• Journal of Information Technology Applications and Management
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• 제29권6호
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• pp.63-80
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• 2022

In this paper, we study structural changes and performance gains in condition-based maintenance process redesign when mobile IoT technology is embedded into urban railway rolling stock. We first develop condition-based maintenance To-Be process model in accordance with the IoT deployment scheme. Secondly, we draw upon theoretical framework of redesign process analysis to develop performance evaluation method suitable to predictive maintenance shift from As-Is ordinary maintenance practice. Subsequently, To-Be process performance evaluations are conducted adopting both the quantitative and qualitative method for time, cost, and dependability dimensions. The results ascertain the considerable benefits captured through detection abnormality prior to actual rolling stock failure occurrence, and details of performance improvements and enhancement of standardization level is revealed. The procedures and results presented in this paper offers useful insights in the fields of IoT economic analysis, condition based maintenance, and business process redesign.

• 방송공학회논문지
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• 제24권7호
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• pp.1221-1227
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• 2019

This paper describes a low-density parity-check (LDPC) coded index modulated orthogonal frequency division multiplexing with quasi-orthogonal sequence (IM-OFDM-QOS) and provides performance evaluations of the proposed system. By using QOS as the spreading code, IM-OFDM-QOS scheme can improve the reception performance than IM-OFDM-SS scheme for a given data rate. On the other hand, LDPC code is widely used to the latest wireless communication systems as forward error correction (FEC) scheme and has Shannon-limit approaching performance. Therefore, by applying LDPC code to IM-OFDM-QOS system as FEC scheme, the reception performance can be further improved. Simulation results show that significant signal-to-noise ratio (SNR) gains can be obtained for LDPC coded IM-OFDM-QOS system compared to the LDPC coded IM-OFDM-SS system and the SNR gain increases with the higher code rate.

• 전자공학회논문지A
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• 제33A권11호
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• pp.10-18
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• 1996

In this paper, performance of a hybrid direct-sequency/slow-frequency-hopped (DS/SFH) spread-spectrum (SS) system with coherent BPSK modulation is analyzed. The bit error probability is derived over a frequency=-selective rician fading channel in the presence of multiple tone jamming. The fading channel is modeled as the wide-sense stationary uncorrelated scattering (WSSUS) model. Numerical evaluations are presented for some combinations of system parameters. The performance of a hybrid DS/SFH SS system is shown to be inferior to that of a ure DS SS system at low jamming-to-signal power ratio (JSR). At high JSR, the performance of a pure DS SS system is shown to be the smae as the worst case performance of a hybrid DS/SFH SS system.

• 한국컴퓨터정보학회논문지
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• 제3권4호
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• pp.70-77
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• 1998

시스템 성능평가의 대상은 하드웨어와 소프트웨어로 나누어 평가할 수 있다. 현재 하드웨어의 평가는 부문별로 많이 개발되어 왔지만, 소프트웨어의 성능은 그 대응책 없이 개발되어 온 사례가 많다. 물론 외국에서는 소프트웨어 성능공학 쪽으로 많은 관심을 기울러 소프트웨어 개발도구 및 방법론이 성능공학 문제와 연관하여 제안되고 있다. 그러나 우리나라에서는 거의 전무한 상태인 것은 사실이다. 그래서 본 연구에서는 소프트웨어개발 도구 및 개발방법론을 정의하여 그 내용을 비교하고자 한다.

• Asian-Australasian Journal of Animal Sciences
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• 제29권2호
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• pp.195-203
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• 2016

This study was conducted to evaluate the effect of dietary supplementation with rice bran, flax seed, or sunflower seed to finishing native Korean cattle (Hanwoo) on growth performances, carcass characteristics, fatty acid composition, free amino acid and peptide contents, and sensory evaluations of Longissimus muscle (LM). A total of 39 Hanwoo steers (average age of 22.2 mo and average body weight (BW) of 552.2 kg) were randomly divided into Control, rice bran (RB), flax seed (FS), or Sunflower seed (SS) groups. The steers were group fed for 273 d until they reached an average age of 31.2 mo. Final BW was 768.2, 785.8, 786.2, and 789.0 kg, and average daily gain was 0.79, 0.85, 0.82, and 0.84 kg for the Control, RS, FS, and SS groups, respectively (p>0.05). Fat thickness of the FS group (19.8 mm) was greater (p<0.05) than that of the other groups. Final yield grade converted into numerical values was 2.0 for the RB group, 1.7 for the Control and SS groups, and 1.4 for the FS group. Marbling degrees for the Control, SS, RB, and FS groups were 5.3, 5.1, 4.7, and 4.6, respectively. Percentages of palmitic acid ($C_{16:0}$), stearic acid ($C_{18:0}$), and arachidic acid ($C_{20:0}$) in the LM were not different among the groups. Palmitoleic ($C_{16:1}$) acid was higher (p<0.05) in the SS group. The concentration of oleic acid was highest (p<0.05) in the Control group (47.73%). The level of linolenic acid ($C_{18:3}$) was 2.3 times higher (p<0.05) in the FS group compared to the other groups. Methionine concentration was (p<0.05) higher in FS (1.7 mg/100 g) and SS (1.2 mg/100 g) steers than in the Control or RB groups. Glutamic acid and ${\alpha}$-aminoadipic acid (${\alpha}$-AAA) contents were (p<0.05) higher in the FS group compared to the other groups. LM from the FS group had numerically higher (p>0.05) scores for flavor, umami, and overall palatability in sensory evaluations. In conclusion, supplementation of flax seed to diets of finishing Hanwoo steers improved sensory evaluations which might have been caused by increases in flavor related amino acids such as methionine, glutamic acid and ${\alpha}$-AAA and peptides, anserine and carnosine, and their complex reactions.

• 한국디지털건축인테리어학회논문집
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• 제13권4호
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• pp.33-39
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• 2013

As lighting energy consumption in buildings occupies high ratio, technical researches to solve it have been constantly carried out. However, basic studies on light environment performance evaluation is actually deficient and only at a level of a simple illumination monitoring. Thus, this study has suggest a light environment energy performance evaluation based on actual residence environments to allow setting lighting interoperation and user required illumination. Conclusions from the study are as follows: 1) As the performance evaluation suggested by this study has not only derived lighting energy usage as well as monitored simple indoor illumination distribution, it is quantitative and allows derivation of visual results. 2) The performance evaluation suggested by this study allows inputs of user required illumination through the performance evaluation server, which is able to support for performance evaluations for various works and users. 3) This study has verified validity of the performance evaluation method by analyzing results of lighting energy reduction by executing performance evaluation on changes of light shelf that is a natural lighting system through the suggested performance evaluation method. This study is significant from a viewpoint that it has suggested a quantitative performance evaluation method on the basis of actual residence environments. Those researches concerned on the energy performance evaluation should be constantly progressed from an aspect that they are another solution of the energy problems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권3호
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• pp.324-340
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• 2010

Video streaming service over wireless networks is a challenging task because of the changes in the wireless channel conditions that can occur due to interference, fading, and station mobility. To provide an efficient wireless video streaming service, the rate adaptation scheme should improve wireless node performance and channel utilization. Moreover, the quality adaptation scheme should be considered at the streaming application. To meet these requirements, we propose a new cross-layer design for video streaming over wireless networks. This design includes the rate and quality adaptation schemes. The rate adaptation scheme selects the optimal transmission mode and resolves the performance anomaly problem. Based on performance improvement by the proposed rate adaptation scheme, our quality adaptation scheme improves the quality of video streaming. Through performance evaluations, we prove that our cross-layer design improves the wireless channel utilization and the quality of video streaming.

• 한국정보처리학회논문지
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• 제3권4호
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• pp.983-991
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• 1996

본 논문에서는 디스크캐쉬 관리 기법의 하나인 동반쓰기 기법을 개선한 복합동반 쓰기 기법을 제안하고 그 성능을 평가하였다. 제안된 기법의 성능 평가를 위하여 디스 크 시스템을 모델화 하여 실제 디스크시스템에 근접한 시뮬레이션 모델을 구현하고 trace-driven 시뮬레이션을 수행하였다. 시뮬레이션의 결과 본 연구에서 제안된 복합 동반쓰기 기법이 기존의 동반쓰기 기법에 비하여 우수한 성능을 나타냄을 증명하였다.

• 산업공학
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• 제17권4호
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• pp.440-449
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• 2004

The OERA(Offensive Earned-Run Average) is a methodology for the performance evaluation of baseball players, which is based on a well- known Markov chain model. The DEA(Data Envelopment Analysis) is an LP-based evaluation technique for performance analysis of DMUs (Decision Making Units), whose production activities are characterized by multiple inputs and outputs. In this paper, the performances of Korean professional baseball players are analytically evaluated using both OERA and DEA methods. We discuss methodological strengths and drawbacks of two kinds of baseball evaluation techniques, by comparing both results. Finally to overcome the shortcomings of both methods, we develop a new analytical approach for baseball evaluation by combining OERA with DEA.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제12권2호
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• pp.119-131
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• 2008

The paper considers the computation method in the performance evaluation of cellular network in the phase-type distribution assumptions that the channel holding times induced from mobility are modeled by well-fitted distributions to reflect an actual situation. When ww consider a phase-type distribution model instead of exponential distribution, the complexity of the computation increase exponential even though the accuracy is improved. We consider an efficient numerical algorithm to compute the performance evaluations in cellular networks such as a handoff call dropping probability, new call blocking probability, and handoff arrival rate. Numerical experiment shows that numerical analysis results are well approximated to the results of simulation.