• Journal of Korea Multimedia Society
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• v.20 no.6
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• pp.911-917
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• 2017

Tor proxy tool is studied which is most frequently used for ransomeware to penetrate into sensitive information. It will be researched for the malicious methods to spread virus by using Tor and considered a countermeasure to prevent them. We present exit relay methodology for Tor security policy, simulate it, and get a probability to detect the ransomeware. And we compare it with TSS technology which is able to protect the attack via virtual server on exit relay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.1030-1037
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• 2008

This paper presents an algorithm for the path-finding problem in unknown environments with cooperative and commutative multi-robots. To verify the algorithm, we investigate the problem of escaping through the exit of a randomly generated maze by muti-robots. For the purpose, we adopt the so called frontier cells and cell utility functions, which were used in the exploration problem for the multi-robots. For the wireless communications among the mobile robots, we modify and utilize the so called the random basket routing, a kind of hop-by-hop opportunistic routing. A mobile robot, once it finds the exit, will choose its next action, either escape immediately or stay-and-relay the exit information for the others, where the robot takes one action based on a given probability. We investigate the optimal probability that minimizes the average escaping time (out of the maze to the exit) of a mobile robot.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.614-618
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• 2015

This paper described an off-axis head-mounted display system. It is composed of a 7-piece coaxial relay lens group and a freeform surface combiner. This configuration has a simple structure and a wide field of view (FOV). In this design, a freeform surface is chosen as the combiner, to simplify the structure and attain good image quality. We generated this freeform surface by considering both coordinates and normals of discrete data points. Moreover, we realize a coaxial structure in the relay lens group, which is compact and benefits from a loose tolerance requirement. The HMD system we finally realized has a 40° × 30° FOV and 15-mm exit pupil diameter.

• Current Optics and Photonics
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• v.2 no.3
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• pp.280-285
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• 2018

A new method to design a see-through off-axis head-mounted-display (OA-HMD) optical system with an ellipsoidal surface is proposed, in which a tilted ellipsoidal surface is used as the combiner, which yields the benefits of easier fabrication and testing compared to a freeform surface. Moreover, we realize a coaxial structure in the relay lens group, which is simple and has looser tolerance requirements, thus making assembly easier. The OA-HMD optical system we realize has a simple structure and consists of a combiner and 7 pieces of coaxial relay lenses. It has a $48^{\circ}{\times}36^{\circ}$ field of view (FOV) and 12-mm exit pupil diameter.

• Journal of Korean Theatre Studies Association
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• no.48
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• pp.485-507
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• 2012

Parodos, the side entrances to orchestra (acting space), was one of the intrinsic elements for the ancient Greek theatre structure. It is worth noting that parodos was the sole structural component that remained the original form while all the other elements such as orchestra, skene, and theatron experienced drastic or gradual changes in form throughout the passage of time. On the reason for parodo's maintenance of the original form, this study suggests a possibility that parodos could be the most intrinsic among the elements for Greek theatre buildings. For evidence, this paper indicates the historical fact that the procession tradition was the key event in the national or civic festival known as City Dionysia, and that the single-direction passageway, as seen in the Panathenaic Way passing through the City Athens, could be the easiest and most efficient way to realize the cause for the procession tradition that is the citizens' participation and subsequent unification. This study suggests another possibility that the single-direction passageway in the procession could be the archetype of parodos. For evidence, this study finds that this type of passageway was ubiquitous around the City Athens especially in the Agora, the most popular place in the city and the gateway to the processional event for Dionysian Cult as well as the space for the earliest Greek theatricality and, therefore, was familiar to the citizens. From the discussion, this paper argues that the Greek theatre should be the miniature of the Agora in terms of form (single-direction passageway) and function (civic participation and unification), and that parodos was the theatrical version of the processional passageway in the Dionysian Cult. In conclusion, this paper argues that parodos played a double role. It satisfied the theatrical necessity by functioning as the passageway to dramatic action (entrance and exit of actor/chorus) and as the literal door for the entrance of the audience members. At the same time, it satisfied the social cause, that is civic participation and subsequent unification, by functioning as the processional passage to relay the theatre space to civic events for the national religious cult.