• 소음진동
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• 제9권2호
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• pp.295-301
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• 1999

A Simplified Finite Element Method(FEM) model has been developed for the Exhaust System. For the verification of the usage of the developed model. Natural Frequencies, Mode Shapes and Frequency Response Function have been compared between numerical analysis and experimental result. It shows that the developed numerical model also can be utilized to prove the Stress distribution of the Exhaust System if it can be adopted for the vibration analysis adequately.

• International journal of advanced smart convergence
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• 제10권4호
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• pp.45-51
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• 2021

Polar transmitter can support multi-band and multi-mode operation. The efficiency of frequency usage can be increased if polar transmitters can transmit multi-carrier signals. In this paper the configuration of polar transmitters is investigated to generate multi-carrier signals. Spectrum and CCDF Simulation results of two-carrier signals generated by the polar transmitter can be used to design of PM and AM path in a polar transmitter.

• Journal of Radiation Protection and Research
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• 제39권3호
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• pp.142-149
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• 2014

한국은 국가건강검진을 시행하여 국민건강증진에 크게 기여하고 있으며 그 수검률 또한 증가하고 있다. 본 연구는 수검률 증가에 따른 방사선검사의 증가가 예상되어 그 이용 빈도(이용량)와 피폭선량을 파악하고자 한다. 본 연구는 2011년 국민건강보험공단 건강검진 분석 자료에서 방사선검사를 분리하여 이용량을 파악하고, UNSCEAR 2008년 보고서의 수록되어 있는 검사별 선량을 적용하여 국가건강검진에서 방사선검사로 인한 피폭선량을 추정한다. 주요 분석결과 2011년 국가건강검진 수검자 1인당 평균 피폭선량은 0.57 mSv로 추정되었고, 최대 11.081 mSv, 최소 0.02 mSv로 추정되었다. 방사선검사의 이용 빈도와 피폭선량은 각각 총 16,005,914건, 6,311.76 person-Sv로, 이중 이용량은 흉부 X선검사가 1,070,569 (69.17%)건으로 가장 높았고, 피폭선량은 위장조영검사가 5,217.94 (82.67%) person-Sv로 가장 높았다. 성 연령별 결과 39세 이하를 제외한 전 연령대에서 여성의 수검비율과 피폭선량이 높았고, 특히 50-54세 여성이 1,674,787 (10.5%)건, 701.59 (11.1%) person-Sv로 가장 높았다. 검사별 선량에서 위장조영검사가 전체 82.67%를 차지하는 만큼 의료상(목적) 반드시 시행하는 경우를 제외하고는 위장내시경검사를 선택하여 수검 받도록 정책적으로 장려하고 외국의 사례와 같이 경제성과 실효성 평가에 따라 폐지된다면 국가건강검진에의 방사선피폭은 현저히 줄어들 것으로 예상한다.

• Journal of Information Technology Applications and Management
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• 제21권4_spc호
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• pp.449-462
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• 2014

As mobile traffic is growing, the demand for spectrum is increasing but the deficiency of spectrum becomes serious as the supply is restricted essentially. For resolving the issue, spectrum sharing system is discussed from the technical and regulatory point of view, where multiple radio users occupy same frequency. In this paper, the policies and adoptions of spectrum sharing system in some countries are analyzed with a focus on TV white space and licensed shared access, which are based on unlicensed and licensed spectrum usage respectively. Some legal and regulatory plans to adopt and activate spectrum sharing in the Radio Waves Act system of Korea are proposed as well.

• ETRI Journal
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• 제37권2호
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• pp.273-282
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• 2015

Vehicle-to-grid presents a mechanism to meet the key requirements of an electric power system, using electric vehicles (EVs) when they are parked. The most economic ancillary service is that of frequency regulation, which imposes some constraints regarding the period and duration of time the vehicles have to be connected to the grid. The majority of research explores the profitability of the aggregator, while the perspective of the EV fleet owner, in terms of their need for usage of their fleet, remains neglected. In this paper, the optimal allocation of available vehicles on a day-ahead basis using queuing theory and fuzzy multi-criteria methodology has been determined. The proposed methodology is illustrated on the daily scheduling of EVs in an electricity distribution company.

• 천문학논총
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• 제15권1호
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• pp.35-60
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• 2000

We have analyzed the frequency sharing in the range of 71-275 GHz, which was adopted as a main topic of the WARC-2000 at the previous conference WARC-97. Though the technology of the active services has not been fully developed in this frequncy range, the heavy usage of this technology is expected in foreseeable future. To protect the passive services from spurious and out-of-band emissions of active services, realignment of the spectrum between 71 GHz and 275 GHz is strongly required. In addition, some effort should be made to allocate special bands for the radio astronomy service.

• 대한한의학회지
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• 제30권3호
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• pp.111-118
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• 2009

Hysterectomy can lead to various symptoms threatening decent quality of life. As the frequency of hysterectomy increases, there are many patients who want to take oriental medicine treatments for complications. Several clinical studies have reported the effectiveness of oriental medicine treatment for post-hysterectomy complications. Out of these symptoms, postoperative nausea and vomiting (PONV, hereafter) are indicated at about 20-40% of frequency within patients with general anesthesia, and they may occur not only during recovery from operation, but also after discharge. Although the incidence of PONV has decreased now thanks to the usage of antiemetics, PONV still causes some difficulties for patients returning to daily life. This study reports two cases of post-hysterectomy complications such as nausea, dizziness, vomiting, general weakness, and coldness of the limbs, which had good responses to herbal medication and acupuncture.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.306-313
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• 2000

The homogenization method and the density function method are common approaches to evaluate the equivalent material properties for design cells composed of matter and void. In this research, using a new topology optimization method based on the homogenized material with a penalty factor and the chessboard prevention strategy, we obtain the optimal layout of a structure for the natural frequency of a designated mode. The volume fraction of nodes of each finite element is chosen as the design variable and a total material usage constraint is imposed. In this paper, the subspace method is used to evaluate the eigenvalue and its corresponding eigenvector of the structure for the designated mode and the recursive quadratic programming algorithm, PLBA algorithm, is used to solve the topology optimization problem.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.110-120
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• 1999

Topology optimization is used for determining the best layout of structural components to achieve predetermined performance goals. In the present study, we consider that the objective function is to maximize the natural frequency of the structure for a designated mode and the constraint function is to constrain a total material usage. In this paper, using a topology optimization technique based on the homogenized material and the chessboard prevention strategy, we obtain the optimal layout and the reinforcement of an elastic structure. Several examples are presented to show the ability of the topology optimization technique used in this paper to deal with an optimal layout problem for a free vibration structure.

• 대한한의진단학회지
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• 제21권1호
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• pp.1-12
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• 2017

Objectives Some major Chinese medical classics like Huangdineijing (黃帝內經) and Nanjing (難經) assert that a normal person breaths 13,500 times every day. It's just half of real breathing cycles of human. So I tried to find a reasonable explanation to solve this conflict between truth and literal description. Materials and methods To find breath count descriptions in Chinese ancient books, I used Kanseki Repository (http://kanripo.org/). To find precedent research on this topic, I used China National Knowledge Infrastructure (http://cnki.net). Results 33 books refers to human breath cycles for a day, and most of them introduce 13,500 as human breathing frequency of one day. Some recent papers on Laoguanshan (老官山) Western Han dynasty manuscripts show new clues on this topic. Conclusion I assume that 13,500 cycles, the incorrect human breathing frequency of a day, might be originated from adjusting the meaning and usage of the word "Xi (息)".