• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.1
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• pp.31-39
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• 2016

Hash function is a cryptographic primitive which conduct authentication, signature and data integrity. Recently, Wang et al. found collision of standard hash function such as MD5, SHA-1. For that reason, National Security Research Institute in Korea suggests a secure structure and efficient hash function, LSH. LSH consists of three steps, initialization, compression, finalization and computes hash value using addition in modulo $2^W$, bit-wise substitution, word-wise substitution and bit-wise XOR. These operation is parallelizable because each step is independently conducted at the same time. In this paper, we analyse LSH structure and implement it over SIMD-SSE, AVX and demonstrate the superiority of LSH.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.701-704
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• 2015

해시함수는 사회 전반에 걸쳐 무결성 및 인증을 제공하기 위하여서 사용하는 함수로써 암호학적으로 중요한 함수이다. 본 논문에서는 2014년 국가보안기술 연구소에서 개발한 해시함수 LSH를 하드웨어적인 구현이 아닌 소프트웨어적인 구현을 수행하였고 또한 Intel CPU 상에서 동작하는 SIMD 기법인 SSE를 이용하여 LSH 알고리즘의 최적화 구현을 수행한다. 고속해시함수 LSH 알고리즘에서 사용하는 주 연산은 ARX(Addition Rotation, Xor)연산으로 SIMD를 적용하기에 용이한 구조로 되어 있다. 본 논문에서는 기존 32 비트 단위의 연산을 수행하는 LSH 알고리즘을 SIMD를 이용하여 128비트 단위의 연산을 수행 하도록 개발하였다. 그 결과 Intel Xeon CPU에서 SIMED를 적용한 결과 적용하지 않은 LSH 알고리즘보다 최대 2.79배의 성능의 향상을 확인 할 수 있다.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.445-446
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• 2015

LSH는 고차원 데이터베이스에서의 빠른 유사 아이템 검색을 위해 널리 사용되고 있는 인덱싱 방안이나, 다양한 파라메터가 존재하여 각 파라메터를 적절하게 설정하는 데에 어려움이 있다. 본 논문에서는 다양한 실험을 통해 고차원의 대용량 멀티미디어 데이터베이스에서의 유사 아이템 검색을 위한 LSH의 파라메터에 따른 성능 추이를 살펴보고, 적절한 파라메터를 설정하는 방안에 대해 논의한다.

• Journal of KIISE:Software and Applications
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• v.37 no.4
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• pp.264-272
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• 2010

Example-based super resolution is a method to restore a high resolution image from low resolution images through training and retrieval of image patches. It is not only good in its performance but also available for a single frame low-resolution image. However, its time complexity is very high because it requires lots of comparisons to retrieve image patches in restoration process. In order to improve the restoration speed, an efficient patch retrieval algorithm is essential. In this paper, we applied various high-dimensional feature retrieval methods, available for the patch retrieval, to a practical example-based super resolution system and compared their speed. As well, we propose to apply the multi-phase candidate reduction approach to the patch retrieval process, which was successfully applied in character recognition fields but not used for the super resolution. In the experiments, LSH was the fastest among conventional methods. The multi-phase candidate reduction method, proposed in this paper, was even faster than LSH: For $1024{\times}1024$ images, it was 3.12 times faster than LSH.

• Women's Health Nursing
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• v.20 no.2
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• pp.148-154
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• 2014

Purpose: This study was done to evaluate postoperative patient satisfaction, vaginal bleeding, and sexual function in women after laparoscopic supracervical hysterectomy (LSH). Methods: A retrospective study was conducted using a questionnaire mailed to 131 women who underwent LSH between 2008 and 2011at the Department of Obstetrics &Gynecology, D University Hospital in Chungnam province. Indication for LSH was uterine myoma. The questionnaire contained questions on overall postoperative satisfaction, influence on quality of life of vaginal bleeding, and sexual satisfaction following surgery. Data were collected from March to July 2013 and 109 (83.2%) patients returned the questionnaire. Results: Most women reported being very satisfied (90.8%) or satisfied (7.3%), but 2 women (1.8%) were not satisfied with LSH. Four patients (3.4%) reported experiencing vaginal bleeding but with no negative influence on quality of life. Of sexually active women, 82 patients (90.1%) reported improvements in sexual function, 8 patients (8.8%) reported "no change", and one patient (1.1%) reported a deterioration Conclusion: Results of this study indicate that LSH is associated with a high degree of patient satisfaction, no negative influence on quality of life from vaginal bleeding, and improvement in sexual function to a minimum 2 years after the procedure.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.364-380
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• 2016

The most popular approach in object classification is based on the bag of visual-words model, which has several fundamental problems that restricting the performance of this method, such as low time efficiency, the synonym and polysemy of visual words, and the lack of spatial information between visual words. In view of this, an object classification based on weakly supervised E2LSH and saliency map weighting is proposed. Firstly, E2LSH (Exact Euclidean Locality Sensitive Hashing) is employed to generate a group of weakly randomized visual dictionary by clustering SIFT features of the training dataset, and the selecting process of hash functions is effectively supervised inspired by the random forest ideas to reduce the randomcity of E2LSH. Secondly, graph-based visual saliency (GBVS) algorithm is applied to detect the saliency map of different images and weight the visual words according to the saliency prior. Finally, saliency map weighted visual language model is carried out to accomplish object classification. Experimental results datasets of Pascal 2007 and Caltech-256 indicate that the distinguishability of objects is effectively improved and our method is superior to the state-of-the-art object classification methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.146-149
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• 2004

We have studied a liquid crystal (LC) mode (named locked super homeotropic (LSH)) in which the LCs aligned homeotropically are locked by surrounding walls such as cubic, hexagonal and cylinder. In the device, the vertically aligned LCs tilt down symmetrically around the center of the cell when a voltage is applied and thus it exhibits wide viewing angle. The structure of this LSH mode is suitable for large-sized display panels. since the LCs are locked in micro domains the LCs do not flow to the bottom of the panel by gravity. This mode is applicable to achieve high performance TFT-LCD TV because of high performance characteristics such as high contrast, high brightness, wide-viewing angle.

• Journal of information and communication convergence engineering
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• v.16 no.2
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• pp.99-105
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• 2018

k-Nearest neighbor join (k-NN Join) is a computationally intensive algorithm that is designed to find k-nearest neighbors from a dataset S for every object in another dataset R. Most related studies on k-NN Join are based on single-computer operations. As the data dimensions and data volume increase, running the k-NN Join algorithm on a single computer cannot generate results quickly. To solve this scalability problem, we introduce the locality-sensitive hashing (LSH) k-NN Join algorithm implemented in Spark, an approach for high-dimensional big data. LSH is used to map similar data onto the same bucket, which can reduce the data search scope. In order to achieve parallel implementation of the algorithm on multiple computers, the Spark framework is used to accelerate the computation of distances between objects in a cluster. Results show that our proposed approach is fast and accurate for high-dimensional and big data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.3
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• pp.323-330
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• 2021

Recently, the advantages of high-speed arithmetic in quantum computers have been known, and interest in quantum circuits utilizing qubits has increased. The Grover algorithm is a quantum algorithm that can reduce n-bit security level symmetric key cryptography and hash functions to n/2-bit security level. Since the Grover algorithm work on quantum computers, the symmetric cryptographic technique and hash function to be applied must be implemented in a quantum circuit. This is the motivation for these studies, and recently, research on implementing symmetric cryptographic technique and hash functions in quantum circuits has been actively conducted. However, at present, in a situation where the number of qubits is limited, we are interested in implementing with the minimum number of qubits and aim for efficient implementation. In this paper, the domestic hash function LSH is efficiently implemented using qubits recycling and pre-computation. Also, major operations such as Mix and Final were efficiently implemented as quantum circuits using ProjectQ, a quantum programming tool provided by IBM, and the quantum resources required for this were evaluated.

• Journal of Korea Multimedia Society
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• v.16 no.6
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• pp.735-745
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• 2013

The emergence of Web 2.0 technologies, such as blogs and wiki, enable even naive users to easily create and share content on the Web using freely available content sharing tools. Wide availability of almost free data and promiscuous sharing of content through social networking platforms created a content borrowing phenomenon, where the same content appears (in many cases in the form of extensive quotations) in different outlets. An immediate side effect of this phenomenon is that identifying which content is re-used by whom is becoming a critical tool in social network analysis, including expert identification and analysis of information flow. Internet-scale reuse detection, however, poses extremely challenging scalability issues: considering the large size of user created data on the web, it is essential that the techniques developed for content-reuse detection should be fast and scalable. Thus, in this paper, we propose a $qSign_{lsh}$ algorithm, a mechanism for identifying multi-sentence content reuse among documents by efficiently combining sentence-level evidences. The experiment results show that $qSign_{lsh}$ significantly improves the reuse detection speed and provides high recall.