• Journal of Astronomy and Space Sciences
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• v.27 no.3
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• pp.221-230
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• 2010

A 4+12+16 amplitude phase shift keying (APSK) modulation outperforms other 32-APSK modulations in a nonlinear additive white Gaussian noise (AWGN) channel because of its intrinsic robustness against AM/AM and AM/PM distortions caused by the nonlinear characteristics of a high-power amplifier. Thus, this modulation scheme has been adopted in the digital video broadcasting-satellite2 European standard. And it has been considered for high rate transmission of telemetry data on deep space communications in consultative committee for space data systems which provides a forum for discussion of common problems in the development and operation of space data systems. In this paper, we present an improved bits-to-symbol mapping scheme with a better bit error rate for a 4+12+16 APSK signal in a nonlinear AWGN channel and propose a simple signal detection algorithm for the 4+12+16 APSK from the presented bit mapping.

• Journal of IKEEE
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• v.24 no.2
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• pp.403-408
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• 2020

Photovoltaic (PV) has both intermittent and uncertainty in nature, so it is difficult to accurately predict. Thus anomaly detection technology is important to diagnose real time PV generation. This paper identifies a correlation between various parameters and classifies the PV data applying k-nearest neighbor and dynamic time warpping. Results for the two classifications showed that an outlier detection by a fault of some facilities, and a temporary power loss by partial shading and overall shading occurring during the short period. Based on 100kW plant data, machine learning analysis and test results verified actual outliers and candidates of outlier.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.289-295
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• 2006

The Musical Slide Show MAF, which currently being standardized by MPEG, conveys the concept of combining several established standard technologies in a single file format. It defines the format of packing up MP3 audio data, along with MPEG-7 Simple Metadata Profile and MPEG-21 Digital Item Declaration metadata; with JPEC images and optional text, and synchronizes them all together to create a slideshow of JPEC image data associated to MP3 audio data during the audio playback. The implementation of Musical Slide Show MAF can be a music karaoke file where users can sing along while listening to the music, view the JPEG slideshow and reading the lyrics; or a story-telling file where users can listen to the narrated story by looking at the related illustration slideshow of the story In this paper we present the tool to producing the Musical Slide Show MAF contents. Regardless the knowledge of user on the MAF file format, the authoring tool simplify the manner of packaging several multimedia contents into single file.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1535-1538
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• 2002

The flexibility of content addressable mem-ory (CAM) can greatly be extended through the use of trits (ternary digits) Trits consist of binary logical values “0” and “1” with addition of “x” (“dont’t care”). The “dont’t care“is extremely useful for providing com- pact representation of sets of bit strings. In this paper, we propose a new ternary CAM with Hamming distance search functions. Each memory cell in the CAM consists of a pair of lambda diodes which can store trits, namely, a logical “0”, “1” and “x” (“dont’t care“). The CAM can compare stored data and an input data in parallel, and find stored data with Hamming distance within a certain range (“near match“). Also, the interrogation characteristics of the ternary CAM are analyzed in detail. Furthermore, the results obtained these analyses are fully confirmed by simulation using the circuit analysis program HSPICE.

• Journal of Distribution Science
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• v.22 no.7
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• pp.33-42
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• 2024

Purpose: The furniture industry has a huge potential for growth in Indonesia. Due to Indonesia's vast natural resources, furniture designers, makers, and retailers are given ease of access. The research analyzes the influence of service quality, promotion, product, and price on brand image and purchase intention in Indonesia's furniture distribution channels. Research design, data, and methodology: The variables used are service quality, promotion, product, price, brand image, and purchase intention. This research is cross-sectional research, which will be conducted among the furniture consumers in Indonesia, from the Instagram followers of a community as of 31 July 2023 with 837.5 thousand followers. The tools that will be used are surveys, conducted according to the sample size and processed using SMARTPLS 4 and the SEM-PLS model. Results: The findings urge that some variables have a significant influence on purchase intention directly but become less significant when influenced by brand image. Some variables can influence purchase intentions significantly through brand image, even if the certain variable did not have a significant influence on purchase intention directly. Conclusions: By knowing the significance of the variables towards brand image and purchase intention, ones with major influence can be implemented as a strategy to improve marketing in Indonesian furniture distributors.

• Current Optics and Photonics
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• v.2 no.5
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• pp.422-430
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• 2018

Rolling shutter operation of CMOS cameras can be utilized in optical camera communications in order to transmit data from an LED to mobile devices such as smart-phones. From temporally modulated light, a spatial flicker pattern is obtained in the captured image, and this is used for signal recovery. Due to the degradation of rolling shutter images caused by light smear, motion blur, and focus blur, the conventional decoding schemes for rolling shutter cameras based on the pattern width for 'OFF' and 'ON' cannot guarantee robust communications performance for practical uses. Aside from conventional techniques, such as polynomial fitting, histogram equalization can be used for blurry light mitigation, but it requires additional computation abilities resulting in burdens on mobile devices. This paper proposes a transition-based decoding scheme for rolling shutter cameras in order to offer simple and robust data decoding in the presence of image degradation. Based on the designed synchronization pulse and modulated data symbols according to the LED dimming level, the decoding process is conducted by observing the transition patterns of two sequential symbol pulses. For this, the extended symbol pulse caused by consecutive symbol pulses with the same level determines whether the second pulse should be included for the next bit decoding or not. The proposed method simply identifies the transition patterns of sequential symbol pulses other than the pattern width of 'OFF' and 'ON' for data decoding, and thus, it is simpler and more accurate. Experimental results ensured that the transition-based decoding scheme is robust even in the presence of blurry lights in the captured image at various dimming levels

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.566-572
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• 2014

We propose a two-way multi-hop relaying scheme improving the throughput as well as enlarging the coverage for ship-to-ship communications in multi-ship marine networks. The proposed scheme reduces the time slots required for the data exchange by designing data transmission and network coding procedures in a sophisticated way based on two-phase digital network coding. Simulation results show that the proposed two-way multi-hop relaying scheme improves the throughput of the conventional one about 5/3 times.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.83-86
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• 2020

본 논문에서는 네트워크 이상치 탐지를 위하여 정상 데이터만을 활용한 메모리 기반 정상성 학습 모델을 제안한다. 오토인코더를 기반으로 정상 데이터의 특징을 표현하는 프로토타입을 생성할 수 있도록 신경망을 구성하고, 네트워크 데이터의 특성을 반영하여 쿼리의 수를 한 개로 고정하며, 사용되는 프로토타입의 수를 지정한 값으로 고정하여 모든 프로토타입에 정상 데이터의 특징을 반영할 수 있는 학습 방법을 제안한다. 해당 모델을 네트워크 이상치 탐지 데이터 세트인 Kyoto Honeypot, UNSW-NB15, CICIDS-2018에 적용하여 본 결과 Kyoto Honeypot에서는 0.821, UNSW-NB15에서는 0.854, CICIDS-2018에서는 0.981의 AUROC를 달성했다.

• Journal of Multimedia Information System
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• v.6 no.1
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• pp.23-30
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• 2019

A communications profile is a system that acquires information from communication links to an ambulance or other vehicle moving on a road and compiles a database based on this information. The equipment (six sets of HDTVs, fish-eye camera, satellite antenna with tracking system, and receiving power from the satellite beacon of the N-star) mounted on the roof of the vehicle, image data were obtained at Yokohama Japan. From these data, the polygon of the building was actually produced and has arranged on the map of the Geographical Survey Institute of a 50 m-mesh. The optical study (relationship between visibility rate and elevation angle) were performed on actual data taken by fish-eye lens, and simulated data by 3D-Map with polygons. There was no big difference. This 3D map system then predicts the communication links that will be available at a given location. For line-of-sight communication, optical analysis allows approximation if the frequency is sufficiently high. For non-line-of-sight communication, previously obtained electric power data can be used as reference information for approximation in certain cases when combined with predicted values calculated based on a 3D map. 3D maps are more effective than 2D maps for landing emergency medical helicopters on public roadways in the event of a disaster. Using advanced imaging technologies, we have produced a semi-automatic creation of a high-precision 3D map at Yokohama Yamashita Park and vicinity and assessed its effectiveness on telecommunications and ambulatory merits.

• Journal of Astronomy and Space Sciences
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• v.37 no.4
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• pp.219-228
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• 2020

A CubeSat platform has become a popular choice due to inexpensive commercial off-the-shelf (COTS) components and low launch cost. However, it requires more power-efficient and higher-data rate downlink capability for space applications related to remote sensing. In addition, the platform is limited by the size, weight and power (SWaP) constraints as well as the regulatory issue of licensing the radio frequency (RF) spectrum. The requirements and limitations have put optical communications on promising alternatives to RF communications for a CubeSat platform, owing to the power efficiency and high data rate as well as the license free spectrum. In this study, we analyzed the performance of optical downlink communications compatible with CubeSat platforms in terms of data rate, bit error rate (BER) and outage probability. Mathematical models of BER and outage probability were derived based on not only the log-normal model of atmospheric turbulence but also a transmitter with a finite extinction ratio. Given the fixed slot width, the optimal guard time and modulation orders were chosen to achieve the target data rate. And the two performance metrics, BER and outage data rate, were analyzed and discussed with respect to beam divergence angle, scintillation index and zenith angle.