Earticle

Holes are generated due to limited precision of deployment, and thus bypassing holes is one important issue of Wireless Sensor Networks (WSNs). In existing routing schemes using an optimal path, intermediate nodes in the path may deplete their energy quickly, which results in expansion of holes. The Ant Colony Optimization (ACO) algorithm solves this problem by balancing the traffic of data transmitted in the optimal path with transition probability. Ant Colony optimization based Location aware Routing (ACLR) is a hole detour scheme that uses nodes residual energy in transition probability to route data packets in a more energy-efficient way. The problem of ACLR is that it causes unbalanced energy consumption when local minimums occur because a packet may be retransmitted many times by one sensor node. In addition, ACLR also limits the number of nodes used for routing data. In this paper, we propose an algorithm that uses the node’s virtual position, calculated by neighbor nodes coordinates, when computing distances between sensor nodes. By using a node’s virtual positions, a routing scheme using Probability based on Virtual Position (PViP) reduces the number of backoff processes and has more neighbor nodes compared to ACLR. This will enhance the delay performance. As a result, it can balance energy consumption among nodes, improve the network lifetime by up to 7.3%, and the transmission delay by up to 2.7%.

In this paper, we propose a new framework to control VR(Virtual reality) contents in real time using user's mouth-wind and acceleration sensor of mobile device. In VR, user interaction technology is important, but various user interface methods is still lacking. Most of the interaction technologies are hand touch screen touch or motion recognition. We propose a new interface technology that can interact with VR contents in real time using user's mouth-wind method with acceleration sensor. The direction of the mouth-wind is determined using the angle and position between the user and the mobile device, and the control position is adjusted using the acceleration sensor of the mobile device. Noise included in the size of the mouth wind is refined using a simple average filter. In order to demonstrate the superiority of the proposed technology, we show the result of interacting with contents in game and simulation in real time by applying control position and mouth-wind external force to the game.

This paper presents a method for enhancing the angular resolution of multiple input multiple output (MIMO) radar systems by employing an extended non-uniform virtual array. Although a larger aperture achieved through non-uniform antenna placement can enhance the resolution, it also introduces sidelobe artifacts that degrade the image quality. To construct a non-uniform array that minimizes the sidelobe effects, the MIMO antenna placement is optimized using a genetic algorithm. Additionally, a convolutional neural network is employed to further suppress residual sidelobe effects that remain after optimization. Notably, to reduce the time and cost associated with collecting large-scale training data, a simulation-based radar data generation method is introduced. Both simulation and real-world measurements using the TI AWR cascade radar module were conducted to validate the proposed method.

Objective: The purpose of the present study was to compare the root positions in virtual tooth setups using only crowns in a simulated treatment with those achieved in the actual treatment. Methods: Pre- and post-treatment intraoral and corresponding cone beam computed tomography (CBCT) scans were obtained from 15 patients who underwent orthodontic treatment with premolar extraction. A conventional virtual tooth setup was used for the treatment simulation. Pre- and post-treatment three-dimensional digital tooth models were fabricated by integrating the patients' intraoral and CBCT scans. The simulated root positions in the virtual setup were obtained by merging the crown in the virtual setup and root in the pre-treatment tooth model. The root positions of the simulated and actual post-treatment tooth models were compared. Results: Differences in root positions between the simulated and actual models were > 1 mm in all teeth, and statistically significant differences were observed (p < 0.05), except for the maxillary lateral incisors. The differences in the inter-root angulation were > 1° in all teeth, and statistically significant differences were observed in the maxillary and mandibular canines. Conclusions: The virtual tooth setup using only crown data showed errors over the clinical limits. The clinical application of a virtual setup using crowns and roots is necessary for accurate and precise treatment simulation, particularly in extraction treatment.

The virtual Frisch-grid method for room-temperature radiation detectors has been widely used because of its simplicity and high performance. Recently, side electrodes were separately attached to each surface of the detectors instead of covering the entire detector surface with a single electrode. The side-electrode structure enables the measurement of the three-dimensional (3D) gamma-ray interaction in the detector. The positional information of the interaction can then be utilized to precisely calibrate the response of the detector for gamma-ray spectroscopy and imaging. In this study, we developed a 3D position-sensitive 5 × 5 × 12 mm³ cadmium-zinc-telluride (CZT) detector and applied a flattening method to correct detector responses. Collimated gamma-rays incident on the surface of the detector were scanned to evaluate the positional accuracy of the detection system. Positional distributions of the radiation interactions with the detector were imaged for quantitative and qualitative evaluation. The energy spectra of various radioisotopes were measured and improved by the detector response calibration according to the calculated positional information. The energy spectra ranged from 59.5 keV (emitted by ²⁴¹Am) to 1332 keV (emitted by ⁶⁰Co). The best energy resolution was 1.06% at 662 keV when the CZT detector was voxelized to 20 × 20 × 10.

Recently, with the rapid development of virtual reality technology, there have been more and more applications of virtual reality technology in various fields. In order to realize a virtual reality, a method of implementing a visualization environment through an HMD (Head Mounted Display) is widely used. However, in the current visualization environment through the HMD, the user feels dizziness when worn, It has the disadvantage of imposing restrictions on. In this study, it is aimed to realize virtual reality visualization environment through multi-screen environment which improves the experience effect of virtual environment by using existing screen instead of visualization through HMD, and compensates for shortcomings of HMD method. In order to realize a multi-screen environment as a highly visualized environment, a technique for matching the spatial position of the multi-screen with the spatial position of the virtual environment is required. To do this, we need an efficient method to precisely measure the position of the space, and we propose a spatial position compensation methodology that can efficiently and precisely measure the position of the real space and reflect it in the virtual environment.

The High school literary education in Korea is needed a change for a well-rounded education in near future. So many learned studied a variety of ways with drama for education forms, but theatrical performance was snapped field application. Therefore we need a new approach way, the way is ‘the virtual position program’ in literary culture. Virtual position is an drama techniques for education and an way with learners to change the perspective of the point of view watching for trouble condition. This note contained concept, framework and the configuration way of the virtual position program in actual scene for literary class. And It propose an utilization act of the virtual position program by Learning model example. The virtual position program has an effect that can change and grow, learner’s ability to literature itself in light of learners and provide hands-on experience to contribute to behavior change of a hybrid situation in the drama situation.

학습자들의 일상과 지나치게 멀어져 버린 학교 문학교육을 정상화하고, 미래를 살아가는데 필요한 다양한 능력을 길러주는 교육이 되도록 하기 위해 새로운문학교육의 방향성을 제시하고, 이를 실천하기 위한 방안과 이 방안을 실현하기위한 교사의 역할에 관한 논의를 진행해 보았다. 새로운 문학교육의 방향은 ‘융합형 문학교육’이라고 이름 붙인 것으로 이것은 교과 통합이 아니라 학습자들이문학 학습 경험을 통해 융합적인 사고를 할 수 있는 다양한 관점과 문제 해결능력을 갖도록 하는 문학교육의 새로운 방향을 의미하는 것이다. 상황 맥락을제시하여 사고하도록 하는 방식의 문학교육으로 특히 이러한 문학교육을 시행하기 위해 수업 장면에서 도로시 헤스컷의 ‘전문가의 외투(mantle of the expert)’ 를 활용한 ‘가상지위(virtual position)’라는 연극적 장치를 활용하는데, 이것은학습자들이 주어진 역할을 통해 다양한 관점에서 문학 작품을 수용하고 활용하는 경험을 하도록 만든 것이다. 이를 위해서 교사는 수업 장면에서는 연극적 상황을 가정하고 ‘역할 내 교사(Teacher-in-role)’로 문제 상황 속으로 학습자들을 끌어들이는 연기를 해야 한다. 수업 이후에는 과제를 제시하거나 확인하고 피드백을 주며, 평가도 진행해야한다. 수업을 떠나서 문학과 관련한 다양한 교내외 활동을 기획하고 제공하여학습자들이 다양한 문학적 경험을 하도록 하는 것도 교사의 역할인데 결국 교사의 역할이 지식의 전달자가 아닌 학습자와 수업 상황맥락을 관리하며, 학습자와학습자 혹은 학습자와 사회를 매개하면서 학습자의 경험을 확장해 주는 역할로변화함을 의미하는 것이다. 이러한 과정 전체를 교사 개인이 책임지기에는 지나치게 방대한 것이기 때문에 교사 역시 집단을 구성하여 진행할 수 있도록 하며,교사의 공동체가 활성화되고 문학교육에 관한 공유를 활발하게 하는 것은 결과적으로 문학교육 체계를 안정시켜 질적으로 우수한 문학교육을 제공하게 되는계기가 될 것이다.

A discussion about teacher role took place for suggestion of new direction of literature education, a plan for practicing and putting this theory into practice to normalize relations with estranged literature education from learners' daily life and to be the education that prepares learners necessary differing ability for their future life. The new direction of literature education is named 'accreted literature education', it would suggest new direction of literature education to get differing perspective for integrated thinking through the learners' literature learning experience not to integrate subjects. It is a type of education to think through suggestion of situation context. Expecially to implement this literature education 'virtual position' that is used from 'mantle of the expert' as theatrical device is used in a lesson scene, it is designed for experience of acceptance and utilization literary works as differing perspective through given a role. For this teachers have to suppose theatrical situation in the lesson scene and act for attracting learners in problematic situation as 'Teacher-in-role'. After the lesson, they need to give, confirm or feedback learners' assignment and proceed evaluation. One of teachers' roles is planning and offering intramural activity related to literature besides lessons and learners can experience various literature activities from it but it's too burden-some for answering for this whole process as an individual teacher so it is needed to proceed with a teacher group and it will serve qualitatively excellent literature education as stabilizing literature education system as a result from revitalizing teacher community and sharing briskly about literature education.

Authors have measured virtual source distance of electron beam from CL/1800 medical linear accelerator, with newly designed method. Beam scanning was performed with the direction of beam axis in the air. Compared results between this study and well established in phantom measurement shows good agreement with in experimental error. And we have found that build-up cap plays very important role in air measurement because of charge build up. The method of in-air measurement of virtual source distance is very easy to set-up and generate accurate results.

가상화폐가 상당부분 인간의 경제활동에 침투한 시장현실에도 불구하고 아직도 대부분의 국가에서는 가상화폐 관련 정의 및 법안을 만들지 못하고 있다. 그 이유는 ① 분산원장(distributed leger) 및 암호화 기술에 기반한 비트코인(2009년)과 1,600여 종의 신종코인 등(alt-coin) 가상화폐의 개념을 일의적으로 정의하기는 어려움이 있다는 점 및 ② 가상화폐들의 기능 및 용도가 매우 다양한 가운데 관련 기술이 발전하면서 새로운 종류도 지속적으로 출현하고 있기 때문인 것으로 요약될 수 있다. 가상화폐가 인간의 경제활동에서 차지하는 비중이 증가하는 것과 더불어 여러 가지 문제점들도 수반되고 있는 등 다양한 연구과제가 존재한다. 국내외의 기존 논의들을 종합해보면, 가상화폐의 지위는 각국 증앙은행으로 부터 상당한 견제를 받고 있는 것으로 보인다. 가상화폐의 효시인 비트코인은 스스로를 “비트코인은 혁신적인 결제 네트워크이자 신종화폐입니다.”라고 주장하고 있다. 그러나 각국의 전반적인 평가는 ‘혁신적인 결제네트워크’로도, ‘신종화폐’로도 인정하지 않는 것으로 보인다. 다만, 초기에 비하여 최근에는 비트코인 등 가상화폐의 투기상품적 성질에 대한 지적이 증가한 것으로 보인다. 가상화폐의 법적 성격을 기존의 법규정만으로 파악하는 것은 용이하지 않다. 그 이유는기존의 관련 법규정이 가상화폐의 출현을 염두에 둔 것이 아니었기 때문일 것이다. 비트코인 등 가상화폐가 가지는, 기존의 법화를 대체하려는 화폐로서의 기능이나 성질은, 초기의 기대 또는 우려에 비하여 약화된 것으로 판단된다. 다만, 시간이 경과함에 따라 금융투자상품으로서의 성질이 강화되고 있는 것으로 보인다. 그럼에도 불구하고 국내에서는 이에 대한 적절한 규제가 시행되고 있다고 보기 어렵다. 기존의 규정중심 체계의 법 규정으로 가상화폐의 법적성격을 획정하는 것은 실익이 크다고 보기 어렵다. 왜냐하면, 한 가상화폐의 법적성격을 규정한다하여도 이후에 새로운 구조의 가상화폐가 등장하는 경우 동일한 기준으로 법적성격의 규정하는 것이 불가능할 수도 있기 때문이다. 따라서 비트코인 등 가상화폐는 각국의 사정에 따라 개념의 파악을 달리할 필요가 있어 보인다. 우리나라의 경우, 현재시점에서 가상화폐는 상대적으로 금융투자상품적 성격이 두드러지는 것으로 볼 수 있다. 가상화폐가 투자목적으로 활발하게 거래되는 현재 상황에서는, 금융투자상품의 투자자에 준하는, 가상화폐 투자자 보호를 위한 일련의 조치가 필요하다. 우선은 금융위원회가규제 방향의 원칙을 밝혀서, 최소한의 투자자보호 장치를 시급히 갖추는 것이 필요하다. 다음으로, 가상화폐의 합리적 규제를 위하여 자본시장법 등 관련 법규정의 개정이나 별도의법률 제정의 검토가 필요할 것이다.

Almost every country struggles to define and establish rules for virtual currency, although virtual currency is now ubiquitous in the financial market to some extent. It is because Bitcoins and Alt-Coins of 1,600 types, which are based on distributed ledger and encryption technology, are not easy to define in a single concept. Various research subjects exist, including virtual currency’s increasing role in economic activities, with a couple of problems that follow it. In short, central banks of major countries have keenly watched the payment and settlement function in virtual currencies. Bitcoin, the first virtual currency, itself insists that “Bitcoin is an innovative payment network and a new kind of money.” Nevertheless, recently the governors of major central banks regard Bitcoin as neither an innovative payment network nor a new kind of money. However, it seems that criticisms on virtual currency being speculative investment has increased compared to earlier times. It is not easy to find out the legal nature of virtual currency from existing laws. It is because existing laws were not written with virtual currency taken into account. The concerns against virtual currency replacing the existing legal currency seems to have weakened than before. In contrast, virtual currency’s function as financial investment instrument has grown. Nevertheless, there are little proper regulations on these functions of virtual currency in Korea. It seems impractical to define the legal nature of virtual currency from the ground of existing rule-based system. It is because even if we succeed to define the legal nature of one virtual currency through the existing rule, this does not guarantee the same for the next one. Therefore, the definition of virtual currency seems to vary from country to country. At this point, virtual currencies stand out as financial investment instrument in Korea. Since virtual currency is actively traded for financial investment instrument, it is necessary to provide protection for the investors. Firstly, Korean Financial Services Commission must announce the principles of regulation on virtual currency, and secondly, amendment of the Financial Investment Services and Capital Markets Act and new legislation on virtual currency is necessary for establishing reasonable regulations on virtual currency.

증강현실 시스템을 구축하는데 있어 실시간 가상객체 위치 추적은 실세계와 가상객체를 정확하고 깊이감 있게 정합하고, 실세계 움직임에 따른 가상객체 위치변화 추적에 중요하다. 따라서 실시간 카메라 입력영상으로부터 가상객체의 위치를 추적하는데 있어 정확성과 함께 빠른 수행시간이 요구된다. 본 논문에서는 HMD(Head Mounted Display)장비에 장착된 두 개의 카메라로부터 관찰자의 시점 이동에 따른 가상객체 정합위치 정보를 입력받아 그 위치를 정확하게 인식하고 빠르게 추적하기 위하여 인위적인 랜드마크 형태를 정의하였으며, 실시간 입력영상으로부터 랜드마크 중심점 위치를 실시간으로 추적하기 위해 일정시간 간격마다 입력받은 첫 영상으로부터 얻은 랜드마크 영역 정보를 이용하여 중심점의 위치를 추적함으로써 수행시간을 줄이고자 하였다.

This paper proposes a method to generate virtual intensity field in space. The sound field of a zone enclosing the listener position is controlled to have maximum acoustic intensity to the desired direction. In order to control acoustic intensity of a zone, space-averaged active intensity is introduced. The ratio of space-averaged active intensity and control effort is defined as a cost function and expressed as a function of source control signals. It is shown that the cost function represents radiation efficiency of multiple sources. The control signals maximizing the cost function is found through eigenvalue analysis. The proposed method is verified by numerical simulations performed in free field condition, and the results provide a relation between wavelength and the size of controllable intensity field.

위성항법시스템 (GNSS: Global Navigation Satellite System)으로 계산되는 위치 정확도는 위성 의사거리 (Pseudo-Range) 측정값 정확도와 DOP (Dilution of Precision) 으로 표현되는 위성의 배치관계를 통해 결정된다. 위성의 의사거리 측정값은 위성 시계, 궤도, 전리층, 대류층, 다중경로 등 여러 요인에 의해 오차가 발생하게 되며, 사용자 의사거리정확도를 향상을 위해서는 정확한 의사거리 측정값이 필요하다. 반면, 위성의 배치의 경우, 사용자의 수신환경에 따라 위치 정확도가 달라진다. 예를 들어, 고층 빌딩이 많은 도심의 경우에는 위성전파 차단의 위험이 많아 가시위성의 수가 감소하고 개활지에 비해 상대적으로 양호한 DOP을 가지기 어렵다. 본 논문은 가상위성 (Virtual Satellite)을 통해 DOP 성능 개선과 의미있는 가상거리측정값 (VRM: Virtual Range Measurement) 정확도를 확보하여, 위치 정확도 향상 시키는 방법에 대해 연구하였다. 그 결과 적절한 가상위성배치와 정확한 가상 거리측정값을 이용하면 수직위치 정확도의 개선 효과를 얻을 수 있었다.

GNSS (Global Navigation Satellite System) Position Accuracy depends on pseudo-range measurement and DOP (Dilution Of Precision) which indicates about navigation satellite geometry. Pseudo-Range has many error sources such as satellite clock, orbit, ionosphere, troposphere, multipath and so on. For the improvement of the accuracy, user can use corrected pseudo-range in DGPS (Differential Global Positioning System), which is one of the relative positioning methods. But, stationary station is needed in relative positioning. In case of DOP, Signal reception environment is important. If receiver sets in the center of city, it could be interrupted reception by buildings. This environment leads to decrease the number of visible satellites and to increase DOP. This paper proposes the concept of GNSS positioning with virtual satellites which have usable VRM (Virtual Range Measurement). Via virtual satellites and VRM, users could get an accurate position. Especially referred virtual satellites constellation has an effect on vertical error.

In this paper, we propose how to determine the optimal camera position using inverse kinematics of virtual link model and manipulability measure. We model the variable distance and viewing direction between a target object and a camera position as a virtual link. And, by using inverse kinematics of virtual link model, we find out regions that satisfy the direction and distance constraints for the observation of target object. The solution of inverse kinematics of virtual link model simultaneously satisfies camera accessibility as well as a direction and distance constraints. And we use a manipulability measure of active camera system in order to determine an optimal camera position among the multiple solutions of inverse kinematics. By using the inverse kinematics of virtual link model and manipulability measure, the optimal camera position in order to observe a target object can be determined easily and rapidly.