• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.10
• /
• pp.1284-1289
• /
• 2016

Recently, digital image processing is applied a lot to the broadcasting, communication, computer graphic, and medical sectors. It generates noise when data is transmitted. There are many kinds of noises that add to the image such as salt and pepper noise, AWGN, and complex noise. Thus, this study divides the corrupted image into four4 areas and estimates the types of noises each pixel, and this study suggested a switching filter that separates the estimated into salt and pepper noise and AWGN. In the case that center pixel of local mask is corrupted by salt and pepper noise, it used a histogram probability weighting of subdivided area. Also, in case that it is corrupted by AWGN, algorithm that is applied to with different weights given for the distribution of each area with using subdivided area's distribution was suggested. For an objective comparison and conclusion, this study used PSNR and compared to existing methods.

• KIPS Transactions on Computer and Communication Systems
• /
• v.8 no.12
• /
• pp.297-304
• /
• 2019

The technological advances such as communication, sensor, and artificial intelligence lead smart factory construction. Smart factory aims at efficient process control by utilizing data from the existing automation process and intelligence technology such as machine learning. As a result of constructing smart factory, productivity increases, but costs increase. Therefore, small companies try to make a step-by-step transition from existing process to smart factory. In this paper, we have proposed a remote control system that support data collection, monitoring, and control for manufacturing equipment to support the construction of CNC cutting machine based small-scale smart factory. We have proposed the structure and design of the proposed system and efficient sensing data transmission scheme. To check the feasibility, the system was implemented for CNC cutting machine and functionality verification was performed. For performance evaluation, the web page access time was measured. The results means that the implemented system is available level.

• The Journal of the Korea Contents Association
• /
• v.13 no.9
• /
• pp.1-9
• /
• 2013

In recent, the cloud computing makes it possible to provide the on-demand provision of software, hardware, and data as a service in various IT fields. This paper uses the cloud computing techniques for the real time broadcasting service of virtual 3D contents. However, the existing related solutions have many problems that the load of the server is rapidly increased or the cost of the server is very high when the number of service users is increased. Therefore, we propose a new application virtualization method to solve these problems. It promises their stable operations in multi-user services because the proposed method does not execute the rendering commands of the application at the host server but delivers and executes them to clients via the Internet. Our performance experiments show that our proposed method outperforms the existing methods.

• Journal of Satellite, Information and Communications
• /
• v.1 no.1
• /
• pp.59-64
• /
• 2006

The broadband power detector for power amplitude envelope detection of the direct-conversion Six-port output signal was designed and implemented in this paper. The power detector should be linearly operated to produce the linear amplitude and phase signal for input RF signals in required broadband frequency range. The power detector should be designed under conditions of matching circuit with low VSWR, which protect unbalanced phase signal from reflection signal due to mismatch between the output port of a six-port and the input port of a power detector. The designed power detectors, which were implemented in L-band with 50 ohm matching and Ku-band with multiple LC matching circuits and isolator, respectively, were analyzed in viewpoints of the utilization as a power detector of direct conversion Six-port. The dynamic range of designed power detectors were also measured and rvaluated as a power detector of Six-port circuit.

• Journal of KIISE:Databases
• /
• v.36 no.3
• /
• pp.189-197
• /
• 2009

Top-k queries are important to many wireless sensor applications. Conventional Top-k query processing algorithms install a filter at each sensor node and suppress unnecessary sensor updates. However, they have some drawbacks that the sensor nodes consume energy extremely to probe sensor reading or update filters. Especially, it becomes worse, when the variation ratio of top-k result is higher. In this paper, we propose a novel Top-k query processing algorithm for energy-efficiency. First, each sensor determines its priority as the order of data gathering. Next, sensor nodes that have higher priority transmit their sensor readings to the base station until gathering k sensor readings. In order to show the superiority of our query processing algorithm, we simulate the performance with the existing query processing algorithms. As a result, our experimental results show that the network lifetime of our method is prolonged largely over the existing method.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.887-887
• /
• 2012

기후변화에 의한 강우패턴의 변화는 강우량 및 강우강도의 증가로 대표되며 국립기상연구소 (2011)에 의하면 현재와 같은 탄소배출이 줄어들지 않는다면 2050년 우리나라의 강수량은 16% 증가하고 일 강수량 80mm 이상의 호우발생일수가 60%이상 증가될 것으로 전망하고 있다. 이와 같이 기후변화로 인해 발생빈도가 증가추세인 집중호우는 산사태와 같은 2차 피해를 유발하고 있으며 강우의 예측 및 실시간 모니터링은 재해 예방 및 수자원관리, 국가 방재역량 강화를 위해 연구되어야 할 분야이다. 이에 본 연구에서는 광역적 강우자료로서 미국 NOAA의 기후예측센터에 의해 제공되는 글로벌 강우량 CMORPH와 지상 강우자료와의 비교 분석을 통해 CMORPH 자료의 수자원 분야 이용 가능성을 분석하는 것을 목적으로 한다. CMORPH는 고급의 시공간적 해상도를 가지며, 단기간의 기후 예측센터 모핑(morphing) 방법에 의한 "CMORPH"라 불리우는 강우평가 알고리즘과 새로운 위성 기반 기술을 이용하여 개발되었다. CMORPH 기술에 의해 생산된 글로벌 강우 추정은 저궤도 위성 수동 마이크로파(passive microwaves, PMW) 관측으로부터 유도되고, 그 형태는 전적으로 정지궤도 위성(geostationary satellite) 적외선(IR) 데이터로부터 얻어진 공간적 전파 정보 (모션 벡터)를 통해 전송된다. 이 기술은 PMW 데이터로부터 유도된 비교적 고품질의 추정 강우를 전파하기 위하여 30분 간격의 정지궤도 위성 IR 이미지로부터 파생된 모션 벡터를 이용하며, 때때로 레이더보다 더 나은 성능을 보이기도 하고(Apip 등 2010), CMORPH의 지역적 제공범위는 $60^{\circ}N-60^{\circ}S$이고 2002년 12월부터 제공하고 있다. 본 연구에서는 CMORPH 자료 중 2002년 12월부터 제공하는 3시간 누가강우 자료를 수집하였고, 자료의 정확도 분석은 갑천유역을 대상으로 하였다. 3시간 누가 강우량을 1일 누가 강우량으로 변환한 후 금강홍수통제소의 갑천 유역 강우관측소 5곳의 강우자료를 티센 평균에 의한 유역 평균강우자료와 비교하였다. 2009년 1년간의 지상관측자료와 CMORPH자료를 비교한 결과 가 0.34 정도로 분석되었으나 추가 연구를 통해 마이크로 웨이브 강우자료 및 3시간 강우자료, 그리고 30분 강우자료의 분석을 통해 다양한 형태의 강우자료 확보뿐만 아니라 광역적인 강우특성 분석도 가능하여 연구 결과의 동아시아지역 등으로 확대 적용할 수 있을 것으로 기대한다.

• Journal of Korea Water Resources Association
• /
• v.41 no.10
• /
• pp.1059-1065
• /
• 2008

Rainfall data is the most basic input data to analyze the hydrological phenomena and can be missing due to various reasons. In this research, a neural network based model to estimate missing rainfall data as approximate values was developed for 12 rainfall stations in the Soyang river basin to improve existing methods. This approach using neural network has shown to be useful in many applications to deal with complicated natural phenomena and displayed better results compared to the popular offline estimating methods, such as RDS(Reciprocal Distance Squared) method and AMM(Arithmetic Mean Method). Additionally, we proposed automated data reconciliation systems composed of a neural network learning processer to be capable of real-time reconciliation to transmit reliable hydrological data online.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.4
• /
• pp.677-684
• /
• 2017

Smart devices are used in a variety of industries, because applications for them are easy to develop and portable. However, industrial equipment can cause security problems for information and accidents when controlling the actuator of the equipment at a remote location. In this paper, we studied methods of solving these problems and the advantages of applying smart control systems to industrial equipment. We propose a manual manipulation method using queries and a smart control access procedure for controlling equipment using a smart device. In addition, we propose a data transmission method employing multiple encryption protocols and a user authentication method using unique information from the smart device and Q & A as the communication data protection and user authentication methods, respectively. In order to evaluate its performance, an operation test of the smart control system and user authentication comparison experiment were performed. In order to understand the advantages of applying the smart control system to the equipment, we conducted a comparative experiment with a teach pendant and evaluated its reaction time in case of error.

• Journal of Advanced Navigation Technology
• /
• v.17 no.5
• /
• pp.497-505
• /
• 2013

In TETRA(TErrestrial Trunked RAdio) standard, TMO(Trunked Mode Operation) communicates with the UE through the base station and it has a higher priority than DMO(Direct Mode Operation) which communicates with UE directly for channel allocation. As a result, the UE needs an algorithm which restricts the frequency allocation by TMO so that DMO can have a successful communication within the network. However, the TETRA DMO standard does not consider this issue. In this paper, we propose an active DMO channel selection algorithm which allocates a channel based on some additional information such as channel usage state of TMO and channel utilization of DMO. The experimental results show that the proposed algorithm outperforms existing DMO channel allocation scheme in terms of the transmission efficiency.

• Journal of KIISE:Software and Applications
• /
• v.26 no.11
• /
• pp.1306-1313
• /
• 1999

본 연구는 인터넷 기반 공유가상공간에서 시스템의 확장성을 유지하기 위하여 이동객체를 대상으로 하는 이벤트 필터링 기법을 제안하고자 한다. 제안된 다중격자 모델 기법은 이동객체의 경로 상에서 대표적인 이벤트를 샘플링하는 방식을 사용한다. 이 방식은 메시지 트래픽의 양을 동적으로 조절하기 위하여 이동객체 간의 관심정도 정보를 수치적으로 변환하여 이벤트 갱신빈도에 반영한다. 대량의 이동객체를 생성하여 제안된 기법을 적용한 성능평가 실험에서 기존의 방식에 비하여 평균 메시지 전송량이 50%이상 감소하는 것으로 확인할 수 있었다. 다중격자 모델은 참여자의 수와 메시지 트래픽 상황에 따라 가상환경의 공유 QoS를 동적으로 조절할 수 있으며, 인터넷 상에서 다수 사용자를 위한 3차원 가상사회 구축 및 온라인 네트워크 게임 개발 등에 활용될 수 있을 것이다.Abstract This paper proposes an event filtering technique that can dynamically control a large amount of event messages produced by moving objects like avatars or autonomous objects in a distributed virtual environment. The proposed multi-level grid model technique uses the method that extracts the representative events from the paths of moving objects. For dynamic control of message traffics, this technique digitizes the DOIs of the avatars and reflects the interest information controlling the frequency of message transmission. For the performance evaluation, a large number of moving objects were created and the model was applied to these avatar groups. In the experiments, more than 50% of messages have been reduced in comparison with the existing AOI-based filtering techniques. The proposed technique can dynamically control the QoS in proportion to the number of users and the amount of messages where a large number of users share a virtual space. This model can be applied to the development of 3D collaborative virtual societies and multi-user online games in the Internet.