• Spatial Information Research
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• v.20 no.4
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• pp.83-92
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• 2012

Location-based services (LBS) are increasingly popular due to the improvement of geo-positioning capabilities and wireless communication technology. However, in order to enjoy LBS services, a user requesting a query must send his/her exact location to the LBS provider. Therefore, it is a key challenge to preserve user's privacy while providing LBS. To solve this problem, the existing method employs a 2PASS cloaking framework that not only hides the actual user location but also reduces bandwidth consumption. However, 2PASS does not fully guarantee the actual user privacy because it does not take the real user distribution into account. Hence, in this paper, we propose a nearest neighbor query processing algorithm that supports K-anonymity property based on the weighted adjacency graph(WAG). Our algorithm not only preserves the location of a user by guaranteeing k-anonymity in a query region, but also improves a bandwidth usage by reducing unnecessary search for a query result. We demonstrate from experimental results that our algorithm outperforms the existing one in terms of query processing time and bandwidth usage.

• The Journal of the Acoustical Society of Korea
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• v.31 no.3
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• pp.197-204
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• 2012

In this thesis, studied the method to minimize the changes in frequency response and level due to the variation of the distance from the source to the microphone. selecting three microphones (omni directional, cardioid, super cardioid) which are being used generally, frequency responses were measured in accordance with the distance changes. Gotten the difference from the reference as the result of measurement, changed responses for each frequency range were compensated in comparison of the original human vocal source. In low frequency range, the low frequency boost caused by the proximity effect and decrease in accordance with the distance were compensated. The variation in mid-frequency range is comparatively small, however since the mid-range is the most important part of the human vocal signal, were compensated the mid-frequency range in comparison of the reference. The human vocal signal variation in high frequency range is extremely small and the high frequency is compensated close to the original source without difficulty. Understanding the microphone characteristics and compensations, this study showed that the response can be maintain among the change of the distance from the source to the microphone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.83-90
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• 2009

In this paper, the problem of electromagnetic transmission through slits in two parallel conducting plates which separate two half spaces is considered. The coupled integral equations for the electric field distributions over the slits are developed for the case that the TM polarized plane wave is incident on the slit and solved by the method of moments. The transmitted power beyond the slit-perforated conducting parallel plates is computed in order to check the variations of the coupled power through slits against some parameters such as the incident angle of the TM polarized wave, slit width, lateral distance between two slits, and distance between the conducting plates. When the lateral distance between two slits approaches near the multiples of half wavelengths, the transmission resonance (maximum power transmission) is observed. If the slit width in the incident side is narrow and the distance between conducting plates is small compared to the wavelength, the maximum of transmitted power is observed to be nearly independent of the incident angle and slit width. In addition, the mechanism of the transmission resonance in the present geometry is explained using a simplified geometry and its equivalent circuit.

• Journal of KIISE
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• v.42 no.3
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• pp.408-412
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• 2015

In base station based networks, traffic overload at the base station is inevitable. Peer-to-peer DTN which disperses the traffic overhead to each node can relieve the traffic overload at the base station. To increase the message delivery ratio and reduce the message overhead, we present novel routing using mobility information which can be obtained from each node, unlike the existing flooding based routings. In the proposed routing scheme, the routing decision metric, which is defined based on the node mobility information, is computed by using the expected distance between each node to the destination. The message is copied to other nodes that have lower expected distance to the destination than the value for the node willing to copy the message. We conducted simulations by using both a random mobility model and a real mobility trace to compare the performance of the proposed routing scheme to the existing routing scheme that does not utilize the mobility information. The performance evaluation showed the proposed routing successfully delivers messages with 10% to 30% less copies compared to previously proposed routing schemes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.21-26
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• 2019

This paper constructs a real-time monitoring system that can identify the individual positions of infants and their proximity to other infants using an Internet of Things (IoT)-based nameplate. The system consists of a precision location tracking module, a data transmission system for calculating gateway location information, a service platform server, and a data analysis processing module considering the development of infants and young children. The purpose of this study is to extract information about how infants interact with each other. The information gathered through this system can be used as important information to improve the peer relations of all infants and toddlers, from neglected infants to infants with no social development problems, to more popular infants. It is possible, based on the proximity information between infants and toddlers, that the teacher can identify positive interactions or negative interactions, and can educate infants on how to improve their peer relationships. These results can be used for consultation with parents, and the information collected through this system can be used as a database to establish a system for improving the relationships between infants and toddlers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.105-113
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• 2003

Because structural systems are becoming lighter and more flexible and have lower natural frequencies and dampings than before, coordinated rhythmic activities such as dancing, audience participation in arenas or concert halls, and aerobics result in undesirable levels of vibration. For rhythmic activities, it is resonant or near resonant behavior that result in significant dynamic amplification and hence human discomfort. The most rational design strategy is to provide enough of a gap between the natural frequency of a floor system and the dominant frequencies excited by planned human activities to assure reasonably that resonance will not occur. For the case study the vibration measurements were performed at the floor of a long-span multi-purpose hall during the rock concert of popular singer.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.1-11
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• 2009

Recently there has arisen concern in both the database community and the graphics society about data retrieval from large motion databases because the high dimensionality of motion data implies high costs. In this circumstance, finding an effective distance measure and an efficient query processing method for such data is a challenging problem. This paper presents an elaborate motion query processing system, SMoFinder (Similar Motion Finder), which incorporates a novel kinematic distance measure and an efficient indexing strategy via adaptive frame segmentation. To this end, we regard human motions as multi-linkage kinematics and propose the weighted Minkowski distance metric. For efficient indexing, we devise a new adaptive segmentation method that chooses representative frames among similar frames and stores chosen frames instead of all frames. For efficient search, we propose a new search method that processes k-nearest neighbors queries over only representative frames. Our experimental results show that the size of motion databases is reduced greatly (${\times}1/25$) but the search capability of SMoFinder is equal to or superior to that of other systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.89-92
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• 2005

Centralized P2P system, Napster and Unstructured P2P system, Gnutella accomplish main current. Centralized system and unstructured system have a restriction in a scalability. To solve the this problem, structured system is appeared. CAN, Chord, Pastry and Tapestry are delegation of this system. Although structured system don't aware physical proximity of node because it uses Distribute Hash Table. In proposing system, a node can communicate with physical proximity of node using concept of LAN. Internet traffic is also decreased because communication in the Chord network divide in two(original network and sub network).

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.207-207
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• 2019

최근 우리나라는 지역 특성 및 기후변화의 영향으로 인해 수문학적 요소의 변동성이 커지고 수자원의 지속적인 관리에 있어 유출량은 중요한 문제로 여겨지고 있다. 특히 일부 소하천 또는 접경지역과 같은 미계측유역은 수문학적 요소에 대한 자료가 부족하고 수문모형의 초기치 설정과 과거 유출량 자료를 통하여 최적화한 매개변수를 결정해야하므로 장기유출분석이 어렵다. 본 연구의 적용유역으로 미계측유역인 임진강상류 유역에 대한 유출량 추정을 위해 계측 유역의 자료를 활용하여 모형의 매개변수 등을 추정하는 지역화 기법인 다중선형회귀분석과 공간근접분석을 활용하여 유출량을 산정 및 검증하였다. 또한, 확률론적 예측이 가능한 앙상블 기법 적용을 통한 유출량 예측을 하였고, 이를 예측 정확성 평가지표를 통해 효율성 검토를 수행하여 미계측유역의 유출량에 대해 확률론적 예측을 수행하였다. 대표적 지역화 기법의 적용성을 검토한 결과, 계측유역을 통해 다중선형회귀분석과 공간근접분석을 abcd 모형에 적용하였다. 모의유출량을 산정하고 실측 유출량과 비교 분석 결과 모의정확성이 높게 분석되었다. 이와 같은 검증 결과를 토대로 미계측유역의 유출량을 추정하였다. 또한, 지역화 기법을 앙상블 기법에 적용하여 확률론적 유출량 예측의 효율성을 검토하였다. 적용유역과 같은 지류를 포함하고 있는 임진강하류 유역을 대상으로 수행하였다. 검증기간(2013년~2017년) 동안의 월 예측 유출량 앙상블 생성을 위해 과거 강우량와 증발량(1988년~2012년) 자료를 사용하였으며, 지역화 기법을 적용한 abcd 모형을 이용하였다. 예측 유출량의 정확성 평가를 실시하였으며, 정확성이 비교적 높게 분석되었다. 이와 같은 결과를 토대로 미계측유역의 확률론적 유출량을 예측하였다. 따라서, 대표적 지역화 기법을 앙상블 기법에 적용하여 확률론적 유출량을 예측할 경우 보다 정확한 유출량 예측이 가능하다.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.71-76
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• 2019

The purpose of this study is to investigate the effect of action learning methods and practices, which have a research focus on learner-centered teaching after training students to use collaborative learning practices from the viewpoint that the learners acquire English skills through peer correction activities based on sociocultural learning theory[1]. From March 1, 2018 to June 15, 2018, one control class and one experimental group were selected from the general freshman English courses. The experimental group attended classes centered on collaborative writing activities using action learning and cooperation techniques, and the control group attended classes lecture style and rote learning methods to teach writing. The result of study has shown that, for the experimental group, there have been statistically significant results in the production of writing, such as the number of words, the number of sentences, and sentence length. Learners could share the knowledge or ideas of others in their learning relationships with more regular basis.