• 기술사
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• 제33권1호
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• pp.51-60
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• 2000

The mitigation technique is to minimize influences to the environments, and it is one of the environmental management(or administration) to techniques. Its objective is to create sustainable environment by keeping human assistance to the environment as minimal as possible. It restores, creates, enhances, and most importantly preserves the environment by avoiding, minizing, rectifying, eliminating, and compensating the natural circumstances The evaluation of adverse effects to the environment and their reduction is as follow: HEP(Habitat Evaluation Procedure) WET(Wet land evaluation technique) HGM(Hydro Geomorphic Assessment) BEST(Biological Evaluation Standardized Technique) Since there are both pro and cons in the American and Japanese mitigation methods, it is hard to choose which one is better.

• Journal of Communications and Networks
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• 제9권2호
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• pp.159-166
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• 2007

In this paper, we propose an efficient and robust interference mitigation technique based on a nullsteering multi-user multiple-input multiple-output (MU-MIMO) spatial division multiple access (SDMA) scheme for frequency sharing between IMT-advanced and fixed satellite service (FSS) in the 3400-4200 and 4500-4800 MHz bands. In the proposed scheme, the pre-existing precoding matrix for SDMA unitary precoded (UPC) MIMO proposed by the authors is modified to construct nulls in the spatial spectrum corresponding to the direction angles of the victim FSS earth station (ES). Furthermore, a numerical formula to calculate the power of the interference signal received at the FSS ES when IMT-Advanced base stations (BS) are operated with the interference mitigation technique is presented. This formula can be derived in closed form and is simply implemented with the help of simulation, resulting in significantly reduced time to obtain the solution. Finally, the frequency sharing results are analyzed in the co-channel and adjacent channel with respect to minimum separation distance and direction of FSS earth station (DOE). Simulation results indicate that the proposed mitigation scheme is highly efficient in terms of reducing the separation distance as well as robust against DOE estimation errors.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.916-924
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• 2015

Electromagnetic Interference (EMI) is a system to system or environment to system phenomenon. The literature survey proved that the Randomized Pulse Width Modulation (RPWM) technique is a promising technique to reduce EMI. A new Constant Trailing Edge, Randomized Pulse Width Modulation (CTERPWM) technique is proposed in this paper. The effect of the proposed RPWM technique for mitigation of conducted-EMI on Cuk converter operating in Continuous Conduction Mode (CCM) is simulated and tested. In this paper, the analytical expressions for the Power Spectral Density (PSD) are derived for the proposed RPWM technique and are validated by experimental measurements. The effectiveness of the proposed RPWM technique on the mitigation of conducted-EMI is verified comparing simulation and experimental results and it is identified that both the results are almost similar with allowable experimental deviations. The comparative investigation proves that the proposed RPWM technique can mitigate and spread the dominant peaks of conducted-EMI over the complete spectrum for the Cuk converter. Based on the investigation the CTERPWM technique is recommended for adoption.

• 한국방재학회지
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• 제5권4호
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• pp.94-105
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• 2005

• 한국방재학회 논문집
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• 제11권3호
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• pp.63-73
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• 2011

본 연구는 방재분야의 교육과정 개발을 위해 DACUM 기법을 이용하여 개발한 교육과정과 전문가회의를 통해 개발한 교육 과정을 비교 분석하여 방재분야의 교육과정을 개발하였다. 첫째, DACUM 기법을 이용한 교육과정 개발은 방재분야의 직무를 예방, 대비, 대응, 복구 등 4가지 직무로 구분하고, 각 직무별로 3명의 방재전문가와 1명의 교육전문가가 3회씩의 워크삽을 통해 예방직무에서 9개 과정, 대비 직무에서 12개 과정, 대비 직무에서 7개 과정, 복구 직무에서 4개의 교육과정을 개발하였다. 둘째, 전문가회의를 통해 교육과정을 개발하였다. 전문가회의는 5명의 방재전문가와 3명의 교육전문가가 4회의 회의를 거쳐 35개의 교육과정을 개발하였다. 이를 통해 DACUM 기법과 전문가회의를 통해 도출된 교육과정을 전문가들의 토론을 거쳐 최종적으로 예방 및 대비 직무에서 31개 과정과 대응 및 복구 직무에서 14개의 교육과정을 개발하였으며, 추가적으로 인적재난에서 6개 과정과 관리자별 4개 과정을 개발하였다.

• 한국조경학회지
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• 제28권1호
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• pp.11-18
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• 2000

Taegu is notorious as hot and dry summer among Korea cities. One of the most important goals of the open space planning is to ameliorate urban climate of the city. The objective of this research is to evaluate the thermal mitigation effect of the cool islands in Taegu metropolitan city. Cool islands of this paper includes parks and rivers surrounded by or adjacent to urbanized areas. Based on the analysis of the thermal band of Landsat TM at May 17, 1997, the thermal mitigation effect of open spaces in the city could be summarized as follows ; Kumho river showed the largest mitigation effect in terms of the width of mitigation zone and temperature difference. Evaporation from wide water surface and evapo-transpiration from riparian grass land could bring into results. Significant mitigation effect of parks covered with forest can be observed. The temperature range of such parks were between 19.05$^{\circ}C$ and 19.44$^{\circ}C$ However, the thermal mitigation effect of Dalsung park and Apsan park was insignificant. The small size and high percentage of hard paving of the former and the relative low density of the residential areas adjacent to the latter could be the main reason. In conclusion, the thermal mitigation effect in urban ope spaces could be detectedby the employment of thermal band data of Landsat TM and GIS buffering technique.

• Journal of Power Electronics
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• 제17권5호
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• pp.1186-1194
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• 2017

This paper proposes an improved low frequency Selective Harmonic Mitigation-PWM (SHM-PWM) technique. The proposed method mitigates the low order harmonics of the output voltage up to the $50^{th}$ harmonic well and satisfies the grid codes EN 50160 and CIGRE-WG 36-05. Using a modified criterion for the switching angles, the range of the modulation index for non-linear SHM equations is improved, without increasing the switching frequency of the CHB converter. Due to the low switching frequency of the CHB converter, mitigating the harmonics of the converter up to the $50^{th}$ order and finding a wider modulation index range, the size and cost of the passive filters can be significantly reduced with the proposed technique. Therefore, the proposed technique is more efficient than the conventional SHM-PWM. To verify the effectiveness of the proposed method, a 7-level Cascaded H-bridge (CHB) converter is utilized for the study. Simulation and experimental results confirm the validity of the above claims.

• Journal of Power Electronics
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• 제17권1호
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• pp.106-114
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• 2017

In this paper, the Selective Harmonic Mitigation-PWM (SHM-PWM) method is used in single-phase and three-phase Cascaded H-Bridge (CHB) inverters in order to fulfill different power quality standards such as EN 50160, CIGRE WG 36-05, IEC 61000-3-6 and IEC 61000-2-12. Non-equal DC link voltages are used to increase the degrees of freedom for the proposed SHM-PWM technique. In addition, it will be shown that the obtained solutions become continuous and without sudden changes. As a result, the look-up tables can be significantly reduced. The proposed three-phase modulation method can mitigate up to the 50th harmonic from the output voltage, while each switch has just one switching in a fundamental period. In other words, the switching frequency of the power switches are limited to 50 Hz, which is the lowest switching frequency that can be achieved in the multilevel converters, when the optimal selective harmonic mitigation method is employed. In single-phase mode, the proposed method can successfully mitigate harmonics up to the 50th, where the switching frequency is 150 Hz. Finally, the validity of the proposed method is verified by simulations and experiments on a 9-level CHB inverter.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.482-484
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• 2005

• 한국방재학회 논문집
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• 제9권6호
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• pp.57-68
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• 2009

최근 인적재난 발생의 불확실성에 대한 유연한 대처를 위해 확률 통계적 재난위험성 평가 및 위험관리 기술에 대한 필요성이 고조되고 있어 관련기술을 인적재난에 적용하기 위한 연구를 수행하였다. 먼저 재난위험성 평가 기법의 실효성, 경제성 및 지속가능한 시스템 구현을 위한 선제조건을 검토하였다. 이로부터 재난의 피해규모-발생확률 분포함수의 이론적 검토를 통해 확률 통계적인 재난위험 지표를 도출하고 재난안전(위험)도 평가에 활용함으로서 보다 간편한 정량적 재난위험도 평가기법을 개발하였기에 이를 소개한다. 또한 이를 활용하여 우리나라와 일본의 확률 통계적인 화재 안전유지 성능을 비교 분석하고 그 결과를 안전지수로 제시하였다. 향후 기존의 재난위험 평가기술과 융화 발전시켜 국내실정에 맞는 미래 재난 추정 및 예측 모델의 최적화 방안을 마련함으로써 지속적인 위험도 분석결과에 기반을 둔 합리적인 통합재난관리 방안 마련이 가능 할 것으로 기대된다.