• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.226-229
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• 1999

We have been developing a method to build models for time series using Genetic Programming. The proposed method has been applied to various kinds of time series e.g. computer-generated chaos, natural phenomena, and financial market indices etc. Now we apply the prediction method to time histories of seismic ground motion i.e. one-step-ahead prediction of seismographic amplitude. Waves of earthquakes are composed of P-waves and S-waves. They propagate in different speeds and have different characteristics. It is believed that P-waves arrive firstly and S-waves arrive secondly. Simulations were performed based on real data of Hyuganada earthquake which broke out at southern part of Kyushuu Island in Japan. To our surprise, prediction model built using the earthquake waves in early time can enough precisely predict main huge waves in later time. Lots of experiments lead us to conclude that every slice of data involves P-wave and S-wave. The simulation results suggest the GP-based prediction method can be utilized in alarm systems or dispatch systems in an emergency.

• 보건교육건강증진학회지
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• 제24권4호
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• pp.99-114
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• 2007

Object: To analyze the effect of a media-campaign for "walking exercise participation improvement", which impacted walking-related awareness and behavior change of residents in Seoul. Method: This study used three campaign media including printing information, walking exercise indication board and a public advertisement of cable TV to lead a walking-related awareness change and practice frequency(number of days per week walking) and time(minutes per day walking) of walking exercise. To evaluate the exposure and message-recall levels of a campaign and effects of awareness change and walking practice, this study used a questionnaire survey(N=377). Result: 1) Group of exposure to campaign more participate and had the higher frequency(p=.015) and time(p=.023) in walking exercise and in comparison with group of nonexposure. 2) Group of changed awareness to campaign more participate and had the higher frequency and time in walking exercise and in comparison with group of no changed perception(p <.05). 3) Level of message recall of ${\ulcorner}$printing information${\lrcorner}$ was associated with number of days per week walking, and level of message recall of ${\ulcorner}$public advertisement of cable TV${\lrcorner}$ was associated with minutes per day walking at a statistically significant level(p <.05). Conclusion: These results suggest that media campaign can enhance the success of community-based efforts to promote awareness change and walking practice.

• 한국산업정보학회논문지
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• 제23권3호
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• pp.1-11
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• 2018

이 논문은 OS가 제공하는 소프트웨어 타이머를 사용한 네트워킹 스택의 구현 상황에서 고도의 정확성이 요구되는 시분할 동기적 통신의 신뢰성 문제를 다룬다. IEEE 802.15.4를 목표 프로토콜로 선정해 비컨 동기화의 신뢰성 향상 이슈를 상세히 탐구한다. 먼저, IEEE 802.15.4 비컨 모드의 구현에 소프트웨어 타이머를 사용할 때, 소프트웨어 타이머에 사용되는 하위 하드웨어 타이머 인터럽트의 처리 지연 및 유실과 소프트웨어 타이머 관리 오버헤드 등이 실제로 비컨 동기화의 저해 요인으로 작용한다는 점을 실험을 통해 확인한다. 이러한 상황을 개선하기 위한 제안한 비컨 대기시간 보정기법은 비컨 동기화의 신뢰성을 향상시킨다는 점을 입증한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.733-735
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• 2012

다중프로세서 시스템 상에서 합성 이용율을 이용한 비주기 태스크들의 프로세서 이용율 계산 시 태스크가 실제 모든 실행시간을 종료하여 더 이상의 실행시간을 갖지 않더라도 현재요청집합에 속해 있다면 실행시간과 종료시한을 합성 이용율에 포함하기 때문에 실제 스케줄링 가능한 태스크들이 실행 불가능한 경우로 판단되는 문제점을 가지고 있다. 본 논문에서는 이러한 문제점을 해결하여 다중 프로세서 시스템에서 더 많은 비주기 태스크들이 스케줄링 가능 하도록 개선된 합성 이용율 방법을 제시 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1555-1570
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• 2016

For monitoring forest fires, a real-time system to prevent fires in wider areas should be supported consistently. However, there has still been a lack of the support for real-time system related to forest fire monitoring. In addition, the 'real-time' processing in a forest fire detection system can lead to excessive consumption of energy. To solve these problems, the intelligent data acquisition of sensing nodes is required, and the maximum energy savings as well as rapid and accurate detection by flame sensors need to be done. In this regard, this paper proposes a node built-in filter algorithm for intelligent data collection of sensing nodes for the rapid detection of forest fires with focus on reducing the power consumption of the remote sensing nodes and providing efficient wireless sensor network-based forest environment monitoring in terms of data transmission, network stability and data acquisition. The experimental result showed that battery life can be extended through the intelligent sampling of remote sensing nodes, and the average accuracy of the measurement of flame detection based on the distance is 44%.

• 한국정보통신학회논문지
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• 제14권12호
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• pp.2649-2656
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• 2010

MC-DS-CDMA 전송 방식에서는 서로 직교성이 있는 여러 개의 부반송파들을 사용함으로서 주파수 다이버시티 효과를 얻을 수 있어 우수한 성능의 전송이 가능하다. 본 논문에서는 시변 채널 환경 하에서 MRRC 안테나 다이버시티 기법을 사용하는 상향링크 MC-DS-CDMA 시스템의 성능을 분석한다. 시변 페이딩 채널은 전송되는 MC-DS-CDMA 신호에 인접 부반송파 간섭을 발생시켜 수신단에서 데이터 재생 시 비트 오류율이 증가된다. 이러한 다중 반송파 전송 방식에서는 또한 채널 추정 에러, 비선형 전력 증폭기 및 송수신간 반송 주파수 편차 등에 의하여 시스템 성능이 열화 된다. 그러므로 위와 같은 영향들을 모두 고려하여 송신 신호가 다중경로 페이딩 채널을 통하여 전송될 때의 데이터 비트 오류율 성능을 분석한다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2021년도 제64차 하계학술대회논문집 29권2호
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• pp.41-44
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• 2021

In this paper, we propose a monitoring system that can monitor gas leakage concentrations in real time and forecast the amount of gas leaked after one minute. When gas leaks happen, they typically lead to accidents such as poisoning, explosion, and fire, so a monitoring system is needed to reduce such occurrences. Previous research has mainly been focused on analyzing explosion characteristics based on gas types, or on warning systems that sound an alarm when a gas leak occurs in industrial areas. However, there are no studies on creating systems that utilize specific gas explosion characteristic analysis or empirical urban gas data. This research establishes a deep learning model that predicts the gas explosion risk level over time, based on the gas data collected in real time. In order to determine the relative risk level of a gas leak, the gas risk level was divided into five levels based on the lower explosion limit. The monitoring platform displays the current risk level, the predicted risk level, and the amount of gas leaked. It is expected that the development of this system will become a starting point for a monitoring system that can be deployed in urban areas.

• 기술혁신연구
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• 제10권2호
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• pp.107-129
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• 2002

Expansion and enhancement of information and communication infrastructure can create a market closer to an ideal type for a perfect competition, utilizing a cyber space in the network (with the expanded usage of Internet and e-commerce) and it could be a market of a monopolistic form. The government can take one of the two approaches responding to this monopolization of the digital market. First, the government maintains laissez-faire policy since the monopoly cannot be maintained over a long period of time due to an increasing in the production, decrease in the price, profit resulting from this and rapid technology evolution. Second, the government can actively interrupt the monopolization of the digital market. Monopolization in a digital market can lead to a market failure. Unstable market structure and too much frequent merger and acquisition contribute to making the digital market very dynamic. Information goods exchanged in the digital market have the features of very low marginal cost required to copy the original product whereas its initial fixed cost is very high. This explains why the information products are not priced based on the existing marginal price determination principles and why companies producing them have various product sales strategies (price/product differentiation strategy, and other sales strategies).

• 한국컴퓨터정보학회논문지
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• 제24권9호
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• pp.51-58
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• 2019

Temporal analysis is very useful and important for digital forensics for reconstructing the timeline of digital events. Forgery of a file's timestamp can lead to inconsistencies in the overall temporal relationship, making it difficult to analyze the timeline in reconstructing actions or events and the results of the analysis might not be reliable. The purpose of the timestamp change is to hide the data in a steganographic way, and the other purpose is for anti-forensics. In both cases, the time stamp change tools are requested to use. In this paper, we propose a classification method based on the behavior of the timestamp change tools. The timestamp change tools are categorized three types according to patterns of the changed timestamps after using the tools. By analyzing the changed timestamps, it can be decided what kind of tool is used. And we show that the three types of the patterns are closely related to API functions which are used to develop the tools.

• 한국지리정보학회지
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• 제4권3호
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• pp.51-60
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• 2001

GPS를 이용하여 차량의 통행과 관련된 행태를 미시적으로 분석할 수 있다. 2대의 시험차량에 GPS장비를 탑재하고 통행함으로서 순간적으로 발생하는 통행특성을 파악할 수 있기 때문이다. 연속류에 있어서 선행차량과 추종차량의 속도차이와 차두간격의 변화는 용량 및 안전과 관련된 중요한 변수이다. 본 연구는 국도 4호선과 28호선을 통행하면서 수집된 자료를 이용하여 이들을 분석하였다. 주행시의 속도차이에 대한 변화의 폭은 3.0%이내로 경미하였다. 하지만, 가 감속시의 속도차이는 시작 직후보다 4초 정도 경과한 뒤의 차이가 더 큰 것으로 나타났다. 차두간격도 이와 비슷한 변화를 나타내었다. 이와는 별개로 안전성을 고려한 감속 직전의 차두간격에 대해서도 분석하였다. 모형에 의한 이론치와 실측치를 비교하였는데, 실측치가 평균 12.52% 더 짧은 것으로 분석되었다. 이로써 시험대상구간에서 운전한 추종차량은 선행차량의 급감속시 추돌사고를 야기할 가능성이 높음을 알 수 있다.