin, East Sea (Japan Sea) include the bottom-simulating reflector, enhanced reflections below the BSR, and seismic chimneys.1

Styles of an isolated, latest Quaternary slope-failure system revealed from sedimentary features of downslope mass-transport deposits in the western margin of Ulleung Basin, East Sea (Japn Sea)

Submarine slope failures is one of the important geological elements for development of continental-margin sequences and generation of geohazards. Important information on slope failures such as their ages, triggering causes, processes, etc. can be revealed from features of both slope failures and downslope associated masstransport deposits (MTDs). In the western margin of the Ulleung Basin, an isolated, latest Quaternary slopefailure system (ca. 13 km x 9 km in area), consisting of arcuate failure scars with head scarps (up to ca. 50 m high), occurs on the present upper to middle slopes, and connects downslope to a gully. Within the slope-failure system, small-scale, elongated failure scars and scarps are present below the head scarps. Just downslope of the gully, fan-shaped bodies of MTDs have been deposited at the base-of-slope. The fan-shaped bodies of MTDs are acoustically transparent or chaotic, and separated by intervals of stratified reflectors on subbottom profiles. The uppermost body of MTDs is 101