• 산업경영시스템학회지
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• 제30권1호
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• pp.59-65
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• 2007

HPI (High-speed Portable Internet) system which provides high speed internet services is going to be commercialized soon. Since HPI provides simultaneously four different service types such as UGS (Unsolicited Grant Service), rtPS (real time Polling Service), nrtPS(non-real time Polling Service), and BE (Best Effort) under different QoS (Quality of Service) requirements and limited wireless channel resources, efficient packet scheduling mechanisms are necessary to increase the utilization of channels as well as to satisfy the various QoS requirements. This study regards the traffic data to be served as time series and proposes a new packet scheduling algorithm based on the nonparametric statistical test. The performance of the newly proposed algorithm is evaluated through the simulation analysis using a simulator that can evaluate the performance of packet scheduling mechanisms under various values of system parameters and measures such as packet delay time, data transmission rate, number of loss packets, and channel utilization.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.317-324
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• 2016

This paper proposes a message transfer application using smartphone with NFC(Near Field Communication) and GCM(Goolge Cloud Messaging) technology for prevention of personal information leakage. In implementing for the proposed system, we design a NFC-based vehicle status alerts service which make it possible to communicate with smartpone message without phone-number between a car driver and an unspecified person. The application provides message communication mechanism without exposing the real phone number, using the NFC tag written with the driver's smartphone device ID and GCM push messages. Through the evaluation result of the actual implemented application, the proposed system can be efficient technology in protection for leakage of personal information such as personal phone- number in daily life.

• Communications for Statistical Applications and Methods
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• 제8권2호
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• pp.557-564
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• 2001

The objective of he study is to record the real conditions along with the soccer ball that is, each player's ball keeping time, the number football keeping, accuracy of passing to other player, direction, etc., on a real-time basis, measure them in numbers and get necessary analyzed output as much as one needs. The study consists of the following stages: (1) Record the data by drawing through Visual Interface on a real-time basis; (2) Graphic windows to display the recorded data item by item in graphic; (3) Form windows to display the individual or team scores anytime when needed; (4) Windows to display the analyzed data in visualized form. The effect of the study is threefold: (1) It inputs all the game-related data on a real-time basis, which was impossible before and shows analyzed contents during the game enabling each tea manager o use; (2) In cse of TV broadcasting or newspaper articles, it explains objectively the situations of he game to the TV viewers or readers; (3) After the game, it provides importance information on each team's playing ability and individual player's technical improvement through data analysis.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권8호
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• pp.594-601
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• 2004

We analyze checkpoint strategy for multiple real-time periodic tasks with hard deadlines. Real-time tasks usually have deadlines associated with them. For multiple real-time tasks, checkpoint strategy considering deadlines of all tasks is very difficult to derive. We analyze the problem of checkpoint placement for such multiple periodic tasks. In our strategy, the interval between checkpoints is determined for each task considering its deadline. An approximated failure probability over a specified interval is derived. Then the number of checkpoints for each task is selected to minimize the approximated failure probability. To show the usefulness of our strategy, error bound between the exact and the approximated failure probability is estimated, which is revealed to be quite small.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.24-34
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• 2021

실시간으로 유동인구를 계측하는 기술은 다양한 산업 분야에서 공간 밀집도에 대한 통찰력을 제공하여 더 좋은 서비스 환경을 만들어준다. 이에 따라 여러 기업과 학계에서는 특정 공간의 유동인구 데이터를 계측하기 위해 오랫동안 다양한 연구를 시도해왔으며, 최근에는 스마트시티와 디지털트윈의 일환으로 Wi-Fi 신호를 활용한 유동인구 분석 사업화가 더욱 활발한 추세이다. 본 논문에서는 유동인구 데이터를 활용하는 일반 수요자(비전문가)의 관점에서 유동인구 계측 시스템에 대해 쉽게 이해할 수 있도록 설명한다. 구체적으로는 사람들이 소지한 스마트폰으로부터 수집되는 MAC-address 값 기반의 유동인구 추정 방법을 제시하는데, 추정값의 정확도를 분석하기 위해 Real MAC-address와 Random MAC-address 값을 구분한 뒤, Real MAC-address가 추출된 실제 스마트폰 기기 수와 CCTV 화면에 집계된 사람 수를 비교하는 실험을 진행한다. 그 결과 두 데이터 간의 유사한 상관 계수가 나타났다. 이러한 결과에 근거하여 MAC-address 분류를 통한 Wi-Fi Probe Request 기반 유동인구 분석 방법을 제시한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.822-825
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• 1988

In this paper, we present a system which enables a real-time measurement of the number and also the body length of the fry (baby fish) using a line image sensor. Here, we consider a situation that fry are transported from a pond to another, pond through a pipe. At one position of the pipe a transparent rectanglar channel is mounted. The images of the fry, which run through this rectanglar channel, are detected by a line image sensor. The image signals are digitized to binary ones and the contour of the fry are detected. After that, a real-time image analysis is executed with a digital signal processor. Labeling program analyses the connection of every pixel. The results are transfered to a personal computer and displayed on the online monitor graphically.

• ETRI Journal
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• 제26권5호
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• pp.391-396
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• 2004

In this paper, we propose a packet scheduling discipline called packet loss fair scheduling, in which the packet loss of each user from different real-time traffic is fairly distributed according to the quality of service requirements. We consider an orthogonal frequency division multiple access (OFDMA) system. The basic frame structure of the system is for the downlink in a cellular packet network, where the time axis is divided into a finite number of slots within a frame, and the frequency axis is segmented into subchannels that consist of multiple subcarriers. In addition, to compensate for fast and slow channel variation, we employ a link adaptation technique such as adaptive modulation and coding. From the simulation results, our proposed packet scheduling scheme can support QoS differentiations while guaranteeing short-term fairness as well as long-term fairness for various real-time traffic.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.519-524
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• 2002

The long span PSC deck of composite girder bridge should be needed in order to improve the endurance and to simplify the structure of the steel bridge. However, there have been few domestic research activities about long-span PSC decks for the steel bridges with a small number of girders. In this study, a literature survey is performed to develop a new deck system for the steel bridge with a small number of girders. By considering the characteristics of a small number of girders bridge system, a cast-in-place long span PSC deck is proposed for a small number of girders bridges. To examine structural behavior and safety of the proposed PSC deck, the real scale partial models of the deck(12m$\times$3.2m) are tested under the static loading. In the test, the failure mode and behavior of each specimen, and ultimate load carrying capacity of the proposed PSC deck are identified.

• 전기학회논문지
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• 제59권11호
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• pp.2103-2107
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• 2010

This paper deals with the recognition of multiple mobile robots equipped with RFID tag. In the case that the number of robots recognized by each RFID reader is larger than that of allocated slots, the clashing recognition occurs. And, in the case that the total number of robots recognized by all RFID reader is larger than that of real robots, the repetitious recognition occurs. We employ the dynamic frame slot allocation by using the ALOHA algorithm to prevent the clashing recognition and estimate the number of robots by using the received signal strength indication to prevent the repetitious recognition. The numerical experiment shows the reliability and the efficiency of the proposed method.

• 한국환경복원기술학회지
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• 제19권4호
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• pp.81-89
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• 2016

This study aims to understand the relationship between visitors and the degradation of natural resources in Bukhansan national park. We analyzed the trend of the number of visitors, destruction of natural resources and decrease of biodiversity per year. We further compared three types of trails, heavily-used trails and rarely-used trails and a trail with limited access, regarding the degree of destruction in the National Park through a field survey. Our result showed that increasing number of visitors had direct and indirect impact on the destruction of natural resources in the National Park. The direct impact came from visitors' excessive use of trails. Naturally, increasing number of visitors caused an immoderate use of natural resources. Physical degradation such as exposure of tree root, poor drainage of trails, trail erosion was more severe than other types of trails. Decreasing biodiversity or mild disturbance around trails is the indirect impact such as broken bough, worn-bark in rarely-used trails. Destruction scale greatly increased as the number of visitors increased. Real-named reservation system helped to prevent trails from degradation. Our result calls for the need of controlling the number of visitors to Bukhansan National Park to mitigate the degradation. We recommend dispersing visitors from the heavily-used trails to other trails and implementing real-named reservation system in the rarely-used trails for the effective management of the national park.