• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
• /
• pp.125-130
• /
• 2005

This paper suggests an efficient method of protection ratio calculation and shows some calculated results applicable to frequency coordination in microwave relay system networks, and the net filter discrimination (NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively, In addition, NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

• 한국병원경영학회지
• /
• 제14권2호
• /
• pp.60-74
• /
• 2009

This study purports to verify managerial effectiveness of the integrated delivery system(IDS) of Japanese health care institutions through comparing the managerial performance between hospital groups providing with both acute and nursing care and those with acute care only. Data on the managerial performance of 697 hospitals providing with nursing care together and 819 hospitals providing with acute care only were collected from Japanese Central Social Insurance Medical Councils 2001, 2003, 2005, and were analyzed using mean comparison test(t-test) between the two groups. The results revealed that there were significant differences between the two groups in such indicators as ratio of material cost, labor cost, depreciation rate, total margin, operating margin, average number of outpatient per day, average revenue of an inpatient per day, total amount of labor cost, gross revenue per employee, and labor productivity. However, we could not find out any consistent evidence which support the effect of integrated delivery system on the hospital managerial performance. Further discussion was made on the limitation of the study and future research agenda relevant to the topic.

• Nuclear Engineering and Technology
• /
• 제48권3호
• /
• pp.684-701
• /
• 2016

The Gaussian process model (GPM) is a flexible surrogate model that can be used for nonparametric regression for multivariate problems. A unique feature of the GPM is that a prediction variance is automatically provided with the regression function. In this paper, we estimate the safety margin of a nuclear power plant by performing regression on the output of best-estimate simulations of a large-break loss-of-coolant accident with sampling of safety system configuration, sequence timing, technical specifications, and thermal hydraulic parameter uncertainties. The key aspect of our approach is that the GPM regression is only performed on the dominant input variables, the safety injection flow rate and the delay time for AC powered pumps to start representing sequence timing uncertainty, providing a predictive model for the peak clad temperature during a reflood phase. Other uncertainties are interpreted as contributors to the measurement noise of the code output and are implicitly treated in the GPM in the noise variance term, providing local uncertainty bounds for the peak clad temperature. We discuss the applicability of the foregoing method to reduce the use of conservative assumptions in best estimate plus uncertainty (BEPU) and Level 1 probabilistic safety assessment (PSA) success criteria definitions while dealing with a large number of uncertainties.

• 대한기계학회논문집A
• /
• 제29권1호
• /
• pp.107-114
• /
• 2005

In order to analyze the elastic-plastic fracture behavior of a structure, the fracture resistance curve of the material should be known first. The standard CT specimen was used to obtain the fracture resistance curves of a piping system. However, it is known that the fracture resistance curve by the standard CT specimen is very conservative to evaluate the integrity of a structure. Also the fracture resistance curve is effected by the specimen geometry and the dimensions because of the constraint effect. The objective of this paper is to be certain the conservativeness of the fracture resistance curve by the standard CT specimen and to provide an additional safety margin. For these, the fracture tests using a real pipe specimen and the standard CT specimen test were performed. A 4-point bending jig was manufactured for the pipe test and the direct current potential drop method was used to measure the crack extension and the length for the pipe test. Also finite element analyses were performed with a CT specimen and a pipe in order to prove the additional safety margin. From the result of tests and analyses of the pipe and the standard CT specimen, it was observed that the fracture analysis with the standard CT specimen is conservative and the additional safety margin was proved.

• 한국콘텐츠학회논문지
• /
• 제14권1호
• /
• pp.318-325
• /
• 2014

본 연구는 국세청에서 공시한 2012년도 공공의료원의 손익계산서 분석을 통해 이익 측면에서의 공공의료원의 경영 분석에 대해 살펴보고자 한 것이다. 국세청에 공시된 2012년 공공의료원의 재무제표 총 38건의 손익계산서 중 중복된 자료를 제외하고 매출액, 매출원가, 판매비와 관리비의 구분 표기가 가능한 자료를 추출하여 최종 22건의 자료를 이용하였다. 분석에는 의료이익, 공헌이익, 매출액 추세를 이용하였다. 공공의료원의 의료이익을 분석한 결과 22개 공공의료원의 평균 의료이익은 손실로 -4,678.9백만 원이었고, 평균공헌이익은 12,572.5백만 원, 매출이 증가한 의료원의 평균 매출 증가액은 1,299.1백만 원이었다. 결과적으로 공공의료원의 의료이익은 손실이나 공헌이익이 발생하고 있고, 아울러 약 2/3의 의료원에서 매출액 증가 추이를 보이는 바 개별 의료원 차원만을 고려한 경영 의사결정 시에는 신중한 접근이 필요하며, 공공의료원이 전국에 지역별 거점 기관의 성격으로 개설되어 있는 국가 공공의료망의 일부라는 측면에서 전사적 차원, 즉 국가적 차원에서의 경영분석과 판단이 이루어져야 함을 제안한다.

• 한국추진공학회지
• /
• 제18권3호
• /
• pp.8-16
• /
• 2014

본 논문은 옆미끄럼각에 따른 초음속 흡입구 버즈마진의 영향도에 대해 분석하였다. 버즈마진은 비행체 종축면에서 획득한 측정 물리량 기반으로 제어 명령을 산출하는 제어기에 의해 안정화 된다고 가정하였다. 해당 분석은 3차원 CFD를 통해 획득한 결과를 기반으로 수행되었으며, 3차원 CFD 해석 데이터는 종축면의 센서 측정 물리량을 모사하기 위해 사용되었다. 종축면 측정치 기반의 제어시스템에서는 기대하지 않은 횡방향 유동 섭동이 총 받음각의 증가의 결과로 나타나며, 이는 엔진 흡입구 성능의 감소를 의미한다. 결과적으로, 제어 안정성 또한 줄어들게 되어 보다 큰 제어 마진이 요구됨을 확인할 수 있었다.

• Journal of electromagnetic engineering and science
• /
• 제6권2호
• /
• pp.103-109
• /
• 2006

This paper suggests an efficient and comprehensive algorithm of the protection ratio derivation and illustrates some calculated results applicable to the initial planning of frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current microwave frequency band of 6.7 GHz including Tx spectrum mask and Rx filter response. According to results, fade margin and co-channel protection ratio reveal 41.4 and 75.2 dB, respectively, for 64-QAM and 60 km at BER $10^{-6}$. It is shown that the net filter discrimination with 40 MHz channel bandwidth provides 28.9 dB at the first adjacent channel, which yields 46.3 dB of adjacent channel protection ratio. In addition, the protection ratio of 38 GHz radio relay system is also reviewed for millimeter wave band applications. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also applied to frequency coordination in fixed millimeter wave networks.

• 전자공학회논문지S
• /
• 제36S권6호
• /
• pp.30-36
• /
• 1999

군 위성통신 체계는 재밍환경을 고려하여 설계되어야 한다. 재밍에 대한 대책으로 위성통신에 직접확산 부호분할 다중접속 방식(DS-CDMA)을 사용시 다중톤 재밍 환경에서 링크용량과 재밍마진을 분석하였다. 위성은 정지궤도에 위치한 위성으로 역확산/재확산방식 중계기를 사용하는 경우와 변복조 및 오류수정까지 하는 경우를 고려하여 각각 링크용량과 재밍마진을 계산하였다. 중계기에서 변복조 및 오류수정까지 하는 경우는 역확산/재확산만 하는 경우보다 용량이 2배이상 증가되는 것으로 나타났다.

• 전기학회논문지P
• /
• 제66권1호
• /
• pp.7-14
• /
• 2017

Recently, the power consumption of industrial consumer has increased rapidly, causing problems such as lack of power reserve margin in summer and winter, and therefore there is a growing need for maximum demand power management to consumers. In this paper, we studied small microgrid system consisting of battery ESS and photovoltaic power system, applied to small and medium sized factories to reduce the maximum demand power of daily industrial power load. To verify the validity of the study, we simulated a small microgrid system using Matlab/Simulink software. As a result of applying the simulation to small and medium sized plants that consume a lot of power, it is confirmed that there is a 13% reduction in demand compared to the existing maximum demand power. This result is expected to contribute to the improvement of the power reserve margin.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.129-130
• /
• 2007

Self servo track writing(SSTW)은 servo track writer(STW)를 이용하지 않고 hard disk drive의 내부 VCM을 이용하여 servo track을 기록하는 방식이다. SSTW는 이전 servo track을 상대적인 reference로 하여 기록하게 되므로 초기에 발생된 error와 외부의 disturbance의 영향으로 error는 급속하게 증가된다. 이것을 radial error propagation 이라 한다. 본 논문에서는 radial error propagation을 억제하기 위한 correction signal을 설계하고 servo writing 과정에서 발생하는 disturbance의 영향을 제거하기 위하여 disturbance observer(DOB)를 add-on type으로 구성하여 tracking 제어기를 설계하였다. 또한 DOB를 적용한 경우와 유사한 gain margin, phase margin과 sensitivity function을 갖는 제어기를 설계하여 그 성능을 비교하였다. 제안된 방식은 radial error propagation을 억제 하였을 뿐만 아니라 disturbance의 최소화하여 쓰여진 track의 DC track spacing과 AC track Squeeze가 개선된 것을 모의실험을 통하여 검증하였다.