• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.636-642
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• 2019

In this paper, we analyzed BER (Bit Error Rate) communication performance according to the detection order of MMSE (Minimum Mean Square Error) based soft decision interference cancellation. As the detection order method, antenna index order method, absolute value magnitude order method of channel elements, absolute value sum order method of channel elements, and SNR (Signal Noise Ratio) order method are proposed. BER performance for the scheme was measured and analyzed. As a simulation environment, 16-QAM (Quadrature Amplitude Modulation) modulation is used in an uncoded environment of an M×M multiple-input multiple-output system, and an independent Rayleigh attenuation channel is considered. The simulation results show that the performance gain is about 1.5dB when the SNR-based detection order method is M=4, and the performance gain is about 3.5dB when M=8 and about 3.5dB when M=16. The more BER performance was confirmed, the more the detection order method of the received signal prevented the interference and error spreading occurring in the detection process.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.88-94
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• 2013

In university laboratories, areas of studies are becoming diverse and complicated according to the development of the industry. New forms of potential risk factors are increasing and they are unlike existing ones. In addition, many students are conducting various experiments in the laboratory. Therefore, they could be exposed to risk more often. Despite these risks, people do not recognize university lab safety activities properly and observe safety precautions. They are exposed to various laboratory accidents continually. In this study, we do not apply the present diagnosis method, checklist, but the safety assessment that is widely used in industry. Then we can find lots of hazard that checklist method could miss. This study will use the 4M and Hazard & Operability to design a new Laboratory safety assessments method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1846-1855
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• 2015

In this paper, a precise relative positioning with TD(time differenced) carrier phase measurements from a low-cost GNSS(Global Navigation Satellite System) receiver is proposed and analysed. The proposed method is using carrier phase measurement from a single GNSS receiver that reference receiver is not required and stand alone positioning is possible. TD operation removes the troublesome integer ambiguity resolution problem, and if the time interval is short, other error, such as, ionospheric, tropospheric delay and ephemeris error are effectively eliminated. The error analysis of the proposed method shows that a precise and positioning with carrier phase is possible. The implemented system is evaluated using a real car experiments. The results show that the horizontal positioning error was less than 3m during 10 minutes experiments, which is 4 times more precise than the results of normal code based absolute positioning.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.292-297
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• 2004

본 연구에서는 단일목적 저수지와 다목적 댐의 최적운영을 위하여 전역최적해를 탐색하는 SCE-UA법을 사용하는 비선형계획법을 적용한 최적화 모형을 구성하고 과거 운영자료를 사용하여 모형의 적용성을 검토하고 분석하였다. 또한, 다목적댐의 운영수위 상승으로 인하여 발생하는 추가용수를 댐하류로 추가적으로 공급함에 따른 댐운영상의 문제점과 해결책을 제시했다. 관개용 단일 목적 저수지의 유입량은 하천망 모형인 SSARR 모형을 이용하여 추정하였다. 관개용 단일 목적저수지의 용수배분을 최적화한 결과, 실측치와 최적방류량간의 상대오차가 $-2.6\~10.5\%$ 범위를 나타냈으며, 비교적 실측방류량과 유사한 형태로 용수를 공급하는 길과를 나타냈다. 다목적 저수지의 최적운영을 위해 발전량, 저수량 및 필요수량의 관계를 목적함수로하는 최적화 모형을 구성하여 섬진강댐의 최적운영에 적용하였다. 섬진강댐의 댐하류 방류량 증가에 따른 운영상의 문제점을 해결하기 위하여 댐하류 유지용수량을 0.17, 0.50, 0.70, 1.0, 1.5, $3.0m^3/sec$ 방류하는 경우로 구분하여 최적운영한 길과, 댐하류 유지용수량이 $1.0m^3/sec$ 이하인 경우에 발전량이 실적평균발전량에 근접한 결과를 나타냈으며, 용수공급량도 계획공급량인 377.4 백만 $m^3$ 보다 $28.9\~100.7$ 백만 $m^3$ 만큼 많은 양을 공급하는 결과를 나타냈다.

• Korean Journal of Environment and Ecology
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• v.12 no.4
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• pp.361-372
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• 1999

Thirty-two plots have been set up and surveyed to investigate the plant community structure and distribution density of Pinus thunbergii-P. densiflora forest in Kojedo District, Hallyo-Haesang National Park. By DCA ordination technique P. thunbergii-P. densiflora forest was classified into P. thunbergii community, P. thunbergii-P. densiflora community, and P. densiflora community. The trend of plant community succession was invalid. The results of simple regression analysis between mean DBH(cm), mean distribution distance(m), and number of individual of P. thunbergii and P. densiflora were as follows: Distribution distance(m) = 0.094$\times$DBH(cm)-0.1248, Number of individual=1,820.1$\times$(cm)$DBH^{-1.6734}$ , Distribution distance(m)=6.6805$\times$Number of $individual^{-0.5425}$ .

• The KIPS Transactions:PartA
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• v.9A no.4
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• pp.519-524
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• 2002

In this paper we study the qualify of sequential coverage analysis under a scenario of distributed stochastic simulation known as MRIP(Multiple Replications In Parallel) in terms of the confidence intervals of coverage and the speedup. The estimator based in the F-distribution was applied to the sequential coverage analysis of steady-state means. in simulations of the $M/M/1/{\infty},\;M/D/I/{\infty}\;and\;M/H_{2}/1/{\infty}$ queueing systems on a single processor and multiple processors. By using multiple processors under the MRIP scenario, the time for collecting many replications needed in sequential coverage analysis is reduced. One can also easily collect more replications by executing it in distributed computers or clusters linked by a local area network.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.101-111
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• 2013

In this study, DEA (Data Envelopment Analysis) was carried out on the four bridges, which have the same extension (L=1,615m), in order to select the most superior, economical method of construction using the LCC concept of each bridge structure in the case of the Ulsan-Pohang double track railway which is scheduled to be constructed. DEA models were analyzed with the CCR model, which was designed for the evaluation of relative efficiency of each model. The initial construction costs, maintenance costs, indirect costs (user costs + indirect loss of social costs), and life cycle costs were used as input variables, and average duration was applied as the output variable. LCC was applied to calculate the input variables, and to get the costs of LCC, 100 years of period and 4.83% of real discount rate were applied, and the costs are classified into initial construction, maintenance, user, and indirect loss of social cost. The analysis results showed that the Method 2 and 3 were evaluated as the most efficient, and the other alternatives were evaluated as the following order; Method 1, the default, and Method 4.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3571-3577
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• 2010

The estimated location coordinator exploration scheme and the E&E(Equivalent distance rate & Estimated location coordinator exploration) compensation algorithm for localization is proposed, and the performance of the E&E is analyzed in this paper. The proposed scheme is adapted to the AEDR(Algorithm for localization using the concept of Equivalent Distance Rate). From several experiments, it is confirmed that the performance of the localization compensation in SDS-TWR is improved from 0.60m to 0.34m in four experimental scenarios, and the performance of the localization compensation ratio of the E&E is also better than that of the AEDR as a level of maximum 15%. It can be thought that the proposed localization compensation algorithm E&E can be sufficiently applicable to various localization applications because the performance of the localization error rate of the E&E is measured as less than 1m in 99% of the total performance experiments.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.3
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• pp.101-113
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• 2015

The purpose of this study is increasing ventilation network usability for urban green space planning by enhancing its practicality and detail. A ventilation network feature extraction technique using roughness length($z_0$) was proposed. Continuously surfaced DZoMs generated from $z_0$(cadastral unit) using three interpolations(IDW, Spline, and Kriging) were compared to choose the most suitable interpolation method. Ventilation network features were extracted using the most suitable interpolation technique and studied with land cover and land surface temperature by spatial overlay comparison. Results show Kriging is most suitable for DZoM and feature extraction in comparison with IDW and Spline. Kriging based features are well fit to the land surface temperature(Landsat-7 ETM+) on summer and winter nights. Noteworthy is that the produced ventilation network appears to mitigate urban heat loads at night. The practical use of proposed ventilation network features are highly expected for urban green space planning, though strict validation and enhancement should follow. (1) $z_0$ enhancement, (2) additional ventilation network interpretation and editing, (3) linking disconnected ventilation network features, and (4) associated dataset enhancement with data integrity should technically preceded to enhance the applicability of a ventilation network for green space planning. The study domain will be expanded to the Seoul metropolitan area to apply the proposed ventilation network to green space planning practice.

• Journal of Korea Water Resources Association
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• v.37 no.4
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• pp.293-304
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• 2004

Sedimentation basin plays an important role in urban water treatment, and there are many complicated phenomena which need to be understood for efficient design and control of it. Especially, the study on the improvement of settling efficiency is required. In this study, commercial CFD (Computational Fluid Dynamics) program, FLUENT, and particle tracking method were used to simulate the flow in sedimentation basin, and to predict the settling efficiency. Computational domain of real scale was made, and detail factors such as porous wall, and outlet trough were considered instead of being simplified. The simulation results were compared with the experimental data to calibrate the parameters of particle tracking method. Sensitivity analysis showed that the particle diameter had more significant effects on settling efficiency than the particle density. The computation results gave the best agreements with the experimental data, when the value of particle diameter was 26.5 ${\mu}{\textrm}{m}$.