Steganalysis of Synonym-Substitution Based Natural Language Watermarking

Zhenshan Yu,Liusheng Huang,Zhili Chen,Lingjun Li,Xinxin Zhao,Youwen Zhu 보안공학연구지원센터 2009 International Journal of Multimedia and Ubiquitous Vol.4 No.2

Natural language watermarking (NLW) is a kind of digital rights management (DRM) techniques specially designed for natural language documents. Watermarking algorithms based on synonym substitution are the most popular kind, they embeds watermark into documents in linguistic meaning-preserving ways. A lot of work has been done on embedding, but only a little on steganalysis such as detecting, destroying, and extracting the watermark. In this paper, we try to distinguish between watermarked articles and unwatermarked articles using context information. We evaluate the suitability of words for their context, and then the suitability sequence of words leads to the final judgment made by a SVM (support vector machine) classifier. IDF (inverse document frequency) is used to weight words’ suitability in order to balance common words and rare ones. This scheme is evaluated on internet instead of in a specific corpus, with the help of Google. Experimental results show that classification accuracy achieves 90.0%. And further analysis of several influencing factors affecting detection effects is also presented.

英ㆍ德刑事起诉裁量权之比较

耿振善(Geng, Zhenshan),金容吉(Kim Yongkil) 한국공공사회학회 2014 공공사회연구 Vol.4 No.2

기소재량권은 법관이 심판과정에서 행하는 자유재량권과 상대되는 개념으로 검찰관이 수사종결 후 공소제기시에 범죄혐의와 기소조건에 부합하더라도 자유재량에 기초하여 기소할지 여부를 결정하는 권한을 말한다. 기소여부의 판단은 소송절차상 수사와 재판의 중간에 위치하여 수사를 바탕으로 재판단계로 진행할 지 여부를 결정하게 되며, 이 단계에서 기소재량권의 올바른 행사는 소송의 진행 및 기소된 자의 운명을 결정하게 되므로 그 중요성이 매우 크다. 영미법계 국가들은 광의의 기소재량권을 채택하고 있는데, 공소기관은 형사사건의 입건수사, 기소심사, 재판과정에서 사건의 사실인정과 법률의 적용에 있어 공정하고 합리적으로 판단할 수 있는 권한을 갖고 있다. 대륙법계 국가의 기소재량권은 통상 기소단계로 한정된 협의의 기소재량권이다. 검찰관이 기소여부 판단시 증거가 충분하고 소추 조건이 구비된 범죄라도 구체적 상황을 고려하여 자유재량으로 공소제기 여부를 결정할 수 있다. 영국검찰관은 사건을 수사하는 경우 두 가지 측면에서 수사검증을 진행하는데 첫째가 증거검증이며 둘째가 공공이익에 대한 검증이다. 영국검찰관은 기소단계에서 기소여부와 더불어 어떤 죄명으로 기소할 지 여부를 결정한다. 또한 피고인이 여러 죄를 범한 경우에 그 중 일부만을 기소할 수 있으며, 하나의 죄를 구성하는 사건에 있어서는 형량이 낮은 죄명으로도 기소할 수도 있다. 이외에도 유죄협상제(Plea bargaining) 및 증인이 증언에 의한 처벌을 면할 수 있도록 하는 것 등은 영국검찰관이 가진 기소재량권의 중요 부분이다. 독일에서 검찰관의 기소재량권 행사의 주요 기준은 두 가지로, 죄형의 경중과 공공이익의 많고 적음이다. 독일 검찰관의 기소재량권 행사는 주로 불기소 방식으로 행사되며, 종류는 ‘경범죄 불기소’와 ‘조건부 불기소’의 두 가지가 있다. 불기소의 범위는 매우 광범위하며, 벌금 부여 등 실질적으로 권한을 행사하고 있으며, 법관이 행사하는 일부 권한도 부여 받아 행사하기도 한다. 또한, 독일의 기소재량권은 법원에 의한 규제와 주 사법부에 의한 감독, 검찰내부 감독, 피해자에 의한 강제기소청구 등의 방법으로 제한되고 있다. 영국과 독일 양국의 기소재량권은 성질, 적용범위, 내용, 제약방식 및 소송가치 등에 있어 뚜렷한 차이를 보인다. 영국의 기소재량권은 필수조건이나 제한이 적어 남용될 우려가 있으나, 독일은 재량권에 너무 많은 감독과 제한조건이 있어 충분한 효용을 발휘하는데 어려움이 있다. 이러한 차이점은 각기 장단점으로 작용하고 있다. 중국에서는 최근에 검찰관의 기소재량권 문제에 있어 두 방식간의 장단점을 취하려는 움직임이 일고 있다. 이러한 경우에 독일검찰관이 기소재량권을 행사하기 전에 법관의 동의를 얻어야 하는 제약방식은 부적절한데, 이는 기소재량권을 침해하는 것으로 검찰관의 적극성을 방해하기 때문이다. 따라서 감독방식의 개혁이 필요하며 사후제약 방식으로 변경하여 검찰관의 적극적인 기소재량권 행사를 보장하여야 할 것이다. The power of prosecuting discretion means that as for the cases which are criminal suspicious and satisfy the legal requirements of prosecution, prosecutors have the power to determine whether to initiate public prosecution pursuant to the specified situations. As the doctrine of prosecutorial discretion has been established in different countries’ modern criminal procedures, the power of prosecutorial discretion has been generally recognized by different countries and playing a significant role in the legal practice. However, due to the differences in terms of legal culture, history tradition, litigation value, different legal systems and countries have different regulations on the power of prosecutorial discretion. As the typical models of Anglo-American law system and Civil law system, UK and German have their own significant characteristics respectively in terms of system design and legal practice. Thus, it is necessary for us to compare the power of prosecutorial discretion between these two countries and do relevant researches. Meanwhile, we need to analyze the differences among countries and explore corresponding reasons. After that, we could have a better understanding on the power of prosecuting discretion, which could promote the reform and perfection of prosecutorial discretion procedure in our country.

Continuous O2-CO2 production using a Co-based oxygen carrier in two parallel fixed-bed reactors

Teng Zhang,Ningsheng Cai,Zhenshan Li 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3

Oxygen-enriched carbon dioxide stream with oxygen concentration higher than 20 vol% was produced continuously by using a Co-based oxygen carrier packed in two parallel fixed-bed reactors operated in a cyclic manner. Oxygen was absorbed by the oxygen carrier with air being fed. An oxygen-enriched carbon dioxide stream was obtained when the fixed-bed was regenerated with carbon dioxide as a purge gas. Multiple absorption and desorption cycles indicated that the Co-based oxygen carrier had high cyclic stability. XRD analysis determined the absorbed and desorbed products were Co3O4 and CoO, respectively. The TGA results indicated that Co-based oxygen carrier did not react with NO or SO2 during the desorption stage. This Co-based oxygen carrier offers potential for applications in the O2-CO2 production for the oxy-fuel coal combustion process.

Yaw wind effect on flutter instability of four typical bridge decks

Zhu, Le-Dong,Xu, You-Lin,Guo, Zhenshan,Chang, Guang-Zhao,Tan, Xiao Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.3

When evaluating flutter instability, it is often assumed that incident wind is normal to the longitudinal axis of a bridge and the flutter critical wind speed estimated from this direction is most unfavorable. However, the results obtained in this study via oblique sectional model tests of four typical types of bridge decks show that the lowest flutter critical wind speeds often occur in the yaw wind cases. The four types of bridge decks tested include a flat single-box deck, a flat ${\Pi}$-shaped thin-wall deck, a flat twin side-girder deck, and a truss-stiffened deck with and without a narrow central gap. The yaw wind effect could reduce the critical wind speed by about 6%, 2%, 8%, 7%, respectively, for the above four types of decks within a wind inclination angle range between $-3^{\circ}$ and $3^{\circ}$, and the yaw wind angles corresponding to the minimal critical wind speeds are between $4^{\circ}$ and $15^{\circ}$. It was also found that the flutter critical wind speed varies in an undulate manner with the increase of yaw angle, and the variation pattern is largely dependent on both deck shape and wind inclination angle. Therefore, the cosine rule based on the mean wind decomposition is generally inapplicable to the estimation of flutter critical wind speed of long-span bridges under skew winds. The unfavorable effect of yaw wind on the flutter instability of long-span bridges should be taken into consideration seriously in the future practice, especially for supper-long span bridges in strong wind regions.

Yaw wind effect on flutter instability of four typical bridge decks

Le-Dong Zhu,You-Lin Xu,Zhenshan Guo,Guang-Zhao Chang,Xiao Tan 한국풍공학회 2013 한국풍공학회지 Vol.17 No.3

When evaluating flutter instability, it is often assumed that incident wind is normal to the longitudinal axis of a bridge and the flutter critical wind speed estimated from this direction is most unfavorable. However, the results obtained in this study via oblique sectional model tests of four typical types of bridge decks show that the lowest flutter critical wind speeds often occur in the yaw wind cases. The four types of bridge decks tested include a flat single-box deck, a flat π-shaped thin-wall deck, a flat twin side-girder deck, and a truss-stiffened deck with and without a narrow central gap. The yaw wind effect could reduce the critical wind speed by about 6%, 2%, 8%, 7%, respectively, for the above four types of decks within a wind inclination angle range between -3° and 3°, and the yaw wind angles corresponding to the minimal critical wind speeds are between 4° and 15°. It was also found that the flutter critical wind speed varies in an undulate manner with the increase of yaw angle, and the variation pattern is largely dependent on both deck shape and wind inclination angle. Therefore, the cosine rule based on the mean wind decomposition is generally inapplicable to the estimation of flutter critical wind speed of long-span bridges under skew winds. The unfavorable effect of yaw wind on the flutter instability of long-span bridges should be taken into consideration seriously in the future practice, especially for supper-long span bridges in strong wind regions.

Topology optimization of unsymmetrical complex plate and shell structures bearing multicondition overload

Yangyang Zhang,Yixiao Qin,Jinpeng Gu,Qianqian Jiao,Feng Wang,Zhenshan Guo,Hao Zhang,Jianjun Wang,Chenghong Mi,Huaipeng Zheng 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

Unsymmetrical complex plate and shell structure is one of the common engineering structures. In practice, more redundant materials exist because of the irrationality of this kind of structure with heavy load and multiple working conditions, and the study of its topology optimization has become an engaging topic. Using the SIMP model, topological results show that one side of the main web is a hollow structure, and the other side of the auxiliary web is a truss structure. According to the topological results and considering manufacturable processing, a new structure is redesigned, the size and shape of the redesigned structure is secondary optimized, and the final structure is obtained. The method in this paper not only meets the performance requirements of the unsymmetrical complex plate and shell structures, but also realizes the topology and lightweight. The effectiveness scientific research value of the proposed method is verified by engineering examples.

Layout Optimization of Stiffeners in Heavy-Duty Thin-Plate Box Grider

Hao Zhang,Yixiao Qin,Jinpeng Gu,Haibiao Gao,Qianqian Jiao,Feng Wang,Zhenshan Guo,Yangyang Zhang,Chenghong Mi 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.8

The optimization of layout and sizes of the stiffeners in heavy-duty box girder could make this kind of the structure more compact and reasonable, which has certain engineering values. In this study, on the basis of the establishment of parametric finite element model, the function approaching method and gradient search method are combined to form a high-precision optimization algorithm, which makes structural analysis be integrated into the optimization process. The optimization takes the type and location of longitudinal stiffening ribs and the thickness and hole position of transverse diaphragms as design variables, the box girder structural behaviors as constraint conditions, and the total volume as objective function. Finally, the weight is reduced by nearly 7%. More importantly, the new asymmetrical layout of the stiffeners is obtained, the distance between the longitudinal stiffening ribs on the main web and the neutral layer is longer than the distance between the longitudinal stiffening ribs on the secondary web and the neutral layer, and the hole position of transverse diaphragms is close to the secondary web. Compared with the current production of symmetrical layout structure, this layout provides a new idea for the design of stiffeners in the bias-rail box girder.